Histone deacetylase inhibitor (SAHA) and repression of EZH2 synergistically inhibit proliferation of gallbladder carcinoma.
Polycomb group protein EZH2, frequently overexpressed in malignant tumors, is the catalytic subunit of polycomb repressive complex 2 (PRC2). PRC2 interacts with HDACs in transcriptional silencing and relates to tumor suppressor loss. We examined the expression of HDAC isoforms (HDAC 1 and 2) and EZH2, and evaluated the possible use of HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) and EZH2 repressor for gallbladder carcinoma. We used 48 surgically resected gallbladders and cultures of human gallbladder epithelial cells (HGECs), gallbladder carcinoma (TGBC2TKB), and cholangiocarcinoma (HuCCT-1 and TFK-1) cell lines for examination. Immunohistochemically, EZH2 was overexpressed in gallbladder carcinoma, especially poorly differentiated carcinoma, but not in normal epithelium. In contrast, HDAC1/2 were expressed in both carcinoma and normal epithelium in vivo. This pattern was verified in cultured cells; EZH2 was highly expressed only in TGBC2TKB, whereas HDAC1/2 were expressed in HGECs and TGBC2TKB. Interestingly, SAHA treatment caused significant cell number decline in three carcinoma cells, and this effect was synergized with EZH2 siRNA treatment; however, HGECs were resistant to SAHA. In TGBC2TKB cells, the expression of EZH2 and HDAC1/2 were decreased by SAHA treatment, and p16(INK4a), E-cadherin, and p21were simultaneously activated; however, no such findings were obtained in HGECs, suggesting that the effect of SAHA depends on the EZH2-mediated tumor suppressor loss. In conclusion, this study suggests a possible mechanism by which carcinoma cells but not normal cells are sensitive to SAHA and indicates the efficacy of this new anticancer agent in combination with EZH2 repression in gallbladder carcinoma.
Yamaguchi
Junpei
J
Department of Human Pathology, Kanazawa University Graduate School of Medicine, Kanazawa, Japan.
Sasaki
Motoko
M
Sato
Yasunori
Y
Itatsu
Keita
K
Harada
Kenichi
K
Zen
Yoh
Y
Ikeda
Hiroko
H
Nimura
Yuji
Y
Nagino
Masato
M
Nakanuma
Yasuni
Y
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000032:analysis; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics; D004268:DNA-Binding Proteins / Q000032:analysis / Q000037:antagonists & inhibitors* / Q000235:genetics; D000071221:Enhancer of Zeste Homolog 2 Protein; D005260:Female; D005706:Gallbladder Neoplasms / Q000188:drug therapy* / Q000473:pathology; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006655:Histone Deacetylases / Q000032:analysis; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D063151:Polycomb Repressive Complex 2; D034741:RNA, Small Interfering / Q000494:pharmacology; D014157:Transcription Factors / Q000032:analysis / Q000037:antagonists & inhibitors* / Q000235:genetics
D000970:Antineoplastic Agents; C493956:CDKN1A protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004268:DNA-Binding Proteins; D056572:Histone Deacetylase Inhibitors; D034741:RNA, Small Interfering; D014157:Transcription Factors; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D063151:Polycomb Repressive Complex 2; D006655:Histone Deacetylases