[Expression of acetyl coenzyme A synthetase 2 in colorectal cancer and its biological role].

OBJECTIVE: To investigate the expression of acetyl coenzyme A synthetase short-chain family member 2 (ACSS2) in patients with colorectal cancer (CRC) and its biological role.

METHODS: A total of 74 CRC tissue samples and 40 normal colorectal tissues were tested by immunohistochemical staining to detect the expression of ACSS2 (cell staining intensity score: 0 points: without staining, 1 points: weak staining, 2 points: intensity staining, 3 point: strong staining; the percentage of positive cells in tumor or negative score: 0 points: negative, 1 point: <25% positive cells, 2 points: 25%-50% positive cells, 3 points: 50%-75% positive cells, 4 points: >75% positive cells. The product of above two scores was the final score.). Association of ACSS2 expression with clinicopathological characteristics was analyzed. Small interfering RNA (siRNA, including A and B group) was used to knock down the expression of ACSS2 in colorectal cell lines (Lovo, HCT116) and their proliferation, migration and epithelial-mesenchymal transition (E-cadherin and Snail as markers) after knocking down were observed.

RESULTS: The expression of ACSS2 was significant higher in CRC tissue than that in normal colorectal tissue (tumor average score 6.284, normal tissue average score 3.625, P<0.01) and the percentage of positive cell was higher than that in normal tissue (tumor 69.9%, normal tissue 45.1%, P=0.000). The use of ACSS2 siRNA successfully knocked down the expression of ACSS2 in Lovo and HCT116 cells. A mild suppression of cell proliferation was observed 5 days after planked (A450 value: Lovo-NC 1.758±0.041, Lovo-ACSS2-siA 1.485±10.026, Lovo-ACSS2-siB 1.371±0.049; HCT116-NC 2.609±0.038, HCT116-ACSS2-siA 2.260±0.042, HCT116-ACSS2-siB 2.295±0.029). While a remarkable ability decline of cell migration was found (Lovo-NC 225±5/field, Lovo-ACSS2-siA 40±5/field, Lovo-ACSS2-siB 79±3/field; HCT116-NC 198±7/field, HCT116-ACSS2-siA 96±7/field, HCT116-ACSS2-siB 77±9/field, P<0.05). Real-time quantitative PCR detection showed that in Lovo cells, expression of E-cadherin up-regulated and expression of Snail down-regulated, while in HCT116 cells, E-cadherin up-regulated slightly [E-cadherin: Lovo NC 1.000±0.211, Lovo-siA 3.403±0.207, Lovo-siB 2.658±0.420 (P<0.05); HCT116 NC 1.000±0.121, HCT116-siA 1.349±0.197, HCT116-siB 1.528±0.147(P>0.05); Snail: Lovo NC 1.000±0.085, Lovo-siA 0.468±0.030, Lovo-siB 0.499±0.088 (P<0.05); HCT116 NC 1.000±0.118, HCT116-siA 0.265±0.020, HCT116-siB 0.194±0.017 (P<0.05)].

CONCLUSION: CRC tissues have high expression of ACSS2, which may be associated with cell migration and epithelial-mesenchymal transition.