Comparative Genomics Reveals Distinct Immune-oncologic Pathways in African American Men with Prostate Cancer

PURPOSE

The role of immune-oncologic mechanisms of racial disparities in prostate cancer remains understudied. Limited research exists to evaluate the molecular underpinnings of immune differences in African American men (AAM) and European American men (EAM) prostate tumor microenvironment (TME).

EXPERIMENTAL DESIGN

A total of 1,173 radiation-naïve radical prostatectomy samples with whole transcriptome data from the Decipher GRID registry were used. Transcriptomic expressions of 1,260 immune-specific genes were selected to assess immune-oncologic differences between AAM and EAM prostate tumors. Race-specific differential expression of genes was assessed using a rank test, and intergene correlational matrix and gene set enrichment was used for pathway analysis.

RESULTS

AAM prostate tumors have significant enrichment of major immune-oncologic pathways, including proinflammatory cytokines, IFNα, IFNγ, TNFα signaling, ILs, and epithelial-mesenchymal transition. AAM TME has higher total immune content score (ICS^HIGH) compared with 0 (37.8% vs. 21.9%, P = 0.003). AAM tumors also have lower DNA damage repair and are genomically radiosensitive as compared with EAM. IFITM3 (IFN-inducible transmembrane protein 3) was one of the major proinflammatory genes overexpressed in AAM that predicted increased risk of biochemical recurrence selectively for AAM in both discovery [HR_AAM = 2.30; 95% confidence interval (CI), 1.21-4.34; P = 0.01] and validation (HR_AAM = 2.42; 95% CI, 1.52-3.86; P = 0.0001) but not in EAM.

CONCLUSIONS

Prostate tumors of AAM manifest a unique immune repertoire and have significant enrichment of proinflammatory immune pathways that are associated with poorer outcomes. Observed immune-oncologic differences can aid in a genomically adaptive approach to treating prostate cancer in AAM.

Dose-dependent detoxication of the airborne pollutant benzene in a randomized trial of broccoli sprout beverage in Qidong, China

BACKGROUND

Airborne pollutants have collectively been classified as a known human carcinogen and, more broadly, affect the health of hundreds of millions of people worldwide. Benzene is a frequent component of air pollution, and strategies to protect individuals against unavoidable exposure to this and other airborne carcinogens could improve the public's health. Earlier clinical trials in Qidong, China, demonstrated efficacy in enhancing the detoxication of benzene using a broccoli sprout beverage.

OBJECTIVES

A randomized, placebo-controlled, multidose trial of a broccoli sprout beverage was designed to determine the lowest effective concentration that enhances benzene detoxication adjudged by enhanced excretion of the urinary biomarker, S-phenylmercapturic acid (SPMA).

METHODS

Following informed consent, 170 subjects were randomly assigned in 5 blocks of 34 each to drink either a placebo beverage (n = 55) or 1 of 3 graded concentrations of a broccoli sprout beverage [full (n = 25), one-half (n = 35), and one-fifth (n = 55)] for 10 consecutive days. Concentrations of SPMA arising through induced benzene conjugation with glutathione were quantified by MS in sequential 12-h overnight urine collections during the intervention.

RESULTS

MS was also used to quantify urinary sulforaphane metabolites in each dosing regimen that resulted in a median 24-h urinary output of 24.6, 10.3, and 4.3 µmol, respectively, confirming a dose-dependent de-escalation of the inducing principle within the beverage. A statistically significant increase in benzene mercapturic acids in urine was found for the high-dose group (+63.2%) during the 10-d period. The one-half dose (+11.3%) and one-fifth dose groups (-6.4%) were not significantly different from placebo controls.

CONCLUSIONS

An intervention with a broccoli sprout beverage enhanced the detoxication of benzene, an important airborne pollutant, when dosed at a concentration evoking a urinary elimination of ∼25 µmol sulforaphane metabolites per day, and it portends a practical and frugal population-based strategy to attenuate associated long-term health risks of air pollution. This trial was registered at clinicaltrials.gov as NCT02656420.

Abstract P1-09-01: CD8+ T-cell gene expression and signatures in breast cancer and adjacent normal breast tissue: Association with body mass index, alcohol intake, and age at diagnosis

Background: Our understanding of mediators of immune infiltration in breast cancer and normal breast tissue remains limited. We hypothesize that patient factors known to be associated with inflammation and immune subsets, including body mass index, alcohol intake, and age and diagnosis, may play an important role in the tumor-immune microenvironment. Analyses of immune gene expression and signatures facilitate interrogation of the immune microenvironment in large patient cohorts.

Methods: Participants from the Nurses' Health Study cohorts I and II diagnosed with invasive breast cancer were included. Total RNA extracted and microarray performed for 882 tumor and 695 tumor-adjacent samples, of which 623 tumors have matched tumor-adjacent data. CD8+ T-cell expression metrics were assessed: CD8A single gene expression (CD8Agene), a CD8 T-cell signature (CD8sig), and a tumor infiltrating lymphocyte signature derived from the GeparSixto clinical trial (GSAct). Standard clinicopathologic features were evaluated, as well as body mass index (BMI) one year prior to diagnosis, cumulative average alcohol intake, and age at diagnosis.

Results: Overall, tumor and adjacent normal tissue demonstrated positive correlation of CD8Agene, CD8sig, and GSAct (n=623 pairs, Pearson's r = 0.46, 0.36, 0.31, respectively; all p<0.001). Similar correlations were present in TCGA breast cancer, an independent cohort (n=112 pairs, Pearson's r = 0.34, 0.17, 0.45, respectively; all p<0.001). We evaluated paired tumor and adjacent normal samples within individual immunohistochemical (IHC) subtype or PAM50 subtype by Wilcoxon signed-rank test. There was not a consistent trend for CD8Agene, CD8sig, nor GSAct to be greater in tumor or normal within subtypes. We then evaluated patient features/exposures and tumor immune expression metrics. For tumor-adjacent normal, there was no significant association of alcohol intake, BMI, or age at diagnosis with CD8 gene/expression metrics. For tumor tissue, a multivariate model demonstrated that BMI one year before diagnosis was significantly associated with CD8Agene expression. There was no significant association of alcohol intake or age at diagnosis with CD8 gene/expression metrics. We are currently evaluating the association of these CD8 T-cell gene expression signatures with CD8 T-cell immunohistochemistry in a subset of patients, which will be reported at the time of abstract presentation.

Conclusion: In this cohort of over 600 tumor:normal pairs and a separate validation cohort, multiple distinct CD8+ T-cell expression metrics are correlated between breast cancer and tumor-adjacent normal breast tissue. This suggests that the adjacent normal breast may reflect an altered immune microenvironment in the context of breast cancer. While age at diagnosis and alcohol intake are not significantly associated with tumor CD8 expression metrics, BMI was significantly associated with tumor CD8Agene expression in a multivariate model.

Citation Format: Damicis A, Heng YJ, Kensler K, Asad S, Adams E, Singh J, Zhang Y, Nock W, Wesolowski R, Williams N, Reinbolt R, Sardesai S, VanDeusen J, Noonan A, Lustberg MB, Ramaswamy B, Eliassen AH, Hankinson SE, Tamimi R, Stover DG. CD8+ T-cell gene expression and signatures in breast cancer and adjacent normal breast tissue: Association with body mass index, alcohol intake, and age at diagnosis [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-09-01.

EZH2 protein expression in normal breast epithelium and risk of breast cancer: results from the Nurses' Health Studies

BACKGROUND

Enhancer of zeste homolog 2 (EZH2) is a polycomb-group protein that is involved in stem cell renewal and carcinogenesis. In breast cancer, increased EZH2 expression is associated with aggressiveness and has been suggested to identify normal breast epithelium at increased risk of breast cancer development. However, the association between EZH2 expression in benign breast tissue and breast cancer risk has not previously been evaluated in a large prospective cohort.

METHODS

We examined the association between EZH2 protein expression and subsequent breast cancer risk using logistic regression in a nested case-control study of benign breast disease (BBD) and breast cancer within the Nurses' Health Studies. EZH2 immunohistochemical expression in normal breast epithelium and stroma was evaluated by computational image analysis and its association with breast cancer risk was analyzed after adjusting for matching factors between cases and controls, the concomitant BBD diagnosis, and the Ki67 proliferation index.

RESULTS

Women with a breast biopsy in which more than 20% of normal epithelial cells expressed EZH2 had a significantly increased risk of developing breast cancer (odds ratio (OR) 2.95, 95% confidence interval (CI) 1.11-7.84) compared to women with less than 10% EZH2 epithelial expression. The risk of developing breast cancer increased for each 5% increase in EZH2 expression (OR 1.22, 95% CI 1.02-1.46, p value 0.026). Additionally, women with high EZH2 expression and low estrogen receptor (ER) expression had a 4-fold higher risk of breast cancer compared to women with low EZH2 and low ER expression (OR 4.02, 95% CI 1.29-12.59).

CONCLUSIONS

These results provide further evidence that EZH2 expression in the normal breast epithelium is independently associated with breast cancer risk and might be used to assist in risk stratification for women with benign breast biopsies.

Abstract 4295: Androgen receptor expression in normal breast TDLUs and subsequent breast cancer risk

Background

Sex steroid hormone signaling is critical in the development and progression of breast cancers, though the role of androgens remains unspecified. Large epidemiologic studies have found a consistent association between circulating androgens and increased breast cancer risk, though it is unknown whether circulating androgens reflect the androgenic milieu in the breast. An interaction between androgen receptor (AR) and estrogen receptor (ER) signaling in the breast has been postulated, wherein AR signaling antagonizes ER signaling in estrogen-rich environments, and AR signaling induces proliferative effects in estrogen-deplete environments.

Methods

We evaluated the association between AR expression and subsequent breast cancer risk in a nested case-control study of women with benign breast disease (BBD) within the Nurses’ Health Studies. Cases were women with BBD that subsequently developed breast cancer (median 9 years later) while controls had BBD but did not develop breast cancer. Tissue microarrays were constructed containing normal terminal ductal lobular unit (TDLU) tissue from the BBD biopsy. AR expression was assessed by immunohistochemistry and the percent of positive-staining nuclei was digitally quantified for 61 breast cancer cases and 184 controls. Logistic regression models adjusting for the year of BBD biopsy, age at cancer diagnosis, years since BBD biopsy, and BBD lesion type were used to calculate odds ratios and 95% confidence intervals for the association between the tertile of AR expression and breast cancer risk. We further evaluated the impact of AR and ER co-expression, each dichotomized at the median, in a sub-analysis of 31 cases and 82 controls. Finally, we assessed AR expression as a predictor of subsequent ER tumor status using polytomous logistic regression.

Results

Overall, women in the highest tertile of AR expression experienced non-significant 1.32-fold increased odds of breast cancer (95% CI: 0.64-1.73, p-trend = 0.559) compared to the lowest tertile. A significant interaction was detected between AR and ER co-expression in normal breast TDLUs and subsequent breast cancer risk (p-interaction = 0.003). Among women with low ER expression, increased AR expression was associated with 2.52-fold increased odds (95% CI: 0.68-9.34) of developing breast cancer. In contrast, among women with high ER expression, high AR expression was associated with a 91% decrease in the odds (OR = 0.09, 95% CI: 0.01-0.62) of breast cancer. AR expression was not predictive of subsequent ER tumor status.

Conclusions

There was little evidence for an overall association between AR expression in normal breast tissue and breast cancer risk, though we observed a significant interaction between AR and ER expression. Our findings support the hypothesis that AR interacts with ER to promote cell proliferation in estrogen-deprived environments and inhibit growth in estrogen-rich environments.

Citation Format: Kevin Kensler, Andrew Beck, Francisco Beca, Laura Collins, Stuart Schnitt, Aditi Hazra, Susan Hankinson, Myles Brown, Rulla Tamimi. Androgen receptor expression in normal breast TDLUs and subsequent breast cancer risk. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4295.