NVP-BEZ-235 enhances radiosensitization via blockade of the PI3k/mTOR pathway in cisplatin-resistant non-small cell lung carcinoma

Kwang Woon Kim, Carey J. Myers, Dae Kwang Jung, Bo Lu

Research output: Contribution to journalArticle

32 Scopus citations

Abstract

Introduction: Most drug resistant cancer cells also develop resistance to radiation therapy. In this study, we hypothesized that the dual inhibitor of phosphatidylinositol-3 kinase/mammalian target of rapamycin, NVP-BEZ-235, could potentially enhance radiosensitization in cisplatin-resistance (CDDP-R) non-small cell lung cancer (NSCLC) cells by disabling autophagy as a mechanism of self-preservation. Methods: We used both in vitro and in vivo approaches, including clonogenic assays, Western blotting, molecular analyses of autophagy and apoptosis, a xenograft model of tumor growth, and immunohistochemical analysis. Results: Basal p-Akt, p-mTOR and p-S6R proteins were enhanced in CDDP-R NSCLC cells. CDDP-R-resistant NSCLC cells are less radiation sensitive in comparison to parental cells (DER=0.82, p=0.02); BEZ-235 enhanced the radiosensitivity (DER=1.2, p=0.01). In addition, combining BEZ-235/RT showed a dramatic tumor growth delay in a mouse xenograft model. Immunohistochemistry showed that combination therapy yielded 50% decrease in caspase-3 activity. Moreover, cell proliferation was reduced by 87.8% and vascular density by 86.1%. These results were associated with a downregulation of PI3K/mTOR signaling pathway and an increase in autophagy. Conclusions: These findings may be utilized as a novel strategy to enhance the efficacy of radiation therapy in drug-selected non-small cell lung cancer exhibiting radioresistance.

Original languageEnglish (US)
Pages (from-to)293-302
Number of pages10
JournalGenes and Cancer
Volume5
Issue number7-8
StatePublished - Jan 1 2014
Externally publishedYes

Keywords

  • Autophagy
  • Cisplatin resistance
  • mTOR
  • NSCLC
  • Radiosensitization

ASJC Scopus subject areas

  • Genetics
  • Cancer Research

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