Biomedical subjects

Timothy J Triche

Publications and source records attributed to Timothy J Triche.

At least 19 recordsLinked to original sources

PubMed2025

EZH2-driven immune evasion at disease presentation defines a targetable high-risk subset of acute leukemia exemplified by t(16;21) FUS::ERG AML.

The past 25 years of clinical trials have produced few improvements in pediatric AML (pAML) outcomes. This is acutely evident in patients with t(16;21)(p11;q22), yielding FUS::ERG. Patients with FUS::ERG-positive AML relapse quickly and do not respond to transplantation. Major histocompatibility complex (MHC) class I & II receptors and costimulatory molecules are absent at diagnosis in FUS::ERG-positive AML, mirroring the phenotype and outcomes of post-transplant relapse. We show that this is driven by overexpression of EZH2, in vitro and in multiple clinical cohorts. While FUS::ERG AML is the most extreme example, this phenotype is shared by lethal CBFA2T3::GLIS2-driven AML, and patients with RUNX1::RUNX1T1 have significantly worse outcomes when EZH2 overexpression co-occurs. The FDA-approved EZH2 inhibitor tazemetostat reverses this phenotype, re-establishes MHC presentation, and elicits immune effector cell-mediated elimination. EZH2 inhibitors may provide the first targeted therapeutic frontline option for AML patients with FUS::ERG, with the potential for broader frontline immunostimulatory benefits.

Journal Article↗

PubMed2007

Population-based study of early age-related macular degeneration: role of the complement factor H Y402H polymorphism in bilateral but not unilateral disease.

OBJECTIVE: Recently, a strong association has been observed for the complement factor H (CFH) Tyr402His polymorphism with early and advanced age-related macular degeneration (AMD) in independent non-Hispanic White, clinic-based, case-control studies. These studies suggest the CFH His402 allele is a major risk allele in early and advanced AMD, explaining 43% to 70% of all AMD in older adults. We utilized a population-based case-control study design of early AMD among Latinos/Hispanics to evaluate the CFH Tyr402His polymorphism for an association with early AMD phenotypes. DESIGN: Retrospective population-based case-control study. PARTICIPANTS: This study cohort consists of 285 early AMD cases and 570 controls matched on age, birthplace, and smoking status. METHODS: Genotype determination was performed by allele-specific digestion of polymerase chain reaction products. MAIN OUTCOME MEASURES: Complement factor H Tyr402His polymorphism. RESULTS: We observed no overall statistically significant association with early AMD among Latinos. However, a subset of early AMD cases that have bilateral, not unilateral, intermediate-to-large soft macular drusen were 1.7 times more likely to carry either the homozygous or heterozygous His402 genotype. CONCLUSIONS: Our data suggest that the CFH Tyr402His is not a major risk factor for overall early AMD in this Latino population, but may play a role in susceptibility to phenotypes of early AMD likely to progress to late AMD.

Alleles↗

PubMed2006

Retinoic acid induces leukemia cell G1 arrest and transition into differentiation by inhibiting cyclin-dependent kinase-activating kinase binding and phosphorylation of PML/RARalpha.

Acute promyelocytic leukemia (APL) cells express promyelocytic leukemia/retinoic acid receptor alpha (PML/RARalpha) fusion protein, which leads to the blocking of APL cell differentiation. Treatment of APL with all-trans-retinoic acid (ATRA) induces disease remission by in vivo differentiation of APL cells. Differentiation requires cell cycle exit; yet how ATRA couples cell cycle exit to differentiation of APL remains largely unknown. We previously found that ATRA-induced cell differentiation accompanies ubiquitination-proteolysis of ménage à trois 1 (MAT1), an assembly factor and targeting subunit of cyclin-dependent kinase (CDK)-activating kinase (CAK) that regulates G1 exit. We report here that CAK binds to and phosphorylates PML/RARalpha in actively proliferating APL cells. In response to ATRA, PML/RARalpha is dissociated from CAK, leading to MAT1 degradation, G1 arrest, and decreased CAK phosphorylation of PML/RARalpha. CAK phosphorylation of PML/RARalpha is inhibited when MAT1 levels are reduced. Both MAT1 degradation and PML/RARalpha hypophosphorylation occur in ATRA-induced G1-arresting cells undergoing differentiation but not in the synchronized G1 cells that do not differentiate. These findings reveal a novel ATRA signaling on APL cell differentiation, in which ATRA coordinates G1 arrest and transition into differentiation by inducing MAT1 degradation and PML/RARalpha hypophosphorylation through disrupting PML/RARalpha binding and phosphorylation by CAK.

Carrier Proteins↗

PubMed2006

Identification of a PAX-FKHR gene expression signature that defines molecular classes and determines the prognosis of alveolar rhabdomyosarcomas.

Alveolar rhabdomyosarcomas (ARMS) are aggressive soft-tissue sarcomas affecting children and young adults. Most ARMS tumors express the PAX3-FKHR or PAX7-FKHR (PAX-FKHR) fusion genes resulting from the t(2;13) or t(1;13) chromosomal translocations, respectively. However, up to 25% of ARMS tumors are fusion negative, making it unclear whether ARMS represent a single disease or multiple clinical and biological entities with a common phenotype. To test to what extent PAX-FKHR determine class and behavior of ARMS, we used oligonucleotide microarray expression profiling on 139 primary rhabdomyosarcoma tumors and an in vitro model. We found that ARMS tumors expressing either PAX-FKHR gene share a common expression profile distinct from fusion-negative ARMS and from the other rhabdomyosarcoma variants. We also observed that PAX-FKHR expression above a minimum level is necessary for the detection of this expression profile. Using an ectopic PAX3-FKHR and PAX7-FKHR expression model, we identified an expression signature regulated by PAX-FKHR that is specific to PAX-FKHR-positive ARMS tumors. Data mining for functional annotations of signature genes suggested a role for PAX-FKHR in regulating ARMS proliferation and differentiation. Cox regression modeling identified a subset of genes within the PAX-FKHR expression signature that segregated ARMS patients into three risk groups with 5-year overall survival estimates of 7%, 48%, and 93%. These prognostic classes were independent of conventional clinical risk factors. Our results show that PAX-FKHR dictate a specific expression signature that helps define the molecular phenotype of PAX-FKHR-positive ARMS tumors and, because it is linked with disease outcome in ARMS patients, determine tumor behavior.

Biomarkers, Tumor↗

PubMed2006

The homeoprotein six1 transcriptionally activates multiple protumorigenic genes but requires ezrin to promote metastasis.

The vast majority of deaths associated with cancer are a consequence of a complex phenotypic behavior, metastasis, by which tumor cells spread from their primary site of origin to regional and distant sites. This process requires the tumor cell to make numerous adjustments, both subtle and dramatic, to successfully reach, survive, and flourish at favorable secondary sites. It has been suggested that molecular mechanisms accounting for metastatic behavior can recapitulate those employed during embryogenesis. We have shown that the homeodomain transcription factor Six1, known to be required for normal development of migratory myogenic progenitor cells, is sufficient to promote metastatic spread in a mouse model of the pediatric skeletal muscle cancer rhabdomyosarcoma. Here, we report that Six1 is able to activate the expression of a set of protumorigenic genes (encoding cyclin D1, c-Myc, and Ezrin) that can control cell proliferation, survival, and motility. Although the role of Ezrin in cytoskeletal organization and adhesion has been well studied, the means by which its expression is regulated are poorly understood. We now show that the gene encoding Ezrin is a direct transcriptional target of Six1. Moreover, Ezrin is indispensable for Six1-induced metastasis and highly expressed in a panel of representative pediatric cancers. Our data indicate that Ezrin represents a promising therapeutic target for patients with advanced-stage rhabdomyosarcoma and perhaps other malignancies.

Animals↗

PubMed2006

Akt-mediated YB-1 phosphorylation activates translation of silent mRNA species.

YB-1 is a broad-specificity RNA-binding protein that is involved in regulation of mRNA transcription, splicing, translation, and stability. In both germinal and somatic cells, YB-1 and related proteins are major components of translationally inactive messenger ribonucleoprotein particles (mRNPs) and are mainly responsible for storage of mRNAs in a silent state. However, mechanisms regulating the repressor activity of YB-1 are not well understood. Here we demonstrate that association of YB-1 with the capped 5' terminus of the mRNA is regulated via phosphorylation by the serine/threonine protein kinase Akt. In contrast to its nonphosphorylated form, phosphorylated YB-1 fails to inhibit cap-dependent but not internal ribosome entry site-dependent translation of a reporter mRNA in vitro. We also show that similar to YB-1, Akt is associated with inactive mRNPs and that activated Akt may relieve translational repression of the YB-1-bound mRNAs. Using Affymetrix microarrays, we found that many of the YB-1-associated messages encode stress- and growth-related proteins, raising the intriguing possibility that Akt-mediated YB-1 phosphorylation could, in part, increase production of proteins regulating cell proliferation, oncogenic transformation, and stress response.

Animals↗

PubMed2005

The ETV6-NTRK3 chimeric tyrosine kinase suppresses TGF-beta signaling by inactivating the TGF-beta type II receptor.

An emerging theme in cancer biology is that although some malignancies occur through the sequential acquisition of different genetic alterations, certain dominantly acting oncoproteins such as those associated with chromosomal translocations have multiple functions and do not require additional mutations for cell transformation. The ETV6-NTRK3 (EN) chimeric tyrosine kinase, a potent oncoprotein expressed in tumors derived from multiple cell lineages, functions as a constitutively active protein tyrosine kinase. Here, we show that EN suppresses TGF-beta signaling by directly binding to the type II TGF-beta receptor, thereby preventing it from interacting with the type I TGF-beta receptor. This activity requires a functional EN protein tyrosine kinase, and type II TGF-beta receptor appears to be a direct target of EN. Our findings provide evidence for a previously undescribed mechanism by which oncogenic tyrosine kinases can block TGF-beta tumor suppressor activity.

Activin Receptors, Type I↗

PubMed2005

Sequence-specific knockdown of EWS-FLI1 by targeted, nonviral delivery of small interfering RNA inhibits tumor growth in a murine model of metastatic Ewing's sarcoma.

The development of effective, systemic therapies for metastatic cancer is highly desired. We show here that the systemic delivery of sequence-specific small interfering RNA (siRNA) against the EWS-FLI1 gene product by a targeted, nonviral delivery system dramatically inhibits tumor growth in a murine model of metastatic Ewing's sarcoma. The nonviral delivery system uses a cyclodextrin-containing polycation to bind and protect siRNA and transferrin as a targeting ligand for delivery to transferrin receptor-expressing tumor cells. Removal of the targeting ligand or the use of a control siRNA sequence eliminates the antitumor effects. Additionally, no abnormalities in interleukin-12 and IFN-alpha, liver and kidney function tests, complete blood counts, or pathology of major organs are observed from long-term, low-pressure, low-volume tail-vein administrations. These data provide strong evidence for the safety and efficacy of this targeted, nonviral siRNA delivery system.

Animals↗

PubMed2005

EWS-FLI1 fusion protein up-regulates critical genes in neural crest development and is responsible for the observed phenotype of Ewing's family of tumors.

Tumor-specific translocations are common in tumors of mesenchymal origin. Whether the translocation determines the phenotype, or vice versa, is debatable. Ewing's family tumors (EFT) are consistently associated with an EWS-FLI1 translocation and a primitive neural phenotype. Histogenesis and classification are therefore uncertain. To test whether EWS-FLI1 fusion gene expression is responsible for the primitive neuroectodermal phenotype of EFT, we established a tetracycline-inducible EWS-FLI1 expression system in a rhabdomyosarcoma cell line RD. Cell morphology changed after EWS-FLI1 expression, resembling cultured EFT cells. Xenografts showed typical EFT features, distinct from tumors formed by parental RD. Neuron-specific microtubule gene MAPT, parasympathetic marker cholecystokinin, and epithelial marker keratin 18 were up-regulated. Conversely, myogenesis was diminished. Comparison of the up-regulated genes in RD-EF with the Ewing's signature genes identified important EWS-FLI1 downstream genes, many involved in neural crest differentiation. These results were validated by real-time reverse transcription-PCR analysis and RNA interference technology using small interfering RNA against EWS-FLI1 breakpoint. The present study shows that the neural phenotype of Ewing's tumors is attributable to the EWS-FLI1 expression and the resultant phenotype resembles developing neural crest. Such tumors have a limited neural phenotype regardless of tissue of origin. These findings challenge traditional views of histogenesis and tumor origin.

Animals↗

PubMed2005

Affymetrix oligonucleotide analysis of gene expression in the injured heart.

Microarrays have helped researchers gain much insight into gene expression profiles in the context of many diseases including those in the injured heart. Our genomic investigations have been focused on elucidation of host gene responses to enterovirus infection. We have gained valuable technical expertise in using Affymetrix oligonucleotide arrays, also known as GeneChips, and cDNA spotted arrays to probe differential gene expression in both cultured cells and in heart tissue. Here, we provide a technique-focused supplement to the Affymetrix GeneChip Expression Analysis Manual for sample preparation, processing, and array hybridization. We provide expanded explanations to highlight important points within the existing protocol and offer variations to standard procedures when appropriate. For investigators using myocardial tissues for microarray experiments, we further address the necessity of and methods for in situ flushing of the vasculature, tissue homogenization, and considerations for limits of expression detection in rare cells. It is our intention to provide useful technical information, based on our experience, to assist those researchers using Affymetrix GeneChips in their own genomic research.

Animals↗

PubMed2004

Lack of interferon response in animals to naked siRNAs.

RNA interference (RNAi) is rapidly becoming the method of choice for the elucidation of gene function and the identification of drug targets. As with other oligonucleotide-based strategies, RNAi is envisioned to ultimately be useful as a human therapeutic. Unlike previous nucleic acid therapeutics, small interfering RNAs have the potential to elicit immune responses via interactions with Toll-like receptor 3 and trigger interferon responses like long, double-stranded RNA and its analogs, such as poly(I:C). Recently, the safety of siRNAs has been questioned because they have been shown to trigger an interferon response in cultured cells. We show here that it is possible to administer naked, synthetic siRNAs to mice and downregulate an endogenous or exogenous target without inducing an interferon response.

Animals↗

PubMed2004

Retinoid-modulated MAT1 ubiquitination and CAK activity.

Human cyclin-dependent kinase (CDK)-activating kinase (CAK) has a dual function in cross-regulation of cell cycle and differentiation, whereas menage a trois 1 (MAT1) assembles CAK and determines CAK's substrate specificity. Although the dynamic state of MAT1 protein levels is found to modulate CAK activity, how intracellular regulation of MAT1 controls CAK activity is unknown. Recent studies demonstrate that retinoic acid (RA)-induced human HL60 cell proliferation/differentiation (P/D) transition is accompanied by MAT1 degradation and decreased CAK phosphorylation of retinoic acid receptor alpha (RARa). Thus, we investigated the biochemical pathway of MAT1 degradation and its relationship with CAK phosphorylation of RARa. We find that RA induces ubiquitination-proteolysis of MAT1 and that ubiquitin-proteasome targets CAK-free MAT1 only. RA-induced MAT1 ubiquitination reduces CAK abundance and decreases CAK phosphorylation of RARalpha, whereas inhibition of MAT1 ubiquitination resists this RA-effect. These findings reveal that RA induces MAT1 ubiquitination to decrease CAK phosphorylation of RARalpha, suggesting a novel mechanism of RA-mediated P/D transition in which MAT1 ubiquitination may act as an integral part of RA-effect to decrease CAK activity in the switch from proliferation to differentiation.

Cell Differentiation↗

PubMed2004

Selective usage of D-Type cyclins by Ewing's tumors and rhabdomyosarcomas.

The genetic mechanisms that control proliferation of childhood musculoskeletal malignancies, notably Ewing's tumor (ET) and rhabdomyosarcoma (RMS), remain largely unknown. Most human cancers appear to overexpress at least one of the G1 cyclins (cyclins D1, D2, D3, E1, and E2) to bypass normal regulation of cell cycle G1 progression. We compared the gene expression profiles of 7 ET and 13 RMS primary tumor samples and found overexpression of cyclin D1 in all 7 ET samples. In contrast, RMS samples expressed higher levels of cyclin D2, cyclin D3, and cyclin E1. This was confirmed by quantitative reverse transcription-polymerase chain reaction and Western blot. The relative roles of RAS-extracellular signal-regulated kinase 1/2 and phosphatidylinositol 3'-kinase (PI3K)-AKT pathways in the regulation of D-type cyclin expression in these tumors were then assessed. Inhibition of either pathway reduced expression of cyclins D1, D2, and D3 in RMS lines, whereas only PI3K inhibitors blocked cyclin D1, D2, and D3 expression in ET lines. Furthermore, PI3K-AKT appeared to regulate D-type cyclin transcription in RMS lines through FKHR and FKHRL1. Finally, the role of the ET-associated EWS-FLI1 fusion gene in regulating D cyclin expression was studied. Inhibition of EWS-FLI1 expression in the TC71 ET line decreased cyclin D1 levels but increased cyclin D3 levels. In contrast, induction of EWS-FLI1 expression in the RD RMS cell line increased cyclin D1 expression but decreased cyclin D3 expression. Our results demonstrate distinct regulation of D-type cyclins in ET and RMS and indicate that EWS-FLI1 can modulate the expression of D-type cyclins independent of cellular backgrounds.

Cell Nucleus↗

PubMed2004

MAT1-modulated cyclin-dependent kinase-activating kinase activity cross-regulates neuroblastoma cell G1 arrest and neurite outgrowth.

Cyclin-dependent kinase-activating kinase (CAK) regulates cell cycle G1 exit, where cells commonly commit either to proliferate or to differentiate. CAK activity in G1 regulation is determined by its assembly factor and targeting subunit, ménage à trois 1 (MAT1). The precise mechanism of how proliferation/differentiation transition is induced from cancer cell G1 arrest remains unknown. We present evidence that in neuroblastoma CHP126 cells, CAK interacts with and phosphorylates retinoblastoma tumor suppressor protein (pRb) and retinoid X receptor alpha (RXRalpha). Retinoic acid (RA)-induced neuroblastoma cell proliferation/differentiation transition is associated with decreased CAK activity, as evidenced by a switch from CAK hyperphosphorylation of pRb and RXRalpha to hypophosphorylation of pRb and RXRalpha. Manipulation of MAT1 abundance shows that MAT1 reduction mimics RA-induced hypophosphorylation of pRb/RXRalpha, proliferation inhibition, and neurite outgrowth, whereas MAT1 overexpression resists these RA actions. Thus, these findings reveal an important mechanism by which MAT1-modulated CAK activity is crucial in the switch from proliferation to differentiation in neuroblastoma cells.

Alitretinoin↗

PubMed2004

Growth inhibition of breast epithelial cells by celecoxib is associated with upregulation of insulin-like growth factor binding protein-3 expression.

Several experimental and epidemiological studies have suggested a role for the use of cyclooxygenase (COX)-2 inhibitors in the prevention of breast cancer. The relative lack of toxicity associated with these compounds favors their use as chemopreventive agents, but the underlying mechanism of their chemopreventive effect remains unclear. We have observed that the COX-2 inhibitor celecoxib inhibits growth and induces apoptosis in the immortalized breast epithelial cell line 184htert. Microarray gene expression analysis of 184htert cells treated with 50 microM celecoxib for 6h revealed the modulation of several genes of interest, including a significant induction of expression of the mRNA encoding insulin-like growth factor binding protein-3 (IGFBP-3). IGFBP-3 is a potent pro-apoptotic protein and growth inhibitor of breast cancer cells, which acts mainly by inhibiting the access of the mitogens IGF-I and IGF-II to their cell surface receptor, but also via IGF-independent effects. Quantitative real-time RT PCR demonstrated that 50 microM celecoxib induced a approximately 3-fold increase in expression of IGFBP-3 mRNA after 6h. Furthermore, ligand blot analysis revealed that celecoxib treatment was associated with the upregulation of IGFBP-3 at the protein level. IGFBP-3 (500 ng/ml) treatment of 184htert cells inhibited IGF-I and serum-induced proliferation, but had no effect on cell growth under serum-free conditions, indicating that IGF-independent effects of IGFBP-3 are not observed in this system. Our results suggest that celecoxib may decrease IGF-I-associated breast cancer risk by a mechanism involving induction of expression of IGFBP-3 and subsequent reduced proliferation of at-risk breast epithelial cells.

Anticarcinogenic Agents↗

PubMed2002

Retinoid-induced G1 arrest and differentiation activation are associated with a switch to cyclin-dependent kinase-activating kinase hypophosphorylation of retinoic acid receptor alpha.

Cell cycle G(1) exit is a critical stage where cells commonly commit to proliferate or to differentiate, but the biochemical events that regulate the proliferation/differentiation (P/D) transition at G(1) exit are presently unclear. We previously showed that MAT1 (ménage à trois 1), an assembly factor and targeting subunit of the cyclin-dependent kinase (CDK)-activating kinase (CAK), modulates CAK activities to regulate G(1) exit. Here we find that the retinoid-induced G(1) arrest and differentiation activation of cultured human leukemic cells are associated with a switch to CAK hypophosphorylation of retinoic acid receptor alpha (RARalpha) from CAK hyperphosphorylation of RARalpha. The switch to CAK hypophosphorylation of RARalpha is accompanied by decreased MAT1 expression and MAT1 fragmentation that occurs in the differentiating cells through the all-trans-retinoic acid (ATRA)-mediated proteasome degradation pathway. Because HL60R cells that harbor a truncated ligand-dependent AF-2 domain of RARalpha do not demonstrate any changes in MAT1 levels or CAK phosphorylation of RARalpha following ATRA stimuli, these biochemical changes appear to be mediated directly through RARalpha. These studies indicate that significant changes in MAT1 levels and CAK activities on RARalpha phosphorylation accompany the ATRA-induced G(1) arrest and differentiation activation, which provide new insights to explore the inversely coordinated P/D transition at G(1) exit.

Bone Neoplasms↗

PubMed2002

Genetic heterogeneity in the alveolar rhabdomyosarcoma subset without typical gene fusions.

Previous studies of the PAX3-FKHR and PAX7-FKHR gene fusions in alveolar rhabdomyosarcoma (ARMS) indicated that the corresponding fusiontranscripts are not detectable in 20% of ARMS cases. To investigate the genetic features of this ARMS subset, we identified 23 ARMS cases in which PAX3-FKHR and PAX7-FKHR transcripts were not detected by a standard sensitivity reverse transcription-PCR (RT-PCR) assay. Subsequent analysis with a high sensitivity RT-PCR assay identified low-level expression of PAX3-FKHR or PAX7-FKHR in three cases. Analysis with a Southern blot assay for PAX3 and PAX7 rearrangements and a fluorescence in situ hybridization assay for FKHR rearrangements identified three cases with variant fusions in which PAX3 or PAX7 is postulated to be joined to novel genomic loci. In one such case, RT-PCR analysis of candidate partners identified a fusion of PAX3 to AFX, which is highly similar in structure and function to FKHR. Additional fluorescence in situ hybridization analysis identified two cases in which a PAX3-FKHR or PAX7-FKHR genomic fusion is present but is not associated with a fusion transcript detectable by RT-PCR. Finally, our analyses of the PAX3, PAX7, and FKHR loci did not identify rearrangements in >50% of cases, consistent with the possibility that there is a true fusion-negative subset. In summary, our analysis of ARMS cases without characteristic PAX3-FKHR or PAX7-FKHR transcripts identified several genetically distinct subsets including low expression or atypical presentation of standard fusions, variant fusions with other genes, and possibly true fusion-negative cases.

Base Sequence↗

PubMed2002

PAX3-FKHR and PAX7-FKHR gene fusions are prognostic indicators in alveolar rhabdomyosarcoma: a report from the children's oncology group.

PURPOSE: Alveolar rhabdomyosarcoma (ARMS) is an aggressive soft tissue malignancy of children and adolescents. Most ARMS patients express PAX3-FKHR or PAX7-FKHR gene fusions resulting from t(2;13) or t(1;13) translocations, respectively. We wished to confirm the diagnostic specificity of gene fusion detection in a large cohort of RMS patients and to evaluate whether these alterations influence clinical outcome in ARMS. PATIENTS AND METHODS: 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. All patients received central pathologic review and were treated using uniform protocols, allowing for meaningful outcome analysis. We examined the relationship between gene fusion status and clinical outcome in the ARMS cohort. RESULTS: PAX3-FKHR and PAX7-FKHR fusion transcripts were detected in 55% and 22% of ARMS patients, respectively; 23% were fusion-negative. All other RMS patients lacked transcripts, confirming the specificity of these alterations for ARMS. Fusion status was not associated with outcome differences in patients with locoregional ARMS. However, in patients presenting with metastatic disease, there was a striking difference in outcome between PAX7-FKHR and PAX3-FKHR patient groups (estimated 4-year overall survival rate of 75% for PAX7-FKHR v 8% for PAX3-FKHR; P =.0015). Multivariate analysis demonstrated a significantly increased risk of failure (P =.025) and death (P =.019) in patients with metastatic disease if their tumors expressed PAX3-FKHR. Among metastatic ARMS, bone marrow involvement was significantly higher in PAX3-FKHR-positive patients. CONCLUSION: Not only are PAX-FKHR fusion transcripts specific for ARMS, but expression of PAX3-FKHR and PAX7-FKHR identifies a very high-risk subgroup and a favorable outcome subgroup, respectively, among patients presenting with metastatic ARMS.

Adolescent↗