RNA Sequencing in Potentially Malignant Disorders

*Ramya Ramadoss, Rajkumar Krishnan, Lekshmy Jayan and Priyadharini Shankaran*

#### **Abstract**

RNA sequencing is a molecular technique which utilizes next generation sequencing to identify and quantify ribonucleic acid (RNA) in a given sample. This technique is utilized in the detection of changes in gene expression. Potentially malignant oral disorders are one of the most troublesome lesions seen in the oral cavity which predisposes to the development of oral cancer. Though there are many methods employed in the diagnosis of these disorders, biopsy followed by histological examination is the gold standard procedure followed in the diagnosis. RNA sequencing has been receiving attention among researchers. Many studies have been conducted to analyze the application of RNA sequencing in the diagnosis of PMODs as well as in the malignant transformation to oral squamous cell carcinoma. The article attempts to summarize the progress in RNA sequencing pertaining to Potentially malignant disorders.

**Keywords:** RNA sequencing, Potentially Malignant Disorders, Diagnostic Markers, Molecular Diagnosis, Oral cancer

#### **1. Introduction**

RNA sequencing is a molecular technique which utilizes next generation sequencing to identify and quantify ribonucleic acid (RNA) in a given sample. This technique is utilized in the detection of changes in gene expression [1]. It also detects mutations or single nucleotide polymorphisms etc. RNA sequencing has greatly replaced cDNA microarray owing to more precise reproduction of using lanes and flow cells. Another added bonus is that this method allows de novo reconstruction of the transcriptome i.e., unknown material can be analyzed [2].

Potentially malignant oral disorders are one of the most troublesome lesions seen in the oral cavity which predisposes to the development of oral cancer. As the saying goes, "prevention is better than cure" it is better to identify and tackle the lesion in the premalignant stage rather than once cancer has developed. Sarode et al. (2014) defined OSCC prone disorders as 'It is a group of disorders of varying etiologies, usually tobacco; characterized by mutagen-associated, spontaneous or hereditary alterations or mutations in the genetic material of oral epithelial cells with or without clinical and histomorphological alterations that may lead to oral squamous cell carcinoma transformation' [3].

Though there are many methods employed in the diagnosis of these disorders, biopsy followed by histological examination is the gold standard procedure followed in the diagnosis [4]. Molecular techniques like PCR, ELISA are attempted in identifying a sensitive and specific marker. A handful of markers (salivary and serum) are attempted but none are identified to lack both specificity and sensitivity ideally required by a diagnostic marker. Microarray has emerged as a promising method as it helped in comparison and analysis of multiple samples at the same time. RNA sequencing has been receiving attention among researchers [3, 4]. Many studies have been conducted to analyze the application of RNA sequencing in the diagnosis of PMODs as well as in the malignant transformation to oral squamous cell carcinoma [5, 6].
