Tumour oxygenation: implications for breast cancer prognosis

Canine mammary tumors as a promising adjunct preclinical model for human breast cancer research: similarities, opportunities, and challenges

Despite significant progress in the field of human breast cancer research and treatment, there is a consistent increase in the incidence rate of 0.5 percent annually, posing challenges in the development of effective novel therapeutic strategies. The failure rate of drugs in clinical trials stands at approximately 95%, primarily attributed to the limitations and lack of reliability of existing preclinical models, such as mice, which do not mimic human tumor biology. This article examines the potential utility of canine mammary tumors as an adjunct preclinical model for investigating human breast cancer. Given the numerous similarities between canine and human breast cancer, canines present a promising alternative model. The discussion delves into the intricate molecular and clinical aspects of human breast cancer and canine mammary tumors, shedding light on the tumors' molecular profiles, identifying specific molecular markers, and the application of radiological imaging modalities. Furthermore, the manuscript addresses the current constraints of preclinical cancer studies, the benefits of using canines as models, and the obstacles linked to the canine mammary tumors model. By concentrating on these elements, this review aims to highlight the viability of canine models in enhancing our understanding and management of human breast cancer.

NIR-II Photoacoustic Imaging-Guided Chemo-Photothermal Therapy Using PA1094T Combined with Anti-CD47 Antibody: Activating Pyroptosis against Orthotopic Glioblastoma

Treating glioblastoma (GBM) with single-agent chemotherapy is often ineffective due to inefficient drug delivery and the immunosuppressive tumor microenvironment, which leads to drug resistance. Strategies that activate programmed cell death mechanisms and repolarized tumor-associated macrophages toward an antitumoral M1-like phenotype can help reverse the immunosuppressive tumor microenvironment. In this study, a novel approach using NIR-II (1000-1700 nm) photoacoustic imaging (PAI)-guided chemo-photothermal therapy is presented. NIR-II imaging, with its superior tissue penetration and reduced background noise, enables precise tumor targeting. A targeted nano prodrug is developed using poly (lactic-co-glycolic acid) nanoparticles loaded with A1094 dye and temozolomide (TMZ), coupled with an anti-CD47 antibody. This system employs synergistic chemo-photothermal therapy activated by NIR-II light, inducing apoptosis, pyroptosis, and T-cell activation. PAI provides rapid, point-of-care GBM diagnosis, and highlighted the effective targeting of the PA1094T nanoplatform. In a recurrent GBM model, the combination of PA1094T and anti-CD47 antibody significantly enhances cancer cell phagocytosis and effectively remodels the immunosuppressive microenvironment, resulting in better therapeutic outcomes compared to conventional therapies. These results indicate that this NIR-II PAI-guided drug cocktail therapy is a promising strategy for treating GBM, potentially addressing drug resistance and improving treatment efficacy through enhanced targeting and immunomodulation.

A Self-Catalytic NO/O2 Gas-Releasing Nanozyme for Radiotherapy Sensitization through Vascular Normalization and Hypoxia Relief

Radiotherapy (RT), essential for treating various cancers, faces challenges from tumor hypoxia, which induces radioresistance. A tumor-targeted "prosthetic-Arginine" coassembled nanozyme system, engineered to catalytically generate nitric oxide (NO) and oxygen (O2) in the tumor microenvironment (TME), overcoming hypoxia and enhancing radiosensitivity is presented. This system integrates the prosthetic heme of nitric oxide synthase (NOS) and catalase (CAT) with NO-donating Fmoc-protected Arginine and Ru3+ ions, creating HRRu nanozymes that merge NOS and CAT functionalities. Surface modification with human heavy chain ferritin (HFn) improves the targeting ability of nanozymes (HRRu-HFn) to tumor tissues. In the TME, strategic arginine incorporation within the nanozyme allows autonomous O2 and NO release, triggered by endogenous hydrogen peroxide, elevating NO and O2 levels to normalize vasculature and improve blood perfusion, thus mitigating hypoxia. Employing the intrinsic O2-transporting ability of heme, HRRu-HFn nanozymes also deliver O2 directly to the tumor site. Utilizing esophageal squamous cell carcinoma as a tumor model, the studies reveal that the synergistic functions of NO and O2 production, alongside targeted delivery, enable the HRRu-HFn nanozymes to combat tumor hypoxia and potentiate radiotherapy. This HRRu-HFn nanozyme based approach holds the potential to reduce the radiation dose required and minimize side effects associated with conventional radiotherapy.

Next-Cell Hypothesis: Mechanism of Obesity-Associated Carcinogenesis

Higher body fat content is related to a higher risk of mortality, and obesity-related cancer represents approximately 40% of all cancer patients diagnosed each year. Furthermore, epigenetic mechanisms are involved in cellular metabolic memory and can determine one's predisposition to being overweight. Low-grade chronic inflammation, a well-established characteristic of obesity, is a central component of tumor development and progression. Cancer-associated adipocytes (CAA), which enhance inflammation- and metastasis-related gene sets within the cancer microenvironment, have pro-tumoral effects. Adipose tissue is a major source of the exosomal micro ribonucleic acids (miRNAs), which modulate pathways involved in the development of obesity and obesity-related comorbidities. Owing to their composition of cargo, exosomes can activate receptors at the target cell or transfer molecules to the target cells and thereby change the phenotype of these cells. Exosomes that are released into the extracellular environment are internalized with their cargo by neighboring cells. The tumor-secreted exosomes promote organ-specific metastasis of tumor cells that normally lack the capacity to metastasize to a specific organ. Therefore, the communication between neighboring cells via exosomes is defined as the "next-cell hypothesis." The reciprocal interaction between the adipocyte and tumor cell is realized through the adipocyte-derived exosomal miRNAs and tumor cell-derived oncogenic miRNAs. The cargo molecules of adipocyte-derived exosomes are important messengers for intercellular communication involved in metabolic responses and have very specific signatures that direct the metabolic activity of target cells. RNA-induced silencing regulates gene expression through various mechanisms. Destabilization of DICER enzyme, which catalyzes the conversion of primary miRNA (pri-miRNA) to precursor miRNA (pre-miRNA), is an important checkpoint in cancer development and progression. Interestingly, adipose tissue in obesity and tumors share similar pathogenic features, and the local hypoxia progress in both. While hypoxia in obesity leads to the adipocyte dysfunction and metabolic abnormalities, in obesity-related cancer cases, it is associated with worsened prognosis, increased metastatic potential, and resistance to chemotherapy. Notch-interleukin-1 (IL-1)-Leptin crosstalk outcome is referred to as "NILCO effect." In this chapter, obesity-related cancer development is discussed in the context of "next-cell hypothesis," miRNA biogenesis, and "NILCO effect."

Nanotechnology-mediated photodynamic therapy: Focus on overcoming tumor hypoxia

The oxygen level in the tumor is a critical marker that determines response to different treatments. Cancerous cells can adapt to hypoxia and low pH conditions within the tumor microenvironment (TME) to regulate tumor metabolism, proliferation, and promote tumor metastasis as well as angiogenesis, consequently leading to treatment failure and recurrence. In recent years, widespread attempts have been made to overcome tumor hypoxia through different methods, such as hyperbaric oxygen therapy (HBOT), hyperthermia, O2 carriers, artificial hemoglobin, oxygen generator hydrogels, and peroxide materials. While oxygen is found to be an essential agent to improve the treatment response of photodynamic therapy (PDT) and other cancer treatment modalities, the development of hypoxia within the tumor is highly associated with PDT failure. Recently, the use of nanoparticles has been a hot topic for researchers and exploited to overcome hypoxia through Oxygen-generating hydrogels, O2 nanocarriers, and O2 -generating nanoparticles. This review aimed to discuss the role of nanotechnology in tumor oxygenation and highlight the challenges, prospective, and recent advances in this area to improve PDT outcomes. This article is categorized under: Nanotechnology Approaches to Biology > Cells at the Nanoscale Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Enhancing chemotherapy for pancreatic cancer through efficient and sustained tumor microenvironment remodeling with a fibroblast-targeted nanosystem

Pancreatic cancer (PC) carries a poor prognosis among all malignancies and poses great challenges to clinical drug accessibility due to the severely fibrotic and hypoxic tumor microenvironment (TME). Therein, cancer-associated fibroblasts (CAFs), which are extremely abundant in PC, play a key role in forming the complex PC microenvironment. Therefore, a highly efficient TME reprogramming therapeutic paradigm that can specifically inhibit CAF function is urgently needed. Herein, we successfully developed a novel CAF-tailored nanosystem (Dex-GP-DOCA, DPD) loaded with a potent anti-fibrosis flavonoid compound (Quercetin, QUE), which possesses biological responsiveness to fibroblast activation protein alpha (FAP-α), prolonged TME remodeling and enhancement of clinical chemotherapeutics. Specifically, DPD/QUE allowed for extracellular matrix (ECM) reduction, vessel normalization, hypoxia-induced drug resistance reversal, and blockade of Wnt16 paracrine in CAFs. More importantly, this chemotherapy conducive microenvironment persisted for at least 8 days following treatment with DPD/QUE. It should also be noted that the effective and prolonged microenvironment modulation induced by DPD/QUE significantly improved the chemotherapy sensitivity of Abraxane and gemcitabine, the first-line chemotherapeutic drugs for PC, with inhibition rates increasing from 37.5% and 40.0% to 87.5% and 85.2%, respectively. Overall, our CAFs-targeted nanosystem showed promising prospects for remodeling the TME and facilitating chemotherapy for refractory pancreatic cancer.

Carbonic Anhydrase IX (CAIX) Expressing Hypoxic Micro-environment Hampers CD8+ Immune Cell Infiltrate in Breast Carcinoma

BACKGROUND

Hypoxia and necrosis are common features of invasive cancer. The dynamic upregulation of carbonic anhydrase IX (CAIX), triggered by hypoxia-inducible factor 1 (HIF-1) is 1 of the mechanisms supporting cellular adaptation to hypoxia in solid tumors, including breast carcinoma. CAIX activity results in extracellular acidosis and in a profound reorganization of the tumor micro-environment, influencing biological behavior and prognosis. The main focus of our study was to evaluate the mass and distribution of the immune infiltrate, more specifically of CD8+ effector T-cells, in relation with tumoral CAIX expression.

MATERIALS AND METHODS

Formalin-fixed and paraffin-embedded breast carcinoma sections were analyzed following double immunohistochemical staining for CAIX and CD8. Scanned digital slides were evaluated for both labelings, and CD8-related signal was determined within and outside CAIX-positive tumor areas using the HistoQuant (3DHistech) image analysis software. Statistical analysis was performed using GraphPad Prism software.

RESULTS

Of the 34 breast carcinomas, 18 tested partially positive for CAIX. The remaining 16 cases were used as the CAIX-negative control group. Necrotic foci were generally associated with CAIX overexpression, and tumors exhibiting signs of necrosis had a significantly higher rate of relative CAIX expression compared with samples without necrosis (11.47±5.505 vs. without necrosis 3.765±3.5 P-value=0.0216). On the other hand, no statistically significant difference was found when comparing relative CD8+ lymphocyte counts in cases with necrosis as opposed to those where necrosis was absent (134.7±55.7 vs. 97.70±57.25; P value=0.1579). No difference in gross CD8+ T-lymphocyte infiltrate could be measured between CAIX positive and negative samples (98.48±37.32 vs. 95.99±50 P value=0.5928). However, in CAIX-expressing tumors a statistical correlation between the CD8+ T-lymphocyte infiltrate and the extent of CAIX-positive areas was observed. Within the same tumor, CD8+ T-lymphocyte counts showed a significant difference betweeen CAIX+ and CAIX- areas (13.06±9.4 vs. 135.6±62.2 P value <0.0001).

CONCLUSION

Our measurements demonstrate for the first time that tumor areas with CAIX expression potentially hamper CD8+ T-lymphocyte infiltration in breast carcinoma. The hypoxia-driven adaptive micro-environment likely interferes with the specific response to biological and immune therapies requiring intact effector T-cell response.

Hypoxia-driven metabolic reprogramming of adipocytes fuels cancer cell proliferation

Objective

Obesity increases the risk of certain cancers, especially tumours that reside close to adipose tissue (breast and ovarian metastasis in the omentum). The obesogenic and tumour micro-environment share a common pathogenic feature, oxygen deprivation (hypoxia). Here we test how hypoxia changes the metabolome of adipocytes to assist cancer cell growth.

Methods

Human and mouse breast and ovarian cancer cell lines were co-cultured with human and mouse adipocytes respectively under normoxia or hypoxia. Proliferation and lipid uptake in cancer cells were measured by commercial assays. Metabolite changes under normoxia or hypoxia were measured in the media of human adipocytes by targeted LC/MS.

Results

Hypoxic cancer-conditioned media increased lipolysis in both human and mouse adipocytes. This led to increased transfer of lipids to cancer cells and consequent increased proliferation under hypoxia. These effects were dependent on HIF1α expression in adipocytes, as mouse adipocytes lacking HIF1α showed blunted responses under hypoxic conditions. Targeted metabolomics of the human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes media revealed that culture with hypoxic-conditioned media from non-malignant mammary epithelial cells (MCF10A) can alter the adipocyte metabolome and drive proliferation of the non-malignant cells.

Conclusion

Here, we show that hypoxia in the adipose-tumour microenvironment is the driving force of the lipid uptake in both mammary and ovarian cancer cells. Hypoxia can modify the adipocyte metabolome towards accelerated lipolysis, glucose deprivation and reduced ketosis. These metabolic shifts in adipocytes could assist both mammary epithelial and cancer cells to bypass the inhibitory effects of hypoxia on proliferation and thrive.

MSOT-Guided Nanotheranostics for Synergistic Mild Photothermal Therapy and Chemotherapy to Boost Necroptosis/Apoptosis

The development of nanotheranostics for precision imaging-guided regulated cell death-mediated synergistic tumor therapy is still challenging. Herein, a novel multifunctional nanotheranostic agent, iRGD-coated maleimide-poly(ethylene glycol)-poly(lactic acid/glycolic acid)-encapsulated hydrophobic gold nanocages (AuNCs) and hydrophilic epigallocatechin gallate (EGCG) (PAuE) is developed for multispectral optoacoustic tomography (MSOT)-guided photothermal therapy (PTT) and chemotherapy. The portions of necroptotic and apoptotic tumor cells were 52.9 and 5.4%, respectively, at 6 h post-incubation after the AuNC-induced mild PTT treatment, whereas they became 14.0 and 46.1% after 24 h, suggesting that the switch of the cell death pathway is a time-dependent process. Mild PTT facilitated the release of EGCG which induces the downregulation of hypoxia-inducible factor-1 (HIF-1α) expression to enhance apoptosis at a later stage, realizing a remarkable tumor growth inhibition in vivo. Moreover, RNA sequence analyses provided insights into the significant changes in genes related to the cross-talk between necroptosis and apoptosis pathways via PAuE upon laser irradiation. In addition, the biodistribution and metabolic pathways of PAuE have been successfully revealed by 3D MSOT. Taken together, this strategy of first combination of EGCG and AuNC-based photothermal agent via triggering necroptosis/apoptosis to downregulate HIF-1α expression in a tumor environment provides a new insight into anti-cancer therapy.

A Brief Overview of the Effects of Exercise and Red Beets on the Immune System in Patients with Prostate Cancer

Research over the past few decades has focused on the use of functional ingredients such as an active lifestyle and proper diet as a treatment for many diseases in the world. Recent studies have shown a variety of health benefits for red beets and their active ingredients such as antioxidant, anti-inflammatory, anti-cancer, blood pressure and fat reduction, anti-diabetic, and anti-obesity effects. This review article examines the effects of exercise and red beet consumption and the effective mechanisms of these two interventions on cellular and molecular pathways in prostate cancer. However, there is a significant relationship between an active lifestyle and proper diet with the incidence of cancer, and the use of these natural interventions for cancer patients in the treatment protocol of avoidance patients. Furthermore, this review article attempts to examine the role and effect of exercise and beetroot nutrition on prostate cancer and provide evidence of the appropriate effects of using natural interventions to prevent, reduce, and even treat cancer in stages. In addition, we examine the molecular mechanisms of the effectiveness of exercise and beetroot consumption. Finally, the use of natural interventions such as exercising and eating beets due to their antioxidant, anti-inflammatory, and anti-cancer properties, due to the lack or low level of side effects, can be considered an important intervention for the prevention and treatment of cancer.

Carbonic anhydrase IX-targeted H-APBC nanosystem combined with phototherapy facilitates the efficacy of PI3K/mTOR inhibitor and resists HIF-1α-dependent tumor hypoxia adaptation

Background

Non-redundant properties such as hypoxia and acidosis promote tumor metabolic adaptation and limit anti-cancer therapies. The key to the adaptation of tumor cells to hypoxia is the transcriptional and stable expression of hypoxia-inducible factor-1 alpha (HIF-1α). The phosphorylation-activated tumorigenic signal PI3K/AKT/mTOR advances the production of downstream HIF-1α to adapt to tumor hypoxia. Studies have elucidated that acid favors inhibition of mTOR signal. Nonetheless, carbonic anhydrase IX (CAIX), overexpressed on membranes of hypoxia tumor cells with pH-regulatory effects, attenuates intracellular acidity, which is unfavorable for mTOR inhibition. Herein, a drug delivery nanoplatform equipped with dual PI3K/mTOR inhibitor Dactolisib (NVP-BEZ235, BEZ235) and CAIX inhibitor 4‐(2‐aminoethyl) benzene sulfonamide (ABS) was designed to mitigate hypoxic adaptation and improve breast cancer treatment.

Results

ABS and PEG-NH₂ were successfully modified on the surface of hollow polydopamine (HPDA), while BEZ235 and Chlorin e6 (Ce6) were effectively loaded with the interior of HPDA to form HPDA-ABS/PEG-BEZ235/Ce6 (H-APBC) nanoparticles. The release of BEZ235 from H-APBC in acid microenvironment could mitigate PI3K/mTOR signal and resist HIF-1α-dependent tumor hypoxia adaptation. More importantly, ABS modified on the surface of H-APBC could augment intracellular acids and enhances the mTOR inhibition. The nanoplatform combined with phototherapy inhibited orthotopic breast cancer growth while reducing spontaneous lung metastasis, angiogenesis, based on altering the microenvironment adapted to hypoxia and extracellular acidosis.

Conclusion

Taken together, compared with free BEZ235 and ABS, the nanoplatform exhibited remarkable anti-tumor efficiency, reduced hypoxia adaptation, mitigated off-tumor toxicity of BEZ235 and solved the limited bioavailability of BEZ235 caused by weak solubility.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01394-w.

Phenoxyaromatic Acid Analogues as Novel Radiotherapy Sensitizers: Design, Synthesis and Biological Evaluation

Radiotherapy is a vital approach for brain tumor treatment. The standard treatment for glioblastoma (GB) is maximal surgical resection combined with radiotherapy and chemotherapy. However, the non-sensitivity of tumor cells in the hypoxic area of solid tumors to radiotherapy may cause radioresistance. Therefore, radiotherapy sensitizers that increase the oxygen concentration within the tumor are promising for increasing the effectiveness of radiation. Inspired by hemoglobin allosteric oxygen release regulators, a series of novel phenoxyacetic acid analogues were designed and synthesized. A numerical method was applied to determine the activity and safety of newly synthesized compounds. In vitro studies on the evaluation of red blood cells revealed that compounds 19c (∆P₅₀ = 45.50 mmHg) and 19t (∆P₅₀ = 44.38 mmHg) improve the oxygen-releasing property effectively compared to positive control efaproxiral (∆P₅₀ = 36.40 mmHg). Preliminary safety evaluation revealed that 19c exhibited no cytotoxicity towards HEK293 and U87MG cells, while 19t was cytotoxic toward both cells with no selectivity. An in vivo activity assay confirmed that 19c exhibited a radiosensitization effect on orthotopically transplanted GB in mouse brains. Moreover, a pharmacokinetic study in rats showed that 19c was orally available.

Tumor Microenvironment in Breast Cancer-Updates on Therapeutic Implications and Pathologic Assessment

The tumor microenvironment (TME) in breast cancer comprises local factors, cancer cells, immune cells and stromal cells of the local and distant tissues. The interaction between cancer cells and their microenvironment plays important roles in tumor proliferation, propagation and response to therapies. There is increasing research in exploring and manipulating the non-cancerous components of the TME for breast cancer treatment. As the TME is now increasingly recognized as a treatment target, its pathologic assessment has become a critical component of breast cancer management. The latest WHO classification of tumors of the breast listed stromal response pattern/fibrotic focus as a prognostic factor and includes recommendations on the assessment of tumor infiltrating lymphocytes and PD-1/PD-L1 expression, with therapeutic implications. This review dissects the TME of breast cancer, describes pathologic assessment relevant for prognostication and treatment decision, and details therapeutic options that interacts with and/or exploits the TME in breast cancer.

Early Imaging and Molecular Changes with Neoadjuvant Bevacizumab in Stage II/III Breast Cancer

This prospective, phase II study evaluated novel biomarkers as predictors of response to bevacizumab in patients with breast cancer (BC), using serial imaging methods and gene expression analysis. Patients with primary stage II/III BC received bevacizumab 15 mg/kg (cycle 1; C1), then four cycles of neoadjuvant docetaxel doxorubicin, and bevacizumab every 3 weeks (C2-C5). Tumour proliferation and hypoxic status were evaluated using 18F-fluoro-3'-deoxy-3'-L-fluorothymidine (FLT)- and 18F-fluoromisonidazole (FMISO)-positron emission tomography (PET) at baseline, and during C1 and C5. Pre- and post-bevacizumab vascular changes were evaluated using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Molecular biomarkers were assessed using microarray analysis. A total of 70 patients were assessed for treatment efficacy. Significant decreases from baseline in tumour proliferation (FLT-PET), vascularity, and perfusion (DCE-MRI) were observed during C1 (p ≤ 0.001), independent of tumour subtype. Bevacizumab treatment did not affect hypoxic tumour status (FMISO-PET). Significant changes in the expression of 28 genes were observed after C1. Changes in vascular endothelial growth factor receptor (VEGFR)-2p levels were observed in 65 patients, with a > 20% decrease in VEGFR-2p observed in 13/65. Serial imaging techniques and molecular gene profiling identified several potentially predictive biomarkers that may predict response to neoadjuvant bevacizumab therapy in BC patients.

Chemotherapeutic effects on breast tumor hemodynamics revealed by eigenspectra multispectral optoacoustic tomography (eMSOT)

Non-invasive monitoring of hemodynamic tumor responses to chemotherapy could provide unique insights into the development of therapeutic resistance and inform therapeutic decision-making in the clinic.

Methods: Here, we examined the longitudinal and dynamic effects of the common chemotherapeutic drug Taxotere on breast tumor (KPL-4) blood volume and oxygen saturation using eigenspectra multispectral optoacoustic tomography (eMSOT) imaging over a period of 41 days. Tumor vascular function was assessed by dynamic oxygen-enhanced eMSOT (OE-eMSOT). The obtained in vivo optoacoustic data were thoroughly validated by ex vivo cryoimaging and immunohistochemical staining against markers of vascularity and hypoxia.

Results: We provide the first preclinical evidence that prolonged treatment with Taxotere causes a significant drop in mean whole tumor oxygenation. Furthermore, application of OE-eMSOT showed a diminished vascular response in Taxotere-treated tumors and revealed the presence of static blood pools, indicating increased vascular permeability.

Conclusion: Our work has important translational implications and supports the feasibility of eMSOT imaging for non-invasive assessment of tumor microenvironmental responses to chemotherapy.

Discovery of Antimetastatic Chiral Ionone Alkaloid Derivatives Targeting HIF-1α/VEGF/VEGFR2 Pathway

Novel chiral ionone alkaloid derivatives were synthesized and their antimetastatic effects were evaluated in human breast cancer cells using chemotaxis assay. Compared with positive control LY294002, a PI3 K inhibitor, derivatives 10 a, 11 a, 11 c, 11 g, 11 j, 11 k and 11 w exhibited significant inhibitory effects against cancer cell migration. Especially, the IC₅₀ for compound 11 g was as low as 0.035±0.004 μM. Further investigations on compound 11 g revealed that it could exert inhibitory effects on the adhesion, migration and invasion of MDA-MB-231 cells. The mechanisms for the antitumor metastatic effects of 11 g might be through the inhibition of HIF-1α/VEGF/VEGFR2/Akt pathway, which suppressed the downstream signaling molecules, including Akt1/mTOR/p70S6K and Akt2/PKCζ/integrin β1 pathways. Taken together, chiral ionone alkaloid derivative 11 g has the potential to be developed into an antitumor metastatic agent for breast cancer.

Hypoxia in Breast Cancer-Scientific Translation to Therapeutic and Diagnostic Clinical Applications

Breast cancer has been the leading cause of female cancer deaths for decades. Intratumoral hypoxia, mainly caused by structural and functional abnormalities in microvasculature, is often associated with a more aggressive phenotype, increased risk of metastasis and resistance to anti-malignancy treatments. The response of cancer cells to hypoxia is ascribed to hypoxia-inducible factors (HIFs) that activate the transcription of a large battery of genes encoding proteins promoting primary tumor vascularization and growth, stromal cell recruitment, extracellular matrix remodeling, cell motility, local tissue invasion, metastasis, and maintenance of the cancer stem cell properties. In this review, we summarized the role of hypoxia specifically in breast cancer, discuss the prognostic and predictive value of hypoxia factors, potential links of hypoxia and endocrine resistance, cancer hypoxia measurements, further involved mechanisms, clinical application of hypoxia-related treatments and open questions.

Intratumor heterogeneity of breast cancer detected by epialleles shows association with hypoxic microenvironment

Rationale: In breast cancer, high intratumor DNA methylation heterogeneity can lead to drug-resistant, metastasis and poor prognosis of tumors, which increases the complexity of cancer diagnosis and treatment. However, most studies are limited to average DNA methylation level of individual CpGs and ignore heterogeneous DNA methylation patterns of cell subpopulations within the tumor. Thus, quantifying the variability in DNA methylation pattern in sequencing reads is valuable for understanding intratumor heterogeneity. Methods: We performed Reduced Representation Bisulfite Sequencing and RNA sequencing for tumor core and tumor periphery regions within one breast tumor. By developing a method named "epialleJS" based on Jensen-Shannon divergence, we detected the differential epialleles between tumor core and tumor periphery (CPDEs). We then explored the correlation between intratumor methylation heterogeneity and hypoxic microenvironment in TCGA breast cancer cohort. Results: More than 70% of CPDEs had higher epipolymorphism in tumor core than tumor periphery, and these CPDEs had lower methylation in tumor core. The CPDEs with lower methylation in tumor core may associate with hypoxic tumor microenvironment. Moreover, we identified a signature of five hypoxia-related DNA methylation markers which can predict the prognosis of breast cancer patients, including a CpG site cg15190451 in gene SLC16A5. Furthermore, immunohistochemical analysis confirmed that the expression of SLC16A5 was associated with clinicopathological characteristics and survival of breast cancer patients. Conclusions: The analysis of intratumor DNA methylation heterogeneity based on epialleles reveals that disordered methylation patterns in tumor core are associated with hypoxic microenvironment, which provides a framework for understanding biological heterogeneous behavior and guidance for developing effective treatment schemes for breast cancer patients.

Links between Inflammation and Postoperative Cancer Recurrence

Despite complete resection, cancer recurrence frequently occurs in clinical practice. This indicates that cancer cells had already metastasized from their organ of origin at the time of resection or had circulated throughout the body via the lymphatic and vascular systems. To obtain this potential for metastasis, cancer cells must undergo essential and intrinsic processes that are supported by the tumor microenvironment. Cancer-associated inflammation may be engaged in cancer development, progression, and metastasis. Despite numerous reports detailing the interplays between cancer and its microenvironment via the inflammatory network, the status of cancer-associated inflammation remains difficult to recognize in clinical settings. In the current paper, we reviewed clinical reports on the relevance between inflammation and cancer recurrence after surgical resection, focusing on inflammatory indicators and cancer recurrence predictors according to cancer type and clinical indicators.

A dendrimer-functionalized turn-on fluorescence probe based on enzyme-activated debonding feature of azobenzene linkage

The hypoxic feature of tumors has led to researchers developing hypoxia-activated prodrugs and probes that leverage oxidoreductases overexpressed in tumor tissues.

Hypoxia re-programs 2'-O-Me modifications on ribosomal RNA

Hypoxia is one of the critical stressors encountered by various cells of the human body under diverse pathophysiologic conditions including cancer and has profound impacts on several metabolic and physiologic processes. Hypoxia prompts internal ribosome entry site (IRES)-mediated translation of key genes, such as VEGF, that are vital for tumor progression. Here, we describe that hypoxia remarkably upregulates RNA Polymerase I activity. We discovered that in hypoxia, rRNA shows a different methylation pattern compared to normoxia. Heterogeneity in ribosomes due to the diversity of ribosomal RNA and protein composition has been postulated to generate “specialized ribosomes” that differentially regulate translation. We find that in hypoxia, a sub-set of differentially methylated ribosomes recognizes the VEGF-C IRES, suggesting that ribosomal heterogeneity allows for altered ribosomal functions in hypoxia.

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Chronic hypoxia stimulates RNA Pol I activity

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In hypoxia, a pool of specialized rRNA translates VEGFC IRES

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Hypoxia changes 2′-O-Me modification - epitranscriptomic marks on rRNA

Hypoxia-induced changes in intragenic DNA methylation correlate with alternative splicing in breast cancer

The tumor microenvironment is marked by gradients in the level of oxygen and nutrients, with oxygen levels reaching a minimum at the core of the tumor, a condition known as tumor hypoxia. Mediated by members of the HIF family of transcription factors, hypoxia leads to a more aggressive tumor phenotype by transactivation of several genes as well as reprogramming of pre-mRNA splicing. Intragenic DNA methylation, which is known to affect alternative splicing in cancer, could be one of several reasons behind the changes in splicing patterns under hypoxia. Here, we have tried to establish a correlation between intragenicDNA methylation and alternative usage of exons in tumor hypoxia. First, we have generated a customhypoxia signature consisting of 34 genes that are upregulated under hypoxia and are direct targets of HIF-1α. Using this gene expression signature, we have successfully stratified publicly available breast cancer patient samples into hypoxia positive and hypoxia negative groups followed by mining of differentially spliced isoforms between these groups. The Hypoxia Hallmark signature from MSigDB was also used independently to stratify the same tumor samples into hypoxic and normoxic.We found that 821 genes were showing differential splicing between samples stratified using a custom signature, whereas, 911 genes were showing differential splicing between samples stratified using the MSigDB signature. Finally, we performed multiple correlation tests between the methylation levels (β) of microarray probes located within 1 kilo base pairs of isoform-specific exons using those exons' expression levels in the same patient samples in which the methylation level was recorded. We found that the expression level of one of the exons ofDHX32 and BICD2 significantly correlated with the methylation levels, and we were also able to predict patient survival (p-value: 0.02 for DHX32 and 0.0024 for BICD2). Our findings provide new insights into the potential functional role of intragenic DNA methylation in modulating alternative splicing during hypoxia.

The modern views of the clinical, morphological and molecular biological predictors of breast cancer sensitivity to chemotherapy

In the treatment of breast cancer, the neoadjuvant chemotherapy is vitally important and the evaluation of its effectiveness is crucial for determining the further therapy treatment, as well as the prognosis of the disease. This review provides current data of the physical, instrumental, morphological, molecular biology and genetics analysis used for the estimation of the neoadjuvant treatment effectiveness. Thus, review discusses the data concerning association of the disease peculiarities with the efficient therapeutic response to neoadjuvant chemotherapy including characteristics of patients (age, status of regional lymph nodes, presence of the lymphovascular invasion) and tumors (size, histological type, degree of differentiation, severity of the lymphoid tumor infiltration, molecular biological and genetic peculiarities). Particular attention is paid to such a promising predictive marker of the breast cancer response to chemotherapy as the level of tissue hypoxia. This section discusses the currently known mechanisms that might enable the effect of tissue hypoxia on the sensitivity of the tumor to drug treatment. The prospects for the use of a comprehensive analysis of predictive markers of the effectiveness of chemotherapeutic treatment are discussed.

Bioengineering the Oxygen-Deprived Tumor Microenvironment Within a Three-Dimensional Platform for Studying Tumor-Immune Interactions

Oxygen deprivation within tumors is one of the most prevalent causes of resilient cancer cell survival and increased immune evasion in breast cancer (BCa). Current in vitro models do not adequately mimic physiological oxygen levels relevant to breast tissue and its tumor-immune interactions. In this study, we propose an approach to engineer a three-dimensional (3D) model (named 3D engineered oxygen, 3D-O) that supports the growth of BCa cells and generates physio- and pathophysiological oxygen levels to understand the role of oxygen availability in tumor-immune interactions. BCa cells (MDA-MB-231 and MCF-7) were embedded into plasma-derived 3D-O scaffolds that reflected physio- and pathophysiological oxygen levels relevant to the healthy and cancerous breast tissue. BCa cells grown within 3D-O scaffolds were analyzed by flow cytometry, confocal imaging, immunohistochemistry/immunofluorescence for cell proliferation, extracellular matrix protein expression, and alterations in immune evasive outcomes. Exosome secretion from 3D-O scaffolds were evaluated using the NanoSight particle analyzer. Peripheral blood mononuclear cells were incorporated on the top of 3D-O scaffolds and the difference in tumor-infiltrating capabilities as a result of different oxygen content were assessed by flow cytometry and confocal imaging. Lastly, hypoxia and Programmed death-ligand 1 (PD-L1) inhibition were validated as targets to sensitize BCa cells in order to overcome immune evasion. Low oxygen-induced adaptations within 3D-O scaffolds validated known tumor hypoxia characteristics such as reduced BCa cell proliferation, increased extracellular matrix protein expression, increased extracellular vesicle secretion and enhanced immune surface marker expression on BCa cells. We further demonstrated that low oxygen in 3D-O scaffolds significantly influence immune infiltration. CD8+ T cell infiltration was impaired under pathophysiological oxygen levels and we were also able to establish that hypoxia and PD-L1 inhibition re-sensitized BCa cells to cytotoxic CD8+ T cells. Bioengineering the oxygen-deprived BCa tumor microenvironment in our engineered 3D-O physiological and tumorous scaffolds supported known intra-tumoral hypoxia characteristics allowing the study of the role of oxygen availability in tumor-immune interactions. The 3D-O model could serve as a promising platform for the evaluation of immunological events and as a drug-screening platform tool to overcome hypoxia-driven immune evasion.

Influence of Fibroblasts on Mammary Gland Development, Breast Cancer Microenvironment Remodeling, and Cancer Cell Dissemination

The stromal microenvironment regulates mammary gland development and tumorigenesis. In normal mammary glands, the stromal microenvironment encompasses the ducts and contains fibroblasts, the main regulators of branching morphogenesis. Understanding the way fibroblast signaling pathways regulate mammary gland development may offer insights into the mechanisms of breast cancer (BC) biology. In fact, the unregulated mammary fibroblast signaling pathways, associated with alterations in extracellular matrix (ECM) remodeling and branching morphogenesis, drive breast cancer microenvironment (BCM) remodeling and cancer growth. The BCM comprises a very heterogeneous tissue containing non-cancer stromal cells, namely, breast cancer-associated fibroblasts (BCAFs), which represent most of the tumor mass. Moreover, the different components of the BCM highly interact with cancer cells, thereby generating a tightly intertwined network. In particular, BC cells activate recruited normal fibroblasts in BCAFs, which, in turn, promote BCM remodeling and metastasis. Thus, comparing the roles of normal fibroblasts and BCAFs in the physiological and metastatic processes, could provide a deeper understanding of the signaling pathways regulating BC dissemination. Here, we review the latest literature describing the structure of the mammary gland and the BCM and summarize the influence of epithelial-mesenchymal transition (EpMT) and autophagy in BC dissemination. Finally, we discuss the roles of fibroblasts and BCAFs in mammary gland development and BCM remodeling, respectively.

Overexpression of bHLH domain of HIF-1 failed to inhibit the HIF-1 transcriptional activity in hypoxia

Background

Hypoxia inducible factor-1 (HIF-1) is considered as the most activated transcriptional factor in response to low oxygen level or hypoxia. HIF-1 binds the hypoxia response element (HRE) sequence in the promoter of different genes, mainly through the bHLH domain and activates the transcription of genes, especially those involved in angiogenesis and EMT. Considering the critical role of bHLH in binding HIF-1 to the HRE sequence, we hypothesized that bHLH could be a promising candidate to be targeted in hypoxia condition.

Methods

We inserted an inhibitory bHLH (ibHLH) domain in a pIRES2-EGFP vector and transfected HEK293T cells with either the control vector or the designed construct. The ibHLH domain consisted of bHLH domains of both HIF-1a and Arnt, capable of competing with HIF-1 in binding to HRE sequences. The transfected cells were then treated with 200 µM of cobalt chloride (CoCl₂) for 48 h to induce hypoxia. Real-time PCR and western blot were performed to evaluate the effect of ibHLH on the genes and proteins involved in angiogenesis and EMT.

Results

Hypoxia was successfully induced in the HEK293T cell line as the gene expression of VEGF, vimentin, and β-catenin were significantly increased after treatment of untransfected HEK293T cells with 200 µM CoCl₂. The gene expression of VEGF, vimentin, and β-catenin and protein level of β-catenin were significantly decreased in the cells transfected with either control or ibHLH vectors in hypoxia. However, ibHLH failed to be effective on these genes and the protein level of β-catenin, when compared to the control vector. We also observed that overexpression of ibHLH had more inhibitory effect on gene and protein expression of N-cadherin compared to the control vector. However, it was not statistically significant.

Conclusion

bHLH has been reported to be an important domain involved in the DNA binding activity of HIF. However, we found that targeting this domain is not sufficient to inhibit the endogenous HIF-1 transcriptional activity. Further studies about the function of critical domains of HIF-1 are necessary for developing a specific HIF-1 inhibitor.

Functionalized Carbon Nanostructures Versus Drug Resistance: Promising Scenarios in Cancer Treatment

Carbon nanostructures (CN) are emerging valuable materials for the assembly of highly engineered multifunctional nanovehicles for cancer therapy, in particular for counteracting the insurgence of multi-drug resistance (MDR). In this regard, carbon nanotubes (CNT), graphene oxide (GO), and fullerenes (F) have been proposed as promising materials due to their superior physical, chemical, and biological features. The possibility to easily modify their surface, conferring tailored properties, allows different CN derivatives to be synthesized. Although many studies have explored this topic, a comprehensive review evaluating the beneficial use of functionalized CNT vs G or F is still missing. Within this paper, the most relevant examples of CN-based nanosystems proposed for MDR reversal are reviewed, taking into consideration the functionalization routes, as well as the biological mechanisms involved and the possible toxicity concerns. The main aim is to understand which functional CN represents the most promising strategy to be further investigated for overcoming MDR in cancer.

Hypoxic environment may enhance migration/penetration of endocrine resistant MCF7- derived breast cancer cells through monolayers of other non-invasive cancer cells in vitro

The response of cancer cells to hypoxic conditions found within the interior of a tumor mass is mediated through the hypoxia inducible factor (HIF) cascade and is thought to promote metastasis. However, given their distant proximity from blood vessels as compared to normoxic cells at the vascularised tumor periphery, it is uncertain if these cells can migrate through the tumor mass to gain access. Hypoxia was simulated by exposure to cobalt chloride or deferoxamine in normal (MCF10A) and cancerous [estrogen receptor (ER)−ve (pII), and ER +ve (YS1.2/ EII)] cells. In this report, HIF1α expression and localization was measured using western blotting, ELISA, and immunofluorescence, cell proliferation by MTT assay, motility and invasion by wound healing, live cell imaging, matrigel and co-culture in chambered slides. We found that the expression and nuclear translocation of HIF1α was significantly elevated by hypoxia, which inhibited cell proliferation, but significantly increased motility of pII cells and their penetration into and through a dense layer of adjacent EII cells, as well as their selective emergence out of a co-culture. These data suggest that endocrine resistant pII cancer cells, having undergone epithelial to mesenchymal transition are able to penetrate through other cell layers, with possible enhancement in response to hypoxia.

Necrosis in the Tumor Microenvironment and Its Role in Cancer Recurrence

Cancer recurrence is one of the most imminent problems in the current world of medicine, and it is responsible for most of the cancer-related death rates worldwide. Long-term administration of anticancer cytotoxic drugs may act as a double-edged sword, as necrosis may lead to renewed cancer progression and treatment resistance. The lack of nutrients, coupled with the induced hypoxia, triggers cell death and secretion of signals that affect the tumor niche. Many efforts have been made to better understand the contribution of hypoxia and metabolic stress to cancer progression and resistance, but mostly with respect to inflammation. Here we provide an overview of the direct anticancer effects of necrotic signals, which are not necessarily mediated by inflammation and the role of DAMPs (damage-associated molecular patterns) on the formation of a pro-cancerous environment.

Effects of Far-infrared Ray on Temozolomide-treated Glioma in Rats

BACKGROUND/AIM

Malignant glioma is a rapidly progressive primary brain cancer. The aim of the study was to investigate the effect of far-infrared ray (FIR) on temozolomide (TMZ)-treated glioma in rats.

MATERIALS AND METHODS

Male, 8-week old, Fischer 344 inbred rats with glioma were randomly divided into three study groups (20 rats in each group). The control group received saline only once daily for 5 days. The TMZ group received TMZ (30 mg/kg) once daily for 5 days. The TMZ plus FIR group received TMZ (30 mg/kg) once daily for 5 days and infrared-c irradiation of 40 min twice daily for 4 weeks. The relative tumor fold and the expression of hypoxia-induced factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) were compared using one-way ANOVA at the end of study.

RESULTS

The relative tumor fold of the TMZ+FIR group was significantly higher compared to the control group, and was borderline higher compared to the TMZ group at Day 7. The relative tumor fold of TMZ+FIR group was significantly higher compared to the control group and the TMZ group at Days 14, 21 and 28. HIF-1α expression of TMZ+FIR group was borderline higher compared to the control group at Day 28. The VEGF expression of TMZ+FIR group was significantly higher compared to the control group and the TMZ group at Day 28.

CONCLUSION

FIR might increase the growth of glioma under TMZ treatment in rats possibly via increasing VEGF expression, but not HIF-1α expression.

Melatonin regulates tumor aggressiveness under acidosis condition in breast cancer cell lines

Breast cancer progression is composed of multiple steps that are influenced by tumor cell adaptations to survive under acidic conditions in the tumor microenvironment. Regulation of this cell survival behavior is a promising strategy to avoid cancer development. Melatonin is a natural hormone produced and secreted by the pineal gland capable of modulating different biological pathways in cancer. Although the anti-cancer effects of melatonin are currently widespread, its role in the acid tumor microenvironment remains poorly understood. The aim of the present study was to investigate the effect of low pH (6.7) on human breast cancer cell lines MCF-7 and MDA-MB-231, and the effectiveness of melatonin in acute acidosis survival mechanisms. Cell viability was measured by a MTT assay and the protein expression of glucose transporter (GLUT)-1, Ki-67 and caspase-3 was evaluated by immunocytochemical (ICC) analysis following low pH media and melatonin treatment. In both cell lines the viability was decreased after melatonin treatment (1 mM) under acidosis conditions for 24 h. ICC analysis showed a significant increase in GLUT-1 and Ki-67 expression at pH 6.7, and a decrease after treatment with melatonin for 12 and 24 h. The low pH media decreased the expression of caspase-3, which was increased after melatonin treatment for 12 and 24 h. Overall, the results of the present study revealed melatonin treatment increases apoptosis, as indicated by changes in caspase-3, and decreases proliferation, indicated by changes to Ki-67, and GLUT-1 protein expression under acute acidosis conditions in breast cancer cell lines.

Tissue necrosis and its role in cancer progression

Great efforts have been made in revealing the mechanisms governing cancer resistance and recurrence. The in-situ effects of cell death, caused by hypoxia and metabolic stress, were largely studied in association with inflammation. However, in this work, we focused on the direct effects of necrosis on cancer promotion and on the tumor microenvironment. The conditions leading to cell necrosis, upon nutrient and oxygen deprivation, were recapitulated in-vitro and were used to generate samples for computational proteomic analysis. Under these conditions, we identified clusters of enriched pathways that may be involved in tumor resistance, leading to cancer recurrence. We show that the content of necrotic cells enhances angiogenesis and proliferation of endothelial cells, induces vasculature, as well as increases migration, invasion, and cell-cell interactions. In-vivo studies, where MDA-MB-231 xenografts were exposed to necrotic lysates, resulted in an increase in both proliferation and angiogenesis. Histological analysis of tumor tissues revealed high expression levels of key mediators that were identified by proteomic analysis. Moreover, when cells were injected systemically, coupled with necrotic lysates, a higher number of large lesions was detected in the lung. Finally, using xenografts, we demonstrated that combining an antagonist of a necrotic signal with an anticancer treatment potentiates the prolonged therapeutic effect. This approach suggests a paradigm shift in which targeting late necrotic-secreted factors may increase survival and enhance the efficacy of anticancer therapy.

Functional role of circular RNAs in cancer development and progression

Circular RNAs (circRNAs) are a large class of endogenously expressed non-coding RNAs formed by covalently closed loops through back-splicing. High throughput sequencing technologies have identified thousands of circRNAs with high sequence conservation and cell type specific expression in eukaryotes. CircRNAs play multiple important roles in cellular physiology functioning as miRNA sponges, transcriptional regulators, RBP binding molecules, templates for protein translation, and immune regulators. In a clinical context, circRNAs expression is correlated with patient's clinicopathological features in cancers including breast, liver, gastric, colorectal, and lung cancer. Additionally, distinct properties of circRNAs, such as high stability, exonuclease resistance, and existence in body fluids, show promising role for circRNAs as molecular biomarkers for tumor diagnosis, non-invasive monitoring, prognosis, and therapeutic intervention. Therefore, it is critical to further understand the molecular mechanism underlying circRNAs interaction in tumors and the recent progress of this RNA species in cancer development. In this review, we provide a detailed description of biological functions, molecular role of circRNAs in different cancers, and its potential role as biomarkers in a clinical context.

Crosstalk between Notch, HIF-1α and GPER in Breast Cancer EMT

The Notch signaling pathway acts in both physiological and pathological conditions, including embryonic development and tumorigenesis. In cancer progression, diverse mechanisms are involved in Notch-mediated biological responses, including angiogenesis and epithelial-mesenchymal-transition (EMT). During EMT, the activation of cellular programs facilitated by transcriptional repressors results in epithelial cells losing their differentiated features, like cell–cell adhesion and apical–basal polarity, whereas they gain motility. As it concerns cancer epithelial cells, EMT may be consequent to the evolution of genetic/epigenetic instability, or triggered by factors that can act within the tumor microenvironment. Following a description of the Notch signaling pathway and its major regulatory nodes, we focus on studies that have given insights into the functional interaction between Notch signaling and either hypoxia or estrogen in breast cancer cells, with a particular focus on EMT. Furthermore, we describe the role of hypoxia signaling in breast cancer cells and discuss recent evidence regarding a functional interaction between HIF-1α and GPER in both breast cancer cells and cancer-associated fibroblasts (CAFs). On the basis of these studies, we propose that a functional network between HIF-1α, GPER and Notch may integrate tumor microenvironmental cues to induce robust EMT in cancer cells. Further investigations are required in order to better understand how hypoxia and estrogen signaling may converge on Notch-mediated EMT within the context of the stroma and tumor cells interaction. However, the data discussed here may anticipate the potential benefits of further pharmacological strategies targeting breast cancer progression.

The effects of intravoxel contrast agent diffusion on the analysis of DCE-MRI data in realistic tissue domains

PURPOSE

Quantitative evaluation of dynamic contrast enhanced MRI (DCE-MRI) allows for estimating perfusion, vessel permeability, and tissue volume fractions by fitting signal intensity curves to pharmacokinetic models. These compart mental models assume rapid equilibration of contrast agent within each voxel. However, there is increasing evidence that this assumption is violated for small molecular weight gadolinium chelates. To evaluate the error introduced by this invalid assumption, we simulated DCE-MRI experiments with volume fractions computed from entire histological tumor cross-sections obtained from murine studies.

METHODS

A 2D finite element model of a diffusion-compensated Tofts-Kety model was developed to simulate dynamic T₁ signal intensity data. Digitized histology slices were segmented into vascular (v_p ), cellular and extravascular extracellular (v_e ) volume fractions. Within this domain, K^trans (the volume transfer constant) was assigned values from 0 to 0.5 min^-1 . A representative signal enhancement curve was then calculated for each imaging voxel and the resulting simulated DCE-MRI data analyzed by the extended Tofts-Kety model.

RESULTS

Results indicated parameterization errors of -19.1% ± 10.6% in K^trans , -4.92% ± 3.86% in v_e , and 79.5% ± 16.8% in v_p for use of Gd-DTPA over 4 tumor domains.

CONCLUSION

These results indicate a need for revising the standard model of DCE-MRI to incorporate a correction for slow diffusion of contrast agent. Magn Reson Med 80:330-340, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Inhibition of pH regulation as a therapeutic strategy in hypoxic human breast cancer cells

Hypoxic cancer cells exhibit resistance to many therapies. This study compared the therapeutic effect of targeting the pH regulatory proteins (CAIX, NHE1 and V-ATPase) that permit cancer cells to adapt to hypoxic conditions, using both 2D and 3D culture models. Drugs targeting CAIX, NHE1 and V-ATPase exhibited anti-proliferative effects in MCF-7, MDA-MB-231 and HBL-100 breast cancer cell lines in 2D. Protein and gene expression analysis in 2D showed that CAIX was the most hypoxia-inducible protein of the 3 targets. However, the expression of CAIX differed between the 3 cell lines. This difference in CAIX expression in hypoxia was consistent with a varying activity of FIH-1 between the cell lines. 3D expression analysis demonstrated that both CAIX and NHE1 were up-regulated in the hypoxic areas of multicellular tumor spheroids. However, the induction of CAIX expression in hypoxia was again cell line dependent. 3D invasion assays conducted with spheroids showed that CAIX inhibition significantly reduced the invasion of cells. Finally, the capability of both NHE1 and CAIX inhibitors to combine effectively with irradiation was exhibited in clonogenic assays. Proteomic-mass-spectrometric analysis indicated that CAIX inhibition might be combining with irradiation through stimulating apoptotic cell death. Of the three proteins, CAIX represents the target with the most promise for the treatment of breast cancer.

PDGFR-β inhibitor slows tumor growth but increases metastasis in combined radiotherapy and Endostar therapy

BACKGROUND

Pericytes are pivotal mural cells of blood vessels and play an essential role in coordinating the function of endothelial cells. Previous studies demonstrated that Endostar, a novel endostatin targeting endothelial cells, can enhance the effect of radiotherapy (RT). The present study addressed whether inhibiting pericytes could potentially improve the efficacy of combined RT and Endostar therapy.

METHODS

Platelet-derived growth factor beta-receptor inhibitor (CP673451) was chosen to inhibit pericytes and RT (12 Gy) was delivered. Lewis lung carcinoma-bearing C57BL/6 mice were randomized into 3 groups: RT, RT + Endo, and RT + Endo + CP673451. Subsequently, tumor microvessel density (MVD), pericyte coverage, tumor hypoxia, and lung metastasis were monitored at different time points following different therapies.

RESULTS

Compared to the other two groups, RT + Endo + CP673451 treatment markedly inhibited tumor growth with no improvement in the overall survival. Further analyses clarified that in comparison to RT alone, RT + Endo significantly reduced the tumor MVD, with a greater decrease noted in the RT + Endo + CP673451 group. However, additional CP673451 accentuated tumor hypoxia and enhanced the pulmonary metastasis in the combined RT and Endostar treatment.

CONCLUSIONS

Tumor growth can be further suppressed by pericyte inhibitor; however, metastases are potentially enhanced. More in-depth studies are warranted to confirm the potential benefits and risks of anti-pericyte therapy.

Assembly of breast cancer heterotypic spheroids on hyaluronic acid coated surfaces

Drug screening is currently demanding for realistic models that are able to reproduce the structural features of solid tumors. 3D cell culture systems, namely spheroids, emerged as a promising approach to provide reliable results during drug development. So far, liquid overlay technique (LOT) is one of the most used methods for spheroids assembly. It comprises cellular aggregation due to their limited adhesion to certain biomaterials, like agarose. However, researchers are currently improving this technique in order to obtain spheroids on surfaces that mimic cancer extracellular matrix (ECM), since cell-ECM interactions modulate cells behavior and their drug resistance profile. Herein, hyaluronic acid (HA) coated surfaces were used, for the first time, for the production of reproducible heterotypic breast cancer spheroids. The obtained results revealed that it is possible to control the size, shape, and number of spheroids gotten per well by changing the HA concentration and the number of cells initially seeded in each well. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1346-1357, 2017.

Hypoxic pathobiology of breast cancer metastasis

Dissemination of breast cancer cells (BCCs) to distant sites (metastasis) is the ultimate cause of mortality in patients with breast cancer. Hypoxia (low O₂) is a microenvironmental hallmark of most solid cancers arising as a mismatch between cellular O₂ consumption and supply. Hypoxic selection of BCCs triggers molecular and cellular adaptations dependent upon hypoxia-inducible factors (HIFs), a family of evolutionarily conserved transcriptional activators that coordinate the expression of numerous genes controlling each step of the metastatic process. In this review, we summarize current advances in the understanding of HIF-driven molecular mechanisms that promote BCC metastatic dissemination and patient mortality. In addition, we discuss the clinical and therapeutic implications of HIF targeting in breast cancers.

Quantification of hypoxia-related gene expression as a potential approach for clinical outcome prediction in breast cancer

Breast cancers are solid tumors frequently characterized by regions with low oxygen concentrations. Cellular adaptations to hypoxia are mainly determined by “hypoxia inducible factors” that mediate transcriptional modifications involved in drug resistance and tumor progression leading to metastasis and relapse occurrence. In this study, we investigated the prognostic value of hypoxia-related gene expression in breast cancer. A systematic review was conducted to select a set of 45 genes involved in hypoxia signaling pathways and breast tumor progression. Gene expression was quantified by RT-qPCR in a retrospective series of 32 patients with invasive ductal carcinoma. Data were analyzed in relation to classical clinicopathological criteria and relapse occurrence. Coordinated overexpression of selected genes was observed in high-grade and HER2+ tumors. Hierarchical cluster analysis of gene expression significantly segregated relapsed patients (p = 0.008, Chi² test). All genes (except one) were up-regulated and six markers were significantly expressed in tumors from recurrent patients. The expression of this 6-gene set was used to develop a basic algorithm for identifying recurrent patients according to a risk score of relapse. Analysis of Kaplan-Meier relapse-free survival curves allowed the definition of a threshold score of 2 (p = 0.021, Mantel-Haenszel test). The risk of recurrence was increased by 40% in patients with a high score. In addition to classical prognostic factors, we showed that hypoxic markers have potential prognostic value for outcome and late recurrence prediction, leading to improved treatment decision-making for patients with early-stage invasive breast cancer. It will be necessary to validate the clinical relevance of this prognostic approach through independent studies including larger prospective patient cohorts.

Increased chemosensitivity and radiosensitivity of human breast cancer cell lines treated with novel functionalized single-walled carbon nanotubes

Hypoxia is a major cause of treatment resistance in breast cancer. Single-walled carbon nanotubes (SWCNTs) exhibit unique properties that make them promising candidates for breast cancer treatment. In the present study, a new functionalized single-walled carbon nanotube carrying oxygen was synthesized; it was determined whether this material could increase chemosensitivity and radiosensitivity of human breast cancer cell lines, and the underlying mechanisms were investigated. MDA-MB-231 cells growing in folic acid (FA) free medium, MDA-MB-231 cells growing in medium containing FA and ZR-75-1 cells were treated with chemotherapy drugs or radiotherapy with or without tombarthite-modified-FA-chitosan (R-O2-FA-CHI)-SWCNTs under hypoxic conditions, and the cell viability was determined by water-soluble tetrazolium salts-1 assay. The cell surviving fractions were determined by colony forming assay. Cell apoptosis induction was monitored by flow cytometry. Expression of B-cell lymphoma 2 (Bcl-2), survivin, hypoxia-inducible factor 1-α (HIF-1α), multidrug resistance-associated protein 1 (MRP-1), P-glycoprotein (P-gp), RAD51 and Ku80 was monitored by western blotting. The novel synthesized R-O2-FA-CHI-SWCNTs were able to significantly enhance the chemosensitivity and radiosensitivity of human breast cancer cell lines and the material exhibited its expected function by downregulating the expression of Bcl-2, survivin, HIF-1α, P-gp, MRP-1, RAD51 and Ku80.

Ki67/SATB1 ratio is an independent prognostic factor of overall survival in patients with early hormone receptor-positive invasive ductal breast carcinoma

Biological diversity of breast cancer presents challenges for personalized therapy and necessitates multiparametric approaches to understand and manage the disease. Multiple protein biomarkers tested by immunohistochemistry (IHC), followed by digital image analysis and multivariate statistics of the data, have been shown to be effective in exploring latent profiles of tumor tissue immunophenotype. In this study, based on tissue microarrays of 107 patients with hormone receptor (HR) positive invasive ductal breast carcinoma, we investigated the prognostic value of the integrated immunophenotype to predict overall survival (OS) of the patients. A set of 10 IHC markers (ER, PR, HER2, Ki67, AR, BCL2, HIF-1α, SATB1, p53, and p16) was used. The main factor of the variance was characterized by opposite loadings of ER/PR/AR/BCL2 and Ki67/HIF-1α; it was associated with histological grade but did not predict OS. The second factor was driven by SATB1 expression along with moderate positive HIF-1α and weak negative Ki67 loadings. Importantly, this factor did not correlate with any clinicopathologic parameters, but was an independent predictor of better OS. Ki67 and SATB1 did not reach statistical significance as single predictors; however, high Ki67/SATB1 ratio was an independent predictor of worse OS. In addition, our data indicate potential double prognostic meaning of HIF-1α expression in breast cancer and necessitate focused studies, taking into account the immunophenotype interactions and tissue heterogeneity aspects.

HIF isoforms have divergent effects on invasion, metastasis, metabolism and formation of lipid droplets

Cancer cells adapt to hypoxia by the stabilization of hypoxia inducible factor (HIF)-α isoforms that increase the transcription of several genes. Among the genes regulated by HIF are enzymes that play a role in invasion, metastasis and metabolism. We engineered triple (estrogen receptor/progesterone receptor/HER2/neu) negative, invasive MDA-MB-231 and SUM149 human breast cancer cells to silence the expression of HIF-1α, HIF-2α or both isoforms of HIF-α. We determined the metabolic consequences of HIF silencing and the ability of HIF-α silenced cells to invade and degrade the extracellular matrix (ECM) under carefully controlled normoxic and hypoxic conditions. We found that silencing HIF-1α alone was not sufficient to attenuate invasiveness in both MDA-MB-231 and SUM149 cell lines. Significantly reduced metastatic burden was observed in single (HIF-1α or HIF-2α) and double α-isoform silenced cells, with the reduction most evident when both HIF-1α and HIF-2α were silenced in MDA-MB-231 cells. HIF-2α played a major role in altering cell metabolism. Lipids and lipid droplets were significantly reduced in HIF-2α and double silenced MDA-MB-231 and SUM149 cells, implicating HIF in their regulation. In addition, lactate production and glucose consumption were reduced. These results suggest that in vivo, cells in or near hypoxic regions are likely to be more invasive. The data indicate that targeting HIF-1α alone is not sufficient to attenuate invasiveness, and that both HIF-1α and HIF-2α play a role in the metastatic cascade in these two cell lines.

Three-Dimensional Breast Cancer Models Mimic Hallmarks of Size-Induced Tumor Progression

Tumor size is strongly correlated with breast cancer metastasis and patient survival. Increased tumor size contributes to hypoxic and metabolic gradients in the solid tumor and to an aggressive tumor phenotype. Thus, it is important to develop three-dimensional (3D) breast tumor models that recapitulate size-induced microenvironmental changes and, consequently, natural tumor progression in real time without the use of artificial culture conditions or gene manipulations. Here, we developed size-controlled multicellular aggregates ("microtumors") of subtype-specific breast cancer cells by using non-adhesive polyethylene glycol dimethacrylate hydrogel microwells of defined sizes (150-600 μm). These 3D microtumor models faithfully represent size-induced microenvironmental changes, such as hypoxic gradients, cellular heterogeneity, and spatial distribution of necrotic/proliferating cells. These microtumors acquire hallmarks of tumor progression in the same cell lines within 6 days. Of note, large microtumors of hormone receptor-positive cells exhibited an aggressive phenotype characterized by collective cell migration and upregulation of mesenchymal markers at mRNA and protein level, which was not observed in small microtumors. Interestingly, triple-negative breast cancer (TNBC) cell lines did not show size-dependent upregulation of mesenchymal markers. In conclusion, size-controlled microtumor models successfully recapitulated clinically observed positive association between tumor size and aggressive phenotype in hormone receptor-positive breast cancer while maintaining clinically proven poor correlation of tumor size with aggressive phenotype in TNBC. Such clinically relevant 3D models generated under controlled experimental conditions can serve as precise preclinical models to study mechanisms involved in breast tumor progression as well as antitumor drug effects as a function of tumor progression. Cancer Res; 76(13); 3732-43. ©2016 AACR.

Breast cancer carcinoma-associated fibroblasts differ from breast fibroblasts in immunological and extracellular matrix regulating pathways

Tumor stroma has been recently shown to play a crucial role in the development of breast cancer. Since the origin of the stromal cells in the tumor is unknown, we have examined differences and similarities between three stromal cell types of mesenchymal origin, namely carcinoma associated fibroblasts from breast tumor (CAFs), fibroblasts from normal breast area (NFs) and bone marrow derived mesenchymal stromal cells (MSCs). In a microarray analysis, immunological, developmental and extracellular matrix -related pathways were over-represented in CAFs when compared to NFs (p<0.001). Under hypoxic conditions, the expression levels of pyruvate dehydrogenase kinase-1 (PDK1) and pyruvate dehydrogenase kinase-4 (PDK4) were lower in CAFs when compared to NFs (fold changes 0.6 and 0.4, respectively). In normoxia, when compared to NFs, CAFs displayed increased expression of glucose transporter 1 (GLUT-1) and PDK1 (fold changes 1.5 and 1.3, respectively). With respect to the assessed surface markers, only CD105 was expressed differently in MSCs when compared to fibroblasts, being more often expressed on MSCs. Cells with myofibroblast features were present in both NF and CAF samples. We conclude, that CAFs differ distinctly from NFs at the gene expression level, this hypothesis was also tested in silico for other available gene expression data.

The CCL2 chemokine is a negative regulator of autophagy and necrosis in luminal B breast cancer cells

Luminal A and B breast cancers are the most prevalent forms of breast cancer diagnosed in women. Compared to luminal A breast cancer patients, patients with luminal B breast cancers experience increased disease recurrence and lower overall survival. The mechanisms that regulate the luminal B subtype remain poorly understood. The chemokine CCL2 is overexpressed in breast cancer, correlating with poor patient prognosis. The purpose of this study was to determine the role of CCL2 expression in luminal B breast cancer cells. Breast tissues, MMTV-PyVmT and MMTV-Neu transgenic mammary tumors forming luminal B-like lesions, were immunostained for CCL2 expression. To determine the role of CCL2 in breast cancer cells, CCL2 gene expression was silenced in mammary tumor tissues and cells using TAT cell-penetrating peptides non-covalently cross linked to siRNAs (Ca-TAT/siRNA). CCL2 expression was examined by ELISA and flow cytometry. Cell growth and survival were analyzed by flow cytometry, immunocytochemistry, and fluorescence microscopy. CCL2 expression was significantly increased in luminal B breast tumors, MMTV- PyVmT and MMTV-Neu mammary tumors, compared or normal breast tissue or luminal A breast tumors. Ca-TAT delivery of CCL2 siRNAs significantly reduced CCL2 expression in PyVmT mammary tumors, and decreased cell proliferation and survival. CCL2 gene silencing in PyVmT carcinoma cells or BT474 luminal B breast cancer cells decreased cell growth and viability associated with increased necrosis and autophagy. CCL2 expression is overexpressed in luminal B breast cancer cells and is important for regulating cell growth and survival by inhibiting necrosis and autophagy.