Interferon stimulated gene-ISG15 is a potential diagnostic biomarker in oral squamous cell carcinomas

Cancer diagnostic biomarkers have a wide range of applications that include early detection of oral precancerous lesions and oral squamous cell carcinomas, and assessing the metastatic status of lesions. The interferon stimulated ISG15 gene encodes an ubiquitin-like protein, which conjugates to stabilize activation status of associated proteins. Hence a deregulated expression of ISG15 may promote carcinogenesis. Indeed overexpression of ISG15 has been observed in several cancers and hence it has been proposed as a strong candidate cancer diagnostic biomarker. Given the emerging relationship between malignant transformation and ISG15, we sought to examine the expression pattern of this gene in tumor biopsies of oral squamous cell carcinoma (OSCC) tissues collected from Indian patients.

Total RNA isolated from thirty oral squamous cell carcinoma tissue biopsy samples were subjected to semi-quantitative RT-PCR with ISG15 specific primers to elucidate the expression level.

Of the thirty oral squamous cell carcinomas that were analyzed, ISG15 expression was found in twenty four samples (80%). Twelve samples expressed low level of ISG15, six of them expressed moderately, while the rest of them expressed very high level of ISG15.

To the best of our knowledge, the results show for the first time an overexpression of ISG15 in up to 80% of oral squamous cell carcinoma tissues collected from Indian patients. Hence ISG15 may be explored for the possibility of use as a high confidence diagnostic biomarker in oral cancers.