Caveolin-1 mutations (P132L and null) and the pathogenesis of breast cancer - Caveolin-1 (P132L) behaves in a dominant-negative manner and Caveolin-1 (-/-) null mice show mammary epithelial cell hyperplasia
Caveolin-1 mutations (P132L and null) and the pathogenesis of breast cancer - Caveolin-1 (P132L) behaves in a dominant-negative manner and Caveolin-1 (-/-) null mice show mammary epithelial cell hyperplasia
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DOI：
10.1016/s0002-9440(10)64412-4
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发表时间：
2002-10-01
影响因子：
6
通讯作者：
Lisanti, MP
中科院分区：
文献类型：
--
作者：
Lee, H;Park, DS;Lisanti, MP
Caveolin-1（Cav-1）是在大多数细胞类型（包括乳腺上皮细胞）中发现的小窝膜的主要结构蛋白。最近，我们将人CAV 1基因定位到一个疑似肿瘤抑制基因座（7q31.1/D 7S 522），该基因座在多种人类癌症以及乳腺肿瘤中缺失。此外，高达16%的人类乳腺癌中的CAV 1基因发生突变（P132 L）。Cav-1基因缺失或突变导致乳腺肿瘤发生的机制尚不清楚。为了了解Cav-1（P132 L）突变在人类乳腺癌发病机制中的作用，我们在野生型（WT）Cav-1中产生了相同的突变，并研究了其在培养细胞中的行为。有趣的是，P132 L突变导致形成错误折叠的Cav-1寡聚体，这些寡聚体保留在高尔基复合体内，并且不靶向小窝或质膜。为了检查Cav-1（P132 L）突变体是否以显性阴性方式表现，我们接下来用Cav-1（P132 L）和WT Cav-1共转染细胞，并评估它们的小窝靶向。我们的研究结果表明，Cav-1（P132 L）的行为在显性负性的方式，造成的错误定位和细胞内滞留的野生型Cav-1。当Cav-1（P132 L）在非转化的人乳腺上皮细胞系（hTERT-HME 1）中以生理水平稳定表达时，获得了几乎相同的结果。这些数据为为什么在乳腺癌患者中仅发现单个突变的CAV 1等位基因提供了分子解释。因此，我们接下来研究Cav-1基因表达的功能失活是否导致体内乳腺肿瘤发生。为此，我们对Cav-1缺陷小鼠（-/-）进行乳腺分析，这些小鼠携带Cav-1基因的靶向破坏（无效突变）。有趣是，我们发现Cav-1基因表达的失活导致乳腺上皮细胞增生，甚至在6周龄的处女雌性小鼠中也是如此。这些数据清楚地表明，在乳腺上皮细胞增生的发病机制中功能性Cav-1的丧失，并表明Cav-1缺失小鼠代表了一种新的动物模型，以研究癌前乳腺疾病。
Caveolin-1 (Cav-1) is the principal structural protein of caveolae membranes that are found in most cells types, including mammary epithelial cells. Recently, we mapped the human CAV1 gene to a suspected tumor suppressor locus (7q31.1/D7S522) that is deleted in a variety of human cancers, as well as mammary tumors. In addition, the CAV1 gene is mutated (P132L) in up to similar to16% of human breast cancers. The mechanism by which deletion or mutation of the Cav-1 gene contributes to mammary tumorigenesis remains unknown. To understand the role of the Cav-1 (P132L) mutation in the pathogenesis of human breast cancers, we generated the same mutation in wild-type (WT) Cav-1 and studied its behavior in cultured cells. Interestingly, the P132L mutation leads to formation of misfolded Cav-1 oligomers that are retained within the Golgi complex and are not targeted to caveolae or the plasma membrane. To examine whether the Cav-1 (P132L) mutant behaves in a dominant-negative manner, we next co-transfected cells with Cav-1 (P132L) and WT Cav-1, and evaluated their caveolar targeting. Our results indicate that Cav-1 (P132L) behaves in a dominant-negative manner, causing the mislocalization and intracellular retention of WT Cav-1. Virtually identical results were obtained when Cav-1 (P132L) was stably expressed at physiological levels in a nontransformed human mammary epithelial cell line (hTERT-HME1). These data provide a molecular explanation for why only a single mutated CAV1 allele is found in patients with breast cancer. Thus, we next investigated if functional inactivation of Cav-1 gene expression leads to mammary tumorigenesis in vivo. For this purpose, we performed mammary gland analysis on Cav-1-deficient mice (-/-) that harbor a targeted disruption of the Cav-1 gene (a null mutation). interestingly, we show that inactivation of Cav-1 gene expression leads to mammary epithelial cell hyperplasia, even in 6-week-old virgin female mice. These data clearly implicate loss of functional Cav-1 in the pathogenesis of mammary epithelial cell hyperplasia, and suggest that Cav-1-null mice represent a novel animal model to study premalignant mammary disease.