Fluorescent-labeled zebrafish RAS-induced embryonal rhabdomyosarcoma (ERMS) were created to facilitate in vivo imaging of tumor-propagating cells, regional tumor heterogeneity, and dynamic cell movements in diverse cellular compartments. Using this strategy, we have identified a molecularly distinct ERMS cell subpopulation that expresses high levels of myf5 and is enriched for ERMS-propagating potential when compared with other tumor-derived cells. Embryonal rhabdomyosarcoma (ERMS) is an aggressive pediatric sarcoma of muscle. Here, we show that tumor-propagating potential is confined to myf5+ERMS cells and can be visualized in live, fluorescent transgenic zebrafish. During early tumor growth, myf5+ERMS cells reside within an expanded satellite cell compartment, but by late stage ERMS, myf5+cells are dynamically reorganized into distinct regions separated from differentiated tumor cells. Human ERMS also contain distinct areas of differentiated and undifferentiated cells. Time-lapse imaging revealed that myf5+ERMS cells populate newly formed tumor only after seeding by highly migratory myogenin+ ERMS cells. This finding helps explain the clinical observation that Myogenin positivity correlates with poor clinical outcome in human ERMS and suggests that differentiated tumor cells play critical roles in metastasis. One-cell stage myf5-GFP/mylz2-mCherry fluorescent transgenic zebrafish were injected with rag2-kRAS12D. A subset of animals developed ERMS. Tumor cells were transplanted into syngeneic recipient animals that lacked fluorescent reporter expression. ERMS cell subfractions were isolated from transplant animals and purified cell populations obtained following two rounds of FACS. Sorted cells were 1) analyzed by microarray/RT-PCR and 2) transplanted at limiting dilution into syngeneic animals. These experiments confirm that zebrafish ERMS contain molecularly distinct cell subfractions that express high levels of myf5-GFP and exhibit difference in gene expression when compared to other ERMS cell subtypes. All four fluorescent-labeled cell populations were analyzed (n=2 tumors total).
In vivo imaging of tumor-propagating cells, regional tumor heterogeneity, and dynamic cell movements in embryonal rhabdomyosarcoma.
Specimen part, Disease, Disease stage, Subject
View SamplesAlmost all human pancreatic ductal adenocarcinomas (PDACs) are driven by oncogenic Kras and the progression of the disease is characterized by the serial appearance of certain genetic lesions. Mouse models have convincingly shown that Kras mutation induces classical PanIN lesions that can progress to PDAC in the appropriate tumor suppressor background. However, the cooperative mechanism between mutant Kras-dependent signaling surrogates and other oncogenic pathways remains to be fully elucidated in order to devise better therapeutic strategy. Mounting evidence PTEN/PI3K perturbation on PDAC tumorigenesis, we observed frequent PTEN inactivation at both genomic and histopathological levels in primary human PDAC samples. The importance of PTEN/PI3K pathway during the development of PDAC was further supported by genetic studies demonstrating that Pten deficiency in cooperation with Kras activation accelerated the formation of invasive PDAC. Mechanistically, combined Kras mutation and Pten inactivation leads to NFkB activation and subsequent induction of cytokine pathways, accompanied with strong stromal activation and immune cell infiltration. Therefore, PTEN/PI3K pathway dictates the activity of NFkB network and serves as a major surrogate during Kras-mediated pancreatic tumorigenesis.
PTEN is a major tumor suppressor in pancreatic ductal adenocarcinoma and regulates an NF-κB-cytokine network.
Specimen part
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