Nicotine stimulates CYP1A1 expression in human hepatocellular carcinoma cells via AP-1, NF-κB, and AhR

The role of β2-AR/PI3K/AKT pathway in the proliferation, migration and invasion of THLE-2 cells induced by nicotine

Nicotine, the primary constituent of tobacco, is one of the important factors that induce the occurrence of hepatocellular carcinoma (HCC). The β2-adrenergic receptor (β2-AR) is implicated in the growth and advancement of tumors. However, the role of β2-AR and its mediated cascades in nicotine-induced HCC remains unclear. This present study aims to observe the effects of nicotine on the proliferation, migration, and invasion of immortalized human liver epithelial (THLE-2) cells, as well as to explore the underlying mechanisms of action. The results of cell counting kit-8 (CCK-8) assay showed that 0.3125 μM nicotine had the ability to promote the proliferation of THLE-2 cells with a significant time-dependent manner. Therefore, THLE-2 cells were mainly selected for chronic treatment with 0.3125 μM nicotine in the later stage to cause transformation. After 30 passages of THLE-2 cells with 0.3125 μM nicotine treatment, chronic exposure to nicotine significantly enhanced the proliferation, metastasis, and invasion of cells. Besides, it also upregulated the intracellular levels of β2-AR, phosphoinositide 3-kinase (PI3K), AKT, matrix metalloproteinase-2 (MMP-2) and Cyclin D1, as well as downregulated the expression of p53. More importantly, the β2-AR/PI3K/AKT pathway was found to mediate the expression of MMP-2, Cyclin D1, and p53 in THLE-2 cells, playing a crucial role in their proliferation, migration, and invasion after continuous exposure to nicotine. Simply put, it demonstrated the role of β2-AR/PI3K/AKT pathway in the transformation of THLE-2 cells induced by nicotine. This study could provide valuable insights into the relationship between nicotine and HCC. Additionally, it lays the groundwork for investigating potential anticancer treatments for liver cancer linked to tobacco consumption.

The critical role of SETDB1-mediated CCND1/PI3K/AKT pathway via p53-RS di-methylation at K370 in the proliferation of WRL68 cells induced by nicotine

Constituents of cigarette smoke are known to be carcinogens. Additionally, there is mounting evidence that the liver is an organ susceptible to tobacco carcinogenicity. Nicotine, the primary constituent of tobacco, plays a role in cancer progression. In our previous study, it was found that nicotine enhances the proliferation of a human normal fetal hepatic (WRL68) cell due to the activation of p53 mutation at Ser249 (p53-RS)/STAT1/CCND1 signaling pathway. Here, we further elucidated the mechanism of regulating this pathway. Firstly, dose-dependent increase of SETDB1 protein level in WRL68 cells upon exposure to nicotine (1.25, 2.5, and 5 μM), significantly enhanced cellular proliferation. In addition, the upregulation of SETDB1 protein was necessary for the nuclear translocation of p53-RS to establish a ternary complex with STAT1 and SETDB1, which facilitated p53-RS di-methylation at K370 (p53-RS/K370me2). After that, the activation of CCND1/PI3K/AKT pathway was initiated when STAT1 stability was enhanced by p53-RS/K370me2, ultimately resulting in cell proliferation. Altogether, the study revealed that the increase in SETDB1 expression could potentially have a significant impact on the activation of CCND1/PI3K/AKT pathway through p53-RS/K370me2, leading to the proliferation of WRL68 cells induced by nicotine, which could contribute to hepatocellular carcinoma for smokers. Besides, the results of this study provided a foundation for the development of anticancer therapies for cancers associated with tobacco use.

AP-1 and SP1 trans-activate the expression of hepatic CYP1A1 and CYP2A6 in the bioactivation of AFB1 in chicken

Dietary exposure to aflatoxin B1 (AFB1) is harmful to the health and performance of domestic animals. The hepatic cytochrome P450s (CYPs), CYP1A1 and CYP2A6, are the primary enzymes responsible for the bioactivation of AFB1 to the highly toxic exo-AFB1-8,9-epoxide (AFBO) in chicks. However, the transcriptional regulation mechanism of these CYP genes in the liver of chicks in AFB1 metabolism remains unknown. Dual-luciferase reporter assay, bioinformatics and site-directed mutation results indicated that specificity protein 1 (SP1) and activator protein-1 (AP-1) motifs were located in the core region -1,063/-948, -606/-541 of the CYP1A1 promoter as well as -636/-595, -503/-462, -147/-1 of the CYP2A6 promoter. Furthermore, overexpression and decoy oligodeoxynucleotide technologies demonstrated that SP1 and AP-1 were pivotal transcriptional activators regulating the promoter activity of CYP1A1 and CYP2A6. Moreover, bioactivation of AFB1 to AFBO could be increased by upregulation of CYP1A1 and CYP2A6 expression, which was trans-activated owing to the upregulalion of AP-1, rather than SP1, stimulated by AFB1-induced reactive oxygen species. Additionally, nano-selenium could reduce ROS, downregulate AP-1 expression and then decrease the expression of CYP1A1 and CYP2A6, thus alleviating the toxicity of AFB1. In conclusion, AP-1 and SP1 played important roles in the transactivation of CYP1A1 and CYP2A6 expression and further bioactivated AFB1 to AFBO in chicken liver, which could provide novel targets for the remediation of aflatoxicosis in chicks.

Effects of heated tobacco product aerosol extracts on DNA methylation and gene transcription in lung epithelial cells

AIMS

Smoking causes DNA methylation (DNAm) alterations that lead to lung cancer development. Although the use of heated tobacco products (HTPs) has recently increased, their impact on health remains unclear. This study aimed to evaluate the effects of HTPs on DNAm and gene transcription in human lung epithelial cells in vitro.

MAIN METHODS

Human lung adenocarcinoma (A549) cells with type II alveolar epithelial characteristics were treated with aerosol extracts of two HTPs or a smoke extract of combustible reference cigarette (RC). Global 5-methylcytosine (5-mC) and 5-hydroxymethylcytosine (5-hmC) levels were quantified using dot blot analysis. Furthermore, reduced representation of bisulfite sequencing, DNA microarray, and quantitative PCR analyses were performed to determine CpG methylation and gene transcription changes induced by HTP and RC.

KEY FINDINGS

Global 5-mC and 5-hmC levels were decreased by the RC extract but not the HTP extracts. However, an HTP extract altered the CpG methylation pattern, and Gene Ontology enrichment analysis of the differentially methylated regions of the RC and HTP groups showed a similar pattern. The HTP extract affected gene expression, albeit to a lesser extent than the RC extract. In particular, the HTP extract markedly affected the mRNA expression and promoter methylation of cytochrome P450 family 1 subfamily A member 1 (CYP1A1), which is associated with carcinogenic risk.

SIGNIFICANCE

The study results suggest that HTPs as well as conventional combustible cigarettes can alter CpG methylation and gene transcription in lung epithelial cells.

Novel insights into the progression and prognosis of the calpain family members in hepatocellular carcinoma: a comprehensive integrated analysis

Objectives: The goal of our bioinformatics study was to comprehensively analyze the association between the whole calpain family members and the progression and prognosis of hepatocellular carcinoma (HCC). Methods: The data were collected from The Cancer Genome Atlas (TCGA). The landscape of the gene expression, copy number variation (CNV), mutation, and DNA methylation of calpain members were analyzed. Clustering analysis was performed to stratify the calpain-related groups. The least absolute shrinkage and selection operator (LASSO)-based Cox model was used to select hub survival genes. Results: We found 14 out of 16 calpain members expressed differently between tumor and normal tissues of HCC. The clustering analyses revealed high- and low-risk calpain groups which had prognostic difference. We found the high-risk calpain group had higher B cell infiltration and higher expression of immune checkpoint genes HAVCR2, PDCD1, and TIGHT. The CMap analysis found that the histone deacetylase (HDAC) inhibitor trichostatin A and the PI3K-AKT-mTOR pathway inhibitors LY-294002 and wortmannin might have a therapeutic effect on the high-risk calpain group. The DEGs between calpain groups were identified. Subsequent univariate Cox analysis of each DEG and LASSO-based Cox model obtained a calpain-related prognostic signature. The risk score model of this signature showed good ability to predict the overall survival of HCC patients in TCGA datasets and external validation datasets from the Gene Expression Omnibus database and the International Cancer Genome Consortium database. Conclusion: We found that calpain family members were associated with the progression, prognosis, and drug response of HCC. Our results require further studies to confirm.

Tetrahydrocurcumin regulates the tumor immune microenvironment to inhibit breast cancer proliferation and metastasis via the CYP1A1/NF-κB signaling pathway

The NF-κB signaling pathway is overactivated in tumor cells, and the activation of the NF-κB signaling pathway releases a large number of inflammatory factors, which enhance tumor immunosuppression and promote tumor metastasis. The cytochrome P450 (CYP450) system consists of important metabolic enzymes present in different tissues and progressive tumors, which may lead to changes in the pharmacological action of drugs in inflammatory diseases such as tumors. In this study, the anticancer effect of tetrahydrocurcumin (THC), an active metabolite of curcumin, on breast cancer cells and the underlying mechanism were investigated. Result showed that THC selectively inhibited proliferation and triggered apoptosis in breast cancer cells in a concentration- and time-dependent manner. Moreover, THC-induced cell apoptosis via a mitochondria-mediated pathway, as indicated by the upregulated ratio of Bax/Bcl-2 and reactive oxygen species (ROS) induction. In addition, THC could affect the CYP450 enzyme metabolic pathway and inhibit the expression of CYP1A1 and activation of the NF-κB pathway, thereby inhibiting the migration and invasion of breast cancer cells. Furthermore, after overexpression of CYP1A1, the inhibitory effects of THC on the proliferation, metastasis, and induction of apoptosis in breast cancer cells were weakened. The knockdown of CYP1A1 significantly enhanced the inhibitory effect of THC on the proliferation, metastasis, and apoptosis induction of breast cancer cells. Notably, THC exhibited a significant tumor growth inhibition and anti-pulmonary metastasis effect in a tumor mouse model of MCF-7 and 4T1 cells by regulating the tumor immunosuppressive microenvironment. Collectively, these results showed that TH could effectively trigger apoptosis and inhibit the migration of breast cancer cells via the CYP1A1/NF-κB signaling pathway, indicating that THC serves as a potential candidate drug for the treatment of breast cancer.

L-Selenocysteine induced HepG-2 cells apoptosis through reactive oxygen species-mediated signaling pathway

BACKGROUND

Currently, Liver cancer is the fifth most common tumor and the second most important reason for cancer-related death in the world. However, there are still many limitations of the clinical treatment of liver cancer, and new treatment options are clearly needed. Fortunately, studies have shown that L-Selenocysteine has a certain effect on cancer. This study was to investigate the effects of L-Selenocysteine on the inhibition of cell proliferation and the promotion of apoptosis of HepG-2 cells through ROS mediated fine signaling pathway.

MATERIALS AND METHODS

CCK-8 assay was applied to evaluating the cytotoxic effect of L-Selenocysteine on HepG-2 cells. Electron microscopy, flow cytometry and Western Blot was utilization in further researching cells signaling pathways.

RESULTS

The growth of HepG-2 cells was inhibited by L-selenocysteine ​​treatment in a dose-dependent manner. The cell viability decreased to 52.20%, 43.20% and 30.83% under the treatment of 4, 8, 16 µM L-selenocysteine, respectively. L-Selenocysteine had higher cytotoxicity towards HepG-2 cells than normal cells. L-Selenocysteine can induce the apoptosis of HepG-2 cells by increasing the DNA fragmentation, and activating the Caspase-3. In addition, it was found that the mechanism of the induction to HepG-2 cell apoptosis by L-Selenocysteine was closely related to the overproduction of ROS and promoted apoptosis through the Bcl-2 signaling pathway.

CONCLUSIONS

Our data suggest that L-selenocysteine ​​may cause mitochondrial damage and subsequently stimulate ROS production. ROS can damage cellular DNA and mediate the production of Casapase-8, Bid, Bcl-2 and other proteins, affecting downstream signaling pathways, and ultimately induced apoptosis.

A Review of Toxicity Mechanism Studies of Electronic Cigarettes on Respiratory System

Electronic cigarettes (e-cigarettes) have attracted much attention as a new substitute for conventional cigarettes. E-cigarettes are first exposed to the respiratory system after inhalation, and studies on the toxicity mechanisms of e-cigarettes have been reported. Current research shows that e-cigarette exposure may have potentially harmful effects on cells, animals, and humans, while the safety evaluation of the long-term effects of e-cigarette use is still unknown. Similar but not identical to conventional cigarettes, the toxicity mechanisms of e-cigarettes are mainly manifested in oxidative stress, inflammatory responses, and DNA damage. This review will summarize the toxicity mechanisms and signal pathways of conventional cigarettes and e-cigarettes concerning the respiratory system, which could give researchers a better understanding and direction on the effects of e-cigarettes on our health.

Piperine Attenuates Lithocholic Acid-Stimulated Interleukin-8 by Suppressing Src/EGFR and Reactive Oxygen Species in Human Colorectal Cancer Cells

Piperine, a natural alkaloidal pungent product present in pepper plants, possesses the properties of anti-inflammatory and anti-metastasis. Lithocholic acid is a monohydroxy-5beta-cholanic acid with an alpha-hydroxy substituent at position 3; it is a secondary bile acid that plays a pivotal role in fat absorption, and has been discovered to mediate colorectal cancer (CRC) cell invasion and migration. However, the effect of piperine on angiogenesis has been poorly investigated. In the current study, we examined the role of piperine on LCA-stimulated angiogenesis by measuring interleukin-8 (IL-8) expression; moreover, we revealed the potential molecular mechanisms in CRC cells. Here, we showed that piperine inhibited LCA-stimulated endothelial EA.hy926 cell angiogenesis in a conditioned medium obtained from colorectal HCT-116 cells. Experiments with an IL-8 neutralizer showed that IL-8 present in the conditioned medium was the major angiogenic factor. Piperine inhibited LCA-stimulated ERK1/2 and AKT via the Src/EGFR-driven ROS signaling pathway in the colorectal cell line (HCT-116). Through mutagenesis and inhibitory studies, we revealed that ERK1/2 acted as an upstream signaling molecule in AP-1 activation, and AKT acted as an upstream signaling molecule in NF-κB activation, which in turn attenuated IL-8 expression. Taken together, we demonstrated that piperine blocked LCA-stimulated IL-8 expression by suppressing Src and EGFR in human CRC HCT-116 cells, thus remarkably attenuating endothelial EA.hy926 cell tube formation.