CEA Promoter-regulated Oncolytic Adenovirus-mediated Hsp70Expression In Immume Gene Therapy For CEA Positive Tumors

Objective To investigate the antitumor activity of the CEA promoter regulated oncolytic adenovirus-mediated Hsp70gene expression for CEA positive tumors.Methods Viral replication experiments were performed to evaluate the selective replication ability of AdCEAp-Hsp70in CEA positive cells and CEA negtive cells. Western blotting was used to examine the expression of Hsp70after AdCEAp-Hsp70infected SGC-7901cells and Hep1-6cells. The inhibitory effect of AdCEAp-Hsp70to SGC-7901cells, Hepl-6cells and BJ cells was detected by MTT assay. Established the Lewis rats model of pancreatic cancer xenografts. Observed the anti pancreatic cancer xenografts activity of the AdCEAp-Hsp70through Lewis rats in vivo experiments. An ELISA assay was used to detect Hsp70protein and cytokine levels of IFN-y, TFN-a, IL-6in the serum. The gamma/delta T cells in tumor tissue were detected by immunohistochemistry.Results Viral replication experiments confirmed the selective proliferation of AdCEAp-Hsp70in CEA positive cells. Western blotting analysis confirmed the expression of Hsp70gene after AdCEAp-Hsp70infected SGC-7901cells and Hepl-6cells. MTT results showed that when the MOI was increased to200pfu/cell, compared with the control group, the survival rates of SGC-7901cells was53.35%(P<0.01), the survival rates of Hepl-6cells was39.11%(P<0.01) and the survival rates of BJ cells was83.13%(P<0.05). Successfully established the Lewis rats model of pancreatic cancer xenografts. Animal experiments showed that the AdCEAp-Hsp70evidently inhibited the growth of pancreatic cancer xenografts in Lewis rats, with the inhibition rate being58.75%(P<0.01). ELISA results showed that in the AdCEAp-Hsp70group, Hsp70, IFN-γ, TNF-α and IL-6levels were significantly higher than in the control and AdCMV-Hsp70groups(P<0.01). Pathological examination of the tumor specimens showed that the AdCEAp-Hsp70group had a significantly higher number of gamma/delta T cells infiltrating the tumor interstitial space than the control and the AdCMV-Hsp70groups (P<0.01).Conclusion①AdCEAp-Hsp70can effectively replicate in CEA positive SGC-7901cells and Hepl-6cells, and obviously reduce the survival rates of SGC-7901cells and Hepl-6cells.②AdCEAp-Hsp70mediated Hsp70expression can evidently inhibit the growth of pancreatic cancer xenografts in Lewis rats and the mechanisms may be related to the induction of IFN-γ, TNF-α and IL-6secretion and promotion of gamma/delta T cells infiltration.