ABSTRACT
Previous studies have demonstrated that microRNAs (miRNAs) are associated with tumor development and progression. miRNA-524-5p (miR-524-5p) has been reported to be involved in the development and progression of several types of cancer, but its role in gastric cancer has not been fully elucidated to date. Therefore, the aim of the present study was to investigate the expression levels and function of miR-524-5p in human gastric cancer. The expression levels of miR-524-5p were assessed in gastric cancer specimens and cell lines, including MKN-45, SGC-7901 and MGC-803 cell lines and gastric epithelial mucosa GES-1 cells, using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Cell proliferation and cell apoptosis assays and invasion analysis in gastric cancer cell lines were performed to evaluate the effects of miR-524-5p on gastric cancer cells in vitro. The expression levels of matrix metallopeptidase (MMP)-2 and MMP-9 were determined by RT-qPCR and western blot analysis. The expression of miR-524-5p was significantly decreased in gastric cancer tissues and cell lines. Additionally, the results of the in vitro experiments demonstrated that overexpression of miR-524-5p inhibited cell proliferation and invasion, and promoted cell apoptosis in gastric cancer cells. Human gastric cancer SGC-7901 and MGC-803 cell lines transfected with miR-524-5p exhibited reduced expression levels of MMP-2 and MMP-9. Taken together, the results of the present study indicated that miR-524-5p may function as a novel tumor suppressor gene in gastric cancer, and may serve as a biomarker and therapeutic target for the treatment of gastric cancer.
ABSTRACT
This study was designed to investigate the proliferation inhibition and apoptosis-promoting effect under hyperthermia and chemotherapy treatment, at cellular level. Human gastric cancer cell line SGC-7901 was cultivated with 5-fluorouracil at different temperatures. Cell proliferation and apoptosis were determined, and expression of Bcl-2 and HSP70 was measured at different treatments. Cell survival rates and inhibition rates in chemotherapy group, thermotherapy group, and thermo-chemotherapy group were drastically lower than the control group (P<0.05). For tumor cells in the thermo-chemotherapy group, survival rates and inhibition rates at three different temperatures were all significantly lower than those in chemotherapy group and thermotherapy group (P<0.05). 5-Fluorouracil induced apoptosis of SGC-7901 cells with a strong temperature dependence, which increased gradually with increase in temperature. At 37°C and 43°C there were significant differences between the thermotherapy group and chemotherapy group and between the thermo-chemotherapy group and thermotherapy group (P<0.01). The expression of Bcl-2 was downregulated and HSP70 was upregulated, with increase in temperature in all groups. Cell apoptosis was not significant at 46°C (P>0.05), which was probably due to thermotolerance caused by HSP70 accumulation. These results suggested that hyperthermia combined with 5-fluorouracil had a synergistic effect in promoting apoptosis and enhancing thermotolerance in gastric cancer cell line SGC-7901.
