ABCF2, an Nrf2 target gene, contributes to cisplatin resistance in ovarian cancer cells

The association of ABC proteins with multidrug resistance in cancer

Multidrug resistance (MDR) poses one of the primary challenges for cancer treatment, especially in cases of metastatic disease. Various mechanisms contribute to MDR, including the overexpression of ATP-binding cassette (ABC) proteins. In this context, we reviewed the literature to establish a correlation between the overexpression of ABC proteins and MDR in cancer, considering both in vitro and clinical studies. Initially, we presented an overview of the seven subfamilies of ABC proteins, along with the subcellular localization of each protein. Subsequently, we identified a panel of 20 ABC proteins (ABCA1-3, ABCA7, ABCB1-2, ABCB4-6, ABCC1-5, ABCC10-11, ABCE1, ABCF2, ABCG1, and ABCG2) associated with MDR. We also emphasize the significance of drug sequestration by certain ABC proteins into intracellular compartments. Among the anticancer drugs linked to MDR, 29 were definitively identified as substrates for at least one of the three most crucial ABC transporters: ABCB1, ABCC1, and ABCG2. We further discussed that the most commonly used drugs in standard regimens for mainly breast cancer, lung cancer, and acute lymphoblastic leukemia could be subject to MDR mediated by ABC transporters. Collectively, these insights will aid in conducting new studies aimed at a deeper understanding of the clinical MDR mediated by ABC proteins and in designing more effective pharmacological treatments to enhance the objective response rate in cancer patients.

High-adhesion ovarian cancer cell resistance to ferroptosis: The activation of NRF2/FSP1 pathway by junctional adhesion molecule JAM3

Ovarian cancer remains a significant challenge due to the lack of effective treatment and the resistance to conventional therapies. Ferroptosis, a form of regulated cell death characterized by iron-depend and lipid peroxidation, has emerged as a potential therapeutic target in cancer. Ovarian cancer has been reported to exert an "iron addiction" phenotype which makes it is susceptible to ferroptosis inducers. However, we found here that high-adhesion ovarian cancer cells were resistant to ferroptosis. Mechanistically, by PCR array, we identified junctional adhesion molecule 3 (JAM3) as a key mediator of ferroptosis resistance in high-adhesion ovarian cancer cells. Knockdowning and blocking JAM3 sensitized cancer cells to ferroptosis inducers RSL3 and erastin, while JAM3 overexpression conferred resistance to these agents. In addition, JAM3 also promoted ovarian cancer cells resistance to chemotherapeutic agent cisplatin in vitro and in vivo by inhibiting ferroptosis. Furthermore, we demonstrated that JAM3 promoted ferroptosis resistance through NRF2-induced upregulation of FSP1, a critical suppressor of lipid peroxidation. Inhibition of the NRF2/FSP1 pathway eliminated high-adhesion, JAM3 overexpressed ovarian cancer cells resistance to ferroptosis, and decreased cancer cells resistance to cisplatin. Moreover, JAM3 high expression was associated with poor prognosis in patients with ovarian cancer. Altogether, this study provided novel insights into the molecular mechanisms underlying ferroptosis resistance and identify JAM3 as a potential therapeutic target for combating drug resistance in ovarian cancer.

Machine learning model identifies genetic predictors of cisplatin-induced ototoxicity in CERS6 and TLR4

BACKGROUND

Cisplatin-induced ototoxicity remains a significant concern in pediatric cancer treatment due to its permanent impact on quality of life. Previously, genetic association analyses have been performed to detect genetic variants associated with this adverse reaction.

METHODS

In this study, a combination of interpretable neural networks and Generative Adversarial Networks (GANs) was employed to identify genetic markers associated with cisplatin-induced ototoxicity. The applied method, BRI-Net, incorporates biological domain knowledge to define the network structure and employs adversarial training to learn an unbiased representation of the data, which is robust to known confounders. Leveraging genomic data from a cohort of 362 cisplatin-treated pediatric cancer patients recruited by the CPNDS (Canadian Pharmacogenomics Network for Drug Safety), this model revealed two statistically significant single nucleotide polymorphisms to be associated with cisplatin-induced ototoxicity.

RESULTS

Two markers within the CERS6 (rs13022792, p-value: 3 × 10-4) and TLR4 (rs10759932, p-value: 7 × 10-4) genes were associated with this cisplatin-induced adverse reaction. CERS6, a ceramide synthase, contributes to elevated ceramide levels, a known initiator of apoptotic signals in mouse models of inner ear hair cells. TLR4, a pattern-recognition protein, initiates inflammation in response to cisplatin, and reduced TLR4 expression has been shown in murine hair cells to confer protection from ototoxicity.

CONCLUSION

Overall, these findings provide a foundation for understanding the genetic landscape of cisplatin-induced ototoxicity, with implications for improving patient care and treatment outcomes.

Paclitaxel-resistance facilitates glycolytic metabolism via Hexokinase-2-regulated ABC and SLC transporter genes in ovarian clear cell carcinoma

Ovarian clear cell carcinoma (OCCC) frequently develops resistance to platinum-based therapies, which is regarded as an aggressive subtype. However, metabolic changes in paclitaxel resistance remain unclear. Herein, we present the metabolic alternations of paclitaxel resistance in bioenergetic profiling in OCCC. Paclitaxel-resistant OCCC cells were developed and metabolically active with oxygen consumption rates (OCR) compared to parental cells. Metabolite profiling analysis revealed that paclitaxel-resistant OCCC cells reduced intracellular ATP and GTP influx rates, increasing the NADH/NAD+ ratio. We further demonstrated that paclitaxel-resistant OCCC cells led to characteristic alternations of metabolite levels in energy-requiring and energy-releasing steps of glycolysis and their corresponding glycolytic enzymes. Copy number alterations and RNA sequencing analysis demonstrated that ATP-binding cassette (ABC) transporters and solute carrier (SLC) transporter genes involved in glycolysis metabolism and molecular transport were enriched in paclitaxel-resistant OCCC cells. We first identified that Hexokinase 2 (HK2) expression is upregulated in paclitaxel-resistant OCCC cells to determine the quantity of glucose entering glycolysis. Utilizing proteolysis-targeting chimera (PROTAC) HK2 degraders, we also found that paclitaxel sensitivity, viability, and oxygen consumption rates under paclitaxel treatment were restored by HK2 degraders treatment, and decreased downstream expression of the ABC and SLC transporters was shown in OCCC cells. Taken together, these findings highlight the paclitaxel resistance in OCCC elucidates metabolic alternation, including ABC- and SLC- drug transporters, thereby affecting glycolysis metabolism in response to paclitaxel resistance, and HK2 may become a novel potential therapeutic target for paclitaxel resistance.

meso-Substituted AB3-type phenothiazinyl porphyrins and their indium and zinc complexes photosensitising properties, cytotoxicity and phototoxicity on ovarian cancer cells

New meso-substituted AB3-type phenothiazinyl porphyrins and ferrocenylvinyl phenothiazinyl porphyrin were synthesised by Suzuki-Miyaura and Mizoroki-Heck cross-coupling reactions, respectively. The free porphyrins were further used in the synthesis of new indium(iii) or zinc(ii) porphyrin complexes. All porphyrins exhibit red fluorescence emission in solution, a property that remains unimpaired following internalisation in ovarian A2780 cancer cells, as evidenced by fluorescence microscopy images. The In(iii) phenothiazinyl porphyrin complexes show a higher quantum yield of fluorescence emission (2aΦ F = 30%, 4aΦ F = 29%, 5aΦ F = 28%) compared to the free base porphyrin precursors, or Zn(ii) complex 4b (Φ F = 10%). The potential of novel phenothiazinyl porphyrins to act as photosensitisers was evaluated using two distinct approaches. The first was through the measurement of the singlet oxygen quantum yield Φ Δ(1O2), while the second employed in vitro measurements of metabolic activity, oxidative stress, nuclear factor-erythroid 2 related factor 2 (Nrf-2) activation and tumour necrosis factor-alpha (TNF-α) under both dark and light irradiation conditions. As reflected by the IC50 values, the most potent cytotoxicity of the phenothiazinyl porphyrins against the A2780 cells was observed for In(iii) ferrocenylvinyl phenothiazinyl porphyrin 4a (36.38 μM), the remaining compounds are less cytotoxic. The reduction in metabolic activity was observed in A2780 ovarian tumour cells treated with 4a and 6a and exposed to light compared to treatment in the absence of light. The oxidative stress, TNF-α and Nrf-2 transcription factor were particularly notable when A2780 cells were treated with 4a and subsequently photoirradiated, the oxidative stress was linked to the highest value of Φ Δ(1O2) recorded for 4a (60%).

Targeting Nrf2 signaling pathways in the role of bladder cancer: From signal network to targeted therapy

Bladder cancer (BC) is the most common malignancy of the urinary system and often recurs after tumor removal and/or is resistant to chemotherapy. In cancer cells, the activity of the signaling pathway changes significantly, affecting a wide range of cell activities from growth and proliferation to apoptosis, invasion and metastasis. Nrf2 is a transcription factor that plays an important role in cellular defense responses to a variety of cellular stresses. There is increasing evidence that Nrf2 acts as a tumor driver and that it is involved in the maintenance of malignant cell phenotypes. Abnormal expression of Nrf2 has been found to be common in a variety of tumors, including bladder cancer. Over-activation of Nrf2 can lead to DNA damage and the development of bladder cancer, and is also associated with various pathological phenomena of bladder cancer, such as metastasis, angiogenesis, and reduced toxicity and efficacy of therapeutic anticancer drugs to provide cell protection for cancer cells. However, the above process can be effectively inhibited or reversed by inhibiting Nrf2. Therefore, Nrf2 signaling may be a potential targeting pathway for bladder cancer. In this review, we will characterize this signaling pathway and summarize the effects of Nrf2 and crosstalk with other signaling pathways on bladder cancer progression. The focus will be on the impact of Nrf2 activation on bladder cancer progression and current therapeutic strategies aimed at blocking the effects of Nrf2. To better determine how to promote new chemotherapy agents, develop new therapeutic agents, and potential therapeutic targets.

TGF β1 promotes the polarization of M2-type macrophages and activates PI3K/mTOR signaling pathway by inhibiting ISG20 to sensitize ovarian cancer to cisplatin

The involvement of Interferon-stimulated exonuclease gene 20 (ISG20) has been reported in renal clear cell carcinoma, hepatocellular carcinoma, and cervical cancer. However, its role in ovarian cancer chemotherapy remains unclear. In this study, we conducted a comparative analysis of TGF-β1 and ISG20 in cisplatin-sensitive and cisplatin-resistant ovarian cancer cells and tissues using qRT-PCR and a tissue immunofluorescence analysis. We also investigated the impact of ISG20-targeted drugs (IFN-γ) and TGF-β1 inhibitors on cisplatin response both in vivo and in vitro. Additionally, we assessed the effects of TGF-β1 or ISG20 on the polarization of tumor-associated macrophages through flow cytometry and ELISA analysis. Our findings revealed that ISG20 expression was lower in cisplatin-resistant tissues compared to cisplatin-sensitive tissues; however, overexpression of ISG20 sensitized ovarian cancer to cisplatin treatment. Furthermore, activation of ISG20 expression with IFN-γ or TGF-β1 inhibitors enhanced the sensitivity of ovarian cancer cells to cisplatin therapy. Notably, our results demonstrated that TGF-β1 promoted M2-type macrophage polarization as well as PI3K/mTOR pathway activation by suppressing ISG20 expression both in vivo and in vitro. In conclusion, our study highlights the critical role played by ISG20 within the network underlying cisplatin resistance in ovarian cancer. Targeting ISG20 using IFN-γ or TGF-β1 inhibitors may represent a promising therapeutic strategy for treating ovarian cancer.

Integrative Inducer Intervention and Transcriptomic Analyses Reveal the Metabolism of Paralytic Shellfish Toxins in Azumapecten farreri

Paralytic shellfish toxins (PSTs) are widely distributed neurotoxins, and the PST metabolic detoxification mechanism in bivalves has received increasing attention. To reveal the effect of phase I (cytochrome P450)-II (GST)-III (ABC transport) metabolic systems on the PST metabolism in Azumapecten farreri, this study amplified stress on the target systems using rifampicin, dl-α-tocopherol, and colchicine; measured PST levels; and conducted transcriptomic analyses. The highest toxin content reached 1623.48 μg STX eq/kg in the hepatopancreas and only 8.8% of that in the gills. Inducer intervention significantly decreased hepatopancreatic PST accumulation. The proportional reductions in the rifampicin-, dl-α-tocopherol-, and colchicine-induced groups were 55.3%, 50.4%, and 36.1%, respectively. Transcriptome analysis showed that 11 modules were significantly correlated with PST metabolism (six positive/five negative), with phase I CYP450 and phase II glutathione metabolism significantly enriched in negatively correlated pathways. Twenty-three phase I-II-III core genes were further validated using qRT-PCR and correlated with PST metabolism, revealing that CYP46A1, CYP4F6, GSTM1, and ABCF2 were significantly correlated, while CYP4F11 and ABCB1 were indirectly correlated. In conclusion, phase I-II-III detoxification enzyme systems jointly participate in the metabolic detoxification of PSTs in A. farreri. This study provides key data support to profoundly elucidate the PST metabolic detoxification mechanism in bivalves.

Regulation of Nrf2/Keap1 signaling pathway in cancer drug resistance by galectin-1: cellular and molecular implications

Oxidative stress is characterized by the deregulation of the redox state in the cells, which plays a role in the initiation of various types of cancers. The activity of galectin-1 (Gal-1) depends on the cell redox state and the redox state of the microenvironment. Gal-1 expression has been related to many different tumor types, as it plays important roles in several processes involved in cancer progression, such as apoptosis, cell migration, adhesion, and immune response. The erythroid-2-related factor 2 (Nrf2)/Kelch-like ECH-associated protein 1 (Keap1) signaling pathway is a crucial mechanism involved in both cell survival and cell defense against oxidative stress. In this review, we delve into the cellular and molecular roles played by Gal-1 in the context of oxidative stress onset in cancer cells, particularly focusing on its involvement in activating the Nrf2/Keap1 signaling pathway. The emerging evidence concerning the anti-apoptotic effect of Gal-1, together with its ability to sustain the activation of the Nrf2 pathway in counteracting oxidative stress, supports the role of Gal-1 in the promotion of tumor cells proliferation, immuno-suppression, and anti-tumor drug resistance, thus highlighting that the inhibition of Gal-1 emerges as a potential strategy for the restraint and regression of tumor progression. Overall, a deeper understanding of the multi-functionality and disease-specific expression profiling of Gal-1 will be crucial for the design and development of novel Gal-1 inhibitors as anticancer agents. Excitingly, although it is still understudied, the ever-growing knowledge of the sophisticated interplay between Gal-1 and Nrf2/Keap1 will enable researchers to gain valuable insights into the underlying causes of carcinogenesis and metastasis.

From clinical management to personalized medicine: novel therapeutic approaches for ovarian clear cell cancer

Ovarian clear-cell cancer is a rare subtype of epithelial ovarian cancer with unique clinical and biological features. Despite optimal cytoreductive surgery and platinum-based chemotherapy being the standard of care, most patients experience drug resistance and a poor prognosis. Therefore, novel therapeutic approaches have been developed, including immune checkpoint blockade, angiogenesis-targeted therapy, ARID1A synthetic lethal interactions, targeting hepatocyte nuclear factor 1β, and ferroptosis. Refining predictive biomarkers can lead to more personalized medicine, identifying patients who would benefit from chemotherapy, targeted therapy, or immunotherapy. Collaboration between academic research groups is crucial for developing prognostic outcomes and conducting clinical trials to advance treatment for ovarian clear-cell cancer. Immediate progress is essential, and research efforts should prioritize the development of more effective therapeutic strategies to benefit all patients.

Effects of chemotherapeutic drugs on the antioxidant capacity of human erythroleukemia cells with MDR phenotype

In this work, we identified that different chemotherapeutic drugs may select cells with different antioxidant capacities. For this, we evaluated the sensitivity of two multidrug-resistant (MDR) erythroleukemia cell lines: Lucena (resistant to vincristine, VCR) and FEPS (resistant to daunorubicin, DNR) derived from the same sensitive cell K562 (non-MDR) to hydrogen peroxide. In addition, we evaluated how the cell lines respond to the oxidizing agent in the absence of VCR/DNR. In absence of VCR, Lucena drastically decreases cell viability when exposed to hydrogen peroxide, while FEPS is not affected even without DNR. To analyze whether selection by different chemotherapeutic agents may generate altered energetic demands, we analyzed the production of reactive oxygen species (ROS) and the relative expression of the glucose transporter 1 gene (glut1). We observed that the selection through DNR apparently generates a higher energy demand than VCR. High levels of transcription factors genes expression (nrf2, hif-1α, and oct4) were kept even when the DNR is withdrawn from the FEPS culture for one month. Together, these results indicate that DNR selects cells with greater ability to express the major transcription factors related to the antioxidant defense system and the main extrusion pump (ABCB1) related to the MDR phenotype. Taking into account that the antioxidant capacity of tumor cells is closely related to resistance to multiple drugs, it is evident that endogenous antioxidant molecules may be targets for the development of new anticancer drugs.

Nrf2 signaling pathway: current status and potential therapeutic targetable role in human cancers

Cancer is a borderless global health challenge that continues to threaten human health. Studies have found that oxidative stress (OS) is often associated with the etiology of many diseases, especially the aging process and cancer. Involved in the OS reaction as a key transcription factor, Nrf2 is a pivotal regulator of cellular redox state and detoxification. Nrf2 can prevent oxidative damage by regulating gene expression with antioxidant response elements (ARE) to promote the antioxidant response process. OS is generated with an imbalance in the redox state and promotes the accumulation of mutations and genome instability, thus associated with the establishment and development of different cancers. Nrf2 activation regulates a plethora of processes inducing cellular proliferation, differentiation and death, and is strongly associated with OS-mediated cancer. What's more, Nrf2 activation is also involved in anti-inflammatory effects and metabolic disorders, neurodegenerative diseases, and multidrug resistance. Nrf2 is highly expressed in multiple human body parts of digestive system, respiratory system, reproductive system and nervous system. In oncology research, Nrf2 has emerged as a promising therapeutic target. Therefore, certain natural compounds and drugs can exert anti-cancer effects through the Nrf2 signaling pathway, and blocking the Nrf2 signaling pathway can reduce some types of tumor recurrence rates and increase sensitivity to chemotherapy. However, Nrf2's dual role and controversial impact in cancer are inevitable consideration factors when treating Nrf2 as a therapeutic target. In this review, we summarized the current state of biological characteristics of Nrf2 and its dual role and development mechanism in different tumor cells, discussed Keap1/Nrf2/ARE signaling pathway and its downstream genes, elaborated the expression of related signaling pathways such as AMPK/mTOR and NF-κB. Besides, the main mechanism of Nrf2 as a cancer therapeutic target and the therapeutic strategies using Nrf2 inhibitors or activators, as well as the possible positive and negative effects of Nrf2 activation were also reviewed. It can be concluded that Nrf2 is related to OS and serves as an important factor in cancer formation and development, thus provides a basis for targeted therapy in human cancers.

Pyrrolidinedione-thiazolidinone hybrid molecules with potent cytotoxic effect in squamous cell carcinoma SCC-15 cells

The hybrid heterocyclic molecules are perspective materials in the development of anticancer drugs. Here, the pyrrolidinedione-thiazolidinone hybrid molecules were designed as potent anticancer agents. This study aimed to investigate the cytotoxic effect of three derivatives 1-(4-hydroxyphenyl)-, 1-(4-chlorophenyl)- and 1-(4-bromophenyl)-3-[5-[2-chloro-3-(4-nitrophenyl)prop-2-enylidene]-4-oxo-2-thioxothiazolidine-3-yl]pyrrolidine-2,5-diones (Les-6287, Les-6294, and Les-6328, respectively), their effect on the production of the reactive oxygen species (ROS), apoptosis induction, and expression of genes - PPARγ, AHR, and NRFL2 - whose products are important in metabolism in human tongue squamous cell carcinoma cells of SCC-15 line. The results of resazurin reduction and lactate dehydrogenase (LDH) release assays proved the toxicity of the tested derivatives for the SCC-15 cells. Les-6287, Les-6294, and Les-6328 inhibited the viability of SCC-15 cells with the half-maximal effective concentration (EC50) in the range of 10.18-32.75 µM at 24 and 48 h treatment. These derivatives reduced the metabolism of SCC-15 cells with the half-maximal inhibitory concentration (IC50) of 6.72-39.85 µM at 24 and 48 h treatment. Les-6287, Les-6294, and Les-6328 reduced the metabolism of normal human keratinocytes of HaCaT line murine fibroblasts of Balb/c 3T3 line to a lesser extent. The compounds used in a range from 50 to 100 µM concentrations decreased ROS production in the SCC-15 cells. The derivatives Les-6287 and Les-6328 decreased the level of expression of mRNA of PPARγ, AHR, and NRFL2 genes in these cells at PPARγ siRNA knockdown and without it. Thus, the anticancer effect of studied hybrid pyrrolidinedione-thiazolidinones in the SCC-15 carcinoma cells is accompanied by a reduction of their metabolic activity and ROS level, and increase in caspase 3 activity. However, these changes are not the result of direct interaction of Les-6287, Les-6294, and Les-6328 with the PPARγ molecule.

The role of the Nrf2/GSH antioxidant system in cisplatin resistance in malignant rhabdoid tumours

PURPOSE

Malignant rhabdoid tumour (MRT) is a rare and aggressive childhood malignancy that occurs in the kidneys or central nervous system and is associated with very poor prognosis. Chemoresistance is a major issue in the treatment of this malignancy leading to an urgent need for a greater understanding of its underlying mechanisms in MRT and novel treatment strategies for MRT patients. The balance between oxidative stress mediated by reactive oxygen species (ROS) and the antioxidant system has become a subject of interest in cancer therapy research. Studies have implicated key players of the antioxidant system in chemotherapeutic including the well-known antioxidant glutathione (GSH) and the transcription factor nuclear erythroid-related factor-2 (Nrf2).   METHODS: This study evaluated the role of these components in the response of MRT cells to treatment with the commonly used chemotherapeutic agent, cisplatin.

RESULTS

This study characterised the basal levels of GSH, ROS and Nrf2 in a panel of MRT cell lines and found a correlation between the expression profile of the antioxidant defence system and cisplatin sensitivity. Results showed that treatment with ROS scavenger N-acetylcysteine (NAC) protected cells from cisplatin-induced ROS and apoptosis. Interestingly, depleting GSH levels with the inhibitor buthionine sulphoximine (BSO) enhanced cisplatin-induced ROS and sensitised cells to cisplatin. Lastly, targeting Nrf2 with the small molecule inhibitor ML385 or by siRNA diminished GSH levels, enhanced ROS and sensitised resistant MRT cells to cisplatin.

CONCLUSIONS

These results suggest that targeting the Nrf2/GSH antioxidant system may present a novel therapeutic strategy to combat chemoresistance in rhabdoid tumours.

Identification of NRF2 Activation as a Prognostic Biomarker in T-Cell Acute Lymphoblastic Leukaemia

The standard-of-care treatment of T-cell acute lymphoblastic leukaemia (T-ALL) with chemotherapy usually achieves reasonable rates of initial complete response. However, patients who relapse or do not respond to conventional therapy show dismal outcomes, with cure rates below 10% and limited therapeutic options. To ameliorate the clinical management of these patients, it is urgent to identify biomarkers able to predict their outcomes. In this work, we investigate whether NRF2 activation constitutes a biomarker with prognostic value in T-ALL. Using transcriptomic, genomic, and clinical data, we found that T-ALL patients with high NFE2L2 levels had shorter overall survival. Our results demonstrate that the PI3K-AKT-mTOR pathway is involved in the oncogenic signalling induced by NRF2 in T-ALL. Furthermore, T-ALL patients with high NFE2L2 levels displayed genetic programs of drug resistance that may be provided by NRF2-induced biosynthesis of glutathione. Altogether, our results indicate that high levels of NFE2L2 may be a predictive biomarker of poor treatment response in T-ALL patients, which would explain the poor prognosis associated with these patients. This enhanced understanding of NRF2 biology in T-ALL may allow a more refined stratification of patients and the proposal of targeted therapies, with the ultimate goal of improving the outcome of relapsed/refractory T-ALL patients.

Cytoprotective Role of Heme Oxygenase-1 in Cancer Chemoresistance: Focus on Antioxidant, Antiapoptotic, and Pro-Autophagy Properties

Chemoresistance remains the foremost challenge in cancer therapy. Targeting reactive oxygen species (ROS) manipulation is a promising strategy in cancer treatment since tumor cells present high levels of intracellular ROS, which makes them more vulnerable to further ROS elevation than normal cells. Nevertheless, dynamic redox evolution and adaptation of tumor cells are capable of counteracting therapy-induced oxidative stress, which leads to chemoresistance. Hence, exploring the cytoprotective mechanisms of tumor cells is urgently needed to overcome chemoresistance. Heme oxygenase-1 (HO-1), a rate-limiting enzyme of heme degradation, acts as a crucial antioxidant defense and cytoprotective molecule in response to cellular stress. Recently, emerging evidence indicated that ROS detoxification and oxidative stress tolerance owing to the antioxidant function of HO-1 contribute to chemoresistance in various cancers. Enhanced HO-1 expression or enzymatic activity was revealed to promote apoptosis resistance and activate protective autophagy, which also involved in the development of chemoresistance. Moreover, inhibition of HO-1 in multiple cancers was identified to reversing chemoresistance or improving chemosensitivity. Here, we summarize the most recent advances regarding the antioxidant, antiapoptotic, and pro-autophagy properties of HO-1 in mediating chemoresistance, highlighting HO-1 as a novel target for overcoming chemoresistance and improving the prognosis of cancer patients.

NFR2/ABC transporter axis in drug resistance of breast cancer cells

Breast cancer is one of the most serious malignancies among women, accounting for about 12% of all cancers. The inherent complexity and heterogeneity of breast cancer results in failure to respond to treatment in the advanced stages of the disease. Breast cancer is caused by several genetic and environmental factors. One of the significant factors involved in the development of breast cancer is oxidative stress, which is generally regulated by nuclear factor erythroid 2-related factor 2 (NRF2). The level of NRF2 expression is low in healthy cells, which maintains the balance of the antioxidant system; however, its expression is higher in cancer cells, which have correlation characteristics such as angiogenesis, stem cell formation, drug resistance, and metastasis. Drug resistance increases with the upregulation of NRF2 expression, which contributes to cell protection. NRF2 controls this mechanism by increasing the expression of ATP-binding cassettes (ABCs). Considering the growing number of studies in this field, we aimed to investigate the relationship between NRF2 and ABCs, as well as their role in the development of drug resistance in breast cancer.

Zinc Finger Protein 90 Knockdown Promotes Cisplatin Sensitivity via Nrf2/HO-1 Pathway in Ovarian Cancer Cell

Our study discussed the role of Zfp90 in ovarian cancer (OC) cell lines' sensitivity to cisplatin. We used two OC cell lines, SK-OV-3 and ES-2, to evaluate their role in cisplatin sensitization. The protein levels of p-Akt, ERK, caspase 3, Bcl-2, Bax, E-cadherin, MMP-2, MMP-9 and other drug resistance-related molecules, including Nrf2/HO-1, were discovered in the SK-OV-3 and ES-2 cells. We also used a human ovarian surface epithelial cell to compare the effect of Zfp90. Our outcomes indicated that cisplatin treatment generates reactive oxygen species (ROS) that modulate apoptotic protein expression. The anti-oxidative signal was also stimulated, which could hinder cell migration. The intervention of Zfp90 could greatly improve the apoptosis pathway and block the migrative pathway to regulate the cisplatin sensitivity in the OC cells. This study implies that the loss of function of Zfp90 might promote cisplatin sensitization in OC cells via regulating the Nrf2/HO-1 pathway to enhance cell apoptosis and inhibit the migrative effect in both SK-OV-3 and ES-2 cells.

Label-Free Quantitative Proteomics Analysis of Adriamycin Selected Multidrug Resistant Human Lung Cancer Cells

The development of drug resistance in lung cancer is a major clinical challenge, leading to a 5-year survival rate of only 18%. Therefore, unravelling the mechanisms of drug resistance and developing novel therapeutic strategies is of crucial importance. This study systematically explores the novel biomarkers of drug resistance using a lung cancer model (DLKP) with a series of drug-resistant variants. In-depth label-free quantitative mass spectrometry-based proteomics and gene ontology analysis shows that parental DLKP cells significantly differ from drug-resistant variants, and the cellular proteome changes even among the drug-resistant subpopulations. Overall, ABC transporter proteins and lipid metabolism were determined to play a significant role in the formation of drug resistance in DKLP cells. A series of membrane-related proteins such as HMOX1, TMB1, EPHX2 and NEU1 were identified to be correlated with levels of drug resistance in the DLKP subpopulations. The study also showed enrichment in biological processes and molecular functions such as drug metabolism, cellular response to the drug and drug binding. In gene ontology analysis, 18 proteins were determined to be positively or negatively correlated with resistance levels. Overall, 34 proteins which potentially have a therapeutic and diagnostic value were identified.

Insights on prospects of nano-siRNA based approaches in treatment of Cancer

siRNA interference, commonly referred to as gene silence, is a biological mechanism that inhibits gene expression in disorders such as cancer. It may enhance the precision, efficacy, and stability of medicines, especially genetic therapies to some extent. However, obstacles such as the delivery of oligonucleotide drugs to inaccessible areas of the body and the prevalence of severe side effects must be overcome. To maximize their potential, it is thus essential to optimize their distribution to target locations and limit their toxicity to healthy cells. The action of siRNA may be harnessed to delete a similar segment of mRNA that encodes a protein that causes sickness. The absence of an efficient delivery mechanism that shields siRNA from nuclease degradation, delivers it to cancer cells and releases it into the cytoplasm of specific cancer cells without causing side effects is currently the greatest obstacle to the practical implementation of siRNA therapy. This article focuses on combinations of siRNA with chemotherapeutic drug delivery systems for the treatment of cancer and gives an overview of several nanocarrier formulations in both research and clinical applications.

A CRISPR screen identifies redox vulnerabilities for KEAP1/NRF2 mutant non-small cell lung cancer

The redox regulator NRF2 is hyperactivated in a large percentage of non-small cell lung cancer (NSCLC) cases, which is associated with chemotherapy and radiation resistance. To identify redox vulnerabilities for KEAP1/NRF2 mutant NSCLC, we conducted a CRISPR-Cas9-based negative selection screen for antioxidant enzyme genes whose loss sensitized cells to sub-lethal concentrations of the superoxide (O2•-) -generating drug β-Lapachone. While our screen identified expected hits in the pentose phosphate pathway, the thioredoxin-dependent antioxidant system, and glutathione reductase, we also identified the mitochondrial superoxide dismutase 2 (SOD2) as one of the top hits. Surprisingly, β-Lapachone did not generate mitochondrial O2•- but rather SOD2 loss enhanced the efficacy of β-Lapachone due to loss of iron-sulfur protein function, loss of mitochondrial ATP maintenance and deficient NADPH production. Importantly, inhibition of mitochondrial electron transport activity sensitized cells to β-Lapachone, demonstrating that these effects may be translated to increase ROS sensitivity therapeutically.

An update of Nrf2 activators and inhibitors in cancer prevention/promotion

NF-E2-related factor 2 (Nrf2) protein is a basic-region leucine zipper transcription factor that defends against endogenous or exogenous stressors. By inducing several cytoprotective and detoxifying gene expressions, Nrf2 can increase the sensitivity of the cells to oxidants and electrophiles. Transient Nrf2 activation, by its specific activators, has protective roles against carcinogenesis and cancer development. However, permanent activation of Nrf2 promotes various cancer properties, comprising malignant progression, chemo/radio resistance, and poor patient prognosis. Taken together, these findings suggest that reaching an optimal balance between paradoxical functions of Nrf2 in malignancy may render a selective improvement to identify therapeutic strategies in cancer treatment. In this review, we describe lately discovered Nrf2 inducers and inhibitors, and their chemopreventive and/or anticancer activities.

The Nrf2 pathway signifies one of the most significant cell defense procedures against exogenous or endogenous stressors. Certainly, by increasing the expression of several cytoprotective genes, the transcription factor Nrf2 can shelter cells and tissues from multiple sources of damage including electrophilic, xenobiotic, metabolic, and oxidative stress. Notably, the aberrant activation or accumulation of Nrf2, a common event in many tumors, confers a selective advantage to cancer cells and is connected to malignant progression, therapy resistance, and poor prognosis. Therefore, lately, Nrf2 has arisen as a hopeful target in treatment of cancer, and many struggles have been made to detect therapeutic strategies intended at disrupting its pro-oncogenic role. By summarizing the outcomes from past and recent studies, this review provided an overview concerning the Nrf2 pathway and the molecular mechanisms causing Nrf2 hyperactivation in cancer cells. Finally, this paper also described some of the most promising therapeutic approaches that have been successfully employed to counteract Nrf2 activity in tumors, with a particular emphasis on the development of natural compounds and the adoption of drug repurposing strategies.

ATP-binding cassette transporters ABCF2 and ABCG9 regulate rice black-streaked dwarf virus infection in its insect vector, Laodelphax striatellus (Fallén)

The majority of plant viral disease is transmitted and spread by insect vectors in the field. The small brown planthopper, Laodelphax striatellus (Fallén), is the only efficient vector for rice black-streaked dwarf virus (RBSDV), a devastating plant virus that infects multiple grain crops, including rice, maize, and wheat. Adenosine triphosphate (ATP)-binding cassette (ABC) transporters participate in various biological processes. However, little is known about whether ABC transporters affect virus infection in insects. In this study, RBSDV accumulation was significantly reduced in L. striatellus after treatment with verapamil, an effective inhibitor of ABC transporters. Thirty-four ABC transporter genes were identified in L. striatellus and expression analysis showed that LsABCF2 and LsABCG9 were significantly upregulated and downregulated, respectively, after RBSDV infection. LsABCF2 and LsABCG9 were expressed during all developmental stages, and LsABCG9 was highly expressed in the midgut of L. striatellus. Knockdown of LsABCF2 promoted RBSDV accumulation, while knockdown of LsABCG9 suppressed RBSDV accumulation in L. striatellus. Our data showed that L. striatellus might upregulate the expression of LsABCF2 and downregulate LsABCG9 expression to suppress RBSDV infection. These results will contribute to understanding the effects of ABC transporters on virus transmission and provide theoretical basis for virus management in the field.

Vinpocetine enhances cisplatin sensitivity of non-small cell lung cancer cells by reducing the nuclear factor erythroid 2-related factor 2 signaling

Vinpocetine exerts pharmacological effects against cardiovascular diseases, while few studies focused on its roles in cancer. The present study investigated the roles of vinpocetine in non-small cell lung cancer (NSCLC) and its relationship with cisplatin resistance. A549 cisplatin-resistant cells (A549/DDP) and nuclear factor erythroid 2-related factor 2 (Nrf2)-overexpressing cell lines were established. 3-(4,5-Dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay was conducted to determine cell viability. Annexin V-propidium iodide assay was conducted to determine cell apoptosis. RT-quantitative PCR and western blot analysis were conducted to determine the levels of mRNA and protein, respectively. NSCLC cell tumor-bearing model was constructed to determine the effects of vinpocetine on tumor growth. Treatment with vinpocetine inhibited cell proliferation and promoted cisplatin-induced cell apoptosis. In addition, treatment with vinpocetine suppressed protein expression of Nrf2 and inhibited messenger RNA levels of heme oxygenase 1 and NAD(P)H dehydrogenase quinone 1 induced by cisplatin. Interestingly, the overexpression of Nrf2 abolished the antiproliferative effects of vinpocetine on NSCLC cells. In vivo data suggested that vinpocetine (50 mg/kg) inhibited tumor growth and enhanced the antitumor effects of cisplatin in the NSCLC cell tumor-bearing model. Vinpocetine enhances cisplatin sensitivity of NSCLC cells in part by suppressing Nrf2 signaling.

Novel Insights on Lipid Metabolism Alterations in Drug Resistance in Cancer

Chemotherapy is one of the primary treatments for most human cancers. Despite great progress in cancer therapeutics, chemotherapy continues to be important for improving the survival of cancer patients, especially for those who has unresectable metastatic tumors or fail to respond to immunotherapy. However, intrinsic or acquired chemoresistance results in tumor recurrence, which remains a major obstacle in anti-cancer treatment. The high prevalence of chemoresistant cancer makes it urgent to deepen our understanding on chemoresistance mechanisms and to develop novel therapeutic strategies. Multiple mechanisms, including drug efflux, enhanced DNA damage reparability, increased detoxifying enzymes levels, presence of cancer stem cells (CSCs), epithelial mesenchymal transition (EMT), autophagy, ferroptosis and resistance to apoptosis, underlie the development of chemoresistance. Recently, accumulating evidence suggests that lipid metabolism alteration is closely related to drug resistance in tumor. Targeting lipid metabolism in combination with traditional chemotherapeutic drugs is a promising strategy to overcome drug resistance. Therefore, this review compiles the current knowledge about aberrant lipid metabolism in chemoresistant cancer, mainly focusing on aberrant fatty acid metabolism, and presents novel therapeutic strategies targeting altered lipid metabolism to overcome chemoresistance in cancer.

Transcription Factor NRF2 Participates in Cell Cycle Progression at the Level of G1/S and Mitotic Checkpoints

Transcription factor NRF2 is a master regulator of the multiple cytoprotective responses that confer growth advantages on a cell. However, its participation in the mechanisms that govern the cell division cycle has not been explored in detail. In this study, we used several standard methods of synchronization of proliferating cells together with flow cytometry and monitored the participation of NRF2 along the cell cycle by the knockdown of its gene expression. We found that the NRF2 levels were highest at S phase entry, and lowest at mitosis. NRF2 depletion promoted both G1 and M arrest. Targeted transcriptomics analysis of cell cycle regulators showed that NRF2 depletion leads to changes in key cell cycle regulators, such as CDK2, TFDP1, CDK6, CDKN1A (p21), CDKN1B (p27), CCNG1, and RAD51. This study gives a new dimension to NRF2 effects, showing their implication in cell cycle progression.

Circular RNA Eps15-homology domain-containing protein 2 induce resistance of renal cell carcinoma to sunitinib via microRNA-4731-5p/ABCF2 axis

Circular RNAs (circRNAs) are linked with the occurrence and progression of renal cell carcinoma (RCC). However, circRNAs’ mechanism in developing resistance to RCC has not been clarified. This research assessed the role and mechanism of circular RNA circ Eps15-homology domain-containing protein 2 (EHD2) in the resistance of sunitinib (SU) to RCC. ACHN, 786-O, 769P, and HEK-293 T cells and RCC tissue samples were used for the investigations. The circEHD2 expression in RCC cells and tissues was determined through RT-qPCR. Association of circEHD2 with RCC histological grade of RCC was done through Chi-square. MiR-4731-5p, ABCF2, and circEHD2 were transfected into RCC cell lines. A dual-luciferase reporter assay was used to determine the interaction between miR-4731-5p, circEHD2, and ABCF2. MTT assay was used to analyze cell viability, while apoptosis was studied using flow cytometry. Colony-formation and transwell experiments were used to assess migration and invasion. The ATP Binding Cassette Subfamily F Member 2 (ABCF2) expression was analyzed through western blot. The results showed increased circEHD2 in SU-resistant RCC tissues and cell lines and implicated in RCC histological grade and SU resistance. Knock-down of circEHD2 down-regulated the resistance of RCC to SU in vitro and vivo; circEHD2 bound to miR-4731-5p to mediate ABCF2 in RCC; ABCF2 rescued the inhibitory effect of circEHD2 knock-down on SU resistance of RCC. In conclusion, circEHD2 enhances RCC resistance to SU via acting as a miR-4731-5p sponge to mediate ABCF2. MiR-4731-5p can target circEHD2 and ABCF2, thus providing a novel and effective therapeutic against renal cell carcinoma.

Role of NRF2 in Ovarian Cancer

Among gynaecologic malignancies, ovarian cancer is one of the most dangerous, with a high fatality rate and relapse due to the occurrence of chemoresistance. Many researchers demonstrated that oxidative stress is involved in tumour occurrence, growth and development. Nuclear factor erythroid 2-related factor 2 (NRF2) is an important transcription factor, playing an important role in protecting against oxidative damage. Increased levels of Reactive Oxygen Species (ROS) activate NRF2 signalling, inducing the expression of antioxidant enzymes, such as haem oxygenase (HO-1), catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD), that protect cells against oxidative stress. However, NRF2 activation in cancer cells is responsible for the development of chemoresistance, inactivating drug-mediated oxidative stress that normally leads to cancer cells’ death. In this review, we report evidence from the literature describing the effect of NRF2 on ovarian cancer, with a focus on its function in drug resistance, NRF2 natural and synthetic modulators and its protective function in normal ovarian preservation.

Oncogenic microRNA-181d binding to OGT contributes to resistance of ovarian cancer cells to cisplatin

Ovarian cancer (OC), a common gynecological cancer, is characterized by a high malignant potential. MicroRNAs (miRNAs or miRs) have been associated with the chemo- or radiotherapeutic resistance of human malignancies. Herein, the current study set out to explore the regulatory mechanism of miR-181d involved in the cisplatin (DDP) resistance of OC cells. Firstly, in-situ hybridization method was performed to identify miR-181d expression in ovarian tissues of DDP-resistant or DDP-sensitive patients. In addition, miR-181d expression in A2780 cells and A2780/DDP cell lines was determined by RT-qPCR. Gain- and loss-of-function experiments were then performed to characterize the effect of miR-181d on OC cell behaviors. We probed the miR-181d affinity to OGT, as well as the downstream glycosylation of KEAP1 and ubiquitination of NRF2. Further, in vivo experiments were performed to define the role of miR-181d in tumor resistance to DDP. miR-181d was highly expressed in the ovarian tissues of DDP-resistant patients and the A2780/DDP cell line. Ectopic expression of miR-181d augmented DDP resistance in OC cells. In addition, miR-181d was found to target the 3′UTR of OGT mRNA, and negatively regulate the OGT expression. Mechanistic results indicated that OGT repressed NRF2 expression through glycosylation of KEAP1, thereby inhibiting the DDP resistance of OC cells. Furthermore, miR-181d negatively orchestrated the OGT/KEAP1/NRF2 axis to enhance the OC resistance to DDP in vivo. Overall, these findings suggest that miR-181d-mediated OGT inhibition restricts the glycosylation of KEAP1, and then reduces the ubiquitination and degradation of NRF2, leading to DDP resistance of OC. This study provides new insights for prevention and control of OC.

Tumour Microenvironment Stress Promotes the Development of Drug Resistance

Multi-drug resistance (MDR) is a leading cause of cancer-related death, and it continues to be a major barrier to cancer treatment. The tumour microenvironment (TME) has proven to play an essential role in not only cancer progression and metastasis, but also the development of resistance to chemotherapy. Despite the significant advances in the efficacy of anti-cancer therapies, the development of drug resistance remains a major impediment to therapeutic success. This review highlights the interplay between various factors within the TME that collectively initiate or propagate MDR. The key TME-mediated mechanisms of MDR regulation that will be discussed herein include (1) altered metabolic processing and the reactive oxygen species (ROS)-hypoxia inducible factor (HIF) axis; (2) changes in stromal cells; (3) increased cancer cell survival via autophagy and failure of apoptosis; (4) altered drug delivery, uptake, or efflux and (5) the induction of a cancer stem cell (CSC) phenotype. The review also discusses thought-provoking ideas that may assist in overcoming the TME-induced MDR. We conclude that stressors from the TME and exposure to chemotherapeutic agents are strongly linked to the development of MDR in cancer cells. Therefore, there remains a vast area for potential research to further elicit the interplay between factors existing both within and outside the TME. Elucidating the mechanisms within this network is essential for developing new therapeutic strategies that are less prone to failure due to the development of resistance in cancer cells.

Reactive oxygen species: Role in carcinogenesis, cancer cell signaling and tumor progression

Cancer is one of the major causes of death in the world and its global burden is expected to continue increasing. In several types of cancers, reactive oxygen species (ROS) have been extensively linked to carcinogenesis and cancer progression. However, studies have reported conflicting evidence regarding the role of ROS in cancer, mostly dependent on the cancer type or the step of the tumorigenic process. We review recent studies describing diverse aspects of the interplay of ROS with cancer in the different stages of cancer progression, with a special focus on their role in carcinogenesis, their importance for cancer cell signaling and their relationship to the most prevalent cancer risk factors.

ATP-binding cassette (ABC) transporters in cancer: A review of recent updates

The ATP-binding cassette (ABC) transporter superfamily is one of the largest membrane protein families existing in wide spectrum of organisms from prokaryotes to human. ABC transporters are also known as efflux pumps because they mediate the cross-membrane transportation of various endo- and xenobiotic molecules energized by ATP hydrolysis. Therefore, ABC transporters have been considered closely to multidrug resistance (MDR) in cancer, where the efflux of structurally distinct chemotherapeutic drugs causes reduced itherapeutic efficacy. Besides, ABC transporters also play other critical biological roles in cancer such as signal transduction. During the past decades, extensive efforts have been made in understanding the structure-function relationship, transportation profile of ABC transporters, as well as the possibility to overcome MDR via targeting these transporters. In this review, we discuss the most recent knowledge regarding ABC transporters and cancer drug resistance in order to provide insights for the development of more effective therapies.

Nutrition Strategy and Life Style in Polycystic Ovary Syndrome-Narrative Review

Here we present an extensive narrative review of the broadly understood modifications to the lifestyles of women with polycystic ovary syndrome (PCOS). The PubMed database was analyzed, combining PCOS entries with causes, diseases, diet supplementation, lifestyle, physical activity, and use of herbs. The metabolic pathways leading to disturbances in lipid, carbohydrate, and hormonal metabolism in targeted patients are described. The article refers to sleep disorders, changes in mental health parameters, and causes of oxidative stress and inflammation. These conditions consistently lead to the occurrence of severe diseases in patients suffering from diabetes, the fatty degeneration of internal organs, infertility, atherosclerosis, cardiovascular diseases, dysbiosis, and cancer. The modification of lifestyles, diet patterns and proper selection of nutrients, pharmacological and natural supplementation in the form of herbs, and physical activity have been proposed. The progress and consequences of PCOS are largely modifiable and depend on the patient’s approach, although we have to take into account also the genetic determinants.

PSMD12 promotes glioma progression by upregulating the expression of Nrf2

Background

Glioma is the most common and aggressive primary brain tumor in adults. Proteasome 26S subunit, non-ATPase 12 (PSMD12), an important subunit in the 26S proteasome, is known to be involved in the growth and apoptosis of breast cancer cells. However, its exact function and underlying molecular mechanisms in glioma remain unknown.

Methods

PSMD12 expression was detected in glioma tissue specimens by immunohistochemistry (IHC) and TCGA database. Overexpression and down-regulation of PSMD12 and Nrf2 were induced in glioma cell lines, and CCK-8 and Transwell assays were used to detect cell proliferation and invasion evaluation, respectively. Xenograft model was used to observe the effect of knockdown of PSMD12 on tumor growth. Immunohistochemical assays and TCGA database were conducted to reveal the relationships between PSMD12 expression and Nrf2. Finally, Western blot and related biological function experiments were used to explore the mechanism of PSMD12 regulating the glioma progression and Nrf2.

Results

We revealed that PSMD12 is upregulated in glioma, especially in high-grade glioma, by analyzing bioinformatics data and clinical specimens. PSMD12 upregulation was associated with poor prognosis in glioma patients. Knockdown of PSMD12 inhibited the growth of glioma cells in vitro and in vivo and decreased their invasion ability, whereas PSMD12 overexpression had the opposite effect. Mechanistic analysis revealed that PSMD12 increased the expression of nuclear factor E2-related factor 2 (Nrf2), which functions as a tumor promoter in the development of glioma. Similar to PSMD12, Nrf2, which exhibited a strong positive correlation with PSMD12, was abnormally elevated in glioma tissues and contributed to worse overall survival (OS). Nrf2 overexpression reversed the inhibitory effects induced by PSMD12 knockdown. Finally, PSMD12 enhanced the proliferation and invasion of glioma cells via Akt signaling-mediated Nrf2 expression.

Conclusions

These results suggest that PSMD12 is considered to be a crucial regulator of the development and progression of glioma and may serve as a potential biomarker or therapeutic target for the treatment of glioma.

Short overview on the relevance of microRNA-reactive oxygen species (ROS) interactions and lipid peroxidation for modulation of oxidative stress-mediated signalling pathways in cancer treatment

OBJECTIVES

Modulation of oxidative stress-mediated signalling pathways is constantly getting more attention as a valuable therapeutic strategy in cancer treatment. Although complexity of redox signalling pathways might represent a major hurdle, the development of advanced -omics technologies allow thorough studies on cancer-specific biology, which is essential to elucidate the impact of these signalling pathways in cancer cells. The scope of our review is to provide updated information about recent developments in cancer treatment.

KEY FINDINGS

In recent years identifying oxidative stress-mediated signalling pathways is a major goal of cancer research assuming it may provide novel therapeutic approaches through the development of agents that may have better tissue penetration and therefore affect specific redox signalling pathways. In this review, we discuss some recent studies focussed on the modulation of oxidative stress-related signalling pathways as a novel anti-cancer treatment, with a particular emphasis on the induction of lipid peroxidation.

CONCLUSIONS

Characterization and modulation of oxidative stress-mediated signalling pathways and lipid peroxidation products will continue to foster novel interest and further investigations, which may pave the way for more effective, selective, and personalized integrative biomedicine treatment strategies.

Nrf2 signaling pathway in cisplatin chemotherapy: Potential involvement in organ protection and chemoresistance

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a vital transcription factor and its induction is of significant importance for protecting against oxidative damage. Increased levels of Reactive Oxygen Species (ROS) stimulate Nrf2 signaling, enhancing the activity of antioxidant enzymes such as catalase, superoxide dismutase and glutathione peroxidase. These enzymes are associated with retarding oxidative stress. On the other hand, Nrf2 activation in cancer cells is responsible for the development of chemoresistance due to disrupting oxidative mediated-cell death by reducing ROS levels. Cisplatin (CP), cis-diamminedichloroplatinum(II), is a potent anti-tumor agent extensively used in cancer therapy, but its frequent application leads to the development of chemoresistance as well. In the present study, association of Nrf2 signaling with chemoresistance to CP and protection against its deleterious effects is discussed. Anti-tumor compounds, mainly phytochemicals, retard chemoresistance by suppressing Nrf2 signaling. Upstream mediators such as microRNAs can regulate Nrf2 expression during CP chemotherapy regimens. Protection against side effects of CP is mediated via activating Nrf2 signaling and its downstream targets activating antioxidant defense system. Protective agents that activate Nrf2 signaling, can ameliorate CP-mediated ototoxicity, nephrotoxicity and neurotoxicity. Reducing ROS levels and preventing cell death are the most important factors involved in alleviating CP toxicity upon Nrf2 activation. As pre-clinical experiments advocate the role of Nrf2 in chemoprotection and CP resistance, translating these findings to the clinic can provide a significant progress in treatment of cancer patients.

Targeting Nrf2 may reverse the drug resistance in ovarian cancer

Background

Acquired resistance to therapeutic drugs has become an important issue in treating ovarian cancer. Studies have shown that the prevalent chemotherapy resistance (cisplatin, paclitaxel etc.) for ovarian cancer occurs partly because of decreased production of reactive oxygen species within the mitochondria of ovarian cancer cells.

Main Body

Nuclear erythroid-related factor-2 (Nrf2) mainly controls the regulation of transcription of genes through the Keap1-Nrf2-ARE signaling pathway and protects cells by fighting oxidative stress and defending against harmful substances. This protective effect is reflected in the promotion of tumor cell growth and their resistance to chemotherapy drugs. Therefore, inhibition of the Nrf2 pathway may reverse drug resistance. In this review, we describe the functions of Nrf2 in drug resistance based on Nrf2-associated signaling pathways determined in previous studies.

Conclusions

Further studies on the relevant mechanisms of Nrf2 may help improve the outcomes of ovarian cancer therapy.

Cisplatin loaded multiwalled carbon nanotubes reverse drug resistance in NSCLC by inhibiting EMT

Background

Lung cancer is one of the important health threats worldwide, of which 5-year survival rate is less than 15%. Non-small-cell lung cancer (NSCLC) accounts for about 80% of all lung cancer with high metastasis and mortality.

Methods

Cisplatin loaded multiwalled carbon nanotubes (Pt-MWNTS) were synthesized and used to evaluate the anticancer effect in our study. The NSCLC cell lines A549 (cisplatin sensitive) and A549/DDP (cisplatin resistant) were used in our in vitro assays. MTT was used to determine Cancer cells viability and invasion were measured by MTT assay and Transwell assay, respectively. Apoptosis and epithelial-mesenchymal transition related marker proteins were measured by western blot. The in vivo anti-cancer effect of Pt-MWNTs were performed in male BALB/c nude mice (4-week old).

Results

Pt-MWNTS were synthesized and characterized by X-ray diffraction, Raman, FT-IR spectroscopy and scan electron microscopy. No significant cytotoxicity of MWNTS was detected in both A549/DDP and A549 cell lines. However, Pt-MWNTS showed a stronger inhibition effect on cell growth than free cisplatin, especially on A549/DDP. We found Pt-MWNTS showed higher intracellular accumulation of cisplatin in A549/DDP cells than free cisplatin and resulted in enhanced the percent of apoptotic cells. Western blot showed that application of Pt-MWNTS can significantly upregulate the expression level of Bax, Bim, Bid, Caspase-3 and Caspase-9 while downregulate the expression level of Bcl-2, compared with free cisplatin. Moreover, the expression level of mesenchymal markers like Vimentin and N-cadherin was more efficiently reduced by Pt-MWNTS treatment in A549/DDP cells than free cisplatin. In vivo study in nude mice proved that Pt-MWNTS more effectively inhibited tumorigenesis compared with cisplatin, although both of them had no significant effect on body weight.

Conclusion

Pt-MWNT reverses the drug resistance in the A549/DDP cell line, underlying its possibility of treating NSCLC with cisplatin resistance.

Nrf2 overexpression increases risk of high tumor mutation burden in acute myeloid leukemia by inhibiting MSH2

Nuclear factor erythroid 2-related factor 2 (Nrf2, also called NFE2L2) plays an important role in cancer chemoresistance. However, little is known about the role of Nrf2 in tumor mutation burden and the effect of Nrf2 in modulating DNA mismatch repair (MMR) gene in acute myeloid leukemia (AML). Here we show that Nrf2 expression is associated with tumor mutation burden in AML. Patients with Nrf2 overexpression had a higher frequency of gene mutation and drug resistance. Nrf2 overexpression protected the AML cells from apoptosis induced by cytarabine in vitro and increased the risk of drug resistance associated with a gene mutation in vivo. Furthermore, Nrf2 overexpression inhibited MutS Homolog 2 (MSH2) protein expression, which caused DNA MMR deficiency. Mechanistically, the inhibition of MSH2 by Nrf2 was in a ROS-independent manner. Further studies showed that an increased activation of JNK/c-Jun signaling in Nrf2 overexpression cells inhibited the expression of the MSH2 protein. Our findings provide evidence that high Nrf2 expression can induce gene instability-dependent drug resistance in AML. This study demonstrates the reason why the high Nrf2 expression leads to the increase of gene mutation frequency in AML, and provides a new strategy for clinical practice.

Targeting Nrf2 for the treatment of Duchenne Muscular Dystrophy

Imbalances in redox homeostasis can result in oxidative stress, which is implicated in various pathological conditions including the fatal neuromuscular disease Duchenne Muscular Dystrophy (DMD). DMD is a complicated disease, with many druggable targets at the cellular and molecular level including calcium-mediated muscle degeneration; mitochondrial dysfunction; oxidative stress; inflammation; insufficient muscle regeneration and dysregulated protein and organelle maintenance. Previous investigative therapeutics tended to isolate and focus on just one of these targets and, consequently, therapeutic activity has been limited. Nuclear erythroid 2-related factor 2 (Nrf2) is a transcription factor that upregulates many cytoprotective gene products in response to oxidants and other toxic stressors. Unlike other strategies, targeted Nrf2 activation has the potential to simultaneously modulate separate pathological features of DMD to amplify therapeutic benefits. Here, we review the literature providing theoretical context for targeting Nrf2 as a disease modifying treatment against DMD.

Nuclear Factor Erythroid 2-Related Factor 2 in Regulating Cancer Metabolism

Significance: Nuclear factor erythroid 2 (NFE2)-related factor 2 (NFE2L2, or NRF2) is a transcription factor predominantly affecting the expression of antioxidant genes. NRF2 plays a significant role in the control of redox balance, which is crucial in cancer cells. NRF2 activation regulates numerous cancer hallmarks, including metabolism, cancer stem cell characteristics, tumor aggressiveness, invasion, and metastasis formation. We review the molecular characteristics of the NRF2 pathway and discuss its interactions with the cancer hallmarks previously listed. Recent Advances: The noncanonical activation of NRF2 was recently discovered, and members of this pathway are involved in carcinogenesis. Further, cancer-related changes (e.g., metabolic flexibility) that support cancer progression were found to be redox- and NRF2 dependent. Critical Issues: NRF2 undergoes Janus-faced behavior in cancers. The pro- or antineoplastic effects of NRF2 are context dependent and essentially based on the specific molecular characteristics of the cancer in question. Therefore, systematic investigation of NRF2 signaling is necessary to clarify its role in cancer etiology. The biggest challenge in the NRF2 field is to determine which cancers can be targeted for better clinical outcomes. Further, large-scale genomic and transcriptomic studies are missing to correlate the clinical outcome with the activity of the NRF2 system. Future Directions: To exploit NRF2 in a clinical setting in the future, the druggable members of the NRF2 pathway should be identified. In addition, it will be important to study how the modulation of the NRF2 system interferes with cytostatic drugs and their combinations.

Genetic screens reveal CCDC115 as a modulator of erythroid iron and heme trafficking

Transferrin-bound iron (TBI), the physiological circulating iron form, is acquired by cells through the transferrin receptor (TfR1) by endocytosis. In erythroid cells, most of the acquired iron is incorporated into heme in the mitochondria. Cellular trafficking of heme is indispensable for erythropoiesis and many other essential biological processes. Comprehensive elucidation of molecular pathways governing and regulating cellular iron acquisition and heme trafficking is required to better understand physiological and pathological processes affecting erythropoiesis. Here, we report the first genome-wide clustered regularly interspaced short palindromic repeats (CRISPR) screens in human erythroid cells to identify determinants of iron and heme uptake, as well as heme-mediated erythroid differentiation. We identified several candidate modulators of TBI acquisition including TfR1, indicating that our approach effectively revealed players mechanistically relevant to the process. Interestingly, components of the endocytic pathway were also revealed as potential determinants of transferrin acquisition. We deciphered a role for the vacuolar-type H+ - ATPase (V- ATPase) assembly factor coiled-coil domain containing 115 (CCDC115) in TBI uptake and validated this role in CCDC115 deficient K562 cells. Our screen in hemin-treated cells revealed perturbations leading to cellular adaptation to heme, including those corresponding to trafficking mechanisms and transcription factors potentiating erythroid differentiation. Pathway analysis indicated that endocytosis and vesicle acidification are key processes for heme trafficking in erythroid precursors. Furthermore, we provided evidence that CCDC115, which we identified as required for TBI uptake, is also involved in cellular heme distribution. This work demonstrates a previously unappreciated common intersection in trafficking of transferrin iron and heme in the endocytic pathway of erythroid cells.

Cellular Responses to Platinum-Based Anticancer Drugs and UVC: Role of p53 and Implications for Cancer Therapy

Chemotherapy is intended to induce cancer cell death through apoptosis and other avenues. Unfortunately, as discussed in this article, moderate doses of genotoxic drugs such as cisplatin typical of those achieved in the clinic often invoke a cytostatic/dormancy rather than cytotoxic/apoptosis response in solid tumour-derived cell lines. This is commonly manifested by an extended apoptotic threshold, with extensive apoptosis only being seen after very high/supralethal doses of such agents. The dormancy response can be associated with senescence-like features, polyploidy and/or multinucleation, depending in part on the p53 status of the cells. In most solid tumour-derived cells, dormancy represents a long-term survival mechanism, ultimately contributing to disease recurrence. This review highlights the nonlinearity of key aspects of the molecular and cellular responses to bulky DNA lesions in human cells treated with chemotherapeutic drugs (e.g., cisplatin) or ultraviolet light-C (a widely used tool for unraveling details of the DNA damage-response) as a function of the level of genotoxic stress. Such data highlight the growing realization that targeting dormant cancer cells, which frequently emerge following conventional anticancer treatments, may represent a novel strategy to prevent or, at least, significantly suppress cancer recurrence.

Nrf2 Inhibitor, Brusatol in Combination with Trastuzumab Exerts Synergistic Antitumor Activity in HER2-Positive Cancers by Inhibiting Nrf2/HO-1 and HER2-AKT/ERK1/2 Pathways

The HER2-targeting antibody trastuzumab has shown effectiveness in treating HER2-positive breast and gastric cancers; however, its responses are limited. Currently, Nrf2 has been deemed as a key transcription factor in promoting cancer progression and resistance by crosstalk with other proliferative signaling pathways. Brusatol as a novel Nrf2 inhibitor has been deemed as an efficacious and safe drug candidate in cancer therapy. In this study, we firstly reported that brusatol exerted the growth-inhibitory effects on HER2-positive cancer cells by regressing Nrf2/HO-1 and HER2-AKT/ERK1/2 signaling pathways in these cells. More importantly, we found that brusatol synergistically enhanced the antitumor activity of trastuzumab against HER2-positive SK-OV-3 and BT-474 cells, which may be attributed to the inhibition of Nrf2/HO-1 and HER2-AKT/ERK1/2 signaling pathways. Furthermore, the synergistic effects were also observed in BT-474 and SK-OV-3 tumor xenografts. In addition, our results showed that trastuzumab markedly enhanced brusatol-induced ROS accumulation and apoptosis level, which could further explain the synergistic effects. To conclude, the study provided a new insight on exploring Nrf2 inhibition in combination with HER2-targeted trastuzumab as a potential clinical treatment regimen in treating HER2-positive cancers.

The Effects of Dietary Supplements that Overactivate the Nrf2/ARE System

Background:

Inflammation is one of the most misunderstood aspects of human health. People have been encouraged to eat foods that have a high antioxidant capacity, and in vitro tests for total antioxidant capacity emerged. They were based on measuring the destruction of oxidized test compounds in direct reactions with the antioxidants in foods. Many dietary supplements arrived in the market. They contained purified antioxidants, such as resveratrol and EGCG that were and still are widely assumed by many to be quite healthy at any dose.

Methods:

The literature on inflammation and the Nrf2/ARE antioxidant system was searched systematically. Articles from prestigious, peer-reviewed journals were obtained and read. The information obtained from them was used to write this review article.

Results:

Over 150 articles and books were read. The information obtained from them showed that very few dietary antioxidants exert their effects by reacting directly with Reactive Oxygen and Nitrogen Species (RONS). Instead, most of the effective antioxidants activate the endogenous Nrf2/ARE antioxidant system. This helps prevent smoldering inflammation and the diseases that it can cause. However, when overactivated or activated constitutively, the Nrf2/ARE antioxidant system can cause some of these diseases, including many types of multidrug resistant cancer, autoimmune, neurodegenerative and cardiovascular diseases.

Conclusion:

Even though green tea, as well as many fruits, vegetables and spices are quite healthy, dietary supplements that deliver much higher doses of antioxidants may not be. People who are diagnosed with cancer and plan to start chemotherapy and/or radiotherapy should probably avoid such supplements. This is because multidrug resistant tumors can hijack and overactivate the Nrf2/ARE antioxidant system.

Insight into the role of p62 in the cisplatin resistant mechanisms of ovarian cancer

Cisplatin is a platinum-based first-line drug for treating ovarian cancer. However, chemotherapy tolerance has limited the efficacy of cisplatin for ovarian cancer patients. Research has demonstrated that cisplatin causes changes in cell survival and death signaling pathways through its interaction with macromolecules and organelles, which indicates that investigation into the DNA off-target effects of cisplatin may provide critical insights into the mechanisms underlying drug resistance. The multifunctional protein p62 works as a signaling hub in the regulation of pro-survival transcriptional factors NF-κB and Nrf2 and connects autophagy and apoptotic signals, which play important roles in maintaining cell homeostasis. In this review, we discuss the role of p62 in cisplatin resistance by exploring p62-associated signaling pathways based on current studies and our work. Insights into these resistance mechanisms may lead to more effective therapeutic strategies for ovarian cancer by targeting p62.