hnRNP K protein is a prognostic marker in head and neck cancer

BM09

 Flávia Amoroso Matos flamatos_bio@yahoo.com.br (1) Adriana Madeira Alvares (2), Ana Maria Mercante(3), Marcelo dos Santos (2) Silvio J.Gutkind(4), Brazilian Head and Neck Genome Project (5), Andréia Machado Leopoldino(1)

(1) Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, FCFRP-USP, Ribeirão Preto, SP, Brazil, (2) Departamento de Biologia Molecular, Hospital Heliópolis, SP, Brazil, (3) Serviço de Anatomia Patológica, Hospital Heliópolis, SP, Brazil, (4) National Institute of Health/NIDCR, Bethesda, MD, USA, (5) GENCAPO Group <http://ctc.fmrp.usp.br/ClinicalGenomics/cp/group.asp>

Introduction: hnRNP K protein has been found in the nucleus and cytoplasm and has been implicated in a variety of cellular functions such as regulation of transcription and translation, RNA splicing, mRNA stability, chromatin remodeling, signal transduction and cell adhesion. The identification of specific protein expression profiles in tumors may lead to the discovery of new markers that can distinguish normal and neoplastic cells, and may also provide new molecular targets in cancer chemoprevention and treatment. hnRNP K is an important regulator of transcription and one of its putative targets is c-Myc gene. Recently, we identified hnRNP K as one protein differentially expressed in tumor samples using proteomic tools. Objectives: To validate hnRNP K expression in cancer we used 93 tumor samples spotted in duplicate on one tissue microarray and analyzed by immunohistochemistry (IHC). We also evaluated its expression in 30 tumors paired with normal counterpart by using immunoblotting technique. Material and Methods: Sixty micrograms of total protein from the tumor and surgical margin samples were separated on 12 % SDS-polyacrylamide gels for immunoblotting analysis. The tissue microarray slide containing 93 samples was prepared by GENCAPO pathologists and gently yielded to us. The antibodies (anti-hnRNPK, anti-B-actina, and anti-rabbit) were purchased from Santa Cruz Biotechnology. The staining system used was Detection System Peroxidase DAB DAKO for IHC and the Super Signal West Pico Chemiluminescent Substrate System (Pierce) or ECL Western Blotting System (GE) for immunoblotting assays. Results: Tissue microarray analyses showed 100% positive tumors for hnRNP K expression, and 68 % of the tumors with hnRNP K nuclear and score 1 or 2 by IHC staining are classified as moderately and well-differentiated. The western blotting confirmed up regulation of hnRNP K in head and neck tumors, and interestingly it was associated with non-survival. Conclusion: Our results showed hnRNP K protein is overexpressed in head and neck cancer and suggest its application as a prognostic marker. Theses findings appoint it as a potential and new therapeutic target in HNSCC. New studies have already been performed to understand how this protein is acting on HNSCC tumorigenesis.