, Inc, Bayer Japan The following people have nothing to disclose: Yasumasa Hara, Taro Yamashita, Naoki Oishi, Kouki Nio, Takehiro Hayashi, Yoshimoto Nomura, Tomoyuki Hayashi, Tomomi Hashiba, Masao Honda Backgrounds: Extracellular vesicles derived from hepatocellular carcinoma (HCC) cells modulate the development of HCC by transferring microRNAs. miR-133b is one of the most ACP-196 datasheet enriched microRNAs in exosomes and its expression in their cells of origin is extremely suppressed (Hepatology

2011). miR-133b has been reported to be down-regulated in many types of neoplasm and to inhibit cell growth by targeting Mcl-1, Bcl-w and MET proto oncogene. We hypothesized that miR-133b could play an onco-suppressive role in HCC. In this study we show the involvement of miR-133b in proliferation and apoptosis. Methods: The expression of miR-133b was measured using quantitative RT-PCR in human HCC tissues and HCC cell lines, PLC/ PRF/5 and Huh7. To examine the effect of miR-133b-forced expression, HCC cells were electroporated with synthetic precursor miR-133b using 4D-Nucleofector (Lonza). Proliferation of HCC cells was determined with growth curve assay and MTS assay. Apoptosis was assessed morphologically and with activation of caspase-3/7 using a luminometric assay. Protein expression was detected by immunoblotting.

Results: miR-133b MAPK inhibitor expression was down-regulated in human HCC tissues compared with corresponding adjacent liver tissues (49.0 ± 8.5%, p < 0.05). Expression of miR-133b was significantly decreased in HCC cell lines compared to primary cultured hepatocytes. Forced expression of miR-133b in HCC cells significantly decreased cell growth by 54.7% (p < 0.05) in PLC/PRF/5 and 31.3% (p < 0.05) in Huh7 cells at 72 hours. Cell viability determined by MTS assay decreased by 48.2% in PLC/PRF/5 and 30.1% in Huh7 at 72 hours after

上海皓元 the transfection of miR-133b. Enforced expression of miR-133b induced apoptotic cells by 22.6% and 18.6%, with an increase in caspase-3/7 activity by 2.1-fold and 2.3-fold in PLC/PRF/5 and Huh7, respectively. Protein expression of previously reported targets, Mcl-1, Bcl-w and MET, was examined with immunoblotting. No significant change was observed in the expression of Mcl-1 and Bcl-w after the forced expression of miR-133b, however, the expression of MET was reduced to 48.3% in PLC/PRF/5 and 23.8% in Huh7. Similarly to the effect of miR-133b-forced expression, transfecting HCC cells with siRNA against MET reduced the cell viability by 34.9% in PLC/PRF/5 at 72 hours. Caspase-3/7 activity was increased 2.4-fold by transfecting PLC/PRF/5 with MET siRNA. Conclusion: miR-133b could regulate proliferation and apoptosis in HCC cells accompanied by suppression of MET. There observations identify miR-133b as a potential therapeutic target in HCC treatment.