Department of Molecular Pharmacology, The Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel.
Prostate. 2011 Jun 15;71(9):929-45. doi: 10.1002/pros.21309. Epub 2010 Dec 6.
Prostate cancer (PCa) progression is often associated with transactivation of the androgen receptor (AR) by endogenous hormones/growth factors. One such factor affecting growth, proliferation, and apoptostis (pro-/anti-) in various cancers is the adipokine leptin. This research studied leptin-induced signaling and apoptosis in androgen sensitive (LNCaP, PC3/AR) and insensitive (PC3, DU145) PCa cell lines.
Signaling was studied by immunoblotting in cells overexpressing leptin receptors (LRb), Janus kinase 2 (JAK2), and kinase negative-HER2-YFP cDNAs. Apoptosis was measured by immunoblotting of apoptotic proteins and by Hoechst staining of condensed DNA.
Leptin rapidly induced activation of JAK2, STAT3, and MAPK (ERK1/2) signaling cascades; it may also induce HER2 transactivation via leptin-induced phospho-JAK2. Leptin was then shown to exert clear pro-apoptotic effects, increasing levels of caspase 3, cleavage of its substrate, poly (ADP-ribose) polymerase (PARP) to cleaved PARP(89) , levels of CK 18, a cytoskeletal protein formed during apoptosis, and DNA condensation. Kinase inhibitors indicated that leptin-induced apoptosis is probably mediated by balanced activation of JAK2/STAT3, p38 MAPK, and PKC pathways in PCa cells. A human leptin mutein LRb antagonist, L39A/D40A/F41A, fully inhibited leptin-induced phosphorylation of JAK2, ERK1/2, and Akt/PKB, and partially abrogated effects on apoptotic proteins. In LNCaP and PC3/AR cells, leptin increased AR protein levels in correlation with raised apoptotic markers. Thus, AR may mediate, at least partly, the leptin-induced apoptotic response.
Leptin can clearly induce apoptosis in human PCa cell lines. These findings could lead to development of new leptin agonists with enhanced pro-apoptotic effects and targeted for use in human PCa.
前列腺癌 (PCa) 的进展通常与雄激素受体 (AR) 的内源性激素/生长因子的转激活有关。影响各种癌症中生长、增殖和凋亡 (促进/抑制) 的一种因素是脂肪因子瘦素。本研究研究了瘦素诱导的信号转导和在雄激素敏感 (LNCaP、PC3/AR) 和不敏感 (PC3、DU145) PCa 细胞系中的凋亡。
通过转染过表达瘦素受体 (LRb)、Janus 激酶 2 (JAK2) 和激酶阴性-HER2-YFP cDNA 的细胞，用免疫印迹法研究信号转导。通过免疫印迹法检测凋亡蛋白和 Hoechst 染色法检测浓缩 DNA 来测量细胞凋亡。
瘦素可快速诱导 JAK2、STAT3 和 MAPK (ERK1/2) 信号通路的激活；它还可以通过瘦素诱导的磷酸化 JAK2 诱导 HER2 的反式激活。然后表明瘦素具有明显的促凋亡作用，增加了 caspase 3 的水平，其底物多聚 (ADP-核糖) 聚合酶 (PARP) 被切割为 cleaved PARP(89)，细胞骨架蛋白 CK 18 的水平，以及 DNA 浓缩。激酶抑制剂表明，瘦素诱导的细胞凋亡可能是通过 PCa 细胞中 JAK2/STAT3、p38 MAPK 和 PKC 途径的平衡激活介导的。一种人瘦素突变体 LRb 拮抗剂 L39A/D40A/F41A，完全抑制了瘦素诱导的 JAK2、ERK1/2 和 Akt/PKB 的磷酸化，并部分阻断了对凋亡蛋白的作用。在 LNCaP 和 PC3/AR 细胞中，瘦素增加了 AR 蛋白水平，与提高的凋亡标志物相关。因此，AR 可能至少部分介导了瘦素诱导的凋亡反应。
瘦素可明显诱导人 PCa 细胞系发生凋亡。这些发现可能导致开发具有增强促凋亡作用的新型瘦素激动剂，并针对人类 PCa 进行靶向治疗。
