Circulating Cell-Free DNA in Liquid Biopsies as Potential Biomarker for Bladder Cancer: A Systematic Review

Metastasis development in non-muscle-invasive bladder cancer

Non-muscle-invasive bladder cancer (NMIBC) is the most common type of bladder cancer presentation and is characterized by a varying probability of recurrence and progression. Sporadically, patients with NMIBC might also develop tumour metastases without any pathological evidence of muscle-invasive disease within the bladder, a condition known as metastatic NMIBC. In the published literature, this phenomenon is limited to several case reports and small reviews, with few data regarding the possible aetiologies. Several possible factors can be potentially associated with metastatic NMIBC, including tumour understaging, the number of transurethral resection procedures received by the patient, the presence of circulating tumour cells, the modality used for diagnostic cystoscopy and possible gender-associated differences. In this Perspective, our aim was to integrate and report currently available data on this relatively rare entity and provide some potential aetiological explanations.

Are elevated mitochondrial DNA fragments in prostatic inflammation a potential biomarker for prostate cancer?

BACKGROUND

We sought to determine whether two soluble forms with different size of mtDNA are linked to prostatic inflammation, and whether they discriminate prostate cancer (PCa) from inflammatory prostatic conditions.

METHODS

Histopathologically diagnosed prostatitis, PCa and benign prostatic hyperplasia patients (n = 93) were enrolled in this study and they were categorized as with and without prostate inflammation. Quantitative RT-PCR was used to analyze the levels of 79-bp and 230-bp fragments in urine and blood samples collected following prostate massage.

RESULTS

The urine mtDNA-79 and mtDNA-230 were significantly increased in patients with prostate inflammation compared with those in without inflammation. Here, 79-bp fragment of apoptotic origin was significantly higher level than 230-bp fragment of necrotic origin. Although mtDNA-79 copy number in serum samples was also increased in patients with prostate inflammation, mtDNA-230 was similar in the two groups. Furthermore, mtDNA-79 and mtDNA-230 copy numbers in postprostate massage urine were higher (about 16-fold and 22-fold, respectively) than those from serum samples. ROC analysis showed that, although post-prostate massage urine have relatively higher performance than blood, ability to discriminate cases of both fragments was not better than that of serum total PSA.

CONCLUSIONS

Our results demonstrate that shorter cf-mtDNA fragment size in particular, increase in the presence of prostate inflammation in post-prostatic massage urine but both fragments could never improve serum total PSA performance.

Bladder cancer patients have increased NETosis and impaired DNaseI-mediated NET degradation that can be therapeutically restored in vitro

Background

Neutrophils, key players of the immune system, also promote tumor development through the formation of neutrophil extracellular traps (NETs) in a process called NETosis. NETs are extracellular networks of DNA, histones and cytoplasmic and granular proteins (calprotectin, myeloperoxidase, elastase, etc.) released by neutrophils upon activation. NETs regulate tumor growth while promoting angiogenesis and invasiveness, and tumor cells also stimulate NETosis. Although NETosis seems to be increased in cancer patients, an increase of NETs in plasma may also be mediated by an impaired degradation by plasma DNaseI, as evidenced in several immunological disorders like lupus nephritis. However, this has never been evidenced in bladder cancer (BC) patients. Herein, we aimed to evaluate the occurrence of increased NETosis in plasma and tumor tissue of BC patients, to ascertain whether it is mediated by a reduced DNaseI activity and degradation, and to in vitro explore novel therapeutic interventions.

Methods

We recruited 71 BC patients from whom we obtained a plasma sample before surgery and a formalin-fixed paraffin embedded tumor tissue sample, and 64 age- and sex-matched healthy controls from whom we obtained a plasma sample. We measured NETs markers (cell-free fDNA, calprotectin, nucleosomes and neutrophil elastase) and the DNaseI activity in plasma with specific assays. We also measured NETs markers in BC tissue by immunofluorescence. Finally, we evaluated the ability of BC and control plasma to degrade in vitro-generated NETs, and evaluated the performance of the approved recombinant human DNaseI (rhDNaseI, Dornase alfa, Pulmozyme^®, Roche) to restore the NET-degradation ability of plasma. In vitro experiments were performed in triplicate. Statistical analysis was conducted with Graphpad (v.8.0.1).

Results

NETosis occurs in BC tissue, more profusely in the muscle-invasive subtype (P<0.01), that with the worst prognosis. Compared to controls, BC patients had increased NETosis and a reduced DNaseI activity in plasma (P<0.0001), which leads to an impairment to degrade NETs (P<0.0001). Remarkably, this can be therapeutically restored with rhDNaseI to the level of healthy controls.

Conclusion

To the best of our knowledge, this is the first report demonstrating that BC patients have an increased NETosis systemically and in the tumor microenvironment, in part caused by an impaired DNaseI-mediated NET degradation. Remarkably, this defect can be therapeutically restored in vitro with the approved Dornase alfa, thus Pulmozyme^® could become a potential therapeutic tool to locally reduce BC progression.

Preoperative Cell-Free DNA (cfDNA) in Muscle-Invasive Bladder Cancer Treatment Outcome

BACKGROUND

Tumor heterogeneity and lack of personalized prognosis leads to bladder cancer (BlCa) patients' lifelong surveillance with invasive interventions, highlighting the need for modern minimally invasive tools for disease management. Herein, we have evaluated the clinical utility of preoperative serum cell-free DNA (cfDNA) in ameliorating patients' risk-stratification and prognosis.

METHODS

cfDNA was purified from 190 preoperative BlCa patients and 26 healthy individuals' serum samples and quantified by 2 assays: an in-house quantitative real-time PCR (qPCR) assay using LEP as reference control and a direct fluorometric assay using Qubit HS dsDNA. Capillary electrophoresis was performed in 31 samples for cfDNA fragment profiling. Tumor relapse/progression and metastasis/death were used as clinical endpoints for non-muscle-invasive bladder cancer and muscle-invasive bladder cancer (MIBC), respectively.

RESULTS

cfDNA profiling by capillary electrophoresis highlighted that total and fragment-related cfDNA levels were significantly increased in BlCa and associated with advance disease stages. Evaluation of cfDNA levels by both Qubit/qPCR displayed highly consistent results (rs = 0.960; P < 0.001). Higher cfDNA was correlated with MIBC and stronger risk for early metastasis (Qubit:hazard ratio [HR] = 3.016, P = 0.009; qPCR:HR = 2.918, P = 0.004) and poor survival (Qubit:HR = 1.898, P = 0.042; qPCR:HR = 1.888, P = 0.026) of MIBC patients. Multivariate cfDNA-fitted models led to superior risk stratification and net benefit for MIBC prognosis compared to disease established markers.

CONCLUSIONS

Elevated preoperative cfDNA levels are strongly associated with higher risk for short-term metastasis and poor outcome of MIBC, supporting modern noninvasive disease prognosis and management.

Urinary Cell-Free DNA in Liquid Biopsy and Cancer Management

BACKGROUND

The current methodology used to detect, diagnose, and monitor many types of cancers requires invasive tissue biopsy testing. Recently, liquid biopsy using blood, plasma, urine, saliva, and various other bodily fluids has shown utility to solve many issues associated with tissue biopsy. Blood/plasma has received most of the attention within the liquid biopsy field, however, obtaining blood samples from patients is still somewhat invasive and requires trained professionals. Using urine to detect cell-free DNA cancer biomarkers offers a truly non-invasive sampling method that can be easily and reproducibly conducted by patients.

CONTENT

Novel technologies and approaches have made the detection of small quantities of cell-free tumor DNA of varying lengths possible. Recent studies using urine circulating tumor DNA to detect cancer mutations and other biomarkers have shown sensitivity comparable to blood/plasma cell-free DNA liquid biopsy for many cancer types. Thus, urine cell-free DNA liquid biopsy may replace or provide supplementary information to tissue/blood biopsies. Further investigation with larger patient cohorts and standardization of pre-analytical factors is necessary to determine the utility of urine cell-free DNA liquid biopsy for cancer detection, diagnosis, and monitoring in a clinical setting.

SUMMARY

In this mini-review we discuss the biological aspects of cell-free DNA in urine, numerous studies using urine cell-free DNA to detect urological cancers, and recent studies using urine cell-free DNA to detect and monitor non-urological cancers including lung, breast, colorectal, and other cancers.

Translational proteomics and phosphoproteomics: Tissue to extracellular vesicles

We are currently experiencing a rapidly developing era in terms of translational and clinical medical sciences. The relatively mature state of nucleic acid examination has significantly improved our understanding of disease mechanism and therapeutic potential of personalized treatment, but misses a large portion of phenotypic disease information. Proteins, in particular phosphorylation events that regulates many cellular functions, could provide real-time information for disease onset, progression and treatment efficacy. The technical advances in liquid chromatography and mass spectrometry have realized large-scale and unbiased proteome and phosphoproteome analyses with disease relevant samples such as tissues. However, tissue biopsy still has multiple shortcomings, such as invasiveness of sample collection, potential health risk for patients, difficulty in protein preservation and extreme heterogeneity. Recently, extracellular vesicles (EVs) have offered a great promise as a unique source of protein biomarkers for non-invasive liquid biopsy. Membranous EVs provide stable preservation of internal proteins and especially labile phosphoproteins, which is essential for effective routine biomarker detection. To aid efficient EV proteomic and phosphoproteomic analyses, recent developments showcase clinically-friendly EV techniques, facilitating diagnostic and therapeutic applications. Ultimately, we envision that with streamlined sample preparation from tissues and EVs proteomics and phosphoproteomics analysis will become routine in clinical settings.

Clinical Application of Circulating Tumor Cells and Circulating Endothelial Cells in Predicting Bladder Cancer Prognosis and Neoadjuvant Chemosensitivity

Purpose

To investigate the role of circulating rare cells (CRCs), namely, circulating tumor cells (CTCs) and circulating endothelial cells (CECs), in aiding early intervention, treatment decision, and prognostication in bladder cancer.

Methods

A total of 196 patients with pathologically confirmed bladder cancer, namely, 141 non-muscle invasive bladder cancer (NMIBC) and 55 muscle invasive bladder cancer (MIBC) patients. There were 32 patients who received cisplatin-based neoadjuvant chemotherapy (NAC) followed by radical cystectomy (RC). Subtraction enrichment combined with immunostaining-fluorescence in situ hybridization (SE-iFISH) strategy was used for CTC/CEC detection. Kaplan–Meier analysis and Cox regression were used to evaluate the overall survival (OS) and recurrence-free survival (RFS). Receiver operator characteristic analysis was used to discriminate NAC sensitivity.

Results

CTCs and CECs were related to clinicopathological characteristics. Triploid CTCs, tetraploid CTCs, and total CECs were found to be higher in incipient patients than in relapse patients (P = 0.036, P = 0.019, and P = 0.025, respectively). The number of total CECs and large cell CECs was also associated with advanced tumor stage (P = 0.028 and P = 0.033) and grade (P = 0.028 and P = 0.041). Remarkably, tumor-biomarker-positive CTCs were associated with worse OS and RFS (P = 0.026 and P = 0.038) in NMIBC patients underwent TURBT. CECs cluster was an independent predictor of recurrence in non-high-risk NMIBC patients underwent TURBT (HR = 9.21, P = 0.040). For NAC analysis, pre-NAC tetraploid CTCs and small cell CTCs demonstrated the capability in discriminating NAC-sensitive from insensitive patients. Additionally, tetraploid CTCs and single CTCs elevated post-NAC would indicate chemoresistance.

Conclusion

CTCs and CECs may putatively guide in diagnosis, prognosis prediction, and therapeutic decision-making for bladder cancer.

Identification of miR-20a-5p as Robust Normalizer for Urine microRNA Studies in Renal Cell Carcinoma and a Profile of Dysregulated microRNAs

Renal cell carcinoma (RCC) is the third most frequent urinary malignancy and one of the most lethal. Current diagnostic and follow-up techniques are harmful and unspecific in low-grade tumors. Novel minimally invasive markers such as urine microRNAs (miRNAs) are under study. However, discrepancies arise among studies in part due to lack of consent regarding normalization. We aimed to identify the best miRNA normalizer for RCC studies performed in urine samples together with a miRNA profile with diagnostic value and another for follow-up. We evaluated the performance of 120 candidate miRNAs in the urine of 16 RCC patients and 16 healthy controls by RT-qPCR followed by a stability analysis with RefFinder. In this screening stage, miR-20a-5p arose as the most stably expressed miRNA in RCC and controls, with a good expression level. Its stability was validated in an independent cohort of 51 RCC patients and 32 controls. Using miR-20a-5p as normalizer, we adjusted and validated a diagnostic model for RCC with three miRNAs (miR-200a-3p, miR-34a-5p and miR-365a-3p) (AUC = 0.65; Confidence Interval 95% [0.51, 0.79], p = 0.043). let-7d-5p and miR-205-5p were also upregulated in patients compared to controls. Comparing RCC samples before surgery and fourteen weeks after, we identified let-7d-5p, miR-152-3p, miR-30c-5p, miR-362-3p and miR-30e-3p as potential follow-up profile for RCC. We identified validated targets of most miRNAs in the renal cell carcinoma pathway. This is the first study that identifies a robust normalizer for urine RCC miRNA studies, miR-20a-5p, which may allow the comparison of future studies among laboratories. Once confirmed in a larger independent cohort, the miRNAs profiles identified may improve the non-invasive diagnosis and follow-up of RCC.