Project description:We sought to determine genes whose expression changed upon treatment with a selective inhibitor of class I PI3 kinase. Total of 6 samples: cells were treated with GDC-0941 at a concentration of 1mM for 6 hours (3 replicates) and control (3 replicates)
Project description:Somatic NOTCH1 mutations are found in ~60% of T lineage acute lymphoblastic leukemias (T-ALLs). Notch1 is cleaved by γ secretase to generate activated Notch intracellular domain (NICD) proteins. The NOTCH1 mutations found in T-ALL constitutively activate Notch1 signaling by increasing NICD levels. Genetic alterations in components of the Ras/PI3 kinase (PI3K)/Akt pathway are also highly prevalent in T-ALL, and often coexist with NOTCH1 mutations. Exposing a T-ALL cell line to the PI3 kinase (PI3K) inhibitor GDC-0941 generated drug resistant clones that down-regulated NICD expression. To address the in vivo relevance of this unexpected observation, we transplanted primary wild-type (WT) and KrasG12D mutant T-ALLs into recipient mice, and treated them with GDC-0941 alone and in combination with the MEK inhibitor PD0325901 (PD901). Although many leukemias responded dramatically to these targeted agents in vivo, drug-resistant clones invariably emerged. Multiple resistant T-ALLs lost NICD expression through mechanisms that included loss of Notch1 mutations found in the parental T-ALL. These GDC-0941-resistant leukemias exhibited reduced expression of many Notch1 target genes, elevated levels of phosphorylated Akt (pAkt), and displayed cross-resistance to γ secretase inhibitors (GSIs). Consistent with these data, inhibiting Notch1 activity in T-ALL cells enhanced PI3K signaling, providing a likely mechanism for in vivo selection against clones with Notch1 pathway activation. Thus, oncogenic Notch1 mutations that promote clonal outgrowth during malignant transformation unexpectedly “switch” to become deleterious during treatment with a PI3K inhibitor. These data advance our understanding of T-ALL pathogenesis and have implications for implementing new therapeutic regimens. We analyzed 28 mouse T-ALL samples obtained after in vivo treatment with GDC-0941 alone or GDC-0941 + PD0325901. These T-ALL samples are either Kras wild type or harbor a KrasG12D mutations.
Project description:Despite decades of clinical use, mechanisms of glucocorticoid resistance are poorly understood. We treated primary murine T lineage acute lymphoblastic leukemias (T-ALLs) with the glucocorticoid dexamethasone (DEX) alone and in combination with the pan-PI3 kinase inhibitor GDC-0941 and observed a robust response to DEX that was modestly enhanced by GDC-0941. Continuous in vivo treatment invariably resulted in outgrowth of drug-resistant clones, ~30% of which showed markedly reduced glucocorticoid receptor (GR) protein expression. A similar proportion of relapsed human T-ALLs also exhibited low GR protein levels. De novo or pre-existing mutations in the gene encoding GR (Nr3c1) occurred in relapsed clones derived from multiple independent parental leukemias. CRISPR/Cas9 gene editing confirmed that loss of GR expression confers DEX resistance. Exposing drug-sensitive T-ALLs to DEX in vivo altered transcript levels of multiple genes, and this response was attenuated in relapsed T-ALLs. These data implicate reduced GR protein expression as a frequent cause of glucocorticoid resistance in T-ALL.
Project description:Somatic NOTCH1 mutations are found in ~60% of T lineage acute lymphoblastic leukemias (T-ALLs). Notch1 is cleaved by γ secretase to generate activated Notch intracellular domain (NICD) proteins. The NOTCH1 mutations found in T-ALL constitutively activate Notch1 signaling by increasing NICD levels. Genetic alterations in components of the Ras/PI3 kinase (PI3K)/Akt pathway are also highly prevalent in T-ALL, and often coexist with NOTCH1 mutations. Exposing a T-ALL cell line to the PI3 kinase (PI3K) inhibitor GDC-0941 generated drug resistant clones that down-regulated NICD expression. To address the in vivo relevance of this unexpected observation, we transplanted primary wild-type (WT) and KrasG12D mutant T-ALLs into recipient mice, and treated them with GDC-0941 alone and in combination with the MEK inhibitor PD0325901 (PD901). Although many leukemias responded dramatically to these targeted agents in vivo, drug-resistant clones invariably emerged. Multiple resistant T-ALLs lost NICD expression through mechanisms that included loss of Notch1 mutations found in the parental T-ALL. These GDC-0941-resistant leukemias exhibited reduced expression of many Notch1 target genes, elevated levels of phosphorylated Akt (pAkt), and displayed cross-resistance to γ secretase inhibitors (GSIs). Consistent with these data, inhibiting Notch1 activity in T-ALL cells enhanced PI3K signaling, providing a likely mechanism for in vivo selection against clones with Notch1 pathway activation. Thus, oncogenic Notch1 mutations that promote clonal outgrowth during malignant transformation unexpectedly “switch” to become deleterious during treatment with a PI3K inhibitor. These data advance our understanding of T-ALL pathogenesis and have implications for implementing new therapeutic regimens.
Project description:RNA Sequencing upon shRNA mediated depletion of RAF kinases or treatment with Cobimetinib (GDC-0973, 250nM, 6hrs) or with pan RAFi (AZ-628, 10uM, 6hrs)
Project description:PTK6 PROTAC treatment of T47D breast cancer cells were analyzed with mass spectrometry for determining PTK6 PROTAC specificity and global proteomic changes.
Project description:We were interested in characterizing the transcriptional changes that occur on a genome-wide scale following treatment of EGFR-mutant lung cancer cells with targeted therapies. HCC827 human lung cancer cells harboring an amplified EGFR allele with an activating in frame deletion of 15 nucleotides in exon 19 were treated in triplicate with 1uM erlotinib (EGFR inhibitor), AZD-6244 (MEK inhibitor) or BEZ-235 (PI3-Kinase/mTOR inhibitor) for 6 hours, followed by total mRNA isolation and whole transcriptome analysis using Affymetrix U133 Plus 2.0 expression arrays.