OBJECTIVETo study the effect of CEA gene regulation on the anti-tumor activity of oncolytic adenovirus H101 to esophageal carcinoma, and to explore the intrinsic factors influencing H101 sensitivity.

METHODSStable human esophageal cancer cell line EC9706 cells with lower (EC9706-SCEA) and higher CEA expression (EC9706-CEA) were chosen, thawed and cultured, and then to analyse the influence of CEA expressed at different levels on cell growth. The cytotoxic effect of H101 was assayed by in vitro and nude mouse in vivo.

RESULTSThe cell growth experiment showed that the population doubling time of EC9706-SCEA, EC9706-CEA and EC9706 cells were (30.9 ± 2.0) h, (31.1 ± 2.5) h and (29.1 ± 2.6) h, respectively, showing no significant difference among them (P > 0.05). The cytotoxic activity of H101 was higher on EC9706-SCEA than on other four groups, when MOI was ≥ 0.01 PFU (P < 0.05). The mouse experiment showed that H101 inhibited the growth of transplanted tumors in all experimental groups. Its effect on CEA-silenced tumors (inhibition rate was 61.5% to 74.5%) was significantly higher than that on CEA-overexpression tumors (32.3% to 38.5%) and control EC9706 transplanted tumors (35.5% to 44.8%). There was a significant difference between them (P < 0.05).

CONCLUSIONSThe results in vitro and in vivo experiments show that H101 can enhance the cytotoxic effect on EC9706 cells with lower CEA expression. To silence the expression of CEA may provide a novel strategy for target gene therapy of esophageal carcinoma.