title: Metallothionein III (MT3) is a putative tumor suppressor gene that is frequently inactivated in pediatric acute myeloid leukemia by promoter hypermethylation.
abstract: BACKGROUND
  Acute myeloid leukemia (AML) is the second most common form of leukemia in children. Aberrant DNA methylation patterns are a characteristic feature in various tumors, including AML. Metallothionein III (MT3) is a tumor suppresser reported to show promoter hypermethylated in various cancers. However, the expression and molecular function of MT3 in pediatric AML is unclear.
  
  
  METHODS
  Eleven human leukemia cell lines and 41 pediatric AML samples and 20 NBM/ITP (Norma bone marrow/Idiopathic thrombocytopenic purpura) control samples were analyzed. Transcription levels of MT3 were evaluated by semi-quantitative and real-time PCR. MT3 methylation status was determined by methylation specific PCR (MSP) and bisulfite genomic sequencing (BSG). The molecular mechanism of MT3 was investigated by apoptosis assays and PCR array analysis.
  
  
  RESULTS
  The MT3 promoter was hypermethylated in leukemia cell lines. More CpG's methylated of MT3 was observed 39.0% pediatric AML samples compared to 10.0% NBM controls. Transcription of MT3 was also significantly decreased in AML samples compared to NBM/ITP controls (P < 0.001); patients with methylated MT3 exhibited lower levels of MT3 expression compared to those with unmethylated MT3 (P = 0.049). After transfection with MT3 lentivirus, proliferation was significantly inhibited in AML cells in a dose-dependent manner (P < 0.05). Annexin V assay showed that apoptosis was significantly upregulated MT3-overexpressing AML cells compared to controls. Real-time PCR array analysis revealed 34 dysregulated genes that may be implicated in MT3 overexpression and apoptosis in AML, including FOXO1.
  
  
  CONCLUSIONS
  MT3 may be a putative tumor suppressor gene in pediatric AML. Epigenetic inactivation of MT3 via promoter hypermethylation was observed in both AML cell lines and pediatric AML samples. Overexpression of MT3 may inhibit proliferation and induce apoptosis in AML cells. FOXO1 was dysregulated in MT3-overexpressing cells, offering an insight into the mechanism of MT3-induced apoptosis. However, further research is required to determine the underlying molecular details.
authors: Yan-Fang
authors: YF
authors: Tao
authors: Li-Xiao
authors: LX
authors: Xu
authors: Jun
authors: J
authors: Lu
authors: Lan
authors: L
authors: Cao
authors: Zhi-Heng
authors: ZH
authors: Li
authors: Shao-Yan
authors: SY
authors: Hu
authors: Na-Na
authors: NN
authors: Wang
authors: Xiao-Juan
authors: XJ
authors: Du
authors: Li-Chao
authors: LC
authors: Sun
authors: Wen-Li
authors: WL
authors: Zhao
authors: Pei-Fang
authors: PF
authors: Xiao
authors: Fang
authors: F
authors: Fang
authors: Yan-Hong
authors: YH
authors: Li
authors: Gang
authors: G
authors: Li
authors: He
authors: H
authors: Zhao
authors: Yi-Ping
authors: YP
authors: Li
authors: Yun-Yun
authors: YY
authors: Xu
authors: Jian
authors: J
authors: Ni
authors: Jian
authors: J
authors: Wang
authors: Department of Hematology and Oncology, Children's Hospital of Soochow University, Suzhou, China. xing_feng66@hotmail.com.
authors: Xing
authors: X
authors: Feng
authors: Jian
authors: J
authors: Pan
mesh_terms: D000293:Adolescent; D001483:Base Sequence; D045744:Cell Line, Tumor; D002648:Child; D002675:Child, Preschool; D019175:DNA Methylation; D017931:DNA Primers; D005260:Female; D016147:Genes, Tumor Suppressor; D006801:Humans; D007223:Infant; D015470:Leukemia, Myeloid, Acute / Q000235:genetics* / Q000473:pathology; D008297:Male; D000090023:Metallothionein 3; D009419:Nerve Tissue Proteins / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic
chemical_list: D017931:DNA Primers; D000090023:Metallothionein 3; D009419:Nerve Tissue Proteins