Systemic aftermaths of tobacco addiction on the physiological composite of human secretome and the prognostic potential of U2AF26 in oral cancers

Objectives

Tobacco chewing and smoking practices have been a common trend among human populations. Tobacco addiction is a commonly known etiology for oral cancers. The study showcases a clinical case (I_5; a 36y male) with a chronic inflamed persistent oral lesion and positive addiction history of tobacco chewing & smoking to screen out a prognostic target for oral malignancy.

Method

Two-dimensional gel electrophoreses (2DE), using the depleted serum proteome of I_5 and healthy control, were performed for resolving the complex protein repertoire of the secretome. MALDI-TOF-MS and in-silico peptide analyses were used for characterizing the 2DE protein spot of interest. The relative real-time PCR, used for validation of the modulations in the expression of the gene of interest, involved oral cancer (n = 14) and pre-cancer lesions (n = 9). The adjacent normal tissues (encircling oral diseased lesions) and healthy oral epithelia were used as the controls.

Results

The comparative analysis of 2DE profiles uncovered substantial disparities between the depleted secretome of the case (I_5) and the control. The qualitative differential spot ‘a’ (absent in I_5 but present in healthy control) corresponding to HNCUP U2AF26-III was found to down-regulate in the serum proteome of OSCC cases (both tobacco addicts & non-addicts) compared to healthy non-addicts. Also, the expression of the nccpU2AF26 showed significant down-regulation in oral-precancerous and cancerous samples in comparison with the healthy oral epithelia while the expression levels were found to be significantly up-regulated when lesions were compared with their adjacent normal tissues.

Conclusions

The serum proteome of a chronic tobacco addict deficits in multiple proteins constituting the physiological human secretome. The U2AF26-III may function as a prognostic biomarker and therapeutic target for oral malignancies. Also, a non-canonical transcript (nccpU2AF26) lacking exon 3 and 4 was identified to be present in normal oral epithelia and POLs, highlighting the need for rigorous analyses of the role(s) played by U2AF26 non-canonical isoform(s) in the genesis of oral precancer and cancer lesions.