Dual blockade of the PI3K/AKT/mTOR (AZD8055) and RAS/MEK/ERK (AZD6244) pathways synergistically inhibits rhabdomyosarcoma cell growth in vitro and in vivo.
Addiction to elevated insulin-like growth factor I receptor and initial modulation of the AKT pathway define the responsiveness of rhabdomyosarcoma to the targeting antibody.
Here, we identify a novel synthetic lethality of concomitant inhibition of HH and PI3K/AKT/mTOR pathways in RMS by GLI1/2 inhibitor GANT61 and PI3K/mTOR inhibitor PI103.
Expression analysis of additional genes, AKT1, NOG and its antagonist BMP4, which interact downstream to FGFR1, demonstrated expression differences between primary RMS tumors and normal skeletal muscles.
We found that PLAG1 regulates IGF2 expression and influences AKT and MAPK pathways in RMS, and IGF2 partially rescues cell death triggered by PLAG1 knockdown.
FGFR1 over-expression in primary rhabdomyosarcoma tumors is associated with hypomethylation of a 5' CpG island and abnormal expression of the AKT1, NOG, and BMP4 genes.
We then demonstrated that Akt inhibition antagonizes RMS-including RMS resistant to EGFR inhibition-and that sustained activity of the Akt1 isoform preferentially blocks rhabdomyoblast differentiation potential in cell culture and <i>in vivo</i>.