Suppression of microRNA-31 increases sensitivity to 5-FU at an early stage, and affects cell migration and invasion in HCT-116 colon cancer cells.
BACKGROUND
MicroRNAs (miRNAs) are endogenously expressed noncoding RNAs with important biological and pathological functions. Although several studies have shown that microRNA-31 (miR-31) is obviously up-regulated in colorectal cancer (CRC), there is no study on the functional roles of miR-31 in CRC.


METHODS
Anti-miR™ miRNA 31 inhibitor (anti-miR-31) is a sequence-specific and chemically modified oligonucleotide to specifically target and knockdown miR-31 molecule. The effect of anti-miR-31 transfection was investigated by real-time PCR. HCT-116p53+/+ and HCT-116p53-/-colon cancer cells were treated by anti-miR-31 with or without 5-fluorouracil (5-FU), cell proliferation was determined by MTT assay; apoptosis was detected by DAPI staining; cell cycle was evaluated by flow cytometry; colony formation, migration and invasion assays were performed to investigate the effect of suppression of miR-31 on the cell lines.


RESULTS
Real-time PCR results showed that anti-miR-31 was efficiently introduced into the cells and reduced miR-31 levels to 44.1% in HCT-116p53+/+ and 67.8% in HCT-116p53-/-cell line (p = 0.042 and 0.046). MTT results showed that anti-miR-31 alone had no effect on the proliferation of HCT-116p53+/+ or HCT-116p53-/-. However, when combined with 5-FU, anti-miR-31 inhibited the proliferation of the two cell lines as early as 24 h after exposure to 5-FU (p = 0.038 and 0.044). Suppression of miR-31 caused a reduction of the migratory cells by nearly 50% compared with the negative control in both HCT-116p53+/+ and HCT-116p53-/-(p = 0.040 and 0.001). The invasive ability of the cells were increased by 8-fold in HCT-116p53+/+ and 2-fold in HCT-116p53-/- (p = 0.045 and 0.009). Suppression of miR-31 had no effect on cell cycle and colony formation (p > 0.05).


CONCLUSIONS
Suppression of miR-31 increases sensitivity to 5-FU at an early stage, and affects cell migration and invasion in HCT-116 colon cancer cells.
Division of Oncology, Department of Clinical and Experiment Medicine, University of Linköping, Linköping, Sweden.
Chao-Jie
CJ
Wang
Johannes
J
Stratmann
Zong-Guang
ZG
Zhou
Xiao-Feng
XF
Sun
D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D002465:Cell Movement; D049109:Cell Proliferation; D005472:Fluorouracil / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic; D045325:HCT116 Cells; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D035683:MicroRNAs / Q000378:metabolism*; D009361:Neoplasm Invasiveness
D000964:Antimetabolites, Antineoplastic; D000970:Antineoplastic Agents; C534612:MIRN31 microRNA, human; D035683:MicroRNAs; C539917:Mirn31 microRNA, mouse; D005472:Fluorouracil