Hideshima Teru, Chauhan Dharminder, Hayashi Toshiaki, Akiyama Masaharu, Mitsiades Nicholas, Mitsiades Constantine, Podar Klaus, Munshi Nikhil C, Richardson Paul G, Anderson Kenneth C
Department of Adult Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Jerome Lipper Multiple Myeloma Center, 44 Binney Street, Boston, MA 02155, USA.
Oncogene. 2003 Nov 20;22(52):8386-93. doi: 10.1038/sj.onc.1207170.
Proteasome inhibitor PS-341 is one of the most promising novel agents against multiple myeloma (MM). We have previously shown that PS-341 inhibits IL-6 triggered phosphorylation of extracellular signal-regulated kinases (ERK) 1/2 (also known as p42/44 mitogen-activated protein kinases) in MM cells. In this study, we further examined whether clinically achievable concentrations of PS-341 could inhibit IL-6 triggered signaling cascades in MM. We found that PS-341 inhibited not only ERK, but also signal transducers and activators of transcription (STAT) 3 as well as Akt phosphorylation. Since gp130 (CD130) dimerizes and is phosphorylated after IL-6 binding to gp80 (IL-6 receptor), we hypothesized that gp130 could be involved in PS-341-induced blockade of signaling cascades mediating MM cell growth, survival, and drug resistance in the bone marrow (BM) microenvironment. In this study, we first demonstrate that PS-341 induces downregulation of gp130 in a time- and dose-dependent manner in vitro, prior to MM cell death. Conversely, downregulation of gp130 is completely abrogated by the pan-caspase inhibitor Z-VAD-FMK, suggesting that downregulation of gp130 is mediated via caspase activation. Z-VAD-FMK also abrogates the inhibitory effect of PS-341 on IL-6-triggered signaling cascades. Importantly, we demonstrate that phosphorylation of ERK, STAT3, and Akt in MM.1S cells induced by either exogenous IL-6 or by binding of MM cells to BM stromal cells is abrogated by PS-341. These studies, therefore, define another novel mechanism whereby PS-341 can overcome the growth and survival advantage in MM cells conferred by the BM milieu. Importantly, this effect on cytokine-induced gp130 signaling cascades may account, at least in part, for the remarkable preclinical sensitivity and clinical responses achieved in MM with PS-341 treatment.
蛋白酶体抑制剂PS - 341是最有前景的抗多发性骨髓瘤（MM）新型药物之一。我们之前已经表明，PS - 341可抑制MM细胞中白细胞介素-6（IL - 6）触发的细胞外信号调节激酶（ERK）1/2（也称为p42/44丝裂原活化蛋白激酶）的磷酸化。在本研究中，我们进一步检测了临床可达到的PS - 341浓度是否能抑制MM中IL - 6触发的信号级联反应。我们发现PS - 341不仅抑制ERK，还抑制信号转导和转录激活因子（STAT）3以及Akt磷酸化。由于gp130（CD130）在IL - 6与gp80（IL - 6受体）结合后会二聚化并磷酸化，我们推测gp130可能参与了PS - 341诱导的对介导MM细胞在骨髓（BM）微环境中生长、存活和耐药性的信号级联反应的阻断。在本研究中，我们首先证明在体外MM细胞死亡之前，PS - 341以时间和剂量依赖性方式诱导gp130下调。相反，泛半胱天冬酶抑制剂Z - VAD - FMK完全消除了gp130的下调，这表明gp130的下调是通过半胱天冬酶激活介导的。Z - VAD - FMK也消除了PS - 341对IL - 6触发的信号级联反应的抑制作用。重要的是，我们证明外源性IL - 6或MM细胞与BM基质细胞结合诱导的MM.1S细胞中ERK、STAT3和Akt的磷酸化被PS - 341消除。因此，这些研究确定了PS - 341可以克服BM微环境赋予MM细胞生长和存活优势的另一种新机制。重要的是，这种对细胞因子诱导的gp130信号级联反应的作用可能至少部分解释了PS - 341治疗MM所取得的显著临床前敏感性和临床反应。
