Oxidative stress, tumor microenvironment, and metabolic reprogramming: a diabolic liaison. Int J Cell Biol. 2012;2012:762825. [PMID: 22666258 PMCID: PMC3361160 DOI: 10.1155/2012/762825]

Exploring the role of the immune microenvironment in hepatocellular carcinoma: Implications for immunotherapy and drug resistance

Hepatocellular carcinoma (HCC), the most common type of liver tumor, is a leading cause of cancer-related deaths, and the incidence of liver cancer is still increasing worldwide. Curative hepatectomy or liver transplantation is only indicated for a small population of patients with early-stage HCC. However, most patients with HCC are not candidates for radical resection due to disease progression, leading to the choice of the conventional tyrosine kinase inhibitor drug sorafenib as first-line treatment. In the past few years, immunotherapy, mainly immune checkpoint inhibitors (ICIs), has revolutionized the clinical strategy for HCC. Combination therapy with ICIs has proven more effective than sorafenib, and clinical trials have been conducted to apply these therapies to patients. Despite significant progress in immunotherapy, the molecular mechanisms behind it remain unclear, and immune resistance is often challenging to overcome. Several studies have pointed out that the complex intercellular communication network in the immune microenvironment of HCC regulates tumor escape and drug resistance to immune response. This underscores the urgent need to analyze the immune microenvironment of HCC. This review describes the immunosuppressive cell populations in the immune microenvironment of HCC, as well as the related clinical trials, aiming to provide insights for the next generation of precision immunotherapy.

A critical appraisal of the role of metabolomics in breast cancer research and diagnostics

Breast cancer (BC) remains the most prevalent cancer among women worldwide, despite significant advancements in its prevention and treatment. The escalating incidence of BC globally necessitates continued research into novel diagnostic and therapeutic strategies. Metabolomics, a burgeoning field, offers a comprehensive analysis of all metabolites within a cell, tissue, system, or organism, providing crucial insights into the dynamic changes occurring during cancer development and progression. This review focuses on the metabolic alterations associated with BC, highlighting the potential of metabolomics in identifying biomarkers for early detection, diagnosis, treatment and prognosis. Metabolomics studies have revealed distinct metabolic signatures in BC, including alterations in lipid metabolism, amino acid metabolism, and energy metabolism. These metabolic changes not only support the rapid proliferation of cancer cells but also influence the tumour microenvironment and therapeutic response. Furthermore, metabolomics holds great promise in personalized medicine, facilitating the development of tailored treatment strategies based on an individual's metabolic profile. By providing a holistic view of the metabolic changes in BC, metabolomics has the potential to revolutionize our understanding of the disease and improve patient outcomes.

Nanomaterials-Induced Redox Imbalance: Challenged and Opportunities for Nanomaterials in Cancer Therapy

Cancer cells typically display redox imbalance compared with normal cells due to increased metabolic rate, accumulated mitochondrial dysfunction, elevated cell signaling, and accelerated peroxisomal activities. This redox imbalance may regulate gene expression, alter protein stability, and modulate existing cellular programs, resulting in inefficient treatment modalities. Therapeutic strategies targeting intra- or extracellular redox states of cancer cells at varying state of progression may trigger programmed cell death if exceeded a certain threshold, enabling therapeutic selectivity and overcoming cancer resistance to radiotherapy and chemotherapy. Nanotechnology provides new opportunities for modulating redox state in cancer cells due to their excellent designability and high reactivity. Various nanomaterials are widely researched to enhance highly reactive substances (free radicals) production, disrupt the endogenous antioxidant defense systems, or both. Here, the physiological features of redox imbalance in cancer cells are described and the challenges in modulating redox state in cancer cells are illustrated. Then, nanomaterials that regulate redox imbalance are classified and elaborated upon based on their ability to target redox regulations. Finally, the future perspectives in this field are proposed. It is hoped this review provides guidance for the design of nanomaterials-based approaches involving modulating intra- or extracellular redox states for cancer therapy, especially for cancers resistant to radiotherapy or chemotherapy, etc.

Myeloid-derived suppressor cells in cancer and cancer therapy

Anticancer agents continue to dominate the list of newly approved drugs, approximately half of which are immunotherapies. This trend illustrates the considerable promise of cancer treatments that modulate the immune system. However, the immune system is complex and dynamic, and can have both tumour-suppressive and tumour-promoting effects. Understanding the full range of immune modulation in cancer is crucial to identifying more effective treatment strategies. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of myeloid cells that develop in association with chronic inflammation, which is a hallmark of cancer. Indeed, MDSCs accumulate in the tumour microenvironment, where they strongly inhibit anticancer functions of T cells and natural killer cells and exert a variety of other tumour-promoting effects. Emerging evidence indicates that MDSCs also contribute to resistance to cancer treatments, particularly immunotherapies. Conversely, treatment approaches designed to eliminate cancer cells can have important additional effects on MDSC function, which can be either positive or negative. In this Review, we discuss the interplay between MDSCs and various other cell types found in tumours as well as the mechanisms by which MDSCs promote tumour progression. We also discuss the relevance and implications of MDSCs for cancer therapy.

Implications and progression of peroxiredoxin 2 (PRDX2) in various human diseases

Peroxiredoxin 2 (PRDX2), a characteristic 2-Cys enzyme is one of the foremost effective scavenger proteins against reactive oxygen species (ROS) and hydrogen peroxide (H2O2) defending cells against oxidative stress. Dysregulation of this antioxidant raises the quantity of ROS and oxidative stress implicated in several diseases. PRDX2 lowers the generation of ROS that takes part in controlling several signalling pathways occurring in neurons, protecting them from stress caused by oxidation and an inflammatory harm. Depending on the aetiological variables, the kind of cancer, and the stage of tumour development, PRDX2 may behave either as an onco-suppressor or a promoter. However, overexpression of PRDX2 may be linked to the development of numerous cancers, including those of the colon, cervix, breast, and prostate. PRDX2 also plays a beneficial effect in inflammatory diseases. PRDX2 being a thiol-specific peroxidase, is known to control proinflammatory reactions. The spilling of PRDX2, on the other hand, accelerates cognitive impairment following a stroke by triggering an inflammatory reflex. PRDX2 expression patterns in vascular cells tend to be crucial to its involvement in cardiovascular diseases. In vascular smooth muscle cells, if the protein tyrosine phosphatase is restricted, PRDX2 could avoid the neointimal thickening which relies on platelet derived growth factor (PDGF), a vital component of vascular remodelling. A proper PRDX2 balance is therefore crucial. The imbalance causes a number of illnesses, including cancers, inflammatory diseases, cardiovascular ailments, and neurological and neurodegenerative problems which are discussed in this review.

Oxidative versus Reductive Stress in Breast Cancer Development and Cellular Mechanism of Alleviation: A Current Perspective with Anti-breast Cancer Drug Resistance

Redox homeostasis is essential for keeping our bodies healthy, but it also helps breast cancer cells grow, stay alive, and resist treatment. Changes in the redox balance and problems with redox signaling can make breast cancer cells grow and spread and make them resistant to chemotherapy and radiation therapy. Reactive oxygen species/reactive nitrogen species (ROS/RNS) generation and the oxidant defense system are out of equilibrium, which causes oxidative stress. Many studies have shown that oxidative stress can affect the start and spread of cancer by interfering with redox (reduction-oxidation) signaling and damaging molecules. The oxidation of invariant cysteine residues in FNIP1 is reversed by reductive stress, which is brought on by protracted antioxidant signaling or mitochondrial inactivity. This permits CUL2FEM1B to recognize its intended target. After the proteasome breaks down FNIP1, mitochondrial function is restored to keep redox balance and cell integrity. Reductive stress is caused by unchecked amplification of antioxidant signaling, and changes in metabolic pathways are a big part of breast tumors' growth. Also, redox reactions make pathways like PI3K, PKC, and protein kinases of the MAPK cascade work better. Kinases and phosphatases control the phosphorylation status of transcription factors like APE1/Ref-1, HIF-1, AP-1, Nrf2, NF-B, p53, FOXO, STAT, and - catenin. Also, how well anti-breast cancer drugs, especially those that cause cytotoxicity by making ROS, treat patients depends on how well the elements that support a cell's redox environment work together. Even though chemotherapy aims to kill cancer cells, which it does by making ROS, this can lead to drug resistance in the long run. The development of novel therapeutic approaches for treating breast cancer will be facilitated by a better understanding of the reductive stress and metabolic pathways in tumor microenvironments.

Formoterol Exerts Anti-Cancer Effects Modulating Oxidative Stress and Epithelial-Mesenchymal Transition Processes in Cigarette Smoke Extract Exposed Lung Adenocarcinoma Cells

Lung cancer frequently affects patients with Chronic Obstructive Pulmonary Disease (COPD). Cigarette smoke (CS) fosters cancer progression by increasing oxidative stress and by modulating epithelial-mesenchymal transition (EMT) processes in cancer cells. Formoterol (FO), a long-acting β2-agonist widely used for the treatment of COPD, exerts antioxidant activities. This study explored in a lung adenocarcinoma cell line (A549) whether FO counteracted the effects of cigarette smoke extract (CSE) relative to oxidative stress, inflammation, EMT processes, and cell migration and proliferation. A549 was stimulated with CSE and FO, ROS were evaluated by flow-cytometry and by nanostructured electrochemical sensor, EMT markers were evaluated by flow-cytometry and Real-Time PCR, IL-8 was evaluated by ELISA, cell migration was assessed by scratch and phalloidin test, and cell proliferation was assessed by clonogenic assay. CSE significantly increased the production of ROS, IL-8 release, cell migration and proliferation, and SNAIL1 expression but significantly decreased E-cadherin expression. FO reverted all these phenomena in CSE-stimulated A549 cells. The present study provides intriguing evidence that FO may exert anti-cancer effects by reverting oxidative stress, inflammation, and EMT markers induced by CS. These findings must be validated in future clinical studies to support FO as a valuable add-on treatment for lung cancer management.

Role of stress granules in tumorigenesis and cancer therapy

Stress granules (SGs) are membrane-less organelles that cell forms via liquid-liquid phase separation (LLPS) under stress conditions such as oxidative stress, ER stress, heat shock and hypoxia. SG assembly is a stress-responsive mechanism by regulating gene expression and cellular signaling pathways. Cancer cells face various stress conditions in tumor microenvironment during tumorigenesis, while SGs contribute to hallmarks of cancer including proliferation, invasion, migration, avoiding apoptosis, metabolism reprogramming and immune evasion. Here, we review the connection between SGs and cancer development, the limitation of SGs on current cancer therapy and promising cancer therapeutic strategies targeting SGs in the future.

Reprogramming of breast tumor-associated macrophages with modulation of arginine metabolism

HER2+ breast tumors have abundant immune-suppressive cells, including M2-type tumor associated macrophages (TAMs). While TAMs consist of the immune-stimulatory M1-type and immune-suppressive M2-type, M1/M2-TAM ratio is reduced in immune-suppressive tumors, contributing to their immunotherapy refractoriness. M1 vs. M2-TAM formation depends on differential arginine metabolism, where M1-TAMs convert arginine to nitric oxide (NO) and M2-TAMs convert arginine to polyamines (PAs). We hypothesize that such distinct arginine metabolism in M1- vs M2-TAMs is attributed to different availability of BH4 (NO synthase cofactor) and that its replenishment would reprogram M2-TAMs to M1-TAMs. Recently, we reported that sepiapterin (SEP), the endogenous BH4 precursor, elevates the expression of M1-TAM markers within HER2+ tumors. Here, we show that SEP restores BH4 levels in M2-TAMs, which then redirects arginine metabolism to NO synthesis and converts M2-TAMs to M1-TAMs. The reprogrammed TAMs exhibit full-fledged capabilities of antigen presentation and induction of effector T cells to trigger immunogenic cell death of HER2+ cancer cells. This study substantiates the utility of SEP in metabolic shift of HER2+ breast tumor microenvironment as a novel immunotherapeutic strategy.

[Diabetes mellitus and the female reproductive system tumors]

The article discusses various pathophysiological conditions and processes that lead to the development of tumors in diabetes mellitus. These include obesity, hyperglycemia, hyperinsulinemia, inflammation, and oxidative stress. The data of epidemiological studies are given, in which it was found that diabetes mellitus (both type 1 and type 2) increases the risk of developing the female reproductive system tumors, such as ovarian cancer, endometrial cancer, while for cervical cancer, vaginal cancer and vulvar cancer, such a relationship has not been clearly identified.

Nutritional Metabolomics in Diet-Breast Cancer Relations: Current Research, Challenges, and Future Directions-A Review

Breast cancer is one of the most common types of cancer in women worldwide, and its incidence is increasing. Diet has been identified as a modifiable risk factor for breast cancer, but the complex interplay between diet, metabolism, and cancer development is not fully understood. Nutritional metabolomics is a rapidly evolving field that can provide insights into the metabolic changes associated with dietary factors and their impact on breast cancer risk. The review's objective is to provide a comprehensive overview of the current research on the application of nutritional metabolomics in understanding the relationship between diet and breast cancer. The search strategy involved querying several electronic databases, including PubMed, Scopus, Web of Science, and Google Scholar. The search terms included combinations of relevant keywords such as "nutritional metabolomics", "diet", "breast cancer", "metabolites", and "biomarkers". In this review, both in vivo and in vitro studies were included, and we summarize the current state of knowledge on the role of nutritional metabolomics in understanding the diet-breast cancer relationship, including identifying specific metabolites and metabolic pathways associated with breast cancer risk. We also discuss the challenges associated with nutritional metabolomics research, including standardization of analytical methods, interpretation of complex data, and integration of multiple-omics approaches. Finally, we highlight future directions for nutritional metabolomics research in studying diet-breast cancer relations, including investigating the role of gut microbiota and integrating multiple-omics approaches. The application of nutritional metabolomics in the study of diet-breast cancer relations, including 2-amino-4-cyano butanoic acid, piperine, caprate, rosten-3β,17β-diol-monosulfate, and γ-carboxyethyl hydrochroman, among others, holds great promise for advancing our understanding of the role of diet in breast cancer development and identifying personalized dietary recommendations for breast cancer prevention, control, and treatment.

Association between the antioxidant properties of SESN proteins and anti-cancer therapies

Since the beginning of SESN protein development, they have attracted highly progressive attention due to their regulatory role in multiple signalling pathways. Through their antioxidant activity and autophagy regulation implication, they can function as powerful antioxidants to reduce oxidative stress in cells. SESN proteins received special attention in the field of regulation of reactive oxygen species level in the cell and its interplay with signalling pathways determining energy and nutrient homeostasis. Since perturbations in these pathways are implicated in cancer onset and development, SESNs might constitute potential novel therapeutic targets of broad interest. In this review, we discuss the impact of SESN proteins on anti-cancer therapy based on naturally occurring compounds and conventionally used drugs that influence oxidative stress and autophagy-induced cellular signalling pathways. The significant changes in reactive oxygen species level and nutrient status in cancer cells generate subsequent biological effect through the regulation of SESN-dependent pathways. Thus, SESN may serve as the key molecule for regulating anti-cancer drugs' induced cellular response.

Metabolic codependencies in the tumor microenvironment and gastric cancer: Difficulties and opportunities

Oncogenesis and the development of tumors affect metabolism throughout the body. Metabolic reprogramming (also known as metabolic remodeling) is a feature of malignant tumors that is driven by oncogenic changes in the cancer cells themselves as well as by cytokines in the tumor microenvironment. These include endothelial cells, matrix fibroblasts, immune cells, and malignant tumor cells. The heterogeneity of mutant clones is affected by the actions of other cells in the tumor and by metabolites and cytokines in the microenvironment. Metabolism can also influence immune cell phenotype and function. Metabolic reprogramming of cancer cells is the result of a convergence of both internal and external signals. The basal metabolic state is maintained by internal signaling, while external signaling fine-tunes the metabolic process based on metabolite availability and cellular needs. This paper reviews the metabolic characteristics of gastric cancer, focusing on the intrinsic and extrinsic mechanisms that drive cancer metabolism in the tumor microenvironment, and interactions between tumor cell metabolic changes and microenvironment metabolic changes. This information will be helpful for the individualized metabolic treatment of gastric cancers.

Rice Bran: From Waste to Nutritious Food Ingredients

Rice (Oryza sativa L.) is a principal food for more than half of the world's people. Rice is predominantly consumed as white rice, a refined grain that is produced during the rice milling process which removes the bran and germ and leaves the starchy endosperm. Rice bran is a by-product produced from the rice milling process, which contains many bioactive compounds, for instance, phenolic compounds, tocotrienols, tocopherols, and γ-oryzanol. These bioactive compounds are thought to protect against cancer, vascular disease, and type 2 diabetes. Extraction of rice bran oil also generates various by-products including rice bran wax, defatted rice bran, filtered cake, and rice acid oil, and some of them exert bioactive substances that could be utilized as functional food ingredients. However, rice bran is often utilized as animal feed or discarded as waste. Therefore, this review aimed to discuss the role of rice bran in metabolic ailments. The bioactive constituents and food product application of rice bran were also highlighted in this study. Collectively, a better understanding of the underlying molecular mechanism and the role of these bioactive compounds exerted in the rice bran would provide a useful approach for the food industry and prevent metabolic ailments.

Amino acid metabolic reprogramming in tumor metastatic colonization

Metastasis is considered as the major cause of cancer death. Cancer cells can be released from primary tumors into the circulation and then colonize in distant organs. How cancer cells acquire the ability to colonize in distant organs has always been the focus of tumor biology. To enable survival and growth in the new environment, metastases commonly reprogram their metabolic states and therefore display different metabolic properties and preferences compared with the primary lesions. For different microenvironments in various colonization sites, cancer cells must transfer to specific metabolic states to colonize in different distant organs, which provides the possibility of evaluating metastasis tendency by tumor metabolic states. Amino acids provide crucial precursors for many biosynthesis and play an essential role in cancer metastasis. Evidence has proved the hyperactivation of several amino acid biosynthetic pathways in metastatic cancer cells, including glutamine, serine, glycine, branched chain amino acids (BCAAs), proline, and asparagine metabolism. The reprogramming of amino acid metabolism can orchestrate energy supply, redox homeostasis, and other metabolism-associated pathways during cancer metastasis. Here, we review the role and function of amino acid metabolic reprogramming in cancer cells colonizing in common metastatic organs, including lung, liver, brain, peritoneum, and bone. In addition, we summarize the current biomarker identification and drug development of cancer metastasis under the amino acid metabolism reprogramming, and discuss the possibility and prospect of targeting organ-specific metastasis for cancer treatment.

Stress Granules in Cancer

The capacity of cells to organize complex biochemical reactions in intracellular space is a fundamental organizational principle of life. Key to this organization is the compartmentalization of the cytoplasm into distinct organelles, which is frequently achieved through intracellular membranes. Recent evidence, however, has added a new layer of flexibility to cellular compartmentalization. As such, in response to specific stimuli, liquid-liquid phase separations can lead to the rapid rearrangements of the cytoplasm to form membraneless organelles. Stress granules (SGs) are one such type of organelle that form specifically when cells are faced with stress stimuli, to aid cells in coping with stress. Inherently, altered SG formation has been linked to the pathogenesis of diseases associated with stress and inflammatory conditions, including cancer. Exciting discoveries have indicated an intimate link between SGs and tumorigenesis. Several pro-tumorigenic signaling molecules including the RAS oncogene, mTOR, and histone deacetylase 6 (HDAC6) have been shown to upregulate SG formation. Based on these studies, SGs have emerged as structures that can integrate oncogenic signaling and tumor-associated stress stimuli to enhance cancer cell fitness. In addition, growing evidence over the past decade suggests that SGs function not only to regulate the switch between survival and cell death, but also contribute to cancer cell proliferation, invasion, metastasis, and drug resistance. Although much remains to be learned about the role of SGs in tumorigenesis, these studies highlight SGs as a key regulatory hub in cancer and a promising therapeutic target.

Advances in the Mechanistic Study of the Control of Oxidative Stress Injury by Modulating HDAC6 Activity

Oxidative stress is defined as an injury resulting from a disturbance in the dynamic equilibrium of the redox environment due to the overproduction of active/radical oxygen exceeding the antioxidative ability of the body. This is a key step in the development of various diseases. Oxidative stress is modulated by different factors and events, including the modification of histones, which are the cores of nucleosomes. Histone modification includes acetylation and deacetylation of certain amino acid residues; this process is catalyzed by different enzymes. Histone deacetylase 6 (HDAC6) is a unique deacetylating protease that also catalyzes the deacetylation of different nonhistone substrates to regulate various physiologic processes. The intimate relationship between HDAC6 and oxidative stress has been demonstrated by different studies. The present paper aims to summarize the data obtained from a mechanistic study of HDAC6 and oxidative stress to guide further investigations on mechanistic characterization and drug development.

Activated PyK2 and Its Associated Molecules Transduce Cellular Signaling from the Cancerous Milieu for Cancer Metastasis

PyK2 is a member of the proline-rich tyrosine kinase and focal adhesion kinase families and is ubiquitously expressed. PyK2 is mainly activated by stimuli, such as activated Src kinases and intracellular acidic pH. The mechanism of PyK2 activation in cancer cells has been addressed extensively. The up-regulation of PyK2 through overexpression and enhanced phosphorylation is a key feature of tumorigenesis and cancer migration. In this review, we summarized the cancer milieu, including acidification and cancer-associated molecules, such as chemical reagents, interactive proteins, chemokine-related molecules, calcium channels/transporters, and oxidative molecules that affect the fate of PyK2. The inhibition of PyK2 leads to a beneficial strategy to attenuate cancer cell development, including metastasis. Thus, we highlighted the effect of PyK2 on various cancer cell types and the distribution of molecules that affect PyK2 activation. In particular, we underlined the relationship between PyK2 and cancer metastasis and its potential to treat cancer cells.

Oncometabolites drive tumorigenesis by enhancing protein acylation: from chromosomal remodelling to nonhistone modification

Metabolites are intermediate products of cellular metabolism catalysed by various enzymes. Metabolic remodelling, as a biochemical fingerprint of cancer cells, causes abnormal metabolite accumulation. These metabolites mainly generate energy or serve as signal transduction mediators via noncovalent interactions. After the development of highly sensitive mass spectrometry technology, various metabolites were shown to covalently modify proteins via forms of lysine acylation, including lysine acetylation, crotonylation, lactylation, succinylation, propionylation, butyrylation, malonylation, glutarylation, 2-hydroxyisobutyrylation and β-hydroxybutyrylation. These modifications can regulate gene expression and intracellular signalling pathways, highlighting the extensive roles of metabolites. Lysine acetylation is not discussed in detail in this review since it has been broadly investigated. We focus on the nine aforementioned novel lysine acylations beyond acetylation, which can be classified into two categories: histone acylations and nonhistone acylations. We summarize the characteristics and common functions of these acylation types and, most importantly, provide a glimpse into their fine-tuned control of tumorigenesis and potential value in tumour diagnosis, monitoring and therapy.

Mapping glycine uptake and its metabolic conversion to glutathione in mouse mammary tumors using functional mass spectrometry imaging

Although glutathione plays a key role in cancer cell viability and therapy response there is no clear trend in relating the level of this antioxidant to clinical stage, histological grade, or therapy response in patient tumors. The likely reason is that static levels of glutathione are not a good indicator of how a tissue deals with oxidative stress. A better indicator is the functional capacity of the tissue to maintain glutathione levels in response to this stress. However, there are few methods to assess glutathione metabolic function in tissue. We have developed a novel functional mass spectrometry imaging (fMSI) method that can map the variations in the conversion of glycine to glutathione metabolic activity across tumor tissue sections by tracking the fate of three glycine isotopologues administered in a timed sequence to tumor-bearing anesthetized mice. This fMSI method generates multiple time point kinetic data for substrate uptake and glutathione production from each spatial location in the tissue. As expected, the fMSI data shows glutathione metabolic activity varies across the murine 4T1 mammary tumor. Although glutathione levels are highest at the tumor periphery there are regions of high content but low metabolic activity. The timed infusion method also detects variations in delivery of the glycine isotopologues thereby providing a measure of tissue perfusion, including evidence of intermittent perfusion, that contributes to the observed differences in metabolic activity. We believe this new approach will be an asset to linking molecular content to tissue function.

An Immune-Related Genetic Feature Depicted the Heterogeneous Nature of Lung Adenocarcinoma and Squamous Cell Carcinoma and Their Distinctive Predicted Drug Responses

One of the primary causes of global cancer-associated mortality is lung cancer (LC). Current improvements in the management of LC rely mainly on the advancement of patient stratification, both molecularly and clinically, to achieve the maximal therapeutic benefit, while most LC screening protocols remain underdeveloped. In this research, we first employed two algorithms (ESTIMATE and xCell) to calculate the immune/stromal infiltration scores. This helped identify the altered immune infiltration landscapes in lung adenocarcinoma (LUAD) and squamous cell carcinoma (LUSC). Afterward, based on their immune-related characteristics, we successfully stratified the LUAD and LUSC into 2 and 3 clusters, respectively. Different from the conventional bioinformatic approaches that start from the investigation of differential expression of single genes, differentially enriched curated gene sets identified through gene set variation analyses (GSVA) were curated, and gene names were reconstructed afterward. Furthermore, weighted gene correlation network analyses (WGCNA) were used to reveal hub genes highly connected with the clustering process. Actual expression levels of critical hub genes among different clusters were compared and so were the functional pathways these genes enriched into. Lastly, a computational method was applied to predict and compare the responses of each cluster to primary therapeutic agents. The heterogeneity presented in our study, along with the drug responses expected for identified clusters, may shed light on future exploration of combination immunochemotherapy that facilitates the optimization of individualized therapy.

Rapid Profiling of Tumor-Immune Interaction Using Acoustically Assembled Patient-Derived Cell Clusters

Tumor microenvironment crosstalk, in particular interactions between cancer cells, T cells, and myeloid-derived suppressor cells (MDSCs), mediates tumor initiation, progression, and response to treatment. However, current patient-derived models such as tumor organoids and 2D cultures lack some essential niche cell types (e.g., MDSCs) and fail to model complex tumor-immune interactions. Here, the authors present the novel acoustically assembled patient-derived cell clusters (APCCs) that can preserve original tumor/immune cell compositions, model their interactions in 3D microenvironments, and test the treatment responses of primary tumors in a rapid, scalable, and user-friendly manner. By incorporating a large array of 3D acoustic trappings within the extracellular matrix, hundreds of APCCs can be assembled within a petri dish within 2 min. Moreover, the APCCs can preserve sensitive and short-lived (≈1 to 2-day lifespan in vivo) tumor-induced MDSCs and model their dynamic suppression of T cell tumor toxicity for up to 24 h. Finally, using the APCCs, the authors succesully model the combinational therapeutic effect of a multi-kinase inhibitor targeting MDSCs (cabozantinib) and an anti-PD-1 immune checkpoint inhibitor (pembrolizumab). The novel APCCs may hold promising potential in predicting treatment response for personalized cancer adjuvant therapy as well as screening novel cancer immunotherapy and combinational therapy.

The crosstalk of the human microbiome in breast and colon cancer: A metabolomics analysis

The human microbiome's role in colon and breast cancer is described in this review. Understanding how the human microbiome and metabolomics interact with breast and colon cancer is the chief area of this study. First, the role of the gut and distal microbiome in breast and colon cancer is investigated, and the direct relationship between microbial dysbiosis and breast and colon cancer is highlighted. This work also focuses on the many metabolomic techniques used to locate prospective biomarkers, make an accurate diagnosis, and research new therapeutic targets for cancer treatment. This review clarifies the influence of anti-tumor medications on the microbiota and the proactive measures that can be taken to treat cancer using a variety of therapies, including radiotherapy, chemotherapy, next-generation biotherapeutics, gene-based therapy, integrated omics technology, and machine learning.

Autophagy: A Key Player in Pancreatic Cancer Progression and a Potential Drug Target

Simple Summary

With the mortality rate of pancreatic cancer predicted to rise over the coming years, it is essential that effective treatment strategies are developed as soon as possible. Pancreatic cancer has always proven very difficult to treat due to its fast growing and aggressive nature. Chemotherapeutic treatment has struggled to increase the survival rate of pancreatic cancer patients due to effective chemo-resistant properties that derive from the supporting tumor microenvironment and autophagy, a vital survival pathway. This review will explore how the autophagy pathway and tumor microenvironment help to sustain tumor survival under stress and expand into a metastatic state. Due to the comprehensive understanding of the autophagy pathway, we will highlight the potential chinks in the pancreatic tumor’s armor and identify potential targets to overcome chemo-resistance in pancreatic cancer. We will also present novel autophagy inhibitors that could reduce tumor survival and how they could be most effectively conceived.

Abstract

Pancreatic cancer is known to have the lowest survival outcomes among all major cancers, and unfortunately, this has only been marginally improved over last four decades. The innate characteristics of pancreatic cancer include an aggressive and fast-growing nature from powerful driver mutations, a highly defensive tumor microenvironment and the upregulation of advantageous survival pathways such as autophagy. Autophagy involves targeted degradation of proteins and organelles to provide a secondary source of cellular supplies to maintain cell growth. Elevated autophagic activity in pancreatic cancer is recognized as a major survival pathway as it provides a plethora of support for tumors by supplying vital resources, maintaining tumour survival under the stressful microenvironment and promoting other pathways involved in tumour progression and metastasis. The combination of these features is unique to pancreatic cancer and present significant resistance to chemotherapeutic strategies, thus, indicating a need for further investigation into therapies targeting this crucial pathway. This review will outline the autophagy pathway and its regulation, in addition to the genetic landscape and tumor microenvironment that contribute to pancreatic cancer severity. Moreover, this review will also discuss the mechanisms of novel therapeutic strategies that inhibit autophagy and how they could be used to suppress tumor progression.

PDIA2 Bridges Endoplasmic Reticulum Stress and Metabolic Reprogramming During Malignant Transformation of Chronic Colitis

Background

Chronic inflammation contributes to approximately 20% of cancers; the underlying mechanisms are still elusive. Here, using an animal model of colitis to colon-cancerous transformation, we demonstrated that endoplasmic reticulum (ER) stress couples with metabolic reprogramming to promote a malignant transformation of chronic inflammation.

Methods

The animal model for chronic colitis to colon-cancerous transformation was established in C57BL/6N mice by azoxymethane (AOM) and dextran sodium sulfate (DSS) treatments. The differential proteins in control and AOM/DSS-treated colon mucosa were determined using proteomic analysis; the kinetics of metabolic modifications were monitored by mitochondrial oxygen flux, extracellular acidification, and targeted metabolomics; the molecule linker between ER stress and metabolic modifications were identified by coimmunoprecipitation, KEGG pathway analysis, and the subcutaneous tumor model using gene-specific knockdown colon cancer cells. Tissue array analysis were used to evaluate the differential protein in cancer and cancer-adjacent tissues.

Results

AOM/DSS treatment induced 38 tumors in 10 mice at the 14th week with the mean tumor size 9.35 ± 3.87 mm², which was significantly decreased to 5.85 ± 0.95 mm² by the ER stress inhibitor 4-phenylbutyric acid (4PBA). Seven differential proteins were determined from control (1,067 ± 48) and AOM/DSS-treated mucosa (1,077 ± 59); the level of ER protein PDIA2 (protein disulfide isomerase-associated 2) was increased over 7-fold in response to AOM/DSS treatment. PDIA2 interacted with 420 proteins that were involved in 8 signaling pathways, in particular with 53 proteins in metabolic pathways. PDIA2 translocated from ER to mitochondria and interacted with the components of complexes I and II to inhibit oxophosphorylation but increase glycolysis. Knockdown PDIA2 in colon cancer cells restored the metabolic imbalance and significantly repressed tumor growth in the xenograft animal model. 4PBA therapy inhibited the AOM/DSS-mediated overexpression of PDIA2 and metabolic modifications and suppressed colon cancer growth. In clinic, PDIA2 was overexpressed in colon cancer tissues rather than cancer-adjacent tissues and was related with the late stages and lymph node metastasis of colon cancer.

Conclusions

Persistent ER stress reprograms the metabolism to promote the malignant transformation of chronic colitis; PDIA2 serves as a molecule linker between ER stress and metabolic reprogramming. The inhibition of ER stress restores metabolic homeostasis and attenuates the cancerous transformation of chronic inflammation.

Modulating Tumour Hypoxia in Prostate Cancer Through Exercise: The Impact of Redox Signalling on Radiosensitivity

Prostate cancer is a complex disease affecting millions of men globally. Radiotherapy (RT) is a common treatment modality although treatment efficacy is dependent upon several features within the tumour microenvironment (TME), especially hypoxia. A hypoxic TME heightens radioresistance and thus disease recurrence and treatment failure continues to pose important challenges. However, the TME evolves under the influence of factors in systemic circulation and cellular crosstalk, underscoring its potential to be acutely and therapeutically modified. Early preclinical evidence suggests exercise may affect tumour growth and some of the benefits drawn, could act to radiosensitise tumours to treatment. Intracellular perturbations in skeletal muscle reactive oxygen species (ROS) stimulate the production of numerous factors that can exert autocrine, paracrine, and endocrine effects on the prostate. However, findings supporting this notion are limited and the associated mechanisms are poorly understood. In light of this preclinical evidence, we propose systemic changes in redox signalling with exercise activate redox-sensitive factors within the TME and improve tumour hypoxia and treatment outcomes, when combined with RT. To this end, we suggest a connection between exercise, ROS and tumour growth kinetics, highlighting the potential of exercise to sensitise tumour cells to RT, and improve treatment efficacy.

Chlorogenic acid activates Nrf2/SKN-1 and prolongs the lifespan of Caenorhabditis elegans via the Akt-FOXO3/DAF16a-DDB1 pathway and activation of DAF16f

Chlorogenic acid (CGA) is the most abundant polyphenol in coffee. It has been widely reported to exhibit antioxidant activity by activating nuclear factor erythroid 2-related factor 2 (Nrf2) potentially via the canonical Keap1-Nrf2 pathway. We herein demonstrated that the knockdown of WDR23, but not Keap1, abolished the effects of CGA on the activation of Nrf2. CGA decreased the expression of DDB1, an adaptor for WDR23-Cullin 4A-RING ligase (CRL4A WDR23). FOXO3, a major target for inactivation by the PI3K/Akt pathway, was identified as the transcription factor responsible for the basal and CGA-inhibited expression of the DDB1 gene. CGA blocked FOXO3 binding to importin-7 (IPO7), thereby inhibiting the nuclear accumulation of FOXO3, down-regulating the expression of DDB1, inhibiting the activity of CRL4 WDR23, and ultimately increasing that of Nrf2. This pathway was conserved in Caenorhabditis elegans, and CGA extended the lifespan partly through this pathway. We found that in C. elegans, the isoform DAF-16a, but not DAF-16f, regulated the expression levels of ddb-1 mRNA and SKN-1 protein. CGA prolonged the mean lifespan of DAF-16a- and DAF-16f-rescued worms by 24% and 9%, respectively, suggesting that both isoforms involve in lifespan-extending effects of CGA, with DAF-16a being more important than DAF-16f. Based on these results, we established a novel Akt-FOXO3/DAF16a-DDB1 axis that links nutrient sensing and oxidative stress response pathways. Our results also provide a novel molecular mechanism for Nrf2/SKN-1 activation by CGA and the increased lifespan of C. elegans by CGA via this pathway.

Melatonin: Regulation of Prion Protein Phase Separation in Cancer Multidrug Resistance

The unique ability to adapt and thrive in inhospitable, stressful tumor microenvironments (TME) also renders cancer cells resistant to traditional chemotherapeutic treatments and/or novel pharmaceuticals. Cancer cells exhibit extensive metabolic alterations involving hypoxia, accelerated glycolysis, oxidative stress, and increased extracellular ATP that may activate ancient, conserved prion adaptive response strategies that exacerbate multidrug resistance (MDR) by exploiting cellular stress to increase cancer metastatic potential and stemness, balance proliferation and differentiation, and amplify resistance to apoptosis. The regulation of prions in MDR is further complicated by important, putative physiological functions of ligand-binding and signal transduction. Melatonin is capable of both enhancing physiological functions and inhibiting oncogenic properties of prion proteins. Through regulation of phase separation of the prion N-terminal domain which targets and interacts with lipid rafts, melatonin may prevent conformational changes that can result in aggregation and/or conversion to pathological, infectious isoforms. As a cancer therapy adjuvant, melatonin could modulate TME oxidative stress levels and hypoxia, reverse pH gradient changes, reduce lipid peroxidation, and protect lipid raft compositions to suppress prion-mediated, non-Mendelian, heritable, but often reversible epigenetic adaptations that facilitate cancer heterogeneity, stemness, metastasis, and drug resistance. This review examines some of the mechanisms that may balance physiological and pathological effects of prions and prion-like proteins achieved through the synergistic use of melatonin to ameliorate MDR, which remains a challenge in cancer treatment.

Metabolic regulation of ferroptosis in the tumor microenvironment

Ferroptosis is an iron-dependent, non-apoptotic form of regulated cell death triggered by impaired redox and antioxidant machinery and propagated by the accumulation of toxic lipid peroxides. A compendium of experimental studies suggest that ferroptosis is tumor-suppressive. Sensitivity or resistance to ferroptosis can be regulated by cell-autonomous and non-cell-autonomous metabolic mechanisms. This includes a role for ferroptosis that extends beyond the tumor cells themselves, mediated by components of the tumor microenvironment, including T cells and other immune cells. Herein, we review the intrinsic and extrinsic factors that promote the sensitivity of cancer cells to ferroptosis and conclude by describing approaches to harness the full utility of ferroptotic agents as therapeutic options for cancer therapy.

The role of polyphenols in overcoming cancer drug resistance: a comprehensive review

Chemotherapeutic drugs are used to treat advanced stages of cancer or following surgery. However, cancers often develop resistance against drugs, leading to failure of treatment and recurrence of the disease. Polyphenols are a family of organic compounds with more than 10,000 members which have a three-membered flavan ring system in common. These natural compounds are known for their beneficial properties, such as free radical scavenging, decreasing oxidative stress, and modulating inflammation. Herein, we discuss the role of polyphenols (mainly curcumin, resveratrol, and epigallocatechin gallate [EGCG]) in different aspects of cancer drug resistance. Increasing drug uptake by tumor cells, decreasing drug metabolism by enzymes (e.g. cytochromes and glutathione-S-transferases), and reducing drug efflux are some of the mechanisms by which polyphenols increase the sensitivity of cancer cells to chemotherapeutic agents. Polyphenols also affect other targets for overcoming chemoresistance in cancer cells, including cell death (i.e. autophagy and apoptosis), EMT, ROS, DNA repair processes, cancer stem cells, and epigenetics (e.g. miRNAs).

The role of the metabolite cargo of extracellular vesicles in tumor progression

Metabolomic reprogramming in tumor and stroma cells is a hallmark of cancer but understanding its effects on the metabolite composition and function of tumor-derived extracellular vesicles (EVs) is still in its infancy. EVs are membrane-bound sacs with a complex molecular composition secreted by all living cells. They are key mediators of intercellular communication both in normal and pathological conditions and play a crucial role in tumor development. Although lipids are major components of EVs, most of the EV cargo studies have targeted proteins and nucleic acids. The potential of the EV metabolome as a source for biomarker discovery has gained recognition recently, but knowledge on the biological activity of tumor EV metabolites still remains limited. Therefore, we aimed (i) to compile the list of metabolites identified in tumor EVs isolated from either clinical specimens or in vitro samples and (ii) describe their role in tumor progression through literature search and pathway analysis.

Targeting the redox imbalance in mitochondria: A novel mode for cancer therapy

Changes in reactive oxygen species (ROS) levels affect many aspects of cell behavior. During carcinogenesis, moderate ROS production modifies gene expression to alter cell function, elevating metabolic activity and ROS. To avoid extreme ROS-activated death, cancer cells increase antioxidative capacity, regulating sustained ROS levels that promote growth. Anticancer therapies are exploring inducing supranormal, cytotoxic oxidative stress levels either inhibiting antioxidative capacity or promoting excess ROS to selectively destroy cancer cells, triggering mechanisms such as apoptosis, autophagy, necrosis, or ferroptosis. This review exemplifies pro-oxidants (natural/synthetic/repurposed drugs) and their clinical significance as cancer therapies providing revolutionary approaches.

Molecular interaction of HIC, an agonist of P2Y1 receptor, and its role in prostate cancer apoptosis

Prostate cancer is a heterogeneous, slow growing asymptomatic cancer that predominantly affects man. A purinergic G-protein coupled receptor, P2Y1R, is targeted for its therapeutic value since it plays a crucial role in many key molecular events of cancer progression and invasion. Our previous study demonstrated that indoline derivative, 1 ((1-(2-Hydroxy-5-nitrophenyl) (4-hydroxyphenyl) methyl)indoline-4‑carbonitrile; HIC), stimulates prostate cancer cell (PCa) growth inhibition via P2Y1R. However, the mode of interaction of P2Y1R with HIC involved in this process remains unclear. Here, we have reported the molecular interactions of HIC with P2Y1R. Molecular dynamics simulation was performed that revealed the stable specific binding of the protein-ligand complex. In vitro analysis has shown increased apoptosis of PCa-cells, PC3, and DU145, upon specific interaction of P2Y1R-HIC. This was further validated using siRNA analysis that showed a higher percentage of apoptotic cells in PCa-cells transfected with P2Y-siRNA-MRS2365 than P2Y-siRNA-HIC treatment. Decreased mitochondrial membrane potential (MMP) activity and reduced glutathione (GSH) level show their role in P2Y1R-HIC mediated apoptosis. These in silico and in vitro results confirmed that HIC could induce mitochondrial apoptotic signaling through the P2Y1R activation. Thus, HIC being a potential ligand upon interaction with P2Y1R might have therapeutic value for the treatment of prostate cancer.

Redox Regulation and Oxidative Stress in Mammalian Oocytes and Embryos Developed In Vivo and In Vitro

Oocytes and preimplantation embryos require careful regulation of the redox environment for optimal development both in vivo and in vitro. Reactive oxygen species (ROS) are generated throughout development as a result of cellular metabolism and enzyme reactions. ROS production can result in (i) oxidative eustress, where ROS are helpful signalling molecules with beneficial physiological functions and where the redox state of the cell is maintained within homeostatic range by a closely coupled system of antioxidants and antioxidant enzymes, or (ii) oxidative distress, where excess ROS are deleterious and impair normal cellular function. in vitro culture of embryos exacerbates ROS production due to a range of issues including culture-medium composition and laboratory culture conditions. This increase in ROS can be detrimental not only to assisted reproductive success rates but can also result in epigenetic and genetic changes in the embryo, resulting in transgenerational effects. This review examines the effects of oxidative stress in the oocyte and preimplantation embryo in both the in vivo and in vitro environment, identifies mechanisms responsible for oxidative stress in the oocyte/embryo in culture and approaches to reduce these problems, and briefly examines the potential impacts on future generations.

The potentials of carbon monoxide-releasing molecules in cancer treatment: An outlook from ROS biology and medicine

Carbon monoxide (CO) is now well recognized a pivotal endogenous signaling molecule in mammalian lives. The proof-of-concept employing chemical carriers of exogenous CO as prodrugs for CO release, also known as CO-releasing molecules (CO-RMs), has been appreciated. The major advantage of CO-RMs is that they are able to deliver CO to the target sites in a controlled manner. There is an increasing body of experimental studies suggesting the therapeutic potentials of CO and CO-RMs in different cancer models. This review firstly presents a short but crucial view concerning the characteristics of CO and CO-RMs. Then, the anticancer activities of CO-RMs that target many cancer hallmarks, mainly proliferation, apoptosis, angiogenesis, and invasion and metastasis, are discussed. However, their anticancer activities are varying and cell-type specific. The aerobic metabolism of molecular oxygen inevitably generates various oxygen-containing reactive metabolites termed reactive oxygen species (ROS) which play important roles in both physiology and pathophysiology. Although ROS act as a double-edged sword in cancer, both sides of which may potentially have been exploited for therapeutic benefits. The main focus of the present review is thus to identify the possible signaling network by which CO-RMs can exert their anticancer actions, where ROS play the central role. Another important issue concerning the potential effect of CO-RMs on the aerobic glycolysis (the Warburg effect) which is a feature of cancer metabolic reprogramming is given before the conclusion with future prospects on the challenges of developing CO-RMs into clinically pharmaceutical candidates in cancer therapy.

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CO-RMs as pro-drugs for controlled CO delivery are potentially beneficial in cancer treatment.

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Anticancer activities of CO-RMs are varying and cell-type specific.

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Anti-proliferative, pro-apoptotic, and anti-angiogenic effects are major niches.

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ROS may play a central role in the molecular pathways underlying anticancer activities of CO-RMs.

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CO-RMs can act against Warburg effect, a feature of cancer metabolic reprogramming.

Extracellular Reactive Oxygen Species (ROS) Production in Fresh Donkey Sperm Exposed to Reductive Stress, Oxidative Stress and NETosis

Jenny shows a large endometrial reaction after semen influx to the uterus with a large amount of polymorphonuclear neutrophils (PMN) migrating into the uterine lumen. PMN act as a sperm selection mechanism through phagocytosis and NETosis (DNA extrudes and, together with proteins, trap spermatozoa). While a reduced percentage of spermatozoa are phagocytosed by PMN, most are found to be attached to neutrophil extracellular traps (NETs). This selection process together with sperm metabolism produces a large amount of reactive oxygen species (ROS) that influence the reproductive success. The present study aimed to determine the extracellular ROS production in both sperm and PMN. With this purpose, (1) donkey sperm were exposed to reductive and oxidative stresses, through adding different concentrations of reduced glutathione (GSH) and hydrogen peroxide (H₂O₂), respectively; and (2) PMN were subjected to NETosis in the presence of the whole semen, sperm, seminal plasma (SP) or other activators such as formyl-methionyl-leucyl-phenylalanine (FMLP). Extracellular ROS production (measured as H₂O₂ levels) was determined with the Amplex^® Red Hydrogen Peroxide/Peroxidase Assay Kit. Donkey sperm showed more resilience to oxidative stress than to the reductive one, and GSH treatments led to greater H₂O₂ extracellular production. Moreover, not only did SP appear to be the main inducer of NETosis in PMN, but it was also able to maintain the extracellular H₂O₂ levels produced by sperm and NETosis.

Association of Tumour Microenvironment with Protein Glycooxidation, DNA Damage, and Nitrosative Stress in Colorectal Cancer

Purpose

In this study, we evaluated the total antioxidant capacity, nitrosative stress, and protein/DNA oxidation and glycoxidation products in patients with colorectal cancer regarding histopathological parameters associated with the tumour microenvironment, such as inflammatory infiltration and tumour budding and compare all determined parameters between tumours located in the right and left side of the colon and normal mucosa.

Patients and Methods

Ferric reducing antioxidant power (FRAP), nitrosative stress (myeloperoxidase (MPO), nitrogen oxide (NO), peroxynitrite, and nitrotyrosine), protein oxidation products (protein carbonyls (PC), total thiols, and ischemia modified albumin (IMA)), protein glycooxidation products (tryptophan, kynurenine, N-formylkynurenine, dityrosine, Amadori product, advanced glycation end products (AGE)) and 8-hydroxydeoxyguanosine (8-OHdG) were measured in homogenates from normal and cancerous tissue of 30 patients with colorectal cancer.

Results

Levels of FRAP (p=0.0009), IMA (p=0.0002), kynurenine (p<0.0001), N-formylkynurenine (p<0.0001), dityrosine (p<0.0001), Amadori products (p=0.0024), AGE (p<0.0001), MPO (p<0.0001), NO (p<0.0001) and nitrotyrosine (p=0.0011) were increased, whereas PC (p=0.0004), tryptophan (p<0.0001), 8-OHdG (p<0.0001) and peroxynitrite (p=0.0003) were decreased in the left-side tumour compared to the right-side tumour and normal mucosa.

Conclusion

Our results showed that colorectal cancer is related with disturbances in antioxidant defense and increased oxidative and nitrosative damages to proteins and DNA. These parameters may be useful for evaluation the progression and differentiation of the tumour location. We also demonstrated that redox indicators may depend on the histological type of the tumour and may influence tumour invasion depth, presence of lymph node and distant metastasis, vascular and neural invasion, inflammatory infiltration, and tumour budding, which are part of the tumour microenvironment.

Improvement in Redox Homeostasis after Cytoreductive Surgery in Colorectal Adenocarcinoma

Colorectal cancer (CRC) as one the most common cancer type is associated with oxidative stress. Surgery is the only curative modality for early-stage CRC. The aim of this study was to evaluate the oxidative damage biomarkers as well as enzymatic and nonenzymatic antioxidants in patients with CRC before and after tumor resection and in healthy controls. 60 patients with stage I/II colorectal adenocarcinoma and 43 healthy controls were recruited in this study. We measured plasma levels of oxidative damage biomarkers, including advanced oxidation protein products (AOPP), advanced glycation end products (AGEs), malondialdehyde (MDA), and oxidized low-density lipoprotein (ox-LDL) at baseline and after tumor removal. We also evaluated the plasma activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) as enzymatic antioxidants and the ferric reducing antioxidant power (FRAP) assay for nonenzymatic antioxidant capacity. Patients with CRC had significantly higher AGE, AOPP, MDA, and ox-LDL and also FRAP levels and higher SOD and GPx and lower CAT activity levels compared to healthy controls (p < 0.05). We did not observe any statistically significant correlation between redox biomarkers and the size and stage of the tumor. AGEs (72.49 ± 4.7 vs. 67.93 ± 8.8, p < 0.001), AOPP (137.64 ± 21.9 vs. 119.08 ± 33.1, p < 0.001), MDA (3.56 ± 0.30 vs. 3.05 ± 0.33, p < 0.001), and ox-LDL (19.78 ± 0.97 vs. 16.94 ± 1.02, p < 0.001) concentrations reduced significantly after tumor removal. The largest effect sizes were found in ox-LDL (d = -2.853, 95% CI 2.50-3.19) and MDA (d = -1.617, 95% CI 0.43-0.57). Serum FRAP levels (1097.5 ± 156.7 vs. 1239.3 ± 290, p < 0.001) and CAT (2.34 ± 0.34 vs. 2.63 ± 0.38, p < 0.001), GPx (102.37 ± 6.58 vs. 108.03 ± 6.95, p < 0.001), and SOD (5.13 ± 0.39 vs. 5.53 ± 0.31, p < 0.001) activity levels increased significantly after surgery. The largest effect sizes among antioxidants were seen in SOD (d = 1.135, 95% CI 0.46-0.34) and GPx (d = 0.836, 95% CI 0.35-0.23). This study indicated that patients with colorectal cancer had higher levels of oxidative stress and antioxidant activity compared to healthy controls. After surgical resection of tumor, we observed a substantial improvement in redox homeostasis.

Adipose Tissue Redox Microenvironment as a Potential Link between Persistent Organic Pollutants and the 16-Year Incidence of Non-hormone-Dependent Cancer

We aimed to assess the relationships among the adipose tissue's (AT) oxidative microenvironment, in situ accumulated persistent organic pollutant (POP) concentrations, and cancer development. POP and oxidative stress levels were quantified in AT samples from 382 adults recruited within the GraMo cohort (2003-2004) in Granada (Spain). The 16-year cancer incidence was ascertained by reviewing health/administrative databases. Cox-regression models and mediation analyses were performed. The enzymes superoxide dismutase (SOD) and glutathione reductase (GRd) were positively associated with the risk of non-hormone-dependent (NHD) cancer [adjusted hazard ratio (HR) 1.76; 95% confidence interval (CI): 1.17, 2.64 and HR 2.35; 95% CI: 1.41, 3.94, respectively]. After adjustment for covariates, polychlorinated biphenyl-138 (PCB-138) (HR 1.78; 95% CI: 1.03, 3.09), β-hexachlorocyclohexane (β-HCH) (HR 1.70; 95% CI: 1.09, 2.64), and hexachlorobenzene (HR 1.54; 95% CI: 1.02, 2.33) were also positively associated with the risk of NHD cancer. Although confidence intervals included the null value, probably because of the modest number of cancer cases, we observed a potential mediation effect of SOD and GRd on the associations between β-HCH and the risk of NHD tumors (percent mediated = 33 and 47%, respectively). Our results highlight the relevance of human AT's oxidative microenvironment as a predictor of future cancer risk as well as its potential mediating role on POP-related carcinogenesis. Given their novelty, these findings should be interpreted with caution and confirmed in future studies.

Hijacked Immune Cells in the Tumor Microenvironment: Molecular Mechanisms of Immunosuppression and Cues to Improve T Cell-Based Immunotherapy of Solid Tumors

The understanding of the tumor microenvironment (TME) has been expanding in recent years in the context of interactions among different cell types, through direct cell–cell communication as well as through soluble factors. It has become evident that the development of a successful antitumor response depends on several TME factors. In this context, the number, type, and subsets of immune cells, as well as the functionality, memory, and exhaustion state of leukocytes are key factors of the TME. Both the presence and functionality of immune cells, in particular T cells, are regulated by cellular and soluble factors of the TME. In this regard, one fundamental reason for failure of antitumor responses is hijacked immune cells, which contribute to the immunosuppressive TME in multiple ways. Specifically, reactive oxygen species (ROS), metabolites, and anti-inflammatory cytokines have central roles in generating an immunosuppressive TME. In this review, we focused on recent developments in the immune cell constituents of the TME, and the micromilieu control of antitumor responses. Furthermore, we highlighted the current challenges of T cell-based immunotherapies and potential future strategies to consider for strengthening their effectiveness.

Responses of Porcupine and Wntless proteins to oxidative, hypoxic and endoplasmic reticulum stresses

The WNT (Wingless and Int-1) proteins play a role in stem cell development and cell differentiation. Mutations in the WNT proteins lead to the development of various tumours, including gastric tumours. Porcupine (PORCN) is a palmitoyltransferase and Wntless (WLS) is a dedicated WNT transport protein that modify and fold the WNT proteins respectively and are involved in their proper secretion and binding to the frizzled (FZD) receptor and the lipoprotein receptor-related protein 5 or 6 (LRP5/6). We investigated how modifications of PORCN and WLS result in changes in WNT expression and secretion from cells under stress conditions that occur in the tumour microenvironment (hypoxia, oxidative stress, endoplasmic reticulum (ER) stress). In the present study, we found the mRNA expression of both PORCN and WLS were significantly increased with treatments inducing oxidative stress (antimycin A) and proteasome inhibition (MG-132), in human colon cancer (HCT116) and human intestinal epithelial cell-6 (HIEC-6) cells. Treatment with ER stressors thapsigargin, tunicamycin, and dithiolthreitol significantly increased PORCN gene expression, while treatment with thapsigargin and dithiolthreitol increased WLS gene expression. The expression of PORCN and WLS proteins increased with hypoxia and ER stressor treatments in both HCT116 and HIEC-6 cells. All stressors used in this study increased beta-catenin (β-catenin) expression in HCT116 cells. Our results suggest that these stressors alter PORCN, WLS and β-catenin expression and function which may, in turn, alter WNT secretion. Silencing the expression of PORCN and WLS with siRNA expression reduced the expression of WLS and WNT3A in HCT116 cells. The possibility exists that PORCN specifically may be involved in a novel signaling pathway, independent of its palmitoleation of the WNT proteins and its role in their secretion, that is rate-limiting for cancer cell growth and tumorigenesis, within the tumour microenvironment.

An Updated Review on Implications of Autophagy and Apoptosis in Tumorigenesis: Possible Alterations in Autophagy through Engineered Nanomaterials and Their Importance in Cancer Therapy

Most commonly recognized as a catabolic pathway, autophagy is a perplexing mechanism through which a living cell can free itself of excess cytoplasmic components, i.e., organelles, by means of certain membranous vesicles or lysosomes filled with degrading enzymes. Upon exposure to external insult or internal stimuli, the cell might opt to activate such a pathway, through which it can gain control over the maintenance of intracellular components and thus sustain homeostasis by intercepting the formation of unnecessary structures or eliminating the already present dysfunctional or inutile organelles. Despite such appropriateness, autophagy might also be considered a frailty for the cell, as it has been said to have a rather complicated role in tumorigenesis. A merit in the early stages of tumor formation, autophagy appears to be salutary because of its tumor-suppressing effects. In fact, several investigations on tumorigenesis have reported diminished levels of autophagic activity in tumor cells, which might result in transition to malignancy. On the contrary, autophagy has been suggested to be a seemingly favorable mechanism to progressed malignancies, as it contributes to survival of such cells. Based on the recent literature, this mechanism might also be activated upon the entry of engineered nanomaterials inside a cell, supposedly protecting the host from foreign materials. Accordingly, there is a good chance that therapeutic interventions for modulating autophagy in malignant cells using nanoparticles may sensitize cancerous cells to certain treatment modalities, e.g., radiotherapy. In this review, we will discuss the signaling pathways involved in autophagy and the significance of the mechanism itself in apoptosis and tumorigenesis while shedding light on possible alterations in autophagy through engineered nanomaterials and their potential therapeutic applications in cancer. SIGNIFICANCE STATEMENT: Autophagy has been said to have a complicated role in tumorigenesis. In the early stages of tumor formation, autophagy appears to be salutary because of its tumor-suppressing effects. On the contrary, autophagy has been suggested to be a favorable mechanism to progressed malignancies. This mechanism might be affected upon the entry of nanomaterials inside a cell. Accordingly, therapeutic interventions for modulating autophagy using nanoparticles may sensitize cancerous cells to certain therapies.

Targeting Fibrosis: The Bridge That Connects Pancreatitis and Pancreatic Cancer

Pancreatic fibrosis is caused by the excessive deposits of extracellular matrix (ECM) and collagen fibers during repeated necrosis to repair damaged pancreatic tissue. Pancreatic fibrosis is frequently present in chronic pancreatitis (CP) and pancreatic cancer (PC). Clinically, pancreatic fibrosis is a pathological feature of pancreatitis and pancreatic cancer. However, many new studies have found that pancreatic fibrosis is involved in the transformation from pancreatitis to pancreatic cancer. Thus, the role of fibrosis in the crosstalk between pancreatitis and pancreatic cancer is critical and still elusive; therefore, it deserves more attention. Here, we review the development of pancreatic fibrosis in inflammation and cancer, and we discuss the therapeutic strategies for alleviating pancreatic fibrosis. We further propose that cellular stress response might be a key driver that links fibrosis to cancer initiation and progression. Therefore, targeting stress proteins, such as nuclear protein 1 (NUPR1), could be an interesting strategy for pancreatic fibrosis and PC treatment.

Inhibition of vascular adhesion protein-1 enhances the anti-tumor effects of immune checkpoint inhibitors

Modulation of the immunosuppressive tumor microenvironment (TME) is essential for enhancing the anti‐tumor effects of immune checkpoint inhibitors (ICIs). Adhesion molecules and enzymes such as vascular adhesion protein‐1 (VAP‐1), which are expressed in some cancers and tumor vascular endothelial cells, may be involved in the generation of an immunosuppressive TME. In this study, the role of VAP‐1 in TME was investigated in 2 murine colon cancer models and human cancer cells. Intraperitoneal administration of the VAP‐1‐specific inhibitor U‐V296 inhibited murine tumor growth by enhancing IFN‐γ‐producing tumor antigen‐specific CD8⁺ T cells. U‐V296 exhibited significant synergistic anti‐tumor effects with ICIs. In the TME of mice treated with U‐V296, the expression of genes associated with M2‐like macrophages, Th2 cells (Il4, Retnla, and Irf4), angiogenesis (Pecam1), and fibrosis (Acta2, Loxl2) were significantly decreased, and the Th1/Th2 balance was increased. H₂O₂, an enzymatic product of VAP‐1, which promoted the production of IL‐4 by mouse Th2 and inhibited IFN‐γ by mouse Th1 and human tumor‐infiltrating lymphocytes, was decreased in tumors and CD31⁺ tumor vascular endothelial cells in the TMEs of mice treated with VAP‐1 inhibitor. TCGA database analysis showed that VAP‐1 expression was a negative prognostic factor in human cancers, exhibiting a significant positive correlation with IL‐4, IL4R, and IL‐13 expression and a negative correlation with IFN‐γ expression. These results indicated that VAP‐1 is involved in the immunosuppressive TMEs through H₂O₂‐associated Th2/M2 conditions and may be an attractive target for the development of combination cancer immunotherapy with ICIs.

Exosomes as Pleiotropic Players in Pancreatic Cancer

Pancreatic cancer (PC) incidence is rising and due to late diagnosis, combined with unsatisfactory response to current therapeutic approaches, this tumor has an extremely high mortality rate. A better understanding of the mechanisms underlying pancreatic carcinogenesis is of paramount importance for rational diagnostic and therapeutic approaches. Multiple lines of evidence have showed that exosomes are actively involved in intercellular communication by transferring their cargos of bioactive molecules to recipient cells within the tumor microenvironment and systemically. Intriguingly, exosomes may exert both protumor and antitumor effects, supporting or hampering processes that play a role in the pathogenesis and progression of PC, including shifts in tumor metabolism, proliferation, invasion, metastasis, and chemoresistance. They also have a dual role in PC immunomodulation, exerting immunosuppressive or immune enhancement effects through several mechanisms. PC-derived exosomes also induce systemic metabolic alterations, leading to the onset of diabetes and weight loss. Moreover, exosomes have been described as promising diagnostic and prognostic biomarkers for PC. Their potential application in PC therapy as drug carriers and therapeutic targets is under investigation. In this review, we provide an overview of the multiple roles played by exosomes in PC biology through their specific cargo biomolecules and of their potential exploitation in early diagnosis and treatment of PC.

Drug Resistance in Glioblastoma: The Two Faces of Oxidative Stress

Glioblastomas (GBM) are the most common primary brain tumor with a median survival of 15 months. A population of cells with stem cell properties (glioblastoma stem cells, GSCs) drives the initiation and progression of GBM and is localized in specialized microenvironments which support their behavior. GBM are characterized as extremely resistant to therapy, resulting in tumor recurrence. Reactive oxygen species (ROS) control the cellular stability by influencing different signaling pathways. Normally, redox systems prevent cell oxidative damage; however, in gliomagenesis, the cellular redox mechanisms are highly impaired. Herein we review the dual nature of the redox status in drug resistance. ROS generation in tumor cells affects the cell cycle and is involved in tumor progression and drug resistance in GBM. However, excess ROS production has been found to induce cell death programs such as apoptosis and autophagy. Since GBM cells have a high metabolic rate and produce high levels of ROS, metabolic adaptation in these cells plays an essential role in resistance to oxidative stress-induced cell death. Finally, the microenvironment with the stromal components participates in the enhancement of the oxidative stress to promote tumor progression and drug resistance.

Hydrogen-Peroxide Synthesis and LDL-Uptake Controls Immunosuppressive Properties in Monocyte-Derived Dendritic Cells

BACKGROUND AND AIMS

Induction of myeloid-derived suppressor cells (MDSC) is a critical step in immune cell evasion by different cancer types, including liver cancer. In the liver, hepatic stromal cells orchestrate induction of MDSCs, employing a mechanism dependent on hydrogen peroxide (H2O2) depletion. However, the effects on monocyte-derived dendritic cells (moDCs) are unknown.

METHODS

Monocytes from healthy donors were differentiated to moDCs in the presence of extracellular enzymatic H2O2-depletion (hereinafter CAT-DCs), and studied phenotypically and functionally. To elucidate the underlying molecular mechanisms, we analyzed H2O2- and LDL-metabolism as they are interconnected in monocyte-driven phagocytosis.

RESULTS

CAT-DCs were of an immature DC phenotype, particularly characterized by impaired expression of the costimulatory molecules CD80/86. Moreover, CAT-DCs were able to suppress T-cells using indoleamine 2,3-dioxygenase (IDO), and induced IL10/IL17-secreting T-cells-a subtype reported to exert immunosuppression in acute myeloid leukemia. CAT-DCs also displayed significantly increased NADPH-oxidase-driven H2O2-production, enhancing low-density lipoprotein (LDL)-uptake. Blocking LDL-uptake restored maturation, and attenuated the immunosuppressive properties of CAT-DCs.

DISCUSSION

Here, we report a novel axis between H2O2- and LDL-metabolism controlling tolerogenic properties in moDCs. Given that moDCs are pivotal in tumor-rejection, and lipid-accumulation is associated with tumor-immune-escape, LDL-metabolism appears to play an important role in tumor-immunology.