Abstract 1690: Sulforaphane enhances cytototoxic effects of novel non-thermal plasma and Tirapazamine combined therapy in pancreatic adenocarcinoma cells

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal cancers, with a five-year survival rate of only 12% due to late detection and limited treatment options. A promising novel combination therapy of Non-Thermal Plasma (NTP) and Tirapazamine (TPZ) has shown success in treating cancers such as melanomas and glioblastoma. This study investigates the efficacy of the novel NTP+TPZ therapy on premetastatic BxPC-3 and metastatic AsPC-1 PDAC cells in vitro and the effects of adding sulforaphane (SF) as a sensitizing agent to enhance the effectiveness of the combined therapy. NTP produces reactive oxygen and nitrogen species (RONS), which induce oxidative stress and apoptosis, while TPZ, a hypoxia-activated prodrug, causes further DNA damage in tumor cells by acting as a topoisomerase II inhibitor. SF was chosen to act as a sensitizing agent since previous studies suggest SF can upregulate Connexin 43 (Cx43) gap junctions, which is an indicator of reversing EMT phenotype, so we hypothesized SF could enhance the therapeutic efficacy of NTP+TPZ. The cytotoxicity of TPZ was determined for both cell lines, yielding IC50 values of 33μM for BxPC-3 and 101μM for AsPC-1. Cell viability assays showed that NTP+TPZ reduced viability by 68.4% in BxPC-3 and 70.1% in AsPC-1 cells, indicating a synergistic effect. Additional trials with SF added at 10 μM in combination with NTP+TPZ resulted in viability decreasing by 86.7% in BxPC-3 and 97.6% in AsPC-1 cells which is an average additional reduction of 32% in BxPC-3 and 40% in AsPC-1 cells compared to treatments without SF. Western blot analyses of EMT markers vimentin and E-cadherin revealed that while SF alone reduced vimentin expression in AsPC-1 cells, it also decreased E-cadherin expression and did not upregulate Cx43 in any SF concentration. In addition, adding SF to the NTP+TPZ therapy unexpectedly stabilized vimentin and decreased E-cadherin expression across multiple conditions, neither of which suggest reversal of the EMT phenotype to explain the increased cytotoxicity of NTP+TPZ. Overall, the data shows that SF increases the cytotoxicity of NTP+TPZ. However, the Western blots show inconsistent loss of vimentin, consistent loss of E-cadherin, and no upregulation of Cx43. While these results suggest SF has potential as an adjunct agent, further investigation is needed to understand the causes of increased cytotoxicity between SF and NTP+TPZ in pancreatic adenocarcinomas. Citation Format: Ishfar Shaan, Brandon Gulledge, Maksym Poplavskyi, Michelle Eubank, Dilbar Alseid, Anya Weinrieb, Gamal Rayan, Shoshanna N. Zucker. Sulforaphane enhances cytototoxic effects of novel non-thermal plasma and Tirapazamine combined therapy in pancreatic adenocarcinoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1690.