Gain of TPPP as a predictor of progression in patients with bladder cancer

The present study investigated the role of tubulin polymerization promoting protein (TPPP) in the regulation of bladder cancer (BC) cell proliferation and migration, in addition to the association between TPPP gene copy number amplification and clinicopathological characteristics of BC. TPPP gene amplification was measured in human BC epithelial cells and samples obtained from 52 patients with BC via fluorescence in situ hybridization. TPPP gain was defined as mean TPPP copy number >2.2 per nucleus (cutoff). The neutrophil-to-lymphocyte ratio (NLR) was also obtained from the preoperative data of the patients. For in vitro assays, BC cell lines were transfected with either TPPP small interfering RNAs or scrambled control, following which cell proliferation and migration were determined using Cell Counting Kit-8 and Transwell migration assays, respectively. The percentage of cells with TPPP copy number amplification in the four BC epithelial cell lines (MGH-U1, -U1R, -U3, -U4) examined (86.0-100.0%) was found to be higher compared with that in the normal human uroepithelial cell lines (3.0 and 9.0%). Patients were divided into one- (1.9%), two- (55.8%), three- (7.7%), four- (26.9%) and five-copy (7.7%) types. Results calculated using Fisher's exact test indicated that the gain of TPPP in patients with BC associated significantly with age (P<0.05), advanced histological grade (P<0.001), tumor stage (P<0.05), histological type (P<0.001) and NLR (P<0.05). In MGH-U1R and MGH-U4 cells, cell proliferation and migration were revealed to be significantly lower following TPPP knockdown compared with those in cells transfected with the scrambled control. In conclusion, findings from the present study suggest that TPPP is important for cell proliferation, cell migration and BC progression, such that TPPP copy number assessment would be advised for preoperative urine cytology for urothelial neoplasia diagnosis.