Role of Reactive Oxygen Species in the Abrogation of Oxaliplatin Activity by Cetuximab in Colorectal Cancer

Cytotoxicity, Cell Line Selectivity and Proapoptotic Activity of New Anticancer Agents Derived From N,N'-Functionalised Benzimidazolium Salts and Their Silver(I)-N-Heterocyclic Carbene Complexes

A new series of N-decyl-N'-benzylbenzimidazolium N-heterocyclic carbene (NHC) precursors and their mononuclear silver(I)-NHC complexes were synthesised and characterised. The benzyl group was functionalised with various para substituents (H, CH3, F, Cl, Br, CN, NO2). The effect of these substituents on cytotoxicity and cell line selectivity against human cervical cancer (HeLa), oestrogen-positive human breast cancer (MCF-7), and normal skin fibroblasts (Hs-27) was investigated. All compounds exhibited significant growth inhibition against the tested cell lines. The activity and selectivity of the compounds were influenced by the para substituents and the type of cell line. The electron-donating methylated NHC precursor and its silver complex generally demonstrated higher growth inhibition potentials than the analogues with electron-withdrawing groups, except in two cases where the fluorinated compounds were more potent against Hs-27 and HeLa, while the chlorinated NHC precursor was more active against MCF-7. Notably, all compounds, particularly the silver(I)-NHC complexes, were more active towards MCF-7 but less toxic towards Hs-27. The methyl-, bromo-, and cyano-containing silver(I)-NHC complexes broadened the safety windows against MCF-7 (selectivity indices ≥ 3). The most selective (against MCF-7) chlorinated NHC precursor and its silver(I)-NHC exhibited ROS-mediated proapoptotic activity, which indicated that these compounds promoted cell death by inducing intracellular ROS formation and accumulation. Our findings highlight the potential use of silver(I)-NHC complexes in the design and development of safe and selective anticancer agents.

An adverse outcome pathway for DNA adduct formation leading to kidney failure

An Adverse Outcome Pathway (AOP) is a conceptual framework in toxicology and risk assessment that outlines the series of events from a chemical's molecular interaction to the resulting adverse health effect. This framework offers a structured approach to organizing biological knowledge, making it especially useful for understanding the mechanisms through which chemicals cause harm. Following a comprehensive analysis of the literature, an AOP was elucidated for key events linking DNA adduct formation, caused by compounds such as platinum anticancer drugs, to tubular necrosis, resulting in kidney failure. Currently, cisplatin, carboplatin and oxaliplatin are the three most utilised Pt-based drugs used globally for the treatment of cancer. The hydrolysis of platinum anticancer agents post-cellular uptake yields electrophilic intermediates that covalently bind to nucleophilic sites on DNA to form adducts that represent the molecular initiating event. When DNA repair mechanisms become unbalanced, the nephrotoxic response following the formation of DNA adducts leads to DNA damage and mitochondrial dysfunction. These events promote the generation and release of reaction oxygen species (ROS) to induce oxidative stress, causing cell death and inflammation. Upon detachment from the basement membrane, these compromised cells are subsequently deposited in the tubular lumen. Tubular obstruction and inflammatory responses to proximal tubule insult can lead to secondary toxicity and tubular necrosis, further exacerbating kidney injury and precipitating a progressive decline of renal function, finally resulting in kidney failure.

The MondoA-dependent TXNIP/GDF15 axis predicts oxaliplatin response in colorectal adenocarcinomas

Chemotherapy, the standard of care treatment for cancer patients with advanced disease, has been increasingly recognized to activate host immune responses to produce durable outcomes. Here, in colorectal adenocarcinoma (CRC) we identify oxaliplatin-induced Thioredoxin-Interacting Protein (TXNIP), a MondoA-dependent tumor suppressor gene, as a negative regulator of Growth/Differentiation Factor 15 (GDF15). GDF15 is a negative prognostic factor in CRC and promotes the differentiation of regulatory T cells (Tregs), which inhibit CD8 T-cell activation. Intriguingly, multiple models including patient-derived tumor organoids demonstrate that the loss of TXNIP and GDF15 responsiveness to oxaliplatin is associated with advanced disease or chemotherapeutic resistance, with transcriptomic or proteomic GDF15/TXNIP ratios showing potential as a prognostic biomarker. These findings illustrate a potentially common pathway where chemotherapy-induced epithelial oxidative stress drives local immune remodeling for patient benefit, with disruption of this pathway seen in refractory or advanced cases.

TRPM3 as a novel target to alleviate acute oxaliplatin-induced peripheral neuropathic pain

ABSTRACT

Chemotherapy-induced peripheral neuropathic pain (CIPNP) is an adverse effect observed in up to 80% of patients of cancer on treatment with cytostatic drugs including paclitaxel and oxaliplatin. Chemotherapy-induced peripheral neuropathic pain can be so severe that it limits dose and choice of chemotherapy and has significant negative consequences on the quality of life of survivors. Current treatment options for CIPNP are limited and unsatisfactory. TRPM3 is a calcium-permeable ion channel functionally expressed in peripheral sensory neurons involved in the detection of thermal stimuli. Here, we focus on the possible involvement of TRPM3 in acute oxaliplatin-induced mechanical allodynia and cold hypersensitivity. In vitro calcium microfluorimetry and whole-cell patch-clamp experiments showed that TRPM3 is functionally upregulated in both heterologous and homologous expression systems after acute (24 hours) oxaliplatin treatment, whereas the direct application of oxaliplatin was without effect. In vivo behavioral studies using an acute oxaliplatin model for CIPNP showed the development of cold and mechano hypersensitivity in control mice, which was lacking in TRPM3 deficient mice. In addition, the levels of protein ERK, a marker for neuronal activity, were significantly reduced in dorsal root ganglion neurons derived from TRPM3 deficient mice compared with control after oxaliplatin administration. Moreover, intraperitoneal injection of a TRPM3 antagonist, isosakuranetin, effectively reduced the oxaliplatin-induced pain behavior in response to cold and mechanical stimulation in mice with an acute form of oxaliplatin-induced peripheral neuropathy. In summary, TRPM3 represents a potential new target for the treatment of neuropathic pain in patients undergoing chemotherapy.

Treatment outcome comparisons of first-line targeted therapy in patients with KRAS wild-type metastatic colorectal cancer: A nationwide database study

BACKGROUND

The first-line systemic therapy for metastatic colorectal cancer (mCRC) is a combination of one targeted therapy agent and a chemotherapy doublet. Whether bevacizumab or anti-epidermal growth factor receptor (anti-EGFR) monoclonal antibody (mAb) is the more effective addition to a chemotherapy doublet as the first-line treatment for inoperable KRAS wild-type mCRC remains controversial in prior clinical trials. Moreover, the association between the sidedness of primary tumors and the efficacy of anti-EGFR mAb needs to be addressed.

METHODS

We established a cohort of patients with KRAS wild-type mCRC who were treated with first-line targeted therapy plus doublet chemotherapy between 2013 and 2018 using Taiwan's National Health Insurance Research Database. Secondary surgery was defined as either resection of primary tumors, liver metastases, lung metastases, or radiofrequency ablation.

RESULTS

A total of 6482 patients were included; bevacizumab and anti-EGFR mAb were the first-line targeted therapies in 3334 (51.4%) and 3148 (48.6%) patients, respectively. Compared with those who received bevacizumab, patients who received anti-EGFR mAb exhibited significantly longer overall survival (OS; median, 23.1 vs. 20.2 months, p = 0.012) and time to treatment failure (TTF; median, 11.3 vs. 10 months, p < 0.001). Among left-sided primary tumors, the OS and TTF benefits of anti-EGFR mAb remained. Among right-sided primary tumors, the OS and TTF were similar regardless of the type of targeted therapy. In multivariate analyses, first-line anti-EGFR mAb therapy remained an independent predictor of longer OS and TTF for left-sided primary tumors. Patients who received anti-EGFR mAb were more likely to receive secondary surgery (29.6% vs. 22.6%, p < 0.0001) than patients who received bevacizumab.

CONCLUSION

For patients who received first-line doublet chemotherapy for KRAS wild-type mCRC, adding anti-EGFR mAb was associated with significantly longer OS and TTF, especially for left-sided primary tumors.

Gastric Cancer Vascularization and the Contribution of Reactive Oxygen Species

Blood vessels are the most important way for cancer cells to survive and diffuse in the body, metastasizing distant organs. During the process of tumor expansion, the neoplastic mass progressively induces modifications in the microenvironment due to its uncontrolled growth, generating a hypoxic and low pH milieu with high fluid pressure and low nutrients concentration. In such a particular condition, reactive oxygen species play a fundamental role, enhancing tumor proliferation and migration, inducing a glycolytic phenotype and promoting angiogenesis. Indeed, to reach new sources of oxygen and metabolites, highly aggressive cancer cells might produce a new abnormal network of vessels independently from endothelial cells, a process called vasculogenic mimicry. Even though many molecular markers and mechanisms, especially in gastric cancer, are still unclear, the formation of such intricate, leaky and abnormal vessel networks is closely associated with patients' poor prognosis, and therefore finding new pharmaceutical solutions to be applied along with canonical chemotherapies in order to control and normalize the formation of such networks is urgent.

PANTHER: AZD8931, inhibitor of EGFR, ERBB2 and ERBB3 signalling, combined with FOLFIRI: a Phase I/II study to determine the importance of schedule and activity in colorectal cancer

BACKGROUND

Epidermal growth factor receptor (EGFR) is a therapeutic target to which HER2/HER3 activation may contribute resistance. This Phase I/II study examined the toxicity and efficacy of high-dose pulsed AZD8931, an EGFR/HER2/HER3 inhibitor, combined with chemotherapy, in metastatic colorectal cancer (CRC).

METHODS

Treatment-naive patients received 4-day pulses of AZD8931 with irinotecan/5-FU (FOLFIRI) in a Phase I/II single-arm trial. Primary endpoint for Phase I was dose limiting toxicity (DLT); for Phase II best overall response. Samples were analysed for pharmacokinetics, EGFR dimers in circulating exosomes and Comet assay quantitating DNA damage.

RESULTS

Eighteen patients received FOLFIRI and AZD8931. At 160 mg bd, 1 patient experienced G3 DLT; 160 mg bd was used for cohort expansion. No grade 5 adverse events (AE) reported. Seven (39%) and 1 (6%) patients experienced grade 3 and grade 4 AEs, respectively. Of 12 patients receiving 160 mg bd, best overall response rate was 25%, median PFS and OS were 8.7 and 21.2 months, respectively. A reduction in circulating HER2/3 dimer in the two responding patients after 12 weeks treatment was observed.

CONCLUSIONS

The combination of pulsed high-dose AZD8931 with FOLFIRI has acceptable toxicity. Further studies of TKI sequencing may establish a role for pulsed use of such agents rather than continuous exposure.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov number: NCT01862003.

KCNQ1OT1 polymorphism rs35622507 and methylation status of KCNQ1OT1 promoter influence the drug resistance to L-OHP

Background: LncRNA potassium voltage-gated channel subfamily Q member 1 opposite strand/antisense transcript 1 (KCNQ1OT1) has been reported to promote resistance to chemotherapy in colon cancer by inhibiting the expression of miR-34a. And the methylation of KCNQ1OT1 was also reported in the pathogenesis of various diseases. In this study, we aimed to study the combined effect of allele variation of KCNQ1OT1 polymorphism rs35622507 and methylation status of KCNQ1OT1 promoter in the treatment of colon cancer.

Methods: The expression levels of KCNQ1OT1, miR-34a, and ATG4B mRNA were assessed by qRT-PCR. ATG4B protein expression was analyzed by Western blot analysis. TUNEL and MTT assay were performed to examine the cell apoptosis and viability. Luciferase assays revealed the relationship between KCNQ1OT1, miR-34a and ATG4B.

Results: Carrier of allele 10 and methylated promoter in KCNQ1OT1 was associated with decreased KCNQ1OT1/ATG4B expression, increased miR-34a expression and enhanced apoptosis in colon cancer tissue samples. And subsequent luciferase assay showed that miR-34a could bind to KCNQ1OT1 and ATG4B at specific binding sites. The knockdown of KCNQ1OT1 significantly suppressed the KCNQ1OT1/ATG4B expression, improved the miR-34a expression and reduced the viability of HCT116 and SW480 cells. The over-expression of ATG4B notably restored the cell viability loss and apoptosis increase induced by the knockdown of KCNQ1OT1. Moreover, oxaliplatin (L-OHP) treatment elevated the apoptosis of HCT116 and SW480 cells.

Conclusions: The drug resistance in the treatment of colon cancer is most reduced in patients carrying allele 10 and methylated in KCNQ1OT1 promoter. This function is accomplished by the signaling pathway of KCNQ1OT1/miR-34a/ATG4B.

Naturally Occurring Antioxidant Therapy in Alzheimer's Disease

It is estimated that the prevalence rate of Alzheimer's disease (AD) will double by the year 2040. Although currently available treatments help with symptom management, they do not prevent, delay the progression of, or cure the disease. Interestingly, a shared characteristic of AD and other neurodegenerative diseases and disorders is oxidative stress. Despite profound evidence supporting the role of oxidative stress in the pathogenesis and progression of AD, none of the currently available treatment options address oxidative stress. Recently, attention has been placed on the use of antioxidants to mitigate the effects of oxidative stress in the central nervous system. In preclinical studies utilizing cellular and animal models, natural antioxidants showed therapeutic promise when administered alone or in combination with other compounds. More recently, the concept of combination antioxidant therapy has been explored as a novel approach to preventing and treating neurodegenerative conditions that present with oxidative stress as a contributing factor. In this review, the relationship between oxidative stress and AD pathology and the neuroprotective role of natural antioxidants from natural sources are discussed. Additionally, the therapeutic potential of natural antioxidants as preventatives and/or treatment for AD is examined, with special attention paid to natural antioxidant combinations and conjugates that are currently being investigated in human clinical trials.

EGFR amplification and outcome in a randomised phase III trial of chemotherapy alone or chemotherapy plus panitumumab for advanced gastro-oesophageal cancers

OBJECTIVE

Epidermal growth factor receptor (EGFR) inhibition may be effective in biomarker-selected populations of advanced gastro-oesophageal adenocarcinoma (aGEA) patients. Here, we tested the association between outcome and EGFR copy number (CN) in pretreatment tissue and plasma cell-free DNA (cfDNA) of patients enrolled in a randomised first-line phase III clinical trial of chemotherapy or chemotherapy plus the anti-EGFR monoclonal antibody panitumumab in aGEA (NCT00824785).

DESIGN

EGFR CN by either fluorescence in situ hybridisation (n=114) or digital-droplet PCR in tissues (n=250) and plasma cfDNAs (n=354) was available for 474 (86%) patients in the intention-to-treat (ITT) population. Tissue and plasma low-pass whole-genome sequencing was used to screen for coamplifications in receptor tyrosine kinases. Interaction between chemotherapy and EGFR inhibitors was modelled in patient-derived organoids (PDOs) from aGEA patients.

RESULTS

EGFR amplification in cfDNA correlated with poor survival in the ITT population and similar trends were observed when the analysis was conducted in tissue and plasma by treatment arm. EGFR inhibition in combination with chemotherapy did not correlate with improved survival, even in patients with significant EGFR CN gains. Addition of anti-EGFR inhibitors to the chemotherapy agent epirubicin in PDOs, resulted in a paradoxical increase in viability and accelerated progression through the cell cycle, associated with p21 and cyclin B1 downregulation and cyclin E1 upregulation, selectively in organoids from EGFR-amplified aGEA.

CONCLUSION

EGFR CN can be accurately measured in tissue and liquid biopsies and may be used for the selection of aGEA patients. EGFR inhibitors may antagonise the antitumour effect of anthracyclines with important implications for the design of future combinatorial trials.

Pharmaceutical immunoglobulin G impairs anti-carcinoma activity of oxaliplatin in colon cancer cells

BACKGROUND

Recent evidence proves that intravenous human immunoglobulin G (IgG) can impair cancer cell viability. However, no study evaluated whether IgG application benefits cancer patients receiving chemotherapeutics.

METHODS

Influence of pharmaceutical-grade human IgG on the viability of a series of patient-derived colon cancer cell lines with and without chemotherapeutic intervention was determined. Cell death was analysed flow cytometrically. In addition, the influence of oxaliplatin and IgG on the ERK1/2-signalling pathway was evaluated by western blots.

RESULTS

We evaluated the effects of pharmaceutical IgG, such as PRIVIGEN^® IgG and Tonglu^® IgG, in combination with chemotherapeutics. We did not observe any significant effects of IgG on tumour cell viability directly; however, human IgG significantly impaired the anti-tumoral effects of oxaliplatin. Primary cancer cell lines express IgG receptors and accumulate human IgG intracellularly. Moreover, while oxaliplatin induced the activation of ERK1/2, the pharmaceutical IgG inhibited ERK1/2 activity.

CONCLUSIONS

The present study demonstrates that pharmaceutical IgG, such as PRIVIGEN^® IgG and Tonglu^® IgG, can impair the anti-carcinoma activity of oxaliplatin. These data strongly suggest that therapeutic IgG as co-medication might have harmful side effects in cancer patients. The clinical significance of these preclinical observations absolutely advises further preclinical, as well as epidemiological and clinical research.

Role of 7-chloro-4-(phenylselanyl) quinoline in the treatment of oxaliplatin-induced hepatic toxicity in mice

There is an increasing incidence of hepatotoxicity induced by oxaliplatin (OXA); therefore, researchers' attention has been drawn to therapeutic alternatives that may decrease OXA-induced hepatotoxicity. Studies indicate that oxidative stress plays a major role in OXA-induced liver injury. As several pharmacological effects of 7-chloro-4-(phenylselanyl) quinole (4-PSQ) involve its antioxidant action, the hypothesis that this organoselenium compound could be promising for the treatment or prevention of hepatotoxicity induced by treatment with OXA was investigated. To test this hypothesis, male Swiss mice received OXA (10 mg·kg-1) on days 0 and 2, followed by oral administration of 4-PSQ (1 mg·kg-1) on days 2 to 14. 4-PSQ reduced the plasma aspartate, and alanine aminotransferase activity increased by exposure to OXA. The histopathological examination of the liver showed that 4-PSQ markedly improved OXA-induced hepatic injury. In addition, treatment with 4-PSQ reduced the oxidation of lipids and proteins (thiobarbituric acid reactive species levels and protein carbonyl content) and attenuated the increase of hepatic catalase and glutathione peroxidase activity caused by OXA. The inhibition of hepatic δ-aminolevulinic dehydratase activity induced by OXA was reverted by 4-PSQ. In conclusion, results indicate that 4-PSQ may be a good therapeutic strategy for attenuating OXA-induced liver damage.

Diversity and versatility of p38 kinase signalling in health and disease

The ability of cells to deal with different types of stressful situations in a precise and coordinated manner is key for survival and involves various signalling networks. Over the past 25 years, p38 kinases — in particular, p38α — have been implicated in the cellular response to stress at many levels. These span from environmental and intracellular stresses, such as hyperosmolarity, oxidative stress or DNA damage, to physiological situations that involve important cellular changes such as differentiation. Given that p38α controls a plethora of functions, dysregulation of this pathway has been linked to diseases such as inflammation, immune disorders or cancer, suggesting the possibility that targeting p38α could be of therapeutic interest. In this Review, we discuss the organization of this signalling pathway focusing on the diversity of p38α substrates, their mechanisms and their links to particular cellular functions. We then address how the different cellular responses can be generated depending on the signal received and the cell type, and highlight the roles of this kinase in human physiology and in pathological contexts.

p38α — the best-characterized member of the p38 kinase family — is a key mediator of cellular stress responses. p38α is activated by a plethora of signals and functions through a multitude of substrates to regulate different cellular behaviours. Understanding context-dependent p38α signalling provides important insights into p38α roles in physiology and pathology.

Synergistic Enhancement of Cancer Therapy Using HDAC Inhibitors: Opportunity for Clinical Trials

Chemotherapy is one of the most established and effective treatments for almost all types of cancer. However, the elevated toxicity due to the non-tumor-associated effects, development of secondary malignancies, infertility, radiation-induced fibrosis and resistance to treatment limit the effectiveness and safety of treatment. In addition, these multiple factors significantly impact quality of life. Over the last decades, our increased understanding of cancer epigenetics has led to new therapeutic approaches and the promise of improved patient outcomes. Epigenetic alterations are commonly found in cancer, especially the increased expression and activity of histone deacetylases (HDACs). Dysregulation of HDACs are critical to the development and progression of the majority of tumors. Hence, HDACs inhibitors (HDACis) were developed and now represent a very promising treatment strategy. The use of HDACis as monotherapy has shown very positive pre-clinical results, but clinical trials have had only limited success. However, combinatorial regimens with other cancer drugs have shown synergistic effects both in pre-clinical and clinical studies. At the same time, these combinations have enhanced the efficacy, reduced the toxicity and tumor resistance to therapy. In this review, we will examine examples of HDACis used in combination with other cancer drugs and highlight the synergistic effects observed in recent preclinical and clinical studies.

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.

SLC25A32 sustains cancer cell proliferation by regulating flavin adenine nucleotide (FAD) metabolism

SLC25A32 is a member of the solute carrier 25 family of mitochondrial transporters. SLC25A32 transports tetrahydrofolate (THF) as well as FAD into mitochondria and regulates mitochondrial one-carbon metabolism and redox balance. While it is known that cancer cells require one-carbon and FAD-dependent mitochondrial metabolism to sustain cell proliferation, the role of SLC25A32 in cancer cell growth remains unexplored.

Our results indicate that the SLC25A32 gene is highly amplified in different tumors and that amplification correlates with increased mRNA expression and reduced patients´ survival. siRNA-mediated knock-down and CRISPR-mediated knock-out of SLC25A32 in cancer cells of different origins, resulted in the identification of cell lines sensitive and resistant to SLC25A32 inhibition. Mechanistically, tracing of deuterated serine revealed that SLC25A32 knock-down does not affect the mitochondrial/cytosolic folate flux as measured by Liquid Chromatography coupled Mass Spectrometry (LC-MS). Instead, SLC25A32 inhibition results in a respiratory chain dysfunction at the FAD-dependent complex II enzyme, induction of Reactive Oxygen Species (ROS) and depletion of reduced glutathione (GSH), which impairs cancer cell proliferation. Moreover, buthionine sulfoximine (BSO) treatment further sensitizes cells to ROS-mediated inhibition of cell proliferation upon SLC25A32 knock-down. Treatment of cells with the FAD precursor riboflavin and with GSH rescues cancer cell proliferation upon SLC25A32 down-regulation.

Our results indicate that the reduction of mitochondrial FAD concentrations by targeting SLC25A32 has potential clinical applications as a single agent or in combination with approved cancer drugs that lead to increased oxidative stress and reduced tumor growth.

Antagonistic Effects of CAPE (a Component of Propolis) on the Cytotoxicity and Genotoxicity of Irinotecan and SN38 in Human Gastrointestinal Cancer Cells In Vitro

The incidence of gastrointestinal cancers is increasing every year. Irinotecan (CPT-11), a drug used in the treatment of colorectal cancer and gastric cancer, is metabolized by carboxylesterases to an active metabolite, SN-38, which is more cytotoxic. CAPE (caffeic acid phenethyl ester) is an active component of propolis, which has a high antibacterial, antiviral, and antineoplastic potential. This study analyses the impact of CAPE on the cytotoxic (MTT assay), genotoxic (comet assay) and proapoptotic (caspase-3/7 activity) potential of irinotecan and its metabolite SN-38 in cultures of gastrointestinal neoplastic cells (HCT116, HT29, AGS). Cytotoxicity and genotoxicity activities of these compounds were carried out in comparison with human peripheral blood lymphocytes (PBLs) in vitro. The antioxidant potential of CAPE was investigated in relation H₂O₂-induced oxidative stress in the both neoplastic cells and PBLs. CAPE expressed cytotoxic, genotoxic, and pro-apoptotic activity against AGS, HCT116, and HT29 tumor cells. CAPE, in the presence of different concentrations of irinotecan or SN38, decreased the cytotoxicity, genotoxicity, and pro-apoptotic activity in these cell lines, but it has no such action on normal human peripheral blood lymphocytes.

Aminooxyacetic acid (AOAA) sensitizes colon cancer cells to oxaliplatin via exaggerating apoptosis induced by ROS

Background: As the third confirmed gaseous transmitter, the role of hydrogen sulfide (H₂S) in the pathogenesis of multiple types of cancer has been attracting increasing attention. Increased expression of cystathionine β-synthase (CBS) and H₂S in colon cancer tissue samples has been validated and tumor-derived H₂S, mainly produced by CBS, stimulates bioenergetics, cell proliferation, and angiogenesis in colon cancer. Recently, the therapeutic manipulation of H₂S has been proposed as a promising anticancer approach. However, the effect of aminooxyacetic acid (AOAA), which has been widely used as an inhibitor of CBS dependent synthesis of H₂S, on the chemotherapeutic effect of oxaliplatin (OXA) and the underlying mechanisms remain to be illustrated.

Methods: We examined the expression of CBS in human colorectal cancer specimens and matched normal mucosa by immunohistochemistry. The effect of AOAA on the sensitivity of colon cancer cells to OXA and the level of apoptosis induced by caspase cascade was investigated in both HCT116 and HT29 cell lines utilizing CCK-8 assays, flow cytometry analysis and western blot analysis. The endogenous levels of reactive oxygen species (ROS) were detected fluorescently by DCF-DA, and glutathione (GSH) levels were measured by a Total GSH Detection Kit. Tumor bearing xenograft mouse models and in vivo imaging systems were further used to investigate the effect of AOAA in vivo and immunohistochemistry (IHC) and TUNEL analysis were performed.

Results: In the current study, we confirmed CBS, the main target of AOAA, is overexpressed in human colorectal cancer by immunohistochemistry. The inhibitory effect of AOAA on the synthesis of H₂S was validated utilizing fluorescent probe and specific electrode. AOAA significantly reduced the IC50 values of OXA in both colon cancer cell lines. Co-incubation with AOAA elicited increased apoptosis induced by OXA, featured by increased activation of caspase cascade. Besides, AOAA further increased the levels of ROS induced by OXA and attenuated the synthesis of glutathione (GSH), which is a vital antioxidant. Besides, the results of in vivo imaging and following IHC and TUNEL analysis were in accordance with cellular experiments, indicating that AOAA sensitizes colon cancer cells to OXA via exaggerating intrinsic apoptosis.

Conclusion: The results suggested that CBS is overexpressed in colorectal cancer tissues and AOAA sensitizes colon cancer cells to OXA via exaggerating apoptosis both in vitro and in vivo. Decreasing the endogenous level of GSH and consequently impaired detoxification of ROS might be one of the mechanisms underlying the effect of AOAA.

Key Genes And Pathways Controlled By E2F1 In Human Castration-Resistant Prostate Cancer Cells

Background

Treatment of castration-resistant prostate cancer (CRPC) is an enormous challenge. As E2F transcription factor 1 (E2F1) is an essential factor in CRPC, this study investigated the genes and pathways controlled by E2F1 and their effects on cellular behavior in CRPC.

Methods

In vitro assays were used to evaluate cellular proliferation, apoptosis, and behavior. Cellular expression was quantified by RNA sequencing (RNA-seq). Gene co-expression was assessed using the GeneMANIA database, and correlations were analyzed with the GEPIA server. Altered pathways of differentially expressed genes (DEGs) were revealed by functional annotation. Module analysis was performed using the STRING database and hub genes were filtered with the Cytoscape software. Some DEGs were validated by real-time quantitative PCR (RT-qPCR).

Results

Knockdown of E2F1 significantly inhibited proliferation and accelerated apoptosis in PC3 cells but not in DU145 cells. Invasion and migration were reduced for both cell lines. A total of 1811 DEGs were identified in PC3 cells and 27 DEGs in DU145 cells exhibiting E2F1 knockdown. Ten overlapping DEGs, including TMOD2 and AIF1L, were identified in both knockdown cell lines and were significantly enriched for association with actin filament organization pathways. TMOD2 and KREMEN2 were genes co-expressed with E2F1; six overlapping DEGs were positively correlated with transcription factor E2F1. DEGs of the PC3 and DU145 groups were associated with multiple pathways. Five DEGs that overlapped between the two cell lines and three hub DEGs from PC3 cells were validated by RT-qPCR.

Conclusion

The results of this study suggest that E2F1 has a critical role in regulating actin filaments, as indicated by the change in expression level of several genes, including TMOD2 and AIF1L, in CRPC. This extends our understanding of the cellular responses affected by E2F1 in CRPC.

AMPKα1 confers survival advantage of colorectal cancer cells under metabolic stress by promoting redox balance through the regulation of glutathione reductase phosphorylation

Patients with stage II or III colorectal cancer (CRC) exhibit various clinical outcomes after radical treatments. The 5-year survival rate was between 50 and 87%. However, the underlying mechanisms of the variation remain unclear. Here we show that AMPKα1 is overexpressed in CRC patient specimens and the high expression is correlated with poor patient survival. We further reveal a previously unrecognized function of AMPKα1, which maintains high level of reduced glutathione to keep reduction–oxidation reaction (redox) homeostasis under stress conditions, thus promoting CRC cell survival under metabolic stress in vitro and enhancing tumorigenesis in vivo. Mechanistically, AMPKα1 regulate the glutathione reductase (GSR) phosphorylation possibly through residue Thr507 which enhances its activity. Suppression of AMPKα1 by using nano-sized polymeric vector induces a favorable therapeutic effect, especially when in combination with oxaliplatin. Our study uncovers a novel function of AMPKα1 in redox regulation and identifies a promising therapeutic strategy for treatment of CRC.

Lobaplatin-Induced Apoptosis Requires p53-Mediated p38MAPK Activation Through ROS Generation in Non-Small-Cell Lung Cancer

Platinum-based chemotherapy is recommended as the first-line treatment regimen for patients with advanced non-small-cell lung cancer (NSCLC). Lobaplatin (LBP), a third-generation platinum anti-neoplastic agent, has shown an improved efficacy. This study is aimed to investigate the mechanisms of LBP-induced apoptosis in the A549 p53 wild-type cell line. The Cell Counting Kit-8 assay (CCK-8), flow cytometry (FCM), Western blot, xenograft tumor models, terminal deoxynucleotide transferase dUTP nick end labeling (TUNEL), and RNA interference were used in this study. Our results showed that the proliferation of A549 cells could be inhibited by LBP. At lower concentrations, LBP triggered cell cycle arrest at the G1 phase in A549 cells. LBP could also induce apoptosis of A549 cells. LBP also increased the expression of PARP and Bax and the cleavage of caspase-3, caspase-8, and caspase-9 and reduced Bcl-2 expression. In vivo experiment confirmed that LBP could inhibit tumor growth in the A549 xenograft models and induce apoptosis. Apoptosis of A549 cells was decreased after transfected with p53 shRNA or treated with reactive oxygen species inhibitor NAC and p38MAPK inhibitor SB203580, suggesting that the p53/ROS/p38MAPK pathway appeared to mediate the LBP-induced apoptosis of A549 cells. Our data demonstrate that LBP could be a promising candidate for the treatment of NSCLC with wild-type p53.

Mitochondrial dysfunction in the pathogenesis of chemotherapy-induced peripheral neuropathy

Several first-line chemotherapeutic agents, including taxanes, platinum agents and proteasome inhibitors, are associated with the dose-limiting side effect of chemotherapy-induced peripheral neuropathy (CIPN). CIPN predominantly manifests as sensory symptoms, which are likely due to drug accumulation within peripheral nervous tissues rather than the central nervous system. No treatment is currently available to prevent or reverse CIPN. The causal mechanisms underlying CIPN are not yet fully understood. Mitochondrial dysfunction has emerged as a major factor contributing to the development and maintenance of CIPN. This chapter will provide an overview of both clinical and preclinical data supporting this hypothesis. We will review the studies reporting the nature of mitochondrial dysfunction evoked by chemotherapy in terms of changes in mitochondrial morphology, bioenergetics and reactive oxygen species (ROS) generation. Furthermore, we will discuss the in vivo effects of pharmacological interventions that counteract chemotherapy-evoked mitochondrial dysfunction and ameliorate pain-like behavior.

Impact of the microbiome on cancer progression and response to anti-cancer therapies

Humans are a colonized with trillions of commensal microorganisms which exert a profound effect on normal host physiology and immune function through an abundance of genetic and metabolic by-products. Although the commensal microbiome has beneficial functions to host physiology, perturbations of the composition of the commensal microbiome or the homeostatic mucosal environment can lead to the induction of immune pathology and systemic inflammation. In the context of cancer progression or response to immune therapy, this inflammation can be detrimental, resulting in tumor growth and the promotion of immune suppression. On the other hand, significant associations have been identified whereby certain commensal microorganisms are able to enhance T cell function or are required for tumor control in cancer patients treated with certain immune therapies and chemotherapies. The focus of this chapter is to highlight the role of the commensal microbiome during tumor progression and in response to immune therapies.

Inhibition of PGE2/EP4 receptor signaling enhances oxaliplatin efficacy in resistant colon cancer cells through modulation of oxidative stress

The platinum-based chemotherapeutic agent, oxaliplatin, is used to treat advanced colorectal cancer (CRC). Unfortunately, nearly all patients acquire resistance to oxaliplatin after long-term use, limiting its therapeutic efficacy. Since COX-2 and PGE₂ signaling can impact colon cancer cell proliferation and survival, we examined how this pathway was affected in an oxaliplatin resistant colon cancer cell line. PGE₂ levels were significantly elevated in oxaliplatin-resistant HT29 cells (OXR) compared to naïve parental HT29 cells (PAR). This increase was associated with elevated COX-2 (17.9-fold; P = 0.008) and reduced 15-hydroxyprostaglandin dehydrogenase (2.9-fold; P < 0.0001) expression. RNAi knockdown of microsomal prostaglandin E synthase-1, the rate-limiting enzyme in PGE₂ synthesis, sensitized OXR cells to oxaliplatin. Downstream effects of PGE₂ in OXR cells were also examined. Selective inhibition of the EP4 PGE₂ receptor by the small molecule inhibitor, L-161,982 enhanced oxaliplatin-induced apoptosis in OXR cells. L-161,982 also reduced expression of the colonic stem cell markers, CD133 and CD44, and inhibited tumor sphere formation. The accumulation of intracellular reactive oxygen species (ROS), a key component of oxaliplatin cytotoxicity, was significantly increased by EP4 inhibition (2.4 -fold; P < 0.0001). Overall, our findings uncover an important role for the COX-2/PGE₂/EP4 signaling axis in oxaliplatin resistance via regulation of oxidative stress.

Panitumumab in combination with modified docetaxel/cisplatin/5-fluorouracil as first-line treatment in gastric and gastroesophageal junction adenocarcinomas: a multicenter phase II study by the Hellenic Oncology Research Group

Background

A phase I/II study to define the maximum tolerated dose (MTD) of biweekly docetaxel/cisplatin/5-fluorouracil (DCF) plus panitumumab (P), its efficacy, and tolerability as first-line treatment in advanced gastroesophageal cancer.

Methods

In phase I part, patients with unresectable locally advanced or metastatic adenocarcinomas of the stomach or the gastroesophageal junction received cisplatin (40 mg/m² on day 1), leucovorin (400 mg/m² on day 1), 5-fluorouracil (400 mg/m² bolus on day 1), 5-fluorouracil (1000 mg/m²/daycontinuous infusion on days 1-2), and escalated doses of docetaxel (on day 1) plus P (6 mg/kg on day 1) every 2 weeks. In phase II part, patients were treated with DCF/P at the MTD and the primary endpoint was response rate. The expected response rate was set at >40%.

Results

The MTD for docetaxel in the mDCF/P was defined at 40 mg/m² and a total of 40 evaluable patients were enrolled in phase II study. One (2.5%) complete and 13 (32.5%) partial responses (overall response rate: 35%), as well as 16 (40%) disease stabilizations were documented. The median progression-free survival was 6.9 months (95% confidence interval [CI] 3.5-10.3) and the median overall survival was 11.3 months (95%CI 7.7-14.8). Grade 3-4 neutropenia occurred in 10 patients (25%) and febrile neutropenia in 2 (5%). Allergic reactions (grade 1-4) occurred in 9 patients (22.5%). There was 1 treatment-related death.

Conclusions

mDCF/P combination was feasible, though associated with a poor toxicity profile. However, the study failed to meet its primary endpoint and was terminated prematurely due to futility.

N-myc downstream-regulated gene 1 promotes oxaliplatin-triggered apoptosis in colorectal cancer cells via enhancing the ubiquitination of Bcl-2

N-myc downstream-regulated gene1 (NDRG1) has been identified as a potent tumor suppressor gene. The molecular mechanisms of anti-tumor activity of NDRG1 involve its suppressive effects on a variety of tumorigenic signaling pathways. The purpose of this study was to investigate the role of NDRG1 in the apoptosis of colorectal cancer (CRC) cells. We first collected the clinical data of locally advanced rectal cancer (LARC) patients receiving oxaliplatin-based neoadjuvant chemotherapy in our medical center. Correlation analysis revealed that NDRG1 positively associated with the downstaging rates and prognosis of patients. Then, the effects of over-expression and depletion of NDRG1 gene on apoptosis of colorectal cancer were tested in vitro and in vivo. NDRG1 over-expression promoted apoptosis in colorectal cancer cells whereas depletion of NDRG1 resulted in resistance to oxaliplatin treatment. Furthermore, we observed that Bcl-2, a major anti-apoptotic protein, was regulated by NDRG1 at post-transcriptional level. By binding Protein kinase Cα (PKCα), a classical regulating factor of Bcl-2, NDRG1 enhanced the ubiquitination and degradation of Bcl-2, thus promoting apoptosis in CRC cells. In addition, NDRG1 inhibited tumor growth and promoted apoptosis in mouse xenograft model. In conclusion, NDRG1 promotes oxaliplatin-triggered apoptosis in colorectal cancer. Therefore, colorectal cancer patients can be stratified by the expression level of NDRG1. NDRG1-positive patients may benefit from oxaliplatin-containing chemotherapy regimens whereas those with negative NDRG1 expression should avoid the usage of this cytotoxic drug.

HER4 isoform CYT2 and its ligand NRG1III are expressed at high levels in human colorectal cancer

The present study aimed to evaluate the expression of human epidermal growth factor receptor (HER4) isoforms and their ligand neuregulin 1 (NRG1) isoforms in human primary colorectal cancer (CRC). The mRNA expression of HER4 isoforms JM-a, JM-b, CYT1 and CYT2, and their ligand isoforms NRG1 I, II and III in CRC tissues and adjacent normal tissues were quantified by reverse transcription-quantitative polymerase chain reaction analysis. Univariate analysis and logistic regression analysis were performed to analyze the association between HER4 and NRG1 expression and lymph node metastasis in CRC. The expression levels of CYT1 (P=0.002), CYT2 (P=0.002) and NRG1 type III (P<0.001) were significantly higher in the CRC tissues than in the adjacent normal tissues. The expression of CYT2 was correlated with tumor stage (P=0.018), lymph node status (P=0.015) and tumor-node-metastasis (P=0.038) in CRC. The expression of NRG1III was correlated with lymph node metastasis, and the expression of CYT2 was associated with the expression of NRG1III (r=0.691, P<0.01). The logistic regression analysis indicated that expression of CYT2 >50 was a risk factor for lymph node metastasis in CRC. In conclusion the expression levels of CYT1, CYT2 and NRG1III were upregulated in CRC. An expression of CYT-2 >50 was identified as a risk factor for lymph node metastasis in CRC. Therefore, CY-2 and NRG1III may be involved in the progression of CRC.

Dihydromyricetin promotes autophagy and apoptosis through ROS-STAT3 signaling in head and neck squamous cell carcinoma

Chemotherapy is an effective weapon in the battle against cancer, but numerous cancer patients are either not sensitive to chemotherapy or develop drug resistance to current chemotherapy regimens. Therefore, an effective chemotherapy mechanism that enhances tumor sensitivity to chemotherapeutics is urgently needed. The aim of the present study was to determine the antitumor activity of dihydromyricetin (DHM) on head and neck squamous cell carcinoma (HNSCC) and its underlying mechanisms. We demonstrated that DHM can markedly induce apoptotic cell death and autophagy in HNSCC cells. Meanwhile, increased autophagy inhibited apoptosis. Pharmacological or genetic inhibition of autophagy further sensitized the HNSCC cells to DHM-induced apoptosis. Mechanistic analysis showed that the antitumor of DHM may be due to the activation phosphorylation of signal transducer and activator of transcription 3 (p-STAT3), which contributed to autophagy. Importantly, DHM triggered reactive oxygen species (ROS) generation in the HNSCC cells and the levels of ROS decreased with N-acetyl-cysteine (NAC), a ROS scavenger. Moreover, NAC abrogated the effects of DHM on STAT3-dependent autophagy. Overall, the following critical issues were observed: first, DHM increased the p-STAT3-dependent autophagy by generating ROS-signaling pathways in head and neck squamous cell carcinoma. Second, inhibiting autophagy could enhance DHM-induced apoptosis in head and neck squamous cell carcinoma.

The hepatoprotective role of reduced glutathione and its underlying mechanism in oxaliplatin-induced acute liver injury

Currently, the underlying mechanism of oxaliplatin (OXA) induced live injury is unclear. In addition, there is no standard clinical treatment for OXA-induced acute liver injury (ALI). In this study, we established an animal model of OXA-induced ALI, and studied the role of oxidative stress in OXA-induced ALI and the impacts of reduced glutathione (GSH) treatment on OXA-induced ALI. To establish an OXA-induced ALI model, KM mice received intraperitoneal injection of OXA (8 mg/kg) for 4 days. Serum alanine aminotransferase (ALT), aspartate aminotransferase levels (AST), hepatic pathology and oxidative stress indicators in liver tissues were analyzed. To study the impact of GSH treatment on OXA-induced ALI, mice were treated with GSH (400 mg/kg, i.p). In this ALI mouse model, ALT and AST levels were significantly increased (P<0.01). Liver pathological examination revealed varying degrees of liver cell turbidity and degeneration, even balloon-like changes and focal necrosis, and sinusoidal hemorrhage in some cells. Compared with control group, the malondialdehyde (MDA) and GSH levels were significantly increased in OXA-treated group (P<0.01), while the superoxide dismutase SOD and GSH-peroxidase levels were decreased after OXA withdrawal (P<0.01). When GSH was used to treat OXA-induced ALI mice, the pathological injury of liver tissues was alleviated, and serum ALT and AST were significantly decreased. In addition, GSH treatment could reduce the OXA-induced increase of MDA level (P<0.05) in liver tissues, but had no impact on SOD level (P>0.05). We have successfully established an OXA-induced ALI model. Using this model, we discover that oxidative stress plays an important role in OXA-induced ALI. GSH-based hepatoprotective therapy can partially inhibit oxidative stress and alleviate OXA-induced ALI.

ID1 promotes hepatocellular carcinoma proliferation and confers chemoresistance to oxaliplatin by activating pentose phosphate pathway

Background

Drug resistance is one of the major concerns in the treatment of hepatocellular carcinoma (HCC). The aim of the present study was to determine whether aberrant high expression of the inhibitor of differentiation 1(ID1) confers oxaliplatin-resistance to HCC by activating the pentose phosphate pathway (PPP).

Methods

Aberrant high expression of ID1 was detected in two oxaliplatin-resistant cell lines MHCC97H–OXA(97H–OXA) and Hep3B–OXA(3B–OXA). The lentiviral shRNA or control shRNA was introduced into the two oxaliplatin-resistant cell lines. The effects of ID1 on cell proliferation, apoptosis and chemoresistance were evaluated in vitro and vivo. The molecular signaling mechanism underlying the induction of HCC proliferation and oxaliplatin resistance by ID1 was explored. The prognostic value of ID1/G6PD signaling in HCC patients was assessed using the Cancer Genome Atlas (TCGA) database.

Results

ID1 was upregulated in oxaliplaitin-resistant HCC cells and promoted HCC cell proliferation and oxaliplatin resistance. Silencing ID1 expression in oxaliplaitin-resistant HCC cell lines inhibited cell proliferation and sensitized oxaliplaitin-resistant cells to death. ID1 knockdown significantly decreased the expression of glucose-6-phosphate dehydrogenase (G6PD), a key enzyme of the PPP. Silencing ID1 expression blocked the activation of G6PD, decreased the production of PPP NADPH, and augmented reactive oxygen and species (ROS), thus inducing cell apoptosis. Study of the molecular mechanism showed that ID1 induced G6PD promoter transcription and activated PPP through Wnt/β-catenin/c-MYC signaling. In addition, ID1/G6PD signaling predicted unfavorable prognosis of HCC patients on the basis of TCGA.

Conclusions

Our study provided the first evidence that ID1 conferred oxaliplatin resistance in HCC by activating the PPP. This newly defined pathway may have important implications in the research and development of new more effective anti-cancer drugs.

Electronic supplementary material

The online version of this article (10.1186/s13046-017-0637-7) contains supplementary material, which is available to authorized users.

Disrupting G6PD-mediated Redox homeostasis enhances chemosensitivity in colorectal cancer

Glucose-6-phosphate dehydrogenase (G6PD) is a key enzyme that generates NADPH to maintain reduced glutathione (GSH), which scavenges reactive oxygen species (ROS) to protect cancer cell from oxidative damage. In this study, we mainly investigate the potential roles of G6PD in colorectal cancer (CRC) development and chemoresistance. We discover that G6PD is overexpressed in CRC cells and patient specimens. High expression of G6PD predicts poor prognosis and correlated with poor outcome of oxaliplatin-based first-line chemotherapy in patients with CRC. Suppressing G6PD decreases NADPH production, lowers GSH levels, impairs the ability to scavenge ROS levels, and enhances oxaliplatin-induced apoptosis in CRC via ROS-mediated damage in vitro. In vivo experiments further shows that silencing G6PD with lentivirus or non-viral gene delivery vector enhances oxaliplatin anti-tumor effects in cell based xenografts and PDX models. In summary, our finding indicated that disrupting G6PD-mediated NADPH homeostasis enhances oxaliplatin-induced apoptosis in CRC through redox modulation. Thus, this study indicates that G6PD is a potential prognostic biomarker and a promising target for CRC therapy.

Induction of reactive oxygen species: an emerging approach for cancer therapy

Reactive oxygen species (ROS), a group of ions and molecules, include hydroxyl radicals (·OH), alkoxyl radicals, superoxide anion (O2·-), singlet oxygen (1O2) and hydrogen peroxide (H2O2). Hydroxyl radicals and alkoxyl radicals are extremely and highly reactive species respectively. Endogenous ROS are mainly formed in mitochondrial respiratory chain. Low levels of ROS play important roles in regulating biological functions in mammalian cells. However, excess production of ROS can induce cell death by oxidative damaging effects to intracellular biomacromolecules. Cancer cell death types induced by ROS include apoptotic, autophagic, ferroptotic and necrotic cell death. Since abnormal metabolism in cancer cells, they have higher ROS content compared to normal cells. The higher endogenous ROS levels in cancer cells endow them more susceptible to the ROS-induction treatment. Indeed, some anticancer drugs currently used in clinic, such as molecular targeted drugs and chemotherapeutic agents, effectively kill cancer cells by inducing ROS generation. In addition, photodynamic therapy (PDT) is mainly based on induction of ROS burst to kill cancer cells. The mechanism of cell death induced by radiotherapy using ionizing radiation also refers to ROS production. Moreover, ROS play an important role in tumor immune therapy. Altogether, combining above traditional treatments with ROS-induced agents will be considered as a promising strategy in cancer therapy. In this review, we focus on our current understanding of the anticancer effects of ROS.

Reversion of resistance to oxaliplatin by inhibition of p38 MAPK in colorectal cancer cell lines: involvement of the calpain / Nox1 pathway

Oxaliplatin is a major treatment for metastatic colorectal cancer, however its effectiveness is greatly diminished by the development of resistances. Our previous work has shown that oxaliplatin efficacy depends on the reactive oxygen species (ROS) produced by Nox1. In this report, we investigated Nox1 involvement in the survival mechanisms of oxaliplatin resistant cell lines that we have selected. Our results show that basal ROS production by Nox1 is increased in resistant cells. Whereas the transitory Nox1-dependent production of superoxide contributes to the cytotoxicity of oxaliplatin in sensitive cells, oxaliplatin treatment of resistant cells leads to a decrease in the production of superoxide associated with an increase of H₂O₂ and a decreased cytotoxicity of oxaliplatin. We have shown that calpains regulate differently Nox1 according to the sensitivity of the cells to oxaliplatin. In sensitive cells, calpains inhibit Nox1 by cleaving NoxA1 leading to a transient ROS production necessary for oxaliplatin cytotoxic effects. In contrast, in resistant cells calpain activation is associated with an increase of Nox1 activity through Src kinases, inducing a strong and maintained ROS production responsible for cell survival. Using a kinomic study we have shown that this overactivation of Nox1 results in an increase of p38 MAPK activity allowing the resistant cells to escape apoptosis. Our results show that the modulation of Nox1 activity in the context of anticancer treatment remains complex. However, a strategy to maximize Nox1 activation while inhibiting the p38 MAPK-dependent escape routes appears to be an option of choice to optimize oxaliplatin efficiency.

MHY451 induces cell cycle arrest and apoptosis by ROS generation in HCT116 human colorectal cancer cells

Colorectal cancer (CRC) is the third most frequently diagnosed cancer and cause of cancer-related deaths. Despite advancements in conventional therapeutic approaches to CRC, most patients with CRC die of their disease. There is a need to develop novel therapeutic agents for this malignancy. Therefore, the present study aimed to examine the anticancer effects and elucidate the underlying mechanism of MHY451 in HCT116 human colorectal cancer cells. Treatment with MHY451 inhibited cell growth in a time- and concentration-dependent manner. MHY451 increased the accumulation of cell cycle progression at the G2/M phase. This agent decreased the protein level of cyclin B1 and its activating partners, Cdc25c and Cdc2, whereas it increased the cell cycle inhibitor p21WAF/CIP. The induction of apoptosis was observed by decreased viability, cleavage of poly(ADP-ribose) polymerase (PARP), alteration in the ratio of Bax/Bcl-2 protein expression and reduction of procaspase-8 and -9. Pretreatment with Z-VAD-FMK, a pan-caspase inhibitor, inhibited MHY451-induced apoptosis, indicating that apoptotic cell death by MHY451 was mediated through caspases. Moreover, the apoptotic effect of MHY451 was reactive oxygen species (ROS)-dependent, evidenced by the inhibition of MHY451-induced PARP cleavage and ROS generation by N-acetylcysteine-induced ROS scavenging. Taken together, these results demonstrate that MHY451 exerts anticancer effects by regulating the cell cycle, inducing apoptosis through caspase activation and generating ROS. These results suggest that MHY451 has considerable potential for chemoprevention or treatment of CRC or both.

Reactive Oxygen Species-Mediated Mechanisms of Action of Targeted Cancer Therapy

Targeted cancer therapies, involving tyrosine kinase inhibitors and monoclonal antibodies, for example, have recently led to substantial prolongation of survival in many metastatic cancers. Compared with traditional chemotherapy and radiotherapy, where reactive oxygen species (ROS) have been directly linked to the mediation of cytotoxic effects and adverse events, the field of oxidative stress regulation is still emerging in targeted cancer therapies. Here, we provide a comprehensive review regarding the current evidence of ROS-mediated effects of antibodies and tyrosine kinase inhibitors, use of which has been indicated in the treatment of solid malignancies and lymphomas. It can be concluded that there is rapidly emerging evidence of ROS-mediated effects of some of these compounds, which is also relevant in the context of drug resistance and how to overcome it.

Reactive Oxygen Species-Mediated Mechanisms of Action of Targeted Cancer Therapy

Targeted cancer therapies, involving tyrosine kinase inhibitors and monoclonal antibodies, for example, have recently led to substantial prolongation of survival in many metastatic cancers. Compared with traditional chemotherapy and radiotherapy, where reactive oxygen species (ROS) have been directly linked to the mediation of cytotoxic effects and adverse events, the field of oxidative stress regulation is still emerging in targeted cancer therapies. Here, we provide a comprehensive review regarding the current evidence of ROS-mediated effects of antibodies and tyrosine kinase inhibitors, use of which has been indicated in the treatment of solid malignancies and lymphomas. It can be concluded that there is rapidly emerging evidence of ROS-mediated effects of some of these compounds, which is also relevant in the context of drug resistance and how to overcome it.

Cetuximab in treatment of metastatic colorectal cancer: final survival analyses and extended RAS data from the NORDIC-VII study

BACKGROUND

The NORDIC-VII study is a randomised phase III trial of cetuximab plus continuous or intermittent fluorouracil, folinic acid, and oxaliplatin (Nordic FLOX) vs FLOX alone in first-line treatment of metastatic colorectal cancer. The present report presents an updated and final survival analysis with BRAF and extended RAS mutational status, 5 years after the primary analysis.

METHODS

A total of 566 patients were included in the intention-to-treat (ITT) population of the NORDIC-VII study. Updated survival status was obtained from 176 patients who were alive in the primary survival analyses. Samples from 223 tumours previously found to be KRAS (exon 2) and BRAF (V600E) wild-type, were re-analysed for KRAS (exons 3 and 4) and NRAS (exons 2-4) mutations.

RESULTS

Including the extended RAS analyses, RAS and BRAF mutational status was available from 457 patients (81% of the ITT population). RAS was mutated in 46% and BRAF in 12% of the tumours. RAS and BRAF, if mutated, were negative prognostic factors. The updated analyses confirmed the finding of the primary report that cetuximab did not provide any additional benefit when added to FLOX in patients with RAS/BRAF wild-type tumours, neither on progression-free nor overall survival. However, the outcomes in a subset of patients, which, after the first eight treatment cycles, received cetuximab alone, suggested a beneficial effect of cetuximab monotherapy.

CONCLUSIONS

Adding cetuximab to Nordic FLOX did not provide any clinical benefit, but the data suggested an effect of cetuximab monotherapy in patients with RAS/BRAF wild-type tumours in the NORDIC-VII cohort. The data were compatible with a negative interaction between cetuximab and the Nordic FLOX chemotherapy backbone.

Three Combined Treatments, a Novel HDAC Inhibitor OBP-801/YM753, 5-Fluorouracil, and Paclitaxel, Induce G₂ Phase Arrest Through the p38 Pathway in Human Ovarian Cancer Cells

Ovarian cancer is the most lethal disease among gynecological malignancies. More effective therapy is required to counter high recurrence rates and chemotherapy resistance. We investigated the efficacy and molecular mechanisms of three combined treatments (TCTs)—a novel histone deacetylase (HDAC) inhibitor OBP-801/YM753, 5-fluorouracil (5-FU), and paclitaxel (PTX)—in human ovarian cancer SKOV-3 and OVCAR-3 cells. The inhibition of cell growth was stronger with TCTs than with each single agent and with two combined treatments. The TCTs significantly induce G₂ phase arrest in both cell lines. We then analyzed the molecular mechanisms and found that the TCTs increased the phosphorylation of p38 (Thr180/Tyr182), decreased the expression of CDC25C, and increased the phosphorylation of CDC2 (Tyr15), an inactive form of CDC2. To examine the responsibilities of the p38 pathway for G₂ phase arrest induced by the TCTs, we employed the p38 inhibitor SB203580. SB203580 inhibited G₂ phase arrest, suppression of CDC25C, and phosphorylation of CDC2 (Tyr15) induced by the TCTs. These results suggest that the TCTs can induce G₂ phase arrest through activation of the p38 signaling pathway. We therefore believe that this combination is promising as a novel therapeutic strategy against ovarian cancer.

p38MAPK and Chemotherapy: We Always Need to Hear Both Sides of the Story

The p38MAPK signaling pathway was initially described as a stress response mechanism. In fact, during previous decades, it was considered a pathway with little interest in oncology especially in comparison with other MAPKs such as ERK1/2, known to be target of oncogenes like Ras. However, its involvement in apoptotic cell death phenomena makes this signaling pathway more attractive for many cancer research laboratories. This apoptotic role allows to establish a link between p38MAPK and regular chemotherapeutic agents such as Cisplatin or base analogs (Cytarabine, Gemcitabine or 5-Fluorouracil) which are currently used in hospitals across the world. In fact, and more recently, p38MAPK has also been connected with targeted therapies like tyrosine kinase inhibitors (vg. Imatinib, Sorafenib) and, to a lesser extent, with monoclonal antibodies. In addition, the oncogenic or tumor suppressor potential of this signaling pathway has aroused the interest of the scientific community in evaluating p38MAPK as a novel target for cancer therapy. In this review, we will summarize the role of p38MAPK in chemotherapy as well as the potential that p38MAPK inhibition can bring to cancer therapy. All the evidences suggest that p38MAPK could be a double-edged sword and that the search for the most appropriate candidate patients, depending on their pathology and treatment, will lead to a more rational use of this new therapeutic tool.