The altered transcriptome and DNA methylation profiles of docetaxel resistance in breast cancer PDX models

Taxanes are standard therapy in clinical practice for metastatic breast cancer; however, primary or acquired chemoresistance are a common cause of mortality. Breast cancer patient-derived xenografts (PDX) are powerful tools for the study of cancer biology and drug treatment response. Specific DNA methylation patterns have been associated to different breast cancer subtypes but its association with chemoresistance remains unstudied. Aiming to elucidate docetaxel resistance mechanisms, we performed genome-wide DNA methylation in breast cancer PDX models, including luminal and triple-negative breast cancer (TNBC) models sensitive to docetaxel, their matched models after emergence of chemoresistance and residual disease after short-term docetaxel treatment. We found that DNA methylation profiles from breast cancer PDX models maintain the subtype-specific methylation patterns of clinical samples. Two main DNA methylation clusters were found in TNBC PDX and remain stable during the emergence of docetaxel resistance; however, some genes/pathways were differentially methylated according to docetaxel response. A DNA methylation signature of resistance able to segregate TNBC based on chemotherapy response was identified. Transcriptomic profiling of selected sensitive/resistant pairs and integrative analysis with methylation data demonstrated correlation between some differentially methylated and expressed genes in docetaxel-resistant TNBC PDX models. Multiple gene expression changes were found after the emergence of docetaxel resistance in TNBC. DNA methylation and transcriptional changes identified between docetaxel-sensitive and -resistant TNBC PDX models or residual disease may have predictive value for chemotherapy response in TNBC. IMPLICATIONS: Subtype-specific DNA methylation patterns are maintained in breast cancer PDX models. While no global methylation changes were found, we uncovered differentially DNA methylated and expressed genes/pathways associated with the emergence of docetaxel resistance in TNBC

Resistance to taxanes in triple negative breast cancer associates with the dynamics of a CD49f+ tumor initiating population

Taxanes are a mainstay of treatment for breast cancer, but resistance often develops followed by metastatic disease and mortality. Aiming to reveal the mechanisms underlying taxane resistance, we used breast cancer patient-derived orthoxenografts (PDX). Mimicking clinical behavior, triple-negative breast tumors (TNBCs) from PDX models were more sensitive to docetaxel than luminal tumors, but they progressively acquired resistance upon continuous drug administration. Mechanistically, we found that a CD49f+ chemoresistant population with tumor-initiating ability is present in sensitive tumors and expands during the acquisition of drug resistance. In the absence of the drug, the resistant CD49f+ population shrinks and taxane sensitivity is restored. We describe a transcriptional signature of resistance, predictive of recurrent disease after chemotherapy in TNBC. Together, these findings identify a CD49f+ population enriched in tumor-initiating ability and chemoresistance properties and evidence a drug holiday effect on the acquired resistance to docetaxel in triple-negative breast cancer

Epigenetic inactivation of the splicing RNA-binding protein CELF2 in human breast cancer.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked DownloadHuman tumors show altered patterns of protein isoforms that can be related to the dysregulation of messenger RNA alternative splicing also observed in transformed cells. Although somatic mutations in core spliceosome components and their associated factors have been described in some cases, almost nothing is known about the contribution of distorted epigenetic patterns to aberrant splicing. Herein, we show that the splicing RNA-binding protein CELF2 is targeted by promoter hypermethylation-associated transcriptional silencing in human cancer. Focusing on the context of breast cancer, we also demonstrate that CELF2 restoration has growth-inhibitory effects and that its epigenetic loss induces an aberrant downstream pattern of alternative splicing, affecting key genes in breast cancer biology such as the autophagy factor ULK1 and the apoptotic protein CARD10. Furthermore, the presence of CELF2 hypermethylation in the clinical setting is associated with shorter overall survival of the breast cancer patients carrying this epigenetic lesion.Health Department PERIS-project of the Catalan Government (Generalitat de Catalunya) AGAUR of the Catalan Government (Generalitat de Catalunya) Instituto de Salud Carlos III Ministerio de Economia y Competitividad (MINECO) European Union (EU) Foundation CELLEX La Caixa Foundatio

Identification of mechanisms of acquired resistance to taxanes in triple negative breast cancer using patient-derived xenografts: a step closer to clinics

[eng] Chemotherapy is a general treatment for most breast tumors and depending on breast cancer subtype combination with targeted anti-hormonal or anti-HER2 therapy is conducted. Taxane-based regimens constitute the most common therapeutic option in patients with triple negative breast cancer (TNBC), but resistance often develops followed by metastatic disease and mortality. Aiming to reveal the mechanisms underlying taxane resistance, we used breast cancer patient-derived xenografts (PDX). Mimicking clinical behavior, triple-negative breast tumors (TNBCs) from PDX models were more sensitive to docetaxel than luminal tumors, but they progressively acquired resistance upon continuous drug administration. We analyzed cancer stem cell population dynamics in paired sensitive and resistant TNBC PDX models, but also epigenomics, genomics and transcriptomics profiles to elucidate the unknown molecular mechanisms responsible for this process. Mechanistically, we found that a CD49f+ chemoresistant population with tumor-initiating ability is present in sensitive tumors and expands during the acquisition of drug resistance. In the absence of the drug, the resistant CD49f+ population shrinks and taxane sensitivity is restored. We describe a transcriptional signature of resistance, predictive of recurrent disease after chemotherapy in TNBC. Together, these findings identify a CD49f+ population enriched in tumor-initiating ability and chemoresistance properties and evidence a drug holiday effect on the acquired resistance to docetaxel in triple-negative breast cancer. Exome sequencing was also performed in the matched sensitive and docetaxel resistant TNBC PDX models. Multiple mutations, small insertion/deletions and copy number variation (CNV) changes were detected in the original human metastatic samples, and most of them were maintained in serially passaged TNBC PDX models even after long term treatment with docetaxel, with very few changes being detected between paired sensitive and resistant tumors. However, we identified a chromosomal amplification of chr12p arm present in the metastatic sample and chemoresistant PDXs of one BRCA1 mutant models which was absent in docetaxel sensitive PDXs. Increased expression levels of genes located at chr12p correlated with amplificacion in chemoresistant tumors. Clinical data from TCGA and METABRIC studies confirmed that chr12p amplification was associated with a small subset of TNBC/basal-like breast cancer patients with increased gene expression of genes from that region and poor survival after chemotherapy. Our findings suggest that there is a subset of TNBC/basal-like breast cancer harbouring chr12p amplification that may be associated with resistance to docetaxel treatment in clinical setting. Genome-wide DNA methylation and gene expression analysis have been performed in preclinical breast cancer patient-derived xenograft (PDX) models with primary and acquired chemoresistance. These analyses revealed that DNA methylation patterns from breast cancer PDX are closer to breast cancer clinical samples than breast cancer cell lines (BCCLs) and they maintain subtype specific methylation patterns. Triple negative PDX tumors show very stable methylation patterns accompanying chemoresistance acquisition but some critical genes/pathways were unraveled as differentially methylated. Transcriptomically, TNBC PDX tumors accumulate gene expression changes during chemoresistance acquisition with some common pathways between different triple negative PDX models. Integrative analysis reveals correlation of some differentially methylated genes as differentially expressed in resistant triple negative breast cancer PDX tumors. These findings identify a set of promising pathways that may contribute to the acquisition of chemoresistance in TNBC patients. Receptor activator of NF-κB (RANK) is expressed in human breast tumors and has been associated with aggressive breast cancers. In this study we used breast cancer PDX models to investigate the functional role of RANK and its ligand (RANKL) in clinical human breast cancer. RANK expression in human breast cancer is more frequent in ER/PR-negative than in hormone receptor positive tumors and that is maintained in breast cancer PDX models. RANKL is generally poorly expressed in human breast cancer, but some RANKL-positive breast cancer PDX models were identified. Selection of RANK/RANKL-positive breast cancer PDX models expressing different levels of RANK or RANKL was done in order to functionally study the role of RANK signalling in human breast cancer. In vitro RANKL treatment on breast cancer cells isolated from RANK/RANKL-positive PDX models show modulation of NF-κB pathway, even in tumors where RANK expression was very low.[spa] La quimioterapia es un tratamiento general usado comúnmente en cáncer de mama, sobretodo en tumores del subtipo triple negativo (TNBC). Éstos responden inicialmente muy bien, pero con el tiempo suelen dar lugar a recidivas o metástasis quimioresistentes. Empleando modelos preclínicos de cáncer de mama hemos estudiado los mecanismos subyacentes de la adquisición de resistencia a taxanos mediante análisis de poblaciones celulares, así como de análisis epigenómicos, genómicos y transcriptómicos Con el estudio de dinámicas poblacionales descubrimos la existencia en tumores TNBC inicialmente sensibles la existencia de una población CD49f+ con capacidad de iniciación tumoral que se expande durante la adquisición de quimioresistencia. Esta población revierte en ausencia de droga y con ella la quimioresistencia. Además, describimos una firma transcripcional de resistencia, predictivo de recidiva de la enfermedad después de la quimioterapia de TNBC. Los análisis genómicos revelaron la existencia de mútiples mutaciones y aberraciones cromosómicas en las muestras de pacientes que se mantienen de forma estable en los modelos preclínicos, aún con la adquisición de quimioresistencia. Únicamente se detectó una amplificación del cromosoma 12 en tumores resistentes no presente en sensibles. Esta amplificación se asocia en muestras clínicas a un subgrupo de tumores TNBC con peor supervivencia que el resto, pudiendo ser quimioresistentes. Los análisis epigenómicos revelaron la utilidad de estos modelos preclínicos al ser muy cercanos a muestras clínicas y mantener los patrones asociados a cada subtipo de cáncer de mama. Estos patrones son tan estables que prácticamente no varían con la adquisición de quimioresistencia, sin embargo algunos genes y rutas concretos sí lo hacen. Los análisis genómicos mostraron algunas vías comunes alteradas y un análisis integrador de los datos de metilación y expresión mostraron genes y rutas afectadas que presentaban metilación y expresión diferencial con la adquisición de resistencia

Rockens text

Idag har de överlevande rockhjältarna från 50- och 60-talen för länge sedan gått in i den gyllene medelåldern. Hur man än definierar den är rocken knappast någon ungdomsmusik längre. Det finns visserligen genrer som bidrar till att dra upp gränserna mot den äldre generationen, såsom rap eller house. Men samtidigt präglas dessa genrer av en självreflexivitet, som lett till en brandskattning av rockhistorien och öppnat en ny möjlighet: att upptäcka ett förflutet som också är föräldrarnas och därigenom överskrida generationsgränserna. Även ur den aspekt som intresserar mig här, nämligen ordets roll i rock, är utvecklingen motsägelsefull. 60-talet grundlade föreställningen att texter skulle vara så ”meningsfulla” att det gick att trycka dem i antologier med ”rockpoesi”. Nu ser vi å ena sidan hur ordet i house reduceras till några få, nätt och jämnt hörbara fraser som upprepas gång på gång, å den andra hur det sväller över alla bräddar och lösgörs från bundenheten till en melodi i rap. Att texten har minskat i betydelse i den ena genren och ökat i den andra verkar uppenbart. Men talar vi om det semantiska innehållet blir resultatet inte lika självklart. Talströmmens oavbrutna flöde och kaskaderna av rim har ett egenvärde i rapen, som handlar om att hävda den egna subjektiviteten gentemot ett i rocktraditionen välbekant hot om anonymisering och utplåning. Vad som sägs kan vara mindre viktigt än hur och t o m att något sägs. I den här artikeln, som baserar sig på en större studie jag är syssel-satt med, vill jag ifrågasätta några vanliga föreställningar om ordets betydelse i rock.1 Den första av dessa är helt enkelt den att det skulle gå att säga något definitivt i den frågan. Det tror jag alltså inte. En andra går ut på att rocktexter (i motsats till poesi) skulle kunna förstås som ren genrediktning. Det tror jag inte heller. Men deras komplexitet är inte lyrisk, utan knuten till att de är avsedda att uppföras, vilket är artikelns huvudpoäng

Dual Fatty Acid Synthase and HER2 Signaling Blockade Shows Marked Antitumor Activity against Breast Cancer Models Resistant to Anti-HER2 Drugs

Blocking the enzyme Fatty Acid Synthase (FASN) leads to apoptosis of HER2-positive breast carcinoma cells. The hypothesis is that blocking FASN, in combination with anti-HER2 signaling agents, would be an effective antitumor strategy in preclinical HER2+ breast cancer models of trastuzumab and lapatinib resistance. We developed and molecularly characterized in vitro HER2+ models of resistance to trastuzumab (SKTR), lapatinib (SKLR) and both (SKLTR). The cellular interactions of combining anti-FASN polyphenolic compounds (EGCG and the synthetic G28UCM) with anti-HER2 signaling drugs (trastuzumab plus pertuzumab and temsirolimus) were analyzed. Tumor growth inhibition after treatment with EGCG, pertuzumab, temsirolimus or the combination was evaluated in two in vivo orthoxenopatients: one derived from a HER2+ patient and another from a patient who relapsed on trastuzumab and lapatinib-based therapy. SKTR, SKLR and SKLTR showed hyperactivation of EGFR and p-ERK1/2 and PI3KCA mutations. Dual-resistant cells (SKLTR) also showed hyperactivation of HER4 and recovered levels of p-AKT compared with mono-resistant cells. mTOR, p-mTOR and FASN expression remained stable in SKTR, SKLR and SKLTR. In vitro, anti-FASN compounds plus pertuzumab showed synergistic interactions in lapatinib- and dual-resistant cells and improved the results of pertuzumab plus trastuzumab co-treatment. FASN inhibitors combined with temsirolimus displayed the strongest synergistic interactions in resistant cells. In vivo, both orthoxenopatients showed strong response to the antitumor activity of the combination of EGCG with pertuzumab or temsirolimus, without signs of toxicity. We showed that the simultaneous blockade of FASN and HER2 pathways is effective in cells and in breast cancer models refractory to anti-HER2 therapie