Curcumin reversed chronic tobacco smoke exposure induced urocystic EMT and acquisition of cancer stem cells properties via Wnt/β-catenin

Tobacco smoke (TS) is the most important single risk factor for bladder cancer. Epithelial-mesenchymal transition (EMT) is a transdifferentiation process, involved in the initiation of TS-related cancer. Cancer stem cells (CSCs) have an essential role in the progression of many tumors including TS-related cancer. However, the molecular mechanisms of TS exposure induced urocystic EMT and acquisition of CSCs properties remains undefined. Wnt/β-catenin pathway is critical for EMT and the maintenance of CSCs. The aim of our present study was to investigate the role of Wnt/β-catenin pathway in chronic TS exposure induced urocystic EMT, stemness acquisition and the preventive effect of curcumin. Long time TS exposure induced EMT changes and the levels of CSCs' markers were significant upregulated. Furthermore, we demonstrated that Wnt/β-catenin pathway modulated TS-triggered EMT and stemness, as evidenced by the findings that TS elevated Wnt/β-catenin activation, and that TS-mediated EMT and stemness were attenuated by Wnt/β-catenin inhibition. Treatment of curcumin reversed TS-elicited activation of Wnt/β-catenin, EMT and CSCs properties. Collectively, these data indicated the regulatory role of Wnt/β-catenin in TS-triggered urocystic EMT, acquisition of CSCs properties and the chemopreventive effect of curcumin.

Effects of Curcumin on Tobacco Smoke-induced Hepatic MAPK Pathway Activation and Epithelial-Mesenchymal Transition In Vivo

Tobacco smoke is a major risk factor for hepatic cancer. Epithelial-mesenchymal transition (EMT) induced by tobacco smoke is crucially involved in the initiation and development of cancer. Mitogen-activated protein kinase (MAPK) pathways play important roles in tobacco smoke-associated carcinogenesis including EMT process. The chemopreventive effect of curcumin supplementation against cancers has been reported. In this study, we investigated the effects of tobacco smoke on MAPK pathway activation and EMT alterations, and then the preventive effect of curcumin was examined in the liver of BALB/c mice. Our results indicated that exposure of mice to tobacco smoke for 12 weeks led to activation of ERK1/2, JNK, p38 and ERK5 pathways as well as activator protein-1 (AP-1) proteins in liver tissue. Exposure of mice to tobacco smoke reduced the hepatic mRNA and protein expression of the epithelial markers, while the hepatic mRNA and protein levels of the mesenchymal markers were increased. Treatment of curcumin effectively attenuated tobacco smoke-induced activation of ERK1/2 and JNK MAPK pathways, AP-1 proteins and EMT alterations in the mice liver. Our data suggested the protective effect of curcumin in tobacco smoke-triggered MAPK pathway activation and EMT in the liver of BALB/c mice, thus providing new insights into the chemoprevention of tobacco smoke-associated hepatic cancer. Copyright © 2017 John Wiley & Sons, Ltd.

Curcumin Suppresses MAPK Pathways to Reverse Tobacco Smoke-induced Gastric Epithelial-Mesenchymal Transition in Mice

Tobacco smoke (TS) has been shown to cause gastric cancer. Epithelial-mesenchymal transition (EMT) is a crucial pathophysiological process in cancer development. Mitogen-activated protein kinase (MAPK) pathways play central roles in tumorigenesis including EMT process. Curcumin is a promising chemopreventive agent for several types of cancers. In the present study, we investigated the effects of TS on MAPK pathway activation and EMT alterations in the stomach of mice, and the preventive effect of curcumin was further examined. Results showed that exposure of mice to TS for 12 weeks resulted in activation of extracellular regulated protein kinases 1 and 2 (ERK1/2), the Jun N-terminal kinase (JNK), p38, and ERK5 MAPK pathways as well as activator protein 1 (AP-1) proteins in stomach. TS reduced the mRNA and protein expression levels of the epithelial markers E-cadherin and ZO-1, while the mRNA and protein expression levels of the mesenchymal markers vimentin and N-cadherin were increased. Treatment of curcumin effectively abrogated TS-triggered gastric activation of ERK1/2 and JNK MAPK pathways, AP-1 proteins, and EMT alterations. These results suggest for the first time the protective effects of curcumin in long-term TS exposure-induced gastric MAPK activation and EMT, thus providing new insights into the pathogenesis and chemoprevention of TS-associated gastric cancer.

ERK5 negatively regulates tobacco smoke-induced pulmonary epithelial-mesenchymal transition

As the primary cause of lung cancer, tobacco smoke (TS) promotes the initiation and progression of lung tumorigenesis. Epithelial-mesenchymal transition (EMT) is a crucial process involved in cell malignant transformation. The role of ERK5, the lesser studied member of MAPKs family, in regulating TS-triggered pulmonary EMT has not been investigated. Normal human bronchial epithelial cells and BALB/c mice were used as in vitro and in vivo TS exposure models. Exposure of normal human bronchial epithelial cells to TS for 7 days induced morphological change, enhanced migratory and invasive capacities, reduced epithelial marker expression and increased mesenchymal marker expression. Importantly, we demonstrated for the first time that ERK5 negatively regulated TS-mediated lung epithelial EMT, as evidenced by the findings that TS suppressed ERK5 activation, and that TS-triggered EMT was mimicked with ERK5 inhibition and reversed by ERK5 overexpression. The negative regulation of ERK5 on pulmonary EMT was further confirmed in mice exposed to TS for 12 weeks. Taken together, our data suggest that ERK5 negatively regulates TS-mediated pulmonary EMT. These findings provide new insight into the molecular mechanisms of TS-associated lung tumorigenesis and may open up new avenues in the search for potential target of lung cancer intervention.

Hesperidin Reversed Long-Term N-methyl-N-nitro-N-Nitroguanidine Exposure Induced EMT and Cell Proliferation by Activating Autophagy in Gastric Tissues of Rats

Gastric cancer is a common malignant tumor worldwide. N-methyl-N-nitro-N-nitroguanidine (MNNG) is one of the most important inducing factors of gastric cancer. Autophagy can affect the occurrence and development of gastric cancer, but the mechanism is not clear. Chemoprevention has been shown to be a rational and very promising approach to the prevention of gastric cancer. Hesperidin is a citrus flavone, an abundant polyphenol in citrus fruits and traditional Chinese medicine. It has an excellent phytochemistry that plays an intervention role in gastric cancer. However, it is unclear whether long-term exposure to MNNG will affect the occurrence of gastric cancer by regulating autophagy and whether hesperidin can play an intervention role in this process. In the present study, we demonstrated that long-term MNNG exposure inhibits autophagy in stomach tissues of rats, promotes the epithelial-mesenchymal transition (EMT) process and cell proliferation and suppresses the activity of the PI3K/AKT pathway. We further found that after rapamycin-activated autophagy, long-term MNNG exposure promoted cell proliferation and EMT were inhibited. In addition, hesperidin promotes autophagy and the activity of the PI3K/AKT pathway, as well as the suppression of proliferation and EMT in the stomach tissues of rats. Our findings indicate that hesperidin reverses MNNG-induced gastric cancer by activating autophagy and the PI3K/AKT pathway, which may provide a new basis for the early prevention and treatment of MNNG-induced gastric cancer.

Curcumin reverses tobacco smoke‑induced epithelial‑mesenchymal transition by suppressing the MAPK pathway in the lungs of mice

Tobacco smoke is a major risk factor for lung cancer. Epithelial‑mesenchymal transition (EMT) is decisive in cancer invasion and metastasis, and therefore promotes cancer progression. Mitogen‑activated protein kinase (MAPK) pathways are implicated in various aspects of cancer development and progression, including the EMT process. The chemopreventive effect of curcumin on carcinogenesis has been reported in vivo and in vitro. The present study investigated tobacco smoke‑induced alterations in the MAPK/activator protein‑1 (AP‑1) pathways, and pulmonary EMT changes in the lungs of mice, and further observed the chemopreventive effect of curcumin. The protein expression levels analyzed by western blot analysis demonstrated that 12 weeks of tobacco smoke exposure activated extracellular‑signal‑regulated kinase (ERK) 1/2, c‑Jun N‑terminal kinase (JNK) and p38 MAPK pathways, in addition to AP‑1, in the lungs of mice, while reducing the activation of ERK5/MAPK pathways. The results also indicated that the mRNA and protein levels of the epithelial markers E‑cadherin and zona occludens‑1 were reduced following tobacco smoke exposure. Conversely, the expression levels of mRNA and protein for the mesenchymal markers vimentin and N‑cadherin were increased. Curcumin treatment inhibited tobacco smoke‑induced MAPK/AP‑1 activation, including ERK1/2, JNK and p38 MAPK pathways, and AP‑1 proteins, and reversed EMT alterations in lung tissue. The results of the present study provide new insights into the molecular mechanisms of tobacco smoke‑associated lung cancer and may open up new avenues in the search for potential therapeutic targets in lung tumorigenesis.

CircRNAs: Emerging Bladder Cancer Biomarkers and Targets

Circular RNAs (circRNAs) are newly discovered intriguing RNAs due to the covalently closed loop structure, high stability, tissue specificity, and functional diversity. In recent years, a large number of circRNAs have been identified through high-throughput sequencing technology and bioinformatics methods, the abnormal expression of circRNAs are closely related to many diseases including bladder cancer (BC). CircRNAs have been proven to have several functions, such as acting as a regulator of parental gene transcription, miRNA sponge and interacting with proteins to regulate its expression. In addition, some circRNAs have been identified to encode proteins. CircRNAs have the characteristics of high abundance, high stability, wide distribution in body fluids, tissue specificity, and developmental stage specificity, which determine that circRNAs has great potential to be utilized as biomarkers for BC. Herein, we briefly summarize the biogenesis, functions and roles, and the current research progress of circRNAs in BC with a focus on the potential application for BC diagnosis, treatment, and prognosis.

Gastric cancer stem cell-derived exosomes promoted tobacco smoke-triggered development of gastric cancer by inducing the expression of circ670

As one of the most common malignant cancers in the world, gastric cancer is caused by mang factors among which tobacco smoke is an important risk factor. Gastric cancer stem cells (GCSCs) and the derived exosomes play a key role in the occurrence and development of gastric cancer, and exosomal circRNA is considered as a new regulatory factor in the development of gastric cancer. However, it is unclear whether tobacco smoke can affect exosomes and their transport circRNAs to promote the development of gastric cancer. Herein, we provided a new insight into tobacco smoke promoting the progression of gastric cancer. In the present study, we demonstrated that tobacco smoke-induced exosomes promoted the spheroidizing ability, stemness genes expression, and epithelial-mesenchymal transition (EMT) process of GCSCs. We further found that hsa-circRNA-000670 (circ670) was up-regulated in tissues of gastric cancer patients with smoking history, tobacco smoke-induced GCSCs, and their exosomes. Functional assays have shown that circ670 knockdown inhibited the stemness and EMT process of GCSCs, whereas circ670 overexpression appeared to have an opposite effect. Our findings indicated that exosomal circ670 promotes the development of tobacco smoke-induced gastric cancer, which may provide insight into the mechanism of tobacco smoke promoting the progression of gastric cancer.

Hesperidin inhibits tobacco smoke-induced pulmonary cell proliferation and EMT in mouse lung tissues via the p38 signaling pathway

Tobacco smoke (TS) is the major cause of lung cancer. The abnormal proliferation and epithelial-mesenchymal transition (EMT) of lung cells promote occurrence and development of lung cancer. The p38 pathway intervenes in this cancer development. Hesperidin also serves a role in human health and disease prevention. The roles of p38 in TS-mediated abnormal cell proliferation and EMT, and the hesperidin intervention thereof are not yet understood. In the present study, it was demonstrated that TS upregulated proliferating cell nuclear antigen, vimentin and N-cadherin expression, whereas it downregulated E-cadherin expression, as assessed using western blotting and reverse transcription-quantitative PCR. Furthermore, it was observed that inhibition of the p38 pathway inhibit TS-induced proliferation and EMT. Hesperidin treatment prevented the TS-induced activation of the p38 pathway, EMT and cell proliferation in mouse lungs. The findings of the present study may provide insights into the pathogenesis of TS-related lung cancer.

Anticancer applications of phytochemicals in gastric cancer: Effects and molecular mechanism

Gastric cancer (GC) is the fourth most common malignant cancer and is a life-threatening disease worldwide. Phytochemicals have been shown to be a rational, safe, non-toxic, and very promising approach to the prevention and treatment of cancer. It has been found that phytochemicals have protective effects against GC through inhibiting cell proliferation, inducing apoptosis and autophagy, suppressing cell invasion and migration, anti-angiogenesis, inhibit Helicobacter pylori infection, regulating the microenvironment. In recent years, the role of phytochemicals in the occurrence, development, drug resistance and prognosis of GC has attracted more and more attention. In order to better understand the relationship between phytochemicals and gastric cancer, we briefly summarize the roles and functions of phytochemicals in GC tumorigenesis, development and prognosis. This review will probably help guide the public to prevent the occurrence and development of GC through phytochemicals, and develop functional foods or drugs for the prevention and treatment of gastric cancer.

Cigarette Smoke-Induced Gastric Cancer Cell Exosomes Affected the Fate of Surrounding Normal Cells via the Circ0000670/Wnt/β-Catenin Axis

Cigarette smoke is a major risk factor for gastric cancer. Exosomes are an important part of intercellular and intra-organ communication systems and can carry circRNA and other components to play a regulatory role in the occurrence and development of gastric cancer. However, it is unclear whether cigarette smoke can affect exosomes and exosomal circRNA to promote the development of gastric cancer. Exosomes secreted by cancer cells promote cancer development by affecting surrounding normal cells. Herein, we aimed to clarify whether the exosomes secreted by cigarette smoke-induced gastric cancer cells can promote the development of gastric cancer by affecting the surrounding gastric mucosal epithelial cells (GES-1). In the present study, we treated gastric cancer cells with cigarette smoke extract for 4 days and demonstrated that cigarette smoke promotes the stemness and EMT of gastric cancer cells and cigarette smoke-induced exosomes promote stemness gene expression, EMT processes and the proliferation of GES-1 cells. We further found that circ0000670 was up-regulated in tissues of gastric cancer patients with smoking history, cigarette smoke-induced gastric cancer cells and their exosomes. Functional assays showed that circ0000670 knockdown inhibited the promoting effects of cigarette smoke-induced exosomes on the stemness and EMT characteristic of GES-1 cells, whereas its overexpression had the opposite effect. In addition, exosomal circ0000670 was found to promote the development of gastric cancer by regulating the Wnt/β-catenin pathway. Our findings indicated that exosomal circ0000670 promotes cigarette smoke-induced gastric cancer development, which might provide a new basis for the treatment of cigarette smoke-related gastric cancer.

Inhibition of tobacco smoke-induced bladder MAPK activation and epithelial-mesenchymal transition in mice by curcumin

Tobacco smoke (TS) has been shown to cause bladder cancer. Epithelial-mesenchymal transition (EMT) is a crucial pathophysiological process in cancer development. MAPK pathways play central roles in tumorigenesis including EMT process. Curcumin is a promising chemopreventive agent for several types of cancers. In the present study we investigated the effects of TS on MAPK pathway activation and EMT alterations in the bladder of mice, and the preventive effect of curcumin was further examined. Results showed that exposure of mice to TS for 12 weeks resulted in activation of ERK1/2, JNK, p38 and ERK5 MAPK pathways as well as AP-1 proteins in bladder. TS reduced mRNA and protein expression levels of epithelial markers E-cadherin and ZO-1, while mRNA and protein expression levels of the mesenchymal markers vimentin and N-cadherin were increased. Curcumin treatment effectively attenuated TS-triggered activation of ERK1/2, JNK and p38 MAPK pathways, AP-1 proteins and EMT alterations in bladder tissue. These results suggest the protective effects of curcumin in TS-induced MAPK activation and EMT, thus providing new insights into the chemoprevention of TS-associated bladder cancer.

Corrigendum: Anticancer applications of phytochemicals in gastric cancer: effects and molecular mechanism

[This corrects the article DOI: 10.3389/fphar.2022.1078090.].

Interventional effect of hesperetin on N-methyl-N'-nitro-N-nitrosoguanidine-induced exosomal circ008274 in affecting normal cells to promote gastric carcinogenesis

BACKGROUND

Hesperetin, a flavonoid predominantly present in citrus fruits, exhibits significant intervention effects on both the initiation and progression of gastric cancer. However, the specific mechanisms underlying this effect remain unclear.

AIM

To investigate the interventional role of hesperetin on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced exosomes in inducing gastric carcinogenesis.

METHODS

Bioinformatics technology was used to identify the critical molecular components underlying hesperetin-mediated inhibition of MNNG induced gastric carcinogenesis through exosomal circular RNA. Biological experiments were conducted to validate these findings.

RESULTS

Exosomes derived from TGES-1 cells (TGES-1-EX) significantly enhanced the proliferation, migration, invasion, epithelial-mesenchymal transition (EMT), and stemness of GES-1 cells. The oncogenic potential of TGES-1-EX was significantly diminished following hesperetin pretreatment. TGES-1-EX with overexpressed or knocked down circ0008274 was extracted and GES-1 cells were treated in combination with hesperetin or alone. Our investigation revealed that hesperetin exerted significant inhibitory effects on MNNG-induced gastric carcinogenesis by exosomal circ0008274. Bioinformatics prediction identified microRNA (miR)-526b-5p as a potential miRNA binding to circ0008274. Functional experiments demonstrated that hesperetin may mediate its intervention in MNNG-induced gastric cancer initiation by targeting miR-526b-5p through exosomal circ0008274. TGES-1-EX circ0008274 promoted the proliferation, EMT, and cancer stem cell-like characteristics in GES-1 cells through miR-526b-5p-mediated regulatory mechanisms.

CONCLUSION

Hesperetin exerted an interventional effect on the gastric carcinogenesis process, particularly through the modulation of exosomal circ0008274 and its interaction with miR-526b-5p.