Abstract P2-07-07: Ehm2 Influences the Aggressiveness of Breast Cancer Cells through Regulation of MMP-9 Expression, and Aberrant Expression of Ehm2 Correlates with Disease Progression in Breast Cancer

Abstract

Abstract Background. Ehm2 is a member of NF2/ERM/4.1 superfamily and has been indicated in cell membrane/cytoskeletal interaction and cellular motility. In the present study, we investigated the expression pattern of Ehm2 in breast cancer and the impact of Ehm2 on the biological behavior of breast cancer cells. Methods. A cohort of breast cancer specimens (normal, n=33; cancer, n=127) was tested for Ehm2 expression, using both quantitative real time PCR and immunohistochemical staining. A hammerhead ribozyme transgene was employed to knockdown Ehm2 expression in breast cancer cells. The effect on growth, cell matrix adhesion, motility and invasion by Ehm2 knockdown was then examined using in vitro assays. Results. Immunohistochemical staining and quantitative real time PCR revealed an increased expression of Ehm2 in breast cancer. High levels of Ehm2 transcripts correlated with disease progression, metastasis and poor prognosis. Disease free survival of the patients with lower level of Ehm2 was 135.8 (125.1-146.5, 95%CI) months, significantly longer compared with 102.5 (78.7-126.4, 95%CI) months of patients with higher level of Ehm2 expression, P=0.039. Knockdown of Ehm2 had inhibitory effects on both in vitro growth and invasion of breast cancer cells. Flow cytometric analysis showed that knockdown of Ehm2 resulted in an increase (>10%) of apoptotic cells overthe control cells. Furthermore, it was shown that knockdown of Ehm2 significantly decreased the protein and mRNA expression of matrix metalloprotease MMP9. Zymograhpy revealed a reduced activity of MMP9 in breast cancer cells after knockdown of Ehm2. In conclusion, Ehm2 is able to promote invasion of cancer cells via regulating MMP9, and can also protect them from apoptosis. This may have important implication in the correlation between increased Ehm2 expression and poor prognosis and metastasis in breast cancer. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-07-07.