Monitoring high-risk bladder cancer

Acetyl-CoA synthetase 3 promotes bladder cancer cell growth under metabolic stress

Cancer cells adapt to nutrient-deprived tumor microenvironment during progression via regulating the level and function of metabolic enzymes. Acetyl-coenzyme A (AcCoA) is a key metabolic intermediate that is crucial for cancer cell metabolism, especially under metabolic stress. It is of special significance to decipher the role acetyl-CoA synthetase short chain family (ACSS) in cancer cells confronting metabolic stress. Here we analyzed the generation of lipogenic AcCoA in bladder cancer cells under metabolic stress and found that in bladder urothelial carcinoma (BLCA) cells, the proportion of lipogenic AcCoA generated from glucose were largely reduced under metabolic stress. Our results revealed that ACSS3 was responsible for lipogenic AcCoA synthesis in BLCA cells under metabolic stress. Interestingly, we found that ACSS3 was required for acetate utilization and histone acetylation. Moreover, our data illustrated that ACSS3 promoted BLCA cell growth. In addition, through analyzing clinical samples, we found that both mRNA and protein levels of ACSS3 were dramatically upregulated in BLCA samples in comparison with adjacent controls and BLCA patients with lower ACSS3 expression were entitled with longer overall survival. Our data revealed an oncogenic role of ACSS3 via regulating AcCoA generation in BLCA and provided a promising target in metabolic pathway for BLCA treatment.

Integrated proteomic and phosphoproteomic analyses of cisplatin-sensitive and resistant bladder cancer cells reveal CDK2 network as a key therapeutic target

BACKGROUND

Cisplatin-based chemotherapy is currently part of the standard of care for bladder cancer (BC). Unfortunately, some patients respond poorly to chemotherapy and have acquired or developed resistance. The molecular mechanisms underlying this resistance remain unclear. Here, we introduce a multidimensional proteomic analysis of a cisplatin-resistant BC model that provides different levels of protein information, including that of the global proteome and phosphoproteome.

METHODS

To characterize the global proteome and phosphoproteome in cisplatin-resistant BC cells, liquid chromatography-mass spectrometry/mass spectrometry experiments combined with comprehensive bioinformatics analysis were performed. Perturbed expression and phosphorylation levels of key kinases associated with cisplatin resistance were further studied using various cell biology assays, including western blot analysis.

RESULTS

Analyses of protein expression and phosphorylation identified significantly altered proteins, which were also EGF-dependent and independent. This suggests that protein phosphorylation plays a significant role in cisplatin-resistant BC. Additional network analysis of significantly altered proteins revealed CDK2, CHEK1, and ERBB2 as central regulators mediating cisplatin resistance. In addition to this, we identified the CDK2 network, which consists of CDK2 and its 5 substrates, as being significantly associated with poor survival after cisplatin chemotherapy.

CONCLUSIONS

Collectively, these findings potentially provide a novel way of classifying higher-risk patients and may guide future research in developing therapeutic targets.

Rewiring of cisplatin-resistant bladder cancer cells through epigenetic regulation of genes involved in amino acid metabolism

Alterations in DNA methylation are important epigenetic markers in bladder cancer (BC). These epigenome modifications may drive the mechanisms of aggressive chemo-resistant BC. Clinicopathological biomarkers that indicate chemotherapeutic resistance are critical for better assessing treatment strategies for individual patients. Thus, in this study, we aimed to determine whether DNA methylation of certain metabolic enzymes is significantly altered in cisplatin-resistant BC cells. Methods: To characterize CpG methylation and nucleosome accessibility in cisplatin-resistant BC cells, the Illumina Infinium HM450 DNA methylation assay was performed. Perturbed gene expression was found to be associated with cisplatin resistance, and the biological roles of spermidine/spermine N1-acetyltransferase (SAT1) and argininosuccinate synthase 1 (ASS1) were further studied using qRT-PCR analysis and various cell biology assays, including western blot. Results:ASS1 and SAT1, genes for amino acid and polyamine metabolism catalysts, respectively, were found to be vastly hypermethylated, resulting in greatly downregulated expression. ASS1 expression is of particular interest because prior studies have demonstrated its potential association with BC stage and recurrence. In regard to chemoresistance, we found that aberrant expression or induced stimulation of SAT1 restored cisplatin sensitivity in the cell culture system. We also found that the addition of exogenous arginine deiminase through administration of ADI-PEG 20 (pegylated arginine deiminase) increased ASS1 expression and enhanced cisplatin's apoptotic effects. Conclusions: Our study demonstrates a novel mechanistic link between the epigenetic perturbation of SAT1 and ASS1 and cancer metabolism in cisplatin-resistant bladder cancer cells. These findings suggest potential utility of SAT1 and ASS1 as predictive biomarkers in re-sensitizing bladder cancer to chemotherapy and personalizing therapy.

Circulating FABP4 is a prognostic biomarker in patients with acute coronary syndrome but not in asymptomatic individuals

OBJECTIVE

Blood-borne biomarkers reflecting atherosclerotic plaque burden have great potential to improve clinical management of atherosclerotic coronary artery disease and acute coronary syndrome (ACS).

APPROACH AND RESULTS

Using data integration from gene expression profiling of coronary thrombi versus peripheral blood mononuclear cells and proteomic analysis of atherosclerotic plaque-derived secretomes versus healthy tissue secretomes, we identified fatty acid-binding protein 4 (FABP4) as a biomarker candidate for coronary artery disease. Its diagnostic and prognostic performance was validated in 3 different clinical settings: (1) in a cross-sectional cohort of patients with stable coronary artery disease, ACS, and healthy individuals (n=820), (2) in a nested case-control cohort of patients with ACS with 30-day follow-up (n=200), and (3) in a population-based nested case-control cohort of asymptomatic individuals with 5-year follow-up (n=414). Circulating FABP4 was marginally higher in patients with ST-segment-elevation myocardial infarction (24.9 ng/mL) compared with controls (23.4 ng/mL; P=0.01). However, elevated FABP4 was associated with adverse secondary cerebrovascular or cardiovascular events during 30-day follow-up after index ACS, independent of age, sex, renal function, and body mass index (odds ratio, 1.7; 95% confidence interval, 1.1-2.5; P=0.02). Circulating FABP4 predicted adverse events with similar prognostic performance as the GRACE in-hospital risk score or N-terminal pro-brain natriuretic peptide. Finally, no significant difference between baseline FABP4 was found in asymptomatic individuals with or without coronary events during 5-year follow-up.

CONCLUSIONS

Circulating FABP4 may prove useful as a prognostic biomarker in risk stratification of patients with ACS.

From infection to immunotherapy: host immune responses to bacteria at the bladder mucosa

The pathogenesis of urinary tract infection and mechanisms of the protective effect of Bacillus Calmette-Guerin (BCG) therapy for bladder cancer highlight the importance of studying the bladder as a unique mucosal surface. Innate responses to bacteria are reviewed, and although our collective knowledge remains incomplete, we discuss how adaptive immunity may be generated following bacterial challenge in the bladder microenvironment. Interestingly, the widely held belief that the bladder is sterile has been challenged recently, indicating the need for further study of the impact of commensal microorganisms on the immune response to uropathogen infection or intentional instillation of BCG. This review addresses the aspects of bladder biology that have been well explored and defines what still must be discovered about the immunobiology of this understudied organ.