Pawlush, Matt L.

Abstract Background: The cellular balance between saturated and monounsaturated fatty acids is a defining feature of tumor lipid metabolism, with SCD1 functioning as a key modulator through the production of MUFAs. Elevated SCD1 activity and MUFA accumulation have been documented in hepatocellular carcinomas, although the consequences of restricting MUFA synthesis have not been fully clarified. Methods: A selective SCD1 inhibitor, SSI-4, was evaluated across established human HCC cell lines and xenograft models. Measurements included cell viability, lipid compositional analyses, and characterization of stress response pathways at both molecular and biochemical levels. The effects of MUFA depletion were studied in vitro and in vivo, with attention to ER stress, apoptosis, ferroptosis markers, and autophagy induction. Results: SSI-4 treatment led to marked reduction in cellular MUFA content and an increase in saturated fatty acid pools. The resulting metabolic stress correlated with activation of unfolded protein response components, caspase-mediated cell death, and the upregulation of ferroptosis-associated genes. Triglyceride and MUFA levels declined precipitously, as confirmed by mass spectrometry-based lipidomics. Tumor growth was suppressed in PDX models and evidence of autophagic flux was apparent in sensitive cell lines. Variability in response highlights metabolic heterogeneity in HCC. Conclusions: Targeted disruption of MUFA biosynthesis inflicts metabolic vulnerability on HCC cells, precipitating membrane alterations and activation of multiple cell death programs. These findings recommend further investigation into metabolic interventions exploiting MUFA depletion, with consideration for stratifying patients according to lipid metabolic phenotypes. Funding: This work is supported by Mayo Clinic Comprehensive Cancer Center and the Jay and Deanie Stein Career Development Award for Cancer Research at Mayo Clinic Jacksonville and the Mayo Clinic Translational Hepatobiliary Cancer SPORE P50CA210964 Career Enhancement Program (CEP) and Florida Department of Health/Florida Cancer Innovation Fund C25C23. Citation Format: Justyna J. Gleba, Victoria N. Rios, Brian M. Necela, Skyeler M. Klinge, Matt L. Pawlush, Mike J. Redig, Aylin Alasonyalilar-Demirer, Han W. Tun, John A. Copland III, . Disrupting tumor lipid homeostasis by MUFA depletion drives cell death in HCC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 7333.

Matrix metalloproteinases (MMPs) are significant drivers of many diseases, including cancer, and are established targets for drug development. Tissue inhibitors of metalloproteinases (TIMPs) are endogenous MMP inhibitors and are being pursued for the development of anti-MMP therapeutics. TIMPs possess many attractive properties for drug candidates, such as complete MMP inhibition, low toxicity, low immunogenicity, and high tissue permeability. However, a major challenge with TIMPs is their rapid clearance from the bloodstream due to their small size. This study explores a method for extending the plasma half-life of the N-terminal domain of TIMP2 (N-TIMP2) by appending it with a long, intrinsically unfolded tail containing Pro, Ala, and Thr (PATylation). We designed and produced two PATylated N-TIMP2 constructs with tail lengths of 100 and 200 amino acids (N-TIMP2-PAT100 and N-TIMP2-PAT200). Both constructs demonstrated higher apparent molecular weights and retained high inhibitory activity against MMP-9. N-TIMP2-PAT200 significantly increased plasma half-life in mice compared to the non-PATylated variant, enhancing its therapeutic potential. PATylation offers distinct advantages for half-life extension, such as fully genetic encoding, monodispersion, and biodegradability. It can be easily applied to N-TIMP2 variants engineered for high affinity and selectivity toward individual MMPs, creating promising candidates for drug development against MMP-related diseases.