Suberoylanilide hydroxamic acid combined with gemcitabine enhances apoptosis in non-small cell lung cancer

Surgery. 2005 Aug;138(2):360-7. doi: 10.1016/j.surg.2005.06.016.

Abstract

Background: We have shown that non-small cell lung cancer (NSCLC) is resistant to the histone deacetylase inhibitor (HDI) suberoylanilide hydroxamic acid (SAHA) through upregulation of the antiapoptotic transcription factor nuclear factor-kappaB (NF-kappaB). HDIs also promote chromatin remodeling, potentially making the DNA more accessible to chemotherapy. We hypothesize that combined SAHA and gemcitabine sensitizes NSCLC to apoptosis.

Methods: Three NSCLC cell lines (A549, H358, H460) were untreated, or treated with SAHA, gemcitabine, or both agents. NF-kappaB-dependent transcription was determined by reporter gene assays, reverse transcriptase-polymerase chain reaction RT-PCR, and Western blot analysis for the NF-kappaB-regulated antiapoptotic gene MnSOD. Survival of NSCLC cells overexpressing Bfl/A1, Bcl-X(L), or MnSOD and treated with SAHA and gemcitabine was determined in the presence or absence of NF-kappaB. Survival of treated cells overexpressing HDAC-1, 2, 3 or p/CAF was determined. Apoptosis was determined by fluorescence-activated cell sorter analysis, DNA fragmentation, and caspase-3 activity. Colony formation assays were performed on cells treated concurrently and sequentially with SAHA and gemcitabine. Assays were performed in triplicate, and the Student t test was applied as appropriate.

Results: SAHA-activated NF-kappaB (P <or= .05) and gemcitabine inhibited these effects (P <or= .01). Increased cell survival was observed after overexpression of antiapoptotic genes, as well as in cells overexpressing HDAC-1, -2, and -3. Fluorescence-activated cell sorter analysis, DNA fragmentation, and caspase-3 assays all showed enhanced apoptosis with combined therapy, compared with single-agent therapy (P <or= .01). Sequential treatment offered no improvement over concurrent treatment.

Conclusions: Combined SAHA and gemcitabine sensitized NSCLC cells to apoptosis. Potential "proapoptotic" mechanisms for this finding include gemcitabine inhibition of SAHA-induced NF-kappaB activation and chromatin remodeling mediated by the inhibition of histone deacetylases.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetylation
  • Antimetabolites, Antineoplastic / pharmacology*
  • Antineoplastic Agents / pharmacology*
  • Apoptosis / drug effects
  • Carcinoma, Non-Small-Cell Lung / drug therapy*
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Chromatin / metabolism
  • Deoxycytidine / analogs & derivatives*
  • Deoxycytidine / pharmacology
  • Drug Synergism
  • Humans
  • Hydroxamic Acids / pharmacology*
  • Lung Neoplasms / drug therapy*
  • NF-kappa B / metabolism
  • Transcription, Genetic / drug effects
  • Vorinostat

Substances

  • Antimetabolites, Antineoplastic
  • Antineoplastic Agents
  • Chromatin
  • Hydroxamic Acids
  • NF-kappa B
  • Deoxycytidine
  • Vorinostat
  • gemcitabine