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Molecular cloning of human TAK1 and its mutational analysis in human lung cancer
1Laboratory of Ultrastructure Research, Aichi Cancer Center Research Institute, Nagoya, Japan.
Abstract:
In previous reports, we described that DPC4/Smad4 and Smad2 are mutated in a fraction of human lung cancers and suggested possible roles of the downstream mediators of transforming growth factor-beta (TGF-beta)-elicited signals in the pathogenesis of this most common cancer. In the present study, we investigated whether another downstream mediator, human TGF-beta-activated kinase 1 (hTAK1), also is altered in lung cancer. For this purpose, the hTAK1 gene was cloned with the aid of an expression sequence tag database search and cDNA library screening, and hTAK1 was found to be expressed ubiquitously in 2 distinct isoforms regulated in a tissue-specific manner in fetal and adult normal tissues. Interestingly, hTAK1 was assigned to the chromosome region 6q14-21, which is deleted frequently in various human malignancies, including lung cancer. Despite our extensive search for alterations in 39 lung cancer specimens as well as in 16 lung cancer cell lines, somatic mutations of hTAK1 were not identified, indicating that hTAK1 itself is not a frequent target for genetic alterations in lung cancer.
Insights
Transforming growth factor-beta (TGF-beta)-activated kinase 1 (hTAK1) was investigated in lung cancer. Despite its location on a frequently deleted chromosome region, hTAK1 mutations were not found in lung cancer specimens or cell lines.
Area of Science:
- Molecular biology
- Cancer research
- Genetics
Background:
- Transforming growth factor-beta (TGF-beta) signaling is crucial in cellular processes.
- Mutations in TGF-beta pathway mediators like Smad4 and Smad2 occur in lung cancer.
- The role of human TGF-beta-activated kinase 1 (hTAK1) in lung cancer pathogenesis is unexplored.
Purpose of the Study:
- To investigate alterations of the hTAK1 gene in human lung cancer.
- To determine the expression patterns of hTAK1 isoforms in normal tissues.
- To assess the potential role of hTAK1 in lung cancer development.
Main Methods:
- Cloning of the hTAK1 gene using expression sequence tag database search and cDNA library screening.
- Analysis of hTAK1 expression in fetal and adult normal tissues.
- Screening for somatic mutations in hTAK1 across 39 lung cancer specimens and 16 lung cancer cell lines.
Main Results:
- hTAK1 is ubiquitously expressed in two distinct isoforms, with tissue-specific regulation.
- hTAK1 is mapped to chromosome region 6q14-21, frequently deleted in malignancies.
- No somatic mutations of hTAK1 were identified in the analyzed lung cancer samples.
Conclusions:
- hTAK1 is not a frequent target of genetic alterations in lung cancer.
- The specific isoforms and tissue-specific regulation of hTAK1 warrant further investigation.
- While not directly mutated, hTAK1's role in the context of chromosome 6 deletions in lung cancer requires further study.