Memmi Elisa Maria, Sanarico Anna Giulia, Giacobbe Arianna, Peschiaroli Angelo, Frezza Valentina, Cicalese Angelo, Pisati Federica, Tosoni Daniela, Zhou Huiqing, Tonon Giovanni, Antonov Alexey, Melino Gerry, Pelicci Pier Giuseppe, Bernassola Francesca
Biochemistry Laboratory, Istituto Dermopatico dell'Immacolata, Istituto di Ricovero e Cura a Carattere Scientifico, Department of Experimental Medicine and Surgery, University of Rome "Tor Vergata," 00133 Rome, Italy;
Department of Biochemical Sciences, Institute of Cellular Biology and Neurobiology, Consiglio Nazionale delle Ricerche, 00015 Rome, Italy;
Proc Natl Acad Sci U S A. 2015 Mar 17;112(11):3499-504. doi: 10.1073/pnas.1500762112. Epub 2015 Mar 4.
The predominant p63 isoform, ΔNp63, is a master regulator of normal epithelial stem cell (SC) maintenance. However, in vivo evidence of the regulation of cancer stem cell (CSC) properties by p63 is still limited. Here, we exploit the transgenic MMTV-ErbB2 (v-erb-b2 avian erythroblastic leukemia viral oncogene homolog 2) mouse model of carcinogenesis to dissect the role of p63 in the regulation of mammary CSC self-renewal and breast tumorigenesis. ErbB2 tumor cells enriched for SC-like properties display increased levels of ΔNp63 expression compared with normal mammary progenitors. Down-regulation of p63 in ErbB2 mammospheres markedly restricts self-renewal and expansion of CSCs, and this action is fully independent of p53. Furthermore, transplantation of ErbB2 progenitors expressing shRNAs against p63 into the mammary fat pads of syngeneic mice delays tumor growth in vivo. p63 knockdown in ErbB2 progenitors diminishes the expression of genes encoding components of the Sonic Hedgehog (Hh) signaling pathway, a driver of mammary SC self-renewal. Remarkably, p63 regulates the expression of Sonic Hedgehog (Shh), GLI family zinc finger 2 (Gli2), and Patched1 (Ptch1) genes by directly binding to their gene regulatory regions, and eventually contributes to pathway activation. Collectively, these studies highlight the importance of p63 in maintaining the self-renewal potential of mammary CSCs via a positive modulation of the Hh signaling pathway.
主要的p63亚型ΔNp63是正常上皮干细胞（SC）维持的主要调节因子。然而，p63对癌症干细胞（CSC）特性调控的体内证据仍然有限。在此，我们利用致癌作用的转基因MMTV-ErbB2（v-erb-b2禽成红细胞白血病病毒癌基因同源物2）小鼠模型来剖析p63在乳腺CSC自我更新调节和乳腺肿瘤发生中的作用。与正常乳腺祖细胞相比，富含SC样特性的ErbB2肿瘤细胞显示出更高水平的ΔNp63表达。在ErbB2乳腺球中下调p63可显著限制CSC的自我更新和扩增，并且这种作用完全独立于p53。此外，将表达针对p63的shRNA的ErbB2祖细胞移植到同基因小鼠的乳腺脂肪垫中可在体内延迟肿瘤生长。在ErbB2祖细胞中敲低p63会降低编码Sonic Hedgehog（Hh）信号通路成分的基因的表达，Hh信号通路是乳腺SC自我更新的驱动因素。值得注意的是，p63通过直接结合其基因调控区域来调节Sonic Hedgehog（Shh）、GLI家族锌指2（Gli2）和Patched1（Ptch1）基因的表达，并最终促进通路激活。总的来说，这些研究突出了p63通过对Hh信号通路的正向调节在维持乳腺CSC自我更新潜能中的重要性。
