Expression pattern of class I histone deacetylases in vulvar intraepithelial neoplasia and vulvar cancer: a tissue microarray study

Upregulated histone deacetylase 2 gene correlates with the progression of oral squamous cell carcinoma

BACKGROUND

Histone deacetylases (HDACs) are considered as an essential regulator of cellular proliferation, differentiation, and apoptosis. The HDAC2 enzyme of Class I HDACs plays an important role in tumor progression of human malignancies.

OBJECTIVE

The aim of the present study was to analyze the HDAC2 gene expression in pre-oral cancer and oral squamous cell carcinoma (OSCC), and its association with clinico-pathological features.

METHODS

The HDAC2 protein expression was analyzed through the immunohistochemistry and western blot techniques in 82 oral pre-malignant, 90 OSCC, and 16 normal control tissues. qRT-PCR was used to quantify the mRNA fold change in all groups.

RESULTS

The HDAC2 protein and mRNA levels were significantly higher in OSCC and pre-oral cancer groups compared to the controls. Immunostaining of HDAC2 protein was enhanced in 84.4% of OSCC and 67.1% of pre-cancerous tissue sections (p< 0.01). The mean protein level was analyzed as 1.96 ± 0.44 in oral carcinoma, 1.61 ± 0.39 in pre-cancer and 0.96 ± 0.10 in control tissues. In addition, HDAC2 mean protein level was associated with histological differentiation (OR = 25, p< 0.05) and tumor-node-metastasis (TNM) stages (OR = 6.2, p< 0.05) of OSCC patients.

CONCLUSIONS

The upregulated HDAC2 gene in pre-cancer and OSCC tissues indicates its crucial role in the transformation of pre-malignant to malignant carcinoma. It could be a potential cancer biomarker of prognosis and targeted therapy in OSCC.

Unraveling the Epigenetic Role and Clinical Impact of Histone Deacetylases in Neoplasia

Histone deacetylases (HDACs) have long been implicated in tumorigenesis and tumor progression demonstrating their important participation in neoplasia. Therefore, numerous studies have been performed, highlighting the mechanism of HDACs action in tumor cells and demonstrating the potential role of HDAC inhibitors in the treatment of different cancer types. The outcome of these studies further delineated and strengthened the solid role that HDACs and epigenetic modifications exert in neoplasia. These results have spread promise regarding the potential use of HDACs as prospective therapeutic targets. Nevertheless, the clinical significance of HDAC expression and their use as biomarkers in cancer has not been extensively elucidated. The aim of our study is to emphasize the clinical significance of HDAC isoforms expression in different tumor types and the correlations noted between the clinicopathological parameters of tumors and patient outcomes. We further discuss the obstacles that the next generation HDAC inhibitors need to overcome, for them to become more potent.

Precursor lesions of vulvar squamous cell carcinoma - histology and biomarkers: A systematic review

The precursor lesion of vulvar squamous cell carcinoma (VSCC), namely vulvar intraepithelial neoplasia (VIN), is classified as: human papillomavirus (HPV)-related high grade squamous intraepithelial lesion (HSIL), and HPV-independent differentiated VIN (dVIN). Traditionally, histology and immunohistochemistry (IHC) have been the basis of diagnosis and classification of VIN. HSIL shows conspicuous histological atypia, and positivity on p16-IHC, whereas dVIN shows less obvious histological atypia, and overexpression or null-pattern on p53-IHC. For both types of VIN, other diagnostic immunohistochemical markers have also been evaluated. Molecular characterization of VIN has been attempted in few recent studies, and novel genotypic subtypes of HPV-independent VSCC and VIN have been identified. This systematic review appraises the VSCC precursors identified so far, focusing on histology and biomarkers (immunohistochemical and molecular). To gain further insights into the carcinogenesis and to identify additional potential biomarkers, gene expression omnibus (GEO) datasets on VSCC were analyzed; the results are presented.

Clinical and molecular classification of vulvar squamous pre-cancers

Vulvar intraepithelial neoplasia (VIN) is a precursor to vulvar squamous cell carcinoma and is defined histopathologically by the presence of atypia. VIN has been classified into two types: usual vulvar intraepithelial neoplasia (uVIN), which is also referred to as a vulvar high-grade squamous intra-epithelial lesion (HSIL), and differentiated VIN (dVIN). The former is associated with chronic infection by sub-types of the human papilloma virus (HPV), whereas dVIN is HPV-independent and frequently associated with lichen sclerosus. The distinction is important because dVIN has a greater risk of, and more rapid transit to, vulvar squamous cell carcinoma. Furthermore, dVIN-associated vulvar cancers have an increased risk of recurrence and higher mortality than those arising from HSIL. Molecular characterization of vulvar squamous cell carcinoma precursors using next-generation sequencing is a relatively novel, but rapidly advancing field. This review appraises recent studies that have investigated the risks of progression to vulvar malignancy associated with HSIL and dVIN, the prognosis of HPV-dependent and HPV-independent vulvar squamous cell carcinomas, and conducted next generation sequencing mutation analyses to elucidate the genomic profiles underlying VIN. These studies suggest that HSIL and dVIN are characterized by different underlying molecular alterations that may have important implications for treatment and follow-up of women diagnosed with vulvar squamous cell cancer.

Overexpression of Cancer-Associated Genes via Epigenetic Derepression Mechanisms in Gynecologic Cancer

Like other cancers, most gynecologic cancers are caused by aberrant expression of cancer-related genes. Epigenetics is one of the most important gene expression mechanisms, which contribute to cancer development and progression by regulating cancer-related genes. Since the discovery of differential gene expression patterns in cancer cells when compared with normal cells, extensive efforts have been made to explore the origins of abnormal gene expression in cancer. Epigenetics, the study of inheritable changes in gene expression that do not alter DNA sequence is a key area of this research. DNA methylation and histone modification are well-known epigenetic mechanisms, while microRNAs and alternative splicing have recently been identified as important regulators of epigenetic mechanisms. These mechanisms not only affect specific target gene expression but also regulate the functioning of other epigenetic mechanisms. Moreover, these diverse epigenetic regulations occur simultaneously. Epigenetic regulation of gene expression is extraordinarily complicated and all epigenetic mechanisms to be studied at once to determine the exact gene regulation mechanisms. Traditionally, the contribution of epigenetics to cancer is thought to be mediated through the inactivation of tumor suppressor genes expression. But recently, it is arising that some oncogenes or cancer-promoting genes (CPGs) are overexpressed in diverse type of cancers through epigenetic derepression mechanism, such as DNA and histone demethylation. Epigenetic derepression arises from diverse epigenetic changes, and all of these mechanisms actively interact with each other to increase oncogenes or CPGs expression in cancer cell. Oncogenes or CPGs overexpressed through epigenetic derepression can initiate cancer development, and accumulation of these abnormal epigenetic changes makes cancer more aggressive and treatment resistance. This review discusses epigenetic mechanisms involved in the overexpression of oncogenes or CPGs via epigenetic derepression in gynecologic cancers. Therefore, improved understanding of these epigenetic mechanisms will provide new targets for gynecologic cancer treatment.

The expression of histone deacetylase 1, but not other class I histone deacetylases, is significantly increased in endometriosis

Class I histone deacetylases (HDACs-1-3) play an important role in steroid hormone-dependent gene expression and in modulating cell survival and proliferation. We analyzed their expression in a tissue microarray including 74 endometriosis samples and 30 normal endometrium controls. The mean HDAC-1 immunoreactivity score (IRS ± standard deviation) was 7.6 ± 2.5 in endometriosis and 5.3 ± 2.3 in normal endometrium (P < .001). In contrast, the IRSs of HDAC-2 and -3 were 11.7 ± 0.7 and 11.8 ± 1.1 in endometriosis and 11.6 ± 1.0 and 11.9 ± 0.4 in normal endometrium (P = .7 and P = .2), respectively. Significant correlations were found between HDAC-1 and estrogen (-alpha/-beta) and progesterone receptor expression. In conclusion, HDAC-1, but not HDAC-2/-3, was significantly increased in endometriosis and associated with steroid hormone receptor expression that may reflect interdependence. In context with the literature, specific inhibitors of HDAC-1 may have inhibitory activities similar to those of broad-spectrum HDAC inhibitors and may be clinically tolerated, which would increase their chance as an option in the treatment of endometriosis.