Making sense of Cbp/p300 loss of function mutations in skin tumorigenesis

Area of Science:

• Oncology
• Molecular Biology
• Dermatology

Background:

• CBP and p300 are homologous lysine acetyltransferases crucial for cell cycle regulation, DNA synthesis, and repair.
• Loss-of-function mutations in CBP/p300 occur in approximately one-third of cutaneous squamous cell carcinoma (cSCC) cases, often co-occurring.
• The precise role of CBP/p300 in cSCC pathogenesis remains unclear.

Purpose of the Study:

• To investigate the role of combined heterozygous loss of CBP/p300 in the pathogenesis of cSCC.
• To establish a mechanistic framework for understanding how CBP/p300 mutations contribute to skin tumorigenesis.

Main Methods:

• Modeling combined heterozygous loss of Cbp/p300 in mouse keratinocytes.
• Utilizing a transgenic HrasS35 allele for selective coupling of Hras to the Erk pathway.
• Analyzing epidermal changes, tumor development, and molecular signaling pathways.

Main Results:

• Reduced dosage of Cbp/p300 exacerbated HrasS35-induced epidermal thickening, leading to skin papillomas.
• This phenotype was linked to decreased expression of Mig6, an Egfr feedback inhibitor.
• Enhanced Egfr signaling to the Ras-Erk pathway was observed, contributing to tumor development.

Conclusions:

• The study provides a mechanistic model for how CBP/p300 loss-of-function mutations drive skin tumorigenesis.
• Findings suggest potential therapeutic strategies targeting CBP/p300-mutated human cSCC.