Circulating Cell-Free miR-154-5p in Plasma as A Non-Invasive Biomarker for Liquid Biopsy to Predict Survival in Oral Squamous Cell Carcinoma Patients

Earlier studies have demonstrated that clinical dysregulation of hsa-miR-154-5p expression was pathogenic in oral squamous cell carcinoma (OSCC).Currently, there is no blood-based molecular biomarker for risk stratification in OSCC.The present study aims to evaluate the level of circulating miR-154-5p expression in blood plasma for the first time as a potential biomarker for liquid biopsy that could be used for risk stratification and early prediction of the prognosis of OSCC patients.Blood samples (before surgery, CT, RT) were collected from each newly diagnosed OSCC patient with informed consent.In each patient, miR-154-5p expression levels were checked from cell-free blood plasma samples through qRT PCR.After surgery, the follow-up data was collected for the next two years.In the present investigation, during analysis, we first revisited the available datasets obtained from TCGA, dbDMEC database, CancerMIRNome database, and published literature sources and critically analyzed the clinical impact of miR-154-5p expression on OSCC.The results of qRT PCR revealed that miR-154-5p expressions in blood plasma samples were significantly downregulated (p<0.0001)(AUC of 0.900) in OSCC patients (n=25) compared to healthy control individuals (n=10).A comparative study was also performed to check the clinical association and correlation, between circulating miR-154-5p expression signature and conventional histopathological markers, and actual disease outcome (recurrence and survival) of each OSCC patient.Based on Mantel-Cox's survival analysis, the results revealed that OSCC patients with low miR-154-5p levels showed a shorter lifespan.Therefore, the downregulation of miR-154-5p is pathogenic in OSCC and this low level of circulating cell-free miR-154-5p could be a potential candidate biomarker for predicting poor survival in OSCC patients.