Identification and Validation of Leucine-rich α-2-glycoprotein 1 as a Noninvasive Biomarker for Improved Precision in Prostate Cancer Risk Stratification.

BACKGROUND: More accurate risk assessments are needed to improve prostate cancer management. OBJECTIVE: To identify blood-based protein biomarkers that provided prognostic information for risk stratification. DESIGN SETTING AND PARTICIPANTS: Mass spectrometry was used to identify biomarker candidates from blood, and validation studies were performed in four independent cohorts retrospectively collected between 1988 and 2015. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary outcome objectives were progression-free survival, prostate cancer-specific survival (PCSS), and overall survival. Statistical analyses to assess survival and model performance were performed. RESULTS AND LIMITATION: Serum leucine-rich α-2-glycoprotein 1 (LRG1) was found to be elevated in fatal prostate cancer. LRG1 provided prognostic information independent of metastasis and increased the accuracy in predicting PCSS, particularly in the first 3 yr. A high LRG1 level is associated with an average of two-fold higher risk of disease-progression and mortality in both high-risk and metastatic patients. However, our study design, with a retrospective analysis of samples spanning several decades back, limits the assessment of the clinical utility of LRG1 in today's clinical practice. Thus, independent prospective studies are needed to establish LRG1 as a clinically useful biomarker for patient management. CONCLUSIONS: High blood levels of LRG1 are unfavourable in newly diagnosed high-risk and metastatic prostate cancer, and LRG1 increased the accuracy of risk stratification of prostate cancer patients. PATIENT SUMMARY: High blood levels of leucine-rich α-2-glycoprotein 1 are unfavourable in newly diagnosed high-risk and metastatic prostate cancer

Lipid degradation promotes prostate cancer cell survival

Prostate cancer is the most common male cancer and androgen receptor (AR) is the major driver of the disease. Here we show that Enoyl-CoA delta isomerase 2 (ECI2) is a novel AR-target that promotes prostate cancer cell survival. Increased ECI2 expression predicts mortality in prostate cancer patients (p = 0.0086). ECI2 encodes for an enzyme involved in lipid metabolism, and we use multiple metabolite profiling platforms and RNA-seq to show that inhibition of ECI2 expression leads to decreased glucose utilization, accumulation of fatty acids and down-regulation of cell cycle related genes. In normal cells, decrease in fatty acid degradation is compensated by increased consumption of glucose, and here we demonstrate that prostate cancer cells are not able to respond to decreased fatty acid degradation. Instead, prostate cancer cells activate incomplete autophagy, which is followed by activation of the cell death response. Finally, we identified a clinically approved compound, perhexiline, which inhibits fatty acid degradation, and replicates the major findings for ECI2 knockdown. This work shows that prostate cancer cells require lipid degradation for survival and identifies a small molecule inhibitor with therapeutic potential.</p

A differential protein solubility approach for the depletion of highly abundant proteins in plasma using ammonium sulfate

This work reports a precipitation and differential protein solubility approach using saturated ammonium sulfate solutions as a depletion and fractionation approach for shotgun proteomic analysis of plasma samples.</p

O-GlcNAc transferase integrates metabolic pathways to regulate the stability of c-MYC in human prostate cancer cells

Abstract Metabolic disruptions that occur widely in cancers offer an attractive focus for generalized treatment strategies. The hexosamine biosynthetic pathway (HBP) senses metabolic status and produces an essential substrate for O-linked β-N-acetylglucosamine transferase (OGT), which glycosylates and thereby modulates the function of its target proteins. Here, we report that the HBP is activated in prostate cancer cells and that OGT is a central regulator of c-Myc stability in this setting. HBP genes were overexpressed in human prostate cancers and androgen regulated in cultured human cancer cell lines. Immunohistochemical analysis of human specimens (n = 1987) established that OGT is upregulated at the protein level and that its expression correlates with high Gleason score, pT and pN stages, and biochemical recurrence. RNA interference–mediated siliencing or pharmacologic inhibition of OGT was sufficient to decrease prostate cancer cell growth. Microarray profiling showed that the principal effects of OGT inhibition in prostate cancer cells were related to cell-cycle progression and DNA replication. In particular, c-MYC was identified as a candidate upstream regulator of OGT target genes and OGT inhibition elicited a dose-dependent decrease in the levels of c-MYC protein but not c-MYC mRNA in cell lines. Supporting this relationship, expression of c-MYC and OGT was tightly correlated in human prostate cancer samples (n = 1306). Our findings identify HBP as a modulator of prostate cancer growth and c-MYC as a key target of OGT function in prostate cancer cells. Cancer Res; 73(16); 5277–87. ©2013 AACR.</jats:p