Project description:Resistant tumours are thought to arise from the action of Darwinian selection on intratumoral genetic heterogeneity. However, clonal selection is incompatible with the late recurrence often characterising luminal breast cancers treated with endocrine therapy (ET), suggesting a more complex interplay between genetic and non-genetic factors. In the present study, we dissect the contributions of clonal genetic diversity and transcriptional plasticity during the early and late phases of ET at single-cell resolution. Using single-cell RNA-sequencing and imaging we disentangle the transcriptional variability of plastic cells and define a rare sub-population of pre-adapted (PA) cells which undergoes further transcriptomic reprogramming and copy number changes to acquire full resistance. PA cells show reduced oestrogen receptor α activity but increased features of quiescence and migration. We find evidence for sub-clonal expression of this PA signature in primary tumours and for dominant expression in clustered circulating tumour cells. We propose a multi-step model for ET resistance development and advocate the use of stage-specific biomarkers.
Project description:Around two thirds of breast tumors are characterized by the expression of estrogen receptor α and are therapeutically treated by blocking estrogen signaling. First line endocrine therapeutics are Tamoxifen which displaces estrogen form its receptor preventing receptor activation and aromatase inhibitors which prevent the formation of estrogen and thereby hormone-deprive the tumors. Therapy resistance remains a major clinical problem, especially for patients with late-stage diagnoses. Tumor heterogeneity may promote therapy resistance either through the selection of pre-existing rare clones or by providing a repertoire of cells that may develop resistance over time. In order to study endocrine therapy resistance on a clonal level, we have developed barcoded (allowing the tracking of single cells) endocrine therapy sensitive and resistant breast cancer cell lines. From these complex cell pools, multiple single cells characterized by a specific barcode were isolated and grown out. We then subjected the clones to phosphoproteomics measurement by Mass spectrometry. Based on their phosphorylation pattern, the kinase activity profiles of endocrine therapy resistant clones were determined to identify differentially activated kinases with implications in therapy resistance.
Project description:The estrogen receptor alpha (ERa) drives the growth of two-thirds of all breast cancers. Endocrine therapy impinges on estrogen-induced ERa activation to block tumor growth. However, half of ERa-positive breast cancers are tolerant or acquire endocrine therapy resistance. Here we demonstrate that breast cancer cells undergo genome-wide reprogramming of their chromatin landscape, defined by epigenomic maps and chromatin openness, as they acquire resistance to endocrine therapy. This reveals a role for the Notch pathway while excluding classical ERa signaling. In agreement, blocking Notch signaling, using gamma-secretase inhibitors, or targeting its downstream gene PBX1 abrogates growth of endocrine therapy-resistant breast cancer cells. Moreover Notch signaling through PBX1 directs a transcriptional program predictive of tumor outcome and endocrine therapy response. Comparing histone modifications (H3K4me2 and H3K36me3), chromatin openness (FAIRE) and PBX1 binding between endocrine therapy sensitive MCF7 and resistant MCF7-LTED cells.
Project description:Targeting metabolic adaptations in the breast cancer–liver metastatic niche using dietary approaches to improve endocrine therapy efficacy
Project description:The estrogen receptor alpha (ERa) drives the growth of two-thirds of all breast cancers. Endocrine therapy impinges on estrogen-induced ERa activation to block tumor growth. However, half of ERa-positive breast cancers are tolerant or acquire endocrine therapy resistance. Here we demonstrate that breast cancer cells undergo genome-wide reprogramming of their chromatin landscape, defined by epigenomic maps and chromatin openness, as they acquire resistance to endocrine therapy. This reveals a role for the Notch pathway while excluding classical ERa signaling. In agreement, blocking Notch signaling, using gamma-secretase inhibitors, or targeting its downstream gene PBX1 abrogates growth of endocrine therapy-resistant breast cancer cells. Moreover Notch signaling through PBX1 directs a transcriptional program predictive of tumor outcome and endocrine therapy response.
Project description:*** This submission includes RNA data, with DNA files available under a different accession number*** Purpose: Endocrine therapy resistance remains the greatest challenge for treating hormone receptor positive breast cancer patients. We aim to identify molecular mechanisms underlying endocrine therapy resistance through in-depth genomic analysis of patient samples. Experimental Design: We collected tumors from 35 estrogen receptor positive breast cancer patients receiving endocrine therapy, of which 3 patients had intrinsic resistance and 19 patients developed acquired resistance. For each patient, multiple tumor specimens were collected during the course of treatment. We performed DNA whole exome sequencing and RNA sequencing on all tumor samples. DNA mutations, copy number alterations and RNA gene expression data were analyzed through supervised analyses comparing paired sensitive and resistant tumor samples to identify molecular features related to endocrine therapy resistance. Results: We identified mutations enriched in resistant tumors including ESR1 and GATA3. ESR1 D538G variant confers endocrine therapy resistance while E380Q variant confers hypersensitivity. We demonstrate that resistant tumors had distinct gene expression profiles and elevated signaling pathways including ER, HER2, GATA3, AKT, RAS and p63 signaling. Integrated analysis for individual patient highlighted the heterogeneity of endocrine therapy resistance mechanisms. Conclusions: Our results suggest that mechanisms underlying endocrine therapy resistance are highly heterogeneous with diverse changes in genomic and transcriptomic levels.
Project description:Growth factor signaling and angiogenesis may promote endocrine-resistance in breast cancer and blocking these pathways can overcome resistance in preclinical models. We conducted a phase-II study of adding the VEGFR/Ras/Raf/MAPK inhibitor sorafenib to endocrine therapy in metastatic ER-positive breast cancer, either upon progression or after maximal response with measurable residual disease. Tumor biopsies and serum were collected on days 1 and 28. Primary endpoint was response by RECIST after 3 months and secondary endpoints included safety, time to progression (TTP), and biomarker assessment. Planned sample size was 43 patients but the study closed after 11 patients because of slow accrual. 8 patients had progressive disease (PD) on entry and 3 had stable disease (SD). One patient with SD discontinued sorafenib after 2-weeks because of grade 3 rash. Of the 10 remaining patients after adding sorafenib, 7 had SD (70%), 3 had PD (30%) and median TTP was 6.1-months. Of the 8 patients who entered the study with PD on endocrine therapy, 5 converted to SD (62%) with a median TTP of 6.4-months. Notably, patients on tamoxifen had a median TTP of 8.4-months. The most common adverse events were hypophosphatemia, hypokalemia, and rash, and the majority were grade 1&2 with no grade 4 toxicities. There was a significant reduction in serum VEGFR2 and PDGFR-α on day-28 (p-values 0.0035 and 0.017, respectively). Both serum VEGF and sVEGFR-1 were increased on day-28, but the differences were not statistically significant (p-values 0.3223 and 0.084, respectively). Microarray analysis identified 32 suppressed genes with an FDR of <0.20 and at least a 2-fold change with no induced genes and 29 KEGG pathways were enriched on day-28. Our study suggests that sorafenib can restore endocrine sensitivity, particularly tamoxifen, and this strategy of adding novel agents in patients progressing on endocrine therapy should be examined in future trials. This was a single-institution, phase II study of adding sorafenib to existing endocrine therapy. On study entry, eligible patients underwent serum sample collection and core biopsy of accessible disease (if applicable) on endocrine therapy and prior to starting sorafenib. Serum and a second biopsy were then collected on day 28. Sorafenib dose was 400mg orally twice daily along with continuing the same endocrine agent. Patients were followed monthly for clinical and toxicity evaluation. Disease response by RECIST criteria was assessed after 3 months by appropriate scans and these were obtained every 2 months thereafter until progression. Sorafenib and the endocrine agent were continued until disease progression or unacceptable toxicity
Project description:Invasive lobular cancer (ILC) accounts for approximately 10-15% of breast carcinomas and although it responds poorly to neoadjuvant chemotherapy, it appears to respond well to endocrine therapy. Pre- and on-treatment (after 2 weeks and 3 months) biopsies and surgical samples were obtained from 14 post-menopausal women with ER+ histologically confirmed ILC who responded to 3 months of neoadjuvant letrozole and were compared with a cohort of 14 responding infiltrating ductal carcinomas (IDCs) matched on clinicopathological features by gene expression profiling. Dynamic clinical response was assessed using periodic 3D ultrasound measurements performed during treatment and defined as a reduction of >70% in tumour volume by 3 months. The changes in gene expression in response to letrozole were highly consistent between responding ILC and IDC tumours, genes involved in proliferation were down-regulated and those involved with immune function and ECM remodelling were up-regulated. However, molecular differences between the histological subtypes were maintained upon treatment. This is the first study of molecular changes in ILC in response to endocrine therapy to date. The genes which change on letrozole are highly consistent between ILC and IDC. Differences in gene expression between ILC and IDC at diagnosis and are maintained at each time point on treatment. 14 Pre treatment, 10 two week and 14 three month on-treatment ILC and 14 Pre treatment, 14 two week and 14 three month on-treatment IDC samples from the same patients. Pre- and on-treatment samples from 7ILC & 6IDC patients were profiled on Illumina HT-12v4 (GPL10558) and samples from 7ILC and 8 IDC patients were profiled previously on Affymetrix U133A (GPL96) see GSE20181