Current chemotherapy of advanced non-small cell lung cancer (NSCLC) produces only a modest increase in survival time. New approaches are needed for this disease. The development of lung cancer is associated with silencing tumor suppressor genes that can occur not only by deletion or mutation, but also by epigenetic changes including histone deacetylation of key lysines. Histone deacetylase inhibitor (HDACI) increases histone acetylation, resulting in DNA with a more open chromatin that favors transcription. We found that the HDACI, suberoylanilide hydroxamic acid (SAHA), suppressed cell growth of five non-small cell lung cancer cell lines in a dose-dependent manner (50% growth inhibition approximately 2 microM). Cell cycle assay by fluorescence-activated cell sorting (FACS) demonstrated that SAHA induced a significant G0-G1 growth arrest of NSCLC cells. Protein assay by Western blot analysis showed that SAHA induced expression of p21WAF1. These results demonstrated that administration of SAHA may be a novel approach to the treatment of non-small cell lung cancer.