Oncotarget

Research Papers:

Autophagy is involved in TGF-β1-induced protective mechanisms and formation of cancer-associated fibroblasts phenotype in tumor microenvironment

Fang-Lan Liu, En-Pan Mo, Liu Yang, Jun Du, Hong-Sheng Wang, Huan Zhang, Hiroshi Kurihara, Jun Xu and Shao-Hui Cai _

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Oncotarget. 2016; 7:4122-4141. https://doi.org/10.18632/oncotarget.6702

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Abstract

Fang-Lan Liu1, En-Pan Mo1, Liu Yang1, Jun Du2, Hong-Sheng Wang2, Huan Zhang1, Hiroshi Kurihara1, Jun Xu1, Shao-Hui Cai1

1Pharmacy College, Jinan University, Guangzhou 510632, China

2Pharmacy College, Sun Yat-Sen University, Guangzhou 510405, China

Correspondence to:

Shao-Hui Cai, e-mail: csh5689@sina.com

Jun Xu, e-mail: goldstar_8209@163.com

Keywords: autophagy, TGF-β1, tumor microenvironment, mitochondria, cancer-associated fibroblasts

Received: July 06, 2015    Accepted: December 02, 2015    Published: December 21, 2015

ABSTRACT

Transforming growth factor-β1 (TGF-β1) present in tumor microenvironment acts in a coordinated fashion to either suppress or promote tumor development. However, the molecular mechanisms underlying the effects of TGF-β1 on tumor microenvironment are not well understood. Our clinical data showed a positive association between TGF-β1 expression and cancer-associated fibroblasts (CAFs) in tumor microenvironment of breast cancer patients. Thus we employed starved NIH3T3 fibroblasts in vitro and 4T1 cells mixed with NIH3T3 fibroblasts xenograft model in vivo to simulate nutritional deprivation of tumor microenvironment to explore the effects of TGF-β1. We demonstrated that TGF-β1 protected NIH3T3 fibroblasts from Star-induced growth inhibition, mitochondrial damage and cell apoptosis. Interestingly, TGF-β1 induced the formation of CAFs phenotype in starvation (Star)-treated NIH3T3 fibroblasts and xenografted Balb/c mice, which promoted breast cancer tumor growth. In both models, autophagy agonist rapamycin increased TGF-β1-induced protective effects and formation of CAFs phenotypes, while autophagy inhibitor 3-methyladenine, Atg5 knockdown or TGF-β type I receptor kinase inhibitor LY-2157299 blocked TGF-β1 induced these effects. Taken together, our results indicated that TGF-β/Smad autophagy was involved in TGF-β1-induced protective effects and formation of CAFs phenotype in tumor microenvironment, which may be used as therapy targets in breast cancer.


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