Bladder Cancer: New Insights into Its Molecular Pathology

Circular RNA SMARCA5 is overexpressed and promotes cell proliferation, migration as well as invasion while inhibits cell apoptosis in bladder cancer

Background

This study aimed to investigate the function of circular RNA SMARCA5 (circ-SMARCA5) on cell proliferation, apoptosis, migration and invasion in bladder cancer.

Methods

Ten pairs of human bladder cancer tissue and adjacent tissue, five human bladder cancer cell lines (including TCCSUP, 5637, J82, UM-UC-3 and T-24) and normal human urothelial cell line SV-HUC-1, were obtained for the detection of circ-SMARCA5. Control overexpression and ShRNA, circ-SMARCA5 overexpression and ShRNA were constructed and transfected into UM-UC-3 cells as Control(+), Control(−), Circ-SMARCA5(+) and Circ-SMARCA5(−) groups. The role of circ-SMARCA5 was investigated in terms of cellular proliferation, apoptosis, migration, and invasion.

Results

Circ-SMARCA5 was overexpressed in tumor tissue compared to paired adjacent tissue and it was also overexpressed in TCCSUP, 5637, J82 and UM-UC-3 cells compared to normal human urothelial cell line SV-HUC-1. In UM-UC-3 cells, cell proliferation ability, migration rate and invasion cell count were increased in Circ-SMARCA5(+) group compared to Control(+) group, while reduced in Circ-SMARCA5(−) group compared to Control(−) group. Regarding the cell apoptosis, apoptosis rate and apoptotic protein C-Caspase 3 expression were decreased in Circ-SMARCA5(+) group than those in Control(+) group but raised in Circ-SMARCA5(−) group compared to Control(−) group, meanwhile, the anti-apoptotic protein Bcl-2 expression was elevated in Circ-SMARCA5(+) group than that in Control(+) group but reduced in Circ-SMARCA5(−) group compared to Control(−) group.

Conclusions

Circ-SMARCA5 is overexpressed, and promotes cell proliferation, migration and invasion, but represses apoptosis in bladder cancer.

Urothelial Carcinoma In Situ (CIS): New Insights

Urothelial carcinoma in situ (CIS) is a high-grade noninvasive malignancy with a high tendency of progression. Although it is typically grouped with other nonmuscle invasive bladder cancers, its higher grade and aggressiveness make it a unique clinical entity. Urothelial CIS is histologically characterized by replacement of the urothelium by cells which fulfill the morphologic criteria of malignancy including nuclear pleomorphism, hyperchromasia, prominent nucleoli, and increased numbers of normal and abnormal mitoses. Urothelial CIS may be categorized as primary when it is not associated with any past or present urothelial carcinoma. It is termed as secondary when there is concomitant or previous urothelial carcinoma in the patient. In recent years detailed molecular studies have provided valuable data for intrinsic molecular subclassification of urothelial carcinoma into 2 broad categories namely luminal and basal types with significant implications for prognosis and therapy. Similar studies on urothelial CIS are limited but have provided crucial insight into the molecular basis of CIS. These studies have revealed that urothelial CIS may also be divided into luminal and basal subtypes, but luminal subtype is much more common. It has also been shown that in many cases, luminal type of urothelial CIS may undergo a class switch to basal type during progression to an invasive carcinoma. Additional studies may be required to confirm and further elaborate these findings.

Intrinsic Molecular Subclassification of Urothelial Carcinoma of the Bladder: Are We Finally there?

Bladder cancer is a highly prevalent disease throughout the world usually encountered in older patients, and associated with substantial morbidity, mortality, and cost. The treatment of bladder cancer has remained unchanged for the last several decades. However, in recent years the availability of comprehensive genomic data from The Cancer Genome Atlas and other large projects have considerably improved our understanding of the pathogenesis of these tumors. These studies demonstrated that bladder cancers can be grouped into 2 broad categories namely basal and luminal molecular subtypes with recognizable subgroups in each of these categories. Clinical data suggest that invasive basal cancers are more sensitive to neoadjuvant chemotherapy (NAC), such that most patients with basal cancers who are aggressively managed with NAC have excellent outcomes. Patients with luminal cancers do not appear to derive much clinical benefit from NAC, but some may appear to be sensitive to anti-programmed death-ligand 1 (PDL1) antibodies and possibly other immune checkpoint inhibitors. It is hoped that future studies will also identify biomarkers such as immunohistochemical markers which may be used to predict therapeutic response of these tumors. This will contribute substantially toward efficient and cost-effective diagnosis and management of these neoplasms.

MicroRNA-143/Musashi-2/KRAS cascade contributes positively to carcinogenesis in human bladder cancer

It has been well established that microRNA (miR)‐143 is downregulated in human bladder cancer (BC). Recent precision medicine has shown that mutations in BC are frequently observed in FGFR3, RAS and PIK3CA genes, all of which correlate with RAS signaling networks. We have previously shown that miR‐143 suppresses cell growth by inhibiting RAS signaling networks in several cancers including BC. In the present study, we showed that synthetic miR‐143 negatively regulated the RNA‐binding protein Musashi‐2 (MSI2) in BC cell lines. MSI2 is an RNA‐binding protein that regulates the stability of certain mRNAs and their translation by binding to the target sequences of the mRNAs. Of note, the present study clarified that MSI2 positively regulated KRAS expression through directly binding to the target sequence of KRASmRNA and promoting its translation, thus contributing to the maintenance of KRAS expression. Thus, miR‐143 silenced KRAS and MSI2, which further downregulated KRAS expression through perturbation of the MSI2/KRAS cascade.

Urinary peptide panel for prognostic assessment of bladder cancer relapse

Non-invasive tools stratifying bladder cancer (BC) patients according to the risk of relapse are urgently needed to guide clinical intervention. As a follow-up to the previously published study on CE-MS-based urinary biomarkers for BC detection and recurrence monitoring, we expanded the investigation towards BC patients with longitudinal data. Profiling datasets of BC patients with follow-up information regarding the relapse status were investigated. The peptidomics dataset (n = 98) was split into training and test set. Cox regression was utilized for feature selection in the training set. Investigation of the entire training set at the single peptide level revealed 36 peptides being strong independent prognostic markers of disease relapse. Those features were further integrated into a Random Forest-based model evaluating the risk of relapse for BC patients. Performance of the model was assessed in the test cohort, showing high significance in BC relapse prognosis [HR = 5.76, p-value = 0.0001, c-index = 0.64]. Urinary peptide profiles integrated into a prognostic model allow for quantitative risk assessment of BC relapse highlighting the need for its incorporation in prospective studies to establish its value in the clinical management of BC.

Collagen stiffness promoted non-muscle-invasive bladder cancer progression to muscle-invasive bladder cancer

Purpose: Bladder cancer (BCa) is generally considered one of the most prevalent deadly diseases worldwide. Patients suffering from muscle-invasive bladder cancer (MIBC) possess dismal prognoses, while those with non-muscle-invasive bladder cancer (NMIBC) generally have a favorable outcome after local treatment. However, some NMIBCs relapse and progress to MIBC, with an unclarified mechanism. Hence, insight into the genetic drivers of BCa progression has tremendous potential benefits for precision therapeutics, risk stratification, and molecular diagnosis. Methods: In this study, three cohorts profile datasets (GSE13507, GSE32584, and GSE89) consisting of NMIBC and MIBC samples were integrated to address the differently expressed genes (DEGs). Subsequently, the protein-protein interaction (PPI) network and pathway enrichment analysis of DGEs were performed. Results: Six collagen members (COL1A1, COL1A2, COL5A2, COL6A1, COL6A2, and COL6A3) were up-regulated and gathered in the ECM-receptor interaction signal pathway identified by KEGG pathway analysis and GSEA. Evidence derived from the Oncomine and TCGA databases indicated that the 6 collagen genes promote the progression of BCa and are negatively associated with patient prognosis. Moreover, taking COL1A1 as a further research object, the results showed that COL1A1 was up-regulated in MIBC and its knockdown significantly inhibited the proliferation, migration, and invasion of 5637 and T24 cells by inhibiting epithelial-mesenchymal transition (EMT) process and the TGF-β signaling pathway. Conclusion: With integrated bioinformatic analysis and cell experiments, we showed that 6 collagen family members are high progression risk factors and that they can be used as independent effective diagnostic and prognostic biomarkers for BCa.

Association of body mass index with bladder cancer risk in men depends on abdominal obesity

PURPOSE

The previous epidemiological studies about the associations between obesity and bladder cancer risk have reported inconsistent results. Therefore, we analyzed whether the abdominal obesity effected on the risk of developing bladder cancer according to body mass index (BMI) using nationally representative data from the National Health Insurance System (NHIS).

PATIENTS AND METHODS

Among people who underwent at least one health examination from 2009 to 2012 in Korea, 11,823,876 men without a previous diagnosis of bladder cancer were followed up until December 2015. Multiple Cox regression analysis was conducted to determine the hazard ratio (HR) and 95% confidence interval (CI) for the association between bladder cancer and BMI or waist circumference (WC).

RESULTS

Significant upward trends in the risk of bladder cancer were observed with increasing BMI or WC according to the multivariate-adjusted model. However, the association between BMI and bladder cancer is influenced by the presence of abdominal obesity. In the group with WC < 90 cm, there was no significant change in the HRs for bladder cancer development beyond the reference BMI. In contrast, the HRs for bladder cancer showed statistically significant increase as the BMI increased beyond the reference BMI in the group with WC ≥ 90 cm.

CONCLUSION

This population-based study showed that increasing BMI and increasing WC were risk factors for developing bladder cancer in men, independent of confounding variables. However, there was a discrepancy in the trend of bladder cancer development according to BMI between the groups with abdominal obesity and without abdominal obesity.

The histone demethylase UTX/KDM6A in cancer: Progress and puzzles

The lysine-specific demethylase 6A/UTX (gene name KDM6A) acts as a component of the COMPASS complex to control gene activation. UTX demethylates H3K27me2/3 at genes and enhancers. Deleterious mutations in KDM6A are found in many cancer types, prominently urothelial carcinoma and certain T-cell leukemias. In certain cancers, however, UTX supports oncogenic transcription factors, e.g. steroid hormone receptors in breast and prostate cancer. In fetal development, UTX regulates lineage choice and cell differentiation. Analogously, loss of UTX function in cancer may lead to metaplasia or impede differentiation. Likely because its function is contingent on its interacting transcription factors, the effects of UTX inactivation are not uniform and require detailed investigation in each cancer type. In urothelial carcinoma, in particular, the functional consequences of the frequent mutations in KDM6A and other COMPASS component genes are poorly understood. Nevertheless, UTX inactivation appears to sensitize many cancers to inhibitors of the H3K27 methyltransferase EZH2. Conversely, inhibitors of UTX enzymatic activity may be applicable in cancers with an oncogenic UTX function. Intriguingly, the fact that KDM6A is localized on the X-chromosome, but both copies are expressed, may account for gender-specific differences in cancer susceptibility. In conclusion, despite recent progress, many open questions need to be addressed, most importantly, the detailed mechanisms by which KDM6A inactivation promotes various cancers, but also with which proteins UTX interacts in and apart from the COMPASS complex, and to which extent its catalytic function is required for its tumor-suppressive function.

MiR-125a-5p suppresses bladder cancer progression through targeting FUT4

MicroRNAs (miRNAs) have been widely studied in various human cancers, including bladder cancer. Previous report revealed that miR-125a-5p is downregulated in urothelial carcinomas. However, the biological function and molecular mechanism of miR-125a-5p in bladder cancer has not been elucidated. Therefore, this study focused on the role of miR-125a-5p in bladder cancer. The expression levels of miR-125a-5p were firstly tested in one normal cell line and four bladder cancer cell lines with qRT-PCR. The relative lower expression of miR-125a-5p was detected in bladder cancer cells. To confirm the effects of ectopic expression of miR-125a-5p on the biological behaviors of bladder cancer cells, gain-of-function assays were carried out. According to experimental results, miR-125a-5p overexpression suppressed cell proliferation and cell cycle progression, induced cell apoptosis. Moreover, overexpression of miR-125a-5p suppressed cell migration and invasion and reversed epithelial-mesenchymal transition (EMT). Mechanism investigation indicated that FUT4 is a target mRNA of miR-125a-5p in bladder cancer. The effects of FUT4 on cell proliferation, apoptosis, migration and invasion were identified by conducting gain-of-function assays. Finally, rescue assays indicated that FUT4 can reverse the effects of miR-125a-5p on bladder cancer progression. In summary, miR-125a-5p suppresses bladder cancer progression through targeting FUT4.

Analysis of potential genes associated with primary cilia in bladder cancer

Background

Dysfunction of primary cilia (PC), which could influence cell cycle and modulate cilia-related signaling transduction, has been reported in several cancers. However, there is no evidence of their function in bladder cancer (BLCA). This study was performed to investigate the presence of PC in BLCA and to explore the potential molecular mechanisms underlying the PC in BLCA.

Patients and methods

The presence of PC was assessed in BLCA and adjacent non-cancerous tissues. The gene expression dataset GSE52519 was employed to obtain differentially expressed genes (DEGs) associated with PC. The mRNA expression of the DEGs were confirmed by Gene Expression Profiling Interactive Analysis. The DEGs properties and pathways were analyzed by Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. Genomatix software was used to predict putative transcription factor binding sites (TFBS) in the promoter region of DEGs, and the transcription factors were achieved according to the shared TFBS, which were supported by the ChIP-Sequence data.

Results

PC were found to be reduced in BLCA tissue samples in this study. Seven DEGs were observed to be associated with PC, and gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis indicated that these DEGs exhibited the properties and functions of PC, and that the Hedgehog signaling pathway probably participated in the pathogenesis and progression of BLCA. The mRNA expression of the seven DEGs in 404 BLCA and 28 normal tissue samples were analyzed, and five DEGs including CENPF, STIL, AURKA, STK39 and OSR1 were identified. Five TFBS including CREB, E2FF, EBOX, ETSF and HOXF in the promoter region of five DEGs were calculated and the transcription factors were obtained according to the shared TFBS.

Conclusion

PC were found to be reduced in BLCA, and the potential molecular mechanisms of PC in BLCA helped to provide novel diagnosis and therapeutic targets for BLCA.

Circ-BPTF promotes bladder cancer progression and recurrence through the miR-31-5p/RAB27A axis

Circ-BPTF (hsa_circ_0000799) is a novel circular RNA derived from BPTF exons. Although BPTF is a well-studied predecessor gene, the characteristics and functions of circ-BPTF have not yet been reported. Here, we show that expression of circ-BPTF is increased in bladder cancer (BCa) tissues and cell lines compared with noncancerous tissues and cell lines. Consistently, BCa patients with higher expression levels of circ-BPTF were found to have higher tumor grades and poorer prognosis. Functionally, knockdown of circ-BPTF inhibited tumor progression in vitro and in vivo. Mechanistically, a target microRNA of circ-BPTF was confirmed to be miR-31-5p, and miR-31-5p mimics partially reversed the effect of circ-BPTF. Furthermore, RAB27A was predicted and shown to be a target of miR-31-5p, and circ-BPTF attenuated the anti-oncogenic effect of miR-31-5p and consequently enhanced RAB27A expression. In summary, our findings reveal that circ-BPTF promotes BCa progression through the miR-31-5p/RAB27A axis, suggesting that circ-BPTF may be a potential target for BCa treatment.