Mechanism of gemcitabine-induced suppression of human cholangiocellular carcinoma cell growth.

Although gemcitabine (2',2'-difluorocytidine monohydrochloride) is a common anticancer agent of cholangiocellular carcinoma (CCC), its growth inhibitory effects and gemcitabine resistance in CCC cells are poorly understood. Our aims were to uncover the mechanism underlying the antitumor effect of gemcitabine and to analyze the mechanism regulating in vitro CCC cell gemcitabine resistance. In addition, we sought to identify miRNAs associated with the antitumor effects of gemcitabine in CCCs. Using a cell proliferation assay and flow cytometry, we examined the ability of gemcitabine to inhibit cell proliferation in three types of human CCC cell lines (HuCCT-1, Huh28, TKKK). We also employed western blotting to investigate the effects of gemcitabine on cell cycle-related molecules in CCC cells. In addition, we used array chips to assess gemcitabine-mediated changes in angiogenic molecules and activated tyrosine kinase receptors in CCC cells. We used miRNA array chips to comprehensively analyze gemcitabine-induced miRNAs and examined clusters of differentially expressed miRNAs in cells with and without gemcitabine treatment. Gemcitabine inhibited cell proliferation in a dose- and time-dependent manner in HuCCT-1 cells, whereas cell proliferation was unchanged in Huh28 and TKKK cells. Gemcitabine inhibited cell cycle progression in HuCCT-1 cells from G0/G1 to S phase, resulting in G1 cell cycle arrest due to the reduction of cyclin D1 expression. In addition, gemcitabine upregulated the angiogenic molecules IL-6, IL-8, ENA-78 and MCP-1. In TKKK cells, by contrast, gemcitabine did not arrest the cell cycle or modify angiogenic molecules. Furthermore, in gemcitabine-sensitive HuCCT-1 cells, gemcitabine markedly altered miRNA expression. The miRNAs and angiogenic molecules altered by gemcitabine contribute to the inhibition of tumor growth in vitro.

MicroRNA profiles in cisplatin-induced apoptosis of hepatocellular carcinoma cells.

Cisplatin [cis-diamminedichloroplatinum (II)], is a platinum coordination compound that is commonly used to treat hepatocellular carcinoma (HCC). It is also one of the most compelling anticancer drugs. Recent studies suggest that cisplatin may reduce cancer risk and improve prognosis. However, the antitumor mechanism of cisplatin in several types of cancers, including HCC, has not been elucidated. The goal of the present study was to evaluate the effects of cisplatin on the proliferation of HCC cells in vitro and to determine which microRNAs (miRNAs) are associated with the anticancer effects of cisplatin in vitro. We used various human HCC-derived cell lines to study the effects of cisplatin on human HCC cells. Cisplatin led to a strong dose- and time- dependent inhibition of cell proliferation in HLE, HLF, HuH7, Li-7, Hep3B and HepG2 cells in vitro. Cisplatin also blocked the progression of the cell cycle in the G0/G1 phase, which inhibited cyclin D1 and induced apoptosis. In addition, miRNA expression was markedly altered by treatment with cisplatin in vitro. Therefore, various miRNAs induced by cisplatin may also contribute to the suppression of cellular proliferation and apoptosis. Our results demonstrate that cisplatin inhibits the growth of HCC, possibly through the induction of G1 cell cycle arrest and apoptosis through the alteration of microRNA expression.