Abstract 361: ZNF24 may modulate microvascular endothelial cell invasion by regulating MMP2 transcription.

Abstract

Abstract ZNF24 is a C2H2 zinc finger transcription factor that regulates angiogenesis by repressing the transcription of vascular endothelial growth factor (VEGF). It has also been implicated in the control of cell proliferation and differentiation in the central nervous system and in hepatocellular carcinoma. In the current study, we have focused on the role of ZNF24 in modulating endothelial cell motility. We have found that silencing of ZNF24 in human microvascular endothelial cells (HMVEC) leads to significantly decreased cell migration and invasion. Consistently, the protein level and proteolytic activity of matrix metalloproteinase-2 (MMP2), but not those of matrix metalloproteinase-9 (MMP9), are significantly downregulated when ZNF24 is silenced in these cells. We have also determined the effect of ZNF24 silencing on the mRNA levels of endogenous inhibitors of MMPs, the tissue inhibitors of metalloproteinases (TIMPs). While TIMP1 and TIMP4 levels are moderately upregulated by ZNF24 silencing, the level of TIMP2, a major regulator of MMP2 proteolytic activity, and that of TIMP3, are significantly decreased. However, ZNF24 siRNA induces only a moderate decrease in the protein level of TIMP2, suggesting that TIMP2 does not play an important role in the regulation of MMP9 activity by ZNF24. Another major regulator of MMP2 proteolytic activity, membrane-type-1 matrix metalloproteinase (MT1-MMP), also does not exhibit significant changes when ZNF24 is silenced, suggesting that MMP2 is regulated by ZNF24 at the transcriptional level. Indeed, the mRNA level of MMP2 is significantly downregulated when cells are transfected with ZNF24 siRNA, indicating that ZNF24 positively regulates the transcription of MMP2. When compared to normal endothelial cells, tumor endothelial cells exhibit higher levels of endogenous ZNF24, suggesting that ZNF24 may function to increase cell invasion in these cells via upregulation of MMP2. Our current studies are focused on determining whether MMP2 is a direct downstream target of ZNF24 as well as on its role(s) in modulating endothelial cell motility in vivo. (Supported by NIH P01 CA045548, the Breast Cancer Research Foundation and the Advanced Medical Research Foundation) Citation Format: Di Jia, Marsha A. Moses. ZNF24 may modulate microvascular endothelial cell invasion by regulating MMP2 transcription. [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 361. doi:10.1158/1538-7445.AM2013-361