The Discovery Of a New factor That Promotes Breast Cancer

            Breast cancer is the second most commonly diagnosed cancer in women; the estrogen-receptor positive breast cancer (ER+ breast cancer) is the most common type. Researchers determined estrogen to promote tumor growth in ER+ breast cancer; patients with ER+ breast cancer would undergo endocrine-base therapies. The therapies consisted of depleting tumors of estrogen, therefore inhibiting the growth of tumors. However, these therapies have been unsuccessful in many patients diagnosed with ER+ breast cancer. Research conducted by Wu et al. has discovered another promoter of tumor growth in ER+ breast cancer, the cholesterol metabolite 27-hydroxycholesterol (27HC). This could also be an explanation of why endocrine-base therapies have been unsuccessful in several cases.

            The research conducted by Wu et al. examined patients with ER+ breast cancer. The results displayed in tumor tissue 27HC content were more abundant than in normal breast tissue. The increase of 27HC content in tumors was a result of the decreased expression of CYP7B1, an enzyme that metabolizes 27HC. The enzyme, CYP7B1 not being able to break down 27HC leads to the increase of 27HC and can be connected with ER+ breast cancer. The prognosis of ER+ breast cancer is dependent on CYP7B1, and the suppression is linked with mortality in cancer patients.

            There are factors that can cause the increase of 27HC such as, women that undergo menopause. The increase of 27HC may be related to the decrease of estrogen that postmenopausal women experience. It has been discovered that estrogen helps regulate CYP7B1 and decreases the 27HC content. Other factors that increase 27HC are obesity, hypercholesterolemia and dyslipidermia also referred to as high-fat and high-cholesterol in the body. High-fat diets and obesity increase the risk of breast cancer and obesity displayed an increase in tumor growth. The results displayed these factors as being promoters for ER+ breast cancer.

            The significance of the research is the ability to find new therapies that revolve around decreasing 27HC content or increasing the metabolizing enzyme CYP7B1. The research allows healthcare providers to determine a prognosis based on CYP7B1 levels in the body. More research needs to be conduct to determine prevention and treatment of ER+ breast cancer.

By UT Southwestern Medical Center

Dr. Philip Shaul and his team were the first to determine that 27HC promotes tumor growth in breast cancer. 

 References

Qian Wu, Tomonori Ishikawa, Rosa Sirianni, Hao Tang, Jeffrey G. McDonald, Ivan S. Yuhanna, Bonne Thompson, Luc Girard, Chieko Mineo, Rolf A. Brekken, Michihisa Umetani, David M. Euhus, Yang Xie, Philip W. Shaul. 27-Hydroxycholesterol Promotes Cell-Autonomous, ER-Positive Breast Cancer Growth. Cell Reports, 2013; DOI:10.1016/j.celrep.2013.10.006

UT Southwestern Medical Center (2013, November 7). Researchers discover new driver of breast cancer. ScienceDaily. Retrieved November 9, 2013, from http://www.sciencedaily.com/releases/2013/11/131107122744.htm