PAX7 is a required target for microRNA-206-induced differentiation of fusion-negative rhabdomyosarcoma.
Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma of childhood. RMS can be parsed based on clinical outcome into two subtypes, fusion-positive RMS (FP-RMS) or fusion-negative RMS (FN-RMS) based on the presence or absence of either PAX3-FOXO1 or PAX7-FOXO1 gene fusions. In both RMS subtypes, tumor cells show histology and a gene expression pattern resembling that of developmentally arrested skeletal muscle. Differentiation therapy is an attractive approach to embryonal tumors of childhood including RMS; however, agents to drive RMS differentiation have not entered the clinic and their mechanisms remain unclear. MicroRNA-206 (miR-206) expression increases through normal muscle development and has decreased levels in RMS compared with normal skeletal muscle. Increasing miR-206 expression drives differentiation of RMS, but the target genes responsible for the relief of the development arrest are largely unknown. Using a combinatorial approach with gene and proteomic profiling coupled with genetic rescue, we identified key miR-206 targets responsible for the FN-RMS differentiation blockade, PAX7, PAX3, NOTCH3, and CCND2. Specifically, we determined that PAX7 downregulation is necessary for miR-206-induced cell cycle exit and myogenic differentiation in FN-RMS but not in FP-RMS. Gene knockdown of targets necessary for miR-206-induced differentiation alone or in combination was not sufficient to phenocopy the differentiation phenotype from miR-206, thus illustrating that miR-206 replacement offers the ability to modulate a complex network of genes responsible for the developmental arrest in FN-RMS. Genetic deletion of miR-206 in a mouse model of FN-RMS accelerated and exacerbated tumor development, indicating that both in vitro and in vivo miR-206 acts as a tumor suppressor in FN-RMS at least partially through downregulation of PAX7. Collectively, our results illustrate that miR-206 relieves the differentiation arrest in FN-RMS and suggests that miR-206 replacement could be a potential therapeutic differentiation strategy.
Department of Oncology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
J A
JA
Hanna
Department of Oncology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
M R
MR
Garcia
Department of Oncology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
J C
JC
Go
Department of Computational Biology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
D
D
Finkelstein
St. Jude Proteomics Facility, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
K
K
Kodali
St. Jude Proteomics Facility, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
V
V
Pagala
St. Jude Proteomics Facility, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
X
X
Wang
St. Jude Proteomics Facility, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.|Department of Structural Biology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.|Department of Developmental Neurobiology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
J
J
Peng
Department of Oncology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
M E
ME
Hatley
D000818:Animals; D002454:Cell Differentiation / Q000235:genetics*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D006801:Humans; D019426:Integrases / Q000378:metabolism; D051379:Mice; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D000072041:PAX3 Transcription Factor / Q000378:metabolism; D051763:PAX7 Transcription Factor / Q000235:genetics* / Q000378:metabolism; D051880:Receptors, Notch / Q000378:metabolism; D015203:Reproducibility of Results; D012208:Rhabdomyosarcoma / Q000235:genetics* / Q000473:pathology*; D014162:Transfection
C546087:MIRN206 microRNA, human; D035683:MicroRNAs; D000072041:PAX3 Transcription Factor; C489409:PAX3 protein, human; D051763:PAX7 Transcription Factor; C497321:PAX7 protein, human; D051880:Receptors, Notch; C045073:Cre recombinase; D019426:Integrases