Isogambogenic acid induces apoptosis-independent autophagic cell death in human non-small-cell lung carcinoma cells

Sci Rep. 2015 Jan 9:5:7697. doi: 10.1038/srep07697.

Abstract

To overcome drug resistance caused by apoptosis deficiency in patients with non-small cell lung carcinoma (NSCLC), there is a need to identify other means of triggering apoptosis-independent cancer cell death. We are the first to report that isogambogenic acid (iso-GNA) can induce apoptosis-independent autophagic cell death in human NSCLC cells. Several features of the iso-GNA-treated NSCLC cells indicated that iso-GNA induced autophagic cell death. First, there was no evidence of apoptosis or cleaved caspase 3 accumulation and activation. Second, iso-GNA treatment induced the formation of autophagic vacuoles, increased LC3 conversion, caused the appearance of autophagosomes and increased the expression of autophagy-related proteins. These findings provide evidence that iso-GNA induces autophagy in NSCLC cells. Third, iso-GNA-induced cell death was inhibited by autophagic inhibitors or by selective ablation of Atg7 and Beclin 1 genes. Furthermore, the mTOR inhibitor rapamycin increased iso-GNA-induced cell death by enhancing autophagy. Finally, a xenograft model provided additional evidence that iso-GNA exhibited anticancer effect through inducing autophagy-dependent cell death in NSCLC cells. Taken together, our results demonstrated that iso-GNA exhibited an anticancer effect by inducing autophagy-dependent cell death in NSCLC cells, which may be an effective chemotherapeutic agent that can be used against NSCLC in a clinical setting.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / toxicity*
  • Apoptosis
  • Apoptosis Regulatory Proteins / antagonists & inhibitors
  • Apoptosis Regulatory Proteins / genetics
  • Apoptosis Regulatory Proteins / metabolism
  • Autophagy / drug effects*
  • Autophagy-Related Protein 7
  • Beclin-1
  • Carcinoma, Non-Small-Cell Lung / metabolism
  • Carcinoma, Non-Small-Cell Lung / pathology
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • G1 Phase Cell Cycle Checkpoints / drug effects
  • Humans
  • Lung Neoplasms / metabolism
  • Lung Neoplasms / pathology
  • Membrane Proteins / antagonists & inhibitors
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Microtubule-Associated Proteins / metabolism
  • Proto-Oncogene Proteins c-akt / metabolism
  • RNA Interference
  • RNA, Small Interfering / metabolism
  • Signal Transduction / drug effects
  • Sirolimus / toxicity
  • TOR Serine-Threonine Kinases / metabolism
  • Ubiquitin-Activating Enzymes / antagonists & inhibitors
  • Ubiquitin-Activating Enzymes / genetics
  • Ubiquitin-Activating Enzymes / metabolism
  • Xanthones / chemistry
  • Xanthones / toxicity*

Substances

  • Antineoplastic Agents
  • Apoptosis Regulatory Proteins
  • BECN1 protein, human
  • Beclin-1
  • MAP1LC3A protein, human
  • Membrane Proteins
  • Microtubule-Associated Proteins
  • RNA, Small Interfering
  • Xanthones
  • isogambogenic acid
  • Proto-Oncogene Proteins c-akt
  • TOR Serine-Threonine Kinases
  • ATG7 protein, human
  • Autophagy-Related Protein 7
  • Ubiquitin-Activating Enzymes
  • Sirolimus