Aberrant methylation of Reprimo in human malignancies.
Reprimo is a new candidate mediator of p53-mediated cell cycle arrest at the G2 phase. Loss of Reprimo gene expression accompanied by its promoter methylation was identified in pancreatic and lung cancers. Our aim was to examine the methylation status of Reprimo in a broad range of cancers. We examined Reprimo expression by RT-PCR and the DNA methylation status of the Reprimo promoter by MSP in 39 tumor cell lines. Loss or downregulation of Reprimo expression was frequent (62%), and we confirmed that transcriptional repression of Reprimo was caused by hypermethylation (overall concordance 92%). Treatment of expression-negative cells with 5-aza-2'-deoxycytidine restored Reprimo expression. We then examined aberrant methylation of Reprimo in 645 tumors representing 16 tumor types. Promoter methylation of Reprimo was found in 79% of gastric cancers, 62% of gallbladder cancers, 57% of lymphomas, 56% of colorectal cancers, 40% of esophageal adenocarcinomas, 37% of breast cancers and 31% of leukemias. Methylation frequencies in ovarian cancers, bladder cancers, cervical cancers, brain tumors, malignant mesotheliomas and pediatric tumors were lower (0-20%). Reprimo methylation was rarely detected in nonmalignant tissues (0-11%) except for gastric epithelia. While colorectal polyps were also frequently methylated (27%), chronic cholecystitis samples were infrequently methylated (4%). Furthermore, we failed to identify Reprimo mutation in colorectal and gastric cancer cell lines and 50 primary colorectal cancers. Aberrant methylation of Reprimo with loss of expression is a common event and may contribute to the pathogenesis of some types of human malignancy.
Takahashi
Takao
T
Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center, Dallas, TX 75390-8593, USA.
Suzuki
Makoto
M
Shigematsu
Hisayuki
H
Shivapurkar
Narayan
N
Echebiri
Chinyere
C
Nomura
Masaharu
M
Stastny
Victor
V
Augustus
Meena
M
Wu
Chew-Wun
CW
Wistuba
Ignacio I
II
Meltzer
Stephen J
SJ
Gazdar
Adi F
AF
D000328:Adult; D001483:Base Sequence; D018797:Cell Cycle Proteins / Q000235:genetics*; D045744:Cell Line, Tumor; D002648:Child; D019175:DNA Methylation; D017931:DNA Primers; D004273:DNA, Neoplasm / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006023:Glycoproteins / Q000235:genetics*; D006801:Humans; D009369:Neoplasms / Q000235:genetics*; D016133:Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
D018797:Cell Cycle Proteins; D017931:DNA Primers; D004273:DNA, Neoplasm; D006023:Glycoproteins; C412566:RPRM protein, human