Mimicking Tumor Hypoxia in Non-Small Cell Lung Cancer Employing Three-Dimensional In Vitro Models

Improving therapeutic strategies for Head and Neck Cancer: Insights from 3D hypoxic cell culture models in treatment response evaluation

Hypoxia in the tumor core negatively affects the outcome of patients with head and neck squamous cell carcinoma (HNSCC). Nevertheless, its role in predicting treatment response requires further exploration. Typically, reduced oxygen levels in the tumor core correlate with diminished efficacy of radiotherapy, chemotherapy, and immunotherapy, which are commonly used for HNSCC patients' treatment. Understanding the mechanistic underpinnings of these varied treatment responses in HNSCC is crucial for enhancing therapeutic outcomes and extending patients' overall survival (OS) rates. Standard monolayer cell culture conditions have major limitations in mimicking tumor physiological features and the complexity of the tumor microenvironment. Three-dimensional (3D) cell cultures enable the recreation of the in vivo tumor attributes, encompassing oxygen and nutrient gradients, cellular morphology, and intracellular connections. It is vital to use the 3D model in treatment response studies to mimic the tumor microenvironment, as evidenced by the decreased sensitivity of 3D structures to anticancer therapy. Accordingly, the aim of the study was to delineate the utility of the 3D models of hypoxic head and neck tumors in drug screening and treatment response studies.

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.

Hypoxia-induced activation of NDR2 underlies brain metastases from Non-Small Cell Lung Cancer

The molecular mechanisms induced by hypoxia are misunderstood in non-small cell lung cancer (NSCLC), and above all the hypoxia and RASSF1A/Hippo signaling relationship. We confirmed that human NSCLC (n = 45) as their brain metastases (BM) counterpart are hypoxic since positive with CAIX-antibody (target gene of Hypoxia-inducible factor (HIF)). A severe and prolonged hypoxia (0.2% O2, 48 h) activated YAP (but not TAZ) in Human Bronchial Epithelial Cells (HBEC) lines by downregulating RASSF1A/kinases Hippo (except for NDR2) regardless their promoter methylation status. Subsequently, the NDR2-overactived HBEC cells exacerbated a HIF-1A, YAP and C-Jun-dependent-amoeboid migration, and mainly, support BM formation. Indeed, NDR2 is more expressed in human tumor of metastatic NSCLC than in human localized NSCLC while NDR2 silencing in HBEC lines (by shRNA) prevented the xenograft formation and growth in a lung cancer-derived BM model in mice. Collectively, our results indicated that NDR2 kinase is over-active in NSCLC by hypoxia and supports BM formation. NDR2 expression is thus a useful biomarker to predict the metastases risk in patients with NSCLC, easily measurable routinely by immunohistochemistry on tumor specimens.

Non-coding RNA-directed therapeutics in lung cancer: Delivery technologies and clinical applications

Lung cancer is one of the most aggressive and deadliest health threats. There has been an increasing interest in non-coding RNA (ncRNA) recently, especially in the areas of carcinogenesis and tumour progression. However, ncRNA-directed therapies are still encountering obstacles on their way to the clinic. In the present article, we provide an overview on the potential of targeting ncRNA in the treatment of lung cancer. Then, we discuss the delivery challenges and recent approaches enabling the delivery of ncRNA-directed therapies to the lung cancer cells, where we illuminate some advanced technologies including chemically-modified oligonucleotides, nuclear targeting, and three-dimensional in vitro models. Furthermore, advanced non-viral delivery systems recruiting nanoparticles, biomimetic delivery systems, and extracellular vesicles are also highlighted. Lastly, the challenges limiting the clinical trials on the therapeutic targeting of ncRNAs in lung cancer and future directions to tackle them are explored.

A decellularized lung extracellular matrix/chondroitin sulfate/gelatin/chitosan-based 3D culture system shapes breast cancer lung metastasis

Distal metastasis of breast cancer is a primary cause of death, and the lung is a common metastatic target of breast cancer. However, the role of the lung niche in promoting breast cancer progression is not well understood. Engineered three-dimensional (3D) in vitro models capable of bridging this knowledge gap can be specifically designed to mimic crucial characteristics of the lung niche in a more physiologically relevant context than conventional two-dimensional systems. In this study, two 3D culture systems were developed to mimic the late stage of breast cancer progression at a lung metastatic site. These 3D models were created based on a novel decellularized lung extracellular matrix/chondroitin sulfate/gelatin/chitosan composite material and on a porcine decellularized lung matrix (PDLM), with the former tailored with comparable properties (stiffness, pore size, biochemical composition, and microstructure) to that of the in vivo lung matrix. The different microstructure and stiffness of the two types of scaffolds yielded diverse presentations of MCF-7 cells in terms of cell distribution, cell morphology, and migration. Cells showed better extensions with apparent pseudopods and more homogeneous and reduced migration activity on the composite scaffold compared to those on the PDLM scaffold. Furthermore, alveolar-like structures with superior porous connectivity in the composite scaffold remarkably promoted aggressive cell proliferation and viability. In conclusion, a novel lung matrix-mimetic 3D in vitro breast cancer lung metastasis model was developed to clarify the underlying correlativity between lung ECM and breast cancer cells after lung colonization. A better understanding of the effects of biochemical and biophysical environments of the lung matrix on cell behaviors can help elucidate the potential mechanisms of breast cancer progression and further improve target discovery of therapeutic strategies.

Experimental assessment of robust reference genes for qRT-PCR in lung cancer studies

Stable internal reference genes are crucial for quantitative real-time PCR (qRT-PCR) analyses in lung cancer studies. Widely used reference genes are mostly chosen by intuition or from pan-cancer transcriptome data and lack experimental validation by qRT-PCR in the context of lung cancer. This study evaluated the stability of candidate reference genes in lung cancer cell lines under normal homeostasis, hypoxia, and serum deprivation to screen for robust reference genes for qRT-PCR in lung cancer studies. The stability of reference gene combinations was also assessed. We found that most of the stably expressed genes from pan-cancer transcriptome analyses were not sufficiently stable under some of the tested conditions. CIAO1, CNOT4, and SNW1 were found to be the most stable reference genes under various conditions. Greater stability was achieved by combining more reference genes. We further used the hypoxia biomarker hypoxia-inducible factor (HIF)-2α to demonstrate that choosing inappropriate reference genes can lead to incorrect qRT-PCR results. We also found that the stable reference genes were irrelevant to malignancy, which may explain their stability under various conditions that cancer cells often encounter. This study provides a list of validated and stable qRT-PCR reference genes and reference gene combinations for lung cancer that may standardize qRT-PCR experiments in future lung cancer studies.

Hypoxia-mediated promotion of glucose metabolism in non-small cell lung cancer correlates with activation of the EZH2/FBXL7/PFKFB4 axis

F-box/LRR-repeat protein 7 (FBXL7) was predicted as a differentially expressed E3 ubiquitin ligase in non-small cell lung cancer (NSCLC), which has been suggested to influence cancer growth and metastasis. In this study, we aimed to decipher the function of FBXL7 in NSCLC and delineate the upstream and downstream mechanisms. FBXL7 expression was verified in NSCLC cell lines and GEPIA-based tissue samples, after which the upstream transcription factor of FBXL7 was bioinformatically identified. The substrate PFKFB4 of the FBXL7 was screened out by tandem affinity purification coupled with mass-spectrometry (TAP/MS). FBXL7 was downregulated in NSCLC cell lines and tissue samples. FBXL7 ubiquitinated and degraded PFKFB4, thus suppressing glucose metabolism and malignant phenotypes of NSCLC cells. Hypoxia-induced HIF-1α upregulation elevated EZH2 and inhibited FBXL7 transcription and reduced its expression, thus promoting PFKFB4 protein stability. By this mechanism, glucose metabolism and the malignant phenotype were enhanced. In addition, knockdown of EZH2 impeded tumor growth through the FBXL7/PFKFB4 axis. In conclusion, our work reveals that the EZH2/FBXL7/PFKFB4 axis plays a regulatory role in glucose metabolism and tumor growth of NSCLC, which is expected to be potential biomarkers for NSCLC.

Immunotherapeutic targets in non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is one of the most common types of cancer in the world and has a 5-year survival rate of ~20%. Immunotherapies have shown promising results leading to durable responses, however, they are only effective for a subset of patients. To determine the best therapeutic approach, a thorough and in-depth profiling of the tumour microenvironment (TME) is required. The TME is a complex network of cell types that form an interconnected network, promoting tumour cell initiation, growth and dissemination. The stroma, immune cells and endothelial cells that comprise the TME generate a plethora of cytotoxic or cytoprotective signalling pathways. In this review, we discuss immunotherapeutic targets in NSCLC tumours and how the TME may influence patients' response to immunotherapy.

Experimental Models to Study End-Organ Morbidity in Sleep Apnea: Lessons Learned and Future Directions

Sleep apnea (SA) is a very prevalent sleep breathing disorder mainly characterized by intermittent hypoxemia and sleep fragmentation, with ensuing systemic inflammation, oxidative stress, and immune deregulation. These perturbations promote the risk of end-organ morbidity, such that SA patients are at increased risk of cardiovascular, neurocognitive, metabolic and malignant disorders. Investigating the potential mechanisms underlying SA-induced end-organ dysfunction requires the use of comprehensive experimental models at the cell, animal and human levels. This review is primarily focused on the experimental models employed to date in the study of the consequences of SA and tackles 3 different approaches. First, cell culture systems whereby controlled patterns of intermittent hypoxia cycling fast enough to mimic the rates of episodic hypoxemia experienced by patients with SA. Second, animal models consisting of implementing realistic upper airway obstruction patterns, intermittent hypoxia, or sleep fragmentation such as to reproduce the noxious events characterizing SA. Finally, human SA models, which consist either in subjecting healthy volunteers to intermittent hypoxia or sleep fragmentation, or alternatively applying oxygen supplementation or temporary nasal pressure therapy withdrawal to SA patients. The advantages, limitations, and potential improvements of these models along with some of their pertinent findings are reviewed.

Quantitative Phase Imaging Detecting the Hypoxia-Induced Patterns in Healthy and Neoplastic Human Colonic Epithelial Cells

Hypoxia is a frequent phenomenon during carcinogenesis and may lead to functional and structural changes in proliferating cancer cells. Colorectal cancer (CRC) is one of the most common neoplasms in which hypoxia is associated with progression. The aim of this study was to assess the optical parameters and microanatomy of CRC and the normal intestinal epithelium cells using the digital holotomography (DHT) method. The examination was conducted on cancer (HT-29, LoVo) and normal colonic cells (CCD-18Co) cultured in normoxic and hypoxic environments. The assessment included optical parameters such as the refractive index (RI) and dry mass as well as the morphological features. Hypoxia decreased the RI in all cells as well as in their cytoplasm, nucleus, and nucleoli. The opposite tendency was noted for spheroid-vesicular structures, where the RI was higher for the hypoxic state. The total volume of hypoxic CCD-18Co and LoVo cells was decreased, while an increase in this parameter was observed for HT-29 cells. Hypoxia increased the radius and cell volume, including the dry mass of the vesicular content. The changes in the optics and morphology of hypoxic cells may suggest the possibility of using DHT in the detection of circulating tumor cells (CTCs).

Emergence of infectious diseases and role of advanced nanomaterials in point-of-care diagnostics: a review

Infectious outbreaks are the foremost global public health concern, challenging the current healthcare system, which claims millions of lives annually. The most crucial way to control an infectious outbreak is by early detection through point-of-care (POC) diagnostics. POC diagnostics are highly advantageous owing to the prompt diagnosis, which is economical, simple and highly efficient with remote access capabilities. In particular, utilization of nanomaterials to architect POC devices has enabled highly integrated and portable (compact) devices with enhanced efficiency. As such, this review will detail the factors influencing the emergence of infectious diseases and methods for fast and accurate detection, thus elucidating the underlying factors of these infections. Furthermore, it comprehensively highlights the importance of different nanomaterials in POCs to detect nucleic acid, whole pathogens, proteins and antibody detection systems. Finally, we summarize findings reported on nanomaterials based on advanced POCs such as lab-on-chip, lab-on-disc-devices, point-of-action and hospital-on-chip. To this end, we discuss the challenges, potential solutions, prospects of integrating internet-of-things, artificial intelligence, 5G communications and data clouding to achieve intelligent POCs.

Design, synthesis and biological evaluation of novel tumor hypoxia-activated EGFR tyrosine kinase inhibitors

Hypoxia is widespread in solid tumors, such as NSCLC, and has become a very attractive target. On the basis of AZD9291 scaffold, novel hypoxia-targeted EGFR inhibitors without the acrylamide warhead but containing hypoxic reductive activation groups were described. Among them, compound JT21 exhibited impressive inhibitory activity (IC₅₀ = 23 nM) against EGFR^L858R/T790M and displayed about 21-fold inhibitory activity decrease against EGFR^wt. Under hypoxia, JT21 exhibited more significant proliferation inhibitory activities against H1975 cells (IC₅₀ = 7.39 ± 2.20 nM) and HCC827 cells (IC₅₀ = 5.88 ± 0.85 nM) than that of AZD9291, which was about 5 times more effective than normoxia activities. Meanwhile, the weak inhibition effects on A549 and BEAS-2B cells suggested JT21 might be a selective inhibitor for EGFR mutations with low toxicity. Furthermore, JT21 could induce apoptosis of H1975 cells under hypoxia and showed good bio-reductive property.

Tumor organoids: applications in cancer modeling and potentials in precision medicine

Cancer is a top-ranked life-threatening disease with intratumor heterogeneity. Tumor heterogeneity is associated with metastasis, relapse, and therapy resistance. These factors contribute to treatment failure and an unfavorable prognosis. Personalized tumor models faithfully capturing the tumor heterogeneity of individual patients are urgently needed for precision medicine. Advances in stem cell culture have given rise to powerful organoid technology for the generation of in vitro three-dimensional tissues that have been shown to more accurately recapitulate the structures, specific functions, molecular characteristics, genomic alterations, expression profiles, and tumor microenvironment of primary tumors. Tumoroids in vitro serve as an important component of the pipeline for the discovery of potential therapeutic targets and the identification of novel compounds. In this review, we will summarize recent advances in tumoroid cultures as an excellent tool for accurate cancer modeling. Additionally, vascularization and immune microenvironment modeling based on organoid technology will also be described. Furthermore, we will summarize the great potential of tumor organoids in predicting the therapeutic response, investigating resistance-related mechanisms, optimizing treatment strategies, and exploring potential therapies. In addition, the bottlenecks and challenges of current tumoroids will also be discussed in this review.

A Programmable Multifunctional 3D Cancer Cell Invasion Micro Platform

In the research of cancer cell invasion and metastasis, recreation of physiologically relevant and faithful three-dimensional (3D) tumor models that recapitulate spatial architecture, spatiotemporal control of cell communication and signaling pathways, and integration of extracellular cues remains an open challenge. Here, a programmable multifunctional 3D cancer cell invasion microbuckets-hydrogel (Mb-H) platform is developed by integrating various function-variable microbuckets and extracellular matrix (ECM)-like hydrogels. Based on this Mb-H micro platform, the aggregation of multi-cancer cells is well controlled to form cancer cell spheroids, and the guiding relationship of single-cell migration and collective cell migration during the epithelial-mesenchymal transition (EMT) of cancer cell invasion are demonstrated. By programming and precisely assembling multiple functions in one system, the Mb-H platform with spatial-temporal controlled release of cytokine transforming growth factor beta (TGF-β) and various functionalized Mb-H platforms with intelligent adjustment of cell-matrix interactions are engineered to coordinate the 3D invasive migration of cancer cell spheroids. This programmable and adaptable 3D cancer cell invasion micro platform takes a new step toward mimicking the dynamically changing (localized) tumor microenvironment and exhibits wide potential applications in cancer research, bio-fabrication, cell signaling, and drug screening.

Multicellular tumor spheroids of LNCaP-Luc prostate cancer cells as in vitro screening models for cytotoxic drugs

An increasing number of studies concerning solid cancers, including prostate cancer, are tending to demonstrate the predominant role of the interactions of tumor cells with their microenvironment, and underlining the relevance of therapeutic approaches co-targeting these two components. Artificial in vitro 3D culture models, such as spheroids, are therefore being designed to allow intercellular interactions between tumor cells and the matrix, under hypoxic conditions mimicking a microtumor. This project aims to develop and characterize a multicellular tumor spheroid (MCTS) model of human prostate cancer cells expressing PSMA, for in vitro drug screening. To this end, 1,000 cells/well were seeded in 100 µl of culture medium with 0.5% of methylcellulose in 96-well, non-adherent, V-shaped bottom plates. Bioluminescent imaging of the spheroids enabled the measurement of spheroid growth. From Day 7 of growth, immunofluorescence studies showed cellular proliferation (Ki-67), mainly located in the periphery of the spheroid section, associated with the formation of an apoptotic core (TUNEL). Scanning electron microscopy and fluorescent imaging (Lox-1 probe) showed the presence of an extracellular matrix and the installation of an oxygen gradient leading to the formation of a hypoxic area during growth. This hypoxia was correlated with increased VEGF excretion. Drug sensitivity was assessed on 2D and 3D cultures. The LNCaP-Luc spheroids are more resistant to docetaxel and TH-302, a hypoxia-activated prodrug, compared with cells grown in a monolayer. For docetaxel, this resistance increased with the spheroid growth stage, whereas the activity of TH-302 was potentiated by the hypoxic environment. In conclusion, the development of LNCaP-Luc cell MCTS provides a simple model mimicking a microtumor; it appears to be particularly well-suited to the validation of new therapeutic approaches targeting proliferation and the microenvironment.

Clinical Application Perspectives of Lung Cancers 3D Tumor Microenvironment Models for In Vitro Cultures

Despite the enormous progress and development of modern therapies, lung cancer remains one of the most common causes of death among men and women. The key element in the development of new anti-cancer drugs is proper planning of the preclinical research phase. The most adequate basic research exemplary for cancer study are 3D tumor microenvironment in vitro models, which allow us to avoid the use of animal models and ensure replicable culture condition. However, the question tormenting the scientist is how to choose the best tool for tumor microenvironment research, especially for extremely heterogenous lung cancer cases. In the presented review we are focused to explain the key factors of lung cancer biology, its microenvironment, and clinical gaps related to different therapies. The review summarized the most important strategies for in vitro culture models mimicking the tumor–tumor microenvironmental interaction, as well as all advantages and disadvantages were depicted. This knowledge could facilitate the right decision to designate proper pre-clinical in vitro study, based on available analytical tools and technical capabilities, to obtain more reliable and personalized results for faster introduction them into the future clinical trials.

Innovative Platform for the Advanced Online Monitoring of Three-Dimensional Cells and Tissue Cultures

The use of 3D cell cultures has gained increasing importance in medical and pharmaceutical research. However, the analysis of the culture medium is hardly representative for the culture conditions within a 3D model which hinders the standardization of 3D cultures and translation of results. Therefore, we developed a modular monitoring platform combining a perfusion bioreactor with an integrated minimally invasive sampling system and implemented sensors that enables the online monitoring of culture parameters and medium compounds within 3D cultures. As a proof-of-concept, primary cells as well as cell lines were cultured on a collagen or gelatin methacryloyl (GelMA) hydrogel matrix, while monitoring relevant culture parameters and analytes. Comparing the interstitial fluid of the 3D models versus the corresponding culture medium, we found considerable differences in the concentrations of several analytes. These results clearly demonstrate that analyses of the culture medium only are not relevant for the development of standardized 3D culture processes. The presented bioreactor with an integrated sampling and sensor platform opens new horizons for the development, optimization, and standardization of 3D cultures. Furthermore, this technology holds the potential to reduce animal studies and improve the transferability of pharmaceutical in vitro studies by gaining more relevant results, bridging the gap towards clinical translation.

Characterization of Oxygen Levels in an Uninfected and Infected Human Blood-Cerebrospinal-Fluid-Barrier Model

The host–pathogen interaction during meningitis can be investigated with blood-cerebrospinal-fluid-barrier (BCSFB) cell culture models. They are commonly handled under atmospheric oxygen conditions (19–21% O₂), although the physiological oxygen conditions are significantly lower in cerebrospinal fluid (CSF) (7–8% O₂). We aimed to characterize oxygen levels in a Streptococcus (S.) suis-infected BCSFB model with transmigrating neutrophils. A BCSFB model with human choroid plexus epithelial cells growing on transwell-filters was used. The upper “blood”-compartment was infected and blood-derived neutrophils were added. S. suis and neutrophils transmigrated through the BCSFB into the “CSF”-compartment. Here, oxygen and pH values were determined with the non-invasive SensorDish^® reader. Slight orbital shaking improved the luminescence-based measurement technique for detecting free oxygen. In the non-infected BCSFB model, an oxygen value of 7% O₂ was determined. However, with S. suis and transmigrating neutrophils, the oxygen value significantly decreased to 2% O₂. The pH level decreased slightly in all groups. In conclusion, we characterized oxygen levels in the BCSFB model and demonstrated the oxygen consumption by cells and bacteria. Oxygen values in the non-infected BCSFB model are comparable to in vivo values determined in pigs in the CSF. Infection and transmigrating neutrophils decrease the oxygen value to lower values.

Biomedical Applications of Non-Small Cell Lung Cancer Spheroids

Lung malignancies accounted for 11% of cancers worldwide in 2020 and remained the leading cause of cancer deaths. About 80% of lung cancers belong to non-small cell lung cancer (NSCLC), which is characterized by extremely high clonal and morphological heterogeneity of tumors and development of multidrug resistance. The improvement of current therapeutic strategies includes several directions. First, increasing knowledge in cancer biology results in better understanding of the mechanisms underlying malignant transformation, alterations in signal transduction, and crosstalk between cancer cells and the tumor microenvironment, including immune cells. In turn, it leads to the discovery of important molecular targets in cancer development, which might be affected pharmaceutically. The second direction focuses on the screening of novel drug candidates, synthetic or from natural sources. Finally, "personalization" of a therapeutic strategy enables maximal damage to the tumor of a patient. The personalization of treatment can be based on the drug screening performed using patient-derived tumor xenografts or in vitro patient-derived cell models. 3D multicellular cancer spheroids, generated from cancer cell lines or tumor-isolated cells, seem to be a helpful tool for the improvement of current NSCLC therapies. Spheroids are used as a tumor-mimicking in vitro model for screening of novel drugs, analysis of intercellular interactions, and oncogenic cell signaling. Moreover, several studies with tumor-derived spheroids suggest this model for the choice of "personalized" therapy. Here we aim to give an overview of the different applications of NSCLC spheroids and discuss the potential contribution of the spheroid model to the development of anticancer strategies.

Replacement Strategies for Animal Studies in Inhalation Testing

Animal testing is mandatory in drug testing and is the gold standard for toxicity and efficacy evaluations. This situation is expected to change in the future as the 3Rs principle, which stands for the replacement, reduction, and refinement of the use of animals in science, is reinforced by many countries. On the other hand, technologies for alternatives to animal testing have increased. The need to develop and use alternatives depends on the complexity of the research topic and also on the extent to which the currently used animal models can mimic human physiology and/or exposure. The lung morphology and physiology of commonly used animal species differs from that of human lungs, and the realistic inhalation exposure of animals is challenging. In vitro and in silico methods can assess important aspects of the in vivo effects, namely particle deposition, dissolution, action at, and permeation through, the respiratory barrier, and pharmacokinetics. This review discusses the limitations of animal models and exposure systems and proposes in vitro and in silico techniques that could, when used together, reduce or even replace animal testing in inhalation testing in the future.

Modulatory role of PACAP and VIP on HIFs expression in lung adenocarcinoma

Lung adenocarcinoma is the most frequent form of non-small cell lung cancer. Inside the tumor mass, uncontrolled cell proliferation generates hypoxic areas leading to activation of hypoxia-inducible factors (HIFs) responsible for neovascularization and tumor metastasis. Pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) are two neuropeptides widely distributed in respiratory organs. Previous studies have demonstrated that these peptides interfere with hypoxic pathways in various diseases, including tumors. However, their modulatory role in HIFs expression in lung adenocarcinomas has not yet been evaluated. In the present paper, we detected the expression profile of PACAP, VIP and related receptors in healthy and adenocarcinoma human lung tissue. To characterize peptides' modulatory effects on HIFs expression, we also exposed A549 lung adenocarcinoma cells and human normal bronchial epithelial BEAS-2B cells to microenvironmental hypoxia by treating them with deferoxamine (DFX). The results showed that PACAP and VIP significantly reduced HIF-1α and HIF-2α levels in both cell lines following hypoxic stress. The HIF-3α expression profile was related to cellular phenotype as it was lower in BEAS-2B and higher in A549 cells under low oxygen tension. In lung adenocarcinoma cells, peptide treatment restored HIF-3 α expression to control levels. These results suggest that endogenous PACAP and VIP exert controversial roles in cellular hypoxic microenvironments depending on the pathophysiological conditions of the lung tissue.

SIRT1/PGC-1α/PPAR-γ Correlate With Hypoxia-Induced Chemoresistance in Non-Small Cell Lung Cancer

Resistance is the major cause of treatment failure and disease progression in non-small cell lung cancer (NSCLC). There is evidence that hypoxia is a key microenvironmental stress associated with resistance to cisplatin, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), and immunotherapy in solid NSCLCs. Numerous studies have contributed to delineating the mechanisms underlying drug resistance in NSCLC; nevertheless, the mechanisms involved in the resistance associated with hypoxia-induced molecular metabolic adaptations in the microenvironment of NSCLC remain unclear. Studies have highlighted the importance of posttranslational regulation of molecular mediators in the control of mitochondrial function in response to hypoxia-induced metabolic adaptations. Hypoxia can upregulate the expression of sirtuin 1 (SIRT1) in a hypoxia-inducible factor (HIF)-dependent manner. SIRT1 is a stress-dependent metabolic sensor that can deacetylate some key transcriptional factors in both metabolism dependent and independent metabolic pathways such as HIF-1α, peroxisome proliferator-activated receptor gamma (PPAR-γ), and PPAR-gamma coactivator 1-alpha (PGC-1α) to affect mitochondrial function and biogenesis, which has a role in hypoxia-induced chemoresistance in NSCLC. Moreover, SIRT1 and HIF-1α can regulate both innate and adaptive immune responses through metabolism-dependent and -independent ways. The objective of this review is to delineate a possible SIRT1/PGC-1α/PPAR-γ signaling-related molecular metabolic mechanism underlying hypoxia-induced chemotherapy resistance in the NSCLC microenvironment. Targeting hypoxia-related metabolic adaptation may be an attractive therapeutic strategy for overcoming chemoresistance in NSCLC.