Project description:Phosphatidylinositol-3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway activation contributes to mantle cell lymphoma (MCL) pathogenesis and drug resistance. However, the use of mTOR inhibitors as single agents have shown limited clinical efficacy in relation with drug activation of feedback loops. Selective PI3K inhibition or dual PI3K/mTOR catalytic inhibition are different therapeutic approaches developed to achieve effective pathway blockage. Here, we evaluated the antitumor activity of a mTOR inhibitor, a pan-PI3K inhibitor and a dual PI3K/mTOR inhibitor in primary MCL cells. We found that dual PI3K/mTOR inhibitor modulated angiogenesis, tumor invasiveness and cytokine signaling compared to a mTOR inhibitor and a pan-PI3K inhibitor in MCL. We used microarrays to compare the effect of these three compounds in MCL and identified distinct classes of down-regulated genes modulated by each compound. Global RNA expression in primary cells from two MCL patients treated with a mTOR inhibitor, a pan-PI3K inhibitor and a dual PI3K/mTOR inhibitor for 8 hours
Project description:Blocking BRD4 or HDACs induces paradoxically similar gene expression, comparably attenuates PI3K/AKT inhibitor resistance in multiple cancer cells.
Project description:We explored potential bypass mechanisms to PI3K/mTOR-directed therapy in KRAS mutant CRC models, utilizing genetically engineered mouse models (GEMM) to generate acquired resistance to the targeted dual PI3K/mTOR small molecule inhibitor PF-04691502. Transcriptomic analysis revealed a dynamic stem-like progenitor signature which was increased in the presence of drug pressure.
Project description:Phosphatidylinositol-3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway activation contributes to mantle cell lymphoma (MCL) pathogenesis and drug resistance. However, the use of mTOR inhibitors as single agents have shown limited clinical efficacy in relation with drug activation of feedback loops. Selective PI3K inhibition or dual PI3K/mTOR catalytic inhibition are different therapeutic approaches developed to achieve effective pathway blockage. Here, we evaluated the antitumor activity of a mTOR inhibitor, a pan-PI3K inhibitor and a dual PI3K/mTOR inhibitor in primary MCL cells. We found that dual PI3K/mTOR inhibitor modulated angiogenesis, tumor invasiveness and cytokine signaling compared to a mTOR inhibitor and a pan-PI3K inhibitor in MCL. We used microarrays to compare the effect of these three compounds in MCL and identified distinct classes of down-regulated genes modulated by each compound.
Project description:Analysis of the effects of a dual specificity PI3K/mTOR inhibitor on two human ovarian cell lines, OV2008 and MCAS. Results provide insight into the adaptive response to PI3K/mTOR inhibition in matrix attached ovarian cancer cells. The PI3K/mTOR-pathway is the most commonly deregulated pathway in epithelial cancers and thus represents an important target for cancer therapeutics. Here we show that dual inhibition of PI3K/mTOR in ovarian cancer 3D-spheroids leads to death of the inner matrix-deprived cells, whereas matrix-attached cells are resistant. Resistance is associated with up-regulation of a cellular survival program that involves both FOXO-regulated transcription and a novel translational resistance mechanism resulting in specific up-regulation of IRES-mediated, cap-independent translation. Inhibition of any of several up-regulated proteins, including Bcl-2, EGFR, or IGF1R, abrogates resistance to dual PI3K/mTOR inhibition. These results demonstrate that acute adaptive response to PI3K/mTOR inhibition resembles well-conserved adaptive response to nutrient and growth factor deprivation and how development of rational drug combinations can bypass resistance mechanisms. Total RNA was isolated 6h and 24h after treatment with 1 M-NM-<M NVP-BEZ235 or DMSO vehicle control from 3D grown structures
Project description:In an effort to understand the mechanisms of acquired resistance to BRAF inhibitors, we isolated clones that acquired resistance to the BRAF inhibitor GSK2118436 derived from the A375 BRAF V600E mutant melanoma cell line. This resistance clones acquired mutations in NRAS and MEK1. One clones, 16R6-4, acquired two mutations in NRAS – Q61K and A146T. Proliferation and western blot analyses demonstrated that these clones were insensitive to single agent GSK2118436 or GSK1120212 (an allosteric MEK inhibitor) but were sensitive to the combination of GSK2118436 and GSK1120212. To further characterize this combination, global transcriptomic analysis was performed in A375 and 16R6-4 after 24 hour treatment with GSK2118436, GSK1120212 or the combination of GSK2118436 and GSK1120212. This data set was published in Molecular Cancer Therapeutics with the title “Combined inhibition of BRAF and MEK, BRAF and PI3K/mTOR, or MEK and PI3K/mTOR overcomes acquired resistance to the BRAF inhibitor GSK2118436, mediated by NRAS or MEK mutations” by Greger, J.G., et.al. A375 and 16R6-4 (an A375 derived GSK2118436 resistance clone) were treated for 24 hours with 0.1 micromolar GSK2118436, 1 micromolar GSK2118436, 0.01 micromolar GSK1120212, 0.1 micromolar GSK2118436 + 0.01 micromolar GSK1120212, or 1 micromolar GSK2118436 + 0.01 micromolar GSK1120212.
Project description:Metastatic squamous cell carcinoma suggest mTOR inhibitor as therapeutic agent because of activation of the PI3K/AKT/mTOR pathway. However, many therapeutic agents about cancer show resistance. Here, we investigated resistance network about mTOR inhibitor in skin squamous cell carcinoma using microarray. Our study identified that CCND1 overexpression increase resistance about mTOR inhibitor. The molecular mechanism may improve in therapeutic effects of mTOR inhibitor in cutaneous SCC.
Project description:Blocking BRD4 or HDACs induces paradoxically similar gene expression, comparably attenuates PI3K/AKT inhibitor resistance in multiple cancer cells.
Project description:Acquisition of resistance to PI3K/AKT-targeted monotherapy regardless of cancer types implies the existence of common mechanisms. Here we demonstrate that while causing glycolysis crisis, acetyl-CoA shortage and global decrease of histone acetylation, PI3K/AKT inhibitors induce drug resistance by selectively augmenting CBP/p300, H3K27 acetylation and BRD4 binding at genomic loci of a subset of growth factor and receptor (GF/R) genes. BRD4 occupation at these loci and drug resistant cell growth are vulnerable to both bromodomain and HDAC inhibitors. Little or none occupation of HDACs at the GF/R gene loci underscores the paradox that cells respond equivalently to the two classes of inhibitors with opposite modes of action. Targeting this unique epigenetic vulnerability offers a general solution to overcome PI3K/AKT inhibitor resistance in different cancers.