GENE TRANSPLANTATION - COMBINED ANTISENSE INHIBITION AND GENE REPLACEMENT STRATEGIES

Optimal gene replacement protocols would include both inhibition of th e endogenous gene and overexpression of the preferred (or mutant) gene . We have developed a novel gene transfer method to test whether antis ense-resistant genes (designed by deletion of antisense RNA target seq uences) can replace the function of endogenous genes. Immunoprecipitat ion studies demonstrated that inducible anti-fos RNA (antisense direct ed against the c-fos gene) reduces endogenous c-fos expression by 90%, but did not affect the transfected antisense-resistant mutant c-fos g enes. Cell growth studies demonstrated that full-length and minimally truncated c-fos expression vectors could restore serum-induced DNA syn thesis but that C-terminally truncated Fos mutants including FBR v-fos could not. Transcriptional studies demonstrate that the endogenous c- fos protein contributes to AP-1 activity and normally suppresses regul ated SRE (serum response element) activity. This ''gene transplant'' m ethod for inhibition of endogenous genes and replacement with preferre d genes has implications for gene therapy of hereditary hematologic di sorders and for the correction or ''repair'' of oncogenes or tumor sup pressor genes in leukemias and lymphomas.