ITGB2-mediated metabolic switch in CAFs promotes OSCC proliferation by oxidation of NADH in mitochondrial oxidative phosphorylation system.

Objectives: Integrins, the coordinator of extracellular and intracellular signaling, are often found to be aberrant in tumors and can reshape the tumor microenvironment. Although previous studies showed that integrin beta 2 (ITGB2) is important for host defense, its expression profile and role in tumors, especially in cancer associated fibroblasts (CAFs) are still unknown. Methods: Immunofluorescence stain and fluorescence activated cell sorting were used to analyze the ITGB2 expression profile in oral squamous cell carcinoma (OSCC). RT-PCR and western blot were used to compare ITGB2 expression in normal fibroblasts (NFs) and cancer associated fibroblasts (CAFs). Clinical data and function-based experiments were used to investigate the promoting tumor growth ability of ITGB2 expressing CAFs. Enhanced glycolysis activity was identified by using bioinformatics analyses and GC/MS assays. MCT1 knockdown OSCC cell lines were constructed to explore the pro-proliferative mechanisms of ITGB2 expressing CAFs in multiple in vitro and in vivo assays. Results: We found that CAFs exhibited significantly higher ITGB2 expression than the matched NFs. In addition, higher ITGB2 expression in CAFs was correlated with higher TNM stages and more Ki67+ tumor cells, indicating its ability to promote OSCC proliferation. Further, co-culture assay demonstrated that ITGB2-mediated lactate release in CAFs promoted OSCC cell proliferation. Mechanically, ITGB2 regulated PI3K/AKT/mTOR pathways to enhance glycolysis activity in CAFs. Accordingly, lactate derived from ITGB2-expressing CAFs was absorbed and metabolized in OSCC to generate NADH, which was then oxidized in the mitochondrial oxidative phosphorylation system (OXPHOS) to produce ATP. Notably, inhibiting the OXPHOS system with metformin delayed the proliferative capacity of OSCC cells cultured in the ITGB2-expressing CAFs medium. Conclusions: Our study uncovered the ITGB2high pro-tumoral CAFs that activated the PI3K/AKT/mTOR axis to promote tumor proliferation in OSCC by NADH oxidation in the mitochondrial oxidative phosphorylation system.

Amino acids signatures of distance-related surgical margins of oral squamous cell carcinoma.

BACKGROUND: Histological assessment of resected margins has some drawbacks. We therefore aimed to identify a panel of metabolic markers for evaluating the surgical margins of oral squamous cell carcinoma during surgery. METHODS: A total of 28 case of OSCC samples were enrolled in the study. Gas chromatography-mass spectrometry based untargeted metabolic analysis was employed to acquire the metabolic perturbation of the distance-related surgical margins in the development group. The acquired MS data were then subjected to univariate and multivariate analysis by MetaboAnalyst. Ultra-high performance liquid chromatography-tandem mass spectrometerbased targeted metabolomics for quantitative analysis of the validation group was performed to verify the results of the development group. Another 60 OSCC patients with dysplastic surgical margins were used to further validate the results of the development group by immunohistochemical examination of key enzyme expression, and correlate them with clinicopathological parameters and clinical outcomes. FINDINGS: We finally identified 4 amino acids as negative margin markers, and 6 amino acids as dysplastic margin markers. IHC analysis showed that asparagine synthetase positive expression in dysplastic surgical margins and its higher expression was correlated with tumor recurrence and local relapse-free survival. INTERPRETATIONS: We developed a panel of metabolic molecular markers to supplement the evaluation of negative and dysplastic margins. FUND: This study was supported by Nanjing Municipal Key Medical Laboratory Constructional Project Funding (Since 2012); Center of Nanjing Clinical Medicine Tumor (Since 2014). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.