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Nuclear factor - kappaB-dependent regulation of p53 gene expression induced by daunomycin genotoxic drug
A C Hellin1, P Calmant, J Gielen
1Laboratory of Medical Chemistry, University of Liège, Belgium.
Abstract:
Anthracycline drugs are widely used for the treatment of solid tumors and leukemia, but the molecular basis of their biological effect is still poorly understood. In the HCT116 colon carcinoma cell line, which retains a wild-type inducible p53 gene, we show that the anthracycline daunomycin is a potent inducer of p53 and NF-kappaB transcription factors. Nuclear accumulation of p53 protein occurred because of increased protein stability and enhanced gene expression. In addition, daunomycin induced the p53 promoter through the binding of p50/p65 NF-kappaB heterodimers to the kappaB site in the p53 promoter. Under our conditions, the free radical scavengers NAC and PDTC were not able to block NF-kappaB activation or p53 induction, indicating that reactive oxygen intermediates were not involved in the cellular response to daunomycin stimulation. Overexpression of a stable unresponsive IkappaBalpha mutant in HCT116 cells resulted in a complete inhibition of the NF-kappaB activation but only a partial impairment of the p53 protein accumulation induced by daunomycin. We conclude that the p53-activating signal generated by daunomycin is partially regulated by NF-kappaB.
Insights
Daunomycin, an anthracycline drug, effectively induces p53 and NF-kappaB transcription factors in colon cancer cells. This study reveals NF-kappaB partially regulates the p53-activating signal triggered by daunomycin.
Area of Science:
- Molecular Biology
- Cancer Research
- Pharmacology
Background:
- Anthracycline drugs are crucial for treating solid tumors and leukemia, yet their precise molecular mechanisms remain unclear.
- Understanding the cellular response to anthracyclines like daunomycin is vital for optimizing cancer therapy.
- The p53 and NF-kappaB pathways are critical in cancer development and drug response.
Purpose of the Study:
- To investigate the molecular basis of daunomycin's biological effects in HCT116 colon carcinoma cells.
- To determine the roles of p53 and NF-kappaB transcription factors in the cellular response to daunomycin.
- To elucidate the signaling pathways involved in daunomycin-induced p53 activation.
Main Methods:
- Utilized the HCT116 colon carcinoma cell line with a wild-type inducible p53 gene.
- Assessed the induction of p53 and NF-kappaB transcription factors following daunomycin treatment.
- Investigated the mechanisms of p53 nuclear accumulation, including protein stability and gene expression.
- Analyzed the regulation of the p53 promoter by NF-kappaB heterodimers.
- Examined the involvement of reactive oxygen species using free radical scavengers (NAC, PDTC).
- Employed overexpression of a stable IkappaBalpha mutant to inhibit NF-kappaB activation.
Main Results:
- Daunomycin was identified as a potent inducer of both p53 and NF-kappaB in HCT116 cells.
- Daunomycin enhanced p53 protein stability and gene expression, leading to nuclear accumulation.
- NF-kappaB (p50/p65 heterodimers) directly induced the p53 promoter by binding to the kappaB site.
- Reactive oxygen intermediates were not implicated in the cellular response to daunomycin.
- Inhibition of NF-kappaB activation partially impaired daunomycin-induced p53 accumulation, suggesting partial regulation.
Conclusions:
- Daunomycin treatment leads to significant induction of p53 and NF-kappaB in colon carcinoma cells.
- The p53-activating signal induced by daunomycin is, in part, regulated by the NF-kappaB pathway.
- These findings contribute to a better understanding of anthracycline mechanisms in cancer treatment.