The influence of mistrust, racism, religious participation, and access to care on patient satisfaction for African American men: the North Carolina-Louisiana Prostate Cancer Project

OBJECTIVE

The purpose of this study was to explore whether a particular combination of individual characteristics influences patient satisfaction with the health care system among a sample of African American men in North Carolina with prostate cancer. Patient satisfaction may be relevant for improving African American men's use of regular care, thus improving the early detection of prostate cancer and attenuating racial disparities in prostate cancer outcomes.

METHODS

This descriptive correlation study examined relationships of individual characteristics that influence patient satisfaction using data from 505 African American men from North Carolina, who prospectively enrolled in the North Carolina-Louisiana Prostate Cancer Project from September 2004 to November 2007. Analyses consisted of univariate statistics, bivariate analysis, and multiple regression analysis.

RESULTS

The variables selected for the final model were: participation in religious activities, mistrust, racism, and perceived access to care. In this study, both cultural variables, mistrust (p=<.0001, F=95.58) and racism (p=<.002, F=5.59), were significantly negatively associated with patient satisfaction and accounted for the majority of the variability represented by individual characteristics.

CONCLUSION

Mistrust and racism are cultural factors that are extremely important and have been negatively associated with patient satisfaction and decreased desires to utilize health care services for African American men. To overcome barriers in seeking health care services, health care providers need to implement a patient-centered approach by creating a clinical environment that demonstrates cultural competence and eliminating policies, procedures, processes, or personnel that foster mistrust and racism.

Proto-oncogene activity of melanoma antigen-A11 (MAGE-A11) regulates retinoblastoma-related p107 and E2F1 proteins

Melanoma antigen-A11 (MAGE-A11) is a low-abundance, primate-specific steroid receptor coregulator in normal tissues of the human reproductive tract that is expressed at higher levels in prostate cancer. Increased expression of MAGE-A11 enhances androgen receptor transcriptional activity and promotes prostate cancer cell growth. Further investigation into the mechanisms of MAGE-A11 function in prostate cancer demonstrated interactions with the retinoblastoma-related protein p107 and Rb tumor suppressor but no interaction with p130 of the Rb family. MAGE-A11 interaction with p107 was associated with transcriptional repression in cells with low MAGE-A11 and transcriptional activation in cells with higher MAGE-A11. Selective interaction of MAGE-A11 with retinoblastoma family members suggested the regulation of E2F transcription factors. MAGE-A11 stabilized p107 by inhibition of ubiquitination and linked p107 to hypophosphorylated E2F1 in association with the stabilization and activation of E2F1. The androgen receptor and MAGE-A11 modulated endogenous expression of the E2F1-regulated cyclin-dependent kinase inhibitor p27(Kip1). The ability of MAGE-A11 to increase E2F1 transcriptional activity was similar to the activity of adenovirus early oncoprotein E1A and depended on MAGE-A11 interactions with p107 and p300. The immunoreactivity of p107 and MAGE-A11 was greater in advanced prostate cancer than in benign prostate, and knockdown with small inhibitory RNA showed that p107 is a transcriptional activator in prostate cancer cells. These results suggest that MAGE-A11 is a proto-oncogene whose increased expression in prostate cancer reverses retinoblastoma-related protein p107 from a transcriptional repressor to a transcriptional activator of the androgen receptor and E2F1.

DNA methylation and nucleosome occupancy regulate the cancer germline antigen gene MAGEA11

MAGEA11 is a cancer germline (CG) antigen and androgen receptor co-activator. Its expression in cancers other than prostate, and its mechanism of activation, has not been reported. In silico analyses reveal that MAGEA11 is frequently expressed in human cancers, is increased during tumor progression, and correlates with poor prognosis and survival. In prostate and epithelial ovarian cancers (EOC), MAGEA11 expression was associated with promoter and global DNA hypomethylation, and with activation of other CG genes. Pharmacological or genetic inhibition of DNA methyltransferases (DNMTs) and/or histone deacetylases (HDACs) activated MAGEA11 in a cell line specific manner. MAGEA11 promoter activity was directly repressed by DNA methylation, and partially depended on Sp1, as pharmacological or genetic targeting of Sp1 reduced MAGEA11 promoter activity and endogenous gene expression. Importantly, DNA methylation regulated nucleosome occupancy specifically at the -1 positioned nucleosome of MAGEA11. Methylation of a single Ets site near the transcriptional start site (TSS) correlated with -1 nucleosome occupancy and, by itself, strongly repressed MAGEA11 promoter activity. Thus, DNA methylation regulates nucleosome occupancy at MAGEA11, and this appears to function cooperatively with sequence-specific transcription factors to regulate gene expression. MAGEA11 regulation is highly instructive for understanding mechanisms regulating CG antigen genes in human cancer.

The association between calcium channel blocker use and prostate cancer outcome

BACKGROUND

Epidemiological studies indicate that calcium channel blocker (CCB) use is inversely related to prostate cancer (PCa) incidence. The association between CCB use and PCa aggressiveness at the time of radical prostatectomy (RP) and outcome after RP was examined.

METHODS

Medication use, PCa aggressiveness and post-RP outcome were retrieved from a prospectively populated database that contains clinical and outcome for RP patients at Roswell Park Cancer Institute (RPCI) from 1993 to 2010. The database was queried for anti-hypertensive medication use at diagnosis for patients with ≥1 year follow-up. Recurrence was defined using NCCN guidelines. Chi-Square tests assessed the relationship between CCB use and PCa aggressiveness. Cox regression models compared the distribution of progression-free survival (PFS) and overall survival (OS) with adjustment for covariates. Results for association between CCB usage and PCa aggressiveness were validated using data from the population-based North Carolina-Louisiana Prostate Cancer Project (PCaP).

RESULTS

48%, 37%, and 15% of RPCI's RP patients (n = 875) had low, intermediate, and high aggressive PCa, respectively. 104 (11%) had a history of CCB use. Patients taking CCBs were more likely to be older, have a higher BMI and use additional anti-hypertensive medications. Diagnostic PSA levels, PCa aggressiveness, and margin status were similar for CCB users and non-users. PFS and OS did not differ between the two groups. Tumor aggressiveness was associated with PFS. CCB use in the PCaP study population was not associated with PCa aggressiveness.

CONCLUSIONS

CCB use is not associated with PCa aggressiveness at diagnosis, PFS or OS.

Abstract LB-12: Plasma 25-hydroxyvitamin D levels are associated with aggressive prostate cancer among African Americans in the North Carolina-Louisiana Prostate Cancer Project (PCaP)

Background: Experimental and ecological studies support links between vitamin D and prostate cancer prevention and prognosis. Given the lower levels of circulating 25-hydroxyvitamin D [25(OH)D] and higher prostate cancer incidence and mortality among African Americans compared to other racial/ethnic groups, the aim of this investigation was to examine the relationship between plasma 25(OH)D levels and prostate cancer aggressiveness among African and European Americans.

Methods: Plasma 25(OH)D was measured using LC/MS/MS in 537 African Americans and 663 European Americans with newly-diagnosed prostate cancer from PCaP. Men were classified as cases (high aggressiveness) if Gleason sum ≥8, or PSA &gt;20 ng/ml, or Gleason sum ≥7 AND clinical stage = T3c-T4c, or Gleason sum=7 with primary pattern 4. The comparison group (low aggressiveness) included men with Gleason sum &lt;7 AND Stage T1-T2 AND PSA &lt; 9 ng/ml. Plasma 25(OH)D was categorized into tertiles in each race based on distributions among the comparison groups. Odds ratios (OR) and 95% confidence intervals (95%CI) were calculated for cases by tertile of plasma 25(OH)D using logistic regression with adjustment for potential confounders.

Results: African Americans had significantly lower mean concentrations of 25(OH)D (17.7 ± 7.6 ng/ml) compared to European Americans (24.6 ± 9.6 ng/ml). The highest tertile (mean=25.79 ng/ml & median=24.29 ng/ml) and middle tertile (mean=16.09 ng/ml & median=15.83) of plasma 25(OH)D were positively associated with highly aggressive prostate cancer among African Americans after adjustment for age, season, education, physical activity, smoking status, and PSA screening history (OR=1.7, 95% CI=1.0, 2.8 and OR=1.8, 95%CI=1.1, 3.0, respectively). No significant associations were observed for European American men.

Conclusions: Plasma 25(OH)D was positively associated with prostate cancer aggressiveness among African Americans but not European Americans, such that subjects with highly aggressive prostate cancer had increased odds of having higher plasma 25(OH)D levels. Research samples were collected after diagnosis, so effects of treatment, extent of disease or associated processes (e.g. weight loss) on plasma 25(OH)D may explain the findings. Ongoing studies include analysis of vitamin D binding protein (DBP) in the plasma and genotyping of DBP affinity variants in PCaP subjects. This approach may help explain the racial differences found, since DBP may modulate the impact of vitamin D status on prostate cancer.

Citation Format: Anna Woloszynska-Read, Lenore Arab, John Adams, Jeannette T. Bensen, Elizabeth TH Fontham, James L. Mohler, Joseph Su, Fred Tabung, Hongmei Zhang, Donald L. Trump, Candace S. Johnson, Susan E. Steck. Plasma 25-hydroxyvitamin D levels are associated with aggressive prostate cancer among African Americans in the North Carolina-Louisiana Prostate Cancer Project (PCaP). [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-12. doi:10.1158/1538-7445.AM2013-LB-12

Abstract 4852: Comparison of manual and automated scoring of androgen receptor staining in prostate tissue

Although manual scoring is generally used to evaluate the presence of androgen receptor (AR) protein as detected by immunohistochemistry in tissue, manual evaluation is tedious, inefficient and subjective. Therefore, manual scoring is not feasible for the evaluation of large numbers of patients. In this study, a technician (CP) rated AR staining in tissue sections of 3 tissue microarrays (TMAs) constructed from 3 cores each of benign and malignant tissue from 134 patients who underwent radical prostatectomy between 1993 and 2006 at Roswell Park Cancer Institute. The manual scorer randomly sampled 50 nuclei from each core and scored each nuclei as not stained (score =0), or lightly (score = 1), moderately (score=2) or darkly (score = 3) stained. The average staining intensity was recorded per patient across the benign cores, and across the tumor cores. Automated staining used the Image Pro image processing program, in which the entire core was scanned, all nuclei segmented and average intensity values per between 0 (completely black) and 255 (completely white) were determined for each nucleus. The mean staining score for each core is calculated by taking the average of all the identified nuclei in the core, and an average intensity is calculated per patient across the benign cores, and across the malignant cores.

The Pearson correlation between manual and automated scoring was 0.76. When stratified by benign or malignant tissue, the Pearson correlation between manual and automated scoring was 0.75 (benign) and 0.78 (malignant).

Automated scoring of AR staining is comparable to manual scoring of AR in prostate tissue. In light of the greater efficiency of automated scoring, future evaluations of immunohistochemical staining may be usefully conducted using automated scoring of nuclei.

Citation Format: Rochelle P. Ondracek, James L. Mohler, Catherine Pilarz, Sarah McEvoy, Karin Kasza, Carl Morrison, James Marshall. Comparison of manual and automated scoring of androgen receptor staining in prostate tissue. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4852. doi:10.1158/1538-7445.AM2013-4852

Receipt of National Comprehensive Cancer Network guideline-concordant prostate cancer care among African American and Caucasian American men in North Carolina

BACKGROUND

African Americans have a higher incidence of prostate cancer and experience poorer outcomes compared with Caucasian Americans. Racial differences in care are well documented; however, few studies have characterized patients based on their prostate cancer risk category, which is required to differentiate appropriate from inappropriate guideline application.

METHODS

The medical records of a population-based sample of 777 North Carolina men with newly diagnosed prostate cancer were studied to assess the association among patient race, clinical factors, and National Comprehensive Cancer Network (NCCN) guideline-concordant prostate cancer care.

RESULTS

African Americans presented with significantly higher Gleason scores (P = .025) and prostate-specific antigen levels (P = .008) than did Caucasian Americans. However, when clinical T stage was considered as well, difference in overall risk category only approached statistical significance (P = .055). Across risk categories, African Americans were less likely to have surgery (58.1% versus 68.0%, P = .004) and more likely to have radiation (39.0% versus 27.4%, P = .001) compared with Caucasian Americans. However, 83.5% of men received guideline-concordant care within 1 year of diagnosis, which did not differ by race in multivariable analysis (odds ratio = 0.83; 95% confidence interval  = 0.54-1.25). Greater patient-perceived access to care was associated with greater odds of receiving guideline-concordant care (odds ratio = 1.06; 95% confidence interval = 1.01-1.12).

CONCLUSIONS

After controlling for NCCN risk category, there were no racial differences in receipt of guideline-concordant care. Efforts to improve prostate cancer treatment outcomes should focus on improving access to the health care system.

Patient-health care provider communication among patients with newly diagnosed prostate cancer: findings from a population-based survey

OBJECTIVE

To examine the multidimensional concept of patient-health care provider (HCP) communication, its effects on patient satisfaction with oncology care services, and related racial differences.

METHODS

The current analysis draws from a population-based survey sample of 1011 African American and 1034 Caucasian American men with newly diagnosed prostate cancer. The variables of satisfaction with health care services, interpersonal treatment, contextual knowledge of the patient, and prostate cancer communication were analyzed using multiple-group structural equation modeling.

RESULTS

Regardless of race, patient-HCP communication was related positively to interpersonal treatment by the HCP, HCP's contextual knowledge of the patient, and prostate cancer communication. More positive patient-HCP communication was related to more satisfaction with health care services. Racial differences were significant in the relationships between patient-HCP communication and prostate cancer communication.

CONCLUSION

Content and interpersonal relationships are important aspects of patient-HCP communication and affect patient satisfaction with oncologic care for prostate cancer.

PRACTICE IMPLICATIONS

HCPs need to integrate the transfer of information with emotional support and interpersonal connection when they communicate with men with newly diagnosed prostate cancer.

The role of intracrine androgen metabolism, androgen receptor and apoptosis in the survival and recurrence of prostate cancer during androgen deprivation therapy

Prostate cancer (CaP) is the most frequently diagnosed cancer and leading cause of cancer death in American men. Almost all men present with advanced CaP and some men who fail potentially curative therapy are treated with androgen deprivation therapy (ADT). ADT is not curative and CaP recurs as the lethal phenotype. The goal of this review is to apply our current understanding of CaP and castration-recurrent CaP (CR-CaP) to earlier studies that characterized ADT and the molecular mechanisms that facilitate the transition from androgen-stimulated CaP to CR-CaP. Reexamination of earlier studies also may provide a better understanding of how more newly recognized mechanisms, such as intracrine metabolism, may be involved with the early events that allow CaP survival after initiation of ADT and subsequent development of CR-CaP.

Who makes the decision regarding the treatment of clinically localized prostate cancer--the patient or physician?: results from a population-based study

BACKGROUND

The current study examined how patients' sociodemographic, cancer-related, and subjective affective factors impacted their role in treatment decision-making.

METHODS

The patient sample (N = 788) was taken from a prospective follow-up study of a population-based cohort. Participants included 343 African American and 445 Caucasian-American patients with clinically localized prostate cancer. Multinomial logistic regression was used to investigate relations between the explanatory variables and the nominal 3-level decision-making variable: patient-only, patient-physician shared, and physician-only.

RESULTS

Approximately 41% of patients reported patient-only decision-making, 45% reported shared decision-making, and 13% reported physician-only decision-making. The odds of patient-only over physician-only decision-making were greater for younger men (vs those aged ≥ 65 years) (odds ratio [OR], 1.68; 95% confidence interval [95% CI], 1.03-2.74), and were less for men with high (vs low) cancer aggressiveness (OR,0.29; 95% CI, 0.15-0.55). The odds of shared over physician-only decision-making were less for men with high (vs low) cancer aggressiveness (OR, 0.40; 95% CI, 0.22-0.73). Greater odds of patient-only and shared decision-making also were found to be associated with greater concerns about the physical impact of treatment and having enough time for decision-making and lower scores of receiving advice from others.

CONCLUSIONS

The findings of the current study indicate that, to facilitate a more patient-oriented decision-making process regarding treatment in those with clinically localized prostate cancer, clinicians need to tailor their interventions according to patient age and cancer aggressiveness, help reduce patient concerns and misconceptions regarding the physical impact of treatments, allow sufficient time for patients to consider treatment options, and assist patients in balancing advice and information received from different sources.

Genetic polymorphism and prostate cancer aggressiveness: a case-only study of 1,536 GWAS and candidate SNPs in African-Americans and European-Americans

BACKGROUND

Genome-wide association studies have established a number of replicated single nucleotide polymorphisms (SNPs) for susceptibility to prostate cancer (CaP), but it is unclear whether these susceptibility SNPs are also associated with disease aggressiveness. This study evaluates whether such replication SNPs or other candidate SNPs are associated with CaP aggressiveness in African-American (AA) and European-American (EA) men.

METHODS

A 1,536 SNP panel which included 34 genome-wide association study (GWAS) replication SNPs, 38 flanking SNPs, a set of ancestry informative markers, and SNPs in candidate genes and other areas was genotyped in 1,060 AA and 1,087 EA men with incident CaP from the North Carolina-Louisiana Prostate Cancer Project (PCaP). Tests for association were conducted using ordinal logistic regression with a log-additive genotype model and a 3-category CaP aggressiveness variable.

RESULTS

Four GWAS replication SNPs (rs2660753, rs13254738, rs10090154, rs2735839) and seven flanking SNPs were associated with CaP aggressiveness (P < 0.05) in three genomic regions: One at 3p12 (EA), seven at 8q24 (5 AA, 2 EA), and three at 19q13 at the kallilkrein-related peptidase 3 (KLK3) locus (two AA, one AA and EA). The KLK3 SNPs also were associated with serum prostate-specific antigen (PSA) levels in AA (P < 0.001) but not in EA. A number of the other SNPs showed some evidence of association but none met study-wide significance levels after adjusting for multiple comparisons.

CONCLUSIONS

Some replicated GWAS susceptibility SNPs may play a role in CaP aggressiveness. However, like susceptibility, these associations are not consistent between racial groups.

The influence of mistrust, racism, religious participation, and access to care on patient satisfaction for African American men: the North Carolina-Louisiana Prostate Cancer Project

OBJECTIVE

The purpose of this study was to explore whether a particular combination of individual characteristics influences patient satisfaction with the health care system among a sample of African American men in North Carolina with prostate cancer. Patient satisfaction may be relevant for improving African American men's use of regular care, thus improving the early detection of prostate cancer and attenuating racial disparities in prostate cancer outcomes.

METHODS

This descriptive correlation study examined relationships of individual characteristics that influence patient satisfaction using data from 505 African American men from North Carolina, who prospectively enrolled in the North Carolina-Louisiana Prostate Cancer Project from September 2004 to November 2007. Analyses consisted of univariate statistics, bivariate analysis, and multiple regression analysis.

RESULTS

The variables selected for the final model were: participation in religious activities, mistrust, racism, and perceived access to care. In this study, both cultural variables, mistrust (p=<.0001, F=95.58) and racism (p=<.002, F=5.59), were significantly negatively associated with patient satisfaction and accounted for the majority of the variability represented by individual characteristics.

CONCLUSION

Mistrust and racism are cultural factors that are extremely important and have been negatively associated with patient satisfaction and decreased desires to utilize health care services for African American men. To overcome barriers in seeking health care services, health care providers need to implement a patient-centered approach by creating a clinical environment that demonstrates cultural competence and eliminating policies, procedures, processes, or personnel that foster mistrust and racism.

Melanoma antigen-A11 (MAGE-A11) enhances transcriptional activity by linking androgen receptor dimers

Prostate cancer growth and progression depend on androgen receptor (AR) signaling through transcriptional mechanisms that require interactions with coregulatory proteins, one of which is the primate-specific steroid receptor coregulator melanoma antigen-A11 (MAGE-A11). In this report, we provide evidence how increased expression of MAGE-A11 during prostate cancer progression enhances AR signaling and prostate cancer growth. MAGE-A11 protein levels were highest in castration-recurrent prostate cancer. The cyclic AMP-induced increase in androgen-dependent and androgen-independent AR transcriptional activity correlated with an increase in MAGE-A11 and was inhibited by silencing MAGE-A11 expression. MAGE-A11 mediated synergistic AR transcriptional activity in LAPC-4 prostate cancer cells. The ability of MAGE-A11 to rescue transcriptional activity of complementary inactive AR mutants and promote coimmunoprecipitation between unlike forms of AR suggests that MAGE-A11 links transcriptionally active AR dimers. A model for the AR·MAGE-A11 multidimeric complex is proposed in which one AR FXXLF motif of the AR dimer engages in the androgen-dependent AR NH(2)- and carboxyl-terminal interaction, whereas the second FXXLF motif region of the AR dimer interacts with dimeric MAGE-A11. The AR·MAGE-A11 multidimeric complex accounts for the dual functions of the AR FXXLF motif in the androgen-dependent AR NH(2)- and carboxyl-terminal interaction and binding MAGE-A11 and for synergy between reported AR splice variants and full-length AR. We conclude that the increased expression of MAGE-A11 in castration-recurrent prostate cancer, which is enhanced by cyclic AMP signaling, increases AR-dependent growth of prostate cancer by MAGE-A11 forming a molecular bridge between transcriptionally active AR dimers.

Abstract A103: Flavonoid intake and prostate cancer aggressiveness among African Americans and European Americans in PCaP

Background: Flavonoids are phytochemicals that are present in plant-based foods such as tea, wine, fruits, vegetables, and cocoa. Animal and cell culture studies indicate a chemopreventive effect of flavonoids on prostate cancer via mechanisms related to anti-inflammation, induction of apoptosis, antioxidation, cell cycle regulation, and impairment of angiogenesis. However, few epidemiological studies have examined associations between flavonoid intake and prostate cancer in humans.

Methods: Data from 920 African-American (AA) and 977 European-American (EA) newly-diagnosed prostate cancer patients from the North Carolina-Louisiana Prostate Cancer Project (PCaP) were used to assess the association between flavonoid intake and prostate cancer aggressiveness. Diet was assessed using a modified version of the National Cancer Institute (NCI) Diet History Questionnaire. The USDA recently released the 2011 USDA Database for the Flavonoid Content of Selected Foods, which allowed for estimation of intake of five subclasses of flavonoids that were summed to calculate total flavonoid intake. Men were classified as cases (high aggressiveness) if Gleason sum ≥8, or PSA &gt;20 ng/ml, or Gleason sum ≥7 AND clinical stage = T3c-T4c. All other men constituted the comparison group (low and intermediate aggressiveness). Odds ratios (OR) and 95% confidence intervals (95%CI) were calculated for high aggressiveness prostate cancer by tertile of flavonoid intake using logistic regression with adjustment for potential confounders.

Results: The highest tertile (compared to the lowest tertile) of total flavonoid intake appeared to be inversely associated with prostate cancer aggressiveness after adjustment for age, race, education, smoking status, and screening history (OR=0.75, 95%CI= 0.54, 1.04). Estimated odds of high aggressiveness prostate cancer with increasing flavonoid intake were reduced further by smoking and age, such that inverse associations were strongest in men &lt;65 years of age (OR=0.62, 95%CI=0.40, 0.98 and OR=0.67, 95%CI=0.42, 1.06 for the middle and highest tertiles, respectively) and in current smokers (OR=0.25, 95%CI=0.11, 0.54 and OR=0.48, 95%CI=0.22, 1.06 for the middle and highest tertiles, respectively). Results did not differ by race. Orange and grapefruit juices and tea were the main contributors to total flavonoid intake in both AA and EA men.

Conclusions: Total flavonoid intake was inversely associated with prostate cancer aggressiveness in this large case-only study. Stratified analyses revealed that current smokers and younger men may receive the most benefit from increased flavonoid intake. This study provides clinical evidence that suggests a plant-based diet may prevent aggressive prostate cancer.

Citation Format: Rebecca R. George, Susan E. Steck, L. Joseph Su, James L. Mohler, Elizabeth T.H. Fontham, Jeannette T. Bensen, James R. Hebert, Hongmei Zhang, Lenore Arab. Flavonoid intake and prostate cancer aggressiveness among African Americans and European Americans in PCaP. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr A103.

Serum glutamate levels correlate with Gleason score and glutamate blockade decreases proliferation, migration, and invasion and induces apoptosis in prostate cancer cells

PURPOSE

During glutaminolysis, glutamine is catabolized to glutamate and incorporated into citric acid cycle and lipogenesis. Serum glutamate levels were measured in patients with primary prostate cancer or metastatic castrate-resistant prostate cancer (mCRPCa) to establish clinical relevance. The effect of glutamate deprivation or blockade by metabotropic glutamate receptor 1 (GRM1) antagonists was investigated on prostate cancer cells' growth, migration, and invasion to establish biologic relevance.

EXPERIMENTAL DESIGN

Serum glutamate levels were measured in normal men (n = 60) and patients with primary prostate cancer (n = 197) or mCRPCa (n = 109). GRM1 expression in prostatic tissues was examined using immunohistochemistry (IHC). Cell growth, migration, and invasion were determined using cell cytotoxicity and modified Boyden chamber assays, respectively. Apoptosis was detected using immunoblotting against cleaved caspases, PARP, and γ-H2AX.

RESULTS

Univariate and multivariate analyses showed significantly higher serum glutamate levels in Gleason score ≥ 8 than in the Gleason score ≤ 7 and in African Americans than in the Caucasian Americans. African Americans with mCRPCa had significantly higher serum glutamate levels than those with primary prostate cancer or benign prostate. However, in Caucasian Americans, serum glutamate levels were similar in normal research subjects and patients with mCRPC. IHC showed weak or no expression of GRM1 in luminal acinar epithelial cells of normal or hyperplastic glands but high expression in primary or metastatic prostate cancer tissues. Glutamate deprivation or blockade decreased prostate cancer cells' proliferation, migration, and invasion and led to apoptotic cell death.

CONCLUSIONS

Glutamate expression is mechanistically associated with and may provide a biomarker of prostate cancer aggressiveness.

Abstract B33: Genome-wide methylation analyses reveal racial differences in blood DNA of prostate cancer patients from the North Carolina-Louisiana Prostate Cancer Project (PCaP) cohort

Epigenetic aberrations occur early in prostate carcinogenesis and contribute to disease progression. African American men experience the highest incidence and mortality from prostate cancer among all groups of men in the US. However, the role of epigenetics in prostate cancer health disparities in African American men has not been investigated thoroughly. Although prostate cancer health disparities are complex phenomena, evidence exists that biological mechanisms contribute to disparity. DNA methylation plays an important role in prostate cancer etiology and progression. Environment-gene interactions may differ between racial groups, in turn leading to variably altered methylomes. Genome-wide investigation of epigenetic variation between African Americans and European Americans may contribute to an understanding of the underlying mechanisms of these health disparities and help identify novel biomarkers of aggressive prostate cancer. We performed a pilot, new generation genome-wide DNA methylation profiling of peripheral blood cell (PBC) DNA from fourteen African Americans and twelve European Americans from the North Carolina-Louisiana Prostate Cancer Project (PCaP) cohort who were matched by age and disease stage. We utilized 450K Illumina methylation array for our studies. Interestingly, we found that African Americans and European Americans are separated into two distinct DNA methylation subgroups using a model-based cluster analysis. Global methylation analysis showed patterns of hypermethylation in African Americans when compared to European Americans, most significantly evident in non-CpG island promoter regions. We then examined gene candidates that were previously implicated in prostate cancer or differentially methylated in normal prostate tissues in African Americans versus European Americans. We identified several genes (e.g., NKX2, RAR-β, and TIMP3) with significant promoter DNA hypermethylation in African Americans when compared to European Americans; this suggests that PBC DNA may in part recapitulate methylation patterns seen in prostate tissue. Our findings demonstrate that racial differences in methylation patterns exist in the blood DNA of prostate cancer patients, which supports the concept that environment-gene interactions might differ among racial and ethnic groups. Furthermore, our findings suggest that future studies should take racial differences into account when searching for blood-based methylation biomarkers. Our ongoing work will explore whether such differences relate to more aggressive disease and poorer prostate cancer outcomes in African Americans when compared to men of European ancestry. (Funded by a grant to AWR from the DoD W81XWH1110308).

Citation Format: Anna Woloszynska-Read, Dan Wang, Song Liu, James L. Mohler, Donald L. Trump, Candace S. Johnson. Genome-wide methylation analyses reveal racial differences in blood DNA of prostate cancer patients from the North Carolina-Louisiana Prostate Cancer Project (PCaP) cohort. [abstract]. In: Proceedings of the Fifth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2012 Oct 27-30; San Diego, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(10 Suppl):Abstract nr B33.

Patient Satisfaction Influenced by interpersonal treatment and communication for African American men: the North Carolina-Louisiana Prostate Cancer Project (PCaP)

The purpose of this study was to determine if a particular set of health behaviors of health care providers and African American men (AAM) influence patient satisfaction from the AAM's perspective. This descriptive, correlational study consisted of 505 AAM in North Carolina diagnosed with prostate cancer and enrolled in the North Carolina-Louisiana Prostate Cancer Project (PCaP). Analyses consisted of bivariate analyses and multiple regression. Patient-to-provider communication, interpersonal treatment, and provider-to-patient communication accounted for 45% (p ≤ .0001) of the variability in patient satisfaction. Interpersonal treatment (provider focusing on the patient) explained the greatest amount (F = 313.53, R² = .39) of patient satisfaction. Since interpersonal treatment focuses on the patient and demonstrated to be the strongest predictor in patient satisfaction, it is noteworthy to consider the emphasis that should be placed on patient-centered care. In addition, knowing important variables positively affecting patient satisfaction provides useful information for developing appropriate interventions to improve AAM health care experiences.