Invasive ability of human renal cell carcinoma cell line Caki-2 is accelerated by gamma-aminobutyric acid, via sustained activation of ERK1/2 inducible matrix metalloproteinases
Invasive ability of human renal cell carcinoma cell line Caki-2 is accelerated by gamma-aminobutyric acid, via sustained activation of ERK1/2 inducible matrix metalloproteinases
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DOI：
10.1080/07357900701522471
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发表时间：
2007-11-01
影响因子：
2.4
通讯作者：
Katsuoka, Yoji
中科院分区：
文献类型：
--
作者：
Inamoto, Teruo;Azuma, Haruhito;Katsuoka, Yoji
γ-氨基丁酸(GABA)最先被发现是中枢神经系统(CNS)中的一种抑制性神经递质，已被报道具有多种功能，包括调节细胞分裂、细胞分化和成熟，并参与中枢神经系统以外的某些癌症的发生。在本研究中，我们利用人肾细胞癌细胞系Caki-2，证明了GABA刺激显著增加了基质金属蛋白酶-2和-9的表达，从而增加了癌细胞的侵袭活性。由于MAPK信号是基质金属蛋白酶表达的关键调节因子之一，我们进一步研究了GABA刺激后的MAPK信号转导。结果发现，GABA刺激促进了MAPKs的磷酸化，包括ERK1/2、JNK和p38。ERK1/2的磷酸化持续到12h，而JNK和p38的磷酸化在30min时恢复到内源性水平。值得注意的是，ras/RAF/MEK/ERK通路抑制剂PD98059可减弱GABA诱导的MMP9的表达，而PD98059和MMP2抑制剂均可减弱GABA诱导的CAKI-2细胞的侵袭活性。此外，通过干扰RNA转染法耗尽MEK/ERK通路获得的数据清楚地证实了上述结果，因为MMP9的表达和GABA诱导的侵袭能力都显著降低。我们还证明，GABA通过上调ERK1/2诱导的侵袭能力的增加主要是通过GABA-B受体介导的。这些结果表明，GABA刺激促进癌细胞侵袭，其作用部分是由于ERK1/2依赖的MMPs上调所致。
Gamma-aminobutyric acid (GABA) was first discovered as an inhibitory neurotransmitter in the central nervous system (CNS) and has been reported to have a variety of functions, including regulation of cell division, cell differentiation and maturation, and to be involved in the development of certain cancers outside the CNS. In the present study, using the human renal cell carcinoma cell line Caki-2, we demonstrated that GABA stimulation significantly increased the expression of MMP-2 and -9 and subsequently increased the invasive activity of the cancer cells. Because MAPK signaling is one of the key regulators of MMP expression, we further evaluated MAPK signaling after stimulation with GABA. It was found that GABA stimulation promoted the phosphorylation of MAPKs, including ERK1/2, JNK, and p38. ERK1/2 phosphorylation was sustained for up to 12 h, while phosphorylation of JNK and p38 returned to the endogenous level by 30 min. It was noteworthy that the ras/raf/MEK/ERK pathway inhibitor PD98059 attenuated GABA-induced MMP-9 expression and that both PD98059 and MMP inhibitors attenuated the GABA-induced invasive activity of Caki-2 cells. Moreover, data obtained by depletion of the MEK/ERK pathway using interfering RNA transfection of Caki-2 cells clearly corroborated the above results, as both MMP-9 expression and GABA-induced invasive ability were decreased significantly. We also demonstrated that the GABA-induced increase in invasive ability via ERK1/2 up-regulation was mediated mainly through the GABA-B receptor. These results indicate that GABA stimulation promotes cancer cell invasion and that the effect is partly due to ERK1/2-dependent up-regulation of MMPs.