Distinct effect of retroviral-mediated IFN-alpha gene transfer on human erythroleukemic and CD34(+) cell growth and differentiation

Human interferon-alpha (IFN-alpha) has been used in the management of leuke mia, but its diverse adverse effects may influence the ability of IFN-alpha to treat this disease. We constructed two retroviral vectors, LSN-IFN-alph a and LNC-IFN-alpha, in which IFN-alpha cDNA was driven by viral LTR and CM V promoters, respectively. After transduction into the PA317 and PG13 retro viral packaging cells, high titers of retrovirus were produced and were use d to infect K562 and human BM CD34(+) hematopoietic cells. The IFN-alpha ge ne expression in transduced K562 cells was confirmed by Northern blot, RT-P CR, RIA, and biologic assay. Cell proliferation and cell viability in IFN-a lpha-transduced K562 cells were significantly suppressed as compared with c ontrol K562 cells. Although the IFN-alpha expression in K562 cells did not affect BCR/ABL expression, it apparently upregulated the production of adhe sion molecules (VLA-4 and Mac-1). We evaluated the effect of IFN-alpha gene transfer on human CD34(+) cells infected with LSN-IFN-alpha retrovirus wit h the aid of fibronectin (FN) fragment CH-296 and growth factors. RIA showe d that IFN-alpha-transduced CD34(+) cells produced 72.2 +/- 15 U/ml of IFN- alpha compared with 4.3 +/- 1.2 U/ml in control CD34(+) cells. Methylcellul ose clonogenic assay indicated that IFN-alpha-transduced CD34(+) cells prod uced similar numbers of burst-forming units-erythrocytes (BFU-E)/colony-for ming units-GM (CFU-GM) colonies as compared with control CD34(+) cells. Sel ected colonies expressed IFN-alpha and neo(r) mRNA, as measured by RT-PCR. These studies indicate that retrovirus-mediated IFN-alpha gene transfer may provide a useful tool for studying the effect of IFN-alpha gene transfer o n leukemic cells and long-lived CD34(+) cells.