PDK-1/AKT pathway as a novel therapeutic target in rhabdomyosarcoma cells using OSU-03012 compound

Abstract

Rhabdomyosarcoma (RMS) is the most common paediatric soft-tissue sarcoma including two major subtypes, alveolar rhabdomyosarcoma (ARMS) and embryonal rhabdomyosarcoma (ERMS). Increasing evidence suggests that oncogenesis of RMS involves multistages of signalling protein dysregulation which may include prolonged activation of serine/threonine kinases such as phosphoinositide-dependant kinase-1 (PDK-1) and AKT. To date, whether PDK-1/AKT pathway is activated in RMS is unknown. This study was to examine phosphorylation status of AKT and to evaluate a novel small molecular inhibitor, OSU-03012 targeting PDK-1 in RMS. We examined phosphorylation levels of AKT using ARMS and ERMS tissue microarray and immunohistochemistry staining. Our results showed phospho-AKT Thr308 level is elevated 42 and 35% in ARMS and ERMS, respectively. Phospho-AKT Ser473 level is also increased 43% in ARMS and 55% in ERMS. Furthermore, we showed that OSU-03012 inhibits cell viability and induces apoptosis in ARMS and ERMS cell lines (RH30, SMS-CTR), which express elevated phospho-AKT levels. Normal cells are much less sensitive to OSU-03012 and in which no detectable apoptosis was observed. This study showed, for the first time, that PDK-1/AKT pathway is activated in RMS and may play an important role in survival of RMS. PDK-1/AKT pathway may be an attractive therapeutic target for cancer intervention in RMS using OSU-03012.

Sarcomas induced in discrete subsets of prospectively isolated skeletal muscle cells

“…Several other candidate genes have been linked to mTOR signaling (51), and positive p-S6 immunostaining confirmed enhanced mTOR signaling in Kras; p16p19 null sarcomas and in 26-33% of human RMS and leiomyosarcomas. Similarly, phosphorylation of AKT (another mTOR pathway component) was reported in 43-55% of human embryonal and alveolar RMS (52). Like Ras, pharmacological inhibition of mTOR signaling in mouse and human sarcoma cells impaired tumor growth, consistent with prior studies using RMS cell lines and xenografts (19,21) and with beneficial effects seen in some patients with advanced sarcomas (45).…”

Efficacy and Safety of Endostar®Combined with Chemotherapy in Patients with Advanced Soft Tissue Sarcomas

“…Some researchers have found that OSU-03012 inhibited tumor cell viability, induced apoptosis in tumor cells, and did not induce detectable apoptosis in normal human cells. So, in the treatment of rhabdomyosarcoma, the novel OSU-03012 compound may be a more potent inhibitor of PDK-1/AKT pathway than the current potent inhibitor of PI3-K/AKT, LY294002 (Cen et al, 2007). In addition, the mammalian target of rapamycin (mTOR) inhibitors has been proven to have promising antitumor activity in patients with metastatic sarcoma (Vincezi et al, 2011).…”

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

“…The PI3K/AKT signaling pathway is frequently activated in many cancers, 48 including ARMS. 38 This pathway is also activated and acts as a promyogenic signal following the exposure of normal myoblasts to differentiationpermissible conditions. 25,26 Because ARMS-T and ARMS-325 cells have an inactive terminal myogenic differentiation program (Fig.…”

“…Activation of AKT signaling pathway, which is a common lesion in many cancers, [35][36][37] is also found in ARMS. 38 Moreover, studies have found that AKT targets FKHR function in normal myogenic differentiation, 6,7 but its fusion derivative PAX3-FKHR abrogates such processes in ARMS. [18][19][20]23,39 However, the molecular mechanism(s) underlying activated AKT signaling in association with PAX3-FKHR in the suppression of myogenic differentiation program in ARMS remains unknown.…”