trans E1 component requirements for maximal replication of E1-defective recombinant adenovirus

Strategies that enable EI-defective recombinant adenoviruses to selectively undergo replication in neoplastic tissue may be useful for future investigations or therapies of malignancies. A growing body of evidence suggests that some molecular alterations commonly associated with malignancies, such as p53 mutations, can modify the specific EI requirements for replication of human serotype adenoviruses, In the studies reported here, a panel of human non-small cell lung cancer cell lines with previously defined p53 status were characterized for basal interleukin-6 (IL-6) and bcl-2 content because previous studies have indicated both proteins can functionally substitute for the replication requirements provided by native EI viral proteins. Cell lines were infected with El-defective adenovirus 5 and simultaneously transfected with different combinations of El plasmids, or a bcl-2 expression plasmid, and adenovirus present in the cells was quantified 6 days later. These assays demonstrated that E1A with both 19- and 55-kDa E1B-encoding plasmids were required for maximal adenoviral replication, independent of the varying p53/IL-6/basal bcl-2 phenotypes of the host cell lines. EIA was required for maximal replication enablement, independent of the basal IL-6 content of these cell lines, and exogenous IL-6 also did not obviate the E1A requirement Interestingly, the bcl-2 expression plasmid did not consistently substitute for the 19-kDa expression plasmid in the context of this replication complementation assay. These results suggest that (1) basal levels of IL-6 greater than that present in these cell lines are necessary for functional replacement of the EIA replication function and (2) bcl-2 does not predictably substitute for the 19-kDa E1B replication function in the context of trans complementation. (C) 1998 Academic Press.