[Viability of Colon Tumor Cells in Insufficient-nutritional Condition is Reduced by MiR-133b Through Regulating Expression of GSTP1].

OBJECTIVE: To determine the expression level of GSTP1 in colon tumor tissues at different stages and the effects of GSTP1 expression on colon tumor cells,and to identify miR that regulate the expression of GSTP1.

METHODS: Realtime PCR and western blot were used to detect the expression level of GSTP1 in colon tumor tissues. pcDNA3.1GSTP1 was constructed and transfected into human colon tumor cell line HCT116. The apoptosis rate and viability of HCT116 were measured. TargetScan and MicroCosm Targets programs were used to measure GSTP1 3'UTR and identify GSTP1targeting miR. pGL3GSTP13'UTR was constructed and transfected with the selected miR into human kidney epithelial cell line HEK293. Dualluciferase reporter assay were performed to detect the regulation effect of the selected miR on GSTP1 expressions. The selected miR was transfected into HCT116,and their levels of GSTP1 expression and reactive oxygen species (ROS) were measured. The selected miR and pcDNA3.1GSTP1 were then transfected together into HCT116. The viability and ROS level of the transfected cells were measured.

RESULTS: The expression levels of GSTP1 increased in colon tumor tissues at all stages. Overexpression of GSTP1 decreased apoptosis and increased viability of HCT116 in insufficientnutritional condition. miR133b could target GSTP1 3'UTR and repressively regulate GSTP1 expressions in HCT116. The overexpression of miR133b rapidly decreased viability and increased ROS level in HCT116 in insufficientnutritional condition. But such effects were absent in normal nutritional condition. In addition,in insufficient nutrition condition,when the HCT116 overexpress miR133b and GSTP1 at the same time,the extent of viability decrease and ROS level increase are shortened.

CONCLUSION: In insufficientnutritional condition,miR133b decreases viability of colon tumor cells by repressively regulating GSTP1 expressions.