Insulin-like growth factor-I has different effects on myogenin induction and cell cycle progression in human alveolar and embryonal rhabdomyosarcoma cells

Kunihiko Tsuchiya, Hajime Hosoi, Akiko Misawa-Furihata, Peter J. Houghton, Tohru Sugimoto

Research output: Contribution to journalArticle

13 Scopus citations


Alveolar rhabdomyosarcoma (RMS) has a much poorer outcome than embryonal RMS. In this study, we found that IGF-I affected the induction of myogenin and cell cycle progression in alveolar RMS cells, but not in embryonal RMS cells. IGF-I enhanced the induction of myogenin protein in alveolar RMS SJ-Rh30 and KP-RMS-MS cells as it did in myoblast C2C12 cells, but not in embryonal RMS RD or KPRMS-KH cells. IGF-I induction of myogenin protein was blocked by anti-IGF-IR monoclonal antibody αIR-3 and the mTOR-specific inhibitor rapamycin. In Rh30mTOR-rr cells, which stably express a rapamycin-resistant mutant mTOR, rapamycin did not inhibit IGF-I induction of myogenin protein. These data suggest that IGF-I induces myogenin in alveolar RMS cells through the IGF-IR/mTOR pathway. In C2C12 cells, IGF-I induces myogenin protein followed by cell cycle arrest leading to myogenic differentiation. IGF-I promoted G1-S cell cycle progression without any signs of terminal differentiation in alveolar RMS cells. On the other hand, IGF-I promoted neither cell cycle arrest nor G1-S cell cycle progression in embryonal RMS cells. In alveolar RMS SJ-Rh30 cells, 4E-BP1, one of two effectors downstream of mTOR, was continuously hyperphosphorylated by IGF-I, whereas in embryonal RMS RD cells, 4E-BP1 was only transiently hyperphosphorylated. These findings suggest that the different effects of IGF-I on myogenin induction and cell cycle progression in alveolar and embryonal RMS cells are due to a difference of phosphorylation status of 4E-BP1. These different responses to IGF-I help to explain immunohistochemical and clinical behavioral differences between alveolar and embryonal RMS.

Original languageEnglish (US)
Pages (from-to)41-47
Number of pages7
JournalInternational journal of oncology
Issue number1
Publication statusPublished - Jul 1 2007



  • 4E-BP1
  • Cell cycle progression
  • IGF-I
  • Myogenin
  • Rhabdomyosarcoma

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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