The deleted in pancreatic cancer locus 4 (DPC4)/SMAD4 tumor suppressor gene is frequently inactivated in pancreatic (approximately 55%) and colorectal cancers (approximately 30%).
Other members of the SMAD family are excellent candidates for JPS, especially SMAD2 (which, like SMAD4, is mutated somatically in colorectal cancers), SMAD3 (which causes colorectal cancer when "knocked out" in mice), SMAD5, and SMAD1.
Smad4 plays a pivotal role in the TGF-beta signaling pathway and has been identified as a tumor suppressor, being mutated or deleted in approximately 50% of pancreatic carcinomas and 15% of colorectal cancers.
MiR-190 and DPC4 expression were measured in five different CRC cell lines by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot.
Two missense mutations in the C-terminal domain of Smad4, D351H (Asp351-->His) and D537Y (Asp537-->Tyr), have been described recently in the human colorectal cancer cell lines CACO-2 and SW948 respectively [Woodford-Richens, Rowan, Gorman, Halford, Bicknell, Wasan, Roylance, Bodmer and Tomlinson (2001) Proc.Natl.Acad.Sci.U.S.A. 98, 9719-9723].
Expression of ANXA10 (P = .038), SMAD family member 4 (P = .028), and deleted in colorectal carcinoma (P = .004) was less common in adenocarcinoma of the distal stomach than in adenocarcinoma of the gastric cardia.
ITF-2B, which is up-regulated during early colorectal carcinogenesis because of loss of adenomatous polyposis coli, is a target for LOH on chromosome 18q, along with deleted in colorectal carcinoma and Smad4.
Our study demonstrated high frequency of <i>Smad4</i> alterations with low expression of Smad4 protein identifying a subgroup of aggressive colorectal cancer to be an independent marker for poor prognosis.
To investigate the potential role of DPC4/SMAD4 gene in colorectal cancers, we examined 73 tumors of clinical stages II or III from Japanese patients, for LOH at 18q21 and also for subtle mutations anywhere within the coding region of DPC4/SMAD4.
To assess the role of Smad4 in E-cadherin regulation in colorectal carcinogenesis further, the present study has analysed Smad4 and E-cadherin RNA and protein expression in colorectal carcinoma cell lines and in 51 late-stage colorectal carcinomas.
The MUTYH mutational signature reflecting persistent 8-oxoG:A mismatches occurs frequently in the APC, KRAS, PIK3CA, FAT4, TP53, FAT1, AMER1, KDM6A, SMAD4 and SMAD2 genes that are associated with CRC.
Following the definition of SMAD4 deletion as a negative predictive marker for chemotherapy benefit in patients with CRC, we aimed to evaluate the clinical relevance of the deletion of other SMAD genes clustered in this region: SMAD2 and SMAD7 in 264 CRC biopsies from a previous clinical study.
SMAD4 is a gastrointestinal malignancy-specific tumor suppressor gene found mutated in one third of colorectal cancer specimens and half of pancreatic tumors.