The cross talk between protein kinase A- and RhoA-mediated signaling in cancer cells
The cross talk between protein kinase A- and RhoA-mediated signaling in cancer cells
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DOI：
10.1177/153537020523001006
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发表时间：
2005-11-01
影响因子：
3.2
通讯作者：
Xu, WR
中科院分区：
文献类型：
--
作者：
Chen, YC;Wang, Y;Xu, WR
研究了环磷酸腺苷（cAMP）/蛋白激酶A（PKA）与RhoA介导的信号转导之间的相互作用及其对人前列腺癌和胃癌细胞生物学特性的影响。在人胃癌细胞系SGC-7901中，溶血磷脂酸（LPA）以剂量依赖性方式增加RhoA活性。细胞渗透性cAMP类似物8-氯苯硫基-cAMP（CPT-cAMP）可抑制LPA诱导的RhoA活化，并导致RhoA在丝氨酸处磷酸化（188）。免疫荧光显微镜、Western blotting和绿色荧光蛋白（GFP）标记的RhoA活细胞定位分析显示，RhoA分布于SGC-7901细胞的胞质和胞核中。LPA和/或CPT-cAMP处理均未引起RhoA明显移位。LPA处理可诱导SGC-7901细胞形成F-actin，而CPT-cAMP可抑制F-actin的形成。在改良Boyden小室实验中，LPA刺激SGC-7901细胞迁移，CPT-cAMP剂量依赖性地抑制LPA的刺激作用。在软琼脂实验中，LPA促进了SGC-7901细胞的早期增殖，CPT-cAMP显著抑制了LPA刺激的细胞生长。在前列腺癌细胞系PC-3中，LPA引起从多边形到圆形的形态学变化，并且用编码组成型活性RhoA（63 L）的质粒DNA转染引起类似的变化。CPT-cAMP治疗抑制了这两种情况下的变化。然而，在PC-3细胞转染编码突变体RhoA 188 A的质粒，LPA诱导变圆，但CPT-cAMP不能阻止的变化。实验结果表明，cAMP/PKA抑制RhoA的活化，而RhoA上的丝氨酸（188）磷酸化是PKA发挥其抑制RhoA活化作用所必需的。cAMP/PKA和RhoA介导的信号转导之间的相互作用对胃癌和前列腺癌细胞的生物学特性，如形态和细胞骨架的改变、迁移和非贴壁依赖性生长等有显著影响。这些结果可能有助于实施侵袭性和转移性前列腺癌和胃癌的新治疗策略。
The Cross talk between cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) and RhoA-mediated signal transductions and the effect of this cross talk on biologic features of human prostate and gastric cancer cells were investigated. In the human gastric cancer cell line, SGC-7901, lysophosphatidic acid (LPA) increased RhoA activity in a dose-dependent manner. The cellular permeable CAMP analog, 8-chlorophenylthio-cAMP (CPT-cAMP), inhibited the LPA-induced RhoA activation and caused phosphorylation of RhoA at serine(188). Immunofluorescence microscopy, Western blotting, and green fluorescent protein (GFP)-tagged RhoA location assay in live cells revealed that RhoA was distributed in both the cytoplasm and nucleus of SGC-7901 cells. Treatment with LPA and/or CPT-cAMP did not induce obvious translocation of RhoA in the cells. The LPA treatment caused formation of F-actin in SGC-7901 cells, and CPT-cAMP inhibited the formation. In a modified Boyden chamber assay, LPA stimulated the migration of SGC-7901 cells, and CPT-cAMP dose-dependently inhibited the stimulating effect of LPA. In soft agar assay, LPA stimulated early proliferation of SGC-7901 cells, and CPT-cAMP significantly inhibited the growth of LPA-stimulated cells. In the prostate cancer cell line, PC-3, LPA caused morphologic changes from polygonal to round, and transfection with plasmid DNA encoding constitutively active RhoA(63L) caused a similar change. Treatment with CPT-cAMP inhibited the changes in both cases. However, in PC-3 cells transfected with a plasmid encoding mutant RhoA188A, LPA induced rounding, but CPT-cAMP could not prevent the change. Results of this experiment indicated that cAMP/PKA inhibited RhoA activation, and serine(188) phosphorylation on RhoA was necessary for PKA to exert its inhibitory effect on RhoA activation. The cross talk between cAMP/PKA and RhoA-mediated signal transductions had significant affect on biologic features of gastric and prostate cancer cells, such as morphologic and cytoskeletal change, migration, and anchorage-independent growth. The results may be helpful in implementing novel therapeutic strategies for invasive and metastatic prostate and gastric cancers.