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#3由 sufang 在 二, 06/09/2015 – 09:02 發表。
2015/06/04_LOX
Scientists Identify Key to Preventing Secondary Cancers
Scientists Identify Key to Preventing Secondary Cancers
Thu, 05/28/2015 – 9:36am
University of Sheffield
Leading scientists from the University of Sheffield and University of Copenhagen have identified a possible key to preventing secondary cancers in breast cancer patients, after discovering an enzyme which enhances the spread of the disease.
Secondary (metastatic) breast cancer is the main cause of the 12,000 deaths which occur from breast cancer in the UK every year. The most common site for the disease to spread is the bone – occurring in around 85 per cent of secondary breast cancer patients. The new research found that the enzyme LysYl Oxidase (LOX) released from the primary tumor causes holes in bone and prepares the bone for the future arrival of cancer cells. The findings suggest that identifying LOX in oestrogen receptor negative (ER negative) breast cancer patients early, could allow doctors to block the enzyme’s activity, preventing bone damage and the spread of tumor cells to the bone (metastasis), halting the progression of the disease. The researchers also showed that treatment with bisphosphonate, an existing class of drug which prevents the loss of bone mass and is already used to treat diseases such as osteoporosis, was able to prevent the changes in the bone and the spread of the disease in mice. The pioneering research, co-led by Dr Alison Gartland at the University of Sheffield’s Department of Human Metabolism, could lead to a better prognosis for cancer patients in the longer term. Dr Gartland said: “This is important progress in the fight against breast cancer metastasis and these findings could lead to new treatments to stop secondary breast tumors growing in the bone, increasing the chances of survival for thousands of patients. “We are really excited about our results that show breast cancer tumors send out signals to destroy the bone before cancer cells get there in order to prepare the bone for the cancer cells’ arrival. “The next step is to find out exactly how the tumor secreted LOX interacts with bone cells to be able to develop new drugs to stop the formation of the bone lesions and cancer metastasis. This could also have implications for how we treat other bone diseases too.” Study co-leader Dr Janine Erler, formerly Team Leader in Cancer Biology at The Institute of Cancer Research, London, who now is Associate Professor at the Biotech Research & Innovation Centre (BRIC) at the University of Copenhagen, said: “Once cancer spreads to the bone it is very difficult to treat. “Our research has shed light on the way breast cancer cells prime the bone so it is ready for their arrival. If we were able to block this process and translate our work to the clinic, we could stop breast cancer in its tracks thereby extending patients’ lives.” The research, funded by Breast Cancer Campaign, Cancer Research UK, Novo nordisk foundation, Danish cancer society, lundbeck foundation, and both universities, is published today (27 May 2015) in the journal Nature. Katherine Woods, Senior Research Communications Manager at Breast Cancer Campaign and Breakthrough Breast Cancer, said: “By unveiling the role that the protein LOX is playing, these results open up a whole new avenue for research and treatments that could stop breast cancer spreading to the bone. The research also adds weight to the growing body of evidence supporting the role of bisphosphonates in stopping secondary breast cancer in its tracks. “The reality of living with secondary breast cancer in the bone is a stark one, which leaves many women with bone pain and fractures that need extensive surgery just when they need to be making the most of the time they have left with friends and family.” She added: “Secondary breast cancer kills 1,000 women each and every month in the UK alone and yet we still don’t know enough about how and why breast cancer spreads to stop it. “Our newly-formed charity is determined that by 2050, no one will lose their life to breast cancer and we’ll do this by ramping up our research efforts, in this area in particular, doing everything possible to achieve that goal.” Source: University of Sheffield _______
#4由 sufang 在 一, 05/25/2015 – 09:00 發表。 2012/05 pdf 4366 Mitochondrial Regulation of Cell Cycle and Prol ANTIOXIDANTS & REDOX SIGNALING pdf 4366 2012-May Mitochondrial Regulation of Cell Cycle and Proliferation Valeria Gabriela Antico Arciuch,1,* Mar ́ıa Eugenia Elguero,1 Juan Jose ́ Poderoso,1–3 and Mar ́ıa Cecilia Carreras1,3,4
I. Introduction 1151 II. Introduction to Mitochondrial Biology 1151 A. The physiology of mitochondria and redox biology 1151 B. NO and mitochondrial redox metabolism 1152 C. H2O2 and antagonistic antioxidant enzymes 1153 D. The intermembrane space and the redox status 1154 III. Mitochondrial Metabolism and Cell Proliferation 1154 A. The Warburg effect: The mitochondrial control of proliferation 1154 B. Mitochondria and redox control in normal and tumor cells 1155 C. Stem cells, mitochondrial ROS metabolism, and differentiation 1156 D. ROS and mitochondrial malignancy: The example of p53 1156 E. The glycolytic effects for mitochondrial oxidative rate 1157 F. Mitochondrial signaling in hypoxia 1157 G. Mechanistic target of rapamycin (serine/threonine kinase)/Akt pathways 1158 H. Hexokinase 1159 I. The regulation of glycolysis and proliferation by the ubiquitination system 1159 IV. ROS: From Proliferation to Cell Death 1160 V. Kinases, Mitochondria, and Cell Cycle 1162 A. The MAPK cascade 1162 B. Akt/protein kinase B 1163 C. Protein kinase C 1164 D. Protein kinase A 1165 VI. Mitochondrial Biogenesis 1165 A. Transcriptional control of mitochondrial biogenesis 1165 B. Mitochondrial biogenesis, NO, and ROS 1166 VII. Mitochondrial Dynamics 1167 A. Mitochondrial fusion 1167 B. Mitochondrial fusion machinery and apoptosis 1168 C. Mitochondrial fission 1169 D. Mitochondrial fission machinery and apoptosis 1169 E. Mitochondrial dynamics, NO, and ROS 1170 VIII. Mitochondrial Biogenesis, Mitochondrial Dynamics, and Cell Cycle 1170 IX. Concluding Remarks COX5A = COX = cytochrome oxidase, the terminal enzyme that transfer electrons to O2 NO = nitric oxide = a powerful modulator of oxygen utilization by reversible binding to COX NO = (1) reduces O2 utilization (2) increass ROS production NO, also known as EDRF (endothelium-derived relazing factor), is biosynthesized endogenously from L-argining, oxygen and NADPH by various NOS (nitric oxide synthetase) NOS1, NOS2 (= iNOS), NOS3 (=eNOS), NOS1AP ________ #5由 sufang 在 一, 05/25/2015 – 08:50 發表。
2012/08 pdf 3495 Association of Betel Nut with Carcinogenesis
PLoS One 2102/08 review (pdf 3495)
Association of Betel Nut with Carcinogenesis: Revisit with a Clinical Perspective
(a) In vivo studies. Several animal studies have confirmed that BN products and derivatives, such as arecoline and BN derived nitrosamines, also referred to as betel specific nitrosamines (BSNA), have the ability to induce neoplastic changes in experimental animals (Figure 3). Alkaloids of BN are suspected to be its main carcinogenic constituent [2]–[6], [9], [24], [62]. Early studies found that the application of arecaidine to the oral mucosa of experimental animals failed to have any carcinogenic effects unless it was supplemented with a known promoter, such as croton oil [24]. However, arecoline administered by gavage produced lung adenocarcinoma, stomach SCC and liver haemangioma in male mice [9]. Cheek pouch application of arecoline following application of slaked lime produced an esophageal papilloma in female hamsters, while local application of arecaidine to the cheek pouch did not produce tumor in male hamsters [9]. To explain the variable observation, it is proposed that the alkaloids first required metabolic activation via nitrosation to develop its carcinogenicity [63]. In vitro data suggest that arecoline is metabolized by carboxylesterase in mouse liver and kidney. Male Swiss albino mice fed BN powder or arecoline showed enhanced levels of the hepatic cytochrome P450 and b5 and decreased levels of hepatic GSH [9]. In fact, human cytochrome P450 was found to be involved in the mutagenic activation of BSNA such as 3-(N-nitrosomethylamino)propionitrile (NMPN), 3-(N-nitrosomethylamino)propionaldehyde (NMPA) and N-nitrosoguvacoline (NG) using genetically engineered Salmonella typhimurium YG7108 expressing each form of human P450 together with NADPH-P450 reductase [64]. Exposure of Swiss albino mice to arecoline was found to lower poly-ADP-ribosylation (PAR) of most cellular and histone proteins and induce relaxation of chromatin, thereby allowing the N-nitrosamines of arecoline easy access to genomic DNA for interaction, while the absence of PAR mediated repair may favour the accumulation of DNA damage [65]. Arecoline induced micronuclei (MN), chromosomal aberrations (CA) and sister chromatid exchange (SCE) in bone marrow cells (BMC) of Swiss albino mice [66], [67]. The arecoline induced DNA damage was found to be influenced by endogenous GSH levels with the frequency of CA and SCE increasing when arecoline was given to mice treated with buthioninesulfoximine (BSO), a GSH synthesis inhibitor (Figure 3). The frequency of SCE was found to be elevated in mouse BMC when mice were exposed to the aqueous extract of betel nut (AEBN) and its tannin [67]. AEBN also induced micronucleated cells (MNC) in BMC of Swiss albino mice [5]. Hamsters fed with powdered diet containing BN or BQ showed significant decrease in the survival rate, body weight, and hyperkeratosis and acanthosis of cheek pouch indicating that BN and BQ components may induce alterations in proliferation and differentiation of oral epithelial cells [68]. When the buccal mucosa of mice was treated regularly with a topical application of water based BNE, the oral epithelium showed progressive changes in epithelial thickness leading to atrophy, increased cellularity of fibroblasts, fibrosis of connective tissue, focal infiltration of inflammatory cells and muscle atrophy [69]. Frequency of all the three cytogenetic endpoints, viz. CA, SCE and MNC, were found to be elevated significantly in a dose dependent manner in cultures exposed to aqueous extracts of paan masala without metabolic activation [70]. The carcinogenic and tumor promoting potentials of an ethanolic paan masala extract (EPME) were determined using the hairless skin of S/RVCri-ba or Bare mice and the forestomach and esophagus of ICRC mice as the target tissues. EPME promoted skin papilloma formation and enhanced the rate of conversion of papilloma to carcinoma. Induction of mild epidermal hyperplasia, dermal edema, increase in epidermal mitotic activity and the rate of epidermal and dermal DNA syntheses by EPME correlated well with its skin tumor promoting potential. In ICRC mice, EPME was inactive as a complete carcinogen, but effectively promoted the development of forestomach and esophageal papilloma and carcinoma in a concentration dependent manner indicating that habitual paan masala use may exert carcinogenic and co-carcinogenic influences [71]. Exposure of male and female mice to paan masala revealed a significant dose dependent increase in lung adenocarcinoma but not in liver and stomach [72]. (b) In vitro studies. BNE was found to decrease cell survival, vital dye accumulation and membrane integrity of cultured human buccal epithelial cells in a dose dependent manner. BNE also caused formation of both DNA single strand breaks and DNA protein cross links [63], [73], [74]. Different BNE, such as aqueous extract of betel nut (AEBN), acetic acid extract of betel nut (AAEBN), HCl extract of betel nut (HEBN) and ethanol extract of betel nut (EEBN) as well as arecoline showed different extents of cytostatic and cytotoxic effects, and induced variable levels of dose dependent unscheduled DNA synthesis (UDS) in Hep2 cells in vitro. In manifestation of these effects arecoline, HEBN and EEBN were most potent [73], [75]. Cultured normal human oral keratinocytes (NHOK) exposed to ripe BNE also showed significant decrease in population doubling, increase in senescence, cell cycle arrest at G1/S phase and decrease in cell proliferation [76]. It has been reported that BQ may accelerate tumor migration by stimulating MMP-8 expression through MEK pathway in at least some carcinomas of the upper aerodigestive tract. Furthermore, arecoline may be one of the positive MMP-8 regulators among BQ ingredients [77]. Investigation of prostaglandin endoperoxide synthase (PHS) action on the growth of OC in response to BNE exposure of two human oral carcinoma cell lines OEC-M1, and KB, and one normal fibroblast cell line, NF, revealed that BNE significantly inhibited the cell growth of OEC-M1, KB and NF. PHS activity in OEC-M1 and NF was significantly increased by low BNE concentrations but significantly reduced at higher concentrations. The PHS activity in KB, on the other hand, was significantly inhibited by BNE and this effect was intensified as concentration increased [78]. Treatment of human oral mucosal fibroblasts (OMF) with BNE or arecoline induced about 3-fold increase in mRNA levels of the proto-oncogene c-jun independent of GSH depletion [79]. The BNE and inflorescence of Piper betle (IPB) also induced DNA strand breaks. In addition, BNE, IPB, the BN polyphenol, catechin as well as arecoline decreased cell survival and proliferation. In contrast, another component of BQ, the aqueous extract of lime, was found to increase cell proliferation [80]. AEBN was found to reduce endogenous glutathione (GSH) level, induce CA and delay cell kinetics in mouse BMC with the induction of SCE probably involving TP53 dependent changes in cell proliferation [81]. Ethyl acetate and n-butanol extracts of BN as well as betel leaf are reported to induce CA in human lymphocytes and Chinese hamster ovary (CHO) cells [4]. All components of BQ have been shown to individually enhance chromatid breaks and exchanges in the range of 12–37% in human cells in vitro. AEBN also induced DNA strand breaks and enhanced cell proliferation in mouse kidney T1 cells in vitro [73]. BNE exposure to CHO-K1 cells caused increased MN frequency, G2/M arrest, cytokinesis failure and an accumulation of hyperploid/aneuploid cells. These events are associated with an increase in intracellular H2O2 level and actin filament disorganization [82]. BNE also elicited actin reorganization resulting in fibroblastoid morphological change, genesis of lamellipodia, loss of subcortical actin and stress fiber formation in cultivated NHOK cells [83]. Arecoline alone has been reported to inhibit cell attachment, cell spreading and cell migration in a dose dependent manner in cultured human gingival fibroblasts (HGF) [84]. In fact, GSH depletion and reduction of glutathione S-transferase (GST) activity have been demonstrated in cultured human oral keratinocytes and in fibroblasts treated with arecoline [9]. Arecoline was also reported to be cytotoxic to human buccal fibroblasts in a dose dependent manner wherein the cellular GST activity was downregulated in a dose dependent manner without increase in lipid peroxidation. Addition of extracellular nicotine acted synergistically on the arecoline induced cytotoxicity, indicating that arecoline may render human OMF more vulnerable to other reactive agents in cigarettes via GST reduction. These observations could explain why patients who practice the combined habit of BQ chewing and cigarette smoking are at greater risk of contracting OC [85]. Arecoline inhibited growth of human KB epithelial cells in dose- and time-dependent manners by causing cell cycle arrest in late S and G2/M phases due to induction of cyclin Bl, Wee 1, and phosphorylated cdc2 proteins and inhibition of p21 protein expression in KB cancer cells. In primary human gingival keratinocyte (HGK) cell line, arecoline effect appeared to be mediated differently. In this case, arecoline induced p21 but inhibited cdc2 and cyclin B1 proteins. This clearly suggests that differential regulation of S and/or G2/M cell cycle related proteins in the HGK and KB cells play crucial roles in different stages of BQ mediated carcinogenesis [86]. Arecoline could also induce γ-H2AX phosphorylation, a sensitive DNA damage marker, in KB, HEP-2, and 293 cells, suggesting that DNA damage was elicited by arecoline. Moreover, the expression of p53 regulated p21 (WAF1) and p53 activated DNA repair were repressed by arecoline [87]. Arecoline was cytotoxic to HGF cells due to depletion of intracellular thiols and inhibition of mitochondrial activity and induced cell cycle arrest in HGF cells at G2/M phase in a dose dependent manner [88]. Global gene expression profiling in HGF exposed to arecoline revealed that four genes related to maintenance of genome stability and DNA repair were repressed by arecoline [89]. They are FANCG, also known as XRCC9 (tumor suppressor capable of correcting CA), CHAF1 and CHAF2 (encoding chromatin assembly factor I or CAF1) and BRCA1 (breast cancer susceptibility gene implicated in DNA damage response and DNA repair). Among them, at least the BRCA1 response was dose dependent. COX-2 and PTGS2, which are involved in cancer initiation and progression, were over expressed in HGF cells. HSP4A1 and DNAAJA1, which belong to the HSP70 family of stress-induced proteins and GDF15/MIC-1, were also upregulated by arecoline in dose dependent manner [89]. Chen et al. established two oral cancer sublines chronically treated with BNE and used methods such as microarray and immunohistochemistry to screen and validate the genes exhibiting altered expressions in BNE sublines or in cancer tissues. They found that a total of 35 genes were differentially expressed in both sublines. Several functional pathways were significantly altered. Six genes were confirmed over 2-fold of changes, including Ches1. Functional analyses showed that overexpression of Ches1 suppressed cell growth and arrested cells in the G2/M phase. They thus concluded that loss of Ches1 may be attributed to BNE-induced oral carcinogenesis [90]. Treatment of normal human oral fibroblasts with BNE was also reported to alter miRNA expression profile. BNE-induced overexpression of miR-23a was found to be correlated with an increase of γ-H2AX, a DNA damage marker. FANCG was confirmed to be a target of miR-23a by ectopic overexpression or knockdown of miR-23a. The correlation between miR-23a overexpression and BN-chewing habit was also reported in oral cancer patients. Thus, BNE-induced miR-23a was correlated with a reduced FANCG expression and DNA double strand break (DSB) repair, which might contribute to BNE-associated human malignancies [91]. Oral fibroblasts with chronic subtoxic BNE treatment were found to exhibit growth arrest and MMP-2 activation. The supernatant of these arrested oral fibroblasts activated the AKT signaling pathway in oral carcinoma cells. Moreover, subcutaneous co-injection of arrested oral fibroblasts into nude mice significantly enhanced the tumorigenicity of xenographic oral carcinoma cells. The investigators therefore concluded that BNE may impair oral fibroblasts and then modulate the progression of oral epithelial oncogenesis via their secreted molecules [92].Various studies have clearly established the mutagenecity of BN and its components. The major metabolite of arecoline, arecoline N-oxide, is reported to be moderately mutagenic to Salmonella typhimurium tester strains TA 100 and TA 98. But this mutagenicity was potently inhibited by glutathione, N-acetylcysteine, and cysteine [93]. Aqueous extracts of BQ without tobacco induced mutations in Salmonella typhimurium but not in Chinese hamster V79 cells. AEBN, on the other hand, induced mutations in Salmonella typhimurium and in Chinese hamster V79 cells besides inducing gene conversion in Saccharomyces cerevisiae as well as CA in CHO cells. BN tannin fraction induced gene conversion in Saccharomyces cerevisiae [4]. Ames test using Salmonella typhimurium strain TA 1535 revealed that arecoline, AEBN and HEBN were weak mutagens while AAEBN and EEBN were strong mutagens suggesting that the mutagenic potential of arecoline could be significantly enhanced by other constituents of BN [5], [94], [95]. Exposure to BNE was also found to induce mutation at the hypoxanthine phosphoribosyltransferase (HPRT) locus in human keratinocytes, which also increased frequency of appearance of MN, intracellular levels of reactive oxygen species (ROS) and 8-hydroxyguanosine in the cells suggesting that stress caused by long term BNE exposure enhanced oxidative stress and genetic damage in human keratinocytes [96]. (c) Human studies. Malignant transformation of human bronchial epithelial cells with the tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (IJC) Carcinogenesis. 1985 Feb;6(2):295-303. |