Background: The Mediterranean herb rosemary has been used for culinary purposes and for their medicinal properties for millennia. Rosemary and its polyphenolic diterpenes (carnosol and carnosic acid) are known to possess anti-oxidant activity that may be beneficial for cancer control. Colorectal cancer is the second leading cause of death from cancer in the United States. Nutrition, particularly intake of vegetables and certain plant components, has been reported to have a major role in colon cancer risk reduction. In our current study, we investigated the anticancer effects of rosemary extract and its two main active ingredients carnosol and carnosic acid on colon cancer cell lines to understand the mechanism. Next, we evaluated the anti-cancer activity of rosemary extract in a nude mice model.

Methods: Two human colon cancer cell lines, HCT116 and SW480, were treated with rosemary extract, carnosol or carnosic acid. MTT, TUNEL and ELISA were used to evaluate cell viability and apoptosis. Western blot and immunofluorescence were used to detect proteins involved in apoptosis. We also evaluated the anti-cancer activity of rosemary extract in nude mouse inoculated with HCT116 cells.

Results: Rosemary extract, carnosol and carnosic acid, increased apoptosis, decreased viability in colon cancer cell lines. Rosemary extract, carnosol and carnosic acid significantly upregulated the expression of Nrf2 and ERK. Rosemary extract also effectively suppressed tumor growth in a xenograft tumor model without affecting body weight.

Conclusions: Rosemary extract inhibits colon cancer cell growth in a xenograft mouse model without observable toxicity. Furthermore, rosemary extract, carnosol and carnosic acid induce the expression of Nrf2 and ERK pathways in colon cancer cells, suggesting further research is needed to evaluate its potential as an anti-cancer and/or chemoprevention agent.

Citation Format: Miao Yan, Gongbo Li, Sakina M. Patiwala, Emily Householter, Jeremy J. Johnson. Anti-cancer activity of rosemary extract in colon cancer cells: Involvement of Nrf2 and ERK pathways. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4122. doi:10.1158/1538-7445.AM2014-4122