Role of Extracellular Heat Shock Protein 90 Alpha in the Metastasis of Oral Squamous Cell Carcinoma: A Systematic Review

Heat shock proteins (HSPs) are expressed in a variety of cancers in human beings and are correlated with differentiation, proliferation, and metastasis. Head and neck squamous cell carcinomas, like other tumors, are exposed to environmental stress, and lack of oxygen and nutrients, and in such situations, hypoxic inducible factor (HIF) initiates the expression of genes causing angiogenesis, invasion, and metastasis. Extracellular heat shock proteins 90 alpha (eHSP90α) are overexpressed in cancers leading to tumor progression and metastasis. Hence, this review will focus on the role of eHSP90α in the metastasis of oral squamous cell carcinomas (OSCC). Different online databases were scoured for relevant articles from October 2000 to October 2022. A total of 342 articles along with duplicates were excluded. The retrieved 45 articles were studied and 39 of them were found to be not eligible as they lacked intervention and their outcome measures did not match with the present review. The final qualitative evaluation included four articles that fulfilled the eligibility criterion. A definitive expression of HSP90 was implicated, as seen in three studies, suggesting its probable role as a prognostic marker for OSCC, but no conclusive evidence was found. The present review suggests that eHSP90α plays a significant role in OSCC. Though a positive association was found between HSP90 expression and its possible correlation with metastasis, affirmative evidence can only be derived with the conduction of many more research studies and their subsequent synthesis of results.