Propofol induces proliferation and invasion of gallbladder cancer cells through activation of Nrf2

Propofol inhibits proliferation, migration, and invasion but promotes apoptosis by regulation of Sox4 in endometrial cancer cells

Propofol is an intravenous sedative hypnotic agent of which the growth-inhibitory effect has been reported on various cancers. However, the roles of propofol in endometrial cancer (EC) remain unclear. This study aimed to explore the effects of propofol on EC in vitro and in vivo. Different concentrations of propofol were used to treat Ishikawa cells. Colony number, cell viability, cell cycle, apoptosis, migration, and invasion were analyzed by colony formation, MTT, flow cytometry, and Transwell assays. In addition, the pcDNA3.1-Sox4 and Sox4 siRNA plasmids were transfected into Ishikawa cells to explore the relationship between propofol and Sox4 in EC cell proliferation. Tumor weight in vivo was measured by xenograft tumor model assay. Protein levels of cell cycle-related factors, apoptosis-related factors, matrix metalloproteinases 9 (MMP9), matrix metalloproteinases 2 (MMP2) and Wnt/β-catenin pathway were examined by western blot. Results showed that propofol significantly decreased colony numbers, inhibited cell viability, migration, and invasion but promoted apoptosis in a dose-dependent manner in Ishikawa cells. Moreover, propofol reduced the expression of Sox4 in a dose-dependent manner. Additionally, propofol significantly suppressed the proportions of Ki67⁺ cells, but Sox4 overexpression reversed the results. Furthermore, in vivo assay results showed that propofol inhibited tumor growth; however, the inhibitory effect was abolished by Sox4 overexpression. Moreover, propofol inhibited Sox4 expression via inactivation of Wnt/β-catenin signal pathway. Our study demonstrated that propofol inhibited cell proliferation, migration, and invasion but promoted apoptosis by regulation of Sox4 in EC cells. These findings might indicate a novel treatment strategy for EC.

Differential role of intravenous anesthetics in colorectal cancer progression: implications for clinical application

Anesthetics are unavoidable to colorectal cancer (CRC) patients who underwent surgical treatment. Thus, the molecular mechanisms underlying the role of the intravenous anesthetics in CRC metastasis are still unclear. In this study, the effects of intravenous anesthetics, such as propofol, etomidate and dexmedetomidine, on cell migration were determined. The migration of CRC cells was inhibited by propofol in vitro, but not in vivo. Etomidate, however, promoted the migration of CRC cells both in vitro and in vivo. Epithelial-mesenchymal transition (EMT) mediated the promotive effect of propofol and etomidate on the migration of CRC cells through PI3K/AKT signaling pathway. Dexmedetomidine alone or in combination with propofol or etomidate had minor effect on the migration of CRC cells. These findings indicate that propofol inhibites CRC cell migration in vitro. Etomidate playes a role for prompting CRC metastasis progression by activating (PI3K)/AKT signaling and inducing EMT. It provides an important hint for the clinical application of these anesthetics.

Propofol Reversed Hypoxia-Induced Docetaxel Resistance in Prostate Cancer Cells by Preventing Epithelial-Mesenchymal Transition by Inhibiting Hypoxia-Inducible Factor 1α

Prostate cancer is the second most frequently diagnosed cancer worldwide. Hypoxia-induced epithelial–mesenchymal transition (EMT), driven by hypoxia-inducible factor 1α (HIF-1α), is involved in cancer progression and metastasis. The present study was designed to explore the role of propofol in hypoxia-induced resistance of prostate cancer cells to docetaxel. We used the Cell Counting Kit-8 and 5-ethynyl-2′-deoxyuridine incorporation assay to measure cell viability and cell proliferation, respectively, in prostate cancer cell lines. Then, we detected HIF-1α, E-cadherin, and vimentin expression using western blotting. Propofol reversed the hypoxia-induced docetaxel resistance in the prostate cancer cell lines. Propofol not only decreased hypoxia-induced HIF-1α expression, but also reversed hypoxia-induced EMT by suppressing HIF-1α. Furthermore, small interfering RNA–mediated silencing of HIF-1α reversed the hypoxia-induced docetaxel resistance, although there was little change in docetaxel sensitivity between the hypoxia group and propofol group. The induction of hypoxia did not affect E-cadherin and vimentin expression, and under the siRNA knockdown conditions, the effects of propofol were obviated. These data support a role for propofol in regulating EMT in prostate cancer cells. Taken together, our findings demonstrate that propofol plays an important role in hypoxia-induced docetaxel sensitivity and EMT in prostate cancer cells and that it is a potential drug for overcoming drug resistance in prostate cancer cells via HIF-1α suppression.

Evaluation of cytotoxicity of propofol and its related mechanism in glioblastoma cells and astrocytes

Propofol (2,6-diisopropylphenol), one of the extensively and commonly used anesthetic agents, has been shown to affect the biological behavior of various models. Previous researches have shown that propofol-induced cytotoxicity might cause anticancer effect in different cells. However, the mechanisms underlying the effect of propofol on cytotoxicity is still elusive in human glioblastoma cells. The aims of this study were to evaluate effects of propofol on cytotoxicity, cell cycle distribution and ROS production, and establish the relationship between oxidative stress and cytotoxicity in GBM 8401 human glioblastoma cells and DI TNC1 rat astrocytes. Propofol (20-30 μM) concentration-dependently induced cytotoxicity, cell cycle arrest, and increased ROS production in GBM 8401 cells but not in DI TNC1 cells. In GBM 8401 cells, propofol induced G2/M phase cell arrest, which affected the CDK1, cyclin B1, p53, and p21 protein expression levels. Furthermore, propofol induced oxygen stresses by increasing O2- and H₂ O₂ levels but treatment with the antioxidant N-acetylcysteine (NAC) partially reversed propofol-regulated antioxidative enzyme levels (superoxide dismutase, catalase, and glutathione peroxidase). Most significantly, propofol induced apoptotic effects by decreasing Bcl-2 but increasing Bax, cleaved caspase-9/caspase-3 levels, which were partially reversed by NAC. Moreover, the pancaspase inhibitor Z-VAD-FMK also partially prevented propofol-induced apoptosis. Together, in GBM 8401 cells but not in DI TNC1 cells, propofol activated ROS-associated apoptosis that involved cell cycle arrest and caspase activation. These findings indicate that propofol not only can be an anesthetic agent which reduces pain but also has the potential to be used for the treatment of human glioblastoma.

Propofol enhances BCR-ABL TKIs' inhibitory effects in chronic myeloid leukemia through Akt/mTOR suppression

Background

The anti-cancer activities of intravenous anesthetic drug propofol have been demonstrated in various types of cancers but not in chronic myeloid leukemia (CML).

Methods

We systematically examined the effect of propofol and its combination with BCR-ABL tyrosine kinase inhibitors (TKIs) in CML cell lines, patient progenitor cells and mouse xenograft model. We analyzed propofol’s underlying mechanism focusing on survival pathway in CML cells.

Results

We show that propofol alone is active in inhibiting proliferation and inducing apoptosis in KBM-7, KU812 and K562 cells, and acts synergistically with imatinib or dasatinib, in in vitro cell culture system and in vivo xenograft model. In addition, propofol is more effective in inducing apoptosis and inhibiting colony formation in CML CD34 progenitor cells than normal bone marrow (NBM) counterparts. Combination of propofol and dasatinib significantly eliminates CML CD34 without affecting NBM CD34 cells. We further demonstrate that propofol suppresses phosphorylation of Akt, mTOR, S6 and 4EBP1 in K562. Overexpression of constitutively active Akt significantly reverses the inhibitory effects of propofol in K562, confirm that propofol acts on CML cells via inhibition of Akt/mTOR. Interestingly, the levels of p-Akt, p-mTOR and p-S6 are lower in cells treated with combination of propofol and imatinib than cells treated with propofol or imatinib alone, suggesting that propofol augments BCR-ABL TKI’s inhibitory effect via suppressing Akt/mTOR pathway.

Conclusion

Our work shows that propofol can be repurposed to for CML treatment. Our findings highlight the therapeutic value of Akt/mTOR in overcoming resistance to BCR-ABL TKI treatment in CML.

Electronic supplementary material

The online version of this article (10.1186/s12871-017-0423-2) contains supplementary material, which is available to authorized users.

The Effects of Anesthetics on Recurrence and Metastasis of Cancer, and Clinical Implications

Surgical resection of the primary tumor may enhance the metastasis and recurrence of cancer. The reaction of patients to surgery includes changes of the immune system, the inflammatory system and the neuroendocrine system. In the perioperative period, anesthetics are used both for anesthesia and analgesia. There are several studies showing that the progression of cancer can be influenced by many kinds of anesthetics, although most of these studies are preclinical and thus have not yet influenced clinical recommendations. This review summarizes recent studies regarding the effects of anesthetics on metastasis and recurrence of cancer.

Effect of propofol on androgen receptor activity in prostate cancer cells

Androgen receptor is a nuclear receptor and transcription factor activated by androgenic hormones. Androgen receptor activity plays a pivotal role in the development and progression of prostate cancer. Although accumulating evidence suggests that general anesthetics, including opioids, affect cancer cell growth and impact patient prognosis, the effect of those drugs on androgen receptor in prostate cancer is not clear. The purpose of this study was to investigate the effect of the general anesthetic propofol on androgen receptor activity in prostate cancer cells. An androgen-dependent human prostate cancer cell line (LNCaP) was stimulated with dihydrotestosterone (DHT) and exposed to propofol. The induction of androgen receptor target genes was investigated using real-time reverse transcription polymerase chain reaction, and androgen receptor protein levels and localization patterns were analyzed using immunoblotting and immunofluorescence assays. The effect of propofol on the proliferation of LNCaP cells was analyzed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Propofol significantly inhibited DHT-induced expression of androgen receptor target genes in a dose- and time-dependent manner, and immunoblotting and immunofluorescence assays indicated that propofol suppressed nuclear levels of androgen receptor proteins. Exposure to propofol for 24h suppressed the proliferation of LNCaP cells, whereas 4h of exposure did not exert significant effects. Together, our results indicate that propofol suppresses nuclear androgen receptor protein levels, and inhibits androgen receptor transcriptional activity and proliferation in LNCaP cells.

Propofol Suppresses Esophageal Squamous Cell Carcinoma Cell Migration and Invasion by Down-Regulation of Sex-Determining Region Y-box 4 (SOX4)

Background

This study was done to verify whether propofol could inhibit esophageal squamous cell carcinoma (ESCC) cell line EC9706 cell migration and invasion by targeting SOX4.

Material/Methods

Different concentrations of propofol were co-incubated with EC9706 cells. The pcDNA-SOX4 or SOX4 siRNA plasmid was transfected into cells before the treatment with propofol 5 μg/L. The migratory and invasion ability of EC9706 cells were tested by wound-healing assay and Transwell chambers. Western blotting was used to investigate the expressions of MMP-2, MMP-9, TIMP-1, TIMP-2, and SOX4. Gelatin zymography was employed to detect the activity of MMP2 and MMP-9.

Results

Compared with the control, the migration and invasion activity of EC9706 cells were decreased after incubation with different concentrations of propofol (P<0.01). The expression of MMP-2, MMP-9, and SOX4 was decreased and that of TIMP-1 was increased in the propofol-treated EC9706 cells (P<0.01). Down-regulation of SOX4 by SOX4-siRNA had the same effect as propofol on EC9706 cells, including suppressing cell migration and invasion, inhibiting the expression and activity of MMP-2/9, and increasing the expression TIMP-1. Over-expression of SOX4 could partly abrogated propofol-mediated inhibition of EC9706 cell migration and invasion.

Conclusions

Propofol inhibits EC9706 cell migration and invasion by down-regulation of SOX4.

Propofol inhibits lung cancer cell viability and induces cell apoptosis by upregulating microRNA-486 expression

Propofol is a frequently used intravenous anesthetic agent. Recent studies show that propofol exerts a number of non-anesthetic effects. The present study aimed to investigate the effects of propofol on lung cancer cell lines H1299 and H1792 and functional role of microRNA (miR)-486 in these effects. H1299 and/or H1792 cells were treated with or without propofol and transfected or not with miR-486 inhibitor, and then cell viability and apoptosis were analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and flow cytometry. The expression of miR-486 was determined by quantitative real-time polymerase chain reaction (qRT-PCR) with or without propofol treatment. Western blot was performed to analyze the protein expression of Forkhead box, class O (FOXO) 1 and 3, Bcl-2 interacting mediator of cell death (Bim), and pro- and activated caspases-3. Results showed that propofol significantly increased the miR-486 levels in both H1299 and H1792 cells compared to untreated cells in a dose-dependent manner (P<0.05 or P<0.01). Propofol statistically decreased cell viability but increased the percentages of apoptotic cells and protein expressions of FOXO1, FOXO3, Bim, and pro- and activated caspases-3; however, miR-486 inhibitor reversed the effects of propofol on cell viability, apoptosis, and protein expression (P<0.05 or P<0.01). In conclusion, propofol might be an ideal anesthetic for lung cancer surgery by effectively inhibiting lung cancer cell viability and inducing cell apoptosis. Modulation of miR-486 might contribute to the anti-tumor activity of propofol.

Propofol induces proliferation partially via downregulation of p53 protein and promotes migration via activation of the Nrf2 pathway in human breast cancer cell line MDA-MB-231

Antioxidants induce the proliferation of cancers by decreasing the expression of p53. Propofol, one of the most extensively used intravenous anesthetics, provides its antioxidative activity via activation of the nuclear factor E2-related factor-2 (Nrf2) pathway, but the mechanisms involved in the effects remain unknown. Thus, we aimed to investigate the function of p53 and Nrf2 in the human breast cancer cell line MDA-MB-231 following treatment with propofol. The cells were treated with propofol (2, 5 and 10 µg/ml) for 1, 4 and 12 h, and MTT assay was used to evaluate cell proliferation, and a wound healing assay was used to evaluate cell migration. Cell apoptosis, caspase-3 activity, and western blot analysis for p53 and Nrf2 protein were also assessed. Finally, PIK-75, a potent Nrf2 inhibitor, was used to confirm the effects of Nrf2 after treatment with propofol. Treatment of MDA-MB‑231 cells with propofol resulted in increased proliferation and migration in a dose- and time-dependent manner. After treatment with propofol for 12 h, the Nrf2 protein expression was increased, while the percentage of apoptotic cells, caspase-3 activity, and expression of p53 were significantly decreased. Additionally, treatment with the Nrf2 inhibitor increased the percentage of apoptotic cells, inhibited the migration almost completely, and decreased the degree of proliferation, while the expression of p53 was not affected. In conclusion, propofol increased the proliferation of human breast cancer MDA-MB‑231 cells, which was at least partially associated with the inhibition of the expression of p53, and induced cell migration, which was involved in the activation of the Nrf2 pathway.

The Crosstalk between Nrf2 and TGF-β1 in the Epithelial-Mesenchymal Transition of Pancreatic Duct Epithelial Cells

Nrf2 and TGF-β1 both affect tumorigenesis in a dual fashion, either by preventing carcinogen induced carcinogenesis and suppressing tumor growth, respectively, or by conferring cytoprotection and invasiveness to tumor cells during malignant transformation. Given the involvement of Nrf2 and TGF-β1 in the adaptation of epithelial cells to persistent inflammatory stress, e.g. of the pancreatic duct epithelium during chronic pancreatitis, a crosstalk between Nrf2 and TGF-β1 can be envisaged. By using premalignant human pancreatic duct cells (HPDE) and the pancreatic ductal adenocarcinoma cell line Colo357, we could show that Nrf2 and TGF-β1 independently but additively conferred an invasive phenotype to HPDE cells, whereas acting synergistically in Colo357 cells. This was accompanied by differential regulation of EMT markers like vimentin, Slug, L1CAM and E-cadherin. Nrf2 activation suppressed E-cadherin expression through an as yet unidentified ARE related site in the E-cadherin promoter, attenuated TGF-β1 induced Smad2/3-activity and enhanced JNK-signaling. In Colo357 cells, TGF-β1 itself was capable of inducing Nrf2 whereas in HPDE cells TGF-β1 per-se did not affect Nrf2 activity, but enhanced Nrf2 induction by tBHQ. In Colo357, but not in HPDE cells, the effects of TGF-β1 on invasion were sensitive to Nrf2 knock-down. In both cell lines, E-cadherin re-expression inhibited the proinvasive effect of Nrf2. Thus, the increased invasion of both cell lines relates to the Nrf2-dependent downregulation of E-cadherin expression. In line, immunohistochemistry analysis of human pancreatic intraepithelial neoplasias in pancreatic tissues from chronic pancreatitis patients revealed strong Nrf2 activity already in premalignant epithelial duct cells, accompanied by partial loss of E-cadherin expression. Our findings indicate that Nrf2 and TGF-β1 both contribute to malignant transformation through distinct EMT related mechanisms accounting for an invasive phenotype. Provided a crosstalk between both pathways, Nrf2 and TGF-β1 mutually promote their tumorigenic potential, a condition manifesting already at an early stage during inflammation induced carcinogenesis of the pancreas.

Nrf2 is a potential prognostic marker and promotes proliferation and invasion in human hepatocellular carcinoma

Background

Nuclear factor E2-related factor 2 (Nrf2 or NFE2L2) is abundantly expressed in cancer cells and relates to proliferation, invasion, and chemoresistance. Our early observations also found that expression of Nrf2 was up-regulated in kinds of cancer including human hepatocellular carcinoma (HCC) cells. But there are limited reports about the expression, significance, function of Nrf2 in HCC.

Methods

First, Nrf2 expression was analyzed in HCC cell lines and tumor samples. Then, the relationship of Nrf2 with clinicopathological factors and survival were analyzed. Further, the effect of Nrf2 on cell proliferation, apoptosis, and metastasis was examined in vitro by modulating expression of Nrf2 through specific shRNA or expression plasmid. Last, the potential mechanisms were also investigated.

Results

Nrf2 was up-regulated in HCC, and expression of Nrf2 was correlated with tumor differentiation, metastasis, and tumor size. Univariate and multivariate analyses indicated that high Nrf2 expression might be a poor prognostic factor. Further studies demonstrated that inhibition of Nrf2 expression inhibited proliferation by inducing apoptosis and repressed invasion, and up-regulation of Nrf2 expression resulted in opposite phenotypes. Moreover, there are positive correlation between Nrf2 expression and that of Bcl-xL and MMP-9.

Conclusion

Nrf2 is a potential prognostic marker and promotes proliferation and invasion in human hepatocellular carcinoma partly through regulating expression of Bcl-xL and MMP-9.

Mini profile of potential anticancer properties of propofol

BACKGROUND

Propofol (2, 6-diisopropylphenol) is an intravenous sedative-hypnotic agent administered to induce and maintain anesthesia. It has been recently revealed that propofol has anticancer properties including direct and indirect suppression of the viability and proliferation of cancer cells by promoting apoptosis in some cancer cell lines.

METHODOLOGY/PRINCIPAL FINDINGS

This study aimed to establish a profile to quantitatively and functionally evaluate the anticancer properties of propofol in three cancer cell lines: non-small cell lung carcinoma cell line A549, human colon carcinoma cell line LoVo, and human breast cancer cell line SK-BR-3. We demonstrated that the expression level of caspase-3, an apoptosis biomarker, significantly increased in a dose-dependent manner after 24-h stimulation with 100 µM propofol in A549 cells, and slightly increased in LoVo cells. However, there was no change in caspase-3 expression in SK-BR-3 cells. High caspase-3 expression in A549 cells may be modulated by the ERK1/2 pathway because phosphorylated ERK1/2 dramatically reduced after propofol treatment. BAX, a major protein that promotes apoptosis in the regulation phase, was highly expressed in A549 cells after treatment with 25 µM propofol. Apoptosis induced by propofol may be associated with cancer cells carrying Kras mutations.

CONCLUSIONS/SIGNIFICANCE

Our results suggest that the anti-cancer effects of propofol, which are consistent with those of previous studies, are likely associated with the Kras mutation status. Only Kras mutation in Codon 12 instead of other Kras status has been demonstrated to play an important role in sensitizing the propofol-induced apoptosis in cancer cell lines from our study. These findings may enable us a detailed investigation of propofol/Kras-mediated cancer cell apoptosis in the future.

[Interaction of anesthetics and analgesics with tumor cells]

The results of preclinical and clinical studies indicate that the perioperative period is a vulnerable period for cancer progression and metastasis. The risk of cancer cell dissemination is enhanced by the combination of surgical manipulation and perioperative immunosuppression. Whether the oncological outcome of cancer patients can be influenced by the choice of anesthetic techniques is still a matter of debate. This review summarizes the molecular characteristics of cancer and interaction of anesthetic and analgesic drugs with cancer cells.

Quantitative analysis of NRF2 pathway reveals key elements of the regulatory circuits underlying antioxidant response and proliferation of ovarian cancer cells

Cells are constantly exposed to Reactive Oxygen Species (ROS) produced both endogenously to meet physiological requirements and from exogenous sources. While endogenous ROS are considered as important signalling molecules, high uncontrollable ROS are detrimental. It is unclear how cells can achieve a balance between maintaining physiological redox homeostasis and robustly activate the antioxidant system to remove exogenous ROS. We have utilised a Systems Biology approach to understand how this robust adaptive system fulfils homeostatic requirements of maintaining steady-state ROS and growth rate, while undergoing rapid readjustment under challenged conditions. Using a panel of human ovarian and normal cell lines, we experimentally quantified and established interrelationships between key elements of ROS homeostasis. The basal levels of NRF2 and KEAP1 were cell line specific and maintained in tight correlation with their growth rates and ROS. Furthermore, perturbation of this balance triggered cell specific kinetics of NRF2 nuclear-cytoplasmic relocalisation and sequestration of exogenous ROS. Our experimental data were employed to parameterise a mathematical model of the NRF2 pathway that elucidated key response mechanisms of redox regulation and showed that the dynamics of NRF2-H2O2 regulation defines a relationship between half-life, total and nuclear NRF2 level and endogenous H2O2 that is cell line specific.

Cytoprotection "gone astray": Nrf2 and its role in cancer

Nrf2 has gained great attention with respect to its pivotal role in cell and tissue protection. Primarily defending cells against metabolic, xenobiotic and oxidative stress, Nrf2 is essential for maintaining tissue integrity. Owing to these functions, Nrf2 is regarded as a promising drug target in the chemoprevention of diseases, including cancer. However, much evidence has accumulated that the beneficial role of Nrf2 in cancer prevention essentially depends on the tight control of its activity. In fact, the deregulation of Nrf2 is a critical determinant in oncogenesis and found in many types of cancer. Therefore, amplified Nrf2 activity has profound effects on the phenotype of tumor cells, including radio/chemoresistance, apoptosis protection, invasiveness, antisenescence, autophagy deficiency, and angiogenicity. The deregulation of Nrf2 can result from various epigenetic and genetic alterations directly affecting Nrf2 control or from the complex interplay of Nrf2 with numerous oncogenic signaling pathways. Additionally, alterations of the cellular environment, eg, during inflammation, contribute to Nrf2 deregulation and its persistent activation. Therefore, the status of Nrf2 as anti- or protumorigenic is defined by many different modalities. A better understanding of these modalities is essential for the safe use of Nrf2 as an activation target for chemoprevention on the one hand and as an inhibition target in cancer therapy on the other. The present review mainly addresses the conditions that promote the oncogenic function of Nrf2 and the resulting consequences providing the rationale for using Nrf2 as a target structure in cancer therapy.

Inflammatory pathways in the early steps of colorectal cancer development

Colorectal cancer is a major cause of cancer-related death in many countries. Colorectal carcinogenesis is a stepwise process which, from normal mucosa leads to malignancy. Many factors have been shown to influence this process, however, at present, several points remain obscure. In recent years some hypotheses have been considered on the mechanisms involved in cancer development, expecially in its early stages. Tissue injury resulting from infectious, mechanical, or chemical agents may elicit a chronic immune response resulting in cellular proliferation and regeneration. Chronic inflammation of the large bowel (as in inflammatory bowel diseases), has been associated with the subsequent development of colorectal cancer. In this review we examine the inflammatory pathways involved in the early steps of carcinogenesis, with particular emphasis on colorectal. Firstly, we describe cells and proteins recently suggested as central in the mechanism leading to tumor development. Macrophages and neutrophils are among the cells mostly involved in these processes and proteins, as cyclooxygenases and resolvins, are crucial in these inflammatory pathways. Indeed, the activation of these pathways establishes an oxidative and anaerobic microenvironment with DNA damage to epithelial cells, and shifting from an aerobic to an anaerobic metabolism. Many cellular mechanisms, such as proliferation, apoptosis, and autophagy are altered causing failure to control normal mucosa repair and renewal.

Targeting the NF-E2-related factor 2 pathway: a novel strategy for glioblastoma (review)

Glioblastoma is the most common and malignant subtype among all brain tumors. Nuclear factor erythroid 2-related factor 2 (Nrf2) is an essential component of cellular defense against a variety of endogenous and exogenous stresses. A marked increase in research over the past few decades focusing on Nrf2 and its role in regulating glioblastoma has revealed the potential value of Nrf2 in the treatment of glioblastoma. In the present review, we discuss a novel framework of Nrf2 in the regulation of glioblastoma and the mechanisms regarding the downregulation of Nrf2 in treating glioblastoma. The candidate mechanisms include direct and indirect means. Direct mechanisms target tumor molecular pathways in order to overcome resistance to chemotherapy and radiotherapy, to inhibit proliferation, to block invasion and migration, to induce apoptosis, to promote differentiation, to enhance autophagy and to target glioblastoma stem cells. Indirect mechanisms target the reaction between glioblastoma cells and the surrounding microenvironment. Overall, the value of the Nrf2 pathway in glioblastoma provides a promising opportunity for new approaches by which to treat glioblastoma.

Oncogenic functions of the transcription factor Nrf2

Nuclear factor E2-related factor 2 (Nrf2) is a transcription factor that controls the expression of a large pool of antioxidant and cytoprotective genes regulating the cellular response to oxidative and electrophilic stress. Nrf2 is negatively regulated by Kelch-like ECH-associated protein 1 (Keap1) and, upon stimulation by an oxidative or electrophilic insult, is rapidly activated by protein stabilization. Owing to its cytoprotective functions, Nrf2 has been traditionally studied in the field of chemoprevention; however, there is accumulated evidence that Keap1/Nrf2 mutations or unbalanced regulation that leads to overexpression or hyperactivation of Nrf2 may participate in tumorigenesis and be involved in chemoresistance of a wide number of solid cancers and leukemias. In addition to protecting cells from reactive oxygen species, Nrf2 seems to play a direct role in cell growth control and is related to apoptosis-regulating pathways. Moreover, Nrf2 activity is connected with oncogenic kinase pathways, structural proteins, hormonal regulation, other transcription factors, and epigenetic enzymes involved in the pathogenesis of various types of tumors. The aim of this review is to compile and summarize existing knowledge of the oncogenic functions of Nrf2 to provide a solid basis for its potential use as a molecular marker and pharmacological target in cancer.

Lactulose ameliorates cerebral ischemia-reperfusion injury in rats by inducing hydrogen by activating Nrf2 expression

Molecular hydrogen has been proven effective in ameliorating cerebral ischemia/reperfusion (I/R) injury by selectively neutralizing reactive oxygen species. Lactulose can produce a considerable amount of hydrogen through fermentation by the bacteria in the gastrointestinal tract. To determine the neuroprotective effects of lactulose against cerebral I/R injury in rats and explore the probable mechanisms, we carried out this study. The stroke model was produced in Sprague-Dawley rats through middle cerebral artery occlusion. Intragastric administration of lactulose substantially increased breath hydrogen concentration. Behavioral and histopathological verifications matched biochemical findings. Behaviorally, rats in the lactulose administration group won higher neurological scores and showed shorter escape latency time in the Morris test. Morphologically, 2,3,5-triphenyltetrazolium chloride showed smaller infarction volume; Nissl staining manifested relatively clear and intact neurons and TUNEL staining showed fewer apoptotic neurons. Biochemically, lactulose decreased brain malondialdehyde content, caspase-3 activity, and 3-nitrotyrosine and 8-hydroxy-2-deoxyguanosine concentration and increased superoxide dismutase activity. The effects of lactulose were superior to those of edaravone. Lactulose orally administered activated the expression of NF-E2-related factor 2 (Nrf2) in the brain as verified by RT-PCR and Western blot. The antibiotics suppressed the neuroprotective effects of lactulose by reducing hydrogen production. Our study for the first time demonstrates a novel therapeutic effect of lactulose on cerebral ischemia/reperfusion injury and the probable underlying mechanisms. Lactulose intragastrically administered possessed neuroprotective effects on cerebral I/R injury in rats, which could be attributed to hydrogen production by the fermentation of lactulose through intestinal bacteria and Nrf2 activation.

Propofol induces apoptosis and increases gemcitabine sensitivity in pancreatic cancer cells in vitro by inhibition of nuclear factor-κB activity

AIM: To investigate the effect of propofol on human pancreatic cells and the molecular mechanism of propofol action.

METHODS: We used the human pancreatic cancer cell line MIAPaCa-2 for in vitro studies measuring growth inhibition and degree of apoptotic cell death induced by propofol alone, gemcitabine alone, or propofol followed by gemcitabine. All experiments were conducted in triplicate and carried out on three or more separate occasions. Data were means of the three or more independent experiments ± SE. Statistically significant differences were determined by two-tailed unpaired Student’s t test and defined as P < 0.05.

RESULTS: Pretreatment of cells with propofol for 24 h followed by gemcitabine resulted in 24%-75% growth inhibition compared with 6%-18% when gemcitabine was used alone. Overall growth inhibition was directly correlated with apoptotic cell death. We also showed that propofol potentiated gemcitabine-induced killing by downregulation of nuclear factor-κB (NF-κB). In contrast, NF-κB was upregulated when pancreatic cancer cells were exposed to gemcitabine alone, suggesting a potential mechanism of acquired chemoresistance.

CONCLUSION: Inactivation of the NF-κB signaling pathway by propofol might abrogate gemcitabine-induced activation of NF-κB, resulting in chemosensitization of pancreatic tumors to gemcitabine.

WITHDRAWN: Propofol reduces MMPs expression by inhibiting PI3K/AKT activity in human HepG2 cells

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