Downregulation of HtrA1 promotes resistance to anoikis and peritoneal dissemination of ovarian cancer cells.
Downregulation of HtrA1 promotes resistance to anoikis and peritoneal dissemination of ovarian cancer cells.
复制标题
DOI：
10.1158/0008-5472.can-09-3557
复制
发表时间：
2010-04-15
期刊：
影响因子：
11.2
通讯作者：
Shridhar V
中科院分区：
文献类型：
--
作者：
He X;Ota T;Liu P;Su C;Chien J;Shridhar V
我们之前发现丝氨酸蛋白酶HtrA1在上皮性卵巢癌（EOC）中是一个下调的基因，但在EOC中HtrA1缺失的功能后果仍不清楚。在这里，我们报道HtrA1的缺失减弱了anoikis -肿瘤转移的关键生理屏障。由于锚定缺失，SKOV3细胞中的HtrA1表达上调，导致HtrA1的自催化激活。在SKOV3和TOV21G细胞中，HtrA1的稳定敲低导致EGFR/AKT通路的激活增强，从而对anoikis产生抗性。在悬浮的SKOV3细胞中，HtrA1表达增强抑制EGFR/AKT通路，导致细胞死亡增加，而蛋白酶失活突变体HtrA1既不能抑制EGFR/AKT通路，也不能增加细胞死亡，提示HtrA1蛋白酶活性在调节anoikis中是必需的。免疫沉淀和免疫荧光分析显示，HtrA1不仅在细胞膜上与EGFR相互作用，而且在细胞核内也与EGFR相互作用。最重要的是，下调HtrA1显著增强了NOD/SCID小鼠中SKOV3ip1细胞的腹膜播散，与源自对照细胞的异种移植物相比，相应肿瘤结节中的p-EGFR水平升高。综上所述，这些数据首次揭示了HtrA1通过减弱EGFR/AKT通路的激活来促进anoikis的新功能，这可能有助于其抑制转移的能力，从而为HtrA1下调的人卵巢肿瘤的侵袭性提供了可能的解释。
We previously identified serine protease HtrA1 as a down-regulated gene in epithelial ovarian cancer (EOC), but the functional consequence of loss of HtrA1 in EOC remains largely unclear. Here, we report that loss of HtrA1 attenuates anoikis - a critical physiological barrier for tumor metastasis. In response to loss of anchorage, HtrA1 expression was up-regulated in SKOV3 cells, resulting in autocatalytic activation of HtrA1. Stable knockdown of HtrA1 in SKOV3 and TOV21G cells resulted in resistance to anoikis due to enhanced activation of EGFR/AKT pathway. In suspended SKOV3 cells, enhanced expression of HtrA1 inhibited EGFR/AKT pathway, leading to increased cell death, while protease inactive mutant HtrA1 failed to result in either the inhibition of EGFR/AKT pathway or increased cell death, suggesting the requirement of HtrA1 protease activity in regulating anoikis. Immunoprecipitation and immunofluorescence assays revealed that HtrA1 interacted with EGFR not only on the cell membrane but also in the nucleus. Most importantly, down-regulation of HtrA1 significantly enhanced the peritoneal dissemination of SKOV3ip1 cells in NOD/SCID mice, with increased p-EGFR level in corresponding tumor nodules compared to that in xenografts originated from the control cells. Taken together, these data reveal for the first time a novel function of HtrA1 in promoting anoikis by attenuating activation of EGFR/AKT pathway that may contribute to its metastasis suppression capacity, thus providing a possible explanation for the aggressive nature of human ovarian tumors with down-regulated HtrA1.