〔Abstract〕 Objective To explore the effect of overexpression of miR-302 on the pro-inflammatory level of colon cancer cells,the level of mitochondrial oxidative stress and tumor formation in nude mice. Methods Colon cancer cells SW480 were randomly divided into a blank control group( Control),a negative control group( miR-NC),and an overexpression group( miR-302 mimic); the expression of miR-302 after transfection was detected by qRTPCR; inflammatory factors interleukin( IL)-6 and inducible nitric oxide synthase( i NOS) were tested with enzyme linked immunosorbent assay( ELISA); IL-1 β and tumor necrosis factor α( TNF-α) mRNA expression were detectd by qRT-PCR detection; the changes in mitochondrial membrane potential were detected by flow cytometry;oxidative stress markers malondialdehyde( MDA) and lactate dehydrogenase( LDH) were detected by kits; mitochondrial damage-related proteins B-cell lymphoma/leukemia 2( Bcl-2) associated X( Bax),Bcl-2,cleaved cysteinyl aspartate specific proteinase( Cleaved cas)-3 and cas3,c-Myc,and their relative levels( Bax/Bcl2,Cleaved cas3/cas3) were detected by Western blot; a nude mouse xenograft model was established to detect tumor tissue weight; caspase 3 positive expression was detected by immunohistochemistry. Results Compared with the miR-NC group,the miR-302 expression,IL-6 and i NOS protein concentrations,IL-1β and TNF-α mRNA levels,oxidative stress marker levels( MDA,LDH),mitochondrial damage-related protein expression( Bax/Bcl2,Cleaved cas3/cas3) and the positive expression of caspase 3 in tumor tissue significantly increased( P<0. 05); compared with miR-NC group,miR-302 Mimic group mitochondrial membrane potential,c-Myc expression and tumor tissue weight significantly reduced( P<0. 05). Conclusion Overexpression of miR-302 induces increased levels of inflammatory factors in colon cancer cells,mitochondrial oxidative stress,and inhibits tumor formation in nude mice.