Exploring the therapeutic mechanisms of resveratrol for treating arecoline-induced malignant transformation in oral epithelial cells: insights into hub targets

BACKGROUND

Betel nut chewing is a significant risk factor for oral cancer due to arecoline, its primary active component. Resveratrol, a non-flavonoid polyphenol, possesses anti-cancer properties. It has been shown to inhibit arecoline-induced oral malignant cells in preliminary experiments but the underlying mechanism remains unclear. This research therefore aimed to explore the potential therapeutic targets of resveratrol in treating arecoline-induced oral cancer.

METHODS

Data mining identified common targets and hub targets of resveratrol in arecoline-induced oral cancer. Gene set variation analysis (GSVA) was used to score and validate the expression and clinical significance of these hub targets in head and neck cancer (HNC) tissues. Molecular docking analysis was conducted on the hub targets. The effect of resveratrol intervention on hub targets was verified by experiments.

RESULTS

Sixty-one common targets and 15 hub targets were identified. Hub targets were highly expressed in HNC and were associated with unfavorable prognoses. They played a role in HNC metastasis, epithelial-mesenchymal transition, and invasion. Their expression also affected immune cell infiltration and correlated negatively with sensitivity to chemotherapeutic agents such as bleomycin and docetaxel. Experiments demonstrated that resveratrol down-regulated the expression of the hub targets, inhibited their proliferation and invasion, and induced apoptosis.

CONCLUSION

Resveratrol inhibits the arecoline-induced malignant phenotype of oral epithelial cells by regulating the expression of some target genes, suggesting that resveratrol may be used not only as an adjuvant treatment for oral cancer, but also as an adjuvant for oral cancer prevention due to its low toxicity and high efficacy. © 2024 Society of Chemical Industry.

Autophagy modulation changes mechano-chemical sensitivity of T24 bladder cancer cells

Bladder cancer cells possess unique adaptive capabilities: shaped by their environment, cells face a complex chemical mixture of metabolites and xenobiotics accompanied by physiological mechanical cues. These responses might translate into resistance to chemotherapeutical regimens and can largely rely on autophagy. Considering molecules capable of rewiring tumor plasticity, compounds of natural origin promise to offer valuable options. Fungal derived metabolites, such as bafilomycin and wortmannin are widely acknowledged as autophagy inhibitors. Here, their potential to tune bladder cancer cells´ adaptability to chemical and physical stimuli was assessed. Additionally, dietary occurring mycotoxins were also investigated, namely deoxynivalenol (DON, 0.1-10 µM) and fusaric acid (FA, 0.1-1 mM). Endowing a Janus' face behavior, DON and FA are on the one side described as toxins with detrimental health effects. Concomitantly, they are also explored experimentally for selective pharmacological applications including anticancer activities. In non-cytotoxic concentrations, bafilomycin (BAFI, 1-10 nM) and wortmannin (WORT, 1 µM) modified cell morphology and reduced cancer cell migration. Application of shear stress and inhibition of mechano-gated PIEZO channels reduced cellular sensitivity to BAFI treatment (1 nM). Similarly, for FA (0.5 mM) PIEZO1 expression and inhibition largely aligned with the modulatory potential on cancer cells motility. Additionally, this study highlighted that the activity profile of compounds with similar cytotoxic potential (e.g. co-incubation DON with BAFI or FA with WORT) can diverge substantially in the regulation of cell mechanotransduction. Considering the interdependence between tumor progression and response to mechanical cues, these data promise to provide a novel viewpoint for the study of chemoresistance and associated pathways.

Fusaric acid inhibits proliferation and induces apoptosis through triggering endoplasmic reticulum stress in MCF-7 human breast cancer cells

Breast cancer has replaced lung cancer to be the leading cancer in the world. Currently, chemotherapy is still the major method for breast cancer therapy, but its overall effect remains unsatisfactory. Fusaric acid (FSA), a mycotoxin derived from fusarium species, has shown potency against the proliferation of several types of cancer cells, but its effect on breast cancer cells has not been examined. Therefore, we explored the possible effect of FSA on the proliferation of MCF-7 human breast cancer cells and uncovered the underlying mechanism in the present study. Our results showed that FSA has a strong anti-proliferative effect on MCF-7 cells through inducing ROS production, apoptosis and arresting cell cycle at G2/M transition phase. Additionally, FSA triggers endoplasmic reticulum (ER) stress in the cells. Notably, the cell cycle arrest and apoptosis inducing effect of FSA can be attenuated by ER stress inhibitor, tauroursodeoxycholic acid. Our study provide evidence that FSA is a potent proliferation inhibition and apoptosis inducing agent against human breast cancer cells, and the possible mechanism involves the activation of ER stress signaling pathways. Our study may highlight that FSA is promising for the future in vivo study and development of potential agent for breast cancer therapy.

Determination of the effects of fusaric acid, a mycotoxin, on cytotoxicity, gamma-H2AX, 8-hydroxy-2 deoxyguanosine and DNA repair gene expressions in pancreatic cancer cells

Pancreatic cancer has a poor prognosis and is an important public health problem for developing countries. Oxidative stress plays an important role in cancer initiation, progression, proliferation, invasion, angiogenesis and metastasis. For this reason, one of the important strategic targets of new cancer therapeutics is to drive cancer cells into apoptosis through oxidative stress. In nuclear and mitochondrial DNA, 8-hydroxy-2'-deoxyguanosine and gamma-H2AX (γ-H2AX) are used as important oxidative stress biomarkers. Fusaric acid (FA) is a mycotoxin that mediates toxicity produced by Fusarium species and exhibits anticancer effects in various cancers via inducing apoptosis, cell cycle arrest, or other cellular mechanisms. The aim of this study was to determine the effects of fusaric acid on cytotoxic and oxidative damage in MIA PaCa-2 and PANC-1 cell lines. In this context, dose and time dependent cytotoxic effect of fusaric acid was determined by XTT method, mRNA expression levels of genes related to DNA repair were determined by RT-PCR, and its effect on 8-hydroxy-2'-deoxyguanosine and γ-H2AX levels was revealed by ELISA assay. According to XTT results, fusaric acid inhibits cell proliferation in MIA PaCa-2 and Panc-1 cells in a dose- and time-dependent manner. IC50 doses were determined as 187.74 μM at 48 h in MIA PaCa-2 cells and 134.83 μM at 48 h in PANC-1 cells, respectively. γ-H2AX and 8-OHdG changes were not found significant in pancreatic cancer cells. The mRNA expression levels of DNA repair-related genes NEIL1, OGG1, XRCC and Apex-1 change with exposure to fusaric acid. This study contributes to the therapeutic approaches to be developed for pancreatic cancer and demonstrates the potential of fusaric acid as an anticancer agent.

Mycotoxin Occurrence, Exposure and Health Implications in Infants and Young Children in Sub-Saharan Africa: A Review

Infants and young children (IYC) remain the most vulnerable population group to environmental hazards worldwide, especially in economically developing regions such as sub-Saharan Africa (SSA). As a result, several governmental and non-governmental institutions including health, environmental and food safety networks and researchers have been proactive toward protecting this group. Mycotoxins, toxic secondary fungal metabolites, contribute largely to the health risks of this young population. In SSA, the scenario is worsened by socioeconomic status, poor agricultural and storage practices, and low level of awareness, as well as the non-establishment and lack of enforcement of regulatory limits in the region. Studies have revealed mycotoxin occurrence in breast milk and other weaning foods. Of concern is the early exposure of infants to mycotoxins through transplacental transfer and breast milk as a consequence of maternal exposure, which may result in adverse health effects. The current paper presents an overview of mycotoxin occurrence in foods intended for IYC in SSA. It discusses the imperative evidence of mycotoxin exposure of this population group in SSA, taking into account consumption data and the occurrence of mycotoxins in food, as well as biomonitoring approaches. Additionally, it discusses the health implications associated with IYC exposure to mycotoxins in SSA.

Zinc and Copper Enhance Cucumber Tolerance to Fusaric Acid by Mediating Its Distribution and Toxicity and Modifying the Antioxidant System

Fusaric acid (FA), the fungal toxin produced by Fusarium oxysporum, plays a predominant role in the virulence and symptom development of Fusarium wilt disease. As mineral nutrients can be protective agents against Fusarium wilt, hydroponic experiments employing zinc (Zn) and copper (Cu) followed by FA treatment were conducted in a glasshouse. FA exhibited strong phytotoxicity on cucumber plants, which was reversed by the addition of Zn or Cu. Thus, Zn or Cu dramatically reduced the wilt index, alleviated the leaf or root cell membrane injury and mitigated against the FA inhibition of plant growth and photosynthesis. Cucumber plants grown with Zn exhibited decreased FA transportation to shoots and a 17% increase in toxicity mitigation and showed minimal hydrogen peroxide, lipid peroxidation level with the increased of antioxidant enzymes activity in both roots and leaves. Cucumber grown with additional Cu absorbed less FA but showed more toxicity mitigation at 20% compared to with additional Zn and exhibited decreased hydrogen peroxide level and increased antioxidant enzymes activity. Thus, adding Zn or Cu can decrease the toxicity of the FA by affecting the absorption or transportation of the FA in plants and mitigate toxicity possibly through chelation. Zn and Cu modify the antioxidant system to scavenge hydrogen peroxide for suppressing FA induction of oxidative damage. Our experiments could provide a theoretical basis for the direct application of micro-fertilizer as protective agents in farming.

Evaluation of the cytotoxic and genotoxic effects of mycotoxin fusaric acid

Fusaric acid (FA) is produced by several Fusarium species and is commonly found in grains. This investigation was performed to evaluate the cytotoxic and genotoxic effects of FA either in human cervix carcinoma (HeLa) cell line using 3-(4,5-dimethylthiazolyl-2)-2,5 diphenyltetrazolium bromide (MTT) assay and in human lymphocytes using chromosome aberrations (CAs), sister chromatid exchanges (SCEs), micronuclei (MN) as well as comet assay in vitro. The cells were treated with 0.78, 1.56, 3.125, 6.25, 12.50, 25, 50, 100, 200, and 400 µg/mL concentrations of FA. It has potent cytotoxic effect on HeLa cell line measured by MTT assay especially at higher concentrations (200, 400 µg/mL). The half of inhibitory concentration (IC₅₀) evidenced by FA in the HeLa cells was 200 μg/mL at 24 h and between 200 and 400 μg/mL at 48 h. It was also observed that FA produced a significant decrease in mitotic index (MI) at 12.50 µg/mL compared to solvent control. Furthermore, it indicated a cytotoxic effect at the concentrations ranging from 25 to 400 μg/mL in human lymphocytes. The results of this research point out that being exposed to FA at high concentrations show cytotoxicity. Besides FA induced comet tail intensity at 3.125, 6.25, and 12.50 µg/mL concentrations in isolated human lymphocytes. On the other hand, no genotoxic effects were seen in human lymphocytes in vitro using CA, SCE and MN assays.

Fusaric Acid Induces DNA Damage and Post-Translational Modifications of p53 in Human Hepatocellular Carcinoma (HepG2 ) Cells

Fusaric acid (FA), a common fungal contaminant of maize, is known to mediate toxicity in plants and animals; however, its mechanism of action is unclear. p53 is a tumor suppressor protein that is activated in response to cellular stress. The function of p53 is regulated by post-translational modifications-ubiquitination, phosphorylation, and acetylation. This study investigated a possible mechanism of FA induced toxicity in the human hepatocellular carcinoma (HepG₂ ) cell line. The effect of FA on DNA integrity and post-translational modifications of p53 were investigated. Methods included: (a) culture and treatment of HepG₂ cells with FA (IC₅₀ : 580.32 μM, 24 h); (b) comet assay (DNA damage); (c) Western blots (protein expression of p53, MDM2, p-Ser-15-p53, a-K382-p53, a-CBP (K1535)/p300 (K1499), HDAC1 and p-Ser-47-Sirt1); and (d) Hoechst 33342 assay (apoptosis analysis). FA caused DNA damage in HepG₂ cells relative to the control (P < 0.0001). FA decreased the protein expression of p53 (0.24-fold, P = 0.0004) and increased the expression of p-Ser-15-p53 (12.74-fold, P = 0.0126) and a-K382-p53 (2.24-fold, P = 0.0096). This occurred despite the significant decrease in the histone acetyltransferase, a-CBP (K1535)/p300 (K1499) (0.42-fold, P = 0.0023) and increase in the histone deacetylase, p-Ser-47-Sirt1 (1.22-fold, P = 0.0020). The expression of MDM2, a negative regulator of p53, was elevated in the FA treatment compared to the control (1.83-fold, P < 0.0001). FA also inhibited cell proliferation and induced apoptosis in HepG₂ cells as evidenced by the Hoechst assay. Together, these results indicate that FA is genotoxic and post-translationally modified p53 leading to HepG₂ cell death. J. Cell. Biochem. 118: 3866-3874, 2017. © 2017 Wiley Periodicals, Inc.

Fusaric acid induces oxidative stress and apoptosis in human cancerous oesophageal SNO cells

Oesophageal cancer (OC) is a global problem incrementally incident among black South African males. The high incidence of OC may be due to the consumption of corn as a staple, often contaminated with mycotoxins. Fusaric acid (FA), a neglected mycotoxin, is known to disrupt mitochondrial energy metabolism, chelates divalent metal cations and induces cell death in plants. This study investigated FA-induced cytotoxicity and apoptotic induction in the SNO OC cell line. Cells were treated with FA (IC₅₀ = 78.81 μg/mL; 24 h; MTT assay) and assayed for oxidative stress and membrane damage (TBARS, LDH cytotoxicity and glutathione), apoptotic induction (ATP levels, caspase-8, -9, -3/7 activities) (Luminometry), single strand DNA and nuclear fragmentation (Comet and Hoechst assay). Additionally, relative expression of pro- and anti-apoptotic proteins were determined (Western Blotting). Significant antioxidant depletion was consistent with a concomitant increase in ROS-induced lipid peroxidation and extracellular LDH levels. FA induced apoptosis by significantly increasing Bax expression and caspase-8, -9 and -3/7 activities whilst decreasing ATP levels and Bcl-2 expression. Further, FA significantly increased comet tail lengths, PARP-1 expression and late stage apoptotic body formation in SNO cells. This study shows that FA is cytotoxic and induces increased apoptosis in SNO cells.

Fusaric acid induces mitochondrial stress in human hepatocellular carcinoma (HepG2) cells

Fusarium spp are common contaminants of maize and produce many mycotoxins, including the fusariotoxin fusaric acid (FA). FA is a niacin related compound, chelator of divalent cations, and mediates toxicity via oxidative stress and possible mitochondrial dysregulation. Sirtuin 3 (SIRT3) is a stress response deacetylase that maintains proper mitochondrial function. We investigated the effect of FA on SIRT3 and oxidative and mitochondrial stress pathways in the hepatocellular carcinoma (HepG2) cell line. We determined FA toxicity (24 h incubation; IC50 = 104 μg/ml) on mitochondrial output, cellular and mitochondrial stress responses, mitochondrial biogenesis and markers of cell death using spectrophotometry, luminometry, qPCR and western blots. FA caused a dose dependent decrease in metabolic activity along with significant depletion of intracellular ATP. FA induced a significant increase in lipid peroxidation, despite up-regulation of the antioxidant transcription factor, Nrf2. FA significantly decreased expression of SIRT3 mRNA with a concomitant decrease in protein expression. Lon protease was also significantly down-regulated. FA induced aberrant mitochondrial biogenesis as evidenced by significantly decreased protein expressions of: PGC-1α, p-CREB, NRF1 and HSP70. Finally, FA activated apoptosis as noted by the significantly increased activity of caspases 3/7 and also induced cellular necrosis. This study provides insight into the molecular mechanisms of FA (a neglected mycotoxin) induced hepatotoxicity.

In vitro and in vivo Anticancer Effects of a Novel 9-Phenyldibenzo[a,c]phenazin-9-ium Cation and Its Ligands

BACKGROUND

Multidrug resistance (MDR) is a major problem in cancer treatment. Cu complexes possess the ability to overcome MDR in cancer. Therefore, the search for new Cu complexes is of great clinical significance and we address the anticancer effects of a previously synthesized novel 9-phenyldibenzo[a,c]phenazin-9-ium cation [1(+)] as [1] [CuCl2] and as [1] [I].

METHODS

The existence of the monovalent Cu(I) in [1] [CuCl2] was proven by electron paramagnetic resonance (EPR) studies and in vivo anticancer effects were studied in animals.

RESULTS

The monovalent nature of the Cu ion in [1] [CuCl2] was determined through EPR. The mean survival time of mice bearing doxorubicin-resistant Ehrlich ascites carcinoma cells is longer when [1] [I] is injected intraperitoneally whereas [1] [CuCl2] does not significantly increase the median survival in tumor-bearing mice. Compounds do not follow the immunomodulatory route and only [1] [I] shows cytotoxic activity in both MDR and drug-sensitive leukemia cell lines.

CONCLUSION

An organic iodide complex rather than a cupric complex possesses direct cytotoxic potential.

Determination of oral bioavailability of fusaric acid in male Sprague-Dawley rats

Head and neck squamous cell cancer accounts for 3 % of new cancer cases and 2 % of cancer mortality annually in the United States. Current treatment options for most head and neck cancers continue to be surgical excision with or without radiation, radiation alone, or chemotherapy with radiation depending on location, stage of disease, and patient preference. Fusaric acid (FA) is a novel compound from a novel class of nicotinic acid derivatives that have activity against head and neck squamous cell carcinoma (HNSCC). Although its exact mechanism is still unknown, FA is thought to be active by increasing damage to DNA and preventing its synthesis and repair. The novel mechanism of FA provides an alternative to present therapies, as a single agent whether given parenterally or orally. It has synergy with conventional agents taxol, carboplatin, and erlotinib. In order to determine if FA has reasonable oral bioavailability, we have determined the pharmacokinetics of FA in male Sprague Dawley rats following administration by gavage and by intravenous injection. The bioavailability of FA was sufficient (58 %) to suggest that FA may be viable as an orally administered medication. Despite the encouraging bioavailability of FA, the intravenous (IV) pharmacokinetics suggested non-linear behavior within the IV dose range of 10, 25, and 75 mg/kg. These results demonstrate that further pharmacokinetic and toxicity studies in larger animals such as dogs and non-human primates are warranted.