Constitutive Activation of Src Kinase as a Mechanism of Acquired Resistance to Dasatinib in Triple Negative Breast Cancer.

Base Excision Repair (BER) addresses base lesions and abasic sites induced by exogenous and endogenous stressors. X-ray cross complementing group 1 (XRCC1) functions as a scaffold protein in BER and single-strand break repair (SSBR), facilitating and coordinating repair through its interaction with a host of critical repair proteins. Alterations of XRCC1 protein and gene expression levels are observed in many cancers, including colorectal, ovarian, and breast cancer. While increases in the expression level of XRCC1 are reported, the transcription factors responsible for this up-regulation are not known. In this study, we identify the signal transducer and activator of transcription 3 (STAT3) as a novel regulator of XRCC1 through chromatin immunoprecipitation. Activation of STAT3 through phosphorylation at Y705 by cytokine (IL-6) signaling increases the expression of XRCC1 and the occupancy of STAT3 within the XRCC1 promoter. In triple negative breast cancer, the constitutive activation of STAT3 upregulates XRCC1 gene and protein expression levels. Increased expression of XRCC1 is associated with aggressiveness and resistance to DNA damaging chemotherapeutics. Thus, we propose that activated STAT3 regulates XRCC1 under stress and growth conditions, but constitutive activation in cancers results in dysregulation of XRCC1 and subsequently BER and SSBR.

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Acquired resistance to combined BET and CDK4/6 inhibition in triple-negative breast cancer

Nature Communications ◽

10.1038/s41467-020-16170-3 ◽

2020 ◽

Vol 11 (1) ◽

Cited By ~ 2

Author(s):

Jennifer Y. Ge ◽

Shaokun Shu ◽

Mijung Kwon ◽

Bojana Jovanović ◽

Katherine Murphy ◽

...

Keyword(s):

Breast Cancer ◽

Triple Negative Breast Cancer ◽

Triple Negative ◽

Acquired Resistance

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Dasatinib Treatment Increases Sensitivity to c-Met Inhibition in Triple-Negative Breast Cancer Cells

Cancers ◽

10.3390/cancers11040548 ◽

2019 ◽

Vol 11 (4) ◽

pp. 548 ◽

Cited By ~ 4

Author(s):

Patricia Gaule ◽

Nupur Mukherjee ◽

Brendan Corkery ◽

Alex Eustace ◽

Kathy Gately ◽

...

Keyword(s):

Breast Cancer ◽

Triple Negative Breast Cancer ◽

Triple Negative ◽

Kinase Inhibitor ◽

Combined Treatment ◽

Single Agent ◽

Src Kinase ◽

Ic50 Value ◽

Met Inhibitor ◽

Dasatinib Treatment

In pre-clinical studies, triple-negative breast cancer (TNBC) cells have demonstrated sensitivity to the multi-targeted kinase inhibitor dasatinib; however, clinical trials with single-agent dasatinib showed limited efficacy in unselected populations of breast cancer, including TNBC. To study potential mechanisms of resistance to dasatinib in TNBC, we established a cell line model of acquired dasatinib resistance (231-DasB). Following an approximately three-month exposure to incrementally increasing concentrations of dasatinib (200 nM to 500 nM) dasatinib, 231-DasB cells were resistant to the agent with a dasatinib IC50 value greater than 5 μM compared to 0.04 ± 0.001 µM in the parental MDA-MB-231 cells. 231-DasB cells also showed resistance (2.2-fold) to the Src kinase inhibitor PD180970. Treatment of 231-DasB cells with dasatinib did not inhibit phosphorylation of Src kinase. The 231-DasB cells also had significantly increased levels of p-Met compared to the parental MDA-MB-231 cells, as measured by luminex, and resistant cells demonstrated a significant increase in sensitivity to the c-Met inhibitor, CpdA, with an IC50 value of 1.4 ± 0.5 µM compared to an IC50 of 6.8 ± 0.2 µM in the parental MDA-MB-231 cells. Treatment with CpdA decreased p-Met and p-Src in both 231-DasB and MDA-MB-231 cells. Combined treatment with dasatinib and CpdA significantly inhibited the growth of MDA-MB-231 parental cells and prevented the emergence of dasatinib resistance. If these in vitro findings can be extrapolated to human cancer treatment, combined treatment with dasatinib and a c-Met inhibitor may block the development of acquired resistance and improve response rates to dasatinib treatment in TNBC.

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Diverse Roles of Annexin A6 in Triple-Negative Breast Cancer Diagnosis, Prognosis and EGFR-Targeted Therapies

Cells ◽

10.3390/cells9081855 ◽

2020 ◽

Vol 9 (8) ◽

pp. 1855 ◽

Cited By ~ 1

Author(s):

Olga Y. Korolkova ◽

Sarrah E. Widatalla ◽

Stephen D. Williams ◽

Diva S. Whalen ◽

Heather K. Beasley ◽

...

Keyword(s):

Breast Cancer ◽

Tumor Suppressor ◽

Triple Negative Breast Cancer ◽

Kinase Inhibitors ◽

Triple Negative ◽

Acquired Resistance ◽

Breast Cancer Diagnosis ◽

Scaffolding Protein ◽

Poor Overall Survival ◽

Suppressor Activity

The calcium (Ca2+)-dependent membrane-binding Annexin A6 (AnxA6), is a multifunctional, predominantly intracellular scaffolding protein, now known to play relevant roles in different cancer types through diverse, often cell-type-specific mechanisms. AnxA6 is differentially expressed in various stages/subtypes of several cancers, and its expression in certain tumor cells is also induced by a variety of pharmacological drugs. Together with the secretion of AnxA6 as a component of extracellular vesicles, this suggests that AnxA6 mediates distinct tumor progression patterns via extracellular and/or intracellular activities. Although it lacks enzymatic activity, some of the AnxA6-mediated functions involving membrane, nucleotide and cholesterol binding as well as the scaffolding of specific proteins or multifactorial protein complexes, suggest its potential utility in the diagnosis, prognosis and therapeutic strategies for various cancers. In breast cancer, the low AnxA6 expression levels in the more aggressive basal-like triple-negative breast cancer (TNBC) subtype correlate with its tumor suppressor activity and the poor overall survival of basal-like TNBC patients. In this review, we highlight the potential tumor suppressor function of AnxA6 in TNBC progression and metastasis, the relevance of AnxA6 in the diagnosis and prognosis of several cancers and discuss the concept of therapy-induced expression of AnxA6 as a novel mechanism for acquired resistance of TNBC to tyrosine kinase inhibitors.

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Retinoic Acid Sensitivity of Triple-Negative Breast-Cancer Cells Characterized by Constitutive Activation of the NOTCH1 Pathway: The Role of RARβ

10.21203/rs.3.rs-53959/v1 ◽

2020 ◽

Author(s):

Gabriela Paroni ◽

Adriana Zanetti ◽

Maria Monica Barzago ◽

Mami Kurosaki ◽

Luca Guarrera ◽

...

Keyword(s):

Breast Cancer ◽

Retinoic Acid ◽

Rna Sequencing ◽

Cell Lines ◽

Triple Negative Breast Cancer ◽

Proliferative Activity ◽

Triple Negative ◽

Proliferation Index ◽

Constitutive Activation ◽

Sequencing Studies

Abstract Background: All-trans retinoic-acid (ATRA) is a promising agent in the personalized treatment/chemo-prevention of breast-cancer. Triple-negative breast-cancer (TNBC) accounts for 15-20% of all mammary tumours and share common features such as a high proliferation index and a basal-like gene expression signature. In spite of this, TNBC is very heterogeneous and lacks effective therapeutic strategies.Methods: We profile eighteen TNBC breast-cancer cell-lines for their sensitivity to the anti-proliferative action of ATRA. In addition, we perform RNA-sequencing studies in two of the most sensitive cell-lines exposed to ATRA, a γ-secretase inhibitor and combinations thereof. Results: The only three TNBC cell-lines (HCC-1599, MB-157 and MDA-MB-157) endowed with ATRA-sensitivity are characterized by constitutive activation of the NOTCH1 γ-secretase product, N1ICD and we identify the associated genetic aberrations of the NOTCH1-gene. N1ICD expression renders HCC-1599, MB-157 and MDA-MB-157 cells sensitive not only to ATRA, but also to γ-secretase inhibitors, like DAPT [N-(N-(3,5-difluorophenacetyl)-L-alanyl)-S-phenylglycine-t-butyl-ester] and PF-03084014. The anti-proliferative action of ATRA and γ-secretase inhibitors is complementary, as combinations of ATRA and DAPT or PF-03084014 cause synergistic effects. This synergism is confirmed in mouse xenografts of HCC-1599 cells. RNA-sequencing studies performed in HCC-1599 and MB-157 cells exposed to ATRA and DAPT demonstrate that the two compounds act on common gene-sets, some of which belong to the NOTCH1 pathway. ATRA inhibits the growth of HCC-1599, MB-157 and MDA-MB-157 cells via RARα, which up-regulates several retinoid target-genes, including RARβ. RARβ induction is observed only in HCC-1599, MB-157 and MDA-MB-157 cells, as the other TNBC cell-lines lack ATRA-dependent stimulation of the retinoid-receptor. RARβ is a key determinant of ATRA anti-proliferative activity, as its silencing suppresses the effects exerted by the retinoid. Conclusions: We demonstrate that ATRA exerts a significant anti-tumor action in TNBC cells characterized by constitutive NOTCH1 activation. We show that ATRA enhances the anti-tumor activity of γ-secretase inhibitors in an additive/synergistic manner. We support the idea that ATRA anti-proliferative activity is mediated by the Retinoid-Acid-Receptor-β (RARβ). The present study represents the basis for the design of clinical trials on the efficacy of combinations between ATRA and γ-secretase inhibitors in the treatment of patients affected by a specific subtype of TNBC.

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Lapatinib-induced annexin A6 upregulation as an adaptive response of triple-negative breast cancer cells to EGFR tyrosine kinase inhibitors

Carcinogenesis ◽

10.1093/carcin/bgy192 ◽

2018 ◽

Vol 40 (8) ◽

pp. 998-1009 ◽

Cited By ~ 5

Author(s):

Sarrah E Widatalla ◽

Olga Y Korolkova ◽

Diva S Whalen ◽

J Shawn Goodwin ◽

Kevin P Williams ◽

...

Keyword(s):

Breast Cancer ◽

Tyrosine Kinase ◽

Tyrosine Kinase Inhibitors ◽

Triple Negative Breast Cancer ◽

Plasma Membranes ◽

Kinase Inhibitors ◽

Triple Negative ◽

Acquired Resistance ◽

Cholesterol Depletion ◽

Late Endosomes

Abstract The epidermal growth factor receptor (EGFR) is a major oncogene in triple-negative breast cancer (TNBC), but the use of EGFR-targeted tyrosine kinase inhibitors (TKI) and therapeutic monoclonal antibodies is associated with poor response and acquired resistance. Understanding the basis for the acquired resistance to these drugs and identifying biomarkers to monitor the ensuing resistance remain a major challenge. We previously showed that reduced expression of annexin A6 (AnxA6), a calcium-dependent membrane-binding tumor suppressor, not only promoted the internalization and degradation of activated EGFR but also sensitized TNBC cells to EGFR-TKIs. Here, we demonstrate that prolong (>3 days) treatment of AnxA6-low TNBC cells with lapatinib led to AnxA6 upregulation and accumulation of cholesterol in late endosomes. Basal extracellular signal-regulated kinase 1 and 2 (ERK1/2) activation was EGFR independent and significantly higher in lapatinib-resistant MDA-MB-468 (LAP-R) cells. These cells were more sensitive to cholesterol depletion than untreated control cells. Inhibition of lapatinib-induced upregulation of AnxA6 by RNA interference (A6sh) or withdrawal lapatinib from LAP-R cells not only reversed the accumulation of cholesterol in late endosomes but also led to enrichment of plasma membranes with cholesterol, restored EGFR-dependent activation of ERK1/2 and sensitized the cells to lapatinib. These data suggest that lapatinib-induced AnxA6 expression and accumulation of cholesterol in late endosomes constitute an adaptive mechanism for EGFR-expressing TNBC cells to overcome prolong treatment with EGFR-targeted TKIs and can be exploited as an option to inhibit and/or monitor the frequently observed acquired resistance to these drugs.

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