Genetic alterations of the TGF-beta signaling pathway in colorectal cancer cell lines: a novel mutation in Smad3 associated with the inactivation of TGF-beta-induced transcriptional activation.
To investigate genetic alterations involved in the TGF-beta signaling pathway in colorectal cancer, we assayed DNA synthesis rates after treating TGF-beta and checked for genetic alterations in TGF-betaRII, TGF-betaRI, Smad2, Smad3, and Smad4 in 12 colorectal cancer cell lines. Eleven lines, except SNU-61, show no significant change in DNA synthesis rate after TGF-beta treatment. In these 11 lines, several mutations were found in genes involved in the TGF-beta signaling pathway: (i) frameshift deletions in the poly(A)(10) tract of the TGF-betaRII gene in SNU-407, SNU-769A, SNU-769B, and SNU-1047 cell lines, (ii) a missense mutation of Smad2 (R321Q) in SNU-81, (iii) two missense mutations in TGF-betaRI (R487W in SNU-175 and A202V in SNU-1040), and (iv) a monoallelic loss at the Smad4 locus in three cell lines. Interestingly, a missense mutation (R373H) in Smad3 gene was found in SNU-769A. To our knowledge, this is the first report of Smad3 mutation in human malignancy. This mutation was found to result in the inhibition of translocation of Smad3 protein to the nucleus and a reduction in the activity of Smad3 during TGF-beta-induced transcriptional activation. These results indicate that the majority of cell lines, which are insensitive to TGF-beta, have alterations in genes involved in the TGF-beta signaling pathway in colorectal cancer cell lines.
Ku
Ja-Lok
JL
Laboratory of Cell Biology, Korean Cell Line Bank, Cancer Research Institute, Seoul National University College of Medicine, Seoul 110-744, Republic of Korea.
Park
Seok-Hee
SH
Yoon
Kyong-Ah
KA
Shin
Young-Kyoung
YK
Kim
Kyung-Hee
KH
Choi
Jin-Sung
JS
Kang
Hio-Chung
HC
Kim
Il-Jin
IJ
Han
Inn-Oc
IO
Park
Jae-Gahb
JG
D001483:Base Sequence; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology; D017931:DNA Primers; D016368:Frameshift Mutation; D006801:Humans; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics*; D051900:Smad3 Protein / Q000235:genetics*; D015533:Transcriptional Activation; D016212:Transforming Growth Factor beta / Q000378:metabolism*
D017931:DNA Primers; D018125:Receptors, Transforming Growth Factor beta; D051900:Smad3 Protein; D016212:Transforming Growth Factor beta