Targeted therapy in advanced bladder cancer: what have we learned?

N6-methyladenosine-related single-nucleotide polymorphism analyses identify oncogene RNFT2 in bladder cancer

Background

Single-nucleotide polymorphisms (SNPs) in N6-methyladenosine (m6A) related genetic locus play significant roles in tumorigenesis and development. The expression level of many oncogenes and tumour suppressor genes changed because of m6A-associated SNPs. In addition, the relationship between m6A-SNP and bladder cancer (BCa) has not been well studied.

Methods

We screened m6A-SNPs in BCa by combining m6A-SNPs data and GWAS-SNPs data. Expression quantitative trait loci (eQTL) and differential expression gene (DEGs) analyses were performed. In ring finger protein, transmembrane 2 (RNFT2), rs3088107 (C  > G) was found to have significant eQTL signals and make RNFT2 gene differentially-regulated mostly in BCa. We validated the expression level of RNFT2 in 32 pairs of BCa tissues and eight BCa cell lines by quantitative real-time PCR (qRT-PCR). Functional assays were performed to investigate the role of rs3088107 and RNFT2 in BCa in vitro.

Results

We identified 673 m6A-SNPs, which were associated with BCa. Of these m6A-SNPs, 221 showed eQTL signals, amongst which, rs3088107 in RNFT2 showed significant eQTL signals. Results of bioinformatic analyses showed that 11 genes with m6A-SNPs had a differential expression level in BCa. RNFT2 was predicted to be significantly up-regulated in BCa. The qRT-PCR results validated that RNFT2 was highly expressed in our own BCa tissues and cell lines. High expression of RNFT2 also indicated a worse overall survival. We also revealed that rs3088107 (C  > G) could inhibit the expression and m6A modification of RNFT2 by qRT-PCR, western-blot and m6A-RIP assays. Moreover, the results of functional assays indicated that RNFT2 promoted BCa cell proliferation and migration.

Conclusion

This research found that m6A-SNPs were associated with oncogene RNFT2 in BCa. Furthermore, m6A-SNPs showed great application potential as a new BCa diagnostic biomarker and prognostic indicator.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02701-z.

Construction of a Co-Expression Network for lncRNAs and mRNAs Related to Urothelial Carcinoma of the Bladder Progression

Carcinoma of urinary bladder is the most familiar cancer of the urinary tract, with the highest incidence in men. However, its prognosis and treatment have not improved significantly in the last 30 years. The main reason for this may be related to the alteration and regulation of genes. These alterations in genes that play a crucial role in cell cycle regulation may result in high-grade tumors and may alter drug sensitivity. Notably, the role of lncRNA in bladder cancer, especially the lncRNA-mRNA regulatory network, has not been fully elucidated. In this manuscript, we compared RNA sequencing (RNA-seq) data from 19 normal bladder tissues and 411 primary bladder tumor tissues using The Cancer Genome Atlas (TCGA) data bank, subjected differentially expressed mRNAs and lncRNAs to weighted gene co-expression network analysis, and screened out modules highly correlated with tumor progression. Subsequently, a lncRNA-mRNA co-expression network was built, and two key mRNAs were identified via COX regression analysis. Kaplan-Meier curve analysis revealed that the overall survival of sick people in the high-risk section was significantly shorter than those in the low-risk section. Therefore, this lncRNA-mRNA-based co-expression pattern may be used clinically to predict the prognosis of carcinoma of urinary bladder people. Our study not only provides a genetic target for carcinoma of urinary bladder therapy but also provides new ideas for people in the medical profession to discover the treatment of various tumors.

Identification of the circRNA-miRNA-mRNA Regulatory Network in Bladder Cancer by Bioinformatics Analysis

In recent years, increasing evidence shows that circular RNA (circRNA) disorder is closely related to tumorigenesis and cancer progression. However, the regulatory functions of most circRNAs in bladder cancer (BCa) remain unclear. This study was aimed at exploring the molecular regulatory mechanism of circRNAs in BCa. We obtained four datasets of circRNA, microRNA (miRNA), and messenger (mRNA) expression profiles from the Gene Expression Omnibus and The Cancer Genome Atlas microarray databases and identified 434, 367, and 4799/4841 differentially expressed circRNAs, miRNAs, and mRNAs, respectively. With these differentially expressed RNAs, we established a circRNA-miRNA-mRNA targeted interaction network. A total of 18, 24, and 51 central circRNAs, miRNAs, and mRNAs were identified, respectively. Among them, the top 10 mRNAs that had high connectivity with other circRNAs and miRNAs were regarded as hub genes. We detected the expression levels of these 10 mRNAs in 16 pairs of BCa tissues and adjacent normal tissues through quantitative real-time polymerase chain reaction. The differentially expressed mRNAs and central mRNAs were enriched in the processes and pathways that are associated with the growth, differentiation, proliferation, and apoptosis of tumor cells. The outstanding genes (CDCA4, GATA6, LATS2, RHOB, ZBTB4, and ZFPM2) also interacted with numerous drugs, indicating their potency as biomarkers and drug targets. The findings of this study provide a deep understanding of the circRNA-related competitive endogenous RNA regulatory mechanism in BCa pathogenesis.

LAPTM4B promotes the progression of bladder cancer by stimulating cell proliferation and invasion

Bladder cancer is a highly metastatic tumor and one of the most common malignant tumors originating in the urinary system. Due to the complicated etiology and lack of significant early symptoms, the diagnosis and treatment of bladder cancer is difficult. Lysosome-associated transmembrane protein 4β (LAPTM4B) was reported to be involved in the development and progression of several types of tumor, however, its potential effect on the development and metastasis of bladder cancer is still unclear. Immunohistochemistry was performed to detect the protein expression level of LAPTM4B in bladder cancer tissues and short hairpin RNAs targeting LAPTM4B were transfected into bladder cancer cells to knockdown its expression. MTT and colony formation assays were performed to detect cell proliferation, while wound healing and Transwell invasion assays were performed to detect cell migration and invasion, respectively. In addition, tumor growth assays were performed to confirm the effects of LAPTM4B in mice. The present study demonstrated that LAPTM4B was associated with the prognosis of patients with bladder cancer. In addition, LAPTM4B was associated with clinical characteristics, including tumor stage and recurrence. The results further showed that LAPTM4B knockdown could suppress the proliferation of bladder cancer cell lines. In addition, the migration and invasion of T24 and 5637 cells was suppressed following LAPTM4B knockdown in vitro. The in vivo data confirmed that knockdown of LAPTM4B markedly inhibited tumor growth and metastasis in mice. In summary, the results from the present study provide strong evidence of the effects of LAPTM4B in bladder cancer progression.

<p>Microarray Expression Profiles and Bioinformatics Analyses Reveal Aberrant Circular RNAs Expression in Bladder Cancer</p>

Background

Increasing evidence shows that circular RNAs (circRNAs) are involved in many biological processes, functioning as microRNA (miRNA) sponges. The aim of this study is to identify differentially expressed circRNAs in bladder cancer (BCa).

Methods

The transcriptome of circRNAs in BCa was assayed by microarray. Quantitative real-time PCR was performed to verify the results. Then, potential miRNA response elements (MREs) between circRNAs and miRNAs were predicted. Pathway and ontology enrichment analyses were performed to identify mechanisms related to the gene regulation of differentially expressed circRNAs.

Results

Three hundred and eighty-six up-regulated and 394 down-regulated circRNAs were identified, and their potential MREs were predicted in BCa.

Conclusion

The differentially expressed circRNAs indicate that circRNAs could play important roles in the molecular pathogenesis of BCa.

Regorefenib induces extrinsic/intrinsic apoptosis and inhibits MAPK/NF-κB-modulated tumor progression in bladder cancer in vitro and in vivo

The aim of the present study is to investigate anticancer effect and mechanism of regorafenib in bladder cancer in vitro and in vivo. Human bladder cancer TSGH 8301 cells were treated with regorafenib, NF-κB, AKT, or mitogen-activated protein kinase (MAPK) inhibitors for different time. The changes of cell viability, NF-κB activation, apoptotic signaling transduction, and expression of tumor progression-associated proteins were evaluated with MTT, NF-κB reporter gene assay, flow cytometry, and Western blotting assay. TSGH 8301 tumor bearing mice were established and treated with vehicle (140 μL of 0.1% DMSO) or regorafenib (10 mg/kg/day by gavage) for 15 days. The changes of tumor volume, body weight, NF-κB activation, MAPK activation, and tumor progression-associated proteins (MMP-9, XIAP, VEGF, and Cyclin-D1) after regorafenib treatment were evaluated with digital caliper, digital weight, and ex vivo Western blotting assay. Our results demonstrated NF-κB activation and protein levels of MMP-9, XIAP, VEGF, and Cyclin-D1 were significantly reduced by NF-κB (QNZ), ERK (PD98059), and P38 (SB203580) inhibitors. Regorafenib also significantly induced extrinsic and intrinsic apoptotic signaling transduction in bladder cancer in vitro. In addition, regorafenib significantly inhibited tumor growth, NF-κB, p38, ERK activation and expression of tumor progression-associated proteins in bladder cancer in vitro and in vivo. Taken together, these results proved that regorafenib not only induced apoptosis through extrinsic and intrinsic pathways and but suppressed MAPK/ NF-κB-modulated tumor progression in bladder cancer.

The Rho GTPase signalling pathway in urothelial carcinoma

Urothelial carcinoma remains a clinical challenge: non-muscle-invasive disease has a high rate of recurrence and risk of progression, and outcomes for patients with advanced disease are poor, owing to a lack of effective systemic therapies. The Rho GTPase family of enzymes was first identified >30 years ago and contains >20 members, which are divided into eight subfamilies: Cdc42, Rac, Rho, RhoUV, RhoBTB, RhoDF, RhoH, and Rnd. Rho GTPases are molecular on-off switches, which are increasingly being understood to have a critical role in a number of cellular processes, including cell migration, cell polarity, cell adhesion, cell cycle progression, and regulation of the cytoskeleton. This switch is an evolutionarily conserved system in which GTPases alternate between GDP-bound (inactive) and GTP-bound (active) forms. The activities of these Rho GTPases are many, context-dependent, and regulated by a number of proteins that are being progressively elucidated. Aberrations of the Rho GTPase signalling pathways have been implicated in various malignancies, including urothelial carcinoma, and understanding of the role of Rho GTPases in these diseases is increasing. This signalling pathway has the potential for therapeutic targeting in urothelial carcinoma. Research in this area is nascent, and much work is necessary before current laboratory-based research can be translated into the clinic.

Precision medicine for urothelial bladder cancer: update on tumour genomics and immunotherapy

Effective management of advanced urothelial bladder cancer is challenging. New discoveries that improve our understanding of molecular bladder cancer subtypes have revealed numerous potentially targetable genomic alterations and demonstrated the efficacy of treatments that harness the immune system. These findings have begun to change paradigms of bladder cancer therapy. For example, DNA repair pathway mutations in genes such as ERCC2, FANCC, ATM, RB1, and others can predict responses to neoadjuvant platinum-based chemotherapies and to targeted therapies on the basis of mutation status. Furthermore, an increasing number of pan-cancer clinical trials (commonly referred to as basket or umbrella trials) are enrolling patients on the basis of molecular and genetic predictors of response. These studies promise to provide improved insight into the true utility of personalized medicine in the treatment of bladder cancer and many other cancer types. Finally, therapies that modulate immune responses have shown great benefit in many cancer types. Several immune checkpoint inhibitors that target programmed cell death protein 1 (PD1), its ligand PDL1, and cytotoxic T lymphocyte-associated protein 4 (CTLA4) have already been approved for use in bladder cancer, representing the most important change to the urological oncologist's tool-kit in over a decade. These advances also provide opportunities for personalization of bladder cancer therapy.

Sleeping beauty: awakening urothelium from its slumber

The bladder urothelium is essentially quiescent but regenerates readily upon injury. The process of urothelial regeneration harkens back to the process of urothelial development whereby urothelial stem/progenitor cells must proliferate and terminally differentiate to establish all three urothelial layers. How the urothelium regulates the level of proliferation and the timing of differentiation to ensure the precise degree of regeneration is of significant interest in the field. Without a carefully-orchestrated process, urothelial regeneration may be inadequate, thereby exposing the host to toxins or pathogens. Alternatively, regeneration may be excessive, thereby setting the stage for tumor development. This review describes our current understanding of urothelial regeneration. The current controversies surrounding the identity and location of urothelial progenitor cells that mediate urothelial regeneration are discussed and evidence for each model is provided. We emphasize the factors that have been shown to be crucial for urothelial regeneration, including local growth factors that stimulate repair, and epithelial-mesenchymal cross talk, which ensures feedback regulation. Also highlighted is the emerging concept of epigenetic regulation of urothelial regeneration, which additionally fine tunes the process through transcriptional regulation of cell cycle genes and growth and differentiation factors. Finally, we emphasize how several of these pathways and/or programs are often dysregulated during malignant transformation, further corroborating their importance in directing normal urothelial regeneration. Together, evidence in the field suggests that any attempt to exploit regenerative programs for the purposes of enhanced urothelial repair or replacement must take into account this delicate balance.

Spatial and temporal clonal evolution during development of metastatic urothelial carcinoma

Patients with metastatic bladder cancer have a median survival of only 13-14 months. Precision medicine using targeted therapy may improve survival. Here we investigated spatial and temporal tumour evolution and tumour heterogeneity in order to evaluate the potential use of targeted treatment of metastatic bladder cancer. We performed a proof-of-concept study by whole exome sequencing of multiple tumour regions (n = 22) from three patients with metastatic bladder cancer. DNA from primary and metastatic tumour biopsies was analysed for mutations using Mutect and potential therapeutic targets were identified. We identified 256, 265 and 378 somatic mutations per patient, encompassing mutations with an estimated functional impact in 6-12 known disease driver genes per patient. Disease driver mutations present in all tumour regions could be identified in all cases, however, over time metastasis specific driver mutations emerged. For each patient we identified 6-10 potentially therapeutic targets, however very few targets were present in all regions. Low mutational allele frequencies were observed in most regions suggesting a complex mixture of different cancer cells with no spatial demarcation of subclones. In conclusion, primary bladder tumours and metastatic lesions showed heterogeneity at the molecular level, but within the primary tumour the heterogeneity appeared low. The observed lack of potential therapeutic targets common to all cancer cells in primary tumours and metastases emphasizes the challenges in designing rational targeted therapy solely based on analysis of the primary tumours.

mTOR inhibitors in urinary bladder cancer

Despite the great scientific advances that have been made in cancer treatment, there is still much to do, particularly with regard to urinary bladder cancer. Some of the drugs used in urinary bladder cancer treatment have been in use for more than 30 years and show reduced effectiveness and high recurrence rates. There have been several attempts to find new and more effective drugs, to be used alone or in combination with the drugs already in use, in order to overcome this situation.The biologically important mammalian target of rapamycin (mTOR) pathway is altered in cancer and mTOR inhibitors have raised many expectations as potentially important anticancer drugs. In this article, the authors will review the mTOR pathway and present their experiences of the use of some mTOR inhibitors, sirolimus, everolimus and temsirolimus, in isolation and in conjunction with non-mTOR inhibitors cisplatin and gemcitabine, on urinary bladder tumour cell lines. The non-muscle-invasive cell line, 5637, is the only one that exhibits a small alteration in the mTOR and AKT phosphorylation after rapalogs exposure. Also, there was a small inhibition of cell proliferation. With gemcitabine plus everolimus or temsirolimus, the results were encouraging as a more effective response was noticed with both combinations, especially in the 5637 and T24 cell lines. Cisplatin associated with everolimus or temsirolimus also gave promising results, as an antiproliferative effect was observed when the drugs were associated, in particular on the 5637 and HT1376 cell lines. Everolimus or temsirolimus in conjunction with gemcitabine or cisplatin could have an important role to play in urinary bladder cancer treatment, depending on the tumour grading.