OBJECTIVETo investigate the effect of replication-competent adenovirus-mediated interleukin-12 gene to chemotherapeutic sensitivity on gastric cancer cell.

METHODSReplication-competent adenovirus and replication-competent adenovirus- mediated interleukin- 12 gene was constructed and expanded separately. The mortality of gastric cancer cell caused by the CNHK200- mIL- 12, Onyx- 015 in combination with different dosages of chemotherapeutic agents were evaluated by MTT assay at the same viral titer with a series of different dosages of chemotherapeutic agent,or at a series of different viral titers with the same dosage of chemotherapeutic agent. The curative effect to the xenografts gastric tumor in nude mouse was also observed by two viruses solely or together with 5-Fu.

RESULTSThe lytic activity of replication-competent adenovirus to gastric cancer cell line SGC-7901 was relatively poor at MOI value of 0.5, but it could be improved significantly when combined with chemotherapeutic agents of ADM, 5-Fu or CAP compared to the simple chemical therapy (P< 0.05). Chemotherapeutic agent 5- Fu could not effectively kill SGC-7901 when used at a relatively low dosage of 10microg/ml,whereas its activity could be improved when combined with a replication-competent adenovirus,and the killing rate was much higher than that with replication-competent adenovirus solely (P< 0.05). The gastric tumor xenografts was prevented and killed by replication adenovirus solely or combined with 5-Fu.

CONCLUSIONThe replication- competent adenovirus- mediated interleukin- 12 gene can increase the chemotherapeutic sensitivity on gastric cancer cell. There is synergetic effect between the replication adenovirus and the chemotherapeutic agents in killing gastric cancer cell.