Prevalence of the HOXB13 G84E mutation in Danish men undergoing radical prostatectomy and its correlations with prostate cancer risk and aggressiveness

A Systematic Review of Family History, Race/Ethnicity, and Genetic Risk on Prostate Cancer Detection and Outcomes: Considerations in PSA-based Screening

AIM

To investigate the role of family history, race/ethnicity, and genetics in prostate cancer (PCa) screening.

METHODS

We conducted a systematic review of articles from January 2013 through September 2023 that focused on the association of race/ethnicity and genetic factors on PCa detection. Of 10,815 studies, we identified 43 that fulfilled our pre-determined PICO (Patient, Intervention, Comparison and Outcome) criteria.

RESULTS

Men with ≥1 first-degree relative(s) with PCa are at increased risk of PCa, even with negative imaging and/or benign prostate biopsy. Black men have higher PCa risk, while Asian men have lower risk. Most of the differences in risks are attributable to environmental and socioeconomic factors; however, genetic differences may play a role. Among numerous pathogenic variants that increase PCa risk, BRCA2, MSH2, and HOXB13 mutations confer the highest risk of PCa. Polygenic risk score (PRS) models identify men at higher PCa risk for a given age and PSA; these models improve when considering other clinical factors and when the model population matches the study population's ancestry.

CONCLUSIONS

Family history of PCa, race/ethnicity, pathogenic variants (particularly BRCA2, MSH2, and HOXB13), and PRS are associated with increased PCa risk and should be considered in shared decision-making to determine PCa screening regimens.

Germline Variants in DNA Damage Repair Genes and HOXB13 Among Black Patients With Early-Onset Prostate Cancer

PURPOSE

Genetic studies of prostate cancer susceptibility have predominantly focused on non-Hispanic White men, despite the observation that Black men are more likely to develop prostate cancer and die from the disease. Therefore, we sought to identify genetic variants in Black patients diagnosed with early-onset prostate cancer.

METHODS

Whole-exome sequencing of germline DNA from a population-based cohort of Black men diagnosed with prostate cancer at age 62 years or younger was performed. Analysis was focused on a panel of DNA damage repair (DDR) genes and HOXB13. All discovered variants were ranked according to their pathogenic potential based upon REVEL score, evidence from existing literature, and prevalence in the cohort. Logistic regression was used to investigate associations between mutation status and relevant clinical characteristics.

RESULTS

Among 743 Black prostate cancer patients, we identified 26 unique pathogenic (P) or likely pathogenic (LP) variants in 14 genes (including HOXB13, BRCA1/2, BRIP1, ATM, CHEK2, and PALB2) among 30 men, or approximately 4.0% of the patient population. We also identified 33 unique variants of unknown significance in 16 genes among 39 men. Because of the rarity of these variants in the population, most associations between clinical characteristics did not achieve statistical significance. However, our results suggest that carriers for P or LP (P/LP) variants were more likely to have a first-degree relative diagnosed with DDR gene-associated cancer, have a higher prostate-specific antigen at time of diagnosis, and be diagnosed with metastatic disease.

CONCLUSION

Variants in DDR genes and HOXB13 may be important cancer risk factors for Black men diagnosed with early-onset prostate cancer, and are more frequently observed in men with a family history of cancer.

The role of prophylactic prostatectomy as a primary prevention strategy in high-risk germline mutation carriers

PURPOSE OF REVIEW

Men with high-risk germline mutations are at significantly higher risk of developing and dying from prostate cancer. Current screening and treatment paradigms may lead to missed opportunities for cure. Herein we review the current literature on prevention, screening and treatment of these carriers and explore the potential role of prophylactic prostatectomy in primary prevention of prostate cancer mortality.

RECENT FINDINGS

Prostate-specific antigen (PSA)-based screening has demonstrated marginal benefits in prostate cancer (PCa) survival and uncertainty remains on its true benefit among high-risk carriers. Recent results indicate that PCa in BRCA 2 carriers occurs at a higher incidence, younger age and progresses more rapidly compared with noncarriers. An intensified screening protocol of MRI and PSA in young carriers demonstrated how using PSA values alone may be insufficient. Current evidence indicates that high-risk carriers have worse survival outcomes after undergoing radical treatment for screening detected disease when compared with noncarriers.

SUMMARY

Prophylactic prostatectomy within the context of a clinical trial is a reasonable primary prevention option for discussion with high-risk carriers, especially BRCA2 carriers during the shared decision-making process. Limitations exist in the current strategies of early PSA screening followed by radical treatment in this group.

Clinical Significance of Gene Mutations and Polymorphic Variants and their Association with Prostate Cancer Risk in Polish Men

Objectives: We tested the association of germline variants in BRCA1, BRCA2, CHEK2, CDKN2A, CYP1B1, HOXB13, MLH1, NBS1, NOD2 andPALB2 genes, as well as in 8q24 region, with prostate cancer (PC) risk and estimated their impact on disease clinical course, including overall survival time in Polish men with localized PC qualified for radical treatment.Materials and Methods: DNA of 110 patients with localized prostate cancer treated with radical prostatectomy (RP), from each age group and with different stages of the disease. DNA samples of the control group consisted of 111 men, volunteers, without PC (age-matched to study group). Sanger sequencing, AS-PCR, RFLP-PCR, and multiplex-PCR were used for  variants detection.Results: The percentage of men with ≥1 germline variant was higher in PC group (52.7%) than in healthy men (37.8%) (P = .03). The presence of ≥2 variants was associated with shorter survival than the presence of one or no variant in the PC group (P = .14, trend). The HOXB13 G84E was detected in 2.9% of PC men and in no healthy men (P = .19, trend, OR = 7.21). A CHEK2 truncating mutation (1100delC or IVS2+1G>A) was detected in 2/110 (1.8%) PC patients and in no healthy men (P = .29, OR=5.14). The NBS1 I171V was detected in 2/110 (1.8%) PC patients and in no men from the control group (OR=5.14, P = .29, NS).Conclusions: We conclude that the presence of more than 2 germline variants was probably associated with shorter survival of patients with localized prostate cancer qualified for radical treatment. The HOXB13 (G84E), CHEK2 (1100delC or IVS2+1G>A) truncating variants and NBS1 (I171V) are associated with PC and hereditary form of the disease. The HOXB13 (G84E) and NOD2 (3020insC) single variants are associated with shorter and CYP1B1 (48CC, 119GG) single genotypes with longer overall survival.

Genetics of prostate cancer and its utility in treatment and screening

Prostate cancer heritability is attributed to a combination of rare, moderate to highly penetrant genetic variants as well as commonly occurring variants conferring modest risks [single nucleotide polymorphisms (SNPs)]. Some of the former type of variants (e.g., BRCA2 mutations) predispose particularly to aggressive prostate cancer and confer poorer prognoses compared to men who do not carry mutations. Molecularly targeted treatments such as PARP inhibitors have improved outcomes in men carrying somatic and/or germline DNA repair gene mutations. Ongoing clinical trials are exploring other molecular targeted approaches based on prostate cancer somatic alterations. Genome wide association studies have identified >250 loci that associate with prostate cancer risk. Multi-ancestry analyses have identified shared as well as population specific risk SNPs. Prostate cancer risk SNPs can be used to estimate a polygenic risk score (PRS) to determine an individual's genetic risk of prostate cancer. The odds ratio of prostate cancer development in men whose PRS lies in the top 1% of the risk profile ranges from 9 to 11. Ongoing studies are investigating the utility of a prostate cancer PRS to target population screening to those at highest risk. With the advent of personalized medicine and development of DNA sequencing technologies, access to clinical genetic testing is increasing, and oncology guidelines from bodies such as NCCN and ESMO have been updated to provide criteria for germline testing of "at risk" healthy men as well as those with prostate cancer. Both germline and somatic prostate cancer research have significantly evolved in the past decade and will lead to further development of precision medicine approaches to prostate cancer treatment as well as potentially developing precision population screening models.

Prostate Cancer Biomarkers: From diagnosis to prognosis and precision-guided therapeutics

Prostate cancer (PCa) is one of the most commonly diagnosed malignancies and among the leading causes of cancer-related death worldwide. It is a highly heterogeneous disease, ranging from remarkably slow progression or inertia to highly aggressive and fatal disease. As therapeutic decision-making, clinical trial design and outcome highly depend on the appropriate stratification of patients to risk groups, it is imperative to differentiate between benign versus more aggressive states. The incorporation of clinically valuable prognostic and predictive biomarkers is also potentially amenable in this process, in the timely prevention of metastatic disease and in the decision for therapy selection. This review summarizes the progress that has so far been made in the identification of the genomic events that can be used for the classification, prediction and prognostication of PCa, and as major targets for clinical intervention. We include an extensive list of emerging biomarkers for which there is enough preclinical evidence to suggest that they may constitute crucial targets for achieving significant advances in the management of the disease. Finally, we highlight the main challenges that are associated with the identification of clinically significant PCa biomarkers and recommend possible ways to overcome such limitations.

Prostate cancer risk variants of the HOXB genetic locus

The G84E germline mutation of HOXB13 predisposes to prostate cancer and is clinically tested for familial cancer care. We investigated the HOXB locus to define a potentially broader contribution to prostate cancer heritability. We sought HOXB locus germline variants altering prostate cancer risk in three European-ancestry case-control study populations (combined 7812 cases and 5047 controls): the International Consortium for Prostate Cancer Genetics Study; the Nashville Familial Prostate Cancer Study; and the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Multiple rare genetic variants had concordant and strong risk effects in these study populations and exceeded genome-wide significance. Independent risk signals were best detected by sentinel variants rs559612720 within SKAP1 (OR = 8.1, P = 2E-9) and rs138213197 (G84E) within HOXB13 (OR = 5.6, P = 2E-11), separated by 567 kb. Half of carriers inherited both risk alleles, while others inherited either alone. Under mutual adjustment, the variants separately carried 3.6- and 3.1-fold risk, respectively, while joint inheritance carried 11.3-fold risk. These risks were further accentuated among men meeting criteria for hereditary prostate cancer, and further still for those with early-onset or aggressive disease. Among hereditary prostate cancer cases diagnosed under age 60 and with aggressive disease, joint inheritance carried a risk of OR = 27.7 relative to controls, P = 2E-8. The HOXB sentinel variant pair more fully captured genetic risk for prostate cancer within the study populations than either variant alone.

Risk stratification in men with a negative prostate biopsy: an interim analysis of a prospective cohort study

OBJECTIVE

To investigate whether a risk score for prostate cancer (PCa) lifetime risk can be used to optimise triaging of patients with a negative prostate biopsy, but under sustained suspicion of PCa.

PATIENTS AND METHODS

In this prospective clinical study, we included, and risk scored patients who had a PCa-negative transrectal ultrasonography (TRUS)-guided prostate biopsy, but elevated prostate-specific antigen (PSA), a suspicious prostate digital rectal examination and/or a positive family history (FH) of PCa. The risk score estimated individual lifetime risk of PCa, based on a polygenic risk score (33 single nucleotide polymorphisms), age, and FH of PCa. Patients were followed, under urological supervision, for up to 4 years with annual controls, always including PSA measurements. Multiparametric magnetic resonance imaging (mpMRI) and/or prostate biopsy was performed at selected annual controls depending on risk score and at the urologist's/patient's discretion, which means that the follow-up differed based on the risk score.

RESULTS

We included 429 patients. After risk scoring, 376/429 (88%) patients were allocated to a normal-risk group (<30% PCa lifetime risk) and 53/429 (12%) to a high-risk group (≥30% PCa lifetime risk). The high-risk group had significantly different follow-up, with more biopsy and mpMRI sessions compared to the normal-risk group. PCa was detected in 89/429 (21%) patients, with 67/376 (18%) patients diagnosed in the normal-risk group and 22/53 (42%) in the high-risk group. There was no statistically significant difference in the cumulative incidence of PCa between the normal-risk group and the high-risk group after 4 years of follow-up. Currently, 67/429 (16%) patients are still being followed in this ongoing study.

CONCLUSION

In a 4-year perspective, our PCa lifetime risk score did not demonstrate significant prognostic value for triaging patients, with a negative TRUS-guided biopsy and sustained suspicion of PCa.

Hereditary Prostate Cancer: Genes Related, Target Therapy and Prevention

Prostate cancer (PCa) is globally the second most diagnosed cancer type and the most common cause of cancer-related deaths in men. Family history of PCa, hereditary breast and ovarian cancer (HBOC) and Lynch syndromes (LS), are among the most important risk factors compared to age, race, ethnicity and environmental factors for PCa development. Hereditary prostate cancer (HPCa) has the highest heritability of any major cancer in men. The proportion of PCa attributable to hereditary factors has been estimated in the range of 5–15%. To date, the genes more consistently associated to HPCa susceptibility include mismatch repair (MMR) genes (MLH1, MSH2, MSH6, and PMS2) and homologous recombination genes (BRCA1/2, ATM, PALB2, CHEK2). Additional genes are also recommended to be integrated into specific research, including HOXB13, BRP1 and NSB1. Importantly, BRCA1/BRCA2 and ATM mutated patients potentially benefit from Poly (ADP-ribose) polymerase PARP inhibitors, through a mechanism of synthetic lethality, causing selective tumor cell cytotoxicity in cell lines. Moreover, the detection of germline alterations in MMR genes has therapeutic implications, as it may help to predict immunotherapy benefits. Here, we discuss the current knowledge of the genetic basis for inherited predisposition to PCa, the potential target therapy, and the role of active surveillance as a management strategy for patients with low-risk PCa. Finally, the current PCa guideline recommendations are reviewed.

Context-dependent HOX transcription factor function in health and disease

During animal development, HOX transcription factors determine the fate of developing tissues to generate diverse organs and appendages. The power of these proteins is striking: mis-expressing a HOX protein causes homeotic transformation of one body part into another. During development, HOX proteins interpret their cellular context through protein interactions, alternative splicing, and post-translational modifications to regulate cell proliferation, cell death, cell migration, cell differentiation, and angiogenesis. Although mutation and/or mis-expression of HOX proteins during development can be lethal, changes in HOX proteins that do not pattern vital organs can result in survivable malformations. In adults, mutation and/or mis-expression of HOX proteins disrupts their gene regulatory networks, deregulating cell behaviors and leading to arthritis and cancer. On the molecular level, HOX proteins are composed of DNA binding homeodomain, and large regions of unstructured, or intrinsically disordered, protein sequence. The primary roles of HOX proteins in arthritis and cancer suggest that mutations associated with these diseases in both the structured and disordered regions of HOX proteins can have substantial functional effects. These insights lead to new questions critical for understanding and manipulating HOX function in physiological and pathological conditions.

Shaping Chromatin States in Prostate Cancer by Pioneer Transcription Factors

The androgen receptor (AR) is a critical therapeutic target in prostate cancer that responds to antagonists in primary disease, but inevitably becomes reactivated, signaling onset of the lethal castration-resistant prostate cancer (CRPC) stage. Epigenomic investigation of the chromatin environment and interacting partners required for AR transcriptional activity has uncovered three pioneer factors that open up chromatin and facilitate AR-driven transcriptional programs. FOXA1, HOXB13, and GATA2 are required for normal AR transcription in prostate epithelial development and for oncogenic AR transcription during prostate carcinogenesis. AR signaling is dependent upon these three pioneer factors both before and after the clinical transition from treatable androgen-dependent disease to untreatable CRPC. Agents targeting their respective DNA binding or downstream chromatin-remodeling events have shown promise in preclinical studies of CRPC. AR-independent functions of FOXA1, HOXB13, and GATA2 are emerging as well. While all three pioneer factors exert effects that promote carcinogenesis, some of their functions may inhibit certain stages of prostate cancer progression. In all, these pioneer factors represent some of the most promising potential therapeutic targets to emerge thus far from the study of the prostate cancer epigenome.

Somatic HOXB13 Expression Correlates with Metastatic Progression in Men with Localized Prostate Cancer Following Radical Prostatectomy

BACKGROUND

Homeobox B13 (HOXB13) expression regulates normal prostate development and mutations are associated with prostate cancer (PCa) formation.

OBJECTIVE

To assess the role of HOXB13 mRNA expression in PCa progression following radical prostatectomy.

DESIGN, SETTING, AND PARTICIPANTS

Genome-wide expression profiles were queried from two retrospective prostatectomy cohorts with follow-up data (Mayo Clinic, n=780; Johns Hopkins Medical Institute [JHMI], n=355), and a prospective genomic registry (n=5239).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Multivariable Cox regressions were used to analyze metastasis-free survival (MFS).

RESULTS AND LIMITATIONS

HOXB13 expression in primary PCa increased with increasing tumor grade and with high metastatic potential based on a genomic signature. The highest quartile of HOXB13 expression was associated with worse MFS compared with the lowest quartile (Mayo Clinic: adjusted hazard ratio [AHR] 1.46, 95% confidence interval [CI] 1.03-2.06, and JHMI: AHR 1.80, 95% CI 1.02-3.19). The combinations of high HOXB13 expression and low expression of its binding partner, MEIS1 (AHR 2.03, 95% CI 1.54-2.66) or MEIS2 (AHR 1.73, 95% CI 1.33-2.26), portended worse MFS. Additionally, high HOXB13 expression in combination with low MEIS1/2 expression correlated with high expression of androgen receptor-mediated genes. The retrospective nature of this study subjects the findings to a bias due to unmeasured variables.

CONCLUSIONS

Primary PCa tumors with increased HOXB13 expression have an increased propensity for metastases following prostatectomy, particularly in the setting of low MEIS1/2 expression. High androgen receptor output may account for worse outcomes for these tumors and suggests heightened sensitivity to androgen suppression.

PATIENT SUMMARY

Using genomic data from a large number of prostate cancer (PCa) tumors, we found that increased expression of homeobox B13 (HOXB13), a gene related to normal prostate development, was associated with worse outcomes following surgery for PCa. A biomarker signature suggests that these tumors would be more susceptible to androgen suppression, a common treatment for PCa. Take Home  Messagece:: In multiple large cohorts, prostate cancer tumors with high homeobox B13 (HOXB13) expression and low expression of its binding partner MEIS1/2 were enriched with high androgen receptor output and had an increased propensity for metastases following surgery.

HOX genes function in Breast Cancer development

Breast cancer develops in the mammary glands during mammalian adulthood and is considered the second most common type of human carcinoma and the most incident and mortal in the female population. In contrast to other human structures, the female mammary glands continue to develop after birth, undergoing various modifications during pregnancy, lactation and involution under the regulation of hormones and transcription factors, including those encoded by the HOX clusters (A, B, C, and D). Interestingly, HOX gene deregulation is often associated to breast cancer development. Within the HOXB cluster, 8 out of the 10 genes present altered expression levels in breast cancer with an impact in its aggressiveness and resistance to hormone therapy, which highlights the importance of HOXB genes as potential therapeutic targets used to overcome the limitations of tamoxifen-resistant cancer treatments. Here, we review the current state of knowledge on the role of HOX genes in breast cancer, specially focus on HOXB, discussing the causes and consequences of HOXB gene deregulation and their relevance as prognostic factors and therapeutic targets.

The Genomic and Molecular Pathology of Prostate Cancer: Clinical Implications for Diagnosis, Prognosis, and Therapy

Prostate cancer (PCa) is the most common noncutaneous malignancy affecting American men and the second most common cause of cancer death. The traditional risk classification schemes for PCa are limited due to the vast clinical and molecular heterogeneity of the disease. Fortunately, recent advancements in sequencing technologies have provided us with valuable insight into the genomics of PCa. To date, a wide array of recurrent genomic alterations in PCa have been identified. Incorporating these distinct molecular subtypes of PCa into prediction models provides opportunities for improved risk stratification and ultimately better patient outcomes. In this review, we summarize the key molecular subtypes of PCa and focus on those genomic alterations that have clinical implications for diagnosis, prognosis, and therapeutic response.

Hereditary prostate cancer - Primetime for genetic testing?

Prostate cancer (PCa) remains the most common cancer in men. The proportion of all PCa attributable to high-risk hereditary factors has been estimated to 5-15%. Recent landmark discoveries in PCa genetics led to the identification of germline mutations/alterations (eg. BRCA1, BRCA2, ATM or HOXB13), single nucleotide polymorphisms or copy number variations associated with PCa incidence and progression. However, offering germline testing to men with an assumed hereditary component is currently controversial. In the present review article, we provide an overview about the epidemiology and the genetic basis of PCa predisposition and critically discuss the significance and consequence in the clinical routine. In addition, we give an overview about genetic tests and report latest findings from ongoing clinical studies. Lastly, we discuss the impact of genetic testing in personalized therapy in advanced stages of the disease.

Epigenetic silencing of MEIS2 in prostate cancer recurrence

Background

Current diagnostic and prognostic tools for prostate cancer (PC) are suboptimal, resulting in overdiagnosis and overtreatment of clinically insignificant tumors. Thus, to improve the management of PC, novel biomarkers are urgently needed.

Results

In this study, we integrated genome-wide methylome (Illumina 450K DNA methylation array (450K)) and RNA sequencing (RNAseq) data performed in a discovery set of 27 PC and 15 adjacent normal (AN) prostate tissue samples to identify candidate driver genes involved in PC development and/or progression. We found significant enrichment for homeobox genes among the most aberrantly methylated and transcriptionally dysregulated genes in PC. Specifically, homeobox gene MEIS2 (Myeloid Ecotropic viral Insertion Site 2) was significantly hypermethylated (p < 0.0001, Mann-Whitney test) and transcriptionally downregulated (p < 0.0001, Mann-Whitney test) in PC compared to non-malignant prostate tissue in our discovery sample set, which was also confirmed in an independent validation set including > 500 PC and AN tissue samples in total (TCGA cohort analyzed by 450K and RNAseq). Furthermore, in three independent radical prostatectomy (RP) cohorts (n > 700 patients in total), low MEIS2 transcriptional expression was significantly associated with poor biochemical recurrence (BCR) free survival (p = 0.0084, 0.0001, and 0.0191, respectively; log-rank test). Next, we analyzed another RP cohort consisting of > 200 PC, AN, and benign prostatic hyperplasia (BPH) samples by quantitative methylation-specific PCR (qMSP) and found that MEIS2 was significantly hypermethylated (p < 0.0001, Mann-Whitney test) in PC compared to non-malignant prostate tissue samples (AN and BPH) with an AUC > 0.84. Moreover, in this cohort, aberrant MEIS2 hypermethylation was significantly associated with post-operative BCR (p = 0.0068, log-rank test), which was subsequently confirmed (p = 0.0067; log-rank test) in the independent TCGA validation cohort (497 RP patients; 450K data).

Conclusions

To the best of our knowledge, this is the first study to investigate, demonstrate, and independently validate a prognostic biomarker potential for MEIS2 at the transcriptional expression level and at the DNA methylation level in PC.

Homeobox B13 G84E Mutation and Prostate Cancer Risk

BACKGROUND

The homeobox B13 (HOXB13) G84E mutation has been recommended for use in genetic counselling for prostate cancer (PCa), but the magnitude of PCa risk conferred by this mutation is uncertain.

OBJECTIVE

To obtain precise risk estimates for mutation carriers and information on how these vary by family history and other factors.

DESIGN, SETTING, AND PARTICIPANTS

Two-fold: a systematic review and meta-analysis of published risk estimates, and a kin-cohort study comprising pedigree data on 11983 PCa patients enrolled during 1993-2014 from 189 UK hospitals and who had been genotyped for HOXB13 G84E.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Relative and absolute PCa risks. Complex segregation analysis with ascertainment adjustment to derive age-specific risks applicable to the population, and to investigate how these vary by family history and birth cohort.

RESULTS AND LIMITATIONS

A meta-analysis of case-control studies revealed significant heterogeneity between reported relative risks (RRs; range: 0.95-33.0, p<0.001) and differences by case selection (p=0.007). Based on case-control studies unselected for PCa family history, the pooled RR estimate was 3.43 (95% confidence interval [CI] 2.78-4.23). In the kin-cohort study, PCa risk for mutation carriers varied by family history (p<0.001). There was a suggestion that RRs decrease with age, but this was not significant (p=0.068). We found higher RR estimates for men from more recent birth cohorts (p=0.004): 3.09 (95% CI 2.03-4.71) for men born in 1929 or earlier and 5.96 (95% CI 4.01-8.88) for men born in 1930 or later. The absolute PCa risk by age 85 for a male HOXB13 G84E carrier varied from 60% for those with no PCa family history to 98% for those with two relatives diagnosed at young ages, compared with an average risk of 15% for noncarriers. Limitations include the reliance on self-reported cancer family history.

CONCLUSIONS

PCa risks for HOXB13 G84E mutation carriers are heterogeneous. Counselling should not be based on average risk estimates but on age-specific absolute risk estimates tailored to individual mutation carriers' family history and birth cohort.

PATIENT SUMMARY

Men who carry a hereditary mutation in the homeobox B13 (HOXB13) gene have a higher than average risk for developing prostate cancer. In our study, we examined a large number of families of men with prostate cancer recruited across UK hospitals, to assess what other factors may contribute to this risk and to assess whether we could create a precise model to help in predicting a man's prostate cancer risk. We found that the risk of developing prostate cancer in men who carry this genetic mutation is also affected by a family history of prostate cancer and their year of birth. This information can be used to assess more personalised prostate cancer risks to men who carry HOXB13 mutations and hence better counsel them on more personalised risk management options, such as tailoring prostate cancer screening frequency.

The Role of HOX Transcription Factors in Cancer Predisposition and Progression

Homeobox (HOX) transcription factors, encoded by a subset of homeodomain superfamily genes, play pivotal roles in many aspects of cellular physiology, embryonic development, and tissue homeostasis. Findings over the past decade have revealed that mutations in HOX genes can lead to increased cancer predisposition, and HOX genes might mediate the effect of many other cancer susceptibility factors by recognizing or executing altered genetic information. Remarkably, several lines of evidence highlight the interplays between HOX transcription factors and cancer risk loci discovered by genome-wide association studies, thereby gaining molecular and biological insight into cancer etiology. In addition, deregulated HOX gene expression impacts various aspects of cancer progression, including tumor angiogenesis, cell autophagy, proliferation, apoptosis, tumor cell migration, and metabolism. In this review, we will discuss the fundamental roles of HOX genes in cancer susceptibility and progression, highlighting multiple molecular mechanisms of HOX involved gene misregulation, as well as their potential implications in clinical practice.

MEIS1 and MEIS2 Expression and Prostate Cancer Progression: A Role For HOXB13 Binding Partners in Metastatic Disease

Purpose: Germline mutations within the MEIS-interaction domain of HOXB13 have implicated a critical function for MEIS-HOX interactions in prostate cancer etiology and progression. The functional and predictive role of changes in MEIS expression within prostate tumor progression, however, remain largely unexplored.Experimental Design: Here we utilize RNA expression datasets, annotated tissue microarrays, and cell-based functional assays to investigate the role of MEIS1 and MEIS2 in prostate cancer and metastatic progression.Results: These analyses demonstrate a stepwise decrease in the expression of both MEIS1 and MEIS2 from benign epithelia, to primary tumor, to metastatic tissues. Positive expression of MEIS proteins in primary tumors, however, is associated with a lower hazard of clinical metastasis (HR = 0.28) after multivariable analysis. Pathway and gene set enrichment analyses identified MEIS-associated networks involved in cMYC signaling, cellular proliferation, motility, and local tumor environment. Depletion of MEIS1 and MEIS2 resulted in increased tumor growth over time in vivo, and decreased MEIS expression in both patient-derived tumors and MEIS-depleted cell lines was associated with increased expression of the protumorigenic genes cMYC and CD142, and decreased expression of AXIN2, FN1, ROCK1, SERPINE2, SNAI2, and TGFβ2.Conclusions: These data implicate a functional role for MEIS proteins in regulating cancer progression, and support a hypothesis whereby tumor expression of MEIS1 and MEIS2 expression confers a more indolent prostate cancer phenotype, with a decreased propensity for metastatic progression. Clin Cancer Res; 24(15); 3668-80. ©2018 AACR.

Genomes of early onset prostate cancer

PURPOSE OF REVIEW

Prostate cancer is a disease of the elderly but a clinically relevant subset occurs early in life. In the current review, we discuss recent findings and the current understanding of the molecular underpinnings associated with early-onset prostate cancer (PCa) and the evidence supporting age-specific differences in the cancer genomes.

RECENT FINDINGS

Recent surveys of PCa patient cohorts have provided novel age-dependent links between germline and somatic aberrations which points to differences in the molecular cause and treatment options.

SUMMARY

Identifying the earliest molecular alterations in PCa can provide insight into the cause of the disease and biomarkers for patient risk stratification. Genomic aberrations of early-onset PCas display several patterns distinct from late-onset PCa genomes, suggesting age-dependent pathomechanisms involving alterations in the androgen receptor pathway.

Impact of the G84E variant on HOXB13 gene and protein expression in formalin-fixed, paraffin-embedded prostate tumours

The HOXB13 G84E variant is associated with risk of prostate cancer (PCa), however the role this variant plays in PCa development is unknown. This study examined 751 cases, 450 relatives and 355 controls to determine the contribution of this variant to PCa risk in Tasmania and investigated HOXB13 gene and protein expression in tumours from nine G84E heterozygote variant and 13 wild-type carriers. Quantitative PCR and immunohistochemistry showed that HOXB13 gene and protein expression did not differ between tumour samples from variant and wild-type carriers. Allele-specific transcription revealed that two of seven G84E carriers transcribed both the variant and wild-type allele, while five carriers transcribed the wild-type allele. Methylation of surrounding CpG sites was lower in the variant compared to the wild-type allele, however overall methylation across the region was very low. Notably, tumour characteristics were less aggressive in the two variant carriers that transcribed the variant allele compared to the five that did not. This study has shown that HOXB13 expression does not differ between tumour tissue of G84E variant carriers and non-carriers. Intriguingly, the G84E variant allele was rarely transcribed in carriers, suggesting that HOXB13 expression may be driven by the wild-type allele in the majority of carriers.

Somatic molecular subtyping of prostate tumors from HOXB13 G84E carriers

A recurrent germline mutation (G84E) in the HOXB13 gene is associated with early onset and family history-positive prostate cancer in patients of European descent, occurring in up to 5% of prostate cancer families. To date, the molecular features of prostate tumors occurring in HOXB13 G84E carriers have not been studied in a large cohort of patients. We identified 101 heterozygous carriers of G84E who underwent radical prostatectomy for prostate cancer between 1985 and 2011 and matched these men by race, age and tumor grade to 99 HOXB13 wild-type controls. Immunostaining for HOXB13, PTEN, ERG, p53 and SPINK1 as well as RNA in situ hybridization for ETV1/4/5 were performed using genetically validated assays. Tumors from G84E carriers generally expressed HOXB13 protein at a level comparable to benign and wild-type glands. ETS gene expression (either ERG or ETV1/4/5) was seen in 36% (36/101) of tumors from G84E carriers compared to 68% (65/96) of the controls (p < 0.0001). PTEN was lost in 11% (11/101) of G84E carriers compared to 25% (25/99) of the controls (p = 0.014). PTEN loss was enriched among ERG-positive compared to ERG-negative tumors in both groups of patients. Nuclear accumulation of the p53 protein, indicative of underlying TP53 missense mutations, was uncommon in both groups, occurring in 1% (1/101) of the G84E carriers versus 2% (2/92) of the controls (p = NS). Taken together, these data suggest that genes other than ERG and PTEN may drive carcinogenesis/progression in the majority of men with germline HOXB13 mutations.

HOXB13 mutations and binding partners in prostate development and cancer: Function, clinical significance, and future directions

The recent and exciting discovery of germline HOXB13 mutations in familial prostate cancer has brought HOX signaling to the forefront of prostate cancer research. An enhanced understanding of HOX signaling, and the co-factors regulating HOX protein specificity and transcriptional regulation, has the high potential to elucidate novel approaches to prevent, diagnose, stage, and treat prostate cancer. Toward our understanding of HOX biology in prostate development and prostate cancer, basic research in developmental model systems as well as other tumor sites provides a mechanistic framework to inform future studies in prostate biology. Here we describe our current understanding of HOX signaling in genitourinary development and cancer, current clinical data of HOXB13 mutations in multiple cancers including prostate cancer, and the role of HOX protein co-factors in development and cancer. These data highlight numerous gaps in our understanding of HOX function in the prostate, and present numerous potentially impactful mechanistic and clinical opportunities for future investigation.

Association between germline homeobox B13 (HOXB13) G84E allele and prostate cancer susceptibility: a meta-analysis and trial sequential analysis

Germline HOXB13 G84E mutation (rs138213197) has been described associated with prostate cancer (PCa) susceptibility but results of different studies are inconsistent. We conducted this meta-analysis to evaluate the specific role of this mutation. Relevant available studies were identified by searching the databases Pubmed, Embase and Web of Science. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to measure the strength of the association. Subgroup analysis were performed to evaluate the specific role of rs138213197 in disease aggressiveness, diagnostic age and family history. Furthermore, trial sequential analysis (TSA) was conducted for the first time to estimate whether the evidence of the results is sufficient. Our results indicated that significant increased PCa susceptibility was associated with rs138213197 compared with non-carriers (OR = 3.38, 95% CI: 2.45-4.66). Besides, in subgroup analysis, HOXB13 G84E variant was obviously associated with early onset (OR = 2.90, 95% CI: 2.24-3.75), affected relatives (OR = 2.60, 95% CI 2.19-3.10) and highly aggressive disease (OR = 2.38, 95% CI 1.84-3.08). By TSA, the findings in the current study were based on sufficient evidence. Therefore, our results indicated that the G84E mutation in HOXB13 gene might increase susceptibility to PCa.