title: Transcriptional and post-transcriptional control of DNA methyltransferase 3B is regulated by phosphatidylinositol 3 kinase/Akt pathway in human hepatocellular carcinoma cell lines.
abstract: DNA methyltransferases (DNMTs) are essential for maintenance of aberrant methylation in cancer cells and play important roles in the development of cancers. Unregulated activation of PI3K/Akt pathway is a prominent feature of many human cancers including human hepatocellular carcinoma (HCC). In present study, we found that DNMT3B mRNA and protein levels were decreased in a dose- and time-dependent manner in HCC cell lines with LY294002 treatment. However, we detected that LY294002 treatment did not induce increase of the degradation of DNMT3B protein using protein decay assay. Moreover we found that Akt induced alteration of the expression of DNMT3B in cells transfected with myristylated variants of Akt2 or cells transfected with small interfering RNA respectively. Based on DNMT3B promoter dual-luciferase reporter assay, we found PI3K pathway regulates DNMT3B expression at transcriptional level. And DNMT3B mRNA decay analysis suggested that down-regulation of DNMT3B by LY294002 is also post-transcriptional control. Furthermore, we demonstrated that LY294002 down-regulated HuR expression in a time-dependent manner in BEL-7404. In summary, we have, for the first time, demonstrate that PI3K/Akt pathway regulates the expression of DNMT3B at transcriptional and post-transcriptional levels, which is particularly important to understand the effects of PI3K/Akt and DNMT3B on hepatocarcinogenesis.
authors.affiliation: Department of Biochemistry and Molecular Biology, Shanghai Medical College, Fudan University, Shanghai 200032, China.
authors.forename: Chuanzhong
authors.initials: C
authors.lastname: Mei
authors.forename: Lidong
authors.initials: L
authors.lastname: Sun
authors.forename: Yonglei
authors.initials: Y
authors.lastname: Liu
authors.forename: Yong
authors.initials: Y
authors.lastname: Yang
authors.forename: Xiumei
authors.initials: X
authors.lastname: Cai
authors.forename: Mingzhu
authors.initials: M
authors.lastname: Liu
authors.forename: Wantong
authors.initials: W
authors.lastname: Yao
authors.forename: Can
authors.initials: C
authors.lastname: Wang
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.forename: Liying
authors.initials: L
authors.lastname: Wang
authors.forename: Zengxia
authors.initials: Z
authors.lastname: Li
authors.forename: Yinghong
authors.initials: Y
authors.lastname: Shi
authors.forename: Shuangjian
authors.initials: S
authors.lastname: Qiu
authors.forename: Jia
authors.initials: J
authors.lastname: Fan
authors.forename: Xiliang
authors.initials: X
authors.lastname: Zha
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002867:Chromones / Q000378:metabolism; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism; D009025:Morpholines / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D000097584:DNA Methyltransferase 3B
chemical_list: D002867:Chromones; D004248:DNA (Cytosine-5-)-Methyltransferases; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger; D000097584:DNA Methyltransferase 3B; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one