The Clinical Signification of Claudin-11 Promoter Hypermethylation for Laryngeal Squamous Cell Carcinoma

Aberrant Expression of Claudins in Head and Neck Carcinomas and Their Prognostic and Therapeutic Value: A Narrative Review

Head and neck carcinomas have been associated with poor prognosis. Recent studies have highlighted the role of claudins' expression in tumors throughout the body, and their prognostic and therapeutic role. Understanding the role of claudins and how their expression affects the progression of carcinomas in the head and neck region may allow for advances in the prognosis and management of this type of cancer. Several studies have highlighted the aberrant expression of the proteins in carcinomas in this region. Specifically, the overexpression of claudin-1 and downregulation of claudins-4, -7, and -17 have been linked with poor survival in oral squamous cell carcinoma patients. In laryngeal squamous cell carcinoma, increased levels of claudins-1 and reduced levels of claudins-3, -8, and -11 have been linked with poor outcomes. Targeting these proteins has shown promising outcomes as therapeutic in preclinical studies. However, studies remain extremely limited in nasal and hypopharyngeal carcinomas. In this review, we survey the available literature describing the aberrant expression of various claudins in carcinomas in this region, while highlighting their potential prognostic and therapeutic value. Then, we describe some molecular mechanisms involved in the aberrant expression of claudins and how they can be utilized as therapeutic targets.

Long non-coding RNA HOXA11 antisense RNA upregulates spermatogenesis-associated serine-rich 2-like to enhance cisplatin resistance in laryngeal squamous cell carcinoma by suppressing microRNA-518a

Long noncoding RNAs (LncRNAs) are closely associated with the chemoresistance of laryngeal squamous cell carcinoma (LSCC). Previous studies indicated that HOXA11-AS could function as a vital regulator in human cancers. However, the regulatory mechanisms of HOXA11-AS in the chemoresistance of LSCC remain unclear. In this study, it was found that HOXA11-AS expression was upregulated in cisplatin (CDDP)-resistant LSCC tissues and cells. Loss-of-function assays revealed that HOXA11-AS knockdown inhibited the viability, migration, and invasion, but promoted the apoptosis of CDDP-resistant LSCC cells. Meanwhile, we identified miR-518a as a downstream gene of HOXA11-AS in LSCC, and miR-518a silencing reversed the promotive effect of HOXA11-AS knockdown on CDDP sensitivity of LSCC cells. In addition, miR-518a could inhibit spermatogenesis-associated serine-rich 2-like (SPATS2L) expression by direct interaction, and upregulation of SPATS2L abrogated the inhibitory effect of HOXA11-AS silencing or miR-518a overexpression on CDDP resistance of CDDP-resistant LSCC cells. In sum, our results demonstrated that HOXA11-AS enhanced CDDP resistance of LSCC via miR-518a/SPATS2L axis, which might offer novel therapeutic strategies for CDDP-resistant LSCC.

Comprehensive analysis of expression and prognostic value of the claudin family in human breast cancer

Claudins (CLDN) are structural components of tight junctions that function in paracellular transport and maintain the epithelial barrier function. Altered expression and distribution of members of the claudin family have been implicated in several cancers including breast cancer (BC). We performed a comprehensive analysis of the expression and prognostic value of claudins in BC using various online databases. Compared with normal tissues, CLDN3, 4, 6, 7, 9, and 14 were upregulated in BC tissues, whereas CLDN2, 5, 8, 10, 11, 15, 19, and 20 were downregulated. A high expression of CLDN2, 5, 6, 9, 10, 11, and 14–20 was associated with better relapse-free survival (RFS), whereas a high CLDN3 expression correlated with poor RFS. In addition, a high expression of CLDN3, 4, 14, and 20 was associated with poor overall survival (OS), whereas that of CLDN5 and CLDN11 was linked to a better OS. Although METABRIC and TCGA datasets revealed 22% and 27% gene alterations, respectively, in the members of the claudin family, these were not associated with survival. These findings suggest CLDN3, 5, and 11 could be promising therapeutic targets for patients with BC.

Circulating microRNA-92a-3p in colorectal cancer: a review

Recent studies have found that microRNAs (miRNAs) are present in body fluids, including blood, cerebrospinal fluid, tears, saliva, breast milk, and urine in a stable form, and are called circulating miRNAs. Although their biological roles remain to be determined, circulating miRNAs are considered as mediators of intercellular communication like hormones and cytokines. Because circulating miRNAs can be collected in a non-invasive manner called as "liquid biopsy", they have also been studied as potential biomarkers for early detection, evaluation of therapeutic effects, and prediction of prognosis in various diseases, including cancers. In this review, we focus on the studies on circulating microRNA-92a-3p (miR-92a-3p) in colorectal cancer (CRC), considering their existence form, isolation methods, potential as biomarkers, and roles in CRC development and progression.

Epigenetic Modifications in Head and Neck Cancer

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common human malignancy in the world, with high mortality and poor prognosis for patients. Among the risk factors are tobacco and alcohol intake, human papilloma virus, and also genetic and epigenetic modifications. Many studies show that epigenetic events play an important role in HNSCC development and progression, including DNA methylation, chromatin remodeling, histone posttranslational covalent modifications, and effects of non-coding RNA. Epigenetic modifications may influence silencing of tumor suppressor genes by promoter hypermethylation, regulate transcription by microRNAs and changes in chromatin structure, or induce genome instability through hypomethylation. Moreover, getting to better understand aberrant patterns of methylation may provide biomarkers for early detection and diagnosis, while knowledge about target genes of microRNAs may improve the therapy of HNSCC and extend overall survival. The aim of this review is to present recent studies which demonstrate the role of epigenetic regulation in the development of HNSCC.

Extracellular Vesicles Containing MicroRNA-92a-3p Facilitate Partial Endothelial-Mesenchymal Transition and Angiogenesis in Endothelial Cells

Extracellular vesicles (EVs) are nanometer-sized membranous vesicles used for primitive cell-to-cell communication. We previously reported that colon cancer-derived EVs contain abundant miR-92a-3p and have a pro-angiogenic function. We previously identified Dickkopf-3 (Dkk-3) as a direct target of miR-92a-3p; however, the pro-angiogenic function of miR-92a-3p cannot only be attributed to downregulation of Dkk-3. Therefore, the complete molecular mechanism by which miR-92a-3p exerts pro-angiogenic effects is still unclear. Here, we comprehensively analyzed the gene sets affected by ectopic expression of miR-92a-3p in endothelial cells to elucidate processes underlying EV-induced angiogenesis. We found that the ectopic expression of miR-92a-3p upregulated cell cycle- and mitosis-related gene expression and downregulated adhesion-related gene expression in endothelial cells. We also identified a novel target gene of miR-92a-3p, claudin-11. Claudin-11 belongs to the claudin gene family, which encodes essential components expressed at tight junctions (TJs). Disruption of TJs with a concomitant loss of claudin expression is a significant event in the process of epithelial-to-mesenchymal transition. Our findings have unveiled a new EV-mediated mechanism for tumor angiogenesis through the induction of partial endothelial-to-mesenchymal transition in endothelial cells.

Methylation status of SFRP1, SFRP2, RASSF1A, RARβ and DAPK1 genes in patients with oral squamous cell carcinoma

Our study assessed the methylation status of the SFRP1, SFRP2, RASSF1A, RARβ and DAPK1 genes, which are associated with epigenetic silencing in cancers. In a group of 75 patients with oral squamous cell carcinoma, aberrant methylation was detected using methylation-specific PCR in tumours and matched margins. Our results showed significantly higher methylation frequency in tumours than in surgical margin of SFRP2 (26.6% vs 11.9%, p < 0.05) and DAPK1 (65.3% vs 41.3%, p < 0.01) genes. Moreover, methylation of the SFRP1 and DAPK1 genes was associated with older age. Advanced tumour stages were associated with lower rates of SFRP1 gene methylation. Decreased methylation levels of the SFRP2 and RASSF1A genes were associated with positive N stage. On the contrary, lymph node metastasis were associated with higher methylation rates of RARβ and DAPK1 genes. Patients with a familial history of cancer were associated with more frequently methylated SFRP1, SFRP2 and DAPK1 genes. Hypermethylation of DAPK1 was associated with decreased risk of death in patients. Our results are suggestive, although not conclusive, that some epigenetic changes, especially frequent hypermethylation of SFRP2 and DAPK1 genes, can be useful as potential diagnostic biomarkers of oral cavity cancer. Moreover, estimating the methylation status in surgical margins could become an additional strategy for more accurate treatment methods. Further efforts are needed to identify and validate this finding on a larger patient group and using new advanced methylation testing methods.

Oxidative stress induced by carboplatin promotes apoptosis and inhibits migration of HN-3 cells

Laryngeal squamous cell carcinoma (LSCC) is currently a serious public health problem in China; thus, it is urgent to identify effective treatment strategies for this disease. Previous studies demonstrated that reactive oxygen species (ROS) serve important roles in the apoptosis of LSCC cells. It has also been indicated that carboplatin (CBDCA), a second-generation platinum compound with broad antineoplastic properties, is able to induce oxidative stress to produce ROS, which in turn promotes apoptosis. Thus, the present study investigated if CBDCA is cytotoxic in LSCC cells due to the oxidative stress caused by ROS. Therefore, an MTT assay was performed to determine the cell viability of HN-3 LSCC cells following treatment with different doses of CBDCA. Subsequently, the expression levels of ROS and the rate of apoptosis/necrosis were evaluated in the cells. Following this, the HN-3 cells were co-treated with CBDCA and glutathione (GSH) or H₂O2, followed by an MTT assay, a cell migration assay and western blot analysis. The results demonstrated that CBDCA reduced the viability of HN-3 cells in a time- and dose-dependent manner and promoted the production of ROS and apoptosis at certain doses. Additionally, the combination treatment of CBDCA and H2O2 enhanced the inhibitory effects of CBDCA on cell viability and migration ability, and promoted apoptosis in HN-3 cells; whereas the combined treatment of CBDCA and GSH exerted opposite effects. The results of the present study demonstrated that CBDCA promotes the apoptosis of HN-3 cells through accumulation of ROS, which may provide a novel treatment strategy for treating LSCC.

Mechanism of HN‑3 cell apoptosis induced by carboplatin: Combination of mitochondrial pathway associated with Ca2+ and the nucleus pathways

Laryngeal carcinomas have been recognized as a serious health threat worldwide. In the present study, the mechanism of apoptosis in HN-3 cells induced by carboplatin (CBCDA), a widely used anti-cancer drug, was investigated. The pro-apoptotic effect of CBCDA in HN-3 cells was demonstrated to be time- and dose-dependent. Therefore, the stages of apoptosis were investigated in chronological order. The results demonstrated that excessive generation of cytosolic Ca²⁺ in HN-3 cells was initially triggered when cells were exposed to CBCDA, followed by the appearance of mitochondrial depolarization and oxidative stress, leading to the release of apoptosis-inducing factor. At later stages, expression of caspase-8 was increased due to the apoptotic signals originating from CBCDA-induced DNA damage, as well as caspase-9 and poly ADP ribose polymerase (PARP) expression upregulation. Glutathione decreased the available CBDCA concentration, decreased apoptosis and alleviating oxidative stress, thus reducing the actual effective concentration. Mechanistic research may benefit the rational design of more efficient therapeutic strategies as well as development of novel platinum-based agents.

Analysis of Site-Specific Methylation of Tumor-Related Genes in Head and Neck Cancer: Potential Utility as Biomarkers for Prognosis

Clarifying the epigenetic regulation of tumor-related genes (TRGs) can provide insights into the mechanisms of tumorigenesis and the risk for disease recurrence in HPV-negative head and neck cancers, originating in the hypopharynx, larynx, and oral cavity. We analyzed the methylation status of the promoters of 30 TRGs in 178 HPV-negative head and neck cancer patients using a quantitative methylation-specific PCR. Promoter methylation was correlated with various clinical characteristics and patient survival. The mean number of methylated TRGs was 14.2 (range, 2-25). In the multivariate Cox proportional hazards analysis, the methylation of COL1A2 and VEGFR1 was associated with poor survival for hypopharyngeal cancer, with hazard ratios: 3.19; p = 0.009 and 3.07; p = 0.014, respectively. The methylation of p16 and COL1A2 were independent prognostic factors for poor survival in laryngeal cancer (hazard ratio: 4.55; p = 0.013 and 3.12; p = 0.035, respectively). In patients with oral cancer, the methylation of TAC1 and SSTR1 best correlated with poor survival (hazard ratio: 4.29; p = 0.005 and 5.38; p = 0.029, respectively). Our findings suggest that methylation status of TRGs could serve as important site-specific biomarkers for prediction of clinical outcomes in patients with HPV-negative head and neck cancer.