Enhancer of zeste homolog 2 silences microRNA-218 in human pancreatic ductal adenocarcinoma cells by inducing formation of heterochromatin.

Enhancer of zeste homolog 2 (EZH2) is a histone methyltransferase that is overexpressed by pancreatic ductal adenocarcinoma (PDAC) cells and increases their aggressiveness. We identified microRNAs (miRs) that are regulated by EZH2 and studied their functions in PDAC cells. We performed miR profile analysis of PDAC cells incubated with EZH2 inhibitor 3-deazaneplanocin A, and pancreatic ductal epithelial cells that overexpressed EZH2. Expression levels of miRs and the targets of miRs were analyzed by quantitative reverse transcription polymerase chain reaction and immunohistochemistry. We expressed different forms of EZH2 to analyze functional domains and used small interfering RNAs to reduce its level in PDAC cells. Expression of miR-218 was repressed by EZH2 in PDAC cells. Levels of miR-218 were significantly reduced in primary PDAC tumor samples compared with paired, adjacent nontumor tissue. Overexpression of miR-218 in SW1990 cells reduced their proliferation and tumor formation and metastasis in nude mice. Loss of miR-218 from SW1990 cells increased levels of UDP-glycosyltransferase 8 and miR-218 was found to bind to its 3'-UTR. Levels of UDP-glycosyltransferase protein and messenger RNA were associated with the metastatic potential of PDAC cell lines and progression of tumors in patients. EZH2 was found to silence miR-218 by binding to its promoter, promoting heterochromatin formation, and recruiting the DNAs methyltransferase 1, 3A, and 3B. EZH2 is up-regulated in PDAC samples from patients and silences miR-218. MicroRNA-218 prevents proliferation of PDAC cells in culture, and tumor growth and metastasis in nude mice. MicroRNA-218 reduces levels of UDP-glycosyltransferase, which is associated with the metastatic potential of PDAC tumors in mice and progression of human PDAC.

Li CH ，To KF ，Tong JH ，Xiao Z ，Xia T ，Lai PB ，Chow SC ，Zhu YX ，Chan SL ，Marquez VE ，Chen Y ... -  《-》

EZH2 coupled with HOTAIR to silence MicroRNA-34a by the induction of heterochromatin formation in human pancreatic ductal adenocarcinoma.

MicroRNA-34a (miR-34a) is frequently downregulated in pancreatic ductal adenocarcinoma (PDAC) cells, however, the silencing mechanism remains unclear. Enhancer of zeste homolog 2 (EZH2) is overexpressed in PDAC, and our previous miRNA profiling showed that inhibition of EZH2 in PDAC cells led to the re-expression of a group of tumor suppressor miRNAs including miR-34a. Here, we studied the effect of ectopic EZH2 expression to the silencing of miR-34a, and identified HOTAIR as an interacting partner to induce heterochromatin formation during miR-34a repression. We identified EZH2 as a major player in silencing miR-34a. Inhibition of EZH2 upregulated miR-34a expression in PDAC cells, while EZH2 overexpression in human pancreatic ductal epithelial (HPDE) cells repressed miR-34a expression and decreased the miR-34a promoter activity. We then showed that HOTAIR played a critical role in EZH2-mediated repression of miR-34a, as knockdown of HOTAIR attenuated the miR-34a inhibition effect in EZH2-overexpressing HPDE cells. HOTAIR physically interacted with miR-34a promoter, and the EZH2-interacting region located at 5' HOTAIR RNA was essential in repressing miR-34a and promoting cell proliferation. More importantly, we showed that the interaction between EZH2 and HOTAIR underlay the silencing of miR-34a through induction of heterochromatin formation. We first showed that manipulation of EZH2 level interfered the occupancy of heterochromatin markers H3K9me2, heterochromatin associated protein 1α and 1γ in PDAC cells. In turn, we showed that knockdown of HOTAIR reduced the occupancy of EZH2 at miR-34a promoter. The identification of HOTAIR-guided miR-34a silencing opened a new avenue in miR-34a-oriented therapy against PDAC.

Li CH ，Xiao Z ，Tong JH ，To KF ，Fang X ，Cheng AS ，Chen Y ... -  《-》

Involvement of CD40 targeting miR-224 and miR-486 on the progression of pancreatic ductal adenocarcinomas.

Mees ST ，Mardin WA ，Sielker S ，Willscher E ，Senninger N ，Schleicher C ，Colombo-Benkmann M ，Haier J ... -  《-》

MicroRNA-101 exerts tumor-suppressive functions in non-small cell lung cancer through directly targeting enhancer of zeste homolog 2.

Zhang JG ，Guo JF ，Liu DL ，Liu Q ，Wang JJ ... -  《-》

Carcinogenesis of intraductal papillary mucinous neoplasm of the pancreas: loss of microRNA-101 promotes overexpression of histone methyltransferase EZH2.

Nakahara O ，Takamori H ，Iwatsuki M ，Baba Y ，Sakamoto Y ，Tanaka H ，Chikamoto A ，Horino K ，Beppu T ，Kanemitsu K ，Honda Y ，Iyama K ，Baba H ... -  《-》