Mammary gland stem cells and their application in breast cancer

ErbB2/HER2-targeted CAR-NK cells eliminate breast cancer cells in an organoid model that recapitulates tumor progression

Chimeric antigen receptor-engineered NK cells hold promise for adoptive cancer immunotherapy. In one such approach, the ErbB2 (HER2)-specific CAR-NK cell line NK-92/5.28.z is under investigation as an off-the-shelf therapy in a phase I trial in glioblastoma patients. To evaluate activity of NK-92/5.28.z cells against ErbB2-positive breast cancer, here we developed an organoid model derived from CKP mice that allows conditional activation of oncogenic driver mutations. Expression of ErbB2 and Cre recombinase in CKP mammary epithelial cells induced malignant transformation, with the resulting EC-CKP cells characterized by neoplastic morphology, loss of p53, and constitutive activation of the MAP kinase pathway. NK-92/5.28.z cells demonstrated potent CAR-mediated cytotoxicity against EC-CKP organoids, with tumor cell lysis dependent on exposure time and organoid size. In vivo passaging of EC-CKP organoids revealed cellular plasticity and induced an EMT phenotype associated with increased resistance to standard therapies. Importantly, NK-92/5.28.z cells retained high and specific cytotoxicity against these breast cancer cells in vitro and in an aggressive organoid-based in vivo mouse model that reflects advanced-stage disease. Our data highlight the therapeutic potential of NK-92/5.28.z cells against ErbB2-positive breast cancer, supporting their further development toward clinical application.

The Critical Role of Inhibitor of Differentiation 4 in Breast Cancer: From Mammary Gland Development to Tumor Progression

Inhibitor of differentiation 4 (ID4) is a highly conserved DNA-binding inhibitory protein of mammals, and its main role is to bind basic helix-loop-helix (b-HLH) so that it loses its DNA-binding activity, which in turn regulates the transcription of key genes, regulating cell differentiation and proliferation as the physiological function. Breast tissue is a highly heterogeneous tissue organ with a strong capacity for remodeling and differentiation, and studies of breast carcinogenesis suggest that the mechanisms regulating the differentiation of breast tissue interact critically with tumorigenesis. The expression level of ID4 and its regulatory mechanism play a crucial role in the study of breast cancer, but its oncogenic or oncostatic role has not yet been unanimously identified, and its regulatory mechanism in breast cancer still needs to be further elucidated. This review summarizes and analyzes the relevant studies of ID4 and the research progress in breast cancer, integrating the development of breast tissue and tumorigenesis with the regulatory role of ID4, to provide some insights into develop new treatment strategies and diagnostic biomarkers.

Distinct clinicopathological features and treatment differences in breast cancer patients of young age

The incidence of breast cancer in young women (aged under 40) is on the rise and is associated with more aggressive tumor characteristics and lower survival rates. Breast cancer is most frequently diagnosed in the sixth decade, and most research presents results based on data from older patients. By using large-scale clinico-pathologic and transcriptomic data from the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) (n = 1932), we aimed to explore age-related differences in treatment, tumor characteristics, and gene expression signatures. Young patients presented more aggressive clinico-pathologic features such as higher histological grade, more frequent lymph node metastasis involvement, and estrogen receptor negativity. Accordingly, age below 40 years was associated with lower mRNA expression of the estrogen- and progesterone receptors, encoded by ESR1 and PGR, a higher proportion of the basal-like subtype, and increased transcription patterns reflecting stemness. Young breast cancer patients showed reduced survival, also within the basal-like subtype. We observed age-related differences in treatment, with more patients receiving chemotherapy among the young. Our results confirm a more challenging disease in young patients with breast cancer despite the more abundant use of chemotherapy. This argues for increased attention to young patients in current management and future research in breast cancer.

The Potential Health Risks and Benefits of Progesterone in the Transgender Woman Population-A Narrative Review

INTRODUCTION

Currently, progesterone is notably absent from conventional feminizing hormone therapies for transgender women. Anecdotal reports indicate the potential for health advantages following the incorporation of progesterone into treatment regimens. The primarily female hormone, progesterone naturally surges in women during the menstrual luteal phase. When administered exogenously, it may expedite bodily changes that are pivotal for gender transition. Progesterone holds promise as a potential remedy for various health conditions prevalent in the transgender woman population.

METHODS

This narrative review synthesizes existing literature and presents a comprehensive account of the administration of exogenous progesterone in transgender women. A literature search was conducted using the PubMed, Embase, ScienceDirect, and ResearchGate databases. The following keywords were used in the search: progesterone, transgender, breast neoplasms, lactation, prostate, testicular neoplasms, and thrombosis. These terms were combined using Boolean operators. The results of the initial search were screened by three independent reviewers based on their relevance to the topic under study.

RESULTS

A total of 104 studies were initially identified as meeting the criteria for inclusion. Following an assessment based on the contents of the title, abstract, and full text, 39 studies were deemed eligible for inclusion. A critical examination of health outcomes was conducted across key sections, including breast development, mental health, lactation, cancer risk (breast and prostate), thrombosis, and nervous and other systems.

DISCUSSION

The use of progesterone in the transgender woman population is a topic that has yet to be sufficiently researched. The limited sample size, short follow-up periods, and lack of randomization restrict the potential for achieving a robust scientific evidence base. In order to gain a fuller understanding of this topic, findings from studies on contraception, hormone replacement therapy, and animal models were considered.

CONCLUSIONS

Progesterone may have a beneficial effect on the bodies of transgender women without significant adverse health effects. Further investigation through well-designed studies is recommended. Randomized controlled trials that include various dosages, broad and long-term effects, and precise demographics are needed. There is an immediate need for more knowledge to create appropriate patent and clinical practice guidelines.

Epigenetic and Immune Mechanisms Linking Breastfeeding to Lower Breast Cancer Rates

This review shows how mammary stem cells (MaSCs) influence breast development, breastfeeding, and breast cancer risk. MaSCs, which can differentiate into various cell types, are vital for breast tissue health, but also disease development in breast tissue. Research shows that breastfeeding affects MaSCs, offering protection against breast cancer through various mechanisms. Hormonal changes such as increased prolactin concentration, oxytocin secretion, lower progesterone levels, and reduced exposure to estrogen during lactation promote apoptosis in potential cancer cells, boost immune surveillance, and modulate inflammation. Key findings reveal that pregnancy at an earlier age and extended breastfeeding reduce MaSC numbers, lowering cancer risk. Additionally, breastfeeding induces various epigenetic changes, such as DNA methylation and histone modification, which provide long-term protection against the development of cancer. Components of breast milk, like alpha-lactalbumin and lactoferrin, contribute by promoting cancer cell apoptosis and inhibiting tumor growth. The dual benefits of breastfeeding are reduced breast cancer risk for mothers and immunological advantages for infants. Multicenter epidemiology research has focused particular attention on longer breastfeeding duration associated with a reduced risk of triple-negative breast cancer. This review offers comprehensive evidence that breastfeeding protects against breast cancer through various biological, hormonal, and molecular mechanisms, showing the importance of promoting breastfeeding as a natural cancer prevention method. This article reviews the role of mammary stem cells in breast development, lactation, and breast cancer.

Intricate relationship between cancer stemness, metastasis, and drug resistance

Cancer stem cells (CSCs) are widely acknowledged as the drivers of tumor initiation, epithelial-mesenchymal transition (EMT) progression, and metastasis. Originating from both hematologic and solid malignancies, CSCs exhibit quiescence, pluripotency, and self-renewal akin to normal stem cells, thus orchestrating tumor heterogeneity and growth. Through a dynamic interplay with the tumor microenvironment (TME) and intricate signaling cascades, CSCs undergo transitions from differentiated cancer cells, culminating in therapy resistance and disease recurrence. This review undertakes an in-depth analysis of the multifaceted mechanisms underlying cancer stemness and CSC-mediated resistance to therapy. Intrinsic factors encompassing the TME, hypoxic conditions, and oxidative stress, alongside extrinsic processes such as drug efflux mechanisms, collectively contribute to therapeutic resistance. An exploration into key signaling pathways, including JAK/STAT, WNT, NOTCH, and HEDGEHOG, sheds light on their pivotal roles in sustaining CSCs phenotypes. Insights gleaned from preclinical and clinical studies hold promise in refining drug discovery efforts and optimizing therapeutic interventions, especially chimeric antigen receptor (CAR)-T cell therapy, cytokine-induced killer (CIK) cell therapy, natural killer (NK) cell-mediated CSC-targeting and others. Ultimately use of cell sorting and single cell sequencing approaches for elucidating the fundamental characteristics and resistance mechanisms inherent in CSCs will enhance our comprehension of CSC and intratumor heterogeneity, which ultimately would inform about tailored and personalized interventions.

Aptamer as a targeted approach towards treatment of breast cancer

Aptamers, a novel type of targeted ligand used in drug delivery, have quickly gained popularity due to their high target specificity and affinity. Different aptamer-mediated drug delivery systems, such as aptamer-drug conjugate (ApDC), aptamer-siRNA, and aptamer-functionalised nanoparticle systems, are currently being developed for the successful treatment of cancer based on the excellent properties of aptamers. These systems can decrease potential toxicity and enhance therapeutic efficacy by targeting the drug moiety. In this review, we provide an overview of recent developments in aptamer-mediated delivery systems for cancer therapy, specifically for breast cancer, and talk about the potential applications and current issues of novel aptamer-based techniques. This study in aptamer technology for breast cancer therapy highlights key aptamers targeting well-established biomarkers such as HER2, oestrogen receptor, and progesterone receptor. Additionally, we explore the potential of aptamers in overcoming various challenges such as drug resistance and improving the delivery of therapeutic agents. This review aims to provide a deeper understanding of the present aptamer-based targeted delivery applications through in-depth analysis to increase efficacy and create new therapeutic approaches that may ultimately lead to better treatment outcomes for cancer patients.

Dependence of human cell survival and proliferation on the CASP3 prodomain

Mechanisms that regulate cell survival and proliferation are important for both the development and homeostasis of normal tissue, and as well as for the emergence and expansion of malignant cell populations. Caspase-3 (CASP3) has long been recognized for its proteolytic role in orchestrating cell death-initiated pathways and related processes; however, whether CASP3 has other functions in mammalian cells that do not depend on its known catalytic activity have remained unknown. To investigate this possibility, we examined the biological and molecular consequences of reducing CASP3 levels in normal and transformed human cells using lentiviral-mediated short hairpin-based knockdown experiments in combination with approaches designed to test the potential rescue capability of different components of the CASP3 protein. The results showed that a ≥50% reduction in CASP3 levels rapidly and consistently arrested cell cycle progression and survival in all cell types tested. Mass spectrometry-based proteomic analyses and more specific flow cytometric measurements strongly implicated CASP3 as playing an essential role in regulating intracellular protein aggregate clearance. Intriguingly, the rescue experiments utilizing different forms of the CASP3 protein showed its prosurvival function and effective removal of protein aggregates did not require its well-known catalytic capability, and pinpointed the N-terminal prodomain of CASP3 as the exclusive component needed in a diversity of human cell types. These findings identify a new mechanism that regulates human cell survival and proliferation and thus expands the complexity of how these processes can be controlled. The graphical abstract illustrates the critical role of CASP3 for sustained proliferation and survival of human cells through the clearance of protein aggregates.

p63: a crucial player in epithelial stemness regulation

Epithelial tissue homeostasis is closely associated with the self-renewal and differentiation behaviors of epithelial stem cells (ESCs). p63, a well-known marker of ESCs, is an indispensable factor for their biological activities during epithelial development. The diversity of p63 isoforms expressed in distinct tissues allows this transcription factor to have a wide array of effects. p63 coordinates the transcription of genes involved in cell survival, stem cell self-renewal, migration, differentiation, and epithelial-to-mesenchymal transition. Through the regulation of these biological processes, p63 contributes to, not only normal epithelial development, but also epithelium-derived cancer pathogenesis. In this review, we provide an overview of the role of p63 in epithelial stemness regulation, including self-renewal, differentiation, proliferation, and senescence. We describe the differential expression of TAp63 and ΔNp63 isoforms and their distinct functional activities in normal epithelial tissues and in epithelium-derived tumors. Furthermore, we summarize the signaling cascades modulating the TAp63 and ΔNp63 isoforms as well as their downstream pathways in stemness regulation.

Mechanotransduction through adhesion molecules: Emerging roles in regulating the stem cell niche

Stem cells have been shown to play an important role in regenerative medicine due to their proliferative and differentiation potential. The challenge, however, lies in regulating and controlling their potential for this purpose. Stem cells are regulated by growth factors as well as an array of biochemical and mechanical signals. While the role of biochemical signals and growth factors in regulating stem cell homeostasis is well explored, the role of mechanical signals has only just started to be investigated. Stem cells interact with their niche or to other stem cells via adhesion molecules that eventually transduce mechanical cues to maintain their homeostatic function. Here, we present a comprehensive review on our current understanding of the influence of the forces perceived by cell adhesion molecules on the regulation of stem cells. Additionally, we provide insights on how this deeper understanding of mechanobiology of stem cells has translated toward therapeutics.

Effects of Apatinib Mesylate Monotherapy on the Incidence of Adverse Reactions and Immune Function in Patients with Breast Cancer after Radical Mastectomy

Objective

To assess the effects of monotherapy with apatinib mesylate on the incidence of adverse events and immune function in breast cancer patients after a radical mastectomy.

Methods

Between December 2018 and August 2020, 90 patients with breast cancer scheduled for a radical mastectomy in People's Liberation Army Navy 971 Hospital were randomly recruited and assigned at a ratio of 1 : 1 to receive either conventional treatment (conventional group) or apatinib mesylate after radical mastectomy (study group). The primary endpoint was disease control rate (DCR), and the secondary endpoints were adverse events and the immune function of the patients.

Results

Monotherapy with apatinib mesylate was associated with a higher DCR (86.67%) versus conventional postoperative treatment (42.23%). All patients in the study group had documented adverse events, including 2 (4.45%) cases of headache, 3 (6.67%) cases of dizziness, 9 (20.00%) cases of hypertension, 6 (13.34%) cases of hand-foot syndrome, 3 (6.67%) cases of thrombocytopenia, 1 (2.23%) case of tinnitus, 7 (15.56%) cases of fatigue, 2 (4.45%) cases of anemia, 2 (4.45%) cases of oral pain, and 10 (22.23%) cases of leukopenia. There were 23 cases of intermittent discontinuation due to adverse events during treatment, 15 cases of dose reduction, and 3 cases of discontinuation due to adverse events. The difference in preoperative and postoperative T-cell subsets and natural killer (NK) cells between the two groups did not come up to the statistical standard (P > 0.05). Monotherapy with apatinib mesylate resulted in significantly lower levels of CD4+, CD4+/CD8+, and NK cells and higher CD8+ levels versus conventional treatment at 1 week and 4 weeks postoperatively (P < 0.05).

Conclusion

Apatinib mesylate monotherapy after radical mastectomy yields a high DCR, a lower incidence of adverse events, and improved immune recovery. Clinical trials are, however, required prior to clinical promotion.

Effect of CDCA5 on Proliferation and Metastasis of Triple Negative Breast Cancer Cells under shRNA Interference Technology

Objective

It was to explore the effect of cell division cycle associated 5 (CDCA5) under shRNA interference on proliferation and metastasis of triple negative breast cancer (TNBC) cells.

Methods

MDA-ME-231 and BT549 cells were selected as the research objects. According to the different interference methods and CDCA5 interference sequences, they were divided into the interference group 1_MDA-ME-231, the interference group 2_MDA-ME-231, the interference group 1_BT549, the interference group 2_BT549 (using shRNA technology), the control group _MDA-ME-231, and the control group _BT549 (breast cancer cells under normal culture conditions). MCF10A cells were routinely cultured as the negative control group to analyze the effect of CDCA5 expression on the proliferation and migration of cancer cells.

Results

The expression of CDCA5 protein in _MDA-ME-231 and _BT549 cells in control group was significantly higher than that in negative control group (P < 0.05). Compared with the control group, the inhibition rates of CDCA5 expression in 1_MDA-ME-231, 2_MDA-ME-231, 1_BT549, and 2_BT549 cells in the interference group were 39.01%, 42.98%, 49.57%, and 60.98%, respectively (P < 0.05). From 12 h, the proliferation level of TNBC cells at different culture time was lower than that of the control group (P < 0.05). Compared with the number of staining cells in the control group, the positive staining cells in 1_MDA-ME-231 (61.42%), 2_MDA-ME-231 (72.06%), 1_BT549 (52.53%), and 2_BT549 (59.65%) in the interference group were significantly decreased (P < 0.05).

Conclusion

The results show that the expression of CDCA5 in TNBC is increased, which plays an important role in the proliferation and migration of cancer cells. shRNA interference technology can knock down the expression of CDCA5 and inhibit its “promoting cancer” effect.

Integration of Single-Cell Transcriptomics With a High Throughput Functional Screening Assay to Resolve Cell Type, Growth Kinetics, and Stemness Heterogeneity Within the Comma-1D Cell Line

Cell lines are one of the most frequently implemented model systems in life sciences research as they provide reproducible high throughput testing. Differentiation of cell cultures varies by line and, in some cases, can result in functional modifications within a population. Although research is increasingly dependent on these in vitro model systems, the heterogeneity within cell lines has not been thoroughly investigated. Here, we have leveraged high throughput single-cell assays to investigate the Comma-1D mouse cell line that is known to differentiate in culture. Using scRNASeq and custom single-cell phenotype assays, we resolve the clonal heterogeneity within the referenced cell line on the genomic and functional level. We performed a cohesive analysis of the transcriptome of 5,195 sequenced cells, of which 85.3% of the total reads successfully mapped to the mm10-3.0.0 reference genome. Across multiple gene expression analysis pipelines, both luminal and myoepithelial lineages were observed. Deep differential gene expression analysis revealed eight subclusters identified as luminal progenitor, luminal differentiated, myoepithelial differentiated, and fibroblast subpopulations-suggesting functional clustering within each lineage. Gene expression of published mammary stem cell (MaSC) markers Epcam, Cd49f, and Sca-1 was detected across the population, with 116 (2.23%) sequenced cells expressing all three markers. To gain insight into functional heterogeneity, cells with patterned MaSC marker expression were isolated and phenotypically investigated through a custom single-cell high throughput assay. The comparison of growth kinetics demonstrates functional heterogeneity within each cell cluster while also illustrating significant limitations in current cell isolation methods. We outlined the upstream use of our novel automated cell identification platform-to be used prior to single-cell culture-for reduced cell stress and improved rare cell identification and capture. Through compounding single-cell pipelines, we better reveal the heterogeneity within Comma-1D to identify subpopulations with specific functional characteristics.

Cancer stem-like cells contribute to paclitaxel resistance in esophageal squamous cell carcinoma

OBJECTIVE

To examine the role of esophageal squamous cell carcinoma (ESCC) stem cells in paclitaxel resistance through the molecular characterization of ESCC stem cells.

METHODS

A resistant cell line (RR-ECl09) of cells were established using intermittent induction and time increments of high-dose paclitaxel in a human esophageal squamous cell carcinoma line (EC109). The multidrug resistance of RR-ECl09 cells to anticancer agents was evaluated by MTT assay. The RR-EC109 and EC109 cells were used for sphere formation assays, clonogenicity assays, stem cell gene expression, and the expression of epithelial-mesenchymal transition markers.

RESULTS

The RR-EC109 cells were established over 7 months. RR-ECl09 cells had 67.258 fold resistance to paclitaxel. The percentage of sphere formation and clone proliferation ability of RR-EC109 cells was higher than that of EC109 cells (P < 0.05). The amount of side population cells in RR-EC109 cells was higher than that of EC109 cells (P < 0.05). RR-EC109 cells produced more mRNA for Bmi1, Nanog, Oct4, Sox2, ABCG2, Nestin, and Ki-67 than EC109 cells (P < 0.05). E-cadherin expression was lower in RR-EC109 cells than in EC109 cells, while N-cadherin, Snail, and Twist expressions were higher in RR-EC109 cells than in EC109 cells (P < 0.05).

CONCLUSIONS

Cancer stem cell (CSC)-like cells exist among paclitaxel-resistant cells in ESCC and may play a role in ESCC drug resistance.

Relationship between ultrasound values and pathology and metastasis in patients with breast cancer

PURPOSE

This study was designed to investigate the relationship between ultrasound values of breast cancer and its pathology and metastasis.

METHODS

A retrospective study was conducted on 80 patients diagnosed with breast cancer by pathologic examination in our hospital. The tumor size, tumor type, tumor grade, and the presence of distant metastasis were recorded. Vascular invasion, molecular subtype, pathobiologic indicators, and other measures were analyzed to explore the correlation between ultrasound measurements and pathology and metastasis in breast cancer patients.

RESULT

The proportion of ultrasound scores did not differ significantly among the groups (P > 0.05). The enrolled subjects were grouped according to tumor types (intraductal carcinoma, invasive ductal carcinoma, invasive lobular carcinoma, and special types), tumor grade (grade 1-3), metastasis, vascular invasion, and pathobiologic indicators (positive or negative ER/PR and HER-2 expression). These factors affected the ultrasound scores of breast cancer patients, resulting in significant differences in the proportions of scores between the groups (P < 0.05).

CONCLUSION

The ultrasound scores of breast cancer are closely related to its pathologic changes, and this has implications for the types of pathological tissues, biologic indicators, and presence of metastasis. Therefore, ultrasound values may be useful as a primary pathologic screening method for breast cancer patients.

miR-4709-3p Inhibits Cell Proliferation by Downregulating TSP50 Expression in Breast Cancer Cells

Breast cancer is a serious threat to the physical and mental health of women all over the world. Our previous results have shown that Serine protease 50 (TSP50), an oncogene overexpressed in breast cancer, can promote proliferation, migration, and invasion of breast cancer cells. Mechanistic studies have revealed that TSP50 promoted tumorigenesis mainly by activating NF-kappa B (NF-κB) and inhibiting activin signaling pathway, indicating that TSP50 played a critical role in the occurrence and development of breast cancer. However, there are few reports on the regulation of TSP50 expression in breast cancer. MicroRNAs (miRNAs) have emerged as an essential posttranscriptional regulator in gene expression and they played a significant role in breast cancer regulation. In the present study, bioinformatics software miRBase and TargetScan were first used to predict and analyze miRNAs that could target TSP50 mRNA 3'UTR and six miRNAs were found. Results from quantitative real-time PCR (qRT-PCR) and western blot suggested that miR-4709-3p could bind to TSP50 mRNA 3'UTR and significantly inhibit the expression of TSP50 protein. Moreover, the effects of miR-4709-3p on the proliferation of breast cancer cells and mammary epithelial cells were detected in vitro. Our data suggested that overexpression of miR-4709-3p mimic greatly inhibited the proliferation of breast cancer cells, whereas overexpression of miR-4709-3p inhibitors significantly promoted the proliferation of breast epithelial cells. Furthermore, the effect of miR-4709-3p on the tumorigenicity of breast cancer cells in vivo was tested, and the results showed that miR-4709-3p significantly reduced the volume and weight of tumor in nude mice. All these results suggested that miR-4709-3p could inhibit the tumorigenesis of breast cancer cells by targeting TSP50. Finally, the underlying molecular mechanisms were investigated and we found that both NF-κB and activin signaling were involved in miR-4709-3p-related tumor inhibitory effect.

Single-cell profiling of long noncoding RNAs and their cell lineage commitment roles via RNA-DNA-DNA triplex formation in mammary epithelium

Long noncoding RNAs (lncRNAs), which are crucial for organ development, exhibit cell-specific expression. Thus, transcriptomic analysis based on total tissue (bulk-seq) cannot accurately reflect the expression pattern of lncRNAs. Here, we used high-throughput single-cell RNA-seq data to investigate the role of lncRNAs using the hierarchical model of mammary epithelium. With our comprehensive annotation of the mammary epithelium, lncRNAs showed much greater cell-lineage specific expression than coding genes. The lineage-specific lncRNAs were functionally correlated with lineage commitment through the coding genes via the cis- and trans-effects of lncRNAs. For the working mechanism, lncRNAs formed a triplex structure with the DNA helix to regulate downstream lineage-specific marker genes. We used lncRNA-Carmn as an example to validate the above findings. Carmn, which is specifically expressed in mammary gland stem cells (MaSCs) and basal cells, positively regulated the Wnt signaling ligand Wnt10a through formation of a lncRNA-DNA-DNA triplex, and thus controlled the stemness of MaSCs. Our study suggests that lncRNAs play essential roles in cell-lineage commitment and provides an approach to decipher lncRNA functions based on single-cell RNA-seq data.

Sphk1 participates in malignant progression of breast cancer by regulating epithelial-mesenchymal transition and stem cell characteristics

BACKGROUND

Sphingosine kinase 1 (Sphk1) is abnormally expressed in various tumors. This study explored the effects of Sphk1 in the polarity of breast cancer (BC) epithelial cells and on stem cell characteristics.

MATERIALS & METHODS

Reverse transcription quantitative PCR (RT-qPCR) was performed to detect Sphk1 levels in human mammary epithelial cells (MCF-10A) and BC cell lines (MCF-7, T47D, SKBR3, MDA-MB-231, and BT-474). After Sphk1-overexpression or Sphk1 silencing, the morphology of cells and stem cell-like properties of BC cells were analyzed. Metastasis of BC cells was assessed by wound healing and Transwell assays. Western blotting was performed to detect levels of epithelial-mesenchymal transition (EMT)-related proteins (E-cadherin, N-cadherin and Vimentin) and stem cell-specific markers (SOX2, OCT4, NANOG and ALDH1).

RESULTS

Sphk1 was increased in BC cell lines than MCF-10A. Sphk1 induced EMT, regulated expression of EMT-related proteins, and accelerated the migration and invasion of BC cells. Silencing Sphk1 inhibited the sphere formation and down-regulated the expression of stem cell-specific markers, whereas Sphk1-overexpression contributed to the maintenance of the characteristics of mammary stem cells.

CONCLUSION

Sphk1 induces migration in BC cells and promotes stem cell characteristics by regulating EMT. The current findings provide a new potential for developing targeted therapy for tumor treatment.

A new view of the mammary epithelial hierarchy and its implications for breast cancer initiation and metastasis

The existence of mammary epithelial stem cell (MaSC) populations capable of mediating mammary gland development and homeostasis has been established for over a decade. A combination of lineage tracing and mammary gland transplantation studies has affirmed that MaSCs and their downstream progenitors are organized in a hierarchal manner; however, these techniques have failed to illuminate the complete spectrum of epithelial intermediate populations or their spatial and temporal relationships. The advent of single cell sequencing technology has allowed for characterization of highly heterogeneous tissues at high resolution. In the last two years, the remarkable advances in single cell RNA sequencing (scRNA-seq) technologies have been leveraged to address the heterogeneity of the mammary epithelium. These studies have afforded fresh insights into the transcriptional differentiation hierarchy and its chronology. Importantly, these data have led to a major conceptual shift in which the rigid boundaries separating stem, progenitor, and differentiated epithelial populations have been deconstructed, resulting in a new more fluid and flexible model of epithelial differentiation. The emerging view of the mammary epithelial hierarchy has important implications for mammary development, carcinogenesis, and metastasis, providing novel insights into the underlying cellular states that may promote malignant phenotypes.

CCR2 Chemokine Receptors Enhance Growth and Cell-Cycle Progression of Breast Cancer Cells through SRC and PKC Activation

Basal-like breast cancers are an aggressive breast cancer subtype, which often lack estrogen receptor, progesterone receptor, and Her2 expression, and are resistant to antihormonal and targeted therapy, resulting in few treatment options. Understanding the underlying mechanisms that regulate progression of basal-like breast cancers would lead to new therapeutic targets and improved treatment strategies. Breast cancer progression is characterized by inflammatory responses, regulated in part by chemokines. The CCL2/CCR2 chemokine pathway is best known for regulating breast cancer progression through macrophage-dependent mechanisms. Here, we demonstrated important biological roles for CCL2/CCR2 signaling in breast cancer cells. Using the MCF10CA1d xenograft model of basal-like breast cancer, primary tumor growth was significantly increased with cotransplantation of patient-derived fibroblasts expressing high levels of CCL2, and was inhibited with CRISP/R gene ablation of stromal CCL2. CRISP/R gene ablation of CCR2 in MCF10CA1d breast cancer cells inhibited breast tumor growth and M2 macrophage recruitment and validated through CCR2 shRNA knockdown in the 4T1 model. Reverse phase protein array analysis revealed that cell-cycle protein expression was associated with CCR2 expression in basal-like breast cancer cells. CCL2 treatment of basal-like breast cancer cell lines increased proliferation and cell-cycle progression associated with SRC and PKC activation. Through pharmacologic approaches, we demonstrated that SRC and PKC negatively regulated expression of the cell-cycle inhibitor protein p27KIP1, and are necessary for CCL2-induced breast cancer cell proliferation. IMPLICATIONS: This report sheds novel light on CCL2/CCR2 chemokine signaling as a mitogenic pathway and cell-cycle regulator in breast cancer cells.

Isoharringtonine inhibits breast cancer stem-like properties and STAT3 signaling

OBJECTIVES

Breast cancer stem cells (BCSCs) contribute to breast cancer progression, relapse, and treatment resistance. Identification of the natural inhibitory components of BCSCs is therefore critical for clinical treatment. Here, we investigated whether isoharringtonine (IHT) had inhibitory effects on BCSCs in breast cancer cell lines.

METHODS

HCC1806, HCC1937, and MCF7 cells were treated with IHT. The proliferation and the migration of cells were detected by MTS assay and wound healing migration assay, respectively. The proportions of BCSCs were determined by flow cytometry and tumor sphere formation assay. Using real-time quantitative polymerase chain reaction (qRT-PCR) and Western blotting, the expression of Nanog and activation of STAT3 were detected, respectively.

RESULTS

Results showed that IHT inhibited the proliferation of HCC1806, HCC1937, and MCF-7 cells, and suppressed the migration of HCC1806 and HCC1937 cells in a dose-dependent manner. IHT treatment decreased the proportion of BCSCs in MCF-7, HCC1806, and HCC1937 cells. In addition, the mRNA level of Nanong was significantly downregulated after IHT treatment. We also found an inhibitory effect of IHT on STAT3 activation.

CONCLUSION

IHT inhibited the proliferation, migration, and BCSC proportion of breast cancer cell lines via inhibition of the STAT3/Nanong pathway.