TRANS E1 COMPONENT REQUIREMENTS FOR MAXIMAL REPLICATION OF E1-DEFECTIVE RECOMBINANT ADENOVIRUS

Strategies that enable EI-defective recombinant adenoviruses to select ively undergo replication in neoplastic tissue may be useful for futur e investigations or therapies of malignancies. A growing body of evide nce suggests that some molecular alterations commonly associated with malignancies, such as p53 mutations, can modify the specific EI requir ements 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 interl eukin-6 (IL-6) and bcl-2 content because previous studies have indicat ed both proteins can functionally substitute for the replication requi rements provided by native EI viral proteins. Cell lines were infected with El-defective adenovirus 5 and simultaneously transfected with di fferent combinations of El plasmids, or a bcl-2 expression plasmid, an d adenovirus present in the cells was quantified 6 days later. These a ssays demonstrated that E1A with both 19- and 55-kDa E1B-encoding plas mids were required for maximal adenoviral replication, independent of the varying p53/IL-6/basal bcl-2 phenotypes of the host cell lines. EI A was required for maximal replication enablement, independent of the basal IL-6 content of these cell lines, and exogenous IL-6 also did no t obviate the E1A requirement Interestingly, the bcl-2 expression plas mid did not consistently substitute for the 19-kDa expression plasmid in the context of this replication complementation assay. These result s suggest that (1) basal levels of IL-6 greater than that present in t hese cell lines are necessary for functional replacement of the EIA re plication function and (2) bcl-2 does not predictably substitute for t he 19-kDa E1B replication function in the context of trans complementa tion. (C) 1998 Academic Press.