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Inhibition of collagen gene expression in systemic sclerosis dermal fibroblasts by mithramycin
N Sandorfi1, N Louneva, E Hitraya
1Division of Rheumatology, Department of medicine, Thomas Jefferson University, Philadelphia, PA 19107-5041, USA.
Background:
The anti-tumour antibiotic mithramycin is also a potent inhibitor of fibrosis after glaucoma surgery. This drug displays high affinity binding to GC-rich sequences in DNA, including those present in the promoter of the gene encoding the alpha1 chain of type I collagen (COL1A1).
Objective:
To evaluate the effects of mithramycin on COL1A1 expression in systemic sclerosis fibroblasts.
Methods:
Confluent cultures of dermal fibroblasts from patients with recent onset diffuse systemic sclerosis were treated with mithramycin in vitro. Cell viability and protein expression were examined by fluorescence and confocal imaging. Type I collagen production was analysed by confocal imaging and metabolic labelling. COL1A1 messenger RNA levels and stability were assessed by northern hybridisation, and COL1A1 transcription was examined by transient transfections.
Results:
Treatment of systemic sclerosis fibroblasts with mithramycin (10-100 nmol/l) did not cause significant cytotoxicity. Type I collagen biosynthesis decreased by 33-40% and 50-70% in cells cultured with mithramycin at 10 nmol/l and 100 nmol/l, respectively. Mithramycin at 50 nmol/l decreased COL1A1 mRNA levels by 40-60%. The effects of mithramycin on collagen gene expression were mediated by transcriptional and post-transcriptional mechanisms as shown by the reduction of COL1A1 promoter activity and by a decrease in the stability of these transcripts, respectively.
Conclusions:
Mithramycin causes potent inhibition of collagen production and gene expression in systemic sclerosis dermal fibroblasts in vitro in the absence of cytotoxic effects. These results suggest that this drug may be an effective treatment for the fibrotic process which is the hallmark of systemic sclerosis.
Insights
Mithramycin effectively inhibits collagen production in systemic sclerosis fibroblasts by reducing COL1A1 gene expression and protein synthesis without causing cytotoxicity. This suggests potential therapeutic applications for fibrotic diseases.
Area of Science:
- Pharmacology
- Molecular Biology
- Dermatology
Background:
- Mithramycin, an anti-tumor antibiotic, inhibits fibrosis and binds GC-rich DNA sequences.
- It targets the COL1A1 gene promoter, crucial for type I collagen production.
Purpose of the Study:
- To investigate mithramycin's impact on COL1A1 gene expression in systemic sclerosis (SSc) fibroblasts.
- To assess the drug's efficacy and safety in treating SSc-related fibrosis.
Main Methods:
- Systemic sclerosis fibroblasts were treated with varying concentrations of mithramycin in vitro.
- Assessed cell viability, collagen production, COL1A1 mRNA levels, and transcription.
- Utilized fluorescence imaging, confocal microscopy, metabolic labeling, northern hybridization, and transient transfections.
Main Results:
- Mithramycin treatment showed no significant cytotoxicity in SSc fibroblasts.
- Type I collagen biosynthesis decreased by 33-70% with increasing mithramycin concentrations (10-100 nmol/l).
- COL1A1 mRNA levels reduced by 40-60% at 50 nmol/l, with effects mediated by transcriptional and post-transcriptional mechanisms.
Conclusions:
- Mithramycin potently inhibits collagen production and gene expression in SSc dermal fibroblasts.
- The drug acts via both transcriptional repression and decreased mRNA stability.
- Mithramycin shows promise as a treatment for the fibrotic processes characteristic of systemic sclerosis.
