Identification Of Gastric Cancer-related Mirnas And Analysis Of Their Clinical Association And Biological Functions

【Objective】To identify the expression profile of miRNAs in gastric cancer, the expression level of miRNAs in gastric cancer tissue was detected. To find out the diagnostic values of gastric cancer through analysis the relationship between miRNA expression levels and clinic pathological features. Further study the function of gastric cancer-related miRNAs, reveals their possible mechanisms in the development of gastric cancer.【Methods】1. Gastric cancer and non-tumor tissue samples were collected and then their total RNAs were isolated. And miRNA microarray assay was used to screen the different expression profile of miRNAs between two types of tissues.2. Choose the most different expression of miRNAs between two types of tissues, analyzed the relationships between their expression levels and clinical associations such as differentiation degree, TNM stage, tissue type and lymphatic node metastasis, and then explained their clinic significances.3. Designed and synthesized the specific inhibitors of miRNAs which highly expressed in gastric cancer tissues and then transfected them into SGC-7901 and MGC-803 gastric cancer cells by liposome. Analyzed the cell growth rate (MTT assay), the inhibition rate of miRNA expression (real-time quantitative reverse transcription-polymerase chain reaction) and the mainly target genes'expression (Western blot). And finally, revealed the possible carcinogenic mechanism of miRNAs.【Results】1. By using miRNA microarray assay, nineteen miRNAs, including twelve upexpressed and seven downexpressed, were found aberrantly expressed in gastric cancer.2. The results of immunohistochemistry indicated that the highly expression of miRNAs, such as miR-106, miR-21 and miR-17-92 cluster, were closely relate to the expression of cancer- related proteins as RB, PTEN and E2F1.3. We found that miR-421 was significantly upexpressed in gastric cancer tissues. Inhibition of miR-421 level by its inhibitor could suppress the growth of gastric cancer cells. The facts that the expression of miR-421 had a negative correlation with the expression of cancer related proteins CBX7 and RBMXL1 indicated that this specific miRNA inhibitor had a growth inhibitory effect on gastric cancer cells.4. Three miRNAs inhibitors, miR-17, miR-106a and miR-421 inhibitors, inhibited the growth of SGC-7901 and MGC-803 gastric cancer cells in a dose-dependant manner. The growth inhibitory effect on SGC-7901 was greater than that on MGC-803.【Conclusion】MicroRNAs have a close relationship with gastric cancers. miR-421 may play an important role in the early stage of stomach carcinogenesis and could be used as an efficiently diagnostic biomarker. The specific miRNA inhibitors could inhibit the growth of gastric cancer cells and may be used for the treatment of gastric cancer.