In the present study, we show that concomitant inhibition of Hedgehog (HH) signaling by the glioma-associated oncogene homolog1 (GLI1)-targeting agent GANT61 and the antiapoptotic BCL-2 protein family member MCL-1 by A-1210477 synergistically induces cell death in HH-driven cancers, i.e. rhabdomyosarcoma (RMS) and medulloblastoma (MB) cells.
Furthermore, one of the top targets, FOXS1, a gene encoding a transcription factor previously implicated in nervous system development, was shown to act in a negative feedback loop limiting the cellular effects of GLI1 in medulloblastoma and rhabdomyosarcoma cells.
We showed that TAF9 interacts with the oncogenic GLI family members GLI1 and GLI2 but not GLI3 in cell-free pull-down assays and with GLI1 in rhabdomyosarcoma and osteosarcoma cell lines.
Expression of GLI1 with or without PTCH was detected in substantial subsets of embryonal RMS (ERMS) and US tumors but only rarely in alveolar RMS tumors.
A mutation in Patched, Smoothened or Gli1, which regulate the Hh signaling pathway, might lead to the onset of glioblastoma, basal cell carcinoma, medulloblastoma and rhabdomyosarcoma.
In neuroblastoma, 96%, 100%, and 68%; in rhabdomyosarcoma, 78%, 100%, and 78%; in Wilms' tumor, 71%, 100%, and 43%; and in hepatoblastoma, 100%, 100%, and 73% of the specimens stained positive for Shh, Ptch, and Gli1, respectively.
Sporadic rhabdomyomas and rhabdomyosarcomas showed overexpression of PTCH (43/43) and GLI1 (41/43) mRNA, as determined by in situ hybridization, indicating ongoing active hedgehog signalling.
We evaluated amplification and overrepresentation of CDK4, MDM2, GLI and SAS genes of the 12q13-15 region, in a group of soft tissue sarcomas including leiomyosarcomas (LMS), alveolar rhabdomyosarcomas (ARMS) and embryonal (anaplastic and classic variants) rhabdomyosarcomas (ERMS), to ascertain genomic alterations and possible differences within histologic subtypes of rhabdomyosarcoma (RMS).
Up-regulation of cyclin D2 and down-regulation of plakoglobin were demonstrated in GLI1-amplified compared with non-amplified human rhabdomyosarcoma cells.