Tumor-specific expression of HMG-CoA reductase in a population-based cohort of breast cancer patients

Background: The mevalonate pathway synthetizes cholesterol, steroid hormones, and non-steriod isoprenoids necessary for cell survival. 3-Hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) is the rate-limiting enzyme of the mevalonate pathway and the target for statin treatment. HMGCR expression in breast tumors has recently been proposed to hold prognostic and treatment-predictive information. This study aimed to investigate whether HMGCR expression in breast cancer patients was associated with patient and tumor characteristics and disease-free survival (DFS). Methods: A population-based cohort of primary breast cancer patients in Lund, Sweden was assembled between October 2002 and June 2012 enrolling 1,116 patients. Tumor tissue microarrays were constructed and stained with a polyclonal HMGCR antibody (Cat. No HPA008338, Atlas Antibodies AB, Stockholm, Sweden, diluted 1: 100) to assess the HMGCR expression in tumor tissue from 885 patients. HMGCR expression was analyzed in relation to patient-and tumor characteristics and disease-free survival (DFS) with last follow-up June 30th 2014. Results: Moderate/ strong HMGCR expression was associated with less axillary lymph node involvement, lower histological grade, estrogen and progesterone receptor positivity, HER2 negativity, and older patient age at diagnosis compared to weak or no HMGCR expression. Patients were followed for up to 11 years. The median follow-up time was 5.0 years for the 739 patients who were alive and still at risk at the last follow-up. HMGCR expression was not associated with DFS. Conclusion: In this study, HMGCR expression was associated with less aggressive tumor characteristics. However, no association between HMGCR expression and DFS was observed. Longer follow-up may be needed to evaluate HMGCR as prognostic or predictive marker in breast cancer.