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Oral squamous cell carcinoma (OSCC) is considered a disease of the elderly. However, the incidence of OSCC has been increased in young (< 45 yrs) adults over the last years. The etiology and molecular mechanisms of early-onset OSCC remain largely unknown. Copy number alterations (CNA) are nearly ubiquitous in cancer and alter a greater portion of the cancer genome than any somatic genetic aberrations. Our study aimed to analyze the CNA landscape of OSCC in young adults compared with patients over 45 years of age.

Seven nonsmoking and HPV-negative OSCC patients (5 under 45 and 2 over 45 years old; T2-3N1M0) were enrolled. The primary tumor and peripheral blood samples were used to isolate DNA using DNeasy Blood & Tissue Kit (Qiagen, USA). DNA libraries were prepared using SureSelect XT v.7 (Agilent, USA) and sequenced on a NextSeq 500 (Illumina, USA).

Three CNAs were detected in 3 out of 5 young patients (60%), and were not detected in elderly patients: amplification of 6q23.2-25.1 and deletion of 3p26.2-26.3 and 8p23.3 regions. The 6q23.2-25.1 region contains BCLAF1, IFNGR1, SGK1, and TNFAIP3 genes, which were previously described as cancer drivers genes. According to TCGA, 6q24.1-24.3 amplification occurs in 2.4% of young people with head and neck cancer. The 3p26.2-26.3 region includes genes of contactins 4 and 6, which belong to the immunoglobulin superfamily. CNTN4 and СNTN6 genes deletions are observed in 1.5% and 0.8%, respectively, in patients with head and neck cancer (TCGA). DLGAP2 and FBXO25 genes are located in 8p23.3 region and deleted in 10.6% of young cases with head and neck cancer as compared to head and neck cancer patients regardless of age – in 4.1% (TCGA).

Our results indicate that deletion of 8p23.3 region can be involved in early-onset OSCC pathogenesis.