Quantitative proteomic approaches to identify biomarkers for oral cancer & targeting S100A7 by RNA-mediated interference through NFκβ-mediated pathway

Abstract

Oral cancer is a leading cause of cancer death worldwide. The goal of cancer-screening program is to detect tumours at early stage. Moreover the screening tool must be sufficiently non invasive and inexpensive to allow widespread applicability.Protein biomarker discovery for early detection of Head and Neck Squamous Cell Carcinoma (HNSCC) is a crucial needs to improve patient outcomes. The proteins secreted from cancer tissues are an important molecules which play a vital role, involved in various biological processes related to cancer metastasis and progression which makes a tissue proteome a rich reservoir of potential biomarkers. Tissue based models are suitable for the studies as the differences in the secreted proteins between cancerous and normal tissues can be easily quantified in a controlled manage system. Mass spectrometry-based proteomics has emerged as an excellent tool for identification of Protein biomarkers in different types of cancer. Proteins secreted from cancerous tissue can be a potential biomarkers. We used isobaric Tag for Relative and Absolute Quantitation (iTRAQ) labeling methodology coupled with high resolution mass spectrometry to identify and quantitate secreted proteins from human tissue. In all, we identified 2074 proteins were identified of which 162 and 125 were up and down regulated proteins respectively expressed in HNSCC derived tissue sample as compared to the normal adjacent Tissue. We detected a higher abundance of some previously known markers for HNSCC including, zinc finger protein ZNF142 (11-fold) and peroxiredoxin-1, (PRDX1) (5 fold) etc demonstrating the validity of our approach. We also identified several novel secreted proteins in HNSCC including, S100A7, (7 fold), apolipoprotein D APOD (10-fold) and Thymosin beta-10 TMSB10 (5-fold). IHC-based validation was conducted in HNSCC using tissue microarrays which revealed over expression of S100A7, APOD and TMSB10 in 70% and 65% of the tested cases, respectively. This proteomic analysis will not only serve as a source of candidate biomarkers but will also enhance the current knowledge on the role of the candidate molecules towards disease progression. The selection of S100A7 was done by the earlier research work and it shows that it has a great role in cancer progression. So, by targeting S100A7 inhibits Oral Cancer Growth and Metastasis by RNA mediated Interference and this occurs through NFκβ mediated Pathway both in vitro and in vivo evaluation. To elucidate the role of S100A7 in Oral cancer, we inhibited the activity of S100A7 in an Oral cancer cell line using a siRNA directed silencing. This resulted in a significant decrease in cell viability, colony formation ability and invasive properties of cancer cells. Further studies are ongoing to explore the therapeutic potential of the candidate genes in HNSCC.