ABSTRACT
Objective To evaluate the effect of microRNA-92a (miR-92a) on regulating cell proliferation by targeting Krüppel-like factor 4 (KLF4) in colon cancer.Methods The miR-92a expressions in 21 colon cancer tissues and matched normal tumor-adjacent tissues and 4 colon cancer cells (HT29,SW480,SW620,HCT116) were detected using quantitative real-time polymerase chain reaction (qRT-PCR).Models of over-expression and suppression of miR-92a were established by transient transfection of miR-92a-3p mimic to HCT116 and transient transfection of miR-92a-3p inhibitor to SW620,respectively.Cell proliferation activity was detected by the CCK-8 colorimetry method,cell cycles were detected by flow cytometry,KLF4 protein expression was detected by Western blotting,and cell luciferase activity was detected by the dual luciferase reporter gene experiment.Results The expression level of miR-92a in colon cancer tissues was (0.648 ± 0.489) fmol/μg total RNA,significantly higher than that in matched normal tumor-adjacent tissues [(0.064 ± 0.062) fmol/μg total RNA],with statistically significant difference (t =-5.420,P ＜ 0.001).In 4 colon cancer cell lines,the miR-92a expression level in HCT116 cells was the lowest,and highest in SW620 cell.When the expression of miR-92a was up-regulated,the cell proliferation activity of 72 h in HCT116 cells was higher than that in the negative control group (0.919 ±0.014 vs.0.765 ± 0.025),with statistically significant difference (t =-9.309,P =0.001),the proportion of S phase cells was also significantly increased [(41.670 ±0.461)％ vs.(38.703 ±0.554)％,t =-7.127,P =0.002),and KLF4 protein expression was decreased (0.460 ± 0.048 vs.0.758 ± 0.109,t =22.865,P =0.028).When the expression of miR-92a was down-regulated,the cell proliferation activity of 72 h in SW620 cells was lower than that in the negative control group (0.608 ± 0.011 vs.0.713 ± 0.005),with statistically significant difference (t =15.920,P ＜ 0.001),while the proportion of S phase cells was decreased [(31.935 ± 0.365) ％ vs.(34.955 ± 0.465) ％,t =8.849,P =0.001],and KLF4 protein expression was increased (0.694 ± 0.121 vs.0.479 ± 0.044,t =-5.246,P =0.034).KLF4 3'UTR wild-type dual luciferase report plasmids were co-transfected with miR-92a-3p mimic to HCT116 cell,and dual luciferase assay showed that miR-92a slightly repressed firefly luciferase actively,but the difference was not statistically significant (t =0.878,P =0.429).There was a negative correlation between the expression of miR-92a and the expression of KLF4 protein in colon cancer tissues,but with no statistical significance (r =-0.163,P =0.699).Conclusion miR-92a is highly expressed in colon cancer tissues.It can promote colon cancer cells proliferation via enhancement of the cell cycle transition of G0-G1 phase to S phase.Up-expression of miR-92a may play a role in down-regulating the expression of KLF4 protein in colon cancer cells.However,KLF4 is not a direct target gene of miR-92a.
ABSTRACT
AIM:TostudythefunctionofmicroRNA(miR)-19aandmiR-92abyseed-targetinginhibitionin multiple myeloma cells and their signal pathways .METHODS:The experiments were divided into t-antimiR-19a group, t-antimiR-92a group, scramble control group and blank control group .The growth-inhibitory potencies were measured by MTT assay.The ability of cell colony formation was measured by cell colony formation assay .The ability of cell invasion was measured by Transwell experiment .The miR-19a and miR-92a target gene signal pathways were integrated by miRFo-cus software.RESULTS:MTT assay showed that t-antimiR-19a and t-antimiR-92a significantly inhibited the viability of multiple myeloma cells , and the best concentration and time were 0.5μmol/L and 48 h, respectively .The colony number in t-antimiR-19a/92a group was less than that in scramble control group .The transfection with t-antimiR-19a or t-antimiR-92a effectively decreased the cell invasion , as the relative invasion cell number was significantly decreased compared with scramble control group.miR-19a and miR-92a were involved in mTOR signaling, cell cycle and other cancer pathways . CONCLUSION:miR-19a and miR-92a cluster might be a potential target for therapeutic intervention in multiple myelo-ma.