The mechanism between epithelial mesenchymal transition in breast cancer and hypoxia microenvironment

ALDH and cancer stem cells: Pathways, challenges, and future directions in targeted therapy

Human ALDH comprise 19 subfamilies in which ALDH1A1, ALDH1A3, ALDH3A1, ALDH5A1, ALDH7A1, and ALDH18A1 are implicated in CSC. Studies have shown that ALDH can also be involved in drug resistance and standard chemotherapy regimens are ineffective in treating patients at the stage of disease recurrence. Existing chemotherapeutic drugs eliminate the bulk of tumors but are usually not effective against CSC which express ALDH+ population. Henceforth, targeting ALDH is convincing to treat the patient's post-relapse. Combination therapies that interlink signaling mechanisms seem promising to increase the overall disease-free survival rate. Therefore, targeting ALDH through ALDH inhibitors along with immunotherapies may create a novel platform for translational research. This review aims to fill in the gap between ALDH1 family members in relation to its cell signaling mechanisms, highlighting their potential as molecular targets to sensitize recurrent tumors and bring forward the future development concerning the current progress and draw backs. This review summarizes the role of cancer stem cells and their upregulation by maintaining the tumor microenvironment in which ALDH is specifically highlighted. It discusses the regulation of ALDH family proteins and the crosstalk between ALDH and CSC in relation to cancer metabolism. Furthermore, it establishes the correlation between ALDH involved signaling mechanisms and their specific targeted inhibitors, as well as their functional modularity, bioavailability, and mechanistic role in various cancers.

TCF12-regulated GRB7 facilitates the HER2+ breast cancer progression by activating Notch1 signaling pathway

BACKGROUND

Human epidermal growth factor receptor 2-positive (HER2+) breast cancer (BC), which accounts for approximately one-fifth of all BCs, are highly invasive with a high rate of recurrence and a poor prognosis. Several studies have shown that growth factor receptor-bound protein 7 (GRB7) might be a potential therapeutic target for tumor diagnosis and prognosis. Nevertheless, the role of GRB7 in HER2+ BC and its underlying mechanisms have not been fully elucidated. The aim of this study was to investigate the biological function and regulatory mechanism of GRB7 in HER2+ BC.

METHODS

Bioinformatics analysis was performed using the TCGA, GEO and CancerSEA databases to evaluate the clinical significance of GRB7. RT quantitative PCR, western blot and immunofluorescence were conducted to assess the expression of GRB7 in BC cell lines and tissues. MTT, EdU, colony formation, wound healing, transwell, and xenograft assays were adopted to explore the biological function of GRB7 in HER2+ BC. RNA sequencing was performed to analyze the signaling pathways associated with GRB7 in SK-BR-3 cells after the cells were transfected with GRB7 siRNA. Chromatin immunoprecipitation analysis (ChIP) and luciferase reporter assay were employed to elucidate the potential molecular regulatory mechanisms of GRB7 in HER2+ BC.

RESULTS

GRB7 was markedly upregulated and associated with poor prognosis in BC, especially in HER2+ BC. Overexpression of GRB7 increased the proliferation, migration, invasion, and colony formation of HER2+ BC cells, while depletion of GRB7 had the opposite effects in HER2+ BC cells and inhibited xenograft growth. ChIP-PCR and luciferase reporter assay revealed that TCF12 directly bound to the promoter of the GRB7 gene to promote its transcription. GRB7 facilitated HER2+ BC epithelial-mesenchymal transition (EMT) progression by interacting with Notch1 to activate Wnt/β-catenin pathways and other signaling (i.e., AKT, ERK). Moreover, forced GRB7 overexpression activated Wnt/β-catenin to promote EMT progression, and partially rescued the inhibition of HER2+ BC proliferation, migration and invasion induced by TCF12 silencing.

CONCLUSIONS

Our work elucidates the oncogenic role of GRB7 in HER2+ BC, which could serve as a prognostic indicator and promising therapeutic target.

Cellular zinc metabolism and zinc signaling: from biological functions to diseases and therapeutic targets

Zinc metabolism at the cellular level is critical for many biological processes in the body. A key observation is the disruption of cellular homeostasis, often coinciding with disease progression. As an essential factor in maintaining cellular equilibrium, cellular zinc has been increasingly spotlighted in the context of disease development. Extensive research suggests zinc's involvement in promoting malignancy and invasion in cancer cells, despite its low tissue concentration. This has led to a growing body of literature investigating zinc's cellular metabolism, particularly the functions of zinc transporters and storage mechanisms during cancer progression. Zinc transportation is under the control of two major transporter families: SLC30 (ZnT) for the excretion of zinc and SLC39 (ZIP) for the zinc intake. Additionally, the storage of this essential element is predominantly mediated by metallothioneins (MTs). This review consolidates knowledge on the critical functions of cellular zinc signaling and underscores potential molecular pathways linking zinc metabolism to disease progression, with a special focus on cancer. We also compile a summary of clinical trials involving zinc ions. Given the main localization of zinc transporters at the cell membrane, the potential for targeted therapies, including small molecules and monoclonal antibodies, offers promising avenues for future exploration.

Photothermal-driven micro/nanomotors: From structural design to potential applications

Micro/nanomotors (MNMs) that accomplish autonomous movement by transforming external energy into mechanical work are attractive cargo delivery vehicles. Among various propulsion mechanisms of MNMs, photothermal propulsion has gained considerable attention because of their unique advantages, such as remote, flexible, accurate, biocompatible, short response time, etc. Moreover, besides as a propulsion source, the light has been extensively investigated as an excitation source in bioimaging, photothermal therapy (PTT), photodynamic therapy (PDT) and so on. Furthermore, the geometric topology and morphology of MNMs have a tremendous impact on improving their performance in motion behavior under NIR light propulsion, environmental suitability and functional versatility. Hence, this review article provides a comprehensive overview of structural design principles and construction strategies of photothermal-driven MNMs, and their emerging nanobiomedical applications. Finally, we further provide an outlook towards prospects and challenges during the development of photothermal-driven MNMs in the future. STATEMENT OF SIGNIFICANCE: Photothermal-driven micro/nanomotors (MNMs) that are regarded as functional cargo delivery tools have gained considerable attention because of unique advantages in propulsion mechanisms, such as remote, flexible, accurate and fully biocompatible light manipulation and extremely short light response time. The geometric topology and morphology of MNMs have a tremendous impact on improving their performance in motion behavior under NIR light propulsion, environmental suitability and functional versatility of MNMs. There are no reports about the review focusing on photothermal-driven MNMs up to now. Herein, we systematically review the latest progress of photothermal-driven MNMs including design principle, fabrication strategy of various MNMs with different structures and nanobiomedical applications. Moreover, the summary and outlook on the development prospects and challenges of photothermal-driven MNMs are proposed, hoping to provide new ideas for the future design of photothermal-driven MNMs with efficient propulsion, multiple functions and high biocompatibility.

Cellular signaling in the hypoxic cancer microenvironment: Implications for drug resistance and therapeutic targeting

The rewiring of cellular metabolism is a defining characteristic of cancer, as tumor cells adapt to acquire essential nutrients from a nutrient-poor environment to sustain their viability and biomass. While hypoxia has been identified as a major factor depriving cancer cells of nutrients, recent studies have revealed that cancer cells distant from supporting blood vessels also face nutrient limitations. To overcome this challenge, hypoxic cancer cells, which heavily rely on glucose as an energy source, employ alternative pathways such as glycogen metabolism and reductive carboxylation of glutamine to meet their energy requirements for survival. Our preliminary studies, alongside others in the field, have shown that under glucose-deficient conditions, hypoxic cells can utilize mannose and maltose as alternative energy sources. This review aims to comprehensively examine the hypoxic cancer microenvironment, its association with drug resistance, and potential therapeutic strategies for targeting this unique niche. Furthermore, we will critically evaluate the current literature on hypoxic cancer microenvironments and explore state-of-the-art techniques used to analyze alternate carbohydrates, specifically mannose and maltose, in complex biological fluids. We will also propose the most effective analytical methods for quantifying mannose and maltose in such biological samples. By gaining a deeper understanding of the hypoxic cancer cell microenvironment and its role in drug resistance, novel therapeutic approaches can be developed to exploit this knowledge.

Targeting breast cancer stem cells through retinoids: A new hope for treatment

Breast cancer is a complex and diverse disease accounting for nearly 30% of all cancers diagnosed in females. But unfortunately, patients develop resistance to the existing chemotherapeutic regimen, resulting in approximately 90% treatment failure. With over half a million deaths annually, it is imperative to explore new therapeutic approaches to combat the disease. Within a breast tumor, a small sub-population of heterogeneous cells, with a unique ability of self-renew and differentiation and responsible for tumor formation, initiation, and recurrence are referred to as breast cancer stem cells (BCSCs). These BCSCs have been identified as one of the main contributors to chemoresistance in breast cancer, making them an attractive target for developing novel therapeutic strategies. These cells exhibit surface biomarkers such as CD44+, CD24-/LOW, ALDH, CD133, and CD49f phenotypes. Higher expression of CD44+ and ALDH activity has been associated with the formation of tumors in various cancers. Moreover, the abnormal regulation of signaling pathways, including Hedgehog, Notch, β-catenin, JAK/STAT, and P13K/AKT/mTOR, leads to the formation of cancer stem cells, resulting in the development of tumors. The growing drug resistance in BC is a significant challenge, highlighting the need for new therapeutic strategies to combat this dreadful disease. Retinoids, a large group of synthetic derivatives of vitamin A, have been studied as chemopreventive agents in clinical trials and have been shown to regulate various crucial biological functions including vision, development, inflammation, and metabolism. On a cellular level, the retinoid activity has been well characterized and translated and is known to induce differentiation and apoptosis, which play important roles in the outcome of the transformation of tissues into malignant. Retinoids have been investigated extensively for their use in the treatment and prevention of cancer due to their high receptor-binding affinity to directly modulate gene expression programs. Therefore, in this study, we aim to summarize the current understanding of BCSCs, their biomarkers, and the associated signaling pathways. Retinoids, such as Adapalene, a third-generation retinoid, have shown promising anti-cancer potential and may serve as therapeutic agents to target BCSCs.

Breast tumor-on-chip: from the tumor microenvironment to medical applications

With the development of microfluidic technology, tumor-on-chip models have gradually become a new tool for the study of breast cancer because they can simulate more key factors of the tumor microenvironment compared with traditional models in vitro. Here, we review up-to-date advancements in breast tumor-on-chip models. We summarize and analyze the breast tumor microenvironment (TME), preclinical breast cancer models for TME simulation, fabrication methods of tumor-on-chip models, tumor-on-chip models for TME reconstruction, and applications of breast tumor-on-chip models and provide a perspective on breast tumor-on-chip models. This review will contribute to the construction and design of microenvironments for breast tumor-on-chip models, even the development of the pharmaceutical field, personalized/precision therapy, and clinical medicine.

Exploration of epithelial-mesenchymal transition-related lncRNA signature and drug sensitivity in breast cancer

Background

Breast cancer (BRCA) has become the most diagnosed cancer worldwide for female and seriously endanger female health. The epithelial-mesenchymal transition (EMT) process is associated with metastasis and drug resistance in BRCA patients. However, the prognostic value of EMT-related lncRNA in BRCA still needs to be revealed. The aim of this study is to construct an EMT-related lncRNA (ERL) signature with accuracy predictive ability for the prognosis of BRCA patients.

Methods

RNA-seq expression data and Clinical characteristics obtained from the TCGA (The Cancer Genome Atlas) were used in the study. First, we identified the EMT-related lncRNA by the Pearson correlation analysis. An EMT-related lncRNAs prognostic risk signature was constructed using univariate Cox regression and Lasso-penalized Cox regression analyses. The model's performance was validated using Kaplan-Meier (KM) survival analysis, ROC curve and C-index. Finally, a nomogram was constructed for clinical practice in evaluating the patients with BRCA and validated by calibration curve and decision curve analysis (DCA). We also evaluated the drug sensitivity of signature lncRNA and the tumor immune cell infiltration in breast cancer.

Results

We constructed a 10-lncRNA risk score signature based on the lncRNAs associated with the EMT process. We could assign BRCA patients to the high- and low-risk group according to the median risk score. The prognostic risk signature showed excellent accuracy and demonstrated sufficient independence from other clinical characteristics. The immune cell infiltration analysis showed that the prognostic risk signature was related to the infiltration of the immune cell subtype. Drug sensitivity analysis proved ERLs signature could effectively predict the sensitivity of patients to common chemotherapy drugs in BRCA and provide guidance for chemotherapy drugs for high-risk and low-risk patients.

Conclusion

Our ERL signature and nomogram have excellent prognostic value and could become reliable tools for clinical guidance.

Berberine inhibits breast carcinoma proliferation and metastasis under hypoxic microenvironment involving gut microbiota and endogenous metabolites

A potential role of berberine, a benzyl isoquinoline alkaloid, in cancer therapy is apparent. Its underlying mechanisms of berberine against breast carcinoma under hypoxia have not been elucidated. We focused on the doubt how berberine restrains breast carcinoma under hypoxia in vitro and in vivo. A molecular analysis of the microbiome via 16S rDNA gene sequencing of DNA from mouse faeces confirmed that the abundances and diversity of gut microbiota were significantly altered in 4T1/Luc mice with higher survival rate following berberine treatment. A metabolome analysis liquid chromatography-mass spectrometer/mass spectrometer (LC-MS/MS) revealed that berberine regulated various endogenous metabolites, especially L-palmitoylcarnitine. Furthermore, the cytotoxicity of berberine was investigated in MDA-MB-231, MCF-7, and 4T1 cells. In vitro to simulate under hypoxic environment, MTT assay showed that berberine inhibited the proliferation of MDA-MB-231, MCF-7, and 4T1 cells with IC₅₀ values of 4.14 ± 0.35μM, 26.53 ± 3.12μM and 11.62 ± 1.44μM, respectively. Wound healing and trans-well invasion studies revealed that berberine inhibited the invasion and migration of breast cancer cells. RT-qPCR analysis shed light that berberine reduced the expression of hypoxia-inducible factor-1α (HIF-1α) gene. Immunofluorescence and western blot demonstrated that berberine decreased the expression of E-cadherin and HIF-1α protein. Taken together, these results provide evidence that berberine efficiently suppresses breast carcinoma growth and metastasis in a hypoxic microenvironment, highlighting the potential of berberine as a promising anti-neoplastic agent to combat breast carcinoma.

A comparative study of smart nanoformulations of diethyldithiocarbamate with Cu4O3 nanoparticles or zinc oxide nanoparticles for efficient eradication of metastatic breast cancer

Metastatic tumor is initiated by metastatic seeds (cancer stem cells "CSCs") in a controlled redox microenvironment. Hence, an effective therapy that disrupts redox balance with eliminating CSCs is critical. Diethyldithiocarbamate (DE) is potent inhibitor of radical detoxifying enzyme (aldehyde dehydrogenase "ALDH"1A) causing effective eradication of CSCs. This DE effect was augmented and more selective by its nanoformulating with green synthesized copper oxide (Cu₄O₃) nanoparticles (NPs) and zinc oxide NPs, forming novel nanocomplexes of CD NPs and ZD NPs, respectively. These nanocomplexes exhibited the highest apoptotic, anti-migration, and ALDH1A inhibition potentials in M.D. Anderson-metastatic breast (MDA-MB) 231 cells. Importantly, these nanocomplexes revealed more selective oxidant activity than fluorouracil by elevating reactive oxygen species with depleting glutathione in only tumor tissues (mammary and liver) using mammary tumor liver metastasis animal model. Due to higher tumoral uptake and stronger oxidant activity of CD NPs than ZD NPs, CD NPs had more potential to induce apoptosis, suppress hypoxia-inducing factor gene, and eliminate CD44⁺CSCs with downregulating their stemness, chemoresistance, and metastatic genes and diminishing hepatic tumor marker (α-fetoprotein). These potentials interpreted the highest tumor size reduction with complete eradicating tumor metastasis to liver in CD NPs. Consequently, CD nanocomplex revealed the highest therapeutic potential representing a safe and promising nanomedicine against the metastatic stage of breast cancer.

Glioblastoma and the search for non-hypothesis driven combination therapeutics in academia

Glioblastoma (GBM) remains a cancer of high unmet clinical need. Current standard of care for GBM, consisting of maximal surgical resection, followed by ionisation radiation (IR) plus concomitant and adjuvant temozolomide (TMZ), provides less than 15-month survival benefit. Efforts by conventional drug discovery to improve overall survival have failed to overcome challenges presented by inherent tumor heterogeneity, therapeutic resistance attributed to GBM stem cells, and tumor niches supporting self-renewal. In this review we describe the steps academic researchers are taking to address these limitations in high throughput screening programs to identify novel GBM combinatorial targets. We detail how they are implementing more physiologically relevant phenotypic assays which better recapitulate key areas of disease biology coupled with more focussed libraries of small compounds, such as drug repurposing, target discovery, pharmacologically active and novel, more comprehensive anti-cancer target-annotated compound libraries. Herein, we discuss the rationale for current GBM combination trials and the need for more systematic and transparent strategies for identification, validation and prioritisation of combinations that lead to clinical trials. Finally, we make specific recommendations to the preclinical, small compound screening paradigm that could increase the likelihood of identifying tractable, combinatorial, small molecule inhibitors and better drug targets specific to GBM.

Three-dimensional core-shell alginate microsphere for cancer hypoxia simulation in vitro

Hypoxia is one of the major causes of cancer resistance and metastasis. Currently, it is still lack of convenient ways to simulate the in vivo hypoxic tumor microenvironment (TME) under normoxia in vitro. In this study, based on multi-polymerized alginate, we established a three-dimensional culture system with a core-shell structure (3d-ACS), which prevents oxygen diffusion to a certain extent, thereby simulating the hypoxic TME in vivo. The cell activity, hypoxia inducible factor (HIF) expression, drug resistance, and the related gene and protein changes of the gastric cancer (GC) cells were investigated in vitro and in vivo. The results demonstrated that the GC cells formed organoid-like structures in the 3d-ACS and manifested more aggressive growth and decreased drug responses. Our study provides an accessible hypoxia platform in the laboratory with moderate configuration and it may be applied in studies of the hypoxia-induced drug resistances and other preclinical fields.

Anti-metastatic breast cancer potential of novel nanocomplexes of diethyldithiocarbamate and green chemically synthesized iron oxide nanoparticles

Mortality rate of metastatic breast cancer is linked to cancer stem cells (CSCs)' aggressive features (chemoresistance to apoptosis and redox imbalance). Therefore, unique dual therapeutic strategy compacts CSCs with inducing oxidative stress-mediated nonapoptosis (ferroptosis), confers effective malignant tumor eradication. Diethyldithiocarbamate (DDC) is a potent inhibitor of CSC aldehyde dehydrogenase and lowers glutathione (GSH) which aggravate iron-dependent ferroptosis. Herein, nanoformulations of DDC with green chemically synthesized ferrous oxide nanoparticles (FeO NPs) and ferric oxide (Fe₂O₃ NPs) were prepared. Due to nanoparticle characters and synergistic effect between iron oxide NPs and DDC, nanocomplexes (DFeO NPs and DFe₂O₃ NPs, respectively) exhibited the strongest anti-metastatic cancer potency in vitro. Because of corresponding iron oxide nature, DFeO NPs demonstrated better therapeutic efficacy than DFe₄O₃ NPs, in mammary tumor liver metastasis-bearing mice, in terms of tumor size, histological analysis, immunostaining % of ki-67⁺ and caspase 3⁺, and gene expression of p53 and BCl2. The potent anti-tumor effect of DFeO nanocomplex is attributed to the maximum elevation of reactive oxygen species and lipid peroxidation (ferroptosis hall marker) with severe depletion of GSH and Nrf2 selectively in both tumor tissues, causing CSC eradication with halting metastatic activity. The latters were confirmed by lowering CD44⁺ % and gene expression of HIF-α, β-catenin, Notch, ABCG2-mediated chemoresistance, and MMP9 with diminishing liver tumor marker. Moreover, this nanocomplex did not cause any abnormal alterations in histological and biochemical parameters, compared to healthy group. Therefore, the selective apoptotic and ferroptotic with anti-CSC effects of DFeO NPs open new safe avenue for metastatic tumor therapy.

Cancer Stem Cells and Circulatory Tumor Cells Promote Breast Cancer Metastasis

Breast cancer (BC) is a highly metastatic, pathological cancer that significantly affects women worldwide. The mortality rate of BC is related to its heterogeneity, aggressive phenotype, and metastasis. Recent studies have highlighted that the tumor microenvironment (TME) is critical for the interplay between metastasis mediators in BC. BC stem cells, tumor-derived exosomes, circulatory tumor cells (CTCs), and signaling pathways dynamically remodel the TME and promote metastasis. This review examines the cellular and molecular mechanisms governing the epithelial to mesenchymal transition (EMT) that facilitate metastasis. This review also discusses the role of cancer stem cells (CSCs), tumor-derived exosomes, and CTs in promoting BC metastasis. Furthermore, the review emphasizes major signaling pathways that mediate metastasis in BC. Finally, the interplay among CSCs, exosomes, and CTCs in mediating metastasis have been highlighted. Therefore, understanding the molecular cues that mediate the association of CSCs, exosomes, and CTCs in TME helps to optimize systemic therapy to target metastatic BC.

CircBCAR3 accelerates esophageal cancer tumorigenesis and metastasis via sponging miR-27a-3p

RATIONALE

Circular RNAs (circRNAs) have been demonstrated to contribute to esophageal cancer progression. CircBCAR3 (hsa_circ_0007624) is predicted to be differentially expressed in esophageal cancer by bioinformatics analysis. We investigated the oncogenic roles and biogenesis of circBCAR3 in esophageal carcinogenesis.

METHODS

Functions of circBCAR3 on cancer cell proliferation, migration, invasion, and ferroptosis were explored using the loss-of-function assays. A xenograft mouse model was used to reveal effects of circBCAR3 on xenograft growth and lung metastasis. The upstream and downstream mechanisms of circBCAR3 were investigated by bioinformatics analysis and confirmed by RNA immunoprecipitation and luciferase reporter assays. The dysregulated genes in hypoxia-induced esophageal cancer cells were identified using RNA-seq.

RESULTS

CircBCAR3 was highly expressed in esophageal cancer tissues and cells and its expression was increased by hypoxia in vitro. Silencing of circBCAR3 repressed the proliferation, migration, invasion, and ferroptosis of esophageal cancer cells in vitro, as well as inhibited the growth and metastasis of esophageal xenograft in mice in vivo. The hypoxia-induced promotive effects on esophageal cancer cell migration and ferroptosis were rescued by circBCAR3 knockdown. Mechanistically, circBCAR3 can interact with miR-27a-3p by the competitive endogenous RNA mechanism to upregulate transportin-1 (TNPO1). Furthermore, our investigation indicated that splicing factor quaking (QKI) is a positive regulator of circBCAR3 via targeting the introns flanking the hsa_circ_0007624-formed exons in BCAR3 pre-mRNA. Hypoxia upregulates E2F7 to transcriptionally activate QKI.

CONCLUSION

Our research demonstrated that splicing factor QKI promotes circBCAR3 biogenesis, which accelerates esophageal cancer tumorigenesis via binding with miR-27a-3p to upregulate TNPO1. These data suggested circBCAR3 as a potential target in the treatment of esophageal cancer. Hypoxia induces the upregulation of E2F7, which transcriptionally activates QKI in esophageal cancer cells. QKI increases the formation of circBCAR3 by juxtaposing the circularized exons. CircBCAR3 binds with miR-27a-3p to promote TNPO1 expression. CircBCAR3 promoted the proliferation, migration, invasion, and ferroptosis of esophageal cancer cells by miR-27a-3p.

Beyond Genetics: Metastasis as an Adaptive Response in Breast Cancer

Metastatic disease represents the primary cause of breast cancer (BC) mortality, yet it is still one of the most enigmatic processes in the biology of this tumor. Metastatic progression includes distinct phases: invasion, intravasation, hematogenous dissemination, extravasation and seeding at distant sites, micro-metastasis formation and metastatic outgrowth. Whole-genome sequencing analyses of primary BC and metastases revealed that BC metastatization is a non-genetically selected trait, rather the result of transcriptional and metabolic adaptation to the unfavorable microenvironmental conditions which cancer cells are exposed to (e.g., hypoxia, low nutrients, endoplasmic reticulum stress and chemotherapy administration). In this regard, the latest multi-omics analyses unveiled intra-tumor phenotypic heterogeneity, which determines the polyclonal nature of breast tumors and constitutes a challenge for clinicians, correlating with patient poor prognosis. The present work reviews BC classification and epidemiology, focusing on the impact of metastatic disease on patient prognosis and survival, while describing general principles and current in vitro/in vivo models of the BC metastatic cascade. The authors address here both genetic and phenotypic intrinsic heterogeneity of breast tumors, reporting the latest studies that support the role of the latter in metastatic spreading. Finally, the review illustrates the mechanisms underlying adaptive stress responses during BC metastatic progression.

Bladder cancer cell lines adapt their aggressiveness profile to oxygen tension

During the process of tumor growth, cancer cells will be subjected to intermittent hypoxia. This results from the delay in the development of the vascular network in relation to the proliferation of cancer cells. The hypoxic nature of a tumor has been demonstrated as a negative factor for patient survival. To evaluate the impact of hypoxia on the survival and migration properties of low and high-grade bladder cancer cell lines, two low-grade (MGHU-3 and SW-780) and two high-grade (SW-1710 and T24) bladder cancer cell lines were cultured in normoxic (20% O₂) or hypoxic atmospheric conditions (2% O₂). The response of bladder cancer cell lines to hypoxic atmospheric cell culture conditions was examined under several parameters, including epithelial-mesenchymal transition, doubling time and metabolic activities, thrombospondin-1 expression, whole Matrix Metallo-Proteinase activity, migration and resistance to oxidative stress. The low-grade cell line response to hypoxia was heterogeneous even if it tended to adopt a more aggressive profile. Hypoxia enhanced migration and pro-survival properties of MGHU-3 cells, whereas these features were reduced for the SW-780 cell line cultured under low oxygen tension. The responses of tested high-grade cell lines were more homogeneous and tended to adopt a less aggressive profile. Hypoxia drastically changed some of the bladder cancer cell line properties, for example matrix metalloproteinases expression for all cancer cells but also switch in glycolytic metabolism of low grade cancer cells. Overall, studying bladder cancer cells in hypoxic environments are relevant for the translation from in vitro findings to in vivo context.

Understanding autophagy role in cancer stem cell development

Cancer stem cells (CSCs) are a small subpopulation of immature cells located in the tumor mass. These cells are responsible for tumor development, proliferation, resistance and spreading. CSCs are characterized by three unique features: the ability to self-renew, differentiation and tumor formation. CSCs are similar to stem cells, but they differ in the malignant phenotype. CSCs become immortal and survive harsh environmental conditions such as hypoxia, starvation and oxidative stress. However, this harsh tumor microenvironment induces the activation of autophagy, which further increases the CSCs stemness profile, and all these features further increase tumorigenicity and metastasis capacity. Autophagy is induced by the extracellular and cellular microenvironment. Hypoxia is one of the most common factors that highly increases the activity of autophagy in CSCs. Therefore, hypoxia-induced autophagy and CSCs proliferation should be elucidated in order to find a novel cure to defeat cancer cells (CSCs and non-CSCs). The remaining challenges to close the gap between the laboratory bench and the development of therapies, to use autophagy against CSCs in patients, could be addressed by adopting a 3D platform to better-mimic the natural environment in which these cells reside. Ultimately allowing to obtain the blueprints for bioprocess scaling up and to develop the production pipeline for safe and cost-effective autophagy-based novel biologics.

Cucurbitacin B inhibits TGF-β1-induced epithelial-mesenchymal transition (EMT) in NSCLC through regulating ROS and PI3K/Akt/mTOR pathways

BACKGROUND

Lung cancer is the leading cause of cancer mortality worldwide, and most of the patients after treatment with EGF-TKIs develop drug resistance, which is closely correlated with EMT. Cucurbitacin B (CuB) is a natural product of the Chinese herb Cucurbitaceae plant, which has a favorable role in anti-inflammation and anti-cancer activities. However, the effect of CuB on EMT is still far from fully explored. In this study, the inhibition effect of CuB on EMT was investigated.

METHODS

In this study, TGF-β1 was used to induce EMT in A549 cells. MTS assay was used to detect the cell viability of CuB co-treated with TGF-β1. Wound healing assay and transwell assay were used to determine the migration and invasion capacity of cells. Flow cytometry and fluorescence microscope were used to detect the ROS level in cells. Western blotting assay and immunofluorescence assay were used to detect the proteins expression. Gefitinib was used to establish EGF-TKI resistant NSCLC cells. B16-F10 intravenous injection mice model was used to evaluate the effect of CuB on lung cancer metastasis in vivo. Caliper IVIS Lumina and HE staining were used to detect the lung cancer metastasis of mice.

RESULTS

In this study, the results indicated that CuB inhibited TGF-β1-induced EMT in A549 cells through reversing the cell morphology changes of EMT, increasing the protein expression of E-cadherin, decreasing the proteins expression of N-cadherin and Vimentin, suppressing the migration and invasion ability. CuB also decreased the ROS production and p-PI3K, p-Akt and p-mTOR expression in TGF-β1-induced EMT in A549 cells. Furthermore, Gefitinib resistant A549 cells (A549-GR) were well established, which has the EMT characteristics, and CuB could inhibit the EMT in A549-GR cells through ROS and PI3K/Akt/mTOR pathways. In vivo study showed that CuB inhibited the lung cancer metastasis effectively through intratracheal administration.

CONCLUSION

CuB inhibits EMT in TGF-β1-induced A549 cells and Gefitinib resistant A549 cells through decreasing ROS production and PI3K/Akt/mTOR signaling pathway. In vivo study validated that CuB inhibits lung cancer metastasis in mice. The study may be supporting CuB as a promising therapeutic agent for NSCLC and Gefitinib resistant NSCLC.

Antitumorigenic Effect of Tramadol and Synergistic Effect With Doxorubicin in Human Breast Cancer Cells

Background

Breast cancer in women is one of the leading causes of cancer mortality worldwide, and curative therapy is the main focus of clinical treatment. Anesthetic-analgesic techniques might alter stress responses and immunity and thereby influence outcomes in cancer patients. This study investigated the effect of tramadol on breast cancer progression and metastasis.

Methods

The effects of tramadol on two different subtypes of human breast adenocarcinoma cell lines, MDA-MB-231 and MCF-7, were studied with regard to cell growth, migration, colony formation and invasion and normoxic or hypoxic microenvironment for the expression of hypoxia-inducible factor-1α, reactive oxygen species, epithelial-mesenchymal transition related and cyclin-related proteins. The co-administration of tramadol and doxorubicin was studied to determine whether the effective doxorubicin dose might be reduced in combination with tramadol.

Results

The results showed that tramadol inhibited cell growth at concentrations more than 0.5 and more than 1.0 mg/mL in MDA-MB-231 and MCF-7 cells, respectively. Additionally, cell migration, colony formation and invasion were inhibited in a dose-dependent manner by tramadol in both cell lines. The combination of tramadol and doxorubicin induced synergistic effects in MDA-MD-231 cells and, with specific dosage combinations in MCF-7 cells.

Conclusions

Tramadol may regulate epithelial-mesenchymal transition and possess cytotoxic effects in breast cancer cells. Tramadol inhibits the progression of breast cancer cells and might be a candidate for combination therapy, especially for triple-negative breast cancer, and is a promising treatment strategy for breast cancer.

Targeting HIF-1α/NOTCH1 pathway eliminates CD44+ cancer stem-like cell phenotypes, malignancy, and resistance to therapy in head and neck squamous cell carcinoma

Poor prognosis of head and neck squamous cell carcinomas (HNSCCs) results from resistance to chemotherapy and radiotherapy. To uncover the drivers of HNSCC resistance, including stemness and hypoxia, in this study, we compared the gene expression between CD44+ and CD44- HNSCC cells and assessed the correlation of CD44 and hypoxia-inducible factor 1α (HIF-1α) expression with mouse features and outcomes of patients with HNSCC. We combined the knockdown or activation of HIF-1α with in vitro and in vivo assays to evaluate effects on stemness and resistance of HNSCC cells. Analysis of clinical data showed that activation of HIF-1α in CD44+ patients with HNSCC was correlated with worse prognosis. Functional assays showed that HIF-1α promoted stemness, resistance, and epithelial-mesenchymal transition in HNSCC CD44+ cells. HIF-1α activated NOTCH1 signaling in HNSCC stem-like cells characterized by CD44 expression. Moreover, inhibition of these signaling proteins using shRNA or Evofosfamide (Evo) development for cancer treatment, reversed chemoresistance in vitro and in vivo. Taken together, our results indicated that targeting HIF-1α attenuated NOTCH1-induced stemness, which regulates responses to chemotherapy or radiotherapy and malignancy in CD44+ HNSCCs. HIF-1α/NOTCH1 signaling may represent a target for HNSCC treatment.

Escape From Cisplatin-Induced Senescence of Hypoxic Lung Cancer Cells Can Be Overcome by Hydroxychloroquine

Chemotherapy is the commonly used treatment for advanced lung cancer. However, it produces side effects such as the development of chemoresistance. A possible responsible mechanism may be therapy-induced senescence (TIS). TIS cells display increased senescence-associated β-galactosidase (SA-β-gal) activity and irreversible growth arrest. However, recent data suggest that TIS cells can reactivate their proliferative potential and lead to cancer recurrence. Our previous study indicated that reactivation of proliferation by TIS cells might be related with autophagy modulation. However, exact relationship between both processes required further studies. Therefore, the aim of our study was to investigate the role of autophagy in the senescence-related chemoresistance of lung cancer cells. For this purpose, human and murine lung cancer cells were treated with two commonly used chemotherapeutics: cisplatin (CIS), which forms DNA adducts or docetaxel (DOC), a microtubule poison. Hypoxia, often overlooked in experimental settings, has been implicated as a mechanism responsible for a significant change in the response to treatment. Thus, cells were cultured under normoxic (~19% O₂) or hypoxic (1% O₂) conditions. Herein, we show that hypoxia increases resistance to CIS. Lung cancer cells cultured under hypoxic conditions escaped from CIS-induced senescence, displayed reduced SA-β-gal activity and a decreased percentage of cells in the G2/M phase of the cell cycle. In turn, hypoxia increased the proliferation of lung cancer cells and the proportion of cells proceeding to the G0/G1 phase. Further molecular analyses demonstrated that hypoxia inhibited the prosenescent p53/p21 signaling pathway and induced epithelial to mesenchymal transition in CIS-treated cancer cells. In cells treated with DOC, such effects were not observed. Of importance, pharmacological autophagy inhibitor, hydroxychloroquine (HCQ) was capable of overcoming short-term CIS-induced resistance of lung cancer cells in hypoxic conditions. Altogether, our data demonstrated that hypoxia favors cancer cell escape from CIS-induced senescence, what could be overcome by inhibition of autophagy with HCQ. Therefore, we propose that HCQ might be used to interfere with the ability of senescent cancer cells to repopulate following exposure to DNA-damaging agents. This effect, however, needs to be tested in a long-term perspective for preclinical and clinical applications.

Angiopoietin-Like Protein 4 and Insulin-Like Growth Factor-1 Expression in Invasive Breast Carcinoma in Young Women

Biomarker identification is imperative for invasive breast carcinoma, which is more aggressive and associated with higher mortality and worse prognosis in younger patients (<45 years) than in older patients (>50 years). The current study aimed to investigate angiopoietin-like protein 4 (ANGPTL4) and insulin-like growth factor-1 (IGF-1) protein expression in breast tissue from young patients with breast carcinoma. Immunohistochemical staining was applied in formalin-fixed, paraffin-embedded samples of breast carcinoma tissue from young patients aged <45 years at the time of diagnosis. Both proteins were expressed in the majority of cases. The highest frequency of positive ANGPTL4 and IGF-1 expression was observed in the luminal A subtype, whereas the HER2-overexpression subtype exhibited the lowest expression frequency for both proteins. There was no significant association between ANGPTL4 (p = 0.897) and IGF-1 (p = 0.091) expression and molecular subtypes of breast carcinoma. The histological grade was a significant predictor of ANGPTL4 expression (grade 1 vs. grade 3, adjusted odds ratio = 12.39, p = 0.040). Therefore, ANGPTL-4 and IGF-1 expressions are common in young breast carcinoma tissue. There is a potential use of them as biomarkers in breast carcinoma.

Aspects of the Epigenetic Regulation of EMT Related to Cancer Metastasis

Epithelial to mesenchymal transition (EMT) occurs during the pathological process associated with tumor progression and is considered to influence and promote the metastatic cascade. Characterized by loss of cell adhesion and apex base polarity, EMT enhances cell motility and metastasis. The key markers of the epithelial to mesenchymal transition are proteins characteristic of the epithelial phenotype, e.g., E-cadherin, cytokeratins, occludin, or desmoplakin, the concentration and activity of which are reduced during this process. On the other hand, as a result of acquiring the characteristics of mesenchymal cells, an increased amount of N-cadherin, vimentin, fibronectin, or vitronectin is observed. Importantly, epithelial cells undergo partial EMT where some of the cells show both epithelial and mesenchymal characteristics. The significant influence of epigenetic regulatory mechanisms is observed in the gene expression involved in EMT. Among the epigenetic modifications accompanying incorrect genetic reprogramming in cancer are changes in the level of DNA methylation within the CpG islands and posttranslational covalent changes of histone proteins. All observed modifications, which are stable but reversible changes, affect the level of gene expression leading to the development and progression of the disease, and consequently affect the uncontrolled growth of the population of cancer cells.

Traditional Chinese Medicine for adjuvant treatment of breast cancer: Taohong Siwu Decoction

The high incidence of breast cancer is the greastest threat to women' health all over the world. Among them, HER-2 positive breast cancer has the characteristics of high malignancy, easy recurrence and metastasis, and poor prognosis. Traditional Chinese medicine (TCM) has a rich theoretical basis and clinical application for breast cancer. TCM believes that blood stasis syndrome is one of the important pathogenesis of breast formation and development. Taohong Siwu Decoction (TSHWD) is based on the "First Prescription of Gynecology" Siwu Decoction. It is widely used in various blood stasis and blood deficiency syndromes, mainly in gynecological blood stasis. Clinical studies have found that THSWD can treat breast cancer by reducing blood vessel and lymphangiogenesis with auxiliary chemotherapy. In this study, we aim to explore the material basis and mechanism of THSWD in the treatment of HER-2 positive breast cancer through literature review and network pharmacology studies. Through a literature review of the traditional application, chemical composition of Chinese herbal medicine of THSWD, as well as its clinical reports and pharmacological research on breast cancer treatment. Meanwhile, we conducted "component-pathway-target" network through network pharmacology reveals the main material basis, possible targets and pathways of THSWD in inhibiting HER-2 positive breast cancer. Literature review and network pharmacology research results had predicted that, baicalein, kaempferol, caffeic acid, amygdalin, quercetin, ferulic acid, gallic acid, catalpol, hydroxysafflor yellow A, paeoniflorin in THSWD are the main effective chemical composition. THSWD regulates 386 protein targets and 166 pathways related to breast cancer. The molecular mechanism is mainly to improve the microenvironment of tumor cells, regulate the process of tumor cell EMT, and inhibit tumor cell proliferation and metastasis. This study revealed the mechanism of action of THSWD in the treatment of HER-2 positive breast cancer through literature review and network pharmacology studies, providing a scientific basis for clinical application.

Adipocyte-derived extracellular vesicles promote breast cancer cell malignancy through HIF-1α activity

Extracellular vesicles (EVs) are emerging key protagonists in intercellular communication between adipocytes and breast cancer (BC) cells. Here, we described a new mechanism by which EVs released by mature adipocytes promoted breast cancer cell malignancy "in vitro" and "in vivo". We found that adipocyte-derived EVs enhanced growth, motility and invasion, stem cell-like properties, as well as specific traits of epithelial-to-mesenchymal transition in both estrogen receptor positive and triple negative BC cells. Of note, adipocyte-derived EVs aid breast tumor cells in lung metastatic colonization after tail-vein injection in mice. These EV-mediated effects occur via the induction of HIF-1α activity, since they were abrogated by the use of the HIF-1α inhibitor KC7F2 or in cells silenced for HIF-1α expression. Moreover, using an "ex vivo" model of obese adipocytes we found that the depletion of EVs counteracted the ability of obese adipocytes to sustain pro-invasive phenotype in BC cells. Interestingly, EVs released by undifferentiated adipocytes failed to induce aggressiveness and HIF-1α expression. These findings shed new light on the role of adipocyte-derived EVs in breast cancer progression, suggesting the possibility to target HIF-1α activity to block the harmful adipocyte-tumor cell dialogue, especially in obese settings.

Study of Stem Cells Influence on Cardiac Cells Cultured with a Cyanide-P-Trifluoromethoxyphenylhydrazone in Organ-on-a-Chip System

Regenerative medicine and stem cells could prove to be an effective solution to the problem of treating heart failure caused by ischemic heart disease. However, further studies on the understanding of the processes which occur during the regeneration of damaged tissue are needed. Microfluidic systems, which provide conditions similar to in vivo, could be useful tools for the development of new therapies using stem cells. We investigated how mesenchymal stem cells (MSCs) affect the metabolic activity of cardiac cells (rat cardiomyoblasts and human cardiomyocytes) incubated with a potent uncoupler of mitochondrial oxidative phosphorylation under microfluidic conditions. A cyanide p-trifluoromethoxyphenylhydrazone (FCCP) was used to mimic disfunctions of mitochondria of cardiac cells. The study was performed in a microfluidic system integrated with nanofiber mats made of poly-l-lactid acid (PLLA) or polyurethane (PU). The microsystem geometry allows four different cell cultures to be conducted under different conditions (which we called: normal, abnormal-as both a mono- and co-culture). Metabolic activity of the cells, based on the bioluminescence assay, was assessed in the culture's performed in the microsystem. It was proved that stem cells increased metabolic activity of cardiac cells maintained with FCCP.

Sohlh2 alleviates malignancy of EOC cells under hypoxia via inhibiting the HIF1α/CA9 signaling pathway

Epithelial ovarian cancer (EOC) is the most common and deadly ovarian cancer. Most of the patients have abdominal/pelvic invasion and metastasis at the time of diagnosis, but the underlying mechanism remains unclear. Insufficiency of blood perfusion and diffusion within most solid tumors can lead to a hypoxic tumor microenvironment and promotes tumor malignancy. In the present study, we detected the role of the spermatogenesis- and oogenesis-specific basic helix-loop-helix (bHLH) transcription factor 2 (sohlh2) on migration, invasion and epithelial-mesenchymal transition (EMT) of EOC cell lines under hypoxia in vitro. We also investigated the possible mechanism underlying it. The results showed that sohlh2 inhibited the migration, invasion and EMT of EOC cells and might function through suppression of the hypoxia-inducible factor 1α (HIF1α)/carbonic anhydrase 9 (CA9) signaling pathway. Our results may open a new avenue for the further development of diagnostic tools and novel therapeutics that will benefit EOC patients.

hCINAP is potentially a direct target gene of HIF-1 and is required for hypoxia-induced EMT and apoptosis in cervical cancer cells

The early metastasis of cervical cancer is a multistep process requiring the cancer cells to adapt to the signal input from different tissue environments, including hypoxia. Hypoxia-induced epithelial-to-mesenchymal transition (EMT) plays a critical role in the ability to invade surrounding tissues. However, the molecular mechanisms underlying EMT in cervical cancer remain to be elucidated. Herein, we show that hypoxia-inducible factor-1alpha (HIF-1α) and aryl hydrocarbon receptor nuclear translocator (ARNT) are recruited to the human coilin-interacting nuclear ATPase protein (hCINAP) promoter and initiate hCINAP expression in hypoxia. Ablation of hCINAP decreased the migratory capacity and EMT of cervical cancer cells under hypoxic conditions. Furthermore, hCINAP regulated EMT through the Akt–mTOR signaling pathway, and inhibits hypoxia-induced p53-dependent apoptosis. Our data collectively show that hCINAP may have essential roles in the metastasis of cervical cancer and could be a potential target for curing cervical cancer.

Targeting cancer stem cells for reversing therapy resistance: mechanism, signaling, and prospective agents

Cancer stem cells (CSCs) show a self-renewal capacity and differentiation potential that contribute to tumor progression and therapy resistance. However, the underlying processes are still unclear. Elucidation of the key hallmarks and resistance mechanisms of CSCs may help improve patient outcomes and reduce relapse by altering therapeutic regimens. Here, we reviewed the identification of CSCs, the intrinsic and extrinsic mechanisms of therapy resistance in CSCs, the signaling pathways of CSCs that mediate treatment failure, and potential CSC-targeting agents in various tumors from the clinical perspective. Targeting the mechanisms and pathways described here might contribute to further drug discovery and therapy.

Self-Propelled and Near-Infrared-Phototaxic Photosynthetic Bacteria as Photothermal Agents for Hypoxia-Targeted Cancer Therapy

Hypoxia can increase the resistance of tumor cells to radiotherapy and chemotherapy. However, the dense extracellular matrix, high interstitial fluid pressure, and irregular blood supply often serve as physical barriers to inhibit penetration of drugs or nanodrugs across tumor blood microvessels into hypoxic regions. Therefore, it is of great significance and highly desirable to improve the efficiency of hypoxia-targeted therapy. In this work, living photosynthetic bacteria (PSB) are utilized as hypoxia-targeted carriers for hypoxic tumor therapy due to their near-infrared (NIR) chemotaxis and their physiological characteristics as facultative aerobes. More interestingly, we discovered that PSB can serve as a kind of photothermal agent to generate heat through nonradiative relaxation pathways due to their strong photoabsorption in the NIR region. Therefore, PSB integrate the properties of hypoxia targeting and photothermal therapeutic agents in an "all-in-one" manner, and no postmodification is needed to achieve hypoxia-targeted cancer therapy. Moreover, as natural bacteria, noncytotoxic PSB were found to enhance immune response that induced the infiltration of cytotoxicity T lymphocyte. Our results indicate PSB specifically accumulate in hypoxic tumor regions, and they show a high efficiency in the elimination of cancer cells. This proof of concept may provide a smart therapeutic system in the field of hypoxia-targeted photothermal therapeutic platforms.

Metabolic heterogeneity and immunocompetence of infiltrating immune cells in the breast cancer microenvironment (Review)

Breast cancer is one of the most common malignancies in women and is characterized by active immunogenicity. Immune cell infiltration plays an important role in the development of breast cancer. The degree of infiltration influences both the response to and effect of treatment. However, immune infiltration is a complex process. Differences in oxygen partial pressure, blood perfusion and nutrients in the tumor microenvironment (TME) suggest that infiltrating immune cells in different sites experience different microenvironments with corresponding changes in the metabolic mode, that is, immune cell metabolism is heterogenous in the TME. Furthermore, the present review found that lipid metabolism can support the immunosuppressive microenvironment in breast cancer based on a review of published literature. Research in this field is still ongoing; however, it is vital to understand the metabolic patterns and effects of different microenvironments for antitumor therapy. Therefore, this review discusses the metabolic responses of various immune cells to different microenvironments in breast cancer and provides potentially meaningful insights for tumor immunotherapy.

Involvement of the ERK/HIF-1α/EMT Pathway in XCL1-Induced Migration of MDA-MB-231 and SK-BR-3 Breast Cancer Cells

Chemokine–receptor interactions play multiple roles in cancer progression. It was reported that the overexpression of X-C motif chemokine receptor 1 (XCR1), a specific receptor for chemokine X-C motif chemokine ligand 1 (XCL1), stimulates the migration of MDA-MB-231 triple-negative breast cancer cells. However, the exact mechanisms of this process remain to be elucidated. Our study found that XCL1 treatment markedly enhanced MDA-MB-231 cell migration. Additionally, XCL1 treatment enhanced epithelial–mesenchymal transition (EMT) of MDA-MB-231 cells via E-cadherin downregulation and upregulation of N-cadherin and vimentin as well as increases in β-catenin nucleus translocation. Furthermore, XCL1 enhanced the expression of hypoxia-inducible factor-1α (HIF-1α) and phosphorylation of extracellular signal-regulated kinase (ERK) 1/2. Notably, the effects of XCL1 on cell migration and intracellular signaling were negated by knockdown of XCR1 using siRNA, confirming XCR1-mediated actions. Treating MDA-MB-231 cells with U0126, a specific mitogen-activated protein kinase kinase (MEK) 1/2 inhibitor, blocked XCL1-induced HIF-1α accumulation and cell migration. The effect of XCL1 on cell migration was also evaluated in ER^-/HER2⁺ SK-BR-3 cells. XCL1 also promoted cell migration, EMT induction, HIF-1α accumulation, and ERK phosphorylation in SK-BR-3 cells. While XCL1 did not exhibit any significant impact on the matrix metalloproteinase (MMP)-2 and -9 expressions in MDA-MB-231 cells, it increased the expression of these enzymes in SK-BR-3 cells. Collectively, our results demonstrate that activation of the ERK/HIF-1α/EMT pathway is involved in the XCL1-induced migration of both MDA-MB-231 and SK-BR-3 breast cancer cells. Based on our findings, the XCL1–XCR1 interaction and its associated signaling molecules may serve as specific targets for the prevention of breast cancer cell migration and metastasis.

A Novel Inhibitor of Carbonic Anhydrases Prevents Hypoxia-Induced TNBC Cell Plasticity

Cell plasticity is the ability that cells have to modify their phenotype, adapting to the environment. Cancer progression is under the strict control of the the tumor microenvironment that strongly determines its success by regulating the behavioral changes of tumor cells. The cross-talk between cancer and stromal cells and the interactions with the extracellular matrix, hypoxia and acidosis contribute to trigger a new tumor cell identity and to enhance tumor heterogeneity and metastatic spread. In highly aggressive triple-negative breast cancer, tumor cells show a significant capability to change their phenotype under the pressure of the hypoxic microenvironment. In this study, we investigated whether targeting the hypoxia-induced protein carbonic anhydrase IX (CA IX) could reduce triple-negative breast cancer (TNBC) cell phenotypic switching involved in processes associated with poor prognosis such as vascular mimicry (VM) and cancer stem cells (CSCs). The treatment of two TNBC cell lines (BT-549 and MDA-MB-231) with a specific CA IX siRNA or with a novel inhibitor of carbonic anhydrases (RC44) severely impaired their ability to form a vascular-like network and mammospheres and reduced their metastatic potential. In addition, the RC44 inhibitor was able to hamper the signal pathways involved in triggering VM and CSC formation. These results demonstrate that targeting hypoxia-induced cell plasticity through CA IX inhibition could be a new opportunity to selectively reduce VM and CSCs, thus improving the efficiency of existing therapies in TNBC.

Three dimensional engineered models to study hypoxia biology in breast cancer

Breast cancer is the second leading cause of mortality among women worldwide. Despite the available therapeutic regimes, variable treatment response is reported among different breast cancer subtypes. Recently, the effects of the tumor microenvironment on tumor progression as well as treatment responses have been widely recognized. Hypoxia and hypoxia inducible factors in the tumor microenvironment have long been known as major players in tumor progression and survival. However, the majority of our understanding of hypoxia biology has been derived from two dimensional (2D) models. Although many hypoxia-targeted therapies have elicited promising results in vitro and in vivo, these results have not been successfully translated into clinical trials. These limitations of 2D models underscore the need to develop and integrate three dimensional (3D) models that recapitulate the complex tumor-stroma interactions in vivo. This review summarizes role of hypoxia in various hallmarks of cancer progression. We then compare traditional 2D experimental systems with novel 3D tissue-engineered models giving accounts of different bioengineering platforms available to develop 3D models and how these 3D models are being exploited to understand the role of hypoxia in breast cancer progression.

Tumorigenesis and Progression As A Consequence of Hypoxic TME：A Prospective View upon Breast Cancer Therapeutic Targets

Intratumoral hypoxia has a significant impact on the development and progression of breast cancer (BC). Rather than exerting limited regional impact, hypoxia create an aggressive macroenvironment for BC. Hypoxia-inducible factors-1(HIF-1) is extensively induced under hypoxia condition of BC, activating the transcription of multiple oncogenes. Thereinto, CD73 is the one which could be secreted into the microenvironment and is in favor of the growth, metastasis, resistance to therapies, as well as the stemness maintenance of BC. In this review, we address the significance of hypoxia/HIF-1/CD73 axis for BC, and provide a novel perspective into BC therapeutic strategies.

The aegis: platelets as biomarkers of tumor progression

There is increasing awareness that platelets play a significant role in creating a hypercoagulable environment that mediates tumor progression, beyond their classical hemostatic function. Platelets have heterogenic responses to agonists, and differential release and uptake of bioactive molecules may be manipulated via reciprocal cross-talk with cells of the tumor microenvironment. Platelets thus promote tumor progression by enhancing tumor growth, promoting the development of tumor-associated vasculature and encouraging invasion. In the metastatic process, platelets form the shield that protects tumor cells from high-velocity forces and immunosurveillance, while ensuring the establishment of the pre-metastatic niche. This review presents the complexity of these concepts, considering platelets as biomarkers for diagnosis, prognosis and potentially as therapeutic targets in cancer.

miRNAs 484 and 210 regulate Pax-5 expression and function in breast cancer cells

Recent studies have enabled the identification of important factors regulating cancer progression, such as paired box gene 5 (Pax-5). This transcription factor has consistently been associated to B-cell cancer lesions and more recently solid tumors including breast carcinoma. Although Pax-5 downstream activity is relatively well characterized, aberrant Pax-5 expression in a cancer-specific context is poorly understood. To investigate the regulation of Pax-5 expression, we turned to micro RNAs (miRNAs), small non-coding RNA molecules that regulate key biological processes. Extensive studies show that miRNA deregulation is prevalent in cancer lesions. In this study, we aim to elucidate a causal link between differentially expressed miRNAs in cancer cells and their putative targeting of Pax-5-dependent cancer processes. Bioinformatic prediction tools indicate that miRNAs 484 and 210 are aberrantly expressed in breast cancer and predicted to target Pax-5 messenger RNA (mRNA). Through conditional modulation of these miRNAs in breast cancer cells, we demonstrate that miRNAs 484 and 210 inhibit Pax-5 expression and regulate Pax-5-associated cancer processes. In validation, we show that these effects are probably caused by direct miRNA/mRNA interaction, which are reversible by Pax-5 recombinant expression. Interestingly, miRNAs 484 and 210, which are both overexpressed in clinical tumor samples, are also modulated during epithelial-mesenchymal transitioning and hypoxia that correlate inversely to Pax-5 expression. This is the first study demonstrating the regulation of Pax-5 expression and function by non-coding RNAs. These findings will help us better understand Pax-5 aberrant expression within cancer cells, creating the possibility for more efficient diagnosis and treatments for cancer patients.

HIF-1α, TWIST-1 and ITGB-1, associated with Tumor Stiffness, as Novel Predictive Markers for the Pathological Response to Neoadjuvant Chemotherapy in Breast Cancer

Purpose

To investigate the relationship between hypoxia-inducible factor 1-alpha (HIF-1α), Twist family BHLH transcription factor 1 (TWIST-1), and β1 integrin (ITGB-1) expression and tumor stiffness, and evaluate performance of HIF-1α, TWIST-1, and ITGB-1 alone and in combination with Ki-67 for predicting pathological responses to neoadjuvant chemotherapy (NACT) in breast cancer (BC).

Patients and Methods

This was a prospective cohort study of 104 BC patients receiving NACT. Tumor stiffness and oxygen score (OS) were evaluated before NACT by shear-wave elastography and optical imaging; HIF-1α, TWIST-1, ITGB-1, and Ki-67 expression were quantitatively assessed by immunohistochemistry of paraffin-embedded tumor samples obtained by core needle biopsy. Indexes were compared among different residual cancer burden (RCB) groups, and associations of HIF-1α, TWIST-1, ITGB-1, and Ki-67 with tumor stiffness and OS were examined. The value of HIF-1α, TWIST-1, ITGB-1, and Ki-67, and a possible new combined index (predRCB) for predicting NACT responses was assessed by receiver operating characteristic (ROC) curves.

Results

HIF-1α, TWIST-1, and ITGB-1 expression were positively correlated with tumor stiffness and negatively with OS. Area under the ROC curves (AUCs) measuring the performance of HIF-1α, TWIST-1, ITGB-1, and Ki-67 for predicting responses to NACT were 0.81, 0.85, 0.79, and 0.80 for favorable responses, and 0.83, 0.86, 0.84, and 0.85 for resistant responses, respectively. PredRCB showed better prediction than the other individual indexes for favorable responses (AUC = 0.88) and resistant responses (AUC = 0.92).

Conclusion

HIF-1α, TWIST-1, ITGB-1, and Ki-67 performed well in predicting favorable responses and resistance to NACT, and predRCB improved the predictive power of the individual indexes. These results support individualized treatment of BC patients receiving NACT.

Hypoxia modulates stem cell properties and induces EMT through N-glycosylation of EpCAM in breast cancer cells

Epithelial cell adhesion molecule (EpCAM), which is a transmembrane glycoprotein, is related to tumor progression. We demonstrated that EpCAM plays important roles in proliferation, apoptosis, and metastasis during breast cancer (BC) progression. But the role of N-glycosylation in EpCAM in tumor aggressiveness is not clear. Here, we evaluated the role of N-glycosylation of EpCAM in stemness and epithelial-mesenchymal transition (EMT) characteristics. EpCAM overexpression increases the expression of stemness markers (NANOG，SOX2, and OCT4) and EMT markers (N-cadherin and vimentin) under the condition of hypoxia in BC. Knockdown of EpCAM and mutation of N-glycosylation of EpCAM maintained in severe hypoxia lead to a significant reduction of stemness/EMT markers. In addition, we found that N-glycosylation of EpCAM is a crucial factor during this process. This demonstrates that EpCAM has a novel regulatory role in stemness/EMT dependence of hypoxia-inducible factor 1-alpha via regulating nuclear factor kappa B in BC cells. Hence, our study reveals EpCAM glycosylation modification as a new regulator of stemness/EMT under hypoxic in BC and points out EpCAM as a potential therapeutic target.

Knockdown of circDENND4C inhibits glycolysis, migration and invasion by up-regulating miR-200b/c in breast cancer under hypoxia

Background

Hypoxia is a key feature of breast cancer, which affects cancer development, metastasis and metabolism. Previous studies suggested that circular RNAs (circRNAs) could participate in cancer progression and hypoxia regulation. This study aimed to investigate the role of circRNA differentially expressed in normal cells and neoplasia domain containing 4C (circDENND4C) in breast cancer progression under hypoxia.

Methods

Forty-three patients with breast cancer were involved in this study. Breast cancer cell lines MDA-MB-453 and SK-BR-3 were cultured under hypoxia (1% O₂) for experiments in vitro. The expression levels of circDENND4C, microRNA-200b (miR-200b) and miR-200c were measured by quantitative real-time polymerase chain reaction. Glycolysis was investigated by glucose consumption, lactate production and hexokinase II (HK2) protein level. Migration and invasion were evaluated via trans-well assay and protein levels of matrix metallopeptidase 9 (MMP9) and MMP2. The interaction between circDENND4C and miR-200b or miR-200c was explored by bioinformatics analysis, luciferase assay and RNA immunoprecipitation. Murine xenograft model was established to investigate the anti-cancer role of circDENND4C in vivo.

Results

circDENND4C highly expressed in breast cancer was up-regulated in response to hypoxia. Knockdown of circDENND4C decreased glycolysis, migration and invasion in breast cancer cells under hypoxia. circDENND4C was validated as a sponge of miR-200b and miR-200c. Deficiency of miR-200b or miR-200c reversed the suppressive effect of circDENND4C knockdown on breast cancer progression. Moreover, silence of circDENND4C reduced xenograft tumor growth by increasing miR-200b and miR-200c.

Conclusion

circDENND4C silence suppresses glycolysis, migration and invasion in breast cancer cells under hypoxia by increasing miR-200b and miR-200c.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1398-2) contains supplementary material, which is available to authorized users.

Friend or foe: Multiple roles of adipose tissue in cancer formation and progression

Obesity is well-known as the second factor for tumorigenesis after smoking and is bound up with the malignant progression of several kinds of cancers, including esophageal cancer, liver cancer, colorectal cancer, kidney cancer, and ovarian cancer. The increased morbidity and mortality of obesity-related cancer are mostly attributed to dysfunctional adipose tissue. The possible mechanisms connecting dysfunctional adipose tissue to high cancer risk mainly focus on chronic inflammation, obesity-related microenvironment, adipokine secretion disorder, and browning of adipose tissue, and so forth. The stromal vascular cells in adipose tissue trigger chronic inflammation through secreting inflammatory factors and promote cancer cell proliferation. Hypertrophic adipose tissues lead to metabolic disorders of adipocytes, such as abnormal levels of adipokines that mediate cancer progression and metastasis. Cancer patients often show adipose tissue browning and cancerous cachexia in an advanced stage, which lead to unsatisfied chemotherapy effect and poor prognosis. However, increasing evidence has shown that adipose tissue may display quite opposite effects in cancer development. Therefore, the interaction between cancers and adipose tissue exert a vital role in mediates adipose tissue dysfunction and further leads to cancer progression. In conclusion, targeting the dysfunction of adipose tissue provides a promising strategy for cancer prevention and therapy.

Extracellular Acidosis Modulates the Expression of Epithelial-Mesenchymal Transition (EMT) Markers and Adhesion of Epithelial and Tumor Cells

Epithelial-to-mesenchymal transition (EMT) is an important process of tumor progression associated with increased metastatic potential. EMT can be activated by external triggers such as cytokines or metabolic parameters (e.g. hypoxia). Since extracellular acidosis is a common finding in tumors, the aim of the study is to analyze its impact on the expression of EMT markers in vitro and in vivo as well as the functional impact on cell adhesion. Therefore, three tumor and two normal epithelial cell lines were incubated for 24 h at pH 6.6 and the expression of EMT markers was studied. In addition, mRNA expression of transcription and metabolic factors related to EMT was measured as well as the functional impact on cell adhesion, either during acidic incubation or after priming cells in an acidic milieu. E-cadherin and N-cadherin were down-regulated in all tumor and normal cell lines studied, whereas vimentin expression increased in only two tumor and one normal cell line. Down-regulation of the cadherins was seen in total protein and to a lesser extent in surface protein. In vivo an increase in N-cadherin and vimentin expression was found. Acidosis up-regulated Twist1 and Acsl1 but down-regulated fumarate hydratase (Fh). Cell adhesion during acidic incubation decreased in AT1 prostate carcinoma cells whereas preceding acidic priming increased their subsequent adhesion. Low tumor pH is able to modulate the expression EMT-related proteins and by this may affect the stability of the tissue structure.

miR-31 shuttled by halofuginone-induced exosomes suppresses MFC-7 cell proliferation by modulating the HDAC2/cell cycle signaling axis

Traditional Chinese medicine (TCM) are both historically important therapeutic agents and important source of new drugs. Halofuginone (HF), a small molecule alkaloid derived from febrifugine, has been shown to exert strong antiproliferative effects that differ markedly among various cell lines. However, whether HF inhibits MCF-7 cell growth in vitro and underlying mechanisms of this process are not yet clear. Here, we offer the strong evidence of the connection between HF treatment, exosome production and proliferation of MCF-7 cells. Our results showed that HF inhibits MCF-7 cell growth in both time- and dose-dependent manner. Further microRNA (miRNA) profiles analysis in HF treated and nontreated MCF-7 cell and exosomes observed that six miRNAs are particularly abundant and sorted in exosomes. miRNAs knockdown experiment in exosomes and the MCF-7 growth inhibition assay showed that exosomal microRNA-31 (miR-31) modulates MCF-7 cells growth by specially targeting the histone deacetylase 2 (HDAC2), which increases the levels of cyclin-dependent kinases 2 (CDK2) and cyclin D1 and suppresses the expression of p21. In conclusion, these data indicate that inhibition of exosome production reduces exosomal miR-31, which targets the HDAC2 and further regulates the level of cell cycle regulatory proteins, contributing to the anticancer functions of HF. Our data suggest a new role for HF and the exosome production in tumorigenesis and may provide novel insights into prevention and treatment of breast cancer.

Downregulation of RGMA by HIF-1A/miR-210-3p axis promotes cell proliferation in oral squamous cell carcinoma

Repulsive guidance molecules comprise a group of proteins that play an important role in carcinogenesis through interactions with their receptors, but their function in oral squamous cell carcinoma (OSCC) is unclear. Here, we investigated the potential role of the RGM family members in oral cancer pathogenesis. Our study showed that only RGMA was significantly downregulated in the OSCC tissues analyzed by TCGA and validated this finding in OSCC cells. The decreased expression of RGMA was strongly associated with the T stage and with poor prognosis. The ectopic expression of RGMA significantly inhibited the proliferation of OSCC cells both in vitro and in vivo. Moreover, we confirmed that RGMA was a target of miR-210-3p in OSCC and miR-210-3p overexpression contributed to the acceleration of OSCC growth. Further experiments revealed that HIF1A specifically interacted with the promoter of miR-210-3p and enhanced its expression. In summary, our research indicates that RGMA is regulated by the HIF1A/miR-210-3p axis and inhibits OSCC cell proliferation; thus, in the future, the development of therapies that target the HIF1A/miR-210-3p/RGMA axis may aid in the treatment of aggressive cancers.

Hypoxia-inducible factor 1-alpha expression correlates with response to neoadjuvant chemotherapy in women with breast cancer

Hypoxia-inducible factor 1-alpha (HIF-1a) has been shown to contribute to resistance to chemotherapy in breast cancer. The purpose of this study was to investigate whether HIF-1a is predictive for pathological response and the prognostic value of HIF-1a in local advanced breast undergoing neoadjuvant chemotherapy.Two hundred twenty patients with none-metastatic locally advanced invasive breast cancer (stages II-III) that subsequently received neoadjuvant chemotherapy were included in an observational study to assess the HIF-1a protein expression by immunohistochemistry. Associations between HIF-1a expression and pathological complete response (pCR) were analyzed using univariate and multivariate analysis. Independent prognostic factors for RFS were identified by multivariate Cox's proportional hazard analysis. A P value < .05 was considered to be statistically significant.The median age was 46 years, Luminal A, Luminal B, HER2-positive, and triple-negative accounted for 3.6%, 57.7%, 7.0% and 16.0%, respectively. A total of 41 patients (18.6%) achieved a pCR after neoadjuvant chemotherapy in the present study. HIF-1α negative patients had a significantly higher pCR rate than HIF-1α positive patients (P = .027). Multivariate analysis demonstrated that HIF-1α negative expression is an independent favorable predictor of pCR. Multivariate Cox regression analysis demonstrated that the HIF-1a expression before NCT showed an independent prognostic value for RFS (HR = 4.168, 95% CI: 1.012-17.170, P = .048).HIF-1a expression correlates with pCR in breast cancer undergoing neoadjuvant chemotherapy. Absent expression of HIF-1a was associated with a better pathological response and could indicate a favorable prognosis in non-pCR breast cancer patients.

Silencing the autophagy-specific gene Beclin-1 contributes to attenuated hypoxia-induced vasculogenic mimicry formation in glioma

OBJECTIVE

To explore the influence of Beclin-1 on vasculogenic mimicry (VM) induced by hypoxia in glioma.

METHODS

CD34-PAS staining was carried out to observe VM formation, and immunohistochemistry was used to determine the expression levels of Beclin-1, HIF-1α, VEGF and MMP2 in 105 patients with primary glioma. Human glioma U87MG cells were divided into Normoxia, Hypoxia, Hypoxia + NC siRNA and Hypoxia + Beclin-1 siRNA groups. Cobalt chloride (CoCl2) was used to stimulate hypoxic conditions, and a VM tube formation assay was used to detect VM formation. Wound healing and Transwell invasion assays were used to detect the invasive and migratory abilities of U87MG cells, respectively. Fluorescent LC3 puncta analysis was performed to examine the status of autophagic flux. Expression levels of Beclin-1 and VM-related molecules were determined using real-time quantitative-polymerase chain reaction (RT-qPCR) and western blotting.

RESULTS

There were 34 VM-positive cases and 71 VM-negative cases among 105 glioma patients, and VM formation was correlated with pathological grade and the expression of Beclin-1, HIF-1α, VEGF and MMP2. Positive relations were found between Beclin-1 and the expression of HIF-1α, VEGF and MMP2. Under hypoxic conditions, significant increases in the total length of tubes, migration rate, invasion cell number and expression of VM-related molecules were found in U87MG cells. Silencing Beclin-1 markedly decreased hypoxia-induced VM formation and the invasive and migratory abilities, together with the expression of VM-related molecules, in U87MG cells and significantly inhibited the autophagic flux.

CONCLUSION

Silencing Beclin-1 can attenuate hypoxia-induced VM formation and the metastatic ability of U87MG cells and is a potential target for VM inhibition in glioma.