A Liquid Biopsy in Bladder Cancer—The Current Landscape in Urinary Biomarkers

The value of urinary exosomal microRNA-21 in the early diagnosis and prognosis of bladder cancer

Bladder cancer (BC) poses high morbidity and mortality, with urinary exosomal microRNA (miR)-21 showing potential value in its diagnosis and prognosis, and we probed its specific role. We prospectively selected 116 BC patients and 116 healthy volunteers as the BC and control groups, respectively. BC urinary exosomal miR-146a-5p, miR-93-5p, miR-663b, miR-21, and miR-4454 relative expression levels were assessed. The correlations between clinical indexes and urinary exosomal miR-21, prognostic value of miR-21, and diagnostic value of the five candidate miRNAs, urine cytology, and miRNA joint diagnostic panel for BC and urinary exosomal miR-21, miR-4454, and urine cytology for Ta-T1 and T2-T4 stage BC were analyzed. Urinary exosomal miR-146a-5p, miR-93-5p, miR-663b, miR-21, and miR-4454 were highly expressed in BC patients. miR-146a-5p, miR-93-5p, miR-663b, miR-21, miR-4454, miRNA combined diagnostic panel, and urine cytology had certain diagnostic value for BC, with miR-21, miR-4454, and miRNA co-diagnostic panel showing the highest diagnostic value. Collectively, urinary exosomal miR-21 was closely related to Tumor-Node-Metastasis staging and grading in BC patients. Urinary exosomal miR-21 had high diagnostic value for BC and Ta-T1 and T2-T4 stage BC, and had high predictive value for BC poor prognosis, providing an effective indicator for the occurrence, development, and prognostic assessment of BC.

Bladder Cancer in Exosomal Perspective: Unraveling New Regulatory Mechanisms

Bladder cancer, a prevalent malignant neoplasm of the urinary tract, exhibits escalating morbidity and mortality rates. Current diagnosis standards rely on invasive and costly cystoscopy and histopathology, underscoring the urgency for non-invasive, high-throughput, and cost-effective novel diagnostic techniques to ensure timely detection and standardized treatment. Recent years have witnessed the rise of exosome research in bladder cancer studies. Exosomes contain abundant bioactive molecules that can help elucidate the intricate mechanisms underlying bladder cancer pathogenesis and metastasis. Exosomes hold potential as biomarkers for early bladder cancer diagnosis while also serving as targeted drug delivery vehicles to enhance treatment efficacy and mitigate adverse effects. Furthermore, exosome analyses offer insights into the complex molecular signaling networks implicated in bladder cancer progression, revealing novel therapeutic targets. This review provides a comprehensive overview of prevalent exosome isolation techniques and highlights the promising clinical utility of exosomes in both diagnostic and therapeutic applications in bladder cancer management.

Urinary exosomal mRNA as a biomarker for the diagnosis of bladder cancer

OBJECTIVE

To study the diagnostic value of mRNA expression in urinary exocrine body in bladder cancer.

METHODS

From February 2022 to December 2022, 60 patients diagnosed with bladder cancer by pathology in the Department of Urology, Affiliated Hospital of Chengde Medical University were selected as the case group. In total, 40 healthy subjects receiving physical examinations were selected as the control group. 100 mL of morning urine samples were collected from the subjects in both groups based on the same standard. Three subjects were randomly selected from each group. Urinary exosomes were extracted by differential ultracentrifugation. High-throughput sequencing (RNA-seq) was used to detect mRNA expression profiles in urinary exosomes and identify differentially expressed genes. Bioinformatic analysis was performed to predict major biological functions of differentially expressed genes and related signaling pathways. RT-PCR validated expression levels of differentially expressed genes in urinary exosomes between the two groups. ROC curves evaluated the diagnostic value of differential genes for bladder cancer. Spearman's correlation analysis determined correlations between differentially expressed genes and the occurrence of bladder cancer. ROC curves speculated the diagnostic value of using combined differentially expressed genes.

RESULTS

Compared with normal subjects, there were 189 significantly differentially expressed genes in urinary exosomes of bladder cancer patients, including 33 up-regulated and 156 down-regulated. According to go and kyoto encyclopedia of genes and genomes (KEGG) analysis, the above differentially expressed genes may participate in the occurrence and development of bladder cancer through the MAPK pathway, PPAP signaling pathway, PI3K Akt signaling pathway and Hippo signaling pathway, affect protein and lipid metabolism, RNase activity, polysaccharide synthesis, signal transduction and other biological processes, and participate in cell proliferation, death, movement and adhesion, as well as cell differentiation and signal transduction. RT-PCR verified that the expression of tmeff1, SDPR, ACBD7, SCG2 and COL6A2 in the two groups of samples was statistically significant ( P  < 0.05). The ROC curve showed that the area under curve area under the curve of the five differential genes were 0.6934, 0.7746, 0.7239, 0.6396 and 0.6610, respectively. The sensitivity was 42.11%, 64.86%, 47.37%, 73.53% and 76.47%, and the specificity was 90%, 81.36%, 96.36%, 61.02% and 58.18%, respectively. Spearman correlation analysis showed that tmeff1, SDPR and acbd7 were associated with the occurrence of bladder cancer. The ROC curve of the combined diagnosis of the three and the two combined diagnoses suggested that the area under the curve of the combined diagnosis of SDPR and acbd7 was 0.7945, the sensitivity was 89.09%, and the specificity was 60.53%.

CONCLUSION

The gene expression profile in urinary exosomes of bladder cancer patients has changed significantly, and the differential genes may play an important biological role in the occurrence and development of bladder cancer. The combined detection of urinary exosome SDPR and ACBD7 has a certain diagnostic value for bladder cancer.

Low Cubilin/Myeloperoxidase ratio as a promising biomarker for prognosis of high-grade T1 bladder cancer

PURPOSE

T1 bladder cancer is known for its high progression and recurrence rates. Identifying aggressive tumours at the non-muscle-invasive stage is crucial to allow early interventions and subsequently increase patient survival. This study aimed to investigate the potential of the cubilin/myeloperoxidase (CUBN/MPO) ratio as a high-grade T1 bladder cancer biomarker.

METHODS

Urine samples were collected from 30 patients who underwent transurethral resection of the tumour with high-grade T1 bladder cancer (June 2015 to December 2019) before surgery. The urinary proteome was analysed using high-resolution mass spectrometry and the CUBN/MPO ratio was calculated. The primary outcome was the recurrence during the follow-up (around 31.5 months after resection). Univariate Cox regression and Kaplan-Meier curves were used for data analysis.

RESULTS

Patients with a low CUBN/MPO ratio exhibited upregulated MPO and/or downregulated CUBN. This group of patients had a higher incidence of disease recurrence and progression. Low CUBN/MPO ratio was significantly associated with a higher likelihood of recurrence, progression, and death. It is worth noting that this study was exploratory and conducted on a small sample size, so further research is needed to validate these findings in larger cohorts.

CONCLUSION

This study highlights the potential of the CUBN/MPO ratio as a prognostic biomarker for high-grade T1 bladder cancer.

Identification of novel protein biomarkers from the blood and urine for the early diagnosis of bladder cancer via proximity extension analysis

BACKGROUND

Bladder cancer (BC) is a very common urinary tract malignancy that has a high incidence and lethality. In this study, we identified BC biomarkers and described a new noninvasive detection method using serum and urine samples for the early detection of BC.

METHODS

Serum and urine samples were retrospectively collected from patients with BC (n = 99) and healthy controls (HC) (n = 50), and the expression levels of 92 inflammation-related proteins were examined via the proximity extension analysis (PEA) technique. Differential protein expression was then evaluated by univariate analysis (p < 0.05). The expression of the selected potential marker was further verified in BC and adjacent tissues by immunohistochemistry (IHC) and single-cell sequencing. A model was constructed to differentiate BC from HC by LASSO regression and compared to the detection capability of FISH.

RESULTS

The univariate analysis revealed significant differences in the expression levels of 40 proteins in the serum (p < 0.05) and 17 proteins in the urine (p < 0.05) between BC patients and HC. Six proteins (AREG, RET, WFDC2, FGFBP1, ESM-1, and PVRL4) were selected as potential BC biomarkers, and their expression was evaluated at the protein and transcriptome levels by IHC and single-cell sequencing, respectively. A diagnostic model (a signature) consisting of 14 protein markers (11 in serum and three in urine) was also established using LASSO regression to distinguish between BC patients and HC (area under the curve = 0.91, PPV = 0.91, sensitivity = 0.87, and specificity = 0.82). Our model showed better diagnostic efficacy than FISH, especially for early-stage, small, and low-grade BC.

CONCLUSION

Using the PEA method, we identified a panel of potential protein markers in the serum and urine of BC patients. These proteins are associated with the development of BC. A total of 14 of these proteins can be used to detect early-stage, small, low-grade BC. Thus, these markers are promising for clinical translation to improve the prognosis of BC patients.

TM9SF1 promotes bladder cancer cell growth and infiltration

BACKGROUND

Bladder cancer (BC) is the most common urological tumor. It has a high recurrence rate, displays tutor heterogeneity, and resists chemotherapy. Furthermore, the long-term survival rate of BC patients has remained unchanged for decades, which seriously affects the quality of patient survival. To improve the survival rate and prognosis of BC patients, it is necessary to explore the molecular mechanisms of BC development and progression and identify targets for treatment and intervention. Transmembrane 9 superfamily member 1 (TM9SF1), also known as MP70 and HMP70, is a member of a family of nine transmembrane superfamily proteins, which was first identified in 1997. TM9SF1 can be expressed in BC, but its biological function and mechanism in BC are not clear.

AIM

To investigate the biological function and mechanism of TM9SF1 in BC.

METHODS

Cells at 60%-80% confluence were transfected with lentiviral vectors for 48-72 h to achieve stable TM9SF1 overexpression or silencing in three BC cell lines (5637, T24, and UM-UC-3). The effect of TM9SF1 on the biological behavior of BC cells was then investigated through CCK8, wound-healing assay, transwell assay, and flow cytometry.

RESULTS

Overexpression of TM9SF1 increased the in vitro proliferation, migration, and invasion of BC cells by promoting the entry of BC cells into the G2/M phase. Silencing of TM9SF1 inhibited in vitro proliferation, migration, and invasion of BC cells and blocked BC cells in the G1 phase.

CONCLUSION

TM9SF1 may be an oncogene in BC.

TM9SF1 is implicated in promoting the proliferation and invasion of bladder cancer cells

Zhuo et al looked into the part of transmembrane 9 superfamily member 1 (TM9SF1) in bladder cancer (BC), and evaluated if it can be used as a therapeutic target. They created a permanent BC cell line and tested the effects of TM9SF1 overexpression and suppression on BC cell growth, movement, invasion, and cell cycle advancement. Their results show that TM9SF1 can boost the growth, movement, and invasion of BC cells and their access into the G2/M stage of the cell cycle. This research gives a novel direction and concept for targeted therapy of BC.

Hypermethylation Loci of ZNF671, IRF8, and OTX1 as Potential Urine-Based Predictive Biomarkers for Bladder Cancer

Bladder cancer (BCa) is a significant health issue and poses a healthcare burden on patients, highlighting the importance of an effective detection method. Here, we developed a urine DNA methylation diagnostic panel for distinguishing between BCa and non-BCa. In the discovery stage, an analysis of the TCGA database was conducted to identify BCa-specific DNA hypermethylation markers. In the validation phase, DNA methylation levels of urine samples were measured with real-time quantitative methylation-specific PCR (qMSP). Comparative analysis of the methylation levels between BCa and non-BCa, along with the receiver operating characteristic (ROC) analyses with machine learning algorithms (logistic regression and decision tree methods) were conducted to develop practical diagnostic panels. The performance evaluation of the panel shows that the individual biomarkers of ZNF671, OTX1, and IRF8 achieved AUCs of 0.86, 0.82, and 0.81, respectively, while the combined yielded an AUC of 0.91. The diagnostic panel using the decision tree algorithm attained an accuracy, sensitivity, and specificity of 82.6%, 75.0%, and 90.9%, respectively. Our results show that the urine-based DNA methylation diagnostic panel provides a sensitive and specific method for detecting and stratifying BCa, showing promise as a standard test that could enhance the diagnosis and prognosis of BCa in clinical settings.

Use of Multiple Machine Learning Approaches for Selecting Urothelial Cancer-Specific DNA Methylation Biomarkers in Urine

Diagnosing urothelial cancer (UCa) via invasive cystoscopy is painful, specifically in men, and can cause infection and bleeding. Because the UCa risk is higher for male patients, urinary non-invasive UCa biomarkers are highly desired to stratify men for invasive cystoscopy. We previously identified multiple DNA methylation sites in urine samples that detect UCa with a high sensitivity and specificity in men. Here, we identified the most relevant markers by employing multiple statistical approaches and machine learning (random forest, boosted trees, LASSO) using a dataset of 251 male UCa patients and 111 controls. Three CpG sites located in ALOX5, TRPS1 and an intergenic region on chromosome 16 have been concordantly selected by all approaches, and their combination in a single decision matrix for clinical use was tested based on their respective thresholds of the individual CpGs. The combination of ALOX5 and TRPS1 yielded the best overall sensitivity (61%) at a pre-set specificity of 95%. This combination exceeded both the diagnostic performance of the most sensitive bioinformatic approach and that of the best single CpG. In summary, we showed that overlap analysis of multiple statistical approaches identifies the most reliable biomarkers for UCa in a male collective. The results may assist in stratifying men for cystoscopy.

Exosomal DNA: Role in Reflecting Tumor Genetic Heterogeneity, Diagnosis, and Disease Monitoring

Extracellular vesicles (EVs), with exosomes at the forefront, are key in transferring cellular information and assorted biological materials, including nucleic acids. While exosomal RNA has been thoroughly examined, exploration into exosomal DNA (exoDNA)-which is stable and promising for cancer diagnostics-lags behind. This hybrid genetic material, combining contributions from both nuclear and mitochondrial DNA (mtDNA), is rooted in the cytoplasm. The enigmatic process concerning its cytoplasmic encapsulation continues to captivate researchers. Covering the entire genetic landscape, exoDNA encases significant oncogenic alterations in genes like TP53, ALK, and IDH1, which is vital for clinical assessment. This review delves into exosomal origins, the ins and outs of DNA encapsulation, and exoDNA's link to tumor biology, underscoring its superiority to circulating tumor DNA in the biomarker arena for both detection and therapy. Amidst scientific progress, there are complexities in the comprehension and practical application of the exoDNA surface. Reflecting on these nuances, we chart the prospective research terrain and potential pitfalls, forging a path for future inquiry. By illuminating both the known and unknown facets of exoDNA, the objective of this review is to provide guidance to the field of liquid biopsy (LB) while minimizing the occurrence of avoidable blind spots and detours.

Classification of formalin-fixed bladder cancer cells with laser tweezer Raman spectroscopy

Bladder cancer is a common cancer that is relatively hard to detect at an early stage because of its non-obvious symptoms. It is known that bladder cells can be found in urine samples which potentially could be used for early detection of bladder cancer. Raman spectroscopy is a powerful non-invasive tool for accessing biochemical information of cells. Combined with laser tweezers, to allow isolation of single cells, Raman spectroscopy has been used to characterise a number of bladder cells that might be found in a urine sample. Using principal component-canonical variates analysis (PC-CVA) and k-fold validation, the results shows that the invasive bladder cancer cells can be identified with accuracy greater than 87%. This demonstrates the potential of developing an early detection method that identifies the invasive bladder cancer cells in urine samples.

Comparative proteomics analysis in different stages of urothelial bladder cancer for identification of potential biomarkers: highlighted role for antioxidant activity

BACKGROUND

Non-muscle-invasive bladder cancer (NMIBC) has a high recurrence rate and muscle-invasive bladder cancer (MIBC) has unfavorable outcomes in urothelial bladder cancer (UBC) patients. Complex UBC-related protein biomarkers for outcome prediction may provide a more efficient management approach with an improved clinical outcome. The aim of this study is to recognize tumor-associated proteins, which are differentially expressed in different stages of UBC patients compared non-cancerous tissues.

METHODS

The proteome of tissue samples of 42 UBC patients (NMIBC n = 25 and MIBC n = 17) was subjected to two-dimensional electrophoresis (2-DE) combined with Liquid chromatography-mass spectrometry (LC-MS) system to identify differentially expressed proteins. The intensity of protein spots was quantified and compared with Prodigy SameSpots software. Functional, pathway, and interaction analyses of identified proteins were performed using geneontology (GO), PANTHER, Reactome, Gene MANIA, and STRING databases.

RESULTS

Twelve proteins identified by LC-MS showed differential expression (over 1.5-fold, p < 0.05) by LC-MS, including 9 up-regulated in NMIBC and 3 up-regulated in MIBC patients. Proteins involved in the detoxification of reactive oxygen species and cellular responses to oxidative stress showed the most significant changes in UBC patients. Additionally, the most potential functions related to these detected proteins were associated with peroxidase, oxidoreductase, and antioxidant activity.

CONCLUSION

We identified several alterations in protein expression involved in canonical pathways which were correlated with the clinical outcomes suggested might be useful as promising biomarkers for early detection, monitoring, and prognosis of UBC.

Detection of the ADGRG6 hotspot mutations in urine for bladder cancer early screening by ARMS-qPCR

BACKGROUND

In bladder cancer, recurrent ADGRG6 enhancer hotspot mutations (chr. 6: 142,706,206 G>A, chr. 6:142,706,209 C>T) were reported at a high mutation rate of approximately 50%. Thus, ADGRG6 enhancer mutation status might be a candidate for diagnostic biomarker.

METHODS

To improve test efficacy, an amplification refractory mutation system combined with quantitative real-time PCR (ARMS-qPCR) assay was developed to detect the ADGRG6 mutations in a patient as a clinical diagnostic test. To validate the performance of the ARMS-qPCR assay, artificial plasmids, cell DNA reference standard were used as templates, respectively. To test the clinical diagnostic ability, we detected the cell free DNA (cfDNA) and sediment DNA (sDNA) of 30 bladder cancer patients' urine by ARMS-qPCR comparing with Sanger sequencing, followed by the droplet digital PCR to confirm the results. We also tested the urine of 100 healthy individuals and 90 patients whose diagnoses urinary tract infections or urinary stones but not bladder cancer.

RESULTS

Sensitivity of 100% and specificity of 96.7% were achieved when the mutation rate of the artificial plasmid was 1%, and sensitivity of 96.7% and specificity of 100% were achieved when the mutation frequency of the reference standard was 0.5%. Sanger sequencing and ARMS-qPCR both detected 30 cases of bladder cancer with 93.3% agreement. For the remaining unmatched sites, ARMS-qPCR results were consistent with droplet digital PCR. Among 100 healthy individuals, three of them carried hotspot mutations by way of ARMS-qPCR. Of 90 patients with urinary tract infections or urinary stones, no mutations were found by ARMS-qPCR. Based on clinical detection, the ARMS-qPCR assay's sensitivity is 83.3%, specificity is 98.4%.

CONCLUSION

We here present a novel urine test for ADGRG6 hotspot mutations with high accuracy and sensitivity, which may potentially serve as a rapid and non-invasive tool for bladder cancer early screening and follow-up relapse monitoring.

Blood-based liquid biopsy: insights into early detection, prediction, and treatment monitoring of bladder cancer

Bladder cancer (BC) is a clinical challenge worldwide with late clinical presentation, poor prognosis, and low survival rates. Traditional cystoscopy and tissue biopsy are routine methods for the diagnosis, prognosis, and monitoring of BC. However, due to the heterogeneity and limitations of tumors, such as aggressiveness, high cost, and limited applicability of longitudinal surveillance, the identification of tumor markers has attracted significant attention in BC. Over the past decade, liquid biopsies (e.g., blood) have proven to be highly efficient methods for the discovery of BC biomarkers. This noninvasive sampling method is used to analyze unique tumor components released into the peripheral circulation and allows serial sampling and longitudinal monitoring of tumor progression. Several liquid biopsy biomarkers are being extensively studied and have shown promising results in clinical applications of BC, including early detection, detection of microscopic residual disease, prediction of recurrence, and response to therapy. Therefore, in this review, we aim to provide an update on various novel blood-based liquid biopsy markers and review the advantages and current limitations of liquid biopsy in BC therapy. The role of blood-based circulating tumor cells, circulating tumor DNA, cell-free RNA, exosomes, metabolomics, and proteomics in diagnosis, prognosis, and treatment monitoring, and their applicability to the personalized management of BC, are highlighted.

Approaches to Clinical Complete Response after Neoadjuvant Chemotherapy in Muscle-Invasive Bladder Cancer: Possibilities and Limitations

In the surgical oncology field, the change from a past radical surgery to an organ preserving surgery is a big trend. In muscle-invasive bladder cancer treatment, neoadjuvant chemotherapy (NAC) followed by radical cystectomy (RC) is the standard of care for muscle-invasive bladder cancer (MIBC) patients eligible for cisplatin. There is a growing interest in bladder preserving strategies after NAC because good oncologic outcome has been reported for pathologic complete response (pCR) patients after NAC, and many studies have continued to discuss whether bladder preservation treatment is possible for these patients. However, in actual clinical practice, decision-making should be determined according to clinical staging and there is a gap that cannot be ignored between clinical complete response (cCR) and pCR. Currently, there is a lack in a uniform approach to post-NAC restaging of MIBC and a standardized cCR definition. In this review, we clarify the gap between cCR and pCR at the current situation and focus on emerging strategies in bladder preservation in selected patients with MIBC who achieve cCR following NAC.

Current and Future Landscape of Perioperative Treatment for Muscle-Invasive Bladder Cancer

Cisplatin-based neoadjuvant chemotherapy followed by radical cystectomy is the current standard of care for muscle-invasive bladder cancer (MIBC). However, less than half of patients are candidates for this treatment, and 50% will develop metastatic disease. Adjuvant chemotherapy could be offered if neoadjuvant treatment has not been administered for suitable patients. It is important to reduce the risk of systemic recurrence and improve the prognosis of localized MIBC. Systemic therapy for metastatic urothelial carcinoma has evolved in recent years. Immune checkpoint inhibitors and targeted agents, such as antibody-drug conjugates or FGFR inhibitors, are new therapeutic alternatives and have shown their benefit in advanced disease. Currently, several clinical trials are investigating the role of these drugs, as monotherapy and in combination with chemotherapy, in the neoadjuvant and adjuvant settings with promising outcomes. In addition, the development of predictive biomarkers could predict responses to neoadjuvant therapies.

Applications of Exosomes in Diagnosing Muscle Invasive Bladder Cancer

Muscle Invasive Bladder Cancer (MIBC) is a subset of bladder cancer with a significant risk for metastases and death. It accounts for nearly 25% of bladder cancer diagnoses. A diagnostic work-up for MIBC is inclusive of urologic evaluation, radiographic imaging with a CT scan, urinalysis, and cystoscopy. These evaluations, especially cystoscopy, are invasive and carry the risk of secondary health concerns. Non-invasive diagnostics such as urine cytology are an attractive alternative currently being investigated to mitigate the requirement for cystoscopy. A pitfall in urine cytology is the lack of available options with high reliability, specificity, and sensitivity to malignant bladder cells. Exosomes are a novel biomarker source which could resolve some of the concerns with urine cytology, due to the high specificity as the surrogates of tumor cells. This review serves to define muscle invasive bladder cancer, current urine cytology methods, the role of exosomes in MIBC, and exosomes application as a diagnostic tool in MIBC. Urinary exosomes as the specific populations of extracellular vesicles could provide additional biomarkers with specificity and sensitivity to bladder malignancies, which are a consistent source of cellular information to direct clinicians for developing treatment strategies. Given its strong presence and differentiation ability between normal and cancerous cells, exosome-based urine cytology is highly promising in providing a perspective of a patient’s bladder cancer.