Autophagy positively regulates the CD44+CD24-/low breast cancer stem-like phenotype
Autophagy positively regulates the CD44+CD24-/low breast cancer stem-like phenotype
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DOI：
10.4161/cc.10.22.17976
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发表时间：
2011-11-15
期刊：
影响因子：
4.3
通讯作者：
Menendez, Javier A.
中科院分区：
文献类型：
--
作者：
Cufi, Silvia;Vazquez-Martin, Alejandro;Menendez, Javier A.
乳腺癌干细胞（BCSC）存活和/或维持其未分化的CD 44（+）CD 24（-/低）间充质样抗原状态的分子机制在很大程度上尚未探索。自噬是细胞质降解和循环的一个关键稳态过程，进化以应对应激条件，可能是BCSCs生物学的基础。通过慢病毒递送的小发夹（sh）RNA稳定和特异性敲低自噬调控基因，显著降低了携带CD 44（+）CD 24（-/低）细胞表面抗原的JIMT-1上皮BC细胞的数量，从亲本和对照（-）shRNA转导细胞中的75%分别降至ATG 8/LC 3 shRNA和ATG 12 shRNA转导细胞中的26%和7%。自噬抑制显著增强了CD 24基因的转录激活，增强了CD 44（+）CD 24（+）细胞与间充质CD 44（+）CD 24（-/低）后代的上皮样表型。EMT聚焦的真实的时间RT-PCR分析显示，自噬的基因消融转录抑制了间充质丝波形蛋白（Vim）的基因编码。shRNA驱动的ATG 12基因沉默和抗疟疾药物氯喹使自噬途径的最后一步失效都阻止了TGF β 1诱导的JIMT-1细胞中波形蛋白的积累。自噬特异性基因的敲低也足以使MDA-MB-231细胞中的CD 24（+）细胞数量增加多达11倍，MDA-MB-231细胞是一种间充质来源的BC模型，实际上由CD 44（+）CD 24（-/低）细胞组成。氯喹处理增加了CD 24（+）细胞的数量，同时减少了波形蛋白在MDA-MB-231细胞中的组成性过表达。这是第一份证明自噬与维持表达高水平CD 44和低水平CD 24的肿瘤细胞（BCSC的典型特征）的机制相关的报告。
The molecular mechanisms used by breast cancer stem cells (BCSCs) to survive and/or maintain their undifferentiated CD44(+)CD24(-/low) mesenchymal-like antigenic state remain largely unexplored. Autophagy, a key homeostatic process of cytoplasmic degradation and recycling evolved to respond to stress conditions, might be causally fundamental in the biology of BCSCs. Stable and specific knockdown of autophagy-regulatory genes by lentiviral-delivered small hairpin (sh) RNA drastically decreased the number of JIMT-1 epithelial BC cells bearing CD44(+)CD24(-/low) cell-surface antigens from similar to 75% in parental and control (-) shRNA-transduced cells to 26% and 7% in ATG8/LC3 shRNA-and ATG12 shRNA-transduced cells, respectively. Autophagy inhibition notably enhanced transcriptional activation of CD24 gene, potentiating the epithelial-like phenotype of CD44(+)CD24(+) cells vs. the mesenchymal CD44(+)CD24(-/low) progeny. EMT-focused Real Time RT-PCR profiling revealed that genetic ablation of autophagy transcriptionally repressed the gene coding for the mesenchymal filament vimentin (VIM). shRNA-driven silencing of the ATG12 gene and disabling the final step in the autophagy pathway by the antimalarial drug chloroquine both prevented TGF beta 1-induced accumulation of vimentin in JIMT-1 cells. Knockdown of autophagy-specific genes was sufficient also to increase by up to 11-times the number of CD24(+) cells in MDA-MB-231 cells, a BC model of mesenchymal origin that is virtually composed of CD44(+)CD24(-/low) cells. Chloroquine treatment augmented the number of CD24(+) cells and concomitantly reduced constitutive overexpression of vimentin in MDA-MB-231 cells. This is the first report demonstrating that autophagy is mechanistically linked to the maintenance of tumor cells expressing high levels of CD44 and low levels of CD24, which are typical of BCSCs.