Abstract LB297: MCT1 regulates the progression of early invasive oral squamous cell carcinoma

Abstract Most oral squamous cell carcinomas (OSCC) progress through clinically identifiable stages, starting from premalignant epithelial dysplasia to early invasive OSCC. How cells transform during this process is largely unknown. High monocarboxylate transporter 1 (MCT1; SLC16A1) expression is correlated with poor outcomes in OSCC patients, where it is thought to promote tumor growth by supporting metabolic coupling between cancer cells and tumor stroma. Because expression of MCT1 markedly increases in the progression from normal to dysplasia to early invasive OSCC, we sought to determine whether MCT1 plays a role in early invasive disease. We knocked out SLC16A1 via CRISPR/Cas9 in an OSCC cell line to determine the effects of MCT1 on cell invasion in three-dimensional organotypic culture (OTC) assays. An MCT1 inhibitor, AZD3965, was used to assess invasion in OTCs and disease progression in a mouse model of oral carcinogenesis. Knockout of MCT1 or treatment with AZD3965 dramatically decreased the invasion of oral cancer cells compared to wild-type cells or untreated controls, respectively, in OTC assays. In addition to reducing the number of oral lesions in mice treated with the carcinogen 4-NQO, AZD3965 also reduced the development of dysplasia and progression toward early invasion in AZD3965-treated mice compared to untreated 4-NQO controls. To identify invasive pathways regulated by MCT1, we used the Nanostring GeoMx Digital Spatial Profiler platform to analyze changes in gene expression between OTC samples using wild type and MCT1 knockout cell lines. We found loss of MCT1 led to alterations in glycolytic metabolism with compensatory changes in mitochondrial activity and increased cholesterol and fatty acid synthesis. Metabolic changes between wild type and knockout cells were confirmed using Seahorse assays and immunoblotting; changes in OTC samples were confirmed by immunofluorescence staining. Our data suggest that MCT1 plays a key role in breaching the basement membrane and facilitating tumor cell migration and invasion by regulating changes in glucose and mitochondrial metabolic pathways. Our data also suggest potential metabolic vulnerabilities in oral cancer cells can be exploited by targeting cholesterol and lipid synthesis pathways in combination with MCT1 inhibition. Our ongoing work involves further assessment of mechanisms regulated by MCT1 to promote progression of oral cancer, including ATAC-seq to assess epigenetic changes, metabolite analysis and metabolic tracing, and the development of relevant mouse models. Citation Format: Erin B. Dickerson, Ethan J. Wong, Ali Khammanivong, Olanrewaju Ajeigbe, Bailey Anderson, Aneri Shah, Ravi Maisuria, Lester R. Drewes, Isha Mutreja, Raj Gopalakrishnan. MCT1 regulates the progression of early invasive oral squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB297.