| Objective:DOT1L,a methyltransferase of H3K79,was observed to be amplified and overexpressed in certain malignancies.The purpose of this study was to detect the difference in expression of DOT1 L in normal gastric tissue and gastric cancer tissue and its impact on survival and prognosis of gastric cancer patients,and to explore whether DOT1 L regulates gastric cancer progression and its mechanism by regulating H3K79 methylation.Methods: 1.Immunohistochemistry was used to detect DOT1 L levels in 101 cases of gastric cancer and marching adjacent normal tissues.2.DOT1 L was inhibited by small interfering RNA(si RNA)and EPZ5676(a targeting drug),and verified by q RT‐PCR.3.The ability of gastric cancer cells under DOT1 L inhibition to proliferate were checked by CCK8 and clone formation assays.4.Flow cytometry was used to detect postcyclic changes of gastric cancer cells inhibited by DOT1 L.5.Western blot was used to detect the expression changes of H3K79me2 and cycle regulators(CDK4,CDK6),so as to explore the effect of DOT1 L on the proliferation mechanism of gastric cancer cells.6.The effect of EPZ5676 on tumor growth was studied through the xenogenic model of nude mice.Results: 1.The expression of DOT1 L is significantly increased in gastric malignant tumors that is related to the degree of differentiation,lymph node metastasis and TNM staging.2.DOT1 L serves as an independent marker for the prognosis of overall survival(OS)with high levels implying worse prognosis.3.After gastric cancer cells were cultured with the targeted drug EPZ5676 in vitro,the expression level of DOT1 L was significantly decreased.4.Compared with the control group,the proliferation ability of gastric cancer cells in the DOT1 L inhibition group was decreased,and the G1 phase of cell cycle was inhibited.5.DOT1 L regulates CDK4 and CDK6 through H3K79me2,which leads to a change in the cell cycle.6.In vivo experiments showed that compared with nude mice that did not use EPZ5676,the tumors of nude mice were smaller and lighter after use.Conclusions: 1.DOT1 L may be an important factor affecting survival and prognosis of gastric cancer.2.DOT1 L regulates the cell cycle factor through H3K79me2,changes the cell cycle and affects the proliferation of gastric cancer cells.3.The targeted drug EPZ5676 has a certain inhibitory effect on the occurrence and development of gastric cancer.This indicates the role of DOT1 L in the prognosis and possible medical intervention of gastric cancer. |
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