Loss of MKP3 mediated by oxidative stress enhances tumorigenicity and chemoresistance of ovarian cancer cells

Atypical phosphatase DUSP11 inhibition promotes nc886 expression and potentiates gemcitabine-mediated cell death through NF-kB modulation

Pancreatic ductal adenocarcinoma (PDAC) represents one of the deadliest cancers among all solid tumors. First-line treatment relies on gemcitabine (Gem) and despite treatment improvements, refractoriness remains a universal challenge. Attempts to decipher how feedback-loops control signaling pathways towards drug resistance have gained attention in recent years, particularly focused on the role of phosphatases. In this study, a CRISPR/Cas9-based phenotypic screen was performed to identify members from the dual-specificity phosphatases (DUSP) family potentially acting on Gem response in PDAC cells. The approach revealed the atypical RNA phosphatase DUSP11 as a potential target, whose inhibition creates vulnerability of PDAC cells to Gem. DUSP11 genetic inhibition impaired cell survival and promoted apoptosis, synergistically enhancing Gem cytotoxicity. In silico transcriptome analysis of RNA-seq data from PDAC human samples identified NF-ĸB signaling pathway highly correlated with DUSP11 upregulation. Consistently, Gem-induced NF-ĸB phosphorylation was blocked upon DUSP11 inhibition in vitro. Mechanistically, we found that DUSP11 directly impacts nc886 expression and modulates PKR-NF-ĸB signaling cascade after Gem exposure in PDAC cells resulting in resistance to Gem-induced cell death. In conclusion, this study provides new insights on DUSP11 role in RNA biology and Gem response in PDAC cells.

Imperative connotation of SODs in cancer: Emerging targets and multifactorial role of action

Superoxide dismutase (SOD) is a crucial enzyme responsible for the redox homeostasis inside the cell. As a part of the antioxidant defense system, it plays a pivotal role in the dismutation of the superoxide radicals (O 2 - $$ {{\mathrm{O}}_2}^{-} $$ ) generated mainly by the oxidative phosphorylation, which would otherwise bring out the redox dysregulation, leading to higher reactive oxygen species (ROS) generation and, ultimately, cell transformation, and malignancy. Several studies have shown the involvement of ROS in a wide range of human cancers. As SOD is the key enzyme in regulating ROS, any change, such as a transcriptional change, epigenetic remodeling, functional alteration, and so forth, either activates the proto-oncogenes or aberrant signaling cascades, which results in cancer. Interestingly, in some cases, SODs act as tumor promoters instead of suppressors. Furthermore, SODs have also been known to switch their role during tumor progression. In this review, we have tried to give a comprehensive account of SODs multifactorial role in various human cancers so that SODs-based therapeutic strategies could be made to thwart cancers.

The pleiotropic functions of reactive oxygen species in cancer

Cellular redox homeostasis is an essential, dynamic process that ensures the balance between reducing and oxidizing reactions within cells and thus has implications across all areas of biology. Changes in levels of reactive oxygen species can disrupt redox homeostasis, leading to oxidative or reductive stress that contributes to the pathogenesis of many malignancies, including cancer. From transformation and tumor initiation to metastatic dissemination, increasing reactive oxygen species in cancer cells can paradoxically promote or suppress the tumorigenic process, depending on the extent of redox stress, its spatiotemporal characteristics and the tumor microenvironment. Here we review how redox regulation influences tumorigenesis, highlighting therapeutic opportunities enabled by redox-related alterations in cancer cells.

Scoparone attenuates PD-L1 expression in human breast cancer cells by MKP-3 upregulation

Breast cancer is a frequently occurring malignant tumor that is one of the leading causes of cancer-related deaths in women worldwide. Monoclonal antibodies that block programed cell death 1 (PD-1)/programed cell death ligand 1 (PD-L1) - a typical immune checkpoint - are currently the recommended standard therapies for many advanced and metastatic tumors such as triple-negative breast cancer. However, some patients develop drug resistance, leading to unfavorable treatment outcomes. Therefore, other approaches are required for anticancer treatments, such as downregulation of PD-L1 expression and promotion of degradation of PD-L1. Scoparone (SCO) is a bioactive compound isolated from Artemisia capillaris that exhibits antitumor activity. However, the effect of SCO on PD-L1 expression in cancer has not been confirmed yet. This study aimed to evaluate the role of SCO in PD-L1 expression in breast cancer cells in vitro. Our results show that SCO downregulated PD-L1 expression in a dose-dependent manner, via AKT inhibition. Interestingly, SCO treatment did not alter PTEN expression, but increased the expression of mitogen-activated protein kinase phosphatase-3 (MKP-3). In addition, the SCO-induced decrease in PD-L1 expression was reversed by siRNA-mediated MKP-3 knockdown. Collectively, these findings suggest that SCO inhibited the expression of PD-L1 in breast cancer cells by upregulating MKP-3 expression. Therefore, SCO may serve as an innovative combinatorial agent for cancer immunotherapy.

Angelicin inhibits cell growth and promotes apoptosis in oral squamous cell carcinoma by negatively regulating DUSP6/cMYC signaling pathway

Angelicin has been reported to have antitumor effects on many types of cancer. However, few studies on angelicin in oral squamous cell carcinoma (OSCC) have been performed. We performed cell cycle and apoptosis analyses to assess the effect of angelicin on OSCC cells. We conducted RNA-seq studies to reveal differentially expressed genes (DEGs). Dual-specificity phosphatase 6 (DUSP6) and c-MYC were strongly down-regulated differential genes. Silencing RNA (siRNA) was used to knockdown DUSP6. The mouse xenograft model was used to mimic OSCC. Angelicin inhibited OSCC in vitro. We found that DUSP6 interacted with c-MYC. DUSP6 knockdown group and DUSP6 knockdown + angelicin group had similar effects of OSCC cells. Angelicin could reduce tumor formation, DUSP6, and c-MYC expression in vivo. Compared with paclitaxel, the tumor inhibition effect of the two drugs was similar. However, angelicin did not cause weight loss and had lower toxicity. In sum, Angelicin has antitumor effects on OSCC in vitro and vivo by negatively regulating the DUSP6 mediated c-MYC signaling pathway.

Anticancer therapeutic effect of ginsenosides through mediating reactive oxygen species

Dysregulation of reactive oxygen species (ROS) production and ROS-regulated pathways in cancer cells leads to abnormal accumulation of reactive oxygen species, displaying a double-edged role in cancer progression, either supporting transformation/proliferation and stimulating tumorigenesis or inducing cell death. Cancer cells can accommodate reactive oxygen species by regulating them at levels that allow the activation of pro-cancer signaling pathways without inducing cell death via modulation of the antioxidant defense system. Therefore, targeting reactive oxygen species is a promising approach for cancer treatment. Ginsenosides, their derivatives, and related drug carriers are well-positioned to modulate multiple signaling pathways by regulating oxidative stress-mediated cellular and molecular targets to induce apoptosis; regulate cell cycle arrest and autophagy, invasion, and metastasis; and enhance the sensitivity of drug-resistant cells to chemotherapeutic agents of different cancers depending on the type, level, and source of reactive oxygen species, and the type and stage of the cancer. Our review focuses on the pro- and anticancer effects of reactive oxygen species, and summarizes the mechanisms and recent advances in different ginsenosides that bring about anticancer effects by targeting reactive oxygen species, providing new ideas for designing further anticancer studies or conducting more preclinical and clinical studies.

An Adverse Outcome Pathway Network for Chemically Induced Oxidative Stress Leading to (Non)genotoxic Carcinogenesis

Nongenotoxic (NGTX) carcinogens induce cancer via other mechanisms than direct DNA damage. A recognized mode of action for NGTX carcinogens is induction of oxidative stress, a state in which the amount of oxidants in a cell exceeds its antioxidant capacity, leading to regenerative proliferation. Currently, carcinogenicity assessment of environmental chemicals primarily relies on genetic toxicity end points. Since NGTX carcinogens lack genotoxic potential, these chemicals may remain undetected in such evaluations. To enhance the predictivity of test strategies for carcinogenicity assessment, a shift toward mechanism-based approaches is required. Here, we present an adverse outcome pathway (AOP) network for chemically induced oxidative stress leading to (NGTX) carcinogenesis. To develop this AOP network, we first investigated the role of oxidative stress in the various cancer hallmarks. Next, possible mechanisms for chemical induction of oxidative stress and the biological effects of oxidative damage to macromolecules were considered. This resulted in an AOP network, of which associated uncertainties were explored. Ultimately, development of AOP networks relevant for carcinogenesis in humans will aid the transition to a mechanism-based, human relevant carcinogenicity assessment that involves a substantially lower number of laboratory animals.

Loss of Kmt2c in vivo leads to EMT, mitochondrial dysfunction and improved response to lapatinib in breast cancer

Deep sequencing of human tumours has uncovered a previously unappreciated role for epigenetic regulators in tumorigenesis. H3K4 methyltransferase KMT2C/MLL3 is mutated in several solid malignancies, including more than 10% of breast tumours. To study the tumour suppressor role of KMT2C in breast cancer, we generated mouse models of Erbb2/Neu, Myc or PIK3CA-driven tumorigenesis, in which the Kmt2c locus is knocked out specifically in the luminal lineage of mouse mammary glands using the Cre recombinase. Kmt2c knock out mice develop tumours earlier, irrespective of the oncogene, assigning a bona fide tumour suppressor role for KMT2C in mammary tumorigenesis. Loss of Kmt2c induces extensive epigenetic and transcriptional changes, which lead to increased ERK1/2 activity, extracellular matrix re-organization, epithelial-to-mesenchymal transition and mitochondrial dysfunction, the latter associated with increased reactive oxygen species production. Loss of Kmt2c renders the Erbb2/Neu-driven tumours more responsive to lapatinib. Publicly available clinical datasets revealed an association of low Kmt2c gene expression and better long-term outcome. Collectively, our findings solidify the role of KMT2C as a tumour suppressor in breast cancer and identify dependencies that could be therapeutically amenable.

Reactive oxygen species and ovarian diseases: Antioxidant strategies

Reactive oxygen species (ROS) are mainly produced in mitochondria and are involved in various physiological activities of the ovary through signaling and are critical for regulating the ovarian cycle. Notably, the imbalance between ROS generation and the antioxidant defense system contributes to the development of ovarian diseases. These contradictory effects have critical implications for potential antioxidant strategies that aim to scavenge excessive ROS. However, much remains to be learned about how ROS causes various ovarian diseases to the application of antioxidant therapy for ovarian diseases. Here, we review the mechanisms of ROS generation and maintenance of homeostasis in the ovary and its associated physiological effects. Additionally, we have highlighted the pathological mechanisms of ROS in ovarian diseases and potential antioxidant strategies for treatment.

Mechanisms of ERK phosphorylation triggered via mouse formyl peptide receptor 2

Formyl peptide receptors (FPRs) are expressed in the cells of the innate immune system and provide binding with pathogen and damage-associated molecular patterns with subsequent activation of the phagocytes for defense reactions such as chemotaxis, secretory degranulation and ROS generation. Probably, FPR2 is one of the unique receptors in the organism; it is able to recognize numerous ligands of different chemical structure, and moreover, these ligands can trigger opposite phagocyte responses promoting either pro- or anti-inflammatory reactions. Therefore, FPR2 and its signaling pathways are of intense research interest. We found only slight activation of ERK1/2 in the response to peptide ligand WKYMVM in the accelerating phase of ROS generation and more intense ERK1/2 phosphorylation in the declining phase of it in mouse bone marrow granulocytes. Lipid agonist BML-111 did not induce significant ERK phosphorylation when applied for 10-1800 s. To some extent co-localization of ERK1/2 and NADPH oxidase subunits was observed even in the intact cells and didn't change under FPR2 stimulation by WKYMVM, while direct PKC activation by PMA resulted to more efficient interaction between ERK1/2 and p47phox/p67phox and their translocation to plasma membrane. We have shown that phosphorylation and activation of ERK1/2 in bone marrow granulocytes depended on FPR2-triggered activity of PI3K and PKC, phosphatase DUSP6, and, the most but not the least, on ROS generation. Since blocking of ROS generation led to a slowdown of ERK activation indicating a significant contribution of ROS to the secondary regulation of ERK activity.

Identification and validation of four photodynamic therapy related genes inhibiting MAPK and inducing cell cycle alteration in squamous cell carcinoma

Introduction

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer, and photodynamic therapy (PDT) is a promising modality against cSCC. This study investigated the impact of PDT on the MAPK pathway and cell cycle alternation of cSCC as well as the related molecular mechanisms.

Method

Expressing mRNA profile data sets GSE98767, GSE45216, and GSE84758 were acquired from the GEO database. The functions of differently expressed genes (DEGs) were enriched by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Least absolute shrinkage and selection operator (Lasso) analysis were used to establish a diagnosis model based on GSE98767. A correlation analysis and a protein–protein interaction (PPI) network were used to evaluate the relationship between cSCC-PDT-related genes and the MAPK pathway. Single-sample gene set enrichment analysis (ssGSEA) was performed on GSE98767 to estimate MAPK activation and cell cycle activity. Finally, the effect of MAPK activation on the cell cycle was explored in vitro.

Result

Four cSCC-PDT-related genes, DUSP6, EFNB2, DNAJB1, and CCNL1, were identified as diagnostic markers of cSCC, which were upregulated in cSCC or LC50 PDT-protocol treatment and negatively correlated with the MAPK promoter. Despite having a smaller MAPK activation score, cSCC showed higher cell cycle activity. The PDT treatment suppressed the G1 to G2/M phase in JNK overexpressed A431 cells.

Conclusion

CCNL1, DNAJB1, DUSP6, and EFNB2 were identified as potential PDT target genes in cSCC treatment, whose potential therapeutic mechanism was inhibiting the MAPK pathway and inducing cell cycle alternation.

Extracellular Vesicles and Cancer Therapy: Insights into the Role of Oxidative Stress

Oxidative stress plays a significant role in cancer development and cancer therapy, and is a major contributor to normal tissue injury. The unique characteristics of extracellular vesicles (EVs) have made them potentially useful as a diagnostic tool in that their molecular content indicates their cell of origin and their lipid membrane protects the content from enzymatic degradation. In addition to their possible use as a diagnostic tool, their role in how normal and diseased cells communicate is of high research interest. The most exciting area is the association of EVs, oxidative stress, and pathogenesis of numerous diseases. However, the relationship between oxidative stress and oxidative modifications of EVs is still unclear, which limits full understanding of the clinical potential of EVs. Here, we discuss how EVs, oxidative stress, and cancer therapy relate to one another; how oxidative stress can contribute to the generation of EVs; and how EVs’ contents reveal the presence of oxidative stress. We also point out the potential promise and limitations of using oxidatively modified EVs as biomarkers of cancer and tissue injury with a focus on pediatric oncology patients.

ROS and miRNA Dysregulation in Ovarian Cancer Development, Angiogenesis and Therapeutic Resistance

The diverse repertoires of cellular mechanisms that progress certain cancer types are being uncovered by recent research and leading to more effective treatment options. Ovarian cancer (OC) is among the most difficult cancers to treat. OC has limited treatment options, especially for patients diagnosed with late-stage OC. The dysregulation of miRNAs in OC plays a significant role in tumorigenesis through the alteration of a multitude of molecular processes. The development of OC can also be due to the utilization of endogenously derived reactive oxygen species (ROS) by activating signaling pathways such as PI3K/AKT and MAPK. Both miRNAs and ROS are involved in regulating OC angiogenesis through mediating multiple angiogenic factors such as hypoxia-induced factor (HIF-1) and vascular endothelial growth factor (VEGF). The NAPDH oxidase subunit NOX4 plays an important role in inducing endogenous ROS production in OC. This review will discuss several important miRNAs, NOX4, and ROS, which contribute to therapeutic resistance in OC, highlighting the effective therapeutic potential of OC through these mechanisms.

Molecular relation between biological stress and carcinogenesis

This paper aims to overview different types of stress, including DNA replication stress, oxidative stress, and psychological stress. Understanding the processes that constitute a cellular response to varied types of stress lets us find differences in how normal cells and cancer cells react to the appearance of a particular kind of stressor. The revealed dissimilarities are the key for targeting new molecules and signaling pathways in anticancer treatment. For this reason, molecular mechanisms that underlay DNA replication stress, oxidative stress, and psychological stress have been studied and briefly presented to indicate biochemical points that make stressors contribute to cancer development. What is more, the viewpoint in which cancer constitutes the outcome and the cause of stress has been taken into consideration. In a described way, this paper draws attention to the problem of cancer-related post-traumatic stress disorder and proposes a novel, multidimensional oncological approach, connecting anticancer treatment with psychiatric support.

Cynarin attenuates LPS-induced endothelial inflammation via upregulation of the negative regulator MKP-3

Clinical observations have revealed that non-resolving low-grade inflammation is linked to the pathogenesis of chronic inflammatory diseases, for example arthritis, atherosclerosis, Alzheimer’s disease, diabetes, and chronic kidney disease. Interestingly, low levels of circulating lipopolysaccharides (LPS) derived from the outer membrane of gram-negative bacteria appear to be one of the primary causes of persistent low-grade inflammation. The inner surface of the blood vessels is lined with endothelial cells; therefore, even low levels of circulating LPS can directly activate these cells and elicit specific cellular responses, such as an increase in the expression levels of cell adhesion molecules and proinflammatory mediators. In endothelial cells, LPS exposure results in an inflammatory response through activation of nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases. Cynarin, a phytochemical found in artichokes, has several pharmacological properties against endothelial inflammation. In the present study, we discovered that cynarin suppressed the LPS-induced increase in the expression levels of vascular cell adhesion molecule-1 and proinflammatory mediators such as monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-α (TNF-α), and interleukin-1β in EA.hy926 cells. Further, cynarin inhibited the activation of p38 and NF-κB pathways by inducing the negative regulator mitogen-activated protein kinase phosphatase 3 (MKP-3) in LPS-stimulated EA.hy926 cells. In conclusion, cynarin alleviates inflammation by upregulating MKP-3, a negative regulator of p38 and NF-κB, and it may be a therapeutic option for treating endothelial inflammation-related diseases.

Biphasic Regulation of Mitogen-Activated Protein Kinase Phosphatase 3 in Hypoxic Colon Cancer Cells

Hypoxia, or low oxygen tension, is a hallmark of the tumor microenvironment. The hypoxia-inducible factor-1α (HIF-1α) subunit plays a critical role in the adaptive cellular response of hypoxic tumor cells to low oxygen tension by activating gene-expression programs that control cancer cell metabolism, angiogenesis, and therapy resistance. Phosphorylation is involved in the stabilization and regulation of HIF-1α transcriptional activity. HIF-1α is activated by several factors, including the mitogen-activated protein kinase (MAPK) superfamily. MAPK phosphatase 3 (MKP-3) is a cytoplasmic dual-specificity phosphatase specific for extracellular signal-regulated kinase 1/2 (Erk1/2). Recent evidence indicates that hypoxia increases the endogenous levels of both MKP-3 mRNA and protein. However, its role in the response of cells to hypoxia is poorly understood. Herein, we demonstrated that small-interfering RNA (siRNA)-mediated knockdown of MKP-3 enhanced HIF-1α (not HIF-2α) levels. Conversely, MKP-3 overexpression suppressed HIF-1α (not HIF-2α) levels, as well as the expression levels of hypoxia-responsive genes (LDHA, CA9, GLUT-1, and VEGF), in hypoxic colon cancer cells. These findings indicated that MKP-3, induced by HIF-1α in hypoxia, negatively regulates HIF-1α protein levels and hypoxia-responsive genes. However, we also found that long-term hypoxia (>12 h) induced proteasomal degradation of MKP-3 in a lactic acid-dependent manner. Taken together, MKP-3 expression is modulated by the hypoxic conditions prevailing in colon cancer, and plays a role in cellular adaptation to tumor hypoxia and tumor progression. Thus, MKP-3 may serve as a potential therapeutic target for colon cancer treatment.

Knockdown of TRIM9 attenuates irinotecan‑induced intestinal mucositis in IEC‑6 cells by regulating DUSP6 expression via the P38 pathway

Intestinal mucositis is a common side effect of cancer chemotherapy and it limits the dose of chemotherapy given to a patient. Tripartite motif family (TRIM) proteins have been reported to be implicated in the regulation of cancer chemotherapy. The present study aimed to investigate the effect of TRIM9 on irinotecan-induced intestinal mucositis in the rat intestinal epithelial cell line IEC-6. The expression of several TRIMs, such as TRIM1, TRIM9, TRIM18, TRIM36, TRIM46 and TRIM67, was examined. After TRIM9 knockdown or overexpression by lentivirus infection, cell proliferation and apoptosis, epithelial barrier tight-junction proteins, inflammatory cytokines, transepithelial electrical resistance (TEER) and FITC dextran were measured. Treatment with irinotecan significantly inhibited cell proliferation and induced cell apoptosis, TRIM9 expression, intestinal mucosal barrier impairment, the levels of inflammatory cytokines and P38 phosphorylation in IEC-6 cells, while the expression levels of epithelial barrier tight-junction protein ZO-1 and Claudin-4 were decreased. Knockdown of TRIM9 partly counteracted the effect of irinotecan treatment, and inhibition of P38 potently reversed the effect of TRIM9 overexpression in IEC-6 cells. Moreover, co-immunoprecipitation showed an interaction between TRIM9 and DUSP6 in IEC-6 cells, and overexpression of DUSP6 notably counteracted the effect of TRIM9 overexpression. The results demonstrated that TRIM9 knockdown may benefit patients with intestinal mucositis by inhibiting inflammatory cytokine expression and repairing intestinal barrier functions, which was probably due to inhibition of the activation of the P38 pathway via targeting DUSP6.

The Stress-Inducible BCL2A1 Is Required for Ovarian Cancer Metastatic Progression in the Peritoneal Microenvironment

Emerging evidence indicates that hypoxia plays a critical role in governing the transcoelomic metastasis of ovarian cancer. Hence, targeting hypoxia may be a promising approach to prevent the metastasis of ovarian cancer. Here, we report that BCL2A1, a BCL2 family member, acts as a hypoxia-inducible gene for promoting tumor progression in ovarian cancer peritoneal metastases. We demonstrated that BCL2A1 was induced not only by hypoxia but also other physiological stresses through NF-κB signaling and then was gradually reduced by the ubiquitin-proteasome pathway in ascites-derived ovarian cancer cells. The upregulated BCL2A1 was frequently found in advanced metastatic ovarian cancer cells, suggesting its clinical relevance in ovarian cancer metastatic progression. Functionally, BCL2A1 enhanced the foci formation ability of ovarian cancer cells in a stress-conditioned medium, colony formation in an ex vivo omental tumor model, and tumor dissemination in vivo. Under stress conditions, BCL2A1 accumulated and colocalized with mitochondria to suppress intrinsic cell apoptosis by interacting with the BH3-only subfamily BCL2 members HRK/BAD/BID in ovarian cancer cells. These findings indicate that BCL2A1 is an early response factor that maintains the survival of ovarian cancer cells in the harsh tumor microenvironment.

Crosstalk between Autophagy and Inflammatory Processes in Cancer

Inflammation is an adaptive response to tissue injury, which is a critical process in order to restore tissue functionality and homeostasis. The association between inflammation and cancer has been a topic of interest for many years, not only inflammatory cells themselves but also the chemokines and cytokines they produce, which affect cancer development. Autophagy is an intracellular self-degradative process providing elimination of damaged or dysfunctional organelles under stressful conditions such as nutrient deficiency, hypoxia, or chemotherapy. Interestingly, the signaling pathways that are involved in cancer-associated inflammation may regulate autophagy as well. These are (1) the toll-like receptor (TLR) signaling cascade, (2) the reactive oxygen species (ROS) signaling pathway, (3) the inflammatory cytokine signaling pathway, and (4) the IκB kinase (IKK)/Nuclear factor-κB (NF-κB) signaling axis. Moreover, the studies on the context-specific functions of autophagy during inflammatory responses in cancer will be discussed here. On that basis, we focus on autophagy inhibitors and activators regulating inflammatory process in cancer as useful candidates for enhancing anticancer effects. This review summarizes how the autophagic process regulates these key inflammatory processes and vice versa in various cancers.

Down-regulation of dual-specificity phosphatase 6, a negative regulator of oncogenic ERK signaling, by ACA-28 induces apoptosis in NIH/3T3 cells overexpressing HER2/ErbB2

Dual-specificity phosphatase 6 (DUSP6) is a key negative feedback regulator of the member of the RAS-ERK MAPK signaling pathway that is associated with cellular proliferation and differentiation. Deterioration of DUSP6 expression could therefore result in deregulated growth activity. We have previously discovered ACA-28, a novel anticancer compound with a unique property to stimulate ERK phosphorylation and induce apoptosis in ERK-active melanoma cells. However, the mechanism of cancer cell-specific-apoptosis by ACA-28 remains obscure. Here, we investigated the involvement of DUSP6 in the mechanisms of the ACA-28-mediated apoptosis by using the NIH/3T3 cells overexpressing HER2/ErbB2 (A4-15 cells), as A4-15 exhibited higher ERK phosphorylation and are more susceptible to ACA-28 than NIH/3T3. We showed that A4-15 exhibited high DUSP6 protein levels, which require ERK activation. Notably, the silencing of the DUDSP6 gene by siRNA inhibited proliferation and induced apoptosis in A4-15, but not in NIH/3T3, indicating that A4-15 requires high DUSP6 expression for growth. Importantly, ACA-28 preferentially down-regulated the DUSP6 protein and proliferation in A4-15 via the proteasome, while it stimulated ERK phosphorylation. Collectively, the up-regulation of DUSP6 may exert a growth-promoting role in cancer cells overexpressing HER2. DUSP6 down-regulation in ERK-active cancer cells might have the potential as a novel cancer measure.

The Lipogenic Regulator SREBP2 Induces Transferrin in Circulating Melanoma Cells and Suppresses Ferroptosis

Circulating tumor cells (CTC) are shed by cancer into the bloodstream, where a viable subset overcomes oxidative stress to initiate metastasis. We show that single CTCs from patients with melanoma coordinately upregulate lipogenesis and iron homeostasis pathways. These are correlated with both intrinsic and acquired resistance to BRAF inhibitors across clonal cultures of BRAF-mutant CTCs. The lipogenesis regulator SREBP2 directly induces transcription of the iron carrier Transferrin (TF), reducing intracellular iron pools, reactive oxygen species, and lipid peroxidation, thereby conferring resistance to inducers of ferroptosis. Knockdown of endogenous TF impairs tumor formation by melanoma CTCs, and their tumorigenic defects are partially rescued by the lipophilic antioxidants ferrostatin-1 and vitamin E. In a prospective melanoma cohort, presence of CTCs with high lipogenic and iron metabolic RNA signatures is correlated with adverse clinical outcome, irrespective of treatment regimen. Thus, SREBP2-driven iron homeostatic pathways contribute to cancer progression, drug resistance, and metastasis. SIGNIFICANCE: Through single-cell analysis of primary and cultured melanoma CTCs, we have uncovered intrinsic cancer cell heterogeneity within lipogenic and iron homeostatic pathways that modulates resistance to BRAF inhibitors and to ferroptosis inducers. Activation of these pathways within CTCs is correlated with adverse clinical outcome, pointing to therapeutic opportunities.This article is highlighted in the In This Issue feature, p. 521.

The meiosis-specific cohesin component stromal antigen 3 promotes cell migration and chemotherapeutic resistance in colorectal cancer

Chromosome instability is one of the hallmarks of cancer. Stromal antigen (STAG) 3 is a core component of the meiosis-specific cohesin complex, which regulates sister chromatid cohesion. Although aberrantly activated genes encoding the cohesin complex have been identified in cancers, little is known about the role of STAG3 in colorectal cancer (CRC). Here, we evaluated the prognostic impact and role of STAG3 in CRC. Analysis of 172 CRC surgical specimens revealed that high STAG3 expression was associated with poor prognosis. STAG3 knockdown inhibited cell migration and increased drug sensitivity to oxaliplatin, 5-fluorouracil, irinotecan hydrochloride hydrate, and BRAF inhibitor in CRC cell lines. The enhanced drug sensitivity was also confirmed in a human organoid established from a CRC specimen. Moreover, suppression of STAG3 increased γH2AX foci. Particularly, in BRAF-mutant CRC cells, STAG3 silencing suppressed the expression of snail family transcriptional repressor 1 and phosphorylation of extracellular signal-regulated kinase via upregulation of dual-specificity phosphatase 6. Our findings suggest that STAG3 is related to poor clinical outcomes and promotes metastasis and chemotherapeutic resistance in CRC. STAG3 may be a novel prognostic marker and potential therapeutic target for CRC.

Role of Nrf2 and mitochondria in cancer stem cells; in carcinogenesis, tumor progression, and chemoresistance

Cancer stem cells (CSCs) are rare sub-population in tumor mass with self-renewal and differentiation abilities; CSCs are considered as the main cells which are responsible for tumor metastasis, cancer recurrence, and chemo/radio-resistance. CSCs are believed to contain low mitochondria in quantity, high concentration of nuclear factor erythroid 2-related factor 2 (Nrf2), and low reactive oxygen species (ROS) levels. Mitochondria regulate certain cellular functions, including controlling of cellular energetics, calcium signaling, cell growth and cell differentiation, cell cycle regulation, and cell death. Also, mitochondria are the main sources of intrinsic ROS production. Dysfunction of CSCs mitochondria due to oxidative phosphorylation is reported in several pathological conditions, including metabolic disorders, age-related diseases, and various types of cancers. ROS levels play a significant role in cellular signal transduction and CSCs' identity and differentiation capability. Nrf2 is a master transcription factor that plays critical functions in maintaining cellular redox hemostasis by regulating several antioxidant and detoxification pathways. Recently, the critical function of Nrf2 in CSCs has been revealed by several studies. Nrf2 is an essential molecule in the maintenance of CSCs' stemness and self-renewal in response to different oxidative stresses such as chemotherapy-induced elevation of ROS. Nrf2 enables these cells to recover from chemotherapy damages, and promotes establishment of invasion and dissemination. In this study, we have summarized the role of Nrf2 and mitochondria function CSCs, which promote cancer development. The significant role of Nrf2 in the regulation of mitochondrial function and ROS levels suggests this molecule as a potential target to eradicate CSCs.

[MicroRNA-145-5p over-expression suppresses proliferation, migration and invasion and promotes apoptosis of human endometrial cancer cells by targeting dual specific phosphatase 6]

OBJECTIVE

To investigate the role of microRNA-145-5p (miR-145-5p) in regulating the proliferation, migration, invasion and apoptosis of human endometrial carcinoma cells.

METHODS

Human endometrial carcinoma Ishikawa cells were transfected with miR-145-5p mimic, miR-145-5p inhibitor, or their negative controls via liposome (Lipo2000), and the changes in the expression of miR-145-5p was verified by real-time PCR. The effects of overexpression or inhibition of miR-145-5p on the proliferation, migration, invasion and apoptosis of the cells were evaluated using MTT assay, wound healing assay, Transwell assay or flow cytometry. Bioinformatic analysis was performed to predict the target genes of miR-145-5p. The mRNA and protein expression levels of the downstream target of miR-145-5p, namely dual specific phosphatase 6 (DUSP6), were detected using real-time PCR and Western blotting.

RESULTS

Transfection of the cells with miR-145-5p mimic significantly suppressed the proliferation of Ishikawa cells, while transfection with miR-145-5p inhibitor obvious enhanced the proliferation of the cells (P < 0.05). Over-expression of miR-145-5p significantly suppressed the migration and invasion and promoted apoptosis of the cells, and inhibition of miR-145-5p caused the reverse changes (P < 0.05). Bioinformatic analysis showed that DUSP6 was the potential target gene of miR-145-5p. Over-expression of miR-145-5p significantly lowered while inhibition of miR-145-5p significantly enhanced the expression of DUSP6 protein (P < 0.05).

CONCLUSIONS

Overexpression of miR-145-5p inhibits the proliferation, migration and invasion and promotes apoptosis of endometrial cancer cells possibly by negative regulation of DUSP6 expression.

Organochlorine pesticides induce inflammation, ROS production, and DNA damage in human epithelial ovary cells: An in vitro study

Although the etiology of ovarian cancer is not clear, certain factors are implicated in this disease, such as ovulation, gonadotropic and steroid hormones, growth factors, cytokines, environmental agents, etc. Epidemiological studies have proven environmental exposure to pesticides with an increased risk of Epithelial Ovarian Cancer (EOC); however, the molecular mechanism underlying the carcinogenic effects of pesticides in human ovary remains poorly understood. The present study aimed to study the pro-inflammatory response of organochlorine pesticides (OCPs) namely β-hexachlorocyclohexane (β-HCH), dichlorodiphenyldichloroethylene (DDE) and Dieldrin following exposure to human ovary surface epithelial cells (HOSE) for risk prediction of epithelial ovarian cancer. We found high level of Reactive oxygen species (ROS) production and DNA damage along with up-regulation of pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, nuclear factor kappa B (NF-kB) and cyclooxygenase (COX)-2 expression in OCPs treated HOSE cells compared to control (DMSO). The result of the present study suggests that β-HCH, DDE, and Dieldrin exposure induce ROS and pro-inflammatory response as well as DNA damage in HOSE cells. These various results show that OCPs may account for the neoplastic transformation of HOSE cells in the ovary.

Overexpression of DUSP6 enhances chemotherapy-resistance of ovarian epithelial cancer by regulating the ERK signaling pathway

Objective: DUSP6 is a negative regulator of the ERK signaling pathway and plays an important role in chemotherapy-resistance. Previously we showed that DUSP6 is overexpressed in ovarian cancer side population (SP) cells that possess cancer stem cell-like properties and are quiescent and chemotherapy-resistant. Here, we explore the effects of DUSP6 on chemotherapy-resistance by examining its regulation of the ERK signaling pathway and G0/G1 cell cycle arrest. Methods: mRNA and protein expression of DUSP6 and G0/G1 cell cycle checkpoint regulating proteins (CyclinD1, CyclinD3 and CyclinE2) was evaluated among ovarian cancer cell lines and tissue samples. Ovarian cancer cells were transiently transfected to overexpress DUSP6. After treatment with cisplatin, cell viability was measured by the MTS assay at 48 hours and the half maximal inhibitory concentration (IC50) for each cell line was calculated. Subcellular localization and cell cycle analysis were determined by using immunofluorescence and FACS, respectively. Results: SKOV3 and OVCAR8 SP cells were shown to express higher levels of DUSP6 and lower levels of CyclinD3 compared with non-SP (NSP) cells (P<0.001). Among 39 ovarian cancer tissue samples, expression of DUSP6 in the chemotherapy-resistant group (12 samples) was higher than in the chemotherapy-sensitive group (27 samples) (P<0.05). While a lower level of expression of CyclinD3 was seen in the chemotherapy-resistant group, it was not statistically different from the chemotherapy-sensitive group. HO8910 cells where shown to have higher IC50 to cisplatin than SKOV3 or OVCAR8 cells, and this correlated with higher levels of DUSP6 expression. Overexpression of DUSP6 in SKOV3 cells led to an increase in cisplatin IC50 values (P<0.05), and also markedly reduced the expression levels of phospho-ERK1/2 and CyclinD3 and to the predominance of cells in the G0/G1 phase. Conclusion: Our findings reveal an enhancement of chemotherapy-resistance and a predominance of cells in G1 cell cycle arrest in DUSP6-overexpressing ovarian cancer cells. This suggests that overexpression of DUSP6 promotes chemotherapy-resistance through the negative regulation of the ERK signaling pathway, increasing the G0/G1 phase ratio among ovarian cancer cells, and leading to cellular quiescence.

DUSP6 SUMOylation protects cells from oxidative damage via direct regulation of Drp1 dephosphorylation

Imbalanced mitochondrial fission/fusion, a major cause of apoptotic cell death, often results from dysregulation of Drp1 phosphorylation of two serines, S616 and S637. Whereas kinases for Drp1-S616 phosphorylation are well-described, phosphatase(s) for its dephosphorylation remains unclear. Here, we show that dual-specificity phosphatase 6 (DUSP6) dephosphorylates Drp1-S616 independently of its known substrates ERK1/2. DUSP6 keeps Drp1-S616 phosphorylation levels low under normal conditions. The stability and catalytic function of DUSP6 are maintained through conjugation of small ubiquitin-like modifier-1 (SUMO1) and SUMO2/3 at lysine-234 (K234), which is disrupted during oxidation through transcriptional up-regulation of SUMO-deconjugating enzyme, SENP1, causing DUSP6 degradation by ubiquitin-proteasome. deSUMOylation underlies DUSP6 degradation, Drp1-S616 hyperphosphorylation, mitochondrial fragmentation, and apoptosis induced by H₂O₂ in cultured cells or brain ischemia/reperfusion in mice. Overexpression of DUSP6, but not the SUMOylation-deficient DUSP6^K234R mutant, protected cells from apoptosis. Thus, DUSP6 exerts a cytoprotective role by directly dephosphorylating Drp1-S616, which is disrupted by deSUMOylation under oxidation.

Dynamic ROS Control by TIGAR Regulates the Initiation and Progression of Pancreatic Cancer

The TIGAR protein has antioxidant activity that supports intestinal tissue repair and adenoma development. Using a pancreatic ductal adenocarcinoma (PDAC) model, we show that reactive oxygen species (ROS) regulation by TIGAR supports premalignant tumor initiation while restricting metastasis. Increased ROS in PDAC cells drives a phenotypic switch that increases migration, invasion, and metastatic capacity. This switch is dependent on increased activation of MAPK signaling and can be reverted by antioxidant treatment. In mouse and human, TIGAR expression is modulated during PDAC development, with higher TIGAR levels in premalignant lesions and lower TIGAR levels in metastasizing tumors. Our study indicates that temporal, dynamic control of ROS underpins full malignant progression and helps to rationalize conflicting reports of pro- and anti-tumor effects of antioxidant treatment.

Dusp6 inhibits epithelial-mesenchymal transition in endometrial adenocarcinoma via ERK signaling pathway

Background Endometrial adenocarcinoma (EAC) is one of the most commonly diagnosed gynaecological malignancies among female population of the developed countries. DUSP6 is a negative regulator of ERK signaling, which is a molecular switch involved in MAPK signaling during the progress of malignancies. DUSP6 was previously found to inhibit tumorigenesis and EMT-associated properties in several cancers, however, its exact role in EAC remains unclear Methods The level of DUSP6, (E-cad) and (N-cad) in EAC cancerous tissues and respective adjacent non-cancerous tissues were examined by western-blot or immunohistochemistry. The cell growth, invasion and migration abilities were measured in Ishikawa 3H12 endometrial cancer cell lines with overexpressed or knock down DUSP6. Protein levels of EMT-associated markers E-cadherin, N-cadherin and Vimentin were also determined. The impacts of DUSP6 on ERK signaling was assessed by detection of ERK and p-ERK. Results Down-regulation of DUSP6 was observed in EAC compared with the normal controls. The overexpression of DUSP6 significantly attenuated tumor cell growth, invasion, migration abilities and inhibited EMT-associated markers, while knock down of DUSP6 showed opposite trends. Overexpression of DUSP6 also down-regulated p-ERK and the knock down of DUSP6 inversely up-regulated p-ERK level. Conclusions DUSP6 inhibited cell growth, invasion and migration abilities in Ishikawa 3H12 cells as well as attenuating EMT-associated properties. This tumor suppressive effect of DUSP6 in EAC is achieved by inhibiting ERK signaling pathway.

Combination of ω-3 fatty acids and cisplatin as a potential alternative strategy for personalized therapy of metastatic melanoma: an in-vitro study

The recently developed therapeutic strategies have led to unprecedented improvements in the control of metastatic melanoma and in the survival of specific subgroups of patients. However, drug resistance, low response rates, and undesired side effects make these treatments not suitable or tolerable for all the patients, and chemotherapeutic treatments appear still indispensable, at least for subgroups of patients. New combinatory strategies are also under investigation as tailored treatments or salvage therapies, including combined treatments of immunotherapy with conventional chemotherapy. On this basis, and in consideration of the antineoplastic properties of ω-3 polyunsaturated fatty acids, we have here investigated the potential of these bioactive dietary factors to revert the resistance frequently exhibited by this form of cancer to cisplatin (CDDP, cis-diamminedichloroplatinum). We demonstrated that docosahexenoic acid (DHA, 22:6ω-3) sensitizes the cells to the CDDP-induced inhibition of cell growth and migration by reverting CDDP effects on DNA damage and ERCC1 expression, as well as on the DUSP6 and p-ERK expressions, which regulate ERCC1 activation upwardly. In line, DUSP6 gene silencing prevented the effect of DHA, confirming that DHA acted on the DUSP6/p-ERK/ERCC1 repair pathways to sensitize melanoma cells to the anticancer effect of CDDP. Similar effects were obtained also with eicosapentaenoic acid (20:5ω-3). Overall, our findings suggest that the combination of CDDP treatment with a dietary supplementation with ω-3 polyunsaturated fatty acids could potentially represent a new therapeutic strategy for overcoming CDDP resistance in metastatic melanoma.

Paclitaxel-loaded biodegradable ROS-sensitive nanoparticles for cancer therapy

Background

Reactive oxygen species (ROS), such as hydrogen peroxide and superoxide, trigger biodegradation of polymer-based nanoparticles (NPs) bearing pinacol-type boronic ester groups. These NPs may selectively release their cargo, in this case paclitaxel (PTX), at the high levels of ROS present in the intracellular environment of inflamed tissues and most tumors.

Purpose

The main objective was to determine anti-tumor efficacy of PTX-loaded ROS-sensitive NPs and to examine whether macrophage infiltration had any impact on treatment efficacy.

Methods

NPs were synthesized and their characteristics in the presence of H₂O₂ were demonstrated. Both confocal microscopy as well as flow cytometry approaches were used to determine degradation of ROS-sensitive NPs. HeLa cells were cultured in vitro and used to establish tumor xenografts in nude mice. In vivo experiments were performed to understand toxicity, biodistribution and anti-tumor efficacy of the NPs. Moreover, we performed immunohistochemistry on tumor sections to study infiltration of M1 and M2 subsets of macrophages.

Results

We demonstrated that PTX delivered in NPs containing a ROS-sensitive polymer exhibits a better anti-tumor efficacy than PTX in NPs containing ROS-non-sensitive polymer, free PTX or Abraxane^® (nab-PTX). The biodistribution revealed that ROS-sensitive NPs exhibit retention in liver, spleen and lungs, suggesting a potential to target cancer metastasizing to these organs. Finally, we demonstrated a correlation between infiltrated macrophage subsets and treatment efficacy, possibly contributing to the efficient anti-tumor effects.

Conclusion

Treatment with ROS-sensitive NPs containing PTX gave an improved therapeutic effect in HeLa xenografts than their counterpart, free PTX or nab-PTX. Our data revealed a correlation between macrophage infiltration and efficiency of the different antitumor treatments, as the most effective NPs resulted in the highest infiltration of the anti-tumorigenic M1 macrophages.

Protein tyrosine phosphatases: promising targets in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer. It is the fourth leading cause of cancer-related death and is associated with a very poor prognosis. KRAS driver mutations occur in approximately 95% of PDAC cases and cause the activation of several signaling pathways such as mitogen-activated protein kinase (MAPK) pathways. Regulation of these signaling pathways is orchestrated by feedback loops mediated by the balance between protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs), leading to activation or inhibition of its downstream targets. The human PTPome comprises 125 members, and these proteins are classified into three distinct families according to their structure. Since PTP activity description, it has become clear that they have both inhibitory and stimulatory effects on cancer-associated signaling processes and that deregulation of PTP function is closely associated with tumorigenesis. Several PTPs have displayed either tumor suppressor or oncogenic characteristics during the development and progression of PDAC. In this sense, PTPs have been presented as promising candidates for the treatment of human pancreatic cancer, and many PTP inhibitors have been developed since these proteins were first associated with cancer. Nevertheless, some challenges persist regarding the development of effective and safe methods to target these molecules and deliver these drugs. In this review, we discuss the role of PTPs in tumorigenesis as tumor suppressor and oncogenic proteins. We have focused on the differential expression of these proteins in PDAC, as well as their clinical implications and possible targeting for pharmacological inhibition in cancer therapy.

Regulation of Dual-Specificity Phosphatase (DUSP) Ubiquitination and Protein Stability

Mitogen-activated protein kinases (MAPKs) are key regulators of signal transduction and cell responses. Abnormalities in MAPKs are associated with multiple diseases. Dual-specificity phosphatases (DUSPs) dephosphorylate many key signaling molecules, including MAPKs, leading to the regulation of duration, magnitude, or spatiotemporal profiles of MAPK activities. Hence, DUSPs need to be properly controlled. Protein post-translational modifications, such as ubiquitination, phosphorylation, methylation, and acetylation, play important roles in the regulation of protein stability and activity. Ubiquitination is critical for controlling protein degradation, activation, and interaction. For DUSPs, ubiquitination induces degradation of eight DUSPs, namely, DUSP1, DUSP4, DUSP5, DUSP6, DUSP7, DUSP8, DUSP9, and DUSP16. In addition, protein stability of DUSP2 and DUSP10 is enhanced by phosphorylation. Methylation-induced ubiquitination of DUSP14 stimulates its phosphatase activity. In this review, we summarize the knowledge of the regulation of DUSP stability and ubiquitination through post-translational modifications.

Environment and Male Fertility: Effects of Benzo-α-Pyrene and Resveratrol on Human Sperm Function In Vitro

Lifestyle, cigarette smoking and environmental pollution have a negative impact on male fertility. Therefore, the aim of this study was to evaluate the in-vitro effects of benzo-α-pyrene (BaP) and aryl hydrocarbon receptor (AHR) agonists on motility and bio-functional sperm parameters. We further assessed whether resveratrol (RES), an AHR antagonist and antioxidant molecule, had any protective effect. To accomplish this, 30 normozoospermic, healthy, non-smoker men not exposed to BaP were enrolled. Spermatozoa of 15 men were incubated with increasing concentrations of BaP to evaluate its effect and to establish its dose response. Then, spermatozoa of the 15 other men were incubated with BaP (15 µM/mL), chosen according to the dose-response and/or RES to evaluate its antagonistic effects. The effects of both substances were evaluated after 3 h of incubation on total and progressive sperm motility and on the following bio-functional sperm parameters evaluated by flow cytometry: Degree of chromatin compactness, viability, phosphatidylserine externalization (PS), late apoptosis, mitochondrial membrane potential (MMP), DNA fragmentation, degree of lipoperoxidation (LP), and concentrations of mitochondrial superoxide anion. Benzo-α-pyrene decreased total and progressive sperm motility, impaired chromatin compactness, and increased sperm lipoperoxidation and mitochondrial superoxide anion levels. All these effects were statistically significant at the lowest concentration tested (15 µM/mL) and they were confirmed at the concentration of 45 µM/mL. In turn, RES was able to counteract the detrimental effects of BaP on sperm motility, abnormal chromatin compactness, lipid peroxidation, and mitochondrial superoxide. This study showed that BaP alters sperm motility and bio-functional sperm parameters and that RES exerts a protective effect on BaP-induced sperm damage.

α-Mangostin and Apigenin Induced Cell Cycle Arrest and Programmed Cell Death in SKOV-3 Ovarian Cancer Cells

Ovarian cancer is the fifth main cause of pre-senescent death in women. Although chemotherapy is generally an efficient treatment, its side effects and the occurrence of chemotherapeutic resistance have prompted the need for alternative treatments. In this study, α-mangostin and apigenin were evaluated as possible anticancer alternatives to the chemotherapeutic drug doxorubicin, used herein as a positive control. The ovarian adenocarcinoma cell line SKOV-3 (ATCC No. HTB77) was used as model ovarian cancer cells, whereas the skin fibroblast line CCD-986Sk (ATCC No. CRL-1947) and lung fibroblast line WI-38 (ATCC No. CCL-75) were used as model untransformed cells. Apigenin and doxorubicin inhibited the growth of SKOV-3 cells in a dose- and time-dependent manner. After 72 hr exposure, doxorubicin was mostly toxic to SKOV-3 cells, whereas apigenin was toxic to SKOV-3 cells but not CCD-986Sk and WI-38 cells. α-Mangostin was more toxic to SKOV-3 cells than to CCD-986Sk cells. A lower cell density, cell shrinkage, and more unattached (floating round) cells were observed in all treated SKOV-3 cells, but the greatest effects were observed with α-mangostin. With regard to programmed cell death, apigenin caused early apoptosis within 24 hr, whereas α-mangostin and doxorubicin caused late apoptosis and necrosis after 72 hr of exposure. Caspase-3 activity was significantly increased in α-mangostin-treated SKOV-3 cells after 12 hr of exposure, whereas only caspase-9 activity was significantly increased in apigenin-treated SKOV-3 cells at 24 hr. Both α-mangostin and apigenin arrested the cell cycle at the G₂/M phase, but after 24 and 48 hr, respectively. Significant upregulation of BCL2 (apoptosis-associated gene) and COX2 (inflammation-associated gene) transcripts was observed in apigenin- and α-mangostin-treated SKOV-3 cells, respectively. α-Mangostin and apigenin are therefore alternative options for SKOV-3 cell inhibition, with apigenin causing rapid early apoptosis related to the intrinsic apoptotic pathway, and α-mangostin likely being involved with inflammation.

Human Epididymis Secretory Protein 4 (HE4) Compromises Cytotoxic Mononuclear Cells via Inducing Dual Specificity Phosphatase 6

While selective overexpression of serum clinical biomarker Human epididymis secretory protein 4 (HE4) is indicative of ovarian cancer tumorigenesis, much is still known about the mechanistic role of the HE4 gene or gene product. Here, we examine the role of the secretory glycoprotein HE4 in ovarian cancer immune evasion. Through modified subtractive hybridization analyses of human peripheral blood mononuclear cells (PBMCs), we have characterized gene targets of HE4 and established a preliminary mechanism of HE4-mediated immune failure in ovarian tumors. Dual specificity phosphatase 6 (DUSP6) emerged as the most upregulated gene in PBMCs upon in vitro exposure to HE4. DUSP6 was found to be upregulated in CD8⁺ cells and CD56⁺ cells. HE4 exposure reduced Erk1/2 phosphorylation specifically in these cell populations and the effect was erased by co-incubation with a DUSP6 inhibitor, (E)-2-benzylidene-3-(cyclohexylamino)-2,3-dihydro-1H-inden-1-one (BCI). In co-culture with PBMCs, HE4-silenced SKOV3 human ovarian cancer cells exhibited enhanced proliferation upon exposure to external HE4, while this effect was partially attenuated by adding BCI to the culture. Additionally, the reversal effects of BCI were erased in the co-culture with CD8⁺ / CD56⁺ cell deprived PBMCs. Taken together, these findings show that HE4 enhances tumorigenesis of ovarian cancer by compromising cytotoxic CD8⁺ and CD56⁺ cells through upregulation of self-produced DUSP6.

Genistein Prevents Development of Spontaneous Ovarian Cancer and Inhibits Tumor Growth in Hen Model

Genistein, the major isoflavone in soybean, has been reported to exert anticancer effects on various types of cancer including ovarian cancer; however, its chemopreventive effects and mechanisms of action in ovarian cancer have not been fully elucidated in spontaneously developing ovarian cancer models. In this study, we demonstrated the preventive effects and mechanisms of genistein in the laying hen model that develops spontaneous ovarian cancer at high incidence rates. Laying hens were randomized to three groups: control (3.01 mg/hen, n = 100), low (52.48 mg/hen n = 100), and high genistein supplementation (106.26 mg/hen/day; per group). At the end of 78 weeks, hens were euthanized and ovarian tumors were collected and analyzed. We observed that genistein supplementation significantly reduced the ovarian tumor incidence (P = 0.002), as well as the number and size of the tumors (P = 0.0001). Molecular analysis of the ovarian tumors revealed that genistein downregulated serum malondialdehyde, a marker for oxidative stress and the expression of NFκB and Bcl-2, whereas it upregulated Nrf2, HO-1, and Bax expression at protein level in ovarian tissues. Moreover, genistein intake decreased the activity of mTOR pathway as evidenced by reduced phosphorylation of mTOR, p70S6K1, and 4E-BP1. Taken together, our findings strongly support the potential of genistein in the chemoprevention of ovarian cancer and highlight the effects of the genistein on the molecular pathways involved in ovarian tumorigenesis.

Resveratrol promotes apoptosis through the induction of dual specificity phosphatase 1 and sensitizes prostate cancer cells to cisplatin

Resveratrol is a polyphenol with chemopreventive properties against prostate cancer; however, the mechanisms underlying its actions are not completely understood. Previously, we demonstrated that DUSP1 induces apoptosis in prostate cancer cells; therefore in the present study we investigated the role of this phosphatase on resveratrol effects. Moreover, we analysed the efficiency of combined treatment of resveratrol and the chemotherapeutic drug cisplatin on cellular viability and apoptosis and its relation with DUSP1 in prostate cancer cells. We found that resveratrol up-regulates DUSP1 expression in androgen-independent prostate cancer cells, which in turn, is involved in the inhibition of the NF-κB pathway and Cox-2 expression. This phosphatase is required for the induction of apoptosis achieved by resveratrol, but does not regulate the effects of this compound on cell cycle. Furthermore, we show that resveratrol cooperates with cisplatin both in the up-regulation of DUSP1 levels and in the promotion of apoptosis, suggesting that DUSP1 is a major determinant of cisplatin sensitivity to apoptosis. These results reveal a novel molecular mechanism by which resveratrol induces apoptosis in prostate cancer cells, and highlight the importance of DUSP1 in future therapeutic approaches based in the use of this polyphenol and cisplatin.

Gene expression profiling of spontaneously occurring canine mammary tumours: Insight into gene networks and pathways linked to cancer pathogenesis

Spontaneously occurring canine mammary tumours (CMTs) are the most common neoplasms of unspayed female dogs leading to thrice higher mortality rates than human breast cancer. These are also attractive models for human breast cancer studies owing to clinical and molecular similarities. Thus, they are important candidates for biomarker studies and understanding cancer pathobiology. The study was designed to explore underlying molecular networks and pathways in CMTs for deciphering new prognostic factors and therapeutic targets. To gain an insight into various pathways and networks associated with the development and pathogenesis of CMTs, comparative cDNA microarray expression profiling was performed using CMT tissues and healthy mammary gland tissues. Upon analysis, 1700 and 1287 differentially expressed genes (DEGs, P ≤ 0.05) were identified in malignant and benign tissues, respectively. DEGs identified from microarray analysis were further annotated using the Ingenuity Systems Pathway Analysis (IPA) tool for detection of deregulated canonical pathways, upstream regulators, and networks associated with malignant, as well as, benign disease. Top scoring key networks in benign and malignant mammary tumours were having central nodes of VEGF and BUB1B, respectively. Cyclins & cell cycle regulation and TREM1 signalling were amongst the top activated canonical pathways in CMTs. Other cancer related significant pathways like apoptosis signalling, dendritic cell maturation, DNA recombination and repair, Wnt/β-catenin signalling, etc. were also found to be altered. Furthermore, seven proteins (ANXA2, APOCII, CDK6, GATC, GDI2, GNAQ and MYH9) highly up-regulated in malignant tissues were identified by two-dimensional gel electrophoresis (2DE) and MALDI-TOF PMF studies which were in concordance with microarray data. Thus, the study has uncovered ample number of candidate genes associated with CMTs which need to be further validated as therapeutic targets and prognostic markers.

Reactive Oxygen and Nitrogen Species-Induced Protein Modifications: Implication in Carcinogenesis and Anticancer Therapy

Cancer is a complex disorder extremely dependent on its microenvironment and highly regulated by multiple intracellular and extracellular stimuli. Studies show that reactive oxygen and nitrogen species (RONS) play key roles in cancer initiation and progression. Accumulation of RONS caused by imbalance between RONS generation and activity of antioxidant system (AOS) has been observed in many cancer types. This leads to alterations in gene expression levels, signal transduction pathways, and protein quality control machinery, that is, processes that regulate cancer cell proliferation, migration, invasion, and apoptosis. This review focuses on the latest advancements evidencing that RONS-induced modifications of key redox-sensitive residues in regulatory proteins, that is, cysteine oxidation/S-sulfenylation/S-glutathionylation/S-nitrosylation and tyrosine nitration, represent important molecular mechanisms underlying carcinogenesis. The oxidative/nitrosative modifications cause alterations in activities of intracellular effectors of MAPK- and PI3K/Akt-mediated signaling pathways, transcription factors (Nrf2, AP-1, NFκB, STAT3, and p53), components of ubiquitin/proteasomal and autophagy/lysosomal protein degradation systems, molecular chaperones, and cytoskeletal proteins. Redox-sensitive proteins, RONS-generating enzymes, and AOS components can serve as targets for relevant anticancer drugs. Chemotherapeutic agents exert their action via RONS generation and induction of cancer cell apoptosis, while drug resistance associates with RONS-induced cancer cell survival; this is exploited in selective anticancer therapy strategies. Cancer Res; 78(21); 6040-7. ©2018 AACR.

Dual-specificity phosphatase 6 deletion protects the colonic epithelium against inflammation and promotes both proliferation and tumorigenesis

The Ras/mitogen‐activated protein kinase (MAPK) pathway controls fundamental cellular processes such as proliferation, differentiation, and apoptosis. The dual‐specificity phosphatase 6 (DUSP6) regulates cytoplasmic MAPK signaling by dephosphorylating and inactivating extracellular signal‐regulated kinase (ERK1/2) MAPK. To determine the role of DUSP6 in the maintenance of intestinal homeostasis, we characterized the intestinal epithelial phenotype of Dusp6 knockout (KO) mice under normal, oncogenic, and proinflammatory conditions. Our results show that loss of Dusp6 increased crypt depth and epithelial cell proliferation without altering colonic architecture. Crypt regeneration capacity was also enhanced, as revealed by ex vivo Dusp6 KO organoid cultures. Additionally, loss of Dusp6 induced goblet cell expansion without affecting enteroendocrine and absorptive cell differentiation. Our data also demonstrate that Dusp6 KO mice were protected from acute dextran sulfate sodium‐induced colitis, as opposed to wild‐type mice. In addition, Dusp6 gene deletion markedly enhanced tumor load in Apc^Min/+ mice. Decreased DUSP6 expression by RNA interference in HT29 colorectal cancer cells enhanced ERK1/2 activation levels and promoted both anchorage‐independent growth in soft agar as well as invasion through Matrigel. Finally, DUSP6 mRNA expression in human colorectal tumors was decreased in advanced stage tumors compared with paired normal tissues. These results demonstrate that DUSP6 phosphatase, by controlling ERK1/2 activation, regulates colonic inflammatory responses, and protects the intestinal epithelium against oncogenic stress.

GPx3-mediated redox signaling arrests the cell cycle and acts as a tumor suppressor in lung cancer cell lines

Glutathione peroxidase 3 (GPx3), a major scavenger of reactive oxygen species (ROS) in plasma, acts as a redox signal modulator. However, the mechanism underlying GPx3-mediated suppression of cancer cell growth is unclear. The aim of this study was to identify these mechanisms with respect to lung cancer. To enhance the redox modulating properties of GPx3, lung cancer cells were subjected to serum starvation for 12 h, resulting in ROS generation in the absence of oxidant treatment. We then investigated whether suppression of tumorigenesis under conditions of oxidative stress was dependent on GPx3. The results showed that GPx3 effectively suppressed proliferation, migration, and invasion of lung cancer cells under oxidative stress. In addition, GPx3 expression led to a significant reduction in ROS production by cancer cells and induced G2/M phase arrest. We also found that inactivation of cyclin B1 significantly suppressed by nuclear factor-κB(NF-κB) inactivation in lung cancer cells was dependent on GPx3 expression. To further elucidate the mechanism(s) underlying GPx3-medited suppression of tumor proliferation, we next examined the effect of GPx3-mediated redox signaling on the ROS-MKP3-extracellular signal-regulated kinase (Erk)-NF-κB-cyclin B1 pathway and found that GPx3 strongly suppressed activation of the Erk-NF-κB-cyclin B1 signaling cascade by protecting MKP3 (an Erk-specific phosphatase) from the effects of ROS. Thus, this study demonstrates for the first time that the GPx3 suppresses proliferation of lung cancer cells by modulating redox-mediated signals.

Anti-inflammatory and antitumor action of hydrogen via reactive oxygen species

Hydrogen (H₂) has advantages that lead it to be used as a novel antioxidant in preventive and therapeutic applications. H₂ can permeate into biomembranes, cytosol, mitochondria and nuclei, and can be dissolved in water or saline to produce H₂ water or H₂-rich saline. H₂ selectively reduces oxidants of the detrimental reactive oxygen species (ROS), including hydroxyl radicals (·OH) and peroxynitrite (ONOO^-), which serve a causative role in the promotion of tumor cell proliferation, invasion and metastasis, but do not disturb metabolic oxidation-reduction reactions in cell signaling. Compared with traditional antioxidants, H₂ is a small molecule that can easily dissipate throughout the body and cells; thus, it may be a safe and effective antioxidant for inflammatory diseases and cancer, since ROS usually initiates tumor progression. Treatment with H₂ may involve correction of the oxidative/anti-oxidative imbalance and suppression of inflammatory mediators. Therefore the present review will discuss the anti-inflammatory and anti-tumorigenic action of H₂ via ROS.

Oxidative stress in female cancers

Breast, cervical and ovarian cancers are highly prevalent in women worldwide. Environmental, hormonal and viral-related factors are especially relevant in the development of these tumors. These factors are strongly related to oxidative stress (OS) through the generation of reactive oxygen species (ROS). The OS is caused by an imbalance in the redox status of the organism and is literally defined as "an imbalance between ROS generation and its detoxification by biological system leading to impairment of damage repair by cell/tissue". The multistep progression of cancer suggests that OS is involved in cancer initiation, promotion and progression. In this review, we described the role of OS and the interplay with environmental, host and viral factors related to breast, cervical and ovarian cancers initiation, promotion and progression. In addition, the role of the natural antioxidant compound curcumin and other compounds for breast, cervical and ovarian cancers prevention/treatment is discussed.

Redox control in cancer development and progression

Cancer is the leading cause of death worldwide after cardiovascular diseases. This has been the case for the last few decades despite there being an increase in the number of cancer treatments. One reason for the apparent lack of drug effectiveness might be, at least in part, due to unspecificity for tumors; which often leads to substantial side effects. One way to improve the treatment of cancer is to increase the specificity of the treatment in accordance with the concept of individualized medicine. This will help to prevent further progression of an existing cancer or even to reduce the tumor burden. Alternatively it would be much more attractive and efficient to prevent the development of cancer in the first place. Therefore, it is important to understand the risk factors and the mechanisms of carcinogenesis in detail. One such risk factor, often associated with tumorigenesis and tumor progression, is an increased abundance of reactive oxygen species (ROS) arising from an imbalance of ROS-producing and -eliminating components. A surplus of ROS can induce oxidative damage of macromolecules including proteins, lipids and DNA. In contrast, ROS are essential for an adequate signal transduction and are known to regulate crucial cellular processes like cellular quiescence, differentiation and even apoptosis. Therefore, regulated ROS-formation at physiological levels can inhibit tumor formation and progression. With this review we provide an overview on the current knowledge of redox control in cancer development and progression.