Abstract 5250: Effect of the β-blocker carvedilol in preventing DMBA-induced mammary gland tumor growth
Authors: Sardar Pabitra Kumar , Yeung Steven , Shahid Ayaz , Andresen Bradley T. , Huang Ying 
Published: April 2023

Abstract
According to global cancer statistics, breast cancer has now become the most diagnosed cancer and has become the fifth leading cause of cancer-related deaths worldwide. A promising method of retarding cancer-related mortality is cancer chemoprevention. However, there is no drug available that can be used routinely as a breast cancer-preventative agent. As carvedilol (CAR), an FDA-approved beta-adrenergic receptor blocker, reduces breast cancer mortality, we hypothesized that CAR might act as a breast cancer preventative agent. Three protocols were utilized to evaluate the ability of CAR to prevent 7,12-Dimethylbenz(a)anthracene (DMBA)-induced mammary tumors in rats. In protocol 1, two doses of CAR (2 and 10 mg/kg) were administered in drinking water as a 7-day pretreatment and throughout the study. In protocol 2, 10 mg/kg tamoxifen and 10 mg/kg carvedilol were provided as a 7-day pretreatment, and treatment was halted after six weeks. In protocol 3, CAR and the non-β-blocking enantiomer R-carvedilol (10 mg/kg) were given as a 7-day pretreatment and throughout the study. In all studies, animals were palpated weekly beginning at week 5 to detect the presence and location of mammary tumors. Tumors were measured using a caliper, and the experiments terminated at week 13. In protocol 1, only 10 mg/kg CAR was effective in delaying DMBA-mediated tumor occurrence (p = 0.0002); the first appearance of tumors and median tumor appearance in CAR-treated rats were separated from rats receiving DMBA alone by 2 and 4 weeks, respectively. However, tumors that did form grew at the same rate in all groups. In protocol 2, tamoxifen served as a control to prevent DMBA-mediated tumors; only one tamoxifen-treated rat developed a tumor at the end of the study. The tamoxifen-treated rats tumor formation was not statistically different than negative controls; however, the CAR group was not statistically different from the DMBA group. In protocol 3, CAR and R-CAR treatment showed delayed tumor formation and growth compared to the DMBA-only group, although not statistically significant. Combining all DMBA and 1-week pretreatment CAR data (n = 58 and 40, respectively), CAR effectively prevents DMBA-induced tumor incidence (p = 0.001), with a 3-week differential in the median tumor formation between the two groups. Therefore, continuous CAR treatment is essential to achieve the observed chemopreventive effects. As carvedilol is a clinically used beta-blocker, the results provide significant implications in breast cancer chemoprevention.
Citation Format: Pabitra Kumar Sardar, Steven Yeung, Ayaz Shahid, Bradley T. Andresen, Ying Huang. Effect of the β-blocker carvedilol in preventing DMBA-induced mammary gland tumor growth. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5250.