Lung Cancer Research Today is a free monthly online journal that collates and summarizes the latest research about Lung Cancer, including details on symptoms, smoking, genetics, treatment, causes. | ||||||||
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Suberoylanilide hydroxamic acid combined with gemcitabine enhances apoptosis in non-small cell lung cancer.Rundall BK, Denlinger CE, Jones DR Department of Surgery, University of Virginia School of Medicine, Charlottesville 22908-0679, USA. 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. Published 12 September 2005 in Surgery, 138(2): 360-7.
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