Study of Hypoxia-inducible factor-2α expression in the malignant transformation of Oral submucous fibrosis

An enigmatic pathogenetic mechanism of hypoxia inducible factor - 1/2 alpha in the progression of fibrosis of oral submucous fibrosis and its malignant transformation: A systematic review and meta-analysis

OBJECTIVE

Oral submucous fibrosis is a frequently reported potentially malignant disorder characterized by fibrosis and a malignant transformation rate of 7-30%. The role of hypoxia-inducible factor-1/2α in malignant transformation mechanisms of oral submucous fibrosis remains uncharted territory owing to a scarcity of studies. Thus the present systematic review and meta-analysis aimed to determine the role of hypoxia-inducible factor-1/2α in the progression of fibrosis of oral submucous fibrosis and its malignant transformation.

MATERIAL AND METHODS

Using PubMed, Google Scholar, and Cochrane Library databases, full-text articles that investigated hypoxia-inducible factor-1/2α in oral submucous fibrosis were entailed for review. A modified Newcastle-Ottawa scale was employed to evaluate risk of bias in all articles and Review Manager was utilized for meta-analysis.

RESULTS

Eighteen and eight qualified articles respectively were included for qualitative and quantitative data synthesis. Progressive upregulation of hypoxia-inducible factor-1/2α in oral submucous fibrosis is associated with fibrosis-induced carcinogenesis. A Random-effects model uncloaked that oral submucous fibrosis cases with significantly increased expression of hypoxia-inducible factor-1α had an increased associated risk of malignant transformation compared with controls (combined odds ratio 523.83, 95% confidence interval 125.74- 2182.28, p < 0.00001).

CONCLUSION

The existing evidence substantiates the notion that hypoxia-inducible factor-1/2α, a fundamental pathogenetic mechanism of progression and malignant transformation of oral submucous fibrosis in the background of fibrosis.

The Study of Expression of Hypoxia-Inducible Factor-1 Alpha (HIF-1 Alpha) and Hypoxia-Inducible Factor-2 Alpha (HIF-2 Alpha) in Oral Squamous Cell Carcinoma: An Immunohistochemical Study

CONTEXT

Oral cancer is the major cause of mortality and morbidity worldwide. There are many factors that influence the tumor microenvironment that promotes tumorigenesis. Hypoxia is one of the factors that affects the process of angiogenesis by inducing proangiogenic factors to maintain the blood supply which in turn enhances the aggressiveness of the tumor and prognosis of solid tumors such as oral squamous cell carcinoma.

AIM AND OBJECTIVE

The aim of the study was to compare the expression of hypoxia-inducible factor 1α (HIF-1α) and hypoxia-inducible factor 2α (HIF-2α) in various histological grades of oral squamous cell carcinoma immunohistochemically.

METHODOLOGY

Immunohistochemical evaluation of HIF-1α and HIF-2α was done in 90 samples of oral squamous cell carcinoma which were graded histologically into 30 samples each of well, moderately and poorly differentiated squamous cell carcinoma. Statistical evaluation: Statistical analysis was done to study the prognostic significance of the biomarkers.

RESULTS

All the cases showed positivity for expression of HIF-1α and HIF-2α. The number of positive staining in both markers reduced as the tumor severity increased from well to poorly differentiated. The expression of MIL of HIF-2α was higher than HIF 1α and HIF 2α expression was mostly seen in cytoplasmic in well-differentiated and nuclear in both moderately and poorly differentiated OSCC suggestive that HIF-2α is a more specific marker to hypoxia.

CONCLUSION

Hypoxia is an essential factor that triggers other angiogenic switch and inflammatory factors which facilitates the process of tumorigenesis. This is also important for predicting the treatment outcome and prognosis of the patients. HIF-2α is a more sensitive marker that appears to be correlated and could perhaps serve as a good surrogate marker of hypoxia.

Molecular pathways of oral submucous fibrosis and its progression to malignancy

OBJECTIVE

The review aims to comprehend various factors engaged in the alteration of molecular events resulting in Oral submucous fibrosis (OSMF) and its malignant transformation.

DESIGN

Literature pertinent to pathways involved in OSMF were explored in databases such as PubMed, Scopus and Google Scholar. The relevant literature was reviewed and critically appraised in this narrative review.

RESULTS

Areca nut components influence myriad of cellular molecules such as cytokines, growth factors, myofibroblasts, non-coding RNAs and alter their expression. These aberrantly expressed molecules drive the progression of OSMF from localized inflammation to fibrosis of buccal mucosa. The oral tissue suffers from oxidative stress, hypoxia, autophagy, aberration of cell cycle and DNA damage. Apoptosis of epithelial layer results in its atrophy facilitating deeper penetration of areca nut elements. With the advance of disease, epithelial-mesenchymal transition eventuates and promotes dysplasia. The jeopardized expression of various cellular molecules, suppressed apoptosis, along with increased genetic alterations and neovascularization favors the malignant transformation.

CONCLUSION

OSMF is a progressive disorder with complex mechanism of pathogenesis initiated by inflammation of oral mucosa. Continuous habit of areca nut chewing and the resulting insult to the tissues prevents healing process and is destined to debilitating disease which affects the quality of life with a higher probability of progression to malignancy.

Immunohistochemical Biomarkers in Oral Submucous Fibrosis - A Scoping Review

INTRODUCTION

This scoping review was done to study the immunohistochemical biomarkers involved in pathogenesis and malignant transformation (MT) of oral submucous fibrosis (OSF), in literature published from 2010 to 2021.

METHOD

The protocol was adapted from the Joanna Briggs Institute Reviewer's Manual (2017, and reported according to the PRISMA guidelines for Scoping Reviews (PRISMA-ScR).

RESULTS

Eighty-six studies included in this review reported 84 immunohistochemical (IHC) biomarkers in OSF: 9 epithelial markers, 29 connective tissue markers, 22 proliferative markers, and 24 other biomarkers that are transcription factors, cancer stem cell markers, cell signaling markers, proteins, and enzymes. The commonly reported IHC biomarkers were alpha-smooth muscle actin (α-SMA) and E-cadherin (7 articles each) followed by vascular endothelial growth factor (VEGF) and CD34 (6 articles each), p53, p63 and Ki67 (5 articles each). α-SMA, Ki67, CD105, and hTERT were significantly increased in oral squamous cell carcinoma arising in a background of OSF (OSCC-OSF) compared to OSF and normal subjects.

CONCLUSION

The identified surrogate IHC biomarkers reported in OSF in this scoping review require validation with long-term prospective studies to facilitate early diagnosis, for use in risk assessment, and plan appropriate treatment for OSF in clinical practice.

Mechanism of tumour microenvironment in the progression and development of oral cancer

Oral cancer has been a major problem all across the globe, majorly in the developing countries. With a growing emphasis in the field of cancer research, the contribution of the tumour microenvironment has been gaining a lot of importance in identifying the role of components other than the tumour cells that cause the development of cancer, thus changing the outlook. The review will shed light on the studies that describe the role of microenvironment, its components as well as summarize the studies related to their mechanism in the progression of oral cancer. The literature for the review was derived mainly from Google Scholar and PubMed, in particular concentrating on the most recent papers published in 2019 and 2020, by using the keywords "Cancer, Oral Cancer, Metastasis, OSCC, Tumour microenvironment, CAFs, ECM, Cytokines, Hypoxia, Therapeutics targeting the microenvironment". The study provides insight into the world of micro-environmental regulation of oral cancer, the mechanism by which they interact and how to exploit it as a potential therapeutic haven for treating the disease. The components Cancer-Associated Fibroblasts (CAFs), Tumour-associated Macrophages (TAMs), Tumour-associated neutrophils (TANs), Hypoxic environment, myeloid-derived stem cells (MDSCs) and T regulatory (Tregs) cells and underlying mechanisms that control them will be the targets of study to understand the microenvironment.