齐墩果烷型三萜 CDDO-Me 通过抑制 Stat3 通路诱导多药耐药骨肉瘤细胞凋亡。

BACKGROUND

The activation of signal transducer and activator of transcription 3 (Stat3) pathway correlates with tumor growth, survival, drug resistance and poor prognosis in osteosarcoma. To explore the potential therapeutic values of this pathway, we assessed both the expression and the activation of Stat3 pathway in several pairs of multidrug resistant (MDR) osteosarcoma cell lines, and tissues. To explore the potential therapeutic values of this pathway, we analyzed the ability of the synthetic oleanane triterpenoid, C-28 methyl ester of 2-cyano-3,12-dioxoolen-1,9-dien-28-oic acid (CDDO-Me), to inhibit Stat3 expression and activation as well as its effects on doxorubicin sensitivity in osteosarcoma cells.

METHODS

Expression of Stat3, phosphorylated Stat3 (pStat3) and Stat3 targeted proteins, including Bcl-XL, Survivin and MCL-1 were determined in drug sensitive and MDR osteosarcoma cell lines and tissues by Western blot analysis. The effect of CDDO-Me on osteosarcoma cell growth was evaluated by MTT and apoptosis by PARP cleavage assay and caspase-3/7 activity.

RESULTS

Stat3 pathway was activated in osteosarcoma tissues and in MDR cell lines. CDDO-Me inhibited growth and induced apoptosis in osteosarcoma cell lines. Treatment with CDDO-Me significantly decreased the level of nuclear translocation and phosphorylation of Stat3. The inhibition of Stat3 pathway correlated with the suppression of the anti-apoptotic Stat3 targeted genes Bcl-XL, survivin, and MCL-1. Furthermore, CDDO-Me increased the cytotoxic effects of doxorubicin in the MDR osteosarcoma cell lines.

CONCLUSIONS

Stat3 pathway is overexpressed in MDR osteosarcoma cells. CDDO-Me significantly inhibited Stat3 phosphorylation, Stat3 nuclear translocation and induced apoptosis in osteosarcoma. This study provides the framework for the clinical evaluation of CDDO-Me, either as monotherapy or perhaps even more effectively in combination with doxorubicin to treat osteosarcoma and overcome drug resistance.

背景

信号转导子和转录激活子 3（Stat3）途径的激活与骨肉瘤的肿瘤生长、存活、耐药和预后不良相关。为了探索该途径的潜在治疗价值，我们评估了几对多药耐药（MDR）骨肉瘤细胞系和组织中 Stat3 途径的表达和激活。为了探索该途径的潜在治疗价值，我们分析了合成齐墩果酸三萜、2-氰基-3,12-二氧代-1,9-二烯-28-酸 C-28 甲酯（CDDO-Me）抑制 Stat3 表达和激活及其对骨肉瘤细胞中多柔比星敏感性的影响。

方法

通过 Western blot 分析检测 Stat3、磷酸化 Stat3（pStat3）和 Stat3 靶向蛋白，包括 Bcl-XL、Survivin 和 MCL-1 在敏感和 MDR 骨肉瘤细胞系和组织中的表达。通过 MTT 评估 CDDO-Me 对骨肉瘤细胞生长的影响，通过 PARP 切割测定和 caspase-3/7 活性评估细胞凋亡。

结果

Stat3 途径在骨肉瘤组织和 MDR 细胞系中被激活。CDDO-Me 抑制骨肉瘤细胞系的生长并诱导其凋亡。CDDO-Me 治疗显著降低 Stat3 核转位和磷酸化水平。Stat3 途径的抑制与抗凋亡 Stat3 靶向基因 Bcl-XL、Survivin 和 MCL-1 的抑制相关。此外，CDDO-Me 增加了 MDR 骨肉瘤细胞系中多柔比星的细胞毒性作用。