OBJECTIVETo study the role of Beclin1 gene in autophagy and apoptosis of SW620 cells.

METHODSRNA interference was used to knockdown the expression of Beclin 1 in SW620 cells, and the cell viability was measured by MTT assays. The autophagic activity in serum-starved SW620 CRC cells was evaluated by assessing endogenous microtubule-associated protein 1 light chain 3 (LC3) protein levels using immunofluorescence assay. Flow cytometry was used to measure the apoptosis rate of SW620 cells treated with serum deprivation, staurosporine or etoposide, and the protein expression of Beclin1 was detected using Western blotting.

RESULTSThe viability of cells in pSUPER-Becl group was significantly reduced after serum deprivation (P<0.05). Serum deprivation for 24 h resulted in a stronger apoptotic resistance in cells in the control and pSUPER-non groups than in pSUPER-Becl group (P<0.05). Treatment with staurosporine the most significantly increased the cell apoptosis in pSUPER-Becl group (P<0.05), and similar effect was observed with etoposide treatment (P<0.05). As the time of serum deprivation extended, the expression of Beclin 1 in control group and pSUPER-non group increased progressively (P<0.05), which was consistent with the changes in LC3 expression; LC3 expression in pSUPER-Becl group decreased significantly with a prolonged serum starvation (P<0.05).

CONCLUSIONBeclin 1 is a crucial regulator of autophagy and apoptosis in colorectal cancer cells to maintain the balance between autophagy and apoptosis. Beclin 1 may serve as a protective mechanism to protect colorectal cancer cells from injury caused by low nutrition and chemotherapy byregulating cell autophagy.