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Hereditary cancer: two hits revisited
1Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, PA USA.
Journal of Cancer Research and Clinical Oncology
|January 1, 1996
Summary
Cancer development often requires two genetic mutations. Inherited cancers involve one germline and one somatic mutation, while non-hereditary cancers involve two somatic mutations. Tumor suppressor gene function is key.
Area of Science:
- Oncology
- Genetics
- Molecular Biology
Background:
- The "two-hit" model explains cancer predisposition through germline and somatic mutations.
- Retinoblastoma (RB1 gene) exemplifies this model in both hereditary and non-hereditary forms.
- Most dominantly inherited cancers follow this two-hit pattern.
Purpose of the Study:
- Investigate tumor specificity despite ubiquitous tumor suppressor gene expression.
- Explore the role of additional genetic events beyond the initial two hits.
- Understand the diminishing impact of germline mutations with increasing genetic events.
Main Methods:
- Review of existing "two-hit" cancer models.
- Analysis of genetic events in retinoblastoma and other cancers.
- Hypothesizing the role of stem-cell proliferation and specific gene mutations (e.g., APC).
Main Results:
- Tumor suppressor gene mutations initiate carcinogenesis, but additional events are often required.
- The number of required genetic events influences the significance of inherited mutations.
- Stem-cell proliferation is crucial in early carcinogenesis, particularly in embryonal tumors and sarcomas.
Conclusions:
- Tumor predilection specificity arises from factors beyond initial mutations, potentially involving additional genetic events.
- In adult renewal tissues, mutations like those in the APC gene may disrupt cell division control, contributing to common carcinomas.
- The interplay between stem-cell proliferation and genetic mutations drives carcinogenesis across different tissue types and age groups.