(282d) Egf Ligands Decrease Retroviral Gene Transfer through Protein Kinase C-Delta

Although a lot of progress has been made in molecular design of retrovirus vectors, the interactions of recombinant retrovirus with host cells remain largely elusive. The inability of recombinant retrovirus to transduce non-dividing cells prompted several studies to determine optimal cocktails of growth factors and/or extracellular matrix molecules to promote gene transfer to slowly diving cells and in particular stem cells. In contrast to previous reports that growth factors increased gene transfer, we found that treatment of human epidermal cells with EGFR ligands i.e. EGF, TGF- or HB-EGF decreased gene transfer in a dose dependent manner. Conversely, treatment with an EGFR function blocking antibody or inhibition of EGFR tyrosine phosphorylation enhanced gene transfer in a dose dependent manner. In addition, abolishing PKC-delta but not PKC-zeta, with chemical inhibitors or siRNA reversed the effects of EGF and restored gene transfer, indicating that the effect of EGFR activation is mediated through PKC-delta. Our results implicate EGFR and PKC-delta in retroviral infection of epidermal keratinocytes and may have wide implications for retrovirus gene transfer or design of antiretroviral therapies.