Whole-genome gene expression analysis in urine samples of patients with prostate cancer and benign prostate hyperplasia

FAM46B Promotes Apoptosis and Inhibits Glycolysis of Prostate Cancer Through Inhibition of the MYC-LDHA Axis

Objective

Increased dependence on glycolysis is a known element of cancer. This study was designed to examine critical glycolysis components including transcription factor MYC and its downstream target lactate dehydrogenase A (LDHA), potential upstream regulators of glycolysis such as family with sequence similarity 46 member B (FAM46B), and the impact of the abundance of these proteins on apoptosis and glycolysis in prostate cancer.

Materials and Methods

A total of 70 primary prostate cancer patient samples were compared to normal tissues for FAM46B and LDHA expression and the corresponding patients’ survival was monitored for 60 months. Prostate cancer cell lines were employed for protein expression manipulation, glucose uptake and LDH assays, and apoptosis measurements. A xenograft mouse model was used to quantify the role of FAM46B and LDHA on tumor growth in vivo.

Results

FAM46B expression was reduced in prostate tumor tissue compared to normal tissue and prostate cancer patients who expressed low amounts of FAM46B had shortened average lifespans compared to those who expressed higher amounts of FAM46B (p=0.008). FAM46B overexpression reduced glucose uptake, decreased LDH activity, and induced apoptosis in prostate cancer cell lines while FAM46B shRNA increased MYC levels in a non-malignant prostate cell line (P69). Conversely, forced expression of LDHA in LNCaP cells produced an increase in glycolysis markers with a corresponding decrease in apoptosis. FAM46B-overexpressing xenografts had starkly blunted growth which was restored with co-overexpression of LDHA.

Conclusion

FAM46B plays a central role in regulating glycolysis and apoptosis in prostate cancer and operates through the regulation of LDHA via MYC. FAM46B’s keystone status in prostate cancer makes it a potential, robust biomarker for prostate cancer prognosis and a promising therapeutic target.

Biomarkers That Differentiate Benign Prostatic Hyperplasia from Prostate Cancer: A Literature Review

Prediction of prostate cancer in primary care is typically based upon serum total prostate-specific antigen (tPSA) and digital rectal examination results. However, these tests lack sensitivity and specificity, leading to over-diagnosis of disease and unnecessary, invasive biopsies. Therefore, there is a clinical need for diagnostic tests that can differentiate between benign conditions and early-stage malignant disease in the prostate. In this review, we evaluate research papers published from 2009 to 2019 reporting biomarkers that identified or differentiated benign prostatic hyperplasia (BPH) from prostate cancer. Our review identifies hundreds of potential biomarkers in urine, serum, tissue, and semen proposed as useful targets for differentiating between prostate cancer and BPH patients. However, it is still not apparent which of these candidate biomarkers are most useful, and many will not progress beyond the discovery stage unless they are properly validated for clinical practice. We conclude that this validation will come through the use of multivariate panels which can assess the value of biomarker candidates in combination with clinical parameters as part of a risk prediction calculator. Implementation of such a model will help clinicians stratify patients with prostate cancer symptoms in primary care, with tangible benefits for both the patient and the health service.

FAM46B inhibits cell proliferation and cell cycle progression in prostate cancer through ubiquitination of β-catenin

FAM46B is a member of the family with sequence similarity 46. Little is known about the expression and functional role(s) of FAM46B in prostate cancer (PC). In this study, the expression of FAM46B expression in The Cancer Genome Atlas, GSE55945, and an independent hospital database was measured by bioinformatics and real-time PCR analysis. After PC cells were transfected with siRNA or a recombinant vector in the absence or presence of a β-catenin signaling inhibitor (XAV-939), the expression levels of FAM46B, C-myc, Cyclin D1, and β-catenin were measured by western blot and real-time PCR. Cell cycle progression and cell proliferation were measured by flow cytometry and the CCK-8 assay. The effects of FAM46B on tumor growth and protein expression in nude mice with PC tumor xenografts were also measured. Our results showed that FAM46B was downregulated but that β-catenin was upregulated in patients with PC. FAM46B silencing promoted cell proliferation and cell cycle progression in PC, which were abrogated by XAV-939. Moreover, FAM46B overexpression inhibited PC cell cycle progression and cell proliferation in vitro and tumor growth in vivo. FAM46B silencing promoted β-catenin protein expression through the inhibition of β-catenin ubiquitination. Our data clearly show that FAM46B inhibits cell proliferation and cell cycle progression in PC through ubiquitination of β-catenin.

A little-studied protein may help in early diagnosis and treatment of prostate cancer (PC), one of the most common cancers in men. Because early-stage PC causes few symptoms, many patients are not diagnosed until later stages, when treatment options are limited. New methods for early diagnosis and treatment are actively sought. Proteins in the FAM46 family are known to be involved in many types of cancer. Dongliang Yan at Shanghai Sixth People’s Hospital East and co-workers investigated what role one protein in this family, FAM46B, might play in PC. Analysis of tumor samples showed that FAM46B levels were much lower in PC than in healthy tissues. These changes were linked to another tumor-associated protein, β-catenin. In further tests in mice, artificially increasing FAM46B levels decreased tumor size. These results could improve treatments for PC.