Mutation and expression analyses of the MET and CDKN2A genes in rhabdomyosarcoma with emphasis on MET overexpression.
Rhabdomyosarcoma (RMS) is the most common soft-tissue sarcoma of childhood. The simultaneous loss of Ink4a/Arf function and disruption of Met signaling in Ink4a/Arf-/- mice transgenic for hepatocyte growth factor/scatter factor (HGF/SF) induces RMS with extremely high penetrance and short latency. To address the roles of MET and CDKN2A (p16INK4A/p14ARF) in human RMS, we performed mutational analyses in 39 samples of RMS by PCR-SSCP. No mutations were detected in exons 14-21 of MET whereas a nonsense mutation at codon 80 of p16(INK4A) was identified in an alveolar RMS cell line. We also quantified the relative expression levels and DNA copy numbers of these genes in seven cell lines and 17 fresh tumors by real-time quantitative PCR. Expression of MET was detected in all samples; however, more than 10-fold difference was found in the samples with higher or lower expression level, despite a normal DNA copy number. The protein expression level was consistent with that of mRNA, and in cell lines with a higher expression level, MET was constitutively activated. Notably, the expression level of MET was significantly higher in patients who died (P = 0.02), in patients with stage IV (P = 0.04), as well as in patients with PAX3-FKHR chimeric transcript (P = 0.04). On the other hand, reduced or absent expression of p16INK4A and/or p14(ARF) showed no significant correlation with the clinicopathological parameters, except for the age at diagnosis. Our data suggest that MET plays a role in the progression of RMS.
Chen
Yuyan
Y
Department of Pediatrics, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
Takita
Junko
J
Mizuguchi
Masashi
M
Tanaka
Kiyoshi
K
Ida
Kohmei
K
Koh
Katsuyoshi
K
Igarashi
Takashi
T
Hanada
Ryoji
R
Tanaka
Yukichi
Y
Park
Myoung-Ja
MJ
Hayashi
Yasuhide
Y
D017668:Age of Onset; D045744:Cell Line, Tumor; D018389:Codon, Nonsense; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics*; D004252:DNA Mutational Analysis; D020869:Gene Expression Profiling; D006801:Humans; D020125:Mutation, Missense; D017354:Point Mutation; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics*; D019859:Proto-Oncogene Proteins c-met; D017978:Receptors, Growth Factor / Q000096:biosynthesis / Q000235:genetics*; D012208:Rhabdomyosarcoma / Q000235:genetics* / Q000378:metabolism
D018389:Codon, Nonsense; D019941:Cyclin-Dependent Kinase Inhibitor p16; D011518:Proto-Oncogene Proteins; D017978:Receptors, Growth Factor; C491743:MET protein, human; D019859:Proto-Oncogene Proteins c-met