Non-canonical AR activity facilitates endocrine resistance in breast cancer

The role of androgen receptor (AR) in endocrine-resistant breast cancer is controversial and clinical trials targeting AR with an AR antagonist (e.g., enzalutamide) have been initiated. Here, we investigated the consequence of AR antagonism using in vitro and in vivo models of endocrine resistance. AR antagonism in MCF7-derived tamoxifen-resistant (TamR) and long-term estrogen-deprived breast cancer cell lines were achieved using siRNA-mediated knockdown or pharmacological inhibition with enzalutamide. The efficacy of enzalutamide was further assessed in vivo in an estrogen-independent endocrine-resistant patient-derived xenograft (PDX) model. Knockdown of AR inhibited the growth of the endocrine-resistant cell line models. Microarray gene expression profiling of the TamR cells following AR knockdown revealed perturbations in proliferative signaling pathways upregulated in endocrine resistance. AR loss also increased some canonical ER signaling events and restored sensitivity of TamR cells to tamoxifen. In contrast, enzalutamide did not recapitulate the effect of AR knockdown in vitro, even though it inhibited canonical AR signaling, which suggests that it is the non-canonical AR activity that facilitated endocrine resistance. Enzalutamide had demonstrable efficacy in inhibiting AR activity in vivo but did not affect the growth of the endocrine-resistant PDX model. Our findings implicate non-canonical AR activity in facilitating an endocrine-resistant phenotype in breast cancer. Unlike canonical AR signaling which is inhibited by enzalutamide, non-canonical AR activity is not effectively antagonized by enzalutamide, and this has important implications in the design of future AR-targeted clinical trials in endocrine-resistant breast cancer.

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Alpelisib Inhibits PIK3CA-Mutant Breast Cancer Growth Through AKT-Dependent Bim Induction and Mcl-1 Degradation

10.21203/rs.3.rs-38718/v1 ◽

2020 ◽

Author(s):

Xiao Tan ◽

Zhongqiang Zhang ◽

Ping Liu ◽

Hongliang Yao ◽

jingshan tong

Keyword(s):

Breast Cancer ◽

Cell Lines ◽

Acquired Resistance ◽

Proteasome Inhibitors ◽

Resistant Cell ◽

Breast Cancer Cell Lines ◽

Breast Cancers ◽

Akt Inhibitor

Abstract Background: PIK3CA mutations are common genomic alterations in estrogen receptor (ER)-positive breast cancers, currently, the development of selective PI3Kα (phosphatidylinositol 3-kinase α) inhibitors is ongoing. The mechanisms contributing to the anticancer activity of alpelisib in PIK3CA-mutant breast cancer cells and the mechanism of acquired resistance to alpelisib remain elusive. Methods: Drug-sensitive cell lines were exposed to alpelisib to establish alpelisib-resistant cell lines. Western blotting was used to assess changes in protein expression. Apoptosis was evaluated by ﬂow cytometry. In vivo with mouse xenograft models and in vitro colony formation and MTS and assay were carried out to determine the growth inhibitory effects of the tested drugs. Protein half-lives were examined and proteasome inhibitors were used to estimate protein degradation. Gene knockdown was carried out using shRNA or siRNA. Results: In the present study, we report the potent induction of apoptosis by alpelisib in PIK3CA-mutant breast cancer cell lines. AKT phosphorylation suppression, AKT/Foxo3a-dependent Bim induction, and AKT/GSK-3β-dependent Mcl-1 degradation were observed. Apoptosis induced by alpelisib was attenuated by Mcl-1 (4A) overexpression or Bim suppression. Furthermore, alpelisib could not modulate Mcl-1 or Bim levels in cell lines that were resistant to alpelisib. AKT inhibitor and alpelisib combination restored the sensitivity of alpelisib-resistant cells to growth inhibition and apoptosis in vitro and in vivo. Conclusions: Therefore, modulation of Mcl-1 degradation and AKT-dependent Bim induction are crucial for mediating the resistance and sensitivity of PIK3CA-mutant breast tumor cells to alpelisib, thus making it a productive strategy for overcoming acquired resistance to alpelisib.

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LPTO-06. A NOVEL BRAIN-PERMEANT CHEMOTHERAPEUTIC AGENT FOR THE TREATMENT OF BREAST CANCER LEPTOMENINGEAL METASTASIS

Neuro-Oncology Advances ◽

10.1093/noajnl/vdz014.029 ◽

2019 ◽

Vol 1 (Supplement_1) ◽

pp. i7-i7

Author(s):

Jiaojiao Deng ◽

Sophia Chernikova ◽

Wolf-Nicolas Fischer ◽

Kerry Koller ◽

Bernd Jandeleit ◽

...

Keyword(s):

Breast Cancer ◽

Brain Tumors ◽

Cell Lines ◽

Chemotherapeutic Agent ◽

Leptomeningeal Metastasis ◽

Breast Cancer Cell Lines ◽

Normal Brain ◽

Breast Cancers

Abstract Leptomeningeal metastasis (LM), a spread of cancer to the cerebrospinal fluid and meninges, is universally and rapidly fatal due to poor detection and no effective treatment. Breast cancers account for a majority of LMs from solid tumors, with triple-negative breast cancers (TNBCs) having the highest propensity to metastasize to LM. The treatment of LM is challenged by poor drug penetration into CNS and high neurotoxicity. Therefore, there is an urgent need for new modalities and targeted therapies able to overcome the limitations of current treatment options. Quadriga has discovered a novel, brain-permeant chemotherapeutic agent that is currently in development as a potential treatment for glioblastoma (GBM). The compound is active in suppressing the growth of GBM tumor cell lines implanted into the brain. Radiolabel distribution studies have shown significant tumor accumulation in intracranial brain tumors while sparing the adjacent normal brain tissue. Recently, we have demonstrated dose-dependent in vitro and in vivo anti-tumor activity with various breast cancer cell lines including the human TNBC cell line MDA-MB-231. To evaluate the in vivo antitumor activity of the compound on LM, we used the mouse model of LM based on the internal carotid injection of luciferase-expressing MDA-MB-231-BR3 cells. Once the bioluminescence signal intensity from the metastatic spread reached (0.2 - 0.5) x 106 photons/sec, mice were dosed i.p. twice a week with either 4 or 8 mg/kg for nine weeks. Tumor growth was monitored by bioluminescence. The compound was well tolerated and caused a significant delay in metastatic growth resulting in significant extension of survival. Tumors regressed completely in ~ 28 % of treated animals. Given that current treatments for LM are palliative with only few studies reporting a survival benefit, Quadriga’s new agent could be effective as a therapeutic for both primary and metastatic brain tumors such as LM. REF: https://onlinelibrary.wiley.com/doi/full/10.1002/pro6.43

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Epigenetic approaches to cancer therapy

Biochemical Society Transactions ◽

10.1042/bst0321095 ◽

2004 ◽

Vol 32 (6) ◽

pp. 1095-1097 ◽

Cited By ~ 21

Author(s):

J.A. Plumb ◽

N. Steele ◽

P.W. Finn ◽

R. Brown

Keyword(s):

Dna Methylation ◽

Cell Line ◽

Gene Promoter ◽

Resistant Cell ◽

Resistant Cell Line ◽

Tumour Suppressor Genes ◽

Control Of Gene Expression ◽

Hmlh1 Gene

Histone deacetylation and DNA methylation have a central role in the control of gene expression, including transcriptional repression of tumour suppressor genes. Loss of DNA mismatch repair due to methylation of the hMLH1 gene promoter results in resistance to cisplatin in vitro and in vivo. The cisplatin-resistant cell line A2780/cp70 is 8-fold more resistant to cisplatin than the non-resistant cell line, and has the hMLH1 gene methylated. Treatment with an inhibitor of DNA methyltransferase, DAC (2-deoxy-5′-azacytidine), results in a partial reversal of DNA methylation, re-expression of MLH1 (mutL homologue 1) and sensitization to cisplatin both in vitro and in vivo. PXD101 is a novel hydroxamate type histone deacetylase inhibitor that shows antitumour activity in vivo and is currently in phase I clinical evaluation. Treatment of A2780/cp70 tumour-bearing mice with DAC followed by PXD101 results in a marked increase in the number of cells that re-express MLH1. Since the clinical use of DAC may be limited by toxicity and eventual re-methylation of genes, we suggest that the combination of DAC and PXD101 could have a role in increasing the efficacy of chemotherapy in patients with tumours that lack MLH1 expression due to hMLH1 gene promoter methylation.

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Blockade of CDK7 Reverses Endocrine Therapy Resistance in Breast Cancer

International Journal of Molecular Sciences ◽

10.3390/ijms21082974 ◽

2020 ◽

Vol 21 (8) ◽

pp. 2974 ◽

Cited By ~ 2

Author(s):

Yasmin M. Attia ◽

Samia A. Shouman ◽

Salama A. Salama ◽

Cristina Ivan ◽

Abdelrahman M. Elsayed ◽

...

Keyword(s):

Breast Cancer ◽

Tumor Volume ◽

Apoptotic Cell ◽

Therapy Resistance ◽

Tamoxifen Treatment ◽

Clinical Samples ◽

Breast Cancer Cell Lines ◽

Breast Cancer Patients

Cyclin-dependent kinase (CDK)-7 inhibitors are emerging as promising drugs for the treatment of different types of cancer that show chemotherapy resistance. Evaluation of the effects of CDK7 inhibitor, THZ1, alone and combined with tamoxifen is of paramount importance. Thus, in the current work, we assessed the effects of THZ1 and/or tamoxifen in two estrogen receptor-positive (ER+) breast cancer cell lines (MCF7) and its tamoxifen resistant counterpart (LCC2) in vitro and in xenograft mouse models of breast cancer. Furthermore, we evaluated the expression of CDK7 in clinical samples from breast cancer patients. Cell viability, apoptosis, and genes involved in cell cycle regulation and tamoxifen resistance were determined. Tumor volume and weight, proliferation marker (Ki67), angiogenic marker (CD31), and apoptotic markers were assayed. Bioinformatic data indicated CDK7 expression was associated with negative prognosis, enhanced pro-oncogenic pathways, and decreased response to tamoxifen. Treatment with THZ1 enhanced tamoxifen-induced cytotoxicity, while it inhibited genes involved in tumor progression in MCF-7 and LCC2 cells. In vivo, THZ1 boosted the effect of tamoxifen on tumor weight and tumor volume, reduced Ki67 and CD31 expression, and increased apoptotic cell death. Our findings identify CDK7 as a possible therapeutic target for breast cancer whether it is sensitive or resistant to tamoxifen therapy.

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Detection of the 170 kDa P-Glycoprotein in Neoplastic and Normal Tissues

Tumori Journal ◽

10.1177/030089168907500605 ◽

1989 ◽

Vol 75 (6) ◽

pp. 542-546 ◽

Cited By ~ 10

Author(s):

Enrico Ronchi ◽

Ornella Sanfilippo ◽

Giovanni Di Fronzo ◽

Maria Rosa Bani ◽

Gabriella Della Torre ◽

...

Keyword(s):

Protein A ◽

Resistant Cell ◽

Nodal Metastasis ◽

Resistant Cell Line ◽

Resistant Variant ◽

Normal Tissues ◽

Immunoblotting Assay ◽

Human Solid Tumors

A membrane purification procedure and an immunoblotting assay have been designed to allow screening of human solid tumors for overexpression of the GP170 glycoprotein without employing a disaggregation method to obtain cell suspensions. The electrophoresed membrane proteins were probed, after Western Blotting, with the C219 monoclonal antibody and iodinated Protein A. The labeling intensity of the bands on the autoradioimmunoblots were quantified by densitometry. To test for the presence of GP170, we used membranes from the UV 2237 fibrosarcoma line and its adriamycin-resistant variant ADMR, grown in vitro or as solid tumor in mice. Membranes of human normal and tumor tissues obtained from previously untreated patients were also tested. An immunoreaction was observed in the adriamycin-resistant UV 2237 lines grown in vitro or in vivo. Quantitatively, the binding of the resistant cell line grown in vitro was higher than that observed in cells grown in mice. Bands in the GP 170 region were observed in 4/7 normal and in 7/7 tumor colon tissues and in the normal medulla from 2 patients with cancer of the renal cortex. No reaction could be found in samples from normal tissue, primary tumor or nodal metastasis from 7 patients with breast cancer.

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Improvement in the Anti-Tumor Efficacy of Doxorubicin Nanosponges in In Vitro and in Mice Bearing Breast Tumor Models

Cancers ◽

10.3390/cancers12010162 ◽

2020 ◽

Vol 12 (1) ◽

pp. 162 ◽

Cited By ~ 4

Author(s):

Monica Argenziano ◽

Casimiro Luca Gigliotti ◽

Nausicaa Clemente ◽

Elena Boggio ◽

Benedetta Ferrara ◽

...

Keyword(s):

Breast Cancer ◽

Cancer Cell ◽

Substantial Reduction ◽

Cancer Growth ◽

Breast Cancer Cell Lines ◽

Cell Cycle Distribution ◽

High Accumulation ◽

New Formulation

Doxorubicin (DOX) is an anthracycline widely used in cancer therapy and in particular in breast cancer treatment. The treatment with DOX appears successful, but it is limited by a severe cardiotoxicity. This work evaluated the in vitro and in vivo anticancer effect of a new formulation of β-cyclodextrin nanosponges containing DOX (BNS-DOX). The BNS-DOX effectiveness was evaluated in human and mouse breast cancer cell lines in vitro in terms of effect on cell growth, cell cycle distribution, and apoptosis induction; and in vivo in BALB-neuT mice developing spontaneous breast cancer in terms of biodistribution, cancer growth inhibition, and heart toxicity. BNS-DOX significantly inhibited cancer cell proliferation, through the induction of apoptosis, with higher efficiency than free DOX. The breast cancer growth in BALB-neuT mice was inhibited by 60% by a BNS-DOX dose five times lower than the DOX therapeutic dose, with substantial reduction of tumor neoangiogenesis and lymphangiogenesis. Biodistribution after BNS-DOX treatment revealed a high accumulation of DOX in the tumor site and a low accumulation in the hearts of mice. Results indicated that use of BNS may be an efficient strategy to deliver DOX in the treatment of breast cancer, since it improves the anti-cancer effectiveness and reduces cardiotoxicity.

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Isoform-specific promotion of breast cancer tumorigenicity by TBX3 involves induction of angiogenesis

Laboratory Investigation ◽

10.1038/s41374-019-0326-6 ◽

2019 ◽

Vol 100 (3) ◽

pp. 400-413

Author(s):

Milica Krstic ◽

Haider M. Hassan ◽

Bart Kolendowski ◽

M. Nicole Hague ◽

Pieter. H. Anborgh ◽

...

Keyword(s):

Breast Cancer ◽

Molecular Subtype ◽

Xenograft Model ◽

Tumor Formation ◽

Transcriptional Analysis ◽

Breast Cancer Cell Lines ◽

Tumor Vascularity ◽

Mouse Xenograft Model

Abstract TBX3 is a member of the highly conserved family of T-box transcription factors involved in embryogenesis, organogenesis and tumor progression. While the functional role of TBX3 in tumorigenesis has been widely studied, less is known about the specific functions of the different isoforms (TBX3iso1 and TBX3iso2) which differ in their DNA-binding domain. We therefore sought to investigate the functional consequence of this highly conserved splice event as it relates to TBX3-induced tumorigenesis. By utilizing a nude mouse xenograft model, we have identified differential tumorigenic potential between TBX3 isoforms, with TBX3iso1 overexpression more commonly associated with invasive carcinoma and high tumor vascularity. Transcriptional analysis of signaling pathways altered by TBX3iso1 and TBX3iso2 overexpression revealed significant differences in angiogenesis-related genes. Importantly, osteopontin (OPN), a cancer-associated secreted phosphoprotein, was significantly up-regulated with TBX3iso1 (but not TBX3iso2) overexpression. This pattern was observed across three non/weakly-tumorigenic breast cancer cell lines (21PT, 21NT, and MCF7). Up-regulation of OPN in TBX3iso1 overexpressing cells was associated with induction of hyaluronan synthase 2 (HAS2) expression and increased retention of hyaluronan in pericellular matrices. These transcriptional changes were accompanied by the ability to induce endothelial cell vascular channel formation by conditioned media in vitro, which could be inhibited through addition of an OPN neutralizing antibody. Within the TCGA breast cancer cohort, we identified an 8.1-fold higher TBX3iso1 to TBX3iso2 transcript ratio in tumors relative to control, and this ratio was positively associated with high-tumor grade and an aggressive molecular subtype. Collectively, the described changes involving TBX3iso1-dependent promotion of angiogenesis may thus serve as an adaptive mechanism within breast cancer cells, potentially explaining differences in tumor formation rates between TBX3 isoforms in vivo. This study is the first of its kind to report significant functional differences between the two TBX3 isoforms, both in vitro and in vivo.

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The Effect of Leucine Restriction on Akt/mTOR Signaling in Breast Cancer Cell Lines In Vitro and In Vivo

Nutrition and Cancer ◽

10.1080/01635581.2011.523504 ◽

2011 ◽

Vol 63 (2) ◽

pp. 264-271 ◽

Cited By ~ 10

Author(s):

Gopal Singh ◽

Argun Akcakanat ◽

Chandeshwar Sharma ◽

David Luyimbazi ◽

Katherine Naff ◽

...

Keyword(s):

Breast Cancer ◽

Cell Lines ◽

Cancer Cell ◽

Breast Cancer Cell ◽

Cancer Cell Lines ◽

Mtor Signaling ◽

Breast Cancer Cell Lines

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Oncostatin M suppresses oestrogen receptor-α expression and is associated with poor outcome in human breast cancer

Endocrine Related Cancer ◽

10.1530/erc-11-0326 ◽

2012 ◽

Vol 19 (2) ◽

pp. 181-195 ◽

Cited By ~ 44

Author(s):

Nathan R West ◽

Leigh C Murphy ◽

Peter H Watson

Keyword(s):

Breast Cancer ◽

Mrna Expression ◽

Oestrogen Receptor ◽

Oncostatin M ◽

Breast Cancer Cell Lines ◽

Dependent Manner ◽

Cancer Management ◽

Er Expression

The most important clinical biomarker for breast cancer management is oestrogen receptor alpha (ERα). Tumours that express ER are candidates for endocrine therapy and are biologically less aggressive, while ER-negative tumours are largely treated with conventional chemotherapy and have a poor prognosis. Despite its significance, the mechanisms regulating ER expression are poorly understood. We hypothesised that the inflammatory cytokine oncostatin M (OSM) can downregulate ER expression in breast cancer. Recombinant OSM potently suppressed ER protein and mRNA expression in vitro in a dose- and time-dependent manner in two human ER+ breast cancer cell lines, MCF7 and T47D. This was dependent on the expression of OSM receptor beta (OSMRβ) and could be blocked by inhibition of the MEKK1/2 mitogen-activated protein kinases. ER loss was also necessary for maximal OSM-induced signal transduction and migratory activity. In vivo, high expression of OSM and OSMR mRNA (determined by RT-PCR) was associated with reduced ER (P<0.01) and progesterone receptor (P<0.05) protein levels in a cohort of 70 invasive breast cancers. High OSM and OSMR mRNA expression was also associated with low expression of ESR1 (ER, P<0.0001) and ER-regulated genes in a previously published breast cancer gene expression dataset (n=321 cases). In the latter cohort, high OSMR expression was associated with shorter recurrence-free and overall survival in univariate (P<0.0001) and multivariate (P=0.022) analyses. OSM signalling may be a novel factor causing suppression of ER and disease progression in breast cancer.

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pH Sensitive Lipid-Polymer Hybrid Nanoparticles Mediated Delivery of Docetaxel: A Viable Approach for Breast Cancer Therapeutic Intervention Development

10.21203/rs.3.rs-23464/v1 ◽

2020 ◽

Author(s):

Ye Yuan ◽

Jia-Xing Song ◽

Mei-Na Zhang ◽

Baoshan Yuan

Keyword(s):

Breast Cancer ◽

Cellular Uptake ◽

Intervention Development ◽

Ph Sensitive ◽

Therapeutic Interventions ◽

Hybrid Nanoparticles ◽

Breast Cancer Cell Lines ◽

Polymer Hybrid

Abstract Present study was planned for the development of pH sensitive lipid polymer hybrid nanoparticles (pHS-LPHNPs) loaded with docetaxel (DTX) for guided and target specific cytosolic-delivery delivery of docetaxel (DTX). pHS-LPHNPs were formulated to entrap DTX by self-assembled nano-precipitation technique and characterised with respect to zeta potential, particle-size, entrapment efficiency, PDI as well as invitro drug release. The cell viability, apoptosis, cellular-uptake, pharmacokinetics, bio-distribution in vital organs, % changes in tumour volume and survival of breast cancer bearing animals were used for the evaluation of efficacy of the formulation. In-vitro studies showed increased cytotoxicity at lower IC50 and better cellular-uptake of pHS-LPHNPs mediated drug by breast cancer cell lines. We saw the better rate of apoptosis of breast cancer cells via Annexin V/Propidium iodide staining. Moreover, in-vivo studies demonstrated improved pharmacokinetics and targetability with minimum drug circulation in deep-seated organs upon delivery of DTX via pHS-LPHNPs in comparison with LPHNPs-DTX and free DTX. We observed sizeable % reduction in tumour-burden with pHS-LPHNPs-DTXthan that withLPHNPs-DTX &free DTX. In brief, pHS-LPHNPs mediated delivery of DTX exhibited promising approach for developing therapeutic-interventions against breast-cancer.

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