Thromboxane A2 receptors in prostate carcinoma:: expression and its role in regulating cell motility via small GTPase Rho
Thromboxane A2 receptors in prostate carcinoma:: expression and its role in regulating cell motility via small GTPase Rho
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DOI：
10.1158/0008-5472.can-07-1018
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发表时间：
2008-01-01
期刊：
影响因子：
11.2
通讯作者：
Honn, Kenneth V.
中科院分区：
文献类型：
--
作者：
Nie, Daotai;Guo, Yande;Honn, Kenneth V.
血栓烷A（2）（TxA（2））是血栓烷合成酶以环氧合酶产物前列腺素H-2为底物形成的前列腺素类化合物。以前，在前列腺肿瘤中发现血栓素合酶表达增加，血栓素合酶抑制剂可减弱肿瘤细胞运动。本研究旨在阐明TxA 2如何调控肿瘤运动。在这里，我们报告，人前列腺癌细胞表达TxA（2）（TP）的功能性受体。配体结合实验发现，PC-3细胞与高亲和力TP拮抗剂SQ 29548的结合是饱和的，Kd为3.64 nmol/L，Bmax为120.4 fmol/百万细胞。用TP激动剂U46619处理PC-3细胞，可引起PC-3细胞收缩，用TP拮抗剂SQ 29548或pinane TxA 2预处理可阻断该收缩。前列腺癌细胞的迁移显着抑制持续激活TP或TP激活的封锁，表明TP激活必须严格控制在细胞迁移。进一步的研究发现，TP激活可激活小G蛋白RhoA，用Rho激酶（ROCK）抑制剂Y27632预处理PC-3细胞可阻断U46619诱导的细胞收缩。RhoA的显性阴性突变体也阻断了U46619诱导的细胞收缩。总之，数据表明TP在前列腺癌中表达，TP的活化通过Rho的活化调节前列腺癌细胞运动性和细胞骨架重组。
Thromboxane A(2) (TxA(2)) is a prostanoid formed by thromboxane synthase using the cyclooxygenase product prostaglandin H-2 as the substrate. Previously, increased expression of thromboxane synthase was found in prostate tumors, and tumor cell motility was attenuated by inhibitors of thromboxane synthase. This study was undertaken to elucidate how tumor motility is regulated by TxA2. Here, we report that human prostate cancer cells express functional receptors for TxA(2) (TP). Ligand binding assay found that PC-3 cells binded to SQ29548, a high-affinity TP antagonist, in a saturable manner with K-d of 3.64 nmol/L and B-max of 120.4 fmol per million cells. Treatment of PC-3 cells by U46619, a TP agonist, induced PC-3 cell contraction, which was blocked by pretreatment with the TP antagonist SQ29548 or pinane TxA2. The migration of prostate cancer cells was significantly inhibited either by sustained activation of TP or by blockade of TP activation, suggesting that TP activation must be tightly controlled during cell migration. Further studies found that small GTPase RhoA was activated by TP activation, and pretreatment of PC-3 cells with Y27632, a Rho kinase (ROCK) inhibitor, blocked U46619-induced cell contraction. A dominant-negative mutant of RhoA also blocked U46619-induced cell contraction. Taken together, the data suggest that TPs are expressed in prostate cancer and activation of TPs regulates prostate cancer cell motility and cytoskeleton reorganization through activation of Rho.