N-acetyl-L-cysteine sensitizes pancreatic cancers to gemcitabine by targeting the NFκB pathway

Post-translational modifications of p65: state of the art

P65, a protein subunit of NF-κB, is a widely distributed transcription factor in eukaryotic cells and exerts diverse regulatory functions. Post-translational modifications such as phosphorylation, acetylation, methylation and ubiquitination modulate p65 transcriptional activity and function, impacting various physiological and pathological processes including inflammation, immune response, cell death, proliferation, differentiation and tumorigenesis. The intricate interplay between these modifications can be antagonistic or synergistic. Understanding p65 post-translational modifications not only elucidates NF-κB pathway regulation but also facilitates the identification of therapeutic targets and diagnostic markers for associated clinical conditions.

A review of chemotherapeutic drugs-induced arrhythmia and potential intervention with traditional Chinese medicines

Significant advances in chemotherapy drugs have reduced mortality in patients with malignant tumors. However, chemotherapy-related cardiotoxicity increases the morbidity and mortality of patients, and has become the second leading cause of death after tumor recurrence, which has received more and more attention in recent years. Arrhythmia is one of the common types of chemotherapy-induced cardiotoxicity, and has become a new risk related to chemotherapy treatment, which seriously affects the therapeutic outcome in patients. Traditional Chinese medicine has experienced thousands of years of clinical practice in China, and has accumulated a wealth of medical theories and treatment formulas, which has unique advantages in the prevention and treatment of malignant diseases. Traditional Chinese medicine may reduce the arrhythmic toxicity caused by chemotherapy without affecting the anti-cancer effect. This paper mainly discussed the types and pathogenesis of secondary chemotherapeutic drug-induced arrhythmia (CDIA), and summarized the studies on Chinese medicine compounds, Chinese medicine Combination Formula and Chinese medicine injection that may be beneficial in intervention with secondary CDIA including atrial fibrillation, ventricular arrhythmia and sinus bradycardia, in order to provide reference for clinical prevention and treatment of chemotherapy-induced arrhythmias.

Inhibitory effect of liriopesides B in combination with gemcitabine on human pancreatic cancer cells

Gemcitabine (GEM) is a standard chemotherapeutic agent for patients with pancreatic cancer; however, GEM-based chemotherapy has a high rate of toxicity. A combination of GEM and active constituents from natural products may enhance its therapeutic efficacy and reduce its toxicity. This study investigated the synergistic effects of the combination of liriopesides B (LirB) from Liriope spicata var. prolifera and GEM on human pancreatic cancer cells. The results of our study showed that the combination of LirB and GEM synergistically decreased the viability of pancreatic cancer cells. The combination also caused a strong increase in apoptosis and a strong decrease in cell migration and invasion. Furthermore, LirB combined with GEM had potent inhibitory effects on pancreatic cancer stem cells (CSCs). Studies on the mechanisms of action showed that the combination more potently inhibited protein kinase B (Akt) and nuclear factor kappa B (NF-κB), as well as the downstream antiapoptotic molecules B-cell lymphoma 2 (Bcl-2) and survivin than either agent used alone. The results of this study suggest that the combination of LirB with GEM may improve the efficacy of GEM for the treatment of pancreatic cancer.

Nuclear factor kappa B expression in non-small cell lung cancer

In this mini-review, we discuss the role of NF-κB, a proinflammatory transcription factor, in the expression of genes involved in inflammation, proliferation, and apoptosis pathways, and link it with prognosis of various human cancers, particularly non-small cell lung cancer (NSCLC). We and others have shown that NF-κB activity can be impacted by post-translational S-glutathionylation through reversible formation of a mixed disulfide bond between its cysteine residues and glutathione (GSH). Clinical data analysis showed that high expression of NF-κB correlated with shorter overall survival (OS) in NSCLC patients, suggesting a tumor promotion function for NF-κB. Moreover, NF-κB expression was associated with tumor stage, lymph node metastasis, and 5-year OS in these patients. NF-κB was over-expressed in the cytoplasm of tumor tissue compared to adjacent normal tissues. S-glutathionylation of NF-κB caused negative regulation by interfering with DNA binding activities of NF-κB subunits. In response to oxidants, S-glutathionylation of NF-κB also correlated with enhanced lung inflammation. Thus, S-glutathionylation is an important contributor to NF-κB regulation and clinical results highlight the importance of NF-κB in NSCLC, where NF-κB levels are associated with unfavorable prognosis.

NAC, NAC, Knockin' on Heaven's door: Interpreting the mechanism of action of N-acetylcysteine in tumor and immune cells

N-acetylcysteine (NAC) has been used as a direct scavenger of reactive oxygen species (hydrogen peroxide, in particular) and an antioxidant in cancer biology and immuno-oncology. NAC is the antioxidant drug most frequently employed in studies using tumor cells, immune cells, and preclinical mouse xenografts. Most studies use redox-active fluorescent probes such as dichlorodihydrofluorescein, hydroethidine, mitochondria-targeted hydroethidine, and proprietary kit-based probes (i.e., CellROX Green and CellROX Red) for intracellular detection of superoxide or hydrogen peroxide. Inhibition of fluorescence by NAC was used as a key experimental observation to support the formation of reactive oxygen species and redox mechanisms proposed for ferroptosis, tumor metastasis, and redox signaling in the tumor microenvironment. Reactive oxygen species such as superoxide and hydrogen peroxide stimulate or abrogate tumor cells and immune cells depending on multiple factors. Understanding the mechanism of antioxidants is crucial for interpretation of the results. Because neither NAC nor the fluorescent probes indicated above react directly with hydrogen peroxide, it is critically important to reinterpret the results to advance our understanding of the mechanism of action of NAC and shed additional mechanistic insight on redox-regulated signaling in tumor biology. To this end, this review is focused on how NAC could affect multiple pathways in cancer cells, including iron signaling, ferroptosis, and the glutathione-dependent antioxidant and redox signaling mechanism, and how NAC could inhibit oxidation of the fluorescent probes through multiple mechanisms.

Bromelain and acetylcysteine (BromAc®) alone and in combination with gemcitabine inhibit subcutaneous deposits of pancreatic cancer after intraperitoneal injection

Gemcitabine (GEM) is commonly chosen for treating pancreatic cancer. However, its use is limited by toxicity. Earlier in vitro studies with GEM in combination with Bromelain (Brom) and Acetylcysteine (Ac) indicated a substantial reduction in IC₅₀. In this study, immunocytochemistry and Western blot were used to explore the mechanistic effects of Brom and Ac (BromAc^®) in vitro. Then, we explored the efficacy and safety of BromAc^® only and with GEM in a pancreatic cancer model in vivo. Immunocytochemistry results revealed a reduction in both MUC1 and MUC4 post-treatment. There was a decrease in VEGF, MMP-9, NF-κβ and cleavage of PARP. There was also a decrease in the cell cycle regulators Cyclin B and D as well as TGF-β and the anti-apoptotic Bcl-2. In vivo, the low and high doses of BromAc^® alone and with chemotherapy agents were safe. A very significant reduction in pancreatic tumour volume, weight, and ki67 were seen with BromAc^® therapy and was equal to treatment with GEM alone and better than treatment with 5-FU. In addition, tumour density was significantly reduced by BromAc^®. In conclusion, the anticancer effect of BromAc^® is probably related to its mucin depletion activity as well as its effect on proteins involved in cell cycle arrest, apoptosis and modulation of the tumour microenvironment. The in vivo results are encouraging and are considered the first evidence of the efficacy of BromAc^® in pancreatic cancer. These results also provide some mechanistic leads of BromAc^®.

Trimetazidine alone or in combination with gemcitabine and/or abraxane decreased cell viability, migration and ATP levels and induced apoptosis of human pancreatic cells

BACKGROUND

Trimetazidine (TMZ) is an anti-ischemic agent that can inhibit the fatty acid oxidation. It has been stated that inhibition of fatty acid oxidation may be an acceptable approach to cancer treatment.

METHODS

We examined the effects of TMZ alone or together with abraxane (ABX) and/or gemcitabine (GEM) on cell viability, apoptosis, adhesion, migration and ATP levels of human pancreatic cancer cell line PANC-1.

RESULTS

TMZ significantly reduced the cell viability at higher concentrations. Lower cell viability values were found in cells co-treated with TMZ + GEM, TMZ + ABX and GEM + ABX. The combined treatment of TMZ with ABX and/or GEM significantly increased the apoptosis rates. The highest percentages of apoptosis were found in TMZ + ABX or TMZ + ABX + GEM treatments. TMZ alone or together with ABX and/or GEM significantly reduced the ATP levels. The lowest migration rates were also found at TMZ + ABX and TMZ + ABX + GEM treatments.

CONCLUSIONS

Our study is the first study to indicate that TMZ can induce cytotoxicity and apoptosis and reduce migration and ATP levels, especially in cells co-treated with ABX and/or GEM. A combination strategy based on inhibition of fatty acid oxidation and anticancer drugs may be more effective in the treatment of pancreatic cancers.

Gemcitabine-Related Atrial Fibrillation: A Case Report and Review of the Literature

Gemcitabine is a commonly used antimetabolite that has been effective in a broad spectrum of tumors so far. The main grade three and four known toxicity of this drug is myelosuppression. Cardiac adverse events have rarely been reported and gemcitabine-induced atrial-fibrillation (AF) has been described in only five previous cases so far. Here we report the 6th case of gemcitabine-related AF. A 68-year-old man diagnosed with metastatic nasopharyngeal cancer was referred to our oncology department. He started first line chemotherapy with gemcitabine and cisplatin. He presented poorly tolerated atrial fibrillation related to gemcitabine infusion that lasted for six days. The treatment was then withdrawn and the patient received best supportive care. We conclude that Medical oncologists and cardiologists should be aware of such toxicities of gemcitabine, especially in the elderly who seem to be at a higher risk of such adverse events and which may dictate discontinuation of the drug.

Induced Cell Death as a Possible Pathway of Antimutagenic Action

The existing concepts of antimutagenesis are briefly reviewed. Published reports on antimutagenic and proapoptotic properties of some polyphenols and compounds of other chemical groups obtained in representative in vitro and in vivo experiments on eukaryotic test systems are discussed. The relationships between the antimutagenic and proapoptotic properties of the analyzed compounds (naringin, apigenin, resveratrol, curcumin, N-acetylcysteine, etc.) are considered in favor of the hypothesis on induced cell death as an antimutagenic tool.

Possible Beneficial Effects of N-Acetylcysteine for Treatment of Triple-Negative Breast Cancer

N-acetylcysteine (NAC) is a widely used antioxidant with therapeutic potential. However, the cancer-promoting effect of NAC observed in some preclinical studies has raised concerns regarding its clinical use. Reactive oxygen species (ROS) can mediate signaling that results in both cancer-promoting and cancer-suppressing effects. The beneficial effect of NAC may depend on whether the type of cancer relies on ROS signaling for its survival and metastasis. Triple-negative breast cancer (TNBC) has aggressive phenotypes and is currently treated with standard chemotherapy as the main systemic treatment option. Particularly, basal-like TNBC cells characterized by inactivated BRCA1 and mutated TP53 produce high ROS levels and rely on ROS signaling for their survival and malignant progression. In addition, the high ROS levels in TNBC cells can mediate the interplay between cancer cells and the tissue microenvironment (TME) to trigger the recruitment and conversion of stromal cells and induce hypoxic responses, thus leading to the creation of cancer-supportive TMEs and increased cancer aggressiveness. However, NAC treatment effectively reduces the ROS production and ROS-mediated signaling that contribute to cell survival, metastasis, and drug resistance in TNBC cells. Therefore, the inclusion of NAC in standard chemotherapy could probably provide additional benefits for TNBC patients.

Targeting hypoxic tumor microenvironment in pancreatic cancer

Attributable to its late diagnosis, early metastasis, and poor prognosis, pancreatic cancer remains one of the most lethal diseases worldwide. Unlike other solid tumors, pancreatic cancer harbors ample stromal cells and abundant extracellular matrix but lacks vascularization, resulting in persistent and severe hypoxia within the tumor. Hypoxic microenvironment has extensive effects on biological behaviors or malignant phenotypes of pancreatic cancer, including metabolic reprogramming, cancer stemness, invasion and metastasis, and pathological angiogenesis, which synergistically contribute to development and therapeutic resistance of pancreatic cancer. Through various mechanisms including but not confined to maintenance of redox homeostasis, activation of autophagy, epigenetic regulation, and those induced by hypoxia-inducible factors, intratumoral hypoxia drives the above biological processes in pancreatic cancer. Recognizing the pivotal roles of hypoxia in pancreatic cancer progression and therapies, hypoxia-based antitumoral strategies have been continuously developed over the recent years, some of which have been applied in clinical trials to evaluate their efficacy and safety in combinatory therapies for patients with pancreatic cancer. In this review, we discuss the molecular mechanisms underlying hypoxia-induced aggressive and therapeutically resistant phenotypes in both pancreatic cancerous and stromal cells. Additionally, we focus more on innovative therapies targeting the tumor hypoxic microenvironment itself, which hold great potential to overcome the resistance to chemotherapy and radiotherapy and to enhance antitumor efficacy and reduce toxicity to normal tissues.

Anticancer drug-induced cardiac rhythm disorders: Current knowledge and basic underlying mechanisms

Significant advances in cancer treatment have resulted in decreased cancer related mortality for many malignancies with some cancer types now considered chronic diseases. Despite these improvements, there is increasing recognition that many cancer patients or cancer survivors can develop cardiovascular diseases, either due to the cancer itself or as a result of anticancer therapy. Much attention has focused on heart failure; however, other cardiotoxicities, notably cardiac rhythm disorders, can occur without underlying cardiomyopathy. Supraventricular tachycardias occur in cancer patients treated with cytotoxic chemotherapy (anthracyclines, gemcitabine, cisplatin and alkylating-agents) or kinase-inhibitors (KIs) such as ibrutinib. Ventricular arrhythmias, with a subset of them being torsades-de-pointes (TdP) favored by QTc prolongation have been reported: this may be the result of direct hERG-channel inhibition or a more recently-described mechanism of phosphoinositide-3-kinase inhibition. The major anticancer drugs responsible for QTc prolongation in this context are KIs, arsenic trioxide, anthracyclines, histone deacetylase inhibitors, and selective estrogen receptor modulators. Anticancer drug-induced cardiac rhythm disorders remain an underappreciated complication even by experienced clinicians. Moreover, the causal relationship of a particular anticancer drug with cardiac arrhythmia occurrence remains challenging due in part to patient comorbidities and complex treatment regimens. For example, any cancer patient may also be diagnosed with common diseases such as hypertension, diabetes or heart failure which increase an individual's arrhythmia susceptibility. Further, anticancer drugs are generally usually used in combination, increasing the challenge around establishing causation. Thus, arrhythmias appear to be an underappreciated adverse effect of anticancer agents and the incidence, significance and underlying mechanisms are now being investigated.

Characterization and use of HapT1-derived homologous tumors as a preclinical model to evaluate therapeutic efficacy of drugs against pancreatic tumor desmoplasia

Desmoplasia in human pancreatic cancer (PC) promotes cancer progression and hinders effective drug delivery. The objectives of this study were to characterize a homologous orthotopic model of PC in Syrian golden hamster and investigate the effect of anti-fibrotic (pirfenidone), antioxidant (N-acetyl cysteine, NAC) and anti-addiction (disulfiram, DSF) drugs on desmoplasia and tumor growth in this model. The HapT1 PC cells when implanted orthotopically into hamsters formed tumors with morphological, cellular and molecular similarities to human PC. Protein profiling of activated hamster pancreatic stellate cells (ha-PSCs) revealed expression of proteins involved in fibrosis, cancer cells growth and metastasis. Pirfenidone, suppressed growth of HapT1 cells and the desmoplastic response in vivo; these effects were enhanced by co-administration of NAC. Disulfiram alone or in combination with copper (Cu) was toxic to HapT1 cells and PSCs in vitro; but co-administration of DSF and Cu accelerated growth of HapT1 cells in vivo. Moreover, DSF had no effect on tumor-associated desmoplasia. Overall, this study identifies HapT1-derived orthotopic tumors as a useful model to study desmoplasia and tumor-directed therapeutics in PC. Pirfenidone in combination with NAC could be a novel combination therapy for PC and warrants investigation in human subjects.

Targeting reactive oxygen species in development and progression of pancreatic cancer

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDA) is characterized by expression of oncogenic KRas which drives all aspects of tumorigenesis. Oncogenic KRas induces the formation of reactive oxygen species (ROS) which have been implicated in initiation and progression of PDA. To facilitate tumor promoting levels and to avoid oncogene-induced senescence or cytotoxicity, ROS homeostasis in PDA cells is balanced by additional up-regulation of antioxidant systems. Areas covered: We examine the sources of ROS in PDA, the mechanisms by which ROS homeostasis is maintained, and the biological consequences of ROS in PDA. Additionally, we discuss the potential mechanisms for targeting ROS homoeostasis as a point of therapeutic intervention. An extensive review of the relevant literature as it relates to the topic was conducted using PubMed. Expert commentary: Even though oncogenic mutations in the KRAS gene have been detected in over 95% of human pancreatic adenocarcinoma, targeting its gene product, KRas, has been difficult. The dependency of PDA cells on balancing ROS homeostasis could be an angle for new prevention or treatment strategies. These include use of antioxidants to prevent formation or progression of precancerous lesions, or methods to increase ROS in tumor cells to toxic levels.

Depletion of mucin in mucin-producing human gastrointestinal carcinoma: Results from in vitro and in vivo studies with bromelain and N-acetylcysteine

Aberrant expression of membrane-associated and secreted mucins, as evident in epithelial tumors, is known to facilitate tumor growth, progression and metastasis, and to provide protection against adverse growth conditions, chemotherapy and immune surveillance. Emerging evidence provides support for the oncogenic role of MUC1 in gastrointestinal carcinomas and relates its expression to an invasive phenotype. Similarly, mucinous differentiation of gastrointestinal tumors, in particular increased or de novo expression of MUC2 and/or MUC5AC, is widely believed to imply an adverse clinicopathological feature. Through formation of viscous gels, too, MUC2 and MUC5AC significantly contribute to the biology and pathogenesis of mucin-secreting gastrointestinal tumors. Here, we investigated the mucin-depleting effects of bromelain (BR) and N-acetylcysteine (NAC), in nine different regimens as single or combination therapy, in in vitro (MKN45, KATOIII and LS174T cell lines) and in vivo (female nude mice bearing intraperitoneal MKN45 and LS174T) settings. The inhibitory effects of the treatment on cancer cell growth and proliferation were also evaluated in vivo. Our results suggest that a combination of BR and NAC with dual effects on growth and mucin products of mucin-expressing tumor cells is a promising candidate towards the development of novel approaches to gastrointestinal malignancies with the involvement of mucin pathology. This capability supports the use of this combination formulation in locoregional approaches for reducing the adverse effects of the aberrantly secreted gel-forming mucins, as in pseudomyxoma peritonei and similar pathologies with ectopic production of mucin.

L-cysteine protects intestinal integrity, attenuates intestinal inflammation and oxidant stress, and modulates NF-κB and Nrf2 pathways in weaned piglets after LPS challenge

In this study we investigated whetherL-cysteine (L-cys) could alleviate LPS-induced intestinal disruption and its underlying mechanism. Piglets fed with anL-cys-supplemented diet had higher average daily gain.L-cys alleviated LPS-induced structural and functional disruption of intestine in weanling piglets, as demonstrated by higher villus height, villus height (VH) to crypt depth (CD) ratio, and transepithelial electrical resistance (TER) and lower FITC-dextran 4 (FD4) kDa flux in jejunum and ileum. Supplementation withL-cys up-regulated occludin and claudin-1 expression, reduced caspase-3 activity and enhanced proliferating cell nuclear antigen expression of jejunum and ileum relative to LPS group. Additionally,L-cys suppressed the LPS-induced intestinal inflammation and oxidative stress, as demonstrated by down-regulated TNF-α, IL-6 and IL-8 mRNA levels, increased catalase, superoxide dismutase, glutathione peroxidase activity, glutathione (GSH) contents and the ratio of GSH and oxidized glutathione in jejunum and ileum. Finally, a diet supplemented withL-cys inhibited NF-κB(p65) nuclear translocation and elevated NF erythroid 2-related factor 2 (Nrf2) translocation compared with the LPS group. Collectively, our results indicated the protective function ofL-cys on intestinal mucosa barrier may closely associated with its anti-inflammation, antioxidant and regulating effect on the NF-κB and Nrf2 signaling pathways.

Potentiation of chemotherapeutics by bromelain and N-acetylcysteine: sequential and combination therapy of gastrointestinal cancer cells

Intraperitoneal chemotherapy together with cytoreductive surgery is the standard of care for a number of peritoneal surface malignancies. However, this approach fails to maintain the complete response and disease recurs due to microscopic residual disease. Although safer than systemic chemotherapy regimens, locoregional treatment with chemotherapeutics can induce toxicity which is a major concern affecting the patient's treatment protocol and outcome. For an enhanced treatment efficacy, efforts should be made to maximize cytotoxic effects of chemotherapeutic agents on tumor cells while minimizing their toxic effects on host cells. Bromelain and N-acetylcysteine are two natural agents with good safety profiles shown to have anti-cancer effects. However, their interaction with chemotherapeutics is unknown. In this study, we investigated if these agents have the potential to sensitize in vitro gastrointestinal cancer models to cisplatin, paclitaxel, 5-fluorouracil, and vincristine. The drug-drug interaction was also analyzed. Our findings suggest that combination of bromelain and N-acetylcysteine with chemotherapeutic agents could give rise to an improved chemotherapeutic index in therapeutic approaches to peritoneal surface malignancies of gastrointestinal origin so that maximum benefits could result from less toxic and more patient-friendly doses. This represents a potentially efficacious strategy for the enhancement of microscopic cytoreduction and is a promising area for future research.