Melanoma is a cancer with high mortality and is projected to cause almost eight thousand deaths during 2008 in the US alone. Though the carcinogenic mechanisms that lead to melanoma remain poorly understood, melanoma is thought to originate from a rare melanocyte stem cell that resides in the skin. Recently, we have found that the transcription Pax3 is expressed by these uncommon melanocyte stem cells. Although Pax3 is required for melanocyte development during embryogenesis, it not found in normal mature melanocytes. Its presence in melanocyte precursors therefore suggests that Pax3 promotes a melanocytic commitment but blocks terminal melanocyte differentiation. If this proposed schema is true, then in normal melanocyte precursors, maintenance of Pax3 expression preserves pluripotency, and its repression induces differentiation. If Pax3 plays these roles in melanocytes, then persistent Pax3 expression might result in the uncontrolled cell growth and loss of terminal differentiation in melanomas. Indeed, we have shown that Pax3 is expressed in melanoma cell lines and primary tumors. The major objective of this application is to elucidate the mechanisms by which Pax3 regulates melanocyte stem cell maturation and how this protein becomes subverted in conversion to a malignant state. The long range goals of our studies are to determine the molecular biology of the melanocyte stem cell in mature skin and how these pathways are disrupted in melanoma. The hypothesis guiding this proposal is that Pax3 regulates a critical control point in the normal maintenance of melanocyte stem cells and this control point is dysegulated in melanoma cells.
In Aim I we exploit the cell restricted expression pattern of Pax3 in the melanocyte stem cell to create mouse models for isolation and study of this rare cell population. We also target Pax3 in these cells to test the necessity of Pax3 in melanocyte precursors.
In Aim II, we investigate the role of Pax3 in melanomas to determine whether and how this protein contributes to the tumor phenotype. Finally in Aim III we explore the role of the canonical Wnt signaling pathway in the melanocyte stem cell and how members of this pathway affect Pax3 function.

Public Health Relevance

Within adults, there are tissue specific stem cells that have the extraordinary ability to maintain and repair their specialized tissue by dividing and generating new cells. Unfortunately, these same qualities that stem cells possess in terms of growth and survival are also found in cancer cells. Our proposal seeks to determine normal molecular pathways of stem cells and to how they become subverted in the conversion into tumors.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA130202-04
Application #
8197856
Study Section
Development - 2 Study Section (DEV2)
Program Officer
Watson, Joanna M
Project Start
2009-02-01
Project End
2013-12-31
Budget Start
2012-01-01
Budget End
2012-12-31
Support Year
4
Fiscal Year
2012
Total Cost
$313,989
Indirect Cost
$112,714
Name
University of Chicago
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
005421136
City
Chicago
State
IL
Country
United States
Zip Code
60637
Kubic, J D; Little, E C; Lui, J W et al. (2015) PAX3 and ETS1 synergistically activate MET expression in melanoma cells. Oncogene 34:4964-74
Lang, Deborah; Mascarenhas, Joseph B; Shea, Christopher R (2013) Melanocytes, melanocyte stem cells, and melanoma stem cells. Clin Dermatol 31:166-78
Mascarenhas, Joseph B; Littlejohn, Erica L; Wolsky, Rebecca J et al. (2010) PAX3 and SOX10 activate MET receptor expression in melanoma. Pigment Cell Melanoma Res 23:225-37
Mascarenhas, Joseph B; Young, Kacey P; Littlejohn, Erica L et al. (2009) PAX6 is expressed in pancreatic cancer and actively participates in cancer progression through activation of the MET tyrosine kinase receptor gene. J Biol Chem 284:27524-32
Kubic, Jennifer D; Young, Kacey P; Plummer, Rebecca S et al. (2008) Pigmentation PAX-ways: the role of Pax3 in melanogenesis, melanocyte stem cell maintenance, and disease. Pigment Cell Melanoma Res 21:627-45
Plummer, Rebecca S; Shea, Christopher R; Nelson, Maria et al. (2008) PAX3 expression in primary melanomas and nevi. Mod Pathol 21:525-30