Abstract 2549: Chromosomal instability and DNA repair status during folic acid deficiency in breast cancer cells

Abstract

Abstract Folic acid deficiency is thought to be procarcinogenic because it promotes the incorporation of genomic uracil. Base excision repair (BER) normally prevents genomic instability by removing procarcinogenic base lesions. However, BER might paradoxically contribute to folate deficient-carcinogenesis if the pathway is initiated but cannot be completed, resulting in the accumulation of BER intermediates (DNA strand breaks). DNA polymerase ≤ (POLα) performs two key steps in BER and so we utilized human metastatic breast cancer cells in which the expression of POLα has been eliminated or transgenically expressed to determine the influence of POLα on chromosomal stability. We found that folic acid deficiency induced premature chromatin condensation (PCC) and strand breaks in POLα deficient cells, demonstrating that folic acid deficiency and BER deficiency induce chromosomal instability. We also examined the expression and localization of PARP1, a key component of BER and strand break repair. PARP1 was not cleaved during folic acid deficiency, suggesting that apoptosis was not occurring under these conditions. More interestingly, PARP1 was dramatically re-localized within the nucleus in POLα deficient cells. We are currently examining the effect of PARP inhibitors and the activation of PARP under these conditions. Collectively, the data suggests that folic acid deficiency in combination with deficiency in POLα is capable of inducing gross chromosomal instability that invokes DSB repair pathways. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2549. doi:1538-7445.AM2012-2549