In our on-going studies, we have found that serum tryptase appears to reflect extent of disease and to serve as a biomarker of both disease regression and progression. We are also increasing our enrollment of families with more than one affected family member in order to investigate genetic associations. We are also documenting bone marrow biopsy findings that may similarly be used to predict disease progression and may lead the way to an improved classification of pediatric onset mastocytosis. Activating mutations in codon D816 of the tyrosine kinase receptor, KIT, are found in the majority of patients with systemic mastocytosis. In a collaboration with Dr. Takemoto and his research group, we found that the transcription factor, microphthalmia-associated transcription factor (MITF), is highly expressed in bone marrow biopsies from patients with systemic mastocytosis and activating c-KIT mutations and that KIT signaling markedly up-regulates MITF protein. MITF mRNA levels did not change significantly with KIT signaling which suggested posttranscriptional regulation. An array screen from mast cells identified miR-539 and miR-381 as being down-regulated by KIT signaling and that they repressed MITF expression through conserved miRNA binding sites in the MITF 3'-untranslated region. Forced expression of these miRNAs suppressed MITF protein and inhibited colony-forming capacity of mastocytosis cell lines, supporting the conclusion that a novel regulatory pathway exists between 2 critical mast cell factors, KIT and MITF which is mediated by miRNAs.

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Smrž, Daniel; Wilson, Todd M; Metcalfe, Dean D et al. (2012) Providing the TORC for cell cycle progression in neoplastic mast cells. Cell Cycle 11:210-1
Castells, Mariana; Metcalfe, Dean D; Escribano, Luis (2011) Diagnosis and treatment of cutaneous mastocytosis in children: practical recommendations. Am J Clin Dermatol 12:259-70
Lee, Youl-Nam; Brandal, Stephanie; Noel, Pierre et al. (2011) KIT signaling regulates MITF expression through miRNAs in normal and malignant mast cell proliferation. Blood 117:3629-40
Smrz, Daniel; Kim, Mi-Sun; Zhang, Shuling et al. (2011) mTORC1 and mTORC2 differentially regulate homeostasis of neoplastic and non-neoplastic human mast cells. Blood 118:6803-13
Uzzaman, Ashraf; Maric, Irina; Noel, Pierre et al. (2009) Pediatric-onset mastocytosis: a long term clinical follow-up and correlation with bone marrow histopathology. Pediatr Blood Cancer 53:629-34
Raymond, Wilfred W; Su, Sharon; Makarova, Anastasia et al. (2009) Alpha 2-macroglobulin capture allows detection of mast cell chymase in serum and creates a reservoir of angiotensin II-generating activity. J Immunol 182:5770-7