Glycogen synthase kinase 3 regulates PAX3–FKHR-mediated cell proliferation in human alveolar rhabdomyosarcoma cells

Abstract

Patients with alveolar rhabdomyosarcoma (ARMS) have poorer response to conventional chemotherapy and lower survival rates than those with embryonal RMS (ERMS). To identify compounds that preferentially block the growth of ARMS, we conducted a small-scale screen of 160 kinase inhibitors against the ARMS cell line Rh30 and ERMS cell line RD and identified inhibitors of glycogen synthase kinase 3 (GSK3), including TWS119 as ARMS-selective inhibitors. GSK3 inhibitors inhibited cell proliferation and induced apoptosis more effectively in Rh30 than RD cells. Ectopic expression of fusion protein PAX3-FKHR in RD cells significantly increased their sensitivity to TWS119. Down-regulation of GSK3 by GSK3 inhibitors or siRNA significantly reduced the transcriptional activity of PAX3-FKHR. These results suggest that GSK3 is directly involved in regulating the transcriptional activity of PAX3-FKHR. Also, GSK3 phosphorylated PAX3-FKHR in vitro, suggesting that GSK3 might regulate PAX3-FKHR activity via phosphorylation. These findings support a novel mechanism of PAX3-FKHR regulation by GSK3 and provide a novel strategy to develop GSK inhibitors as anti-ARMS therapies.

Efficacy of glycogen synthase kinase-3β targeting against osteosarcoma via activation of β-catenin

“…Together with other studies, our observations have established GSK-3β as a potential therapeutic target in common adult-onset chronic diseases including cancer [13, 18, 19]. Therapeutic effects of GSK-3β inhibition have been shown in epithelial as well as in hematopoietic, neuronal and musculoskeletal cell malignancies including leukemia [20], glioblastoma [16, 17] and rhabdomyosarcoma [21, 22]. …”

AKT and PAX3-FKHR cooperation enforces myogenic differentiation blockade in alveolar rhabdomyosarcoma cell

“…Several studies have reported phosphorylation in the PAX3 domain of PAX3-FKHR in association with its transcriptional activity. 1,[54][55][56][57][58] However, none of the above studies reported phosphorylation-induced we did perceive, during the assessment of PAX3-FKHR transactivation potency in ARMS cells, that PAX3-FKHR appears as a doublet of a faster and slower migrating form. Interestingly, the data showed the shift of PAX3-FKHR to a slower migrating form in ARMS cells grown in DM.…”

“…However, includes phosphorylation. 54,55 Since induced PAX3-FKHR phosphorylation occurred when cells were grown in DM, we hypothesized that phosphorylation could be responsible for the decreased PAX3-FKHR transcriptional activity. Several studies have reported phosphorylation in the PAX3 domain of PAX3-FKHR in association with its transcriptional activity.…”

Exosomes derived from embryonal and alveolar rhabdomyosarcoma carry differential miRNA cargo and promote invasion of recipient fibroblasts

“…Significantly represented networks featured proteins previously implicated in ARMS biology (GSK3b, MDM2, CDKN1A, CDKN2A, IGF1R)4344454647, proteins involved in immune evasion and tumor metastasis (CXCL8, CSF1, IFNAR1, CCR2, CASR)4849505152, stemness (SOX2, POU5F1)5354, tumor cell proliferation and invasion (YBX1)41, or have been associated with other tumor types with a possible role in tumor biology (PRKACA, MYO1C, BRINP3)555657. The finding of the miRNA networks targeting proteins involved in stemness, immune evasion and metastasis, enriched in ARMS but not ERMS exosomes, suggests that paracrine signaling via exosomes may have differential effects on mediating the known aggressive behavior of ARMS.…”