Abstract P5-04-16: Extracellular matrix 1 (ECM1) knockdown alters cellular characteristics, CD44 expression and other metastasis associated genes in breast cancer cells

Abstract

Abstract Introduction: ECM1 is known to be over-expressed in multiple tumor cell lines and primary tumors, including breast cancers. ECM1 overexpression is also an independent predictor of poor prognosis in primary breast carcinomas. While similar associations have also been reported in other tumors, the mechanisms by which ECM1 affects prognosis have not been elucidated. Methods: ECM1 was silenced in the Hs578t and MDA-MB231 breast cancer cell lines using siRNA. The cells were evaluated for morphological changes, migration (wound-healing assay, TScratch program), matrigel invasion and cell attachment. Real Time RT-PCR using a 94-geneTumor Metastasis Array (TaqMan), was performed to assess the effects of ECM1 downregulation on in Hs578t cells. Alterations in RNA expression were validated at the protein level using western blots. Differences between groups were evaluated using the student's t-test and p<0.05 was considered statistically significant. Results: ECM1 silenced cells demonstrated altered morphology with a more elongated appearance to the cells, when compared those transfected with non-targeting siRNA. Reduced cell migration was noted for both silenced Hs578t and MB231 cell lines (both p<0.0001). Matrigel invasion was reduced in the Hs578t cell line only (p<0.002). however, cell attachment was decreased in both cell lines. (p <0.0001 for Hs578t, and < 0.01 for MB231). ECM1 downregulation affected the expression of several metastasis associated genes including CD44, Metalloproteinase-2, fibronectin at the RNA level. CD44 expression was significantly reduced in ECM1-silenced cells by western blot. Conclusion: ECM1 appears to be involved in maintenance of tumor cell shape, migration, invasion and attachment properties in the cell lines tested, and also affects expression of CD44 protein, a known tumor prognostic factor. ECM1 may be a key molecule affecting tumor progression and metastasis, which is a complex process involving these components. Our findings suggest mechanisms by which ECM1 overexpression may affect tumor prognosis. Further work is needed to evaluate if altering ECM1 expression may be a novel therapeutic option for these tumors. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-04-16.