P2Y嘌呤受体活化的PI-3K信号通路在前列腺癌细胞生长和侵袭中的作用

目的研究P2Y嘌呤受体激动剂对前列腺癌细胞PI-3K信号通路的激活及对肿瘤细胞生长和侵袭的影响。方法以高转移的人前列腺癌细胞系1E8为研究对象,以Western blot法,用特异性识别磷酸化Akt的抗体检测PI-3K信号通路的活化情况;以细胞计数、流式细胞术、Matrigel侵袭实验等方法检测P2Y受体激活的PI-3K／Akt信号通路在前列腺癌细胞生长和侵袭中的作用。结果P2Y嘌呤受体激动剂以时间和剂量依赖的方式激活了1E8细胞中的PI-3K／Akt信号通路。其持续刺激导致的生长抑制作用主要通过将细胞阻滞在S期实现（刺激组S期细胞分数比对照组提高22．3％）。应用特异性抑制剂LY294002阻断PI-3K通路明显影响1E8细胞的生长,但不能逆转P2Y受体介导的生长抑制作用。P2Y受体瞬时激活对前列腺癌细胞体外侵袭的促进作用主要通过增强细胞的运动能力（刺激组划痕修复率比对照组提高21．2％）,而非提高基质金属蛋白酶（MMP）-2和MMP-9的酶解活性实现,且此促侵袭作用可被LY294002明显抑制。结论P2Y嘌呤受体可以激活人前列腺癌细胞的PI．3K信号通路,并通过这条通路促进肿瘤细胞的运动能力进而促进侵袭;该通路是前列腺癌细胞生长的重要调节通路,但不参与P2Y嘌呤受体对前列腺癌细胞生长抑制的调节。

P2Y purinergic receptor activated PI-3K/Akt signaling pathway in regulation of growth and invasion of prostatic cancer

OBJECTIVE: To investigate P2Y purinergic receptor activated PI-3K/Akt signaling pathway in the regulation of growth and invasion of prostate cancer in vitro. METHODS: Western blot was used to detect phosphorylation of Akt (a downstream target molecule of PI-3K) by P2Y receptor agonist in 1E8 cells (a highly metastatic subclone derived from PC-3 prostatic cancer cell line). Cell counts, flow cytometry, Matrigel invasion assay, wound healing assay and gelatin zymography were used to detect changes of biological behaviors of 1E8 cells after P2Y receptor activation. RESULTS: AMP-PNP, one non-hydrolysis ATP analogue and P2Y receptor agonist, induced significant phosphorylation of Akt in a time- and dose-dependent manner in IE8 cells. LY294002, a specific inhibitor of PI-3K, effectively blocked Akt phosphorylation induced by AMP-PNP. Continuous exposure to AMP-PNP induced significant growth inhibition of 1E8 cells (inhibition rate at 50.2% at the 8th day), and this inhibition was mainly due to an arrest at S phase of the cell cycle (the S phase fraction of AMP-PNP treated cells was 22.3% higher than that of the control). Application of LY294002 did not reverse the growth inhibition effect of AMP-PNP. Matrigel invasion assay showed that AMP-PNP stimulation increased invasive ability of 1E8 cells, and this effect was effectively blocked by LY294002. No significant changes in the activation of MMP-2 and MMP-9 were detected by gelatin zymography, although wound healing assay showed 21.2% increase in cell migration after AMP-PNP treatment. CONCLUSIONS: PI-3K/Akt signaling pathway participates in P2Y receptor-stimulated prostate cancer invasion by enhancing cell motility, rather than up-regulating MMP-2 and MMP-9 activities. PI-3K signaling pathway plays an important role in prostate cancer proliferation, but is not involved in P2Y receptor mediated growth inhibition.