Abstract 537: Molecular mechanisms that control the interactions between osteogenic-breast carcinoma cells

Abstract

Abstract Cancer cell and metastatic progression from primary site are predominantly influenced by signals that are derived from primary tumor stroma. SVEP1, a novel CAM molecule cloned in our laboratory, shares its expression in preosteoblastic and mammary carcinoma cells. SVEP1 was suggested to be involved in cell adhesion processes. It is crucial to learn its role in metastatic breast carcinoma, leading to bone niche, since SVEP1 can be a candidate for breast cancer cells homing to bone. We aim to understand molecular regulation of metastatic process and advance our knowledge about molecules that play a role in cell-cell interactions and homing of mammary carcinoma cells to specific sites. Bioinformatics tools were used to reveal putative promoter region of SVEP1 gene, potential transcriptional binding sites and to expand our knowledge about SVEP1 alternative spliced forms. SVEP1 promoter was cloned upstream to reporter gene and transiently tranfected for learning its transcriptional regulation. We detect specific transcription factors binding by Chromatin immunoprecipitation (ChIP). For identification of SVEP1 as an epigenetically silenced cancer-related gene cells will be treated with 5aza2'cytidine and/or trichostatin A, then SVEP1 gene expression will be examined by RT-PCR. 800bp upstream the TSS-SVEP1 promoter will be subjected to Methylation specific PCR (MSP) following different stimuli. Differential expression of SVEP1 spliced forms will be screened by RT-PCR using specific primers. Results: In transient transfection assays, TNFα and Estradiol increased SVEP1 promoter transcriptional activity. In ChIP assays TNFα enhanced ERα binding to SVEP1 promoter. These results were coincident with elevated SVEP1 full length mRNA expression following TNFα treatment. The 800bp upstream the TSS-SVEP1 promoter are transcriptionally regulated by DNA methylation. By using MSP this region was assessed to be highly methylated in DA3 cells, but less methylated in MBA15 cells. Methylation status of that region was regulated by TNF and Estrogen treatments. SVEP1 spliced forms expression pattern was characterized in preosteoblastic (MBA15) versus mammary carcinoma cells (DA3). Conclusions: Cell-cell contacts require engagement of adhesion factors yet to be determined. SVEP1, a novel CAM molecule, was suggested to be involved in cell adhesion processes. It is crucial to learn its role in metastatic breast carcinoma, leading to bone, since SVEP1 can be candidate for breast cancer cells homing to bone. Characterization of SVEP1 expression that participates in initial cell adhesion process is of prime interest. SVEP1's role in bone microenvironment may be important in creating an interactive network that regulates skeletal cells. Further research of SVEP1 expression regulation will help to understand its role as a mediator of interactions between normal and tumorogenic cells within bone marrow microenvironment. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 537.