Downregulation of TNF-alpha and VEGF expression by Sp1 decoy oligodeoxynucleotides in mouse melanoma tumor
E M Novak1, M Metzger, R Chammas
1Research and Molecular Biology Division, Pró-Sangue Hemocentro de São Paulo Foundation, São Paulo, Brazil. enovak@usp.br
Abstract:
Melanoma tumor growth and progression are highly dependent on adequate blood supply through angiogenesis. Since several genes involved in angiogenesis revealed potential binding sites for the transcription factor Sp1, we have examined the effects of local inoculation of Sp1 decoy oligodeoxynucleotides (ODNs) on the growth of transplanted murine melanoma tumors and the expression of VEGF and TNF-alpha within these tumors. Treatment with Sp1 decoy ODNs, but not their mutated form, led to a significant increase (P=0.041) of the tumor necrotic area, as evaluated morphometrically. Tumor necrosis was associated with a significant decrease of microvascular density (P=0.012) and relative vascular area (P=0.026), as determined by counting CD34-positive vascular structures within the tumor microenvironment of Sp1 decoy ODNs and control ODN-treated tumors. RT-PCR experiments showed a strong decrease in the levels of VEGF188 and VEGF164 isoforms and a moderate decrease of TNF-alpha in Sp1 decoy-treated tumors. Taken together, our results indicate that Sp1 decoy ODNs may inhibit angiogenesis by affecting the gene expression of key players in angiogenesis such as TNF-alpha and VEGF. These findings indicate that Sp1 decoy ODNs may be a potential new therapeutic tool in antiangiogenic therapy.
Insights
Sp1 decoy oligodeoxynucleotides (ODNs) significantly increased melanoma tumor necrosis by inhibiting angiogenesis. This suggests Sp1 decoy ODNs are a promising therapeutic for antiangiogenic therapy.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Melanoma tumor growth relies on angiogenesis.
- Transcription factor Sp1 influences genes crucial for angiogenesis.
Purpose of the Study:
- To investigate the impact of Sp1 decoy oligodeoxynucleotides (ODNs) on melanoma tumor growth.
- To assess the effect of Sp1 decoy ODNs on VEGF and TNF-alpha expression in tumors.
Main Methods:
- Local inoculation of Sp1 decoy ODNs and control ODNs in murine melanoma models.
- Morphometric evaluation of tumor necrotic area.
- Assessment of microvascular density and vascular area using CD34 staining.
- Quantitative analysis of VEGF and TNF-alpha gene expression via RT-PCR.
Main Results:
- Sp1 decoy ODNs significantly increased tumor necrotic area (P=0.041).
- Treatment led to decreased microvascular density (P=0.012) and relative vascular area (P=0.026).
- Reduced expression of VEGF (188 and 164 isoforms) and TNF-alpha was observed.
Conclusions:
- Sp1 decoy ODNs inhibit melanoma angiogenesis by downregulating VEGF and TNF-alpha.
- Sp1 decoy ODNs represent a potential therapeutic strategy for antiangiogenic therapy in melanoma.
