Role of cystine transport in intracellular glutathione level and cisplatin resistance in human ovarian cancer cell lines

Discovery and Validation of Ferroptosis-Associated Genes of Ulcerative Colitis

Background

Ulcerative colitis (UC) is a long-lasting idiopathic condition, but its precise mechanisms remain unclear. Meanwhile, evidence has demonstrated that ferroptosis seems to interlock with the progress of UC. This research sought to identify hub genes of UC related to ferroptosis.

Methods

First, the relevant profiles for this article were obtained from GEO database. From the FerrDb, 479 genes linked to ferroptosis were retrieved. Using analysis of the difference and WGCNA on colonic samples from GSE73661, the remaining six hub genes linked to ferroptosis and UC were discovered. Through logistic regression analyses, the diagnostic model was constructed and was then evaluated by external validation using dataset GSE92415. Afterwards, the correlation between immune cell filtration in UC and hub genes was examined. Finally, a mice model of colitis was established, and the results were verified using qRT-PCR.

Results

We acquired six hub genes linked to ferroptosis and UC. In order to create a diagnostic model for UC, we used logistic regression analysis to screen three of the six ferroptosis related genes (HIF1A, SLC7A11, and LPIN1). The ROC curve showed that the three hub genes had outstanding potential for disease diagnosis (AUC = 0.976), which was subsequently validated in samples from GSE92415 (AUC = 0.962) and blood samples from GSE3365 (AUC = 0.847) and GSE94648 (AUC = 0.769). These genes might be crucial for UC immunity based upon the results on the immune system. Furthermore, mouse samples examined using qRT-PCR also verified our findings.

Conclusion

In conclusion, the findings have important implications for ferroptosis and UC, and these hub genes may also offer fresh perspectives on the aetiology and therapeutic approaches of UC.

Exploring the relationship between anastasis and mitochondrial ROS-mediated ferroptosis in metastatic chemoresistant cancers: a call for investigation

Ferroptosis induces significant changes in mitochondrial morphology, including membrane condensation, volume reduction, cristae alteration, and outer membrane rupture, affecting mitochondrial function and cellular fate. Recent reports have described the intrinsic cellular iron metabolism and its intricate connection to ferroptosis, a significant kind of cell death characterized by iron dependence and oxidative stress regulation. Furthermore, updated molecular insights have elucidated the significance of mitochondria in ferroptosis and its implications in various cancers. In the context of cancer therapy, understanding the dual role of anastasis and ferroptosis in chemoresistance is crucial. Targeting the molecular pathways involved in anastasis may enhance the efficacy of ferroptosis inducers, providing a synergistic approach to overcome chemoresistance. Research into how DNA damage response (DDR) proteins, metabolic changes, and redox states interact during anastasis and ferroptosis can offer new insights into designing combinatorial therapeutic regimens against several cancers associated with stemness. These treatments could potentially inhibit anastasis while simultaneously inducing ferroptosis, thereby reducing the likelihood of cancer cells evading death and developing resistance to chemotherapy. The objective of this study is to explore the intricate interplay between anastasis, ferroptosis, EMT and chemoresistance, and immunotherapeutics to better understand their collective impact on cancer therapy outcomes. We searched public research databases including google scholar, PubMed, relemed, and the national library of medicine related to this topic. In this review, we discussed the interplay between the tricarboxylic acid cycle and glycolysis implicated in modulating ferroptosis, adding complexity to its regulatory mechanisms. Additionally, the regulatory role of reactive oxygen species (ROS) and the electron transport chain (ETC) in ferroptosis has garnered significant attention. Lipid metabolism, particularly involving GPX4 and System Xc- plays a significant role in both the progression of ferroptosis and cancer. There is a need to investigate the intricate interplay between anastasis, ferroptosis, and chemoresistance to better understand cancer therapy clinical outcomes. Integrating anastasis, and ferroptosis into strategies targeting chemoresistance and exploring its potential synergy with immunotherapy represent promising avenues for advancing chemoresistant cancer treatment. Understanding the intricate interplay among mitochondria, anastasis, ROS, and ferroptosis is vital in oncology, potentially revolutionizing personalized cancer treatment and drug development.

Nanodrugs based on co-delivery strategies to combat cisplatin resistance

Cisplatin (CDDP), as a broad-spectrum anticancer drug, is able to bind to DNA and inhibit cell division. Despite the widespread use of cisplatin since its discovery, cisplatin resistance developed during prolonged chemotherapy, similar to other small molecule chemotherapeutic agents, severely limits its clinical application. Cisplatin resistance in cancer cells is mainly caused by three reasons: DNA repair, decreased cisplatin uptake/increased efflux, and cisplatin inactivation. In earlier combination therapies, the emergence of multidrug resistance (MDR) in cancer cells prevented the achievement of the desired therapeutic effect even with the accurate combination of two chemotherapeutic drugs. Therefore, combination therapy using nanocarriers for co-delivery of drugs is considered to be ideal for alleviating cisplatin resistance and reducing cisplatin-related toxicity in cancer cells. This article provides an overview of the design of cisplatin nano-drugs used to combat cancer cell resistance, elucidates the mechanisms of action of cisplatin and the pathways through which cancer cells develop resistance, and finally discusses the design of drugs and related carriers that can synergistically reduce cancer resistance when combined with cisplatin.

Exploring Amino Acid Transporters as Therapeutic Targets for Cancer: An Examination of Inhibitor Structures, Selectivity Issues, and Discovery Approaches

Amino acid transporters are abundant amongst the solute carrier family and have an important role in facilitating the transfer of amino acids across cell membranes. Because of their impact on cell nutrient distribution, they also appear to have an important role in the growth and development of cancer. Naturally, this has made amino acid transporters a novel target of interest for the development of new anticancer drugs. Many attempts have been made to develop inhibitors of amino acid transporters to slow down cancer cell growth, and some have even reached clinical trials. The purpose of this review is to help organize the available information on the efforts to discover amino acid transporter inhibitors by focusing on the amino acid transporters ASCT2 (SLC1A5), LAT1 (SLC7A5), xCT (SLC7A11), SNAT1 (SLC38A1), SNAT2 (SLC38A2), and PAT1 (SLC36A1). We discuss the function of the transporters, their implication in cancer, their known inhibitors, issues regarding selective inhibitors, and the efforts and strategies of discovering inhibitors. The goal is to encourage researchers to continue the search and development within the field of cancer treatment research targeting amino acid transporters.

Modulating ferroptosis sensitivity: environmental and cellular targets within the tumor microenvironment

Ferroptosis, a novel form of cell death triggered by iron-dependent phospholipid peroxidation, presents significant therapeutic potential across diverse cancer types. Central to cellular metabolism, the metabolic pathways associated with ferroptosis are discernible in both cancerous and immune cells. This review begins by delving into the intricate reciprocal regulation of ferroptosis between cancer and immune cells. It subsequently details how factors within the tumor microenvironment (TME) such as nutrient scarcity, hypoxia, and cellular density modulate ferroptosis sensitivity. We conclude by offering a comprehensive examination of distinct immunophenotypes and environmental and metabolic targets geared towards enhancing ferroptosis responsiveness within the TME. In sum, tailoring precise ferroptosis interventions and combination strategies to suit the unique TME of specific cancers may herald improved patient outcomes.

m6A epitranscriptome analysis reveals differentially methylated transcripts that drive early chemoresistance in bladder cancer

N 6-Methyladenosine (m6A) RNA modifications dynamically regulate messenger RNA processing, differentiation and cell fate. Given these functions, we hypothesized that m6A modifications play a role in the transition to chemoresistance. To test this, we took an agnostic discovery approach anchored directly to chemoresistance rather than to any particular m6A effector protein. Specifically, we used methyl-RNA immunoprecipitation followed by sequencing (MeRIP-seq) in parallel with RNA sequencing to identify gene transcripts that were both differentially methylated and differentially expressed between cisplatin-sensitive and cisplatin-resistant bladder cancer (BC) cells. We filtered and prioritized these genes using clinical and functional database tools, and then validated several of the top candidates via targeted quantitative polymerase chain reaction (qPCR) and MeRIP-PCR. In cisplatin-resistant cells, SLC7A11 transcripts had decreased methylation associated with decreased m6A reader YTHDF3 binding, prolonged RNA stability, and increased RNA and protein levels, leading to reduced ferroptosis and increased survival. Consistent with this, cisplatin-sensitive BC cell lines and patient-derived organoids exposed to cisplatin for as little as 48 h exhibited similar mechanisms of SLC7A11 upregulation and chemoresistance, trends that were also reflected in public cancer survival databases. Collectively, these findings highlight epitranscriptomic plasticity as a mechanism of rapid chemoresistance and a potential therapeutic target.

Exploring the role of the disulfidptosis-related gene SLC7A11 in adrenocortical carcinoma: implications for prognosis, immune infiltration, and therapeutic strategies

BACKGROUND

Disulfidptosis and the disulfidptosis-related gene SLC7A11 have recently attracted significant attention for their role in tumorigenesis and tumour management. However, its association with adrenocortical carcinoma (ACC) is rarely discussed.

METHODS

Differential analysis, Cox regression analysis, and survival analysis were used to screen for the hub gene SLC7A11 in the TCGA and GTEx databases and disulfidptosis-related gene sets. Then, we performed an association analysis between SLC7A11 and clinically relevant factors in ACC patients. Univariate and multivariate Cox regression analyses were performed to evaluate the prognostic value of SLC7A11 and clinically relevant factors. Weighted gene coexpression analysis was used to find genes associated with SLC7A11. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses and the LinkedOmics database were used to analyse the functions of SLC7A11-associated genes. The CIBERSORT and Xcell algorithms were used to analyse the relationship between SLC7A11 and immune cell infiltration in ACC. The TISIDB database was applied to search for the correlation between SLC7A11 expression and immune chemokines. In addition, we performed a correlation analysis for SLC7A11 expression and tumour mutational burden and immune checkpoint-related genes and assessed drug sensitivity based on SLC7A11 expression. Immunohistochemistry and RT‒qPCR were used to validate the upregulation of SLC7A11 in the ACC.

RESULTS

SLC7A11 is highly expressed in multiple urological tumours, including ACC. SLC7A11 expression is strongly associated with clinically relevant factors (M-stage and MYL6 expression) in ACC. SLC7A11 and the constructed nomogram can accurately predict ACC patient outcomes. The functions of SLC7A11 and its closely related genes are tightly associated with the occurrence of disulfidptosis in ACC. SLC7A11 expression was tightly associated with various immune cell infiltration disorders in the ACC tumour microenvironment (TME). It was positively correlated with the expression of immune chemokines (CXCL8, CXCL3, and CCL20) and negatively correlated with the expression of immune chemokines (CXCL17 and CCL14). SLC7A11 expression was positively associated with the expression of immune checkpoint genes (NRP1, TNFSF4, TNFRSF9, and CD276) and tumour mutation burden. The expression level of SLC7A11 in ACC patients is closely associated withcthe drug sensitivity.

CONCLUSION

In ACC, high expression of SLC7A11 is associated with migration, invasion, drug sensitivity, immune infiltration disorders, and poor prognosis, and its induction of disulfidptosis is a promising target for the treatment of ACC.

Nanoparticle-Mediated Delivery of Satraplatin to Overcome Cisplatin Drug Resistance

Drug resistance and cancer metastasis are the major obstacles for widely used platinum-based chemotherapy. It is acknowledgement that the decreasing intracellular accumulation of anticancer drugs and increasing sulfur-binding detoxification are two major mechanisms related to drug resistance. Herein, we developed a practical and straightforward method for formulating the clinically used anticancer drug satraplatin (JM-216) with D-α-tocopheryl polyethylene glycol succinate (TPGS)-based polymers to create satraplatin-loaded nanoparticles (SatPt-NPs). The experimental results demonstrate that SatPt-NPs exhibited comparable efficacy to A2780 in treating the A2780 cisplatin-resistant ovarian cancer cell line (A2780DDP), indicating their significant potential in overcoming drug resistance. Additionally, buthionine sulfoximine (BSO) is capable of depleting intracellular glutathione (GSH), resulting in reduced detoxification. After BSO treatment, the IC₅₀ value of SatPt-NPs changed from 0.178 to 0.133 μM, which remained relatively unchanged compared to cisplatin. This suggests that SatPt-NPs can overcome drug resistance by evading GSH detoxification. Therefore, SatPt-NPs have the ability to inhibit drug resistance in tumor cells and hold tremendous potential in cancer treatment.

miR-509-5p promotes colorectal cancer cell ferroptosis by targeting SLC7A11

BACKGROUND/AIM

Colorectal cancer (CRC), is characterized by aberrant microRNA (miRNA) expression during their development and progression. Recently, miR-509-5p's role as a regulator of several malignancies has been highlighted. Its function in CRC, however, is exposed. This research aimed to determine the relative abundance of miR-509-5p and its biological function in colorectal cancer.

METHODS

The expression of miR-509-5p in CRC cell lines and tissues, as well as neighboring normal tissues, was evaluated using real-time quantitative polymerase chain reaction (RT-PCR). 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyl-2 H-tetrazolium bromide (MTT) was used to assess cell viability. The association between miR-509-5p and its predicted target in CRC cells was analyzed using bioinformatics tools. The levels of Solute carrier family seven number 11 (SLC7A11) were assessed using enzyme-linked immunosorbent assay (ELISA), while malondialdehyde (MDA) and iron content levels were determined colorimetrically.

RESULTS

Compared to adjacent normal tissue and normal colorectal cell, there was a significant reduction in miR-509-5p expression in both CRC tissues and cells. miR-509-5p upregulation inhibited Caco-2 cell viability. SLC7A11 was predicted to be the cellular target of miR-509-5p. Interestingly, miR-509-5p's overexpression suppressed both mRNA and protein levels of SLC7A11, whereas its downregulation boosted SLC7A11 gene expression. Finally, overexpressing miR-509-5p resulted in increased MDA and iron levels.

CONCLUSION

Our results demonstrate that miR-509-5p has CRC tumor suppressor functions through controlling the expression of SLC7A11 and promotion of ferroptosis providing a new therapeutic target for the treatment of CRC.

Ferroptosis-modulating small molecules for targeting drug-resistant cancer: Challenges and opportunities in manipulating redox signaling

Ferroptosis is an iron-dependent cell death program that is characterized by excessive lipid peroxidation. Triggering ferroptosis has been proposed as a promising strategy to fight cancer and overcome drug resistance in antitumor therapy. Understanding the molecular interactions and structural features of ferroptosis-inducing compounds might therefore open the door to efficient pharmacological strategies against aggressive, metastatic, and therapy-resistant cancer. We here summarize the molecular mechanisms and structural requirements of ferroptosis-inducing small molecules that target central players in ferroptosis. Focus is placed on (i) glutathione peroxidase (GPX) 4, the only GPX isoenzyme that detoxifies complex membrane-bound lipid hydroperoxides, (ii) the cystine/glutamate antiporter system Xc - that is central for glutathione regeneration, (iii) the redox-protective transcription factor nuclear factor erythroid 2-related factor (NRF2), and (iv) GPX4 repression in combination with induced heme degradation via heme oxygenase-1. We deduce common features for efficient ferroptotic activity and highlight challenges in drug development. Moreover, we critically discuss the potential of natural products as ferroptosis-inducing lead structures and provide a comprehensive overview of structurally diverse biogenic and bioinspired small molecules that trigger ferroptosis via iron oxidation, inhibition of the thioredoxin/thioredoxin reductase system or less defined modes of action.

Lipid metabolism alterations and ferroptosis in cancer: Paving the way for solving cancer resistance

Cancer often perturbs lipid metabolism, which leads to the alteration of metabolism intermediates, contributing to their deregulated growth and metastasis. Alteration of lipid metabolism shifting to contain more polyunsaturated fatty acids (PUFAs) in membrane phospholipids (PLs) also leads to cancer therapy resistance. High amounts of PL-PUFAs render cancer cells more vulnerable to lipid peroxidation (LPO), predisposing them towards ferroptosis, a new form of iron-dependent oxidative regulated cell death. The commitment of cancer undergoing ferroptotic cell death depends on the adaptive lipidome remodeling, LPO patterns, and LPO scavenging ability in heterogeneous cancer cells. Ferroptosis is receiving attention in cancer research as treating cancers, altering membrane lipid homeostasis, and refractory from conventional therapies. Therefore, a better understanding of the molecular underpinning of lipid metabolism alterations may provide new opportunities for solving cancer resistance. This review intends to understand altered lipid metabolism in cancers and discuss lipid composition and metabolic processes associated with ferroptosis induction in cancers.

Erk1/2-Dependent HNSCC Cell Susceptibility to Erastin-Induced Ferroptosis

Unfavorable clinical outcomes mean that cancer researchers must attempt to develop novel therapeutic strategies to overcome therapeutic resistance in patients with HNSCC. Recently, ferroptosis was shown to be a promising pathway possessing druggable targets, such as xCT (SLC7A11). Unfortunately, little is known about the molecular mechanisms underlying the susceptibility of HNSCC cells to ferroptosis. The goal of this study was to determine whether HNSCC cells with activated Erk1/2 are vulnerable to ferroptosis induction. Our results have shown that xCT (SLC7A11) was overexpressed in malignant tissues obtained from the patients with HNSCC, whereas normal mucosa demonstrated weak expression of the protein. In order to investigate the role of Erk1/2 in the decrease in cell viability caused by erastin, xCT-overexpressing FaDu and SCC25 HNSCC cells were used. The ravoxertinib-dependent inhibition of Erk1/2 signaling led to the decrease in erastin efficacy due to the effect on ROS production and the upregulation of ROS scavengers SOD1 and SOD2, resulting in repressed lipid peroxidation. Therefore, it was concluded that the erastin-dependent activation of ferroptosis seems to be a promising approach which can be further developed as an additional strategy for the treatment of HNSCC. As ferroptosis induction via erastin is strongly dependent on the expression of Erk1/2, this MAP kinase can be considered as a predictor for cancer cells' response to erastin.

Ferroptosis induction via targeting metabolic alterations in head and neck cancer

Ferroptosis is a newly regulated cell death induced by the accumulation of iron-mediated lipid peroxidation. The alteration of cancer metabolism may contribute to proliferation, metastasis, and treatment resistance in human cancers, implicating the sensitivity to ferroptosis induction. Altered metabolism in cancer cells regulates oxidative stresses and changes metabolism intermediates, contributing to their deregulated growth and proliferation. Cancer metabolic changes toward the elevation of cellular free iron and polyunsaturated fatty acids sensitize cancer cells to lipid peroxidation toxicity tightly linked to ferroptosis. The altered metabolism in cancers can be served as a promising target to reverse cancer therapeutic resistance by ferroptosis induction to selectively kill cancer cells while sparing normal cells. The role of mitochondria and lipid metabolism in inducing ferroptosis in head and neck cancer (HNC) has been elucidated in previous studies. Ferroptosis is receiving attention in cancer research as treating cancers altering cellular metabolism and refractory from conventional therapies. More in-depth studies are needed to develop highly therapeutic drugs and practical methods to induce ferroptosis in diverse cancer cells and tumor microenvironments effectively. Therefore, this review intends to understand the altered metabolism and find new therapeutic possibilities using ferroptosis in HNC.

El-Tohamy M, A. Alhwaiti S. Advanced polymeric metal/metal oxide bionanocomposite using seaweed Laurencia dendroidea extract for antiprotozoal, anticancer, and photocatalytic applications

Background

Biosynthesized nanoparticles are gaining popularity due to their distinctive biological applications as well as bioactive secondary metabolites from natural products that contribute in green synthesis.

Methodology

This study reports a facile, ecofriendly, reliable, and cost-effective synthesis of silver nanoparticles (AgNPs), copper oxide nanoparticles (CuONPs), and polymeric PVP-silver-copper oxide nanocomposite using ethanol extract of seaweed Laurencia dendroidea and were evaluated for antiprotozoal, anticancer and photocatalytic potential. The nanostructures of the AgNPs, CuONPs, and polymeric PVP-Ag-CuO nanocomposite were confirmed by different spectroscopic and microscopic procedures.

Results

The UV-vis spectrum displayed distinct absorption peaks at 440, 350, and 470 nm for AgNPs, CuONPs, and polymeric Ag-CuO nanocomposite, respectively. The average particles size of the formed AgNPs, CuONPs, and Ag-CuO nanocomposite was 25, 28, and 30 nm, respectively with zeta potential values -31.7 ± 0.6 mV, -17.6 ± 4.2 mV, and -22.9 ± 4.45 mV. The microscopic investigation of biosynthesized nanomaterials revealed a spherical morphological shape with average crystallite sizes of 17.56 nm (AgNPs), 18.21 nm (CuONPs), and 25.46 nm (PVP-Ag-CuO nanocomposite). The antiprotozoal potential of green synthesized nanomaterials was examined against Leishmania amazonensis and Trypanosoma cruzi parasites. The polymeric PVP-Ag-CuO nanocomposite exerted the highest antiprotozoal effect with IC₅₀ values of 17.32 ± 1.5 and 17.48 ± 4.2 µM, in contrast to AgNPs and CuONPs. The anticancer potential of AgNPs, CuONPs, and polymeric PVP-Ag-CuO nanocomposite against HepG2 cancer cell lines revealed that all the nanomaterials were effective and the highest anticancer potential was displayed by PVP-Ag-CuO nanocomposite with IC₅₀ values 91.34 µg mL^-1 at 200 µg mL^-1 concentration. Additionally, PVP-Ag-CuO nanocomposite showed strong photocatalytic effect.

Conclusion

Overall, this study suggested that the biogenic synthesized nanomaterials AgNPs, CuONPs, and polymeric PVP-Ag-CuO nanocomposite using ethanol extract of seaweed L. dendroidea possesses promising antiprotozoal anticancer and photocatalytic effect and could be further exploited for the development of antiprotozoal and anticancer therapeutics agents.

Is depression the missing link between inflammatory mediators and cancer?

Patients with cancer are at greater risk of developing depression in comparison to the general population and this is associated with serious adverse effects, such as poorer quality of life, worse prognosis and higher mortality. Although the relationship between depression and cancer is now well established, a common underlying pathophysiological mechanism between the two conditions is yet to be elucidated. Existing theories of depression, based on monoamine neurotransmitter system dysfunction, are insufficient as explanations of the disorder. Recent advances have implicated neuroinflammatory mechanisms in the etiology of depression and it has been demonstrated that inflammation at a peripheral level may be mirrored centrally in astrocytes and microglia serving to promote chronic levels of inflammation in the brain. Three major routes to depression in cancer in which proinflammatory mediators are implicated, seem likely. Activation of the kynurenine pathway involving cytokines, increases tryptophan catabolism, resulting in diminished levels of serotonin which is widely acknowledged as being the hallmark of depression. It also results in neurotoxic effects on brain regions thought to be involved in the evolution of major depression. Proinflammatory mediators also play a crucial role in impairing regulatory glucocorticoid mediated feedback of the hypothalamic-pituitary-adrenal axis, which is activated by stress and considered to be involved in both depression and cancer. The third route is via the glutamatergic pathway, whereby glutamate excitotoxicity may lead to depression associated with cancer. A better understanding of the mechanisms underlying these dysregulated and other newly emerging pathways may provide a rationale for therapeutic targeting, serving to improve the care of cancer patients.

Expression of CD98hc in Pancreatic Cancer and Its Role in Cancer Cell Behavior

Background: Cluster of differentiation 98 heavy chain (CD98hc) is a transmembrane protein, which functions both as a coreceptor of ß-integrins, enhancing intracellular integrin-dependent downstream signaling, and as a transporter of branched-chain and aromatic amino acids. As such, it is pivotal in cell cycle regulation and protection of oxidative, nutritional and DNA replication stress. Overexpression of CD98hc occurs widely in cancer cells and is associated with poor clinical prognosis. The role of CD98hc in pancreatic cancer remains to be elucidated. The aim of this study was to determine the expression of CD98hc in pancreatic ductal adenocarcinoma and to define its potential functional role in cancer cell biology.

Methods: Immunohistochemical staining for CD98hc was performed on 222 tissue samples of patients with pancreatic ductal adenocarcinoma. The pancreatic cancer cell lines PANC-1 and BxPC-3 were used to determine the effect of CD98hc expression on cancer cell behavior using cell adhesion, cell trans-migration and cell spreading assays. Flow cytometry was performed to study the rate of apoptosis after detachment or serum starvation. shRNA-lentiviral constructs were used to knock down or reconstitute full length or mutated CD98hc.

Results: Up to 20% of pancreatic ductal adenocarcinomas express CD98hc in the acinar cells (13%) and islet cells (20%) embedded in tumor tissue. Although expression of CD98hc in tumor tissue was not associated with a particular tumor stage or grade, our data show a trend towards longer overall survival of pancreatic cancer patients without CD98hc expression as compared to those with immunohistochemical positivity. In vitro downregulation of CD98hc in the pancreatic cancer cell lines PANC-1 and BxPC-3 significantly inhibits cell proliferation (p<0.05), self-renewal (p<0.05) and anchorage-independent growth (p<0.05).

Conclusion: CD98hc is expressed in a remarkable percentage of pancreatic ductal adenocarcinomas. Due to its important role in cell behavior and malignant cell transformation, it may be a promising molecular target for potential new therapeutic approaches in pancreatic cancer in the future.

Radiotracers for Nuclear Imaging of Reactive Oxygen Species: Advances Made So Far

Reactive oxygen species (ROS) are a cluster of highly reactive and short-lived oxygen-containing molecules that lead to metabolic disorders where production exceeds catabolism in an organism. Many specific radiotracers for positron/single-photon emission tomography have been developed to reveal the discrepancy of ROS levels in normal and damaged tissues and further clarify the relationship between ROS and diseases. This review summarizes the advances achieved for the development of ROS radiotracers to date. The structure design, radiosynthesis, and imaging performance of existing radiotracers are discussed with the individual ROS-response mechanisms highlighted.

A xCT role in tumour-associated ferroptosis shed light on novel therapeutic options

Solute carrier family 7 member 11 (SLC7A11; also known as xCT), a key component of the cystine/glutamate antiporter, is essential for the maintenance of cellular redox status and the regulation of tumor-associated ferroptosis. Accumulating evidence has demonstrated that xCT overexpression, resulting from different oncogenic and tumor suppressor signaling, promotes tumor progression and multidrug resistance partially via suppressing ferroptosis. In addition, recent studies have highlighted the role of xCT in regulating the metabolic flexibility in cancer cells. In this review, the xCT activities in intracellular redox balance and in ferroptotic cell death have been summarized. Moreover, the role of xCT in promoting tumor development, drug resistance, and nutrient dependency in cancer cells has been explored. Finally, different therapeutic strategies, xCT-based, for anti-cancer treatments have been discussed.

Glutamatergic system components as potential biomarkers and therapeutic targets in cancer in non-neural organs

Glutamate is one of the most abundant amino acids in the blood. Besides its role as a neurotransmitter in the brain, it is a key substrate in several metabolic pathways and a primary messenger that acts through its receptors outside the central nervous system (CNS). The two main types of glutamate receptors, ionotropic and metabotropic, are well characterized in CNS and have been recently analyzed for their roles in non-neural organs. Glutamate receptor expression may be particularly important for tumor growth in organs with high concentrations of glutamate and might also influence the propensity of such tumors to set metastases in glutamate-rich organs, such as the liver. The study of glutamate transporters has also acquired relevance in the physiology and pathologies outside the CNS, especially in the field of cancer research. In this review, we address the recent findings about the expression of glutamatergic system components, such as receptors and transporters, their role in the physiology and pathology of cancer in non-neural organs, and their possible use as biomarkers and therapeutic targets.

Targeting multidrug resistance-associated protein 1 (MRP1)-expressing cancers: Beyond pharmacological inhibition

Resistance to chemotherapy remains one of the most significant obstacles to successful cancer treatment. While inhibiting drug efflux mediated by ATP-binding cassette (ABC) transporters is a seemingly attractive and logical approach to combat multidrug resistance (MDR), small molecule inhibition of ABC transporters has so far failed to confer clinical benefit, despite considerable efforts by medicinal chemists, biologists, and clinicians. The long-sought treatment to eradicate cancers displaying ABC transporter overexpression may therefore lie within alternative targeting strategies. When aberrantly expressed, the ABC transporter multidrug resistance-associated protein 1 (MRP1, ABCC1) confers MDR, but can also shift cellular redox balance, leaving the cell vulnerable to select agents. Here, we explore the physiological roles of MRP1, the rational for targeting this transporter in cancer, the development of small molecule MRP1 inhibitors, and the most recent developments in alternative therapeutic approaches for targeting cancers with MRP1 overexpression. We discuss approaches that extend beyond simple MRP1 inhibition by exploiting the collateral sensitivity to glutathione depletion and ferroptosis, the rationale for targeting the shared transcriptional regulators of both MRP1 and glutathione biosynthesis, advances in gene silencing, and new molecules that modulate transporter activity to the detriment of the cancer cell. These strategies illustrate promising new approaches to address multidrug resistant disease that extend beyond the simple reversal of MDR and offer exciting routes for further research.

NADPH debt drives redox bankruptcy: SLC7A11/xCT-mediated cystine uptake as a double-edged sword in cellular redox regulation

Cystine/glutamate antiporter solute carrier family 7 member 11 (SLC7A11; also known as xCT) plays a key role in antioxidant defense by mediating cystine uptake, promoting glutathione synthesis, and maintaining cell survival under oxidative stress conditions. Recent studies showed that, to prevent toxic buildup of highly insoluble cystine inside cells, cancer cells with high expression of SLC7A11 (SLC7A11^high) are forced to quickly reduce cystine to more soluble cysteine, which requires substantial NADPH supply from the glucose-pentose phosphate pathway (PPP) route, thereby inducing glucose- and PPP-dependency in SLC7A11^high cancer cells. Limiting glucose supply to SLC7A11^high cancer cells results in significant NADPH “debt”, redox “bankruptcy”, and subsequent cell death. This review summarizes our current understanding of NADPH-generating and -consuming pathways, discusses the opposing role of SLC7A11 in protecting cells from oxidative stress–induced cell death such as ferroptosis but promoting glucose starvation–induced cell death, and proposes the concept that SLC7A11-mediated cystine uptake acts as a double-edged sword in cellular redox regulation. A detailed understanding of SLC7A11 in redox biology may identify metabolic vulnerabilities in SLC7A11^high cancer for therapeutic targeting.

GADD45α alleviates the CDDP resistance of SK-OV3/cddp cells via redox-mediated DNA damage

Epithelial ovarian cancer has the highest mortality rate of all malignant ovarian cancer types. Great progress has been made in the treatment of ovarian cancer in recent years. However, drug resistance has led to a low level of 5-year survival rate of epithelial ovarian cancer, and the molecular mechanism of which remains unknown. The aim of the present study was to identify the role of redox status in the cisplatin (CDDP) resistance of ovarian cancer. CDDP-resistant SK-OV3 (SK-OV3/cddp) cells were prepared and their reactive oxygen species and glutathione levels were investigated. The effects of hydrogen peroxide on the CDDP sensitivity of the SK-OV3/cddp cells and their expression levels of the redox-associated protein growth arrest and DNA damage 45a (GADD45α) were also investigated. In addition, the impact of GADD45α overexpression on cell viability was evaluated in vitro and in vivo, and the levels of Ser-139 phosphorylated H2A histone family member X (γ-H2AX), which is associated with DNA damage, were detected. The results suggested that redox status affected the drug resistance of the ovarian cancer cells by increasing the expression of GADD45α. The overexpression of GADD45α reversed the CDDP resistance of the SK-OV3/cddp cells and increased the level of γ-H2AX. In conclusion, GADD45α alleviated the CDDP resistance of SK-OV3/cddp cells via the induction of redox-mediated DNA damage.

SLC7A11 regulated by NRF2 modulates esophageal squamous cell carcinoma radiosensitivity by inhibiting ferroptosis

BACKGROUND

Solute carrier family 7 member 11(SLC7A11) is a component of cysteine/glutamate transporter, which plays a key role in tumor growth; however, its underlying effect on radiosensitivity in esophageal squamous cell carcinoma (ESCC) remains unclear. This study aimed to clarify SLC7A11's expression and correlation with nuclear expression of nuclear factor erythroid-2 (NRF2)-associated radioresistance in ESCC.

METHODS

We included 127 ESCC patients who received radical chemoradiotherapy. Immunohistochemical staining was used to detect SLC7A11 and NRF2 nuclear expression, and the relationship between clinicopathological characteristics and survival rates or therapy response were evaluated. Western blot, dual-reporter assays and Chromatin immunoprecipitation (ChIP)-sequencing were used to analyze their relationship in vitro. Their roles in radioresistance were then investigated through multiple validation steps.

RESULTS

NRF2 nuclear expression and SLC7A11 expression were overexpressed in ESCC tissues and were positively correlated with one another. NRF2 nuclear expression was significantly associated with tumor length, lymph node metastasis, and TNM stage, while SLC7A11 expression was associated with lymph node metastasis. Patients with high NRF2 nuclear expression and SLC7A11 expression had significantly shorter overall and progression-free survival, and poor treatment response. The multivariate model showed that NRF2 nuclear expression and SLC7A11 expression, sex and tumor location are independent prognostic factors. In vitro analysis confirmed that hyperactivation of NRF2 induced SLC7A11 expression by directly binding to its promoter region, promoting radioresistance, reducing radiotherapy-induced lipid peroxidation levels, PTGS2 expression, and radiotherapy-related ferroptosis morphologic features.

CONCLUSION

Our study reveals a connection between high SLC7A11 expression and NRF2 nuclear expression in patients with ESCC that was related to worse survival and poorer therapy outcomes. SLC7A11-mediated ferroptosis inhibition induced NRF2-associated radioresistance, highlighting potential of NRF2/SLC7A11/ferroptosis axis as future therapeutic targets against therapy resistance biomarker.

Engineering nanomedicine for glutathione depletion-augmented cancer therapy

Glutathione (GSH), the main redox buffer, has long been recognized as a pivotal modulator of tumor initiation, progression and metastasis. It is also implicated in the resistance of platinum-based chemotherapy and radiation therapy. Therefore, depleting intracellular GSH was considered a potent solution to combating cancer. However, reducing GSH within cancer cells alone always failed to yield desirable therapeutic effects. In this regard, the convergence of GSH-scavenging agents with therapeutic drugs has thus been pursued in clinical practice. Unfortunately, the therapeutic outcomes are still unsatisfactory due to untargeted drug delivery. Advanced nanomedicine of synergistic GSH depletion and cancer treatment has attracted tremendous interest because they promise to deliver superior therapeutic benefits while alleviating life-threatening side effects. In the past five years, the authors and others have demonstrated that numerous nanomedicines, by simultaneously delivering GSH-depleting agents and therapeutic components, boost not only traditional chemotherapy and radiotherapy but also multifarious emerging treatment modalities, including photodynamic therapy, sonodynamic therapy, chemodynamic therapy, ferroptosis, and immunotherapy, to name a few, and achieved decent treatment outcomes in a large number of rodent tumor models. In this review, we summarize the most recent progress in engineering nanomedicine for GSH depletion-enhanced cancer therapies. Biosynthesis of GSH and various types of GSH-consuming strategies will be briefly introduced. The challenges and perspectives of leveraging nanomedicine for GSH consumption-augmented cancer therapies will be discussed at the end.

Cysteine Boosts Fitness Under Hypoxia-Mimicked Conditions in Ovarian Cancer by Metabolic Reprogramming

Among gynecologic malignancies, ovarian cancer is the third most prevalent and the most common cause of death, especially due to diagnosis at an advanced stage together with resistance to therapy. As a solid tumor grows, cancer cells in the microenvironment are exposed to regions of hypoxia, a selective pressure prompting tumor progression and chemoresistance. We have previously shown that cysteine contributes to the adaptation to this hypoxic microenvironment, but the mechanisms by which cysteine protects ovarian cancer cells from hypoxia-induced death are still to be unveiled. Herein, we hypothesized that cysteine contribution relies on cellular metabolism reprogramming and energy production, being cysteine itself a metabolic source. Our results strongly supported a role of xCT symporter in energy production that requires cysteine metabolism instead of hydrogen sulfide (H2S) per se. Cysteine degradation depends on the action of the H2S-synthesizing enzymes cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE), and/or 3-mercaptopyruvate sulfurtransferase (MpST; together with cysteine aminotransferase, CAT). In normoxia, CBS and CSE inhibition had a mild impact on cysteine-sustained ATP production, pointing out the relevance of CAT + MpST pathway. However, in hypoxia, the concomitant inhibition of CBS and CSE had a stronger impact on ATP synthesis, thus also supporting a role of their hydrogen sulfide and/or cysteine persulfide-synthesizing activity in this stressful condition. However, the relative contributions of each of these enzymes (CBS/CSE/MpST) on cysteine-derived ATP synthesis under hypoxia remains unclear, due to the lack of specific inhibitors. Strikingly, NMR analysis strongly supported a role of cysteine in the whole cellular metabolism rewiring under hypoxia. Additionally, the use of cysteine to supply biosynthesis and bioenergetics was reinforced, bringing cysteine to the plateau of a main carbon sources in cancer. Collectively, this work supports that sulfur and carbon metabolism reprogramming underlies the adaptation to hypoxic microenvironment promoted by cysteine in ovarian cancer.

Ferroptosis: A Trusted Ally in Combating Drug Resistance in Cancer

Ferroptosis, which is an iron-dependent, non-apoptotic cell death mechanism, has recently been proposed as a novel approach in cancer treatment. Bearing distinctive features and its exclusive mechanism have put forward the potential therapeutic benefit of triggering this newly discovered form of cell death. Numerous studies have indicated that apoptotic pathways are often deactivated in resistant cells, leading to a failure in therapy. Hence, alternative strategies to promote cell death are required. Mounting evidence suggests that drug-resistant cancer cells are particularly sensitive to ferroptosis. Given that cancer cells consume a higher amount of iron than healthy ones, ferroptosis not only stands as an excellent alternative to trigger cell death and reverse drug-resistance, but also provides selectivity in therapy. This review focuses specifically on overcoming drug-resistance in cancer through activating ferroptotic pathways and brings together the relevant chemotherapeutics-based and nanotherapeutics-based studies to offer a perspective for researchers regarding the potential use of this mechanism in developing novel therapeutic strategies.

Characterization of a hyaluronic acid and folic acid-based hydrogel for cisplatin delivery: Antineoplastic effect in human ovarian cancer cells in vitro

We successfully prepared and characterized a hyaluronic acid- and folic acid-based hydrogel for the delivery of cisplatin (GEL-CIS) with the aim to induce specific and efficient incorporation of CIS into ovarian cancer (OC) cells, improve its antineoplastic effect and avoid CIS-resistance. The slow and controlled release of the drug from the polymeric network and its swelling degree at physiologic pH suggested its suitability for CIS delivery in OC. We compared here the effects of pure CIS to that of GEL-CIS on human OC cell lines, either wild type or CIS-resistant, in basal conditions and in the presence of macrophage-derived conditioned medium, mimicking the action of tumor-associated macrophages in vivo. GEL-CIS inhibited OC cell growth and migration more efficiently than pure CIS and modulated the expression of proteins involved in the Epithelial Mesenchymal Transition, a process playing a key role in OC metastatic spread and resistance to CIS.

Metabolic and Amino Acid Alterations of the Tumor Microenvironment

Metabolic changes driven by the hostile tumor microenvironment surrounding cancer cells and the effect of these changes on tumorigenesis and metastatic potential have been known for a long time. The usual point of interest is glucose and changes in its utilization by cancer cells, mainly in the form of the Warburg effect. However, amino acids, both intra- and extracellular, also represent an important aspect of tumour microenvironment, which can have a significant effect on cancer cell metabolism and overall development of the tumor. Namely, alterations in the metabolism of amino acids glutamine, sarcosine, aspartate, methionine and cysteine have been previously connected to the tumor progression and aggressivity of cancer. The aim of this review is to pinpoint current gaps in our knowledge of the role of amino acids as a part of the tumor microenvironment and to show the effect of various amino acids on cancer cell metabolism and metastatic potential. This review shows limitations and exceptions from the traditionally accepted model of Warburg effect in some cancer tissues, with the emphasis on prostate cancer, because the traditional definition of Warburg effect as a metabolic switch to aerobic glycolysis does not always apply. Prostatic tissue both in a healthy and transformed state significantly differs in many metabolic aspects, including the metabolisms of glucose and amino acids, from the metabolism of other tissues. Findings from different tissues are, therefore, not always interchangeable and have to be taken into account during experimentation modifying the environment of tumor tissue by amino acid supplementation or depletion, which could potentially serve as a new therapeutic approach.

Control of Oxidative Stress in Cancer Chemoresistance: Spotlight on Nrf2 Role

Chemoresistance represents the main obstacle to cancer treatment with both conventional and targeted therapy. Beyond specific molecular alterations, which can lead to targeted therapy, metabolic remodeling, including the control of redox status, plays an important role in cancer cell survival following therapy. Although cancer cells generally have a high basal reactive oxygen species (ROS) level, which makes them more susceptible than normal cells to a further increase of ROS, chemoresistant cancer cells become highly adapted to intrinsic or drug-induced oxidative stress by upregulating their antioxidant systems. The antioxidant response is principally mediated by the transcription factor Nrf2, which has been considered the master regulator of antioxidant and cytoprotective genes. Nrf2 expression is often increased in several types of chemoresistant cancer cells, and its expression is mediated by diverse mechanisms. In addition to Nrf2, other transcription factors and transcriptional coactivators can participate to maintain the high antioxidant levels in chemo and radio-resistant cancer cells. The control of expression and function of these molecules has been recently deepened to identify which of these could be used as a new therapeutic target in the treatment of tumors resistant to conventional therapy. In this review, we report the more recent advances in the study of Nrf2 regulation in chemoresistant cancers and the role played by other transcription factors and transcriptional coactivators in the control of antioxidant responses in chemoresistant cancer cells.

Cysteine metabolic circuitries: druggable targets in cancer

To enable survival in adverse conditions, cancer cells undergo global metabolic adaptations. The amino acid cysteine actively contributes to cancer metabolic remodelling on three different levels: first, in its free form, in redox control, as a component of the antioxidant glutathione or its involvement in protein s-cysteinylation, a reversible post-translational modification; second, as a substrate for the production of hydrogen sulphide (H2S), which feeds the mitochondrial electron transfer chain and mediates per-sulphidation of ATPase and glycolytic enzymes, thereby stimulating cellular bioenergetics; and, finally, as a carbon source for epigenetic regulation, biomass production and energy production. This review will provide a systematic portrayal of the role of cysteine in cancer biology as a source of carbon and sulphur atoms, the pivotal role of cysteine in different metabolic pathways and the importance of H2S as an energetic substrate and signalling molecule. The different pools of cysteine in the cell and within the body, and their putative use as prognostic cancer markers will be also addressed. Finally, we will discuss the pharmacological means and potential of targeting cysteine metabolism for the treatment of cancer.

Microwave-Assisted Rapid Green Synthesis of Gold Nanoparticles Using Seed Extract of Trachyspermum ammi: ROS Mediated Biofilm Inhibition and Anticancer Activity

Green synthesis of metal nanoparticles using plant extracts as capping and reducing agents for the biomedical applications has received considerable attention. Moreover, emergence and spread of multidrug resistance among bacterial pathogens has become a major health concern and lookout for novel alternative effective drugs has gained momentum. In current study, we synthesized gold nanoparticles using the seed extract of Trachyspermum ammi (TA-AuNPs), assessed its efficacy against drug resistant biofilms of Listeria monocytogenes and Serratia marcescens, and evaluated its anticancer potential against HepG2 cancer cell lines. Microwave-assisted green synthesis of gold nanoparticles was carried out and characterization was done using UV-vis spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and dynamic light scattering (DLS). Most nanoparticles were observed as spherical and spheroidal with few anisotropies with an average crystalline size of 16.63 nm. Synthesized TA-AuNPs demonstrated significant biofilm inhibitory activity against L. monocytogenes (73%) as well as S. marcescens (81%). Exopolysaccharide (EPS), motility, and CSH, key elements that facilitate the formation and maintenance of biofilm were also inhibited significantly at the tested sub-minimum inhibitory concentrations (sub-MICs). Further, TA-AuNPs effectively obliterated preformed mature biofilms of S. marcescens and L. monocytogenes by 64% and 58%, respectively. Induction of intracellular ROS production in TA-AuNPs treated bacterial cells could be the plausible mechanism for the reduced biofilm formation in test pathogens. Administration of TA-AuNPs resulted in the arrest of cellular proliferation in a concentration-dependent manner. TA-AuNPs decrease the intracellular GSH in HepG2 cancer cell lines, cells become more prone to ROS generation, hence induce apoptosis. Thus, this work proposes a new eco-friendly and rapid approach for fabricating NPs which can be exploited for multifarious biomedical applications.

Nano-scale imaging of dual stable isotope labeled oxaliplatin in human colon cancer cells reveals the nucleolus as a putative node for therapeutic effect

Oxaliplatin shows a superior clinical activity in colorectal cancer compared to cisplatin. Nevertheless, the knowledge about its cellular distribution and the mechanisms responsible for the different range of oxaliplatin-responsive tumors is far from complete. In this study, we combined highly sensitive element specific and isotope selective imaging by nanometer-scale secondary ion mass spectrometry (NanoSIMS) with transmission electron microscopy to investigate the subcellular accumulation of oxaliplatin in three human colon cancer cell lines (SW480, HCT116 wt, HCT116 OxR). Oxaliplatin bearing dual stable isotope labeled moieties, i.e. ²H-labeled diaminocyclohexane (DACH) and ¹³C-labeled oxalate, were applied for comparative analysis of the subcellular distribution patterns of the central metal and the ligands. In all the investigated cell lines, oxaliplatin was found to have a pronounced tendency for cytoplasmic aggregation in single membrane bound organelles, presumably related to various stages of the endocytic pathway. Moreover, nuclear structures, heterochromatin and in particular nucleoli, were affected by platinum-drug exposure. In order to explore the consequences of oxaliplatin resistance, subcellular drug distribution patterns were investigated in a pair of isogenic malignant cell lines with distinct levels of drug sensitivity (HCT116 wt and HCT116 OxR, the latter with acquired resistance to oxaliplatin). The subcellular platinum distribution was found to be similar in both cell lines, with only slightly higher accumulation in the sensitive HCT116 wt cells which is inconsistent with the resistance factor of more than 20-fold. Instead, the isotopic analysis revealed a disproportionally high accumulation of the oxalate ligand in the resistant cell line.

Up-Regulation of circEIF6 Contributes to Pancreatic Cancer Development Through Targeting miR-557/SLC7A11/PI3K/AKT Signaling

BACKGROUND

Accruing evidences have pointed out that abnormal expression of circular RNAs (circRNAs) was closely related to the development of many malignancies. The present study intended to disclose the role of circRNA eukaryotic translation initiation factor 6 (circEIF6; hsa_circ_0060055) in pancreatic cancer progression.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to determine the expression of circEIF6, EIF6 messenger RNA (mRNA), microRNA-557 (miR-557) and solute carrier family 7 member 11 (SLC7A11) mRNA. Cell proliferation ability, migration and invasion abilities and apoptosis were evaluated by Cell Counting Kit 8 (CCK8) assay, transwell migration and invasion assays and flow cytometry. Western blot assay was performed for the expression determination of all proteins. The predicted interaction between miR-557 and circEIF6 or SLC7A11 was confirmed by dual-luciferase reporter assay. Xenograft tumor model was used for exploring the biological function of circEIF6 in vivo.

RESULTS

CircEIF6 abundance was aberrantly up-regulated in pancreatic tumor tissues and cell lines. Cell proliferation, migration and invasion were significantly restrained while cell apoptosis was induced with the silencing of circEIF6 in pancreatic cancer cells. CircEIF6 silencing also hampered the activation of phosphatidylinositol 3-kinase (PI3K)/AKT serine/threonine kinase (AKT) pathway. CircEIF6 bound to miR-557, and circEIF6 silencing elevated the expression of miR-557 in pancreatic cancer cells. MiR-557 knockdown partly overturned circEIF6 silencing-induced effects in pancreatic cancer cells. SLC7A11 was a target of miR-557, and miR-557 overexpression suppressed malignant potential of pancreatic cancer cells partly through reducing the expression of SLC7A11. CircEIF6 knockdown blocked xenograft tumor growth in vivo.

CONCLUSION

CircEIF6 aggravated pancreatic cancer development through promoting cell proliferation, migration and invasion and suppressing cell apoptosis through targeting miR-557/SLC7A11/PI3K/AKT signaling.

Screening and Identifying Cisplatin-Related Gene Mutations in Lung Squamous Cell Carcinoma

Introduction

Platinum-based chemotherapy is the cornerstone of treatment for patients with LUSC, but cisplatin resistance greatly restricts its clinical application. Therefore, it is particularly important to screen the predominant LUSC population using biomarkers.

Methods

Data for 15 LUSC cell lines were downloaded from the Genomics of Drug Sensitivity in Cancer (GDSC) Project database to screen for mutations related to cisplatin susceptibility. We conducted whole-exome sequencing (WES) of tumors from 58 LUSC patients from Sichuan Provincial People’s Hospital of University of Electronic Science and Technology. Subsequently, the clinical prognostic value of these mutations was verified by using The Cancer Genome Atlas (TCGA)-LUSC cohort and our cohort (n=58).

Results

Based on the cisplatin sensitivity data of GDSC-LUSC and survival analysis of TCGA-LUSC and Local-LUSC cohorts, we found that only mutation of IGF2R was associated with cisplatin sensitivity, better overall survival [OS; P=0.04, HR (95% CI): 0.42 (0.23–0.78)] and progression-free survival [PFS; P =0.016, HR (95% CI): 0.26 (0.12–0.59)]. However, there were no significant differences in the frequencies of gene mutations between the IGF2R-mutant (IGF2R-MT) and IGF2R-wild-type (IGF2R-WT) groups. Gene set enrichment analysis (GSEA) and single-sample GSEA (ssGSEA) indicated enhanced intracellular detoxification and decreased abnormal signaling activity to reverse cisplatin tolerance in the IGF2R-MT group.

Conclusion

The results suggest that IGF2R mutations are a potential biomarker for screening LUSC patients suitable for cisplatin treatment.

Ferroptosis: a new unexpected chance to treat metastatic melanoma?

Human skin melanoma is one of the most aggressive and difficult to treat human malignancies, with an increasing incidence over the years. While the resection of the early diagnosed primary tumor remains the best clinical approach, advanced/metastatic melanoma still remains with a poor prognosis. Indeed, although enormous progress in the therapeutic treatment of human tumors has been made in recent years, patients affected by metastatic melanoma are still poorly affected by these clinical advances. Therefore, new valuable therapeutic approaches are urgently needed, to design and define effective treatments to consistently increase the overall survival rate of patients affected by this malignancy. In this review we summarize the main signaling pathways studied to kill human skin melanoma, and introduce the ferroptotic cell death as a new pathway to be explored to eradicate this tumor.

Cystine transporter SLC7A11/xCT in cancer: ferroptosis, nutrient dependency, and cancer therapy

The cystine/glutamate antiporter SLC7A11 (also commonly known as xCT) functions to import cystine for glutathione biosynthesis and antioxidant defense and is overexpressed in multiple human cancers. Recent studies revealed that SLC7A11 overexpression promotes tumor growth partly through suppressing ferroptosis, a form of regulated cell death induced by excessive lipid peroxidation. However, cancer cells with high expression of SLC7A11 (SLC7A11^high) also have to endure the significant cost associated with SLC7A11-mediated metabolic reprogramming, leading to glucose- and glutamine-dependency in SLC7A11^high cancer cells, which presents potential metabolic vulnerabilities for therapeutic targeting in SLC7A11^high cancer. In this review, we summarize diverse regulatory mechanisms of SLC7A11 in cancer, discuss ferroptosis-dependent and -independent functions of SLC7A11 in promoting tumor development, explore the mechanistic basis of SLC7A11-induced nutrient dependency in cancer cells, and conceptualize therapeutic strategies to target SLC7A11 in cancer treatment. This review will provide the foundation for further understanding SLC7A11 in ferroptosis, nutrient dependency, and tumor biology and for developing novel effective cancer therapies.

xCT: A Critical Molecule That Links Cancer Metabolism to Redox Signaling

System x_c^- cystine/glutamate antiporter, composed of a light-chain subunit (xCT, SLC7A11) and a heavy-chain subunit (CD98hc, SLC3A2), is mainly responsible for the cellular uptake of cystine in exchange for intracellular glutamate. In recent years, the xCT molecule has been found to play an important role in tumor growth, progression, metastasis, and multidrug resistance in various types of cancer. Interestingly, xCT also exhibits an essential function in regulating tumor-associated ferroptosis. Despite significant progress in targeting the system x_c^- transporter in cancer treatment, the underlying mechanisms still remain elusive. It is also unclear why solid tumors are more sensitive to xCT inhibitors such as sulfasalazine, as compared to hematological malignancies. This review mainly focuses on the role of xCT cystine/glutamate transporter in regard to tumor growth, chemoresistance, tumor-selective ferroptosis, and the mechanisms regulating xCT gene expression. The potential therapeutic implications of targeting the system x_c^- and its combination with chemotherapeutic agents or immunotherapy to suppress tumor growth and overcome drug resistance are also discussed.

xCT inhibitor sulfasalazine depletes paclitaxel-resistant tumor cells through ferroptosis in uterine serous carcinoma

Glutathione (GSH) is a primary antioxidant that protects cells against reactive oxygen species (ROS), and high levels of GSH promote cancer cell survival and resistance to chemotherapy. The glutamine transporter xCT is essential for the intracellular synthesis of GSH, whereby xCT determines the intracellular redox balance. However, whether xCT inhibition can overcome GSH-mediated resistance to chemotherapeutic agents in uterine serous carcinoma (USC) remains unclear. Thus, the present study investigated the effect of the xCT inhibitor, sulfasalazine (SAS) on cytotoxicity in paclitaxel-sensitive and -resistant USC cell lines. The molecular mechanism by which SAS induces ferroptotic cell death in paclitaxel-resistant cells was assessed. The results of the cytotoxicity assay demonstrated that SAS was more cytotoxic in paclitaxel-resistant cells compared with in -sensitive cells; however, paclitaxel cytotoxicity was not enhanced in either of the USC cell lines. Immunoblotting analysis and the cell death assays performed using ferroptosis inhibitors indicated that SAS-mediated cell death was induced through ferroptosis, and not apoptosis, in paclitaxel-resistant cells. Furthermore, ROS production was increased in paclitaxel-resistant but not in -sensitive cells, even at low SAS concentration, and JNK was activated, which is a downstream target in the Ras signaling pathway. Knockdown of JNK reversed the inhibitory effect of SAS on cell proliferation and cell death. The synthetic lethal interaction between ROS accumulation and Ras effector JNK activation may be critical for enhancing the sensitivity to ferroptotic cell death mediated by xCT inhibitor, SAS. Taken together, the results of the present study suggest that xCT inhibition may be an effective treatment for patients with recurrent paclitaxel-resistant USC.

Cysteine as a Carbon Source, a Hot Spot in Cancer Cells Survival

Cancer cells undergo a metabolic rewiring in order to fulfill the energy and biomass requirements. Cysteine is a pivotal organic compound that contributes for cancer metabolic remodeling at three different levels: (1) in redox control, free or as a component of glutathione; (2) in ATP production, via hydrogen sulfide (H₂S) production, serving as a donor to electron transport chain (ETC), and (3) as a carbon source for biomass and energy production. In the present review, emphasis will be given to the role of cysteine as a carbon source, focusing on the metabolic reliance on cysteine, benefiting the metabolic fitness and survival of cancer cells. Therefore, the interplay between cysteine metabolism and other metabolic pathways, as well as the regulation of cysteine metabolism related enzymes and transporters, will be also addressed. Finally, the usefulness of cysteine metabolic route as a target in cancer treatment will be highlighted.

High-throughput screening suggests glutathione synthetase as an anti-tumor target of polydatin using human proteome chip

Polydatin (PD) is a bio-active ingredient with known anti-tumor effects. However, its specific protein targets yet have not been systematically screened, and the molecular anti-tumor mechanism is still unclear. Here, proteomic-chip was efficiently used to screen potential targets of PD. First, we investigated through animal experiment and proteomics studies, and found that polydatin play an important role in tumor cells. Then, the red-green fluorescent of polydatin was compared comprehensively to screen its targets on chip, followed by bioinformatics analysis. Glutathione synthetase (GSS) was selected as candidate research target. After a series of molecular biological experiments GSS was confirmed a target protein for PD in vitro. Moreover, we also found that PD can significantly inhibit the activity of GSS in vitro and live cells. Our findings reveal that PD could be a selective small-molecule GSS enzyme activity inhibitor and GSS could be a potential therapeutic target in cancer.

MiR-139-5p/SLC7A11 inhibits the proliferation, invasion and metastasis of pancreatic carcinoma via PI3K/Akt signaling pathway

OBJECTIVE

Pancreatic carcinoma (PANC) is one of the important aggressive cancers, with deficiency in effective therapeutics. The study aimed to investigate the effects and molecular mechanism of miR-139-5p/SLC7A11 on the proliferation and metastasis of PANC.

METHODS

Bioinformatics was used to analyze the differentially expressed genes in the TCGA database. PANC cell lines with overexpressed miR-139-5p and Solute Carrier Family 7, Member 11 (SLC7A11) was established, and have been used to detect cell proliferation, invasion and metastasis of PANC Subsequently, bioinformatic analysis and dual luciferase reporter assay were performed to confirm that SLC7A11 was a target gene of miR-139-5p. Xenograft mice model was used to explore the functions of miR-139-5p in PANC tumorigenicity.

RESULTS

MiR-139-5p could regulate and affect the protein expression of P13K and Akt associated with phosphatidylinositol signaling pathway by inhibiting SLC7A11. MiR-139-5p was found to be lowly expressed in PANC tissues, while SLC7A11 was highly expressed. Low expression of miR-139-5p and high expression of SLC7A11 were positively associated with poor clinical outcomes. PANC cell proliferation, invasion and metastasis could be inhibited by miR-139-5p overexpression and be promoted by SLC7A11 overexpression. MiR-139-5p overexpression could suppress PANC tumor growth and the expressions of SLC7A11, p-PI3K, p-Akt in tumor tissues. Therefore, the inhibitory of miR-139-5p to PANC cell proliferation, invasion and metastasis was partly due to its inhibiting effect on SLC7A11 expression.

CONCLUSION

Our study proves that miR-139-5p/SLC7A11 has important functions on PANC, suggesting that miR-139-5p can be used as a biomarker for PANC patients.

miR-27a ameliorates chemoresistance of breast cancer cells by disruption of reactive oxygen species homeostasis and impairment of autophagy

In patients with breast cancer, primary chemotherapy often fails due to survival of chemoresistant breast cancer stem cells (BCSCs) which results in recurrence and metastasis of the tumor. However, the factors determining the chemoresistance of BCSCs have remained to be investigated. Here, we profiled a series of differentially expressed microRNAs (miRNAs) between parental adherent breast cancer cells and BCSC-mimicking mammosphere-derived cancer cells, and identified hsa-miR-27a as a negative regulator for survival and chemoresistance of BCSCs. In the mammosphere, we found that the expression of hsa-miR-27a was downregulated, and ectopic overexpression of hsa-miR-27a reduced both number and size of mammospheres. In addition, overexpression of hsa-miR-27a sensitized breast cancer cells to anticancer drugs by downregulation of genes essential for detoxification of reactive oxygen species (ROS) and impairment of autophagy. Therefore, enhancing the hsa-miR-27a signaling pathway can be a potential therapeutic modality for breast cancer.

Overexpression of SLC6A1 associates with drug resistance and poor prognosis in prostate cancer

Background

Solute Carrier Family 6 Member 1 (SLC6A1) has been identified as a cancer-promoting gene in various human cancers, such as clear cell renal cell carcinoma and ovarian cancer. However, its roles in prostate cancer (PCa) has not been fully elucidated. The aim of this study was to investigate the expression and clinical significance of SLC6A1 in PCa tissues and its effect on drug resistance to docetaxel in PCa.

Methods

Expression patterns of SLC6A1 protein in PCa tissues were examined by immunohistochemistry based on Tissue microarray. Associations of SLC6A1 protein expression with various clinicopathological features and patients’ prognosis of PCa were also statistically evaluated based on TCGA data. Roles of SLC6A1 deregulation in prostate carcinogenesis and drug resistance was further determined in vitro and in vivo experiments.

Results

Based on TCGA Dataset, SLC6A1 expression was markedly higher in patients with high Gleason score, advanced clinical stage and positive biochemical recurrence than those with control features (all P < 0.05). Both unvariate and multivariate analyses demonstrated that SLC6A1 expression was significantly associated with biochemical recurrence-free survival in PCa patients. In addition, enforced expression of SLC6A1 effectively promoted cell proliferation, migration and invasion of PCa cells in vitro. Moreover, the inhibition of SLC6A1 suppressed the tumor growth in vivo. Additionally, immunohistochemical notches of PCNA and MMP-9 in the low-expression cluster were pointedly lower compared to those of NC group. Finally, the cell viability revealed that the overexpression of SLC6A1 obviously promoted the PCa cell resistant to docetaxel (DTX), and the transplanted tumor in the overexpression group had no significant reduction compared with the untreated group.

Conclusions

Our data suggest that SLC6A1 overexpression may be associated with aggressive progression and short biochemical recurrence-free survival of PCa, and may be related to the resistance to docetaxel therapy.

Metabolic Remodeling as a Way of Adapting to Tumor Microenvironment (TME), a Job of Several Holders

The microenvironment depends and generates dependence on all the cells and structures that share the same niche, the biotope. The contemporaneous view of the tumor microenvironment (TME) agrees with this idea. The cells that make up the tumor, whether malignant or not, behave similarly to classes of elements within a living community. These elements inhabit, modify and benefit from all the facilities the microenvironment has to offer and that will contribute to the survival and growth of the tumor and the progression of the disease.The metabolic adaptation to microenvironment is a crucial process conducting to an established tumor able to grow locally, invade and metastasized. The metastatic cancer cells are reasonable more plastic than non-metastatic cancer cells, because the previous ones must survive in the microenvironment where the primary tumor develops and in addition, they must prosper in the microenvironment in the metastasized organ.The metabolic remodeling requires not only the adjustment of metabolic pathways per se but also the readjustment of signaling pathways that will receive and obey to the extracellular instructions, commanding the metabolic adaptation. Many diverse players are pivotal in cancer metabolic fitness from the initial signaling stimuli, going through the activation or repression of genes, until the phenotype display. The new phenotype will permit the import and consumption of organic compounds, useful for energy and biomass production, and the export of metabolic products that are useless or must be secreted for a further recycling or controlled uptake. In the metabolic network, three subsets of players are pivotal: (1) the organic compounds; (2) the transmembrane transporters, and (3) the enzymes.This chapter will present the "Pharaonic" intent of diagraming the interplay between these three elements in an attempt of simplifying and, at the same time, of showing the complex sight of cancer metabolism, addressing the orchestrating role of microenvironment and highlighting the influence of non-cancerous cells.

Global metabolomic profiling of trastuzumab resistant gastric cancer cells reveals major metabolic pathways and metabolic signatures based on UHPLC-Q exactive-MS/MS

Resistance mechanism exploration has become an urgent need owing to the widespread trastuzumab resistance in gastric cancer. In this study, UHPLC-Q exactive MS/MS was carried out to characterize the metabolic profiles of human gastric cancer cell lines NCI N87, MKN45 (trastuzumab-sensitive) and NCI N87/R, MKN45/R (trastuzumab-resistant), respectively. Metabolic signatures and different metabolites were identified using multivariate in combination with univariate analysis. Integrated pathway enrichment analysis was executed using MetaboAnalyst and KEGG metabolic libraries to analyze the altered metabolic pathways in trastuzumab resistant cells. A total of 79 and 75 different metabolites were positively identified by utilizing authentic standards in NCI N87/R and MKN45/R cells, respectively. Furthermore, enrichment analysis demonstrated that seven metabolic pathways in NCI N87/R cells and five in MKN45/R cells were significantly changed. These pathways are involved in amino acid, nucleotide, carbohydrate, cofactor and vitamin metabolism, of which alanine, aspartate and glutamate metabolism displayed the highest pathway impact and lower P value both in NCI N87/R and MKN45/R cells. Moreover, we constructed a metabolomics-proteomics network between substantially altered metabolites and target genes which revealed citrate being regulated by citrate synthase and ACLY, while proline regulation was due to EPRS, PYCRL and PYCR1/2, respectively. Overall, our findings disclose prominent alterations of metabolic signatures in NCI N87/R and MKN45/R cells when compared with the parent cells which are crucial for understanding of underlying mechanisms of resistance and for developing strategies to overcome trastuzumab resistance.

Metabolic Remodelling: An Accomplice for New Therapeutic Strategies to Fight Lung Cancer

Metabolic remodelling is a hallmark of cancer, however little has been unravelled in its role in chemoresistance, which is a major hurdle to cancer control. Lung cancer is a leading cause of death by cancer, mainly due to the diagnosis at an advanced stage and to the development of resistance to therapy. Targeted therapeutic agents combined with comprehensive drugs are commonly used to treat lung cancer. However, resistance mechanisms are difficult to avoid. In this review, we will address some of those therapeutic regimens, resistance mechanisms that are eventually developed by lung cancer cells, metabolic alterations that have already been described in lung cancer and putative new therapeutic strategies, and the integration of conventional drugs and genetic and metabolic-targeted therapies. The oxidative stress is pivotal in this whole network. A better understanding of cancer cell metabolism and molecular adaptations underlying resistance mechanisms will provide clues to design new therapeutic strategies, including the combination of chemotherapeutic and targeted agents, considering metabolic intervenients. As cancer cells undergo a constant metabolic adaptive drift, therapeutic regimens must constantly adapt.

In silico characterization of residues essential for substrate binding of human cystine transporter, xCT

xCT is a sodium-independent amino acid antiporter that imports L-cystine and exports L-glutamate in a 1:1 ratio. It is a component of heterodimeric amino acid transporter system Xc- working at the cross-roads of maintaining neurological processes and regulating antioxidant defense. The transporter has 12 transmembrane domains with intracellular N- and C-termini, and like other transporter proteins can undergo various conformational changes while switching the ligand accessibilities from intracellular to extracellular site. In the present study, we generated two homology models of human xCT in two distinct conformations: inward-facing occluded state and outward-facing open state. Our results indicated the substrate translocation channel composed of transmembrane helices TMs 1, 3, 6, 8, and 10. We docked anionic L-cystine and L-glutamate within the cavities to assess the two distinct binding scenarios for xCT as antiporter. We also assessed the interactions between the ligands and transporter and observed that ligands bind to similar residues within the channel. Using MM-PBSA/MM-GBSA approach, we computed the binding energies of these ligands to different conformational states. Cystine and glutamate bind xCT with favorable binding energies, with more favorable binding observed in inward occluded state than in outward open state. We further computed the residue-wise decomposition of these binding energies and identified the residues as essential for substrate binding/permeation. Filtering the residues that form favorable energetic contributions to the ligand binding in both the states, our studies suggest T56, A60, R135, A138, V141, Y244, A247, F250, S330, L392, and R396 as critical residues for ligand binding as well as ligand transport for any conformational state adopted by xCT during its transport cycle. .Graphical Abstract.

Plasma cysteine/cystine and glutathione/glutathione disulfide redox potentials in HIV and COPD patients

Chronic obstructive pulmonary disease (COPD) is prevalent in patients infected with HIV. The purpose of this study was to test the hypothesis that systemic oxidation correlates with loss of lung function in subjects with COPD, and that HIV infection can contribute to creating such an environment. Subjects were recruited at the University of Louisville in the following groups: HIV-infected (n = 36), COPD (n = 32), HIV and COPD (n = 28), and uninfected controls with normal lung function (n = 34). HIV infection was assessed by viral load and CD4 cell counts. Pulmonary function was determined by spirometry, and plasma was collected for measurement of cysteine (Cys), cystine (CySS), glutathione (GSH) and GSH disulfide (GSSG) by HPLC followed by estimation of redox potentials (E_h) using the Nernst equation. Results showed that patients with COPD had more oxidized plasma E_h Cys/CySS than patients with normal lung function, but plasma E_h GSH/GSSG was unaltered. In addition, there was a correlation between the extent of plasma E_h Cys/CySS oxidation and loss of lung function, and this correlation remained even after correcting for age, sex, race and body mass index. HIV infection per se was not associated with increased oxidation of plasma E_h Cys/CySS, but plasma E_h Cys/CySS was more oxidized in patients with lower CD4-positve T cell counts. In patients with both HIV infection and COPD, there was a significant correlation between CD4 cell counts and lung function. Thus, systemic oxidation correlated with decreased lung function in subjects with COPD and decreased CD4 counts in subjects infected with HIV. Thus, factors contributing to plasma E_h Cys/CySS may represent novel mechanisms underlying the increased prevalence of COPD in people living with HIV.