The Study Of MiR-124 Expression And Its Mechanisms In Gastric Cancer

Part 1 Expression of mi R-124 was decreased in gastric cancerGastric cancer is one of the most common malignant tumors in the world. The morbidity and the mortality are very high among malignant tumors. The mechanism of gastric carcinogenesis is not clarified. The epigenetical mechanism including DNA methylation, histone modification, chromotin remodeling and non-coding RNA. A deal of studies have confirmed that the epigenetical regulation play roles in multiple steps of carcinogenesis. Non-coding RNA is a hotspot in recent years. Mi RNAs are involved in tumor development and progression. Mi RNAs play important roles in the development, proliferation and metastasis in gastric cancer. mi R-124 is considered to be a tumor suppressor in multiple tumors, but its function is unclear in gastric cancer. Objective: To identify the expression of mi R-124 in gastric cancer cells and tissues. Methods: In this study, the expression of mi R-124 in human gastric mucosal epithelium cells and gastric cancer cells was detected by q RT-PCR, the expression of mi R-124 in gastric cancer tissues and matched paracarcinoma tissues, the relationship between mi R-124 and clinical parameters of gastric cancer patients was statistically analyzed. Results: The results identified that the expression of mi R-124 was downregulated in MKN-74, MKN-28, MKN-45, MGC-803, SGC-7901 and AGS cells compared to GES-1 cells. mi R-124 was strongly positively expressed in paracarcinoma gastric mucosa, but low-expressed, focal positively or negtively expressed in gastric cancer tissues. mi R-124 was correlated to histological stage, TNM stage and node metastasis of gastric cancer patients, but not the age, gender and tumor size. The OS and DFS of mi R-124 low-expressed patients was shorter than mi R-124 high-expressed patients. Conclusions: mi R-124 was downregulated in gastric cancer cells and tissues. The expression of mi R-124 was correlated to histological stage, TNM stage, node metastasis and prognosis. Part 2 mi R-124 suppressed the proliferation and enhances drug sensitivity by targeting EZH2 in gastric cancerMi RNAs take part in multiple processes of tumors, such as cells proliferation, apoptosis, cell cycle arrest, invation and migration, angiogenesis, epithelial mesenchymal transition, and stem cell characters maitain and so on. mi R-124 was reported to inhibit tumor growth, proliferation and enhanc chemosensitivity. Drug resistance is a obstacle to successfully cure cancers. Objective: To identify the function and mechanisms of mi R-124 in gastric cancer. Methods: The effects of mi R-124 on the cells proliferation and sensivitity to 5-Fu in gastric cancer cells was detected by MTT, the effect of mi R-124 on clony formation was tested by soft agar clony formation asssay, the function of mi R-124 on gastric cancer cells in vivo was analyzed by nude mouse transplantation tumor experiment. And target genes of mi R-124 was predicted using online software, EZH2 was a target of mi R-124 by luciferase reporter assay, q RT-PCR and Western blot. Results: The cell survival rate of GES-1, MKN-74, MKN-28, MKN-45, MGC-803, SGC-7901 and AGS cells was(91.6±9.3)%,(68.4±5.7)%,(54.7±3.5)%,(64.2±6.1)%,(38.9±3.7)%,(43.6±5.2%) and(63.1±4.8)% respectively. The cell survival rate of MKN-74, MKN-28, MKN-45, MGC-803, SGC-7901 and AGS cells was decreased compared with GES-1 cells. The clony formation rate of MKN-45(22.3±2.1%) and AGS cells(59.1±4.7%) after transfected with mi R-124 mimics was declined compared with the control group. The transplanted tumor size and weight of mi R-124 mimics treated group was smaller than the control. The mi R-124 could enhancd sensitivity of 5-Fu in AGS cells. mi R-124 suppressed the expression of EZH2 by binding to 3’UTR in gastric cancer cells. The expression of EZH2 was negatively correlated to mi R-124 in gastric cancer tissues. The expression of EZH2 was not correlated to gender, age, tumor size, TNM stage and lymphatic metastasis, but was related to tumor differentiation. The proliferation of AGS cells after transfected with EZH2 si RNA on 24 h was not different from the control group. But on 48 h and 72 h, the proliferation was remarkably decreased compared with the control group. Proliferation rate of mi R-124 inhibitor in combination with si-control group was increased compared with inhibitor control in combination with si-control group. Proliferation rate of EZH2 si RNA in combination with inhibitor control was decreased compared with inhibitor control in combination with si-control group. but there was no differece between mi R-124 inhibitor group and EZH2 si RNA group compared with the control group.Conclustions: mi R-124 could inhibit proliferation of tumer cell in vitro and vivo, and enhance 5-Fu sensitivity in gastric cancer cell line. EZH2 was a target of mi R-124. EZH2 was correlated with tumor differentiation of gastric cancer patients. EZH2 mediated the sensitivity of 5-Fu by mi R-124 in gastric cancer cells.