Project description:Background: Alveolar rhabdomyosarcoma (ARMS) has a high propensity to metastasize, leading to its aggressiveness and a poor survival rate among those with the disease. More than 80% of aggressive ARMSs harbor a PAX3-FKHR fusion transcription factor, which regulates cell migration and promotes metastasis, most likely by regulating the fusion protein's transcriptional targets. Therefore, identifying druggable transcription targets of PAX3-FKHR that are also downstream effectors of PAX3-FKHR-mediated cell migration and metastasis may lead to novel therapeutic approaches for treating ARMS. Methods: To identify genes whose expression is directly affected by the level of PAX3-FKHR in an ARMS cellular-context, we first developed an ARMS cell line in which PAX3-FKHR is stably down-regulated, and showed that stably downregulating PAX3-FKHR in ARMS cells significantly decreased the cells' motility. We used microarrays analysis to identify genes whose expression level decreased when PAX3-FKHR was downregulated. We used mutational analysis, promoter reporter assays, and electrophoretic mobility shift assays to determine whether PAX3-FKHR binds directly and specifically to the promoter region of the target gene. We used siRNA and pharmacologic inhibitor to downregulate the target gene of PAX3-FKHR and investigated the effect of such downregulation on cell motility, Results: We found that When PAX3-FKHR was downregulated, the expression of carnitine palmitoyltransferase 1A (CPT1A) decreased. We showed that PAX3-FKHR binds directly and specifically to a paired-domain binding-site in the CPT1A promoter region, indicating that CPT1A is a novel direct transcriptional target of PAX3-FKHR. Furthermore, downregulating CPT1Adecreased cell motility in ARMS cells, indicating that CPT1A is a downstream effector of PAX3-FKHR-mediated cell migration and metastasis. Conclusions: Taken together, we have identified CPT1A as a novel direct transcriptional target of PAX3-FKHR and revealed the novel function of CPT1A in promoting cell motility. CPT1A may represent a novel therapeutic target for the treatment of ARMS.

Project description:Background: Alveolar rhabdomyosarcoma (ARMS) has a high propensity to metastasize, leading to its aggressiveness and a poor survival rate among those with the disease. More than 80% of aggressive ARMSs harbor a PAX3-FKHR fusion transcription factor, which regulates cell migration and promotes metastasis, most likely by regulating the fusion protein's transcriptional targets. Therefore, identifying druggable transcription targets of PAX3-FKHR that are also downstream effectors of PAX3-FKHR-mediated cell migration and metastasis may lead to novel therapeutic approaches for treating ARMS. Methods: To identify genes whose expression is directly affected by the level of PAX3-FKHR in an ARMS cellular-context, we first developed an ARMS cell line in which PAX3-FKHR is stably down-regulated, and showed that stably downregulating PAX3-FKHR in ARMS cells significantly decreased the cells' motility. We used microarrays analysis to identify genes whose expression level decreased when PAX3-FKHR was downregulated. We used mutational analysis, promoter reporter assays, and electrophoretic mobility shift assays to determine whether PAX3-FKHR binds directly and specifically to the promoter region of the target gene. We used siRNA and pharmacologic inhibitor to downregulate the target gene of PAX3-FKHR and investigated the effect of such downregulation on cell motility, Results: We found that When PAX3-FKHR was downregulated, the expression of carnitine palmitoyltransferase 1A (CPT1A) decreased. We showed that PAX3-FKHR binds directly and specifically to a paired-domain binding-site in the CPT1A promoter region, indicating that CPT1A is a novel direct transcriptional target of PAX3-FKHR. Furthermore, downregulating CPT1Adecreased cell motility in ARMS cells, indicating that CPT1A is a downstream effector of PAX3-FKHR-mediated cell migration and metastasis. Conclusions: Taken together, we have identified CPT1A as a novel direct transcriptional target of PAX3-FKHR and revealed the novel function of CPT1A in promoting cell motility. CPT1A may represent a novel therapeutic target for the treatment of ARMS. Identification of transcription targets of PAX3-FKHR in human alveolar rhabdomyosarcoma: By stably knocking down PAX3-FKHR in human alveolar rhabdomyosarcoma cell line Rh30 and comparing the gene expression profile of the knockdown clone (KD) to the parental Rh30, transcription targets of PAX3-FKHR have been identified. Gene expression in parental Rh30 cells was compared to that in either Rh30 cells stably expressing shRNA targeting PAX3-FKHR (KD) or control non-targeting shRNA (CON), in duplicate.

Project description: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).

Dataset Information

Transcription profiling of human embryonal rhabdomyosarcoma (EMRS) culture to identify PAX3-FKHR regulated genes differentially expressed between alveolar and embryonal rhabdomyosarcomas

Publications

Identification of PAX3-FKHR-regulated genes differentially expressed between alveolar and embryonal rhabdomyosarcoma: focus on MYCN as a biologically relevant target.

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