scholarly journals Counteracting Chemoresistance with Metformin in Breast Cancers: Targeting Cancer Stem Cells

Cancers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2482
Author(s):  
Samson Mathews Samuel ◽  
Elizabeth Varghese ◽  
Lenka Koklesová ◽  
Alena Líšková ◽  
Peter Kubatka ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Stem Cells ◽  
Cancer Stem Cells ◽  
Molecular Mechanisms ◽  
Epithelial Mesenchymal Transition ◽  
Acquired Resistance ◽  
Breast Cancers ◽  
Intrinsic Resistance ◽  
Mesenchymal Transition ◽  
Cancer Breast

Despite the leaps and bounds in achieving success in the management and treatment of breast cancers through surgery, chemotherapy, and radiotherapy, breast cancer remains the most frequently occurring cancer in women and the most common cause of cancer-related deaths among women. Systemic therapeutic approaches, such as chemotherapy, although beneficial in treating and curing breast cancer subjects with localized breast tumors, tend to fail in metastatic cases of the disease due to (a) an acquired resistance to the chemotherapeutic drug and (b) the development of intrinsic resistance to therapy. The existence of cancer stem cells (CSCs) plays a crucial role in both acquired and intrinsic chemoresistance. CSCs are less abundant than terminally differentiated cancer cells and confer chemoresistance through a unique altered metabolism and capability to evade the immune response system. Furthermore, CSCs possess active DNA repair systems, transporters that support multidrug resistance (MDR), advanced detoxification processes, and the ability to self-renew and differentiate into tumor progenitor cells, thereby supporting cancer invasion, metastasis, and recurrence/relapse. Hence, current research is focusing on targeting CSCs to overcome resistance and improve the efficacy of the treatment and management of breast cancer. Studies revealed that metformin (1, 1-dimethylbiguanide), a widely used anti-hyperglycemic agent, sensitizes tumor response to various chemotherapeutic drugs. Metformin selectively targets CSCs and improves the hypoxic microenvironment, suppresses the tumor metastasis and inflammation, as well as regulates the metabolic programming, induces apoptosis, and reverses epithelial–mesenchymal transition and MDR. Here, we discuss cancer (breast cancer) and chemoresistance, the molecular mechanisms of chemoresistance in breast cancers, and metformin as a chemo-sensitizing/re-sensitizing agent, with a particular focus on breast CSCs as a critical contributing factor to acquired and intrinsic chemoresistance. The review outlines the prospects and directions for a better understanding and re-purposing of metformin as an anti-cancer/chemo-sensitizing drug in the treatment of breast cancer. It intends to provide a rationale for the use of metformin as a combinatory therapy in a clinical setting.

scholarly journals Breast fibroblasts in both cancer and normal tissues induce phenotypic transformation of breast cancer stem cells: a preliminary study

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4805 ◽  
Author(s):  
Bixiao Wang ◽  
Chunfang Xi ◽  
Mingwei Liu ◽  
Haichen Sun ◽  
Shuang Liu ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Stem Cells ◽  
Cancer Stem Cells ◽  
Conditioned Medium ◽  
Cell Invasion ◽  
Epithelial Mesenchymal Transition ◽  
Breast Cancer Stem Cells ◽  
Mesenchymal Transition ◽  
Mammosphere Formation ◽  
Phenotypic Transformation

Background Breast cancer stem cells (BCSCs) are associated with the invasion of breast cancer. In recent years, studies have demonstrated different phenotypes among BCSCs. Furthermore, BCSCs of diverse phenotypes are present at different tumour sites and different histological stages. Fibroblasts are involved in the phenotypic transformation of BCSCs. Cancer-associated fibroblasts (CAFs) participate in the induction of epithelial–mesenchymal transition, thereby promoting the acquisition of stem cell characteristics, but little is known about the role of normal fibroblasts (NFs) in the phenotypic transformation of BCSCs or about the effect of CAFs and NFs on BCSC phenotypes. Methods A total of six pairs of primary CAFs and NFs were isolated from surgical samples of breast cancer patients and subjected to morphological, immunohistochemical, cell invasion and proteomics analyses. After establishing a cell culture system with conditioned medium from CAFs and NFs, we used the mammosphere formation assay to explore the effect of CAFs and NFs on the self-renewal ability of BCSCs. The effect of CAFs and NFs on the phenotypic differentiation of BCSCs was further analysed by flow cytometry and immunofluorescence. Results The isolated CAFs and NFs did not show significant differences in cell morphology or alpha-smooth muscle actin (α-SMA) expression, but cell invasion and proteomics analyses demonstrated heterogeneity among these fibroblasts. Both CAFs and NFs could promote the generation of BCSCs, but CAFs displayed a greater ability than NFs in promoting mammosphere formation. Conditioned medium from CAFs increased the proportion of aldehyde dehydrogenase-1 positive (ALDH1+) BCSCs, but conditioned medium from NFs was more likely to promote the generation of CD44+CD24− BCSCs from MCF-7 cells. Discussion This study validated the heterogeneity among CAFs and NFs and expanded on the conclusion that fibroblasts promote the generation of cancer stem cells. Our results particularly emphasized the effect of NFs on the phenotypic transformation of BCSCs. In addition, this study further highlighted the roles of CAFs and NFs in the induction of different phenotypes in BCSCs.

scholarly journals Notch Signaling in Breast Cancer: A Role in Drug Resistance

Cells ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 2204
Author(s):  
McKenna BeLow ◽  
Clodia Osipo
Keyword(s):  
Breast Cancer ◽  
Stem Cells ◽  
Cancer Stem Cells ◽  
Notch Signaling ◽  
Cell Fate ◽  
Targeted Therapies ◽  
Notch Pathway ◽  
Breast Cancer Stem Cells ◽  
Breast Cancers ◽  
Mesenchymal Transition

Breast cancer is a heterogeneous disease that can be subdivided into unique molecular subtypes based on protein expression of the Estrogen Receptor, Progesterone Receptor, and/or the Human Epidermal Growth Factor Receptor 2. Therapeutic approaches are designed to inhibit these overexpressed receptors either by endocrine therapy, targeted therapies, or combinations with cytotoxic chemotherapy. However, a significant percentage of breast cancers are inherently resistant or acquire resistance to therapies, and mechanisms that promote resistance remain poorly understood. Notch signaling is an evolutionarily conserved signaling pathway that regulates cell fate, including survival and self-renewal of stem cells, proliferation, or differentiation. Deregulation of Notch signaling promotes resistance to targeted or cytotoxic therapies by enriching of a small population of resistant cells, referred to as breast cancer stem cells, within the bulk tumor; enhancing stem-like features during the process of de-differentiation of tumor cells; or promoting epithelial to mesenchymal transition. Preclinical studies have shown that targeting the Notch pathway can prevent or reverse resistance through reduction or elimination of breast cancer stem cells. However, Notch inhibitors have yet to be clinically approved for the treatment of breast cancer, mainly due to dose-limiting gastrointestinal toxicity. In this review, we discuss potential mechanisms of Notch-mediated resistance in breast cancer cells and breast cancer stem cells, and various methods of targeting Notch through γ-secretase inhibitors, Notch signaling biologics, or transcriptional inhibitors. We also discuss future plans for identification of novel Notch-targeted therapies, in order to reduce toxicity and improve outcomes for women with resistant breast cancer.

scholarly journals Chemotherapeutic Stress Influences Epithelial–Mesenchymal Transition and Stemness in Cancer Stem Cells of Triple-Negative Breast Cancer

2020 ◽  
Vol 21 (2) ◽  
pp. 404 ◽  
Author(s):  
Li ◽  
Strietz ◽  
Bleilevens ◽  
Stickeler ◽  
Maurer
Keyword(s):  
Breast Cancer ◽  
Stem Cells ◽  
Cancer Stem Cells ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Epithelial Mesenchymal Transition ◽  
Mrna Level ◽  
Sublethal Dose ◽  
Mesenchymal Transition ◽  
Migratory Capacity

Triple-negative breast cancer (TNBC) is a subtype of breast cancer characterized by the absence of estrogen and progesterone receptors (ER, PR) and lacking an overexpression of human epidermal growth factor receptor 2 (HER2). Apart from this lack of therapeutic targets, TNBC also shows an increased capacity for early metastasis and therapy resistance. Currently, many TNBC patients receive neoadjuvant chemotherapy (NACT) upon detection of the disease. With TNBC likely being driven at least in part by a cancer stem-like cell type, we wanted to evaluate the response of primary cancer stem cells (CSCs) to standard chemotherapeutics. Therefore, we set up a survival model using primary CSCs to mimic tumor cells in patients under chemotherapy. Breast cancer stem cells (BCSCs) were exposed to chemotherapeutics with a sublethal dose for six days. Surviving cells were allowed to recover in culture medium without chemotherapeutics. Surviving and recovered cells were examined in regard to proliferation, migratory capacity, sphere forming capacity, epithelial–mesenchymal transition (EMT) factor expression at the mRNA level, and cancer-related microRNA (miRNA) profile. Our results indicate that chemotherapeutic stress enhanced sphere forming capacity of BCSCs, and changed cell morphology and EMT-related gene expression at the mRNA level, whereas the migratory capacity was unaffected. Six miRNAs were identified as potential regulators in this process.

scholarly journals TGFβ/TNFα-Mediated Epithelial–Mesenchymal Transition Generates Breast Cancer Stem Cells with a Claudin-Low Phenotype

2011 ◽  
Vol 71 (13) ◽  
pp. 4707-4719 ◽  
Author(s):  
Michael K. Asiedu ◽  
James N. Ingle ◽  
Marshall D. Behrens ◽  
Derek C. Radisky ◽  
Keith L. Knutson
Keyword(s):  
Breast Cancer ◽  
Stem Cells ◽  
Cancer Stem Cells ◽  
Epithelial Mesenchymal Transition ◽  
Breast Cancer Stem Cells ◽  
Mesenchymal Transition

Resensitization of palbociclib-resistant MCF-7 cells by inhibiting TGF-β-induced epithelial-mesenchymal transition.

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. e13061-e13061
Author(s):  
Minsun Chang ◽  
Sujeong Park ◽  
Byung Ha An
Keyword(s):  
Breast Cancer ◽  
Cellular Response ◽  
Molecular Mechanisms ◽  
Epithelial Mesenchymal Transition ◽  
Negative Impact ◽  
Acquired Resistance ◽  
Mesenchymal Transition ◽  
Er Positive ◽  
Mcf 7 ◽  
Positive Breast Cancer

e13061 Background: Inhibition of cyclin-dependent kinases 4 and 6 (CDK4/6) is the most recent therapeutic method to treat estrogen receptor (ER)-positive breast cancer. Three CDK4/6 inhibitors have been approved by the FDA. The acquired resistance to CDK4/6 inhibitors are expected to have a negative impact on success of breast cancer therapy. It is critical to understand the molecular mechanisms underlying drug resistances to devise a better regimen or overcome drug resistance. Methods: The derivative MCF-7 (MCF-7:PR) cells which exert acquired resistance to palbociclib (PCB), one of the FDA-approved CDK4/6 inhibitors, are recently established. The EMT characteristics, major mechanisms for the EMT, and inhibition of TGF-β signaling pathways are studied in MCF-7:PR cells. Results: The mesenchymal markers are increased and the epithelial ones are decreased at both mRNA and protein levels in our cell line model. Transwell migration and would healing assays also demonstrated that MCF-7:PR cells exert EMT properties. Hyperactivation of TGF-β/Smad signaling was observed in MCF-7:PR cells. Chemical inhibition of TGF-β signaling lead to diminished cell migration and resistance to PCB. Conclusions: Resistance to PCB in MCF-7 cells resulted in significant changes in cell motility and molecular markers associated with EMT. In particular, TGF-β signaling is closely related to EMT and its inhibition reversed the EMT and cellular response to PCT. Our findings suggest that the modulation of EMT via inhibition of TGF-β signaling can be one of strategies to bypass PCB resistance in ER-positive breast cancer.

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