Methyl jasmonate sensitizes human bladder cancer cells to gambogic acid-induced apoptosis through down-regulation of EZH2 expression by miR-101.
OBJECTIVE
Gambogic acid (GA) and methyl jasmonate (MJ) are increasingly being recognized as novel natural anticancer compounds. Here, we investigated the antitumour effects of GA in combination with MJ on human bladder cancer cells.


METHODS
Cell viability was detected by cell counting kit-8 assay. Cell apoptosis was assessed by Hoechst 33258 staining and flow cytometry. Protein levels were determined by immunoblotting and expressions of mRNA and miRNAs by RT-PCR. Differential expressions of a group of downstream genes were identified using microarray analysis.


RESULTS
MJ significantly sensitized bladder cancer cells to GA-induced growth inhibition and apoptosis while sparing normal fibroblasts. MJ enhanced GA-induced activation of caspase-3 and caspase-9, and down-regulated the expression of XIAP. Furthermore, treatment of bladder cancer cells with a combination of GA and MJ induced synergistic inhibition of the enhancer of zeste homologue 2 (EZH2) expression, whereas miR-101 expression was up-regulated. Conversely, knockdown of miR-101 restored this decreased expression of EZH2 and suppressed the inhibitory effect of GA and MJ on the growth of bladder cancer cells. Microarray analysis showed that genes closely associated with bladder cancer development were significantly down-regulated by GA and MJ. In a s.c. xenograft mouse model of human bladder carcinoma, the combination of GA and MJ exerted an increased antitumour effect compared with GA alone.


CONCLUSIONS
MJ sensitizes bladder cancer cells to GA-induced apoptosis by down-regulating the expression of EZH2 induced by miR-101. Thus, the combination of selective anti-cancer agents MJ and GA could provide a novel strategy for treating human bladder cancer.
Department of Urology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China.
Yongjun
Y
Wang
Wei
W
Xiang
Miao
M
Wang
Tao
T
Huang
Xingyuan
X
Xiao
Liang
L
Wang
Dan
D
Tao
Liyun
L
Dong
Fuqing
F
Zeng
Guosong
G
Jiang
D000085:Acetates / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use*; D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D003517:Cyclopentanes / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use*; D004357:Drug Synergism; D000071221:Enhancer of Zeste Homolog 2 Protein; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D035683:MicroRNAs / Q000819:agonists* / Q000037:antagonists & inhibitors / Q000378:metabolism; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D054883:Oxylipins / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use*; D063151:Polycomb Repressive Complex 2 / Q000819:agonists / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D012334:RNA, Neoplasm / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism; D011897:Random Allocation; D014407:Tumor Cells, Cultured; D001743:Urinary Bladder / Q000187:drug effects / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D044004:Xanthones / Q000008:administration & dosage / Q000819:agonists / Q000494:pharmacology / Q000627:therapeutic use*; D023041:Xenograft Model Antitumor Assays
D000085:Acetates; D000972:Antineoplastic Agents, Phytogenic; D003517:Cyclopentanes; C534072:MIRN101 microRNA, human; D035683:MicroRNAs; D009363:Neoplasm Proteins; D054883:Oxylipins; D012334:RNA, Neoplasm; D044004:Xanthones; C052659:gambogic acid; C072239:methyl jasmonate; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D063151:Polycomb Repressive Complex 2
EZH2; apoptosis; gambogic acid; methyl jasmonate; miR-101; sensitization