The role of Her2-Nrf2 axis in induction of oxaliplatin resistance in colon cancer cells

HER2 targeted therapy in colorectal Cancer: Current landscape and future directions

Colorectal cancer (CRC) is one of the most common causes of tumor-related deaths globally. Despite recent improvements in the comprehensive therapy of malignancy, metastatic CRC continues to have a poor prognosis. Human epidermal growth factor receptor 2 (HER2) is an established oncogenic driver, which is successfully targeted for breast and gastric cancers. Approximately 5% of CRC patients carry somatic HER2 mutations or gene amplification. In 2019, the U.S. Food and Drug Administration have approved trastuzumab and pertuzumab in combination with chemotherapy for the treatment of HER2-positive metastatic CRC. This approval marked a significant milestone in the treatment of CRC, as HER2-positive patients now have access to targeted therapies that can improve their outcomes. Yet, assessment for HER2 overexpression/ amplification in CRC has not been standardized. The resistance mechanisms to anti-HER2 therapy have been not clearly investigated in CRC. Although many unknowns remain, an improved understanding of these anti-HER2 agents will be essential for advanced CRC. In this review, we provide an overview of the role of HER2 in CRC as an oncogenic driver, a prognostic and predictive biomarker, and a clinically actionable target, as well as the current progress and challenges in the field.

Rhodomyrtus tomentosa as a new anticancer molecular strategy in breast histology via Her2, IL33, EGFR, and MUC1

The prevalence of breast cancer among patients in Indonesia is significant. Indonesian individuals maintain the belief that cancer cannot be cured alone by pharmaceuticals and treatment; herbal remedies must be used in conjunction. Rhodomyrtus tomentosa, also known as Haramonting, is an indigenous Indonesian medicinal plant renowned for its copious antioxidant properties. The objective of study was to assess the impact of haramonting on breast cancer by examining the expression of various biomarker proteins associated with breast cancer. Haramonting was administered to breast cancer model mice at different doses over a period of 30 days. Subsequently, blood and breast samples were obtained for immunohistochemistry and enzyme-linked immunosorbent assays (ELISA). Authors have discovered that there has been a notable rise in the proliferation of epithelial cells in the duct lobes, resulting in the formation of ducts and lobules. Additionally, the researchers discovered that the breasts exhibited distinct clinical and histological alterations. Haramonting possesses the capacity to restore the concentrations of malondialdehyde (MDA) and superoxide dismutase (SOD) to normal levels in the blood serum of rats afflicted with cancer. The histopathological analysis of the breast tissue revealed elevated levels of Her2, IL33, EGFR, and MUC1. The authors also discovered a notable increase in the growth of epithelial cells, with two or more layers of cells reaching towards the centre of the duct. The size of the epithelial cells exhibits variability; however, this state ameliorates with the administration of a dosage of 300 mg/kgBW of this botanical specimen. This study proposes that Haramonting may be effective in treating breast cancer.

Mechanisms and applications of ferroptosis-associated regulators in cancer therapy and drug resistance

Iron is an essential element for almost all living things. Both iron excess and iron deficiency can damage the body's health, but the body has developed complex mechanisms to regulate iron balance. The imbalance of iron homeostasis and lipid peroxidation are important features of ferroptosis. In this review, we summarize the latest regulatory mechanisms of ferroptosis, the roles of relevant regulators that target ferroptosis for cancer therapy, and their relationship to drug resistance. In conclusion, targeting ferroptosis is an important strategy for cancer therapy.

From resistance to resilience: Uncovering chemotherapeutic resistance mechanisms; insights from established models

Despite the tremendous advances in cancer treatment, resistance to chemotherapeutic agents impedes higher success rates and accounts for major relapses in cancer therapy. Moreover, the resistance of cancer cells to chemotherapy is linked to low efficacy and high recurrence of cancer. To stand up against chemotherapy resistance, different models of chemotherapy resistance have been established to study various molecular mechanisms of chemotherapy resistance. Consequently, this review is going to discuss different models of induction of chemotherapy resistance, highlighting the most common mechanisms of cancer resistance against different chemotherapeutic agents, including overexpression of efflux pumps, drug inactivation, epigenetic modulation, and epithelial-mesenchymal transition. This review aims to open a new avenue for researchers to lower the resistance to the existing chemotherapeutic agents, develop new therapeutic agents with low resistance potential, and establish possible prognostic markers for chemotherapy resistance.

Targeted delivery of oxaliplatin via folate-decorated niosomal nanoparticles potentiates resistance reversion of colon cancer cells

Background

Colorectal cancer (CRC) is a prevalent type of cancer, ranking third in incidence and fourth in cancer-related deaths globally. The increase in mortality rates related to colorectal cancer among younger patients is a cause for concern. Chemotherapy is the primary approach for palliative care in colon cancer, but the development of drug resistance limits its effectiveness. Apoptosis is a process of programmed cell death that plays a crucial role in regulating normal cell death and abnormal tissue degeneration in cancer. Genes such as caspase-3, caspase-9, p53, and survivin are involved in apoptosis induction. The field of nanotechnology has presented exciting opportunities for controlled drug delivery and addressing drug resistance in cancer. Niosomes are among the nanocarriers known for their impressive features, making them excellent candidates for drug delivery. In the current study, we investigate whether niosomal nanoparticles coated with FA have the ability to deliver oxaliplatin to drug-resistant cells effectively and potentially resistance reversion in colon cancer cells.

Methods

The niosomal nanoparticles (NPs) were fabricated using the thin-film hydration method and characterized using DLS (Dynamic Light Scattering), FTIR (Fourier Transform Infrared Spectroscopy), SEM (Scanning Electron Microscopy), and AFM (Atomic Force Microscopy) systems. The drug release and drug encapsulation efficiency of the NPs were also determined. An MTT assay was performed on oxaliplatin-resistant cells to determine the IC50 values of the drug in its pure and nano-encapsulated forms. Gene expression of caspase-3, caspase-9, p53, and survivin was investigated using the qRT-PCR (quantitative Reverse Transcription Polymerase Chain Reaction) technique, and cell apoptosis or necrosis was quantified using flow cytometry.

Results

Size, PDI, zeta potential, morphology, drug release, and encapsulation efficiency of fabricated niosomal NPs were acceptable. Oxaliplatin anti-cancer drug showed a higher impact on cancerous cells in nano-encapsulated form. The expression level of caspase-3, caspase-9, and p53 was increased which was in confirmation by flow cytometry results.

Conclusion

Taken together, results of this study demonstrated potential effect of folate decorated oxaliplatin-loaded niosomal NPs to resistance-reversion of Oxaliplatin-resistance colon cancer cells.

Nrf2 inhibition increases sensitivity to chemotherapy of colorectal cancer by promoting ferroptosis and pyroptosis

Oxaliplatin is widely used in chemotherapy for colorectal cancer (CRC), but its sensitivity has become a major obstacle to limiting efficacy. Many literatures reported that Nrf2 activation promoted tumor chemoresistance. In this study, we explored the role and mechanism of Nrf2 inhibition in oxaliplatin-based chemosensitivity of CRC. In vitro experiments, we applied 4-octyl itaconate (4-OI) to activate Nrf2, and used lentivirus to knock down Nrf2 in CRC cell lines. By measuring cell viability, colony formation, apoptosis, reactive oxygen species production, and western blot, we found that oxaliplatin and lobaplatin suppressed the growth of HCT-116 and LOVO cells in a dose-dependent manner, and promoted the expression of Nrf2. 4-OI, an Nrf2 activator, reduced the sensibility of CRC cells to oxaliplatin and lobaplatin, while the knockdown of Nrf2 promoted the sensibility of CRC cells to oxaliplatin and lobaplatin. Through the public databases, we found that the expression of GPX4 in normal tissues was lower compared with cancer tissues in CRC, and the high GPX4 expression predicted a poor prognosis. Meanwhile, we found that oxaliplatin reduced the expression of GPX4 in vitro. The knockdown of Nrf2 enhanced the effects of oxaliplatin to reduce the expression of GPX4 and GSH content, and increase the MDA content, which enhanced oxaliplatin-induced ferroptosis. Subsequently, we found that oxaliplatin promoted the expression of GSDME-N, and induced LDH, IL-1β, and TNF-a release, and the knockdown of Nrf2 aggravated the occurrence of GSMDE-mediated pyroptosis. Finally, we found that the knockdown of Nrf2 enhanced the inhibition of oxaliplatin on HCT116 xenograft tumor growth in vivo. Thus, our study showed that Nrf2 inhibition improved sensitivity to oxaliplatin of CRC cells by promoting ferroptosis and pyroptosis, which provided a new target for overcoming chemoresistance in CRC.

Molecular mechanisms of ROS-modulated cancer chemoresistance and therapeutic strategies

Drug resistance is the main obstacle to achieving a cure in many cancer patients. Reactive oxygen species (ROS) are master regulators of cancer development that act through complex mechanisms. Remarkably, ROS levels and antioxidant content are typically higher in drug-resistant cancer cells than in non-resistant and normal cells, and have been shown to play a central role in modulating drug resistance. Therefore, determining the underlying functions of ROS in the modulation of drug resistance will contribute to develop therapies that sensitize cancer resistant cells by leveraging ROS modulation. In this review, we summarize the notable literature on the sources and regulation of ROS production and highlight the complex roles of ROS in cancer chemoresistance, encompassing transcription factor-mediated chemoresistance, maintenance of cancer stem cells, and their impact on the tumor microenvironment. We also discuss the potential of ROS-targeted therapies in overcoming tumor therapeutic resistance.

Role of the ER-induced UPR pathway, apoptosis, and autophagy in colorectal cancer

When large amounts of misfolded or unfolded proteins accumulate in the endoplasmic reticulum (ER) in response to stress, a process called unfolded protein response (UPR) is activated. The disruption of this process leads to many diseases including diabetes, neurodegenerative diseases, and many cancers. In the process of UPR in response to stress and unfolded proteins, specific signaling pathways are induced in the endoplasmic reticulum and subsequently transmitted to the nucleus and cytoplasm, causing homeostasis and restoring the cell's normal condition with reducing protein translation and synthesis. The UPR response followed by stress enhancement balances cell survival with death, therefore in this condition cells decide either to survive or have the path of apoptosis ahead. However, in some cases, this balance is disturbed and the UPR pathway is chronically activated or not activated and the cell conditions lead to cancer. This study aimed to briefly investigate the association between ER stress, UPR, apoptosis, and autophagy in colorectal cancer (CRC). Moreover, in current study, we will try to demonstrate canonical ways and methods for the treatment of CRC cells with attenuated ER stress.

Drug-induced oxidative stress in cancer treatments: Angel or devil?

Oxidative stress (OS), defined as redox imbalance in favor of oxidant burden, is one of the most significant biological events in cancer progression. Cancer cells generally represent a higher oxidant level, which suggests a dual therapeutic strategy by regulating redox status (i.e., pro-oxidant therapy and/or antioxidant therapy). Indeed, pro-oxidant therapy exhibits a great anti-cancer capability, attributing to a higher oxidant accumulation within cancer cells, whereas antioxidant therapy to restore redox homeostasis has been claimed to fail in several clinical practices. Targeting the redox vulnerability of cancer cells by pro-oxidants capable of generating excessive reactive oxygen species (ROS) has surfaced as an important anti-cancer strategy. However, multiple adverse effects caused by the indiscriminate attacks of uncontrolled drug-induced OS on normal tissues and the drug-tolerant capacity of some certain cancer cells greatly limit their further applications. Herein, we review several representative oxidative anti-cancer drugs and summarize their side effects on normal tissues and organs, emphasizing that seeking a balance between pro-oxidant therapy and oxidative damage is of great value in exploiting next-generation OS-based anti-cancer chemotherapeutics.

CRISPR/Cas9 gene editing: a new approach for overcoming drug resistance in cancer

The CRISPR/Cas9 system is an RNA-based adaptive immune system in bacteria and archaea. Various studies have shown that it is possible to target a wide range of human genes and treat some human diseases, including cancers, by the CRISPR/Cas9 system. In fact, CRISPR/Cas9 gene editing is one of the most efficient genome manipulation techniques. Studies have shown that CRISPR/Cas9 technology, in addition to having the potential to be used as a new therapeutic approach in the treatment of cancers, can also be used to enhance the effectiveness of existing treatments. Undoubtedly, the issue of drug resistance is one of the main obstacles in the treatment of cancers. Cancer cells resist anticancer drugs by a variety of mechanisms, such as enhancing anticancer drugs efflux, enhancing DNA repair, enhancing stemness, and attenuating apoptosis. Mutations in some proteins of different cellular signaling pathways are associated with these events and drug resistance. Recent studies have shown that the CRISPR/Cas9 technique can be used to target important genes involved in these mechanisms, thereby increasing the effectiveness of anticancer drugs. In this review article, studies related to the applications of this technique in overcoming drug resistance in cancer cells will be reviewed. In addition, we will give a brief overview of the limitations of the CRISP/Cas9 gene-editing technique.

In vitro exosomal transfer of Nrf2 led to the oxaliplatin resistance in human colorectal cancer LS174T cells

Chemotherapy resistance is a serious pitfall in the treatment of colon cancers (CCs). Previous studies have found that exosomes (Exo) play a pivotal role in tumor drug resistance via the transfer of proteins and genetic materials to the acceptor cells. To date, the mechanisms orchestrating Exo-derived resistance in cancer cells have been the center of attention. Herein, we aimed to evaluate the role of exosomal nuclear factor erythroid 2-related factor 2 (Nrf2) on oxaliplatin (1-OHP) resistance in human colorectal cancer LS174T cells in vitro. To this end, exosomal-Nrf2-mediated 1-OHP resistance was examined using different assays. Exo was isolated from resistant LS174T cells (LS174T/R) and added to the culture medium of sensitive LS174T cells (LS174T/S). According to our data, LS174T/S cells successfully adsorbed PKH26-Exo driven from LS174T/R cells. Western blotting showed an increased Nrf2 level in Exo isolated from LS174T/R cells compared to LS174T/S cell-derived Exo (p < .05). The incubation of LS174T/S cells with LS174T/R-derived Exo increased half-maximal inhibitory concentration values in response to treatment with 1-OHP (p < .05). Besides this, the apoptotic changes were diminished in LS174T/S cells after incubation with LS174T/R-derived Exo. Of note, the exposure of LS174T/S cells to LS174T/R cell-derived Exo increased the expression of Nrf2 and P-glycoprotein (P-gp) compared to the nontreated LS174T/S cells (p < .05). In line with these changes, lower intracellular Rhodamin 123 content was detected in Exo-treated cells compared to the nontreated LS174T/S cells. Exo increased migration and clonogenic capacity of LS174T/S cells after incubation with Exo-derived from resistant cells. Of note, inhibition of Nrf2 with a specific blocker, brusatol, blunted these effects. Taken together, Exo-mediated transfer of Nrf2 is involved in the development of oxaliplatin resistance in CC cells by upregulating P-gp.

Oxaliplatin induces ferroptosis and oxidative stress in HT29 colorectal cancer cells by inhibiting the Nrf2 signaling pathway

Oxaliplatin is a third-generation platinum drug that is used as first-line chemotherapy for colorectal cancer (CRC). Ferroptosis has been demonstrated to induce cell death and oxidative stress in CRC. The aim of the present study was to investigate whether oxaliplatin could exert anticancer effects on CRC by promoting ferroptosis and oxidative stress. Cell viability and apoptosis were assessed by performing Cell Counting Kit-8 and TUNEL assays, respectively, in the presence or absence of the ferroptosis inducer, erastin. Western blotting was performed to detect the levels of certain nuclear factor erythroid 2-related factor 2 (Nrf2)-associated proteins in HT29 cells treated with oxaliplatin. Furthermore, after treating cells with the Nrf2 activator, NK-252, Fe²⁺ was detected in cells using a commercial kit. Ferroptosis-associated protein expression was also evaluated via western blotting. Additionally, ELISA was adopted to measure the levels of oxidative stress-related factors. Following the addition of erastin, iron ion content, ferroptosis-related protein expression and the levels of oxidative stress-related factors were assayed as described previously. The results of the present study demonstrated that oxaliplatin inhibited viability and the Nrf2 signaling pathway in CRC cells. In addition, oxaliplatin promoted ferroptosis and oxidative stress in CRC cells by inhibiting the Nrf2 signaling pathway. Treatment with oxaliplatin enhanced the effects of erastin on CRC cells by promoting ferroptosis and oxidative stress and inhibiting cell viability. In conclusion, oxaliplatin induced ferroptosis and oxidative stress in CRC cells by inhibiting the Nrf2 signaling pathway.

HNMT Upregulation Induces Cancer Stem Cell Formation and Confers Protection against Oxidative Stress through Interaction with HER2 in Non-Small-Cell Lung Cancer

Background: The treatment of non-small-cell lung cancer (NSCLC) involves platinum-based chemotherapy. It is typically accompanied by chemoresistance resulting from antioxidant properties conferred by cancer stem cells (CSCs). Human epidermal growth factor receptor 2 (HER2) enhances CSCs and antioxidant properties in cancers, including NSCLC. Methods: Here, we elucidated the role of histamine N-methyltransferase (HNMT), a histamine metabolism enzyme significantly upregulated in NSCLC and coexpressed with HER2. HNMT expression in lung cancer tissues was determined using quantitative reverse transcription PCR (RT-qPCR). A publicly available dataset was used to determine HNMT’s potential as an NSCLC target molecule. Immunohistochemistry and coimmunoprecipitation were used to determine HNMT–HER2 correlations and interactions, respectively. HNMT shRNA and overexpression plasmids were used to explore HNMT functions in vitro and in vivo. We also examined miRNAs that may target HNMT and investigated HNMT/HER2’s role on NSCLC cells’ antioxidant properties. Finally, how HNMT loss affects NSCLC cells’ sensitivity to cisplatin was investigated. Results: HNMT was significantly upregulated in human NSCLC tissues, conferred a worse prognosis, and was coexpressed with HER2. HNMT depletion and overexpression respectively decreased and increased cell proliferation, colony formation, tumorsphere formation, and CSCs marker expression. Coimmunoprecipitation analysis indicated that HNMT directly interacts with HER2. TARGETSCAN analysis revealed that HNMT is a miR-223 and miR-3065-5p target. TBHp treatment increased HER2 expression, whereas shHNMT disrupted the Nuclear factor erythroid 2-related factor 2 (Nrf2)/ hemeoxygenase-1 (HO-1)/HER2 axis and increased reactive oxygen species accumulation in NSCLC cells. Finally, shHNMT sensitized H441 cells to cisplatin treatment in vitro and in vivo. Conclusions: Therefore, HNMT upregulation in NSCLC cells may upregulate HER2 expression, increasing tumorigenicity and chemoresistance through CSCs maintenance and antioxidant properties. This newly discovered regulatory axis may aid in retarding NSCLC progression and chemoresistance.

The Impact of Nrf2 Silencing on Nrf2-PD-L1 Axis to Overcome Oxaliplatin Resistance and Migration in Colon Cancer Cells

Background:

Nuclear factor-erythroid 2-related factor 2 (Nrf2) plays a key role in promoting chemoresistance in various cancers. PD-L1 is one of the downstream targets of the Nrf2 signaling pathway. This molecule has some beneficial impacts on tumors growth by inhibition of the immune system. This study aimed to investigate the potential role of the Nrf2-PD-L1 axis in the promotion of oxaliplatin resistance in colon cancer cells.

Methods:

We examined Nrf2, PD- L1, and CD80 expression in the tumor and margin tissue samples from CRC patients. After that role of the Nrf2-PD-L1 axis in promotion of Oxaliplatin resistance was investigated.

Results:

Our data revealed that Nrf2 and PD-L1 mRNA expressions were markedly higher in tumor tissues compared to margin tissues. The PD-L1 mRNA expression level was also increased in the resistant cells. However, Nrf2 expression was decreased in SW480/Res cells and increased in LS174T/Res cells. The inhibition of Nrf2 through siRNA treatment in SW480/Res and LS174T/Res cells has decreased the IC50 values of oxaliplatin. Inhibition of the Nrf2 has significantly increased the oxaliplatin-induced apoptosis, and reduced the migration in SW480/Res cells.

Conclusion:

It is suggested that effective inhibition of Nrf2-PD-L1 signaling pathways can be considered as a novel approach to improve oxaliplatin efficacy in colon cancer patients.

Synthesis and Biological Evaluation of New N-Acyl-α-amino Ketones and 1,3-Oxazoles Derivatives

In order to develop novel bioactive substances with potent activities, some new valine-derived compounds incorporating a 4-(phenylsulfonyl)phenyl fragment, namely, acyclic precursors from N-acyl-α-amino acids and N-acyl-α-amino ketones classes, and heterocycles from the large family of 1,3-oxazole-based compounds, were synthesized. The structures of the new compounds were established using elemental analysis and spectral (UV-Vis, FT-IR, MS, NMR) data, and their purity was checked by reversed-phase HPLC. The newly synthesized compounds were evaluated for their antimicrobial and antibiofilm activities, for toxicity on D. magna, and by in silico studies regarding their potential mechanism of action and toxicity. The 2-aza-3-isopropyl-1-[4-(phenylsulfonyl)phenyl]-1,4-butanedione 4b bearing a p-tolyl group in 4-position exhibited the best antibacterial activity against the planktonic growth of both Gram-positive and Gram-negative strains, while the N-acyl-α-amino acid 2 and 1,3-oxazol-5(4H)-one 3 inhibited the Enterococcus faecium biofilms. Despite not all newly synthesized compounds showing significant biological activity, the general scaffold allows several future optimizations for obtaining better novel antimicrobial agents by the introduction of various substituents on the phenyl moiety at position 5 of the 1,3-oxazole nucleus.

A New Oxaliplatin Resistance-Related Gene Signature With Strong Predicting Ability in Colon Cancer Identified by Comprehensive Profiling

Numerous colon cancer cases are resistant to chemotherapy based on oxaliplatin and suffer from relapse. A number of survival- and prognosis-related biomarkers have been identified based on database mining for patients who develop drug resistance, but the single individual gene biomarker cannot attain high specificity and sensitivity in prognosis prediction. This work was conducted aiming to establish a new gene signature using oxaliplatin resistance-related genes to predict the prognosis for colon cancer. To this end, we downloaded gene expression profile data of cell lines that are resistant and not resistant to oxaliplatin from the Gene Expression Omnibus (GEO) database. Altogether, 495 oxaliplatin resistance-related genes were searched by weighted gene co-expression network analysis (WGCNA) and differential expression analysis. As suggested by functional analysis, the above genes were mostly enriched into cell adhesion and immune processes. Besides, a signature was built based on four oxaliplatin resistance-related genes selected from the training set to predict the overall survival (OS) by stepwise regression and least absolute shrinkage and selection operator (LASSO) Cox analysis. Relative to the low risk score group, the high risk score group had dismal OS (P < 0.0001). Moreover, the area under the curve (AUC) value regarding the 5-year OS was 0.72, indicating that the risk score was accurate in the prediction of OS for colon cancer patients (AUC >0.7). Additionally, multivariate Cox regression suggested that the signature constructed based on four oxaliplatin resistance-related genes predicted the prognosis for colon cancer cases [hazard ratio (HR), 2.77; 95% CI, 2.03–3.78; P < 0.001]. Finally, external test sets were utilized to further validate the stability and accuracy of oxaliplatin resistance-related gene signature for prognosis of colon cancer patients. To sum up, this study establishes a signature based on four oxaliplatin resistance-related genes for predicting the survival of colon cancer patients, which sheds more light on the mechanisms of oxaliplatin resistance and helps identify colon cancer cases with a dismal prognostic outcome.

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

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

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.

Emerging role of NRF2 in ROS-mediated tumor chemoresistance

Chemoresistance is a central cause for the tumor management failure. Cancer cells disrupt the redox homeostasis through reactive oxygen species (ROS) regulatory mechanisms, leading to tumor progression and chemoresistance. The transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) is a master regulator of neutralizing cellular ROS and restoring redox balance. Understanding the role of NRF2 in ROS-mediated chemoresistance can be helpful in the development of chemotherapy strategies with better efficiency. In this review, we sum up the roles of ROS in the development of chemoresistance to classical chemotherapy agents including cisplatin, 5-fluorouracil, gemcitabine, oxaliplatin, paclitaxel, and doxorubicin, and how to overcome ROS-mediated tumor chemoresistance by targeting NRF2. Finally, we propose that targeting NRF2 might be a promising strategy to resist ROS-driven chemoresistance and acquire better efficacy in cancer treatment.

Kinome scale profiling of venom effects on cancer cells reveals potential new venom activities

The search for novel and relevant cancer therapeutics is continuous and ongoing. Cancer adaptations, resulting in therapeutic treatment failures, fuel this continuous necessity for new drugs to novel targets. Recently, researchers have started to investigate the effect of venoms and venom components on different types of cancer, investigating their mechanisms of action. Receptor tyrosine kinases (RTKs) comprise a family of highly conserved and functionally important druggable targets for cancer therapy. This research exploits the novelty of complex venom mixtures to affect phosphorylation of the epidermal growth factor receptor (EGFR) and related RTK family members, dually identifying new activities and unexplored avenues for future cancer and venom research. Six whole venoms from diverse species taxa, were evaluated for their ability to illicit changes in the phosphorylated expression of a panel of 49 commonly expressed RTKs. The triple negative breast cancer cell line MDA-MB-468 was treated with optimised venom doses, pre-determined by SDS PAGE and Western blot analysis. The phosphorylated expression levels of 49 RTKs in response to the venoms were assessed with the use of Human Phospho-RTK Arrays and analysed using ImageLab 5.2.1 analysis software (BioRad). Inhibition of EGFR phosphorylation occurred with treatment of venom from Acanthoscurria geniculata (Theraphosidae), Heterometrus swammerdami (Scorpionidae), Crotalus durissus vegrandis (Crotalidae) and Naja naja (Elapidae). Western green mamba Dendroaspis viridis venom increased EGFR phosphorylation. Eph, HGFR and HER were the most affected receptor families by venoms. Whilst the importance of these changes in terms of effect on MDA-MB-468 cells' long-term viability and functionality are still unclear, the findings present exciting opportunities for further investigation as potential drug targets in cancer and as tools to understand better how these pathways interact.

Phytochemical compounds targeting on Nrf2 for chemoprevention in colorectal cancer

Colorectal cancer (CRC) has become one of the major factors of tumor-related morbidity and mortality in the world because of its poor prognosis and consequences of metastatic spread. Currently, chemoprevention has been considered as a way of preventing cancer who takes advantage of plant phytochemicals and synthetic compounds. Phytochemical compounds are receiving much considerable attention for their ability in chemoprevention due to low toxicity and cost. For strategies of chemoprevention, keeping the balance of internal and external environment in cells or tissues is important. Hence, it is particularly important to eliminate overmuch carcinogens and carcinogenic metabolites by phase 2 detoxifying enzymes and antioxidant enzymes such as glutathione S-transferase (GST), heme oxygenase-1(HO-1) and so on. Nuclear factor-erythroid 2-related factor 2 (Nrf2) plays a key role in regulating these enzymes via mediating antioxidant response elements (ARE). In this review, we collected recent studies of phytochemical compounds targeting on Nrf2 in CRC treatment. We summarized the mechanisms of these compounds in activating Nrf2, and their effects on chemotherapeutic agents.

The potential impact of trigonelline loaded micelles on Nrf2 suppression to overcome oxaliplatin resistance in colon cancer cells

Nuclear factor erythroid 2-related factor 2 (Nrf2) has a pivotal role in promoting chemoresistance by regulation of antioxidants and detoxification enzymes. Trigonelline is one of the major alkaloids in raw coffee which has been recently introduced as potent inhibitor of Nrf2. This study investigated the role of trigonelline and trigonelline loaded micelles in Nrf2 inhibition to break down oxaliplatin resistance in colon cancer cells. The PCL-PEG-PCL and PLA-PCL-PEG-PCL-PLA copolymers and trigonelline loaded micelles were prepared and characterized for fourier transforms infrared (FTIR), hydrogen nuclear magnetic resonance (¹H-NMR), carbon nuclear magnetic resonance (¹³C-NMR) spectroscopy, particle size, zeta potential, scanning electron microscopy (SEM) and entrapment efficiency. Cell viability and apoptosis were evaluated by using MTT and flow cytometry assays, respectively. Nrf2, MRP1, NQO1, HO-1, Bax, and Bcl2 gene expressions were examined by qRT-PCR. Our results revealed that micelles had spherical shapes with narrow sizes and zeta potential indexes of - 9.06 ± 6.94 mV for trigonelline loaded 3Block and - 7.47 ± 6.08 mV for trigonelline loaded 5Block micelles. After Nrf2 inhibition by trigonelline, antioxidant response element (ARE) related gene expressions were decreased (p < 0.05) with a significantly higher impact by trigonelline loaded micelles (p < 0.05). Trigonelline loaded micelles also strongly decreased IC50 value of oxaliplatin in resistant colon cancer cells (p < 0.05). Furthermore, trigonelline loaded 5Block micelle increased oxaliplatin-induced apoptosis in a Nrf2/ARE dependent manner. Altogether, the current study suggests that delivery of trigonelline loaded micelles as potent Nrf2 inhibitors can be considered as a promising strategy to overcome oxaliplatin resistance in colon cancer patients.

PD-1/PD-L1-dependent immune response in colorectal cancer

Colorectal cancer (CRC) is still considered as the third most frequent cancer in the world. Microsatellite instability (MSI), inflammation, and microRNAs have been demonstrated as the main contributing factors in CRC. Subtype 1 CRC is defined by NK cells infiltration, induction of Th1 lymphocyte and cytotoxic T cell responses as well as upregulation of immune checkpoint proteins including programmed cell death-1 (PD-1). Based on the diverse features of CRC, such as the stage and localization of the tumor, several treatment approaches are available. However, the efficiency of these treatments may be decreased due to the development of diverse resistance mechanisms. It has been proven that monoclonal antibodies (mAbs) can increase the effectiveness of CRC treatments. Nowadays, several mAbs including nivolumab and pembrolizumab have been approved for the treatment of CRC. Immune checkpoint receptors including PD-1 can be inhibited by these antibodies. Combination therapy gives an opportunity for advanced treatment for CRC patients. In this review, an update has been provided on the molecular mechanisms involved in MSI colorectal cancer immune microenvironment by focusing on PD-ligand 1 (PD-L1) and treatment of patients with advanced immunotherapy, which were examined in the different clinical trial phases. Considering induced expression of PD-L1 by conventional chemotherapeutics, we have summarized the role of PD-L1 in CRC, the chemotherapy effects on the PD-1/PD-L1 axis and novel combined approaches to enhance immunotherapy of CRC by focusing on PD-L1.

Redox-Mediated Mechanism of Chemoresistance in Cancer Cells

Cellular reactive oxygen species (ROS) status is stabilized by a balance of ROS generation and elimination called redox homeostasis. ROS is increased by activation of endoplasmic reticulum stress, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase family members and adenosine triphosphate (ATP) synthesis of mitochondria. Increased ROS is detoxified by superoxide dismutase, catalase, and peroxiredoxins. ROS has a role as a secondary messenger in signal transduction. Cancer cells induce fluctuations of redox homeostasis by variation of ROS regulated machinery, leading to increased tumorigenesis and chemoresistance. Redox-mediated mechanisms of chemoresistance include endoplasmic reticulum stress-mediated autophagy, increased cell cycle progression, and increased conversion to metastasis or cancer stem-like cells. This review discusses changes of the redox state in tumorigenesis and redox-mediated mechanisms involved in tolerance to chemotherapeutic drugs in cancer.

SMYD2-OE promotes oxaliplatin resistance in colon cancer through MDR1/P-glycoprotein via MEK/ERK/AP1 pathway

Background

SET and MYND domain-containing protein 2 (SMYD2-OE) plays an important role in cancer development through methylating histone and non-histone proteins. However, little is known about the relevance of SMYD2-OE in colon cancer. Moreover, oxaliplatin (L-OHP) is applied as first line for colon cancer chemotherapy, but drug resistance restricts its efficacy. Unexpectedly, the mechanism of L-OHP resistance in colon cancer remains unclear. In this study, we investigated the relationship of SMYD2-OE expression and L-OHP resistance in colon cancer and further explored the underlying mechanism linking SMYD2-OE, L-OHP resistance, and colon cancer.

Materials and methods

Expression levels of SMYD2-OE in colon cancer tissues of patients were tested. In vitro and in vivo assays were conducted to explore the function and mechanism of SMYD2-OE in colon cancer sensitivity to L-OHP.

Results

SMYD2-OE was overexpressed in colon cancer tissues compared with non-neoplastic tissues and associated with poor prognosis of patients with colon cancer after L-OHP-based chemotherapy. Knockdown of SMYD2-OE increased colon cancer sensitivity to L-OHP in vitro and in vivo. However, SMYD2-OE overexpression promoted L-OHP resistance in colon cancer cell in vitro. In addition, SMYD2-OE could upregulate MDR1/P-glycoprotein expression depending on MEK/ERK/AP-1 signaling pathway activity.

Conclusion

These results imply that SMYD2-OE promotes L-OHP resistance in colon cancer by regulating MDR1/P-glycoprotein through MEK/ERK/AP-1 signaling pathway, providing a potential strategy to sensitize chemotherapy by SMYD2-OE knockdown in colon cancer treatment.