Tumor hypoxia: definitions and current clinical, biologic, and molecular aspects

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

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

A light-activatable theranostic combination for ratiometric hypoxia imaging and oxygen-deprived drug activity enhancement

While performing oxygen-related tumour treatments such as chemotherapy and photodynamic therapy, real-time monitoring hypoxia of tumour is of great value and significance. Here, we design a theranostic combination for light-activated ratiometric hypoxia imaging, hypoxia modulating and prodrug activation. This combination consisted of an oxygen-sensitive near-infrared-emitting ratiometric phosphorescence probe and a hypoxia-activated prodrug-loaded covalent organic framework. In this combination, the probe plays two roles, including quantitative monitoring of oxygen concentration by ratiometric imaging and consuming the oxygen of tumour under light excitation by photodynamic therapy. Meanwhile, the enhanced hypoxia microenvironment of tumour can raise the cytotoxicity of prodrug loaded in covalent organic framework, resulting in boosting antitumour therapeutic effects in vivo. This theranostic combination can precisely provide therapeutic regime and screen hypoxia-activated prodrugs based on real-time tumour hypoxia level, offering a strategy to develop hypoxia mediated tumour theranostics with hypoxia targeted prodrugs.

Oxyhaemoglobin saturation NIR-IIb imaging for assessing cancer metabolism and predicting the response to immunotherapy

In vivo quantitative assessment of oxyhaemoglobin saturation (sO2) status in tumour-associated vessels could provide insights into cancer metabolism and behaviour. Here we develop a non-invasive in vivo sO2 imaging technique to visualize the sO2 levels of healthy and tumour tissue based on photoluminescence bioimaging in the near-infrared IIb (NIR-IIb; 1,500-1,700 nm) window. Real-time dynamic sO2 imaging with a high frame rate (33 Hz) reveals the cerebral arteries and veins through intact mouse scalp/skull, and this imaging is consistent with the haemodynamic analysis results. Utilizing our non-invasive sO2 imaging, the tumour-associated-vessel sO2 levels of various cancer models are evaluated. A positive correlation between the tumour-associated-vessel sO2 levels and the basal oxygen consumption rate of corresponding cancer cells at the early stages of tumorigenesis suggests that cancer cells modulate the tumour metabolic microenvironment. We also find that a positive therapeutic response to the checkpoint blockade cancer immunotherapy could lead to a dramatic decrease of the tumour-associated-vessel sO2 levels. Two-plex dynamic NIR-IIb imaging can be used to simultaneously observe tumour-vessel sO2 and PD-L1, allowing a more accurate prediction of immunotherapy response.

A novel lactate dehydrogenase-based risk score model to predict the prognosis of primary central nervous system germ cell tumor treated with chemoradiotherapy

BACKGROUND

The prognostic role of lactate dehydrogenase (LDH) has been confirmed in many malignant tumors, but the role of serum LDH in primary central nervous system germ cell tumor (GCT) remains unknown. This study aimed to assess the prognostic value of LDH in GCT patients and develop a nomogram to predict prognosis in patients undergoing chemoradiotherapy.

METHODS

A total of 161 patients with GCT were included in this study. Using a restricted cubic spline (RCS) model, the optimal cutoff point for LDH was determined to be 217 U/L. The survival of GCT patients was evaluated using the Kaplan-Meier method and log-rank test to analyze the effects of LDH levels. Univariate Cox regression, multivariate Cox regression, and LASSO Cox regression were conducted to identify prognostic factors, which were incorporated into a nomogram for predicting overall survival (OS). The predictive accuracy of the nomogram was assessed using the C-index, calibration curve, area under the time-dependent receiver operating characteristic curve (time-dependent AUC), and risk group stratification. The net benefits of the nomogram at different threshold probabilities were quantified using decision curve analysis (DCA).

RESULTS

The high-LDH group had significantly shorter OS compared to the low-LDH group (P = 0.016). Based on the SYSUCC cohort, three variables were shown to be significant factors for OS and were incorporated in the nomogram: LDH, histopathology, and dissemination. It showed good discrimination ability, with C-index of 0.789 (95% CI, 0.671-0.907). Additionally, the clinical usefulness of the nomogram was confirmed by calibration curves and time-dependent AUC. DCA further highlighted the potential of the nomogram to guide clinical treatment strategies for patients. Moreover, there was a significant difference in OS among patients categorized into different risk groups (P < 0.001).

CONCLUSION

LDH levels may serve as a reliable predictor for assessing the therapeutic effect of chemoradiotherapy in GCT. The developed nomogram exhibits high accuracy in predicting survival outcomes, aiding in the classification of prognostic groups, and supporting informed clinical decision-making.

Hypoxia A Typical Target in Human Lung Cancer Therapy

Lung cancer (LC) is the leading cause of cancer-related death globally. Comprehensive knowledge of the cellular and molecular etiology of LC is perilous for the development of active treatment approaches. Hypoxia in cancer is linked with malignancy, and its phenotype is implicated in the hypoxic reaction, which is being studied as a prospective cancer treatment target. The hypervascularization of the tumor is the main feature of human LC, and hypoxia is a major stimulator of neo-angiogenesis. It was seen that low oxygen levels in human LC are a critical aspect of this lethal illness. However, as there is a considerable body of literature espousing the presumed functional relevance of hypoxia in LC, the direct measurement of oxygen concentration in Human LC is yet to be determined. This narrative review aims to show the importance and as a future target for novel research studies that can lead to the perception of LC therapy in hypoxic malignancies.

Study of expression of GLUT-1 in oral potentially malignant disorders and oral squamous cell carcinoma: An immuno-histochemical analysis

Background

Glucose is the chief source of energy for cells, and glucose transporter 1 (GLUT-1) is one of the most common glucose transporters in humans. Tumour cells are known to express hypoxia-related protein, and these may allow tumour cells to survive under a sustained hypoxic environment. Surviving cells develop a more aggressive phenotype, which results in poor prognosis.

Aims and Objectives

Expression and comparison of GLUT-1 in normal tissues, potentially malignant disorders (PMDs), and oral squamous cell carcinoma (OSCC) and comparison of expression in different grades of OSCC.

Material and Methods

A total of 57 cases (10 normal, 17 PMD, and 30 cases of OSCC) were stained immuno-histochemically with GLUT-1. The expression was scored as 0, 1, 2, 3, and 4 for negative, mild, moderate, severe, and intense staining, respectively.

Results

GLUT-1 expression was detected in all grades of OSCC. A significant correlation was found on comparing normal and OSCC, normal and PMDs, and PMD and OSCC. The expression of GLUT-1 was significant when compared with different histopathological grades of OSCC.

Conclusions

Expression of GLUT-1 increased from normal to PMDs to increasing grades of OSCC and hence can be used as a prognostic predictive marker for OSCC.

Tumor-derived lactate promotes resistance to bevacizumab treatment by facilitating autophagy enhancer protein RUBCNL expression through histone H3 lysine 18 lactylation (H3K18la) in colorectal cancer

Bevacizumab plays an important role in the first and second line treatment for metastatic colorectal cancer (CRC). And induction of hypoxia and the tumors response to it plays an important role in determining the efficacy of antiangiogenic therapy while the connection between them remains unclear. Here, we found that lactate accumulated in the tumor environment of CRC and acted as substrates for histone lactylation, and this process was further induced by cellular enhanced glycolysis in hypoxia. We determined that CRC patients resistant to bevacizumab treatment presented with elevated levels of histone lactylation and inhibition of histone lactylation efficiently suppressed CRC tumorigenesis, progression and survival in hypoxia. Histone lactylation promoted the transcription of RUBCNL/Pacer, facilitating autophagosome maturation through interacting with BECN1 (beclin 1) and mediating the recruitment and function of the class III phosphatidylinositol 3-kinase complex, which had a crucial role in hypoxic cancer cells proliferation and survival. Moreover, combining inhibition of histone lactylation and macroautophagy/autophagy with bevacizumab treatment demonstrated remarkable treatment efficacy in bevacizumab-resistance patients-derived pre-clinical models. These findings delivered a new exploration and important supplement of metabolic reprogramming-epigenetic regulation, and provided a new strategy for improving clinical efficacy of bevacizumab in CRC by inhibition of histone lactylation.Abbreviations: 2-DG: 2-deoxy-D-glucose; BECN1: beclin 1; CQ: chloroquine; CRC: colorectal cancer; DMOG: dimethyloxalylglycine; H3K18la: histone H3 lysine 18 lactylation; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; Nala: sodium lactate; PDO: patient-derived orgnoid; PDX: patient-derived xenograft; RUBCNL/Pacer: rubicon like autophagy enhancer; SQSTM1/p62: sequestosome 1.

Local Microbubble Removal in Polydimethylsiloxane Microchannel by Balancing Negative and Atmospheric Pressures

Long-term experiments using organoids and tissues are crucial for drug development. Microfluidic devices have been regularly used in long-term experiments. However, microbubbles often form in these devices, and they may damage and starve cells. A method involving the application of negative pressure has been reported to remove microbubbles from microfluidic devices composed of polydimethylsiloxane; however, negative pressure affects the cells and tissues in microfluidic devices. In this study, a local microbubble removal method was developed using a microfluidic device with 0.5 mm thin polydimethylsiloxane sidewalls. The thin sidewalls counterbalanced the negative and atmospheric pressures, thereby localizing the negative pressure near the negatively pressurized chamber. Microbubbles were removed within 5 mm of the negatively pressurized chamber; however, those in an area 7 mm and more from the chamber were not removed. Using the local removal method, a long-term perfusion test was performed, and no contact was confirmed between the bubbles and the simulated tissue for 72 h.

Targeting the lactic acid metabolic pathway for antitumor therapy

Lactic acid is one of the most abundant products of cellular metabolism and has historically been considered a cell-damaging metabolic product. However, as research has deepened, the beneficial effects of lactic acid on tumor cells and the tumor microenvironment have received increasing attention from the oncology community. Lactic acid can not only provide tumor cells with energy but also act as a messenger molecule that promotes tumor growth and progression and protects tumor cells from immune cells and killing by radiation and chemotherapy. Thus, the inhibition of tumor cell lactic acid metabolism has emerged as a novel antitumor treatment strategy that can also effectively enhance the efficacy of conventional antitumor therapies. In this review, we classify the currently available therapies targeting lactic acid metabolism and examine their prospects for clinical application.

Alteration in the expression of the chemotherapy resistance‑related genes in response to chronic and acute hypoxia in pancreatic cancer

Pancreatic cancer is currently one of the least curable types of human cancer and remains a key health problem. One of the most important characteristics of pancreatic cancer is its ability to grow under hypoxic conditions. Hypoxia is associated with resistance of cancer cells to radiotherapy and chemotherapy. It is a major contributor to pancreatic cancer genetic instability, which local and systemic resistance that may result in poor clinical outcome. Accordingly, identifying gene expression changes in cancer resistance genes that occur under hypoxic conditions may identify a new therapeutic target. The aim of the present study was to explore the association between hypoxia and resistance to chemotherapy and determine the alteration in the expression of cancer resistance-related genes in the presence of hypoxia. Pancreatic cancer cells (PANC-1) were exposed to 8 h hypoxic episodes (<1% oxygen) three times/week for a total of 20 episodes (chronic hypoxia) or 72 h hypoxic episodes twice/week for a total of 10 episodes (acute hypoxia). The alterations in gene expression were examined using reverse transcription-quantitative PCR array compared with normoxic cells. Chemoresistance of hypoxic cells toward doxorubicin was assessed using MTT cell proliferation assay. Both chronic and acute hypoxia induced chemoresistance toward doxorubicin in PANC-1 pancreatic cancer cell line. The greatest changes occurred in estrogen Receptor Alpha Gene (ESR1) and ETS Like-1 protein (ELK1) pathways, in nucleic transcription factor Peroxisome proliferator-activated receptors (PPARs) and in a cell cycle inhibitor cyclin dependent kinase inhibitor 1A (CDKN1A). The present study demonstrated that exposing cells to prolonged hypoxia results in different gene expression changes involving pleotropic pathways that serve a role in inducing resistance in pancreatic cancer.

Role of HIF-1α in Ameloblastoma: A Systematic Review

Hypoxia-inducible factor-1α is a transcriptional protein that has been extensively researched in human cancers whose overexpression is found to be associated with unfavorable prognosis. Contemporary studies have proved its vital role in ameloblastoma by correlating its expression with the aggressiveness of the tumor. Therefore, an attempt was made to explore its significance in the malignant transformation and prognosis of ameloblastoma. The present systematic review aimed to understand the impact of HIF-1α in AMB which might lead to favorable outcomes in the treatment. An electronic search was carried out using PubMed, Scopus, Google scholar, Cochrane library, and EMBASE databases. Original articles from all languages involving HIF-1α in AMB were scrutinized by two independent authors. Data were compiled and tabulated in Microsoft Excel and the Risk of bias was analyzed using the JBI tool. Twelve eligible articles were included for the quantitative analysis comprising 305 cases of AMB in which HIF-1α expression was studied for various characteristics like pattern, intensity, and site of immunoexpression which were found to be increased with an increase in the aggressiveness of AMB. It was concluded that HIF-1α is proven to have a crucial role in the progression and aggressiveness of AMB. Extended research regarding the crucial role of HIF-1α in the initiation of tumors and therapies aiming at HIF-1α in AMB cases might show promising outcomes in the future.

Prognostic value of glucose transporter proteins-1 (GLUT1) in breast carcinoma

Several studies have reported increased glucose transporters (GLUT) expression in different cancer types, including breast cancer. The primary purpose of this study is to examine GLUT1 immunoexpression in breast cancer patients in Saudi Arabia and to determine its significance. The study examined the association between GLUT1 immunophenotype and the clinicopathological characteristics in breast cancer. GLUT1 expression was analyzed in retrospectively collected tissue samples (n = 578) from breast cancer patients using immunohistochemistry. A total of 311 (54%) of the cases expressed GLUT1 cytoplasmic immunohistochemical staining. In univariate analysis, we found a significant association between GLUT1 expression and high-grade tumors (p < 0.0001). Positive estrogen and progesterone receptor results predicted lower GLUT1 immunoexpression (p < 0.0001 for both). Vascular invasion showed a significant association with GLUT1 immunoexpression (p = 0.045). Our findings support that GLUT1 immunohistochemistry can be used as a marker to determine the grade and hormonal receptor status in breast cancer.

PEG-conjugated bovine haemoglobin enhances efficiency of chemotherapeutic agent doxorubicin with alleviating DOX-induced splenocardiac toxicity in the breast cancer

Doxorubicin (DOX) is an effective chemotherapeutic agent widely used for cancer treatment. However, hypoxia in tumour tissue and obvious adverse effects particularly cardiotoxicity restricts the clinical usage of DOX. Our study is based on the co-administration of haemoglobin-based oxygen carriers (HBOCs) and DOX in a breast cancer model to investigate HBOCs' ability to enhance chemotherapeutic effectiveness and its capabilities to alleviate the side effects induced by DOX. In an in-vitro study, the results suggested the cytotoxicity of DOX was significantly improved when combined with HBOCs in a hypoxic environment, and produced more γ-H2AX indicating higher DNA damage than free DOX did. Compared with administration of free DOX, combined therapy exhibited a stronger tumour suppressive effect in an in-vivo study. Further mechanism studies showed that the expression of various proteins such as hypoxia-inducible factor-1α (HIF-1α), CD31, CD34, and vascular endothelial growth factor (VEGF) in tumour tissues was also significantly reduced in the combined treatment group. In addition, HBOCs can significantly reduce the splenocardiac toxicity induced by DOX, according to the results of the haematoxylin and eosin (H&E) staining and histological investigation. This study suggested that PEG-conjugated bovine haemoglobin may not only reduce the hypoxia in tumours and increase the efficiency of chemotherapeutic agent DOX, but also alleviate the irreversible heart toxicity caused by DOX-inducted splenocardiac dysregulation.

Comparison effects of Ferula gummosa essential oil and Beta-pinene Alginate nanoparticles on human melanoma and breast cancer cells proliferation and apoptotic index in short term normobaric hyperoxic model

BACKGROUND

Breast cancer is the most common cancer among women, and melanoma is the most dreadful type of skin cancer. Due to the side effects of chemotherapy drugs, the development of new herbal nano-medicines has been considered.

METHODS

This study first investigated the chemical composition of Ferula gummosa essential oil using GC-MS analysis; β-pinene, with 61.57%, was the major compound. Next, alginate nanoparticles containing β-pinene and the essential oil with particle sizes of 174 ± 7 and 137 ± 6 nm were prepared. Meanwhile, their zeta potentials were 12.4 ± 0.7 and 28.1 ± 1 mV. Besides, the successful loading of β-pinene and the essential oil in nanoparticles was confirmed using ATR-FTIR analysis. After that, their effects on viability and apoptotic index of human melanoma and breast cancer cells were investigated in normoxia and normobaric hyperoxia (NBO) conditions.

RESULTS

The best efficacy on A-375 and MDA-MB-231 cells was achieved by alginate nanoparticles containing the EO at hyperoxic and normoxia conditions; IC50 76 and 104 µg/mL. Besides, it affected apoptosis-involved genes; as Bax/Bcl-2 ratio was higher than 1, conditions for induction of apoptosis were obtained. Higher sensitivity was observed in the A-375 cell line treated with Alg-EO in the NBO model.

CONCLUSIONS

Alginate nanoparticles containing F. gummosa EO could be considered for further investigation in anticancer studies. Also, it may be expected that NBO can be a new strategy for delaying cancer progression and improving nanotherapy efficacy.

Nanomedicine Strategies in Conquering and Utilizing the Cancer Hypoxia Environment

Cancer with a complex pathological process is a major disease to human welfare. Due to the imbalance between oxygen (O2) supply and consumption, hypoxia is a natural characteristic of most solid tumors and an important obstacle for cancer therapy, which is closely related to tumor proliferation, metastasis, and invasion. Various strategies to exploit the feature of tumor hypoxia have been developed in the past decade, which can be used to alleviate tumor hypoxia, or utilize the hypoxia for targeted delivery and diagnostic imaging. The strategies to alleviate tumor hypoxia include delivering O2, in situ O2 generation, reprogramming the tumor vascular system, decreasing O2 consumption, and inhibiting HIF-1 related pathways. On the other side, hypoxia can also be utilized for hypoxia-responsive chemical construction and hypoxia-active prodrug-based strategies. Taking advantage of hypoxia in the tumor region, a number of methods have been applied to identify and keep track of changes in tumor hypoxia. Herein, we thoroughly review the recent progress of nanomedicine strategies in both conquering and utilizing hypoxia to combat cancer and put forward the prospect of emerging nanomaterials for future clinical transformation, which hopes to provide perspectives in nanomaterials design.

Ultrasound-guided Photoacoustic image Annotation Toolkit in MATLAB (PHANTOM) for preclinical applications

Depth-dependent fluence-compensation in photoacoustic (PA) imaging is paramount for accurate quantification of chromophores from deep tissues. Here we present a user-friendly toolkit named PHANTOM (PHotoacoustic ANnotation TOolkit for MATLAB) that includes a graphical interface and assists in the segmentation of ultrasound-guided PA images. We modelled the light source configuration with Monte Carlo eXtreme and utilized 3D segmented tissues from ultrasound to generate fluence maps to depth compensate PA images. The methodology was used to analyze PA images of phantoms with varying blood oxygenation and results were validated with oxygen electrode measurements. Two preclinical models, a subcutaneous tumor and a calcified placenta, were imaged and fluence-compensated using the PHANTOM toolkit and the results were verified with immunohistochemistry. The PHANTOM toolkit provides scripts and auxiliary functions to enable biomedical researchers not specialized in optical imaging to apply fluence correction to PA images, enhancing accessibility of quantitative PAI for researchers in various fields.

Leveraging hypoxia in triple-negative breast cancer as a promising treatment strategy

Current treatment strategies for triple-negative breast cancer (TNBC) are based upon conventional chemotherapy, immunotherapy, or a combination of both. The treatment regimen for chemotherapy is often a combination of two or more drugs, either dose dense or low dose for synergy. Anthracyclines, alkylating agents, antimicrotubule agents, and antimetabolites for early-stage TNBC; and antimetabolites, non-taxane microtubule inhibitors, and cross-linker platinums for late-stage TNBC are usually administered in the clinical setting. Newer options for patients with advanced TNBC, such as poly (ADP-ribose) polymerase (PARP) inhibitors and immune checkpoint inhibitors, have recently emerged for cases where surgery is not a viable option and the disease has metastasized. This review outlines the current trends in hypoxia-inspired treatment strategies for TNBC with a focus on clinical trials.

Sononeoperfusion effect by ultrasound and microbubble promotes nitric oxide release to alleviate hypoxia in a mouse MC38 tumor model

Tumor hypoperfusion not only impedes therapeutic drug delivery and accumulation, but also leads to a hypoxic and acidic tumor microenvironment, resulting in tumor proliferation, invasion, and therapeutic resistance. Sononeoperfusion effect refers to tumor perfusion enhancement using ultrasound and microbubbles. This study aimed to further investigate hypoxia alleviation by sononeoperfusion effect and explore the characteristics and mechanism of sononeoperfusion effect. To stimulate the sononeoperfusion effect, mice bearing MC38 colon cancers were included in this study and diagnostic ultrasound for therapy was set at a mechanical index (MI) of 0.1, 0.3, and 0.5, frequency of 3 MHz, pulse length of 5 cycles, and pulse repetition frequency of 2000 Hz. The results demonstrated that a single ultrasound and microbubble (USMB) treatment resulted in tumor perfusion enhancement at MI = 0.3, and nitric oxide (NO) concentration increased at MI = 0.3/0.5 (P < 0.05). However, there were no significant difference in the hypoxia-inducible factor-1α (HIF-1α) or D-lactate (D-LA) (P > 0.05) levels. Multiple sononeoperfusion effects were observed at MI = 0.3/0.5 (P < 0.05). For each treatment, USMB slightly but steadily improved the tumor tissue oxygen partial pressure (pO2) during and post treatment. It alleviated tumor hypoxia by decreasing HIF-1α, D-LA level and the hypoxic immunofluorescence intensity at MI = 0.3/0.5 (P < 0.05). The sononeoperfusion effect was not stimulated after eNOS inhibition. In conclusion, USMB with appropriate MI could lead to a sononeoperfusion effect via NO release, resulting in hypoxia amelioration. The tumors were not resistant to multiple sononeoperfusion effects. Repeated sononeoperfusion is a promising approach for relieving tumor hypoxia and resistance to therapy.

Biophysics in tumor growth and progression: from single mechano-sensitive molecules to mechanomedicine

Evidence from physical sciences in oncology increasingly suggests that the interplay between the biophysical tumor microenvironment and genetic regulation has significant impact on tumor progression. Especially, tumor cells and the associated stromal cells not only alter their own cytoskeleton and physical properties but also remodel the microenvironment with anomalous physical properties. Together, these altered mechano-omics of tumor tissues and their constituents fundamentally shift the mechanotransduction paradigms in tumorous and stromal cells and activate oncogenic signaling within the neoplastic niche to facilitate tumor progression. However, current findings on tumor biophysics are limited, scattered, and often contradictory in multiple contexts. Systematic understanding of how biophysical cues influence tumor pathophysiology is still lacking. This review discusses recent different schools of findings in tumor biophysics that have arisen from multi-scale mechanobiology and the cutting-edge technologies. These findings range from the molecular and cellular to the whole tissue level and feature functional crosstalk between mechanotransduction and oncogenic signaling. We highlight the potential of these anomalous physical alterations as new therapeutic targets for cancer mechanomedicine. This framework reconciles opposing opinions in the field, proposes new directions for future cancer research, and conceptualizes novel mechanomedicine landscape to overcome the inherent shortcomings of conventional cancer diagnosis and therapies.

Inverse correlation between Alzheimer's disease and cancer from the perspective of hypoxia

Sporadic Alzheimer's disease and cancer remain epidemiologically inversely related, and exploring the reverse pathogenesis is important for our understanding of both. Cognitive dysfunctions in Alzheimer's disease (AD) might result from the depletion of adaptive reserves in the brain. Energy storage in the brain is limited and is dynamically regulated by neurovascular and neurometabolic coupling. The research on neurodegenerative diseases has been dominated by the neurocentric view that neuronal defects cause the diseases. However, the proposal of the 2-hit vascular hypothesis in AD led us to focus on alterations in the vasculature, especially hypoperfusion. Chronic hypoxia is a feature shared by AD and cancer. It is interesting how contradicting chronic hypoxia's effects on both cancer and AD are. In this article, we discuss the potential links between the 2 diseases' etiology, from comparable upstream circumstances to diametrically opposed downstream effects. We suggest opposing potential mechanisms, including upregulation and downregulation of hypoxia-inducible factor-1α, the Warburg and reverse-Warburg effects, lactate-mediated intracellular acidic and alkaline conditions, and VDAC1-mediated apoptosis and antiapoptosis, and search for regulators that may be identified as the crossroads between cancer and AD.

Hypoxia-inducing cryogels uncover key cancer-immune cell interactions in an oxygen-deficient tumor microenvironment

Hypoxia is a major factor shaping the immune landscape, and several cancer models have been developed to emulate hypoxic tumors. However, to date, they still have several limitations, such as the lack of reproducibility, inadequate biophysical cues, limited immune cell infiltration, and poor oxygen (O2) control, leading to non-pathophysiological tumor responses. Therefore, it is essential to develop better cancer models that mimic key features of the tumor extracellular matrix and recreate tumor-associated hypoxia while allowing cell infiltration and cancer-immune cell interactions. Herein, hypoxia-inducing cryogels (HICs) have been engineered using hyaluronic acid (HA) to fabricate three-dimensional microtissues and model a hypoxic tumor microenvironment. Specifically, tumor cell-laden HICs have been designed to deplete O2 locally and induce long-standing hypoxia. HICs promoted changes in hypoxia-responsive gene expression and phenotype, a metabolic adaptation to anaerobic glycolysis, and chemotherapy resistance. Additionally, HIC-supported tumor models induced dendritic cell (DC) inhibition, revealing a phenotypic change in the plasmacytoid DC (pDC) subset and an impaired conventional DC (cDC) response in hypoxia. Lastly, our HIC-based melanoma model induced CD8+ T cell inhibition, a condition associated with the downregulation of pro-inflammatory cytokine secretion, increased expression of immunomodulatory factors, and decreased degranulation and cytotoxic capacity of T cells. Overall, these data suggest that HICs can be used as a tool to model solid-like tumor microenvironments and has great potential to deepen our understanding of cancer-immune cell relationship in low O2 conditions and may pave the way for developing more effective therapies.

The Dual Luminescence Lifetime pH/Oxygen Sensor: Evaluation of Applicability for Intravital Analysis of 2D- and 3D-Cultivated Human Endometrial Mesenchymal Stromal Cells

The oxygenation of cells and tissues and acidification of the cellular endolysosomal system are among the major factors that ensure normal functioning of an organism and are violated in various pathologies. Recording of these parameters and their changes under various conditions is an important task for both basic research and clinical applications. In the present work, we utilized internalizable dual pH/O2 lifetime sensor (Ir-HSA-FITC) based on the covalent conjugation of human serum albumin (HSA) with fluorescein isothiocyanate (FITC) as pH sensor and an orthometalated iridium complex as O2 sensor. The probe was tested for simultaneous detection of acidification level and oxygen concentration in endolysosomes of endometrial mesenchymal stem/stromal cells (enMSCs) cultivated as 2D monolayers and 3D spheroids. Using a combined FLIM/PLIM approach, we found that due to high autofluorescence of enMSCs FITC lifetime signal in control cells was insufficient to estimate pH changes. However, using flow cytometry and confocal microscopy, we managed to detect the FITC signal response to inhibition of endolysosomal acidification by Bafilomycin A1. The iridium chromophore phosphorescence was detected reliably by all methods used. It was demonstrated that the sensor, accumulated in endolysosomes for 24 h, disappeared from proliferating 2D enMSCs by 72 h, but can still be recorded in non-proliferating spheroids. PLIM showed high sensitivity and responsiveness of iridium chromophore phosphorescence to experimental hypoxia both in 2D and 3D cultures. In spheroids, the phosphorescence signal was detected at a depth of up to 60 μm using PLIM and showed a gradient in the intracellular O2 level towards their center.

The relationship between cancer and biomechanics

The onset, development, diagnosis, and treatment of cancer involve intricate interactions among various factors, spanning the realms of mechanics, physics, chemistry, and biology. Within our bodies, cells are subject to a variety of forces such as gravity, magnetism, tension, compression, shear stress, and biological static force/hydrostatic pressure. These forces are perceived by mechanoreceptors as mechanical signals, which are then transmitted to cells through a process known as mechanical transduction. During tumor development, invasion and metastasis, there are significant biomechanical influences on various aspects such as tumor angiogenesis, interactions between tumor cells and the extracellular matrix (ECM), interactions between tumor cells and other cells, and interactions between tumor cells and the circulatory system and vasculature. The tumor microenvironment comprises a complex interplay of cells, ECM and vasculature, with the ECM, comprising collagen, fibronectins, integrins, laminins and matrix metalloproteinases, acting as a critical mediator of mechanical properties and a key component within the mechanical signaling pathway. The vasculature exerts appropriate shear forces on tumor cells, enabling their escape from immune surveillance, facilitating their dissemination in the bloodstream, dictating the trajectory of circulating tumor cells (CTCs) and playing a pivotal role in regulating adhesion to the vessel wall. Tumor biomechanics plays a critical role in tumor progression and metastasis, as alterations in biomechanical properties throughout the malignant transformation process trigger a cascade of changes in cellular behavior and the tumor microenvironment, ultimately culminating in the malignant biological behavior of the tumor.

Systematic investigation of mitochondrial transfer between cancer cells and T cells at single-cell resolution

Mitochondria (MT) participate in most metabolic activities of mammalian cells. A near-unidirectional mitochondrial transfer from T cells to cancer cells was recently observed to "metabolically empower" cancer cells while "depleting immune cells," providing new insights into tumor-T cell interaction and immune evasion. Here, we leverage single-cell RNA-seq technology and introduce MERCI, a statistical deconvolution method for tracing and quantifying mitochondrial trafficking between cancer and T cells. Through rigorous benchmarking and validation, MERCI accurately predicts the recipient cells and their relative mitochondrial compositions. Application of MERCI to human cancer samples identifies a reproducible MT transfer phenotype, with its signature genes involved in cytoskeleton remodeling, energy production, and TNF-α signaling pathways. Moreover, MT transfer is associated with increased cell cycle activity and poor clinical outcome across different cancer types. In summary, MERCI enables systematic investigation of an understudied aspect of tumor-T cell interactions that may lead to the development of therapeutic opportunities.

Molecular imaging of tumor hypoxia: Evolution of nitroimidazole radiopharmaceuticals and insights for future development

Though growing evidence has been collected in support of the concept of dose escalation based on the molecular level images indicating hypoxic tumor sub-volumes that could be radio-resistant, validation of the concept is still a work in progress. Molecular imaging of tumor hypoxia using radiopharmaceuticals is expected to provide the required input to plan dose escalation through Image Guided Radiation Therapy (IGRT) to kill/control the radio-resistant hypoxic tumor cells. The success of the IGRT, therefore, is heavily dependent on the quality of images obtained using the radiopharmaceutical and the extent to which the image represents the true hypoxic status of the tumor in spite of the heterogeneous nature of tumor hypoxia. Available literature on radiopharmaceuticals for imaging hypoxia is highly skewed in favor of nitroimidazole as the pharmacophore given their ability to undergo oxygen dependent reduction in hypoxic cells. In this context, present review on nitroimidazole radiopharmaceuticals would be immensely helpful to the researchers to obtain a birds-eye view on what has been achieved so far and what can be tried differently to obtain a better hypoxia imaging agent. The review also covers various methods of radiolabeling that could be utilized for developing radiotracers for hypoxia targeting applications.

pH/NIR-responsive and self-healing coatings with bacteria killing, osteogenesis, and angiogenesis performances on magnesium alloy

Although biodegradable polymer coatings can impede corrosion of magnesium (Mg)-based orthopedic implants, they are prone to excessive degradation and accidental scratching in practice. Bone implant-related infection and limited osteointegration are other factors that adversely impact clinical application of Mg-based biomedical implants. Herein, a self-healing polymeric coating is constructed on the Mg alloy together with incorporation of a stimuli-responsive drug delivery nanoplatform by a spin-spray layer-by-layer (SSLbL) assembly technique. The nanocontainers are based on simvastatin (SIM)-encapsulated hollow mesoporous silica nanoparticles (S@HMSs) modified with polydopamine (PDA) and polycaprolactone diacrylate (PCL-DA) bilayer. Owing to the dynamic reversible reactions, the hybrid coating shows a fast, stable, and cyclical water-enabled self-healing capacity. The antibacterial assay indicates good bacteria-killing properties under near infrared (NIR) irradiation due to synergistic effects of hyperthermia, reactive oxygens species (ROS), and SIM leaching. In vitro results demonstrate that NIR laser irradiation promotes the cytocompatibility, osteogenesis, and angiogenesis. The coating facilitates alkaline phosphatase activity and expedites extracellular matrix mineralization as well as expression of osteogenesis-related genes. This study reveals a useful strategy to develop multifunctional coatings on bioabsorbable Mg alloys for orthopedic implants.

In vitro and in vivo characterization of [64Cu][Cu(elesclomol)] as a novel theranostic agent for hypoxic solid tumors

PURPOSE

Hypoxic tumors are associated with therapy resistance and poor cancer prognosis, but methods to detect and counter tumor hypoxia remain insufficient. Our purpose was to investigate 64Cu(II)-elesclomol ([64Cu][Cu(ES)]) as a novel theranostic agent for hypoxic tumors, by implementing an improved production method and assessing its therapeutic and diagnostic potential compared to the established Cu-64 radiopharmaceuticals [64Cu]CuCl2 and [diacetyl-bis(N4-methylthiosemicarbazone) [64Cu][Cu(ATSM)].

METHODS

Cu-64 was produced using a biomedical cyclotron at 12 MeV with the reaction 64Ni(p,n)64Cu, followed by synthesis of [64Cu]CuCl2, [64Cu][Cu(ATSM)], and [64Cu][Cu(ES)]. In vitro therapeutic effects were assessed in both normoxic and hypoxic cells (22Rv1 and PC3 prostate cancer cells, and U-87MG glioblastoma cells) using the clonogenic assay and analyzing cellular uptake and internalization. In vivo therapeutic effects were assessed in 22Rv1 xenografts in BALB/cAnN-Foxn1nu/nu/Rj mice receiving a single or multiple doses of radiopharmaceutical, before their feasibility to detect tumor hypoxia was assessed by positron emission tomography (PET) in 22Rv1 and U-87MG xenografts.

RESULTS

In vitro and in vivo studies demonstrated that [64Cu][Cu(ES)] reduced cell survival and inhibited tumor growth more effectively than [64Cu][Cu(ATSM)] and [64Cu]CuCl2. Hypoxia increased the cellular uptake and internalization of [64Cu][Cu(ES)] and [64Cu][Cu(ATSM)]. [64Cu][Cu(ES)]-PET tumor hypoxia detection was feasible and also revealed an unexpected finding of uptake in the brain.

CONCLUSION

To the best of our knowledge, this is the first time that ES is radiolabeled with [64Cu]CuCl2 to [64Cu][Cu(ES)]. We demonstrated superior therapeutic effects of [64Cu][Cu(ES)] compared to [64Cu][Cu(ATSM)] and [64Cu]CuCl2 and that [64Cu][Cu(ES)]-PET is feasible. [64Cu][Cu(ES)] is a promising theranostic agent for hypoxic solid tumors.

NADH elevation during chronic hypoxia leads to VHL-mediated HIF-1α degradation via SIRT1 inhibition

BACKGROUND

Under conditions of hypoxia, cancer cells with hypoxia inducible factor-1α (HIF-1α) from heterogeneous tumor cells show greater aggression and progression in an effort to compensate for harsh environmental conditions. Extensive study on the stability of HIF-1α under conditions of acute hypoxia in cancer progression has been conducted, however, understanding of its involvement during the chronic phase is limited.

METHODS

In this study, we investigated the effect of SIRT1 on HIF1 stability in a typical chronic hypoxic conditon that maintains cells for 24 h under hypoxia using Western blotting, co-IP, measurement of intracellular NAD + and NADH levels, semi-quantitative RT-PCR analysis, invasion assay, gene knockdown.

RESULTS

Here we demonstrated that the high concentration of pyruvate in the medium, which can be easily overlooked, has an effect on the stability of HIF-1α. We also demonstrated that NADH functions as a signal for conveyance of HIF-1α degradation via the SIRT1 and VHL signaling pathway under conditions of chronic hypoxia, which in turn leads to attenuation of hypoxically strengthened invasion and angiogenic activities. A steep increase in the level of NADH occurs during chronic hypoxia, leading to upregulation of acetylation and degradation of HIF-1α via inactivation of SIRT1. Of particular interest, p300-mediated acetylation at lysine 709 of HIF-1α is recogonized by VHL, which leads to degradation of HIF-1α via ubiquitin/proteasome machinary under conditions of chronic hypoxia. In addition, we demonstrated that NADH-elevation-induced acetylation and subsequent degradation of HIF-1α was independent of proline hydroxylation.

CONCLUSIONS

Our findings suggest a critical role of SIRT1 as a metabolic sensor in coordination of hypoxic status via regulation of HIF-1α stability. These results also demonstrate the involvement of VHL in degradation of HIF-1α through recognition of PHD-mediated hydroxylation in normoxia and p300-mediated HIF-1α acetylation in hypoxia.

Interrogating bioinspired ESIPT/PCET-based Ir(iii)-complexes as organelle-targeted phototherapeutics: a redox-catalysis under hypoxia to evoke synergistic ferroptosis/apoptosis

Installing proton-coupled electron transfer (PCET) in Ir-complexes is indeed a newly explored phenomenon, offering high quantum efficiency and tunable photophysics; however, the prospects for its application in various fields, including interrogating biological systems, are quite open and exciting. Herein, we developed various organelle-targeted Ir(iii)-complexes by leveraging the photoinduced PCET process to see the opportunities in phototherapeutic application and investigate the underlying mechanisms of action (MOAs). We diversified the ligands' nature and also incorporated a H-bonded benzimidazole-phenol (BIP) moiety with π-conjugated ancillary ligands in Ir(iii) to study the excited-state intramolecular proton transfer (ESIPT) process for tuning dual emission bands and to tempt excited-state PCET. These visible or two-photon-NIR light activatable Ir-catalysts generate reactive hydroxyl radicals (˙OH) and simultaneously oxidize electron donating biomolecules (1,4-dihydronicotinamide adenine dinucleotide or glutathione) to disrupt redox homeostasis, downregulate the GPX4 enzyme, and amplify oxidative stress and lipid peroxide (LPO) accumulation. Our homogeneous photocatalytic platform efficiently triggers organelle dysfunction mediated by a Fenton-like pathway with spatiotemporal control upon illumination to evoke ferroptosis poised with the synergistic action of apoptosis in a hypoxic environment leading to cell death. Ir2 is the most efficient photochemotherapy agent among others, which provided profound cytophototoxicity to 4T1 and MCF-7 cancerous cells and inhibited solid hypoxic tumor growth in vitro and in vivo.

Carbon Ions for Hypoxic Tumors: Are We Making the Most of Them?

Hypoxia, which is associated with abnormal vessel growth, is a characteristic feature of many solid tumors that increases their metastatic potential and resistance to radiotherapy. Carbon-ion radiation therapy, either alone or in combination with other treatments, is one of the most promising treatments for hypoxic tumors because the oxygen enhancement ratio decreases with increasing particle LET. Nevertheless, current clinical practice does not yet fully benefit from the use of carbon ions to tackle hypoxia. Here, we provide an overview of the existing experimental and clinical evidence supporting the efficacy of C-ion radiotherapy in overcoming hypoxia-induced radioresistance, followed by a discussion of the strategies proposed to enhance it, including different approaches to maximize LET in the tumors.

Synthesis and Evaluation of 99mTc-Labelled 2-Nitroimidazole Derivatives with Different Linkers for Tumour Hypoxia Imaging

When developing novel radiopharmaceuticals, a linker moiety between the chelator and targeting vector can have a crucial influence on adjusting the affinity of the tracer and its biodistribution in organisms. To develop novel 99mTc-labelled hypoxia imaging radiotracers, in this study, five isocyanide-containing 2-nitroimidazole derivatives with different linkers (L1, L2, L3, L4 and L5) were synthesised and radiolabelled with technetium-99m to obtain five stable 99mTc-complexes ([99mTc]Tc-L1, [99mTc]Tc-L2, [99mTc]Tc-L3, [99mTc]Tc-L4 and [99mTc]Tc-L5). Corresponding rhenium analogues of [99mTc]Tc-L1 were synthesised and suggested the structures of these 99mTc-complexes would be a monovalent cation with a technetium (I) core surrounded by six ligands. [99mTc]Tc-L1 is hydrophilic, while the lipophilicities of [99mTc]Tc-L2, [99mTc]Tc-L3, [99mTc]Tc-L4 and [99mTc]Tc-L5 are close. In vitro cell experiments showed that all five novel 99mTc-complexes had higher uptake in hypoxic cells compared with aerobic cells, which indicates the complexes have good hypoxia selectivity. The biodistribution of the five 99mTc-complexes in S180 tumour-bearing mice showed that they all had certain uptake in the tumours. Among them, [99mTc]Tc-L1 had the highest tumour-to-muscle (4.68 ± 0.44) and tumour-to-blood (3.81 ± 0.46) ratios. The introduction of polyethylene glycol (PEG) chains effectively reduced the lipophilicity and decreased uptake by the liver, intestine and blood but also increased clearance from the tumours. In vivo metabolic studies showed [99mTc]Tc-L1 kept intact and remained stable in tumour, blood and urine at 2 h post-injection. The results of SPECT imaging showed that [99mTc]Tc-L1 had significant tumour uptake at 2 h post-injection, but there was still high uptake in abdominal organs such as the liver and kidney, suggesting that this complex needs to be further optimised before being used for tumour hypoxia imaging.

NIR diagnostic imaging of triple-negative breast cancer and its lymph node metastasis for high-efficiency hypoxia-activated multimodal therapy

BACKGROUND

Triple-negative breast cancer (TNBC) possesses special biological behavior and clinicopathological characteristics, which is highly invasive and propensity to metastasize to lymph nodes, leading to a worse prognosis than other types of breast cancer. Thus, the development of an effective therapeutic method is significant to improve the survival rate of TNBC patients.

RESULTS

In this work, a liposome-based theranostic nanosystem (ILA@Lip) was successfully prepared by simultaneously encapsulating IR 780 as the photosensitizer and lenvatinib as an anti-angiogenic agent, together with banoxantrone (AQ4N) molecule as the hypoxia-activated prodrug. The ILA@Lip can be applied for the near-infrared (NIR) fluorescence diagnostic imaging of TNBC and its lymph node metastasis for multimodal therapy. Lenvatinib in ILA@Lip can inhibit angiogenesis by cutting oxygen supply, thereby leading to enhanced hypoxia levels. Meanwhile, large amounts of reactive oxygen species (ROS) were produced while IR 780 was irradiated by an 808 nm laser, which also rapidly exhausted oxygen in tumor cells to worsen tumor hypoxia. Through creating an extremely hypoxic in TNBC, the conversion of non-toxic AQ4N to toxic AQ4 was much more efficiency for hypoxia-activated chemotherapy. Cytotoxicity assay of ILA@Lip indicated excellent biocompatibility with normal cells and tissues, but showed high toxicity in hypoxic breast cancer cells. Also, the in vivo tumors treated by the ILA@Lip with laser irradiation were admirably suppressed in both subcutaneous tumor model and orthotopic tumor models.

CONCLUSION

Utilizing ILA@Lip is a profound strategy to create an extremely hypoxic tumor microenvironment for higher therapeutic efficacy of hypoxia-activated chemotherapy, which realized collective suppression of tumor growth and has promising potential for clinical translation.

Revolutionizing cancer treatment: The power of cell-based drug delivery systems

Intravenous administration of drugs is a widely used cancer therapy approach. However, the efficacy of these drugs is often hindered by various biological barriers, including circulation, accumulation, and penetration, resulting in poor delivery to solid tumors. Recently, cell-based drug delivery platforms have emerged as promising solutions to overcome these limitations. These platforms offer several advantages, including prolonged circulation time, active targeting, controlled release, and excellent biocompatibility. Cell-based delivery systems encompass cell membrane coating, intracellular loading, and extracellular backpacking. These innovative platforms hold the potential to revolutionize cancer diagnosis, monitoring, and treatment, presenting a plethora of opportunities for the advancement and integration of pharmaceuticals, medicine, and materials science. Nevertheless, several technological, ethical, and financial barriers must be addressed to facilitate the translation of these platforms into clinical practice. In this review, we explore the emerging strategies to overcome these challenges, focusing specifically on the functions and advantages of cell-mediated drug delivery in cancer treatment.

Targeted therapy for head and neck squamous cell carcinoma microenvironment

Head and neck squamous cell carcinoma (HNSCC) originates from the squamous epithelium of the oral cavity, oropharynx, larynx, and hypopharynx. HNSCC in the oral cavity and larynx is strongly associated with tobacco smoking and alcohol consumption, while oropharyngeal cancer is increasingly attributed to infection by human papillomavirus (HPV), particularly HPV-16. The tumor microenvironment (TME) is a complex network of cancer cells, immune cells, stromal cells, surrounding blood vessels, and signaling molecules, and plays a critical role in tumor cell survival, invasion, and recurrence. Therefore, it is critical to elucidate the molecular basis of the interaction between tumor cells and the TME in order to develop innovative anti-cancer therapeutic strategies.

Thieno[3,4-d]pyrimidin-4(3H)-thione: an effective, oxygenation independent, heavy-atom-free photosensitizer for cancer cells

All-organic, heavy-atom-free photosensitizers based on thionation of nucleobases are receiving increased attention because they are easy to make, noncytotoxic, work both in the presence and absence of molecular oxygen, and can be readily incorporated into DNA and RNA. In this contribution, the DNA and RNA fluorescent probe, thieno[3,4-d]pyrimidin-4(1H)-one, has been thionated to develop thieno[3,4-d]pyrimidin-4(3H)-thione, which is nonfluorescent and absorbs near-visible radiation with about 60% higher efficiency. Steady-state absorption and emission spectra are combined with transient absorption spectroscopy and CASPT2 calculations to delineate the electronic relaxation mechanisms of both pyrimidine derivatives in aqueous and acetonitrile solutions. It is demonstrated that thieno[3,4-d]pyrimidin-4(3H)-thione efficiently populates the long-lived and reactive triplet state generating singlet oxygen with a quantum yield of about 80% independent of solvent. It is further shown that thieno[3,4-d]pyrimidin-4(3H)-thione exhibits high photodynamic efficacy against monolayer melanoma cells and cervical cancer cells both under normoxic and hypoxic conditions. Our combined spectroscopic, computational, and in vitro data demonstrate the excellent potential of thieno[3,4-d]pyrimidin-4(1H)-thione as a heavy-atom-free PDT agent and paves the way for further development of photosensitizers based on the thionation of thieno[3,4-d]pyrimidine derivatives. Collectively, the experimental and computational results demonstrate that thieno[3,4-d]pyrimidine-4(3H)-thione stands out as the most promising thiobase photosensitizer developed to this date.

Nanomedicine Strategies for Targeting Tumor Stroma

The tumor stroma, or the microenvironment surrounding solid tumors, can significantly impact the effectiveness of cancer therapies. The tumor microenvironment is characterized by high interstitial pressure, a consequence of leaky vasculature, and dense stroma created by excessive deposition of various macromolecules such as collagen, fibronectin, and hyaluronic acid (HA). In addition, non-cancerous cells such as cancer-associated fibroblasts (CAFs) and the extracellular matrix (ECM) itself can promote tumor growth. In recent years, there has been increased interest in combining standard cancer treatments with stromal-targeting strategies or stromal modulators to improve therapeutic outcomes. Furthermore, the use of nanomedicine, which can improve the delivery and retention of drugs in the tumor, has been proposed to target the stroma. This review focuses on how different stromal components contribute to tumor progression and impede chemotherapeutic delivery. Additionally, this review highlights recent advancements in nanomedicine-based stromal modulation and discusses potential future directions for developing more effective stroma-targeted cancer therapies.

Bioorthogonally Assisted Phototherapy: Recent Advances and Prospects

Photoresponsive materials offer excellent spatiotemporal control over biological processes and the emerging phototherapeutic methods are expected to have significant effects on targeted cancer therapies. Recent examples show that combination of photoactivatable approaches with bioorthogonal chemistry enhances the precision of targeted phototherapies and profound implications are foreseen particularly in the treatment of disperse/diffuse tumors. The extra level of on-target selectivity and improved spatial/temporal control considerably intensified related bioorthogonally assisted phototherapy research. The anticipated growth of further developments in the field justifies the timeliness of a brief summary of the state of the art.

The hypoxia-associated genes in immune infiltration and treatment options of lung adenocarcinoma

Background

Lung adenocarcinoma (LUAD) is a common lung cancer with a poor prognosis under standard chemotherapy. Hypoxia is a crucial factor in the development of solid tumors, and hypoxia-related genes (HRGs) are closely associated with the proliferation of LUAD cells.

Methods

In this study, LUAD HRGs were screened, and bioinformatics analysis and experimental validation were conducted. The Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO) databases were used to gather LUAD RNA-seq data and accompanying clinical information. LUAD subtypes were identified by unsupervised cluster analysis, and immune infiltration analysis of subtypes was conducted by GSVA and ssGSEA. Cox regression and LASSO regression analyses were used to obtain prognosis-related HRGs. Prognostic analysis was used to evaluate HRGs. Differences in enrichment pathways and immunotherapy were observed between risk groups based on GSEA and the TIDE method. Finally, RT-PCR and in vitro experiments were used to confirm prognosis-related HRG expression in LUAD cells.

Results

Two hypoxia-associated subtypes of LUAD were distinguished, demonstrating significant differences in prognostic analysis and immunological characteristics between subtypes. A prognostic model based on six HRGs (HK1, PDK3, PFKL, SLC2A1, STC1, and XPNPEP1) was developed for LUAD. HK1, SLC2A1, STC1, and XPNPEP1 were found to be risk factors for LUAD. PDK3 and PFKL were protective factors in LUAD patients.

Conclusion

This study demonstrates the effect of hypoxia-associated genes on immune infiltration in LUAD and provides options for immunotherapy and therapeutic strategies in LUAD.

Morphological and molecular-biological features of glioblastoma progression in tolerant and susceptible to hypoxia Wistar rats

Hypoxia is a major pathogenetic factor in many cancers. Individual resistance to suboptimal oxygen availability is subject to broad variation and its possible role in tumorigenesis remains underexplored. This study aimed at specific characterization of glioblastoma progression in male tolerant and susceptible to hypoxia Wistar rats. Hypoxia resistance was assessed by gasping time measurement in an 11,500 m altitude-equivalent hypobaric decompression chamber. Based on the outcome, the animals were assigned to three groups termed 'tolerant to hypoxia' (n = 13), 'normal', and 'susceptible to hypoxia' (n = 24). The 'normal' group was excluded from subsequent experiments. One month later, the animals underwent inoculation with rat glioblastoma 101.8 followed by monitoring of survival, body weight dynamics and neurological symptoms. The animals were sacrificed on post-inoculation days 11 (subgroup 1) and 15 (subgroup 2). Relative vessels number, necrosis areas and Ki-67 index were assessed microscopically; tumor volumes were determined by 3D reconstruction from histological images; serum levels of HIF-1α, IL-1β, and TNFα were determined by ELISA. None of the tolerant to hypoxia animals died of the disease during observation period, cf. 85% survival on day 11 and 55% survival on day 15 in the susceptible group. On day 11, proliferative activity of the tumors in the tolerant animals was higher compared with the susceptible group. On day 15, proliferative activity, necrosis area and volume of the tumors in the tolerant to hypoxia animals were higher compared with the susceptible group. ELISA revealed no dynamics in TNFα levels, elevated levels of IL-1β in the susceptible animals on day 15 in comparison with day 11 and tolerant ones. Moreover, there were elevated levels of HIF-1α in the tolerant animals on day 15 in comparison with day 11. Thus, the proliferative activity of glioblastoma cells and the content of HIF-1α were higher in tolerant to hypoxia rats, but the mortality associated with the tumor process and IL-1β level in them were lower than in susceptible animals. Specific features of glioblastoma 101.8 progression in tolerant and susceptible to hypoxia rats, including survival, tumor growth rates and IL-1β level, can become the basis of new personalized approaches for cancer diseases treatment in accordance to individual hypoxia resistance.

Self-assembled nanoformulations of paclitaxel for enhanced cancer theranostics

Chemotherapy has occupied the critical position in cancer therapy, especially towards the post-operative, advanced, recurrent, and metastatic tumors. Paclitaxel (PTX)-based formulations have been widely used in clinical practice, while the therapeutic effect is far from satisfied due to off-target toxicity and drug resistance. The caseless multi-components make the preparation technology complicated and aggravate the concerns with the excipients-associated toxicity. The self-assembled PTX nanoparticles possess a high drug content and could incorporate various functional molecules for enhancing the therapeutic index. In this work, we summarize the self-assembly strategy for diverse nanodrugs of PTX. Then, the advancement of nanodrugs for tumor therapy, especially emphasis on mono-chemotherapy, combinational therapy, and theranostics, have been outlined. Finally, the challenges and potential improvements have been briefly spotlighted.

Immunohistochemistry and oxygen saturation endoscopic imaging reveal hypoxia in submucosal invasive esophageal squamous cell carcinoma

BACKGROUND

Hypoxic microenvironment is prominent in advanced esophageal squamous cell carcinoma (ESCC). However, it is unclear whether ESCC becomes hypoxic when it remains in the mucosal layer or as it invades the submucosal layer. We aimed to investigate whether intramucosal (Tis-T1a) or submucosal invasive (T1b) ESCC becomes hypoxic using endoscopic submucosal dissection samples.

METHODS

We evaluated the expression of hypoxia markers including hypoxia inducible factor 1α (HIF-1α), carbonic anhydrase IX (CAIX), and glucose transporter 1 (GLUT1) by H-score and vessel density by microvessel count (MVC) and microvessel density (MVD) for CD31 and α-smooth muscle actin (α-SMA) with immunohistochemical staining (n = 109). Further, we quantified oxygen saturation (StO2 ) with oxygen saturation endoscopic imaging (OXEI) (n = 16) and compared them to non-neoplasia controls, Tis-T1a, and T1b.

RESULTS

In Tis-T1a, cccIX (13.0 vs. 0.290, p < 0.001) and GLUT1 (199 vs. 37.6, p < 0.001) were significantly increased. Similarly, median MVC (22.7/mm2 vs. 14.2/mm2 , p < 0.001) and MVD (0.991% vs. 0.478%, p < 0.001) were markedly augmented. Additionally, in T1b, the mean expression of HIF-1α (16.0 vs. 4.95, p < 0.001), CAIX (15.7 vs. 0.290, p < 0.001), and GLUT1 (177 vs. 37.6, p < 0.001) were significantly heightened, and median MVC (24.8/mm2 vs. 14.2/mm2 , p < 0.001) and MVD (1.51% vs. 0.478%, p < 0.001) were markedly higher. Furthermore, OXEI revealed that median StO2 was significantly lower in T1b than in non-neoplasia (54% vs. 61.5%, p = 0.00131) and tended to be lower in T1b than in Tis-T1a (54% vs. 62%, p = 0.0606).

CONCLUSION

These results suggest that ESCC becomes hypoxic even at an early stage, and is especially prominent in T1b.

Macrophage-reprogramming upconverting nanoparticles for enhanced TAM-mediated antitumor therapy of hypoxic breast cancer

In an attempt to achieve antitumor effects by switching the phenotype of macrophages from the tumor-promoting M2 type to the tumor-suppressing M1 type, we fabricated mannose-decorated/macrophage membrane-coated, silica-layered NaErF4@NaLuF4 upconverting nanoparticles (UCNPs) co-doped with perfluorocarbon (PFC)/chlorin e6 (Ce6) and loaded with paclitaxel (PTX) (UCNP@mSiO2-PFC/Ce6@RAW-Man/PTX: ∼61 nm; -11.6 mV). These nanoparticles were designed to have two major functionalities, (i) efficient singlet oxygen generation aided by an oxygen supply and (ii) good targeting to tumor-associated macrophage (TAMs) (M2-type), to induce polarization to M1 type macrophages that release proinflammatory cytokines and suppress breast cancers. The primary UCNPs consisted of lanthanide elements (erbium and lutetium) in a core@shell structure, and they facilely emitted 660 nm light in response to a deep-penetrating 808 nm near-infrared laser. Moreover, the UCNPs@mSiO2-PFC/Ce6@RAW-Man/PTX were able to release O2 and generate 1O2 because of the co-doped PFC/Ce6 and upconversion. Our nanocarriers' excellent uptake to RAW 264.7 macrophage cells (M2 type) and efficient M1-type polarization activity were clearly demonstrated using qRT-PCR and immunofluorescence-based confocal laser scanning microscopy. Our nanocarriers displayed significant cytotoxicity to 4T1 cells in 2D culture and 3D co-culture systems of 4T1/RAW 264.7 cells. More importantly, UCNPs@mSiO2-PFC/Ce6@RAW-Man/PTX (+808 nm laser) noticeably suppressed tumor growth in 4T1-xenografted mice, compared with the other treatment groups (332.4 vs. 709.5-1185.5 mm3). We attribute this antitumor efficacy to the prominent M1-type macrophage polarization caused by our nanocarriers through efficient ROS/O2 generation and targeting of M2-type TAMs via mannose ligands on coated macrophage-membrane.

Angiogenesis and prostate cancer: MicroRNAs comes into view

Angiogenesis, the formation of new blood vessels, is an important stage in the growth of cancer. Extracellular matrix, endothelial cells, and soluble substances must be carefully coordinated during the multistep procedure of angiogenesis. Inducers and inhibitors have been found to control pretty much every phase. In addition to benign prostatic hyperplasia, prostatic intraepithelial neoplasia, and angiogenesis have a critical role in the initiation and progression of prostate cancer. MicroRNA (miRNA) is endogenous, short, non-coding RNA molecules of almost 22 nucleotides play a role in regulating cellular processes and regulating several genes' expression. Through controlling endothelial migration, differentiation, death, and cell proliferation, miRNAs have a significant function in angiogenesis. A number of pathological and physiological processes, particularly prostate cancer's emergence, depend on the regulation of angiogenesis. Investigating the functions played with miRNAs in angiogenesis is crucial because it might result in the creation of novel prostate cancer therapies that entail regulating angiogenesis. The function of several miRNAs and its targeting genes engaged in cancer of the prostate angiogenesis will be reviewed in this review in light of the most recent developments. The potential clinical utility of miRNAs potentially a novel therapeutic targets will also be explored, as well as their capacity to control prostate cancer angiogenesis and the underlying mechanisms.

Hypoxia: syndicating triple negative breast cancer against various therapeutic regimens

Triple-negative breast cancer (TNBC) is one of the deadliest subtypes of breast cancer (BC) for its high aggressiveness, heterogeneity, and hypoxic nature. Based on biological and clinical observations the TNBC related mortality is very high worldwide. Emerging studies have clearly demonstrated that hypoxia regulates the critical metabolic, developmental, and survival pathways in TNBC, which include glycolysis and angiogenesis. Alterations to these pathways accelerate the cancer stem cells (CSCs) enrichment and immune escape, which further lead to tumor invasion, migration, and metastasis. Beside this, hypoxia also manipulates the epigenetic plasticity and DNA damage response (DDR) to syndicate TNBC survival and its progression. Hypoxia fundamentally creates the low oxygen condition responsible for the alteration in Hypoxia-Inducible Factor-1alpha (HIF-1α) signaling within the tumor microenvironment, allowing tumors to survive and making them resistant to various therapies. Therefore, there is an urgent need for society to establish target-based therapies that overcome the resistance and limitations of the current treatment plan for TNBC. In this review article, we have thoroughly discussed the plausible significance of HIF-1α as a target in various therapeutic regimens such as chemotherapy, radiotherapy, immunotherapy, anti-angiogenic therapy, adjuvant therapy photodynamic therapy, adoptive cell therapy, combination therapies, antibody drug conjugates and cancer vaccines. Further, we also reviewed here the intrinsic mechanism and existing issues in targeting HIF-1α while improvising the current therapeutic strategies. This review highlights and discusses the future perspectives and the major alternatives to overcome TNBC resistance by targeting hypoxia-induced signaling.

Advancement and application of novel cell-penetrating peptide in cancer management

Cell-penetrating peptides (CPPs) are small amino acid sequences with the potential to enter cell membranes. Along with nucleic acids, large proteins, and other chemical compounds, they can deliver several bioactive cargos inside cells. Numerous CPPs have been extracted from natural or synthetic materials since the discovery of the first CPP. In the past few decades, a significant variety of studies have shown the potential of CPPs to cure different diseases. The low toxicity in peptide compared to other drug delivery carriers is a significant benefit of CPP-based therapy, in addition to the high efficacy brought about by swift and effective delivery. A significant tendency for intracellular DNA delivery may also be observed when nanoparticles and the cell penetration peptide are combined. CPPs are frequently used to increase intracellular absorption of nucleic acid, and other therapeutic agents inside the cell. Due to long-term side effects and possible toxicity, its implementation is restricted. The use of cell-permeating peptides is a commonly used technique to increase their intracellular absorption. Additionally, CPPs have lately been sought for application in vivo, following their success in cellular studies. This review will go through the numerous CPPs, the chemical modifications that improve their cellular uptake, the various means for getting them across cell membranes, and the biological activity they acquire after being conjugate with specific chemicals.

Recent Developments in PET and SPECT Radiotracers as Radiopharmaceuticals for Hypoxia Tumors

Hypoxia, a deficiency in the levels of oxygen, is a common feature of most solid tumors and induces many characteristics of cancer. Hypoxia is associated with metastases and strong resistance to radio- and chemotherapy, and can decrease the accuracy of cancer prognosis. Non-invasive imaging methods such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) using hypoxia-targeting radiopharmaceuticals have been used for the detection and therapy of tumor hypoxia. Nitroimidazoles are bioreducible moieties that can be selectively reduced under hypoxic conditions covalently bind to intracellular macromolecules, and are trapped within hypoxic cells and tissues. Recently, there has been a strong motivation to develop PET and SPECT radiotracers as radiopharmaceuticals containing nitroimidazole moieties for the visualization and treatment of hypoxic tumors. In this review, we summarize the development of some novel PET and SPECT radiotracers as radiopharmaceuticals containing nitroimidazoles, as well as their physicochemical properties, in vitro cellular uptake values, in vivo biodistribution, and PET/SPECT imaging results.

Recent Advances of 68Ga-Labeled PET Radiotracers with Nitroimidazole in the Diagnosis of Hypoxia Tumors

Positron emission tomography (PET) is a noninvasive molecular imaging method extensively applied in the detection and treatment of various diseases. Hypoxia is a common phenomenon found in most solid tumors. Nitroimidazole is a group of bioreducible pharmacophores that selectively accumulate in hypoxic regions of the body. Over the past few decades, many scientists have reported the use of radiopharmaceuticals containing nitroimidazole for the detection of hypoxic tumors. Gallium-68, a positron-emitting radioisotope, has a favorable half-life time of 68 min and can be conveniently produced by ⁶⁸Ge/⁶⁸Ga generators. Recently, there has been significant progress in the preparation of novel ⁶⁸Ga-labeled complexes bearing nitroimidazole moieties for the diagnosis of hypoxia. This review provides a comprehensive overview of the current status of developing ⁶⁸Ga-labeled radiopharmaceuticals with nitroimidazole moieties, their pharmacokinetics, and in vitro and in vivo studies, as well as PET imaging studies for hypoxic tumors.

Fluorescence microscopy imaging of mitochondrial metabolism in cancer cells

Mitochondrial metabolism is an important contributor to cancer cell survival and proliferation that coexists with enhanced glycolytic activity. Measuring mitochondrial activity is useful to characterize cancer metabolism patterns, to identify metabolic vulnerabilities and to identify new drug targets. Optical imaging, especially fluorescent microscopy, is one of the most valuable tools for studying mitochondrial bioenergetics because it provides semiquantitative and quantitative readouts as well as spatiotemporal resolution of mitochondrial metabolism. This review aims to acquaint the reader with microscopy imaging techniques currently used to determine mitochondrial membrane potential (ΔΨm), nicotinamide adenine dinucleotide (NADH), ATP and reactive oxygen species (ROS) that are major readouts of mitochondrial metabolism. We describe features, advantages, and limitations of the most used fluorescence imaging modalities: widefield, confocal and multiphoton microscopy, and fluorescent lifetime imaging (FLIM). We also discus relevant aspects of image processing. We briefly describe the role and production of NADH, NADHP, flavins and various ROS including superoxide and hydrogen peroxide and discuss how these parameters can be analyzed by fluorescent microscopy. We also explain the importance, value, and limitations of label-free autofluorescence imaging of NAD(P)H and FAD. Practical hints for the use of fluorescent probes and newly developed sensors for imaging ΔΨm, ATP and ROS are described. Overall, we provide updated information about the use of microscopy to study cancer metabolism that will be of interest to all investigators regardless of their level of expertise in the field.

Perspectives for Improving the Tumor Targeting of Nanomedicine via the EPR Effect in Clinical Tumors

Over the past few decades, the enhanced permeability and retention (EPR) effect of nanomedicine has been a crucial phenomenon in targeted cancer therapy. Specifically, understanding the EPR effect has been a significant aspect of delivering anticancer agents efficiently to targeted tumors. Although the therapeutic effect has been demonstrated in experimental models using mouse xenografts, the clinical translation of the EPR effect of nanomedicine faces several challenges due to dense extracellular matrix (ECM), high interstitial fluid pressure (IFP) levels, and other factors that arise from tumor heterogeneity and complexity. Therefore, understanding the mechanism of the EPR effect of nanomedicine in clinics is essential to overcome the hurdles of the clinical translation of nanomedicine. This paper introduces the basic mechanism of the EPR effect of nanomedicine, the recently discussed challenges of the EPR effect of nanomedicine, and various strategies of recent nanomedicine to overcome the limitations expected from the patients' tumor microenvironments.

Quantitative intravital imaging for real-time monitoring of pancreatic tumor cell hypoxia and stroma in an orthotopic mouse model

Pancreatic cancer is a lethal disease with few successful treatment options. Recent evidence demonstrates that tumor hypoxia promotes pancreatic tumor invasion, metastasis, and therapy resistance. However, little is known about the complex relationship between hypoxia and the pancreatic tumor microenvironment (TME). In this study, we developed a novel intravital fluorescence microscopy platform with an orthotopic mouse model of pancreatic cancer to study tumor cell hypoxia within the TME in vivo, at cellular resolution, over time. Using a fluorescent BxPC3-DsRed tumor cell line with a hypoxia-response element (HRE)/green fluorescent protein (GFP) reporter, we showed that HRE/GFP is a reliable biomarker of pancreatic tumor hypoxia, responding dynamically and reversibly to changing oxygen concentrations within the TME. We also characterized the spatial relationships between tumor hypoxia, microvasculature, and tumor-associated collagen structures using in vivo second harmonic generation microscopy. This quantitative multimodal imaging platform enables the unprecedented study of hypoxia within the pancreatic TME in vivo.