Prostate-specific membrane antigen (PSMA) is a transmembrane protein expressed in prostate cancer as well as in the neo-vasculature of nonprostatic solid tumors. Here, we determined the expression pattern of PSMA in the vasculature of oral squamous cell carcinoma. Using a previously validated antibody, PSMA staining distribution and cyclooxygenase 2 (COX2) expression status was evaluated in a cohort of patients with squamous cell carcinoma of the oral cavity (n ¼ 96) using immunohistochemistry and was correlated with clinicopathological features as well as outcome. Twenty-four (25%) cases showed no detectable PSMA staining, 48 (50%) demonstrated positive immunoreactivity for PSMA in less than 50% of microvessels and 24 (25%) cases showed strong endothelial PSMA expression in more than 50% of tumor-associated microvessels. High endothelial PSMA expression was associated with greatly reduced survival (18.2 vs 77.3 months; P ¼ 0.0001) and maintained prognostic significance after adjusting for grade and stage in multivariate analysis (hazard ratio ¼ 2.19, P ¼ 0.007). Furthermore, we observed a strong association between endothelial PSMA and cancer cell-specific COX2 expression. In conclusion, we provide the first evidence for the prognostic significance of endothelial PSMA expression in oral squamous cell carcinoma and, suggest a potential interaction between arachidonic acid metabolites and endothelial PSMA expression in the tumor neo-vasculature.

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While a shift in energy metabolism is essential to cancers, the knowledge about the involvement of the mitochondrial genome in tumorigenesis and progression in oral squamous cell carcinoma (OSCC) is still very limited. In this study, we evaluated 37 OSCC tumors and the corresponding benign mucosa tissue pairs by deep sequencing of the complete mitochondrial DNA (mtDNA). After extensive quality control, we identified 287 variants, 137 in tumor and 150 in benign samples exceeding the 1% threshold. Variant heteroplasmy levels were significantly increased in cancer compared to benign tissues (p = 0.0002). Furthermore, pairwise high heteroplasmy frequency difference variants (∆HF% > 20) with potential functional impact were increased in the cancer tissues (p = 0.024). Fourteen mutations were identified in the protein-coding region, out of which thirteen were detected in cancer and only one in benign tissue. After eight years of follow-up, the risk of mortality was higher for patients who harbored at least one ∆HF% > 20 variant in mtDNA protein-coding regions relative to those with no mutations (HR = 4.6, (95%CI = 1.3–17); p = 0.019 in primary tumor carriers). Haplogroup affiliation showed an impact on survival time, which however needs confirmation in a larger study. In conclusion, we observed a significantly higher accumulation of somatic mutations in the cancer tissues associated with a worse prognosis.

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