Jiang Lu, Chen Yongchang, Li Yueying, Lan Ting, Wu Min, Wang Ying, Qian Hai
Department of Physiology, School of Medical Science and Laboratory Medicine, Jiangsu University, Zhenjiang, Jiangsu 212013, P.R. China.
Mol Med Rep. 2014 Apr;9(4):1405-9. doi: 10.3892/mmr.2014.1942. Epub 2014 Feb 10.
Our previous data demonstrated that type II cGMP‑dependent protein kinase (PKG II) inhibited epidermal growth factor (EGF)-induced MAPK/ERK/JNK‑mediated signal transduction through inhibiting the phosphorylation/activation of the epidermal growth factor receptor (EGFR). Since the EGFR also binds with several other ligands as well as EGF, the present study was designed to investigate whether PKG II inhibited transforming growth factor-α (TGF-α), betacellulin (BTC) and epiregulin (EPR) induced phosphorylation/activation of the EGFR and consequent MAPK/ERK‑mediated signaling. The human gastric cancer cell line AGS, was infected with adenoviral constructs encoding cDNA of PKG II (Ad-PKG II) to increase the expression of PKG II and was treated with 8-pCPT-cGMP to activate the kinase. Western blotting was applied to detect the phosphorylation of EGFR and MAPK/ERK. The results demonstrated that treatment with EGF (100 ng/ml, 5 min), TGF-α (100 ng/ml, 5 min), BTC (100 ng/ml, 5 min) and EPR (100 ng/ml, 5 min) increased the tyrosine (tyr) 1068 phosphorylation of the EGFR and the threonine (thr) 202/tyr 204 phosphorylation of MAPK/ERK. Infecting the cells with Ad-PKG II and stimulating the kinase with 8-pCPT-cGMP efficiently inhibited the phosphorylation of the EGFR and MAPK/ERK induced by EGF, TGF-α, BTC and EPR. The results indicated that PKG II also inhibits the activation of the EGFR caused by diverse ligands of the receptor.
我们之前的数据表明，II型环磷酸鸟苷依赖性蛋白激酶（PKG II）通过抑制表皮生长因子受体（EGFR）的磷酸化/激活，抑制表皮生长因子（EGF）诱导的MAPK/ERK/JNK介导的信号转导。由于EGFR除了与EGF结合外，还与其他几种配体结合，因此本研究旨在探讨PKG II是否抑制转化生长因子-α（TGF-α）、β细胞素（BTC）和表皮调节素（EPR）诱导的EGFR磷酸化/激活以及随后的MAPK/ERK介导的信号传导。将人胃癌细胞系AGS用编码PKG II cDNA的腺病毒构建体（Ad-PKG II）感染以增加PKG II的表达，并用8-pCPT-cGMP处理以激活该激酶。采用蛋白质免疫印迹法检测EGFR和MAPK/ERK的磷酸化。结果表明，用EGF（100 ng/ml，5分钟）、TGF-α（100 ng/ml，5分钟）、BTC（100 ng/ml，5分钟）和EPR（100 ng/ml，5分钟）处理可增加EGFR的酪氨酸（tyr）1068磷酸化以及MAPK/ERK的苏氨酸（thr）202/酪氨酸（tyr）204磷酸化。用Ad-PKG II感染细胞并用8-pCPT-cGMP刺激激酶可有效抑制EGF、TGF-α、BTC和EPR诱导的EGFR和MAPK/ERK的磷酸化。结果表明，PKG II也抑制由该受体的多种配体引起的EGFR激活。
