Somatic Mitochondrial Mutations in Oral Cavity Cancers among Senegalese Patients

Document Type: Research Articles

Authors

1 Department of Maxillofacial Surgery and Stomatology University Hospital Center Aristide le Dantec, Dakar, Senegal.

2 GENGESPOP Team, Department of Animal Biology, Faculty of Science and Technology, Cheikh Anta Diop University, Dakar, Senegal.

3 Department of Animal Biology, Faculty of Science and Technology, Cheikh Anta Diop University, Dakar, Senegal.

4 Cancer Institut, Faculty of Medicine, Pharmacy and Stomatology, Cheikh Anta Diop University, Dakar, Senegal.

Abstract

Background: Somatic mutations affecting the mitochondrial DNA (mtDNA) have been frequently observed in
human cancers and proposed as important oncological biomarkers. However, the exact mtDNA mutations that is
responsible for the pathogenesis of cancer remains unclear. The aim of this study was to investigate somatic mutations
in the MT-CYB and D-Loop regions of mitochondrial DNA (mtDNA) in oral cavity cancers from Senegalese patients.
Methods: MT-CYB and the D-Loop of mtDNA derived from 45 oral cavity cancer tissues and 21 control blood
samples were assessed by PCR and sequencing. The sequences of MT-CYB and the D-Loop from cancerous tissues
were compared with control sequences, and sequence differences were recognized as somatic mutations. Results:
Overall, 389 somatic mtDNA mutations were identified, most of which (79.43%) were located in the D-Loop
region. The majority of base substitution mutations were G-to-A (63.93%) and T-to-C (16.39%) transitions. In the
protein-coding MT-CYB gene, 29 missense mutations were observed. The pathogenic mutation load of MT-CYB was
3.11%. Pathogenic mutations were carried by 25% of patients. pArg76Pro (pArg282Pro in rCRS) was novel and was
the most common pathogenic mutation observed. Conclusion: These results strongly indicate that mtDNA mutations
are a potential marker of oral cavity cancer.

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