KINDAI UNIVERSITY


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TAKEDA Tomoya

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FacultyDepartment of Pharmacy
PositionAssistant Professor
Degree
Commentator Guidehttps://www.kindai.ac.jp/meikan/1238-takeda-tomoya.html
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Last Updated :2020/08/10

Education and Career

Education

  •   2009 04  - 2011 03 , Kobe University, Graduate School of Medicine

Academic & Professional Experience

  •   2018 04 ,  - 現在, Faculty of Pharmacy, Kindai University
  •   2014 04 ,  - 2018 03 , Research Associate, Faculty of Pharmacy, Kinki University

Research Activities

Research Areas

  • Life sciences, Pharmacology

Research Interests

  • cancer

Published Papers

  • Overactivation of Akt Contributes to MEK Inhibitor Primary and Acquired Resistance in Colorectal Cancer Cells., Tsubaki M, Takeda T, Noguchi M, Jinushi M, Seki S, Morii Y, Shimomura K, Imano M, Satou T, Nishida S, Cancers, Cancers, 11(12), Nov. 2019 , Refereed
  • Inhibition of HSP90 overcomes melphalan resistance through downregulation of Src in multiple myeloma cells., Tabata M, Tsubaki M, Takeda T, Tateishi K, Maekawa S, Tsurushima K, Imano M, Satou T, Ishizaka T, Nishida S, Clinical and experimental medicine, Clinical and experimental medicine, Oct. 2019 , Refereed
  • Combination therapy with dacarbazine and statins improved the survival rate in mice with metastatic melanoma., Tsubaki M, Takeda T, Obata N, Kawashima K, Tabata M, Imano M, Satou T, Nishida S, Journal of cellular physiology, Journal of cellular physiology, 234(10), 17975 - 17989, Aug. 2019 , Refereed
  • RANKL-induced c-Src activation contributes to conventional anti-cancer drug resistance and dasatinib overcomes this resistance in RANK-expressing multiple myeloma cells., Mashimo K, Tsubaki M, Takeda T, Asano R, Jinushi M, Imano M, Satou T, Sakaguchi K, Nishida S, Clinical and experimental medicine, Clinical and experimental medicine, 19(1), 133 - 141, Oct. 2018 , Refereed
  • Overexpression of HIF-1α contributes to melphalan resistance in multiple myeloma cells by activation of ERK1/2, Akt, and NF-κB., Tsubaki M, Takeda T, Tomonari Y, Koumoto YI, Imano M, Satou T, Nishida S, Laboratory investigation; a journal of technical methods and pathology, Laboratory investigation; a journal of technical methods and pathology, 99(1), 72 - 84, Oct. 2018 , Refereed
  • Tamoxifen suppresses paclitaxel-, vincristine-, and bortezomib-induced neuropathy via inhibition of the protein kinase C/extracellular signal-regulated kinase pathway., Tsubaki M, Takeda T, Matsumoto M, Kato N, Yasuhara S, Koumoto YI, Imano M, Satou T, Nishida S, Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine, Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine, 40(10), 1010428318808670, Oct. 2018 , Refereed
  • The MIP-1α autocrine loop contributes to decreased sensitivity to anticancer drugs., Masanobu Tsubaki, Tomoya Takeda, Yoshika Tomonari, Kenji Mashimo, Yu-Ichi Koumoto, Sachi Hoshida, Tatsuki Itoh, Motohiro Imano, Takao Satou, Katsuhiko Sakaguchi, Shozo Nishida, Journal of cellular physiology, Journal of cellular physiology, 233(5), 4258 - 4271, May 2018 , Refereed
    Summary:Several autocrine soluble factors, including macrophage inflammatory protein-1α (MIP-1α), tumor necrosis factor-α, and hepatocyte growth factor, promote cell survival and growth in multiple myeloma (MM) cells. We hypothesized that inhibition of the MIP-1α autocrine loop may enhance the cytotoxic effect of anticancer drugs in MM cell lines. In the present study, an MIP-1α neutralizing antibody suppressed cell proliferation and enhanced the cytotoxic effect of melphalan or bortezomib on MM cells. In addition, melphalan resistance cells (RPMI8226/L-PAM and HS-sultan/L-PAM cells) secreted MIP-1α and neutralizing antibody of MIP-1α partially overcame melphalan resistance. Moreover, combination treatment with MIP-1α neutralizing antibody and melphalan or bortezomib inhibited extracellular signal regulated kinase 1/2 (ERK1/2), Akt, and mammalian target of rapamycin (mTOR) activation, Bcl-2, Bcl-xL, and Survivin expression, and upregulated the expression of Bim and cleaved Poly (ADP-ribose) polymerase (PARP). Treatment of IM9 cells with MIP-1α siRNA suppressed the activation of ERK1/2, Akt, and mTOR, and enhanced the cytotoxic effect of melphalan and bortezomib. These results indicate that MIP-1α neutralizing antibodies or MIP-1α siRNA enhance the cytotoxic effect of melphalan and bortezomib by suppressing the chemokine receptor/ERK and chemokine receptor/Akt/mTOR pathways. The inhibition of MIP-1α may thus provide a new therapeutic approach to control tumor progression and bone destruction in patients with MM.
  • Pioglitazone inhibits cancer cell growth through STAT3 inhibition and enhanced AIF expression via a PPARγ-independent pathway., Masanobu Tsubaki, Tomoya Takeda, Yoshika Tomonari, Keishi Kawashima, Tatsuki Itoh, Motohiro Imano, Takao Satou, Shozo Nishida, Journal of cellular physiology, Journal of cellular physiology, 233(4), 3638 - 3647, Apr. 2018 , Refereed
    Summary:Pioglitazone is an anti-diabetic agent that belongs to the thiazolidinedione class, which target peroxisome proliferator-activated receptor γ (PPARγ), a transcription factor in the nuclear receptor family. Different cancer cells expressing high levels of PPARγ and PPARγ ligands induce cell cycle arrest, cell differentiation, and apoptosis. However, the mechanisms underlying these processes remain unknown. Here, we investigated the mechanism underlying pioglitazone-induced apoptosis in human cancer cells. We showed that at similar concentrations, pioglitazone induced death in cancer cells expressing high or low levels of PPARγ. Combined treatment of pioglitazone and GW9662, a PPARγ antagonist, did not rescue this cell death phenotype. Z-VAD-fmk, a pan-caspase inhibitor, did not reverse pioglitazone-induced apoptosis in cancer cells expressing PPARγ at high or low levels. Pioglitazone suppressed the activation of signal transducers and activator of transcription 3 (STAT3) and Survivin expression, and enhanced the apoptosis-inducing factor (AIF) levels in these cells. Furthermore, pioglitazone enhanced the cytotoxic effect of cisplatin and oxaliplatin by suppressing Survivin and increasing AIF expression. These results indicated that pioglitazone induced apoptosis via a PPARγ-independent pathway, thus describing pioglitazone as a potential therapeutic agent for controlling the progression of different cancers.
  • Trametinib suppresses chemotherapy-induced cold and mechanical allodynia via inhibition of extracellular-regulated protein kinase 1/2 activation., Tsubaki M, Takeda T, Matsumoto M, Kato N, Asano RT, Imano M, Satou T, Nishida S, American journal of cancer research, American journal of cancer research, 8(7), 1239 - 1248, 2018 , Refereed
  • Statins induce apoptosis through inhibition of Ras signaling pathways and enhancement of Bim and p27 expression in human hematopoietic tumor cells., Fujiwara D, Tsubaki M, Takeda T, Tomonari Y, Koumoto YI, Sakaguchi K, Nishida S, Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine, Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine, 39(10), 1010428317734947, Oct. 2017 , Refereed
  • [Influence of Next-Day Administration of Pegfilgrastim after FEC100 Chemotherapy in Japanese with Breast Cancer on Neutrophil Count]., Fujiwara D, Mashimo K, Kimura K, Noda A, Taki K, Yoshibayashi H, Takeda T, Tsubaki M, Nishida S, Sakaguchi K, Gan to kagaku ryoho. Cancer & chemotherapy, Gan to kagaku ryoho. Cancer & chemotherapy, 44(2), 149 - 152, Feb. 2017 , Refereed
  • Mangiferin enhances the sensitivity of human multiple myeloma cells to anticancer drugs through suppression of the nuclear factor κB pathway., Tomoya Takeda, Masanobu Tsubaki, Toshiki Kino, Ayako Kawamura, Shota Isoyama, Tatsuki Itoh, Motohiro Imano, Genzoh Tanabe, Osamu Muraoka, Hideaki Matsuda, Takao Satou, Shozo Nishida, International journal of oncology, International journal of oncology, 48(6), 2704 - 12, Jun. 2016 , Refereed
    Summary:Multiple myeloma (MM) is still an incurable hematological malignancy with a 5-year survival rate of ~35%, despite the use of various treatment options. The nuclear factor κB (NF-κB) pathway plays a crucial role in the pathogenesis of MM. Thus, inhibition of the NF-κB pathway is a potential target for the treatment of MM. In a previous study, we showed that mangiferin suppressed the nuclear translocation of NF-κB. However, the treatment of MM involves a combination of two or three drugs. In this study, we examined the effect of the combination of mangiferin and conventional anticancer drugs in an MM cell line. We showed that the combination of mangiferin and an anticancer drug decreased the viability of MM cell lines in comparison with each drug used separately. The decrease in the combination of mangiferin and an anticancer drug induced cell viability was attributed to increase the expression of p53 and Noxa and decreases the expression of XIAP, survivin, and Bcl-xL proteins via inhibition of NF-κB pathway. In addition, the combination treatment caused the induction of apoptosis, activation of caspase-3 and the accumulation of the cells in the sub-G1 phase of the cell cycle. Our findings suggest that the combination of mangiferin and an anticancer drug could be used as a new regime for the treatment of MM.
  • Statins inhibited the MIP-1α expression via inhibition of Ras/ERK and Ras/Akt pathways in myeloma cells., Masanobu Tsubaki, Kenji Mashimo, Tomoya Takeda, Toshiki Kino, Arisa Fujita, Tatsuki Itoh, Motohiro Imano, Katsuhiko Sakaguchi, Takao Satou, Shozo Nishida, Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie, Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie, 78, 23 - 29, Mar. 2016 , Refereed
    Summary:Macrophage inflammatory protein-1alpha (MIP-1α) is detected at high concentrations in patients with multiple myeloma. It is thought to play an important role in the etiology of multiple myeloma and osteolysis. Thus, inhibiting MIP-1α expression may be useful in developing therapeutic treatments for multiple myeloma-induced osteolysis. In this study, we investigated the potential of statins to inhibit mRNA expression and secretion of MIP-1α in mouse myeloma cells (MOPC-31C). We found that statins inhibited the lipopolysaccharide (LPS)-induced MIP-1α mRNA expression and protein secretion in MOPC-31C cells. This inhibition was reversed when farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate (GGPP), intermediates of the mevalonate pathway, were combined with statins. Furthermore, statins reduced the GTP form of Ras, a phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2), and phosphorylated Akt. Our results indicate that statins inhibit biosynthesis of FPP and GGPP and thereby down regulate signal transduction of Ras/ERK and Ras/Akt pathways. The net effect suppresses LPS-induced MIP-1α mRNA expression and protein secretion in MOPC-31C cells. Thus, statins hold great promise for developing effective therapies against myeloma-induced osteolysis.
  • Overexpression of survivin via activation of ERK1/2, Akt, and NF-kappa B plays a central role in vincristine resistance in multiple myeloma cells, Masanobu Tsubaki, Tomoya Takeda, Naoki Ogawa, Kotaro Sakamoto, Hirotaka Shimaoka, Arisa Fujita, Tatsuki Itoh, Motohiro Imano, Toshihiko Ishizaka, Takao Satou, Shozo Nishida, LEUKEMIA RESEARCH, LEUKEMIA RESEARCH, 39(4), 445 - 452, Apr. 2015 , Refereed
    Summary:The acquisition of anti-cancer drug resistance is a major limitation of chemotherapy for multiple myeloma(MM) and it is thus important to identify the mechanisms by which MM cells develop such drug resistance. In a previous study, we showed that multidrug resistance (MDR) involves the overexpression of MDR1 and survivin in vincristine-resistant RPMI8226/VCR cells. However, the underlying mechanism of MDR remains unclear. In this study, we investigated the mechanism of MDR in RPMI8226/VCR cells, and found that RPMI8226/VCR cells exhibit increased levels of activated ERK1/2, Akt, and NF-kappa B, while the levels of activated mTOR, p38MAPK, and JNK do not differ between RPMI8226/VCR cells and their vincristine-susceptible counterparts. In addition, the inhibition of ERK1/2, Akt, or NF-kappa B by inhibitors reversed thedrug resistance of RPMI8226/VCR cells via the suppression of survivin expression, but did not affect MDR1 expression; RNA silencing of survivin expression completely reversed vincristine resistance, while MDR1 silencing only weakly suppressed vincristine resistance in RPMI8226/VCR cells. These results indicate that enhanced survivin expression via the activation of ERK1/2, Akt, and NF-kappa B plays a critical role in vincristine resistance in RPMI8226/VCR cells. Our findings suggest that ERK1/2, Akt, and NF-kappa B inhibitors are potentially useful as anti-MDR agents for the treatment of vincristine-resistant MM. (C) 2015 Elsevier Ltd. All rights reserved.
  • Mangiferin suppresses CIA by suppressing the expression of TNF-α, IL-6, IL-1β, and RANKL through inhibiting the activation of NF-κB and ERK1/2., Masanobu Tsubaki, Tomoya Takeda, Toshiki Kino, Tatsuki Itoh, Motohiro Imano, Genzo Tanabe, Osamu Muraoka, Takao Satou, Shozo Nishida, American journal of translational research, American journal of translational research, 7(8), 1371 - 81, 2015 , Refereed
    Summary:Rheumatoid arthritis is a systemic autoimmune disease characterized by chronic inflammation of synovial joints, ultimately leading to a progressive and irreversible joint destruction. Activation of nuclear factor-kappa B (NF-κB) promotes production of proinflammatory cytokines in various inflammatory diseases including rheumatoid arthritis. Mangiferin, 1,3,6,7-tetrahydroxyxanthone-C2-β-D-glucoside (C-glucosyl xanthone), is a naturally occurring polyphenol. Our previous results showed that mangiferin suppressed NF-κB activation. However, it is unclear, whether mangiferin can prevent rheumatoid arthritis through suppression of NF-κB activation and expression of various cytokines, such as tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6), which play a critical role in the pathogenesis of rheumatoid arthritis. In the present study, we found that mangiferin suppressed the progression and incidence of CIA in DBA1/J mice. In CIA mice, mangiferin inhibited the mRNA expression of cytokine genes in thymus and spleen of CIA mie and led to decreased serum levels of IL-1β, IL-6, TNF-α, and receptor activator NF-κB ligand (RANKL) via inhibition of NF-κB and activation of extracellular signal-regulated kinase 1/2 (ERK1/2). In addition, mangiferin markedly inhibited not only developing but also clinically evident CIA. These findings suggest that mangiferin has potential clinical applications for the treatment of rheumatoid arthritis.
  • Bisphosphonates and statins inhibit expression and secretion of MIP-1 alpha via suppression of Ras/MEK/ERK/AML-1A and Ras/PI3K/Akt/AML-1A pathways, Masanobu Tsubaki, Tomoya Takeda, Kotaro Sakamoto, Hirotaka Shimaoka, Arisa Fujita, Tatsuki Itoh, Motohiro Imano, Kenji Mashimo, Daiichiro Fujiwara, Katsuhiko Sakaguchi, Takao Satou, Shozo Nishida, AMERICAN JOURNAL OF CANCER RESEARCH, AMERICAN JOURNAL OF CANCER RESEARCH, 5(1), 168 - 179, 2015 , Refereed
    Summary:Osteolytic bone disease in multiple myeloma (MM) is associated with upregulated osteoclast activity. Macrophage inflammatory protein-1 alpha (MIP-1 alpha) is crucially involved in the development of osteolytic bone lesions in MM. We previously reported that minodronate inhibited lipopolysaccharide-induced MIP-1 alpha secretion in mouse myeloma cells. However, it remains unknown whether bisphosphonates and statins inhibit MIP-1 alpha secretion by human MM cells. In present study, we investigated whether bisphosphonates and statins had any inhibitory effect on MIP-1 alpha secretion by human myeloma cells and the mechanism underlying this effect. In this study, we found that bisphosphonates and statins inhibited MIP-1 alpha mRNA and MIP-1 alpha secretion and suppressed extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt phosphorylation by inhibiting Ras prenylation. Moreover, bisphosphonates and statins suppressed the expression of acute myeloid leukemia-1 alpha (AML-1A) mRNA, a MIP-1 alpha transcription factor. These results indicate that bisphosphonates and statins suppress the Ras/mitogen-activated protein kinase kinase/ERK/AML-1A and Ras/phosphatidylinositol-3 kinase/Akt/AML-1A pathways, thereby inhibiting MIP-1 alpha secretion by MM cells. Therefore, use of MIP-1 alpha expression inhibitors such as bisphosphonates and statins may provide a new therapeutic approach to inhibiting tumour progression and bone destruction in MM patients.
  • Dimethyl fumarate induces apoptosis of hematopoietic tumor cells via inhibition of NF-kappa B nuclear translocation and down-regulation of Bcl-xL and XIAP, Masanobu Tsubaki, Naoki Ogawa, Tomoya Takeda, Kotaro Sakamoto, Hirotaka Shimaoka, Arisa Fujita, Tatsuki Itoh, Motohiro Imano, Takao Satou, Shozo Nishida, BIOMEDICINE & PHARMACOTHERAPY, BIOMEDICINE & PHARMACOTHERAPY, 68(8), 999 - 1005, Oct. 2014 , Refereed
    Summary:Dimethyl fumarate (DMF) is a fumaric acid ester that is used to treat psoriasis and multiple sclerosis. Recently, DMF was found to exhibit anti-tumor effects. However, the molecular mechanisms underlying these effects have not been elucidated. In this study, we investigated the mechanism of DMF-induced apoptosis in different human hematopoietic tumor cell lines. We found that DMF induced apoptosis in different human hematopoietic tumor cell lines but it did not affect the normal human B lymphocyte cell line RPMI 1788. We also observed a concurrent increase in caspase-3 activity and in the number of Annexin-V-positive cells. Furthermore, an examination of the survival signals, which are activated by apoptotic stimuli, revealed that DMF significantly inhibited nuclear factor-kappa B (NF-kappa B) p65 nuclear translocation. In addition, DMF suppressed B-cell lymphoma extra-large (Bcl-xL) and X-linked inhibitor of apoptosis (XIAP) expression whereas Bcl-2, survivin, Bcl-2-associated X protein (Bax), and Bim levels did not change. These results indicated that DMF induced apoptosis by suppressing NF-kappa B activation, and Bcl-xL and XIAP expression. These findings suggested that DMF might have potential as an anticancer agent that could be used in combination therapy with other anticancer drugs for the treatment of human hematopoietic tumors. (C) 2014 Elsevier Masson SAS. All rights reserved.
  • Activation of NF-κB by the RANKL/RANK system up-regulates snail and twist expressions and induces epithelial-to-mesenchymal transition in mammary tumor cell lines., Tsubaki M, Komai M, Fujimoto S, Itoh T, Imano M, Sakamoto K, Shimaoka H, Takeda T, Ogawa N, Mashimo K, Fujiwara D, Mukai J, Sakaguchi K, Satou T, Nishida S, Journal of experimental & clinical cancer research : CR, Journal of experimental & clinical cancer research : CR, 32, 62, Sep. 2013 , Refereed
  • Akt2 regulates Rac1 activity in the insulin-dependent signaling pathway leading to GLUT4 translocation to the plasma membrane in skeletal muscle cells., Nozaki S, Takeda T, Kitaura T, Takenaka N, Kataoka T, Satoh T, Cellular signalling, Cellular signalling, 25(6), 1361 - 1371, Jun. 2013 , Refereed
  • Bavachin induces the apoptosis of multiple myeloma cell lines by inhibiting the activation of nuclear factor kappa B and signal transducer and activator of transcription 3., Tomoya Takeda, Masanobu Tsubaki, Yoshika Tomonari, Keishi Kawashima, Tatsuki Itoh, Motohiro Imano, Takao Satou, Shozo Nishida, Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie, Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie, 100, 486 - 494, Apr. 2018 , Refereed
    Summary:Bavachin is a phytoestrogen purified from natural herbal plants such as Psoralea corylifolia. In this study, we examined the effect of bavachin in multiple myeloma (MM) cell lines. We found that bavachin decreased the viability of MM cell lines, but was not cytotoxic towards normal cells. It inhibited the activation of nuclear factor kappa B (NF-κB) and signal transducer and activator of transcription 3 (STAT3). Furthermore, bavachin increased the expression of p53 and NOXA, and decreased the expression of X-linked inhibitor of apoptosis protein (XIAP), survivin, B cell lymphoma-extra large (Bcl-xL), and Bcl-2. Additionally, bavachin induced apoptosis by the activation of caspase-3 and caspase-9, implicating the involvement of the mitochondrial pathway. Our results suggest that bavachin induces apoptosis through the inhibition of NF-κB and STAT3 activation in MM cell lines. Most importantly, few NF-κB and STAT3 inhibitors with high efficiency, specificity, and safety are currently available for clinical cancer therapy. Hence, bavachin, which targets NF-κB and STAT3, is a potential anticancer agent for the treatment of MM.
  • Rebamipide suppresses 5-fluorouracil-induced cell death via the activation of Akt/mTOR pathway and regulates the expression of Bcl-2 family proteins., Masanobu Tsubaki, Tomoya Takeda, Ryo-Ta Asano, Tomoyuki Matsuda, Shin-Ichiro Fujimoto, Tatsuki Itoh, Motohiro Imano, Takao Satou, Shozo Nishida, Toxicology in vitro : an international journal published in association with BIBRA, Toxicology in vitro : an international journal published in association with BIBRA, 46, 284 - 293, Feb. 2018 , Refereed
    Summary:Oral mucositis is a common adverse effect of chemotherapy that limits the required dose of chemotherapeutic agents. Numerous attempts to mitigate chemotherapy-induced oral mucositis have failed to identify an appropriate treatment. Recently, it has been indicated that rebamipide prevents chemoradiotherapy-induced oral mucositis in patients. However, the details of the underlying mechanism involved in the cytoprotective effect of rebamipide remain obscure. In the present study, we investigated the mechanism behind rebamipide cytoprotective effect in the oral mucosa using primary normal human oral keratinocytes (NHOK cells). We found that rebamipide prevented 5-fluorouracil (5-FU)-induced cell death in NHOK cells. In addition, rebamipide increased the levels of phosphorylated Akt and mTOR, enhanced the Bcl-2 and Bcl-xL expressions, and suppressed the expression of Bax and Bim. This is in contrast to 5-FU-induced suppression of Akt and mTOR activation, Bcl-2 and Bcl-xL expressions, and the enhanced expression of Bax and Bim. These findings suggest that rebamipide can potentially be used for the protection of oral mucosa from chemotherapy-induced mucositis. This is the first study that elucidates the specific molecular pathway for the cytoprotective effect of rebamipide.
  • Contributions of MET activation to BCR-ABL1 tyrosine kinase inhibitor resistance in chronic myeloid leukemia cells., Masanobu Tsubaki, Tomoya Takeda, Toshiki Kino, Kazuko Sakai, Tatsuki Itoh, Motohiro Imano, Takashi Nakayama, Kazuto Nishio, Takao Satou, Shozo Nishida, Oncotarget, Oncotarget, 8(24), 38717 - 38730, Jun. 13 2017 , Refereed
    Summary:Resistance to the breakpoint cluster region-abelson 1 (BCR-ABL1) tyrosine kinase inhibitor (TKI) imatinib poses a major problem when treating chronic myeloid leukemia (CML). Imatinib resistance often results from a secondary mutation in BCR-ABL1. However, in the absence of a mutation in BCR-ABL1, the basis of BCR-ABL1-independent resistance must be elucidated. To gain insight into the mechanisms of BCR-ABL1-independent imatinib resistance, we performed an array-based comparative genomic hybridization. We identified various resistance-related genes, and focused on MET. Treatment with a MET inhibitor resensitized K562/IR cells to BCR-ABL1 TKIs. Combined treatment of K562/IR cells with imatinib and a MET inhibitor suppressed extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinase (JNK) activation, but did not affect AKT activation. Our findings implicate the MET/ERK and MET/JNK pathways in conferring resistance to imatinib, providing new insights into the mechanisms of BCR-ABL1 TKI resistance in CML.
  • The sensitivity of head and neck carcinoma cells to statins is related to the expression of their Ras expression status, and statin-induced apoptosis is mediated via suppression of the Ras/ERK and Ras/mTOR pathways., Masanobu Tsubaki, Daichiro Fujiwara, Tomoya Takeda, Toshiki Kino, Yoshika Tomonari, Tatsuki Itoh, Motohiro Imano, Takao Satou, Katsuhiko Sakaguchi, Shozo Nishida, Clinical and experimental pharmacology & physiology, Clinical and experimental pharmacology & physiology, 44(2), 222 - 234, Feb. 2017 , Refereed
    Summary:Statins induce apoptosis of tumour cells by inhibiting the prenylation of small G-proteins. However, the details of the apoptosis-inducing mechanisms remain poorly understood. The present study showed that the induction of apoptosis by statins in four different human head and neck squamous cell carcinoma (HNSCC) cell lines, HSC-3, HEp-2, Ca9-22, and SAS cells was mediated by increased caspase-3 activity. Statins induced apoptosis by the suppression of geranylgeranyl pyrophosphate biosynthesis. Furthermore, statins decreased the levels of phosphorylated ERK and mTOR by inhibiting the membrane localization of Ras and enhancing Bim expression in HSC-3 and HEp-2 cells. We also found that in all the cell types analyzed, the IC50 values for fluvastatin and simvastatin were highest in HEp-2 cells. In addition, HSC-3, Ca9-22, and SAS cells had higher Ras expression and membrane localization, higher activation of ERK1/2 and mTOR, and lower levels of Bim expression than HEp-2 cells. Our results indicate that statins induce apoptosis by increasing the activation of caspase-3 and by enhancing Bim expression through inhibition of the Ras/ERK and Ras/mTOR pathways. Furthermore, the sensitivity of HNSCC cells to statin treatment was closely related to Ras expression and prenylation levels, indicating that statins may act more effectively against tumours with high Ras expression and Ras-variability. Therefore, our findings support the use of statins as potential anticancer agents.
  • Mangiferin, a novel nuclear factor kappa B-inducing kinase inhibitor, suppresses metastasis and tumor growth in a mouse metastatic melanoma model., Tomoya Takeda, Masanobu Tsubaki, Kotaro Sakamoto, Eri Ichimura, Aya Enomoto, Yuri Suzuki, Tatsuki Itoh, Motohiro Imano, Genzoh Tanabe, Osamu Muraoka, Hideaki Matsuda, Takao Satou, Shozo Nishida, Toxicology and applied pharmacology, Toxicology and applied pharmacology, 306, 105 - 12, Sep. 01 2016 , Refereed
    Summary:Advanced metastatic melanoma, one of the most aggressive malignancies, is currently without reliable therapy. Therefore, new therapies are urgently needed. Mangiferin is a naturally occurring glucosylxanthone and exerts many beneficial biological activities. However, the effect of mangiferin on metastasis and tumor growth of metastatic melanoma remains unclear. In this study, we evaluated the effect of mangiferin on metastasis and tumor growth in a mouse metastatic melanoma model. We found that mangiferin inhibited spontaneous metastasis and tumor growth. Furthermore, mangiferin suppressed the nuclear translocation of nuclear factor kappa B (NF-κB) and expression of phosphorylated NF-κB-inducing kinase (NIK), inhibitor of kappa B kinase (IKK), and inhibitor of kappa B (IκB) and increases the expression of IκB protein in vivo. In addition, we found that mangiferin inhibited the expression of matrix metalloproteinases (MMPs) and very late antigens (VLAs) in vivo. Mangiferin treatment also increased the expression of cleaved caspase-3, cleaved Poly ADP ribose polymerase-1 (PARP-1), p53 upregulated modulator of apoptosis (PUMA), p53, and phosphorylated p53 proteins, and decreased the expression of Survivin and Bcl-associated X (Bcl-xL) proteins in vivo. These results indicate that mangiferin selectivity suppresses the NF-κB pathway via inhibition of NIK activation, thereby inhibiting metastasis and tumor growth. Importantly, the number of reported NIK selective inhibitors is limited. Taken together, our data suggest that mangiferin may be a potential therapeutic agent with a new mechanism of targeting NIK for the treatment of metastatic melanoma.
  • RANK-RANKL interactions are involved in cell adhesion-mediated drug resistance in multiple myeloma cell lines., Masanobu Tsubaki, Tomoya Takeda, Misako Yoshizumi, Emi Ueda, Tatsuki Itoh, Motohiro Imano, Takao Satou, Shozo Nishida, Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine, Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine, 37(7), 9099 - 110, Jul. 2016 , Refereed
    Summary:Interaction between multiple myeloma (MM) cells and the bone marrow microenvironment plays a critical role in MM pathogenesis and the development of drug resistance. Recently, it has been reported that MM cells express the receptor activator of nuclear factor-κB (NF-κB) (RANK). However, the role of the RANK/RANK ligand (RANKL) system in drug resistance remains unclear. In this study, we demonstrated a novel function of the RANK/RANKL system in promoting drug resistance in MM. We found that RANKL treatment induced drug resistance in RANK-expressing but not RANK-negative cell lines. RANKL stimulation of RANK-expressing cells increased multidrug resistance protein 1 (MDR1), breast cancer resistance protein (BCRP), and lung resistance protein 1 (LRP1) expression and decreased Bim expression through various signaling molecules. RNA silencing of Bim expression induced drug resistance, but the RANKL-mediated drug resistance could not be overcome through the RNA silencing of MDR1, BCRP, and LRP1 expression. These results indicate that the RANK/RANKL system induces chemoresistance through the activation of multiple signal transduction pathways and by decreasing Bim expression in RANK-positive MM cells. These findings may prove to be useful in the development of cell adhesion-mediated drug resistance inhibitors in RANK-positive MM cells.
  • Mangiferin induces apoptosis in multiple myeloma cell lines by suppressing the activation of nuclear factor kappa B-inducing kinase., Tomoya Takeda, Masanobu Tsubaki, Toshiki Kino, Misa Yamagishi, Megumi Iida, Tatsuki Itoh, Motohiro Imano, Genzoh Tanabe, Osamu Muraoka, Takao Satou, Shozo Nishida, Chemico-biological interactions, Chemico-biological interactions, 251, 26 - 33, May 05 2016 , Refereed
    Summary:Mangiferin is a naturally occurring glucosyl xanthone, which induces apoptosis in various cancer cells. However, the molecular mechanism underlying mangiferin-induced apoptosis has not been clarified thus far. Therefore, we examined the molecular mechanism underlying mangiferin-induced apoptosis in multiple myeloma (MM) cell lines. We found that mangiferin decreased the viability of MM cell lines in a concentration-dependent manner. We also observed an increased number of apoptotic cells, caspase-3 activation, and a decrease in the mitochondrial membrane potential. In addition, mangiferin inhibited the nuclear translocation of nuclear factor kappa B (NF-κB) and expression of phosphorylated inhibitor kappa B (IκB) and increased the expression of IκB protein, whereas no changes were observed in the phosphorylation levels of extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal protein kinase 1/2 (JNK1/2), and mammalian target of rapamycin (mTOR). The molecular mechanism responsible for mangiferin-induced inhibition of nuclear translocation of NF-κB was a decrease in the expression of phosphorylated NF-κB-inducing kinase (NIK). Moreover, mangiferin decreased the expression of X-linked inhibitor of apoptosis protein (XIAP), survivin, and Bcl-xL proteins. Knockdown of NIK expression showed results similar to those observed with mangiferin treatment. Our results suggest that mangiferin induces apoptosis through the inhibition of nuclear translocation of NF-κB by suppressing NIK activation in MM cell lines. Our results provide a new insight into the molecular mechanism of mangiferin-induced apoptosis. Importantly, since the number of reported NIK inhibitors is limited, mangiferin, which targets NIK, may be a potential anticancer agent for the treatment of MM.
  • PKC/MEK inhibitors suppress oxaliplatin- induced neuropathy and potentiate the antitumor effects, Masanobu Tsubaki, Tomoya Takeda, Tadahumi Tani, Hirotaka Shimaoka, Naohiro Suzuyama, Kotaro Sakamoto, Arisa Fujita, Naoki Ogawa, Tatsuki Itoh, Motohiro Imano, Yoshinori Funakami, Seiji Ichida, Takao Satou, Shozo Nishida, INTERNATIONAL JOURNAL OF CANCER, INTERNATIONAL JOURNAL OF CANCER, 137(1), 243 - 250, Jul. 2015 , Refereed
    Summary:Oxaliplatin is a key drug commonly used in colorectal cancer treatment. Despite high clinical efficacy, its therapeutic application is limited by common, dose-limiting occurrence of neuropathy. As usual symptomatic neuropathy treatments fail to improve the patients' condition, there is an urgent need to advance our understanding of the pathogenesis of neuropathy to propose effective therapy and ensure adequate pain management. Oxaliplatin-induced neuropathy was recently reported to be associated with protein kinase C (PKC) activation. It is unclear, however, whether PKC inhibition can prevent neuropathy. In our current studies, we found that a PKC inhibitor, tamoxifen, inhibited oxaliplatin-induced neuropathy via the PKC/extracellular signal-regulated kinase (ERK)/c-Fos pathway in lumbar spinal cords (lumbar segments 4-6). Additionally, tamoxifen was shown to act in synergy with oxaliplatin to inhibit growth in tumor cells-implanted mice. Moreover, mitogen-activated protein kinase kinase (MEK) 1/2 inhibitor, PD0325901, suppressed oxaliplatin-induced neuropathy and enhanced oxaliplatin efficacy. Our results indicate that oxaliplatin-induced neuropathy is associated with PKC/ERK/c-Fos pathway in lumbar spinal cord. Additionally, we demonstrate that disruption of this pathway by PKC and MEK inhibitors suppresses oxaliplatin-induced neuropathy, thereby suggesting that PKC and MEK inhibitors may be therapeutically useful in preventing oxaliplatin-induced neuropathy and could aid in combination antitumor pharmacotherapy.
  • Statins improve survival by inhibiting spontaneous metastasis and tumor growth in a mouse melanoma model., Masanobu Tsubaki, Tomoya Takeda, Toshiki Kino, Naoya Obata, Tatsuki Itoh, Motohiro Imano, Kenji Mashimo, Daichiro Fujiwara, Katsuhiko Sakaguchi, Takao Satou, Shozo Nishida, American journal of cancer research, American journal of cancer research, 5(10), 3186 - 97, 2015 , Refereed
    Summary:Metastatic melanoma is a life-threatening disease for which no effective treatment is currently available. In melanoma cells, Rho overexpression promotes invasion and metastasis. However, the effect of statins on spontaneous metastasis and tumor growth remains unclear. In the present study, we investigated the mechanism of statin-mediated tumor growth and metastasis inhibition in an in vivo model. We found that statins significantly inhibited spontaneous metastasis and tumor growth. Statins inhibited the mRNA expression and enzymatic activities of matrix metalloproteinases (MMPs) in vivo and also suppressed the mRNA and protein expression of very late antigens (VLAs). Moreover, statins inhibited the prenylation of Rho as well as the phosphorylation of LIM kinase, serum response factor (SRF), and c-Fos downstream of the Rho signaling pathway. In addition, statins enhanced p53, p21, and p27 expression and reduced phosphorylation of cyclin-dependent kinase and expression of cyclin D1 and E2. These results indicate that statins suppress Rho signaling pathways, thereby inhibiting tumor metastasis and growth. Furthermore, statins markedly improved the survival rate in a metastasis model, suggesting that statins have potential clinical applications for the treatment of metastatic cancers.
  • Nitrogen-containing bisphosphonates inhibit RANKL- and M-CSF-induced osteoclast formation through the inhibition of ERK1/2 and Akt activation, Masanobu Tsubaki, Makiko Komai, Tatsuki Itoh, Motohiro Imano, Kotaro Sakamoto, Hirotaka Shimaoka, Tomoya Takeda, Naoki Ogawa, Kenji Mashimo, Daiichiro Fujiwara, Junji Mukai, Katsuhiko Sakaguchi, Takao Satou, Shozo Nishida, JOURNAL OF BIOMEDICAL SCIENCE, JOURNAL OF BIOMEDICAL SCIENCE, 21, 10, Feb. 2014 , Refereed
    Summary:Background: Bisphosphonates are an important class of antiresorptive drugs used in the treatment of metabolic bone diseases. Recent studies have shown that nitrogen-containing bisphosphonates induced apoptosis in rabbit osteoclasts and prevented prenylated small GTPase. However, whether bisphosphonates inhibit osteoclast formation has not been determined. In the present study, we investigated the inhibitory effect of minodronate and alendronate on the osteoclast formation and clarified the mechanism involved in a mouse macrophage-like cell lines C7 and RAW264.7. Results: It was found that minodronate and alendronate inhibited the osteoclast formation of C7 cells induced by receptor activator of NF kB ligand and macrophage colony stimulating factor, which are inhibited by the suppression of geranylgeranyl pyrophosphate (GGPP) biosynthesis. It was also found that minodronate and alendronate inhibited the osteoclast formation of RAW264.7 cells induced by receptor activator of NF-kappa B ligand. Furthermore, minodronate and alendornate decreased phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt; similarly, U0126, a mitogen protein kinase kinase 1/2 (MEK1/2) inhibitor, and LY294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor, inhibited osteoclast formation. Conclusions: This indicates that minodronate and alendronate inhibit GGPP biosynthesis in the mevalonate pathway and then signal transduction in the MEK/ERK and PI3K/Akt pathways, thereby inhibiting osteoclast formation. These results suggest a novel effect of bisphosphonates that could be effective in the treatment of bone metabolic diseases, such as osteoporosis.
  • By inhibiting Sic, verapamil and dasatinib overcome multidrug resistance via increased expression of Bim and decreased expressions of MDR1 and survivin in human multidrug-resistant myeloma cells, Masanobu Tsubaki, Makiko Komai, Tatsuki Itoh, Motohiro Imano, Kotaro Sakamoto, Hirotaka Shimaoka, Tomoya Takeda, Naoki Ogawa, Kenji Mashimo, Daiichiro Fujiwara, Junji Mukai, Katsuhiko Sakaguchi, Takao Satou, Shozo Nishida, LEUKEMIA RESEARCH, LEUKEMIA RESEARCH, 38(1), 121 - 130, Jan. 2014 , Refereed
    Summary:The calcium channel blocker verapamil inhibits the transport function of multidrug resistance protein 1 (MDR1). Although verapamil acts to reverse MDR in cancer cells, the underlying mechanism remains unclear. In the present study, we investigated the mechanism of reversing MDR by verapamil in anticancer drug-resistant multiple myeloma (MM) cell lines. We found that verapamil suppresses MDR1 and survivin expressions and increases Bim expression via suppression of Src activation. Furthermore, dasatinib reversed the drug-resistance of the drug-resistant cell lines. These findings suggest that Src inhibitors are potentially useful as an anti-MDR agent for the treatment of malignant tumor cells. (C) 2013 Elsevier Ltd. All rights reserved.
  • Inhibition of the tumour necrosis factor-alpha autocrine loop enhances the sensitivity of multiple myeloma cells to anticancer drugs, Masanobu Tsubaki, Makiko Komai, Tatsuki Itoh, Motohiro Imano, Kotaro Sakamoto, Hirotaka Shimaoka, Naoki Ogawa, Kenji Mashimo, Daichiro Fujiwara, Tomoya Takeda, Junji Mukai, Katsuhiko Sakaguchi, Takao Satou, Shozo Nishida, EUROPEAN JOURNAL OF CANCER, EUROPEAN JOURNAL OF CANCER, 49(17), 3708 - 3717, Nov. 2013 , Refereed
    Summary:Several autocrine soluble factors, including macrophage inflammatory protein-1 alpha and tumour necrosis factor-alpha (TNF-alpha), promote the survival and growth of multiple myeloma (MM) cells. We hypothesised that inhibition of the TNF-alpha autocrine loop may enhance the cytotoxic effect of anticancer drugs in MM cell lines. In the present study, a TNF-alpha-neutralizing antibody suppressed cell proliferation and enhanced the cytotoxic effect of anticancer drugs onMMcells. In addition, combination treatment with the TNF-alpha-neutralizing antibody and the chemotherapy agent melphalan inhibited nuclear factor kappa B (NF-kappa B) p65 nuclear translocation and mammalian target of rapamycin (mTOR) activation and upregulated the expression of Bax and Bim. Treatment of ARH-77 cells with the NF-kappa B inhibitor dimethyl fumarate or the mTOR inhibitor rapamycin suppressed NF-kappa B p65 nuclear translocation and enhanced the cytotoxic effect of melphalan. Furthermore, infliximab, a monoclonal antibody against TNF-alpha, also enhanced the cytotoxic effect of anticancer drugs in ARH-77 cells. These results indicated that TNF-alpha-neutralizing antibodies or infliximab enhanced the cytotoxic effect of anticancer drugs by suppressing the TNF receptor/mTOR/NF-kappa B pathways. The inhibition of TNF-alpha may thus provide a new therapeutic approach to control tumour progression and bone destruction in MM patients. (C) 2013 Elsevier Ltd. All rights reserved.
  • MarR-type Transcriptional Regulator ChlR Activates Expression of Tetrapyrrole Biosynthesis Genes in Response to Low-oxygen Conditions in Cyanobacteria, Rina Aoki, Tomoya Takeda, Tatsuo Omata, Kunio Ihara, Yuichi Fujita, JOURNAL OF BIOLOGICAL CHEMISTRY, JOURNAL OF BIOLOGICAL CHEMISTRY, 287(16), 13500 - 13507, Apr. 2012 , Refereed
    Summary:Oxygen is required for three enzyme reactions in chlorophyll and bilin biosynthesis pathways: coproporphyrinogen III oxidase (HemF), heme oxygenase (HO1), and Mg-protoporphyrin IX monomethylester cyclase (ChlA(I)). The cyanobacterium Synechocystis sp. PCC 6803 has alternative enzymes, HemN, HO2, and ChlA(II), to supply chlorophyll/bilins even under low-oxygen environments. The three genes form an operon, chlA(II)-ho2-hemN, that is induced in response to low-oxygen conditions to bypass the oxygen-dependent reactions. Here we identified a transcriptional regulator for the induction of the operon in response to low-oxygen conditions. A pseudorevertant, Delta ho1R, was isolated from a HO1-lacking mutant Delta ho1 that is lethal under aerobic conditions. Delta ho1R grew well even under aerobic conditions. In Delta ho1R, HO2 that is induced only under low-oxygen conditions was anomalously expressed under aerobic conditions to complement the loss of HO1. A G-to-C transversion in sll1512 causing the amino acid change from aspartate 35 to histidine was identified as the relevant mutation by resequencing of the Delta ho1R genome. Sll1512 is a MarR-type transcriptional regulator. An sll1512-lacking mutant grew poorly under low-oxygen conditions with a remarked decrease in Chl content that would be caused by the suppressed induction of the chlA(II) and hemN genes in Chl biosynthesis under low-oxygen conditions. These results demonstrated that Sll1512 is an activator in response to low-oxygen environments and that the D35H variant becomes a constitutive activator. This hypothesis was supported by a gel shift assay showing that the Sll1512-D35H variant binds to the DNA fragment upstream of the operon. We propose to name sll1512 chlR.
  • Validation of diffusive mini-samplers for aldehyde and VOC and its feasibility for measuring the exposure levels of elementary school children, Atsuko Araki, Tazuru Tsuboi, Toshio Kawai, Yu Ait Bamai, Tomoya Takeda, Eiji Yoshioka, Reiko Kishi, JOURNAL OF ENVIRONMENTAL MONITORING, JOURNAL OF ENVIRONMENTAL MONITORING, 14(2), 368 - 374, Feb. 2012 , Refereed
    Summary:Exposure to various chemicals can cause adverse effects to health, such as asthma and allergies, especially in children. Data on personal exposure levels in children are scarce, thus small lightweight diffusive mini-samplers for aldehydes and volatile organic compounds (VOCs) were designed to measure the exposure level of children to these chemicals. The aim of the study was to validate and examine the applicability of these mini-samplers for measuring daily chemical exposure. The diffusive mini-samplers are 20 mm in length, 11 mm in diameter, and 1.67 g in weight. The devices are cylindrically shaped with polytetrafluoroethylene membrane filters placed at each end. To measure aldehydes and acetone, 20 mg of 2,4-dinitrophenylhydrazine was used as an absorbent. To measure VOCs, a carbon molecular sieve was used. The sampling rate for each chemical was determined by parallel sampling with active samplers in a closed exposure bag. The blank levels of the chemicals and the storage stability of the device were tested. The mini-samplers were compared to commercially available diffusive samplers. To examine the applicability of the samplers, 65 elementary school children carried them for 24 h. The sampling rates for formaldehyde, acetaldehyde, and acetone were 20.9, 22.9, and 19.7 mL min(-1), respectively. The limits of quantification (LOQ) for the 24-hour sampling by high-performance liquid chromatography/ultraviolet (HPLC/UV) analysis were 8.3, 7.6, and 8.8 mu g m(-3) for formaldehyde, acetaldehyde, and acetone, respectively. The sampling rates for the 11 VOCs were determined and ranged from 3.3 mL min(-1) for styrene and 2-ethyl-1-hexanol to 11.7 mL min(-1) for benzene. The LOQ for the 24-hour sampling by gas chromatography-mass spectrometry (GC-MS) analysis ranged from 5.9-105.2 mu g m(-3), 1.1-24.7 parts per billion. The storage stability after 5 days ranged from 94.8 to 118.2%. Formaldehyde, acetone, benzene, and toluene were detected above the LOQ in more than 90% of the children, and the median concentrations were 21.7, 20.9, 10.1, and 21.5 mu g m(-3), respectively. This study shows that the diffusive samplers developed were suitable for children to carry and were capable of measuring the children's daily chemical exposure.
  • Crucial role of the small GTPase Rac1 in insulin-stimulated translocation of glucose transporter 4 to the mouse skeletal muscle sarcolemma, Shuji Ueda, Sohei Kitazawa, Kota Ishida, Yuki Nishikawa, Megumi Matsui, Hikaru Matsumoto, Takuji Aoki, Shinsuke Nozaki, Tomoya Takeda, Yoshikazu Tamori, Atsu Aiba, C. Ronald Kahn, Tohru Kataoka, Takaya Satoh, FASEB JOURNAL, FASEB JOURNAL, 24(7), 2254 - 2261, Jul. 2010 , Refereed
    Summary:The Rho family GTPase Rac1 has been implicated in the regulation of glucose uptake in myoblast cell lines. However, no evidence for the role of Rac1 has been provided by a mouse model. The purpose of this study is to test the involvement of Rac1 in insulin action in mouse skeletal muscle. Intravenous administration of insulin indeed elicited Rac1 activation in gastrocnemius muscle, suggesting the involvement of Rac1 in this signaling pathway. We then examined whether insulin-stimulated translocation of the facilitative glucose transporter GLUT4 from its storage sites to the skeletal muscle sarcolemma depends on Rac1. We show that ectopic expression of constitutively activated Rac1, as well as intravenous administration of insulin, caused translocation of GLUT4 to the gastrocnemius muscle sarcolemma, as revealed by immunofluorescent staining of a transiently expressed exofacial epitope-tagged GLUT4 reporter. Of particular note, insulin-dependent, but not constitutively activated Rac1-induced, GLUT4 translocation was markedly suppressed in skeletal muscle-specific rac1-knockout mice compared to control mice. Immunogold electron microscopic analysis of endogenous GLUT4 gave similar results. Collectively, we propose a critical role of Rac1 in insulin-dependent GLUT4 translocation to the skeletal muscle sarcolemma, which has heretofore been predicted solely by cell culture studies.-Ueda, S., Kitazawa, S., Ishida, K., Nishikawa, Y., Matsui, M., Matsumoto, H., Aoki, T., Nozaki, S., Takeda, T., Tamori, Y., Aiba, A., Kahn, C. R., Kataoka, T., Satoh, T. Crucial role of the small GTPase Rac1 in insulin-stimulated translocation of glucose transporter 4 to the mouse skeletal muscle sarcolemma. FASEB J. 24, 2254-2261 (2010). www.fasebj.org