Proteomic characterization of arsenic and cadmium exposure in bladder cells

Abstract

Rationale Accumulating evidence has linked prolonged exposure to heavy metals to cancer occurrence in the urinary system. However, the specific biological mechanisms responsible for the association of heavy metals with the unusually high incidence of upper tract urothelial carcinoma in Taiwan are complex and incompletely understood. Methods To elucidate the specific biological mechanism and identify molecular indicators of the unusually high association of upper tract urothelial carcinoma with heavy metal exposure, protein expression following the treatment of T24 human bladder carcinoma and RT4 human bladder papilloma cell line models with arsenic (As) and cadmium (Cd) was studied. Proteomic changes in these cell models were integrated with data from a human bladder cancer (BLCA) tissue proteome to identify possible protein indicators of heavy metal exposure. Results After mass spectrometry based proteomic analysis and verification by Western blotting procedures, we identified 66 proteins that were up‐regulated and 92 proteins that were down‐regulated in RT4 cell extracts after treatment with As or Cd. Some 52 proteins were up‐regulated and 136 proteins were down‐regulated in T24 cell extracts after treatment with Cd. We further confirmed that down‐expression of the PML (promyelocytic leukemia) protein was sustained for at least 75 days after exposure of bladder cells to As. Dysregulation of these cellular proteins by As was associated with three biological pathways. Immunohistochemical analyses of paraffin‐embedded BLCA tissue slides confirmed that PML protein expression was decreased in BLCA tumor cells compared with adjacent noncancerous epithelial cells. Conclusions These data suggest that PML may play an important role in the pathogenesis of BLCA and may be an indicator of heavy metal exposure in bladder cells.

Temporal Modulation of Differential Alternative Splicing in HaCaT Human Keratinocyte Cell Line Chronically Exposed to Arsenic for up to 28 Wk

“…Multiple mechanisms can give rise to changes in the proteome, including differential transcription and translation (Hoogendijk et al 2019;Ishikawa 2021;Iwasaki and Ingolia 2017;Vogel and Marcotte 2012), alternative splicing (Liu et al 2017), and differential protein degradation (Grandi and Bantscheff 2019). Several of these mechanisms have been studied regarding arsenic toxicity (Al-Eryani et al 2018a;Berglund et al 2009;Chen et al 2020b;Riedmann et al 2015;, but the role of differential alternative splicing remains poorly understood. One previous study in the arsenicexposed Ad12-SV40 2B cell line model of arsenic-induced lung carcinogenesis demonstrated 104 differential alternative splicing events (Riedmann et al 2015).…”