Abstract:

Objective To investigate the effect of miR⁃140⁃5p on autophagy and oxaliplatin sensitivity in colorectal cancer（CRC）cells. Methods The expression of miR⁃140⁃5p mRNA in CRC tissues and adjacent tissues of 30 patients was detected by real⁃time quantitative polynucleotide chain reaction（RT⁃qPCR）. The expres⁃ sion of miR⁃140⁃5p mRNA in CRC cells and normal colorectal cells was detected. CRC cells HCT 116 were trans⁃ fected by miR⁃140⁃5p mimics and the transfection efficiency was measured by RT⁃qPCR. CCK⁃8 was used to detect the cell viability of the transfected group and the control group. The expression of microtubule associated protein light chain 3（LC3）was detected by western blot. Expression of LC3 fluorescence spots was detected by immunoflu⁃ orescence. After transfection with miR⁃140⁃5p mimics and co⁃treatment of autophagy activator rapamycin，CCK⁃8 was used to detect the sensitivity of CRC cells to oxaliplatin in the co⁃treated group and the transfected miR⁃140⁃5p mimics group. Clone formation assay was used to detect the proliferation of CRC cells. Results The expression of miR ⁃140⁃5p in CRC tissues and CRC cell lines was significantly lower than that in adjacent tissues and normal colorectal cell lines（P < 0.05）. CCK⁃8 results showed that overexpression of miR⁃140⁃5p promoted the sensitivity of CRC cells to oxaliplatin（P < 0.05）. Western blot showed that overexpression of miR⁃140⁃5p promotes reduced expression levels of LC3II/I，immunofluorescence showed that overexpression of miR⁃140⁃5p inhibited the expres⁃ sion of LC3 fluorescent spots（P < 0.05）. After overexpression of miR⁃140⁃5p was co⁃treated with rapamycin，CCK⁃8showed that cells in co⁃treated group were less sensitive to oxaliplatin than those in the miR⁃140⁃5p mimics group alone. Clone formation experiment showed that the cell proliferation level of co ⁃treatment group increased. Conclusion The expression of miR⁃140⁃5p in CRC tissues and CRC cell lines is lower than that in adjacent tis⁃ sues and normal colorectal cell lines，respectively. MiR⁃140⁃5p promotes the sensitivity of CRC cells to oxaliplatin by inhibiting autophagy，which may provide a strategy for targeted therapy of CRC.

Key words: colorectal cancer,  , miR?140?5p,  , oxaliplatin,  , drug resistance,  , autophagy ,