Hypoxia-mediated drug resistance in breast cancers

Targeted proteomics addresses selectivity and complexity of protein degradation by autophagy

Macroautophagy/autophagy is a constitutively active catabolic lysosomal degradation pathway, often found dysregulated in human diseases. It is often considered to act in a cytoprotective manner and is commonly upregulated in cells undergoing stress. Its initiation is regulated at the protein level and does not require de novo protein synthesis. Historically, autophagy has been regarded as nonselective; however, it is now clear that different stimuli can lead to the selective degradation of cellular components via selective autophagy receptors (SARs). Due to its selective nature and the existence of multiple degradation pathways potentially acting in concert, monitoring of autophagy flux, i.e. selective autophagy-dependent protein degradation, should address this complexity. Here, we introduce a targeted proteomics approach monitoring abundance changes of 37 autophagy-related proteins covering process-relevant proteins such as the initiation complex and the Atg8-family protein lipidation machinery, as well as most known SARs. We show that proteins involved in autophagosome biogenesis are upregulated and spared from degradation under autophagy-inducing conditions in contrast to SARs, in a cell-line dependent manner. Classical bulk stimuli such as nutrient starvation mainly induce degradation of ubiquitin-dependent soluble SARs and not of ubiquitin-independent, membrane-bound SARs. In contrast, treatment with the iron chelator deferiprone leads to the degradation of ubiquitin-dependent and -independent SARs linked to mitophagy and reticulophagy/ER-phagy. Our approach is automatable and supports large-scale screening assays paving the way to (pre)clinical applications and monitoring of specific autophagy flux.Abbreviation: AMBRA1: autophagy and beclin 1 regulator 1; ATG: autophagy related; BafA1: bafilomycin A1; BNIP1: BCL2 interacting protein 1; BNIP3: BCL2 interacting protein 3; BNIP3L/NIX: BCL2 interacting protein 3-like; CALCOCO2/NDP52: calcium binding and coiled-coil domain 2; CCPG1: cell cycle progression 1; CV: coefficients of variations; CCCP: carbonyl cyanide m-chlorophenyl hydrazone; DFP: deferiprone; ER: endoplasmic reticulum; FKBP8: FKBP prolyl isomerase 8; GABARAPL: GABA type A receptor associated protein like; LC: liquid chromatography; LOD: limit of detection; LOQ: limit of quantification; MAP1LC3: microtubule associated protein 1 light chain 3; MS: mass spectrometry; NCOA4: nuclear receptor coactivator 4; NBR1: NBR1 autophagy cargo receptor; NUFIP1: nuclear FMR1 interacting protein 1; OPTN: optineurin; PHB2: prohibitin 2; PNPLA2/ATGL: patatin like phospholipase domain containing 2; POI: protein of interest; PTM: posttranslational modification; PRM: parallel reaction monitoring; RB1CC1/FIP200: RB1 inducible coiled-coil 1; RETREG1/FAM134B: reticulophagy regulator 1; RPS6KB1: ribosomal protein S6 kinase B1; RTN3: reticulon 3; SARs: selective autophagy receptors; SQSTM1/p62: sequestosome 1; STBD1: starch binding domain 1; TAX1BP1: Tax1 binding protein 1; TFEB: transcription factor EB; TNIP1: TNFAIP3 interacting protein 1; TOLLIP: toll interacting protein; ULK1: unc-51 like autophagy activating kinase 1; WBP2: WW domain binding protein 2; WDFY3/Alfy: WD repeat and FYVE domain containing 3; WIPI2: WD repeat domain, phosphoinositide interacting 2.

Aptamer functionalized hypoxia-potentiating agent and hypoxia-inducible factor inhibitor combined with hypoxia-activated prodrug for enhanced tumor therapy

Triple-negative breast cancer (TNBC) is the most lethal subtype of breast cancer. Hypoxia-activated prodrugs (HAPs) have shown promise as potential therapeutic agents for TNBC. While increasing hypoxia levels may promote the HAP activation, it raises concerns regarding HIF1α-dependent drug resistance. It is desirable to develop a targeted approach that enhances tumor hypoxia for HAP activation without promoting HIF1α-dependent drug resistance in TNBC treatment. Herein, we proposed a multi-responsive carrier-free self-assembled nanomedicine named AQ4N@CA4T1ASO. This nanomedicine first targeted tumors by the TNBC-targeting aptamers (T1), and then disassembled in the reductive and acidic conditions within tumors. The released Combretastatin 4 (CA4) could exacerbate hypoxia, thereby promoting the conversion of inactive Banoxantrone (AQ4N) to its active form, AQ4. Simultaneously, the released antisense oligonucleotide (ASO) could attenuate hypoxia-induced HIF1α mRNA expression, thereby sensitizing the tumor to chemotherapy. Overall, this smart nanomedicine represents a profound targeted therapy strategy, combining "hypoxia-potentiating, hypoxia-activated, chemo-sensitization" approaches for TNBC treatment. In vivo study demonstrated significant suppression of tumor growth, highlighting the promising potential of this nanomedicine for future clinical translation.

Small Molecule Inhibitors of Arylamine N-Acetyltransferase 1 Attenuate Cellular Respiration

Arylamine N-acetyltransferase 1 (NAT1) expression has been shown to attenuate mitochondrial function, suggesting it is a promising drug target in diseases of mitochondrial dysfunction. Here, several second-generation naphthoquinones have been investigated as small molecule inhibitors of NAT1. The results show that the compounds inhibit both in vitro and in whole cells. A lead compound (Cmp350) was further investigated for its ability to alter mitochondrial metabolism in MDA-MB-231 cells. At concentrations that inhibited NAT1 by over 85%, no overt toxicity was observed. Moreover, the inhibitor decreased basal respiration and reserve respiratory capacity without affecting ATP production. Cells treated with Cmp350 were almost exclusively dependent on glucose as a fuel source. We postulate that Cmp350 is an excellent lead compound for the development of NAT1-targeted inhibitors as both experimental tools and therapeutics in the treatment of hypermetabolic diseases such as amyotrophic lateral sclerosis, cancer cachexia, and sepsis.

Hypoxia-inducible factor in breast cancer: role and target for breast cancer treatment

Globally, breast cancer stands as the most prevalent form of cancer among women. The tumor microenvironment of breast cancer often exhibits hypoxia. Hypoxia-inducible factor 1-alpha, a transcription factor, is found to be overexpressed and activated in breast cancer, playing a pivotal role in the anoxic microenvironment by mediating a series of reactions. Hypoxia-inducible factor 1-alpha is involved in regulating downstream pathways and target genes, which are crucial in hypoxic conditions, including glycolysis, angiogenesis, and metastasis. These processes significantly contribute to breast cancer progression by managing cancer-related activities linked to tumor invasion, metastasis, immune evasion, and drug resistance, resulting in poor prognosis for patients. Consequently, there is a significant interest in Hypoxia-inducible factor 1-alpha as a potential target for cancer therapy. Presently, research on drugs targeting Hypoxia-inducible factor 1-alpha is predominantly in the preclinical phase, highlighting the need for an in-depth understanding of HIF-1α and its regulatory pathway. It is anticipated that the future will see the introduction of effective HIF-1α inhibitors into clinical trials, offering new hope for breast cancer patients. Therefore, this review focuses on the structure and function of HIF-1α, its role in advancing breast cancer, and strategies to combat HIF-1α-dependent drug resistance, underlining its therapeutic potential.

Research progress on the role of reactive oxygen species in the initiation, development and treatment of breast cancer

According to international cancer data, breast cancer (BC) is the leading type of cancer in women. Although significant progress has been made in treating BC, metastasis and drug resistance continue to be the primary causes of mortality for many patients. Reactive oxygen species (ROS) play a dual role in vivo: normal levels can maintain the body's normal physiological function; however, high levels of ROS below the toxicity threshold can lead to mtDNA damage, activation of proto-oncogenes, and inhibition of tumor suppressor genes, which are important causes of BC. Differences in the production and regulation of ROS in different BC subtypes have important implications for the development and treatment of BC. ROS can also serve as an important intracellular signal transduction factor by affecting the antioxidant system, activating MAPK and PI3K/AKT, and other signal pathways to regulate cell cycle and change the relationship between cells and the activity of metalloproteinases, which significantly impacts the metastasis of BC. Hypoxia in the BC microenvironment increases ROS production levels, thereby inducing the expression of hypoxia inducible factor-1α (HIF-1α) and forming "ROS- HIF-1α-ROS" cycle that exacerbates BC development. Many anti-BC therapies generate sufficient toxic ROS to promote cancer cell apoptosis, but because the basal level of ROS in BC cells exceeds that of normal cells, this leads to up-regulation of the antioxidant system, drug efflux, and apoptosis inhibition, rendering BC cells resistant to the drug. ROS crosstalks with tumor vessels and stromal cells in the microenvironment, increasing invasiveness and drug resistance in BC.

Metal-Organic Framework-Mediated Synergistic Hypoxia-Activated Chemo-Immunotherapy Induced by High Intensity Focused Ultrasound for Enhanced Cancer Theranostics

High intensity focused ultrasound (HIFU) has attracted considerable attention as a noninvasive, efficient, and economic therapeutic modality for solid tumors. However, HIFU surgery has its intrinsic limitation in completely ablating tumors, leading to residual tumor tissue. Furthermore, the severely hypoxic environment ensuring after surgery can exacerbate the unrestricted proliferation and metabolism of residual tumor cells, leading to tumor recurrence and metastasis. To address these limitations, a versatile HIFU-specific metal-organic framework nanosystem (called ADMOFs) is developed by coordinating hypoxia-activated prodrug AQ4N, Mn2+, and DOX based on the postoperative response to changes in the tumor microenvironment. ADMOFs loaded with AQ4N/Mn2+ exhibited remarkable tumor-targeting behavior in vivo and enhanced photoacoustic/magnetic resonance imaging effects, enabling more accurate guidance for HIFU surgery. After surgery, the ADMOFs exploited the severely hypoxic tumor environment induced by HIFU, overcoming hypoxia-associated drug resistance, and inducing immunogenic cell death. Finally, it effectively inhibited tumor growth and eliminated lung metastasis. Transcriptome studies revealed that this strategy significantly up-regulated genes involved in apoptosis, cell cycle, and HIF-1 signaling pathway while downregulating genes related to tumor proliferation and metastasis. These findings suggest that combining hypoxia-activated chemo-immunotherapy with HIFU is a promising strategy for enhancing cancer theranostics.

Recent Contributions of Mass Spectrometry-Based "Omics" in the Studies of Breast Cancer

Breast cancer (BC) is one of the most heterogeneous groups of cancer. As every biotype of BC is unique and presents a particular "omic" signature, they are increasingly characterized nowadays with novel mass spectrometry (MS) strategies. BC therapeutic approaches are primarily based on the two features of human epidermal growth factor receptor 2 (HER2) and estrogen receptor (ER) positivity. Various strategic MS implementations are reported in studies of BC also involving data independent acquisitions (DIAs) of MS which report novel differential proteomic, lipidomic, proteogenomic, phosphoproteomic, and metabolomic characterizations associated with the disease and its therapeutics. Recently many "omic" studies have aimed to identify distinct subsidiary biotypes for diagnosis, prognosis, and targets of treatment. Along with these, drug-induced-resistance phenotypes are characterized by "omic" changes. These identifying aspects of the disease may influence treatment outcomes in the near future. Drug quantifications and characterizations are also done regularly and have implications in therapeutic monitoring and in drug efficacy assessments. We report these studies, mentioning their implications toward the understanding of BC. We briefly provide the MS instrumentation principles that are adopted in such studies as an overview with a brief outlook on DIA-MS strategies. In all of these, we have chosen a model cancer for its revelations through MS-based "omics".

Hypoxia-induced miR-181a-5p up-regulation reduces epirubicin sensitivity in breast cancer cells through inhibiting EPDR1/TRPC1 to activate PI3K/AKT signaling pathway

Breast carcinoma (BC) ranks as a predominant malignancy and constitutes the second principal cause of mortality among women globally. Epirubicin stands as the drug of choice for BC therapeutics. Nevertheless, the emergence of chemoresistance has significantly curtailed its therapeutic efficacy. The resistance mechanisms to Epirubicin remain not entirely elucidated, yet they are conjectured to stem from diminished tumor vascular perfusion and resultant hypoxia consequent to Epirubicin administration. In our investigation, we meticulously scrutinized the Gene Expression Omnibus database for EPDR1, a gene implicated in hypoxia and Epirubicin resistance in BC. Subsequently, we delineated the impact of EPDR1 on cellular proliferation, motility, invasive capabilities, and interstitial-related proteins in BC cells, employing methodologies such as the CCK-8 assay, Transwell assay, and western blot analysis. Our research further unveiled that hypoxia-induced miR-181a-5p orchestrates the regulation of BC cell duplication, migration, invasion, and interstitial-related protein expression via modulation of EPDR1. In addition, we identified TRPC1, a gene associated with EPDR1 expression in BC, and substantiated that EPDR1 influences BC cellular dynamics through TRPC1-mediated modulation of the PI3K/AKT signaling cascade. Our findings underscore the pivotal role of EPDR1 in the development of BC. EPDR1 was found to be expressed at subdued levels in BC tissues, Epirubicin-resistant BC cells, and hypoxic BC cells. The overexpression of EPDR1 curtailed BC cell proliferation, motility, invasiveness, and the expression of interstitial-related proteins. At a mechanistic level, the overexpression of hypoxia-induced miR-181a-5p was observed to inhibit the EPDR1/TRPC1 axis, thereby activating the PI3K/AKT signaling pathway and diminishing the sensitivity to Epirubicin in BC cells. In summation, our study demonstrates that the augmentation of hypoxia-induced miR-181a-5p diminishes Epirubicin sensitivity in BC cells by attenuating EPDR1/TRPC1 expression, thereby invigorating the PI3K/AKT signaling pathway. This exposition offers a theoretical foundation for the application of Epirubicin in BC therapy, marking a significant contribution to the existing body of oncological literature.

Biomaterial-Based Responsive Nanomedicines for Targeting Solid Tumor Microenvironments

Solid tumors are composed of a highly complex and heterogenic microenvironment, with increasing metabolic status. This environment plays a crucial role in the clinical therapeutic outcome of conventional treatments and innovative antitumor nanomedicines. Scientists have devoted great efforts to conquering the challenges of the tumor microenvironment (TME), in respect of effective drug accumulation and activity at the tumor site. The main focus is to overcome the obstacles of abnormal vasculature, dense stroma, extracellular matrix, hypoxia, and pH gradient acidosis. In this endeavor, nanomedicines that are targeting distinct features of TME have flourished; these aim to increase site specificity and achieve deep tumor penetration. Recently, research efforts have focused on the immune reprograming of TME in order to promote suppression of cancer stem cells and prevention of metastasis. Thereby, several nanomedicine therapeutics which have shown promise in preclinical studies have entered clinical trials or are already in clinical practice. Various novel strategies were employed in preclinical studies and clinical trials. Among them, nanomedicines based on biomaterials show great promise in improving the therapeutic efficacy, reducing side effects, and promoting synergistic activity for TME responsive targeting. In this review, we focused on the targeting mechanisms of nanomedicines in response to the microenvironment of solid tumors. We describe responsive nanomedicines which take advantage of biomaterials' properties to exploit the features of TME or overcome the obstacles posed by TME. The development of such systems has significantly advanced the application of biomaterials in combinational therapies and in immunotherapies for improved anticancer effectiveness.

The cell stress and immunity cycle in cancer: Toward next generation of cancer immunotherapy

The cellular stress and immunity cycle is a cornerstone of organismal homeostasis. Stress activates intracellular and intercellular communications within a tissue or organ to initiate adaptive responses aiming to resolve the origin of this stress. If such local measures are unable to ameliorate this stress, then intercellular communications expand toward immune activation with the aim of recruiting immune cells to effectively resolve the situation while executing tissue repair to ameliorate any damage and facilitate homeostasis. This cellular stress-immunity cycle is severely dysregulated in diseased contexts like cancer. On one hand, cancer cells dysregulate the normal cellular stress responses to reorient them toward upholding growth at all costs, even at the expense of organismal integrity and homeostasis. On the other hand, the tumors severely dysregulate or inhibit various components of organismal immunity, for example, by facilitating immunosuppressive tumor landscape, lowering antigenicity, and increasing T-cell dysfunction. In this review we aim to comprehensively discuss the basis behind tumoral dysregulation of cellular stress-immunity cycle. We also offer insights into current understanding of the regulators and deregulators of this cycle and how they can be targeted for conceptualizing successful cancer immunotherapy regimen.

Addressing Genetic Tumor Heterogeneity, Post-Therapy Metastatic Spread, Cancer Repopulation, and Development of Acquired Tumor Cell Resistance

The concept of post-therapy metastatic spread, cancer repopulation and acquired tumor cell resistance (M-CRAC) rationalizes tumor progression because of tumor cell heterogeneity arising from post-therapy genetic damage and subsequent tissue repair mechanisms. Therapeutic strategies designed to specifically address M-CRAC involve tissue editing approaches, such as low-dose metronomic chemotherapy and the use of transcriptional modulators with or without targeted therapies. Notably, tumor tissue editing holds the potential to treat patients, who are refractory to or relapsing (r/r) after conventional chemotherapy, which is usually based on administering a maximum tolerable dose of a cytostatic drugs. Clinical trials enrolling patients with r/r malignancies, e.g., non-small cell lung cancer, Hodgkin's lymphoma, Langerhans cell histiocytosis and acute myelocytic leukemia, indicate that tissue editing approaches could yield tangible clinical benefit. In contrast to conventional chemotherapy or state-of-the-art precision medicine, tissue editing employs a multi-pronged approach targeting important drivers of M-CRAC across various tumor entities, thereby, simultaneously engaging tumor cell differentiation, immunomodulation, and inflammation control. In this review, we highlight the M-CRAC concept as a major factor in resistance to conventional cancer therapies and discusses tissue editing as a potential treatment.

Semisynthesis and anti-cancer properties of novel honokiol derivatives in human nasopharyngeal carcinoma CNE-2Z cells

In this study, 21 new honokiol derivatives were synthesised, and their anti-cancer properties were investigated. Among these, compound 1g exhibited the most potent cytotoxic activity against human nasopharyngeal carcinoma CNE-2Z cells, human gastric cancer SGC7901 cells, human breast cancer MCF-7 cells, and mouse leydig testicular cancer I-10 lines with IC50 values of 6.04, 7.17, 6.83, and 5.30 μM, respectively. Compared to the parental compound, 1g displayed up to 5.18-fold enhancement of the cytotoxic effect on CNE-2Z cells. We further demonstrated that 1g inhibited cell growth, suppressed migration and invasion, and induced apoptosis of CNE-2Z cells by down-regulating HIF-1α, MMP-2, MMP-9, Bcl-2, Akt and up-regulating Bax protein levels. Transfection of CNE-2Z cells with HIF-1α siRNA reduced cell migration and invasion. In addition, in vivo experiments confirmed that 1g inhibited tumour growth in CNE-2Z cell-xenografted nude mice with low toxicity. Thus, our data suggested that 1g was a potent and safe lead compound for nasopharyngeal carcinoma therapy.

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

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

Comprehensive analysis of resistance mechanisms to EGFR-TKIs and establishment and validation of prognostic model

PURPOSE

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) are the first-line therapy for patients with lung adenocarcinoma (LUAD) harboring activating EGFR mutations. However, the emergence of drug resistance to EGFR-TKIs remains a critical obstacle for successful treatment and is associated with poor patient outcomes. The overarching objective of this study is to apply bioinformatics tools to gain insights into the mechanisms underlying resistance to EGFR-TKIs and develop a robust predictive model.

METHODS

The genes associated with gefitinib resistance in the LUAD cell Gene Expression Omnibus (GEO) database were identified using gene chip expression data. Functional enrichment analysis, gene set enrichment analysis (GSEA), and immune infiltration analysis were performed to comprehensively explore the mechanism of gefitinib resistance. Furthermore, a GRRG_score was constructed by integrating genes related to LUAD prognosis from The Cancer Genome Atlas (TCGA) database with the screened Gefitinib Resistant Related differentially expressed genes (GRRDEGs) using the Least Absolute Shrinkage and Selection Operator (LASSO) and Cox regression analyses. Furthermore, we conducted an in-depth analysis of the tumor microenvironment (TME) features and their association with immune infiltration between different GRRG_score groups. A prognostic model for LUAD was developed based on the GRRG_score and validated. The HPA database was used to validate protein expression. The CTR-DB database was utilized to validate the results of drug therapy prediction based on the relevant genes.

RESULTS

A total of 110 differentially expression genes were identified. Pathway enrichment analysis of DEGs showed that the differentially expressed genes were mainly enriched in Mucin type O-glycan biosynthesis, Cytokine-cytokine receptor interaction, Sphingolipid metabolism. Gene set enrichment analysis showed that biological processes strongly correlated with gefitinib resistance were cell proliferation and immune-related pathways, EPITHELIAL_MESENCHYMAL_TRANSITION, APICAL_SURFACE, and APICAL_JUNCTION were highly expressed in the drug-resistant group; KRAS_SIGNALING_DN, HYPOXIA, and HEDGEHOG_SIGNALING were highly expressed in the drug-resistant group. The GRRG_score was constructed based on the expression levels of 13 genes, including HSPA2, ATP8B3, SPOCK1, EIF6, NUP62CL, BCAR3, PCSK9, NT5E, FLNC, KRT8, FSCN1, ANGPTL4, and ID1. We further screened and validated two key genes, namely, NUP62CL and KRT8, which exhibited predictive value for both prognosis and drug resistance.

CONCLUSIONS

Our study identified several novel GRRDEGs and provided insight into the underlying mechanisms of gefitinib resistance in LUAD. Our results have implications for developing more effective treatment strategies and prognostic models for LUAD patients.

Strategic Design of Conquering Hypoxia in Tumor for Advanced Photodynamic Therapy

Photodynamic therapy (PDT), with its advantages of high targeting, minimally invasive, and low toxicity side effects, has been widely used in the clinical therapy of various tumors, especially superficial tumors. However, the tumor microenvironment (TME) presents hypoxia due to the low oxygen (O2 ) supply caused by abnormal vascularization in neoplastic tissues and high O2 consumption induced by the rapid proliferation of tumor cells. The efficacy of oxygen-consumping PDT can be hampered by a hypoxic TME. To address this problem, researchers have been developing advanced nanoplatforms and strategies to enhance the therapeutic effect of PDT in tumor treatment. This review summarizes recent advanced PDT therapeutic strategies to against the hypoxic TME, thus enhancing PDT efficacy, including increasing O2 content in TME through delivering O2 to the tumors and in situ generations of O2 ; decreasing the O2 consumption during PDT by design of type I photosensitizers. Moreover, recent synergistically combined therapy of PDT and other therapeutic methods such as chemotherapy, photothermal therapy, immunotherapy, and gas therapy is accounted for by addressing the challenging problems of mono PDT in hypoxic environments, including tumor resistance, proliferation, and metastasis. Finally, perspectives of the opportunities and challenges of PDT in future clinical research and translations are provided.

A PDA-Functionalized 3D Lung Scaffold Bioplatform to Construct Complicated Breast Tumor Microenvironment for Anticancer Drug Screening and Immunotherapy

2D cell culture occupies an important place in cancer progression and drug discovery research. However, it limitedly models the "true biology" of tumors in vivo. 3D tumor culture systems can better mimic tumor characteristics for anticancer drug discovery but still maintain great challenges. Herein, polydopamine (PDA)-modified decellularized lung scaffolds are designed and can serve as a functional biosystem to study tumor progression and anticancer drug screening, as well as mimic the tumor microenvironment. PDA-modified scaffolds with strong hydrophilicity and excellent cell compatibility can promote cell growth and proliferation. After 96 h treatment with 5-FU, cisplatin, and DOX, higher survival rates in PDA-modified scaffolds are observed compared to nonmodified scaffolds and 2D systems. The E-cadhesion formation, HIF-1α-mediated senescence decrease, and tumor stemness enhancement can drive drug resistance and antitumor drug screening of breast cancer cells. Moreover, there is a higher survival rate of CD45+ /CD3+ /CD4+ /CD8+ T cells in PDA-modified scaffolds for potential cancer immunotherapy drug screening. This PDA-modified tumor bioplatform will supply some promising information for studying tumor progression, overcoming tumor resistance, and screening tumor immunotherapy drugs.

LINC01116 affects patient survival differently and is dissimilarly expressed in ER+ and ER- breast cancer samples

BACKGROUND

Breast cancer is the most commonly detected cancer and one of the leading causes of cancer mortality. Emerging evidence supports that aberrant expression of lncRNAs is correlated with tumor progression and various aspects of tumor development.

AIM

This study aimed to evaluate the expression pattern of LINC01116 in breast cancer tissues and investigate the impact of LINC01116 on patients' survival.

METHODS AND RESULTS

Microarray and qRT-PCR data analysis were performed, and the KM-plotter database was used in this study. In addition, the gain of function approach was performed to examine the effect of LINC01116 on breast cancer cells in-vitro. The results exhibited that LINC01116 is meaningfully upregulated in the ER+ tumor specimens compared to the ER- ones. Also, relative to normal tissues, the expression of LINC01116 in ER+ and ER- tumor tissues significantly increased and decreased, respectively. ROC curve analysis revealed the power of LINC01116 in distinguishing ER+ from ER- samples. Additionally, the Kaplan-Meier survival analysis showed that the LINC01116 expression positively correlates with survival probability in all as well as ER+ patients. However, this correlation was negative in ER- patients. Furthermore, our results showed that the overexpression of LINC01116 induces TGF-β signaling in ER- cells (MDA-MB-231), and microarray data analysis revealed that LINC01116 is significantly upregulated in 17β-Estradiol treated MCF7 cells.

CONCLUSION

In conclusion, our results suggest that LINC01116 can be a potential biomarker in distinguishing ER+ and ER- tissues and has different effects on patients' survival based on ER status by affecting TGF-β and ER signaling.

A novel cross-communication of HIF-1α and HIF-2α with Wnt signaling in TNBC and influence of hypoxic microenvironment in the formation of an organ-on-chip model of breast cancer

The microenvironment role is very important in cancer development. The epithelial-mesenchymal transition of the cancer cells depends upon specific signaling and microenvironmental conditions, such as hypoxic conditions. The crosstalk between hypoxia and Wnt signaling through some molecular mechanism in TNBC is related. Cross-communication between hypoxia and Wnt signaling in cancer cells is known, but the detailed mechanism in TNBC is unknown. This review includes the role of the hypoxia microenvironment in TNBC and the novel crosstalk of the Wnt signaling and hypoxia. When targeted, the new pathway and crosstalk link may be a solution for metastatic TNBC and chemoresistance. The microenvironment influences cancer's metastasis, which changes from person to person. Therefore, organ-on-a-chip is a very novel model to test the drugs clinically before going for human trials, focusing on personalized medications can be done. The effect of the hypoxia microenvironment on breast cancer stem cells is still unknown. Apart from all the published papers, this paper mainly focuses only on the hypoxic microenvironment and its association with the growth of TNBC. The medicines or small proteins, drugs, mimics, and inhibitors targeting wnt and hypoxia genes are consolidated in this review paper.

CMA mediates resistance in breast cancer models

BACKGROUND

Breast cancer (BC) is the most common malignancy in women and the second leading cause of cancer-related death; chemoresistance is still a clinical challenge mainly because of the different molecular features of this kind of tumour. Doxorubicin (Doxo) is widely used despite its adverse effects and the common onset of resistance. Chaperone-Mediated Autophagy (CMA) has been identified as an important mechanism through which chemotherapeutics can exert their cytotoxic effects and, in this context, LAMP-2A, the key player of CMA, can be a useful biomarker.

METHODS

A cohort of patients and breast cancer cells have been screened for Doxo effect and CMA activation by analysing the LAMP-2A level. Molecular silencing has been used to clarify CMA role in BC responsiveness to treatments. Low Doxo doses were combined with other drugs (TMZ or PX-478, a HIF-1α inhibitor) to evaluate their cytotoxic ability and their role in modulating CMA.

RESULTS

In this paper, we showed that CMA is an important mechanism mediating the responsiveness of breast cancer cell to different treatments (Doxo and TMZ, as suggested by triple negative cells that are TMZ-resistant and fails to activate CMA). The LAMP-2A expression level was specific for different cell lines and patient-derived tumour subtypes, and was also useful in discriminating patients for their survival rates. Moreover, molecular silencing or pharmacological blockage of HIF-1α activity reverted BC resistance to TMZ. The combination of low-dose Doxo with TMZ or PX-478 showed that the drug associations have synergistic behaviours.

CONCLUSION

Here, we demonstrated that CMA activity exerts a fundamental role in the responsiveness to different treatments, and LAMP-2A can be proposed as a reliable prognostic biomarker in breast cancer. In this context, HIF-1α, a potential target of CMA, can also be assessed as a valuable therapeutic target in BC in view of identifying new, more efficient and less toxic therapeutic drug combinations. Moreover, the possibility to combine Doxo with other drugs acting on different but coherent molecular targets could help overcome resistance and open the way to a decrease in the dose of the single drugs.

Exosome-mediated crosstalk between tumor cells and innate immune cells: implications for cancer progression and therapeutic strategies

The increasing number of cancer-associated deaths despite the substantial improvement in diagnosis and treatment has sparked discussions on the need for novel biomarkers and therapeutic strategies for cancer. Exosomes have become crucial players in tumor development and progression, largely due to the diverse nature of their cargo content released to recipient cells. Importantly, exosome-mediated crosstalk between tumor and stromal cells is essential in reprogramming the tumor microenvironment to facilitate tumor progression. As a result, exosomes have gradually become a marker for the early diagnosis of many diseases and an important tool in drug delivery systems. However, the precise mechanisms by which exosomes participate in tumor progression remain elusive, multifaceted, and a double-edged sword, thus requiring further clarification. The available evidence suggests that exosomes can facilitate communication between innate immune cells and tumor cells to either support or inhibit tumor progression. Herein, this review focused on exosome-mediated intercellular communication between tumor cells and macrophages, neutrophils, mast cells, monocytes, dendritic cells, and natural killer cells. Specifically, how such intercellular communication affects tumor progression has been described. It has also been discussed that, depending on their cargo, exosomes can suppress or promote tumor cell progression. In addition, the potential application of exosomes and strategies to target exosomes in cancer treatment has been comprehensively discussed.

Interplay between LncRNAs and microRNAs in Breast Cancer

(1) Although long noncoding RNAs (lncRNAs) are known to be precursors of microRNAs (miRNAs), they frequently act as competing endogoneous RNAs (ceRNAs), yet still their interplay with miRNA is not well known. However, their interaction with miRNAs may result in the modulation of miRNA action. (2) To determine the contribution of these RNA molecules in tumor resistance to chemotherapeutic drugs, it is essential to consider not only the oncogenic and tumor suppressive function of miRNAs but also the impact of lncRNAs on miRNAs. Therefore, we performed an extensive search in different databases including PubMed. (3) The present study concerns the interplay between lncRNAs and miRNAs in the regulatory post-transcriptional network and their impact on drugs used in the treatment of breast cancer. (4) Consideration of this interplay may improve the search for new drugs to circumvent chemoresistance.

The Promise of Nanoparticles-Based Radiotherapy in Cancer Treatment

Radiation has been utilized for a long time for the treatment of cancer patients. However, radiotherapy (RT) has many constraints, among which non-selectivity is the primary one. The implementation of nanoparticles (NPs) with RT not only localizes radiation in targeted tissue but also provides significant tumoricidal effect(s) compared to radiation alone. NPs can be functionalized with both biomolecules and therapeutic agents, and their combination significantly reduces the side effects of RT. NP-based RT destroys cancer cells through multiple mechanisms, including ROS generation, which in turn damages DNA and other cellular organelles, inhibiting of the DNA double-strand damage-repair system, obstructing of the cell cycle, regulating of the tumor microenvironment, and killing of cancer stem cells. Furthermore, such combined treatments overcome radioresistance and drug resistance to chemotherapy. Additionally, NP-based RT in combined treatments have shown synergistic therapeutic benefit(s) and enhanced the therapeutic window. Furthermore, a combination of phototherapy, i.e., photodynamic therapy and photothermal therapy with NP-based RT, not only reduces phototoxicity but also offers excellent therapeutic benefits. Moreover, using NPs with RT has shown promise in cancer treatment and shown excellent therapeutic outcomes in clinical trials. Therefore, extensive research in this field will pave the way toward improved RT in cancer treatment.

Nanotechnological strategies to increase the oxygen content of the tumor

Hypoxia is a negative prognostic indicator of solid tumors, which not only changes the survival state of tumors and increases their invasiveness but also remarkably reduces the sensitivity of tumors to treatments such as radiotherapy, chemotherapy and photodynamic therapy. Thus, developing therapeutic strategies to alleviate tumor hypoxia has recently been considered an extremely valuable target in oncology. In this review, nanotechnological strategies to elevate oxygen levels in tumor therapy in recent years are summarized, including (I) improving the hypoxic tumor microenvironment, (II) oxygen delivery to hypoxic tumors, and (III) oxygen generation in hypoxic tumors. Finally, the challenges and prospects of these nanotechnological strategies for alleviating tumor hypoxia are presented.

NRP1 promotes prostate cancer progression via modulating EGFR-dependent AKT pathway activation

Prostate cancer (PCa) is the most common malignant tumor with a high global incidence in males. The mechanism underlying PCa progression is still not clear. This study observed that NRP1 was highly expressed in PCa and associated with poor prognosis in PCa patients. Functionally, NRP1 depletion attenuated the proliferation and migration ability of PCa cells in vitro and in vivo, while NRP1 overexpression promoted PCa cell proliferation and migration. Moreover, it was observed that NRP1 depletion induced G1 phase arrest in PCa cells. Mechanistically, HIF1α is bound to the specific promoter region of NRP1, thereby regulating its transcriptional activation. Subsequently, NRP1 interacted with EGFR, leading to EGFR phosphorylation. This study also provided evidence that the b1/b2 domain of NRP1 was responsible for the interaction with the extracellular domain of EGFR. Moreover, EGFR mediated NRP1-induced activation of the AKT signaling pathway, which promoted the malignant progression of PCa. In addition, the administration of NRP1 inhibitor EG01377 significantly inactivated the EGFR/AKT signaling axis, thereby suppressing PCa progression. In conclusion, the findings from this study highlighted the molecular mechanism underlying NRP1 expression in PCa and provide a potential predictor and therapeutic target for clinical prognosis and treatment of PCa.

Correlation between hypoxia and HGF/c-MET expression in the management of pancreatic cancer

Pancreatic cancer (PC) is very deadly and difficult to treat. The presence of hypoxia has been shown to increase the probability of cancer developing and spreading. Pancreatic ductal adenocarcinoma (PDAC/PC) has traditionally viewed a highly lethal form of cancer due to its high occurrence of early metastases. Desmoplasia/stroma is often thick and collagenous, with pancreatic stellate cells as the primary source (PSCs). Cancer cells and other stromal cells interact with PSCs, promoting disease development. The hepatocyte growth factor (HGF)/c-MET pathway have been proposed as a growth factor mechanism mediating this interaction. Human growth factor (HGF) is secreted by pancreatic stellate cells (PSCs), and its receptor, c-MET, is generated by pancreatic cancer cells and endothelial cells. Hypoxia is frequent in malignant tumors, particularly pancreatic (PC). Hypoxia results from limitless tumor development and promotes survival, progression, and invasion. Hypoxic is becoming a critical driver and therapeutic target of pancreatic cancer as its hypoxia microenvironment is defined. Recent breakthroughs in cancer biology show that hypoxia promotes tumor proliferation, aggressiveness, and therapeutic resistance. Hypoxia-inducible factors (HIFs) stabilize hypoxia signaling. Hypoxia cMet is a key component of pancreatic tumor microenvironments, which also have a fibrotic response, that hypoxia, promotes and modulates. c-Met is a tyrosine-protein kinase. As describe it simply, the MET gene in humans' codes for a protein called hepatocyte growth factor receptor (HGFR). Most cancerous tumors and pancreatic cancer in particular, suffer from a lack of oxygen (PC). Due to unrestrained tumor development, hypoxia develops, actively contributing to tumor survival, progression, and invasion. As the processes by which hypoxia signaling promotes invasion and metastasis become clear, c-MET has emerged as an important determinant of pancreatic cancer malignancy and a potential pharmacological target. This manuscript provides the most current findings on the role of hypoxia and HGF/c-MET expression in the treatment of pancreatic cancer.

Development of highly potent and specific AKR1C3 inhibitors to restore the chemosensitivity of drug-resistant breast cancer

Aldo-keto reductase 1C3 (AKR1C3) is overexpressed in multiple hormone related cancers, such as breast and prostate cancer, and is correlated with tumor development and aggressiveness. As a phase I biotransformation enzyme, AKR1C3 catalyzes the metabolic processes that lead to resistance to anthracyclines, the "gold standard" for breast cancer treatment. Novel approaches to restore the chemotherapy sensitivity of breast cancer are urgently required. Herein, we developed a new class of AKR1C3 inhibitors that demonstrated potent inhibitory activity and exquisite selectivity for closely related isoforms. The best derivative 27 (S19-1035) exhibits an IC₅₀ value of 3.04 nM for AKR1C3 and >3289-fold selectivity over other isoforms. We determined the co-crystal structures of AKR1C3 with three of the inhibitors, providing a solid foundation for further structure-based drug optimization. Co-administration of these AKR1C3 inhibitors significantly reversed the doxorubicin (DOX) resistance in a resistant breast cancer cell line. Therefore, the novel AKR1C3 specific inhibitors developed in this work may serve as effective adjuvants to overcome DOX resistance in breast cancer treatment.

Protein degradation: expanding the toolbox to restrain cancer drug resistance

Despite significant progress in clinical management, drug resistance remains a major obstacle. Recent research based on protein degradation to restrain drug resistance has attracted wide attention, and several therapeutic strategies such as inhibition of proteasome with bortezomib and proteolysis-targeting chimeric have been developed. Compared with intervention at the transcriptional level, targeting the degradation process seems to be a more rapid and direct strategy. Proteasomal proteolysis and lysosomal proteolysis are the most critical quality control systems responsible for the degradation of proteins or organelles. Although proteasomal and lysosomal inhibitors (e.g., bortezomib and chloroquine) have achieved certain improvements in some clinical application scenarios, their routine application in practice is still a long way off, which is due to the lack of precise targeting capabilities and inevitable side effects. In-depth studies on the regulatory mechanism of critical protein degradation regulators, including E3 ubiquitin ligases, deubiquitylating enzymes (DUBs), and chaperones, are expected to provide precise clues for developing targeting strategies and reducing side effects. Here, we discuss the underlying mechanisms of protein degradation in regulating drug efflux, drug metabolism, DNA repair, drug target alteration, downstream bypass signaling, sustaining of stemness, and tumor microenvironment remodeling to delineate the functional roles of protein degradation in drug resistance. We also highlight specific E3 ligases, DUBs, and chaperones, discussing possible strategies modulating protein degradation to target cancer drug resistance. A systematic summary of the molecular basis by which protein degradation regulates tumor drug resistance will help facilitate the development of appropriate clinical strategies.

α‑hederin overcomes hypoxia‑mediated drug resistance in colorectal cancer by inhibiting the AKT/Bcl2 pathway

Currently, chemoresistance is a major challenge that directly affects the prognosis of patients with colorectal cancer (CRC). In addition, hypoxia is associated with poor prognosis and therapeutic resistance in patients with cancer. Accumulating evidence has shown that α‑hederin has significant antitumour effects and that α‑hederin can inhibit hypoxia‑mediated drug resistance in CRC; however, the underlying mechanism remains unclear. In the present study, viability and proliferation assays were used to evaluate the effect of α‑hederin on the drug resistance of CRC cells under hypoxia. Sequencing analysis and apoptosis assays were used to determine the effect of α‑hederin on apoptosis under hypoxia. Western blot analysis and reverse transcription‑quantitative PCR were used to measure apoptosis‑related protein and mRNA expression levels. Furthermore, different mouse models were established to study the effect of α‑hederin on hypoxia‑mediated CRC drug resistance in vivo. In the present study, the high expression of Bcl2 in hypoxic CRC cells was revealed to be a key factor in their drug resistance, whereas α‑hederin inhibited the expression of Bcl2 by reducing AKT phosphorylation in vitro and in vivo, and promoted the apoptosis of CRC cells under hypoxia. By contrast, overexpression of AKT reversed the effect of α‑hederin on CRC cell apoptosis under hypoxia. Taken together, these results suggested that α‑hederin may overcome hypoxia‑mediated drug resistance in CRC by inhibiting the AKT/Bcl2 pathway. In the future, α‑hederin may be used as a novel adjuvant for reversing drug resistance in CRC.

Hypoxia-ameliorated photothermal manganese dioxide nanoplatform for reversing doxorubicin resistance

Drug resistance is a huge hurdle in tumor therapy. Tumor hypoxia contributes to chemotherapy resistance by inducing the hypoxia-inducible factor-1α (HIF-1α) pathway. To reduce tumor hypoxia, novel approaches have been devised, providing significant importance to reverse therapeutic resistance and improve the effectiveness of antitumor therapies. Herein, the nanosystem of bovine serum albumin (BSA)-templated manganese dioxide (MnO₂) nanoparticles (BSA/MnO₂ NPs) loaded with doxorubicin (DOX) (DOX-BSA/MnO₂ NPs) developed in our previous report was further explored for their physicochemical properties and capacity to reverse DOX resistance because of their excellent photothermal and tumor microenvironment (TME) response effects. The DOX-BSA/MnO₂ NPs showed good biocompatibility and hemocompatibility. Meanwhile, DOX-BSA/MnO₂ NPs could greatly affect DOX pharmacokinetic properties, with prolonged circulation time and reduced cardiotoxicity, besides enhancing accumulation at tumor sites. DOX-BSA/MnO₂ NPs can interact with H₂O₂ and H⁺ in TME to form oxygen and exhibit excellent photothermal effect to further alleviate hypoxia due to MnO₂, reversing DOX resistance by down-regulating HIF-1α expression and significantly improving the antitumor efficiency in DOX-resistant human breast carcinoma cell line (MCF-7/ADR) tumor model. The hypoxia-ameliorated photothermal MnO₂ platform is a promising strategy for revering DOX resistance.

The complex nature of heterogeneity and its roles in breast cancer biology and therapeutic responsiveness

Heterogeneity is a complex feature of cells and tissues with many interacting components. Depending on the nature of the research context, interacting features of cellular, drug response, genetic, molecular, spatial, temporal, and vascular heterogeneity may be present. We describe the various forms of heterogeneity with examples of their interactions and how they play a role in affecting cellular phenotype and drug responses in breast cancer. While cellular heterogeneity may be the most widely described and invoked, many forms of heterogeneity are evident within the tumor microenvironment and affect responses to the endocrine and cytotoxic drugs widely used in standard clinical care. Drug response heterogeneity is a critical determinant of clinical response and curative potential and also is multifaceted when encountered. The interactive nature of some forms of heterogeneity is readily apparent. For example, the process of metastasis has the properties of both temporal and spatial heterogeneity within the host, whereas each individual metastatic deposit may exhibit cellular, genetic, molecular, and vascular heterogeneity. This review describes the many forms of heterogeneity, their integrated activities, and offers some insights into how heterogeneity may be understood and studied in the future.

Biomedical engineered nanomaterials to alleviate tumor hypoxia for enhanced photodynamic therapy

Photodynamic therapy (PDT), as a highly selective, widely applicable, and non-invasive therapeutic modality that is an alternative to radiotherapy and chemotherapy, is extensively applied to cancer therapy. Practically, the efficiency of PDT is severely hindered by the existence of hypoxia in tumor tissue. Hypoxia is a typical hallmark of malignant solid tumors, which remains an essential impediment to many current treatments, thereby leading to poor clinical prognosis after therapy. To address this issue, studies have been focused on modulating tumor hypoxia to augment the therapeutic efficacy. Although nanomaterials to relieve tumor hypoxia for enhanced PDT have been demonstrated in many research articles, a systematical summary of the role of nanomaterials in alleviating tumor hypoxia is scarce. In this review, we introduced the mechanism of PDT, and the involved therapeutic modality of PDT for ablation of tumor cells was specifically summarized. Moreover, current advances in nanomaterials-mediated tumor oxygenation via oxygen-carrying or oxygen-generation tactics to alleviate tumor hypoxia are emphasized. Based on these considerable summaries and analyses, we proposed some feasible perspectives on nanoparticle-based tumor oxygenation to ameliorate the therapeutic outcomes, which may provide some detailed information in designing new oxygenation nanomaterials in this burgeneous field.

Hypoxia activated HGF expression in pancreatic stellate cells confers resistance of pancreatic cancer cells to EGFR inhibition

BACKGROUND

Epidermal growth factor receptor (EGFR) is an essential target for cancer treatment. However, EGFR inhibitor erlotinib showed limited clinical benefit in pancreatic cancer therapy. Here, we showed the underlying mechanism of tumor microenvironment suppressing the sensitivity of EGFR inhibitor through the pancreatic stellate cell (PSC).

METHODS

The expression of alpha-smooth muscle actin (α-SMA) and hypoxia marker in human pancreatic cancer tissues were detected by immunohistochemistry, and their correlation with overall survival was evaluated. Human immortalized PSC was constructed and used to investigate the potential effect on pancreatic cancer cell lines in hypoxia and normoxia. Luciferase reporter assay and Chromatin immunoprecipitation were performed to explore the potential mechanisms in vitro. The combined inhibition of EGFR and Met was evaluated in an orthotopic xenograft mouse model of pancreatic cancer.

FINDINGS

We found that high expression levels of α-SMA and hypoxia markers are associated with poor prognosis of pancreatic cancer patients. Mechanistically, we demonstrated that hypoxia induced the expression and secretion of HGF in PSC via transcription factor HIF-1α. PSC-derived HGF activates Met, the HGF receptor, suppressing the sensitivity of pancreatic cancer cells to EGFR inhibitor in a KRAS-independent manner by activating the PI3K-AKT pathway. Furthermore, we found that the combination of EGFR inhibitor and Met inhibitor significantly suppressed tumor growth in an orthotopic xenograft mouse model.

INTERPRETATION

Our study revealed a previously uncharacterized HIF1α-HGF-Met-PI3K-AKT signaling axis between PSC and cancer cells and indicated that EGFR inhibition plus Met inhibition might be a promising strategy for pancreatic cancer treatment.

FUNDING

This study was supported by The National Natural Science Foundation of China.

Small Extracellular Vesicles from Hypoxic Triple-Negative Breast Cancer Cells Induce Oxygen-Dependent Cell Invasion

Hypoxia, a condition of low oxygenation frequently found in triple-negative breast tumors (TNBC), promotes extracellular vesicle (EV) secretion and favors cell invasion, a complex process in which cell morphology is altered, dynamic focal adhesion spots are created, and ECM is remodeled. Here, we investigated the invasive properties triggered by TNBC-derived hypoxic small EV (SEVh) in vitro in cells cultured under hypoxic (1% O₂) and normoxic (20% O₂) conditions, using phenotypical and proteomic approaches. SEVh characterization demonstrated increased protein abundance and diversity over normoxic SEV (SEVn), with enrichment in pro-invasive pathways. In normoxic cells, SEVh promotes invasive behavior through pro-migratory morphology, invadopodia development, ECM degradation, and matrix metalloprotease (MMP) secretion. The proteome profiling of 20% O₂-cultured cells exposed to SEVh determined enrichment in metabolic processes and cell cycles, modulating cell health to escape apoptotic pathways. In hypoxia, SEVh was responsible for proteolytic and catabolic pathway inducement, interfering with integrin availability and gelatinase expression. Overall, our results demonstrate the importance of hypoxic signaling via SEV in tumors for the early establishment of metastasis.

Conducive target range of breast cancer: Hypoxic tumor microenvironment

Breast cancer is a kind of malignant tumor disease that poses a serious threat to human health. Its biological characteristics of rapid proliferation and delayed angiogenesis, lead to intratumoral hypoxia as a common finding in breast cancer. HIF as a transcription factor, mediate a series of reactions in the hypoxic microenvironment, including metabolic reprogramming, tumor angiogenesis, tumor cell proliferation and metastasis and other important physiological and pathological processes, as well as gene instability under hypoxia. In addition, in the immune microenvironment of hypoxia, both innate and acquired immunity of tumor cells undergo subtle changes to support tumor and inhibit immune activity. Thus, the elucidation of tumor microenvironment hypoxia provides a promising target for the resistance and limited efficacy of current breast cancer therapies. We also summarize the hypoxic mechanisms of breast cancer treatment related drug resistance, as well as the current status and prospects of latest related drugs targeted HIF inhibitors.

Crosstalk between Hypoxia and Extracellular Matrix in the Tumor Microenvironment in Breast Cancer

Even though breast cancer is the most diagnosed cancer among women, treatments are not always successful in preventing its progression. Recent studies suggest that hypoxia and the extracellular matrix (ECM) are important in altering cell metabolism and tumor metastasis. Therefore, the aim of this review is to study the crosstalk between hypoxia and the ECM and to assess their impact on breast cancer progression. The findings indicate that hypoxic signaling engages multiple mechanisms that directly contribute to ECM remodeling, ultimately increasing breast cancer aggressiveness. Second, hypoxia and the ECM cooperate to alter different aspects of cell metabolism. They mutually enhance aerobic glycolysis through upregulation of glucose transport, glycolytic enzymes, and by regulating intracellular pH. Both alter lipid and amino acid metabolism by stimulating lipid and amino acid uptake and synthesis, thereby providing the tumor with additional energy for growth and metastasis. Third, YAP/TAZ signaling is not merely regulated by the tumor microenvironment and cell metabolism, but it also regulates it primarily through its target c-Myc. Taken together, this review provides a better understanding of the crosstalk between hypoxia and the ECM in breast cancer. Additionally, it points to a role for the YAP/TAZ mechanotransduction pathway as an important link between hypoxia and the ECM in the tumor microenvironment, driving breast cancer progression.

An order-to-disorder structural switch regulates HIF-1 transcription through S247 phosphorylation in the HIF1α PAS-B domain

Hypoxia-inducible factor 1 (HIF-1), a transcriptional activator that mediates cellular responses to hypoxic stress, is essential for tumor progression. It is a heterodimer comprising HIF1α and HIF1β, with multiple interfaces among their PAS-A, PAS-B, and bHLH domains. HIF1β is also known as aryl hydrocarbon receptor nuclear translocator (ARNT). Casein kinase 1δ-dependent phosphorylation of the solvent-front residue S247 on the HIF1α PAS-B domain interrupts HIF1α-ARNT complex formation and reduces HIF-1 transcription activity. However, S247 is involved in neither HIF1α-ARNT complex formation nor stabilization of the relative orientation between the HIF1α PAS-A and PAS-B domains. To uncover the underlying allosteric mechanism, we conducted Gaussian accelerated molecular dynamics simulations and identified two distinct conformations of the pS247-carrying HIF1α PAS-B domain: H291-in and H291-out. The H291-in structure can associate with the HIF1α PAS-A domain and form a V-shaped pouch to accommodate the ARNT PAS-A domain, but it cannot associate with the ARNT PAS-B domain. By contrast, the H291-out structure can bind to the ARNT PAS-B domain, but its association with the HIF1α PAS-A domain leads to an unsuitable relative orientation to accommodate the ARNT PAS-A domain. Both conformations were also collected in parallel simulations of the unphosphorylated PAS-B domain. Both structures manage to associate with the ARNT PAS-B and HIF1α PAS-A domains; thus, they are adequate for HIF1α-ARNT complex formation. The domain-domain contact pattern in a phosphorylated variant is shuffled by an order-to-disorder structural switch, triggered by the newly formed K251-pS247 interaction.

The role of hypoxia-inducible factor-1 alpha in multidrug-resistant breast cancer

Breast cancer is the most common cancer in women worldwide with increasing incidence. Significant therapeutics advances in the field of breast cancer have resulted in a growing number of treatment options, whereas de novo or acquired resistance is still a persistent clinical challenge. Drug resistance involves a variety of mechanisms, and hypoxia is one of the many causes. Hypoxia-inducible Factor-1 Alpha (HIF-1α) is a key transcription factor which can regulate the response of cells to hypoxia. HIF-1α can trigger anaerobic glycolysis of tumor cells, induce angiogenesis, promote the proliferation, invasion, and migration of tumor cells, and lead to multidrug resistance. This review mainly discusses the role of HIF-1α in the drug-resistant breast cancer and highlighted the potential of HIF-1α -targeted therapy.

Breast Cancer Subtypes Based on Hypoxia-Related Gene Sets Identify Potential Therapeutic Agents

Purpose: The hypoxic tumor microenvironment was reported to be involved in different tumorigenesis mechanisms of breast cancer (BC). We aimed to establish a hypoxia-related gene signature to identify a new BC subtype through the clustering analysis and explore potential compounds targeting the BC subtypes.

Methods: Gene expression data and clinical features of BC and adjacent non-tumor tissues were downloaded from the Cancer Genome Atlas-Breast cancer (TCGA-BRCA) database. We comprehensively revealed the activity changes of Gene Ontology (GO) biological processes (BP) gene sets in BC by gene set variation analysis (GSVA) and identified three hypoxia-related BC subtypes. We then matched the differentially expressed gene profile of each subtype with the gene profile in CMap database to identify the potential agents targeting the BC subtypes.

Results: 562 of Gene Ontology biological processes gene sets significantly correlated with hypoxia score in breast cancer. 969 BC patients were clustered into three subtypes based on the enrichment score of hypoxia-associated gene sets. Subtype 1 patients displayed better survival than subtype 2 and 3. KEGG pathway enrichment analysis of each subtype was performed based on the unique differential expression genes profile. In subtype 1, the upregulated genes were associated with lipid and amino acid metabolism regulation; in subtype 2, the upregulated genes were associated with metabolic energy regulation, while in subtype 3, the upregulated genes were associated with apoptosis and protein process. Using the CMap database, 55, 111 and 63 compounds were identified, targeting subtype 1, 2, and 3, respectively.

Conclusion: In this study, novel hypoxia-related subtypes were developed for patients with BC. In addition, biological processes associated with differential expression genes profile and potential therapeutic target compounds were identified in each subtype. The new classification might provide a better understanding of the role of hypoxia in breast cancer and more individualized treatment for patients.

The Promise of Targeting Hypoxia to Improve Cancer Immunotherapy: Mirage or Reality?

Almost all solid tumors display hypoxic areas in the tumor microenvironment associated with therapeutic failure. It is now well established that the abnormal growth of malignant solid tumors exacerbates their susceptibility to hypoxia. Therefore, targeting hypoxia remains an attractive strategy to sensitize tumors to various therapies. Tumor cell adaptions to hypoxia are primarily mediated by hypoxia-inducible factor-1 alpha (HIF-1α). Sensing hypoxia by HIF-1α impairs the apoptotic potential of tumor cells, thus increasing their proliferative capacity and contributing to the development of a chaotic vasculature in the tumor microenvironment. Therefore, in addition to the negative impact of hypoxia on tumor response to chemo- and radio-therapies, hypoxia has also been described as a major hijacker of the tumor response by impairing the tumor cell susceptibility to immune cell killing. This review is not intended to provide a comprehensive overview of the work published by several groups on the multiple mechanisms by which hypoxia impairs the anti-tumor immunity and establishes the immunosuppressive tumor microenvironment. There are several excellent reviews highlighting the value of targeting hypoxia to improve the benefit of immunotherapy. Here, we first provide a brief overview of the mechanisms involved in the establishment of hypoxic stress in the tumor microenvironment. We then discuss our recently published data on how targeting hypoxia, by deleting a critical domain in HIF-1α, contributes to the improvement of the anti-tumor immune response. Our aim is to support the current dogma about the relevance of targeting hypoxia in cancer immunotherapy.

Ferroptosis-Driven Nanotherapeutics to Reverse Drug Resistance in Tumor Microenvironment

Ferroptosis, characterized by iron-dependent lipid reactive oxygen species (ROS) accumulation, is non-apoptotic programmed cell death highly relevant to tumor development. It was found to manipulate oncogenes and resistant mutations of cancer cells via lipid metabolism pathways converging on phospholipid glutathione peroxidase (GPX4) that squanders lipid peroxides (L-OOH) to block the iron-mediated reactions of peroxides, thus rendering resistant cancer cells vulnerable to ferroptotic cell death. By accumulating ROS and lipid peroxidation (LPO) products to lethal levels in tumor microenvironment (TME), ferroptosis-driven nanotherapeutics show a superior ability of eradicating aggressive malignancies than traditional therapeutic modalities, especially for the drug-resistant tumors with high metastasis tendency. Moreover, Fenton reaction, inhibition of GPX-4, and exogenous regulation of LPO are three major therapeutic strategies to induce ferroptosis in cancer cells, which were generally applied in ferroptosis-driven nanotherapeutics. In this review, we elaborate current trends of ferroptosis-driven nanotherapeutics to reverse drug resistance of tumors in anticancer fields at the intersection of cancer biology, materials science, and chemistry. Finally, their challenges and perspectives toward feasible translational studies are spotlighted, which would ignite the hope of anti-resistant cancer treatment.

Phthalimide Analogs Enhance Genotoxicity of Cyclophosphamide and Inhibit Its Associated Hypoxia

Cyclophosphamide (CP) is a mutagen that is used in cancer chemotherapy, due to its genotoxicity and as an immunosuppressive agent. Thalidomide (TH) is another cancer chemotherapeutic drug. In this study, the cytogenotoxicity and hypoxia modulatory activities of two phthalimide analogs of TH have been evaluated with/without CP. Both analogs have increased CP-stimulated chromosomal aberrations than those induced by TH, including gaps, breaks/fragments, deletions, multiple aberrations, and tetraploidy. The analogs have elevated the cytotoxic effect of CP by inhibiting the mitotic activity, in which analog 2 showed higher mitosis inhibition. CP has induced binucleated and polynucleated bone marrow cells (BMCs), while micronuclei (MN) are absent. TH and analogs have elevated the CP-stimulated binucleated BMCs, while only analogs have increased the CP-induced polynucleated BMCs and inhibited the mononucleated BMCs. MN-BMCs were shown together with mononucleated, binucleated, and polynucleated cells in the CP group. Both analogs have elevated mononucleated and polynucleated MN-BMCs, whereas in presence of CP, TH and analogs have enhanced mononucleated and binucleated MN-BMCs. The analogs significantly induce DNA fragmentation in a comet assay, where analog 1 is the strongest inducer. The treatment of mice with CP has resulted in a high hypoxia status as indicated by high pimonidazole adducts and high HIF-1α and HIF-2α concentrations in lymphocytes. Analogs/CP-treated mice showed low pimonidazole adducts. Both analogs have inhibited HIF-1α concentration but not HIF-2α. Taken together, the study findings suggest that both analogs have a higher potential to induce CP-genotoxicity than TH and that both analogs inhibit CP-hypoxia via the HIF-1α-dependent mechanism, in which analog 1 is a more potent anti-hypoxic agent than analog 2. Analog 1 is suggested as an adjacent CP-complementary agent to induce CP-genotoxicity and to inhibit CP-associated hypoxia.

Therapeutic implication of carbon monoxide in drug resistant cancers

Drug resistance is the major obstacle that undermines effective cancer treatment. Recently, the application of gas signaling molecules, e.g., carbon monoxide (CO), in overcoming drug resistance has gained significant attention. Growing evidence showed that CO could inhibit mitochondria respiratory effect and glycolysis, two major ATP production pathways in cancer cells, and suppress angiogenesis and inhibit the activity of cystathionine β-synthase that is important in regulating cancer cells homeostasis, leading to synergistic effects when combined with cisplatin, doxorubicin, or phototherapy, etc. in certain resistant cancer cells. In the current review, we attempted to have a summary of these research conducted in the past decade using CO in treating drug resistant cancers, and have a detailed interpretation of the underlying mechanisms. The critical challenges will be discussed and potential solutions will also be provided. The information collected in this work will hopefully evoke more effects in using CO for the treatment of drug resistant cancers.

In vitrobreast cancer model with patient-specific morphological features for personalized medicine

In vitro cancer models that can simulate patient-specific drug responses for personalized medicine have attracted significant attention. However, the technologies used to produce such models can only recapitulate the morphological heterogeneity of human cancer tissue. Here, we developed a novel 3D technique to bioprint an in vitro breast cancer model with patient-specific morphological features. This model can precisely mimic the cellular microstructures of heterogeneous cancer tissues and produce drug responses similar to those of human cancers. We established a bioprinting process for generating cancer cell aggregates with ductal and solid tissue microstructures that reflected the morphology of breast cancer tissues, and applied it to develop breast cancer models. The genotypic and phenotypic characteristics of the ductal and solid cancer aggregates bioprinted with human breast cancer cells (MCF7, SKBR3, MDA-MB-231) were respectively similar to those of early and advanced cancers. The bioprinted solid cancer cell aggregates showed significantly higher hypoxia (>8 times) and mesenchymal (>2-4 times) marker expressions, invasion activity (>15 times), and drug resistance than the bioprinted ductal aggregates. Co-printing the ductal and solid aggregates produced heterogeneous breast cancer tissue models that recapitulated three different stages of breast cancer tissue morphology. The bioprinted cancer tissue models representing advanced cancer were more and less resistant, respectively, to the anthracycline antibiotic doxorubicin and the hypoxia-activated prodrug tirapazamine; these were analogous to the results in human cancer. The present findings showed that cancer cell aggregates can mimic the pathological micromorphology of human breast cancer tissue and they can be bioprinted to produce breast cancer tissue in vitro that can morphologically represent the clinical stage of cancer in individual patients.

New insights into the discovery of drugs for triple-negative breast cancer metastasis

INTRODUCTION

Triple-negative breast cancer (TNBC) is of great concern due to its aggressiveness and lack of targeted therapy. For these reasons, TNBC is one of the main causes of death in women, mainly due to metastases. Tumor dissemination has highlighted a set of possible targets, with extensive research into new single-target drugs, in addition to drug repurposing strategies, being undertaken to discover new classes of potential inhibitors of metastasis.

AREAS COVERED

The authors here describe the main proposed targets and the bases of their pharmacological inhibition with different chemical compounds. The authors also discuss the state-of-the-art from the latest clinical trials and highlight other potential targets for metastatic TNBC.

EXPERT OPINION

In the last decade, oncology research has changed its focus from primary tumors to moving tumor cells, their products, and to the secondary tumor and its surroundings, for the purpose of finding targets to treat metastasis. Consequently, our comprehension of the complexity of the metastatic process has increased drastically, with, furthermore, the discovery of new potential targets. Although promising, the wide range of strategies is still not effective to suppress TNBC metastasis in terms of increasing patient survival or decreasing the number of metastases. Treating or preventing metastasis continues to be a great challenge.

Hypoxia signaling pathway: A central mediator in endocrine tumors

Adequate oxygen levels are essential for the functioning and maintenance of biological processes in virtually every cell, albeit based on specific need. Thus, any change in oxygen pressure leads to modulated activation of the hypoxia pathway, which affects numerous physiological and pathological processes, including hematopoiesis, inflammation, and tumor development. The Hypoxia Inducible Factors (HIFs) are essential transcription factors and the driving force of the hypoxia pathway; whereas, their inhibitors, HIF prolyl hydroxylase domain (PHDs) proteins are the true oxygen sensors that critically regulate this response. Recently, we and others have described the central role of the PHD/HIF axis in various compartments of the adrenal gland and its potential influence in associated tumors, including pheochromocytomas and paragangliomas. Here, we provide an overview of the most recent findings on the hypoxia signaling pathway in vivo, including its role in the endocrine system, especially in adrenal tumors.

MiR-526b-3p Attenuates Breast Cancer Stem Cell Properties and Chemoresistance by Targeting HIF-2α/Notch Signaling

Chemoresistance is a severe clinical challenge in breast cancer. Hypoxia and cancer stem cells (CSCs) contribute to the paclitaxel (PTX) resistance, but the molecular mechanisms are still elusive. MicorRNAs (miRNA) have been considered a promising therapeutic strategy in various cancers. Here, we identified the crucial function of miR-526b-3p in regulating PTX resistance and CSC properties. Our data demonstrated that miR-526b-3p mimic repressed the cell viability of breast cancer cells. The counts of Edu-positive cells were reduced by miR-526b-3p in breast cancer cells. Meanwhile, the apoptosis of breast cancer cells was induced by miR-526b-3p. Tumorigenicity analysis in the nude mice confirmed that miR-526b-3p attenuated the breast cancer cell growth in vivo. Significantly, hypoxia could enhance IC50 value of PTX in breast cancer cells. IC50 value of PTX was induced in breast cancer mammospheres. The hypoxia-inducible factor 2α (HIF-2α) expression was enhanced, but miR-526b-3p expression was repressed under hypoxia in breast cancer cells. Also, breast cancer mammospheres presented high HIF-2α expression and low miR-526b-3p expression. The inhibition of miR-526b-3p enhanced the IC50 value of PTX in breast cancer cells. MiR-526b-3p inhibitor enhanced the colony formation counts of PTX-treated breast cancer cells. The treatment of miR-526b-3p mimic suppressed the sphere formation counts of breast cancer cells and inhibited ALDH1 and Nanog expression. MiR-526b-3p was able to target HIF-2α in the cells. The overexpression enhanced but miR-526b-3p reduced the IC50 value of PTX in breast cancer cells, in which the overexpression of HIF-2α could rescue the miR-526b-3p-inhibited IC50 value of PTX. Overexpression of HIF-2α reversed miR-526b-3p-regulated apoptosis, colony formation ability, and ALDH1 and Nanog expression in the cells. Interestingly, the overexpression of HIF-2α induced but miR-526b-3p repressed the expression of HIF-2α, Hey2, and Notch in PTX-treated breast cancer cells, while HIF-2α could reverse the effect of miR-526b-3p. In conclusion, miR-526b-3p attenuated breast cancer stem cell properties and chemoresistance by targeting HIF-2α/Notch signaling. MiR-526b-3p may be utilized in the relieving chemoresistance in breast cancer.

Baicalein resensitizes tamoxifen-resistant breast cancer cells by reducing aerobic glycolysis and reversing mitochondrial dysfunction via inhibition of hypoxia-inducible factor-1α

Drug resistance is a major hurdle for the effectiveness of tamoxifen (TAM) to provide clinical benefit. Therefore, it is essential to identify a sensitizer that could be used to improve TAM efficacy in treating TAM-resistant breast cancer. Here, we investigated the ability of baicalein to reverse TAM resistance. We found that baicalein increased the efficacy of TAM in inhibiting proliferation and inducing apoptosis of TAM-resistant cells. It also enhanced the TAM-induced growth reduction of resistant cells from NOD/SCID mouse mammary fat pads, without causing obvious systemic toxicity. Analyses using the CellMiner tool and the Kaplan-Meier plotter database showed that HIF-1α expression was inversely correlated with TAM therapeutic response in NCI-60 cancer cells and breast cancer patients. HIF-1α expression was increased in TAM-resistant cells due to an increase in mRNA levels and reduced ubiquitin-mediated degradation. Baicalein reduced HIF-1α expression by promoting its interaction with PHD2 and pVHL, thus facilitating ubiquitin ligase-mediated proteasomal degradation and thereby suppressing the nuclear translocation, binding to the hypoxia-response element, and transcriptional activity of HIF-1α. As a result, baicalein downregulated aerobic glycolysis by restricting glucose uptake, lactate production, ATP generation, lactate/pyruvate ratio and expression of HIF-1α-targeted glycolytic genes, thereby enhancing the antiproliferative efficacy of TAM. Furthermore, baicalein interfered with HIF-1α inhibition of mitochondrial biosynthesis, which increased mitochondrial DNA content and mitochondrial numbers, restored the generation of reactive oxygen species in mitochondria, and thus enhanced the TAM-induced mitochondrial apoptotic pathway. The HIF-1α stabilizer dimethyloxallyl glycine prevented the baicalein-induced downregulation of glycolysis and mitochondrial biosynthesis and reduced the effects of baicalein on reversing TAM resistance. Our results indicate that baicalein is a promising candidate to help overcome TAM resistance by sensitizing resistant cells to TAM-induced growth inhibition and apoptosis. The mechanism underlying the effects of baicalein consists of inhibition of HIF-1α-mediated aerobic glycolysis and mitochondrial dysfunction.

Structural Insights into the Interactions of Digoxin and Na+/K+-ATPase and Other Targets for the Inhibition of Cancer Cell Proliferation

Digoxin is a cardiac glycoside long used to treat congestive heart failure and found recently to show antitumor potential. The hydroxy groups connected at the C-12, C-14, and C-3′a positions; the C-17 unsaturated lactone unit; the conformation of the steroid core; and the C-3 saccharide moiety have been demonstrated as being important for digoxin’s cytotoxicity and interactions with Na⁺/K⁺-ATPase. The docking profiles for digoxin and several derivatives and Na⁺/K⁺-ATPase were investigated; an additional small Asn130 side pocket was revealed, which could be useful in the design of novel digoxin-like antitumor agents. In addition, the docking scores for digoxin and its derivatives were found to correlate with their cytotoxicity, indicating a potential use of these values in the prediction of the cancer cell cytotoxicity of other cardiac glycosides. Moreover, in these docking studies, digoxin was found to bind to FIH-1 and NF-κB but not HDAC, IAP, and PI3K, suggesting that this cardiac glycoside directly targets FIH-1, Na⁺/K⁺-ATPase, and NF-κB to mediate its antitumor potential. Differentially, digoxigenin, the aglycon of digoxin, binds to HDAC and PI3K, but not FIH-1, IAP, Na⁺/K⁺-ATPase, and NF-κB, indicating that this compound may target tumor autophagy and metabolism to mediate its antitumor propensity.

Small-molecule probes for fluorescent detection of cellular hypoxia-related nitroreductase

Nitroreductase is a reductase that catalyzes nitro aromatic compounds to aromatic amines. It effectively reduces nitro to hydroxylamine or amino when in the presence of nicotinamide adenine dinucleotide or nicotinamide adenine dinucleotide phosphate. In terms of tumor, nitroreductase is upregulated in hypoxic tumor cells, and its content is directly related to the degree of hypoxia. Therefore, effective detection of nitroreductase is important not only for the study of cellular hypoxia, but also for the diagnosis and treatment of tumors and related diseases. In this review, we summarized the latest advances in small-molecule fluorescent probes for nitroreductase detection based on different fluorescence mechanisms, with a focus on research conducted between May 2018 and December 2020. The development trends and application prospect in this rapidly developing field were also highlighted.