Cong Huang

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. Copyright

Curcumin Suppresses Lung Cancer Stem Cells via Inhibiting Wnt/β-catenin and Sonic Hedgehog Pathways

Cancer stem cells (CSCs) are highly implicated in the progression of human cancers. Thus, targeting CSCs may be a promising strategy for cancer therapy. Wnt/β‐catenin and Sonic Hedgehog pathways play an important regulatory role in maintaining CSC characteristics. Natural compounds, such as curcumin, possess chemopreventive properties. However, the interventional effect of curcumin on lung CSCs has not been clarified. In the present study, tumorsphere formation assay was used to enrich lung CSCs from A549 and H1299 cells. We showed that the levels of lung CSC markers (CD133, CD44, ALDHA1, Nanog and Oct4) and the number of CD133‐positive cells were significantly elevated in the sphere‐forming cells. We further illustrated that curcumin efficiently abolished lung CSC traits, as evidenced by reduced tumorsphere formation, reduced number of CD133‐positive cells, decreased expression levels of lung CSC markers, as well as proliferation inhibition and apoptosis induction. Moreover, we demonstrated that curcumin suppressed the activation of both Wnt/β‐catenin and Sonic Hedgehog pathways. Taken together, our data suggested that curcumin exhibited its interventional effect on lung CSCs via inhibition of Wnt/β‐catenin and Sonic Hedgehog pathways. These novel findings could provide new insights into the potential therapeutic application of curcumin in lung CSC elimination and cancer intervention. Copyright

Curcumin attenuates BPA-induced insulin resistance in HepG2 cells through suppression of JNK/p38 pathways

Bisphenol A (BPA) is an artificial environmental endocrine disrupting chemicals. Accumulating evidence indicates that exposure to BPA contributes to insulin resistance through diverse mechanism including inflammation and oxidative stress. Previous studies have suggested curcumin as a safe phytochemical which can improve obesity-related insulin resistance, inflammation and oxidative stress. The present study aimed to investigate the ability of curcumin to prevent BPA-induced insulin resistance in vitro and the underlying mechanism. Following the establishmet of in vitro insulin resistance via BPA treatment in human liver HepG2 cells, the protective effects of curcumin were determiend. We showed that treatment of HepG2 cells with 100nM BPA for 5days induced significantly decreased glucose consumption, impaired insulin signaling, elevation of pro-inflammatory cytokines and oxidative stress, and activation of signaling pathways; inhibition of JNK and p38 pathways, but not ERK nor NF-κB pathways, improved glucose consumption and insulin signaling in BPA-treated HepG2 cells. Moreover, we revealed that curcumin effectively attenuated the spectrum of effects of BPA-triggered insulin resistance, whereas pretreatment with JNK and p38 agonist anisomycin could significantly compensate the effects caused by curcumin. These data illustrated the role of JNK/p38 activation in BPA-induced insulin resistance and suggested curcumin as a promising candidate for the intervention of BPA-induced insulin resistance.

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. Copyright

miR-19 targeting of GSK3β mediates sulforaphane suppression of lung cancer stem cells

Cancer stem cells (CSCs) play a central role in the development of cancer. The canonical Wnt/β-catenin pathway is critical for maintaining stemness of CSCs. Phytochemicals from dietary compounds possess anti-CSCs properties and have been characterized as promising therapeutic agents for the prevention and treatment of many cancers. To date, the involvement and function of miR-19, a key oncogenic miRNA, in regulating Wnt/β-catenin pathway and lung CSCs has not been defined. Meanwhile, the effect of sulforaphane (SFN) on lung CSCs also remains to be elucidated. Here, we reported that lung CSCs up-regulated miR-19a and miR-19b expression. Overexpression of miR-19a/19b enhanced the ability of tumorsphere formation, up-regulated the expression of lung CSCs markers, increased Wnt/β-catenin pathway activation and β-catenin/TCF transcriptional activity in lung CSCs. In contrary, down-regulation of miR-19 suppressed lung CSCs activity and Wnt/β-catenin activation. We further revealed that miR-19 activated Wnt/β-catenin pathway by directly targeting GSK3β, the key negative modulator of this pathway. Moreover, we showed that SFN exhibited inhibitory effect on lung CSCs through suppressing miR-19 and Wnt/β-catenin pathway. Taken together, these data illustrate the role of miR-19 in regulating lung CSCs traits and miR-19/GSK3β/β-catenin axis in SFN intervention of lung CSCs. Findings from this study could provide important new insights into the molecular mechanisms of lung CSCs regulation as well as its target intervention.

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

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.

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 Alzheimers 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 Alzheimers 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.

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.

Abstract 3182: Tobacco smoke induces pulmonary neuroendocrine alterations in vivo

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Tobacco smoke is the leading cause of lung cancer. High-grade malignant pulmonary neuroendocrine tumors, including small cell lung cancers (SCLCs) and large cell neuroendocrine carcinomas (LCNECs), are almost exclusively associated with tobacco smoking. Unanalogous to most of other lung tumors such as squamous cell carcinomas, adenocarcinoma, adenosquamous carcinoma or carcinoid, no precursor lesions for high-grade lung neuroendocrine tumors have so far been identified. The purpose of the present study was to investigate the effects of tobacco smoke on pulmonary neuroendocrine alterations in phenotypically normal cells in vivo. Male BALB/c mice were exposed to tobacco smoke for 6h/day, 7days/week for 12 weeks. Pulmonary histology, neuroendocrine differentiation as well as MAPK/AP-1 activation were examined in lung tissues. Exposure to tobacco smoke significantly induced expression of neuroendocrine differentiation markers such as chromogranin A, neural cell adhesion molecule/(CD56), synaptophysin, and neuron specific enolase, as demonstrated by immunohistochemistry, Western blotting and real-time PCR. The expression levels of epithelial markers, including E-cadherin, zona ocludens-1, cytokeratin 5 and involucrin, were downregulated by tobacco smoke. Moreover, tobacco smoke significantly increased levels of p-ERK1/2, p-JNK and p-p38, while it suppressed p-ERK5 level. Expression of Jun and Fos proteins were differentially regulated by tobacco smoke. Taken together, the present study provides experimental evidence for the first time that tobacco smoke induces pulmonary neuroendocrine differentiation, shedding new light on the carcinogenic process of pulmonary neuroendocrine tumors. Citation Format: Wei Xie, Zhaofeng Liang, Ying Yin, Chunfeng Xie, Hao Geng, Li Zhao, Rui Wu, Xiaoting Li, Feifei Deng, Jieshu Wu, Shanshan Geng, Mingming Zhu, Jianyun Zhu, Weiwei Zhu, Cong Huang, Caiyun Zhong. Tobacco smoke induces pulmonary neuroendocrine alterations in vivo . [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3182. doi:10.1158/1538-7445.AM2014-3182