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Updated: Sep 1, 2026
Cell Population Analyses During Skin Carcinogenesis
Published on: August 21, 2013
Enhanced Sp1 DNA-binding activity in murine keratinocyte cell lines and epidermal tumors
1Department of Carcinogenesis, The University of Texas M.D. Anderson Cancer Center, Smithville 78957, USA. kumar@odin.mdacc.tmc.edu
Abstract:
Altered regulation of ornithine decarboxylase (ODC) is frequently observed in epidermal tumors. We have shown that the transcription factor Sp1 is one of the regulators of ODC expression and that Sp3 antagonizes this Sp1-mediated activation of ODC expression. These results led us to examine the levels and binding activity of Sp1 and Sp3 in nuclear extracts prepared from cultured murine keratinocytes, transformed keratinocyte cell lines and epidermal tumors. Here we show that the Sp1 DNA-binding activity is higher in established keratinocyte cell line extracts than in primary keratinocyte extracts. Sp1 message levels and Sp1 DNA-binding activity was found to be low in 20-week papillomas and high in squamous cell carcinomas. These results suggest that increased levels of Sp1 and enhanced Sp1 DNA binding activity are correlated with epidermal tumor progression. Based on these results, we propose that increased Sp1 DNA binding may augment the proliferative capacity of tumor cells through overexpression of Sp1-responsive genes, possibly including ODC.
Insights
Transcription factor Sp1 activity increases with epidermal tumor progression. This enhanced Sp1 DNA binding may drive tumor cell proliferation by upregulating genes like ornithine decarboxylase (ODC).
Area of Science:
- Molecular biology
- Cancer research
- Dermatology
Background:
- Altered ornithine decarboxylase (ODC) regulation is common in epidermal tumors.
- The transcription factor Sp1 activates ODC expression, while Sp3 antagonizes this.
- Understanding Sp1 and Sp3 roles is crucial for epidermal tumor research.
Purpose of the Study:
- To investigate the levels and DNA-binding activity of Sp1 and Sp3 in epidermal carcinogenesis.
- To correlate Sp1 and Sp3 activity with tumor progression from papillomas to squamous cell carcinomas.
Main Methods:
- Analysis of nuclear extracts from primary keratinocytes, transformed cell lines, and murine epidermal tumors.
- Quantification of Sp1 and Sp3 levels and DNA-binding activity.
Main Results:
- Sp1 DNA-binding activity was higher in established keratinocyte cell lines than in primary cells.
- Sp1 levels and DNA-binding activity were low in papillomas but high in squamous cell carcinomas.
- Sp3's role was not detailed in this abstract, focus is on Sp1.
Conclusions:
- Increased Sp1 levels and DNA-binding activity correlate with epidermal tumor progression.
- Enhanced Sp1 DNA binding may promote tumor cell proliferation via Sp1-responsive genes, potentially including ODC.
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