Abstract 1973: Novel relationships of expression of methylxanthine alkaloid receptor genes and risk of breast carcinoma recurrence
Authors: Sereff Seth B. , Daniels Michael W. , Wittliff James L. 
Published: July 2017

Consumption of methylxanthine alkaloids such as caffeine, theophylline and theobromine may induce breast pain. Caffeine appears to induce its biological activities by antagonizing adenosine receptors, which have been implicated in breast cancer cell behavior in vitro. Our goal is to evaluate expression of genes for methylxanthine receptors and metabolizing enzymes for assessing risk of breast cancer recurrence.

Procedures: De-identified primary cancers previously collected, stored and analyzed under stringent conditions were employed to amass an IRB-approved, de-identified comprehensive Database. Patient-related properties (e.g., nodal status, clinical outcome) and results from estrogen (ER) and progestin receptor (PR) analyses and gene expression assays guided selection. To decode clinical utility of gene expression profiles, Laser Capture Microdissection (PixCell IIe™ Arcturus/Thermo Fisher) was used previously to non-destructively collect carcinoma cells. RNA was extracted, amplified and analyzed by microarray (~ 22,000 genes).

Results: Gene expression levels of 8 methylxanthine receptors, 8 metabolizing enzymes and various phosphodiesterases were retrieved from microarray results of 247 breast biopsies. Univariable Cox regressions and Kaplan Meier plots were determined for each candidate gene with R software. Kaplan-Meier plots of PDE4A, CYP2A6 or CYP2E individually indicated lower expression was related to decreased progression free (PFS) and overall survival (OS) while PDE1A over-expression predicted decreased PFS and OS. ADORA2B and RYR1 over-expression was associated with lower OS. Gene expression was examined with ER or PR status without regard to clinical outcome. Breast cancers that were ER+ exhibited lower ADORA1, ADORA2B and RYR1 expression and elevated expression of PDE4A, CYP2A6 and CYP2E. PR+ carcinomas also exhibited decreased expression of ADORA2B and RYR1 expression. However, over-expression of ADORA3, PDE4A, CYP2C8 and CYP2E was observed in PR+ cancers. Analysis of variance (ANOVA) of carcinomas according to ER/PR status indicated ADORA2B expression was elevated in ER- cancers regardless of PR status. ANOVA also showed PDE4A was over expressed in ER+ carcinomas regardless of PR status. LASSO analysis revealed CYP2E, PDE1A and PDE4A expression taken jointly predicted PFS which was validated externally (Breast Cancer Meta-base) with SurvExpress.

Conclusions: Collectively, results suggest expression of genes involved in methylxanthine action and metabolism may be used to predict breast cancer behavior. Significantly, we identified gene expression signatures in single cell types that were highly associated with clinical outcome suggesting promise for development of novel prognostic tests for breast carcinoma management and design of new therapeutics.

Citation Format: Seth B. Sereff, Michael W. Daniels, James L. Wittliff. Novel relationships of expression of methylxanthine alkaloid receptor genes and risk of breast carcinoma recurrence [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1973. doi:10.1158/1538-7445.AM2017-1973