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p21 (WAF1/Cip1/Sdi1/Pic1) mRNA is expressed in neuroblastoma cell lines but not in Ewing's sarcoma and primitive
T Maeda1, N Nishimura, H Nakamura
1Department of Pediatrics, Rokko Island Hospital, Kobe, Japan.
Abstract:
The p21 protein inhibits the activity of cyclin-Cdk complexes and suppresses cell cycle progression. Wild type p53 can induce p21, but mutated p53 cannot. Previous studies have demonstrated that mutation of p53 is absent in neuroblastoma (NB). These reports prompted us to examine whether p53 induced p21 in NB. We examined the expression of p21 and p53 mRNA in eight NB, two Ewing's sarcoma (ES) and two primitive neuroectodermal tumor (PNET) cell lines by Northern blot analysis, and sequenced p53 cDNA of these cells. Although p53 mRNA was detected in all analyzed cell lines by Northern blot analysis, p21 mRNA was detected in six NB but not in two NB, two ES and two PNET cell lines. We detected the point mutation of p53 at codon 273 (CGT to TGT) in one NB and two ES cell lines. The non-transforming substitution at codon 72 (CCC to CGC) was detected in all analyzed cell lines. One PNET cell line had a large deletion of p53 cDNA. These results showed that p21 mRNA was usually expressed in NB but not in ES and PNET. This may suggest that the down stream of the p53 signal transduction pathway in NB is different from that of the closely related tumors of ES and PNET.
Insights
Neuroblastoma (NB) cells typically express p21, a cell cycle inhibitor, unlike Ewing sarcoma (ES) and primitive neuroectodermal tumors (PNET). This suggests distinct p53 signaling pathways in NB compared to related pediatric cancers.
Area of Science:
- Molecular Biology
- Oncology
- Cancer Genetics
Background:
- The p21 protein is a key inhibitor of cyclin-dependent kinase (CDK) complexes, crucial for cell cycle progression.
- Wild-type p53 protein can induce p21 expression, while mutated p53 cannot.
- Previous research indicated a lack of p53 mutations in neuroblastoma (NB).
Purpose of the Study:
- To investigate whether the p53 pathway induces p21 expression in neuroblastoma (NB).
- To compare p21 and p53 mRNA expression in NB, Ewing sarcoma (ES), and primitive neuroectodermal tumor (PNET) cell lines.
- To analyze p53 cDNA for mutations in these pediatric tumor cell lines.
Main Methods:
- Northern blot analysis was used to examine p21 and p53 mRNA expression.
- p53 cDNA sequencing was performed to identify point mutations and deletions.
- Analysis included eight NB, two ES, and two PNET cell lines.
Main Results:
- p53 mRNA was detected in all analyzed cell lines.
- p21 mRNA was expressed in six out of eight NB cell lines but absent in two NB, two ES, and two PNET cell lines.
- p53 mutations (codon 273) were found in one NB and two ES cell lines; a large deletion was noted in one PNET line.
Conclusions:
- p21 mRNA is generally expressed in neuroblastoma but not typically in Ewing sarcoma or PNET.
- These findings suggest that the downstream p53 signaling pathway in NB differs from that in closely related tumors like ES and PNET.
- The differential expression of p21 may indicate distinct mechanisms of cell cycle regulation in these pediatric cancers.