CD44+/CD24- phenotype predicts a poor prognosis in triple-negative breast cancer

JARID2 activation by NFYA promotes stemness of triple-negative breast cancer cells through the PI3K/AKT pathway

BACKGROUND

This study aimed to investigate the role of Jumonji AT Rich Interacting Domain 2 (JARID2) in regulating triple-negative breast cancer (TNBC) stemness and its mechanism.

RESEARCH DESIGN AND METHODS

Bioinformatics analysis examined JARID2 expression, prognosis, and transcription factors. Quantitative polymerase chain reaction, western blot, and immunohistochemistry detected expression. Dual luciferase reporter gene and chromatin immunoprecipitation assays verified binding. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and colony formation assay detected viability and proliferation. Sphere formation assay detected the sphere formation efficiency. Flow cytometry detected CD44+/CD24- -marked stem cells. A xenograft tumor model verified the effect of JARID2 in vivo.

RESULTS

JARID2 and nuclear transcription factor Y subunit α (NFYA) were upregulated in TNBC tissues and positively correlated. Knockdown of JARID2 or NFYA inhibited cell stemness by inhibiting the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PKB/AKT) signaling pathway. Enforced JARID2 expression rescued the suppressive effect of NFYA knockdown on the PI3K/AKT signaling pathway and cell stemness. Knockdown of JARID2 inhibited tumor growth and cell stemness in mice but was alleviated by concurrent overexpression of NFYA.

CONCLUSIONS

NFYA promotes TNBC cell stemness by upregulating JARID2 expression and regulating the PI3K/AKT signaling pathway, suggesting JARID2 as a potential target for innovating drugs that target TNBC stem cells.

Ferroptosis as a promising targeted therapy for triple negative breast cancer

PURPOSE

Triple negative breast cancer (TNBC) is a challenging subtype characterized by the absence of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression. Standard treatment options are limited, and approximately 45% of patients develop distant metastasis. Ferroptosis, a regulated form of cell death triggered by iron-dependent lipid peroxidation and oxidative stress, has emerged as a potential targeted therapy for TNBC.

METHODS

This study utilizes a multifaceted approach to investigate the induction of ferroptosis as a therapeutic strategy for TNBC. It explores metabolic alterations, redox imbalance, and oncogenic signaling pathways to understand their roles in inducing ferroptosis, characterized by lipid peroxidation, reactive oxygen species (ROS) generation, and altered cellular morphology. Critical pathways such as Xc-/GSH/GPX4, ACSL4/LPCAT3, and nuclear factor erythroid 2-related factor 2 (NRF2) are examined for their regulatory roles in ferroptosis and their potential dysregulation contributing to cancer cell survival and resistance.

RESULTS

Inducing ferroptosis has been shown to inhibit tumor growth, enhance the efficacy of conventional therapies, and overcome drug resistance in TNBC. Lipophilic antioxidants, GPX4 inhibitors, and inhibitors of the Xc- system have been demonstrated to be potential ferroptosis inducers. Additionally, targeting the NRF2 pathway and exploring other ferroptosis regulators, such as ferroptosis suppressor protein 1 (FSP1), and the PERK-eIF2α-ATF4-CHOP pathway, may offer novel therapeutic avenues.

CONCLUSION

Further research is needed to understand the mechanisms, optimize therapeutic strategies, and evaluate the safety and efficacy of ferroptosis-targeted therapies in TNBC treatment. Overall, targeting ferroptosis represents a promising approach to improving treatment outcomes and overcoming the challenges posed by TNBC.

The role of telocytes and miR-21-5p in tumorigenicity and metastasis of breast cancer stem cells

BACKGROUND

This study aims to investigate the roles of telocytes on the metastatic properties of breast cancer stem cells (CSCs), and to re-evaluate the effect of miR-21-5p expression on CSCs following the addition of telocytes.

METHODS AND RESULTS

Telocytes from human bone marrow mononuclear cells were isolated/characterised. This was followed by the isolation/characterisation of CSCs from the MDA-MB-231. miR-21-5p was both overexpressed/inhibited in CSCs. Through co-culture studies, EMT transition and oncogenic properties of CSCs were investigated by analysing changes in ALDH1 and vimentin protein levels as well as changes in the ABCC11, SNAI1, LZTFL1, Oct 3/4, E- and N-cadherin gene expression levels. With the inhibition of miR-21-5p, significant increases in LZTFL and ABCC11 were observed with the addition of telocytes. The expression of the LZTFL gene, which decreased with the overexpression of miR-21-5p, increased in CSCs after co-culture with telocytes. While an increase expression of ABCC11, SNAI1, N-Cadherin, vimentin and ALDH was observed in CSCs after overexpression of miR-21-5p, significant decreases in these expressions were observed after co-culture with telocyte.

CONCLUSIONS

In our study, by gene/protein level analysis we demonstrated that telocytes may have the potential to reduce cancer metastasis through miR-21-5p in breast cancer progression and reduce EMT transition.

The Breast Cancer Single-Cell Atlas: Defining cellular heterogeneity within model cell lines and primary tumors to inform disease subtype, stemness, and treatment options

PURPOSE

Breast Cancer (BC) is the most diagnosed cancer in women; however, through significant research, relative survival rates have significantly improved. Despite progress, there remains a gap in our understanding of BC subtypes and personalized treatments. This manuscript characterized cellular heterogeneity in BC cell lines through scRNAseq to resolve variability in subtyping, disease modeling potential, and therapeutic targeting predictions.

METHODS

We generated a Breast Cancer Single-Cell Cell Line Atlas (BSCLA) to help inform future BC research. We sequenced over 36,195 cells composed of 13 cell lines spanning the spectrum of clinical BC subtypes and leveraged publicly available data comprising 39,214 cells from 26 primary tumors.

RESULTS

Unsupervised clustering identified 49 subpopulations within the cell line dataset. We resolve ambiguity in subtype annotation comparing expression of Estrogen Receptor, Progesterone Receptor, and Human Epidermal Growth Factor Receptor 2 genes. Gene correlations with disease subtype highlighted S100A7 and MUCL1 overexpression in HER2 + cells as possible cell motility and localization drivers. We also present genes driving populational drifts to generate novel gene vectors characterizing each subpopulation. A global Cancer Stem Cell (CSC) scoring vector was used to identify stemness potential for subpopulations and model multi-potency. Finally, we overlay the BSCLA dataset with FDA-approved targets to identify to predict the efficacy of subpopulation-specific therapies.

CONCLUSION

The BSCLA defines the heterogeneity within BC cell lines, enhancing our overall understanding of BC cellular diversity to guide future BC research, including model cell line selection, unintended sample source effects, stemness factors between cell lines, and cell type-specific treatment response.

Role of Cancer Stem-like Cells in the Process of Invasion and Mesenchymal Transformation by a Reconstituted Triple-negative Breast Cancer Cell Population Resistant to p53-induced Apoptosis

We investigated the role of cancer stem cells (CSCs) in a population of triple-negative breast cancer (TNBC) cells that are resistant to apoptosis. A human breast cancer cell population capable of inducing p53 expression with doxycycline (Dox) was created and used as an untreated control (UT). After the addition of Dox to UT for 5 days, the cell population reconstituted with cells showing resistance to apoptosis was named RE. Fluorescence-activated cell sorting (FACS) and immunostaining revealed that after the addition of Dox, the ratio of cells in the S and G2/M phases decreased in UT as apoptosis proceeded, but did not markedly change in apoptosis-resistant RE. CSC-like cells in RE exhibited a cell morphology with a larger ratio of the major/minor axis than UT. FACS showed that RE had a higher proportion of CSC-like cells and contained more CD44+CD24- mesenchymal CSCs than ALDH1A3+ epithelial-like CSCs. In a Matrigel invasion assay, UT was more likely to form a three-dimensional cell population, whereas RE exhibited a planar population, higher migration ability, and the up-regulated expression of epithelial-mesenchymal transition-related genes. These results provide insights into the mechanisms by which TNBC cells acquire treatment resistance at the time of recurrence.

Integrating Genomic Information with Tumor-Immune Microenvironment in Triple-Negative Breast Cancer

BACKGROUND

the development and progression of triple-negative breast cancer (TNBC) is driven by somatic driver mutations and the tumor-immune microenvironment. To date, data on somatic mutations has not been leveraged and integrated with information on the immune microenvironment to elucidate the possible oncogenic interactions and their potential effects on clinical outcomes. Here, we investigated possible oncogenic interactions between somatic mutations and the tumor-immune microenvironment, and their correlation with patient survival in TNBC.

METHODS

We performed analysis combining data on 7,875 somatic mutated genes with information on 1,751 immune-modulated genes, using gene-expression data as the intermediate phenotype, and correlated the resulting information with survival. We conducted functional analysis to identify immune-modulated molecular networks and signaling pathways enriched for somatic mutations likely to drive clinical outcomes.

RESULTS

We discovered differences in somatic mutation profiles between patients who died and those who survived, and a signature of somatic mutated immune-modulated genes transcriptionally associated with TNBC, predictive of survival. In addition, we discovered immune-modulated molecular networks and signaling pathways enriched for somatic mutations.

CONCLUSIONS

The investigation revealed possible oncogenic interactions between somatic mutations and the tumor-immune microenvironment in TNBC, likely to affect clinical outcomes.

Construction and Validation of a Prognostic Model Based on mRNAsi-Related Genes in Breast Cancer

Background

Breast cancer is a big threat to the women across the world with substantial morbidity and mortality. The pressing matter of our study is to establish a prognostic gene model for breast cancer based on mRNAsi for predicting patient's prognostic survival.

Methods

From The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases, we downloaded the expression profiles of genes in breast cancer. On the basis of one-class logistic regression (OCLR) machine learning algorithm, mRNAsi of samples was calculated. Kaplan-Meier (K-M) and Kruskal-Wallis (K-W) tests were utilized for the assessment of the connection between mRNAsi and clinicopathological variables of the samples. As for the analysis on the correlation between mRNAsi and immune infiltration, ESTIMATE combined with Spearman test was employed. The weighted gene coexpression network analysis (WGCNA) network was established by utilizing the differentially expressed genes in breast cancer, and the target module with the most significant correlation with mRNAsi was screened. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were conducted to figure out the biological functions of the target module. As for the construction of the prognostic model, univariate, least absolute shrinkage and selection operator (LASSO) and multivariate Cox regression analyses were performed on genes in the module. The single sample gene set enrichment analysis (ssGSEA) and tumor mutational burden were employed for the analysis on immune infiltration and gene mutations in the high- and low-risk groups. As for the analysis on whether this model had the prognostic value, the nomogram and calibration curves of risk scores and clinical characteristics were drawn.

Results

Nine mRNAsi-related genes (CFB, MAL2, PSME2, MRPL13, HMGB3, DCTPP1, SHCBP1, SLC35A2, and EVA1B) comprised the prognostic model. According to the results of ssGSEA and gene mutation analysis, differences were shown in immune cell infiltration and gene mutation frequency between the high- and low-risk groups.

Conclusion

Nine mRNAsi-related genes screened in our research can be considered as the biomarkers to predict breast cancer patients' prognoses, and this model has a potential relationship with individual somatic gene mutations and immune regulation. This study can offer new insight into the development of diagnostic and clinical treatment strategies for breast cancer.

Challenges for Triple Negative Breast Cancer Treatment: Defeating Heterogeneity and Cancer Stemness

The Triple Negative Breast Cancer (TNBC) subtype is known to have a more aggressive clinical course compared to other breast cancer subtypes. Targeted therapies for this type of breast cancer are limited and patients are mostly treated with conventional chemo- and radio-therapies which are not specific and do not target resistant cells. Therefore, one of the major clinical challenges is to find compounds that target the drug-resistant cell populations which are responsible for reforming secondary tumours. The molecular profiling of the different TNBC subtypes holds a promise for better defining these resistant cells specific to each tumour. To this end, a better understanding of TNBC heterogeneity and cancer stemness is required, and extensive genomic analysis can help to understand the disease complexity and distinguish new molecular drivers that can be targeted in the clinics. The use of persister cancer cell-targeting therapies combined with other therapies may provide a big advance to improve TNBC patients' survival.

Evaluation of CD44+/CD24- and Aldehyde Dehydrogenase Enzyme Markers in Cancer Stem Cells as Prognostic Indicators for Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) has been extensively studied not just for its aggressive behavior but also to understand its complex molecular nature. This type of heterogeneous tumor shows no expression of estrogen receptor (ER) or progesterone receptor (PR) and does not express the HER2 gene, and often these tumors are high grade with distinct histological groups. The basal-like subtype is most commonly related to the TNBC type of neoplasms; it can be further classified according to Lehmann and Burstein expert’s criteria. TNBC is related to breast stem cell markers such as CD44+/CD24- and high levels of enzyme aldehyde dehydrogenase (ALDH), which have been shown to possess stem cell features that are involved in differentiation, vascular invasion, tumorigenesis, and metastatic potential. CD44+/CD24- and high levels of ALDH have significance as markers as well as indicators of poor prognosis in TNBC. The databases used in this review are PMC, PubMed, and Google Scholar.

Predictive Biomarkers of Response to Neoadjuvant Chemotherapy in Breast Cancer: Current and Future Perspectives for Precision Medicine

Pathological complete response (pCR) after neoadjuvant chemotherapy in patients with early breast cancer is correlated with better survival. Meanwhile, an expanding arsenal of post-neoadjuvant treatment strategies have proven beneficial in the absence of pCR, leading to an increased use of neoadjuvant systemic therapy in patients with early breast cancer and the search for predictive biomarkers of response. The better prediction of response to neoadjuvant chemotherapy could enable the escalation or de-escalation of neoadjuvant treatment strategies, with the ultimate goal of improving the clinical management of early breast cancer. Clinico-pathological prognostic factors are currently used to estimate the potential benefit of neoadjuvant systemic treatment but are not accurate enough to allow for personalized response prediction. Other factors have recently been proposed but are not yet implementable in daily clinical practice or remain of limited utility due to the intertumoral heterogeneity of breast cancer. In this review, we describe the current knowledge about predictive factors for response to neoadjuvant chemotherapy in breast cancer patients and highlight the future perspectives that could lead to the better prediction of response, focusing on the current biomarkers used for clinical decision making and the different gene signatures that have recently been proposed for patient stratification and the prediction of response to therapies. We also discuss the intratumoral phenotypic heterogeneity in breast cancers as well as the emerging techniques and relevant pre-clinical models that could integrate this biological factor currently limiting the reliable prediction of response to neoadjuvant systemic therapy.

Triple-negative breast cancer drug resistance, durable efficacy, and cure: How advanced biological insights and emerging drug modalities could transform progress

INTRODUCTION

Triple-negative breast cancer (TNBC) is a heterogeneous disease characterized by the lack of estrogen receptor (ER), progesterone receptor (PR) and epidermal growth factor receptor 2 (HER2) and often associated with poor survival outcomes. The backbone of current treatments for TNBC relies on chemotherapy; however, resistance to cytotoxic agents is a commonly encountered hurdle to overcome.

AREAS COVERED

: Current understanding on the mechanisms involved in TNBC chemoresistance is evaluated and novel potential actionable targets and recently explored modalities for carrying and delivering chemotherapeutics are highlighted.

EXPERT OPINION

: A comprehensive identification of both genomic and functional TNBC signatures is required for a more definite categorization of the patients in order to prevent insensitivity to chemotherapy and therefore realize the full potential of precision-medicine approaches. In this scenario, cell-line-derived xenografts (CDX), patient-derived xenografts (PDX), patient-derived orthotopic xenografts (PDOX) and patient-derived organoids (PDO) are indispensable experimental models for evaluating the efficacy of drug candidates and predicting the therapeutic response. The combination of increasingly sensitive "omics" technologies, computational algorithms and innovative drug modalities may accelerate the successful translation of novel candidate TNBC targets from basic research to clinical settings, thus contributing to reach optimal clinical output, with lower side effects and reduced resistance.

SLFN12 Over-expression Sensitizes Triple Negative Breast Cancer Cells to Chemotherapy Drugs and Radiotherapy

BACKGROUND/AIM

Schlafen 12 (SLFN12) expression correlates with survival in triple negative breast cancer (TNBC). SLFN12 slows TNBC proliferation and induces TNBC differentiation, but whether SLFN12 affects the tumoral response to chemotherapy or radiation is unknown.

MATERIALS AND METHODS

We over-expressed SLFN12 in MDA-MB-231 cells using two different lentiviral vectors. We assessed viable cell numbers via crystal violet assay after treatment with carboplatin, paclitaxel, olaparib, zoledronic acid, camptothecin, or cesium irradiation. CHK1 and CHK2 phosphorylation was assessed by western blot and the effects of inhibiting CHK1/CHK2 by AZD7762 were examined. Key findings were confirmed in Hs578t and BT549 TNBC cells after adenoviral SLFN12 over-expression.

RESULTS

SLFN12 over-expression increased TNBC sensitivity to radiation, carboplatin, paclitaxel, zoledronic acid, and camptothecin, but not to olaparib. SLFN12 over-expression decreased CHK1 and CHK2 phosphorylation after treatment with the DNA damaging agent camptothecin (CPT). The CHK1/CHK2 inhibitor diminished the significant cytotoxicity difference between over-expression and baseline SLFN12 levels in response to carboplatin.

CONCLUSION

SLFN12 increases TNBC sensitivity to DNA-damaging agents at least in part by reducing CHK1/2 phosphorylation. This may contribute to improved survival in patients whose TNBC over-expresses SLFN12. Therefore, SLFN12 levels may be used to customize or predict radiotherapy and chemotherapy effects in TNBC.

Breast cancer stem cells: mechanobiology reveals highly invasive cancer cell subpopulations

Cancer stem-like cells (CSCs) are a typically small subpopulation of highly tumorigenic cells that can self-renew, differentiate, drive tumor progression, and may mediate drug resistance and metastasis. Metastasis driving CSCs are expected to be highly invasive. To determine the relative invasiveness of CSCs, we isolate distinct subpopulations in the metastatic, MDA-MB-231 breast-cancer cell line, identified by the stem-cell markers aldehyde dehydrogenase (ALDH) and CD44. We determine CSC-subpopulation invasiveness levels using our rapid (2 h) mechanobiology-based assay. Specifically, invasive cells forcefully push and indent the surface of physiological-stiffness synthetic gels to cell-scale depths, where the percentage of indenting cells and their attained depths have previously provided clinically relevant predictions of the metastatic risk in different cancer types. We observe that the small (3.2%) CD44+ALDH+ cell-subpopulation indents more and attains significantly deeper depths (65% indenting to 6 ± 0.3 µm) relative to CD44+ALDH-, CD44-ALDH-, CD44-ALDH+ cells, and the whole-sample control (with 18-44% indenting cells reaching average depths of 4.4-5 µm). The CD44+ALDH+ similarly demonstrates twofold higher migratory capacity in Boyden chambers. The higher invasiveness of CD44+ALDH+ cells reveals their likely role in facilitating disease progression, providing prognostic markers for increased risk of recurrence and metastasis.

Novel function of THEMIS2 in the enhancement of cancer stemness and chemoresistance by releasing PTP1B from MET

Triple negative breast cancer (TNBC) possesses poor prognosis mainly due to lack of effective endocrine or targeted therapies, aggressive nature and high rate of chemoresistance. Cancer stem cells (CSCs) are considered to play critical roles in cancer recurrence and chemoresistance. THEMIS2 was identified as the sole common elevated gene in three triple negative breast cancer (TNBC) and two ovarian CSC lines. We discovered an intrinsic signaling scaffold function of THEMIS2, which acts as a novel regulator of cancer stemness in promoting multiple cancer stemness properties including sphere formation, stemness markers expression, chemoresistance and tumorigenicity with low numbers of cancer cells implantation. For the first time, we demonstrated that THEMIS2 specifically enhanced MET activating phosphorylation by suppressing the association of protein-tyrosine phosphatases 1B (PTP1B) with p-MET and MET, which accounted mainly for THEMIS2-mediated effect on cancer stemness and chemoresistance. Increased THEMIS2 expression was associated with poor survival in TNBC patients and in patients from our breast cancer cohort. We found that non-cytotoxic dosages of cryptotanshinone (CPT) could potently inhibit cancer stemness, chemoresistance and tumorigenicity by suppressing expression of THEMIS2. Notably, stable overexpression of THEMIS2 is associated with enhanced sensitivity toward Capmatinib and CPT treatment. Expression levels of THEMIS2 and p-MET protein were positively correlated in the 465 breast cancer specimens. Our study revealed the novel oncogenic role of THEMIS2 and its underlying mechanism via suppressing PTP1B association with MET and thus leading to its activation. Our findings suggest that THEMIS2 could be a biomarker for MET targeted therapy and also provide a potential clinical application using low dosages of CPT for treatment of THEMIS2 positive TNBC.

Molecular Mechanisms, Biomarkers and Emerging Therapies for Chemotherapy Resistant TNBC

Triple-negative breast cancer (TNBC) is associated with high recurrence rates, high incidence of distant metastases, and poor overall survival (OS). Taxane and anthracycline-containing chemotherapy (CT) is currently the main systemic treatment option for TNBC, while platinum-based chemotherapy showed promising results in the neoadjuvant and metastatic settings. An early arising of intrinsic or acquired CT resistance is common and represents the main hurdle for successful TNBC treatment. Numerous mechanisms were uncovered that can lead to the development of chemoresistance. These include cancer stem cells (CSCs) induction after neoadjuvant chemotherapy (NACT), ATP-binding cassette (ABC) transporters, hypoxia and avoidance of apoptosis, single factors such as tyrosine kinase receptors (EGFR, IGFR1), a disintegrin and metalloproteinase 10 (ADAM10), and a few pathological molecular pathways. Some biomarkers capable of predicting resistance to specific chemotherapeutic agents were identified and are expected to be validated in future studies for a more accurate selection of drugs to be employed and for a more tailored approach, both in neoadjuvant and advanced settings. Recently, based on specific biomarkers, some therapies were tailored to TNBC subsets and became available in clinical practice: olaparib and talazoparib for BRCA1/2 germline mutation carriers larotrectinib and entrectinib for neurotrophic tropomyosin receptor kinase (NTRK) gene fusion carriers, and anti-trophoblast cell surface antigen 2 (Trop2) antibody drug conjugate therapy for heavily pretreated metastatic TNBC (mTNBC). Further therapies targeting some pathologic molecular pathways, apoptosis, miRNAS, epidermal growth factor receptor (EGFR), insulin growth factor 1 receptor (IGF-1R), and androgen receptor (AR) are under investigation. Among them, phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) and EGFR inhibitors as well as antiandrogens showed promising results and are under evaluation in Phase II/III clinical trials. Emerging therapies allow to select specific antiblastics that alone or by integrating the conventional therapeutic approach may overcome/hinder chemoresistance.

The Role of Breast Cancer Stem Cells in Chemoresistance and Metastasis in Triple-Negative Breast Cancer

Triple negative breast cancer (TNBC) remains an aggressive disease due to the lack of targeted therapies and low rate of response to chemotherapy that is currently the main treatment modality for TNBC. Breast cancer stem cells (BCSCs) are a small subpopulation of breast tumors and recognized as drivers of tumorigenesis. TNBC tumors are characterized as being enriched for BCSCs. Studies have demonstrated the role of BCSCs as the source of metastatic disease and chemoresistance in TNBC. Multiple targets against BCSCs are now under investigation, with the considerations of either selectively targeting BCSCs or co-targeting BCSCs and non-BCSCs (majority of tumor cells). This review article provides a comprehensive overview of recent advances in the role of BCSCs in TNBC and the identification of cancer stem cell biomarkers, paving the way for the development of new targeted therapies. The review also highlights the resultant discovery of cancer stem cell targets in TNBC and the ongoing clinical trials treating chemoresistant breast cancer. We aim to provide insights into better understanding the mutational landscape of BCSCs and exploring potential molecular signaling pathways targeting BCSCs to overcome chemoresistance and prevent metastasis in TNBC, ultimately to improve the overall survival of patients with this devastating disease.

Cell Differentiation Trajectory-Associated Molecular Classification of Osteosarcoma

This study aims to investigate the differentiation trajectory of osteosarcoma cells and to construct molecular subtypes with their respective characteristics and generate a multi-gene signature for predicting prognosis. Integrated single-cell RNA-sequencing (scRNA-seq) data, bulk RNA-seq data and microarray data from osteosarcoma samples were used for analysis. Via scRNA-seq data, time-related as well as differentiation-related genes were recognized as osteosarcoma tumor stem cell-related genes (OSCGs). In Gene Expression Omnibus (GEO) cohort, osteosarcoma patients were classified into two subtypes based on prognostic OSCGs and it was found that molecular typing successfully predicted overall survival, tumor microenvironment and immune infiltration status. Further, available drugs for influencing osteosarcoma via prognostic OSCGs were revealed. A 3-OSCG-based prognostic risk score signature was generated and by combining other clinic-pathological independent prognostic factor, stage at diagnosis, a nomogram was established to predict individual survival probability. In external independent TARGET cohort, the molecular types, the 3-gene signature as well as nomogram were validated. In conclusion, osteosarcoma cell differentiation occupies a crucial position in many facets, such as tumor prognosis and microenvironment, suggesting promising therapeutic targets for this disease.

Analyzing mRNAsi-Related Genes Identifies Novel Prognostic Markers and Potential Drug Combination for Patients with Basal Breast Cancer

Basal breast cancer subtype is the worst prognosis subtypes among all breast cancer subtypes. Recently, a new tumor stemness index-mRNAsi is found to be able to measure the degree of oncogenic differentiation of tissues. The mRNAsi involved in a variety of cancer processes is derived from the innovative application of one-class logistic regression (OCLR) machine learning algorithm to the whole genome expression of various stem cells and tumor cells. However, it is largely unknown about mRNAsi in basal breast cancer. Here, we find that basal breast cancer carries the highest mRNAsi among all four subtypes of breast cancer, especially 385 mRNAsi-related genes are positively related to the high mRNAsi value in basal breast cancer. This high mRNAsi is also closely related to active cell cycle, DNA replication, and metabolic reprogramming in basal breast cancer. Intriguingly, in the 385 genes, TRIM59, SEPT3, RAD51AP1, and EXO1 can act as independent protective prognostic factors, but CTSF and ABHD4B can serve as independent bad prognostic factors in patients with basal breast cancer. Remarkably, we establish a robust prognostic model containing the 6 mRNAsi-related genes that can effectively predict the survival rate of patients with the basal breast cancer subtype. Finally, the drug sensitivity analysis reveals that some drug combinations may be effectively against basal breast cancer via targeting the mRNAsi-related genes. Taken together, our study not only identifies novel prognostic biomarkers for basal breast cancers but also provides the drug sensitivity data by establishing an mRNAsi-related prognostic model.

Angiopoietin-like protein 4 is a chromatin-bound protein that enhances mammosphere formation in vitro and experimental triple-negative breast cancer brain and liver metastases in vivo

INTRODUCTION:

Metastatic progression in triple-negative breast cancer (TNBC) patients occurs primarily because of nuclear reprogramming that includes chromatin remodeling and epigenetic modifications. The existing and most successful chemotherapies available for metastatic TNBC target nuclear proteins or damage DNA. The objectives here are to investigate an undescribed role for the molecular biology of nuclear angiopoietin-like protein 4 (ANGPTL4) and to characterize the effect of ectopic overexpression of ANGPTL4 in the metastatic biology of TNBC.

MATERIALS AND METHODS:

Lentiviral-mediated transduction was used to overexpress ANGPTL4 in the TNBC cell line MD Anderson–metastatic breast cancer 231. The overexpression of ANGPTL4 was confirmed by western blot and ELISA. Subcellular fractionation, western blot, and immunofluorescence microscopy were used to characterize the intracellular localization of ANGPTL4. Mammosphere culture and the anchorage-independent growth assay analyzed the metastatic potential of the cell line. Xenograft assays assessed the effect of ANGPTL4 overexpression on TNBC metastases in vivo.

RESULTS:

The ANGPTL4 overexpressing cell line formed larger mammospheres and anchorage-independent colonies in vitro and developed larger primary tumors, more liver metastases, and brain metastatic outgrowth in vivo in comparison to a cell line that expressed endogenous levels of ANGPTL4. ANGPTL4, aurora kinase A (AURKA), a mitotic kinase, and Tat-interacting protein p60 kDa (Tip60), a lysine acetyltransferase, associated with chromatin in the ANGPTL4 overexpressing cells but not in cells that expressed endogenous levels of ANGPTL4.

CONCLUSIONS:

The ANGPTL4 overexpressing cell line showed in vitro and in vivo activities that suggest that nuclear ANGPTL4, AURKA, and Tip60 may cooperatively modulate TNBC metastases within chromatin-remodeling complexes or DNA-associated machinery.

A Systematic Review to Clarify the Prognostic Values of CD44 and CD44+CD24- Phenotype in Triple-Negative Breast Cancer Patients: Lessons Learned and The Road Ahead

As a unique population of tumor bulk, cancer stem cells have been implicated in tumor relapse and chemoresistance in triple-negative breast cancer (TNBC). Therefore, understanding the phenotype of cancer stem cells can pave the way for introducing novel molecular targeted therapies for treating TNBC patients. Preclinical studies have identified CD44⁺CD24^-/low as a cancer stem cell phenotype; however, clinical studies have reported seemingly controversial results regarding the prognostic values of CD44 and CD44⁺CD24^-/low phenotype in TNBC patients. To critically review the clinicopathological significance and prognostic values of CD44 and CD44⁺CD24^-/low phenotype in TNBC patients, the Scopus, Embase, PubMed, and Web of Science databases were systematically searched to obtain the relevant records published before 20 October 2020. Based on nine included studies, CD44 and CD44⁺CD24^-/low phenotype are associated with inferior prognosis in TNBC patients. Moreover, these cancer stem cell markers have been associated with advanced tumor stage, tumor size, higher tumor grade, tumor metastasis, and lymphatic involvement in TNBC patients. Our evidence has also indicated that, unlike the treatment-naïve TNBC patients, the tumoral cells of chemoradiotherapy-treated TNBC patients can upregulate the CD44⁺CD24^-/low phenotype and establish an inverse association with androgen receptor (AR), leading to the inferior prognosis of affected patients. In summary, CD44 and CD44⁺CD24^-/low phenotype can be utilized to determine TNBC patients' prognosis in the pathology department as a routine practice, and targeting these phenotypes can substantially improve the prognosis of TNBC patients.

High Levels of Serum IgG for Opisthorchis viverrini and CD44 Expression Predict Worse Prognosis for Cholangiocarcinoma Patients after Curative Resection

Background

Opisthorchis viverrini (OV)-associated cholangiocarcinoma (CCA) has a high immune response with chronic inflammation and oxidative stress. CD44 and Nestin, two cancer stem cell (CSC) markers, play major roles in cancer cell survival. Effects of immune response and expression CSC markers on survival of patients with CCA remain unclear.

Objective

To investigate the effects of level of OV IgG together with CSC marker expression and also the combination of these markers on survival of CCA patients after curative resection.

Methods

All serum specimens from CCA patients who underwent curative surgery from 2005 to 2015 were examined for IgG for OV antigen by ELISA. Tissue specimens were studied for CD44 and Nestin expression. Survival analysis by Cox proportional hazard model was used for estimating hazard ratio (HR) with a 95% confidence interval (CI).

Results

In this study, 122 (69.3%) of 176 were positive for OV IgG, and 35 (19.9%) were considered to have high-positive OV IgG. CD44s positive expression was found in 54 (40%), CD44v6 high expression in 96 (69.6%), CD44v8-10 high expression in 87 (63.5%) and Nestin high expression in 21 (16.1%). Multivariate survival analysis found that high-positive OV IgG and late stage tumor were independent prognostic factors with the adjusted HR of 2.24 (95% CI 1.27–3.93) and 2.78 (95% CI 1.46–5.29), respectively. Subgroup analysis in early and late stage CCA showed that a combined positive OV IgG and CD44s expression with the high expression of CD44v8-10 had the significantly poorest prognosis with HR of 3.75 (95% CI 1.61–8.72) and HR of 1.76 (95% CI 1.02–3.03), respectively.

Conclusion

A high level of OV IgG as well as a high level of CSC markers resulted in an aggressive CCA. OV IgG level together with CSC markers can be used as the prognostic markers for CCA patients’ survival. The study of the CD44 pathway is promising for adjuvant treatment.

Biological characteristics of a sub-population of cancer stem cells from two triple-negative breast tumour cell lines

Triple-negative breast tumours (TNBTs) make up 15-20% of all breast tumours. There is no treatment for them, and the role that cancer stem cells (CSCs) have in carcinogenesis is still unclear, so finding markers and therapeutic targets in CSC exosomes requires these cells to exist as a homogeneous cell population. The objective of this work was to determine differences in ultrastructural morphology, proliferative capacity, and mouse-xenotransplantation characteristics of the MDA-MB-231 and MDA-MB-436 TNBT cell lines with the CD44 high /CD24 low phenotype in order to study their exosomes. The results show that the CD44 high /CD24 low MBA-MB-231 cells had a population doubling time of 41.56 h, compared to 44.79 h in the MDA-MB-436 cell line. After magnetic immunoseparation, 18.75% and 14.56% of the stem cell population of the MDA-MB-231 and MDA-MB-436 cell lines, respectively, were of the CD44 high /CD24 low phenotype, which were expanded to reach purities of 80.4% and 87.6%. The same expanded lineage in both cell lines was shown to possess the pluripotency markers Nanog and Oct4. Under a scanning electron microscope, the CD44 high /CD24 low lineage of the MBA-MD-231 cell line formed groups of more interconnected cells than this lineage of the MBA-MD-436 line. A total of 16% of the mice inoculated with the CD44 high /CD24 low lineage of either cell line presented tumours of the breast, lung, and submandibular ganglia, in whose tissues variable numbers of inoculated cells were found 30 days post-inoculation. By magnetic immunoselection, it was possible to isolate in similar quantities and characterize, expand, and xenotransplant the CD44 high /CD24 low lineage of the MDA-MB-231 and MDA-MB-436 cell lines. The former cell line has greater proliferative capacity, the two lines differ under scanning electron microscopy in how they intercommunicate, and both cell lines induce new tumours in mice and persist at least 30 days post-inoculation in the transplanted animal so their exosomes would also be different.

The Role of Serotonin in Breast Cancer Stem Cells

Breast tumors were the first tumors of epithelial origin shown to follow the cancer stem cell model. The model proposes that cancer stem cells are uniquely endowed with tumorigenic capacity and that their aberrant differentiation yields non-tumorigenic progeny, which constitute the bulk of the tumor cell population. Breast cancer stem cells resist therapies and seed metastases; thus, they account for breast cancer recurrence. Hence, targeting these cells is essential to achieve durable breast cancer remissions. We identified compounds including selective antagonists of multiple serotonergic system pathway components required for serotonin biosynthesis, transport, activity via multiple 5-HT receptors (5-HTRs), and catabolism that reduce the viability of breast cancer stem cells of both mouse and human origin using multiple orthologous assays. The molecular targets of the selective antagonists are expressed in breast tumors and breast cancer cell lines, which also produce serotonin, implying that it plays a required functional role in these cells. The selective antagonists act synergistically with chemotherapy to shrink mouse mammary tumors and human breast tumor xenografts primarily by inducing programmed tumor cell death. We hypothesize those serotonergic proteins of diverse activity function by common signaling pathways to maintain cancer stem cell viability. Here, we summarize our recent findings and the relevant literature regarding the role of serotonin in breast cancer.

Chitosan oligosaccharide decorated liposomes combined with TH302 for photodynamic therapy in triple negative breast cancer

BACKGROUND

Triple negative breast cancer (TNBC) is an aggressive tumor with extremely high mortality that results from its lack of effective therapeutic targets. As an adhesion molecule related to tumorigenesis and tumor metastasis, cluster of differentiation-44 (also known as CD44) is overexpressed in TNBC. Moreover, CD44 can be effectively targeted by a specific hyaluronic acid analog, namely, chitosan oligosaccharide (CO). In this study, a CO-coated liposome was designed, with Photochlor (HPPH) as the 660 nm light mediated photosensitizer and evofosfamide (also known as TH302) as the hypoxia-activated prodrug. The obtained liposomes can help diagnose TNBC by fluorescence imaging and produce antitumor therapy by synergetic photodynamic therapy (PDT) and chemotherapy.

RESULTS

Compared with the nontargeted liposomes, the targeted liposomes exhibited good biocompatibility and targeting capability in vitro; in vivo, the targeted liposomes exhibited much better fluorescence imaging capability. Additionally, liposomes loaded with HPPH and TH302 showed significantly better antitumor effects than the other monotherapy groups both in vitro and in vivo.

CONCLUSION

The impressive synergistic antitumor effects, together with the superior fluorescence imaging capability, good biocompatibility and minor side effects confers the liposomes with potential for future translational research in the diagnosis and CD44-overexpressing cancer therapy, especially TNBC.

89Zr-Labeled Multifunctional Liposomes Conjugate Chitosan for PET-Trackable Triple-Negative Breast Cancer Stem Cell Targeted Therapy

Purpose

Therapy for triple-negative breast cancer (TNBC) is a global problem due to lack of specific targets for treatment selection. Cancer stem cells (CSCs) are responsible for tumor formation and recurrence but also offer a promising target for TNBC-targeted therapy. Here, zirconium-89 (⁸⁹Zr)-labelled multifunctional liposomes (MLPs) surface-decorated with chitosan (CS) were fabricated to specifically target and trace cluster of differentiation 44⁺ (CD44⁺) TNBC CSCs specifically.

Patients and Methods

The biological basis of CS targeting CD44 for cancer therapy was investigated by detecting the expression of CD44 in TNBC CSCs and TNBC tissues. Molecular docking and dynamics simulations were performed to investigate the molecular basis of CS targeting CD44 for cancer therapy. Gambogic acid (GA)-loaded, ⁸⁹Zr@CS-MLPs (⁸⁹Zr-CS-GA-MLPs) were prepared, and their uptake and biodistribution were observed. The anti-tumor efficacy of ⁸⁹Zr@CS-GA-MLPs was investigated in vivo.

Results

CD44 is overexpressed in TNBC CSCs and tissues. Molecular docking and dynamics simulations showed that CS could be stably docked into the active site of CD44 in a reasonable conformation. Furthermore, ⁸⁹Zr@CS-GA-MLPs were able to bind specifically to CD44⁺ TNBC stem-like cells and accumulated in tumors of xenograft-bearing mice with excellent radiochemical stability. ⁸⁹Zr@CS-GA-MLPs loaded with GA showed remarkable anti-tumor efficacy in vivo.

Conclusion

The GA-loaded, ⁸⁹Zr-labelled, CS-decorated MLPs developed in this study represent a novel strategy for TNBC imaging and therapy.

Characteristics of Molecularly Engineered Anticancer Drug Conjugated Organic Nanomicelles for Site-Selective Cancer Cell Rupture and Growth Inhibition of Tumor Spheroids

Site-selective uptake and specific biodistribution of chemotherapeutic drugs are essential prerequisites for targeted cancer therapy. Especially, antibody and peptide conjugated drugs have been attempted as localized therapeutic agents. However, the characteristics of drug conjugated nanosystems are less explored, which are limited with their toxicity, low therapeutic efficacy, complicated synthesis, and high costs. Herein, we report a biocompatible (about 95%) molecularly engineered anticancer drug conjugated nanomicelles (∼200 nm in size) for site-selective CD44 overexpressed cancer cell rupture and tumor growth inhibition. Microscopic analysis demonstrates the distinct visualization of organic-organic interfaces (∼5 nm), which are corroborated with spectroscopic measurements confirmed the conjugation of niclosamide drug with hyaluronic acid (NIC-HA). Uniformly distributed hemocompatible (about 99%) organic nanomicelles exhibit the cellular membrane and cytoplasmic targeting with significant cellular rupture (IC₅₀ of 4 μM for MDA MB 231 cells) indicating their inherent targeting ability for cancer cells and cancer stem cells. An inclusive in vitro and in vivo analysis for targeted antitumor activity (HT1080 tumor xenograft model) of NIC-HA nanoconjugates (∼24.6% loading) exhibited promising cancer cell death and tumor growth inhibition (60%, p < 0.05) due to STAT-3 signaling pathway inhibition and induction of apoptosis in CD44-positive triple negative breast cancer cells.

Novel strategies to target chemoresistant triple-negative breast cancer

Previous studies from our group and others have shown that current drug treatment(s) strategies eliminate bulk of tumor cells (non-CSCs) but it had a minimal effect on cancer stem cells (CSCs) leading to resistance and tumor recurrence. We studied the effects of CFM-4.16 (CARP-1 functional mimetic) and/or cisplatin on four Triple-negative breast cancer (TNBC) MDA-MB-468, MDA-MB-231, CRL-2335 and BR-1126, two cisplatin resistant CisR/MDA-231 and CisR/MDA-468 and cancer stem cells (CSCs) from resistant cell lines. TNBC cells treated with CFM-4.16 plus cisplatin inhibited the expression of FZD8, LRP6 and c-Myc and significantly enhanced cell death in all the cell lines by ~70%-80% compared with the control(s). When Cisplatin resistant CisR/MDA-231 and CisR/MDA-468 were treated with CFM-4.16 plus cisplatin, they also showed a reduction in FZD8 and LRP6 and increased apoptosis compared to control group. Similarly, CFM-4.16 plus cisplatin treatment reduced mammospheres formation abilities of CSCs by 80-90% compared to control group, increased PARP cleavage and apoptosis. Data shows CFM-4.16 plus cisplatin treatment significantly increased apoptosis/cell death in parental, cisplatin resistant and CSCs. Taken together the data suggests that FZD8-mediated Wnt-signaling plays a major role in mediating CSCs growth and resistance to chemotherapy and its inhibition enhances the chemotherapeutic response in TNBC.

Subtype-specific characterization of breast cancer invasion using a microfluidic tumor platform

Understanding progression of breast cancers to invasive ductal carcinoma (IDC) can significantly improve breast cancer treatments. However, it is still difficult to identify genetic signatures and the role of tumor microenvironment to distinguish pathological stages of pre-invasive lesion and IDC. Presence of multiple subtypes of breast cancers makes the assessment more challenging. In this study, an in-vitro microfluidic assay was developed to quantitatively assess the subtype-specific invasion potential of breast cancers. The developed assay is a microfluidic platform in which a ductal structure of epithelial cancer cells is surrounded with a three-dimensional (3D) collagen matrix. In the developed platform, two triple negative cancer subtypes (MDA-MB-231 and SUM-159PT) invaded into the surrounding matrix but the luminal A subtype, MCF-7, did not. Among invasive subtypes, SUM-159PT cells showed significantly higher invasion and degradation of the surrounding matrix than MDA-MB-231. Interestingly, the cells cultured on the platform expressed higher levels of CD24 than in their conventional 2D cultures. This microfluidic platform may be a useful tool to characterize and predict invasive potential of breast cancer subtypes or patient-derived cells.

The circRNA circIFI30 promotes progression of triple-negative breast cancer and correlates with prognosis

Growing evidence suggests that circRNAs exert a critical role in tumorigenesis and cancer progression. To date, the molecular mechanisms underlying circRNAs in triple-negative breast cancer (TNBC) are still poorly known. Here, circRNA expression profile was investigated by RNA sequencing in TNBC tissues and matched para-carcinoma tissues. We found that circIFI30 was significantly up-regulated in TNBC tissues and cells using quantitative real-time PCR and in situ hybridization. High circIFI30 expression was positively correlated with clinical TNM stage, pathological grade and poor prognosis of TNBC patients. Functionally, a series of in vivo and in vitro experiments showed that knockdown of circIFI30 could markedly inhibit TNBC cell proliferation, migration, invasion and cell cycle progression, induce apoptosis as well as suppress tumorigenesis and metastasis. Up-regulation of circIFI30 exerted an opposite effect. Mechanistically, we demonstrated that circIFI30 might act as a competing endogenous RNA (ceRNA) of miR-520b-3p to abolish the suppressive effect on target gene CD44 by fluorescent in situ hybridization (FISH), dual luciferase reporter assay, RNA immunoprecipitation and RNA pull-down assays. Therefore, our work uncovers the mechanism by which circIFI30 could promote TNBC progression through circIFI30/miR-520b-3p/CD44 axis and circIFI30 could be a novel diagnostic/prognostic marker and therapeutic target for TNBC patients.

Tumorigenic and Metastatic Role of CD44-/low/CD24-/low Cells in Luminal Breast Cancer

Cells with high CD44 but low CD24 expression (CD44^high/CD24^-/low) and high aldehyde dehydrogenase activity (ALDH^br) are widely considered to be drivers of metastasis, therapy resistance and tumor recurrence in breast cancer. However, the role of the CD44^high/CD24^-/low and ALDH^br phenotypes in identifying tumorigenic cells in breast cancer remains controversial due to the discrepancy in their distribution and tumorigenic potential in intrinsic breast cancer subtypes. In this study, we analyzed the cells expressing these markers in six different breast cancer cell lines representing major breast cancer subtypes (T47D, MCF-7, BT-474, AU-565, Hs578T and MDA-MB-231). CD44^high/CD24^-/low, ALDH^br and CD44^-/low/CD24^-/low cell populations were isolated by flow cytometry and analyzed for hallmark stem cell characteristics of differentiation, migration, invasiveness and metastasis using in vitro and in vivo techniques. Our results demonstrate that the CD44^-/low/CD24^-/low cell population, which is enriched in luminal cell lines (T47D, MCF-7 and BT-474), possesses metastatic and tumorigenic properties. We also show that, contrary to previous claims, the expression of the ALDH1 isoform ALDH1A1 does not affect the tumorigenic potential of cell lines with high ALDH activity (BT-474 and AU-565). Further transcriptomic and clinical studies are needed to determine the potential of these markers as early diagnostic tools and treatment targets.

Association of CD44 and CD24 phenotype with lymph node metastasis and survival in triple-negative breast cancer

BACKGROUND

CD44⁺CD24^-/low phenotypes are associated with poor outcome of triple-negative breast cancer (TNBC); however, the role of the CD44⁺CD24^-/low phenotype in lymph node metastasis and survival has not been fully understood in TNBC.

METHODS

A total of 51 TNBC patients were included. CD44 and CD24 expression was determined using immunohistochemistry by which CD44 and CD24 were double-immunostained. Overall survival (OS) and disease-free survival (DFS) were estimated using the Kaplan-Meier method.

RESULTS

The proportion of the CD44⁺CD24^-/low phenotype was 33.3% in TNBC specimens without lymph node metastases and 69.0% in those with lymph node metastases. In addition, the CD44⁺CD24^-/low phenotype correlated significantly with tumor size, histologic classification, TNM stage, and lymph node metastasis (P < 0.05). The CD44⁺CD24^-/low phenotype was detected in 69.0% of TNBC patients with lymph node metastases, and 51.7% of TNBC patients without lymph node metastases. In TNBC patients without lymph node metastases, the median DFS and OS were 18.2 and 28 months in cases with a CD44⁺CD24^-/low phenotype and 26.5 and 42.5 months in those without a CD44⁺CD24^-/low phenotype (P < 0.05), and in TNBC patients with lymph node metastases, the median DFS and OS were 17.2 and 25.7 months in cases with a CD44⁺CD24^-/low phenotype and 24.5 and 39.3 months in those without a CD44⁺CD24^-/low phenotype, respectively (P < 0.05).

CONCLUSIONS

CD44 and CD24 are independent prognostic markers for patients with TNBC. The CD44⁺CD24^-/low phenotype correlates with more aggressive clinicopathologic features and is strongly associated with poor prognosis in patients with TNBC.

The Missing Lnc: The Potential of Targeting Triple-Negative Breast Cancer and Cancer Stem Cells by Inhibiting Long Non-Coding RNAs

Treatment decisions for breast cancer are based on staging and hormone receptor expression and include chemotherapies and endocrine therapy. While effective in many cases, some breast cancers are resistant to therapy, metastasize and recur, leading to eventual death. Higher percentages of tumor-initiating cancer stem cells (CSCs) may contribute to the increased aggressiveness, chemoresistance, and worse outcomes among breast cancer. This may be particularly true in triple-negative breast cancers (TNBCs) which have higher percentages of CSCs and are associated with worse outcomes. In recent years, increasing numbers of long non-coding RNAs (lncRNAs) have been identified as playing an important role in breast cancer progression and some of these have been specifically associated within the CSC populations of breast cancers. LncRNAs are non-protein-coding transcripts greater than 200 nucleotides which can have critical functions in gene expression regulation. The preclinical evidence regarding lncRNA antagonists for the treatment of cancer is promising and therefore, presents a potential novel approach for treating breast cancer and targeting therapy-resistant CSCs within these tumors. Herein, we summarize the lncRNAs that have been identified as functionally relevant in breast CSCs. Furthermore, our review of the literature and analysis of patient datasets has revealed that many of these breast CSC-associated lncRNAs are also enriched in TNBC. Together, this suggests that these lncRNAs may be playing a particularly important role in TNBC. Thus, certain breast cancer-promoting/CSC-associated lncRNAs could be targeted in the treatment of TNBCs and the CSCs within these tumors should be susceptible to anti-lncRNA therapy.

miRNAs as radio-response biomarkers for breast cancer stem cells

In breast cancer (BC), the presence of cancer stem cells (CSCs) has been related to relapse, metastasis, and radioresistance. Radiotherapy (RT) is an extended BC treatment, but is not always effective. CSCs have several mechanisms of radioresistance in place, and some miRNAs are involved in the cellular response to ionizing radiation (IR). Here, we studied how IR affects the expression of miRNAs related to stemness in different molecular BC subtypes. Exposition of BC cells to radiation doses of 2, 4, or 6 Gy affected their phenotype, functional characteristics, pluripotency gene expression, and in vivo tumorigenic capacity. This held true for various molecular subtypes of BC cells (classified by ER, PR and HER‐2 status), and for BC cells either plated in monolayer, or being in suspension as mammospheres. However, the effect of IR on the expression of eight stemness‐ and radioresistance‐related miRNAs (miR‐210, miR‐10b, miR‐182, miR‐142, miR‐221, miR‐21, miR‐93, miR‐15b) varied, depending on cell line subpopulation and clinicopathological features of BC patients. Therefore, clinicopathological features and, potentially also, chemotherapy regimen should be both taken into consideration, for determining a potential miRNA signature by liquid biopsy in BC patients treated with RT. Personalized and precision RT dosage regimes could improve the prognosis, treatment, and survival of BC patients.

Schlafen12 Reduces the Aggressiveness of Triple Negative Breast Cancer through Post-Transcriptional Regulation of ZEB1 That Drives Stem Cell Differentiation

BACKGROUND/AIMS

Schlafen12 (SLFN12) promotes human intestinal and prostatic epithelial differentiation. We sought to determine whether SLFN12 reduces triple-negative breast cancer (TNBC) aggressiveness.

METHODS

We validated bioinformatics analyses of publicly available databases by staining human TNBC. After virally overexpressing or siRNA-reducing SLFN12 in TNBC cell lines, we measured proliferation by CCK-8 assay, invasion into basement-membrane-coated pores, mRNA by q-RT-PCR and protein by Western blotting. Flow cytometry assessed proliferation and stem cell marker expression, and sorted CD44+/CD24- cells. Stemness was also assessed by mammosphere formation, and translation by click-it-AHA chemistry.

RESULTS

SLFN12 expression was lower in TNBC tumors and correlated with survival. SLFN12 overexpression reduced TNBC MDA-MB-231, BT549, and Hs578T proliferation. In MDA-MB-231 cells, AdSLFN12 reduced invasion, promoted cell cycle arrest, increased E-cadherin promoter activity, mRNA, and protein, and reduced vimentin expression and protein. SLFN12 knockdown increased vimentin. AdSLFN12 reduced the proportion of MDA-MB-231 CD44⁺CD24^- cells, with parallel differentiation changes. SLFN12 overexpression reduced MDA-MB-231 mammosphere formation. SLFN12 overexpression decreased ZEB1 and Slug protein despite increased ZEB1 and Slug mRNA in all three lines. SLFN12 overexpression accelerated MDA-MB-231 ZEB1 proteasomal degradation and slowed ZEB1 translation. SLFN12 knockdown increased ZEB1 protein. Coexpressing ZEB1 attenuated the SLFN12 effect on E-cadherin mRNA and proliferation in all three lines.

CONCLUSION

SLFN12 may reduce TNBC aggressiveness and improve survival in part by a post-transcriptional decrease in ZEB1 that promotes TNBC cancer stem cell differentiation.

The Clinical Impact of Cancer Stem Cells

Patients with cancer can go though many stages in their disease, including diagnosis, recurrence, metastasis, and treatment failure. Cancer stem cells (CSCs) are a subgroup of cells within tumors that may explain the mechanism by which tumors recur and progress. CSCs can both self-renew and produce progenitor cells of more differentiated cancer cells as well as heterogeneously demonstrate resistance and the abilities to migrate and metastasize. These "stemness" characteristics are often the result of dysregulation of one or more pathways, which can be detected by various biomarkers. Although there has been considerable laboratory research conducted on CSCs, its relevance to the practicing oncologist may seem questionable. We sought to determine the clinical impact of CSCs on patients. A systematic literature search was conducted to identify analyses containing survival information based on the expression of known CSC biomarkers in any cancer. Overall, 234 survival analyses were identified, of which 82% reported that high expression of CSC biomarker(s) resulted in poor overall survival and/or disease-free survival compared with low or no expression of the biomarker. Elevated stemness biomarker levels were also associated with decreased tumor differentiation, altered TNM stage, and increased metastasis. This analysis would suggest that CSCs have a clinical impact on patients and that practicing oncologists need to start considering incorporating CSC-targeting therapies into their patients' treatment regimens. IMPLICATIONS FOR PRACTICE: Cancer stem cells (CSCs) may occur at any stage of cancer and are implicated in the occurrence of resistance, recurrence, and metastasis. A systematic literature analysis has shown that the presence of CSCs, identified via the upregulation of stemness pathway biomarkers, results in reduced survival across all cancers studied. Several CSC-targeting agents are currently approved, and several others are in clinical trials. Future treatment regimens will likely include CSC-targeting agents to enable the elimination of these holdouts to current therapies.

Mechanisms of Chemotherapy Resistance in Triple-Negative Breast Cancer-How We Can Rise to the Challenge

Triple-negative (TNBC) is the most lethal subtype of breast cancer owing to high heterogeneity, aggressive nature, and lack of treatment options. Chemotherapy remains the standard of care for TNBC treatment, but unfortunately, patients frequently develop resistance. Accordingly, in recent years, tremendous effort has been made into elucidating the mechanisms of TNBC chemoresistance with the goal of identifying new molecular targets. It has become evident that the development of TNBC chemoresistance is multifaceted and based on the elaborate interplay of the tumor microenvironment, drug efflux, cancer stem cells, and bulk tumor cells. Alterations of multiple signaling pathways govern these interactions. Moreover, TNBC's high heterogeneity, highlighted in the existence of several molecular signatures, presents a significant obstacle to successful treatment. In the present, in-depth review, we explore the contribution of key mechanisms to TNBC chemoresistance as well as emerging strategies to overcome them. We discuss novel anti-tumor agents that target the components of these mechanisms and pay special attention to their current clinical development while emphasizing the challenges still ahead of successful TNBC management. The evidence presented in this review outlines the role of crucial pathways in TNBC survival following chemotherapy treatment and highlights the importance of using combinatorial drug strategies and incorporating biomarkers in clinical studies.

Recombinant human PRG4 (rhPRG4) suppresses breast cancer cell invasion by inhibiting TGFβ-Hyaluronan-CD44 signalling pathway

Metastasis is the major cause of cancer-related morbidity and mortality. The ability of cancer cells to become invasive and migratory contribute significantly to metastatic growth, which necessitates the identification of novel anti-migratory and anti-invasive therapeutic approaches. Proteoglycan 4 (PRG4), a mucin-like glycoprotein, contributes to joint synovial homeostasis through its friction-reducing and anti-adhesive properties. Adhesion to surrounding extracellular matrix (ECM) components is critical for cancer cells to invade the ECM and eventually become metastatic, raising the question whether PRG4 has an anti-invasive effect on cancer cells. Here, we report that a full-length recombinant human PRG4 (rhPRG4) suppresses the ability of the secreted protein transforming growth factor beta (TGFβ) to induce phenotypic disruption of three-dimensional human breast cancer cell-derived organoids by reducing ligand-induced cell invasion. In mechanistic studies, we find that rhPRG4 suppresses TGFβ-induced invasiveness of cancer cells by inhibiting the downstream hyaluronan (HA)-cell surface cluster of differentiation 44 (CD44) signalling axis. Furthermore, we find that rhPRG4 represses TGFβ-dependent increase in the protein abundance of CD44 and of the enzyme HAS2, which is involved in HA biosynthesis. It is widely accepted that TGFβ has both tumor suppressing and tumor promoting roles in cancer. The novel finding that rhPRG4 opposes HAS2 and CD44 induction by TGFβ has implications for downregulating the tumor promoting roles, while maintaining the tumor suppressive aspects of TGFβ actions. Finally, these findings point to rhPRG4's potential clinical utility as a therapeutic treatment for invasive and metastatic breast cancer.

Prevention of breast cancer by dietary polyphenols-role of cancer stem cells

Breast cancer is a common malignancy with poor prognosis. Cancer cells are heterogeneous and cancer stem cells (CSCs) are primarily responsible for tumor relapse, treatment-resistance and metastasis, so for breast cancer stem cells (BCSCs). Diets are known to be associated with carcinogenesis. Food-derived polyphenols are able to attenuate the formation and virulence of BCSCs, implying that these compounds and their analogs might be promising agents for preventing breast cancer. In the present review, we summarized the origin and surface markers of BCSCs and possible mechanisms responsible for the inhibitory effects of polyphenols on BCSCs. The suppressive effects of common dietary polyphenols against BCSCs, such as curcumin, epigallocatechin gallate (EGCG) and related polyphenolic compounds were further discussed.