Histone Deacetylase 3 Inhibition Overcomes BIM Deletion Polymorphism-Mediated Osimertinib Resistance in EGFR-Mutant Lung Cancer.

Purpose: The BIM deletion polymorphism is associated with apoptosis resistance to EGFR tyrosine kinase inhibitors (EGFR-TKI), such as gefitinib and erlotinib, in non-small cell lung cancer (NSCLC) harboring EGFR mutations. Here, we investigated whether the BIM deletion polymorphism contributes to resistance against osimertinib, a third-generation EGFR-TKI. In addition, we determined the efficacy of a histone deacetylase (HDAC) inhibitor, vorinostat, against this form of resistance and elucidated the underlying mechanism.Experimental Design: We used EGFR-mutated NSCLC cell lines, which were either heterozygous or homozygous for the BIM deletion polymorphism, to evaluate the effect of osimertinib in vitro and in vivo Protein expression was examined by Western blotting. Alternative splicing of BIM mRNA was analyzed by RT-PCR.Results:EGFR-mutated NSCLC cell lines with the BIM deletion polymorphism exhibited apoptosis resistance to osimertinib in a polymorphism dosage-dependent manner, and this resistance was overcome by combined use with vorinostat. Experiments with homozygous BIM deletion-positive cells revealed that vorinostat affected the alternative splicing of BIM mRNA in the deletion allele, increased the expression of active BIM protein, and thereby induced apoptosis in osimertinib-treated cells. These effects were mediated predominantly by HDAC3 inhibition. In xenograft models, combined use of vorinostat with osimertinib could regress tumors in EGFR-mutated NSCLC cells homozygous for the BIM deletion polymorphism. Moreover, this combination could induce apoptosis even when tumor cells acquired EGFR-T790M mutations.Conclusions: These findings indicate the importance of developing HDAC3-selective inhibitors, and their combined use with osimertinib, for treating EGFR-mutated lung cancers carrying the BIM deletion polymorphism. Clin Cancer Res; 23(12); 3139-49. ©2016 AACR.

Indomethacin-guided cancer selective prodrug conjugate activated by histone deacetylase and tumour-associated protease.

An indomethacin-guided drug delivery conjugate (IGDDC) has been designed by utilizing cancer associated elevated HDAC and CTSL activities as consecutive demasking ventures for drug activation. IGDDC exhibited preferential uptake by COX-2 positive cells both in vitro and ex vivo highlighting indomethacin's role in designing new cancer-specific drug delivery frameworks.

Combined proteasome and histone deacetylase inhibition in non-small cell lung cancer.

OBJECTIVE: Inhibitors of histone deacetylases are potent inducers of cell-cycle arrest and apoptosis in certain malignancies. We have previously demonstrated that chemotherapy activates the antiapoptotic transcription factor nuclear factor kappa B in non-small cell lung cancer and fails to induce significant levels of apoptosis. We hypothesize that nuclear factor kappa B inhibition with the proteasome inhibitor bortezomib (formerly known as PS-341) will sensitize non-small cell lung cancer cells to histone deacetylase inhibitor-mediated apoptosis. METHODS: Tumorigenic non-small cell lung cancer cells (A549, H358, and H460) were treated with bortezomib, followed by the histone deactylase inhibitor sodium butyrate. After treatment, nuclear factor kappa B transcriptional activity was measured by using a luciferase reporter assay and transcription of the nuclear factor kappa B-dependent gene IL8. Apoptosis was determined on the basis of caspase-3 activation and DNA fragmentation. Western blot analyses for the cell-cycle regulatory proteins p21 and p53 were performed, and cell-cycle alterations were determined by means of FACS analysis. Experiments were performed in triplicate, and statistical significance was determined by using unpaired t tests. RESULTS: Butyrate increased nuclear factor kappa B transcriptional activity 4-fold relative to that seen in control cells (P =.05) in all non-small cell lung cancer cell lines. Treatment with bortezomib reduced butyrate-induced activation of nuclear factor kappa B to baseline levels. The proteins p21 and p53 were stabilized after treatment with bortezomib, correlating with a G(2)/M cell-cycle arrest. Treatment with butyrate alone resulted in minimal apoptosis, but combined histone deacetylase and proteasome inhibition increased apoptosis 3- to 4-fold (P =.02). CONCLUSIONS: Combined molecular targeting of histone deacteylases and proteasomes synergistically induced apoptosis in non-small cell lung cancer. Pharmacologic nuclear factor kappa B suppression through proteasome inhibition, followed by treatment with histone deacetylase inhibitors, might represent a novel treatment strategy for patients with non-small cell lung cancer.