Abstract 3620: N-myristoylation inhibition reduces angiogenesis and cancer cell migration

Abstract Myristoylation is the modification of proteins by the 14-carbon fatty acid myristate. In humans, two N-myristoyltransferases (NMT1 and NMT2) catalyze myristate transfer onto >200 proteins to regulate membrane binding and signal transduction. The pan-NMT inhibitor PCLX-001 has been in phase I clinical trials over a year for the treatment of lymphoma and advanced solid malignancies. Lack of myristoylation promotes the degradation of numerous normally myristoylated proteins like the proto-oncogenic Src family kinases (SFKs). SFKs like Src and Lyn are essential for downstream signaling of Vascular Endothelial Growth Factor (VEGF) and Epidermal Growth Factor (EGF) receptor tyrosine kinases. Thus, SFKs are critical for angiogenesis and cell motility. Angiogenesis is essential for tumor growth and dissemination of cancer cells to distal locations. VEGF-induced angiogenesis requires Src activation, suggesting that PCLX-001 may have antiangiogenic properties. SFKs also promote cell migration/metastasis, the leading cause of cancer-associated mortality. Lyn SFK knockdown was shown to reduce breast cancer migration and neighbouring tissue invasion, suggesting that PCLX-001 may also inhibit cell migration/metastasis. We investigated the antiangiogenic properties of PCLX-001 in vitro using HUVEC umbilical cord cells. PCLX-001 treatment significantly reduced HUVEC sprouting and tube-formation to levels lower than two FDA-approved angiogenesis inhibitors Sorafenib and Sunitinib. PCLX-001 also significantly reduced neo-vascularisation in vivo at lower concentrations than these two drugs using a chicken chorioallantoic membrane model, demonstrating the high potential of myristoylation inhibitors to reduce angiogenesis. We then validated our observations in vivo using a HT-1376 bladder mouse xenograft model. Tumors from mice treated for 28 days at increasing PCLX-001 concentrations showed significant reduction of Src, Lyn, and VEGF receptor protein levels as measured by immunohistochemistry, further validating PCLX-001 effect in vivo. We hypothesize that PCLX-001 acts downstream of VEGF/EGF receptors by inducing degradation of un-myristoylated SFKs. We confirmed this by knocking down NMT1 or treating breast cancer cells with PCLX-001 and found that both significantly reduced SFK protein levels. In a wound-healing assay using PCLX-001, we observed significant dose-dependent cell migration inhibition. PCLX-001 also dose-dependently reduced migration and invasion in transwell migration/invasion assays, indicating that myristoylation is required for optimal migration and potentially cancer cell metastasis. Overall, by lowering SFK levels, PCLX-001 reduces angiogenesis, cell migration/invasion, and thus potentially cancer metastasis. Reducing these classical cancer hallmarks in malignant cells may benefit a wide array of cancer patients and ultimately improve cancer treatment outcomes. Citation Format: Rony Pain, Erwan Beauchamp, Katia Carmine-Simmen, Jay Gamma, Rebecca Reif, Abul Azad, Allan Murray, John Lewis, Luc Berthiaume. N-myristoylation inhibition reduces angiogenesis and cancer cell migration. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3620.