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P53 and IGFBP-3: apoptosis and cancer protection
1Division of Pediatric Endocrinology, The University of Pennsylvania, Philadelphia, Pennsylvania, 19104, USA.
Abstract:
p53, perhaps the single most important human tumor suppressor, is commonly mutated in human cancers. Normally genotoxic stress and hypoxia activate p53, which, through DNA-specific transcription activation, transcriptional repression, and protein-protein interactions, triggers cell cycle arrest and apoptosis. One of the genes induced by p53 was identified as that encoding the insulin-like growth factor binding protein (IGFBP)-3. IGFBP-3 was originally defined by the somatomedin hypothesis as the principal carrier of IGF-I in the circulation and the primary regulator of the amount of free IGF-I available to interact with the IGF-1 receptor. However, there is accumulating evidence that IGFBP-3 can also cause apoptosis in an IGF-independent manner. Thus, IGFBP-3 induction by p53 constitutes a new means of cross-talk between the p53 and IGF axes, and suggests that the ultimate function of IGFBP-3 may be to serve a protective role against the potentially carcinogenic effects of growth hormone and IGF-I.
Insights
The tumor suppressor p53 induces insulin-like growth factor binding protein 3 (IGFBP-3), a protein that can trigger apoptosis independently of IGF-I. This discovery reveals a new link between p53 and IGF signaling, suggesting IGFBP-3 protects against cancer.
Area of Science:
- Molecular Biology
- Cancer Research
- Endocrinology
Background:
- The tumor suppressor p53 is crucial for preventing cancer by inducing cell cycle arrest and apoptosis.
- p53 activation is typically triggered by genotoxic stress and hypoxia.
- Insulin-like growth factor binding protein 3 (IGFBP-3) is known to regulate IGF-I bioavailability.
Purpose of the Study:
- To investigate the relationship between p53 and IGFBP-3.
- To explore the role of IGFBP-3 in p53-mediated apoptosis.
- To understand the cross-talk between the p53 and IGF signaling pathways.
Main Methods:
- Analysis of gene expression following p53 activation.
- Investigating the function of IGFBP-3 in cellular processes.
- Studying the interaction between p53 and IGFBP-3.
Main Results:
- p53 induces the expression of IGFBP-3.
- IGFBP-3 can induce apoptosis independently of IGF-I.
- This suggests a novel IGF-independent function for IGFBP-3.
Conclusions:
- p53 induction of IGFBP-3 represents a new mechanism of cross-talk between the p53 and IGF axes.
- IGFBP-3 may play a protective role against the carcinogenic effects of growth hormone and IGF-I.
- This finding offers new insights into cancer suppression and potential therapeutic strategies.