Induction of endoplasmic reticulum stress response by TZD18, a novel dual ligand for peroxisome proliferator-activated receptor α/γ, in human breast cancer cells

Previously we reported that the peroxisome proliferator-activated receptor α/γ dual ligand TZD18 inhibited growth and induced apoptosis of leukemia and glioblastoma cells. Now we show that TZD18 also has the same effects against six human breast cancer cell lines. To obtain insights into the mechani...

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Published in:Molecular cancer therapeutics 2009-08, Vol.8 (8), p.2296-2307
Main Authors: Zang, Chuanbing, Liu, Hongyu, Bertz, Janina, Possinger, Kurt, Koeffler, H Phillip, Elstner, Elena, Eucker, Jan
Format: Article
Language:English
Subjects:
Antineoplastic Agents - pharmacology
Apoptosis
breast cancer
Breast Neoplasms - drug therapy
Breast Neoplasms - metabolism
Cell Line, Tumor
Endoplasmic Reticulum - drug effects
Endoplasmic Reticulum - metabolism
endoplasmic reticulum stress
Female
Humans
Ligands
Phenyl Ethers - pharmacology
PPAR alpha - agonists
PPAR alpha - metabolism
PPAR dual ligands
PPAR gamma - agonists
PPAR gamma - metabolism
RNA, Small Interfering - metabolism
Thiazolidinediones - pharmacology
Transcription Factor CHOP - genetics
Transcription Factor CHOP - metabolism
Up-Regulation
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Summary:Previously we reported that the peroxisome proliferator-activated receptor α/γ dual ligand TZD18 inhibited growth and induced apoptosis of leukemia and glioblastoma cells. Now we show that TZD18 also has the same effects against six human breast cancer cell lines. To obtain insights into the mechanism involved in TZD18-induced growth inhibition and apoptosis in breast cancer, the gene expression profiles of TZD18-treated and untreated MCF-7 and MDA-MB-231 cells were compared by microarray analysis. Results reveal that many genes implicated in endoplasmic reticulum stress signaling, such as CHOP (also known as DDIT3 or GADD153 ), GRP78 ( HSPA5 ), and ATF4 , are highly up-regulated, suggesting endoplasmic reticulum stress is induced. This is supported by our data that treatment of MCF-7 and MDA-MB-231 cells with TZD18 induces phosphorylation of PERK and the α subunit of eukaryotic initiation factor 2 (eIF2α), as well as an up-regulation of GRP78 and an activation of ATF6, all of which are specific markers for endoplasmic reticulum stress. Furthermore, this ligand increases the endoplasmic reticulum stress–related cell death–regulators such as CHOP, DR5, GADD34, Bax, and Bak in these cells. Importantly, knockdown of CHOP by small interference RNA antagonizes the TZD18-induced apoptosis, indicating a crucial role of CHOP in the apoptotic process triggered by TZD18. In addition, TZD18 also activates stress-sensitive mitogen-activated protein kinase (MAPK) pathways including p38, ERK, and JNK. The specific inhibitors of these MAPKs attenuated the TZD18-induced growth inhibition in these cells. These results clearly show that activation of these MAPKs is important for TZD18-induced growth inhibition. In summary, TZD18-treatment leads to the activation of endoplasmic reticulum stress response and, subsequently, growth arrest and apoptosis in breast cancer cells. [Mol Cancer Ther 2009;8(8):2296–307]
ISSN:1535-7163
1538-8514
DOI:10.1158/1535-7163.MCT-09-0347