Genetics and genomics of prostate cancer

Identification of the cytoplasmic DNA-Sensing cGAS-STING pathway-mediated gene signatures and molecular subtypes in prostate cancer

BACKGROUND

Considering the age relevance of prostate cancer (PCa) and the involvement of the cGAS-STING pathway in aging and cancer, we aim to classify PCa into distinct molecular subtypes and identify key genes from the novel perspective of the cGAS-STING pathway. It is of significance to guide personalized intervention of cancer-targeting therapy based on genetic evidence.

METHODS

The 430 patients with PCa from the TCGA database were included. We integrated 29 key genes involved in cGAS-STING pathway and analyzed differentially expressed genes and biochemical recurrence (BCR)-free survival-related genes. The assessments of tumor stemness and heterogeneity and tumor microenvironment (TME) were conducted to reveal potential mechanisms.

RESULTS

PCa patients were classified into two distinct subtypes using AURKB, TREX1, and STAT6, and subtype 1 had a worse prognosis than subtype 2 (HR: 21.19, p < 0.001). The findings were validated in the MSKCC2010 cohort. Among subtype 1 and subtype 2, the top ten mutation genes were MUC5B, DNAH9, SLC5A10, ZNF462, USP31, SIPA1L3, PLEC, HRAS, MYOM1, and ITGB6. Gene set variation analysis revealed a high enrichment of the E2F target in subtype 1, and gene set enrichment analysis showed significant enrichment of base excision repair, cell cycle, and DNA replication in subtype 1. TME evaluation indicated that subtype 1 had a significantly higher level of T cells follicular helper and a lower level of plasma cells than subtype 2.

CONCLUSIONS

The molecular subtypes mediated by the cGAS-STING pathway and the genetic risk score may aid in identifying potentially high-risk PCa patients who may benefit from pharmacologic therapies targeting the cGAS-STING pathway.

Prostate cancer genotyping for risk stratification and precision treatment

Prostate cancer (PC) is the most frequently diagnosed cancer and second leading cause of cancer-related deaths in men. It is heterogeneous, as is evident from the wide spectrum of therapeutic approaches. Most patients with PC are initially responsive to androgen deprivation therapy; however, the majority of cases are either hormone-sensitive PC or castration-resistant PC. Current therapeutic protocols follow the evolution of PC, a continuously progressive process involving a combination of widespread genomic alterations. These genomic alterations are either hereditary germline mutations, such as mutations in BRCA2, or specific only to tumor cells (somatic). Tumor-specific genomic spectra include genomic structural rearrangements, canonical androgen response genes, and many other specific genes such as TMPRSS2-ERG fusion, SPOP/FOXA1, TP53/RB1/PTEN, and BRCA2. New evidence indicates the involvement of signaling pathways including PI3K, WNT/β-catenin, SRC, and IL-6/STAT, which have been shown to promote epithelial-mesenchymal transition cancer stem cell-like features/stemness, and neuroendocrine differentiation in PC. Over the last decade, our understanding of the genotype-phenotype relationships has been enhanced considerably. The genetic background of PC related to canonical genetic alterations and signaling pathway activation genes has shed more insight into the molecular subtype and disease landscape, resulting in a more flexible role of individual therapies targeting diverse genotypes and phenotypes.

[99mTc]Tc-PSMA-T4-Novel SPECT Tracer for Metastatic PCa: From Bench to Clinic

Despite significant advances in nuclear medicine for diagnosing and treating prostate cancer (PCa), research into new ligands with increasingly better biological properties is still ongoing. Prostate-specific membrane antigen (PSMA) ligands show great potential as radioisotope carriers for the diagnosis and therapy of patients with metastatic PCa. PSMA is expressed in most types of prostate cancer, and its expression is increased in poorly differentiated, metastatic, and hormone-refractory cancers; therefore, it may be a valuable target for the development of radiopharmaceuticals and radioligands, such as urea PSMA inhibitors, for the precise diagnosis, staging, and treatment of prostate cancer. Four developed PSMA-HYNIC inhibitors for technetium-99m labeling and subsequent diagnosis were subjected to preclinical in vitro and in vivo studies to evaluate and compare their diagnostic properties. Among the studied compounds, the PSMA-T4 (Glu-CO-Lys-L-Trp-4-Amc-HYNIC) inhibitor showed the best biological properties for the diagnosis of PCa metastases. [99mTc]Tc-PSMA-T4 also showed effectiveness in single-photon emission computed tomography (SPECT) studies in humans, and soon, its usefulness will be extensively evaluated in phase 2/3 clinical trials.

Review of prostate cancer genomic studies in Africa

Prostate cancer (PCa) is the second most commonly diagnosed in men worldwide and one of the most frequent cancers in men in Africa. The heterogeneity of this cancer fosters the need to identify potential genetic risk factors/biomarkers. Omics variations may significantly contribute to early diagnosis and personalized treatment. However, there are few genomic studies of this disease in African populations. This review sheds light on the status of genomics research on PCa in Africa and outlines the common variants identified thus far. The allele frequencies of the most significant SNPs in Afro-native, Afro-descendants, and European populations were compared. We advocate how these few but promising data will aid in understanding, better diagnosing, and precisely treating this cancer and the need for further collaborative research on the genomics of PCa in the African continent.

High-fat diet during sexual maturation induces hyperplastic differentiation of rat prostate and higher expression of AR45 isoform and ERα

We examined the consequences of high-fat diet (HFD) on prostate histophysiology in two periods along sexual maturation of rats and the impact on the gland in adulthood. After weaning, male Wistar rats were fed a balanced diet (4 % fat-C3, C6, C9) or a HFD (20 % fat- HF3, HF6, HF9) for 3, 6 or 9 weeks. Fat deposit weights, blood glucose and levels of serum testosterone and estrogen were measured. Prostate was evaluated for histology, proliferative and apoptotic cell index, and for the expression of androgen (AR), estrogen receptors type α (ERα) and aromatase. HFD did not affect estrogen levels and elevated serum testosterone only in HF9. HFD reduced prostate weight in HF6 and increased it in adulthood (HF9) but relative prostate weight was unchanged among groups. Cell proliferation, height and density were higher in epithelium of all HFD-groups, compared to controls, featuring the epithelial hyperplasia. Epithelial apoptosis was lower in HF9. HF3 and HF9 exhibited higher expressions of ERα, indicating that HFD triggers a new activation of ERα expression in the acinar epithelium. The content of prostatic aromatase was also elevated in HF9. Increased numbers of AR-positive cells were observed in all HFD groups, and western blotting analysis showed an increase in the truncated form of 45 kDa (AR45) and a reduction in the expression of 110 kDa-AR for HF3 and HF9. In conclusion, excessive dietary fats during sexual maturation of rats led to developmental programming of the prostate, inducing a hyperplastic status with perturbations in AR isoforms expression and reactivation of ERα in adulthood, whose implications for posterior prostatic health could be detrimental.

Glycyrrhiza glabra-Enhanced Extract and Adriamycin Antiproliferative Effect on PC-3 Prostate Cancer Cells

Prostate cancer is the second most commonly diagnosed cancer in men worldwide, which is almost incurable, once it progresses into the metastatic stage. Adriamycin (ADR) is a known chemotherapeutic agent that causes severe side effects. In recent years, studies in natural plant products have revealed their anticancer activities. In particular, Glycyrrhiza glabra enhanced extract (GGE), commonly known as licorice, has been reported to exert antiproliferative properties against cancer cells. In this study, the cytotoxic potential of GGE was assessed in PC-3 cells, when it is administrated alone or in combination with Adriamycin. PC-3 cells were treated with GGE and/or ADR, and the inhibition of cell proliferation was evaluated by the MTT assay. Cell cycle alterations and apoptosis rate were measured through flow cytometry. Expression levels of autophagy-related genes were evaluated with specific ELISA kits, Western blotting, and real-time PCR, while NMR spectrometry was used to identify the implication of specific metabolites. Our results demonstrated that GGE alone or in co-treatment with ADR shows antiproliferative properties against PC-3 cells, which are mediated by both apoptosis and autophagy mechanisms.

The impact of interleukin-10 (IL-10) gene 4 polymorphisms on peripheral blood IL-10 variation and prostate cancer risk based on published studies

This study purported to investigate the impact of interleukin-10 (IL-10) gene 4 polymorphisms (−1082G>A, -819T>C, -592A>C and 210T>C) on peripheral blood IL-10 variation and prostate cancer (PCa) risk, with a special consideration given to various origins of between-study heterogeneity. 2 researchers independently fulfilled literature retrieval, quality assessment and information collection. Sub-grouped analyses per ethnicity, continent, design type, control source, genotyping procedure, genotype validation, age-matched status, study sample size, quality score and controls’ mean age were conducted, respectively. Total 17 unduplicated studies (patients/controls: 7561/8101) were assessable for PCa risk, and 4 unduplicated studies (1189 subjects) for peripheral blood IL-10 variation. Pooling all assessable studies identified a marginally significant association between the -1082A allele and increased PCa risk (odds ratio (OR)=1.10, 95% confidence interval [CI]: 1.00 to 1.21) (Heterogeneity I²=64.3%), and no significance was detected in sub-grouped analyses of this polymorphism. Contrastingly, the -592C allele was significantly associated with reduced PCa risk in both prospective (OR=0.85, 95% CI: 0.77 to 0.95) and population-based (OR=0.92, 95% CI: 0.84 to 1.00) studies (Heterogeneity I²=0.0% and 18.1%). Moreover, carriers of combined -592CA/CC genotypes had a significant higher level of peripheral blood IL-10 than the -592AA genotype carriers (weighted mean difference=0.45 and 0.54 mg/dL, 95% CI: 0.23 to 0.67 and 0.30 to 0.39). The above comparisons possessed a low probability of publication bias. In sum, our findings suggested that IL-10 gene -592A>C polymorphism may represent a promising candidate locus for the occurrence of PCa, and further signified a contributing role of this polymorphism in prostate carcinogenesis.

Vitamin K and its analogs: Potential avenues for prostate cancer management

Epidemiological studies have demonstrated a relationship between cancer incidence and dietary habits. Especially intake of certain essential nutrients like vitamins has been shown to be beneficial in experimental studies and some clinical trials. Vitamin K (VK) is an essential nutrient involved in the blood clotting cascade, and there are considerable experimental data demonstrating its potential anticancer activity in several cancer types including prostate cancer. Previous in vitro and in vivo studies have focused mainly on anti-oxidative effects as the underlying anticancer mechanism of VK. However, recent studies reveal that VK inhibits the growth of cancer cells through other mechanisms, including apoptosis, cell cycle arrest, autophagy, and modulation of various transcription factors such as Myc and Fos. In the present review, we focus on the anticancer effect of dietary VK and its analogs on prostate cancer, with an emphasis on the signaling pathways that are activated following exposure to these compounds. This review also highlights the potential of VK and its derivatives as an adjuvant treatment in combination with other vitamins or with chemotherapeutic drugs. Based on our recent results and a review of the existing literature, we present evidence that VK and its derivatives can potentially be explored as cancer therapy, especially for prostate cancer.

CD24 is a genetic modifier for risk and progression of prostate cancer

CD24 plays an oncogenic role in the onset and progression of various human cancers, including prostate cancer. In the present study, we identified two linkage disequilibrium blocks with four recombination hotspot motifs in human CD24 locus. To elucidate whether genetic variants of CD24 are associated with susceptibility to prostate cancer and its disease status, we conducted a case-control association study with two P170 C/T and P-534 A/C polymorphisms of CD24 in 590 patients with prostate cancer and 590 healthy controls. A significant increased risk of prostate cancer was found in men with the P170^T/T genotype over the P170^C/C genotype (odd ratio = 1.74, 95% confidence interval = 1.16-2.63, P = 0.008), and in men with the P-534^C/C genotype over the P-534^A/A genotype (odd ratio = 1.47, 95% CI = 1.18-2.26, P = 0.003). Cochran-Armitage trend analysis showed that the P170^T allele was significantly correlated with an increased risk of prostate cancer progression (P = 0.029, trend between genotypes and stages) and this observation was also validated in an independent sample cohort. Next, we found that tumors with P170^T or P-534^C alleles had more twofold increased protein expressions of CD24 as compared to those with P170^C or P-534^A alleles, respectively. Likewise, tumors with a combination of P170^T/T and P-534^C/C genotypes were associated with a high mRNA level of CD24. Our data suggest a significant association of CD24 genetic variants with prostate cancer onset and progression, which provides new insight into molecular genetics of prostate cancer; however, these findings need to be validated in multiple independent cohorts. © 2016 Wiley Periodicals, Inc.

DNA alterations in the tumor genome and their associations with clinical outcome in prostate cancer

Although most prostate cancer (PCa) cases are not life-threatening, approximately 293 000 men worldwide die annually due to PCa. These lethal cases are thought to be caused by coordinated genomic alterations that accumulate over time. Recent genome-wide analyses of DNA from subjects with PCa have revealed most, if not all, genetic changes in both germline and PCa tumor genomes. In this article, I first review the major, somatically acquired genomic characteristics of various subtypes of PCa. I then recap key findings on the relationships between genomic alterations and clinical parameters, such as biochemical recurrence or clinical relapse, metastasis and cancer-specific mortality. Finally, I outline the need for, and challenges with, validation of recent findings in prospective studies for clinical utility. It is clearer now than ever before that the landscape of somatically acquired aberrations in PCa is highlighted by DNA copy number alterations (CNAs) and TMPRSS2-ERG fusion derived from complex rearrangements, numerous single nucleotide variations or mutations, tremendous heterogeneity, and continuously punctuated evolution. Genome-wide CNAs, PTEN loss, MYC gain in primary tumors, and TP53 loss/mutation and AR amplification/mutation in advanced metastatic PCa have consistently been associated with worse cancer prognosis. With this recently gained knowledge, it is now an opportune time to develop DNA-based tests that provide more accurate patient stratification for prediction of clinical outcome, which will ultimately lead to more personalized cancer care than is possible at present.

The Cumulative Effect of Gene-Gene and Gene-Environment Interactions on the Risk of Prostate Cancer in Chinese Men

Prostate cancer (PCa) is a multifactorial disease involving complex genetic and environmental factors interactions. Gene-gene and gene-environment interactions associated with PCa in Chinese men are less studied. We explored the association between 36 SNPs and PCa in 574 subjects from northern China. Body mass index (BMI), smoking, and alcohol consumption were determined through self-administered questionnaires in 134 PCa patients. Then gene-gene and gene-environment interactions among the PCa-associated SNPs were analyzed using the generalized multifactor dimensionality reduction (GMDR) and logistic regression methods. Allelic and genotypic association analyses showed that six variants were associated with PCa and the cumulative effect suggested men who carried any combination of 1, 2, or ≥3 risk genotypes had a gradually increased PCa risk (odds ratios (ORs) = 1.79–4.41). GMDR analysis identified the best gene-gene interaction model with scores of 10 for both the cross-validation consistency and sign tests. For gene-environment interactions, rs6983561 CC and rs16901966 GG in individuals with a BMI ≥ 28 had ORs of 7.66 (p = 0.032) and 5.33 (p = 0.046), respectively. rs7679673 CC + CA and rs12653946 TT in individuals that smoked had ORs of 2.77 (p = 0.007) and 3.11 (p = 0.024), respectively. rs7679673 CC in individuals that consumed alcohol had an OR of 4.37 (p = 0.041). These results suggest that polymorphisms, either individually or by interacting with other genes or environmental factors, contribute to an increased risk of PCa.

Associations of body mass index, smoking, and alcohol consumption with prostate cancer mortality in the Asia Cohort Consortium

Many potentially modifiable risk factors for prostate cancer are also associated with prostate cancer screening, which may induce a bias in epidemiologic studies. We investigated the associations of body mass index (weight (kg)/height (m)(2)), smoking, and alcohol consumption with risk of fatal prostate cancer in Asian countries where prostate cancer screening is not widely utilized. Analysis included 18 prospective cohort studies conducted during 1963-2006 across 6 countries in southern and eastern Asia that are part of the Asia Cohort Consortium. Body mass index, smoking, and alcohol intake were determined by questionnaire at baseline, and cause of death was ascertained through death certificates. Analysis included 522,736 men aged 54 years, on average, at baseline. During 4.8 million person-years of follow-up, there were 634 prostate cancer deaths (367 prostate cancer deaths across the 11 cohorts with alcohol data). In Cox proportional hazards analyses of all cohorts in the Asia Cohort Consortium, prostate cancer mortality was not significantly associated with obesity (body mass index >25: hazard ratio (HR) = 1.08, 95% confidence interval (CI): 0.85, 1.36), ever smoking (HR = 1.00, 95% CI: 0.84, 1.21), or heavy alcohol intake (HR = 1.00, 95% CI: 0.74, 1.35). Differences in prostate cancer screening and detection probably contribute to differences in the association of obesity, smoking, or alcohol intake with prostate cancer risk and mortality between Asian and Western populations and thus require further investigation.

Growth factors mediated cell signalling in prostate cancer progression: Implications in discovery of anti-prostate cancer agents

Cancer is one of the leading causes of mortality amongst world's population, in which prostate cancer is one of the most encountered malignancies among men. Globally, it is the sixth leading cause of cancer-related death in men. Prostate cancer is more prevalent in the developed world and is increasing at alarming rates in the developing countries. Prostate cancer is mostly a very sluggish progressing disease, caused by the overproduction of steroidal hormones like dihydrotestosterone or due to over-expression of enzymes such as 5-α-reductase. Various studies have revealed that growth factors play a crucial role in the progression of prostate cancer as they act either by directly elevating the level of steroidal hormones or upregulating enzyme efficacy by the active feedback mechanism. Presently, treatment options for prostate cancer include radiotherapy, surgery and chemotherapy. If treatment is done with prevailing traditional chemotherapy; it leads to resistance and development of androgen-independent prostate cancer that further complicates the situation with no cure option left. The current review article is an attempt to cover and establish an understanding of some major signalling pathways intervened through survival factors (IGF-1R), growth factors (TGF-α, EGF), Wnt, Hedgehog, interleukin, cytokinins and death factor receptor which are frequently dysregulated in prostate cancer. This will enable the researchers to design and develop better therapeutic strategies targeting growth factors and their cross talks mediated prostate cancer cell signalling.

A study of molecular signals deregulating mismatch repair genes in prostate cancer compared to benign prostatic hyperplasia

Prostate cancer is one of the leading causes of mortality among aging males. There is an unmet requirement of clinically useful biomarkers for early detection of prostate cancer to reduce the liabilities of overtreatment and accompanying morbidity. The present population-based study investigates the factors disrupting expression of multiple functionally related genes of DNA mismatch repair pathway in prostate cancer patients to identify molecular attributes distinguishing adenocarcinoma from benign hyperplasia of prostate. Gene expression was compared between tissue samples from prostate cancer and benign prostatic hyperplasia using real-time-PCR, western blot and immunohistochemistry. Assessment of genotypes of seven single-nucleotide-polymorphisms of three MMR genes was conducted using PCR-coupled RFLP and sequencing. Promoter methylation was interrogated by methylation-specific-PCR and bisulfite-sequencing. Interaction between microRNAs and MMR genes was verified by 3'UTR-based dual luciferase assays. Concurrent reduction of three MMR genes namely hMLH1, hMSH6 and hMSH2 (34-85%, P<0.05) was observed in prostate cancer tissues. hMSH6 polymorphism rs1800932(Pro92Pro) conferred a borderline protection in cancer patients (OR = 0.33, 95% CI = 0.15-0.75). Relative transcript level of hMLH1 was inversely related (r = -0.59, P<0.05) with methylation quotient of its promoter which showed a significantly higher methylation density (P = 0.008, Z = -2.649) in cancer patients. hsa-miR-155, hsa-miR-141 and hsa-miR-21 gene expressions were significantly elevated (66-85%, P<0.05) in tumor specimens and negatively correlated (r = -0.602 to -0.527, P<0.05) with that of MMR genes. hsa-miR-155 & hsa-miR-141 and hsa-miR-155 & hsa-miR-21 were demonstrated to bind to their putative seed sequences in hMLH1 and hMSH6 3'UTRs respectively. Relatively higher expression of DNA methyl-transferases (DNMT1 and DNMT3b) and HIF-1α genes (34-50%, P<0.05) were also detected in tumor tissues. This study provides statistical evidence that MMR deficiency is correlated with hypermethylation of hMLH1 promoter and upregulation of hsa-miR-155, hsa-miR-141 and hsa-miR-21 in prostate cancer. This comparative study reflects that microRNA expression level, particularly hsa-miR-155, exhibits predictive signature of prostate adenocarcinoma.

Synonymous Polymorphisms in HOXB13 as a Protective Factor for Prostate Cancer

BACKGROUND

Genomic association and linkage studies, as well as epidemiological data have implicated both the HOXB13 gene and single nucleotide polymorphisms (SNPs) in the development of prostate cancer (PCa). The recent association between the G84E polymorphism in the HOXB13 gene and PCa has been shown to result in a more aggressive cancer with an earlier onset of the disease. We examined the frequency of this mutation and other recurrent HOXB13 SNPs in patients with PCa and those with benign prostatic hyperplasia (BPH) or no cancer.

METHODS

Reverse transcriptase-polymerase chain reaction (RT-PCR) was performed on exons 1 and 2 of HOXB13 gene, followed by bidirectional Sanger Sequencing on peripheral blood from 232 PCa (age 46-92) and 110 BPH (age 45-84) patients. Statistical analysis was used to correlate between recurrent SNPs and PCa.

RESULTS

The G84E mutation was found at a low frequency in randomly selected PCa and BPH (both 0.9%). Two recurrent, synonymous SNPs, rs8556 and rs900627, were also detected. rs8556 was detected in 48 PCa (20.7%) and 26 BPH (23.6%) subjects; rs9900627was detected in 27 PCa (11.6%) and 19 BPH (17.3%) subjects. Having both rs8556 and rs9900627 or being homozygous for either one was associated with being 2.9 times less likely to develop PCa (p=0.05).

CONCLUSIONS

Although a larger study in order to confirm our findings, our data suggests a significant negative correlation between two SNPs, rs8556 and rs9900627, and the presence of PCa.

Mast cells as a potential prognostic marker in prostate cancer

Despite years of intensive investigation that has been made in understanding prostate cancer, it remains one of the major men's health issues and the leading cause of death worldwide. It is now ascertained that prostate cancer emerges from multiple spontaneous and/or inherited alterations that induce changes in expression patterns of genes and proteins that function in complex networks controlling critical cellular events. It is now accepted that several innate and adaptive immune cells, including T- and B-lymphocytes, macrophages, natural killer cells, dendritic cells, neutrophils, eosinophils, and mast cells (MCs), infiltrate the prostate cancer. All of these cells are irregularly scattered within the tumor and loaded with an assorted array of cytokines, chemokines, and inflammatory and cytotoxic mediators. This complex framework reflects the diversity in tumor biology and tumor-host interactions. MCs are well-established effector cells in Immunoglobulin-E (Ig-E) associated immune responses and potent effector cells of the innate immune system; however, their clinical significance in prostate cancer is still debated. Here, these controversies are summarized, focusing on the implications of these findings in understanding the roles of MCs in primary prostate cancer.