INTRODUCTION

Bladder cancer (BC) is one of the most common types of cancer in the world and its incidence is 3.5 times higher in men than in women. It was estimated by The American Cancer Society that there were 81.190 new cases of BC in the United States in 2018 and 17.240 deaths due to BC [1]. 90% of malignancies in the bladder are urothelial carcinoma (UC) and 75-80% of urothelial carcinomas are non-muscle invasive bladder tumors (NMIBT). NMIBT, depending on its progression, may be carcinoma in situ (5%), Ta stage tumors (70%) or T1 stage tumors (25%) invading the lamina propria layer of the bladder. In NMIBT, it is clinically important whether the tumor is a high grade or low grade besides the tumor stage. Among all bladder tumors, high grade-T1 stage tumors (Hg-pT1) are known to have clinically significant heterogeneity, recurrence, progression, and mortality. In addition, clinical management of Hg-pT1 tumors is a subject of discussion. There is no consensus on the choice of treatment due to the different pathological subtypes of pT1 [2, 3]. It is evident that proteomic approaches will be useful in order to elucidate the invasion of the cells forming the bladder tumor tissue at the molecular level. However, there are limited studies that target the non-muscle invasive bladder tumor tissues for biomarker discovery and to understand tumor progression. Therefore we aimed to assess the proteomic profiles of Hg-pT1 bladder tumors and compare these profiles with the control tissues.

MATERIALS AND METHODS

Hg-pT1 bladder tumor tissues and their corresponding healthy tissues obtained from 4 male patients during TUR-BT operation. There was no carcinoma in situ formation accompanying the tumors. The collected tissue samples were washed with Phosphate Buffered Saline (PBS) and snap-frozen in liquid nitrogen. Tissue samples were stored at -80 °C until the working day. Tissues were homogenized and then lysed using UPX Solution (Expedeon, UK). Tryptic peptides were obtained with the aid of the kit (Expedeon, UK) following the Filter Aided Sample Preparation (FASP) method [4] and separated with Liquid Chromatography- Tandem Mass Spectrometry (LC-MS/MS) using Xevo G2-XS Q-Tof (Waters, USA). Progenesis QI (Waters, USA) software was used to identify the peptides and obtained peptide sequences were searched against the Homo sapiens database from Uniprot. The identified proteins were further analyzed by bioinformatic approaches using PANTHER, STRING and Signor tools.

RESULTS AND DISCUSSION

As a result of the analysis, 1166 proteins were identified. Of these, 90 proteins were statistically significant (p <0.05). Proteins that increased in tumor tissues (n= 55) were responsible for heteronuclear RNA metabolism, translational regulation activity, endoplasmic reticulum stress, mitochondrial stress, and aerobic glycolysis due to Warburg effect. Decreasing proteins in tumor tissues (n= 35) were involved in cellular adhesion and regulation of the cell skeleton. The change in mass signal intensities of all proteins between tumor and healthy tissues were further examined. Accordingly, Galectin-3, S100A11, Fibronectin, HSP60, HSP70, and HSP90's analog HSP90AB1 and HSP90B1 proteins were found to increase in Hg-pT1 tumor tissues among all proteins. It can be said that these proteins have prognostic importance for Hg-pT1 bladder tumors. In addition, this study may contribute to an understanding of the progressive characteristics of Hg-T1 stage bladder tumors.