Shanghai Jiao Tong University Affiliated International Peace Maternal and Child Health Hospital, Shanghai, People's Republic of China.
Int J Gynecol Cancer. 2011 Nov;21(8):1357-65. doi: 10.1097/IGC.0b013e3182216ac9.
The objectives of the study were to evaluate the role of mitogen-activated protein kinase (MAPK) signaling in normal, hyperplastic, and neoplastic endometrium in relation to estrogen receptor (ER) status and to investigate whether 17β-estradiol (E2) and tamoxifen (TAM) mediate the proliferation and apoptosis of endometrial cancer cells through the MAPK pathway.
The expressions of phosphorylated and total extracellular signal-regulated kinases 1/2 (phosphorylated extracellular signal-regulated kinase 1/2 [p-ERK1/2] and total ERK1/2 [t-ERK1/2]) were analyzed with immunohistochemistry in normal, hyperplastic, and neoplastic endometrium. The expression levels of p-ERK1/2 and t-ERK1/2 in RL95-2 and KLE after stimulation by E2, progesterone (P), and TAM were detected by Western blotting. The effects of E2 and TAM in combination with MAPK pathway inhibitors on the growth and apoptosis of endometrial cancer cells were examined by the MTS assay and flow cytometry analysis.
The expression level of p-ERK1/2 was significantly associated with the International Federation of Gynecology and Obstetrics stage (P = 0.0072). The ratio of phosphorylated/total ERK1/2 was higher in ER-positive endometrial cancer tissues and cells (P < 0.05). 17β-Estradiol increased ERK1/2 phosphorylation, and TAM decreased ERK1/2 phosphorylation in endometrial cancer cell lines within 30 minutes (P < 0.05). The MEK1/2 inhibitor, U0126, and the stress-activated protein kinase/c-Jun NH2-terminal kinase inhibitor, SP600125, significantly suppressed the proliferation of human endometrial cancer cell lines RL95-2 and KLE induced by E2 (P < 0.05). The level of TAM-induced apoptosis was greater in KLE than in RL95-2 cells, and the p38 cascade was involved in the TAM-induced apoptosis of both cell lines (P < 0.05).
The cross-talk between MAPK signaling and ER status might exert a key role in progression of endometrial cancer. Furthermore, the effects of E2 or TAM on the proliferation or apoptosis of ER-positive and ER-negative endometrial cancer cells were mediated through distinct MAPK pathways. These mechanisms might contribute to ER-specific differences in MAPK activation for molecular-target therapies in endometrial carcinoma.
本研究旨在评估丝裂原活化蛋白激酶（MAPK）信号通路在雌激素受体（ER）状态相关的正常、增生和癌变子宫内膜中的作用，并探讨 17β-雌二醇（E2）和他莫昔芬（TAM）是否通过 MAPK 通路介导子宫内膜癌细胞的增殖和凋亡。
采用免疫组织化学法检测正常、增生和癌变子宫内膜中磷酸化和总细胞外信号调节激酶 1/2（磷酸化细胞外信号调节激酶 1/2 [p-ERK1/2]和总 ERK1/2 [t-ERK1/2]）的表达。用 Western blot 法检测 E2、孕激素（P）和 TAM 刺激 RL95-2 和 KLE 后 p-ERK1/2 和 t-ERK1/2 的表达水平。通过 MTS 检测和流式细胞术分析，研究 E2 和 TAM 与 MAPK 通路抑制剂联合对子宫内膜癌细胞生长和凋亡的影响。
p-ERK1/2 的表达水平与国际妇产科联合会（FIGO）分期显著相关（P = 0.0072）。ER 阳性子宫内膜癌组织和细胞中磷酸化/总 ERK1/2 比值较高（P < 0.05）。E2 在 30 分钟内增加了子宫内膜癌细胞系中 ERK1/2 的磷酸化，而 TAM 则降低了 ERK1/2 的磷酸化（P < 0.05）。MEK1/2 抑制剂 U0126 和应激激活蛋白激酶/c-Jun NH2-末端激酶抑制剂 SP600125 显著抑制了 E2 诱导的人子宫内膜癌细胞系 RL95-2 和 KLE 的增殖（P < 0.05）。与 RL95-2 细胞相比，TAM 诱导 KLE 细胞凋亡的水平更高，p38 级联反应参与了两种细胞系的 TAM 诱导凋亡（P < 0.05）。
MAPK 信号通路与 ER 状态之间的相互作用可能在子宫内膜癌的进展中发挥关键作用。此外，E2 或 TAM 对 ER 阳性和 ER 阴性子宫内膜癌细胞的增殖或凋亡的影响是通过不同的 MAPK 通路介导的。这些机制可能有助于 ER 特异性差异在子宫内膜癌的分子靶向治疗中的 MAPK 激活。
