In vitro and in vivo evaluation of doxorubicin‐based anti‐cancer treatment in combination with the herbal medicine black cohosh (655.3)

Abstract

Many breast cancer patients use herbal extracts of black cohosh (BC) in combination with doxorubicin (DOX). In this study we evaluated the synergistic effects of BC and DOX on: (1) in vitro viability, colony formation of human breast cancer cells (MCF‐7), and (2) in vivo evaluation of tumor growth and metabolism.For viability study, MCF‐7 were incubated with DOX (1‐100μM for 2hrs) and BC (100xdose for 6hrs) alone or combined. To assess the MCF‐7 survival, we used a clonogenic assay. MCF‐7 were incubated with DOX (0.1‐10μM for 2hrs) and BC (10‐100x dose for 6hrs) alone or combined, and cultured for 2wks. Colonies were scanned with a digital stereoscope and counted.In vivo experiments were performed on OVEX nude mice injected with MCF‐7. After 6wks of tumor growth, animals were divided into groups: a control and those receiving DOX (4mg/kg/wk), BC (20mg/kg/d) or both DOX and BC. Tumor growth was measured twice a week using digital calipers. We performed PET‐CT imaging with 18F‐FDG at baseline, 2 and 6 wks after the treatment. PET‐CT images were analyzed and tumor activity expressed as %ID/g.We observed significant increase in the number of apoptotic cells after incubation with both DOX and BC vs. control. DOX altered the potential of MCF‐7 cells to form colonies, however co‐incubation with BC did not affect this process. In vivo PET‐CT revealed significant reduction in tumor metabolism after treatment with DOX (40%) and BC (20%) alone. However, we did not observe any synergistic effects when treated with DOX and BC. Both DOX and BC inhibited tumor growth by 20% and 12%, respectively. DOX and BC treatment resulted in a 57% reduction in tumor size.BC exerts synergistic effects on DOX cytotoxicity resulting in reduction in tumor size, but this change is independent of in vitro ability of MCF‐7 to form colonies, and in vivo tumor glucose metabolism. Further studies are necessary to establish which mechanism underlies these effects and to examine potential clinical implications in management of breast cancer patients.Grant Funding Source: UIUC Research Board Award (Dobrucki, I.T.)