In vitro evidence of the promoting effect of testosterone in kidney stone disease: A proteomics approach and functional validation.

UNLABELLED: Incidence of kidney stone disease in males is 2- to 4-fold greater than in females. This study aimed to determine effects of testosterone on kidney stone disease using a proteomics approach. MDCK renal tubular cells were treated with or without 20nM testosterone for 7days. Cellular proteins were extracted, resolved by 2-DE, and stained with Deep Purple fluorescence dye (n=5 gels derived from 5 independent samples/group). Spot matching, quantitative intensity analysis, and statistics revealed significant changes in levels of nine protein spots after testosterone treatment. These proteins were then identified by nanoLC-ESI-Qq-TOF MS/MS. Global protein network analysis using STRING software revealed α-enolase as the central node of protein-protein interactions. The increased level of α-enolase was then confirmed by Western blotting analysis, whereas immunofluorescence study revealed the increased α-enolase on cell surface and intracellularly. Functional analysis confirmed the potential role of the increased α-enolase in enhanced calcium oxalate monohydrate (COM) crystal-cell adhesion induced by testosterone. Finally, neutralization of surface α-enolase using anti-α-enolase antibody successfully reduced the enhanced COM crystal-cell adhesion to the basal level. Our data provided in vitro evidence of promoting effect of testosterone on kidney stone disease via enhanced COM crystal-cell adhesion by the increased surface α-enolase. BIOLOGICAL SIGNIFICANCE: The incidence of kidney stone disease in male is 2- to 4-fold greater than in female. One of the possible factors of the male preference is the higher testosterone hormone level. However, precise molecular mechanisms that testosterone plays in kidney stone disease remained unclear. Our present study is the first exploratory investigation on such aspect using a proteomics approach. Our data also provide a novel mechanistic aspect of how testosterone can impact the risk of kidney stone formation (i.e. the discovery that testosterone increases alpha-enolase expression on the surface of renal tubular cells that is responsible, at least in part, for crystal-cell adhesion).