Intravital imaging of melanoma in combination with molecular analysis reveals key changes in stromal ECM and tumor behavior in persistence against MEKi

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  • March 20, 2019
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  • Brighton, Hailey
    • Affiliation: School of Medicine, Department of Cell Biology and Physiology
Abstract
  • Melanoma is a devastating disease, and while a number of targeted therapies are used to treat patients with malignant melanoma, tumors become resistant. Understanding tumor response to targeted therapies and how therapeutic strategies fail is a critical challenge in modern oncology. To investigate tumor behavior and response to a selective small molecule inhibitor of MEK1/2 (Trametinib) in vivo, we developed an intravital imaging approach to directly visualize drug response in a BRAFV600E/PTEN-null mouse model of melanoma by genetically incorporating a tdTomato fluorescent reporter allele (tdTomatoLSL). Through highly localized application of tamoxifen (4-HT) and noninvasive, serial intravital microscopy, I was able to directly visualize formation and progression of tumors at the single cell level in situ longitudinally over time. I directly imaged primary tumors in mice throughout treatment with MEKi and observed changes in tumor cell behavior during drug response for twelve weeks. I identified a clear relationship between bundled collagen and tumor cell survival in response to MEKi and collaborated with the Johnson lab to couple this model with transcriptome and kinome reprogramming analysis. Molecular analysis of tumors at early and late stages on MEKi identified a phenotypic shift toward an epithelial phenotype, characterized by c-Kit activity and the induction of a EMT_down and PI3K/AKT survival pathway signatures for melanoma persistence in vivo. Together, these approaches give a holistic view of the complex changes of tumor cells and stromal tissue in response to targeted therapy and provide insight for future treatment strategies.
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  • In Copyright
Advisor
  • Sharpless, Norman
  • Dudley, Andrew
  • Burridge, Keith
  • Kim, William
  • Bear, James
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2017
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