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Identification of Differentially Expressed miRNAs in Head and Neck Squamous Cell Carcinoma Implicated in Immune System

Head and Neck Squamous Cell Carcinoma (HNSCC) is the 7th most common malignancy worldwide. The immune system plays a key role in the development, establishment and progression of HNSCC. Cancer cells produce cytokines suppressing cell-mediated antitumour immunity allowing immune escape, that enables the cancer to manifest. Thus, HNSCC creates local immunosuppressive condition, with lower absolute lymphocyte counts than those found in healthy subjects. Impairment of tumour- infiltrating T-lymphocytes affecting clinical outcome has also been reported in HNSCC and other cancers. Small non-coding RNA molecules, microRNAs (miRNAs ; miRs) have been demonstrated to function as important regulators of immune response in both physiological and pathological conditions. Deregulation of miRs is associated with almost all human malignancies and recent studies showed several deregulated miRs in HNSCC. A key role for miR-21 and miR-31 was shown in the modulation of inflammatory response in cancer. Different miRs have been reported to control the development and functions of tumour-associated immune cells. The aim of this study was therefore to identify those miRs that are deregulated in HNSCC as this could indicate potential therapeutic targets for immunotherapy. MicroRNA profiling of fresh HNSCC tumours and of non-malignant tonsils (normal controls) was performed on 19 HNSCC patient samples and 3 normal controls. Total RNA was extracted (Qiagen) and analysed by miR next-generation sequencing (NGS ; Illumina). The expressions of significantly deregulated miRs were confirmed by quantitative reverse-transcription polymerase chain reaction (q-RT-PCR). Several differentially expressed miRNAs implicated in immune response (miR-21, -31, -26b, -27a, -101) in tumour tissues in comparison to controls were identified. While those miRs have already been found in other studies on HNSCC, the relation of the deregulated expression of those miRNAs to the immune system in HNSCC has not been explored so far. The identified miRs represent specific new prognostic and diagnostic biomarkers, and possibly immunotherapeutic targets. Understanding of their function in relation to the regulation of the immune system is important and might help to improve therapy of HNSCC patients.

head neck cancer, miRNA, immunology

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