K-Ras and H-Ras activation promote distinct consequences on endometrial cell survival
K-Ras and H-Ras activation promote distinct consequences on endometrial cell survival
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DOI：
10.1158/0008-5472.can-3487-2
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发表时间：
2004-04-15
期刊：
影响因子：
11.2
通讯作者：
Wake, N
中科院分区：
文献类型：
--
作者：
Ninomiya, Y;Kato, K;Wake, N
大量证据表明Ras信号传导有助于子宫内膜癌的发生。我们之前证明携带致癌[(12)Val]K-ras 的子宫内膜癌细胞容易发生细胞凋亡。本研究利用大鼠子宫内膜细胞（RENT4 细胞）检验了 K-Ras 和 H-Ras 在诱导细胞凋亡中的作用。我们发现组成型激活的 K-Ras 促进细胞凋亡，而 H-Ras 突变体则挽救了大鼠子宫内膜细胞的凋亡。 Raf-1 (Raf-CAAX) 的组成型活性形式的表达促进细胞凋亡，而磷酸肌醇 3-激酶的组成型活性催化亚基 p110K227E 的表达使细胞逃避凋亡。此外，特异性抑制剂 UO126 对 MEK-MAPK 通路的抑制可挽救细胞免于凋亡，而其特异性抑制剂 LY294002 对磷酸肌醇 3-激酶的抑制可促进表达活化 K-Ras 的 RENT4 细胞凋亡。然而，两种抑制剂均促进表达活化 H-Ras 的 RENT4 细胞凋亡。 K-Ras 和 H-Ras 表达细胞之间 MEK 抑制剂对细胞凋亡调节的差异取决于每种 Ras 亚型下游效应蛋白的相互作用。最后。为了阐明下游 K-Ras 信号通路的作用，我们生成了 K-Ras 效应结构域突变体（K12V35S、K12V40C）。我们检查了 K-Ras 效应结构域突变体（K12V35S、K12V40C）诱导的细胞凋亡的发生率。与模拟细胞相比，K12V35S 细胞中磷酸-MAPK 与磷酸-Akt 的相对比率高于 K12V40C 细胞。 K12V35S蛋白的异位表达增加了凋亡细胞的比例，反过来，与没有效应结构域突变体的K12V蛋白的表达相比，K12V40C蛋白的表达减少。这些结果表明，K-和 H-Ras 介导的信号通路对细胞凋亡具有不同的影响，并且 K-Ras 下游 Raf/MEK/MAPK 通路是诱导子宫内膜细胞凋亡所必需的。两条途径的协调有助于子宫内膜细胞的存活。
A considerable amount of evidence indicates that Ras signaling contributes to the development of endometrial cancer. We previously demonstrated that endometrial cancer cells carrying oncogenic [(12)Val]K-ras were susceptible to apoptosis. The present study examined the role of K-and H-Ras in the induction of apoptosis using rat endometrial cells (RENT4 cells). We found that constitutively activated K-Ras promoted apoptotic cell death, whereas the H-Ras mutant rescued rat endometrial cells front apoptosis. Expression of a constitutively active form of Raf-1 (Raf-CAAX) promoted apoptosis, whereas expression of a constitutively active catalytic subunit of phosphoinositide 3-kinase, p110K227E, allowed cells to escape front apoptosis. Moreover, inhibition of the MEK-MAPK pathway by the specific inhibitor, UO126, rescued the cells from apoptosis, whereas the inhibition of phosphoinositide 3-kinase by its specific inhibitor, LY294002, promoted apoptosis in RENT4 cells expressing activated K-Ras. However, both inhibitors promoted apoptosis in RENT4 cells expressing activated H-Ras. This difference in the regulation of apoptosis by the MEK inhibitor between K-Ras- and H-Ras-expressing cells depended on the interaction of effector proteins downstream of each Ras isoform. Finally. to elucidate the role of downstream K-Ras signal pathways, we generated K-Ras effector domain mutants (K12V35S, K12V40C). We examined the incidence of apoptotic cell death induced by the K-Ras effector domain mutants (K12V35S, K12V40C). The relative ratio of phospho-MAPK to phospho-Akt compared with that of mock cells was higher in K12V35S cells than in K12V40C cells. Ectopic expression of K12V35S protein increased the proportion of apoptotic cells, and in turn, the expression of K12V40C protein decreased compared with the expression of K12V protein without the effector domain mutant. These results demonstrate that K- and H-Ras-mediated signaling pathways exert distinct effects on apoptosis and that K-Ras downstream Raf/MEK/MAPK pathway is required for the induction of apoptosis in endometrial cells. Coordination of the two pathways contributes to endometrial cell survival.