Glutathione and cysteines suppress cytotoxicity of gas phase of cigarette smoke by direct reacting with unsaturated carbonyl compounds in the gas phase

Metabolic fate of the natural anticancer agent cucurbitacin B: an LC-MS/MS-enabled profiling of its major phase I and II conjugates in vivo

Cucurbitacin B (CuB) is a natural triterpenoid with diverse pharmacological effects including potent anticancer activity. However, its oral bioavailability is hampered by limited metabolism in vivo. We characterized CuB's in vivo metabolism in rats to uncover bioactive metabolites retaining therapeutic potential, using a robust UHPLC-Q-TOF-MS/MS workflow. This workflow combined molecular networking, fragmentation filtering, and mass defect filtering to identify CuB metabolites in rat urine, plasma, and feces following oral administration. Thirteen metabolites were identified and seven were confirmed. Major phase I transformations involved hydrolysis, reduction, epoxidation, and amination. Phase II conjugation included cysteine, glutathione, glucuronide, and gluconic acid conjugates. Notably, one of the main metabolites formed was the cysteine conjugate CuB-Cys. CuB-Cys maintained similar in vitro antiproliferative activity to CuB on HepG2, MCF-7, and PANC-1 cancer cell lines. However, it demonstrated lower cytotoxicity towards non-cancerous L02 cells, highlighting improved therapeutic selectivity. Mechanistically, CuB-Cys induced greater apoptotic signaling in HepG2 cells than CuB via enhanced caspase activation and disrupted BAX-Bcl-2 balance. This represents the first systematic characterization of CuB's in vivo metabolic pathway. The identification and confirmation of CuB-Cys provide insight for drug development efforts aiming to maintain therapeutic efficacy while reducing toxicity, via metabolite-based approaches. Our findings shed light on strategies for improving CuB's clinical potential.

Antioxidative effects of N-acetylcysteine in patients with β-thalassemia: A quick review on clinical trials

Background and Aims

Several studies have highlighted the potent antioxidant properties of N-acetyl cysteine (NAC). This review aimed to assess the impact of NAC on oxidative stress biomarkers in patients with β-thalassemia.

Methods

The review included articles published before 2024 that investigated the effects of NAC on oxidative stress in individuals with β-thalassemia. A comprehensive search was conducted across various databases, including Scopus, PubMed, Web of Science, Trip, and CENTRAL. Only English-language clinical trials were considered for inclusion in this review. Besides, the number needed to treat (NNT) was calculated based on the included studies.

Results

Ninety-nine articles were retrieved from electronic databases, and after a thorough review, eight articles were selected for comprehensive text analysis. The highest dose of NAC administered was 10 mg/kg/day (equivalent to 600 mg/day) over a period of 3-6 months. All the studies assessing the impact of NAC on oxidative stress indicators in β-thalassemia patients demonstrated positive effects during the 3-month follow-up period. Most estimated NNTs fell into 1-5, suggesting significant clinical therapeutic value in this context.

Conclusion

The current potency of NAC alone appears to be effective in ameliorating oxidative stress in patients with β-thalassemia major. While a 3-month duration seems adequate to demonstrate the antioxidant properties of NAC in this population, larger and well-designed clinical trials are warranted. Current clinical evidence possesses a high risk of bias.

Methyl vinyl ketone and its analogs covalently modify PI3K and alter physiological functions by inhibiting PI3K signaling

Reactive carbonyl species (RCS), which are abundant in the environment and are produced in vivo under stress, covalently bind to nucleophilic residues such as Cys in proteins. Disruption of protein function by RCS exposure is predicted to play a role in the development of various diseases such as cancer and metabolic disorders, but most studies on RCS have been limited to simple cytotoxicity validation, leaving their target proteins and resulting physiological changes unknown. In this study, we focused on methyl vinyl ketone (MVK), which is one of the main RCS found in cigarette smoke and exhaust gas. We found that MVK suppressed PI3K-Akt signaling, which regulates processes involved in cellular homeostasis, including cell proliferation, autophagy, and glucose metabolism. Interestingly, MVK inhibits the interaction between the epidermal growth factor receptor and PI3K. Cys656 in the SH2 domain of the PI3K p85 subunit, which is the covalently binding site of MVK, is important for this interaction. Suppression of PI3K-Akt signaling by MVK reversed epidermal growth factor-induced negative regulation of autophagy and attenuated glucose uptake. Furthermore, we analyzed the effects of the 23 RCS compounds with structures similar to MVK and showed that their analogs also suppressed PI3K-Akt signaling in a manner that correlated with their similarities to MVK. Our study demonstrates the mechanism of MVK and its analogs in suppressing PI3K-Akt signaling and modulating physiological functions, providing a model for future studies analyzing environmental reactive species.

Effect of N-Acetylcysteine on Cisplatin Toxicity: A Review of the Literature

N-acetylcysteine (NAC) is a membrane-permeable cysteine precursor capable of enhancing the intracellular cysteine pool, enhancing cellular glutathione (GSH) synthesis, and thus potentiating the endogenous antioxidant mechanism. Late administration of NAC after cisplatin has been shown in different in vivo studies to reduce the side effects caused by various toxicities at different levels without affecting the antitumor efficacy of platinum, improving total and enzymatic antioxidant capacity and decreasing oxidative stress markers. These characteristics provide NAC with a rationale as a potentially effective chemo protectant in cisplatin-based therapeutic cycles. NAC represents a potential candidate as a chemoprotective agent to decrease toxicities secondary to cisplatin treatment. It suggests that it could be used in clinical trials, whereby the effective dose, timing, and route should be adjusted to optimize chemoprotection. This review provides an overview of the effect of NAC on cisplatin toxicity, a drug widely used in the clinic in adults and children.

Effects of antioxidant capacity on micronucleus induction by cigarette smoke in mammalian cells

We have compared micronucleus (MN) induction by cigarette smoke in the L5178Y, TK6, and CHL/IU cell lines. The test sample was total particulate matter of 3R4F reference cigarette smoke, suspended in DMSO. After 3-h treatment, with or without a rat liver S9 metabolic activation system, followed by 24-h recovery, dose-dependent MN increases were seen in all cell lines. However, CHL/IU and TK6 cells were more resistant than L5178Y cells (comparison by Benchmark Doses with PROAST software). 3R4F smoke generates reactive oxygen species (ROS). Therefore, we explored the relationship between the sensitivities to 3R4F smoke and the antioxidant capacities of the cell lines. While the total antioxidant capacities were not significantly different among the cell lines, cellular glutathione (GSH) was higher in CHL/IU cells than in L5178Y cells. Pretreatment of CHL/IU cells with a GSH precursor, N-acetylcysteine (NAC), reduced the genotoxicity/cytotoxicity of 3R4F, whereas an inhibitor of GSH biosynthesis, buthionine sulfoximine (BSO), enhanced it. The effects of NAC and BSO were also seen after treatment with allyl isothiocyanate, a ROS-generating chemical, but not with mitomycin C, a ROS-independent genotoxicant. Pretreatment with NAC increased cellular thiol levels. From the present results, the genotoxicity and cytotoxicity of cigarette smoke differs among these cell lines in a manner that may be related to their antioxidant thiol levels.

Nuclear factor kappa-B contributes to cigarette smoke tolerance in pancreatic ductal adenocarcinoma through cysteine metabolism

BACKGROUND

Retrospective studies revealed that cigarette smoking enhances risk of incidence and worsens prognosis in pancreatic cancer (PC) patients. Poor prognosis in smoker cohort of PC patients indicates prevalence of cigarette smoke stimulated survival mechanisms yet to be explored in PC. In this study, cigarette smoke induced metabolic pathways were explored and targeted in PC.

METHODS

Human pancreatic ductal adenocarcinoma cell (PDAC) lines, genetically engineered mice models (GEMMs), mass spectrometry based heavy isotope-based metabolite analysis, cytotoxicity assays and Nuclear factor kappa-B (NF-kB) targeting were utilized in this study. Cigarette smoke extract (CSE) was prepared fresh each day by bubbling cell culture media with the smoke emitted from 85 mm, filtered, Code 1R6F reference cigarettes and used for in vitro procedures. High dose cigarette smoke exposure of GEMMs was achieved by daily exposure of animals to similar cigarettes, 6 h/day for a total period of 180 days.

FINDINGS

We observed that PDAC cells upregulate glutathione anabolism through cysteine uptake and glutamate cysteine ligase (GCLM), supporting survival, upon CSE exposure. In vivo, cigarette smoke exposure leads to concomitant upregulation of GCLM and activated NF-kB in the PDAC consistent with in vitro, in CSE-exposed PDAC. Finally, either inhibition of NF-kB or depletion of cysteine impaired PDAC cell survival in cigarette smoke exposed conditions through suppression of glutathione and ROS enhancement, reverted by glutathione supplementation.

INTERPRETATION

Our findings demonstrate scope for targeting smoke induced, NF-kB mediated, cysteine and glutathione metabolism for improving the survival of smoke addicted PDAC.

Complex Coronary Instent Chronic Total Occlusion Lesions: Oxidative Stress, Inflammation, and Coronary Stent Lengths

The oxidative stress and inflammation played the key roles in the development of atherosclerotic coronary plaques. However, the relationships between pro/antioxidant, pro/anti-inflammatory status, and complex coronary instent chronic total occlusion lesions were not clear in the elderly patients with very long stent implantations. We tried to evaluate the roles of pro/antioxidant and pro/anti-inflammatory biomarkers in the diagnosis of complex reocclusion lesions in elderly patients after coronary stenting. We evaluated the expression levels of acrolein (ACR), malondialdehyde (MDA), high sensitivity C-reactive protein (hs-CRP), tumor necrosis factor-α (TNF-α), superoxide dismutase 3 (SOD3), paraoxonase-1 (PON-1), endothelial nitric oxide synthase (eNOS), and stromal cell-derived factor-1α (SDF-1α) in the elderly patients with very long stent implantations and complex reocclusion lesions. Levels of ACR, MDA, hs-CRP, and TNF-α were remarkably increased (P < 0.001), and levels of SOD3, PON-1, eNOS, and SDF-1α were decreased significantly (P < 0.001) in the elderly patients with very long stents and complex reocclusion lesions. The prooxidant and proinflammatory biomarkers were remarkably increased, as well as antioxidant and anti-inflammatory biomarkers were decreased significantly in the elderly patients with very long stent implantations and complex reocclusion lesions after coronary stenting. In conclusion, these findings indicated that the imbalance between prooxidant/proinflammatory and antioxidant/anti-inflammatory status was associated with complex reocclusion lesions, suggesting that oxidative stress and inflammation played the key roles in progression of complex reocclusion lesions in the elderly patients with very long stent implantations.

Pro-inflammatory Mediators and Oxidative Stress: Therapeutic Markers for Recurrent Angina Pectoris after Coronary Artery Stenting in Elderly Patients

BACKGROUND

Pro-inflammatory mediators and oxidative stress are related to severity of angina pectoris in patients with coronary heart disease.

OBJECTIVE

We evaluated the effects of pro-inflammatory mediators and oxidative stress on recurrent angina pectoris after coronary artery stenting in elderly patients.

METHODS

We determined the expression levels of malondialdehyde (MDA), acrolein (ACR), tumour necrosis factor-α (TNF-α), toll-like receptor 4 (TLR4), superoxide dismutase 3 (SOD3), paraoxonase-1 (PON-1), stromal cell-derived factor-1α (SDF-1α) and endothelial progenitor cells (EPCs) in elderly patients with recurrent angina pectoris after coronary artery stenting.

RESULTS

Levels of MDA, ACR, TNF-α and TLR4 were significantly increased (p<0.001), and levels of SOD3, PON-1, SDF-1α and EPCs were significantly decreased (p<0.001) in the elderly patients with recurrent angina pectoris after coronary artery stenting. MDA, ACR, TNF-α and TLR4 as markers of oxidative stress and pro-inflammatory mediators may have suppressed SOD3, PON-1, SDF-1α and EPCs as markers of anti-oxidative stress/anti-inflammatory responses. Oxidative stress and pro-inflammatory mediators were important factors involved in recurrent angina pectoris of elderly patients after coronary artery stenting.

CONCLUSION

Oxidative stress and pro-inflammatory mediators could be considered as potential non-invasive prognostic, predictive and therapeutic biomarkers for stable recurrent angina and recurrent unstable angina in the elderly patients after coronary artery stenting.

Acrolein in cigarette smoke attenuates the innate immune responses mediated by surfactant protein D

BACKGROUND

Surfactant proteins (SP) A and D belong to collectin family proteins, which play important roles in innate immune response in the lung. We previously demonstrated that cigarette smoke (CS) increases the acrolein modification of SP-A, thereby impairing the innate immune abilities of this protein. In this study, we focused on the effects of CS and its component, acrolein, on the innate immunity role of another collectin, SP-D.

METHODS

To determine whether aldehyde directly affects SP-D, we examined the lungs of mice exposed to CS for 1 week and detected aldehyde-modified SP-D using an aldehyde reactive probe. The structural changes in CS extract (CSE) or acrolein-exposed recombinant human (h)SP-D were determined by western blot, liquid chromatography-electrospray ionization tandem mass spectrometry, and blue native-polyacrylamide gel electrophoresis analyses. Innate immune functions of SP-D were determined by bacteria growth and macrophage phagocytosis.

RESULTS

Aldehyde-modified SP-D as well as SP-A was detected in the lungs of mice exposed to CS for 1 week. Exposure of hSP-D to CSE or acrolein induced an increased higher-molecular -weight of hSP-D and acrolein induced modification of five lysine residues in hSP-D. These modifications led to disruption of the multimer structure of SP-D and attenuated its ability to inhibit bacterial growth and activate macrophage phagocytosis.

CONCLUSION

CS induced acrolein modification in SP-D, which in turn induced structural and functional defects in SP-D.

GENERAL SIGNIFICANCE

These results suggest that CS-induced structural and functional defects in SP-D contribute to the dysfunction of innate immune responses in the lung following CS exposure.

N-Acetylcysteine: Antioxidant, Aldehyde Scavenger, and More

N-Acetylcysteine is a commonly used antioxidant that is broadly effective despite its limited reactive oxygen species (ROS) reactivity. Chemoprotection by N-acetylcysteine frequently results from inactivation of primary toxicants or reactive electrophiles arising as metabolites or lipid peroxidation products. ROS are linked to the development of many human diseases and biological injury by numerous xenobiotics. Oxidative damage is the first mechanism that is often tested for toxicants. There is also a frequent projection of the established ROS mechanism for one member to a broader group to which this chemical belongs. However, the biological significance of oxidative processes is not always easy to establish, as oxidants could be a cause or result of cellular injury. The role of ROS is tested through genetic manipulations of oxidative stress-protective proteins and addition of small antioxidants. In general, genetic approaches produce protective effects weaker than those of small antioxidants, which can reflect different anti-ROS specificity. Another possibility is that chemical antioxidants have ROS-unrelated chemoprotective activities.