The mitochondrial pathway of apoptosis is controlled by the ratio of anti-and pro-apoptotic members of the Bcl-2 family of proteins. The molecular events underlying how a given physiological stimulus changes this ratio to trigger apoptosis remains unclear. We report here that human 17-b-estradiol (E2) and its related steroid hormones induce apoptosis by binding directly to phosphodiesterase 3A, which in turn recruits and stabilizes an otherwise fast-turnover protein Schlafen 12 (SLFN12). The elevated SLFN12 binds to ribosomes to exclude the recruitment of signal recognition particles (SRPs), thereby blocking the continuous protein translation occurring on the endoplasmic reticulum of E2-treated cells. These proteins include Bcl-2 and Mcl-1, whose ensuing decrease triggers apoptosis. The SLFN12 protein and an apoptosis activation marker were co-localized in syncytiotrophoblast of human placentas, where levels of estrogen-related hormones are high, and dynamic cell turnover by apoptosis is critical for successful implantation and placenta development.

No abstract

IntroductionBladder cancer (BC) is one of the most prevalent urinary cancers, and its management is still a problem causing recurrence and progression, elevating mortality.Materials and MethodsWe aimed at the nuclear mitochondria-related genes (MTRGs), collected from the MITOMAP: A Human Mitochondrial Genome Database. Meanwhile, the expression profiles and clinical information of BC were downloaded from the Cancer Genome Atlas (TCGA) as a training group. The univariate, multivariate, and the least absolute shrinkage and selection operator (LASSO) Cox regression analyses were used to construct a nuclear mitochondrial-related multi-genes signature and the prognostic nomogram.ResultsA total of 17 nuclear MTRGs were identified to be correlated with the overall survival (OS) of BC patients, and a nuclear MTRGs signature based on 16 genes expression was further determined by the LASSO Cox regression analysis. Based on a nuclear MTRGs scoring system, BC patients from the TCGA cohort were divided into high- and low- nuclear MTRGs score groups. Patients with a high nuclear MTRGs score exhibited a significantly poorer outcome (median OS: 92.90 vs 20.20 months, p<0.0001). The nuclear MTRGs signature was further verified in three independent datasets, namely, GSE13507, GSE31684, and GSE32548, from the Gene Expression Omnibus (GEO). The BC patients with a high nuclear MTRGs score had significantly worse survival (median OS in GSE13507: 31.52 vs 98.00 months, p<0.05; GSE31684: 32.85 months vs unreached, p<0.05; GSE32548: unreached vs unreached, p<0.05). Furthermore, muscle-invasive bladder cancer (MIBC) patients had a significantly higher nuclear MTRGs score (p<0.05) than non-muscle-invasive bladder cancer (NMIBC) patients. The integrated signature outperformed each involved MTRG. In addition, a nuclear MTRGs-based nomogram was constructed as a novel prediction prognosis model, whose AUC values for OS at 1, 3, 5 years were 0.76, 0.75, and 0.75, respectively, showing the prognostic nomogram had good and stable predicting ability. Enrichment analyses of the hallmark gene set and KEGG pathway revealed that the E2F targets, G2M checkpoint pathways, and cell cycle had influences on the survival of BC patients. Furthermore, the analysis of tumor microenvironment indicated more CD8+ T cells and higher immune score in patients with high nuclear MTRGs score, which might confer sensitivity to immune checkpoint inhibitors.ConclusionsNot only could the signature and prognostic nomogram predict the prognosis of BC, but it also had potential therapeutic guidance.

This is an open access article under the terms of the Creat ive Commo ns Attri bution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.