Abstract LB-283: Prognostic significance of BRMS1 promoter methylation in operable breast cancer.

Abstract

Abstract Introduction: Breast Cancer Metastasis Suppressor-1 (BRMS1) encodes a predominantly nuclear protein that differentially regulates expression of multiple genes, leading to suppression of metastasis without affecting orthotopic tumor growth. We examined the clinical relevance of BRMS1 promoter methylation in early breast cancer. Methods: We analyzed 118 formalin-fixed paraffin embedded samples: 5 pairs of breast tumors and adjacent non-cancerous tissues, 14 non-cancerous tissues, 10 benign fibroadenomas, and 84 primary breast tumors. Peripheral blood mononuclear cells were isolated from 39/84 of these patients and were fixed in cytospins. BRMS1 methylation status was investigated in all FFPE and cytospin stained circulating tumor cells using methylation specific PCR. BRMS1 expression was examined using double-immunofluorescence in isolated PBMC cytospins using anti-BRMS1 and pancytokeratin A45-B/B3 antibodies. Results: BRMS1 promoter methylation was observed in 0/19 noncancerous breast tissues, 0/10 benign fibroadenomas and 31/84(37.8%) breast tumors. During the follow-up period 27/84(32.1%) patients relapsed of which 19/84(22.6%) patients died as a consequence of disease progression. BRMS1 methylation was detected in 15/27(55.6%) patients that relapsed and in 10/19(52.6%) of patients that died. BRMS1 promoter methylation was associated with reduced disease-free interval (P=0.009) while a trend towards a reduced overall survival (OS) was also observed (P=0.071). Expression of BRMS1 on CTC was very heterogeneous: CTC with high BRMS1 expression were found in 7/13(53.8%) CTC positive samples while exclusively CTC with high BRMS1 were found in only 3 patients (23.0%). CTC with low BRMS1 expression were found in 3 patients. CTC negative for BRMS1 were found in 8/13(61.5%) patients. Exclusively CTC with low or negative BRMS1-expression were identified in 6/13(46.1%) patients. 4/13(30.8%) patients had both high and low or negative BRMS1 expression in their CTC. Conclusions: BRMS1 promoter methylation provides important prognostic information for disease free survival in early breast cancer patients. BRMS1 promoter methylation and protein expression were evaluated in primary tumors and corresponding CTC for the first time. BRMS1 expression in CTC was heterogeneous in individual patient samples. CTC expressing epithelial markers but no BRMS1 seem to define a worse prognosis group of patients. These results need to be further evaluated and validated in a larger cohort of breast cancer patients. Citation Format: Maria Chimonidou, Galatea Kallergi, Vasilis Georgoulias, Danny Welch, Evi Lianidou. Prognostic significance of BRMS1 promoter methylation in operable breast cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-283. doi:10.1158/1538-7445.AM2013-LB-283