Curcumin modulates miR-19/PTEN/AKT/p53 axis to suppress bisphenol A-induced MCF-7 breast cancer cell proliferation

Breast cancer is the most common cancer in women. Bisphenol A (BPA), as a known endocrine disrupter, is closely related to the development of breast cancer. Curcumin has been clinically used in chemopreventation and treatment of cancer; however, it remains unknown whether microRNAs are involved in curcumin-mediated protection from BPA-associated promotive effects on breast cancer. In the present study, we showed that BPA exhibited estrogenic activity by increasing the proliferation of estrogen-receptor-positive MCF-7 human breast cancer cells and triggering transition of the cells from G1 to S phase. Curcumin inhibited the proliferative effects of BPA on MCF-7 cells. Meanwhile, BPA-induced upregulation of oncogenic miR-19a and miR-19b, and the dysregulated expression of miR-19-related downstream proteins, including PTEN, p-AKT, p-MDM2, p53, and proliferating cell nuclear antigen, were reversed by curcumin. Furthermore, the important role of miR-19 in BPA-mediated MCF-7 cell proliferation was also illustrated. These results suggest for the first time that curcumin modulates miR-19/PTEN/AKT/p53 axis to exhibit its protective effects against BPA-associated breast cancer promotion. Findings from this study could provide new insights into the molecular mechanisms by which BPA exerts its breast-cancer-promoting effect as well as its target intervention.

UBR2 Enriched in p53 Deficient Mouse Bone Marrow Mesenchymal Stem Cell-Exosome Promoted Gastric Cancer Progression via Wnt/β-Catenin Pathway

The deficiency or mutation of p53 has been linked to several types of cancers. The mesenchymal stem cell (MSC) is an important component in the tumor microenvironment, and exosomes secreted by MSCs can transfer bioactive molecules, including proteins and nucleic acid, to other cells in the tumor microenvironment to influence the progress of a tumor. However, whether the state of p53 in MSCs can impact the bioactive molecule secretion of exosomes to promote cancer progression and the regulatory mechanism remains elusive. Our study aimed to investigate the regulation of ubiquitin protein ligase E3 component n-recognin 2 (UBR2) enriched in exosomes secreted by p53 deficient mouse bone marrow MSC (p53-/- mBMMSC) in gastric cancer progression in vivo and in vitro. We found that the concentration of exosome was significantly higher in p53-/- mBMMSC than that in p53 wild-type mBMMSC (p53+/+ mBMMSC). In particular, UBR2 was highly expressed in p53-/- mBMMSC cells and exosomes. P53-/- mBMMSC exosomes enriched UBR2 could be internalized into p53+/+ mBMMSC and murine foregastric carcinoma (MFC) cells and induce the overexpression of UBR2 in these cells which elevated cell proliferation, migration, and the expression of stemness-related genes. Mechanistically, the downregulation of UBR2 in p53-/- mBMMSC exosomes could reverse these actions. Moreover, a majority of Wnt family members, β-catenin, and its downstream genes (CD44, CyclinD1, CyclinD3, and C-myc) were significantly decreased in MFC knockdown UBR2 and β-catenin depletion, an additional depletion of UBR2 had no significant difference in the expression of Nanog, OCT4, Vimentin, and E-cadherin. Taken together, our findings indicated that p53-/- mBMMSC exosomes could deliver UBR2 to target cells and promote gastric cancer growth and metastasis by regulating Wnt/β-catenin pathway. Stem Cells 2017;35:2267-2279.

Anti-inflammatory Activity of Magnesium Isoglycyrrhizinate Through Inhibition of Phospholipase A2/Arachidonic Acid Pathway

Glycyrrhiza glabra (licorice) has been known to possess various pharmacological properties including anti-inflammatory, antioxidants, antiviral, and hepatoprotective activities. Magnesium isoglycyrrhizinate (MgIG), a magnesium salt of 18-α glycyrrhizic acid stereoisomer, is clinically used for the treatment of inflammatory liver diseases. However, the mechanism by which MgIG exerts its anti-inflammatory effects remains unknown. In the present study, we investigated the inhibitory potential of MgIG in phospholipase A2 (PLA2)/arachidonic acid (AA) pathway and release of the pathway-generated inflammatory lipid mediators in RAW264.7 macrophages. Results revealed that MgIG suppressed LPS-induced activation of PLA2 and production of AA metabolites such as prostaglandin E2 (PGE2), prostacyclin (PGI2), thromboxane 2 (TXB2), and leukotrienes (LTB4) in macrophages. Furthermore, LPS-induced AA-metabolizing enzymes including COX-2, COX-1, 5-LOX, TXB synthase, and PGI2 synthase were significantly inhibited by MgIG. Taken together, our data suggest that modulation of cyclooxygenase (COXs) and 5-lipoxygenase (LOX) pathways in AA metabolism could be a novel mechanism for the anti-inflammatory effects of MgIG.

Medium-chain triglyceride ameliorates insulin resistance and inflammation in high fat diet-induced obese mice

PURPOSE

The aim of the present study was to investigate the in vivo effects of dietary medium-chain triglyceride (MCT) on inflammation and insulin resistance as well as the underlying potential molecular mechanisms in high fat diet-induced obese mice.

METHODS

Male C57BL/6J mice (n = 24) were fed one of the following three diets for a period of 12 weeks: (1) a modified AIN-76 diet with 5 % corn oil (normal diet); (2) a high-fat control diet (17 % w/w lard and 3 % w/w corn oil, HFC); (3) an isocaloric high-fat diet supplemented with MCT (17 % w/w MCT and 3 % w/w corn oil, HF-MCT). Glucose metabolism was evaluated by fasting blood glucose levels and intraperitoneal glucose tolerance test. Insulin sensitivity was evaluated by fasting serum insulin levels and the index of homeostasis model assessment-insulin resistance. The levels of serum interleukin-6 (IL-6), interleukin-10 (IL-10), and tumor necrosis factor-α were measured by ELISA, and hepatic activation of nuclear factor κB (NF-κB) and mitogen-activated protein kinase (MAPK) pathways was determined using western blot analysis.

RESULTS

Compared to HFC diet, consumption of HF-MCT did not induce body weight gain and white adipose tissue accumulation in mice. HFC-induced increases in serum fasting glucose and insulin levels as well as glucose intolerance were prevented by HF-MCT diet. Meanwhile, HF-MCT resulted in significantly lower serum IL-6 level and higher IL-10 level, and lower expression levels of inducible nitric oxide synthase and cyclooxygenase-2 protein in liver tissues when compared to HFC. In addition, HF-MCT attenuated HFC-triggered hepatic activation of NF-κB and p38 MAPK.

CONCLUSIONS

Our study demonstrated that MCT was efficacious in suppressing body fat accumulation, insulin resistance, inflammatory response, and NF-κB and p38 MAPK activation in high fat diet-fed mice. These data suggest that MCT may exert beneficial effects against high fat diet-induced insulin resistance and inflammation.

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.

Phthalates promote prostate cancer cell proliferation through activation of ERK5 and p38

Prostate cancer is one of the most commonly diagnosed cancers in man. Studies have shown that phthalates may act as promoters in various types of cancer; however, the role of phthalates in prostate cancer has been rarely reported. The MAPK/AP-1 pathway is a vital regulator of cell proliferation in cancer. In this report we found that three typical phthalates, diethylhexyl phthalate (DEHP), Butyl benzyl phthalate (BBP) and Dibutyl phthalate (DBP), up-regulated cyclinD1 and PCNA, down-regulated P21, inducing proliferation of prostate cancer cells. Furthermore, we found that phthalates increased the expression of p-ERK5 and p-p38, along with upregulation of AP-1 (p-c-fos and p-c-jun). In studies with ERK5 and a p38 inhibitor, our data showed that downregulation of p-ERK5 or p38 inhibited phthalate-triggered cell proliferation. Taken together, findings from this study suggest that phthalates activate MAPK/AP-1 pathway and may potentially promote cell proliferation in prostate cancer, thus providing new insight into the effects and the underlying mechanism of phthalates on prostate cancer.

Modulation of miR-34a in curcumin-induced antiproliferation of prostate cancer cells

Curcumin is a phytochemical which exhibits significant inhibitory effect in multiple cancers including prostate cancer. MicroRNA-34a (miR-34a) was found to be a master tumor suppressor miRNA and regulated the growth of cancer cells. To date, however, the role of miR-34a in the anticancer action of curcumin against prostate cancer has been rarely reported. In the present study, we showed that curcumin altered the expression of cell cycle-related genes (cyclin D1, PCNA, and p21) and inhibited the proliferation of prostate cancer cells. Furthermore, we found that curcumin significantly upregulated the expression of miR-34a, along with the downregulated expression of β-catenin and c-myc in three prostate cancer cell lines. Inhibition of miR-34a activated β-catenin/c-myc axis, altered cell cycle-related genes expression and significantly suppressed the antiproliferation effect of curcumin in prostate cancer cells. Findings from this study revealed that miR-34a plays an important role in the antiproliferation effect of curcumin in prostate cancer.

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.

Benzidine induces epithelial-mesenchymal transition in human uroepithelial cells through ERK1/2 pathway

Prolonged benzidine exposure is a known cause of urothelial carcinoma (UC). Benzidine-induced epithelial-to-mesenchymal transition (EMT) is critically involved in cell malignant transformation. The role of ERK1/2 in regulating benzidine-triggered EMT has not been investigated. This study was to investigate the regulatory role of ERK1/2 in benzidine-induced EMT. By using wound healing and transwell chamber migration assays, we found that benzidine could increase SV-HUC-1 cells invasion activity, western blotting and Immunofluorescence showed that the expression levels of Snail, β-catenin, Vimentin, and MMP-2 were significantly increased, while, the expression levels of E-cadherin, ZO-1 were decreased. To further demonstrate the mechanism in this process, we found that the phosphorylation of ERK1/2, p38, JNK and AP-1 proteins were significantly enhanced compared to the control group (*P < 0.05). Afterward, treated with MAPK pathways inhibitors, only ERK inhibitor（U0126）could reduce the expression of EMT markers in SV-HUC-1 cells, but not p38 and JNK inhibitor（SB203580, SP600125）, which indicated that benzidine induces the epithelial-mesenchymal transition in human uroepithelial cells through ERK1/2 pathway. Taken together, findings from this study could provide into the molecular mechanisms by which benzidine exerts its bladder-cancer-promoting effect as well as its target intervention.

YAP signaling in gastric cancer-derived mesenchymal stem cells is critical for its promoting role in cancer progression

Cancer-associated mesenchymal stem cells (MSCs) are critically involved in tumor development and progression. However, the mechanisms of action for MSCs in cancer remain largely unknown. Herein, we reported that the expression of Yes-associated protein 1 (YAP) was higher in gastric cancer derived mesenchymal stem cells (GC‑MSCs) than that in bone marrow derived MSCs (BM‑MSCs). YAP knockdown not only inhibited the growth, migration and invasion, and stemness of GC‑MSCs, but also suppressed their promoting effect on gastric cancer growth in vitro and in vivo. In addition, the interference of YAP expression in GC‑MSCs also attenuated the promoting role of gastric cancer cells in endothelial cell tube formation and migration. Mechanistically, YAP knockdown reduced the activation of β-catenin and its target genes in gastric cancer cells by GC‑MSCs. Taken together, these findings suggest that YAP activation in GC‑MSCs plays an important role in promoting gastric cancer progression, which may represent a potential target for gastric cancer therapy.

Modulation of miR-19 in Aluminum-Induced Neural Cell Apoptosis

Neuronal cell death is an important feature of neurodegeneration. Aluminum is associated with neurodegenerative disorders, particularly Alzheimer's disease. However, the underlying mechanisms by which aluminum induces neuronal apoptosis remain to be elucidated. miR-19 is a key miRNA implicated in regulating cell survival process, while the role of miR-19 in Alzheimer's disease has not been investigated. In the present study, we showed that Aluminum maltolate (Al-malt), a lipophilic Al complex which is a common component of human diet with the ability to facilitate the entry of Al into the brain, induced apoptosis in human neuroblastoma SH-SY5Y cells, along with downregulation of miR-19a/miR-19b, upregulation of miR-19-targeted PTEN, and alterations of its downstream apoptosis related proteins including AKT, p53, Bax, and Bcl-2. miR-19 overexpression attenuated Al-malt-induced apoptosis as well as changes in the expression of apoptosis related proteins in SH-SY5Y cells. We further revealed that exposure of rats to Al-malt for 12 weeks at doses relevant to human exposure significantly elevated Al concentrations in serum and brain tissues. Al-malt dose-dependently induced apoptosis in rat brain, as evidenced by increased caspase activation and increased TUNEL staining. Consistent with in vitro results, Al-malt reduced miR-19 expression and altered the expression of apoptotic related proteins in rat brain. Taken together, our data suggest for the first time that miR-19 modulation is critically involved in Al-induced neural cell apoptosis. Findings from this study could provide new insight into the molecular mechanisms of Al-associated neurodegenerative pathogenesis.

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.

Cigarette smoke induced urocystic epithelial mesenchymal transition via MAPK pathways

Cigarette smoke has been shown to be a major risk factor for bladder cancer. Epithelial-mesenchymal transition (EMT) is a crucial process in cancer development. The role of MAPK pathways in regulating cigarette smoke-triggered urocystic EMT remains to be elucidated. Human normal urothelial cells and BALB/c mice were used as in vitro and in vivo cigarette smoke exposure models. Exposure of human normal urothelial cells to cigarette smoke induced morphological change, enhanced migratory and invasive capacities, reduced epithelial marker expression and increased mesenchymal marker expression, along with the activation of MAPK pathways. Moreover, we revealed that ERK1/2 and p38 inhibitors, but rather JNK inhibitor, effectively attenuated cigarette smoke-induced urocystic EMT. Importantly, the regulatory function of ERK1/2 and p38 pathways in cigarette smoke-triggered urocystic EMT was further confirmed in mice exposed to CS for 12 weeks. These findings could provide new insight into the molecular mechanisms of cigarette smoke-associated bladder cancer development as well as its potential intervention.

miR-19 targeting of PTEN mediates butyl benzyl phthalate-induced proliferation in both ER(+) and ER(-) breast cancer cells

Breast cancer is the most common cancer among women worldwide. Butyl benzyl phthalate (BBP) is ubiquitous in human's environment, and is strongly linked to breast cancer development. microRNA (miRNA) is an important regulator of target genes. So far, no studies have been reported yet to reveal the action of miRNAs in BBP-mediated breast cancer cell proliferation. In this study, we showed that BBP induced proliferation of both ER(+) MCF-7 and ER(-) MDA-MB-231 breast cancer cells, proved by increased cell viability, transition of cell cycle from G1 to S phase, upregulation of proliferating cell nuclear antigen (PCNA) and Cyclin D1, and downregulation of p21. Meanwhile, the expression of oncogenic miR-19a/b and PTEN/AKT/p21 axis was also modulated by BBP. Furthermore, for the first time we revealed that miR-19 played crucial role in the promoting effect of BBP on breast cancer cells through targeting PTEN 3'UTR. Findings from this study could provide an important new perspective on the molecular mechanisms through which BBP exerts its promoting effect on breast cancer as well as its target intervention.

Butyl benzyl phthalate promotes prostate cancer cell proliferation through miR-34a downregulation

Prostate cancer is the most common malignancy in men. Phthalate esters are a class of environmental endocrine disruptors and were reported to be cancer promoting agents, however the potential role of phthalate esters in prostate cancer has been rarely reported. Mounting evidence has shown that miR-34a is a master tumor suppressor miRNA in cancer. The aim of this study was to investigate the role of butyl benzyl phthalate (BBP), one of the typical phthalate esters, in cell proliferation of prostate cancer cells. Human prostate cancer LNCaP and PC-3 cells were exposed to low dose of BBP for 6 days. The results showed that 10-6 and 10-7 mol/L BBP increased the expression of cyclinD1 and PCNA, decreased p21 expression, and induced cell growth in both LNCaP and PC-3 cells. Furthermore, we found that BBP significantly downregulated the expression of miR-34a, along with upregulation of miR-34a target gene c-myc. Using cell tranfection of miR-34a mimic and inhibitor, we demonstrated that BBP promoted cell proliferation through miR-34a/c-myc axis in prostate cancer cells. Findings from this study could provide new insight into the involvement and the molecular mechanism of phthalate esters on prostate cancer.

Cigarette smoke extract-induced proliferation of normal human urothelial cells via the MAPK/AP-1 pathway

Bladder cancer (BC) is universally acknowledged as a significant public health issue, worldwide. Numerous studies have demonstrated that cigarette smoke is the primary risk factor for BC. However, the mechanism of cigarette smoke-induced BC has not been fully elucidated. Sustained epithelial cell hyperplasia has been identified as a preneoplastic lesion during the formation of BC. The aim of the present study was to investigate whether exposure to cigarette smoke extract (CSE) induced proliferation in normal human urothelial SV-HUC-1 cells. Furthermore, the role of the mitogen-activated protein kinase (MAPK)/activator protein-1 (AP-1) pathway in the CSE-induced proliferation of SV-HUC-1 cells was also investigated. The present study revealed that the expression of phosphorylated-extracellular signal regulated protein kinase (ERK)1/2, Jun N-terminal kinase (JNK) and p38 was significantly increased following exposure to CSE in SV-HUC-1 cells. Furthermore, CSE increased the expression of the proliferation markers, cyclin D1 and proliferating cell nuclear antigen. By contrast, CSE attenuated the expression of p21. In addition, the inhibitors of ERK1/2 and JNK reversed the aforementioned effects of CSE. However, p38 inhibition did not reverse CSE-induced proliferation. In conclusion, the results of the present study demonstrated that exposure to CSE induced proliferation in normal human urothelial cells. Furthermore, the results also indicated that the ERK1/2 and JNK pathways are important for the regulation of proliferation via the AP-1 proteins.

Gastric-cancer-derived mesenchymal stem cells: a promising target for resveratrol in the suppression of gastric cancer metastasis

The tumor microenvironment (TM) is an essential factor of tumor progression. Mesenchymal stem cells (MSCs) are important components of the TM and play critical roles in cancer metastasis. Resveratrol (RES) is a potential antitumor drug that has attracted extensive attention. However, it remains unclear whether RES can exert its antitumor activity by targeting MSCs located in the TM. In this study, we demonstrated that the conditioned medium of gastric-cancer-derived MSCs (GC-MSCs) promoted gastric cancer (GC) metastasis and facilitated the progression of epithelialmesenchymal transition (EMT) of GC cells. However, after pretreatment with RES, the prometastatic effect of GC-MSCs on GC cells was reversed. Furthermore, RES reduced GC-MSC (IL-6, IL-8, MCP-1, VEGF) gene expression and protein secretion, and counteracted the activation of the GC-MSC-induced Wnt/β-catenin signaling of GC cells, with less β-catenin nuclear transport and declined expression of β-catenin, CD44, and CyclinD3 in GC cells. Re-expression of β-catenin impaired the inhibitory effect of RES on GC cells. In conclusion, RES restricted the mobility increase of GC cells and reversed the progress of EMT induced by GC-MSCs by inactivating the Wnt/β-catenin signaling. GC-MSCs are promising target for RES in the inhibition of GC metastasis.

Cigarette smoke extract induces epithelial-mesenchymal transition of human bladder cancer T24 cells through activation of ERK1/2 pathway

Bladder cancer is a common genitourinary malignant disease worldwide. Abundant evidence has shown that cigarette smoke (CS) is a crucial risk factor for bladder cancer. Nevertheless, the mechanism underlying the relationship between cigarette smoking and bladder cancer remains unclear. In the present study, we investigated the effects of cigarette smoke extract (CSE) on mitogen-activated protein kinase (MAPK) pathway activation and EMT alterations in human bladder cancer T24 cells, and the preventive effect of extracellular regulated protein kinases 1 and 2 (ERK1/2) inhibitor U0126 was further examined. Our results illustrated that CSE exposure induced morphological change of human bladder cancer T24 cells, enhanced migratory and invasive capacities, reduced epithelial marker expression and elevated mesenchymal marker expression. Meanwhile, exposure of T24 cells to CSE resulted in activation of ERK1/2 pathway as well as activator protein 1 (AP-1) proteins. Interestingly, treatment with ERK1/2 inhibitor U0126 effectively abrogated CSE-triggered EMT and ERK1/2/AP-1 activation. These findings provide novel insight into the molecular mechanisms of CS-associated bladder cancer and may open up new avenues in the search for potential target of bladder cancer intervention.

Folic Acid Protected Neural Cells Against Aluminum-Maltolate-Induced Apoptosis by Preventing miR-19 Downregulation

Aluminum (Al)-induced apoptosis is considered as the major cause of its neurotoxicity. Folic acid possesses neuroprotective function by preventing neural cell apoptosis. microRNAs (miRNAs) are important regulators of gene expression participating in cellular processes. As a key component of the miR-17-92 cluster, miR-19 is implicated in regulating apoptotic process, while its role in the neuroprotective effect of folic acid has not been investigated. The present study aimed to investigate the potential involvement and function of miR-19 in the protective action of folic acid against Al-induced neural cell apoptosis. Human SH-SY5Y cells were treated with Al-maltolate (Al-malt) in the presence or absence of folic acid. Results showed that Al-malt-induced apoptosis of SH-SY5Y cells was effectively prevented by folic acid. Al-malt suppressed the expression of miR-19a/19b, along with alterations of miR-19 related apoptotic proteins including PTEN, p-AKT, p53, Bax, Bcl-2, caspase 9 and caspase 3; and these effects were ameliorated by folic acid. miR-19 inhibitor alone induced apoptosis of SH-SY5Y cells. Combination treatment of folic acid and miR-19 inhibitor diminished the neuroprotective effect of folic acid. These findings demonstrated that folic acid protected neuronal cells against Al-malt-induced apoptosis by preventing the downregulation of miR-19 and modulation of miR-19 related downstream PTEN/AKT/p53 pathway.

miR-374 mediates the malignant transformation of gastric cancer-associated mesenchymal stem cells in an experimental rat model

Mesenchymal stem cells (MSCs) are a critical component of the tumor microenvironment. Upon distinct pathological stimulus, MSCs show phenotypic and functional changes. Gastric cancer is one of the leading causes of cancer‑related deaths worldwide. The roles and mechanisms of MSCs in gastric cancer have not been well characterized. In the present study, we investigated the roles of MSCs in the malignant transformation from gastritis to gastric cancer using an N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced gastric cancer model. We isolated MSCs from the gastric tissues of normal (RGN-MSCs) and MNNG-exposed rats (RGI-MSCs), and compared the biological properties of RGI-MSCs with RGN-MSCs. We found that RGI-MSCs had increased proliferative and migratory capabilities than these capacities noted in the RGN-MSCs. In addition, RGI-MSCs produced higher levels of IL-6, CXCL10 and MCP-1 than RGN-MSCs. Moreover, RGI-MSCs promoted the migration of normal gastric mucosa epithelial cells by inducing epithelial-mesenchymal transition (EMT). The upregulation of miR-374 in RGI-MSCs was partially responsible for their increased proliferative and migratory capabilities. Collectively, our findings provide new evidence for the roles of MSCs in gastric carcinogenesis, suggesting that targeting gastric cancer-associated MSCs may represent a novel avenue for gastric cancer therapy.

ERK5 positively regulates cigarette smoke-induced urocystic epithelial-mesenchymal transition in SV‑40 immortalized human urothelial cells

Bladder cancer is universally acknowledged as a significant public health issue. Abundant evidence shows that cigarette smoke (CS) is the primary risk factor for bladder cancer. However, the mechanism of CS-induced bladder cancer has not been fully elucidated. CS-induced epithelial-mesenchymal transition (EMT) is critically involved in cell malignant transformation. The role of ERK5, the lesser studied member of the MAPK family, in regulating CS-triggered EMT has not yet been investigated. The objective of the present study was to investigate the regulatory role of ERK5 in CS-induced urocystic EMT. SV-40 immortalized normal human urothelial cells (SV-HUC-1) were used as in vitro CS exposure models. EMT phenotypic alterations were assessed by changes in cell morphology, invasive capacity, as well as expression of epithelial and mesenchymal markers. Protein and mRNA expression levels were analyzed by western blotting and quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). ERK5 inhibition studies were performed with a specific inhibitor. Exposure of SV-HUC-1 cells to CS induced morphological change, enhanced invasive capacity, reduced epithelial marker expression and increased mesenchymal marker expression. Importantly, we demonstrated for the first time that ERK5 positively regulated CS-mediated EMT in urothelial cells, as evidenced by the findings that CS promoted ERK5 activation, and that the CS-triggered alteration in the EMT phenotype was reversed by ERK5 inhibition.

Cigarette smoke extract induces the proliferation of normal human urothelial cells through the NF-κB pathway

Bladder cancer is a common genitourinary malignant disease worldwide. Convincing evidence shows that cigarette smoke (CS) is a crucial risk factor for bladder cancer, yet the role of the NF-κB signaling pathway in the development of CS-associated bladder cancer has not been fully elucidated. In the present study, we found that exposure to cigarette smoke extract (CSE) induced proliferation and triggered the transition of normal human urothelial cells from G1 to S phase. Moreover, CSE exposure enhanced the expression of cyclin D1 and proliferating cell nuclear antigen (PCNA) and decreased the expression of p21 in SV-HUC-1 cells. Furthermore, the levels of nuclear NF-κB p65/p50 were significantly elevated by CSE. Pre-treatment with the NF-κB inhibitor (PDTC) reversed CSE-triggered cell proliferation. Taken together, our study revealed that CSE induced proliferation of normal human urothelial cells through the NF-κB pathway, and these data enhance our understanding of the CSE-related carcinogenesis of bladder cancer.

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.

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.

Curcumin reverses benzidine-induced cell proliferation by suppressing ERK1/2 pathway in human bladder cancer T24 cells

Bladder cancer is one of the leading causes of cancer-related death in the world. Prolonged exposure to benzidine is a known cause of bladder cancer. Curcumin has been clinically used in chemoprevention and treatment of cancer. However, it remains unknown whether mitogen-activated protein kinase (MAPK) pathways are involved in curcumin-mediated protection from benzidine-associated promotive effects on bladder cancer. In our study, we found that benzidine increased the proliferation of human bladder cancer T24 cells, triggered transition of the cells from G1 to S phase, elevated the expression of cyclin D1 and proliferating cell nuclear antigen (PCNA) and decreased p21 expression. Meanwhile, exposure of T24 cells to benzidine resulted in activation of extracellular regulated protein kinases 1 and 2 (ERK1/2) pathway as well as activator protein 1 (AP-1) proteins. Treatment with ERK1/2 inhibitor U0126 or curcumin effectively abrogated benzidine-triggered cell proliferation and ERK1/2/AP-1 activation. These results suggested for the first time that curcumin in low concentrations played a protective role in benzidine-induced ERK1/2/AP-1 activation and proliferation of bladder cancer cells, therefore providing new insights into the pathogenesis and chemoprevention of benzidine-associated bladder cancer.