Determinants of resistance to chemotherapy and ionizing radiation in breast cancer stem cells

Combination of monensin and erlotinib synergistically inhibited the growth and cancer stem cell properties of triple-negative breast cancer by simultaneously inhibiting EGFR and PI3K signaling pathways

BACKGROUND

Cancer stem cells (CSCs) in triple-negative breast cancer (TNBC) are recognized as a highly challenging subset of cells, renowned for their heightened propensity for relapse and unfavorable prognosis. Monensin, an ionophoric antibiotic, has been reported to exhibit significant therapeutic efficacy against various cancers, especially CSCs. Erlotinib is classified as one of the EGFR-TKIs and has been previously identified as a promising therapeutic target for TNBC. Our research aims to assess the effectiveness of combination of monensin and erlotinib as a potential treatment strategy for TNBC.

METHODS

The combination of monensin and erlotinib was assessed for its potential anticancer activity through various in vitro assays, including cytotoxicity assay, colony formation assay, wound healing assay, transwell assay, mammosphere formation assay, and proportion of CSCs assay. Additionally, an in vivo study using tumor-bearing nude mice was conducted to evaluate the inhibitory effect of the monensin and erlotinib combination on tumor growth.

RESULTS

The results indicated that combination of monensin with erlotinib synergistically inhibited cell proliferation, the migration rate, the invasion ability and decreased the CSCs proportion, and CSC markers SOX2 and CD133 in vivo and in vitro. Furthermore, the primary proteins involved in the signaling pathways of the EGFR/ERK and PI3K/AKT are simultaneously inhibited by the combination treatment of monensin and erlotinib in vivo and in vitro.

CONCLUSIONS

The simultaneous inhibition of the EGFR/ERK and PI3K/AKT/mTOR signaling pathways by the combination of monensin and erlotinib exhibited a synergistic effect on suppressing tumor proliferation and cancer cell stemness in TNBC.

Identification and Validation of a Prognostic Signature Derived from the Cancer Stem Cells for Oral Squamous Cell Carcinoma

The progression and metastasis of oral squamous cell carcinoma (OSCC) are highly influenced by cancer stem cells (CSCs) due to their unique self-renewal and plasticity. In this study, data were obtained from a single-cell RNA-sequencing dataset (GSE172577) in the GEO database, and LASSO-Cox regression analysis was performed on 1344 CSCs-related genes to establish a six-gene prognostic signature (6-GPS) consisting of ADM, POLR1D, PTGR1, RPL35A, PGK1, and P4HA1. High-risk scores were significantly associated with unfavorable survival outcomes, and these features were thoroughly validated in the ICGC. The results of nomograms, calibration plots, and ROC curves confirmed the good prognostic accuracy of 6-GPS for OSCC. Additionally, the knockdown of ADM or POLR1D genes may significantly inhibit the proliferation, migration, and invasion of OSCC cells through the JAK/HIF-1 pathway. Furthermore, cell-cycle arrest occurred in the G1 phase by suppressing Cyclin D1. In summary, 6-GPS may play a crucial role in the occurrence and development of OSCC and has the potential to be developed further as a diagnostic, therapeutic, and prognostic tool for OSCC.

Oxidized ATM governs stemness of breast cancer stem cell through regulating ubiquitylation and acetylation switch

Cancer stem cells (CSCs), as parts of tumor initiation cells, play a crucial role to tumorigenesis, development and recurrence. However, the complicated mechanisms of CSCs to adapt to tumor microenvironment and its stemness maintenance remains unclear. Here, we show that oxidized ATM, a hypoxia-activated cytoplasm ATM, acts a novel function to maintain CSC stemness in triple-negative breast cancer cells (BCSCs) via regulating histone H4 acetylation. Mechanistically, oxidized ATM phosphorylates TRIM21 (a E3 ubiquitin ligase) serine 80 and serine 469. Serine 80 phosphorylation of TRIM21 is essential for the ubiquitination activity of TRIM21. TRIM21 binds with SIRT1 (one of deacetylase), resulting in ubiquitylation-mediated degradation of SIRT1. The reduced SIRT1 leads to increase of histone H4 acetylation, thus facilitating CSC-related gene expression. Clinical data verify that high level of ATM in breast tumors is positively correlated with malignant grade, and is closely related with low SIRT1, high p-TRIM21, and high CD44 expression. In conclusion, our study provides a novel mechanism by which oxidized ATM governing BCSCs stemness and reveals an important link among oxidized ATM, histone acetylation, and BCSCs maintenance.

Dual Targeting of DNA Damage Response Proteins Implicated in Cancer Radioresistance

Ionizing radiation can induce different types of DNA lesions, leading to genomic instability and ultimately cell death. Radiation therapy or radiotherapy, a major modality in cancer treatment, harnesses the genotoxic potential of radiation to target and destroy cancer cells. Nevertheless, cancer cells have the capacity to develop resistance to radiation treatment (radioresistance), which poses a major obstacle in the effective management of cancer. It has been shown that administration of platinum-based drugs to cancer patients can increase tumor radiosensitivity, but despite this, it is associated with severe adverse effects. Several lines of evidence support that activation of the DNA damage response and repair machinery in the irradiated cancer cells enhances radioresistance and cellular survival through the efficient repair of DNA lesions. Therefore, targeting of key DNA damage repair factors would render cancer cells vulnerable to the irradiation effects, increase cancer cell killing, and reduce the risk of side effects on healthy tissue. Herein, we have employed a computer-aided drug design approach for generating ab initio a chemical compound with drug-like properties potentially targeting two proteins implicated in multiple DNA repair pathways. The findings of this study could be taken into consideration in clinical decision-making in terms of co-administering radiation with DNA damage repair factor-based drugs.

Tumor microenvironment-induced tumor cell plasticity: relationship with hypoxic stress and impact on tumor resistance

The role of tumor interaction with stromal components during carcinogenesis is crucial for the design of efficient cancer treatment approaches. It is widely admitted that tumor hypoxic stress is associated with tumor aggressiveness and thus impacts susceptibility and resistance to different types of treatments. Notable biological processes that hypoxia functions in include its regulation of tumor heterogeneity and plasticity. While hypoxia has been reported as a major player in tumor survival and dissemination regulation, the significance of hypoxia inducible factors in cancer stem cell development remains poorly understood. Several reports indicate that the emergence of cancer stem cells in addition to their phenotype and function within a hypoxic tumor microenvironment impacts cancer progression. In this respect, evidence showed that cancer stem cells are key elements of intratumoral heterogeneity and more importantly are responsible for tumor relapse and escape to treatments. This paper briefly reviews our current knowledge of the interaction between tumor hypoxic stress and its role in stemness acquisition and maintenance. Our review extensively covers the influence of hypoxia on the formation and maintenance of cancer stem cells and discusses the potential of targeting hypoxia-induced alterations in the expression and function of the so far known stem cell markers in cancer therapy approaches. We believe that a better and integrated understanding of the effect of hypoxia on stemness during carcinogenesis might lead to new strategies for exploiting hypoxia-associated pathways and their targeting in the clinical setting in order to overcome resistance mechanisms. More importantly, at the present time, efforts are oriented towards the design of innovative therapeutical approaches that specifically target cancer stem cells.

Effects of bromodomain and extra-terminal inhibitor JQ1 and interleukin-6 on breast cancer cells

BACKGROUND

Bromodomain and extra-terminal (BET) proteins are recognized acetylated lysine of histone 4 and act as scaffolds to recruit many other proteins to promoters and enhancers of active genes, especially at the super-enhancers of key genes, driving the transcription process and have been identified as potential therapeutic targets in breast cancer. However, the efficacy of BET inhibitors such as JQ1 in breast cancer therapy is impeded by interleukin-6 (IL-6) through an as-yet-defined mechanism.

METHODS AND RESULTS

We investigated the interplay between IL-6 and JQ1 in MCF-7 and MDA-MB-231 human breast cancer cells. The results demonstrate that the efficacy of JQ1 on the inhibition of cell growth and apoptosis was stronger in MDA-MB-231 cells than in MCF-7 cells. Further, MCF-7 cells, but not MDA-MB-231 cells, exhibited increased expression of CXCR4 following IL-6 treatment. JQ1 significantly reduced CXCR4 surface expression in both cell lines and diminished the effects of IL-6 pre-treatment on MCF-7 cells. While IL-6 suppressed the extension of breast cancer stem cells in MCF-7 cells, JQ1 impeded its inhibitory effect. In MCF-7 cells JQ1 increased the number of senescent cells in a time-dependent manner.

CONCLUSION

Analysis of gene expression indicated that JQ1 and IL-6 synergistically increase SNAIL expression and decrease c-MYC expression in MCF-7 cells. So, the BET proteins are promising, novel therapeutic targets in late-stage breast cancers. BET inhibitors similar to JQ1 show promise as therapeutic candidates for breast cancers, especially when triple-negative breast cancer cells are increased and/or tumor-promoting factors like IL-6 exist in the tumor microenvironment.

Recent advances in novel miRNA mediated approaches for targeting breast cancer

Breast cancer (BC) is considered one of the most frequent cancers among woman worldwide. While conventional therapy has been successful in treating many cases of breast cancer, drug resistance, heterogenicity, tumour features and recurrence, invasion, metastasis and the presence of breast cancer stem cells can hinder the effect of treatments, and can reduce the quality of life of patients. MicroRNAs (miRNAs) are short non-coding RNA molecules that play a crucial role in the development and progression of breast cancer. Several studies have reported that aberrant expression of specific miRNAs is associated with the pathogenesis of breast cancer. However, miRNAs are emerging as potential biomarkers and therapeutic targets for breast cancer. Understanding their role in breast cancer biology could help develop more effective treatments for this disease. The present study discusses the biogenesis and function of miRNAs, as well as miRNA therapy approaches for targeting and treating breast cancer cells.

Soft Tissue Ewing Sarcoma Cell Drug Resistance Revisited: A Systems Biology Approach

Ewing sarcoma is a rare type of cancer that develops in the bones and soft tissues. Drug therapy represents an extensively used modality for the treatment of sarcomas. However, cancer cells tend to develop resistance to antineoplastic agents, thereby posing a major barrier in treatment effectiveness. Thus, there is a need to uncover the molecular mechanisms underlying chemoresistance in sarcomas and, hence, to enhance the anticancer treatment outcome. In this study, a differential gene expression analysis was conducted on high-throughput transcriptomic data of chemoresistant versus chemoresponsive Ewing sarcoma cells. By applying functional enrichment analysis and protein-protein interactions on the differentially expressed genes and their corresponding products, we uncovered genes with a hub role in drug resistance. Granted that non-coding RNA epigenetic regulators play a pivotal role in chemotherapy by targeting genes associated with drug response, we investigated the non-coding RNA molecules that potentially regulate the expression of the detected chemoresistance genes. Of particular importance, some chemoresistance-relevant genes were associated with the autonomic nervous system, suggesting the involvement of the latter in the drug response. The findings of this study could be taken into consideration in the clinical setting for the accurate assessment of drug response in sarcoma patients and the application of tailored therapeutic strategies.

Breast cancer: miRNAs monitoring chemoresistance and systemic therapy

With a high mortality rate that accounts for millions of cancer-related deaths each year, breast cancer is the second most common malignancy in women. Chemotherapy has significant potential in the prevention and spreading of breast cancer; however, drug resistance often hinders therapy in breast cancer patients. The identification and the use of novel molecular biomarkers, which can predict response to chemotherapy, might lead to tailoring breast cancer treatment. In this context, accumulating research has reported microRNAs (miRNAs) as potential biomarkers for early cancer detection, and are conducive to designing a more specific treatment plan by helping analyze drug resistance and sensitivity in breast cancer treatment. In this review, miRNAs are discussed in two alternative ways-as tumor suppressors to be used in miRNA replacement therapy to reduce oncogenesis and as oncomirs to lessen the translation of the target miRNA. Different miRNAs like miR-638, miR-17, miR-20b, miR-342, miR-484, miR-21, miR-24, miR-27, miR-23 and miR-200 are involved in the regulation of chemoresistance through diverse genetic targets. For instance, tumor-suppressing miRNAs like miR-342, miR-16, miR-214, and miR-128 and tumor-promoting miRNAs like miR101 and miR-106-25 cluster regulate the cell cycle, apoptosis, epithelial to mesenchymal transition and other pathways to impart breast cancer drug resistance. Hence, in this review, we have discussed the significance of miRNA biomarkers that could assist in providing novel therapeutic targets to overcome potential chemotherapy resistance to systemic therapy and further facilitate the design of tailored therapy for enhanced efficacy against breast cancer.

Enhanced E6AP-mediated ubiquitination of ENO1 via LINC00663 contributes to radiosensitivity of breast cancer by regulating mitochondrial homeostasis

Radiotherapy has shown measurable efficacy in breast cancer (BC). Elucidating the mechanisms and developing effective strategies against resistance, which is a major challenge, is crucial. Mitochondria, which regulate homeostasis of the redox environment, have emerged as a radiotherapeutic target. However, the mechanism via which mitochondria are controlled under radiation remains elusive. Here, we identified alpha-enolase (ENO1), as a prognostic marker for the efficacy of BC radiotherapy. ENO1 enhances radio-therapeutic resistance in BC via reducing the production of reactive oxygen species (ROS) and apoptosis in vitro and in vivo through modulation of mitochondrial homeostasis. Moreover, LINC00663 was identified as an upstream regulator of ENO1, which regulates radiotherapeutic sensitivity by downregulating ENO1 expression in BC cells. LINC00663 regulates ENO1 protein stability by enhancing the E6AP-mediated ubiquitin-proteasome pathway. In BC patients, LINC00663 expression is negatively correlated with ENO1 expression. Among patients treated with IR, those who did not respond to radiotherapy expressed lower levels of LINC00663 than those sensitive to radiotherapy. Our work established LINC00663/ENO1 critical to regulate IR-resistance in BC. Inhibition of ENO1 with a specific inhibitor or supplement of LINC00663 could be potential sensitizing therapeutic strategies for BC.

Preclinical and Clinical Trials of New Treatment Strategies Targeting Cancer Stem Cells in Subtypes of Breast Cancer

Breast cancer (BC) can be classified into various histological subtypes, each associated with different prognoses and treatment options, including surgery, radiation, chemotherapy, and endocrine therapy. Despite advances in this area, many patients still face treatment failure, the risk of metastasis, and disease recurrence, which can ultimately lead to death. Mammary tumors, like other solid tumors, contain a population of small cells known as cancer stem-like cells (CSCs) that have high tumorigenic potential and are involved in cancer initiation, progression, metastasis, tumor recurrence, and resistance to therapy. Therefore, designing therapies specifically targeting at CSCs could help to control the growth of this cell population, leading to increased survival rates for BC patients. In this review, we discuss the characteristics of CSCs, their surface biomarkers, and the active signaling pathways associated with the acquisition of stemness in BC. We also cover preclinical and clinical studies that focus on evaluating new therapy systems targeted at CSCs in BC through various combinations of treatments, targeted delivery systems, and potential new drugs that inhibit the properties that allow these cells to survive and proliferate.

Innovative nanotheranostics: Smart nanoparticles based approach to overcome breast cancer stem cells mediated chemo- and radioresistances

The alarming increase in the number of breast cancer patients worldwide and the increasing death rate indicate that the traditional and current medicines are insufficient to fight against it. The onset of chemo- and radioresistances and cancer stem cell-based recurrence make this problem harder, and this hour needs a novel treatment approach. Competent nanoparticle-based accurate drug delivery and cancer nanotheranostics like photothermal therapy, photodynamic therapy, chemodynamic therapy, and sonodynamic therapy can be the key to solving this problem due to their unique characteristics. These innovative formulations can be a better cargo with fewer side effects than the standard chemotherapy and can eliminate the stability problems associated with cancer immunotherapy. The nanotheranostic systems can kill the tumor cells and the resistant breast cancer stem cells by novel mechanisms like local hyperthermia and reactive oxygen species and prevent tumor recurrence. These theranostic systems can also combine with chemotherapy or immunotherapy approaches. These combining approaches can be the future of anticancer therapy, especially to overcome the breast cancer stem cells mediated chemo- and radioresistances. This review paper discusses several novel theranostic systems and smart nanoparticles, their mechanism of action, and their modifications with time. It explains their relevance and market scope in the current era. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Role of stiffness and physico-chemical properties of tumour microenvironment on breast cancer cell stemness

Several physico-chemical properties of the tumour microenvironment (TME) are dysregulated during tumour progression, such as tissue stiffness, extracellular pH and interstitial fluid flow. Traditional preclinical models, although useful to study biological processes, do not provide sufficient control over these physico-chemical properties, hence limiting the understanding of cause-effect relationships between the TME and cancer cells. Breast cancer stem cells (B-CSCs), a dynamic population within the tumour, are known to affect tumour progression, metastasis and therapeutic resistance. With their emerging importance in disease physiology, it is essential to study the interplay between above-mentioned TME physico-chemical variables and B-CSC marker expression. In this work, 3D in vitro models with controlled physico-chemical properties (hydrogel stiffness and composition, perfusion, pH) were used to mimic normal and tumour breast tissue to study changes in proliferation, morphology and B-CSC population in two separate breast cancer cell lines (MCF-7 and MDA-MB 231). Cells encapsulated in alginate-gelatin hydrogels varying in stiffness (2-10 kPa), density and adhesion ligand (gelatin) were perfused (500 µL/min) for up to 14 days. Physiological (pH 7.4) and tumorigenic (pH 6.5) media were used to mimic changes in extracellular pH within the TME. We found that both cell lines have distinct responses to changes in physico-chemical factors in terms of proliferation, cell aggregates size and morphology. Most importantly, stiff and dense hydrogels (10 kPa) and acidic pH (6.5) play a key role in B-CSCs dynamics, increasing both epithelial (E-CSCs) and mesenchymal cancer stem cell (M-CSCs) marker expression, supporting direct impact of the physico-chemical microenvironment on disease onset and progression. STATEMENT OF SIGNIFICANCE: Currently no studies evaluate the impact of physico-chemical properties of the tumour microenvironment on breast cancer stem cell (B-CSC) marker expression in a single in vitro model and at the same time. In this study, 3D in vitro models with varying stiffness, extracellular pH and fluid flow are used to recapitulate the breast tumour microenvironment to evaluate for the first time their direct effect on multiple breast cancer phenotypes: cell proliferation, cell aggregate size and shape, and B-CSC markers. Results suggest these models could open new ways of monitoring disease phenotypes, from the early-onset to progression, as well as being used as testing platforms for effective identification of specific phenotypes in the presence of relevant tumour physico-chemical microenvironment.

Can EGFR be a therapeutic target in breast cancer?

Epidermal growth factor receptor (EGFR) is highly expressed in certain cancer types and is involved in regulating the biological characteristics of cancer progression, including proliferation, metastasis, and drug resistance. Various medicines targeting EGFR have been developed and approved for several cancer types, such as lung and colon cancer. To date, however, EGFR inhibitors have not achieved satisfactory clinical results in breast cancer, which continues to be the most serious malignant tumor type in females. Therefore, clarifying the underlying mechanisms related to the ineffectiveness of EGFR inhibitors in breast cancer and developing new EGFR-targeted strategies (e.g., combination therapy) remain critical challenges. Various studies have demonstrated aberrant expression and maintenance of EGFR levels in breast cancer. In this review, we summarize the regulatory mechanisms underlying EGFR protein expression in breast cancer cells, including EGFR mutations, amplification, endocytic dysfunction, recycling acceleration, and degradation disorders. We also discuss potential therapeutic strategies that act directly or indirectly on EGFR, including reducing EGFR protein expression, treating the target protein to mediate precise clearance, and inhibiting non-EGFR signaling pathways. This review should provide new therapeutic perspectives for breast cancer patients with high EGFR expression.

Anti-cancer therapeutic strategies based on HGF/MET, EpCAM, and tumor-stromal cross talk

As an intelligent disease, tumors apply several pathways to evade the immune system. It can use alternative routes to bypass intracellular signaling pathways, such as nuclear factor-κB (NF-κB), Wnt, and mitogen-activated protein (MAP)/phosphoinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR). Therefore, these mechanisms lead to therapeutic resistance in cancer. Also, these pathways play important roles in the proliferation, survival, migration, and invasion of cells. In most cancers, these signaling pathways are overactivated, caused by mutation, overexpression, etc. Since numerous molecules share these signaling pathways, the identification of key molecules is crucial to achieve favorable consequences in cancer therapy. One of the key molecules is the mesenchymal-epithelial transition factor (MET; c-Met) and its ligand hepatocyte growth factor (HGF). Another molecule is the epithelial cell adhesion molecule (EpCAM), which its binding is hemophilic. Although both of them are involved in many physiologic processes (especially in embryonic stages), in some cancers, they are overexpressed on epithelial cells. Since they share intracellular pathways, targeting them simultaneously may inhibit substitute pathways that tumor uses to evade the immune system and resistant to therapeutic agents.

Effect of long noncoding RNA CCAT2 on drug sensitivity to 5-fluorouracil of breast cancer cells through microRNA-145 meditated by p53

The current study was set out to investigate the mechanism by which silenced long noncoding RNA (lncRNA) colon cancer-associated transcript 2 (CCAT2) modulates the cell growth, migration, invasion, and drug sensitivity of breast cancer (BC) cells to 5-fluorouracil (5-Fu) with the involvement of miR-145 and p53. First, high CCAT2 expression was presented in BC cells and tissues. Subsequently, the links between CCAT2 expression and BC clinicopathological features were analyzed. Highly-expressed CCAT2 was linked to lymph node metastasis, positive progesterone receptor, estrogen receptor, and Ki-67 of BC cells. Then, the gain- and loss-of-function approaches were performed to measure the regulatory role of CCAT2 in the biological processes of BC cells. Silencing of CCAT2 suppressed in vitro cell growth, proliferation, invasion, migration abilities, and epithelial-mesenchymal transformation, increased cell apoptosis, and enhanced drug sensitivity of BC cells. Silencing of CCAT2 upregulated miR-145, which was poorly expressed in drug-resistant BC cells. p53 can bind to the miR-145 promoter region and increase miR-145 expression. Upregulation of miR-145 induced by silencing of CCAT2 can be invalidated by p53-siRNA. To conclude, p53-induced activation of miR-145 could be inhibited by CCAT2, while overexpression of CCAT2 could improve the drug resistance of BC cells to 5-Fu.

Overview of non-coding RNAs in breast cancers

Breast cancer in women is the second most common cancer and the fifth leading cause of cancer death worldwide. Although earlier diagnosis and detection of breast cancer has resulted in lower mortality rates, further advances in prevention, detection, and treatment are needed to improve outcomes and survival for women with breast cancer as well as to offer a personalized therapeutic approach. It is now well-established that non-coding RNAs (ncRNAs) represent 98% of the transcriptome but in-depth knowledge about their involvement in the regulation of gene expression is lacking. A growing body of research indicates that ncRNAs are essential for tumorigenesis by regulating the expression of tumour-related genes. In this review, we focus on their implication in breast cancer genesis but also report the latest knowledge of their theragnostic and therapeutic role. We highlight the need for accurate quantification of circulating ncRNAs which is determinant to develop reliable biomarkers. Further studies are mandatory to finally enter the era of personalized medicine for women with breast cancer.

Microbial Mediated Synthesis of Zinc Oxide Nanoparticles, Characterization and Multifaceted Applications

Nanoparticles have gained considerable importance compared to bulk counterparts due to their unique properties. Due to their high surface to volume ratio and high reactivity, metallic and metal-oxide nanostructures have shown great potential applications. Among them, zinc oxide nanoparticles (ZnONPs) have gained tremendous attention attributed to their unique properties such as low toxicity, biocompatibility, simplicity, easy fabrication, and environmental friendly. Remarkably, ZnONPs exhibit optical, physical, antimicrobial, anticancer, anti-inflammatory and wound healing properties. These nanoparticles have been applied in various fields such as in biomedicine, biosensors, electronics, food, cosmetic industries, textile, agriculture and environment. The synthesis of ZnONPs can be performed by chemical, physical and biological methods. Although the chemical and physical methods suffer from some disadvantages such as the involvement of high temperature and pressure conditions, high cost and not environmentally friendly, the green synthesis of ZnONPs offers a promising substitute to these conventional methods. On that account, the microbial mediated synthesis of ZnONPs is clean, eco-friendly, nontoxic and biocompatible method. This paper reviews the microbial synthesis of ZnONPs, parameters used for the optimization process and their physicochemical properties. The potential applications of ZnONPs in biomedical, agricultural and environmental fields as well as their toxic aspects on human beings and animals have been reviewed.

A neutrophil-mediated carrier regulates tumor stemness by inhibiting autophagy to prevent postoperative triple-negative breast cancer recurrence and metastasis

Recurrence and metastasis after resection are still the main challenges in clinical treatment of breast cancer. Residual tumor and cancer stem-like cells are the primary culprits of recurrence and metastasis. Recent research studies indicate that autophagy is a cytoprotective mechanism of tumors, which maintains the stemness of cancer cells and promotes tumor proliferation and metastasis. Here, we constructed a "Trojan horse" using neutrophils as the carrier (PH-RL@NEs) to prevent the recurrence and metastasis of postoperative breast cancer. Neutrophils, as a "Trojan horse," can quickly respond to postoperative inflammation and accurately deliver drugs to the residual tumor site. The inflammation-triggered "Trojan horse" was then opened to release the liposomes containing the chemotherapeutic drug paclitaxel (PTX) and the autophagy inhibitor hydroxychloroquine (HCQ). We found that HCQ could effectively inhibit tumor cell autophagy, interfere with tumor epithelial-mesenchymal transition, and reduce the tumor stem cell-like population. In the orthotopic 4T1 postoperative recurrence models, PTX and HCQ synergistically killed tumors and regulated the stemness of tumor cells, thereby significantly inhibiting tumor recurrence and metastasis. Our work proved that the inhibition of autophagy to reduce tumor stemness is feasible and effective, which opens up a new prospect for postoperative tumor treatment. STATEMENT OF SIGNIFICANCE: The present study aimed to solve the issues of postoperative recurrence and metastasis of breast cancer and low efficiency of drug administration after surgery. For this purpose, we constructed neutrophils containing hydroxychloroquine (HCQ) and paclitaxel (PTX) co-loaded liposomes (PH-RL@NEs), which for the first time regulated the stemness of tumor cells by inhibiting autophagy, thereby inhibiting postoperative recurrence and metastasis of breast cancer cells. The results showed that PH-RL@NEs enhanced the targeted drug delivery efficiency, with the help of postoperative inflammation chemotaxis of neutrophils. HCQ effectively inhibited autophagy of tumor cells and reduced tumor stem cell-like cells, thus improving the therapeutic effect in the 4T1 in situ postoperative recurrence model.

An innovative systematic approach introduced the involved lncRNA-miR-mRNA network in cell cycle and proliferation after conventional treatments in breast cancer patients

INTRODUCTION

The present study aimed to explore the involved lncRNA-miRNA-mRNA network in the cell cycle and proliferation after conventional treatments in Luminal A breast cancer patients.

METHODS

The candidate miRNAs (miRs), lncRNAs, and mRNAs were first taken from the Gene Expression Omnibus and TCGA databases. The lncRNA-miR-mRNA network was then constructed using the high-throughput sequencing data. The expression levels of selected targets were measured in the breast cancer and healthy samples by the Real-Time PCR technique and compared with the clinical outcomes by the Kaplan-Meier method.

RESULTS

Our analysis revealed a group of differentially expressed 3 lncRNAs, 9 miRs, and 14 mRNAs in breast cancer patients. A significant expression decrease of the selected tumor suppressor lncRNAs, miRs, and genes and a substantial expression increase of the selected onco-lncRNAs, oncomiRs, and oncogenes were obtained in the patients compared to the healthy group. The plasma levels of the lncRNAs, miRs, and mRNAs were more significant after the operation, chemotherapy, and radiotherapy than the pre-treatment. The Kaplan-Meier analysis indicated that the patients with a high expression of miR-21, miR-20b, IGF1R, and E2F2 and a low expression of miR-125a, PDCD4, and PTEN had exhibited a shorter overall survival rate.

CONCLUSION

Our results suggested that the underlying mechanisms of the lncRNA, miRs, and mRNAs and relevant signaling pathways may be considered predictive and therapeutic targets for breast cancer.

Accuracy of ultrasound elastography for predicting breast cancer response to neoadjuvant chemotherapy: A systematic review and meta-analysis

BACKGROUND

Several studies have reported the prognostic value of ultrasound elastography (UE) in patients receiving neoadjuvant chemotherapy (NACT) for breast cancer. However, the assessment of parameters differed between shear-wave elastography and strain elastography in terms of measured elasticity parameter and mode of imaging. It is important, therefore, to assess the accuracy of the two modes of elastography.

AIM

To assess the accuracy of UE for predicting the pathologic complete response (pCR) in breast cancer patients following NACT.

METHODS

A comprehensive and systematic search was performed in the databases of MEDLINE, EMBASE, SCOPUS, PubMed Central, CINAHL, Web of Science and Cochrane library from inception until December 2020. Meta-analysis was performed using STATA software “Midas” package.

RESULTS

A total of 14 studies with 989 patients were included. The pooled sensitivities were 86% [95% confidence interval (CI): 76%-92%] for UE, 77% (95%CI: 68%-84%) for shear-wave elastography, and 92% (95%CI: 73%-98%) for strain-wave elastography. The pooled score specificities were 86% (95%CI: 80%-90%) for UE, 84% (95%CI: 72%-91%) for shear-wave elasticity, and 87% (95%CI: 81%-92%) for strain-wave elastography. A significant heterogeneity was found among studies based on the chi-square test results and an I² statistic > 75%.

CONCLUSION

Strain-wave type of UE can accurately predict the pCR following NACT amongst breast cancer patients. Studies exploring its accuracy in different ethnic populations are required to strengthen the evidence.

Dinaciclib inhibits the stemness of two subtypes of human breast cancer cells by targeting the FoxM1 and Hedgehog signaling pathway

Cyclin‑dependent kinase (CDK)4/6 inhibitors in combination with endocrine therapy are the current standard of care used in the first‑line treatment of hormone receptor‑positive/HER2‑negative metastatic breast cancer (BC). Although CDK4/6 inhibitors mainly target the cell cycle, emerging evidence has indicated further potential roles of CDKs other than regulating cell cycle progression. The G₁ and G₂/M transition regulators, including cyclins D and E, as well as their catalytic partners, CDK2, CDK4 and CDK6, have been reported to play crucial roles in pluripotency maintenance and cell fate decisions of human pluripotent stem cells by controlling transcription factors, signaling pathways and epigenetic regulators. Dinaciclib, a CDK1/2/5/9 inhibitor, is currently being evaluated in clinical trials against various cancer types, including BC. However, the underlying molecular mechanisms of CDK1/2/5/9 inhibitors in regulating BC stemness remain poorly understood. The present study aimed to examine the stemness‑inhibitory effects of dinaciclib in MCF‑7 (luminal) and HCC‑1806 (triple‑negative) BC cells. We found that this drug not only effectively reduced the self‑renewal abilities and other malignant properties, but also dose‑dependently decreased the protein expression levels of three BC stem cell markers, CD44, aldehyde dehydrogenase 1 family member A1 (ALDH1A1) and BMI1 proto‑oncogene, polycomb ring finger (Bmi1), as well as three embryonic stem cell markers, Oct4, Nanog and Sox2. Moreover, the dinaciclib‑induced decrease of Oct4 and Nanog protein expression was able to be restored by co‑treatment with MG‑132, a proteasome inhibitor. Forkhead box M1 (FoxM1), both a stemness‑stimulating transcription factor and a cell cycle regulator, along with the Hedgehog signaling pathway, were identified as the therapeutic targets of dinaciclib. Collectively, the present results demonstrated a novel role of dinaciclib in suppressing BC stemness and indicated its potential use for future cancer treatments.

Circulating Tumor Cells in Breast Cancer Patients: A Balancing Act between Stemness, EMT Features and DNA Damage Responses

Circulating tumor cells (CTCs) traverse vessels to travel from the primary tumor to distant organs where they adhere, transmigrate, and seed metastases. To cope with these challenges, CTCs have reached maximal flexibility to change their differentiation status, morphology, migratory capacity, and their responses to genotoxic stress caused by metabolic changes, hormones, the inflammatory environment, or cytostatic treatment. A significant percentage of breast cancer cells are defective in homologous recombination repair and other mechanisms that protect the integrity of the replication fork. To prevent cell death caused by broken forks, alternative, mutagenic repair, and bypass pathways are engaged but these increase genomic instability. CTCs, arising from such breast tumors, are endowed with an even larger toolbox of escape mechanisms that can be switched on and off at different stages during their journey according to the stress stimulus. Accumulating evidence suggests that DNA damage responses, DNA repair, and replication are integral parts of a regulatory network orchestrating the plasticity of stemness features and transitions between epithelial and mesenchymal states in CTCs. This review summarizes the published information on these regulatory circuits of relevance for the design of biomarkers reflecting CTC functions in real-time to monitor therapeutic responses and detect evolving chemoresistance mechanisms.

Breast Cancer Stem Cells: A Clinician's View

Much has been revealed about breast cancer stem cells, their properties, and behavior and yet, a gap remains between the ever expanding knowledge and its effective clinical applications. The previous chapters have illustrated the extraordinary wealth of methodologies presently used to continue improving our understanding of breast cancer stem cells. The hope is that soon all this knowledge will translate into applicable improvements in the clinic.

Anticancer Mechanisms of Salinomycin in Breast Cancer and Its Clinical Applications

Breast cancer (BC) is the most frequent cancer among women worldwide and is the leading cause of cancer-related deaths in women. Cancer cells with stem cell-like features and tumor-initiating potential contribute to drug resistance, tumor recurrence, and metastasis. To achieve better clinical outcomes, it is crucial to eradicate both bulk BC cells and breast cancer stem cells (BCSCs). Salinomycin, a monocarboxylic polyether antibiotic isolated from Streptomyces albus, can precisely kill cancer stem cells (CSCs), particularly BCSCs, by various mechanisms, including apoptosis, autophagy, and necrosis. There is increasing evidence that salinomycin can inhibit cell proliferation, invasion, and migration in BC and reverse the immune-inhibitory microenvironment to prevent tumor growth and metastasis. Therefore, salinomycin is a promising therapeutic drug for BC. In this review, we summarize established mechanisms by which salinomycin protects against BC and discuss its future clinical applications.

Nrf2 inhibition sensitizes breast cancer stem cells to ionizing radiation via suppressing DNA repair

Radiation is widely used for cancer treatment but the radioresistance properties of cancer stem cells (CSCs) pose a significant challenge to the success of cancer therapy. Nuclear factor erythroid-2-related factor 2 (Nrf2) has emerged as a prominent regulator of cellular antioxidant responses and its over-activation is associated with drug resistant in cancer cells. However, the role of Nrf2 signaling in regulating the response of CSCs to irradiation has yet to be defined. Here, we show that exposure of triple-negative breast cancer (TNBC) cells to ionizing radiation (IR) upregulates Nrf2 expression and promotes its nuclear translocation in a reactive oxygen species (ROS)-dependent manner. Ectopic overexpression of Nrf2 attenuates, whereas knockdown of Nrf2 potentiates IR-induced killing of TNBC CSCs. Mechanistically, we found that Nrf2 knockdown increases IR-induced ROS production and impedes DNA repair at least in part via inhibition of DNA-PK. Furthermore, activation of Nrf2 by sulforaphane diminishes, whereas inhibition of Nrf2 by ML385 enhances IR-induced killing of TNBC CSCs. Collectively, these results demonstrate that IR-induced ROS production can activate Nrf2 signaling, which in turn counteracts the killing effect of irradiation. Therefore, pharmacological inhibition of IR-induced Nrf2 activation by ML385 could be a new therapeutic approach to sensitize therapy-resistant CSCs to radiotherapy.

Involvement of TRPM8 Channel in Radiation-Induced DNA Damage Repair Mechanism Contributing to Radioresistance of B16 Melanoma

Radiation is an effective cancer treatment, but cancer cells can acquire radioresistance, which is associated with increased DNA damage response and enhanced proliferative capacity, and therefore, it is important to understand the intracellular biochemical responses to γ-irradiation. The transient receptor potential melastatin 8 (TRPM8) channel plays roles in the development and progression of tumors, but it is unclear whether it is involved in the DNA damage response induced by γ-irradiation. Here, we show that a TRPM8 channel inhibitor suppresses the DNA damage response (phosphorylated histone variant H2AX-p53-binding protein 1 (γH2AX-53BP1) focus formation) and colony formation of B16 melanoma cells. Furthermore, the TRPM8 channel-specific agonist WS-12 enhanced the DNA damage response and increased the survival fraction after γ-irradiation. We found that the TRPM8 channel inhibitor enhanced G₂/M phase arrest after γ-irradiation. Phosphorylation of ataxia telangiectasia mutated and p53, which both contribute to the DNA damage response was also suppressed after γ-irradiation. In addition, the TRPM8 channel inhibitor enhanced the γ-irradiation-induced suppression of tumor growth in vivo. We conclude that the TRPM8 channel is involved in radiation-induced DNA damage repair and contributes to the radioresistance of B16 melanoma cells. TRPM8 channel inhibitors might be clinically useful as radiosensitizers to enhance radiation therapy of melanoma.

Drug Resistance in Metastatic Breast Cancer: Tumor Targeted Nanomedicine to the Rescue

Breast cancer, specifically metastatic breast, is a leading cause of morbidity and mortality in women. This is mainly due to relapse and reoccurrence of tumor. The primary reason for cancer relapse is the development of multidrug resistance (MDR) hampering the treatment and prognosis. MDR can occur due to a multitude of molecular events, including increased expression of efflux transporters such as P-gp, BCRP, or MRP1; epithelial to mesenchymal transition; and resistance development in breast cancer stem cells. Excessive dose dumping in chemotherapy can cause intrinsic anti-cancer MDR to appear prior to chemotherapy and after the treatment. Hence, novel targeted nanomedicines encapsulating chemotherapeutics and gene therapy products may assist to overcome cancer drug resistance. Targeted nanomedicines offer innovative strategies to overcome the limitations of conventional chemotherapy while permitting enhanced selectivity to cancer cells. Targeted nanotheranostics permit targeted drug release, precise breast cancer diagnosis, and importantly, the ability to overcome MDR. The article discusses various nanomedicines designed to selectively target breast cancer, triple negative breast cancer, and breast cancer stem cells. In addition, the review discusses recent approaches, including combination nanoparticles (NPs), theranostic NPs, and stimuli sensitive or “smart” NPs. Recent innovations in microRNA NPs and personalized medicine NPs are also discussed. Future perspective research for complex targeted and multi-stage responsive nanomedicines for metastatic breast cancer is discussed.

Investigating Molecular Determinants of Cancer Cell Resistance to Ionizing Radiation Through an Integrative Bioinformatics Approach

Eradication of cancer cells through exposure to high doses of ionizing radiation (IR) is a widely used therapeutic strategy in the clinical setting. However, in many cases, cancer cells can develop remarkable resistance to radiation. Radioresistance represents a prominent obstacle in the effective treatment of cancer. Therefore, elucidation of the molecular mechanisms and pathways related to radioresistance in cancer cells is of paramount importance. In the present study, an integrative bioinformatics approach was applied to three publicly available RNA sequencing and microarray transcriptome datasets of human cancer cells of different tissue origins treated with ionizing radiation. These data were investigated in order to identify genes with a significantly altered expression between radioresistant and corresponding radiosensitive cancer cells. Through rigorous statistical and biological analyses, 36 genes were identified as potential biomarkers of radioresistance. These genes, which are primarily implicated in DNA damage repair, oxidative stress, cell pro-survival, and apoptotic pathways, could serve as potential diagnostic/prognostic markers cancer cell resistance to radiation treatment, as well as for therapy outcome and cancer patient survival. In addition, our findings could be potentially utilized in the laboratory and clinical setting for enhancing cancer cell susceptibility to radiation therapy protocols.

Trailblazing perspectives on targeting breast cancer stem cells

Breast cancer (BCa) is one of the most prevalent malignant tumors affecting women's health worldwide. The recurrence and metastasis of BCa have made it a long-standing challenge to achieve remission-persistent or disease-undetectable clinical outcomes. Cancer stem cells (CSCs) possess the ability to self-renew and generate heterogeneous tumor bulk. The existence of CSCs has been found to be vital in the initiation, metastasis, therapy resistance, and recurrence of tumors across cancer types. Because CSCs grow slowly in their dormant state, they are insensitive to conventional chemotherapies; however, when CSCs emerge from their dormant state and become clinically evident, they usually acquire genetic traits that make them resistant to existing therapies. Moreover, CSCs also show evidence of acquired drug resistance in synchrony with tumor relapses. The concept of CSCs provides a new treatment strategy for BCa. In this review, we highlight the recent advances in research on breast CSCs and their association with epithelial-mesenchymal transition (EMT), circulating tumor cells (CTCs), plasticity of tumor cells, tumor microenvironment (TME), T-cell modulatory protein PD-L1, and non-coding RNAs. On the basis that CSCs are associated with multiple dysregulated biological processes, we envisage that increased understanding of disease sub-classification, selected combination of conventional treatment, molecular aberration directed therapy, immunotherapy, and CSC targeting/sensitizing strategy might improve the treatment outcome of patients with advanced BCa. We also discuss novel perspectives on new drugs and therapeutics purposing the potent and selective expunging of CSCs.

A Novel Model Incorporating Tumor Stiffness, Blood Flow Characteristics, and Ki-67 Expression to Predict Responses After Neoadjuvant Chemotherapy in Breast Cancer

Objective

To investigate the ability of tumor stiffness, tumor blood flow, and Ki-67 expression alone or in combination in predicting the pathological response to neoadjuvant chemotherapy (NACT) in breast cancer.

Patients and Methods

This prospective cohort study included 145 breast cancer patients treated with NACT. Tumor stiffness (maximum stiffness (Emax), mean stiffness (Emean)), blood score (BS), and their relative changes, were evaluated before (t0), during (t1-t5), and at the end of NACT (t6) by shear-wave elastography and optical imaging. Ki-67 expression was quantitatively evaluated by immunohistochemistry using core biopsy specimens obtained before NACT. Pathological responses were evaluated by residual cancer burden. The ability of tumor stiffness, BS, Ki-67, and predRCB-which combined ΔEmean (t2) (the relative changes in Emean after the second NACT cycle), BS2 (BS after the second NACT cycle), and Ki-67-in predicting tumor responses was compared using receiver operating characteristic curves and the Z-test.

Results

Tumor stiffness and BS decreased during NACT. ΔEmean (t2), BS2, and Ki-67 had better predictive performance than other indexes in identifying a favorable response (AUC = 0.82, 0.81, and 0.80) and resistance responses (AUC = 0.85, 0.79, and 0.84), with no significant differences between the three (p > 0.05). PredRCB had better predictive performance than any parameter alone for a favorable response (AUC = 0.90) and resistance (AUC = 0.93).

Conclusion

Tumor stiffness, BS, and Ki-67 expression showed good and similar abilities for predicting the pathological response to NACT, and predRCB was a significantly better predictor than each index alone. These results may help design therapeutic strategies for breast cancer patients undergoing NACT.

Breast cancers, mammary stem cells, and cancer stem cells, characteristics, and hypotheses

The cellular heterogeneity of breast cancers still represents a major therapeutic challenge. The latest genomic studies have classified breast cancers in distinct clusters to inform the therapeutic approaches and predict clinical outcomes. The mammary epithelium is composed of luminal and basal cells, and this seemingly hierarchical organization is dependent on various stem cells and progenitors populating the mammary gland. Some cancer cells are conceptually similar to the stem cells as they can self-renew and generate bulk populations of nontumorigenic cells. Two models have been proposed to explain the cell of origin of breast cancer and involve either the reprogramming of differentiated mammary cells or the dysregulation of mammary stem cells or progenitors. Both hypotheses are not exclusive and imply the accumulation of independent mutational events. Cancer stem cells have been isolated from breast tumors and implicated in the development, metastasis, and recurrence of breast cancers. Recent advances in single-cell sequencing help deciphering the clonal evolution within each breast tumor. Still, few clinical trials have been focused on these specific cancer cell populations.

Assessing the prognostic value of stemness-related genes in breast cancer patients

Breast cancer (BC) is currently one of the deadliest tumors worldwide. Cancer stem cells (CSCs) are a small group of tumor cells with self-renewal and differentiation abilities and high treatment resistance. One of the reasons for treatment failures is the inability to completely eliminate tumor stem cells. By using the edgeR package, we identified stemness-related differentially expressed genes in GSE69280. Via Lasso-penalized Cox regression analysis and univariate Cox regression analysis, survival genes were screened out to construct a prognostic model. Via nomograms and ROC curves, we verified the accuracy of the prognostic model. We selected 4 genes (PSMB9, CXCL13, NPR3, and CDKN2C) to establish a prognostic model from TCGA data and a validation model from GSE24450 data. We found that the low-risk score group had better OS than the high-risk score group, whether using TCGA or GSE24450 data. A prognostic model including four stemness-related genes was constructed in our study to determine targets of breast cancer stem cells (BCSCs) and improve the treatment effect.

Bufalin attenuates triple-negative breast cancer cell stemness by inhibiting the expression of SOX2/OCT4

Triple-negative breast cancer (TNBC) has the poorest prognosis among all types of breast cancer and there is yet no effective therapy. Chemotherapy is the traditional standard of care for patients with TNBC; however, treatment of TNBC with chemotherapy may lead to the enrichment of cancer stem cells (CSCs), which exhibitan enhanced capacity for self-renewal, tumor initiation and metastasis. The present study demonstrated that bufalin, a small molecular compound used in traditional Chinese medicine, exerted anticancer effects on a wide range of cancer cell lines, inhibited cell proliferation through inducing G2/M cell cycle arrest, and triggered apoptosis in the TNBC cell lines MDA-MB-231 and HCC-1937. Consistently, bufalin markedly suppressed TNBC growth in a cell line-derived xenograft model. More importantly, unlike common chemotherapeutic drugs, bufalin reduced the stemness of TNBC stem cells. A mechanistic study suggested that bufalin may suppress the proliferation of TNBC stem cells by inhibiting the expression of octamer-binding transcription factor 4 (OCT4) and sex determining region Y-box 2 (SOX2) in MDA-MB-231 and HCC-1937 cells. These results indicated that bufalin may hold promise as a therapeutic agent in TNBC, and its effects may be mediated through the SOX2/OCT4 axis.

A novel taxane, difluorovinyl-ortataxel, effectively overcomes paclitaxel-resistance in breast cancer cells

Paclitaxel (PTX) is widely used to treat breast and ovarian cancers, but innate and acquired resistance often compromises its applications. The objective of this study was to screen new-generation taxanes for their efficiency against both PTX-sensitive and PTX-resistant breast cancer cells. From twelve compounds, difluorovinyl-ortataxel (DFV-OTX) displayed potent cytotoxic activities against both PTX-sensitive and PTX-resistant breast cancer cells. Moreover, DFV-OTX effectively induced tubulin/microtubule polymerization and G2/M phase arrest, leading to apoptosis in both PTX-sensitive and PTX-resistant cancer cells. Molecular docking analysis showed that DFV-OTX possesses unique hydrogen-bonding and van der Waals interactions with β-tubulin. LC-MS/MS analysis also demonstrated that the intracellular drug amount of DFV-OTX was lower than that of PTX, which would be critical to overcome PTX-resistance. Furthermore, DFV-OTX exhibited clear efficacy in the MCF-7R and MDA-MB-231R tumor xenografts in mouse models. Taken together, our results demonstrate that the novel taxane, DFV-OTX, can effectively overcome PTX-resistance in MDA-MB-231R cells, wherein the drug resistance was attributed to ABCB1/ABCG2 upregulation and a distinct mode of action in MCF-7R cells. Our results strongly indicate that DFV-OTX is a promising chemotherapeutic agent for the treatment of PTX-resistant cancers.

Efficacy of shear-wave elastography versus dynamic optical breast imaging for predicting the pathological response to neoadjuvant chemotherapy in breast cancer

PURPOSE

Explore the value of shear-wave elastography (SWE) parameters and dynamic optical breast imaging features for predicting pathological responses to neoadjuvant chemotherapy (NACT) in breast cancer (BC).

METHOD

This prospective cohort study included 91 BC patients receiving NACT. Tumor size, SWE (maximum stiffness [Emax] and mean stiffness [Emean]), blood score (BS), and oxygen score (OS) and their relative changes were collected before (t0), during (t1-t5), and after NACT (t6). The pathological response was classified according to the residual cancer burden. Relationships between tumor size, SWE stiffness, BS, and OS at t0-t6 were analyzed, and their predictive power was compared.

RESULTS

During six NACT cycles, tumor size, tumor stiffness, and BS decreased, and tumor OS increased. ΔEmean (t2), E2mean, BS2, and OS2 had a greater power than other indexes for predicting a favorable response (AUC = 0.79, 0.71, 0.77, 0.78) and a resistance response (0.86, 0.74, 0.71, 0.71). For the favorable response, predictive power did not differ significantly between ΔEmean (t2), E2mean, BS2, and OS2, whereas for the resistance response, ΔEmean (t2) showed better prediction than E2mean, BS2, and OS2.

CONCLUSIONS

SWE stiffness, BS, and OS exhibited good and similar performances in predicting a NACT favorable response, and SWE stiffness showed better performance than BS and OS in predicting NACT resistance. These results may provide an important reference for individualized treatment in BC patients receiving NACT.

Effects of Shen Cao Granules on Chemotherapy-Induced Thrombocytopenia in Gastrointestinal Cancer Patients: A Randomized Controlled Trial

Background: To observe clinical effects of Shen Cao granules on thrombocytopenia in patients with gastrointestinal cancer undergoing chemotherapy. Patients and Methods: Patients under a FOLFIRI chemotherapy regimen (n = 92) were randomly divided into study and control groups (n = 46 for each group) and were given 10 g of Shen Cao granules and a placebo, respectively, once daily on chemotherapy treatment days. Platelet counts were measured every other day and any adverse reaction recorded during the study and at follow-up. Results: The incidence of thrombocytopenia (grades II-IV) in the study group was significantly decreased, and the length of hospitalization significantly reduced compared with the control group (11.21 ± 2.46 vs 15.34 ± 3.68 days, P < .05). The minimum numbers of post-chemotherapy platelets and the values of platelet counts 21 days after chemotherapy were significantly increased ([100.65 ± 63.16] × 10⁹/L vs [60.21 ±37.22] × 10⁹/L, P < .05; [267.81 ± 81.32] × 10⁹/L vs [146.42 ± 70.54] × 10⁹/L, P < .001), and the duration of thrombocytopenia and treatment with recombinant human interleukin-11 was significantly decreased in the Shen Cao treatment compared with the control group. No serious adverse events were observed. Conclusions: Shen Cao granules were effective in decreasing chemotherapy-induced thrombocytopenia, shortened the duration of thrombocytopenia, and reduced the length of hospital stay and costs.

Radiation and Stemness Phenotype May Influence Individual Breast Cancer Outcomes: The Crucial Role of MMPs and Microenvironment

Breast cancer is the most common cancer in women. Radiotherapy (RT) is one of the mainstay treatments for cancer but in some cases is not effective. Cancer stem cells (CSCs) within the tumor can be responsible for recurrence and metastasis after RT. Matrix metalloproteases (MMPs), regulated mainly by tissue inhibitors of metalloproteinases (TIMPs) and histone deacetylases (HDACs), may also contribute to tumor development by modifying its activity after RT. The aim of this work was to study the effects of RT on the expression of MMPs, TIMPs and HDACs on different cell subpopulations in MCF-7, MDA-MB-231 and SK-BR-3 cell lines. We assessed the in vitro expression of these genes in different 3D culture models and induced tumors in female NSG mice by orthotopic xenotransplants. Our results showed that gene expression is related to the cell subpopulation studied, the culture model used and the single radiation dose administered. Moreover, the crucial role played by the microenvironment in terms of cell interactions and CSC plasticity in tumor growth and RT outcome is also shown, supporting the use of higher doses (6 Gy) to achieve better control of tumor development.

A Bioinformatic Approach for the Identification of Molecular Determinants of Resistance/Sensitivity to Cancer Thermotherapy

Application of heat above 43°C and up to 47°C, the so-called “thermal ablation” range, leads to tumor cell destruction either by apoptosis or by necrosis. However, tumor cells have developed mechanisms of defense that render them thermoresistant. Of importance, the in situ application of heat for the treatment of localized solid tumors can also prime specific antitumor immunity. Herein, a bioinformatic approach was employed for the identification of molecular determinants implicated in thermoresistance and immunogenic cell death (ICD). To this end, both literature-derived (text mining) and microarray gene expression profile data were processed, followed by functional enrichment analysis. Two important functional gene modules were detected in hyperthermia resistance and ICD, the former including members of the heat shock protein (HSP) family of molecular chaperones and the latter including immune-related molecules, respectively. Of note, the molecules HSP90AA1 and HSPA4 were found common between thermoresistance and damage signaling molecules (damage-associated molecular patterns (DAMPs)) and ICD. In addition, the prognostic potential of HSP90AA1 and HSPA4 overexpression for cancer patients' overall survival was investigated. The results of this study could constitute the basis for the strategic development of more efficient and personalized therapeutic strategies against cancer by means of thermotherapy, by taking into consideration the genetic profile of each patient.

Target delivery selective CSF-1R inhibitor to tumor-associated macrophages via erythrocyte-cancer cell hybrid membrane camouflaged pH-responsive copolymer micelle for cancer immunotherapy

Tumor-associated macrophages (TAMs) is a promising therapeutic target for cancer immunotherapy, while TAMs targeting therapy using nano-sized drug delivery system (NDDS) is a great challenge. To overcome these drawbacks, a novel erythrocyte-cancer cell hybrid membrane camouflaged pH-responsive copolymer micelle (dextran-grafted-poly (histidine) copolymer) was prepared to target deliver a selective CSF-1R inhibitor: BLZ-945 (shorten as DH@ECm) to TAMs for TAMs depletion. The prepared DH@ECm possessed favorable particle size (~190 nm) preferable immune camouflage and tumor homologies targeting characteristic when it was intravenously administrated into blood system. In tumor acidic microenvironment, DH@ECm possessed pH-responsive characteristic and unique "membrane escape effect" to facilitate recognition and internalization by TAMs via dextran-CD206 receptor specific interaction (about 3.9 fold than free drug), followed by TAMs depletion in vitro. For in vivo studies, DH@ECm could reverse tumor immune-microenvironment with the elevation of CD8⁺ T cells and possess sufficient tumor immunotherapy (inhibition rate: 64.5%). All the in vitro and in vivo studies demonstrated the therapeutical potential of DH@ECm for tumor immunotherapy.

Involvement of adenosine A2B receptor in radiation-induced translocation of epidermal growth factor receptor and DNA damage response leading to radioresistance in human lung cancer cells

BACKGROUND

Adenosine receptors are involved in tumor growth, progression, and response to therapy. Among them, A2B receptor is highly expressed in various tumors. Furthermore, ionizing radiation induces translocation of epidermal growth factor receptor (EGFR), which promotes DNA repair and contributes to radioresistance. We hypothesized that A2B receptor might be involved in the translocation of EGFR.

METHODS

We investigated whether A2B receptor is involved in EGFR translocation and DNA damage response (γH2AX/53BP1 focus formation) of lung cancer cells by means of immunofluorescence studies. Radiosensitivity was evaluated by colony formation assay after γ-irradiation.

RESULTS

A2B receptor was expressed at higher levels in cancer cells than in normal cells. A2B receptor antagonist treatment or A2B receptor knockdown suppressed EGFR translocation, γH2AX/53BP1 focus formation, and colony formation of lung cancer cell lines A549, calu-6 and NCI-H446, compared with a normal cell line (beas-2b). γ-Irradiation-induced phosphorylation of src and EGFR was also attenuated by suppression of A2B receptor expression.

CONCLUSION

Activation of A2B receptor mediates γ-radiation-induced translocation of EGFR and phosphorylation of src and EGFR, thereby promoting recovery of irradiated lung cancer cells from DNA damage.

GENERAL SIGNIFICANCE

Our results indicate that A2B receptors contribute to radiation resistance in a cancer-cell-specific manner, and may be a promising target for radiosensitizers in cancer radiotherapy.

The Regulatory Role of MicroRNAs in Breast Cancer

MicroRNAs (miRNAs) are small non-coding RNA molecules which function as critical post-transcriptional gene regulators of various biological functions. Generally, miRNAs negatively regulate gene expression by binding to their selective messenger RNAs (mRNAs), thereby leading to either mRNA degradation or translational repression, depending on the degree of complementarity with target mRNA sequences. Aberrant expression of these miRNAs has been linked etiologically with various human diseases including breast cancer. Different cellular pathways of breast cancer development such as cell proliferation, apoptotic response, metastasis, cancer recurrence and chemoresistance are regulated by either the oncogenic miRNA (oncomiR) or tumor suppressor miRNA (tsmiR). In this review, we highlight the current state of research into miRNA involved in breast cancer, with particular attention to articles published between the years 2000 to 2019, using detailed searches of the databases PubMed, Google Scholar, and Scopus. The post-transcriptional gene regulatory roles of various dysregulated miRNAs in breast cancer and their potential as therapeutic targets are also discussed.

Potential Role of MSC/Cancer Cell Fusion and EMT for Breast Cancer Stem Cell Formation

Solid tumors comprise of maturated cancer cells and self-renewing cancer stem-like cells (CSCs), which are associated with various other nontumorigenic cell populations in the tumor microenvironment. In addition to immune cells, endothelial cells, fibroblasts, and further cell types, mesenchymal stroma/stem-like cells (MSC) represent an important cell population recruited to tumor sites and predominantly interacting with the different cancer cells. Breast cancer models were among the first to reveal distinct properties of CSCs, however, the cellular process(es) through which these cells are generated, maintained, and expanded within neoplastic tissues remains incompletely understood. Here, we discuss several possible scenarios that are not mutually exclusive but may even act synergistically: fusion of cancer cells with MSC to yield hybrid cells and/or the induction of epithelial-mesenchymal transition (EMT) in breast cancer cells by MSC, which can relay signals for retrodifferentiation and eventually, the generation of breast CSCs (BCSCs). In either case, the consequences may be promotion of self-renewal capacity, tumor cell plasticity and heterogeneity, an increase in the cancer cells’ invasive and metastatic potential, and the acquisition of resistance mechanisms towards chemo- or radiotherapy. While specific signaling mechanisms involved in each of these properties remain to be elucidated, the present review article focusses on a potential involvement of cancer cell fusion and EMT in the development of breast cancer stem cells.

LSD1 coordinates with the SIN3A/HDAC complex and maintains sensitivity to chemotherapy in breast cancer

Lysine-specific demethylase 1 (LSD1) was the first histone demethylase identified as catalysing the removal of mono- and di-methylation marks on histone H3-K4. Despite the potential broad action of LSD1 in transcription regulation, recent studies indicate that LSD1 may coordinate with multiple epigenetic regulatory complexes including CoREST/HDAC complex, NuRD complex, SIRT1, and PRC2, implying complicated mechanistic actions of this seemingly simple enzyme. Here, we report that LSD1 is also an integral component of the SIN3A/HDAC complex. Transcriptional target analysis using ChIP-on-chip technology revealed that the LSD1/SIN3A/HDAC complex targets several cellular signalling pathways that are critically involved in cell proliferation, survival, metastasis, and apoptosis, especially the p53 signalling pathway. We have demonstrated that LSD1 coordinates with the SIN3A/HDAC complex in inhibiting a series of genes such as CASP7, TGFB2, CDKN1A(p21), HIF1A, TERT, and MDM2, some of which are oncogenic. Our experiments also found that LSD1 and SIN3A are required for optimal survival and growth of breast cancer cells while also essential for the maintenance of epithelial homoeostasis and chemosensitivity. Our data indicate that LSD1 is a functional alternative subunit of the SIN3A/HDAC complex, providing a molecular basis for the interplay of histone demethylation and deacetylation in chromatin remodelling, and suggest that the LSD1/SIN3A/HDAC complex could be a target for breast cancer therapeutic strategies.

RhoC regulates radioresistance via crosstalk of ROCK2 with the DNA repair machinery in cervical cancer

Background

Radioresistance remains a challenge to the successful treatment of various tumors. Intrinsic factors like alterations in signaling pathways regulate response to radiation. RhoC, which has been shown to modulate several tumor phenotypes has been investigated in this report for its role in radioresistance. In vitro and clinical sample-based studies have been performed to understand its contribution to radiation response in cervical cancer and this is the first report to establish the role of RhoC and its effector ROCK2 in cervical cancer radiation response.

Methods

Biochemical, transcriptomic and immunological approaches including flow cytometry and immunofluorescence were used to understand the role of RhoC and ROCK2. RhoC variants, siRNA and chemical inhibitors were used to alter the function of RhoC and ROCK2. Transcriptomic profiling was performed to understand the gene expression pattern of the cells. Live sorting using an intracellular antigen has been developed to isolate the cells for transcriptomic studies.

Results

Enhanced expression of RhoC conferred radioprotection on the tumor cells while inhibition of RhoC resulted in sensitization of cells to radiation. The RhoC overexpressing cells had a better DNA repair machinery as observed using transcriptomic analysis. Similarly, overexpression of ROCK2, protected tumor cells against radiation while its inhibition increased radiosensitivity in vitro. Further investigations revealed that ROCK2 inhibition abolished the radioresistance phenotype, conferred by RhoC on SiHa cells, confirming that it is a downstream effector of RhoC in this context. Additionally, transcriptional analysis of the live sorted ROCK2 high and ROCK2 low expressing SiHa cells revealed an upregulation of the DNA repair pathway proteins. Consequently, inhibition of ROCK2 resulted in reduced expression of pH2Ax and MRN complex proteins, critical to repair of double strand breaks. Clinical sample-based studies also demonstrated that ROCK2 inhibition sensitizes tumor cells to irradiation.

Conclusions

Our data primarily indicates that RhoC and ROCK2 signaling is important for the radioresistance phenotype in cervical cancer tumor cells and is regulated via association of ROCK2 with the proteins of DNA repair pathway involving pH2Ax, MRE11 and RAD50 proteins, partly offering insights into the mechanism of radioresistance in tumor cells. These findings highlight RhoC-ROCK2 signaling involvement in DNA repair and urge the need for development of these molecules as targets to alleviate the non-responsiveness of cervical cancer tumor cells to irradiation treatment.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1385-7) contains supplementary material, which is available to authorized users.

Hyaluronic acid hydrogels with defined crosslink density for the efficient enrichment of breast cancer stem cells

Cancer stem cells (CSCs) have been much proposed as potential tumor eradication targets since they possess highly tumorigenic qualities. However, efficient and fast enrichment of CSCs for cancer biology study and drug screening has been challenging. CD44 is a cell surface receptor for hyaluronic acid (HA) and has been reported as an important CSC marker. Here, we show a simple and label-free method for the enrichment of CSCs highly expressing CD44 using enzymatically crosslinked HA hydrogels. HA hydrogels were formed with different crosslink densities to modulate the interaction between the CD44 and HA chains. We show that HA hydrogels with defined crosslink densities isolated cancer cells expressing high CD44 from breast cancer cell lines in a facile, efficient manner. The enriched cells exhibited CSC-like characteristics such as high expression of CSC markers (octamer-binding transcription factor 4 (OCT4) and aldehyde dehydrogenase 1 (ALDH1)), enhanced tumorsphere formation and chemoresistance. The enriched cells also displayed strong tumorigenicity, metastatic potential and poor survival in vivo. The HA hydrogel provides a simple, fast and efficient platform for CSC enrichment and promotes new anticancer strategies that target breast CSCs. STATEMENT OF SIGNIFICANCE: There is strong interest in developing isolation methods for cancer stem cells (CSCs), due in growing desire for CSC eradication for promising cancer therapy. Tumor sphere formation and fluorescence-activated cell sorting have been widely used for CSC isolation, while these methods require cultivation for several days and labelling of cell surface proteins, respectively. A simple and label-free method for breast CSC isolation is developed using HA-based hydrogels with tunable crosslink density. The efficient enrichment of breast CSCs is achieved by HA-CD44 specific interaction, which is controlled by hydrogel crosslink density. We believe that the simple approach that isolates cells with CSC-like characteristics would facilitate the anticancer drug development and cancer research.

Chemoresistance mechanisms of breast cancer and their countermeasures

Chemoresistance is one of the major challenges for the breast cancer treatment. Owing to its heterogeneous nature, the chemoresistance mechanisms of breast cancer are complicated, and not been fully elucidated. The existing treatments fall short of offering adequate solution to drug resistance, so more effective approaches are desperately needed to improve existing therapeutic regimens. To overcome this hurdle, a number of strategies are being investigated, such as novel agents or drug carriers and combination treatment. In addition, some new therapeutics including gene therapy and immunotherapy may be promising for dealing with the resistance. In this article, we review the mechanisms of chemoresistance in breast cancer. Furthermore, the potential therapeutic methods to overcome the resistance were discussed.

miR3609 sensitizes breast cancer cells to adriamycin by blocking the programmed death-ligand 1 immune checkpoint

Chemoresistance is the leading cause of breast cancer therapy failure, and studies of the mechanisms underlying chemoresistance and the treatment of drug-resistant tumors remain challenging. In the present study, we discovered a novel microRNA, miR3609, that influences the malignancy of breast cancer. Our results showed miR-3609 expression was lower in resistant breast cancer cells than in sensitive breast cancer cells (MCF-7), while PD-L1 expression was higher in resistant breast cancer cells than in sensitive breast cancer cells. Co-transfection of a miR-3609 plasmid with a luciferase construct containing the PD-L1 3'-untranslated region suppressed luciferase activity. Transfection of a miR-3609 mimic markedly suppressed PD-L1 protein expression in MDA-MB-231 and MDA-MB-468 cells in a dose-dependent manner and increased the sensitivity of MCF7/ADR cells to adriamycin, whereas transfection of a miR-3609 inhibitor enhanced PD-L1 protein expression in HBL-100 and MCF-7 cells. In addition, knockdown of PD-L1 by siRNA restored the sensitivity of MCF7/ADR cells to adriamycin. Mice injected with breast cancer cells stably overexpressing miR3609 survived markedly longer and had fewer tumors than mice injected with control miRNA (miR-sc)-transfected cells. Treatment with a CD8⁺ blocking antibody (anti-CD8) eliminated these effects, suggesting that CD8⁺ T cells are required for the efficacy of miR3609 in breast cancer. Further, low miR-3609 expression and high PD-L1 expression were correlated with poor prognosis in breast cancer patients. Therefore, restoration of miR-3609 expression may sensitize breast cancer to adriamycin by blocking PD-L1 expression.