Sulforaphane Enhances Cytotoxic Effects of Non-Thermal Plasma and Tirapazamine Combination Therapy in Pancreatic Adenocarcinoma Cells

Pancreatic adenocarcinoma remains a highly lethal malignancy with limited effective treatment options, largely due to late-stage detection and rapid progression to metastatic disease. Therapeutic strategies capable of targeting both pre-metastatic and metastatic tumors are critically needed. In this study, we evaluated a combination therapy consisting of non-thermal plasma (NTP), a generator of reactive oxygen and nitrogen species, and the hypoxia-activated prodrug tirapazamine (TPZ). We further investigated whether sulforaphane (SF), a bioactive phytochemical, could further enhance therapeutic efficacy. NTP and TPZ produced strong cytotoxic effects as single agents and demonstrated additive to synergistic activity when combined, reducing viability by 87% in pre-metastatic BxPC-3 cells and achieving near-complete elimination of metastatic AsPC-1 cells. The addition of sulforaphane (10 µM) further enhanced cytotoxicity across all treatment conditions, with Bliss independence analysis indicating additive to synergistic interactions depending on cell line and treatment combination. Sulforaphane-mediated enhancement occurred without restoration of connexin 43 expression or coordinated reversal of epithelial-to-mesenchymal transition markers, and treatments did not induce N-cadherin upregulation or suggest acquisition of invasive characteristics. Together, these findings support NTP + TPZ as a potent combinatorial strategy for pancreatic adenocarcinoma and identify sulforaphane as an effective adjunct that enhances cytotoxic efficacy through mechanisms that remain to be fully elucidated.