The oral cancer with the highest incidence in the world is the squamous cell carcinoma (SCC), totaling more than 90% of all cases of cancer in the oral cavity. The most widely used prognostic factor is the clinical stage of the patient, based on the TNM classification (Malignant Tumors Classification). However, this classification system is not perfect, mainly because tumors with similar morphology and stage behave differently considering its different biological characteristics. Thus, the research of molecular markers involved in the development of human diseases has been the subject of intense research. The discovery that saliva are indicators of systemic disease, molecular profiles favored the development of a new outlook on noninvasive diagnosis: the diagnosis based on the saliva proteomics. In proteomics discovery studies, developed by our research group (1) differential abundance of 137 secreted protein was demonstrated by mass spectrometry in carcinoma cell line when compared to a noncancerous cell line (Kawahara et al. submitted to BMC Biology) and (2) the differential abundance of 44 proteins was found in the saliva of patients with SCC (Winck et al., submitted to Nature Scientific Reports). From these data, further study of proteomics-based targets, we find plenty of 14 proteins in saliva of patients with SCC and the differential abundance of 10 of these proteins was confirmed (Kawahara et al., submitted to the Journal of Proteome Research). However, despite these studies indicates potential candidates for markers, its correlation with the prognosis can not be performed due to the heterogeneous distribution of patients between the different staging. In addition, the high mortality rate compromised the calcutation of patient survival. Thus, the main objective of this project is the quantification of a panel of candidate proteins in the saliva of patients with SCC and the correlation with prognosis and risk of tumor regional metastasis in defined groups. The protein quantitation will be performed in the mass spectrometer LTQ Orbitrap Velos (Thermo Fisher Scientific) coupled with ultra performance liquid chromatography (LC-MS / MS). The candidate markers will be validated by immunohistochemistry (tissue microarray) to assess whether increased expression in saliva reflects the increased expression in SCC tissues and therefore is secreted by tissue or the increased expression is a response of patient organism to the presence of tumor. Proteins differentially abundant will be analyzed using specific software to obtain information about its interaction network, cellular localization and biological processes performed to assist in directing the functional studies of such molecules. It is expected that this project indicate a panel of marker proteins of SCC, contributing to the prognostic evaluation, the patient's risk profile and the possibility of recurrence and also lead to therapeutic intervention strategies.
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