Department of Pathology, Barbara Ann Karmanos Cancer Center, Wayne State University School of Medicine, Detroit, MI 48201, USA.
Breast Cancer Res Treat. 2011 Feb;126(1):15-25. doi: 10.1007/s10549-010-0883-2. Epub 2010 Apr 9.
Platelet-derived growth factor-D (PDGF-D) has been linked with several human malignancies; however, its role in breast cancer progression is not known. We found that PDGF-D expressing breast cancer cell lines MDA-MB-231 and SUM-149 are more invasive compared to cell lines with little or no expression of PDGF-D such as MDA-MB-468 and MCF-7 cells. Over-expression of PDGF-D in PDGF-D low expressing MDA-MB-468 and MCF-7 cells by cDNA transfection showed increased cell proliferation while silencing the expression of PDGF-D by siRNA in PDGF-D high expressing MDA-MB-231 and SUM-149 cells showed decreased cell proliferation and increased apoptosis. Moreover, PDGF-D over-expression was positively correlated with the expression of Notch-1 and Jagged-1, and the expression of mesenchymal markers (Vimentin and ZEB-2) with concomitant decreased expression of epithelial marker E-cadherin. Since NF-κB activation plays a crucial role in Notch signaling as well as in epithelial-mesenchymal transition and tumor aggressiveness, we determined the DNA binding activity of NF-κB and our findings are consistent showing that PDGF-D over-expression led to increased DNA binding activity of NF-κB while it was found to be decreased by inactivation of PDGF-D. These results were also consistent with the expression and activity of MMP-9 and VEGF, as well as invasive characteristics. Further, forced expression of Notch-1/Jagged-1 by cDNA transfection de-repressed the effects of PDGF-D silencing on NF-κB activity and invasion. From these results, we conclude that PDGF-D plays an important role in breast tumor aggressiveness and this process is mechanistically linked with the activation of Notch and NF-κB signaling.
血小板衍生生长因子-D（PDGF-D）与多种人类恶性肿瘤有关；然而，其在乳腺癌进展中的作用尚不清楚。我们发现，与 PDGF-D 表达很少或没有的细胞系（如 MDA-MB-468 和 MCF-7 细胞）相比，表达 PDGF-D 的乳腺癌细胞系 MDA-MB-231 和 SUM-149 更具侵袭性。通过 cDNA 转染在 PDGF-D 低表达的 MDA-MB-468 和 MCF-7 细胞中过表达 PDGF-D 显示出细胞增殖增加，而在 PDGF-D 高表达的 MDA-MB-231 和 SUM-149 细胞中通过 siRNA 沉默 PDGF-D 的表达则显示出细胞增殖减少和凋亡增加。此外，PDGF-D 的过表达与 Notch-1 和 Jagged-1 的表达呈正相关，与上皮标志物 E-钙黏蛋白的表达呈负相关，同时与间充质标志物（波形蛋白和 ZEB-2）的表达呈正相关。由于 NF-κB 激活在 Notch 信号转导以及上皮-间充质转化和肿瘤侵袭性中起着至关重要的作用，我们确定了 NF-κB 的 DNA 结合活性，我们的研究结果一致表明，PDGF-D 的过表达导致 NF-κB 的 DNA 结合活性增加，而 PDGF-D 的失活则导致 NF-κB 的 DNA 结合活性降低。这些结果也与 MMP-9 和 VEGF 的表达和活性以及侵袭特性一致。此外，通过 cDNA 转染强制表达 Notch-1/Jagged-1 可逆转 PDGF-D 沉默对 NF-κB 活性和侵袭的影响。从这些结果中，我们得出结论，PDGF-D 在乳腺癌肿瘤侵袭性中起着重要作用，这一过程与 Notch 和 NF-κB 信号的激活在机制上相关。
