The goal of this proposal is to identify the earliest melanoma precursors and to study the mechanisms of intraepidermal melanoma progression. Recent studies have identified a field effect comprised of genetically abnormal melanocytes in the non-lesional skin adjacent to primary melanomas. Evidence suggests that these field cells may be a source of local recurrences. The field effect appears to be confined to melanomas with a lentiginous growth pattern i.e. an intraepidermal growth pattern in which melanocytes are arranged as single units within the basilar epidermis such as acral and lentigo maligna melanomas. These melanoma types frequently have activating genetic alterations in the KIT signaling pathway. Since KIT has an essential role in melanocyte migration and homing of melanoblasts to the basal dermis, the hypothesis is that KIT pathway activation represents the initiating event that is subsequently followed by the acquisition of additional genetic alterations required to form clinically and histologically detectable lesions. To test this hypothesis, the candidate has developed a xenograft model of early human melanoma progression. Specifically, she will study the intraepidermal migration of genetically engineered melanocytes and melanoma cells expressing relevant KIT mutations seeded into human skin reconstructs grafted onto immunodeficient mice. In parallel, the candidate will evaluate the impact of KIT inhibitors on intraepidermal melanoma progression. These studies will provide an explanation for the tendency of certain melanoma types to recur after apparently complete excision and will offer the possibility to use KIT inhibitors to treat early melanoma.

Public Health Relevance

Melanoma is a malignant tumor arising from melanocytes. Melanomas have a high tendency to recur despite apparently clear surgical margins. We hypothesize that the origin of melanoma recurrences are cells that carry a mutation on a gene (KIT). Our studies will provide an explanation for the tendency of certain melanoma types to recur after apparently complete excision and will offer the possibility to use KIT inhibitors to treat early melanoma. The written critiques and criteria scores of individual reviewers are provided in essentially unedited form in the Critique section below. Please note that these critiques and criteria scores were prepared prior to the meeting and may not have been revised subsequent to any discussions at the review meeting. The Resume and Summary of Discussion section above summarizes the final opinions of the committee.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Clinical Investigator Award (CIA) (K08)
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Study Section
Subcommittee G - Education (NCI)
Program Officer
Perkins, Susan N
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University of California San Francisco
Schools of Medicine
San Francisco
United States
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Latorre, Alfonso; Posch, Christian; Garcimartín, Yolanda et al. (2014) Single-point mutation detection in RNA extracts using gold nanoparticles modified with hydrophobic molecular beacon-like structures. Chem Commun (Camb) 50:3018-20
Vujic, Igor; Posch, Christian; Sanlorenzo, Martina et al. (2014) Mutant NRASQ61 shares signaling similarities across various cancer types--potential implications for future therapies. Oncotarget 5:7936-44
Sanlorenzo, Martina; Choudhry, Aditi; Vujic, Igor et al. (2014) Comparative profile of cutaneous adverse events: BRAF/MEK inhibitor combination therapy versus BRAF monotherapy in melanoma. J Am Acad Dermatol 71:1102-1109.e1
Posch, Christian; Moslehi, Homayoun; Feeney, Luzviminda et al. (2013) Combined targeting of MEK and PI3K/mTOR effector pathways is necessary to effectively inhibit NRAS mutant melanoma in vitro and in vivo. Proc Natl Acad Sci U S A 110:4015-20