DNA demethylation of claudin-4 suppresses migration and invasion in laryngeal squamous carcinoma cells

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.

Gene Expression Profiles of Methyltransferases and Demethylases Associated with Metastasis, Tumor Invasion, CpG73 Methylation, and HPV Status in Head and Neck Squamous Cell Carcinoma

Epigenetic studies on the role of DNA-modifying enzymes in HNSCC tumorigenesis have focused on a single enzyme or a group of enzymes. To acquire a more comprehensive insight into the expression profile of methyltransferases and demethylases, in the present study, we examined the mRNA expression of the DNA methyltransferases DNMT1, DNMT3A, and DNMT3B, the DNA demethylases TET1, TET2, TET3, and TDG, and the RNA methyltransferase TRDMT1 by RT-qPCR in paired tumor-normal tissue samples from HNSCC patients. We characterized their expression patterns in relation to regional lymph node metastasis, invasion, HPV16 infection, and CpG73 methylation. Here, we show that tumors with regional lymph node metastases (pN+) exhibited decreased expression of DNMT1, 3A and 3B, and TET1 and 3 compared to non-metastatic tumors (pN0), suggesting that metastasis requires a distinct expression profile of DNA methyltransferases/demethylases in solid tumors. Furthermore, we identified the effect of perivascular invasion and HPV16 on DNMT3B expression in HNSCC. Finally, the expression of TET2 and TDG was inversely correlated with the hypermethylation of CpG73, which has previously been associated with poorer survival in HNSCC. Our study further confirms the importance of DNA methyltransferases and demethylases as potential prognostic biomarkers as well as molecular therapeutic targets for HNSCC.