YC-1 inhibits proliferation of breast cancer cells by down-regulating EZH2 expression via activation of c-Cbl and ERK.
OBJECTIVE
YC-1 exhibits potent anticancer activity via numerous actions in many cancer cell lines. Hence, we investigated the in vivo antitumour efficacy of YC-1 in an MDA-MB-468 xenograft model and elucidated the mechanism of down-regulation of enhancer of zeste homology 2 (EZH2) by YC-1 in breast cancer cells.


METHODS
In YC-1-treated breast cancer cells and tumour specimens from YC-1-treated MDA-MB-468 xenografts, EZH2 expression was analysed by Western blotting. Pharmacological inhibitors and short hairpin RNA-mediated knockdown were applied to identify possible signalling pathways involved in EZH2 down-regulation by YC-1.


RESULTS
YC-1 reduced the viability of breast cancer cells and tumour growth in MDA-MB-468 xenografts. In breast cancer cells, YC-1 down-regulated EZH2 expression in a concentration- and time-dependent manner. Depletion of EZH2 reduced the proliferation and susceptibility of breast cancer cells to YC-1-induced apoptosis. EZH2 expression was suppressed in tumour specimens from YC-1-treated MDA-MB-468 xenograft mice. YC-1 enhanced both the degradation rate and ubiquitination of EZH2. The down-regulation of EZH2 by YC-1 was associated with activation of PKA and Src-Raf-ERK-mediated signalling pathways. Furthermore, depletion of Casitas B-lineage lymphoma (c-Cbl), an E3 ubiquitin ligase, abolished YC-1-induced apoptosis and suppression of EZH2. YC-1 rapidly activated c-Cbl to induce signalling associated with ERK and EZH2.


CONCLUSIONS
We discovered that YC-1 induces apoptosis and inhibits tumour growth of breast cancer cells via down-regulation of EZH2 by activating c-Cbl and ERK. These data suggest that YC-1 is a potential anticancer drug candidate for triple-negative breast cancer.
Graduate Institute of Pharmaceutical Chemistry, China Medical University, Taichung, Taiwan.
Ling-Chu
LC
Chang
Hui-Yi
HY
Lin
Meng-Tung
MT
Tsai
Ruey-Hwang
RH
Chou
Fang-Yu
FY
Lee
Che-Ming
CM
Teng
Min-Tsang
MT
Hsieh
Hsin-Yi
HY
Hung
Li-Jiau
LJ
Huang
Yung-Luen
YL
Yu
Sheng-Chu
SC
Kuo
D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor; D000071221:Enhancer of Zeste Homolog 2 Protein; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D007191:Indazoles / Q000737:chemistry / Q000494:pharmacology*; D008325:Mammary Neoplasms, Experimental / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D051379:Mice; D063151:Polycomb Repressive Complex 2 / Q000096:biosynthesis / Q000172:deficiency* / Q000235:genetics; D050721:Proto-Oncogene Proteins c-cbl / Q000378:metabolism*; D013329:Structure-Activity Relationship
D000970:Antineoplastic Agents; D007191:Indazoles; C090937:3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D063151:Polycomb Repressive Complex 2; D050721:Proto-Oncogene Proteins c-cbl; D048049:Extracellular Signal-Regulated MAP Kinases; C067419:CBL protein, human