407 Glucose activates STAT3, promoting XRCC1 expression and increased DNA repair after exogenous challenge

Abstract

OBJECTIVES/GOALS: Inflammation-promoting exposures, including hyperglycemia and inflammatory cytokines, are common in the development and progression of multiple cancers. Here, we determine if high glucose drives the dysregulation of XRCC1, changing BER/SSBR capacity, and increasing resistance to DNA damaging agents. METHODS/STUDY POPULATION: Here, we acutely exposed cell lines models with 30 mM glucose to mimic hyperglycemic changes and monitored the gene and protein expression of STAT3 and XRCC1. We selected the osteosarcoma cell line U2OS, with high STAT3 activation before glucose challenge, and the non-tumorigenic human embryonic kidney cell line HEK293T, with low STAT3 activation before glucose challenge, to dissect the role STAT3 plays in dysregulating DNA repair. We also examined changes in STAT3 occupancy at the XRCC1 promoter following glucose challenge using chromatin immunoprecipitation (ChIP). Finally, we measured changes in the sensitivity to the alkylating agent methyl methanesulfonate (MMS) induced by the glucose challenge using cell survival and DNA strand break analysis. RESULTS/ANTICIPATED RESULTS: High glucose challenge increases the phosphorylation and activation of STAT3 and subsequently increases XRCC1 gene and protein content in the cell. Acute high glucose activated STAT3, driving the subsequent expression of XRCC1 in U2OS and HEK293T cells through increased STAT3 occupancy at the XRCC1 promoter. High glucose also reduced sensitivity to MMS, increasing cell survival. The most significant increase in resistance to MMS occurred in the HEK293T, which also showed the largest increase in XRCC1 protein expression following the glucose challenge. Increased survival correlated with the faster resolution of DNA strand breaks in glucose-challenged cell lines. DISCUSSION/SIGNIFICANCE: This work has identified a novel regulatory mechanism by which high glucose drives the expression of XRCC1 through STAT3 activation, increasing DNA repair and resistance to the DNA damaging agent MMS. These data suggest dietary choices induce sustained XRCC1 expression and may contribute to chemoresistance and poor survival outcomes in cancers.