Loss of heterozygosity in FANCG, FANCF and BRIP1 from head and neck squamous cell carcinoma of the oral cavity

MFI2 upregulation promotes malignant progression through EGF/FAK signaling in oral cavity squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the predominant histological type of the head and neck squamous cell carcinoma (HNSCC). By comparing the differentially expressed genes (DEGs) in OSCC-TCGA patients with copy number variations (CNVs) that we identify in OSCC-OncoScan dataset, we herein identified 37 dysregulated candidate genes. Among these potential candidate genes, 26 have been previously reported as dysregulated proteins or genes in HNSCC. Among 11 novel candidates, the overall survival analysis revealed that melanotransferrin (MFI2) is the most significant prognostic molecular in OSCC-TCGA patients. Another independent Taiwanese cohort confirmed that higher MFI2 transcript levels were significantly associated with poor prognosis. Mechanistically, we found that knockdown of MFI2 reduced cell viability, migration and invasion via modulating EGF/FAK signaling in OSCC cells. Collectively, our results support a mechanistic understanding of a novel role for MFI2 in promoting cell invasiveness in OSCC.

Fanconi anemia and dyskeratosis congenita/telomere biology disorders: Two inherited bone marrow failure syndromes with genomic instability

Inherited bone marrow failure syndromes (IBMFS) are a complex and heterogeneous group of genetic diseases. To date, at least 13 IBMFS have been characterized. Their pathophysiology is associated with germline pathogenic variants in genes that affect hematopoiesis. A couple of these diseases also have genomic instability, Fanconi anemia due to DNA damage repair deficiency and dyskeratosis congenita/telomere biology disorders as a result of an alteration in telomere maintenance. Patients can have extramedullary manifestations, including cancer and functional or structural physical abnormalities. Furthermore, the phenotypic spectrum varies from cryptic features to patients with significantly evident manifestations. These diseases require a high index of suspicion and should be considered in any patient with abnormal hematopoiesis, even if extramedullary manifestations are not evident. This review describes the disrupted cellular processes that lead to the affected maintenance of the genome structure, contrasting the dysmorphological and oncological phenotypes of Fanconi anemia and dyskeratosis congenita/telomere biology disorders. Through a dysmorphological analysis, we describe the phenotypic features that allow to make the differential diagnosis and the early identification of patients, even before the onset of hematological or oncological manifestations. From the oncological perspective, we analyzed the spectrum and risks of cancers in patients and carriers.

Mutated FANCA Gene Role in the Modulation of Energy Metabolism and Mitochondrial Dynamics in Head and Neck Squamous Cell Carcinoma

Fanconi Anaemia (FA) is a rare recessive genetic disorder characterized by a defective DNA repair mechanism. Although aplastic anaemia is the principal clinical sign in FA, patients develop a head and neck squamous cell carcinoma (HNSCC) with a frequency 500–700 folds higher than the general population, which appears more aggressive, with survival of under two years. Since FA gene mutations are also associated with a defect in the aerobic metabolism and an increased oxidative stress accumulation, this work aims to evaluate the effect of FANCA mutation on the energy metabolism and the relative mitochondrial quality control pathways in an HNSCC cellular model. Energy metabolism and cellular antioxidant capacities were evaluated by oximetric, luminometric, and spectrophotometric assays. The dynamics of the mitochondrial network, the quality of mitophagy and autophagy, and DNA double-strand damage were analysed by Western blot analysis. Data show that the HNSCC cellular model carrying the FANCA gene mutation displays an altered electron transport between respiratory Complexes I and III that does not depend on the OxPhos protein expression. Moreover, FANCA HNSCC cells show an imbalance between fusion and fission processes and alterations in autophagy and mitophagy pathways. Together, all these alterations associated with the FANCA gene mutation cause cellular energy depletion and a metabolic switch to glycolysis, exacerbating the Warburg effect in HNSCC cells and increasing the growth rate. In addition, the altered DNA repair due to the FANCA mutation causes a higher accumulation of DNA damage in the HNSCC cellular model. In conclusion, changes in energy metabolism and mitochondrial dynamics could explain the strict correlation between HNSCC and FA genes, helping to identify new therapeutic targets.

Age-specific oncogenic pathways in head and neck squamous cell carcinoma - are elderly a different subcategory?

BACKGROUND

In recent clinical practice, an increasing number of elderly patients suffering from head and neck squamous cell carcinoma (HNSCC) of unknown pathophysiology is observed. The majority of HNSCC patients can roughly be divided into three subcategories. First, a small group of young patients who present with variants of genomic aberrations and inheritable diseases like Fanconi anaemia. Second, an increasing population of HPV-related HNSCCs that are regarded as genomic stable tumours with a more favourable prognosis. Though HPV-related tumours used to be more common among younger males, a notable rise in the elderly population is observed. The third subcategory, that of HPV-negative tumours, has been shown to be more heterogeneous with involvement of a variety of oncogenic pathways related to lifestyle factors like smoking and alcohol consumption, often seen in middle-aged males. Some of these pathways could be related to age, such as TP53 alterations, EGFR activation, apoptotic pathway alterations and field cancerization.

CONCLUSIONS

In this narrative review, we provide an overview of established and newly discovered age-specific pathophysiological mechanisms underlying HNSCC. We propose a fourth subcategory of patients with a suspected different pathophysiology: elderly (HPV-negative) HNSCC patients without a history of tobacco and alcohol consumption. In this subcategory, carcinogenesis seems to be a multi-step process based on genomic instability, immunosenescence, cell cycle disruption and telomere shortening. To conclude, we discuss suggestions for future research to fill the knowledge gap about age-dependent HNSCC carcinogenesis.

Characterization of Recurrent Relevant Genes Reveals a Novel Role of RPL36A in Radioresistant Oral Squamous Cell Carcinoma

Simple Summary

Radioresistance is one of the major factors contributing to radiotherapy failure in OSCC. By systematically comparing the prognostic values of all genes in TCGA-OSCC patients with and without radiotherapy, radioresistance-associated genes were identified. Higher RPL36A transcript levels were found to be associated with a poor prognosis only in OSCC patients with radiotherapy in the cohort of TCGA and another independent Taiwanese cohort. RPL36A was then shown to be involved in the regulation of DNA damage, cell cycle and apoptosis, leading to radioresistance. Thus, such integrated studies are expected to be greatly beneficial for the development of new therapeutic interventions for radioresistant OSCC in the future.

Abstract

Radioresistance is one of the major factors that contributes to radiotherapy failure in oral cavity squamous cell carcinoma (OSCC). By comparing the prognostic values of 20,502 genes expressed in patients in The Cancer Genome Atlas (TCGA)-OSCC cohort with (n = 162) and without radiotherapy (n = 118), herein identified 297 genes positively correlated with poor disease-free survival in OSCC patients with radiotherapy as the potential radioresistance-associated genes. Among the potential radioresistance-associated genes, 36 genes were upregulated in cancerous tissues relative to normal tissues. The bioinformatics analysis revealed that 60S ribosomal protein L36a (RPL36A) was the most frequently detected gene involved in radioresistance-associated gene-mediated biological pathways. Then, two independent cohorts (n = 162 and n = 136) were assessed to confirm that higher RPL36A transcript levels were significantly associated with a poor prognosis only in OSCC patients with radiotherapy. Mechanistically, we found that knockdown of RPL36A increased radiosensitivity via sensitizing cells to DNA damage and promoted G2/M cell cycle arrest followed by augmenting the irradiation-induced apoptosis pathway in OSCC cells. Taken together, our study supports the use of large-scale genomic data for identifying specific radioresistance-associated genes and suggests a regulatory role for RPL36A in the development of radioresistance in OSCC.

Type 2 diabetes mellitus promotes the proliferation, metastasis, and suppresses the apoptosis in oral squamous cell carcinoma

BACKGROUND

Our previous study revealed that patients with oral squamous cell carcinoma and concomitant type 2 diabetes mellitus presented a lower 5-year survival rate. Hyperglycemia has been increasingly recognized as a risk factor for more advanced disease and poorer prognosis in patients with oral squamous cell carcinoma. However, its role remains unclear.

METHODS

The expressions of BRIP1, Ki67, E-cadherin, and cleaved caspase-3 were detected by immunohistochemistry in oral squamous cell carcinoma tissues with or without type 2 diabetes mellitus. Cell counting kit-8 assay and wound healing assay were used to determine the proliferative and migratory ability of oral squamous cell carcinoma cells cultured with or without high glucose in vitro. Flow cytometry was applied to distinguish the role of high glucose on the cell cycle and apoptosis rates.

RESULTS

The expression level of Ki67 was elevated while BRIP1, E-cadherin, and cleaved caspase-3 were downregulated in patients with oral squamous cell carcinoma coexisting with diabetes. The cell proliferation and migration in oral squamous cell carcinoma cell lines were significantly enhanced by high glucose. Flow cytometric analysis suggested that high glucose predisposed cancer cells to stay at S/G₂ phase and to exhibit lower apoptosis rates.

CONCLUSION

Our results implicated that type 2 diabetes mellitus may play a crucial role in the development and progression of oral squamous cell carcinoma through hyperglycemia, affecting cancer cell proliferation, migration, and apoptosis. This finding might provide a new direction for the prevention and treatment of oral squamous cell carcinoma.

Improvement in the risk assessment of oral leukoplakia through morphology-related copy number analysis

Oral leukoplakia is the most common type of oral potentially malignant disorders and considered a precursor lesion to oral squamous cell carcinoma. However, a predictor of oral leukoplakia prognosis has not yet been identified. We investigated whether copy number alteration patterns may effectively predict the prognostic outcomes of oral leukoplakia using routinely processed paraffin sections. Comparison of copy number alteration patterns between oral leukoplakia with hyperplasia (HOL, n=22) and dysplasia (DOL, n=21) showed that oral leukoplakia with dysplasia had a higher copy number alteration rate (86%) than oral leukoplakia with hyperplasia (46%). Oral leukoplakia with dysplasia exhibited a wider range of genomic variations across all chromosomes compared with oral leukoplakia with hyperplasia. We also examined a retrospective cohort of 477 patients with oral leukoplakia with hyperplasia with detailed follow-up information. The malignant transformation (MT, n=19) and leukoplakia recurrence (LR, n=253) groups had higher frequencies of aneuploidy events and copy number loss rate than the free of disease (FD, n=205) group. Together, our results revealed the association between the degree of copy number alterations and the histological grade of oral leukoplakia and demonstrated that copy number alteration may be effective for prognosis prediction in oral leukoplakia patients with hyperplasia.