DNA copy number alterations and PPARG amplification in a patient with multifocal bladder urothelial carcinoma

Attachment of Cancer Urothelial Cells to the Bladder Epithelium Occurs on Uroplakin-Negative Cells and Is Mediated by Desmosomal and Not by Classical Cadherins

Urinary bladder cancer is often multifocal; however, the intraluminal dissemination of the urothelial cancer cells is poorly understood. The involvement of N-cadherin in the adhesion of the cancer urothelial cells to the urothelium had not previously been studied. Therefore, we herein explore the possibility of the intraluminal dissemination of the urothelial cancer cells by evaluating the role of classical cadherins in the adhesion of urothelial cancer cells to the urothelium. We used E-cadherin negative T24 cells and established a T24 Ncad^low cell line with an additionally decreased expression of N-cadherin in the plasma membrane and a decreased secretion of proform of metalloproteinase 2. The labelled T24 and T24 Ncad^low cells were seeded onto urothelial in vitro models. After 24 h in co-culture, unattached cancer cells were rinsed and urothelia with attached cancer urothelial cells were processed for fluorescence and electron microscopy. Both the T24 and T24 Ncad^low cells attached to the urothelium, yet only to the uroplakin-negative urothelial cells. The ultrastructural analysis showed that T24 and T24 Ncad^low cells adhere to poorly differentiated urothelial cells by desmosomes. To achieve this, they first disrupt tight junctions of superficial urothelial cells. This study indicates that the lack of E-cadherin expression and decreased expression of N-cadherin in the plasma membrane of T24 cells does not interfere with their adhesion to the urothelium; therefore, our results suggest that intraluminal dissemination of cancer urothelial cells along the urothelium occurs on uroplakin-negative cells and is desmosome-mediated.

TM4SF1 regulates apoptosis, cell cycle and ROS metabolism via the PPARγ-SIRT1 feedback loop in human bladder cancer cells

Transmembrane-4-L-Six-Family-1 (TM4SF1) is a member of the L6 family and functions as a signal transducer to regulate cell development, growth and motility. Here we show that TM4SF1 is strongly upregulated in human muscle invasive bladder cancer (MIBC) tissues, corroborating the bioinformatical results of transcriptome analysis. Moreover, tissue microarray (TMA) shows significant correlations (p < 0.05) between high expression of TM4SF1 and T stage, TNM stage, lymph node metastasis status and survival rate of MIBC patients, indicating a positive association between TM4SF1 expression and poorer prognosis. Furthermore, in vitro and in vivo studies indicate that the proliferation of human bladder cancer (BCa) cells is significantly suppressed by knockdown of TM4SF1 (p < 0.05). Functionally, the reduction of TM4SF1 could induce cell cycle arrest and apoptosis possibly via the upregulation of reactive oxygen species (ROS) in BCa cells. In addition, these observations could be recovered by treatment with GW9662 (antagonist of PPARγ) and resveratrol (activator of SIRT1). Taken together, our results suggest that high expression of TM4SF1 predicts poor prognosis of MIBC.

Silencing of HJURP induces dysregulation of cell cycle and ROS metabolism in bladder cancer cells via PPARγ-SIRT1 feedback loop

Holliday Junction Recognition Protein (HJURP) is a centromeric histone chaperone involving in de novo histone H3 variant CenH3 (CENP-A) recruitment. Our transcriptome and in vivo study revealed that HJURP is significantly upregulated in bladder cancer (BCa) tissues at both mRNA and protein levels. Knockdown of HJURP inhibited proliferation and viability of BCa cell lines revealed by CCK-8, colony formation and Ki-67-staining assays, and induced apoptosis and reactive oxygen species (ROS) production, as well as triggered cell cycle arrest at G0/G1 phase possibly via loss of CENP-A. Interestingly, in the HJURP-reduced BCa cells the levels of PPARγ and acetylated-p53 were increased, while the ratio of phosphorylated/total SIRT1 protein was decreased. Moreover, after treatment of the BCa cells using PPARγ antagonist (GW9662) and SIRT1 agonist (resveratrol, RSV) respectively, thee phenotypes of cell cycle arrest, increased ROS production and inhibited proliferation rate were all rescued. Taken together, our results suggested that HJURP might regulate proliferation and apoptosis via the PPARγ-SIRT1 negative feedback loop in BCa cells.

Using Copy Number Alterations to Identify New Therapeutic Targets for Bladder Carcinoma

Bladder cancer represents the ninth most widespread malignancy throughout the world. It is characterized by the presence of two different clinical and prognostic subtypes: non-muscle-invasive bladder cancers (NMIBCs) and muscle-invasive bladder cancers (MIBCs). MIBCs have a poor outcome with a common progression to metastasis. Despite improvements in knowledge, treatment has not advanced significantly in recent years, with the absence of new therapeutic targets. Because of the limitations of current therapeutic options, the greater challenge will be to identify biomarkers for clinical application. For this reason, we compared our array comparative genomic hybridization (array-CGH) results with those reported in literature for invasive bladder tumors and, in particular, we focused on the evaluation of copy number alterations (CNAs) present in biopsies and retained in the corresponding cancer stem cell (CSC) subpopulations that should be the main target of therapy. According to our data, CCNE1, MYC, MDM2 and PPARG genes could be interesting therapeutic targets for bladder CSC subpopulations. Surprisingly, HER2 copy number gains are not retained in bladder CSCs, making the gene-targeted therapy less interesting than the others. These results provide precious advice for further study on bladder therapy; however, the clinical importance of these results should be explored.