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PTEN, DMBT1, and p16 alterations in diffusely infiltrating astrocytomas
Xing Fan1, Jorge Muñoz, Stephen G Sanko
1Molecular Neuro-Oncology Laboratory, University of Navarre Medical School, Irunlarrea s/n, E-31008 Pamplona, Spain.
International Journal of Oncology
|August 9, 2002
Summary
Genetic alterations in PTEN, DMBT1, and p16 genes are implicated in astrocytoma development. PTEN changes appear late, while DMBT1 and p16 alterations may be early events in low-grade astrocytomas, suggesting multiple pathways control tumor growth.
Area of Science:
- Neuro-oncology
- Cancer Genetics
- Molecular Biology
Background:
- Diffusely infiltrating astrocytomas are linked to genetic losses on chromosomes 10q and 9p.
- Tumor suppressor genes PTEN, DMBT1, and p16 are critical in regulating cell growth and preventing cancer.
Purpose of the Study:
- To investigate the roles of PTEN, DMBT1, and p16 tumor suppressor genes in astrocytoma development.
- To determine if alterations in these genes occur early or late in astrocytoma progression.
Main Methods:
- Genetic screening of 50 low- and high-grade astrocytomas for point mutations, homozygous deletions, and promoter hypermethylation.
- Utilized PCR-SSCP, direct sequencing, differential PCR, and methylation-specific PCR for comprehensive analysis.
Main Results:
- PTEN alterations (mutation/deletion) were observed in GBMs but not lower-grade astrocytomas.
- DMBT1 homozygous deletions occurred in GBMs and low-grade astrocytomas.
- p16 homozygous deletions and promoter hypermethylation were found in both GBMs and low-grade astrocytomas, with no point mutations detected.
Conclusions:
- PTEN alterations suggest late-stage genetic events in astrocytoma progression.
- DMBT1 and p16 alterations appear to be early events, occurring even in low-grade astrocytomas.
- Multiple independent genetic mechanisms likely contribute to glioblastoma multiforme (GBM) tumorigenesis, requiring aberrations in distinct pathways.