Phorbol 12-myristate 13-acetate and serum synergize to promote rapamycin-insensitive cell proliferation via protein kinase C-eta.
Phorbol 12-myristate 13-acetate and serum synergize to promote rapamycin-insensitive cell proliferation via protein kinase C-eta.
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佛波醇 12-肉豆蔻酸酯 13-乙酸酯和血清协同作用，通过蛋白激酶 C-eta 促进雷帕霉素不敏感的细胞增殖。
DOI：
10.1038/sj.onc.1209791
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发表时间：
2007
期刊：
影响因子：
8
通讯作者：
Hussaini,IM
中科院分区：
文献类型：
--
作者：
Martin,PM;Aeder,SE;Chrestensen,CA;Sturgill,TW;Hussaini,IM
以前，我们已经表明，PKC-η（蛋白激酶C-eta）积极调节胶质母细胞瘤增殖，并赋予辐射诱导的细胞凋亡的阻力。在这项研究中，我们研究了雷帕霉素在两种胶质母细胞瘤细胞系U-251 MG（PKC-η表达）和U-1242 MG（PKC-η缺陷）中抑制PKC-η活化后细胞增殖的功效。在U-251 MG细胞中，当细胞同时用10%血清和佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA，100 nM）（PKC同工酶的有效激活剂）刺激时，雷帕霉素（10 nM）处理作为抗增殖剂的效果较差。雷帕霉素不敏感的生长归因于PKC-η，因为用激酶死亡形式的PKC-η（U-251 kr）感染的U-1242 MG和U-251 MG细胞对雷帕霉素诱导的细胞增殖抑制敏感。转染PKC-η反义寡核苷酸的U-251 MG细胞对雷帕霉素敏感。用PMA刺激的表达PKC-η的细胞维持Thr 389上的p70 S6 K磷酸化和rpS 6（ser 235/36）的磷酸化，表明p70 S6 K激酶活性仍然完整。用小干扰RNA寡核苷酸抑制p70 S6 K表达在PMA和血清的组合存在下抑制细胞增殖大于50%。此外，p70 S6 K与PKC-η共沉淀，表明PKC-η和p70 S6 K之间的物理相互作用调节了观察到的磷酸化。总之，这些数据表明雷帕霉素不敏感的胶质母细胞瘤增殖涉及PKC-η信号传导。
Previously, we have shown that PKC-η (protein kinase C-eta) positively regulates glioblastoma proliferation and confers resistance to irradiation-induced apoptosis. In this study, we investigated the efficacy of rapamycin in inhibiting cell proliferation in two glioblastoma cell lines U-251MG (PKC-η expressing) and U-1242MG (PKC-η deficient) following PKC-η activation. In U-251MG cells, rapamycin (10 n M) treatment was less effective as an antiproliferative agent when cells were concurrently stimulated with 10% serum and phorbol 12-myristate 13-acetate (PMA, 100 n M), a potent activator of PKC isozymes. Rapamycin-insensitive growth was owing to PKC-η, as U-1242MG and U-251MG cells infected with a kinase-dead form of PKC-η (U-251kr) were susceptible to rapamycin-induced inhibition of cell proliferation. Furthermore, U-251MG cells transfected with PKC-η antisense oligonucleotides were sensitive to rapamycin. PKC-η-expressing cells stimulated with PMA maintained p70S6K phosphorylation on Thr389 and phosphorylation of rpS6 (ser235/36), suggesting p70S6K kinase activity was still intact. Inhibition of p70S6K expression with small interfering RNA oligonucleotides inhibited cell proliferation greater than 50% in the presence of a combination of PMA and serum. Additionally, p70S6K co-precipitated with PKC-η, suggesting a physical interaction between PKC-η and p70S6K regulates the observed phosphorylation. Taken together, these data demonstrate that rapamycin-insensitive glioblastoma proliferation involves PKC-η signaling.