Epigenetic actions of environmental factors and promising drugs for cancer therapy

The World of Oral Cancer and Its Risk Factors Viewed from the Aspect of MicroRNA Expression Patterns

Oral cancer is one of the leading causes of death worldwide, with a reported 5-year survival rate of around 50% after treatment. Epigenetic modifications are considered to have a key role in oral carcinogenesis due to histone modifications, aberrant DNA methylation, and altered expression of miRNAs. MicroRNAs (miRNAs) are small non-coding RNAs that have a key role in cancer development by regulating signaling pathways involved in carcinogenesis. MiRNA deregulation identified in oral cancer has led to the idea of using them as potential biomarkers for early diagnosis, prognosis, and the development of novel therapeutic strategies. In recent years, a key role has been observed for risk factors in preventing and treating this malignancy. The purpose of this review is to summarize the recent knowledge about the altered mechanisms of oral cancer due to risk factors and the role of miRNAs in these mechanisms.

The link among microbiota, epigenetics, and disease development

The microbiome is a community of various microorganisms that inhabit or live on the skin of humans/animals, sharing the body space with their hosts. It is a sort of complex ecosystem of trillions of commensals, symbiotic, and pathogenic microorganisms, including trillions of bacteria, archaea, protozoa, fungi, and viruses. The microbiota plays a role in the health and disease status of the host. Their number, species dominance, and viability are dynamic. Their long-term disturbance is usually accompanied by serious diseases such as metabolic disorders, cardiovascular diseases, or even cancer. While epigenetics is a term that refers to different stimuli that induce modifications in gene expression patterns without structural changes in the inherited DNA sequence, these changes can be reversible or even persist for several generations. Epigenetics can be described as cell memory that stores experience against internal and external factors. Results from multiple institutions have contributed to the role and close interaction of both microbiota and epigenetics in disease induction. Understanding the mechanisms of both players enables a better understanding of disease induction and development and also opens the horizon to revolutionary therapeutic approaches. The present review illustrates the roles of diet, microbiome, and epigenetics in the induction of several chronic diseases. In addition, it discusses the application of epigenetic data to develop diagnostic biomarkers and therapeutics and evaluate their safety for patients. Understanding the interaction among all these elements enables the development of innovative preventive/therapeutic approaches for disease control.

Epigenetic mechanisms and the hallmarks of cancer: an intimate affair

Epigenetic mechanisms comprising DNA methylation, histone modifications, and noncoding RNAs affect chromatin structure and regulate gene expression. These mechanisms control normal embryonic development and adult life and their deregulation contributes to several diseases including cancer. The process of tumorigenesis is complex and results from the evolution of different "hallmarks of cancer". Hanahan and Weinberg presented in 2000 and 2011 seminal contributions in the cancer field, first the six hallmarks of cancer and a decade later two additional hallmarks and two enabling characteristics were added. Here, we surmise that epigenetic mechanisms regulate and contribute to every single hallmark in cancer, and thus represent the hallmark of hallmarks in tumorigenesis. Focusing on epigenetics as a major hallmark in cancer formation has profound preventive, therapeutic, and clinical implications.

Reading Cancer: Chromatin Readers as Druggable Targets for Cancer Treatment

The epigenetic machinery deputed to control histone post-translational modifications is frequently dysregulated in cancer cells. With epigenetics being naturally reversible, it represents a good target for therapies directed to restore normal gene expression. Since the discovery of Bromodomain and Extra Terminal (BET) inhibitors, a great effort has been spent investigating the effects of chromatin readers’ inhibition, specifically the class of proteins assigned to bind acetylated and methylated residues. So far, focused studies have been produced on epigenetic regulation, dissecting a specific class of epigenetic-related proteins or investigating epigenetic therapy in a specific tumor type. In this review, recent steps toward drug discovery on the different classes of chromatin readers have been outlined, highlighting the pros and cons of current therapeutic approaches.

Hypermethylation of CCND2 in Lung and Breast Cancer Is a Potential Biomarker and Drug Target

Lung and breast cancer are the leading causes of mortality in women worldwide. The discovery of molecular alterations that underlie these two cancers and corresponding drugs has contributed to precision medicine. We found that CCND2 is a common target in lung and breast cancer. Hypermethylation of the CCND2 gene was reported previously; however, no comprehensive study has investigated the clinical significance of CCND2 alterations and its applications and drug discovery. Genome-wide methylation and quantitative methylation-specific real-time polymerase chain reaction (PCR) showed CCND2 promoter hypermethylation in Taiwanese breast cancer patients. As compared with paired normal tissues and healthy individuals, CCND2 promoter hypermethylation was detected in 40.9% of breast tumors and 44.4% of plasma circulating cell-free DNA of patients. The western cohort of The Cancer Genome Atlas also demonstrated CCND2 promoter hypermethylation in female lung cancer, lung adenocarcinoma, and breast cancer patients and that CCND2 promoter hypermethylation is an independent poor prognostic factor. The cell model assay indicated that CCND2 expression inhibited cancer cell growth and migration ability. The demethylating agent antroquinonol D upregulated CCND2 expression, caused cell cycle arrest, and inhibited cancer cell growth and migration ability. In conclusion, hypermethylation of CCND2 is a potential diagnostic, prognostic marker and drug target, and it is induced by antroquinonol D.