Arecoline-induced pro-fibrotic proteins in LLC-PK1 cells are dependent on c-Jun N-terminal kinase

A review of the traditional uses, pharmacology, and toxicology of areca nut

BACKGROUND

Areca nut, the fruit of A. catechu, is an important Chinese herbal medicine and is the first of China's "four southern medicines". The main chemical components are alkaloids, phenols, polysaccharides, amino acids, and terpenoids. The flowers, leaves, fruits and seeds of A. catechu contain high medicinal value. However, with the emergence of adverse reactions in people who chew areca nut, people have doubts about the safety of the use of areca nut.

PURPOSE

In view of the two sides of pharmacology and toxicology of areca nut, this study comprehensively reviewed the components of different parts of A. catechu, the mechanism of pharmacology and toxicology, and the relationship between dosage and pharmacology and toxicology, in order to provide a new reference for the safe application of areca nut.

METHODS

We used "Areca nut", "Betel nut", and known biologically active ingredients in areca nut, combined with "natural active ingredients", "pharmacological activity", and "toxicological effect" as keywords to search in PubMed, Web of Science, Science Direct and CNKI up to March 2024.

RESULTS

A large number of studies have shown that low-dose areca nut has pharmacological effects such as deworming, anti-inflammatory, improving gastrointestinal function, lowering blood lipids, preventing atherosclerosis, anti-depression properties. The important mechanism involved in these effects is to reduce the generation of ROS, inhibit the activation of NADPH oxidase, increase the activity of antioxidant enzymes, affect MAPK, AKT, TLR, NF-κB, Nrf-2, PI3 K, STAT3 signaling pathway, reduce COX-2, IL-1β m RNA, MCP-1 and ICAM-1 mRNA gene expression, reduce IL-6, IL-8, IGE levels, activate AMPK signaling pathway, change the ion level in cells, and increase Bax/Bcl-2 ratio. It interferes with the biochemical metabolic process of bacteria. Long-term consumption of areca nut in large quantities will cause some adverse reactions or related malignant diseases to the human body.

CONCLUSION

We reviewed the pharmacological and toxicological effects and related mechanisms of areca nut, revealed the relationship between dose and pharmacological and toxicological effects, and discussed how to reduce the toxicity of areca nut and improve the comprehensive utilization of areca nut. It provides a reference for the study of the relationship between areca nut and human health, as well as the safe and rational use and full development and utilization of areca nut.

Areca nut-induced metabolic reprogramming and M2 differentiation promote OPMD malignant transformation

BACKGROUND

Betel quid and its major ingredient, areca nut, are recognized by IARC as major risk factors in oral cancer development. Areca nut extract (ANE) exposure has been linked to OPMD progression and malignant transformation to OSCC. However, the detailed mechanism through which ANE acts on other cell types in the oral microenvironment to promote oral carcinogenesis remains elusive.

METHODS

Immunoprofiling of macrophages associated with OPMD and OSCC was carried out by immunohistochemical and immunofluorescence staining. Phosphokinase and cytokine arrays and western blotting were performed to determine the underlying mechanisms. Transwell assays were used to evaluate the migration-promoting effect of ANE. Hamster model was finally applied to confirm the in vivo effect of ANE.

RESULTS

We reported that M2 macrophages positively correlated with oral cancer progression. ANE induced M2 macrophage differentiation, CREB phosphorylation and VCAM-1 secretion and increased mitochondrial metabolism. Conditioned medium and VCAM-1 from ANE-treated macrophages promoted migration and mesenchymal phenotypes in oral precancer cells. In vivo studies showed that ANE enhanced M2 polarization and related signaling pathways in the oral buccal tissues of hamsters.

CONCLUSION

Our study provides novel mechanisms for areca nut-induced oral carcinogenesis, demonstrating that areca nut promotes M2 macrophage differentiation and secretion of oncogenic cytokines that critically activate malignant transformation of oral premalignant cells.

Nephrotoxicity induced by natural compounds from herbal medicines - a challenge for clinical application

Herbal medicines (HMs) have long been considered safe and effective without serious toxic and side effects. With the continuous use of HMs, more and more attention has been paid to adverse reactions and toxic events, especially the nephrotoxicity caused by natural compounds in HMs. The composition of HMs is complex and various, especially the mechanism of toxic components has been a difficult and hot topic. This review comprehensively summarizes the kidney toxicity characterization and mechanism of nephrotoxic natural compounds (organic acids, alkaloids, glycosides, terpenoids, phenylpropanoids, flavonoids, anthraquinones, cytotoxic proteins, and minerals) from different sources. Recommendations for the prevention and treatment of HMs-induced kidney injury were provided. In vitro and in vivo models for evaluating nephrotoxicity and the latest biomarkers are also included in this investigation. More broadly, this review may provide theoretical basis for safety evaluation and further comprehensive development and utilization of HMs in the future.

In Vitro and In Vivo Antifibrotic Effects of Fraxetin on Renal Interstitial Fibrosis via the ERK Signaling Pathway

Fraxetin, a natural derivative of coumarin, is known to have anti-inflammatory, anti-oxidant, and hepatoprotective effects in multiple diseases and in liver fibrosis. Whether fraxetin exerts similar effects against renal fibrosis is unknown. In a Unilateral Ureteral Obstruction (UUO) mouse model of renal fibrosis, fraxetin decreased UUO-induced renal dysfunction with a marked reduction in renal interstitial collagen fibers as detected by Masson’s Trichrome staining. Fraxetin treatment also inhibited the expression of α-SMA, Collagen I, Collagen IV, fibronectin, N-cadherin, vimentin, phosphorylated-ERK, and increased the expression of E-cadherin in UUO mice, as shown by immunohistochemical staining and western blot analysis. In vitro studies showed that fraxetin and indoxyl sulfate had no cytotoxic effects on MES13 kidney cells, but that fraxetin significantly decreased IS-induced cell motility and decreased protein expression of α-SMA, N-cadherin, vimentin, and Collagen IV via the ERK-mediated signaling pathway. These findings provide insight into the mechanism underlying fraxetin-induced inhibition of fibrogenesis in renal tissue and suggest that fraxetin treatment may be beneficial for slowing CKD progression.

Arecoline suppresses epithelial cell viability by upregulating tropomyosin-1 through the transforming growth factor-β/Smad pathway

CONTEXT

Oral submucous fibrosis (OSF) is a chronic and progressive disease. Arecoline, present in betel nuts, has been proposed as a vital aetiological factor. However, the underlying mechanism remains unclear.

OBJECTIVES

This research elucidates the expression of tropomyosin-1 (TPM1) and its regulation mechanism in HaCaT cells treated with arecoline.

MATERIALS AND METHODS

HaCaT cells were assigned into three groups: (1) Control; (2) Treated with arecoline (0.16 mM) for 48 h (3) Treated with arecoline (0.16 mM) and transfected with small interfering RNA (siRNA) for TPM1 (50 nM) for 48 h. CCK8, cell cycle, and apoptosis phenotypic analyses were performed. PCR and western blot analyses were performed to detect the expression level of TPM1 and examine the related signalling pathway.

RESULTS

The IC₅₀ of arecoline was approximately 50 μg/mL (0.21 mM). The arecoline dose (0.16 mM) and time (48 h) markedly increased TPM1 expression at the mRNA and protein levels in HaCaT cells. Arecoline suppressed the cell growth, caused cell cycle arrest at the G1 phase, and induced cell apoptosis in HaCaT cells. siRNA-mediated knockdown of TPM1 attenuated the effect of arecoline on cell proliferation, apoptosis, and cell cycle arrest at the G1 phase. Furthermore, blocking of the transforming growth factor (TGF)-β receptor using SB431542 significantly suppressed TPM1 expression in the cells treated with arecoline.

DISCUSSION AND CONCLUSIONS

Arecoline suppresses HaCaT cell viability by upregulating TPM1 through the TGF-β/Smad signalling pathway. This research provides a scientific basis for further study of arecoline and TPM1 in OSF and can be generalised to broader pharmacological studies. TPM1 may be a promising molecular target for treating OSF.

Arecoline suppresses epithelial cell viability through the Akt/mTOR signaling pathway via upregulation of PHLPP2

Arecoline, the major active ingredient of the betel nut, is involved in the pathogenesis of oral submucous fibrosis. However, the underlying mechanism of this pathogenesis remains unclear. In this study, we found that arecoline suppresses the cell proliferation of the HaCaT epithelial cell and induces cell cycle arrest at the G1/S phase with an IC50 of 50 μg/mL. Furthermore, we found that arecoline reduces the protein level of cyclin D1, but it has no effect on its mRNA level and protein stability, implying that arecoline may modulate the translation of cyclin D1. We also observed the downregulation of the Akt/mTOR signaling pathway after treatment with arecoline, which may be related to the translation of cyclin D1. RNA-seq analysis identified that PHLPP2, the direct upstream target of Akt, is significantly upregulated after arecoline treatment. siRNA-mediated knockdown of PHLPP2 recovered the phosphorylation state of Akt, as well as attenuated the effect of arecoline on cell viability. Thus, our study revealed the crucial role of PHLPP2 in arecoline-induced cell viability suppression.

CYP450-mediated mitochondrial ROS production involved in arecoline N-oxide-induced oxidative damage in liver cell lines

BACKGROUND

IARC has classified the betel nut as a human environmental carcinogen. Previous studies have found that arecoline (AR) is the major alkaloid present in the saliva of betel quid chewers. Saliva contains a large content of AR which has been further shown to cause mutation of oral mucosa cells, resulting in oral cancer. Whereas, to date, there are only few studies reported the hepatotoxicity associated with arecoline and betel nut chewing. Therefore, the main purpose of this study was to determine the toxic effects of AR and its oxidative metabolite, arecoline N-oxide (ARNO), in normal liver cell lines.

METHODS

The cytotoxic, genotoxic, and mutagenic effects were detected by crystal violet staining, alkaline comet assay, and Salmonella mutagenicity test, respectively. Measurement of intracellular reactive oxygen species (ROS) generation was determined using the H2-DCFDA assay.

RESULTS

Our results demonstrated that ARNO exerted higher cytotoxicity, DNA damage, and mutagenicity than its parent compound arecoline in liver cells. Antioxidants, such as N-acetylcysteine, Trolox, and penicillamine, strongly protected liver cells from ARNO-induced DNA damage and ROS production. Furthermore, co-treatment with Mito-TEMPO also effectively blocked ARNO-induced ROS production in liver cells. Besides antioxidants, co-treatment with 1-aminobenzotriazole and methimazole nearly completely suppressed ARNO-induced ROS production in liver cells.

CONCLUSIONS

Our data suggest that arecoline ingested from the habit of chewing betel quid can be primarily oxidized to ARNO, thereby enhancing its toxicity through increased ROS production. Considering the excellent protective effects of both mitochondria-targeted antioxidant and CYP450 inhibitor on ARNO-induced ROS production in liver cells, mitochondria CYP450-mediated metabolism of ARNO may be a key mechanism. Collectively, our results provide novel cellular evidence for the positive connection between habitual betel quid chewing and the risk for liver damage.

Betel nut chewing and the risk of chronic kidney disease: evidence from a meta-analysis

PURPOSE

To investigate and quantify the potential association between betel nut chewing and the risk of chronic kidney disease (CKD).

METHODS

We searched five online databases including PubMed, EMBASE, ISI Web of Science, Wanfang and CNKI to identify observational studies that published prior to May, 1, 2017. The primary outcome was the association between betel nut chewing and CKD expressed as odds ratio (OR) and the corresponding 95% confidence interval (95%CI) after adjustment for other covariates. Meta-analysis was performed using RevMan 5.3 software; the leave-one-out sensitivity analysis was used to confirm the stability of drawn conclusion.

RESULTS

Five studies comprising a total of 10,562 CKD patients and 34,038 subjects without CKD that analyzed the relationship between betel nut chewing and CKD were included in our study; all the included studies were performed in Taiwan. After the adjustment for covariates, the combined adjusted ORs showed that betel nut used had 1.44 times higher risk to develop CKD compared with non-chewers (OR 1.44, 95%CI 1.08-1.92).

CONCLUSIONS

Betel nut chewing could significantly increase the risk of CKD, indicating that betel nut chewing may exist as an independent risk factor for CKD. Further investigation should be warranted.