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p21WAF1 mutations and human malignancies
M Shiohara1, K Koike, A Komiyama
1Department of Pediatrics, Shinshu University School of Medicine, Asahi, Matsumoto, Japan.
Abstract:
During the past few years, several categories of cyclin-dependent kinase inhibitors (CDKIs), which negatively regulate cyclin/cyclin-dependent kinase (CDK) activities, were cloned. The p21WAF1, also known as CIP1 or SDI1, was the first reported CDKI: it's expression is induced by wild-type p53. The p21WAF1 is a potent inhibitor of most cyclin/CDK complexes and also inhibits the ability of the proliferating cell nuclear antigen (PCNA) to activate DNA polymerase d. Alterations of the cell-cycle can cause cellular transformation. We analysed 471 primary samples from 15 types of human malignancies and 36 cell lines for structural alterations of the p21WAF1 gene. No changes were found in the coding region of p21WAF1 gene by polymerase-chain reaction-single-strand conformation polymorphism (PCR-SSCP) analysis. Many of these tumors had a normal p53 gene. Other investigators showed that p21WAF1 knockout mice did not have an increased incidence of cancer, while p53 knock-out mice did. Taken together, the absence of alterations of p21WAF1 in a series of malignancies suggests that p21WAF1 may not have a role in either onset or progression of most human cancers. Furthermore, p53 probably activates additional, critical tumor suppressor pathways.
Insights
The p21WAF1 gene, a cyclin-dependent kinase inhibitor (CDKI), showed no structural alterations in human cancers. This suggests p21WAF1 may not play a significant role in cancer development or progression.
Area of Science:
- Molecular Biology
- Cancer Research
- Cell Cycle Regulation
Background:
- Cyclin-dependent kinase inhibitors (CDKIs) regulate cell cycle progression.
- p21WAF1 (CIP1/SDI1) is a CDKI induced by wild-type p53 and inhibits cyclin/CDK complexes and DNA polymerase.
- Cell cycle dysregulation is linked to cellular transformation and cancer.
Purpose of the Study:
- To investigate structural alterations in the p21WAF1 gene across various human malignancies.
- To determine the potential role of p21WAF1 in the onset and progression of human cancers.
Main Methods:
- Analysis of 471 primary tumor samples from 15 cancer types and 36 cell lines.
- Polymerase-chain reaction-single-strand conformation polymorphism (PCR-SSCP) to detect structural changes in the p21WAF1 gene coding region.
Main Results:
- No structural alterations were identified in the coding region of the p21WAF1 gene in the analyzed cancer samples.
- Many tumors analyzed possessed a normal p53 gene.
- Previous studies indicated p21WAF1 knockout mice did not exhibit increased cancer incidence, unlike p53 knockout mice.
Conclusions:
- The absence of p21WAF1 alterations in human malignancies suggests it may not be a key player in the initiation or progression of most human cancers.
- The tumor suppressor function of p53 likely involves other critical pathways beyond p21WAF1 activation.