Genetically elevated bioavailable testosterone level was associated with the occurrence of benign prostatic hyperplasia

Genetic Predisposition to Benign Prostatic Hyperplasia: Where Do We Stand?

Background and objective

Genetic predisposition is a factor in 40-70% of cases of benign prostatic hyperplasia (BPH) and voiding symptoms. However, informal reviews summarizing genes and variants imparting genetic disposition to BPH are not yet available.

Methods

We conducted an informal narrative review of genes and variants associated with BPH or voiding symptoms in candidate gene studies, genome-wide association studies (GWAS), and Mendelian randomization studies. A literature search of PubMed was performed using the terms "BPH heritability", "LUTS heritability", "BPH risk variant", "LUTS genetic risk", "GWAS BPH", and "genome-wide BPH".

Key findings and limitations

Candidate gene studies focused on variants related to the vitamin D receptor, steroid metabolism, detoxification, inflammation, cytokines, and growth factors, which were previously found to be associated with prostate cancer. Despite overall limited conclusiveness of candidate gene approaches, some recent studies point to population-dependent contributions of single variants to genetic BPH predisposition. Four GWAS and two Mendelian randomization studies for BPH identified correlation of BPH and voiding symptoms with variants related to testosterone, prostate-specific antigen, progesterone, transcription factors, the cell cycle, neuronal organization, and thyroid-stimulating hormone.

Conclusions and clinical implications

The drug targetability of most of the genes identified in the BPH setting is precluded by predictable unbalanced side effects, low efficacy, unknown organ specificity, and a lack of characterization in the prostate. Meta-analyses of GWAS are not yet available for BPH. Unless calculated using quantitative approaches, specific contributions of the risk variants identified to the overall risk of BPH remain uncertain.

Patient summary

While age is a risk factor for benign enlargement of the prostate in all affected patients, genetic factors may be involved in 39-72% of patients. Research has identified a number of possible risk genes, but is still at a very early stage. It is unlikely that drugs could be used to target these genes because of expected side effects that would be tolerated for cancer treatment, but not for benign diseases, or low efficacy in previous clinical trials.

Association between dietary niacin intake and benign prostatic hyperplasia: a population-based results from NHANES 2003-2008

PURPOSE

Benign prostatic hyperplasia (BPH) commonly impacts the quality of life in older men. However, there is lack of research on relationship between dietary niacin intake and the risk of BPH. The purpose of this study was to investigate the relationship between dietary niacin intake and the risk of BPH.

METHODS

Data from the NHANES spanning 2003 to 2008 were utilized. BPH was determined using a self-report questionnaire, while dietary niacin intake was calculated based on the mean of two distinct diet interviews. Multivariate logistic regressions were performed to explore the association, supplemented with restricted cubic splines and subgroup analysis.

RESULTS

A total of 700 males were enrolled, of which 653 men had BPH. After adjusting for all covariates, a high dietary intake of niacin was associated with an increased risk of BPH (OR: 1.04; 95%CI: 1.01-1.07). Furthermore, when the lowest dietary niacin intake is used as the reference, the highest tertile is associated with an increased risk of BPH (OR: 2.34, 95% CI: 1.24-4,42). Restricted cubic splines demonstrated a positive correlation between dietary niacin intake and BPH risk.

CONCLUSIONS

The study results demonstrated a positive association between dietary niacin intake and the risk of BPH in elderly men in the US. These findings underscore the importance of systematic assessment before supplementing micronutrients in elderly men.

Assessment of glycemic susceptibility across multiple urological and reproductive disorders

OBJECTIVE

To test the glycemic susceptibility in three urological cancers and eight urological/reproductive diseases using the Mendelian randomization (MR) method.

MATERIALS AND METHODS

Two-sample MR was applied to investigate the causal role of three glycemic traits (type II diabetes, fasting glucose and glycated hemoglobin (HbA1c)) in eleven urological/reproductive diseases (kidney cancer, bladder cancer, prostate cancer, kidney/ureter stone, urinary incontinence, benign prostatic hyperplasia, erectile dysfunction, female infertility, male infertility, abnormal spermatozoa and polycystic ovary syndrome). Further multivariate MR (MVMR) and mediating analysis were performed to investigate the associations.

RESULTS

Among all the 11 diseases, type II diabetes was positively associated with erectile dysfunction, which was stable across both cohorts [odds ratio (OR): 1.59, 95% confidence interval (CI): 1.15-2.20, P = 0.005 for FinnGen Biobank and OR: 1.14, 95% CI: 1.08-1.21, P < 0.001 for the other cohort]. Also, type II diabetes was negatively associated with male infertility (OR: 0.57, 95% CI: 0.39-0.84, P = 0.005). In addition, all three glycemic traits were observed to be positively associated with polycystic ovary syndrome (OR: 2.36, 95% CI: 1.16-4.76, P = 0.017 for fasting glucose per mmol/L; OR: 3.04, 95% CI: 1.10-8.39, P = 0.032 for HbA1c per percentage; and OR: 1.21, 95% CI: 1.00-1.46, P = 0.046 for type II diabetes). Mediating analysis confirmed the effect of type II diabetes on these diseases.

CONCLUSIONS

There existed glycemic susceptibility in erectile dysfunction, male infertility and polycystic ovary syndrome. We could not conclude stable glycemic susceptibility in other urological/reproductive diseases.

Does metformin really reduce prostate cancer risk: an up-to-date comprehensive genome-wide analysis

BACKGROUND

The relationship between metformin use and prostate cancer (PCa) risk has yet to be clear despite more than a decade of debate on this topic. Hence, we aimed to investigate the causal role of metformin in reducing PCa risk through an up-to-date comprehensive genome-wide analysis.

METHODS

We employed validated instrument variables of metformin use derived from a prior high-quality study, including five potential targets (AMPK, GCG, GDF15, MCI and MG3). Mendelian randomization (MR) analysis was performed to harmonize genetically predicted metformin use and PCa phenotypes. PCa phenotypes were from two large genome-wide association studies (GWAS), the Prostate Cancer Association Group to Investigate Cancer-Associated Alterations in the Genome (PRACTICAL) and the FinnGen cohort. Seven methods were applied to generate MR results: the inverse variance weighted (IVW), IVW with multiplicative random effects, MR-Egger, MR-Egger (bootstrap), weighted median, simple mode and weighted mode. Strict sensitivity analysis was conducted to satisfy core assumptions of MR design.

RESULTS

We enrolled 32 significant single nucleotide polymorphisms (SNPs) that involved with metformin use. Nearly all targets yielded insignificant primary results (IVW with multiplicative random effects), except that AMPK target posed a positive effect on PCa risk from FinnGen cohort [odds ratio (OR): 6.09, 95% confidence interval (CI): 1.10-33.53, P value: 0.038]. The general effect of metformin use, comprising all 5 targets, also yielded negative results (random-effect meta-analysis with OR: 1.09, 95% CI: 0.76-1.58, P value: 0.637 for PRACTICAL; OR: 2.55, 95% CI: 0.58-11.16, P value: 0.215 for FinnGen). None of the sensitivity analyses provided support for a causal association between metformin use and PCa risk.

CONCLUSION

This up-to-date study did not support the protective role of metformin in reducing PCa risk, considering each target, overall effect, and sensitivity analysis. It is imperative to reflect on the presumed "almighty medicine" and ongoing phase III trials are anticipated to assess the anti-neoplasm effect of metformin.

Genetic susceptibility of urolithiasis: comprehensive results from genome-wide analysis

BACKGROUND

The pathogenesis of urolithiasis is multi-factorial and genetic factors have been shown to play a significant role in the development of urolithiasis. We tried to apply genome-wide Mendelian randomization (MR) analysis and figure out reliable gene susceptibility of urolithiasis from the largest samples to date in two independent genome-wide association studies (GWAS) database of European ancestry.

METHODS

We extracted summary statistics of expression quantitative trait locus (eQTL) from eQTLGen consortium. Urolithiasis phenotype information was obtained from both FinnGen Biobank and UK Biobank. Multiple two-sample MR analysis with a Bonferroni-corrected P threshold (P < 2.5e-06) was conducted. The primary endpoint was the causal effect calculated by random-effect inverse variance weighted (IVW) method. Sensitivity analysis, volcano plots, scatter plots, and regional plots were also performed and visualized.

RESULTS

After multiple MR tests between 19942 eQTLs and urolithiasis phenotype from both cohorts, 30 common eQTLs with consistent effect size direction were found to be causally associated with urolithiasis risk. Finally only one gene (LMAN2) was simultaneously identified among all top significant eQTLs from both FinnGen Biobank (beta = 0.6758, se = 0.0327, P = 6.775e-95) and UK Biobank (beta = 0.0044, se = 0.0009, P = 2.417e-06). We also found that LMAN2 was with the largest beta effect size on urolithiasis phenotype from the two cohorts.

CONCLUSION

We for the first time implemented genome-wide MR analysis to investigate the genetic susceptibility of urolithiasis in general population of European ancestry. Our results provided novel insights into common genetic variants of urinary stone disease, which was of great help to subsequent researches.

Investigating the causal associations between metabolic biomarkers and the risk of kidney cancer

Metabolic reprogramming plays an important role in kidney cancer. We aim to investigate the causal effect of 249 metabolic biomarkers on kidney cancer from population-based data. This study extracts data from previous genome wide association studies with large sample size. The primary endpoint is random-effect inverse variance weighted (IVW). After completing 249 times of two-sample Mendelian randomization analysis, those significant metabolites are included for further sensitivity analysis. According to a strict Bonferrion-corrected level (P < 2e-04), we only find two metabolites that are causally associated with renal cancer. They are lactate (OR:3.25, 95% CI: 1.84-5.76, P = 5.08e-05) and phospholipids to total lipids ratio in large LDL (low density lipoprotein) (OR: 0.63, 95% CI: 0.50-0.80, P = 1.39e-04). The results are stable through all the sensitivity analysis. The results emphasize the central role of lactate in kidney tumorigenesis and provide novel insights into possible mechanism how phospholipids could affect kidney tumorigenesis.

SGLT2 inhibition and three urological cancers: Up-to-date results

OBJECTIVE

To identify the causal role of sodium-glucose cotransporter 2 (SGLT2) inhibition on three urological cancers.

METHODS

Six single nucleotide polymorphisms associated with the expression level of SLC5A2, a proxy for SGLT2 inhibition, from a recent publication were extracted. Three common urological cancers, including bladder cancer, prostate cancer and kidney cancer, were analysed. The main cohort of bladder cancer was derived from UK Biobank (1279 cases and 372,016 controls). The prostate cancer cohort was from the Prostate Cancer Association Group to Investigate Cancer Associated Alterations in the Genome (PRACTICAL) consortium (79,148 cases and 61,106 controls). The kidney cancer phenotype was from the UK Biobank cohort of 463,010 individuals (1114 cases and 461,896 controls). Primary and sensitivity analysis were performed to validate the results. In vitro analysis was also incorporated to validate the Mendelian randomisation results.

RESULTS

In primary analysis, SGLT2 inhibition was associated with reduced risk of bladder cancer (OR: 0.98, 95% CI: 0.97-0.99) per unit lowering of HbA1c level. A protective association was also observed for prostate cancer with odds ratio = 0.31 (95% CI = 0.21-0.47). However, we did not discover a causal relationship between SGLT2 inhibition and kidney cancer (OR: 1.00, 95% CI: 0.99-1.00). Sensitivity analysis and in vitro validation did not support the causal role of SGLT2 inhibition in increasing cancer risk.

CONCLUSIONS

We did not find any evidence that SGLT2 inhibition could increase the risk of the three cancers. Even in some analysis, SGLT2 inhibition tended to show protective effects on the three urological cancers.

The causal relationship between sarcopenic obesity factors and benign prostate hyperplasia

Background

Both benign prostatic hyperplasia (BPH) and sarcopenic obesity (SO) are common conditions among older adult/adults males. The prevalent lifestyle associated with SO is a significant risk factor for the development of BPH. Therefore, we investigated the causal relationship between SO factors and BPH.

Method

The instrumental variables for SO factors were selected using the inverse variance-weighted method, which served as the primary approach for Mendelian randomization analysis to assess the causal effect based on summary data derived from genome-wide association studies of BPH.

Result

The increase in BMR (OR = 1.248; 95% CI = (1.087, 1.432); P = 0.002) and ALM (OR = 1.126; 95% CI = (1.032, 1.228); P = 0.008) was found to be associated with an elevated risk of BPH. However, no genetic causality between fat-free mass distribution, muscle mass distribution, and BPH was observed.

Conclusion

Our findings indicate that a genetic causal association between BMR, ALM and BPH. BMR and ALM are risk factors for BPH. The decrease in BMR and ALM signified the onset and progression of SO, thus SO is a protective factor for BPH.