Non-Invasive Saliva-based Detection of Gene Mutations in Oral Cancer Patients by Oral Rub and Rinse Technique

Abstract

Background: Oral Squamous Cell Carcinoma (OSCC) is the most widely reported cancer worldwide. Liquid biopsy, a method that relies on identification of tumor-associated cells and/or cell free nucleic acids from body fluids is becoming increasingly popular in cancer diagnostics. The aim of the study was to evaluate the feasibility of Oral Rub and Rinse (ORR) technique in determining the genetic changes in common biomarkers of oral cancer such as TP53 using DNA obtained from saliva of oral cancer patients. Methods: A total of 15 oral cancer patients were recruited in the study and pre-surgical saliva samples were collected using the ORR technique. Tissue samples included in the study were obtained during the surgical excision of the cancerous oral lesion. Genomic DNA was isolated from the salivary cell plug and the tissues and the TP53 gene was amplified by PCR. The PCR products of all the exons of TP53 (Exons 2 to 11) were electrophoresed on agarose gel, purified and sequenced by Sanger method. The obtained sequences were compared with the reference sequence of TP53 gene. Statistical analysis used: Descriptive statistics were used and reported as frequency and percentage. Results: Capillary sequencing of TP53 gene from tissue DNA revealed the presence of codon 72 c.215C>G (p.Pro72Arg) polymorphism in 10 patients (67%) and a heterozygous mutation at codon 172 c.514 G>T (p.Val172Phe) in 2 patients (13%). Among the 10 samples that showed codon 72 polymorphism, matched salivary DNA was available for 6 samples and 4 out of these showed same genetic change at codon 72. Similarly, of the 3 samples that showed codon 172 mutation, matched salivary DNA was available for 1 sample and the mutation status was identical. Conclusion: The results suggest a potential for clinical applications of ORR technique as an alternative to invasive tissue biopsy for detection of genetic changes in candidate biomarkers in oral cancer.

Review of Disease-Specific microRNAs by Strategically Bridging Genetics and Epigenetics in Oral Squamous Cell Carcinoma

“…In addition, by directly targeting the 3′UTR of its mRNA transcript, miR-155-5p inhibits the expression of ARID2 and is responsible for a substantial decrease in its levels in OSCC. Inhibition of ARID2 expression by miR-155-5p results in a rise in high levels of E-cadherin, vimentin, and snail proteins, indicating that the miR-155-5p/ARID2 axis is essential for promoting tumor growth and mediating OSCC-related EMT and subsequent metastasis [ 34 , 79 ].…”

“…TP53 , also known as the p53 gene, encodes the protein p53, which acts as a tumor suppressor since it plays a crucial role in regulating cell cycle progression, DNA repair, apoptosis, and genomic stability [ 34 , 35 ]. TP53 is considered to be the most mutated gene in OSCC, resulting in uncontrolled cell growth and genomic instability [ 36 ].…”