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

METHODSA 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.

RESULTSThe 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)].

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