Continuous bladder infusion methods for studying voiding function in the ambulatory mouse

Arsenic-induced disruption of circadian rhythms and glutamine anaplerosis in human urothelial carcinoma

Inorganic arsenic (iAs)-induced urothelial carcinoma (UC) develops into a poor-prognosis malignancy. Arsenic-induced oxidative stress contributes to circadian rhythm disruption altered metabolism. Glutamine anaplerosis is a common metabolic feature of rapidly proliferating malignant cells, in which glutaminase (GLS) is a key enzyme in this process. Therefore, this study intends to determine if arsenic-induced oxidative stress can alter circadian rhythms and promote glutamine anaplerosis. Exonic expression of core circadian molecules (CLOCK, ARNTL, and NR1D1) and GLS in varying grades of UC were assessed using 423 bladder cancer samples from the TCGA Urothelial Bladder Cancer (BLCA) dataset. The levels of circadian proteins and metabolic markers in 44 UC patients from non-black foot disease (BFD) and BFD areas were detected by immunohistochemistry. In vitro and in vivo experiments elucidated the regulatory mechanisms of arsenic-mediated circadian disturbance and metabolic alteration. Public database analysis showed that ARNTL, NR1D1, and GLS exhibited greater expression in more high-grade UC. Strong immunoreactivity for BMAL1, GLS, and low levels of NR1D1 were found in malignant urothelial lesions, especially in arsenic-exposed UC. Arsenic-induced overexpression of BMAL1 and GLS involves activation of NADH: quinone oxidoreductase 1 (NQO1), continuously altering the NADH oscillations to promote glutamate metabolism in SV-HUC-1, T24 and BFTC-905 cells. These phenomenon were also demonstrated in the urothelium of arsenic-exposed animals. The present findings highlight the potential clinical significance of BMAL1 and GLS in UC in the BFD region. Furthermore, these results suggest that arsenic interferes with circadian rhythm and glutamine anaplerosis by NADH oscillatory imbalance in urothelial cells and urothelial cancer cells, predisposing them to malignant development.

Modeling of chronic radiation-induced cystitis in mice

Purpose

Radiation cystitis (RC), a severe inflammatory bladder condition, develops as a side effect of pelvic radiation therapy in cancer patients. There are currently no effective therapies to treat RC, in part from the lack of preclinical model systems. In this study, we developed a mouse model for RC and used a Small Animal Radiation Research Platform to simulate the targeted delivery of radiation as used with human patients.

Methods and materials

To induce RC, C3H mice received a single radiation dose of 20 Gy delivered through 2 beams. Mice were subjected to weekly micturition measurements to assess changes in urinary frequency. At the end of the study, bladder tissues were processed for histology.

Results

Radiation was well-tolerated; no change in weight was observed in the weeks after treatment, and there was no hair loss at the irradiation sites. Starting at 17 weeks after treatment, micturition frequency was significantly higher in irradiated mice versus control animals. Pathological changes include fibrosis, inflammation, urothelial thinning, and necrosis. At a site of severe insult, we observed telangiectasia, absence of uroplakin-3 and E-cadherin relocalization.

Conclusions

We developed an RC model that mimics the human pathology and functional changes. Furthermore, radiation exposure attenuates the urothelial integrity long-term, allowing for potential continuous irritability of the bladder wall from exposure to urine. Future studies will focus on the underlying molecular changes associated with this condition and investigate novel treatment strategies.

Aldehyde dehydrogenase induction in arsenic-exposed rat bladder epithelium

Arsenic is widely distributed in the environment. Many human cancers, including urothelial carcinoma (UC), show a dose-dependent relationship with arsenic exposure in the south-west coast of Taiwan (also known as the blackfoot disease (BFD) areas). However, the molecular mechanisms of arsenic-mediated UC carcinogenesis has not yet been defined. In vivo study, the rat bladder epithelium were exposed with arsenic for 48 h. The proteins were extracted from untreated and arsenic-treated rat bladder cells and utilized two-dimensional gel electrophoresis and mass spectrometry. Selected peptides were extracted from the gel and identified by quadrupole-time of flight (Q-TOF) Ultima-Micromass spectra. The significantly difference expression of proteins in arsenic-treated groups as compared with untreated groups was confirmed by immunohistochemistry (IHC) and western blotting. We found that thirteen proteins were down-regulated and nine proteins were up-regulated in arsenic-treated rat bladder cells when compared with untreated groups. The IHC and western blotting results confirmed that aldehyde dehydrogenase (ALDH) protein was up-regulated in arsenic-treated rat bladder epithelium. Expression of ALDH protein was significantly higher in UC patients from BFD areas than those from non-BFD areas using IHC (p=0.018). In conclusion, the ALDH protein expression could be used as molecular markers for arsenic-induced transformation.

Roles of oxidative stress and the ERK1/2, PTEN and p70S6K signaling pathways in arsenite-induced autophagy

Studies show that arsenite induces oxidative stress and modifies cellular function via phosphorylation of proteins and inhibition of DNA repair enzymes. Autophagy, which has multiple physiological and pathological roles in cellular function, is initiated by oxidative stress and is regulated by the signaling pathways of phosphatidylinositol 3-phosphate kinase (PI3K)/mammalian target of rapamycin (mTOR)/p70S6 kinase (p70S6K) and extracellular signaling-regulated protein kinase 1/2 (ERK1/2) that play important roles in oncogenesis. However, the effects of arsenite-induced oxidative stress on autophagy and on expression of related proteins are not fully understood. This study found that cells treated with sodium arsenite had reduced 8-oxoguanine DNA glycosylase 1 (OGG1) and increased 8-hydroxy-2'-deoxyguanosine (8-OHdG) and activating transcription factor (ATF) 3 in SV-40 immortalized human uroepithelial (SV-HUC-1) cells. Arsenite also increased the number of autophagosomes and increased levels of the autophagy markers Beclin-1 and microtubule-associated protein 1 light chain 3B. Reactive oxygen species scavenger decreased arsenite-induced autophagy in SV-HUC-1 cells. Our previous work showed that arsenite induced phosphorylation of the ERK1/2 signaling pathway. The current study further showed that arsenite decreased phosphatase and tensin homologue (PTEN) levels and increased phospho-p70S6 kinase (p-p70S6K) in SV-HUC-1 cells. However, both kinase inhibitor U0126 and the DNA (cytosine-5-)-methyltransferase 1 (DNMT1) inhibitor 5-aza-deoxycytidine abolished the effect of arsenite on expressions of PTEN and p-p70S6K. These results show that autophagy induced by arsenite exposure is mediated by oxidative stress, which regulates activation of the PTEN, p70S6K and ERK1/2 signaling pathways. Thus, this study clarifies the role of autophagy in arsenite-induced urothelial carcinogenesis.

Expression of WWOX and FHIT is downregulated by exposure to arsenite in human uroepithelial cells

Ecological studies in Taiwan, Chile, Argentina, Bangladesh, and Mexico have confirmed significant dose-dependent associations between ingestion of arsenic-contaminated drinking water and the risk of various human malignancies. The FHIT and WWOX genes are active in common fragile sites FRA3B and FRA16D, respectively. Reduced expression of FHIT or WWOX is known to be an early indicator of carcinogen-induced cancers. However, the effect of arsenite on the expressions and molecular mechanisms of these markers is still unclear. The aims of this study were (i) to observe the expression of ATR, WWOX and FHIT proteins in urothelial carcinoma (UC) between endemic and non-endemic areas of blackfoot disease (BFD) by immunohistochemical analyses; (ii) to compare expression of these genes between arsenite-treated SV-HUC-1 human epithelial cells and rat uroepithelial cells; and (iii) to determine the role of DNMT and MEK inhibitors on expressions of WWOX and FHIT in response to arsenite in SV-HUC-1. The experiments revealed that expressions of ATR, WWOX and FHIT in UC significantly differed between BFD areas and non-BFD areas (p=0.003, 0.009 and 0.021, respectively). In fact, the results for the arsenite-treated groups showed that ATR, WWOX and FHIT are downregulated by arsenite in SV-HUC-1. However, the inhibitors suppressed the effects of arsenite on WWOX and FHIT proteins and mRNA expression. In conclusion, arsenite decreased expressions of ATR, WWOX and FHIT via ERK1/2 activation in SV-HUC-1 cells. These findings confirm that dysregulations of these markers may contribute to arsenite-induced carcinogenesis.