Abstract 2862: BMP4 mediated suppression of cholesterol synthesis and breast cancer metastasis

Abstract

Abstract Breast cancer affects one in seven women and kills more than 600,000 women each year. Compared to the 98.9% survival rate of patients with localized breast cancer, the five-year survival rate of patients with distant metastasis is only 28.1%. Using cDNA arrays and patient datasets, we found that a protein called bone morphogenetic protein 4 (BMP4) is downregulated in highly metastatic breast cancer cells and in high-grade breast tumors. BMP4 is a ligand in the TFGβ/BMP cytokine family and has the capacity to suppress TGFβ signaling through induction of SMAD6 and SMAD7. In several different preclinical metastasis models, we have shown that restored BMP4 expression in breast cancer cells with metastatic capacity does not alter primary tumor growth but results in significantly reduced metastasis to lung, liver and spine (p< 0.01), following primary tumor resection. MDA-MB-231HM cells with or without enforced BMP4 expression were recovered from primary mammary tumors and subjected to transcriptomic profiling by RNAseq. This analysis revealed that BMP4 suppressed multiple genes involved in the cholesterol biosynthesis pathway (p=2.56×10-7) and down-regulated cholesterol levels in the tumors (p=0.042). In a patient cohort of over 2000 predominantly luminal breast cancers, we found that stage, as measured by size and lymph node status, was not altered by statin use, however statin users had less high grade tumors and more luminal A tumors. In terms of recurrence, we found a marked risk reduction in patients with luminal B tumors (p=0.014) and particularly in Her2+ luminal B tumors (p=0.045). Lung, liver and brain metastases were most reduced in statin users. Current experiments involve testing a statin therapy, with the knowledge that statins are not effective in mice, but should inhibit cholesterol synthesis in human tumors in xenograft models. In addition, we are testing an inhibitor of the nuclear receptor RORγ that has been reported to activate cholesterol synthesis through SREBP2, a master regulator of cholesterol synthesis. Citation Format: Robin L. Anderson, Lap Hing Chi, Allan D. Burrows, Suraya Roslan, Andrew Redfern. BMP4 mediated suppression of cholesterol synthesis and breast cancer metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2862.