The DNA damage response (DDR) depends on a series of signal transduction pathways mediated by a cascade of proteins. One such protein is Human DNA Helicase B (HELB). The role of HELB in the DNA damage response is not fully understood. Nevertheless, HELB was implicated in DNA recombination, replication and cellular recovery from replication stress. HELB responds to DNA damage caused by hydroxyurea and the topoisomerase inhibitors etoposide and camptothecin but not the crosslinker mitomycin C. This suggests that HELB responds only to certain types of DNA damage. To investigate the role of HELB in a specific DDR pathway we studied the response of HELB to damage caused by the bifunctional chemotherapeutic agent: Carmustine (BCNU) and cross-linking agent: Cisplatin (CDDP). BCNU alkylates the O6 position of guanine and can form cross-links by alkylating two bases. Alkylation of the O6 position of guanine is cytotoxic. In addition, since BCNU is a bifunctional alkylator, it can form crosslinks by alkylating two bases. Typically, damage caused by alkylation is repaired by base excision repair (BER) although BCNU crosslinks are repaired by nucleotide excision repair (NER). Using human embryonic kidney (HEK) 293T wild type (WT) and HELB knockout cells (KO), we compared relative concentrations of phospho-replication protein A (P33-RPA) and histone γH2AX produced between each cell line in response to treatment with the various drugs via western blots (WB). A WB performed after treatment with 5mM Hydroxyurea suggested more P33-RPA and γH2AX produced by the HELB-KO cells.<br/>

Response of human DNA helicase B to alkylating and cross-linking agents

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.