Browsing by Author "Laxmidhar Das"

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Anti-carcinogenic action of curcumin by activation of antioxidant defence system and inhibition of NF-κB signalling in lymphoma-bearing mice
(2012) Laxmidhar Das; Manjula Vinayak
NF-κB (nuclear factor κB) plays a significant role in inflammation, immunity, cell proliferation, apoptosis and malignancy. ROS (reactive oxygen species) are among the most important regulating factors of NF-κB. Intracellular ROS are mainly regulated by an endogenous antioxidant defence system. Any disruption of redox balance leads to oxidative stress, which causes a number of pathological conditions including inflammation and malignancy. Increased metabolic activity in cancerous cells leads to oxidative stress, which is further enhanced due to depletion of the endogenous antioxidant defence system. However, the activation and signalling of NF-κB are reported to be inhibited by overexpression and induced activity of antioxidant enzymes. Therefore the present study focuses on the correlation between the endogenous antioxidant defence system, ROS and NF-κB activation during lymphoma growth in mice. The study highlights the anti-carcinogenic role of curcumin by modulation of NF-κB activation and oxidative stress via the endogenous antioxidant defence system. Oxidative stress was monitored by lipid peroxidation, protein carbonylation and antioxidant enzyme activity. NF-κB-mediated signalling was tested by DNA-binding activity. The results reflect that intracellular production of H 2O 2 in oxidative tumour micro-environment regulates NF-κB activation. Curcumin inhibits oxidative state in the liver of lymphoma-bearing mice by enhancing the transcription and activities of antioxidant enzymes, which in turn modulate activation of NF-κB, leading to a decrease in lymphoma growth. Morphological changes as well as cell proliferation and cell survival assays confirmed reduced lymphoma growth. Thus curcumin contributes to cancer prevention by disrupting the vicious cycle of constant ROS production, responsible for a high oxidative micro-environment for tumour growth. ©The Authors Journal compilation ©2012 Biochemical Society.
Curcumin attenuates carcinogenesis by down regulating proinflammatory cytokine interleukin-1 (IL-1α and IL-1β) via modulation of AP-1 and NF-IL6 in lymphoma bearing mice
(Elsevier, 2014) Laxmidhar Das; Manjula Vinayak
Interleukin-1 (IL-1α and IL-1β) is a prototypic, potent, multifunctional proinflammatory cytokine affecting almost all cell types. Expression of IL-1 is up regulated in different tumor phenotypes and is implicated as an important factor in tumor progression via expression of metastatic, angiogenic genes and growth factors. Therefore, down regulation of expression of IL-1 may be able to inhibit cancer progression. Mechanism of transcriptional regulation of mouse IL-1α is not yet reported. AP-1 binding site at - 12 to - 6 on human IL-1α promotor is highly conserved in rat IL-1α gene and regulates its expression. Based on in silico analysis, regions - 12 to - 6 bp is found to be conserved in human and mouse IL-1α gene promotor and therefore selected to study activation of IL-1α. Further, the regions - 12 to - 6 bp in mouse IL-1α gene promotor corresponding to AP-1 binding element show 3′ → 5′ orientation, necessary for AP-1 binding. The present work is focused on long term effect of curcumin on expression of IL-1α and IL-1β in liver of lymphoma bearing mice. Transcriptional regulation of IL-1α and IL-1β was analyzed by AP-1 and NF-IL-6 respectively. Elevated expression and protein level of IL-1α and IL-1β were found in lymphoma bearing mice compared to normal, which were significantly down regulated by curcumin treatment. Similarly, curcumin treatment down regulated activation of IL-1α and IL-1β via AP-1 and NF-IL-6 respectively. The findings conclude that curcumin attenuates carcinogenesis by down regulating proinflammatory cytokine interleukin-1 (IL-1α and IL-1β) via modulation of AP-1 and NF-IL6 respectively in lymphoma bearing mice. © 2014 Elsevier B.V.
Curcumin modulates glycolytic metabolism and inflammatory cytokines via Nrf 2 in dalton’s lymphoma ascites cells in Vivo
(Bentham Science Publishers B.V., 2018) Laxmidhar Das; Manjula Vinayak
Background: Warburg effect is characterized by the upregulation of HIF-1 and c-Myc regulated LDH-A, even aerobically owing to hypoxic environment and alterations in oncogenes or tumor suppressor genes in cancer. Reduced antioxidant defence system in transformed cells favors higher ROS production, which plays a significant role in carcinogenesis and acts as an important regulator of NF-κB. In addition, various proinflammatory cytokines play active roles in maintenance and progression of cancer. Objective: In continuation with our previous studies illustrating the long-term effect of curcumin using a liver tissue, present study was aimed to elucidate the anti-cancer effect of curcumin due to its long-term effect in the regulation of glycolytic metabolism, NF-κB activation, expression of proinflammatory cytokines in Dalton’s lymphoma ascites cells in vivo. Method: Spectrophotometric assays, RT-PCR and EMSA were performed to address the problems. Results: Results revealed that curcumin-induced activation of antioxidant enzymes, Nrf2 and downstream signaling gene NQO1. Reduction of oxidative stress, down-regulation of NADPH: Oxidase, decline in ROS and H2O2 levels were also observed. Activation of NF-κB, expression of COX2, HIF-1α and cMyc, as well as expression and activity of LDH-A were significantly reduced by curcumin. Besides, expression of proinflammatory cytokines was significantly down-regulated via reducing binding of nuclear protein with AP-1, NF-IL6, ETS and NF-κB binding elements of IL-1α, IL-1β, TNF-α and IL-6 promoters, respectively. Conclusion: Curcumin downregulates glycolytic metabolism via modulation of stress-activated genes and reduces oxidative stress by enhancing antioxidant defence system, which inhibits activation of NF-κB signaling and expression of proinflammatory cytokines in Dalton’s lymphoma ascites cells in vivo. © 2018 Bentham Science Publishers.
Long term effect of curcumin in regulation of glycolytic pathway and angiogenesis via modulation of stress activated genes in prevention of cancer
(Public Library of Science, 2014) Laxmidhar Das; Manjula Vinayak
Oxidative stress, an important factor in modulation of glycolytic pathway and induction of stress activated genes, is further augmented due to reduced antioxidant defense system, which promotes cancer progression via inducing angiogenesis. Curcumin, a naturally occurring chemopreventive phytochemical, is reported to inhibit carcinogenesis in various experimental animal models. However, the underlying mechanism involved in anticarcinogenic action of curcumin due to its long term effect is still to be reported because of its rapid metabolism, although metabolites are accumulated in tissues and remain for a longer time. Therefore, the long term effect of curcumin needs thorough investigation. The present study aimed to analyze the anticarcinogenic action of curcumin in liver, even after withdrawal of treatment in Dalton's lymphoma bearing mice. Oxidative stress observed during lymphoma progression reduced antioxidant enzyme activities, and induced angiogenesis as well as activation of early stress activated genes and glycolytic pathway. Curcumin treatment resulted in activation of antioxidant enzyme super oxide dismutase and down regulation of ROS level as well as activity of ROS producing enzyme NADPH:oxidase, expression of stress activated genes HIF-1α, cMyc and LDH activity towards normal level. Further, it lead to significant inhibition of angiogenesis, observed via MMPs activity, PKCα and VEGF level, as well as by matrigel plug assay. Thus findings of this study conclude that the long term effect of curcumin shows anticarcinogenic potential via induction of antioxidant defense system and inhibition of angiogenesis via down regulation of stress activated genes and glycolytic pathway in liver of lymphoma bearing mice. © 2014 Das, Vinayak.
Long term effect of curcumin in restoration of tumour suppressor p53 and phase-II antioxidant enzymes via activation of Nrf2 signalling and modulation of inflammation in prevention of cancer
(Public Library of Science, 2015) Laxmidhar Das; Manjula Vinayak
Inhibition of carcinogenesis may be a consequence of attenuation of oxidative stress via activation of antioxidant defence system, restoration and stabilization of tumour suppressor proteins along with modulation of inflammatory mediators. Previously we have delineated significant role of curcumin during its long term effect in regulation of glycolytic pathway and angiogenesis, which in turn results in prevention of cancer via modulation of stress activated genes. Present study was designed to investigate long term effect of curcumin in regulation of Nrf2 mediated phase-II antioxidant enzymes, tumour suppressor p53 and inflammation under oxidative tumour microenvironment in liver of T-cell lymphoma bearing mice. Inhibition of Nrf2 signalling observed during lymphoma progression, resulted in down regulation of phase II antioxidant enzymes, p53 as well as activation of inflammatory signals. Curcumin potentiated significant increase in Nrf2 activation. It restored activity of phase-II antioxidant enzymes like GST, GR, NQO1, and tumour suppressor p53 level. In addition, curcumin modulated inflammation via upregulation of TGF-β and reciprocal regulation of iNOS and COX2. The study suggests that during long term effect, curcumin leads to prevention of cancer by inducing phase-II antioxidant enzymes via activation of Nrf2 signalling, restoration of tumour suppressor p53 and modulation of inflammatory mediators like iNOS and COX2 in liver of lymphoma bearing mice. © 2015 Das, Vinayak.
Long-term effect of curcumin down-regulates expression of tumor necrosis factor-α and interleukin-6 via modulation of E26 transformation-specific protein and nuclear factor-κB transcription factors in livers of lymphoma bearing mice
(Informa Healthcare, 2014) Laxmidhar Das; Manjula Vinayak
Tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) are typical multifunctional proinflammatory cytokines involved actively in the regulation of immunity, hematopoiesis, inflammation and carcinogenesis. Coordinated regulation of these cytokines could be required for effective regulation of early phase inflammation and cancer progression. The present work was aimed to analyze the anti-carcinogenic action of curcumin on the expression of TNF-α and IL-6 even after withdrawal of treatment. Up-regulated expressions of TNF-α and IL-6 in terms of mRNA and protein levels in lymphoma bearing mice were significantly down-regulated by curcumin as compared to normal. Electrophoretic mobility shift assay (EMSA) results revealed that curcumin reduced binding of nuclear protein with ETS and NF-κB binding elements of TNF-α and IL-6 promoters, respectively. The anti-carcinogenic effect of curcumin against lymphoma progression has been reported previously. In continuation, the present study suggests that the long-term effect of curcumin may contribute to attenuate cancer progression via the down-regulation of TNF-α and IL-6 modulated by E26 transformation-specific protein (ETS) and nuclear factor-κB (NF-κB), respectively. © 2014 Informa UK, Ltd.