O'Neill Kathleen I, Kuo Li-Wei, Williams Michelle M, Lind Hanne, Crump Lyndsey S, Hammond Nia G, Spoelstra Nicole S, Caino M Cecilia, Richer Jennifer K
Department of Pathology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
Cancers (Basel). 2022 Jul 21;14(14):3543. doi: 10.3390/cancers14143543.
Triple-negative breast cancer (TNBC) often undergoes at least partial epithelial-to-mesenchymal transition (EMT) to facilitate metastasis. Identifying EMT-associated characteristics can reveal novel dependencies that may serve as therapeutic vulnerabilities in this aggressive breast cancer subtype. We found that , which encodes the lysosomal cholesterol transporter Niemann-Pick type C1 is highly expressed in TNBC as compared to estrogen receptor-positive (ER+) breast cancer, and is significantly elevated in high-grade disease. We demonstrated that is directly targeted by microRNA-200c (miR-200c), a potent suppressor of EMT, providing a mechanism for its differential expression in breast cancer subtypes. The silencing of in TNBC causes an accumulation of cholesterol-filled lysosomes, and drives decreased growth in soft agar and invasive capacity. Conversely, overexpression of NPC1 in an ER+ cell line increases invasion and growth in soft agar. We further identified TNBC cell lines as cholesterol auxotrophs, however, they do not solely depend on NPC1 for adequate cholesterol supply. The silencing of in TNBC cell lines led to altered mitochondrial function and morphology, suppression of mTOR signaling, and accumulation of autophagosomes. A small molecule inhibitor of NPC1, U18666A, decreased TNBC proliferation and synergized with the chemotherapeutic drug, paclitaxel. This work suggests that NPC1 promotes aggressive characteristics in TNBC, and identifies NPC1 as a potential therapeutic target.
三阴性乳腺癌（TNBC）常经历至少部分上皮-间质转化（EMT）以促进转移。识别与EMT相关的特征可揭示新的依赖性，这些依赖性可能成为这种侵袭性乳腺癌亚型的治疗靶点。我们发现，编码溶酶体胆固醇转运蛋白尼曼-匹克C1型（NPC1）的基因在TNBC中与雌激素受体阳性（ER+）乳腺癌相比高度表达，且在高级别疾病中显著升高。我们证明NPC1直接受微小RNA-200c（miR-200c，一种EMT的有效抑制剂）靶向，这为其在乳腺癌亚型中的差异表达提供了一种机制。在TNBC中沉默NPC1会导致充满胆固醇的溶酶体积累，并导致软琼脂中生长减少和侵袭能力下降。相反，在ER+细胞系中过表达NPC1会增加软琼脂中的侵袭和生长。我们进一步确定TNBC细胞系为胆固醇营养缺陷型，然而，它们并不完全依赖NPC1来获得充足的胆固醇供应。在TNBC细胞系中沉默NPC1会导致线粒体功能和形态改变、mTOR信号通路受抑制以及自噬体积累。NPC1的小分子抑制剂U18666A可降低TNBC增殖，并与化疗药物紫杉醇协同作用。这项工作表明NPC1促进TNBC的侵袭性特征，并将NPC1确定为一个潜在的治疗靶点。
