Analysis of 5′-flanking region of human Smad4 (DPC4) gene

Minami, Rieko; Kitazawa, Riko; Maeda, Sakan; Kitazawa, Sohei

doi:10.1016/s0167-4781(98)00217-6

Cited by 16 publications

(28 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Moreover, there is only a limited number of published reports on putative Smad4 promoter sequences. These do not, however, cover sequences upstream of the most 5 0 exon of Smad4 (Minami et al, 1998;Zhou et al, 1999;Roth et al, 2000). Our own preliminary studies of putative promoter sequences by bisulfite sequencing did not provide evidence for hypermethylation in C4-I and C4-II.…”

Section: Discussionmentioning

confidence: 68%

Smad4 deficiency in cervical carcinoma cells

et al. 2004

View full text Add to dashboard Cite

Section: Discussionmentioning

confidence: 68%

Smad4 deficiency in cervical carcinoma cells

et al. 2004

View full text Add to dashboard Cite

“…R. Minami and S. Kitazawa (Kobe University, Kobe, Japan) [21]. A 331-bp proximal fragment of the DPC4 promoter region from the transcription start site was amplified by PCR using genomic DNA from tumors and their blood cells.…”

Section: Cloning Of the Dpc4 Promoter Region And Dna Sequencingmentioning

confidence: 99%

“…Thus, we became interested in the possibility that somatic mutations in the DPC4 promoter regions silenced or disturbed the transcription. A 1.4-kb fragment of the 5′ flanking region of the DPC4 gene was cloned recently from a phage library by using the first exon's sequence as a primer [21]. We amplified a 331-bp fragment of the DPC4 promoter region by PCR with genomic DNAs obtained from the six tumors that failed to express normal DPC4 transcripts.…”

Section: Disruption Of Dpc4 Transcription By Somatic Mutations In Thementioning

confidence: 99%

Involvement of mutations in theDPC4 promoter in endometrial carcinoma development

et al. 1999

Self Cite

View full text Add to dashboard Cite

To define the target of chromosome 18q loss of heterozygosity, which is prevalent in endometrial carcinomas, we made a deletion map from 64 tumors. Loss of heterozygosity on 18q was found in 20 tumors. Among these, 14 tumors carried deletions at the 18q21.1 region, where the DPC4 gene is located. DPC4 transcription was disturbed in all six of the tumors with deletions at 18q21.1 examined, which sharply contrasted with the positive transcription in 12 tumors that retained heterozygosity at the 18q21.1 region. However, in the 14 tumors with the 18q21.1 deletions, the remaining allele had the wild-type sequence of the DPC4 coding region instead of somatic mutations in the DPC4 coding region. We found a one- and two-base substitutions in the DPC4 promoter in two of the six tumors that showed disturbed DPC4 transcription. Chloramphenicol acetyltransferase assays clearly demonstrated that the mutant promoters had the potential to suppress or silence DPC4 transcription, implicating the DPC4 gene in endometrial carcinoma.

show abstract

“…Second, hypermethylation as a mechanism of inactivation of tumor suppressor genes is well characterized (17). However, in two previous studies regarding hypermethylation of SMAD4, either the first exon of SMAD4 was omitted from the hypermethylation assay, or an irrelevant promoter region of SMAD4 was used (18,19); thus, the role of hypermethylation as a mechanism for SMAD4 gene inactivation remains unknown. Third, although they are rare in gastric cancer (7), SMAD4 mutations can result in changes in the tertiary structure and stability of the protein (20 -22).…”

mentioning

confidence: 99%

Inactivation of SMAD4 Tumor Suppressor Gene During Gastric Carcinoma Progression

Wang

Kim

Lee

et al. 2007

Clinical Cancer Research

100

View full text Add to dashboard Cite

Purpose: Mothers against decapentaplegic homologue 4 (SMAD4) is a tumor suppressor gene associated with gastrointestinal carcinogenesis. The aim of the present study is to more precisely characterize its role in the development and progression of human gastric carcinoma. Experimental Design: The expression of SMAD4 was investigated in 283 gastric adenocarcinomas and related lesions, as well as in 9 gastric carcinoma cell lines. We also analyzed the methylation status of SMAD4 gene by using methylation-specific PCR, examined loss of heterozygosity (LOH) of this gene locus by using a vicinal marker, and detected exon mutation of SMAD4 through exon-by-exon amplification. Moreover, we assessed whether MG132, a proteasome inhibitor, affected the SMAD4 protein level. Results: We found loss of SMAD4 protein expression in the cytoplasm (36 of 114, 32%) and in the nucleus (46 of 114, 40%) of gastric cancer cells. The loss of nuclear SMAD4 expression in primary tumors correlated significantly with poor survival, and was an independent prognostic marker in multivariate analysis.We also found a substantial decrease in SMAD4 expression at both the RNA and protein level in several human gastric carcinoma cell lines. In addition, we found that LOH (20 of 70, 29%) and promoter hypermethylation (4 of 73, 5%) were associated with the loss of SMAD4 expression. SMAD4 protein levels were also affected in certain gastric carcinoma cell lines following incubation with MG132. Conclusion: Taken together, our results indicate that the loss of SMAD4, especially loss of nuclear SMAD4 expression, is involved in gastric cancer progression. The loss of SMAD4 in gastric carcinomas was due to several mechanisms, including LOH, hypermethylation, and proteasome degradation.

show abstract

Analysis of 5′-flanking region of human Smad4 (DPC4) gene

Cited by 16 publications

References 17 publications

Smad4 deficiency in cervical carcinoma cells

Smad4 deficiency in cervical carcinoma cells

Involvement of mutations in theDPC4 promoter in endometrial carcinoma development

Inactivation of SMAD4 Tumor Suppressor Gene During Gastric Carcinoma Progression

Contact Info

Product

Resources

About