Beclin-1 expression in normal bladder and in Cd and As exposed and transformed human urothelial cells (UROtsa)

The expression of beclin-1 in normal human bladder and in Cd²⁺ and As³⁺ exposed and transformed urothelial cells (UROtsa) was examined in this study. It was shown using a combination of real-time PCR, Western analysis and immunohistochemistry that beclin-1 was expressed in the urothelial cells of the normal bladder. It was also demonstrated that the parental UROtsa cell line expressed beclin-1 mRNA and protein at levels similar to that of the in situ urothelium. The level of beclin-1 expression underwent only modest alterations when the UROtsa cells were malignantly transformed by Cd²⁺ or As³⁺ or when the parental cells were exposed acutely to Cd²⁺ or As³⁺. While there were instances of significant alterations at individual time points and within cell line-to-cell line comparisons there was no evidence of a dose–response relationship or correlations to the phenotypic properties of the cell lines. Similar results were obtained for the expression of the Atg-5, Atg-7, Atg-12 and LC3B autophagy-related proteins. The findings provide initial evidence for beclin-1 expression in normal bladder and that large alterations in the expression of beclin-1 and associated proteins do not occur when human urothelial cells are malignantly transformed with, or exposed to, either Cd²⁺ or As^3+.