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

Area of Science:

• Oncology
• Virology
• Molecular Biology

Background:

• Recombinant adenoviruses with defective E1 genes show potential for cancer therapy by replicating selectively in tumors.
• Malignancy-associated molecular changes, such as p53 mutations, may alter adenovirus E1 gene replication needs.
• Interleukin-6 (IL-6) and bcl-2 proteins have been suggested to functionally replace native E1 viral proteins for replication.

Purpose of the Study:

• To investigate if p53 status, IL-6, or bcl-2 levels in non-small cell lung cancer (NSCLC) cell lines can substitute for E1 gene requirements for adenovirus replication.
• To determine the specific E1 gene requirements for maximal adenovirus replication in NSCLC cells with varying molecular profiles.

Main Methods:

• Characterization of NSCLC cell lines for basal IL-6 and bcl-2 expression.
• Infection of cell lines with E1-defective adenovirus 5.
• Transfection with combinations of E1 plasmids or a bcl-2 expression plasmid.
• Quantification of viral replication 6 days post-infection.

Main Results:

• Maximal adenovirus replication required both E1A and E1B (19- and 55-kDa) regardless of host cell p53, IL-6, or bcl-2 status.
• E1A was essential for replication, and its requirement was not obviated by basal IL-6 levels or exogenous IL-6.
• A bcl-2 expression plasmid did not consistently substitute for the 19-kDa E1B protein in replication complementation assays.

Conclusions:

• Basal IL-6 levels higher than those in the tested cell lines may be necessary for E1A replication function replacement.
• Bcl-2 does not reliably substitute for the 19-kDa E1B protein's replication function during trans complementation.