Functional analysis of ESM1 by siRNA knockdown in primary and metastatic head and neck cancer cells
ESM1 (endothelial cell‐specific molecule‐1), also known as Endocan, was originally cloned from a human endothelial cell cDNA library in 1996.9 ESM1 is a 50 kDa soluble proteoglycan; the mature polypeptide consists of 165 amino acids and includes a single dermatan sulfate chain covalently linked to the serine residue at position 137.9 ESM1 has been identified as a dermatan sulfate proteoglycan that can circulate freely in the bloodstream.11 Overexpression of ESM1 has an important role in tumor growth, development, and angiogenesis.12 It is now known that ESM1 is expressed in several types of cancer and that it affects cell survival and migration. Recent studies showed that ESM1 expression significantly affects the proliferation and migration of cells in colorectal, gastric, nasopharyngeal, and hepatocellular carcinomas.15 To the best of our knowledge, to date, there has not been any study of ESM1 in cancers of the head and neck. The head and neck region of the body is rich in lymphatic vessels, and nodal metastases here are prevalent.
Investigation of the effect of ESM1 in primary tumors and metastases may result in its use as a prognostic marker for patients with head and neck cancer. To this end, we transfected cells with siRNA to silence ESM1 expression. Subsequently, we investigated the effect of this gene through various molecular analyses. We characterized gene expression levels as well as cellular proliferation and migration to better understand the effects of this gene in the cell lines. The results of these analyses are an important first step in illuminating the basic effects of ESM1 in head and neck cancer.