JNK相互作用蛋白1（JIP-1）可保护LNCaP前列腺癌细胞免于因12-0-十四烷酰佛波醇-13-乙酸酯（TPA）介导的生长停滞和凋亡。

JNK interacting protein 1 (JIP-1) protects LNCaP prostate cancer cells from growth arrest and apoptosis mediated by 12-0-tetradecanoylphorbol-13-acetate (TPA).

作者信息

Ikezoe T, Yang Y, Taguchi H, Koeffler H P

机构信息

Division of Hematology/Oncology, Cedars-Sinai Research Institute, University of California-Los Angeles School of Medicine, Los Angeles, CA 90048, USA.

出版信息

Br J Cancer. 2004 May 17;90(10):2017-24. doi: 10.1038/sj.bjc.6601834.

DOI:10.1038/sj.bjc.6601834

PMID:15138488

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC2409468/

Abstract

12-0-tetradecanoylphorbol-13-acetate (TPA) stimulates protein kinase C (PKC) which mediates apoptosis in androgen-sensitive LNCaP human prostate cancer cells. The downstream signals of PKC that mediate TPA-induced apoptosis in LNCaP cells are unclear. In this study, we found that TPA activates the c-Jun NH2-terminal kinase (JNK)/c-Jun/AP-1 pathway. To explore the possible role that the JNK/c-Jun/AP-1 signal pathway has on TPA-induced apoptosis in LNCaP cells, we stably transfected the scaffold protein, JNK interacting protein 1 (JIP-1), which binds to JNK inhibiting its ability to phosphorylate c-Jun. TPA (10(-9)-10(-7) mol l(-1)) caused phosphorylation of JNK in both wild-type and JIP-1-transfected (LNCaP-JIP-1) cells. It resulted in phosphorylation and upregulation of expression of c-Jun protein in the wild-type LNCaP cells, but not in the JIP-1-transfected LNCaP cells. In addition, upregulation of AP-1 reporter activity by TPA (10(-9) mol l(-1)) occurred in LNCaP cells but was abrogated in LNCaP-JIP-1 cells. Thus, TPA stimulated c-Jun through JNK, and JIP-1 effectively blocked JNK. TPA (10(-12)-10(-8) mol l(-1)) treatment of LNCaP cells caused their growth inhibition, cell cycle arrest, upregulation of p53 and p21waf1, and induction of apoptosis. All of these effects were significantly attenuated when LNCaP-JIP-1 cells were similarly treated with TPA. A previous study showed that c-Jun/AP-1 blocked androgen receptor (AR) signaling by inhibiting AR binding to AR response elements (AREs) of target genes including prostate-specific antigen (PSA). Therefore, we hypothesised that TPA would not be able to disrupt the AR signal pathway in LNCaP-JIP-1 cells. Contrary to expectation, TPA (10(-9)-10(-8) mol l(-1)) inhibited DHT-induced AREs reporter activity and decreased levels of PSA in the LNCaP-JIP-1 cells. Taken together, TPA, probably by stimulation of PKC, phosphorylates JNK, which phosphorylates and increases expression of c-Jun leading to AP-1 activity. Growth control of prostate cancer cells can be mediated through the JNK/c-Jun pathway, but androgen responsiveness of these cells can be independent of this pathway, suggesting that androgen independence in progressive prostate cancer may not occur through activation of this pathway.

摘要

12 - O - 十四烷酰佛波醇 - 13 - 乙酸酯（TPA）可刺激蛋白激酶C（PKC），PKC介导雄激素敏感的LNCaP人前列腺癌细胞的凋亡。介导TPA诱导LNCaP细胞凋亡的PKC下游信号尚不清楚。在本研究中，我们发现TPA激活c - Jun氨基末端激酶（JNK）/c - Jun/AP - 1信号通路。为探究JNK/c - Jun/AP - 1信号通路在TPA诱导LNCaP细胞凋亡中可能发挥的作用，我们稳定转染了支架蛋白JNK相互作用蛋白1（JIP - 1），该蛋白与JNK结合可抑制其磷酸化c - Jun的能力。TPA（10⁻⁹ - 10⁻⁷ mol·l⁻¹）可使野生型细胞和转染JIP - 1的细胞（LNCaP - JIP - 1）中的JNK发生磷酸化。这导致野生型LNCaP细胞中c - Jun蛋白发生磷酸化并上调其表达，但在转染JIP - 1的LNCaP细胞中未出现这种情况。此外，TPA（10⁻⁹ mol·l⁻¹）可使LNCaP细胞中AP - 1报告基因活性上调，但在LNCaP - JIP - 1细胞中这种上调被消除。因此，TPA通过JNK刺激c - Jun，而JIP - 1可有效阻断JNK。用TPA（10⁻¹² - 10⁻⁸ mol·l⁻¹）处理LNCaP细胞会导致其生长抑制、细胞周期停滞、p53和p21waf1上调以及凋亡诱导。当用TPA对LNCaP - JIP - 1细胞进行类似处理时，所有这些效应均显著减弱。先前的一项研究表明，c - Jun/AP - 1通过抑制雄激素受体（AR）与包括前列腺特异性抗原（PSA）在内的靶基因的AR反应元件（AREs）结合来阻断AR信号通路。因此，我们推测TPA无法破坏LNCaP - JIP - 1细胞中的AR信号通路。与预期相反，TPA（10⁻⁹ - 10⁻⁸ mol·l⁻¹）可抑制LNCaP - JIP - 1细胞中双氢睾酮（DHT）诱导的AREs报告基因活性，并降低PSA水平。综上所述，TPA可能通过刺激PKC使JNK磷酸化，JNK进而使c - Jun磷酸化并增加其表达，导致AP - 1活性增加。前列腺癌细胞的生长调控可通过JNK/c - Jun信号通路介导，但这些细胞的雄激素反应性可能独立于该信号通路，这表明进展期前列腺癌中的雄激素非依赖性可能并非通过该信号通路的激活而发生。