OBJECTIVETo elucidate the mechanism of curcumin in radiotherapy sensitization for colorectal cancer cells.

METHODSColorectal cancer HT-29 cells were cultured and treated with radiation and curcumin. MTT method was used to detect the cell growth inhibition. Then the high-throughput microarray was used to detect the differences in gene expression levels for each test group to identify differentially expressed genes, and each differential gene was validated by Western blotting.

RESULTSCell growth inhibition rates at 48-hour and 72-hour in curcumin combined with radiotherapy group were significantly higher than those in simple radiotherapy group (P<0.05). Expression of 95 genes associated with gene-injury repair was detected by microarray. Compared to simple radiotherapy group, LIG4 and PNKP expression was down-regulated, and XRCC5 and CCNH expression was up-regulated in the curcumin combined with radiotherapy group (all P<0.05). Western blotting revealed LIG4 and PNKP protein expression decreased, and XRCC5 and CCNH protein expression increased in the curcumin combined with radiotherapy group as compared to the simple radiotherapy group (all P<0.05).

CONCLUSIONRadiation sensitization effect of curcumin on colorectal cancer cells HT-29 may be associated with the regulation of genes of CCNH, LIG4, XRCC5, PNKP.