Role of hypoxia-inducible factors in breast cancer metastasis

The application of immune checkpoint blockade in breast cancer and the emerging role of nanoparticle

Breast cancer is the most common malignancy in the female population with a high mortality rate. Despite the satisfying depth of studies evaluating the contributory role of immune checkpoints in this malignancy, few articles have reviewed the pros and cons of immune checkpoint blockades (ICBs). In the current review, we provide an overview of immune-related inhibitory molecules and also discuss the original data obtained from international research laboratories on the aberrant expression of T and non-T cell-associated immune checkpoints in breast cancer. Then, we especially focus on recent studies that utilized ICBs as the treatment strategy in breast cancer and provide their efficiency reports. As there are always costs and benefits, we discuss the limitations and challenges toward ICB therapy such as adverse events and drug resistance. In the last section, we allocate an overview of the recent data concerning the application of nanoparticle systems for cancer immunotherapy and propose that nano-based ICB approaches may overcome the challenges related to ICB therapy in breast cancer. In conclusion, it seems it is time for nanoscience to more rapidly move forward into clinical trials and illuminates the breast cancer treatment area with its potent features for the target delivery of ICBs.

Total synthesis and biological evaluation of 7-hydroxyneolamellarin A as hypoxia-inducible factor-1α inhibitor for cancer therapy

7-Hydroxyneolamellarin A (7-OH-Neo A, 1), a natural marine product derived from sponge Dendrilla nigra, was first synthesized with 10% overall yield under the instruction of convergent synthetic strategy. We found that 7-OH-Neo A could attenuate the accumulation of hypoxia-inducible factor-1α (HIF-1α) protein and inhibit vascular epidermal growth factor (VEGF) transcriptional activity, showing well inhibitory effect on HIF-1 signaling pathway. Meantime, 7-OH-Neo A had the well anti-tumor activities, such as inhibiting tumor angiogenesis, proliferation, migration and invasion. More importantly, 7-OH-Neo A exhibited profound anti-tumor effect in mice breast cancer model by suppressing the accumulation of HIF-1α in tumor tissue. Mechanism study demonstrated that 7-OH-Neo A might target the protein with the ability of stabilizing HIF-1α in hypoxia. Due to the excellent water solubility, superior anti-tumor activity and good biocompatibility, 7-OH-Neo A shows the promising potential for being exploited as an anti-tumor agent in near future.

Quantitative Longitudinal Imaging Reveals that Inhibiting Hedgehog Activity Alleviates the Hypoxic Tumor Landscape

Metastases account for the majority of mortalities related to breast cancer. The onset and sustained presence of hypoxia strongly correlates with increased incidence of metastasis and unfavorable prognosis in patients with breast cancer. The Hedgehog (Hh) signaling pathway is dysregulated in breast cancer, and its abnormal activity enables tumor progression and metastasis. In addition to programming tumor cell behavior, Hh activity enables tumor cells to craft a metastasis-conducive microenvironment. Hypoxia is a prominent feature of growing tumors that impacts multiple signaling circuits that converge upon malignant progression. We investigated the role of Hh activity in crafting a hypoxic environment of breast cancer. We used radioactive tracer [¹⁸F]-fluoromisonidazole (FMISO) positron emission tomography (PET) to image tumor hypoxia. We show that tumors competent for Hh activity are able to establish a hypoxic milieu; pharmacologic inhibition of Hh signaling in a syngeneic mammary tumor model mitigates tumor hypoxia. Furthermore, in hypoxia, Hh activity is robustly activated in tumor cells and institutes increased HIF signaling in a VHL-dependent manner. The findings establish a novel perspective on Hh activity in crafting a hypoxic tumor landscape and molecularly navigating the tumor cells to adapt to hypoxic conditions. IMPLICATIONS: Importantly, we present a translational strategy of utilizing longitudinal hypoxia imaging to measure the efficacy of vismodegib in a preclinical model of triple-negative breast cancer.

A persistent invasive phenotype in post-hypoxic tumor cells is revealed by fate mapping and computational modeling

Hypoxia is a critical factor in solid tumors that has been associated with cancer progression and aggressiveness. We recently developed a hypoxia fate mapping system to trace post-hypoxic cells within a tumor for the first time. This approach uses an oxygen-dependent fluorescent switch and allowed us to measure key biological features such as oxygen distribution, cell proliferation, and migration. We developed a computational model to investigate the motility and phenotypic persistence of hypoxic and post-hypoxic cells during tumor progression. The cellular behavior was defined by phenotypic persistence time, cell movement bias, and the fraction of cells that respond to an enhanced migratory stimulus. This work combined advanced cell tracking and imaging techniques with mathematical modeling, to reveal that a persistent invasive migratory phenotype that develops under hypoxia is required for cellular escape into the surrounding tissue, promoting the formation of invasive structures (“plumes”) that expand toward the oxygenated tumor regions.

•

A fluorescent fate mapping system allows tracking of hypoxic and post-hypoxic cells

•

Computational modeling predicts the formation of post-hypoxic invasive plumes

•

Simulations show post-hypoxic cells must maintain persistant migration to form plumes

•

Tracking cells exposed to intratumoral hypoxia confirms persistent migration

Proteomics and its applications in breast cancer

Breast cancer is an individually unique, multi-faceted and chameleonic disease, an eternal challenge for the new era of high-integrated precision diagnostic and personalized oncomedicine. Besides traditional single-omics fields (such as genomics, epigenomics, transcriptomics and metabolomics) and multi-omics contributions (proteogenomics, proteotranscriptomics or reproductomics), several new "-omics" approaches and exciting proteomics subfields are contributing to basic and advanced understanding of these "multiple diseases termed breast cancer": phenomics/cellomics, connectomics and interactomics, secretomics, matrisomics, exosomics, angiomics, chaperomics and epichaperomics, phosphoproteomics, ubiquitinomics, metalloproteomics, terminomics, degradomics and metadegradomics, adhesomics, stressomics, microbiomics, immunomics, salivaomics, materiomics and other biomics. Throughout the extremely complex neoplastic process, a Breast Cancer Cell Continuum Concept (BCCCC) has been modeled in this review as a spatio-temporal and holistic approach, as long as the breast cancer represents a complex cascade comprising successively integrated populations of heterogeneous tumor and cancer-associated cells, that reflect the carcinoma's progression from a "driving mutation" and formation of the breast primary tumor, toward the distant secondary tumors in different tissues and organs, via circulating tumor cell populations. This BCCCC is widely sustained by a Breast Cancer Proteomic Continuum Concept (BCPCC), where each phenotype of neoplastic and tumor-associated cells is characterized by a changing and adaptive proteomic profile detected in solid and liquid minimal invasive biopsies by complex proteomics approaches. Such a profile is created, beginning with the proteomic landscape of different neoplastic cell populations and cancer-associated cells, followed by subsequent analysis of protein biomarkers involved in epithelial-mesenchymal transition and intravasation, circulating tumor cell proteomics, and, finally, by protein biomarkers that highlight the extravasation and distant metastatic invasion. Proteomics technologies are producing important data in breast cancer diagnostic, prognostic, and predictive biomarkers discovery and validation, are detecting genetic aberrations at the proteome level, describing functional and regulatory pathways and emphasizing specific protein and peptide profiles in human tissues, biological fluids, cell lines and animal models. Also, proteomics can identify different breast cancer subtypes and specific protein and proteoform expression, can assess the efficacy of cancer therapies at cellular and tissular level and can even identify new therapeutic target proteins in clinical studies.

Review: Nanomaterials for Reactive Oxygen Species Detection and Monitoring in Biological Environments

Reactive oxygen species (ROS) and dissolved oxygen play key roles across many biological processes, and fluorescent stains and dyes are the primary tools used to quantify these species in vitro. However, spatio-temporal monitoring of ROS and dissolved oxygen in biological systems are challenging due to issues including poor photostability, lack of reversibility, and rapid off-site diffusion. In particular, ROS monitoring is hindered by the short lifetime of ROS molecules and their low abundance. The combination of nanomaterials and fluorescent detection has led to new opportunities for development of imaging probes, sensors, and theranostic products, because the scaffolds lead to improved optical properties, tuneable interactions with cells and media, and ratiometric sensing robust to environmental drift. In this review, we aim to critically assess and highlight recent development in nanosensors and nanomaterials used for the detection of oxygen and ROS in biological systems, and their future potential use as diagnosis tools.

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.

Differential effects of HIF2α antagonist and HIF2α silencing in renal cancer and sensitivity to repurposed drugs

BACKGROUND

In clear cell renal cell carcinoma, 80% of cases have biallelic inactivation of the VHL gene, leading to constitutive activation of both HIF1α and HIF2α. As HIF2α is the driver of the disease promoting tumour growth and metastasis, drugs targeting HIF2α have been developed. However, resistance is common, therefore new therapies are needed.

METHODS

We assessed the effect of the HIF2α antagonist PT2385 in several steps of tumour development and performed RNAseq to identify genes differentially expressed upon treatment. A drug screening was used to identify drugs with antiproliferative effects on VHL-mutated HIF2α-expressing cells and could increase effectiveness of PT2385.

RESULTS

PT2385 did not reduce cell proliferation or clonogenicity but, in contrast to the genetic silencing of HIF2α, it reduced in vitro cell invasion. Many HIF-inducible genes were down-regulated upon PT2385 treatment, whereas some genes involved in cell migration or extracellular matrix were up-regulated. HIF2α was associated with resistance to statins, addition to PT2385 did not increase the sensitivity.

CONCLUSIONS

this study shows key differences between inhibiting a target versus knockdown, which are potentially targetable.

Metastatic Breast Cancer, Organotropism and Therapeutics: A Review

The final stage of breast cancer involves spreading breast cancer cells to the vital organs like the brain, liver lungs and bones in the process called metastasis. Once the target organ is overtaken by the metastatic breast cancer cells, its usual function is compromised causing organ dysfunction and death. Despite the significant research on breast cancer metastasis, it's still the main culprit of breast cancer-related deaths. Exploring the complex molecular pathways associated with the initiation and progression of breast cancer metastasis could lead to the discovery of more effective ways of treating the devastating phenomenon. The present review article highlights the recent advances to understand the complexity associated with breast cancer metastases, organotropism and therapeutic advances.

Anticancer Potential of Aguerin B, a Sesquiterpene Lactone Isolated from Centaurea behen in Metastatic Breast Cancer Cells

BACKGROUND

Breast carcinoma is a malignant disease that represents the most common non-skin malignancy and a chief reason of cancer death in women. Large interest is growing in the use of natural products for cancer treatment, especially with goal of suppression angiogenesis, tumor cell growth, motility, as well as invasion and metastasis with low/no toxicity. It is evident from recent patents on the anticancer properties of sesquiterpene lactones such as parthenolide.

OBJECTIVE

In this study, using MDA-MB-231 cells of a human breast adenocarcinoma, the effects of aguerin B, as a natural sesquiterpene lactone, has been evaluated, in terms of the expression of metastatic-related genes (Pak-1, Rac-1 and HIF-1α).

METHODS

Cytotoxicity of aguerin B was tested toward MDA-MB-231 breast tumor cells using MTT. Scratch assay was accomplished to evaluate the tumor cell invasion. To understand the underlying molecular basis, the mRNA expressions were evaluated by real time PCR.

RESULTS

It was found that aguerin B significantly inhibited human breast cancer cell growth in vitro (IC50 = 2μg/mL) and this effect was accompanied with a persuasive suppression on metastasis. Our results showed that aguerin B in IC50 concentration down-regulated Rac-1, Pak-1, Hif-1α and Zeb-1 transcriptional levels.

CONCLUSION

Taken together, this study demonstrated that aguerin B possessed potential anti-metastatic effect, suggesting that it may consider as a potential multi target bio compound for treatment of breast metastatic carcinoma.

The genomic architecture of metastasis in breast cancer: focus on mechanistic aspects, signalling pathways and therapeutic strategies

Breast cancer is a multifactorial, heterogeneous disease and the second most frequent cancer amongst women worldwide. Metastasis is one of the most leading causes of death in these patients. Early-stage or locally advanced breast cancer is limited to the breast or nearby lymph nodes. When breast cancer spreads to farther tissues/organs from its original site, it is referred to as metastatic or stage IV breast cancer. Normal breast development is regulated by specific genes and signalling pathways controlling cell proliferation, cell death, cell differentiation and cell motility. Dysregulation of genes involved in various signalling pathways not only leads to the formation of primary tumour but also to the metastasis as well. The metastatic cascade is represented by a multi-step process including invasion of the local tumour cell followed by its entry into the vasculature, exit of malignant cells from the circulation and ultimately their colonization at the distant sites. These stages are referred to as formation of primary tumour, angiogenesis, invasion, intravasation and extravasation, respectively. The major sites of metastasis of breast cancer are the lymph nodes, bone, brain and lung. Only about 28% five-year survival rate has been reported for stage IV breast cancer. Metastasis is a serious concern for breast cancer and therefore, various therapeutic strategies such as tyrosine kinase inhibitors have been developed to target specific dysregulated genes and various signalling pathways involved in different steps of metastasis. In addition, other therapies like hyperbaric oxygen therapy, RNA interference and CRISPR/Cas9 are also being explored as novel strategies to cure the stage IV/metastatic breast cancer. Therefore, the current review has been compiled with an aim to evaluate the genetic basis of stage IV breast cancer with a focus on the molecular mechanisms. In addition, the therapeutic strategies targeting these dysregulated genes involved in various signalling pathways have also been discussed. Genome editing technologies that can target specific genes in the affected areas by making knock-in and knock-out alternations and thereby bring significant treatment outcomes in breast cancer have also been summarized.

The prognostic outcome of 'type 2 diabetes mellitus and breast cancer' association pivots on hypoxia-hyperglycemia axis

Type 2 diabetes mellitus and breast cancer are complex, chronic, heterogeneous, and multi-factorial diseases; with common risk factors including but not limited to diet, obesity, and age. They also share mutually inclusive phenotypic features such as the metabolic deregulations resulting from hyperglycemia, hypoxic conditions and hormonal imbalances. Although, the association between diabetes and cancer has long been speculated; however, the exact molecular nature of this link remains to be fully elucidated. Both the diseases are leading causes of death worldwide and a causal relationship between the two if not addressed, may translate into a major global health concern. Previous studies have hypothesized hyperglycemia, hyperinsulinemia, hormonal imbalances and chronic inflammation, as some of the possible grounds for explaining how diabetes may lead to cancer initiation, yet further research still needs to be done to validate these proposed mechanisms. At the crux of this dilemma, hyperglycemia and hypoxia are two intimately related states involving an intricate level of crosstalk and hypoxia inducible factor 1, at the center of this, plays a key role in mediating an aggressive disease state, particularly in solid tumors such as breast cancer. Subsequently, elucidating the role of HIF1 in establishing the diabetes-breast cancer link on hypoxia-hyperglycemia axis may not only provide an insight into the molecular mechanisms underlying the association but also, illuminate on the prognostic outcome of the therapeutic targeting of HIF1 signaling in diabetic patients with breast cancer or vice versa. Hence, this review highlights the critical role of HIF1 signaling in patients with both T2DM and breast cancer, potentiates its significance as a prognostic marker in comorbid patients, and further discusses the potential prognostic outcome of targeting HIF1, subsequently establishing the pressing need for HIF1 molecular profiling-based patient selection leading to more effective therapeutic strategies emerging from personalized medicine.

Targeting Hypoxia-Inducible Factor-1-Mediated Metastasis for Cancer Therapy

Significance: Hypoxia is emerging as a crucial regulator of the tumor microenvironment; it governs the metastatic potential of multiple primary cancers. It is also potentially involved in the regulation of tumorigenesis, tumor metabolism, and proangiogenic activity. Recent Advances: A wealth of clinical data across a wide range of cancer types has revealed strong correlations between hypoxia or the overexpression of hypoxia-inducible transcription factors and the rates of distant metastases and poor prognoses. Hypoxia-inducible factor (HIF)-1α, one of the key regulatory molecules of the HIF-1 signaling pathways, is involved in multiple crucial steps in the metastatic cascade. Critical Issues: Here, we present recent findings on the roles of the HIF-1 complex in tumor metastasis and highlight the potential of HIF-1α as a target for abrogating tumor metastasis. Moreover, we systematically describe the regulatory role of HIF-1 at each step of the metastatic cascade. Finally, we present the most recent advances in potential pharmacological interventions and the development of specific HIF-1 inhibitors for blocking tumor metastasis. Future Directions: Well-designed clinical trials are urgently needed to validate the anti-metastatic activity of HIF-1 inhibitors discovered in preclinical models. Antioxid. Redox Signal. 34, 1484-1497.

UCA1 Overexpression Promotes Hypoxic Breast Cancer Cell Proliferation and Inhibits Apoptosis via HIF-1α Activation

The noncoding RNA termed urothelial carcinoma-associated 1 (UCA1) is an oncogenic lncRNA involved in promoting the growth of several tumors through various pathways. The aim of this study was to explore the expression of UCA1 in hypoxic breast cancer and its impact on tumorigenesis in low levels of oxygen. Here, we show that UCA1 is upregulated in a number of hypoxic (1% O₂) breast cancer cells. In addition, UCA1 expression is significantly overexpressed in breast cancer tissues compared to matched normal cells. UCA1 knockdown in hypoxia inhibits breast cancer proliferation and induces apoptosis. The knockdown of hypoxia-inducible transcription factor 1α (HIF-1α) but not HIF-2α significantly decreases the expression of UCA1 in hypoxia. Overall, these findings indicate that UCA1 is a hallmark of hypoxic breast cancer and its expression is positively regulated by HIF-1α.

S-Nitrosylation in Tumor Microenvironment

S-nitrosylation is a selective and reversible post-translational modification of protein thiols by nitric oxide (NO), which is a bioactive signaling molecule, to exert a variety of effects. These effects include the modulation of protein conformation, activity, stability, and protein-protein interactions. S-nitrosylation plays a central role in propagating NO signals within a cell, tissue, and tissue microenvironment, as the nitrosyl moiety can rapidly be transferred from one protein to another upon contact. This modification has also been reported to confer either tumor-suppressing or tumor-promoting effects and is portrayed as a process involved in every stage of cancer progression. In particular, S-nitrosylation has recently been found as an essential regulator of the tumor microenvironment (TME), the environment around a tumor governing the disease pathogenesis. This review aims to outline the effects of S-nitrosylation on different resident cells in the TME and the diverse outcomes in a context-dependent manner. Furthermore, we will discuss the therapeutic potentials of modulating S-nitrosylation levels in tumors.

Gain of HIF1 Activity and Loss of miRNA let-7d Promote Breast Cancer Metastasis to the Brain via the PDGF/PDGFR Axis

Early detection and adjuvant therapies have significantly improved survival of patients with breast cancer over the past three decades. In contrast, management of metastatic disease remains unresolved. Brain metastasis is a late complication frequently observed among patients with metastatic breast cancer, whose poor prognosis calls for novel and more effective therapies. Here, we report that active hypoxia inducible factor-1 (HIF1) signaling and loss of the miRNA let-7d concur to promote brain metastasis in a recently established model of spontaneous breast cancer metastasis from the primary site to the brain (4T1-BM₂), and additionally in murine and human experimental models of breast cancer brain metastasis (D2A1-BM₂ and MDA231-BrM₂). Active HIF1 and let-7d loss upregulated expression of platelet-derived growth factor (PDGF) B/A in murine and human brain metastatic cells, respectively, while either individual silencing of HIF1α and PDGF-A/B or let-7d overexpression suppressed brain metastasis formation in the tested models. Let-7d silencing upregulated HIF1α expression and HIF1 activity, indicating a regulatory hierarchy of the system. The clinical relevance of the identified targets was supported by human gene expression data analyses. Treatment of mice with nilotinib, a kinase inhibitor impinging on PDGF receptor (PDGFR) signaling, prevented formation of spontaneous brain metastases in the 4T1-BM₂ model and reduced growth of established brain metastases in mouse and human models. These results identify active HIF1 signaling and let-7d loss as coordinated events promoting breast cancer brain metastasis through increased expression of PDGF-A/B. Moreover, they identify PDGFR inhibition as a potentially actionable therapeutic strategy for patients with brain metastatis. SIGNIFICANCE: These findings show that loss of miRNA let-7d and active HIF1 signaling promotes breast cancer brain metastasis via PDGF and that pharmacologic inhibition of PDGFR suppresses brain metastasis, suggesting novel therapeutic opportunities. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/3/594/F1.large.jpg.See related article by Thies et al., p. 606.

Distinct mRNAs in Cancer Extracellular Vesicles Activate Angiogenesis and Alter Transcriptome of Vascular Endothelial Cells

Simple Summary

Cancer extracellular vesicles (EVs) are implicated in various processes of cancer development, with most of the EV-induced changes attributed to EV proteins and microRNAs. However, the knowledge about the cancer EV-mRNAs remains limited. Here, we have assessed the mRNAs of 61 diverse oncogenes and found half of them, including VEGFA and SNAIL1/2, are abundant in cancer EVs while absent in non-tumorigenic cell-derived EVs. Fluorescent trafficking shows the EV VEGFA mRNAs are translatable after being internalized by the recipient cell. Concomitantly, the cancer EVs induced VEGFA-dependent angiogenesis and upregulated epithelial-mesenchymal transition-related genes. Our findings reveal that the EV-mRNA profile can reflect the cell malignancy, and the intercellular transfer of these mRNAs can contribute toward tumor angiogenesis.

Abstract

Cancer-derived extracellular vesicles (EVs) have been demonstrated to be implicated in various processes of cancer development, with most of the EV-induced changes attributed to EV-proteins and EV-microRNAs. However, the knowledge about the abundance of cancer EV-mRNAs and their contribution to cancer development remain elusive. Here, we show that mRNAs prevail in cancer EVs as compared with normal EVs, and cancer EVs that carry abundant angiogenic mRNAs activate angiogenesis in human umbilical vein endothelial cells (HUVECs). Specifically, of a gene panel comprising 61 hypoxia-targeted oncogenes, a larger proportion is harbored by cancer EVs (>40%) than normal EVs (14.8%). Fluorescent trafficking indicates cancer EVs deliver translatable mRNAs such as VEGFA to HUVECs, contributing to the activation of VEGFR-dependent angiogenesis and the upregulation of epithelial-mesenchymal transition-related and metabolism-related genes. Overall, our findings provide novel insights into EV-mRNAs and their role in angiogenesis, and has potential for diagnostic and therapeutic applications.

Exploiting S-nitrosylation for cancer therapy: facts and perspectives

S-nitrosylation, the post-translational modification of cysteines by nitric oxide, has been implicated in several cellular processes and tissue homeostasis. As a result, alterations in the mechanisms controlling the levels of S-nitrosylated proteins have been found in pathological states. In the last few years, a role in cancer has been proposed, supported by the evidence that various oncoproteins undergo gain- or loss-of-function modifications upon S-nitrosylation. Here, we aim at providing insight into the current knowledge about the role of S-nitrosylation in different aspects of cancer biology and report the main anticancer strategies based on: (i) reducing S-nitrosylation-mediated oncogenic effects, (ii) boosting S-nitrosylation to stimulate cell death, (iii) exploiting S-nitrosylation through synthetic lethality.

Angiogenesis regulation by microRNAs and long non-coding RNAs in human breast cancer

MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are capable of regulating gene expression post-transcriptionally. Since the past decade, a number of in vitro, in vivo, and clinical studies reported the roles of these non-coding RNAs (ncRNAs) in regulating angiogenesis, an important cancer hallmark that is associated with metastases and poor prognosis. The specific roles of various miRNAs and lncRNAs in regulating angiogenesis in breast cancer, with particular focus on the downstream targets and signalling pathways regulated by these ncRNAs will be discussed in this review. In light of the recent trend in exploiting ncRNAs as cancer therapeutics, the potential use of miRNAs and lncRNAs as biomarkers and novel therapeutic agent against angiogenesis was also discussed.

A Network Pharmacology Study on the Molecular Mechanisms of FDY003 for Breast Cancer Treatment

Herbal medicines have drawn considerable attention with regard to their potential applications in breast cancer (BC) treatment, a frequently diagnosed malignant disease, considering their anticancer efficacy with relatively less adverse effects. However, their mechanisms of systemic action have not been understood comprehensively. Based on network pharmacology approaches, we attempted to unveil the mechanisms of FDY003, an herbal drug comprised of Lonicera japonica Thunberg, Artemisia capillaris Thunberg, and Cordyceps militaris, against BC at a systemic level. We found that FDY003 exhibited pharmacological effects on human BC cells. Subsequently, detailed data regarding the biochemical components contained in FDY003 were obtained from comprehensive herbal medicine-related databases, including TCMSP and CancerHSP. By evaluating their pharmacokinetic properties, 18 chemical compounds in FDY003 were shown to be potentially active constituents interacting with 140 BC-associated therapeutic targets to produce the pharmacological activity. Gene ontology enrichment analysis using g:Profiler indicated that the FDY003 targets were involved in the modulation of cellular processes, involving the cell proliferation, cell cycle process, and cell apoptosis. Based on a KEGG pathway enrichment analysis, we further revealed that a variety of oncogenic pathways that play key roles in the pathology of BC were significantly enriched with the therapeutic targets of FDY003; these included PI3K-Akt, MAPK, focal adhesion, FoxO, TNF, and estrogen signaling pathways. Here, we present a network-perspective of the molecular mechanisms via which herbal drugs treat BC.

Advances in biofabrication techniques for collagen-based 3D in vitro culture models for breast cancer research

Collagen is the most abundant component of the extracellular matrix (ECM), therefore it represents an ideal biomaterial for the culture of a variety of cell types. Recently, collagen-based scaffolds have shown promise as 3D culture platforms for breast cancer-based research. Two-dimensional (2D) in vitro culture models, while useful for gaining preliminary insights, are ultimately flawed as they do not adequately replicate the tumour microenvironment. As a result, they do not facilitate proper 3D cell-cell/cell-matrix interactions and often an exaggerated response to therapeutic agents occurs. The ECM plays a crucial role in the development and spread of cancer. Alterations within the ECM have a significant impact on the pathogenesis of cancer, the initiation of metastasis and ultimate progression of the disease. 3D in vitro culture models that aim to replicate the tumour microenvironment have the potential to offer a new frontier for cancer research with cell growth, morphology and genetic properties that more closely match in vivo cancers. While initial 3D in vitro culture models used in breast cancer research consisted of simple hydrogel platforms, recent advances in biofabrication techniques, including freeze-drying, electrospinning and 3D bioprinting, have enabled the fabrication of biomimetic collagen-based platforms that more closely replicate the breast cancer ECM. This review highlights the current application of collagen-based scaffolds as 3D in vitro culture models for breast cancer research, specifically for adherence-based scaffolds (i.e. matrix-assisted). Finally, the future perspectives of 3D in vitro breast cancer models and their potential to lead to an improved understanding of breast cancer diagnosis and treatment are discussed.

The regulation of Hypoxia-Inducible Factor-1 (HIF-1alpha) expression by Protein Disulfide Isomerase (PDI)

Hypoxia-inducible factor-1alpha (HIF-1alpha), a transcription factor, plays a critical role in adaption to hypoxia, which is a major feature of diseases, including cancer. Protein disulfide isomerase (PDI) is up-regulated in numerous cancers and leads to cancer progression. PDI, a member of the TRX superfamily, regulates the transcriptional activities of several transcription factors. To investigate the mechanisms by which PDI affects the function of HIF-1alpha, the overexpression or knockdown of PDI was performed. The overexpression of PDI decreased HIF-1alpha expression in the human hepatocarcinoma cell line, Hep3B, whereas the knockdown of endogenous PDI increased its expression. NH₄Cl inhibited the decrease in HIF-1alpha expression by PDI overexpression, suggesting that HIF-1alpha was degraded by the lysosomal pathway. HIF-1alpha is transferred to lysosomal membranes by heat shock cognate 70 kDa protein (HSC70). The knockdown of HSC70 abolished the decrease, and PDI facilitated the interaction between HIF-1alpha and HSC70. HIF-1alpha directly interacted with PDI. PDI exists not only in the endoplasmic reticulum (ER), but also in the cytosol. Hypoxia increased cytosolic PDI. We also investigated changes in the redox state of HIF-1alpha using PEG-maleimide, which binds to thiols synthesized from disulfide bonds by reduction. An up-shift in the HIF-1alpha band by the overexpression of PDI was detected, suggesting that PDI formed disulfide bond in HIF-1alpha. HIF-1alpha oxidized by PDI was not degraded in HSC70-knockdown cells, indicating that the formation of disulfide bond in HIF-1alpha was important for decreases in HIF-1alpha expression. To the best of our knowledge, this is the first study to show the regulation of the expression and redox state of HIF-1alpha by PDI. We also demonstrated that PDI formed disulfide bonds in HIF-1alpha 1–245 aa and decreased its expression. In conclusion, the present results showed that PDI is a novel factor regulating HIF-1alpha through lysosome-dependent degradation by changes in its redox state.

The Role of BRCA1/2-Mutated Tumor Microenvironment in Breast Cancer

Taking into account the factors of high incidence rate, prevalence and mortality, breast cancer represents a crucial social and economic burden. Most cases of breast cancer develop as a consequence of somatic mutations accumulating in mammary epithelial cells throughout lifetime and approximately 5-10% can be ascribed to monogenic predispositions. Even though the role of genetic predispositions in breast cancer is well described in the context of genetics, very little is known about the role of the microenvironment carrying the same aberrant cells impaired by the germline mutation in the breast cancer development and progression. Based on the clinical observations, carcinomas carrying mutations in hereditary tumor-suppressor genes involved in maintaining genome integrity such as BRCA1/2 have worse prognosis and aggressive behavior. One of the mechanisms clarifying the aggressive nature of BRCA-associated tumors implies alterations within the surrounding adipose tissue itself. The objective of this review is to look at the role of BRCA1/2 mutations in the context of breast tumor microenvironment and plausible mechanisms by which it contributes to the aggressive behavior of the tumor cells.

Hypoxia, endoplasmic reticulum stress and chemoresistance: dangerous liaisons

Solid tumors often grow in a micro-environment characterized by < 2% O₂ tension. This condition, together with the aberrant activation of specific oncogenic patwhays, increases the amount and activity of the hypoxia-inducible factor-1α (HIF-1α), a transcription factor that controls up to 200 genes involved in neoangiogenesis, metabolic rewiring, invasion and drug resistance. Hypoxia also induces endoplasmic reticulum (ER) stress, a condition that triggers cell death, if cells are irreversibly damaged, or cell survival, if the stress is mild.Hypoxia and chronic ER stress both induce chemoresistance. In this review we discuss the multiple and interconnected circuitries that link hypoxic environment, chronic ER stress and chemoresistance. We suggest that hypoxia and ER stress train and select the cells more adapted to survive in unfavorable conditions, by activating pleiotropic mechanisms including apoptosis inhibition, metabolic rewiring, anti-oxidant defences, drugs efflux. This adaptative process unequivocally expands clones that acquire resistance to chemotherapy.We believe that pharmacological inhibitors of HIF-1α and modulators of ER stress, although characterized by low specificty and anti-cancer efficacy when used as single agents, may be repurposed as chemosensitizers against hypoxic and chemorefractory tumors in the next future.

Mitochondrial malic enzyme 2 promotes breast cancer metastasis via stabilizing HIF-1α under hypoxia

Objective

α-ketoglutarate (α-KG) is the substrate to hydroxylate collagen and hypoxia-inducible factor-1α (HIF-1α), which are important for cancer metastasis. Previous studies have shown that the upregulation of collagen prolyl 4-hydroxylase in breast cancer cells stabilizes the expression of HIF-1α by depleting α-KG levels. We hypothesized that mitochondrial malic enzyme 2 (ME2) might also affect HIF-1α expression via modulating α-KG levels in breast cancer cells.

Methods

We evaluated ME2 protein expression in 100 breast cancer patients using immunohistochemistry and correlated with clinicopathological indicators. The effect of ME2 knockout on cancer metastasis was evaluated using an orthotopic breast cancer model. The effect of ME2 knockout or knockdown on the levels of α-KG and HIF-1α proteins in breast cancer cell lines was determined both in vitro and in vivo.

Results

ME2 was found to be upregulated in the human breast cancerous tissues compared with the matched precancerous tissues (P<0.001). The elevated expression of ME2 was associated with a poor prognosis (P=0.019). ME2 upregulation was also related to lymph node metastasis (P=0.016), pathological staging (P=0.033), and vascular cancer embolus (P=0.014). Also, ME2 knockout significantly inhibited lung metastasisin vivo. In the tumors formed by ME2 knockout cells, the levels of α-KG were significantly increased and collagen hydroxylation level did not change significantly but HIF-1α protein expression was significantly decreased, compared to the control samples. In cell culture, cells with ME2 knockout or knockdown demonstrated significantly higher α-KG levels but significantly lower HIF-1α protein expression than control cells under hypoxia. Exogenous malate and α-KG exerted similar effect on HIF-1α in breast cancer cells to ME2 knockout or knockdown. Additionally, treatment with malate significantly decreased 4T1 breast cancer lung metastasis. ME2 expression was associated with HIF-1α levels in human breast cancer samples (P=0.008).

Conclusions

Our results provide evidence that upregulation of ME2 is associated with a poor prognosis of breast cancer patients and propose a mechanistic understanding of a link between ME2 and breast cancer metastasis.

Hypoxia-mediated drug resistance in breast cancers

Tissue hypoxia in solid tumors is caused by several pathological changes associated with tumor growth, including altered microvasculature structure, increased diffusional distances, and tumor-associated anemia. As the oxygen tension decreases, tumor cells adapt to the limited oxygen supply. Previous studies have shown that such adaptation leads to an aggressive phenotype that is resistant to many anti-cancer therapies. Induction of hypoxia inducible factors (HIFs) mediates many proteomic and genomic changes associated with tumor hypoxia. In breast cancers, HIFs not only predict poor prognosis, but also promote metastasis and drug resistance. Several studies have proposed HIF-1α as a druggable target in drug-resistant breast cancers, leading to the synthesis and development of small molecule inhibitors. Disappointingly, however, none of these small molecule inhibitors have progressed to clinical use. In this review, we briefly discuss the role of HIF-1α in breast cancer drug resistance and summarize the current and future approaches to targeting this transcription factor in breast cancer treatment.

Cancer Stem Cell-Associated Pathways in the Metabolic Reprogramming of Breast Cancer

Metabolic reprogramming of cancer is now considered a hallmark of many malignant tumors, including breast cancer, which remains the most commonly diagnosed cancer in women all over the world. One of the main challenges for the effective treatment of breast cancer emanates from the existence of a subpopulation of tumor-initiating cells, known as cancer stem cells (CSCs). Over the years, several pathways involved in the regulation of CSCs have been identified and characterized. Recent research has also shown that CSCs are capable of adopting a metabolic flexibility to survive under various stressors, contributing to chemo-resistance, metastasis, and disease relapse. This review summarizes the links between the metabolic adaptations of breast cancer cells and CSC-associated pathways. Identification of the drivers capable of the metabolic rewiring in breast cancer cells and CSCs and the signaling pathways contributing to metabolic flexibility may lead to the development of effective therapeutic strategies. This review also covers the role of these metabolic adaptation in conferring drug resistance and metastasis in breast CSCs.

Quadruple-negative breast cancer: novel implications for a new disease

Based on the androgen receptor (AR) expression, triple-negative breast cancer (TNBC) can be subdivided into AR-positive TNBC and AR-negative TNBC, also known as quadruple-negative breast cancer (QNBC). QNBC characterization and treatment is fraught with many challenges. In QNBC, there is a greater paucity of prognostic biomarkers and therapeutic targets than AR-positive TNBC. Although the prognostic role of AR in TNBC remains controversial, many studies revealed that a lack of AR expression confers a more aggressive disease course. Literature characterizing QNBC tumor biology and uncovering novel biomarkers for improved management of the disease remains scarce. In this comprehensive review, we summarize the current QNBC landscape and propose avenues for future research, suggesting potential biomarkers and therapeutic strategies that warrant investigation.

Genome-Wide Epigenetic Signatures of Adaptive Developmental Plasticity in the Andes

High-altitude adaptation is a classic example of natural selection operating on the human genome. Physiological and genetic adaptations have been documented in populations with a history of living at high altitude. However, the role of epigenetic gene regulation, including DNA methylation, in high-altitude adaptation is not well understood. We performed an epigenome-wide DNA methylation association study based on whole blood from 113 Peruvian Quechua with differential lifetime exposures to high altitude (>2,500) and recruited based on a migrant study design. We identified two significant differentially methylated positions (DMPs) and 62 differentially methylated regions (DMRs) associated with high-altitude developmental and lifelong exposure statuses. DMPs and DMRs were found in genes associated with hypoxia-inducible factor pathway, red blood cell production, blood pressure, and others. DMPs and DMRs associated with fractional exhaled nitric oxide also were identified. We found a significant association between EPAS1 methylation and EPAS1 SNP genotypes, suggesting that local genetic variation influences patterns of methylation. Our findings demonstrate that DNA methylation is associated with early developmental and lifelong high-altitude exposures among Peruvian Quechua as well as altitude-adaptive phenotypes. Together these findings suggest that epigenetic mechanisms might be involved in adaptive developmental plasticity to high altitude. Moreover, we show that local genetic variation is associated with DNA methylation levels, suggesting that methylation associated SNPs could be a potential avenue for research on genetic adaptation to hypoxia in Andeans.

Lactate in the Tumor Microenvironment: An Essential Molecule in Cancer Progression and Treatment

Simple Summary

The role of lactate in cancer described by Otto Warburg in 1927 states that cancer cells uptake high amount of glucose with a marked increase in lactate production, this is known as the “Warburg effect”. Since then lactate turn out to be a major signaling molecule in cancer progression. Its release from tumor cells is accompanied by acidification ranging from 6.3 to 6.9 in the tumor microenvironment (TME) which favors processes such as tumor promotion, angiogenesis, metastasis, tumor resistance and more importantly, immunosuppression which has been associated with a poor outcome. The goal of this review is to examine and discuss in deep detail the recent studies that address the role of lactate in all these cancerous processes. Lastly, we explore the efforts to target the lactate production and its transport as a promising approach for cancer therapeutics.

Abstract

Cancer is a complex disease that includes the reprogramming of metabolic pathways by malignant proliferating cells, including those affecting the tumor microenvironment (TME). The “TME concept” was introduced in recognition of the roles played by factors other than tumor cells in cancer progression. In response to the hypoxic or semi-hypoxic characteristic of the TME, cancer cells generate a large amount of lactate via the metabolism of glucose and glutamine. Export of this newly generated lactate by the tumor cells together with H+ prevents intracellular acidification but acidifies the TME. In recent years, the importance of lactate and acidosis in carcinogenesis has gained increasing attention, including the role of lactate as a tumor-promoting metabolite. Here we review the existing literature on lactate metabolism in tumor cells and the ability of extracellular lactate to direct the metabolic reprogramming of those cells. Studies demonstrating the roles of lactate in biological processes that drive or sustain carcinogenesis (tumor promotion, angiogenesis, metastasis and tumor resistance) and lactate’s role as an immunosuppressor that contributes to tumor evasion are also considered. Finally, we consider recent therapeutic efforts using available drugs directed at and interfering with lactate production and transport in cancer treatment.

Liposomal formulation of HIF-1α inhibitor echinomycin eliminates established metastases of triple-negative breast cancer

Hypoxia-inducible factor 1α (HIF-1α) is recognized as a prime molecular target for metastatic cancer. However, no specific HIF-1α inhibitor has been approved for clinical use. Here, we demonstrated that in vivo efficacy of echinomycin in solid tumors with HIF-1α overexpression is formulation-dependent. Compared to previously-used Cremophor-formulated echinomycin, which was toxic and ineffective in clinical trials, liposomal-echinomycin provides significantly more inhibition of primary tumor growth and only liposome-formulated echinomycin can eliminate established triple-negative breast cancer (TNBC) metastases, which are the leading cause of death from breast cancer, as available therapies remain minimally effective at this stage. Pharmacodynamic analyses reveal liposomal-echinomycin more potently inhibits HIF-1α transcriptional activity in primary and metastasized TNBC cells in vivo, the latter of which are HIF-1α enriched. The data suggest that nanoliposomal-echinomycin can provide safe and effective therapeutic HIF-1α inhibition and could represent the most potent HIF-1α inhibitor in prospective trials for metastatic cancer.

In vivo longitudinal and multimodal imaging of hypoxia-inducible factor 1α and angiogenesis in breast cancer

Background

Angiogenesis and hypoxia-inducible factor 1α (HIF-1α) play major roles in solid tumors. This study aimed to establish a longitudinal and multimodal imaging model for in vivo evaluation of HIF1α and angiogenesis in breast cancer.

Methods

By transfection of a 5 hypoxia-responsive element (HRE)/green fluorescent protein (GFP) plasmid, the cell line Ca761-hre-gfp was established, which emitted green fluorescence triggered by HIF-1α under hypoxia. The cells were subjected to CoCl₂-simulated hypoxia to confirm the imaging strategy. We grew Ca761-hre-gfp cells in the left rear flanks of twelve 615 mice. Experiments were conducted on days 4, 9, 15, and 19. For in vivo analysis, Ca761-hre-gfp subcutaneous allografted tumors were imaged in vivo using contrast-enhanced ultrasound (CEUS) and fluorescence imaging (FLI) during tumor development. The tumor size, CEUS peak intensity, and FLI photons were measured to evaluate tumor growth, angiogenesis, and HIF-1α activity, respectively. After each experiment, three mice were randomly sacrificed and tumor specimens were collected to examine HIF-1α activity and the microvessel density (MVD).

Results

In vitro, both green fluorescence and HIF-1α expression were detected in Ca761-hre-gfp cells treated with CoCl₂, indicating the suitability of the cells to detect HIF-1α activity. In vivo, HIF-1α activity first increased and then decreased, which was significantly correlated with angiogenic changes (r = 0.803, P = 0.005). These changes were confirmed by immunohistochemical staining of HIF-1α and MVD.

Conclusions

The findings validated the Ca761-hre-gfp murine allograft model for reliable evaluation of HIF-1α activity and angiogenesis longitudinally using both molecular and pre-clinical non-invasive imaging modalities. The cell line may be useful for studies of anti-HIF pathway therapies.

ER and PI3K Pathway Activity in Primary ER Positive Breast Cancer Is Associated with Progression-Free Survival of Metastatic Patients under First-Line Tamoxifen

Estrogen receptor positive (ER+) breast cancer patients are eligible for hormonal treatment, but only around half respond. A test with higher specificity for prediction of endocrine therapy response is needed to avoid hormonal overtreatment and to enable selection of alternative treatments. A novel testing method was reported before that enables measurement of functional signal transduction pathway activity in individual cancer tissue samples, using mRNA levels of target genes of the respective pathway-specific transcription factor. Using this method, 130 primary breast cancer samples were analyzed from non-metastatic ER+ patients, treated with surgery without adjuvant hormonal therapy, who subsequently developed metastatic disease that was treated with first-line tamoxifen. Quantitative activity levels were measured of androgen and estrogen receptor (AR and ER), PI3K-FOXO, Hedgehog (HH), NFκB, TGFβ, and Wnt pathways. Based on samples with known pathway activity, thresholds were set to distinguish low from high activity. Subsequently, pathway activity levels were correlated with the tamoxifen treatment response and progression-free survival. High ER pathway activity was measured in 41% of the primary tumors and was associated with longer time to progression (PFS) of metastases during first-line tamoxifen treatment. In contrast, high PI3K, HH, and androgen receptor pathway activity was associated with shorter PFS, and high PI3K and TGFβ pathway activity with worse treatment response. Potential clinical utility of assessment of ER pathway activity lies in predicting response to hormonal therapy, while activity of PI3K, HH, TGFβ, and AR pathways may indicate failure to respond, but also opens new avenues for alternative or complementary targeted treatments.

HIF-1 stabilization exerts anticancer effects in breast cancer cells in vitro and in vivo

Tumor hypoxia and high activity of hypoxia-inducible factor-1 (HIF-1) correlate with adverse disease outcomes, malignancy, resistance to therapy and metastasis. Nonetheless, recent studies indicate that under certain circumstances, HIF-1 stabilization may exert protective effects and even decrease tumor cell aggressiveness. This study aimed to characterize the potential anticancer effect of molidustat (BAY 85-3934), the prolyl hydroxylase (PHD) inhibitor and HIF-1 stabilizator. We confirmed that molidustat stabilizes HIF-1α and induces the expression of vascular endothelial growth factor (VEGF) in MDA-MB-231 breast cancer cells, to a similar or even greater extent than hypoxia. Interestingly, decreased cell survival and colony formation capabilities, together with S/G2 cell cycle arrest, were observed after treatment with PHD inhibitor. Importantly, molidustat enhanced the effectiveness of the chemotherapeutic drug, gemcitabine, on cancer cells. Finally, the xenograft model revealed decreased tumor growth in vivo after molidustat treatment. Both in vitro and in vivo analysis showed no differences in the angiogenic potential of endothelial cells treated with tumor-conditioned media or vascularization of the MDA-MB-231 xenografts, respectively. In summary, molidustat treatment exhibits an inhibitory effect on breast cancer cell survival, self-renewal capacity and potentiates the efficacy of chemotherapeutic gemcitabine.

The Cancer Stem Cell in Hepatocellular Carcinoma

The recognition of intra-tumoral cellular heterogeneity has given way to the concept of the cancer stem cell (CSC). According to this concept, CSCs are able to self-renew and differentiate into all of the cancer cell lineages present within the tumor, placing the CSC at the top of a hierarchical tree. The observation that these cells—in contrast to bulk tumor cells—are able to exclusively initiate new tumors, initiate metastatic spread and resist chemotherapy implies that CSCs are solely responsible for tumor recurrence and should be therapeutically targeted. Toward this end, dissecting and understanding the biology of CSCs should translate into new clinical therapeutic approaches. In this article, we review the CSC concept in cancer, with a special focus on hepatocellular carcinoma.

The Hypoxic Response Expression as a Survival Biomarkers in Treatment-Naive Advanced Breast Cancer

OBJECTIVE

Hypoxia-associated biomarkers profiling may provide information for prognosis, staging, and subsequent therapy. We aim to evaluate whether the quantitative gene and protein expression of hypoxic response tumor markers - carbonic anhydrase IX (CAIX) and hypoxia- inducible factor 1 alpha (HIF1A) - may have a role in predicting survival in advanced breast cancer of Indonesian population.

METHODS

Tumor tissues and peripheral blood samples were collected from treatment - naïve locally advanced (LABC) or metastatic breast cancer patients (MBC) at Wahidin Sudirohusodo General Hospital (Makassar, South Sulawesi) and its referral network hospitals from July 2017 to March 2019. The level of mRNA (of blood and tumor tissue samples) and soluble protein (of blood samples) of CAIX and HIF1A were measured by RT-qPCR and ELISA methods, respectively, besides the standard histopathological grading and molecular subtype assessment. The CAIX and HIF1A expression, patients' age, tumor characteristics, surgery status, and neoadjuvant chemotherapy drug classes were further involved in survival analyses for overall survival (OS) and progression-free survival (PFS).

RESULTS

Forty (30 LABC, 10 MBC) eligible patients examined were 21 hormone-receptors positives (15 Luminal A, 6 Luminal B) and 19 hormone-receptors negatives (10 HER2-enriched, 9 triple-negative). The CAIX blood mRNA and CAIX soluble protein levels in hormone-receptors negative patients were higher than in hormone-receptor-positive patients (p < 0.05). In univariate analysis, both CAIX and HIF1A levels predict OS (except HIF1A protein) with CAIX tissue mRNA has the highest hazard ratio (HR 8.04, 95%CI:2.45-26.39), but not PFS. Cox proportional hazard model confirmed that CAIX tissue mRNA is the independent predictor of OS (HR 6.10, 95%CI: 1.16-32.13) along with surgical status and tumor advancement type (LABC or MBC).

CONCLUSIONS

CAIX mRNA expression of tumor tissue in treatment-naïve advanced breast cancer has a predictive value for OS.
.

Bayesian Network Marker Selection via the Thresholded Graph Laplacian Gaussian Prior

Selecting informative nodes over large-scale networks becomes increasingly important in many research areas. Most existing methods focus on the local network structure and incur heavy computational costs for the large-scale problem. In this work, we propose a novel prior model for Bayesian network marker selection in the generalized linear model (GLM) framework: the Thresholded Graph Laplacian Gaussian (TGLG) prior, which adopts the graph Laplacian matrix to characterize the conditional dependence between neighboring markers accounting for the global network structure. Under mild conditions, we show the proposed model enjoys the posterior consistency with a diverging number of edges and nodes in the network. We also develop a Metropolis-adjusted Langevin algorithm (MALA) for efficient posterior computation, which is scalable to large-scale networks. We illustrate the superiorities of the proposed method compared with existing alternatives via extensive simulation studies and an analysis of the breast cancer gene expression dataset in the Cancer Genome Atlas (TCGA).

Microfluidic platform for three-dimensional cell culture under spatiotemporal heterogeneity of oxygen tension

Cells in a tumor microenvironment are exposed to spatial and temporal variations in oxygen tension due to hyperproliferation and immature vascularization. Such spatiotemporal oxygen heterogeneity affects the behavior of cancer cells, leading to cancer growth and metastasis, and thus, it is essential to clarify the cellular responses of cancer cells to oxygen tension. Herein, we describe a new double-layer microfluidic device allowing the control of oxygen tension and the behavior of cancer cells under spatiotemporal oxygen heterogeneity. Two parallel gas channels were located above the media and gel channels to enhance gas exchange, and a gas-impermeable polycarbonate film was embedded in the device to prevent the diffusion of atmospheric oxygen. Variations in oxygen tension in the device with the experimental parameters and design variables were investigated computationally and validated by using oxygen-sensitive nanoparticles. The present device can generate a uniform hypoxic condition at oxygen levels down to 0.3% O2, as well as a linear oxygen gradient from 3% O2 to 17% O2 across the gel channel within 15 min. Moreover, human breast cancer cells suspended in type I collagen gel were introduced in the gel channel to observe their response under controlled oxygen tension. Hypoxic exposure activated the proliferation and motility of the cells, which showed a local maximum increase at 5% O2. Under the oxygen gradient condition, the increase in the cell number was relatively high in the central mild hypoxia region. These findings demonstrate the utility of the present device to study cellular responses in an oxygen-controlled microenvironment.

TSGA10 Over Expression Decreases Metastasic and Metabolic Activity by Inhibiting HIF-1 in Breast Cancer Cells

BACKGROUND AND AIMS

HIF-1 is an important factor that play critical roles in metabolic and metastasis activity of cancer cells. HIF-1 activity can have regulated by TSGA10. Although decreased metastatic activity of cancer cells through TSGA10 inhibitory effect on HIF-1 have already been demonstrated, changes in cancer metabolism and its impact on metastasis in breast cancer is still not determined. So, we aimed to investigate TSGA10 overexpression effect on breast cancer metabolism as well as metastasis.

METHODS

TSGA10 vector was designed and stable transfected into MCF-7 cells. The efficiency of transfection was assessed by Real-time PCR and western blot. After HIF-1 induction at high and low glucose conditions, cell proliferation, cell cycle profile, metabolic and metastasis activity of cells were assessed. Furthermore, biomarker expressions of ER, PR, HER2, Ki67 and E-cadherin in cancer cells were measured.

RESULTS

Our results showed decrease of cell proliferation and cell cycle arrest in G2/M phase. Reduce expression of GLUT1, lactate production and reactive oxygen species (ROS) below their basal level indicated decreased metabolic activity. Furthermore, metastatic activity reduction was shown by decrease expression of different involve genes in metastasis, protelytic activity of MMOLP-2/9, carbonic anhydrase (CA) IX activity and increase of wound closure. Moreover, except for E-cadherin, expression of ER, PR, HER2 and Ki67 was declined in cells.

CONCLUSION

Our findings indicated that TSGA10 overexpression could decrease the metastatic and metabolic activity of cancer cells through its inhibitory effect on HIF-1 activity. Therefore, TSGA10 could be considered in the research for therapeutic candidates in cancer.

Sanguinarine disrupts the colocalization and interaction of HIF-1α with tyrosine and serine phosphorylated-STAT3 in breast cancer

Breast cancer is one leading cause of death in females, especially triple‐negative breast cancer (TNBC). Hypoxia is a key feature leading to tumour progression driven by hypoxia‐inducible factor (HIF)‐1α. The aim is to investigate the mechanism of HIF‐1α and signal transducer and activator of transcription‐3 (STAT3) interaction and discover a compound to disrupt the interaction in breast cancer cells. The regulation pattern of HIF‐1α and STAT3 was analysed in hypoxic TNBC cells and patient samples. The effects of a natural alkaloid, sanguinarine, on HIF‐1α and STAT3 colocalization and interaction were evaluated in vitro and mouse xenograft models. We observed strong colocalization of HIF‐1α, p‐STAT3‐Tyr and p‐STAT3‐Ser in TNBC patient samples. Sanguinarine could inhibit the nuclear colocalization and interaction of HIF‐1α with p‐STAT3‐Tyr and p‐STAT3‐Ser in vivo and in vitro. Our results may bring insights to the HIF‐1α/STAT3 interaction in breast cancers and suggest sanguinarine as a promising candidate for HIF‐α/STAT3 inhibition.

Regulation of hypoxia-inducible factor functions in the nucleus by sphingosine-1-phosphate

Sphingosine kinase 2 (SphK2) is known to phosphorylate the nuclear sphingolipid metabolite to generate sphingosine-1-phosphate (S1P). Nuclear S1P is involved in epigenetic regulation of gene expression; however, the underlying mechanisms are not well understood. In this work, we have identified the role of nuclear S1P and SphK2 in regulating hypoxia-responsive master transcription factors hypoxia-inducible factor (HIF)-1α/2α, and their functions in breast cancer, with a focus on triple-negative breast cancer (TNBC). We have shown SphK2 is associated with HIF-1α in protein complexes, and is enriched at the promoters of HIF target genes, including vascular endothelial growth factor (VEGF), where it enhances local histone H3 acetylation and transcription. S1P specifically binds to the PAS domains of HIF-1α. SphK2, and HIF-1α expression levels are elevated in metastatic estrogen receptor-positive (ER+) and TNBC clinical tissue specimens compared to healthy breast tissue samples. To determine if S1P formation in the nucleus by SphK2 is a key regulator of HIF functions, we found using a preclinical TNBC xenograft mouse model, and an existing selective SphK2 inhibitor K-145, that nuclear S1P, histone acetylation, HIF-1α expression, and TNBC tumor growth were all reduced in vivo. Our results suggest that S1P and SphK2 in the nucleus are linked to the regulation of HIF-1α/2α functions associated with breast cancer progression, and may provide potential therapeutic targets.

Cancer stem cells and their unique role in metastatic spread

Cancer stem cells (CSC) possess abilities generally associated with embryonic or adult stem cells, especially self-renewal and differentiation, but also dormancy and cellular plasticity that allow adaption to new environmental circumstances. These abilities are ideal prerequisites for the successful establishment of metastasis. This review highlights the role of CSCs in every step of the metastatic cascade from cancer cell invasion into blood vessels, survival in the blood stream, attachment and extravasation as well as colonization of the host organ and subsequent establishment of distant macrometastasis.

RhoB is regulated by hypoxia and modulates metastasis in breast cancer

BACKGROUND

RhoB is a Rho family GTPase that is highly homologous to RhoA and RhoC. RhoA and RhoC have been shown to promote tumor progression in many cancer types; however, a distinct role for RhoB in cancer has not been delineated. Additionally, several well-characterized studies have shown that small GTPases such as RhoA, Rac1, and Cdc42 are induced in vitro under hypoxia, but whether and how hypoxia regulates RhoB in breast cancer remains elusive.

AIMS

To determine whether and how hypoxia regulates RhoB expression and to understand the role of RhoB in breast cancer metastasis.

METHODS

We investigated the effects of hypoxia on the expression and activation of RhoB using real-time quantitative polymerase chain reaction and western blotting. We also examined the significance of both decreased and increased RhoB expression in breast cancer using CRISPR depletion of RhoB or a vector overexpressing RhoB in 3D in vitro migration models and in an in vivo mouse model.

RESULTS

We found that hypoxia significantly upregulated RhoB mRNA and protein expression resulting in increased levels of activated RhoB. Both loss of RhoB and gain of RhoB expression led to reduced migration in a 3D collagen matrix and invasion within a multicellular 3D spheroid. We showed that neither the reduction nor overexpression of RhoB affected tumor growth in vivo. While the loss of RhoB had no effect on metastasis, RhoB overexpression led to decreased metastasis to the lungs, liver, and lymph nodes of mice.

CONCLUSION

Our results suggest that RhoB may have an important role in suppressing breast cancer metastasis.

Circular RNA; a new biomarker for breast cancer: A systematic review

Circular RNAs (circRNAs) were recently discovered as a looped subset of competing endogenous RNAs, with an ability to regulate gene expression by microRNA sponging. There are several studies on their potential roles in cancer development, such as colorectal cancer and basal cell carcinoma. However, there is still a significant gap in the knowledge about circRNA functions in breast cancer (BC) progression. The current study systematically reviewed circRNA biogenesis and their potential roles as a novel biomarker in BC on published studies of the MEDLINE®/PubMed, Cochrane®, and Scopus® databases. The obtained results showed a general dysregulation of circRNAs expression in BC cells with a cell-type and stage-specific manner. The potential connection between circRNAs and BC cell proliferation, apoptosis, metastasis, and chemotherapy sensitivity and resistance were discussed.

Is Lactate an Oncometabolite? Evidence Supporting a Role for Lactate in the Regulation of Transcriptional Activity of Cancer-Related Genes in MCF7 Breast Cancer Cells

Lactate is a ubiquitous molecule in cancer. In this exploratory study, our aim was to test the hypothesis that lactate could function as an oncometabolite by evaluating whether lactate exposure modifies the expression of oncogenes, or genes encoding transcription factors, cell division, and cell proliferation in MCF7 cells, a human breast cancer cell line. Gene transcription was compared between MCF7 cells incubated in (a) glucose/glutamine-free media (control), (b) glucose-containing media to stimulate endogenous lactate production (replicating some of the original Warburg studies), and (c) glucose-containing media supplemented with L-lactate (10 and 20 mM). We found that both endogenous, glucose-derived lactate and exogenous, lactate supplementation significantly affected the transcription of key oncogenes (MYC, RAS, and PI3KCA), transcription factors (HIF1A and E2F1), tumor suppressors (BRCA1, BRCA2) as well as cell cycle and proliferation genes involved in breast cancer (AKT1, ATM, CCND1, CDK4, CDKN1A, CDK2B) (0.001 < p < 0.05 for all genes). Our findings support the hypothesis that lactate acts as an oncometabolite in MCF7 cells. Further research is necessary on other cell lines and biopsy cultures to show generality of the findings and reveal the mechanisms by which dysregulated lactate metabolism could act as an oncometabolite in carcinogenesis.

Generating linear oxygen gradients across 3D cell cultures with block-layered oxygen controlled chips (BLOCCs)

Oxygen is a transcriptional regulator responsible for tissue homeostasis and maintenance. Studies relating cellular phenotype with oxygen tension often use hypoxia chambers, which expose cells to a single, static oxygen tension. Despite their ease of use, these chambers are unable to replicate the oxygen gradients found in healthy and diseased tissues. Microfabricated devices capable of imposing an oxygen gradient across tissue-like structures are a promising tool for these studies, as they can provide a high density of information in a single experimental setup. We describe the fabrication and characterization of a modular device, which leverages the gas-permeability of silicone to impose gradients of oxygen across cell-containing regions, assembled by layering sheets of laser cut acrylic and silicone rubber. The silicone also acts as a barrier, separating the flowing gases from the cell culture medium, preventing evaporation or bubble formation in experiments that require prolonged periods of incubation. The acrylic components provide a rigid framework to provide a sterile culture environment. Using oxygen-sensing films, we show the device can support gradients of different ranges and steepness by simply changing the composition of the gases flowing through the silicone components of the BLOCC. Using a cell-based reporter assay, we demonstrate that cellular responses to hypoxia are proportional to oxygen tension.

Hypoxia-Inducible Factor 1A Upregulates HMGN5 by Increasing the Expression of GATA1 and Plays a Role in Osteosarcoma Metastasis

Osteosarcoma is one of the most common malignant tumors in children and adolescents and is characterized by early metastasis. High-mobility group N (HMGN) domains are involved in the development of several tumors. Our previous study found that HMGN5 is highly expressed in osteosarcoma tissues and knockdown of HMGN5 inhibits migration and invasion of U-2 OS and Saos-2 cells. A hypoxic environment is commonly found in solid tumors such as osteosarcoma and is likely to be associated with tumor metastasis, so we further explored the relationship between HMGN5 and the hypoxic environment. Hypoxia-inducible factor 1A (HIF1A) is an adaptive factor in the hypoxic environment. We found that HIF1A and HMGN5 were upregulated in osteosarcoma (OS) cells cultured in the hypoxic environment, and the results of overexpression and knockdown experiments showed that HIF1A upregulated the transcription factor GATA1 and further promoted the expression of HMGN5. In addition, MMP2 and MMP9 were subsequently upregulated through the c-jun pathway, and finally, this promoted the migration and invasion of OS cells. It is suggested that HMGN5 may be an important downstream factor for HIF1A to promote osteosarcoma metastasis. It has an important clinical significance for the selection of therapeutic targets for osteosarcoma.