抑制ERK/Akt介导的c-Fos表达是胡椒碱诱导结直肠癌细胞中细胞周期蛋白D1下调和肿瘤抑制所必需的。

Inhibition of ERKs/Akt-Mediated c-Fos Expression Is Required for Piperlongumine-Induced Cyclin D1 Downregulation and Tumor Suppression in Colorectal Cancer Cells.

作者信息

Gao Feng, Zhou Li, Li Ming, Liu Wenbin, Yang Shuting, Li Wei

机构信息

Cell Transplantation and Gene Therapy Institute, The Third Xiangya Hospital, Central South University, Changsha, Hunan 410013, People's Republic of China.

Department of Ultrasonography, The Third Xiangya Hospital of Central South University, Changsha, Hunan 410013, People's Republic of China.

出版信息

Onco Targets Ther. 2020 Jun 15;13:5591-5603. doi: 10.2147/OTT.S251295. eCollection 2020.

BACKGROUND

Deregulation of Cyclin D1 and cell cycle progression plays a critical role in tumorigenesis. The natural compound piperlongumine (PL) exhibits potential anticancer effects in various cancer models, but the underlying mechanism needs further elucidation.

METHODS

The inhibitory effect of PL on colorectal cancer (CRC) cells was determined by anchorage-dependent and -independent assays. The protein level of Cyclin D1 was examined by immunoblot (IB) and immunohistochemical staining (IHC). The mRNA level was determined by qRT-PCR. Phosphorylation of histone H3 was analyzed by immunofluorescence (IF). The cell cycle was examined by flow cytometry. The in vivo antitumor effect was validated by the xenograft mouse model.

RESULTS

Cyclin D1 was overexpressed in CRC tissues and cells, and was required for maintaining cell growth, colony formation, and in vivo tumorigenesis. PL decreased the protein level of c-Fos, which eventually reduced the transcriptional activity of AP-1 and the mRNA level of Cyclin D1. Mechanism study showed that PL impaired EGF-induced activation of ERK1/2 and Akt signalings, which resulted in a reduction of c-Fos transcription. Furthermore, PL reduced the half-life of c-Fos and caused the ubiquitination-dependent degradation of c-Fos. Finally, the in vivo antitumor effect of PL on CRC cells was examined using a xenograft mouse model.

CONCLUSION

Our data indicate that PL is a promising antitumor agent that deserves further study for CRC treatment.

背景

细胞周期蛋白D1（Cyclin D1）的失调和细胞周期进程在肿瘤发生中起关键作用。天然化合物胡椒碱（PL）在多种癌症模型中显示出潜在的抗癌作用，但其潜在机制需要进一步阐明。

方法

通过锚定依赖性和非依赖性试验确定PL对结肠直肠癌（CRC）细胞的抑制作用。通过免疫印迹（IB）和免疫组织化学染色（IHC）检测Cyclin D1的蛋白水平。通过qRT-PCR测定mRNA水平。通过免疫荧光（IF）分析组蛋白H3的磷酸化。通过流式细胞术检测细胞周期。通过异种移植小鼠模型验证体内抗肿瘤作用。

结果

Cyclin D1在CRC组织和细胞中过表达，并且是维持细胞生长、集落形成和体内肿瘤发生所必需的。PL降低了c-Fos的蛋白水平，最终降低了AP-1的转录活性和Cyclin D1的mRNA水平。机制研究表明，PL损害了表皮生长因子（EGF）诱导的细胞外信号调节激酶1/2（ERK1/2）和蛋白激酶B（Akt）信号通路的激活，从而导致c-Fos转录减少。此外，PL缩短了c-Fos的半衰期，并导致c-Fos的泛素化依赖性降解。最后，使用异种移植小鼠模型检测了PL对CRC细胞的体内抗肿瘤作用。