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A. Thomas Look, MD

Pediatric Hematology/Oncology


  • Professor of Pediatrics, Harvard Medical School

Contact Information

  • Office Phone Number(617) 632-5826
  • Fax(617) 632-6989


Dr. Look received his MD in 1975 and residency training in pediatrics at the University of Michigan. He completed a fellowship in pediatric oncology at St. Jude Children's Research Hospital, where he trained in the molecular biology of cancer and eventually became chair of the Experimental Oncology Department. In 1999, he joined DFCI as vice chair for research in the Department of Pediatric Oncology.

Recent Awards:

  • Second Annual Giulio J. D'Angio Lecturer, University of Pennsylvania Cancer Center 1999
  • Award for Excellence in Pediatric Research, American Academy of Pediatrics 1995
  • 2nd Annual Lecturer in Leukemia at The Hospital for Sick Children, Toronto, Canada 2000
  • ASPHO Frank A. Oski Memorial Lectureship Award 2005
  • Member, Association of American Physicians 2005


Genetic Models of Leukemogenesis and Neuroblastoma

We are using zebrafish, in combination with murine and cell culture systems, to dissect developmental pathways subverted in human cancer. Zebrafish have been shown to share conserved pathways of development and disease pathogenesis with humans, thus permitting the identification of novel genes that are activated (oncogenes) or inactivated (tumor suppressors) during malignant transformation. We are using transgenic strategies to generate conditional zebrafish models of leukemias and solid tumors.We have identified novel genes regulating myelopoiesis, and are currently studying their respective contributions to the molecular pathogenesis of myelodysplastic syndrome and acute myeloid leukemia. We are applying similar approaches to study peripheral sympathetic nervous system development and to identify tumor suppressors in childhood neuroblastoma. We have also isolated a tumor-prone, mutant p53 zebrafish to study pathways involving this key regulator of DNA repair, cell cycle regulation, and apoptosis. p53 is the most commonly mutated gene in human cancers, and our zebrafish model is allowing us to study its role in several types of cancer.Our most advanced zebrafish model involves a transgenic line that develops T cell acute lymphoblastic leukemia (T-ALL). We are using this model to conduct one of the first cancer-related vertebrate genetic modifier screens, which will allow us to identify enhancers and suppressors of T-ALL progression. Using in vitro genome-scale location analysis (GSLA), we are also identifying the direct targets of oncogenic transcription factors and validating candidate target genes utilizing short interfering RNA strategies in human T-ALL cell lines. Through the combined use of these approaches, we hope to uncover novel genes and targets for the development of small-molecule inhibitors as therapeutics.In addition, we are studying apoptotic pathways controlled by the Slug transcription factor. We have shown that, in developing blood cells, DNA damage and p53 induction leads to the activation of Slug, which itself is a direct repressor of puma, a pro-apoptotic BH3-only protein. Mice deficient in both genes survive irradiation doses that are lethal to mice lacking Slug alone. Thus, Slug provides a novel mechanism downstream of p53 to ensure cell survival, rescuing damaged hematopoietic progenitors from programmed cell death, and allowing restorative repopulation of blood cells after radiation and other insults that cause DNA damage.

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