Rapamycin-enhanced mitomycin C-induced apoptotic death is mediated through the S6K1-Bad-Bak pathway in peritoneal carcinomatosis

X. Song, A. K. Dilly, S. Y. Kim, H. A. Choudry, Y. J. Lee

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Peritoneal carcinomatosis (PC) is the most common secondary cancerous disease, and more effective novel regimens are needed. In this study, we identified a novel combination treatment for PC, chemotherapeutic agent mitomycin C in combination with mTOR (mammalian target of rapamycin) inhibitor rapamycin. We observed that the combination of mitomycin C and rapamycin induced synergistic cytotoxicity and apoptosis, which was mediated through an increase in caspase activation. The combination of mitomycin C and rapamycin inactivated p70 S6 ribosomal kinase (S6K1) and dephosphorylated Bad, leading to dissociation of Bcl-xL from Bak, which resulted in Bak oligomerization, mitochondria dysfunction and cytochrome c release. PF-4708671, a S6K1-specific inhibitor, enhanced the combination treatment-induced apoptosis, whereas S6K1 E389 DeltaCT-HA (S6K1 active form) dramatically decreased the induction of apoptosis. In addition, the combination treatment significantly inhibited LS174T intraperitoneal tumor growth in vivo. This study provides a preclinical rationale for apoptosis induction linked with the mTOR pathway through a combination of chemotherapeutic agents and mTOR inhibitor, and will support this combinatorial strategy to PC patients.

Original languageEnglish (US)
Article numbere1281
JournalCell Death and Disease
Issue number6
StatePublished - Jun 2014
Externally publishedYes

ASJC Scopus subject areas

  • Immunology
  • Cellular and Molecular Neuroscience
  • Cell Biology
  • Cancer Research


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