AUTHOR=Patel Krishna , Bhat Firdous Ahmad , Patil Shankargouda , Routray Samapika , Mohanty Neeta , Nair Bipin , Sidransky David , Ganesh Mandakulutur S. , Ray Jay Gopal , Gowda Harsha , Chatterjee Aditi 

TITLE=Whole-Exome Sequencing Analysis of Oral Squamous Cell Carcinoma Delineated by Tobacco Usage Habits

JOURNAL=Frontiers in Oncology

VOLUME=11

YEAR=2021

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2021.660696

DOI=10.3389/fonc.2021.660696

ISSN=2234-943X

ABSTRACT=<p>Oral squamous cell carcinoma (OSCC) is a common cancer of the oral cavity in India. Cigarette smoking and chewing tobacco are known risk factors associated with OSCC. However, genomic alterations in OSCC with varied tobacco consumption history are not well-characterized. In this study, we carried out whole-exome sequencing to characterize the mutational landscape of OSCC tumors from subjects with different tobacco consumption habits. We identified several frequently mutated genes, including <italic>TP53</italic>, <italic>NOTCH1</italic>, <italic>CASP8</italic>, <italic>RYR2</italic>, <italic>LRP2</italic>, <italic>CDKN2A</italic>, and <italic>ATM</italic>. <italic>TP53</italic> and <italic>HRAS</italic> exhibited mutually exclusive mutation patterns. We identified recurrent amplifications in the 1q31, 7q35, 14q11, 22q11, and 22q13 regions and observed amplification of <italic>EGFR</italic> in 25% of samples with tobacco consumption history. We observed genomic alterations in several genes associated with PTK6 signaling. We observed alterations in clinically actionable targets including <italic>ERBB4</italic>, <italic>HRAS</italic>, <italic>EGFR</italic>, <italic>NOTCH1</italic>, <italic>NOTCH4</italic>, and <italic>NOTCH3</italic>. We observed enrichment of signature 29 in 40% of OSCC samples from tobacco chewers. Signature 15 associated with defective DNA mismatch repair was enriched in 80% of OSCC samples. <italic>NOTCH1</italic> was mutated in 36% of samples and harbored truncating as well as missense variants. We observed copy number alterations in 67% of OSCC samples. Several genes associated with non-receptor tyrosine kinase signaling were affected in OSCC. These molecules can serve as potential candidates for therapeutic targeting in OSCC.</p>