Growth factor and proto-oncogene expression in psoriasis.

Area of Science:

• Dermatology
• Molecular Biology
• Oncology

Background:

• Psoriasis is a chronic inflammatory skin disease characterized by epidermal hyperplasia.
• Proto-oncogenes and growth factors play critical roles in cell proliferation and differentiation.

Purpose of the Study:

• To investigate the expression patterns of key proto-oncogenes and growth factors in normal skin versus psoriatic lesions.
• To determine the potential role of specific growth factors, like TGF-alpha, in the pathogenesis of psoriatic epidermal hyperplasia.

Main Methods:

• RNA blot hybridization was used to analyze gene expression in frozen skin biopsy samples.
• Lipocortin II and cyclophilin transcripts served as internal controls for normalization.
• Organ culture and cytokine treatments were employed to study gene induction dynamics.

Main Results:

• Transforming growth factor-alpha (TGF-alpha) mRNA levels were markedly increased in psoriatic lesions compared to normal skin.
• Expression of c-myc, c-Ha-ras, c-erbB (EGF receptor), c-jun, and TGF-beta showed no significant increase, while c-fos decreased in lesions.
• Short-term incubation of skin tissue induced c-fos, c-jun, and c-myc, suggesting a response to acute injury rather than chronic hyperplasia.
• Interferon-gamma (IFN-gamma), EGF, and TGF-alpha influenced TGF-alpha mRNA levels in cultured keratinocytes.

Conclusions:

• The selective overabundance of TGF-alpha mRNA in psoriatic lesions points to its significant role in the pathogenesis of epidermal hyperplasia.
• Activation of the epidermal growth factor receptor (EGF receptor) tyrosine kinase by TGF-alpha is likely crucial in psoriasis.
• Proto-oncogene overexpression might be more indicative of acute skin injury responses than the steady-state hyperplasia seen in psoriasis.