RESTORATION OF BRCA1 GENE FUNCTION BY LENTIVIRUS-VECTOR MEDIATED CELL TRANSDUCTION

Breast cancer is the most common type of neoplasia in women. Currently 90% of cases are sporadic and 10% hereditary. Eighty percent hereditary breast cancers are associated with mutations of breast cancer-associated genes (BRCA) type 1 and 2. This genetic background makes people at high risk to develop disease and therefore need suitable preventative strategies. Preventive mastectomy and chemoprevention are the only approaches available to date. Unfortunately side effects and invasiveness of these procedures make necessary the development of alternative strategies. Since loss of functionality of BRCA1 greatly increases the risk to develop breast cancer, to restore its function or replace the mutated gene before the emergence of neoplasia is a safer and better tolerated approach to prevent the disease. Among available techniques to insert genetic material into a specific target cell, vector derived by viruses are the most appreciable approaches. Lentiviral vectors, which integrate in host cell genome and ensure prolonged expression of the therapeutic gene, are more apt for this intervention strategy. To this aim we have produced a lentiviral vector from the feline immunodeficiency virus (FIV) to transduce wild type BRCA1 into primary mammary cells. Delivery system and restoration of BRCA1 activity was validated in tumor cells encoding an inactive BRCA1. Transduced BRCA1 was efficiently expressed and fully functional as demonstrated by the restored ability to repair DNA damages upon exposition to ionizing radiations of transduced cells. The same vector was also able to transduce epithelial primary cells derived from a breast cancer patient. These results pave the way to develop novel preventative approaches against human breast cancer.