Somatic SDHA mutations in paragangliomas in siblings: Case report of 2 cases

Application value of whole exome sequencing in screening and identifying novel mutations of hypopharyngeal cancer

The research on targeted therapy of hypopharyngeal cancer is very scarce. The discovery of new targeted driver genes will promote the progress of hypopharyngeal cancer therapy to a great extent. In our research, whole-exome sequencing in 10 patients with hypopharyngeal cancer was performed to identify single nucleotide variations (SNVs) and insertions and deletions (INDELs). American College of Medical Genetics and Genomics (ACMG) guidelines were used to evaluate the pathogenicity of the selected variants. 8113 mutation sites in 5326 genes were identified after strict screening. We identified 72 pathogenic mutations in 53 genes according to the ACMG guidelines. Gene Ontology (GO) annotation and KEGG enrichment analysis show the effect of these genes on cancer. Protein-protein interaction (PPI) was analyzed by string online software. The validation results of the ualcan database showed that 22 of the 53 genes may be related to the poor prognosis of patients with hypopharyngeal cancer. RBM20 has the most significant correlation with hypopharyngeal cancer, and it is likely to be the driver gene of hypopharyngeal cancer. In conclusion, we found possible therapeutic targets for hypopharyngeal cancer, especially RBM20 and KMT2C. Our study provides a basis for the pathogenesis and targeted therapy of hypopharyngeal cancer.

Mitochondrial respiratory complexes: Significance in human mitochondrial disorders and cancers

Mitochondria are pivotal organelles that govern cellular energy production through the oxidative phosphorylation system utilizing five respiratory complexes. In addition, mitochondria also contribute to various critical signaling pathways including apoptosis, damage-associated molecular patterns, calcium homeostasis, lipid, and amino acid biosynthesis. Among these diverse functions, the energy generation program oversee by mitochondria represents an immaculate orchestration and functional coordination between the mitochondria and nuclear encoded molecules. Perturbation in this program through respiratory complexes' alteration results in the manifestation of various mitochondrial disorders and malignancy, which is alarmingly becoming evident in the recent literature. Considering the clinical relevance and importance of this emerging medical problem, this review sheds light on the timing and nature of molecular alterations in various respiratory complexes and their functional consequences observed in various mitochondrial disorders and human cancers. Finally, we discussed how this wealth of information could be exploited and tailored to develop respiratory complex targeted personalized therapeutics and biomarkers for better management of various incurable human mitochondrial disorders and cancers.

Somatic Mutation Profiling in Head and Neck Paragangliomas

CONTEXT

Head and neck paragangliomas (HNPGLs) are rare neoplasms with a high degree of heritability. Paragangliomas present as polygenic diseases caused by combined alterations in multiple genes; however, many driver changes remain unknown.

OBJECTIVE

The objective of the study was to analyze somatic mutation profiles in HNPGLs.

METHODS

Whole-exome sequencing of 42 tumors and matched normal tissues obtained from Russian patients with HNPGLs was carried out. Somatic mutation profiling included variant calling and utilizing MutSig and SigProfiler packages.

RESULTS

57% of patients harbored germline and somatic variants in paraganglioma (PGL) susceptibility genes or potentially related genes. Somatic variants in novel genes were found in 17% of patients without mutations in any known PGL-related genes. The studied cohort was characterized by 6 significantly mutated genes: SDHD, BCAS4, SLC25A14, RBM3, TP53, and ASCC1, as well as 4 COSMIC single base substitutions (SBS)-96 mutational signatures (SBS5, SBS29, SBS1, and SBS7b). Tumors with germline variants specifically displayed SBS11 and SBS19, when an SBS33-specific mutational signature was identified for cases without those. Beta allele frequency analysis of copy number variations revealed loss of heterozygosity of the wild-type allele in 1 patient with germline mutation c.287-2A>G in the SDHB gene. In patients with germline mutation c.A305G in the SDHD gene, frequent potential loss of chromosome 11 was observed.

CONCLUSION

These results give an understanding of somatic changes and the mutational landscape associated with HNPGLs and are important for the identification of molecular mechanisms involved in tumor development.