Murine & Human In Vivo Models of Melanoma Formation

Univ Of North Carolina Chapel Hill, Chapel Hill NC

Investigators

Linked publications & trials

Abstract

Project 3 utilizes human and murine model systems to address the links between signature genetic events in melanoma progression (p16INK4a loss and N-RAS/B-RAF mutation) and the DMAdamage response in melanocytes. This project combines analyses of novel murine models of melanoma with a comprehensive molecular and immunohistochemical study of a large, clinically annotated human melanoma database. In specific aim 1, we combine two different RAS alleles, conditionally inactivatable p53 and p16INK4a alleles, and an inducible, melanocyte-specific CRE allele to produce new murine models of melanoma that are highly faithful to the human genetics of this tumor. In these models, all oncogenic events are restricted to the melanocytic compartment, and include somatic inactivation of p16/p53 or somatic activation of K-RAS, Two of the alleles (Tyr-CRE-ER-T and conditional p16INK4a) are newly characterized and unpublished. In specific aim 2, we combine these novel murine models of melanoma with neonatal UV-B exposure to facilitate in vivo melanomagenesis. Specific aim 2 also includes a detailed immunohistochemical analysis of the kinetics of the expression of markers of the DNA damage response and senescence with or without UV- B treatment in the setting of RAS activation, p16INK4a loss and/or p53 loss. This specific aim employs a similar approach to analyze human dermal reconstructs in immunodeficient mice with and without UV exposure using reagents supplied from projects 1 and 2. In specific aim 3, we extend our analysis of human primary formalin-fixed and paraffin-embedded melanocytic lesions to identify the relationship among RAS/RAF/p16INK4a mutation, ERK MAP kinase activation, senescence and the DNA damage response in the progression from nevus to metastatic tumor. This specific aim includes a comprehensive immunohistochemical analysis of several markers of the DNA damage response and senescence, as well as a mutational analysis of N-RAS, B-RAF and p16INK4a. This specific aim is powered (250 melanocytic lesions from nevus to metaststic melanoma) to account for molecular heterogeneity in primary tumors but still uncover biologically significant relationships among these signature genetic events, the DNA damage response and melanoma progression. We expect this work will further our basic understanding of human melanoma progression as well as identify new clinjcal predictors of disease progression and outcome.