Chemotherapy Induces Breast Cancer Stemness in Association with Dysregulated Monocytosis

The role of the miR-30a-5p/BCL2L11 pathway in rosmarinic acid-induced apoptosis in MDA-MB-231-derived breast cancer stem-like cells

Background

Rosmarinic acid (RA), a natural phenolic acid, exhibits promising anti-cancer properties. The abnormal expression of microRNA (miRNA) regulates the gene expression and plays a role as an oncogenic or tumor suppressor in TNBC. However, the biological role of RA in miR-30a-5p on BCL2L11 during MDA-MB-231 induced breast cancer stem-like cells (BCSCs) progression and its regulatory mechanism have not been elucidated.

Objective

To investigate whether RA inhibited the silencing effect of miR-30a-5p on the BCL2L11 gene and promoted apoptosis in BCSCs.

Materials and Methods

We assessed the migration, colony formation, proliferation, cell cycle, and apoptosis of BCSCs after RA treatment using the wound-healing assay, colony formation assay, CCK-8 assay, and flow cytometry, respectively. The expression of mRNA and protein levels of BCL-2, Bax, BCL2L11, and P53 genes in BCSCs after RA treatment was obtained by real-time polymerase chain reaction and Western blot. Differential miRNA expression in BCSCs was analyzed by high-throughput sequencing. Targetscan was utilized to predict the targets of miR-30a-5p. The dual luciferase reporter system was used for validation of the miR-30a-5p target.

Results

Wound-healing assay, colony formation assay, CCK-8 assay, and cell cycle assay results showed that RA inhibited migration, colony formation and viability of BCSCs, and cell cycle arrest in the G0-G1 phase. At the highest dose of RA, we noticed cell atrophy, while the arrest rate at 100 μg/mL RA surpassed that at 200 μg/mL RA. Apoptotic cells appeared early (Membrane Associated Protein V FITC+, PI-) or late (Membrane Associated Protein V FITC+, PI+) upon administration of 200 μg/mL RA, Using high-throughput sequencing to compare the differences in miRNA expression, we detected downregulation of miR-30a-5p expression, and the results of dual luciferase reporter gene analysis indicated that BCL2L11 was a direct target of miR-30a-5p.

Conclusion

RA inhibited the silencing effect of miR-30a-5p on the BCL2L11 gene and enhanced apoptosis in BCSCs.

The role of host response to chemotherapy: resistance, metastasis and clinical implications

Chemotherapy remains the primary treatment for most metastatic cancers. However, the response to chemotherapy and targeted agents is often transient, and concurrent development of resistance is the primary impediment to effective cancer therapy. Strategies to overcome resistance to treatment have focused on cancer cell intrinsic factors and the tumor microenvironment (TME). Recent evidence indicates that systemic chemotherapy has a significant impact on the host that either facilitates tumor growth, allowing metastatic spread, or renders treatment ineffective. These host responses include the release of bone marrow-derived cells, activation of stromal cells in the TME, and induction of different molecular effectors. Here, we provide an overview of chemotherapy-induced systemic host responses that support tumor aggressiveness and metastasis, and which contribute to therapy resistance. Studying host responses to chemotherapy provides a solid basis for the development of adjuvant strategies to improve treatment outcomes and delay resistance to chemotherapy. This review discusses the emerging field of host response to cancer therapy, and its preclinical and potential clinical implications, explaining how under certain circumstances, these host effects contribute to metastasis and resistance to chemotherapy.

Determining M2 macrophages content for the anti-tumor effects of metal-organic framework-encapsulated pazopanib nanoparticles in breast cancer

Pazopanib (PAZ), an oral multi-tyrosine kinase inhibitor, demonstrates promising cytostatic activities against various human cancers. However, its clinical utility is limited by substantial side effects and therapeutic resistance. We developed a nanoplatform capable of delivering PAZ for enhanced anti-breast cancer therapy. Nanometer-sized PAZ@Fe-MOF, compared to free PAZ, demonstrated increased anti-tumor therapeutic activities in both syngeneic murine 4T1 and xenograft human MDA-MB-231 breast cancer models. High-throughput single-cell RNA sequencing (scRNAseq) revealed that PAZ@Fe-MOF significantly reduced pro-tumorigenic M2-like macrophage populations at tumor sites and suppressed M2-type signaling pathways, such as ATF6-TGFBR1-SMAD3, as well as chemokines including CCL17, CCL22, and CCL24. PAZ@Fe-MOF reprogramed the inhibitory immune microenvironment and curbed tumorigenicity by blocking the polarization of M2 phenotype macrophages. This platform offers a promising and new strategy for improving the cytotoxicity of PAZ against breast cancers. It provides a method to evaluate the immunological response of tumor cells to PAZ-mediated treatment.

Tumor-initiating cells establish a niche to overcome isolation stress

While the tumor microenvironment is a critical contributor to cancer progression, early steps of tumor initiation and metastasis also rely on the ability of individual tumor cells to survive and thrive at locations where tumor stroma or immune infiltration has yet to be established. In this opinion article, we use the term 'isolation stress' to broadly describe the challenges that individual tumor cells must overcome during the initiation and expansion of the primary tumor beyond permissive boundaries and metastatic spread into distant sites, including a lack of cell-cell contact, adhesion to protumor extracellular matrix proteins, and access to nutrients, oxygen, and soluble factors that support growth. In particular, we highlight the ability of solitary tumor cells to autonomously generate a specialized fibronectin-enriched extracellular matrix to create their own pericellular niche that supports tumor initiation. Cancer cells that can creatively evade the effects of isolation stress not only become more broadly stress tolerant, they also tend to show enhanced stemness, drug resistance, tumor initiation, and metastasis.

Tumor microenvironment of cancer stem cells: Perspectives on cancer stem cell targeting

There are few tumor cell subpopulations with stem cell characteristics in tumor tissue, defined as cancer stem cells (CSCs) or cancer stem-like cells (CSLCs), which can reconstruct neoplasms with malignant biological behaviors such as invasiveness via self-renewal and unlimited generation. The microenvironment that CSCs depend on consists of various cellular components and corresponding medium components. Among these factors existing at a variety of levels and forms, cytokine networks and numerous signal pathways play an important role in signaling transduction. These factors promote or maintain cancer cell stemness, and participate in cancer recurrence, metastasis, and resistance. This review aims to summarize the recent molecular data concerning the multilayered relationship between CSCs and CSC-favorable microenvironments. We also discuss the therapeutic implications of targeting this synergistic interplay, hoping to give an insight into targeting cancer cell stemness for tumor therapy and prognosis.

Impact of Chemotherapeutic Stress Depends on The Nature of Breast Cancer Spheroid and Induce Behavioral Plasticity to Resistant Population

Cellular or tumor dormancy, identified recently as one of the main reasons behind post-therapy recurrence, can be caused by diverse reasons. Chemotherapy has recently been recognized as one of such reasons. However, in-depth studies of chemotherapy-induced dormancy are lacking due to the absence of an in vitro human-relevant model tailor-made for such a scenario. This report utilized multicellular breast cancer spheroid to create a primary platform for establishing a chemotherapy-induced dormancy model. It is observed that extreme chemotherapeutic stress affects invasive and non-invasive spheroids differently. Non-invasive spheroids exhibit more resilience and maintain viability and migrational ability, while invasive spheroids display heightened susceptibility and improved tumorigenic capacity. Heterogenous spheroids exhibit increased tumorigenic capacity while show minimal survival ability. Further probing of chemotherapeutically dormant spheroids is needed to understand the molecular mechanism and identify dormancy-related markers to achieve therapeutic success in the future.

Unveiling the mechanisms and challenges of cancer drug resistance

Cancer treatment faces many hurdles and resistance is one among them. Anti-cancer treatment strategies are evolving due to innate and acquired resistance capacity, governed by genetic, epigenetic, proteomic, metabolic, or microenvironmental cues that ultimately enable selected cancer cells to survive and progress under unfavorable conditions. Although the mechanism of drug resistance is being widely studied to generate new target-based drugs with better potency than existing ones. However, due to the broader flexibility in acquired drug resistance, advanced therapeutic options with better efficacy need to be explored. Combination therapy is an alternative with a better success rate though the risk of amplified side effects is commonplace. Moreover, recent groundbreaking precision immune therapy is one of the ways to overcome drug resistance and has revolutionized anticancer therapy to a greater extent with the only limitation of being individual-specific and needs further attention. This review will focus on the challenges and strategies opted by cancer cells to withstand the current therapies at the molecular level and also highlights the emerging therapeutic options -like immunological, and stem cell-based options that may prove to have better potential to challenge the existing problem of therapy resistance. Video Abstract.

pH-Responsive Polypropylene Sulfide Magnetic Nanocarrier-Mediated Chemo-Hyperthermia Kills Breast Cancer Stem Cells by Long-Term Reversal of Multidrug Resistance and Chemotherapy Resensitization

Cancer stem cells (CSCs) present a formidable challenge in cancer treatment due to their inherent resistance to chemotherapy, primarily driven by the overexpression of ABC transporters and multidrug resistance (MDR). Despite extensive research on pharmacological small-molecule inhibitors, effectively managing MDR and improving chemotherapeutic outcomes remain elusive. On the other hand, magnetic hyperthermia (MHT) holds great promise as a cancer therapeutic, but there is limited research on its potential to reverse MDR in breast CSCs and effectively eliminate CSCs through combined chemo-hyperthermia. To address these gaps, we developed tumor microenvironment-sensitive, drug-loaded poly(propylene sulfide) (PPS)-coated magnetic nanoparticles (PPS-MnFe). These nanoparticles were employed to investigate hyperthermia sensitivity and MDR reversion in breast CSCs, comparing their performance to that of small-molecule inhibitors. Additionally, we explored the efficacy of combined chemo-hyperthermia in killing CSCs. CSC-enriched breast cancer cells were subjected to low-dose MHT at 42 °C for 30 min and then treated with the chemical MDR inhibitor salinomycin (SAL). The effectiveness of each treatment in inhibiting MDR was assessed by measuring the efflux of the MDR substrate, rhodamine 123 (R123) dye. Notably, MHT induced a prolonged reversal of MDR activity compared with SAL treatment alone. After successfully inhibiting MDR, the breast CSCs were exposed to chemotherapy using paclitaxel to trigger synergistic cell death. The combination of MHT and chemotherapy demonstrated remarkable reductions in stemness properties, MDR reversal, and the effective eradication of breast CSCs in this innovative dual-modality approach.

Microdevices for cancer stem cell culture as a predictive chemotherapeutic response platform

Microfluidic platforms for clinical use are a promising translational strategy for cancer research specially for drug screening. Identifying cancer stem cells (CSC) using sphere culture techniques in microfluidic devices (MDs) showed to be better reproducing physiological responses than other in vitro models and allow the optimization of samples and reagents. We evaluated individual sphere proliferation and stemness toward chemotherapeutic treatment (CT) with doxorubicin and cisplatin in bladder cancer cell lines (MB49-I and J82) cultured in MDs used as CSC treatment response platform. Our results confirm the usefulness of this device to evaluate the CT effect in sphere-forming efficiency, size, and growth rate from individual spheres within MDs and robust information comparable to conventional culture plates was obtained. The expression of pluripotency genetic markers (Oct4, Sox2, Nanog, and CD44) could be analyzed by qPCR and immunofluorescence in spheres growing directly in MDs. MDs are a suitable platform for sphere isolation from tumor samples and can provide information about CT response. Microfluidic-based CSC studies could provide information about treatment response of cancer patients from small samples and can be a promising tool for CSC-targeted specific treatment with potential in precision medicine. KEY MESSAGES: We have designed a microfluidic platform for CSC enriched culture by tumor sphere formation. Using MDs, we could quantify and determine sphere response after CT using murine and human cell lines as a proof of concept. MDs can be used as a tumor-derived sphere isolation platform to test the effect of antitumoral compounds in sphere proliferation.

Self-assembly of CXCR4 antagonist peptide-docetaxel conjugates for breast tumor multi-organ metastasis inhibition

As a representative chemotherapeutic drug, docetaxel (DTX) has been used for breast cancer treatment for decades. However, the poor solubility of DTX limits its efficacy, and the DTX based therapy increases the metastasis risk due to the upregulation of C-X-C chemokine receptor type 4 (CXCR4) expression during the treatment. Herein, we conjugated CXCR4 antagonist peptide (CTCE) with DTX (termed CTCE-DTX) as an anti-metastasis agent to treat breast cancer. CTCE-DTX could self-assemble to nanoparticles, targeting CXCR4-upregulated metastatic tumor cells and enhancing the DTX efficacy. Thus, the CTCE-DTX NPs achieved promising efficacy on inhibiting both bone-specific metastasis and lung metastasis of triple-negative breast cancer. Our work provided a rational strategy on designing peptide-drug conjugates with synergistic anti-tumor efficacy.

NPRA promotes fatty acid metabolism and proliferation of gastric cancer cells by binding to PPARα

Among cancers, gastric cancer (GC) ranks third globally in morbidity and mortality, particularly in East Asia. Natriuretic peptide receptor A (NPRA), a receptor for guanylate cyclase, plays important roles in regulating water and sodium balance. Recent studies have suggested that NPRA is involved in tumorigenesis, but its role in GC development remains unclear. Herein, we showed that the expression level of NPRA was positively correlated with gastric tumor size and clinical stage. Patients with high NPRA expression had a lower five-year survival rate than those with low expression, and NPRA was identified as an independent predictor of GC prognosis. NPRA knockdown suppressed GC cell proliferation, migration and invasion. NPRA overexpression enhanced cell malignant behavior. Immunohistochemistry of collected tumor samples showed that tumors with high NPRA expression had higher peroxisome proliferator-activated receptor α (PPARα) levels. In vivo and in vitro studies showed that NPRA promotes fatty acid oxidation and tumor cell metastasis. Co-IP showed that NPRA binds to PPARα and prevents PPARα degradation. PPARα upregulation under NPRA protection activates arnitine palmitoyl transferase 1B (CPT1B) to promote fatty acid oxidation. In this study, new mechanisms by which NPRA promotes the development of GC and new regulatory mechanisms of PPARα were identified.

Cancer stem cell fate determination: mito-nuclear communication

Cancer stem cells (CSCs) are considered to be responsible for tumor recurrence and metastasis. Therefore, clarification of the mechanisms involved in CSC stemness maintenance and cell fate determination would provide a new strategy for cancer therapy. Unregulated cellular energetics has been accepted as one of the hallmarks of cancer cells, but recent studies have revealed that mitochondrial metabolism can also actively determine CSC fate by affecting nuclear stemness gene expression. Herein, from the perspective of mito-nuclear communication, we review recent progress on the influence of mitochondria on CSC potential from four aspects: metabolism, dynamics, mitochondrial homeostasis, and reactive oxygen species (ROS). Video Abstract.

Rational Drug Design of Targeted and Enzyme-Cleavable Vitamin E Analogs as a Neoadjuvant to Chemotherapy: In Vitro and In Vivo Evaluation on Reduction of the Cardiotoxicity Side Effect of Doxorubicin

Traditional drug design focuses on specific biological targets where specific receptors or biomarkers are overexpressed by cancer cells. Cancer cells circumvent the interventions by activating survival pathways and/or downregulating cell death pathways for their survival. A priori activation of apoptosis pathways of tumor (AAAPT) is a novel tumor-sensitizing technology that sensitizes tumor cells that are not responding well to the current treatments by targeting specific survival pathways involved in the desensitization of tumor cells and tries to revive them selectively in cancer cells, sparing normal cells. Several vitamin E derivatives (AMP-001, AMP-002, AMP-003, and AMP-004) were synthesized, characterized, and studied for their anti-tumorigenic properties and their synergistic potential with the standard chemotherapy doxorubicin in various cancer cells including brain cancer stem cells in vitro. Preliminary studies revealed that AAAPT drugs (a) reduced the invasive potential of brain tumor stem cells, (b) synergized with Federal Drug Application-approved doxorubicin, and (c) enhanced the therapeutic index of doxorubicin in the triple-negative breast cancer tumor rat model, preserving the ventricular function compared to cardiotoxic doxorubicin alone at therapeutic dose. The AAAPT approach has the advantage of inhibiting survival pathways and activating cell death pathways selectively in cancer cells by using targeting, linkers cleavable by tumor-specific Cathepsin B, and PEGylation technology to enhance the bioavailability. We propose AAAPT drugs as a neoadjuvant to chemotherapy and not as stand-alone therapy, which is shown to be effective in expanding the therapeutic index of doxorubicin and making it work at lower doses.

Evaluation of the WBC-differential flagging performances and accuracy of the HORIBA Yumizen H2500 cell counter in oncology patients from a single institution

INTRODUCTION

The Yumizen H2500 (YH2500) cell analyser was compared to the Pentra DX Nexus (both from HORIBA Medical) to evaluate the efficiency of the new YH2500 technology for the WBC-differential in samples from oncology patients with WBC-diff abnormalities.

MATERIAL AND METHODS

The 220 samples with slide review criteria on the Nexus were systematically analysed on the YH2500. The WBC-diff was compared to flow cytometry (FCM). The 100 additional samples with Monocyte/Neutrophil separation flags were evaluated. The flagging performance and the accuracy of the WBC-diff were analysed.

RESULTS

The YH2500 generated fewer flags than the Nexus (47.73% vs 66.64%; p < .0001), except for Monocyte/Neutrophil flag (15.5% vs. 2.7%; p < 0.0001). Overall performances were higher on the YH2500 (Sensitivity, 100 vs. 89.6%; Specificity 81.0% vs. 50.9%; PPV, 74.3% vs. 62.9%; NPV, 100% vs. 69.5%; Efficiency, 87.7% vs. 69.5%). YH2500 showed a statistically significant better correlation with FCM for the 6-part differential than the Nexus. On 134 samples with Monocyte/Neutrophil separation flag, it was shown that, in samples with less than 10% monocytes on the YH2500, the results of monocyte and neutrophil counts were comparable to the manual count, and that these samples did not need a slide review if no other main criterion for review was present.

CONCLUSION

The YH2500 demonstrated better performance characteristics than the previous cell counter, the Nexus. Its implementation in our laboratory routine work significantly improved the practice workflow, decreased the number of manual cell counts and increased the pertinence of slide review and reporting of the microscopic count.

Chemotherapy as a regulator of extracellular matrix-cell communication: Implications in therapy resistance

The development of most solid cancers, including pancreatic, breast, lung, liver, and ovarian cancer, involves a desmoplastic reaction: a process of major remodeling of the extracellular matrix (ECM) affecting the ECM composition, mechanics, and microarchitecture. These properties of the ECM influence key cancer cell functions, including treatment resistance. Furthermore, emerging data show that various chemotherapeutic treatments lead to alterations in ECM features and ECM-cell communication. Here, we summarize the current knowledge around the effects of chemotherapy on both the ECM remodeling and ECM-cell signaling and discuss the implications of these alterations on distinct mechanisms of chemoresistance. Additionally, we provide an overview of current therapeutic strategies and ongoing clinical trials utilizing anti-cancer drugs to target the ECM-cell communication and explore the future challenges of these strategies.

Monocyte programming by cancer therapy

Monocytes in peripheral blood circulation are the precursor of essential cells that control tumor progression, that include tumor-associated macrophages (TAMs), dendritic cells (DCs) and myeloid-derive suppressor cells (MDSC). Monocytes-derived cells orchestrate immune reactions in tumor microenvironment that control disease outcome and efficiency of cancer therapy. Four major types of anti-cancer therapy, surgery, radiotherapy, chemotherapy, and most recent immunotherapy, affect tumor-associated macrophage (TAM) polarization and functions. TAMs can also decrease the efficiency of therapy in a tumor-specific way. Monocytes is a major source of TAMs, and are recruited to tumor mass from the blood circulation. However, the mechanisms of monocyte programming in circulation by different therapeutic onsets are only emerging. In our review, we present the state-of-the art about the effects of anti-cancer therapy on monocyte progenitors and their dedifferentiation, on the content of monocyte subpopulations and their transcriptional programs in the circulation, on their recruitment into tumor mass and their potential to give origin for TAMs in tumor-specific microenvironment. We have also summarized very limited available knowledge about genetics that can affect monocyte interaction with cancer therapy, and highlighted the perspectives for the therapeutic targeting of circulating monocytes in cancer patients. We summarized the knowledge about the mediators that affect monocytes fate in all four types of therapies, and we highlighted the perspectives for targeting monocytes to develop combined and minimally invasive anti-cancer therapeutic approaches.

Beyond Immunosuppression: The Multifaceted Functions of Tumor-Promoting Myeloid Cells in Breast Cancers

Breast cancers are commonly associated with an immunosuppressive microenvironment responsible for tumor escape from anti-cancer immunity. Cells of the myeloid lineage account for a major part of this tumor-promoting landscape. These myeloid cells are composed of heterogeneous subsets at different stages of differentiation and have traditionally been described by their cardinal ability to suppress innate and adaptive anticancer immunity. However, evidence has accumulated that, beyond their immunosuppressive properties, breast cancer-induced myeloid cells are also equipped with a broad array of “non-immunological” tumor-promoting functions. They therefore represent major impediments for anticancer therapies, particularly for immune-based interventions. We herein analyze and discuss current literature related to the versatile properties of the different myeloid cell subsets engaged in breast cancer development. We critically assess persisting difficulties and challenges in unequivocally discriminate dedicated subsets, which has so far prevented both the selective targeting of these immunosuppressive cells and their use as potential biomarkers. In this context, we propose the concept of IMCGL, “pro-tumoral immunosuppressive myeloid cells of the granulocytic lineage”, to more accurately reflect the contentious nature and origin of granulocytic cells in the breast tumor microenvironment. Future research prospects related to the role of this myeloid landscape in breast cancer are further considered.

Peripheral Blood Monocyte Abundance Predicts Outcomes in Patients with Breast Cancer

Biomarkers of response are needed in breast cancer to stratify patients to appropriate therapies and avoid unnecessary toxicity. We used peripheral blood gene expression and cell type abundance to identify biomarkers of response and recurrence in neoadjuvant chemotherapy treated breast cancer patients. We identified a signature of interferon and complement response that was higher in the blood of patients with pathologic complete response. This signature was preferentially expressed by monocytes in single cell RNA sequencing. Monocytes are routinely measured clinically, enabling examination of clinically measured monocytes in multiple independent cohorts. We found that peripheral monocytes were higher in patients with good outcomes in four cohorts of breast cancer patients. Blood gene expression and cell type abundance biomarkers may be useful for prognostication in breast cancer.

Significance

Biomarkers are needed in breast cancer to identify patients at risk for recurrence. Blood is an attractive site for biomarker identification due to the relative ease of longitudinal sampling. Our study suggests that blood-based gene expression and cell type abundance biomarkers may have clinical utility in breast cancer.

Single-Cell Proteomic Profiling Identifies Nanoparticle Enhanced Therapy for Triple Negative Breast Cancer Stem Cells

Breast cancer remains a major cause of cancer-related deaths in women worldwide. Chemotherapy-promoted stemness and enhanced stem cell plasticity in breast cancer is a cause for great concern. The discovery of drugs targeting BCSCs was suggested to be an important advancement in the establishment of therapy that improves the efficacy of chemotherapy. In this work, by using single-cell mass cytometry, we observed that stemness in spheroid-forming cells derived from MDA-MB-231 cells was significantly increased after doxorubicin administration and up-regulated integrin αvβ3 expression was also observed. An RGD-included nanoparticle (CS-V) was designed, and it was found that it could promote doxorubicin’s efficacy against MDA-MB-231 spheroid cells. The above observations suggested that the combination of RGD-included nanoparticles (CS-V) with the chemo-drug doxorubicin could be developed as a potential therapy for breast cancer.

Combinatorial Strategies to Target Molecular and Signaling Pathways to Disarm Cancer Stem Cells

Cancer is an urgent public health issue with a very huge number of cases all over the world expected to increase by 2040. Despite improved diagnosis and therapeutic protocols, it remains the main leading cause of death in the world. Cancer stem cells (CSCs) constitute a tumor subpopulation defined by ability to self-renewal and to generate the heterogeneous and differentiated cell lineages that form the tumor bulk. These cells represent a major concern in cancer treatment due to resistance to conventional protocols of radiotherapy, chemotherapy and molecular targeted therapy. In fact, although partial or complete tumor regression can be achieved in patients, these responses are often followed by cancer relapse due to the expansion of CSCs population. The aberrant activation of developmental and oncogenic signaling pathways plays a relevant role in promoting CSCs therapy resistance. Although several targeted approaches relying on monotherapy have been developed to affect these pathways, they have shown limited efficacy. Therefore, an urgent need to design alternative combinatorial strategies to replace conventional regimens exists. This review summarizes the preclinical studies which provide a proof of concept of therapeutic efficacy of combinatorial approaches targeting the CSCs.

Differential Diagnosis and Workup of Monocytosis: A Systematic Approach to a Common Hematologic Finding

Purpose of Review

Monocytosis is a frequently encountered clinical condition that needs appropriate investigation due to a broad range of differential diagnoses. This review is meant to summarize the latest literature in the diagnostic testing and interpretation and offer a stepwise diagnostic approach for a patient presenting with monocytosis.

Recent Findings

Basic studies have highlighted the phenotypic and functional heterogeneity in the monocyte compartment. Studies, both translational and clinical, have provided insights into why monocytosis occurs and how to distinguish the different etiologies. Flow cytometry studies have illustrated that monocyte repartitioning can distinguish chronic myelomonocytic leukemia, a prototypical neoplasm with monocytosis from other reactive or neoplastic causes.

Summary

In summary, we provide an algorithmic approach to the diagnosis of a patient presenting with monocytosis and expect this document to serve as a reference guide for clinicians.

Lipid nanocapsules co-encapsulating paclitaxel and salinomycin for eradicating breast cancer and cancer stem cells

Cancer stem cells (CSCs) comprise a diminutive population of the tumor but pose major obstacles in cancer treatment, often their presence being correlated with poor prognosis, therapeutic resistance and relapse. Nanocarriers of combined drugs regimes demonstrate improved pharmacokinetics and decreased systemic toxicity by targeting the bulk tumor cells along with CSCs, holding the key to future successful chemotherapy. Herein, we developed lipid nanocapsules (LNCs) with co-encapsulated paclitaxel (PTX) and salinomycin (SAL) to eliminate breast cancer cells (MCF-7; non-bCSCs) and cancer stem cells (bCSCs) respectively. LNCs loaded with either PTX or SAL alone or in combination were fabricated by the phase inversion temperature (PIT) method. Physicochemical properties such as nano-size (90 ± 5 nm) and spherical morphology of LNCs were confirmed by dynamic light scattering (DLS) and scanning electron microscopy (SEM) respectively. More than 98 % encapsulation efficiency of drug, alone or in combination, and their controlled drug release was obtained. Drug loaded LNCs were efficiently internalized and exhibited cytotoxicity in non-bCSCs and bCSCs, with dual drug loaded LNCs offering superior cytotoxicity and anti-bCSCs property. Drug loaded nanocapsules induced apoptosis in bCSCs, potentiated with the co-delivery of paclitaxel and salinomycin. Synergistic cytotoxic effect on both cells, non-bCSCs and bCSCs and effective reduction of the tumor mammospheres growth by co-encapsulated paclitaxel and salinomycin suggest LNCs to be promising for treatment of breast cancer.

13R,20-Dihydroxydocosahexaenoic Acid, a Novel Dihydroxy- DHA Derivative, Inhibits Breast Cancer Stemness through Regulation of the Stat3/IL-6 Signaling Pathway by Inducing ROS Production

Breast cancer is a major health problem worldwide. Cancer stem cells (CSCs) are known to mediate breast cancer metastasis and recurrence and are therefore a promising therapeutic target. In this study, we investigated the anti-inflammatory effect of 13R,20-dihydroxydocosahexaenoic acid (13R,20-diHDHA), a novel dihydroxy-DHA derivative, which was synthesized through an enzymatic reaction using cyanobacterial lipoxygenase. We found that 13R,20-diHDHA reduced the macrophage secretion of the inflammatory cytokines, IL-6 and TNF-α, and thus appeared to have anti-inflammatory effects. As the inflammatory tumor microenvironment is largely devoted to supporting the cancer stemness of breast cancer cells, we investigated the effect of 13R,20-diHDHA on breast cancer stemness. Indeed, 13R,20-diHDHA effectively inhibited breast cancer stemness, as evidenced by its ability to dose-dependently inhibit the mammospheres formation, colony formation, migration, and invasion of breast CSCs. 13R,20-diHDHA reduced the populations of CD44^high/CD24^low and aldehyde dehydrogenase (ALDH)-positive cells and the expression levels of the cancer stemness-related self-renewal genes, Nanog, Sox2, Oct4, c-Myc, and CD44. 13R,20-diHDHA increased reactive oxygen species (ROS) production, and the generated ROS reduced the phosphorylation of nuclear signal transducer and activator of transcription 3 (Stat3) and the secretion of IL-6 by mammospheres. These data collectively suggest that 13R,20-diHDHA inhibits breast cancer stemness through ROS production and downstream regulation of Stat3/IL-6 signaling, and thus might be developed as an anti-cancer agent acting against CSCs.

Emerging role of tumor cell plasticity in modifying therapeutic response

Resistance to cancer therapy is a major barrier to cancer management. Conventional views have proposed that acquisition of resistance may result from genetic mutations. However, accumulating evidence implicates a key role of non-mutational resistance mechanisms underlying drug tolerance, the latter of which is the focus that will be discussed here. Such non-mutational processes are largely driven by tumor cell plasticity, which renders tumor cells insusceptible to the drug-targeted pathway, thereby facilitating the tumor cell survival and growth. The concept of tumor cell plasticity highlights the significance of re-activation of developmental programs that are closely correlated with epithelial-mesenchymal transition, acquisition properties of cancer stem cells, and trans-differentiation potential during drug exposure. From observations in various cancers, this concept provides an opportunity for investigating the nature of anticancer drug resistance. Over the years, our understanding of the emerging role of phenotype switching in modifying therapeutic response has considerably increased. This expanded knowledge of tumor cell plasticity contributes to developing novel therapeutic strategies or combination therapy regimens using available anticancer drugs, which are likely to improve patient outcomes in clinical practice.

lncRNA HotairM1 Depletion Promotes Self-Renewal of Cancer Stem Cells through HOXA1-Nanog Regulation Loop

In cancer cells, a gain of stemness may have profound implications for tumor initiation, aggressiveness, and clinical outcome. However, the molecular mechanisms underlying the self-renewal maintenance of cancer stem-like cells (CSCs) remain elusive. Here, based on analysis of transcriptome sequencing, we identified a long noncoding RNA (lncRNA) named HotairM1, which is weakly expressed in human colorectal carcinoma and uveal melanoma, and a much lower expression in corresponding CSCs. Our results showed that HotairM1 depletion could promote CSC self-renewal and tumor propagation. Mechanistically, HotairM1 recruit EZH2 and SUZ12 to the promoter of its target gene HOXA1, leading to histone H3K27 trimethylation and epigenetic silencing of HOXA1. The silence of HOXA1 subsequently induces the H3K27 acetylation at the enhancer site of Nanog gene to upregulate its expression. The enrichment of Nanog could further inhibit HOXA1 expression, forming a reciprocal regulation loop augmenting the stemness maintaining effect. In summary, our results revealed a lncRNA-based regulatory loop that sustains self-renewal of CSCs, which highlights the critical role of HotairM1 in CSC development through the HOXA1-Nanog signaling loop.

Resistance to Anti-angiogenic Therapies: A Mechanism Depending on the Time of Exposure to the Drugs

Angiogenesis, the formation of new blood vessels from preexisting one, represents a critical process for oxygen and nutrient supply to proliferating cells, therefore promoting tumor growth and metastasis. The Vascular Endothelial Growth Factor (VEGF) pathway is one of the key mediators of angiogenesis in cancer. Therefore, several therapies including monoclonal antibodies or tyrosine kinase inhibitors target this axis. Although preclinical studies demonstrated strong antitumor activity, clinical studies were disappointing. Antiangiogenic drugs, used to treat metastatic patients suffering of different types of cancers, prolonged survival to different extents but are not curative. In this review, we focused on different mechanisms involved in resistance to antiangiogenic therapies from early stage resistance involving mainly tumor cells to late stages related to the adaptation of the microenvironment.

Albumin Nanoparticle of Paclitaxel (Abraxane) Decreases while Taxol Increases Breast Cancer Stem Cells in Treatment of Triple Negative Breast Cancer

Triple-negative breast cancer (TNBC) has a high rate of metastasis, which is associated with breast cancer stem-like cells (CSCs). Although Taxol (micelle formulation of paclitaxel) is the first line chemotherapy to treat TNBC, it increases CSCs in residual tumors. Abraxane, albumin nanoparticle of paclitaxel, showed lower plasma concentration compared to Taxol in both human and animal models, but it is not clear why Abraxane showed superior efficacy to Taxol in treatment of metastatic breast cancer in humans. In this study, we intend to investigate if Abraxane eliminates CSCs for its better efficacy. The results showed that Abraxane showed similar cytotoxicity in SUM149 cells in comparison with Taxol. Although Abraxane showed 3- to 5-fold lower blood drug concentration compared to Taxol, it achieved similar tumor drug concentration and 10-fold higher tumor/plasma ratio in SUM149 xenograft NOD/SCID mouse model. In addition, Abraxane and Taxol showed similar efficacy to shrink the tumor size in orthotopic breast cancer NOD/SCID mouse model. However, Abraxane decreased breast CSCs frequency by 3- to 9-fold, while Taxol increased breast CSCs frequency in an orthotopic breast cancer NOD/SCID mouse model. Furthermore, Abraxane increased 3- to 15-fold intracellular uptake in both ALDH+ CSCs and differentiated ALDH- cells in comparison with Taxol, which provides a mechanism for Abraxane's superior efficacy to eliminate CSCs in comparison with Taxol. Our data suggest albumin nanoparticle Abraxane may have a broad implication to enhance drug's efficacy by eliminating breast cancer stem cells for treatment of metastatic diseases.

An evolving paradigm of cancer stem cell hierarchies: therapeutic implications

Over a decade of research has confirmed the critical role of cancer stem-like cells (CSCs) in tumor initiation, chemoresistance, and metastasis. Increasingly, CSC hierarchies have begun to be defined with some recurring themes. This includes evidence that these hierarchies are 'flexible,' with both cell state transitions and dedifferentiation events possible. These findings pose therapeutic hurdles and opportunities. Here, we review cancer stem cell hierarchies and their interactions with the tumor microenvironment. We also discuss the current therapeutic approaches designed to target CSC hierarchies and initial clinical trial results for CSC targeting agents. While cancer stem cell targeted therapies are still in their infancy, we are beginning to see encouraging results that suggest a positive outlook for CSC-targeting approaches.

A Stemness and EMT Based Gene Expression Signature Identifies Phenotypic Plasticity and is A Predictive but Not Prognostic Biomarker for Breast Cancer

Aims: Molecular heterogeneity of breast cancer results in variation in morphology, metastatic potential and response to therapy. We previously showed that breast cancer cell line sub-groups obtained by a clustering approach using highly variable genes overlapped almost completely with sub-groups generated by a drug cytotoxicity-profile based approach. Two distinct cell populations thus identified were CSC(cancer stem cell)-like and non-CSC-like. In this study we asked whether an mRNA based gene signature identifying these two cell types would explain variation in stemness, EMT, drug sensitivity, and prognosis in silico and in vitro. Main methods:In silico analyses were performed using publicly available cell line and patient tumor datasets. In vitro analyses of phenotypic plasticity and drug responsiveness were obtained using human breast cancer cell lines. Key findings: We find a novel gene list (CNCL) that can generate both categorical and continuous variables corresponding to the stemness/EMT (epithelial to mesenchymal transition) state of tumors. We are presenting a novel robust gene signature that unites previous observations related either to EMT or stemness in breast cancer. We show in silico, that this signature perfectly predicts behavior of tumor cells tested in vitro, and can reflect tumor plasticity. We thus demonstrate for the first time, that breast cancer subtypes are sensitive to either Lapatinib or Midostaurin. The same gene list is not capable of predicting prognosis in most cohorts, except for one that includes patients receiving neo-adjuvant taxene therapy. Significance: CNCL is a robust gene list that can identify both stemness and the EMT state of cell lines and tumors. It can be used to trace tumor cells during the course of phenotypic changes they undergo, that result in altered responses to therapeutic agents. The fact that such a list cannot be used to identify prognosis in most patient cohorts suggests that presence of factors other than stemness and EMT affect mortality.

Mechanisms behind prometastatic changes induced by neoadjuvant chemotherapy in the breast cancer microenvironment

Chemotherapy, along with surgery and radiotherapy, is a key treatment option for malignant tumors. Neoadjuvant chemotherapy (NACT) reduces the tumor size and enables total tumor resection. In addition, NACT is believed to be more effective in destroying micrometastases than the same chemotherapy performed after surgery. To date, various NACT regimens have been tested and implemented, which provide a favorable outcome in primary tumors and reduce the risk of progression. However, there is increasing evidence of the NACT ability to increase the risk of cancer progression. This review discusses potential mechanisms by which NACT promotes distant metastasis of breast cancer through changes in the microenvironment of tumor cells. We describe prometastatic NACT-mediated changes in angiogenesis, immuno-inflammatory reactions in the stroma, intravasation, and amount of circulating tumor cells. The role of NACT-related cellular stress in cancer metastasis is also discussed.

Chemotherapy-Induced Extracellular Vesicle miRNAs Promote Breast Cancer Stemness by Targeting ONECUT2

Cancer-secreted, extracellular vesicle (EV)-encapsulated miRNAs enable cancer cells to communicate with each other and with noncancerous cells in tumor pathogenesis and response to therapies. Here, we show that treatment with a sublethal dose of chemotherapeutic agents induces breast cancer cells to secrete EV with the capacity to stimulate a cancer stem-like cell (CSC) phenotype, rendering cancer cells resistance to therapy. Chemotherapy induced breast cancer cells to secrete multiple EV miRNAs, including miR-9-5p, miR-195-5p, and miR-203a-3p, which simultaneously targeted the transcription factor One Cut Homeobox 2 (ONECUT2), leading to induction of CSC traits and expression of stemness-associated genes, including NOTCH1, SOX9, NANOG, OCT4, and SOX2. Inhibition of these miRNAs or restoration of ONECUT2 expression abolished the CSC-stimulating effect of EV from chemotherapy-treated cancer cells. In mice bearing xenograft mammary tumors, docetaxel treatment caused elevations of miR-9-5p, miR-195-5p, and miR-203a-3p in circulating EV and decreased ONECUT2 expression and increased levels of stemness-associated genes. These effects following chemotherapy were diminished in tumors deficient in exosome secretion. In human breast tumors, neoadjuvant chemotherapy decreased ONECUT2 expression in tumor cells. Our results indicate a mechanism by which cancer cells communicate with each other and self-adapt to survive in response to cytotoxic treatment. Targeting these adaptation mechanisms along with chemotherapy, such as by blocking the EV miRNA-ONECUT2 axis, represents a potential strategy to maximize the anticancer effect of chemotherapy and to reduce chemoresistance in cancer management. SIGNIFICANCE: These findings reveal a critical mechanism of resistance to chemotherapy by which breast cancer cells secrete miRNA-containing extracellular vesicles to stimulate cancer stem cell-like features.

Single‑cell intratumoral stemness analysis reveals the involvement of cell cycle and DNA damage repair in two different types of esophageal cancer

Intratumoral heterogeneity, particularly the potential cancer stemness of single cancer cells, has not yet been fully elucidated in human esophageal cancer. Single‑cell transcriptome sequencing of two types of esophageal adenocarcinoma (EAC) and two types of esophageal squamous cell carcinoma (ESCC) tissues was performed, and the intratumoral cancer stemness of the types of esophageal cancer were characterized at the single‑cell level in the present study. By comparing the transcriptomic profiles of single cancer cells with high and low stemness in individual patients, it was revealed that the overexpression of cell cycle‑associated genes in EAC cells was highly correlated with stemness, whereas overexpression of genes involved in the signaling pathways of DNA replication and DNA damage repair was significantly correlated with stemness in ESCC. High expression of these stemness‑associated genes was correlated with poor prognosis of patients. Additionally, poly [ADP‑ribose] polymerase(PARP)4 was identified as a novel cancer stemness‑associated gene in ESCC and its association with survival was validated in a cohort of 121 patients with ESCC. These findings have profound potential implications for the use of cell cycle inhibitors in EAC and PARP inhibitors in ESCC, which may provide novel mechanistic insights into the plasticity of esophageal cancer.

Type I interferon/IRF7 axis instigates chemotherapy-induced immunological dormancy in breast cancer

Neoadjuvant and adjuvant chemotherapies provide survival benefits to breast cancer patients, in particular in estrogen receptor negative (ER^-) cancers, by reducing rates of recurrences. It is assumed that the benefits of (neo)adjuvant chemotherapy are due to the killing of disseminated, residual cancer cells, however, there is no formal evidence for it. Here, we provide experimental evidence that ER^- breast cancer cells that survived high-dose Doxorubicin and Methotrexate based chemotherapies elicit a state of immunological dormancy. Hallmark of this dormant phenotype is the sustained activation of the IRF7/IFN-β/IFNAR axis subsisting beyond chemotherapy treatment. Upregulation of IRF7 in treated cancer cells promoted resistance to chemotherapy, reduced cell growth and induced switching of the response from a myeloid derived suppressor cell-dominated immune response to a CD4⁺/CD8⁺ T cell-dependent anti-tumor response. IRF7 silencing in tumor cells or systemic blocking of IFNAR reversed the state of dormancy, while spontaneous escape from dormancy was associated with loss of IFN-β production. Presence of IFN-β in the circulation of ER^- breast cancer patients treated with neoadjuvant Epirubicin chemotherapy correlated with a significantly longer distant metastasis-free survival. These findings establish chemotherapy-induced immunological dormancy in ER^- breast cancer as a novel concept for (neo)adjuvant chemotherapy activity, and implicate sustained activation of the IRF7/IFN-β/IFNAR pathway in this effect. Further, IFN-β emerges as a potential predictive biomarker and therapeutic molecule to improve outcome of ER^- breast cancer patients treated with (neo)adjuvant chemotherapy.

Notch and Wnt Dysregulation and Its Relevance for Breast Cancer and Tumor Initiation

Breast cancer is the second leading cause of cancer deaths among women in the world. Treatment has been improved and, in combination with early detection, this has resulted in reduced mortality rates. Further improvement in therapy development is however warranted. This will be particularly important for certain sub-classes of breast cancer, such as triple-negative breast cancer, where currently no specific therapies are available. An important therapy development focus emerges from the notion that dysregulation of two major signaling pathways, Notch and Wnt signaling, are major drivers for breast cancer development. In this review, we discuss recent insights into the Notch and Wnt signaling pathways and into how they act synergistically both in normal development and cancer. We also discuss how dysregulation of the two pathways contributes to breast cancer and strategies to develop novel breast cancer therapies starting from a Notch and Wnt dysregulation perspective.

Therapy-induced enrichment of cancer stem-like cells in solid human tumors: Where do we stand?

The development of local recurrence and metastatic disease, most probably attributable to the intrinsic or acquired resistance of tumor cells to standard therapy, still constitute the major clinical problem preventing the cure of cancer patients. Despite progress in the research of new therapeutic targets and compounds, resistant cells displaying stem-like properties seem to play a leading role in therapeutic failures and to be the culprit cells responsible for associated tumor recurrence. A whole new plethora of research studies suggest that drug-tolerant cancer stem cells may be induced by conventional cancer chemotherapeutics such as doxorubicin, cisplatinum and ionizing radiation. This phenotypic plasticity and transition from a differentiated to stem-like cell state associates with the activation of diverse stem cell self-renewal (e.g. Notch, Hedgehog, Wnt), drug efflux (e.g. ABC transporters) and survival-related pathways (e.g. TGF-β, ERK, AKT), which may confer resistance and treatment failures in solid tumors. Therefore, combined therapeutic strategies aiming to simultaneously target drug-sensitive tumor cells and their capacity of phenotypic switching may lead to survival benefits and meaningful disease remissions. This knowledge can be applicable to the clinic and contribute to better therapeutic outcomes and prevent tumor recurrence.