Lewis Monica J, Liu Jianzhong, Libby Emily Falk, Lee Minnkyong, Crawford Nigel P S, Hurst Douglas R
Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, USA.
Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA.
Oncotarget. 2016 Nov 29;7(48):78713-78725. doi: 10.18632/oncotarget.12805.
SIN3 corepressor complexes play important roles in both normal development and breast cancer. Mammalian cells have two paralogs of SIN3 (SIN3A and SIN3B) that are encoded by distinct genes and have unique functions in many developmental processes. However, specific roles for SIN3A and SIN3B in breast cancer progression have not been characterized. We generated stable knockdown cells of SIN3 paralogs individually and in combination using three non-overlapping shRNA. Stable knockdown of SIN3B caused a significant decrease in transwell invasion through Matrigel and decreased the number of invasive colonies when grown in a 3D extracellular matrix. Conversely, stable knockdown of SIN3A significantly increased transwell invasion and increased the number of invasive colonies. These results were corroborated in vivo in which SIN3B knockdown significantly decreased and SIN3A knockdown increased experimental lung metastases. RNA sequencing was used to identify unique targets and biological pathways that were altered upon knockdown of SIN3A compared to SIN3B. Additionally, we analyzed microarray data sets to identify correlations of SIN3A and SIN3B expression with survival in patients with breast cancer. These data sets indicated that high mRNA expression of SIN3A as well as low mRNA expression of SIN3B correlates with longer relapse free survival specifically in patients with triple negative breast cancer which corresponds with our in vitro and in vivo data. These results demonstrate key functional differences between SIN3 paralogs in regulating the process of breast cancer metastasis and suggest metastasis suppressive roles of SIN3A and metastasis promoting roles of SIN3B.
SIN3共抑制复合物在正常发育和乳腺癌中均发挥重要作用。哺乳动物细胞中有两种SIN3旁系同源物（SIN3A和SIN3B），它们由不同基因编码，在许多发育过程中具有独特功能。然而，SIN3A和SIN3B在乳腺癌进展中的具体作用尚未明确。我们使用三种非重叠短发夹RNA（shRNA）分别或联合构建了SIN3旁系同源物的稳定敲低细胞系。稳定敲低SIN3B导致通过基质胶的Transwell侵袭显著减少，并且在三维细胞外基质中生长时侵袭集落数量减少。相反，稳定敲低SIN3A显著增加了Transwell侵袭并增加了侵袭集落数量。这些结果在体内得到了证实，其中敲低SIN3B显著减少了实验性肺转移，而敲低SIN3A则增加了实验性肺转移。RNA测序用于鉴定与敲低SIN3A相比敲低SIN3B时改变的独特靶点和生物学途径。此外，我们分析了微阵列数据集以确定SIN3A和SIN3B表达与乳腺癌患者生存率的相关性。这些数据集表明，SIN3A的高mRNA表达以及SIN3B的低mRNA表达与更长的无复发生存期相关，特别是在三阴性乳腺癌患者中，这与我们的体外和体内数据一致。这些结果证明了SIN3旁系同源物在调节乳腺癌转移过程中的关键功能差异，并表明SIN3A具有转移抑制作用，而SIN3B具有转移促进作用。
