Hypoxia Changes Energy Metabolism and Growth Rate in Non-Small Cell Lung Cancer Cells

Hypoxia studies in non‑small cell lung cancer: Pathogenesis and clinical implications (Review)

Non‑small cell lung cancer (NSCLC) is one of the most prevalent and lethal types of cancers worldwide and its high incidence and mortality rates pose a significant public health challenge. Despite significant advances in targeted therapy and immunotherapy, the overall prognosis of patients with NSCLC remains poor. Hypoxia is a critical driving factor in tumor progression, influencing the biological behavior of tumor cells through complex molecular mechanisms. The present review systematically examined the role of the hypoxic microenvironment in NSCLC, demonstrating its crucial role in promoting tumor cell growth, invasion and metastasis. Additionally, it has been previously reported that the hypoxic microenvironment enhances tumor cell resistance by activating hypoxia‑inducible factor and regulating exosome secretion. The hypoxic microenvironment also enables tumor cells to adapt to low oxygen and nutrient‑deficient conditions by enhancing metabolic reprogramming, such as through upregulating glycolysis. Further studies have shown that the hypoxic microenvironment facilitates immune escape by modulating tumor‑associated immune cells and suppressing the antitumor response of the immune system. Moreover, the hypoxic microenvironment increases tumor resistance to radiotherapy, chemotherapy and other types of targeted therapy through various pathways, significantly reducing the therapeutic efficacy of these treatments. Therefore, it could be suggested that early detection of cellular hypoxia and targeted therapy based on hypoxia may offer new therapeutic approaches for patients with NSCLC. The present review not only deepened the current understanding of the mechanisms of action and role of the hypoxic microenvironment in NSCLC but also provided a solid theoretical basis for the future development of precision treatments for patients with NSCLC.

Influence of lactate in resistance to anti‑PD‑1/PD‑L1 therapy: Mechanisms and clinical applications (Review)

Metabolic reprogramming is a prominent characteristic of tumor cells, evidenced by heightened secretion of lactate, which is linked to tumor progression. Furthermore, the accumulation of lactate in the tumor microenvironment (TME) influences immune cell activity, including the activity of macrophages, dendritic cells and T cells, fostering an immunosuppressive milieu. Anti‑programmed cell death protein 1 (PD‑1)/programmed death‑ligand 1 (PD‑L1) therapy is associated with a prolonged survival time of patients with non‑small cell lung cancer. However, some patients still develop resistance to anti‑PD‑1/PD‑L1 therapy. Lactate is associated with resistance to anti‑PD‑1/PD‑L1 therapy. The present review summarizes what is known about lactate metabolism in tumor cells and how it affects immune cell function. In addition, the present review emphasizes the relationship between lactate secretion and immunotherapy resistance. The present review also explores the potential for targeting lactate within the TME to enhance the efficacy of immunotherapy.

Strategies to Overcome Intrinsic and Acquired Resistance to Chemoradiotherapy in Head and Neck Cancer

Definitive chemoradiotherapy (CRT) is a cornerstone of treatment for locoregionally advanced head and neck cancer (HNC). Research is ongoing on how to improve the tumor response to treatment and limit normal tissue toxicity. A major limitation in that regard is the growing occurrence of intrinsic or acquired treatment resistance in advanced cases. In this review, we will discuss how overexpression of efflux pumps, perturbation of apoptosis-related factors, increased expression of antioxidants, glucose metabolism, metallotheionein expression, increased DNA repair, cancer stem cells, epithelial-mesenchymal transition, non-coding RNA and the tumour microenvironment contribute towards resistance of HNC to chemotherapy and/or radiotherapy. These mechanisms have been investigated for years and been exploited for therapeutic gain in resistant patients, paving the way to the development of new promising drugs. Since in vitro studies on resistance requires a suitable model, we will also summarize published techniques and treatment schedules that have been shown to generate acquired resistance to chemo- and/or radiotherapy that most closely mimics the clinical scenario.

DNA Damage and Inflammatory Response of p53 Null H358 Non-Small Cell Lung Cancer Cells to X-Ray Exposure Under Chronic Hypoxia

Hypoxia-induced radioresistance limits therapeutic success in cancer. In addition, p53 mutations are widespread in tumors including non-small cell lung carcinomas (NSCLCs), and they might modify the radiation response of hypoxic tumor cells. We therefore analyzed the DNA damage and inflammatory response in chronically hypoxic (1% O2, 48 h) p53 null H358 NSCLC cells after X-ray exposure. We used the colony-forming ability assay to determine cell survival, γH2AX immunofluorescence microscopy to quantify DNA double-strand breaks (DSBs), flow cytometry of DAPI-stained cells to measure cell cycle distribution, ELISAs to quantify IL-6 and IL-8 secretion in cell culture supernatants, and RNA sequencing to determine gene expression. Chronic hypoxia increased the colony-forming ability and radioresistance of H358 cells. It did not affect the formation or resolution of X-ray-induced DSBs. It reduced the fraction of cells undergoing G2 arrest after X-ray exposure and delayed the onset of G2 arrest. Hypoxia led to an earlier enhancement in cytokines secretion rate after X-irradiation compared to normoxic controls. Gene expression changes were most pronounced after the combined exposure to hypoxia and X-rays and pertained to senescence and different cell death pathways. In conclusion, hypoxia-induced radioresistance is present despite the absence of functional p53. This resistance is related to differences in clonogenicity, cell cycle regulation, cytokine secretion, and gene expression under chronic hypoxia, but not to differences in DNA DSB repair kinetics.

Differential effects of hypoxia on motility using various in vitro models of lung adenocarcinoma

Lung cancer is the leading cause of cancer-related death globally. Metastasis is the most common reason of mortality in which hypoxia is suggested to have a pivotal role. However, the effect of hypoxia on the metastatic potential and migratory activity of cancer cells is largely unexplored and warrants detailed scientific investigations. Accordingly, we analyzed changes on cell proliferation and migratory activity both in single-cell migration and invasion under normoxic and hypoxic conditions in lung adenocarcinoma cell lines. Alterations in crucial genes and proteins associated with cellular response to hypoxia, epithelial-mesenchymal transition, proliferation and apoptosis were also analyzed. Generally, we observed no change in proliferation upon hypoxic conditions and no detectable induction of apoptosis. Interestingly, we observed that single-cell motility was generally reduced while invasion under confluent conditions using scratch assay was enhanced by hypoxia in most of the cell lines. Furthermore, we detected changes in the expression of EMT markers that are consistent with enhanced motility and metastasis-promoting effect of hypoxia. In summary, our study indicated cell line-, time of exposure- and migrational type-dependent effects of hypoxia in cellular proliferation, motility and gene expression. Our results contribute to better understanding and tackling cancer metastasis.

Hypoxia: Intriguing Feature in Cancer Cell Biology

Hypoxia, a key aspect of the tumor microenvironment, plays a vital role in cell proliferation, angiogenesis, metabolism, and the immune response within tumors. These factors collectively promote tumor advancement, aggressiveness, metastasis and result in a poor prognosis. Hypoxia inducible factor 1α (HIF-1α), activated under low oxygen conditions, mediates many of these effects by altering drug target expression, metabolic regulation, and oxygen consumption. These changes promote cancer cell growth and survival. Hypoxic tumor cells develop aggressive traits and resistance to chemotherapy and radiotherapy, leading to increased mortality. Targeting hypoxic tumor offers a potential solution to overcome the challenges posed by tumor heterogeneity and can be used in designing diagnostic and therapeutic nanocarriers for various solid cancers. This concept provides an overview of the intricate relationship between hypoxia and the tumor microenvironment, highlighting its potential as a promising tool for cancer therapies. The article explores the development of hypoxia in cancer cells and its role in cancer progression, along with the latest advancements in hypoxia-triggered cancer treatment.

Pathophysiological Implications of Protein Lactylation in Pancreatic Epithelial Tumors

Protein lactylation is a post-translational modification associated with glycolysis. Although recent evidence indicates that protein lactylation is involved in epigenetic gene regulation, its pathophysiological significance remains unclear, particularly in neoplasms. Herein, we investigated the potential involvement of protein lactylation in the molecular mechanisms underlying benign and malignant pancreatic epithelial tumors, as well as its role in the response of pancreatic cancer (PC) cells to gemcitabine. Increased lactylation was observed in the nuclei of intraductal papillary mucinous adenoma, non-invasive intraductal papillary mucinous carcinoma, and invasive carcinoma, in parallel to the upregulation of hypoxia-inducible factor-1α. This observation indicated that a hypoxia-associated increase in nuclear protein lactylation could be a biochemical hallmark in pancreatic epithelial tumors. The standard PC chemotherapy drug gemcitabine suppressed histone lactylation in vitro, suggesting that histone lactylation might be relevant to its mechanism of action. Taken together, our findings suggest that protein lactylation may be involved in the development of pancreatic epithelial tumors and could represent a potential therapeutic target for PC.

Tumor-associated macrophages in non-small-cell lung cancer: From treatment resistance mechanisms to therapeutic targets

Non-small cell lung cancer (NSCLC) remains one of the leading causes of cancer-related deaths worldwide. Different treatment approaches are typically employed based on the stage of NSCLC. Common clinical treatment methods include surgical resection, drug therapy, and radiation therapy. However, with the introduction and utilization of immune checkpoint inhibitors, cancer treatment has entered a new era, completely revolutionizing the treatment landscape for various cancers and significantly improving overall patient survival. Concurrently, treatment resistance often poses a critical challenge, with many patients experiencing disease progression following an initial response due to treatment resistance. Increasing evidence suggests that the tumor microenvironment (TME) plays a pivotal role in treatment resistance. Tumor-associated macrophages (TAMs) within the TME can promote treatment resistance in NSCLC by secreting various cytokines activating signaling pathways, and interacting with other immune cells. Therefore, this article will focus on elucidating the key mechanisms of TAMs in treatment resistance and analyze how targeting TAMs can reduce the levels of treatment resistance in NSCLC, providing a comprehensive understanding of the principles and approaches to overcome treatment resistance in NSCLC.

Hypoxia Modulates Radiosensitivity and Response to Different Radiation Qualities in A549 Non-Small Cell Lung Cancer (NSCLC) Cells

Hypoxia-induced radioresistance reduces the efficacy of radiotherapy for solid malignancies, including non-small cell lung cancer (NSCLC). Cellular hypoxia can confer radioresistance through cellular and tumor micro-environment adaptations. Until recently, studies evaluating radioresistance secondary to hypoxia were designed to maintain cellular hypoxia only before and during irradiation, while any handling of post-irradiated cells was carried out in standard oxic conditions due to the unavailability of hypoxia workstations. This limited the possibility of simulating in vivo or clinical conditions in vitro. The presence of molecular oxygen is more important for the radiotoxicity of low-linear energy transfer (LET) radiation (e.g., X-rays) than that of high-LET carbon (12C) ions. The mechanisms responsible for 12C ions' potential to overcome hypoxia-induced radioresistance are currently not fully understood. Therefore, the radioresistance of hypoxic A549 NSCLC cells following exposure to X-rays or 12C ions was investigated along with cell cycle progression and gene expression by maintaining hypoxia before, during and after irradiation. A549 cells were incubated under normoxia (20% O2) or hypoxia (1% O2) for 48 h and then irradiated with X-rays (200 kV) or 12C ions (35 MeV/n, LET ~75 keV/µm). Cell survival was evaluated using colony-forming ability (CFA) assays immediately or 24 h after irradiation (late plating). DNA double-strand breaks (DSBs) were analyzed using γH2AX immunofluorescence microscopy. Cell cycle progression was determined by flow cytometry of 4',6-diamidino-2-phenylindole-stained cells. The global transcription profile post-irradiation was evaluated by RNA sequencing. When hypoxia was maintained before, during and after irradiation, hypoxia-induced radioresistance was observed only in late plating CFA experiments. The killing efficiency of 12C ions was much higher than that of X-rays. Cell survival under hypoxia was affected more strongly by the timepoint of plating in the case of X-rays compared to 12C ions. Cell cycle arrest following irradiation under hypoxia was less pronounced but more prolonged. DSB induction and resolution following irradiation were not significantly different under normoxia and hypoxia. Gene expression response to irradiation primarily comprised cell cycle regulation for both radiation qualities and oxygen conditions. Several PI3K target genes involved in cell migration and cell motility were differentially upregulated in hypoxic cells. Hypoxia-induced radioresistance may be linked to altered cell cycle response to irradiation and PI3K-mediated changes in cell motility and migration in A549 cells rather than less DNA damage or faster repair.

USP7 promotes non-small-cell lung cancer cell glycolysis and survival by stabilizing and activating c-Abl

BACKGROUND

Abelson tyrosine kinase (c-Abl) is frequently mutated and highly expressed, and promotes non-small-cell lung cancer (NSCLC) survival, metastasis and tumorigenesis. c-Abl could also be modified through ubiquitination, but the underlying mechanism is not well understood.

METHODS

Mass spectrometry assays were performed to search c-Abl deubiquitination enzymes. The molecular mechanism was determined using Co-IP assays, pull-down assays, Western blotting upon gene knockdown or overexpression. Cell lines and animal models were used to investigate the role of c-Abl and USP7 in NSCLC. EdU staining assay and Transwell assay were performed to evaluate the proliferation and migration ability of NSCLC cells, respectively.

RESULTS

Ubiquitin-specific protease 7 (USP7) is found to upregulate c-Abl via the deubiquitinase screen. USP7 interacts with c-Abl and decreases its K48-linked polyubiquitination, thereby increasing the stability of c-Abl. In addition to the wild-type one, c-Abl mutants can also be deubiquitinated and stabilized by USP7. Moreover, USP7 promotes c-Abl accumulation in cytoplasm by increasing its binding to 14-3-3α/β and activates the oncogenic c-Abl signalling pathway. Furthermore, the USP7/c-Abl axis promotes NSCLC cell glycolysis by direct phosphorylating and stabilizing hexokinase-2 (HK2). Knockdown of USP7 or c-Abl suppresses NSCLC cell glycolysis and reduces lactate production. Further studies revealed that overexpression of USP7 facilitates NSCLC cell growth and metastasis as well as xenograft growth in nude mice, while these activities are suppressed with USP7 or c-Abl being knocked down.

CONCLUSIONS

USP7 is a deubiquitinase of c-Abl and upregulates its oncogenic activity. USP7 promotes NSCLC cell metabolism by activating c-Abl and HK2. Targeting the USP7/c-Abl/HK2 axis might be a potential strategy to the precision therapy of NSCLC.

In vitro anti-cancer activity of a polyherbal preparation, VEDICINALS®9, against A549 human lung adenocarcinoma cells

PURPOSE

Non-small cell lung cancer (NSCLC) is among the leading causes of morbidity and mortality worldwide. Despite the availability of several treatment options, the five-year survival rate of NSCLC is extremely low (<20%). This underlines the necessity of more effective therapeutic alternatives. In this context, plant-derived extracts and bioactive molecules extracted from plants, known collectively as phytoceuticals, represent an extremely variegated source of bioactive compounds with potent anticancer potential. In the present study, we tested the in vitro anticancer activity of a polyherbal preparation, VEDICINALS®9, containing nine different bioactive principles extracted by medicinal plants.

METHODS

The anticancer activity of VEDICINALS®9 was investigated by measuring its impact on A549 human NSCLC cell proliferation (MTT assay and trypan blue staining), migration (wound healing assay and transwell chamber assay) and by measuring the impact on the expression of cancer-related proteins (Human XL Oncology Protein Array).

RESULTS

We show that VEDICINALS®9 at a concentration of 0.2% v/v has potent anticancer effect, significantly inhibiting A549 cell proliferation and migration. Mechanistically, this was achieved by downregulating the expression of proteins involved in cancer cell proliferation (Axl, FGF basic, enolase 2, progranulin, survivin) and migration (Dkk-1, cathepsins B and D, BCL-x, amphiregulin, CapG, u-plasminogen activator). Furthermore, treatment with VEDICINALS®9 resulted in increased expression of the oncosuppressor protein p53 and of the angiogenesis inhibitor endostatin.

CONCLUSIONS

Taken together, our results provide proof of principle of the potent anticancer activity of the polyherbal preparation VEDICINALS®9, highlighting its enormous potential as an alternative or adjuvant therapy for lung cancer.

Differential Inhibition of Anaplerotic Pyruvate Carboxylation and Glutaminolysis-Fueled Anabolism Underlies Distinct Toxicity of Selenium Agents in Human Lung Cancer

Past chemopreventive human trials on dietary selenium supplements produced controversial outcomes. They largely employed selenomethionine (SeM)-based diets. SeM was less toxic than selenite or methylseleninic acid (MSeA) to lung cancer cells. We thus investigated the toxic action of these Se agents in two non-small cell lung cancer (NSCLC) cell lines and ex vivo organotypic cultures (OTC) of NSCLC patient lung tissues. Stable isotope-resolved metabolomics (SIRM) using 13C6-glucose and 13C5,15N2-glutamine tracers with gene knockdowns were employed to examine metabolic dysregulations associated with cell type- and treatment-dependent phenotypic changes. Inhibition of key anaplerotic processes, pyruvate carboxylation (PyC) and glutaminolysis were elicited by exposure to MSeA and selenite but not by SeM. They were accompanied by distinct anabolic dysregulation and reflected cell type-dependent changes in proliferation/death/cell cycle arrest. NSCLC OTC showed similar responses of PyC and/or glutaminolysis to the three agents, which correlated with tissue damages. Altogether, we found differential perturbations in anaplerosis-fueled anabolic pathways to underlie the distinct anti-cancer actions of the three Se agents, which could also explain the failure of SeM-based chemoprevention trials.