Project description:SKBR-3 HER2+ breast cancer cells were treated with 25 nM Dharmacon siGENOME non-targeting (NT) siRNA control pool or siRNA pool targeting FOXA1 for 48h, then treated with either DMSO or 300nM lapatinib for 24h.
Project description:SKBR-3 and BT474m1 HER2+ breast cancer cell lines were treated with lapatinib, JQ1, or lapatinib and JQ1 or (for SKBR-3) treated with siRNA pools (non-targeting control or FOXA1) prior to drug treatment before being used for ChIPseq (BRD4, MED1, H3K27Ac, or FOXA1 (for SKBR-3))
Project description:SKBR-3 or BT474m1 HER2+ breast cancer cells were treated with either DMSO, 300nM lapatinib, 300nM JQ1, or lapatinib and JQ1 in combination for 48h.
Project description:Inhibition of the HER2/ERBB2 receptor is a keystone to treating HER2-positive malignancies, particularly breast cancer, but a significant fraction of HER2-positive (HER2+) breast cancers recur or fail to respond. Anti-HER2 monoclonal antibodies, like trastuzumab or pertuzumab, and ATP active site inhibitors like lapatinib, commonly lack durability because of adaptive changes in the tumor leading to resistance. HER2+ cell line responses to inhibition with lapatinib were analyzed by RNAseq and ChIPseq to characterize transcriptional and epigenetic changes. Motif analysis of lapatinib-responsive genomic regions implicated the pioneer transcription factor FOXA1 as a mediator of adaptive responses. Lapatinib in combination with FOXA1 depletion led to dysregulation of enhancers, impaired adaptive upregulation of HER3, and decreased proliferation. HER2-directed therapy using clinically relevant drugs (trastuzumab with or without lapatinib or pertuzumab) in a 7-day clinical trial designed to examine early pharmacodynamic response to antibody-based anti-HER2 therapy showed reduced FOXA1 expression was coincident with decreased HER2 and HER3 levels, decreased proliferation gene signatures, and increased immune gene signatures. This highlights the importance of the immune response to anti-HER2 antibodies and suggests that inhibiting FOXA1-mediated adaptive responses in combination with HER2 targeting is a potential therapeutic strategy.
Project description:Inhibition of the HER2/ERBB2 receptor is a keystone to treating HER2-positive malignancies, particularly breast cancer, but a significant fraction of HER2-positive (HER2+) breast cancers recur or fail to respond. Anti-HER2 monoclonal antibodies, like trastuzumab or pertuzumab, and ATP active site inhibitors like lapatinib, commonly lack durability because of adaptive changes in the tumor leading to resistance. HER2-directed therapy using clinically relevant drugs (trastuzumab with or without lapatinib or pertuzumab) in a 7-day clinical trial (ClinicalTrials.gov Identifier: NCT01875666, LCCC1214) designed to examine early pharmacodynamic response to antibody-based anti-HER2 therapy showed reduced FOXA1 transcription factor expression was coincident with decreased HER2 and HER3 levels, decreased proliferation gene signatures, and increased immune gene signatures. Patient samples from this trial, when sufficient material was available, were also subjected to kinase enrichment using multiplexed kinase inhibitor bead affinity chromatography and LC-MS/MS. Strongly responsive transcriptional responses observed in a subset of patients corresponded to decreased binding of CDK1 and DDR1 by our proteomic approach. Taken together, our results highlight the importance of the immune response to anti-HER2 antibodies and suggests that inhibiting FOXA1-mediated adaptive responses in combination with HER2 targeting is a potential therapeutic strategy.
Project description:Despite advances in HER2-targeted therapeutics, resistance remains a significant clinical problem in HER2-positive (HER2+) breast cancer, especially in the metastatic setting. Drug-tolerant persisters (DTPs), a sub-population of cancer cells that survive via reversible, non-genetic mechanisms, are implicated in resistance to tyrosine kinase inhibitors (TKIs) in several cancer models, but DTPs for HER2-targeted TKIs have not been characterized extensively. We found that upon treatment with the TKI lapatinib, HER2+ breast cancer lines yielded DTPs with luminal-like or mesenchymal-like transcriptional programs and differential sensitivity to lapatinib/anti-estradiol combinations. Lentiviral barcoding and single cell RNA-sequencing indicate that HER2+/ER+ cells cycle stochastically through a pre-DTP state, characterized by a G0-like signature, which uniquely gives rise to DTPs upon lapatinib exposure.
Project description:Adjuvant docetaxel, carboplatin, and trastuzumab (TCH) is a standard regimen for HER2+ breast cancer. Dual HER2-blockade with lapatinib (L) and trastuzumab demonstrated significant activity in the metastatic and neoadjuvant settings. This study evaluates neoadjuvant TC plus trastuzumab (H) and/or lapatinib (L). This study demonstrated a similar pCR rate with TCH and TCHL and a lower rate of pCR with TCL. Treatment-related toxicity limited the ability for participants to receive protocol-specified chemotherapy and HER2-targeted therapy in the TCHL Arm.
Project description:Adjuvant docetaxel, carboplatin, and trastuzumab (TCH) is a standard regimen for HER2+ breast cancer. Dual HER2-blockade with lapatinib (L) and trastuzumab demonstrated significant activity in the metastatic and neoadjuvant settings. This study evaluates neoadjuvant TC plus trastuzumab (H) and/or lapatinib (L). This study demonstrated a similar pCR rate with TCH and TCHL and a lower rate of pCR with TCL. Treatment-related toxicity limited the ability for participants to receive protocol-specified chemotherapy and HER2-targeted therapy in the TCHL Arm.
Project description:To identify genes, whose loss of function confers drug resistance to lapatinib, we performed a genome-wide CRISPR/Cas9 gene knockout screening in two human gastric cancer cell lines harboring HER2 amplification, N87 and OE19, respectively. By performing this study, we identiied a goup of genes associated with lapatinib resistance in HER2-amplified gastric cancer.