Many findings have demonstrated that PAX/FOXO1-positive ARMS have a worse prognosis than PAX/FOXO1-negative ones and that distinct molecular features characterize RMS with different gene fusion statuses.
Detection of PAX3/PAX7-FKHR fusion transcripts by 1-step reverse transcriptase polymerase chain reaction is a novel tool for RMS diagnosis and differentiation.
We have determined the presence of the PAX3/7-FKHR fusion genes in 91 primary rhabdomyosarcoma tumours using a combination of classical cytogenetics, FISH and RT-PCR, with a view to determining the clinical characteristics of tumours with and without the characteristic translocations.
Together with the observed effects on the PAX3-FOXO1 fusion protein, these data suggest SAHA as a possible therapeutic agent for clinical testing in patients with fusion protein-positive RMS.
We determined PAX3-FKHR or PAX7-FKHR fusion status in 171 childhood rhabdomyosarcoma (RMS) patients entered onto the Intergroup Rhabdomyosarcoma Study IV, including 78 ARMS patients, using established reverse transcriptase polymerase chain reaction assays.
This study describes the in vitro and in vivo activity of PXD-101 (Belinostat), a novel hydroxamic acid-type pan-HDACs inhibitor characterized by a larger safety and efficacy, on myogenic-derived PAX3/FOXO1 fusion protein positive (RH30) or negative (RD) expressing rhabdomyosarcoma (RMS) cell lines.
These results indicate that the involvement of PAX3 and PAX3-FKHR in rhabdomyosarcoma tumourigenesis may be through downregulation of PTEN tumour suppressor gene, affecting the PTEN/AKT survival pathway.
Our findings identify a novel role of both PAX3-FOXO1 and its downstream effector miR-486-5p in exosome-mediated oncogenic paracrine effects of RMS, and suggest its possible use as a biomarker.
The map of PAX3-FKHR binding sites provides a framework for understanding the pathogenic roles of PAX3-FKHR, as well as its molecular targets to allow a systematic evaluation of agents against this aggressive rhabdomyosarcoma.
We previously identified the class I-specific histone deacetylase inhibitor, entinostat (ENT), as a pharmacological agent that transcriptionally suppresses the PAX3:FOXO1 tumor-initiating fusion gene found in alveolar rhabdomyosarcoma (aRMS), and we further investigated the mechanism by which ENT suppresses PAX3:FOXO1 oncogene and demonstrated the preclinical efficacy of ENT in RMS orthotopic allograft and patient-derived xenograft (PDX) models.
Translocation of the 5' region of the FKHR gene to the derivative chromosome 2, and retention of the 3' region of FKHR on the derivative chromosome 13 [(der(13)], were demonstrated in metaphase cells from a rhabdomyosarcoma cell line with a previously identified t(2;13) translocation.
Convenience cohorts have been used to investigate the prognostic significance of chromosomal translocations between the PAX3 or PAX7 and the FOXO1 genes in rhabdomyosarcoma, the most common pediatric sarcoma.
A less frequent variant translocation t(1;13) involves another PAX family gene, /PAX7/, located in chromosome 1 and /FOXO1/ and is present in 10-15% of cases of the alveolar subtype in RMS.
While RMS has been traditionally classified on the basis of its histological appearance (with embryonal and alveolar being most common), it is now clear that the PAX-FOXO1 fusion product drives prognosis.
An analysis of IGFBP2 mRNA and protein localization in human tumors showed abnormal protein accumulation in the Golgi complex, mostly in PAX/FKHR-negative RMS.
Sequential immunoprecipitations with anti-PAX3 and anti-FKHR sera demonstrated expression of a 97-kDa PAX3-FKHR fusion protein in the t(2;13)-positive rhabdomyosarcoma Rh30 cell line and verified that a single polypeptide contains epitopes derived from each protein.
Notably, ALK mRNA distinguished unfavourable PAX3/7-FOXO1-positive tumours from PAX3/7-FOXO1-negative RMS (P<0.0001), and also correlated with larger tumour size (P<0.05) and advanced clinical stage (P<0.01), independently of fusion gene status.