Date of Award

2024

Document Type

Honors Thesis (Open Access)

Department

Colby College. Chemistry Dept.

Advisor(s)

Kevin Rice

Second Advisor

Julie Millard

Abstract

Bifunctional alkylating agents have demonstrated high clinical utility as a chemotherapeutic strategy against cancer. These compounds have been well-characterized for their capacity to exert cytotoxicity via interstrand DNA crosslinking. However, the same electrophilic chemistry can also form DNA-protein crosslinks (DPCs) whose contributions to these drugs’ antitumor effects have been less well-defined. Recently, the metalloprotease SPRTN has been implicated as a predominant mediator of DPC repair in mammalian cells. Previous work has demonstrated that SPRTN deficiency increases the sensitivity of cancer cells to DPC-inducing agents such as formaldehyde and cisplatin, but these findings have yet to be translated more broadly across chemotherapies capable of inducing these lesions. Herein, we investigated the effects of impairing SPRTN repair on cancer cells’ sensitivity to bifunctional alkylating agents. First, we employed RNA interference to transiently knock down SPRTN expression in HeLa cells by over ten-fold relative to non-targeting controls. Using this SPRTN knockdown model, we then demonstrated a 2.4-fold decrease in the LD50 of mechlorethamine relative to control experiments. However, we observed no difference in DPC burden between SPRTN knockdown and control HeLa cells after treatment with a highly lethal dose of mechlorethamine and recovery over an extended period. Our preliminary data suggest a role for SPRTN in HeLa cells’ response to bifunctional alkylating agents, but more work is necessary to validate these propositions. Nonetheless, this study may support that inhibition of SPRTN in combination with crosslinking chemotherapies could warrant further investigation as a therapeutic strategy for the treatment of certain cancers.

Keywords

Cancer, Chemotherapy, DNA-alkylating agents, DNA-protein crosslinks, DNA damage repair

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