Hypermethylation of Promoter Region of LATS1 - a CDK Interacting Protein in Oral Squamous Cell Carcinomas - a Pilot Study in India

Background: Epigenetic silencing of tumor suppressor genes due to promoter hypermethylation is one of thefrequent mechanisms observed in cancers. Hypermethylation of several tumor suppressor genes involved in cellcycle regulation has been reported in many types of tumors including oral squamous cell carcinomas. LATS1(Large Tumor Suppressor, isoform 1) is a novel tumor suppressor gene that regulates cell cycle progression byforming complexes with the cyclin dependent kinase, CDK1. Promoter hypermethylation of the LATS1 gene hasbeen observed in several carcinomas and also has been linked with prognosis. However, the methylation statusof LATS1 in oral squamous cell carcinomas is not known. As oral cancer is one of the most prevalent forms ofcancer in India, the present study was designed to investigate the methylation status of LATS1 promoter andassociate it with histopathological findings in order to determine any associations of the genetic status withstage of differentiation. Materials and
Methods: Tumor chromosomal DNA isolated from biopsy tissues ofthirteen oral squamous cell carcinoma biopsy tissues were subjected to digestion with methylation sensitiveHpaII enzyme followed by amplification with primers flanking CCGG motifs in promoter region of LATS1gene. The PCR amplicons were subsequently subjected to agarose gel electrophoresis along with undigestedamplification control.
Results: HpaII enzyme based methylation sensitive PCR identified LATS1 promoterhypermethylation in seven out of thirteen oral squamous cell carcinoma samples.
Conclusions: The identificationof LATS1 promoter hypermethylation in seven oral squamous cell carcinoma samples (54%), which includedone sample with epithelial dysplasia, two early invasive and one moderately differentiated lesions indicatesthat the hypermethylation of this gene may be one of the early event during carcinogenesis. To the best of ourknowledge, this is the first study to have explored and identified positive association between LATS1 promoterhypermethylation with histopathological features in oral squamous cell carcinomas.