PI3K inhibition in ER+ breast cancer microarray data
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PROVIDER: PRJNA114891 | ENA |
REPOSITORIES: ENA
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Project description:Gene expression data of breast cancer samples before and after PI3K inhibition In the study presented here, we evaluated the expression profiles of a total of 105 unique genes in 6 breast cancer samples before and after PI3K-inhibitor therapy
2015-04-15 | E-GEOD-63579 | biostudies-arrayexpress
Project description:Activating mutations of PIK3CA are the most frequent genomic alterations in estrogen receptor (ER)-positive breast tumors and selective PI3Kα inhibitors are in clinical development. The activity of these agents, however, is not homogenous and only a fraction of patients bearing PIK3CA-mutant ER-positive tumors benefit from single agent administration. Searching for mechanisms of resistance, we observed that suppression of PI3K signaling with different agents results in induction of ER-dependent transcriptional activity as demonstrated by changes in expression in genes containing ER binding sites, enhanced ER transcription and increased occupancy by the ER of promoter regions of upregulated genes. Furthermore, expression of ESR1 mRNA and ER protein levels themselves were also increased upon PI3K inhibition. These changes in gene expression were confirmed in vivo in xenograft and patient derived models and in tumors from patients undergoing treatment with the PI3Kα inhibitor BYL719. The observed effects on transcription were enhanced by the addition of estradiol and suppressed by the anti-ER therapies fulvestrant and tamoxifen. Fulvestrant markedly sensitized ER-positive tumors to PI3Kα inhibition. We propose that increased ER transcriptional activity may be a compensatory mechanism that limits the activity of PI3K inhibitors and that combined PI3K and ER inhibition is a rational approach to target these tumors. The aim of our study was to explore the mechanism by which combination of PI3K pathway inhibitors and estrogen receptor function blockade results in superior antitumor activity. We aimed to evaluate whether changes in ER function were influencing the clinical response to anti-PI3K therapy in ER-positive breast tumors that harbor PI3K pathway activation. For this purpose, we planned to use various specific PI3K inhibitors, namely: BYL719 (p110α specific catalytic inhibitor), GDC0941 (pan-PI3K inhibitor), GDC0032 and BAY80-6946 (p110sparing PI3K inhibitors) in a panel of ER-positive breast cancer cell lines and xenografts that harbor PIK3CA activating mutations. We also used MK2206 (pan-AKT allosteric inhibitor) to inhibit the PI3K pathway in ER-positive cell lines which activate this pathway through PTEN loss. Finally, in order to evaluate the role of ER up-regulation as a pro-survival signal in our in vitro and in vivo models, we planned to use the selective ER modulator 4-hydroxy-tamoxifen (4-OHT) and degrader fulvestrant. For the in vivo experiments, the number of animals in each group was calculated to measure a 25% difference between the means of placebo and treatment groups with a power of 80% and a p value of 0.01. Host mice carrying xenografts were randomly and equally assigned to either control or treatment groups. Animal experiments were conducted in a controlled and non-blinded manner. Moreover, we evaluated by means of RNAseq gene expression changes breast cancer patients that underwent BYL719 based therapy to validate our in vitro findings in terms of ER expression. In vitro experiments were performed at least two times and at least in triplicate for each replica.
2015-04-29 | E-GEOD-64033 | biostudies-arrayexpress
Project description:Gene expression data of breast cancer samples before and after PI3K inhibition
2015-04-15 | GSE63579 | GEO
Project description:The phosphoinositide 3-kinase (PI3K) pathway integrates extracellular stimuli to phosphorylate and activate key downstream effectors such as AKT and serum-and glucocorticoid-inducible kinase (SGK1). We have previously reported that the PI3K pathway regulates ER-dependent transcription in breast cancer through the phosphorylation of the epigenetic regulator KMT2D by AKT. Here, we provide new insights into how the PI3K pathway propagates its effects to control KMT2D and ER function via SGK1, another PI3K downstream effector. Specifically, we show that PI3K inhibition, via a negative feedback loop, activates SGK1 to promote chromatin-based regulation of ER-dependent gene expression. PI3K/AKT inhibitors activate ER, which subsequently promotes SGK1 transcription through direct binding to its promoter. Elevated SGK1, in turn, phosphorylates KMT2D, suppressing its function and altering the chromatin landscape to attenuate ER-dependent expression. Thus, we have determined that SGK1 regulates the chromatin landscape and ER-dependent transcription via the direct phosphorylation of KMT2D. These findings reveal an ER-SGK1-KMT2D signaling circuit aimed to attenuate ER response through a previously unknown role for SGK1 to program chromatin and ER transcriptional output.
2019-04-02 | GSE119522 | GEO
Project description:Activating mutations of PIK3CA are the most frequent genomic alterations in estrogen receptor (ER)-positive breast tumors and selective PI3Kα inhibitors are in clinical development. The activity of these agents, however, is not homogenous and only a fraction of patients bearing PIK3CA-mutant ER-positive tumors benefit from single agent administration. Searching for mechanisms of resistance, we observed that suppression of PI3K signaling with different agents results in induction of ER-dependent transcriptional activity as demonstrated by changes in expression in genes containing ER binding sites, enhanced ER transcription and increased occupancy by the ER of promoter regions of upregulated genes. Furthermore, expression of ESR1 mRNA and ER protein levels themselves were also increased upon PI3K inhibition. These changes in gene expression were confirmed in vivo in xenograft and patient derived models and in tumors from patients undergoing treatment with the PI3Kα inhibitor BYL719. The observed effects on transcription were enhanced by the addition of estradiol and suppressed by the anti-ER therapies fulvestrant and tamoxifen. Fulvestrant markedly sensitized ER-positive tumors to PI3Kα inhibition. We propose that increased ER transcriptional activity may be a compensatory mechanism that limits the activity of PI3K inhibitors and that combined PI3K and ER inhibition is a rational approach to target these tumors.
2015-04-29 | GSE64033 | GEO
Project description:The high frequency of aberrant PI3K pathway activation in hormone receptor-positive (HR+) breast cancer has led to the development, clinical testing, and approval of the p110a-selective PI3K inhibitor alpelisib. The limited clinical efficacy of alpelisib and other PI3K inhibitors is partially attributed to the functional antagonism between PI3K and estrogen receptor (ER) signaling, which is mitigated via combined PI3K inhibition and endocrine therapy. We and others have previously demonstrated chromatin-associated mechanisms by which PI3K supports cancer development and antagonizes ER signaling through the modulation of the H3K4 methylation axis; inhibition of KDM5A promoter H3K4 demethylation and KMT2D/MLL4-directed enhancer H3K4 methylation. Here we show that inhibition of the H3K4 histone methyltransferase MLL1 in combination with PI3K inhibition impairs HR+ breast cancer clonogenicity and cell proliferation. While combined PI3K/MLL1 inhibition reduces PI3K/AKT signaling and H3K4 methylation, MLL1 inhibition increases PI3K/AKT signaling and dysregulates the expression of processes that lead to AKT activation. These data reveal a feedback loop between MLL1 and AKT whereby MLL1 inhibition reactivates AKT. We show that combined PI3K and MLL1 inhibition synergizes to cause cell death in in vitro and in vivo models of HR+ breast cancer, which is enhanced by the additional genetic ablation of the H3K4 methyltransferase and AKT target KMT2D/MLL4. Together, our data provide evidence of a feedback mechanism connecting histone methylation with AKT and may support the preclinical development and testing of pan-MLL inhibitors.
2022-10-01 | GSE214329 | GEO
Project description:The high frequency of aberrant PI3K pathway activation in hormone receptor-positive (HR+) breast cancer has led to the development, clinical testing, and approval of the p110a-selective PI3K inhibitor alpelisib. The limited clinical efficacy of alpelisib and other PI3K inhibitors is partially attributed to the functional antagonism between PI3K and estrogen receptor (ER) signaling, which is mitigated via combined PI3K inhibition and endocrine therapy. We and others have previously demonstrated chromatin-associated mechanisms by which PI3K supports cancer development and antagonizes ER signaling through the modulation of the H3K4 methylation axis; inhibition of KDM5A promoter H3K4 demethylation and KMT2D/MLL4-directed enhancer H3K4 methylation. Here we show that inhibition of the H3K4 histone methyltransferase MLL1 in combination with PI3K inhibition impairs HR+ breast cancer clonogenicity and cell proliferation. While combined PI3K/MLL1 inhibition reduces PI3K/AKT signaling and H3K4 methylation, MLL1 inhibition increases PI3K/AKT signaling and dysregulates the expression of processes that lead to AKT activation. These data reveal a feedback loop between MLL1 and AKT whereby MLL1 inhibition reactivates AKT. We show that combined PI3K and MLL1 inhibition synergizes to cause cell death in in vitro and in vivo models of HR+ breast cancer, which is enhanced by the additional genetic ablation of the H3K4 methyltransferase and AKT target KMT2D/MLL4. Together, our data provide evidence of a feedback mechanism connecting histone methylation with AKT and may support the preclinical development and testing of pan-MLL inhibitors.
2022-10-01 | GSE214331 | GEO
Project description:Although pre-clinical and clinical studies on PARP1 inhibitors, alone and in combination with DNA-damaging agents, show promising results, further ways to improve and broaden the scope of application of this therapeutic approach are warranted. To this end, we have investigated the possibility of improving the response of BRCA1 mutant breast cancer cells to PARP1 inhibition by co-targeting the PI3K pathway. The human breast cancer cell line MDA-MB-436, which lacks the expression of both BRCA1 and PTEN, was treated with the PARP1 inhibitor AG014699 as a single agent or in combination with the PI3K inhibitor LY294002 for 7 days. The human breast cancer cell line MDA-MB-436 was treated with the PARP1 inhibitor AG014699 as a single agent or in combination with the PI3K inhibitor LY294002 for 7 days. All treatments were performed in triplicates. Total RNA was extracted hybridized onto the Illumina HumanHT-12 v4.0 microarray platform.
2012-01-19 | E-GEOD-34817 | biostudies-arrayexpress
Project description:Breast cancer is the second most common cancer type worldwide, representing 25% of all cancers in women. PIK3CA is one of the most frequently mutated genes in breast cancer and mutations result in constitutive activation of the PI3K/mTOR pathway. More than 30 inhibitors against PI3K/mTOR are being tested in clinical trials, however, resistance mechanisms evolve frequently resulting in disease progression. The aim of our study was to investigate PIK3CA collaborative mutations that result in resistance to BYL719, a PI3Kα selective inhibitor. For this purpose, we used a genome-wide PiggyBac transposon mediated mutagenesis screen in a PIK3CAH1047R mutated murine tumor model. One of the tumor suppressor genes discovered was neurofibromin 1 (NF1). Using shRNA-mediated knockdown and CRISPR/Cas9-mediated knockout of NF1 in murine and human PIK3CAH1047R cell lines and a patient derived xenograft organoid model, we found that NF1 loss reduces sensitivity to PI3Kα inhibition. Additionally, we find that loss of NF1 correlates with enhanced glycolysis and lower levels of ROS. Unexpectedly, treatment with NAC sensitized NF1 KO cells to PI3K inhibition in vitro, and in vivo. Global phospho-proteomics indicated that the combination with NAC enhances the inhibitory effect of PI3K inhibition on mTOR signaling, which inhibits proliferation of NF1 KO tumor cells. This raises the interesting possibility to combine PI3K inhibition with NAC especially in NF1 loss tumors
2023-03-30 | PXD034644 | Pride
Project description:The RNA-Seq analysed the changes in protease gene expression upon short-term PI3K inhibition in three breast cancer cell lines.
2021-12-31 | GSE186196 | GEO