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Microarray analysis of UVB-regulated genes in keratinocytes: downregulation of angiogenesis inhibitor
1Department of Dermatology, Johns Hopkins Outpatient Center, Johns Hopkins University, 601 N. Caroline Street, Room 6068, Baltimore, MD, USA.
Background:
Ultraviolet (UV) B light is an environmental mutagen that induces changes in cutaneous gene expression leading to immune suppression and carcinogenesis. Keratinocytes are a primary target for UVB.
Objective:
To further delineate UVB-induced gene expression changes in keratinocytes.
Methods:
cDNA microarray technology was utilized to examine gene expression in normal human KC (NHKC) following 20 mJcm(-2) UVB irradiation. Data was confirmed by semi-quantitative RT-PCR.
Results:
Microarray analysis revealed 57 genes were upregulated, and 27 genes were downregulated, by at least two-fold following UVB. One downregulated gene was the endogenous angiogenesis inhibitor thrombospondin-1 (TSP-1). Semi-quantitative RT-PCR confirmed persistent downregulation of TSP-1 up to 18h following UVB. Microarray analysis also revealed upregulation of platelet-derived endothelial cell growth factor (PD-ECGF)--an angiogenesis activator.
Conclusion:
Our results suggest a gene expression mechanism by which UVB induces an angiogenic switch in keratinocytes. This may represent an important early event promoting neovascularization and growth of cutaneous neoplasms.
Insights
Ultraviolet (UV) B light alters gene expression in skin cells, potentially promoting cancer. UVB exposure downregulates thrombospondin-1 (TSP-1) and upregulates platelet-derived endothelial cell growth factor (PD-ECGF), suggesting a mechanism for tumor growth.
Area of Science:
- Dermatology
- Molecular Biology
- Oncology
Background:
- Ultraviolet (UV) B radiation is a known environmental mutagen.
- UVB exposure induces changes in skin gene expression, leading to immune suppression and skin cancer.
- Keratinocytes are a primary cellular target for UVB damage.
Purpose of the Study:
- To investigate UVB-induced gene expression alterations in keratinocytes.
- To identify specific genes affected by UVB irradiation in skin cells.
Main Methods:
- Utilized cDNA microarray technology to analyze gene expression in normal human keratinocytes (NHKC).
- Quantified gene expression changes following a dose of 20 mJcm(-2) UVB irradiation.
- Confirmed key gene expression changes using semi-quantitative reverse transcription polymerase chain reaction (RT-PCR).
Main Results:
- Microarray analysis identified 57 upregulated and 27 downregulated genes (at least two-fold change) after UVB exposure.
- Thrombospondin-1 (TSP-1), an endogenous angiogenesis inhibitor, was significantly downregulated.
- Platelet-derived endothelial cell growth factor (PD-ECGF), an angiogenesis activator, was upregulated.
- RT-PCR confirmed sustained downregulation of TSP-1 for up to 18 hours post-UVB exposure.
Conclusions:
- UVB exposure induces significant gene expression changes in keratinocytes.
- These alterations include the downregulation of angiogenesis inhibitors and upregulation of pro-angiogenic factors.
- This UVB-induced "angiogenic switch" in keratinocytes may be a critical early step in the development of skin tumors.
