Beta-defensin index: A functional biomarker for oral cancer detection

There is an unmet clinical need for a non-invasive and cost-effective test for oral squamous cell carcinoma (OSCC) that informs clinicians when a biopsy is warranted. Human beta-defensin 3 (hBD-3), an epithelial cell-derived anti-microbial peptide, is pro-tumorigenic and overexpressed in early-stage OSCC compared to hBD-2. We validate this expression dichotomy in carcinoma in situ and OSCC lesions using immunofluorescence microscopy and flow cytometry. The proportion of hBD-3/hBD-2 levels in non-invasively collected lesional cells compared to contralateral normal cells, obtained by ELISA, generates the beta-defensin index (BDI). Proof-of-principle and blinded discovery studies demonstrate that BDI discriminates OSCC from benign lesions. A multi-center validation study shows sensitivity and specificity values of 98.2% (95% confidence interval [CI] 90.3-99.9) and 82.6% (95% CI 68.6-92.2), respectively. A proof-of-principle study shows that BDI is adaptable to a point-of-care assay using microfluidics. We propose that BDI may fulfill a major unmet need in low-socioeconomic countries where pathology services are lacking.

Predominant factors influencing reactive oxygen species in cancer stem cells

Reactive oxygen species (ROS) and its related signaling pathways and regulating molecules play a major role in the growth and development of cancer stem cells. The concept of ROS and cancer stem cells (CSCs) has been gaining much attention since the past decade and the evidence show that these CSCs possess robust self-renewal and tumorigenic potential and are resistant to conventional chemo- and radiotherapy and believed to be responsible for tumor progression, metastasis, and recurrence. It seems reasonable to say that cancer can be cured only if the CSCs are eradicated. ROS are Janus-faced molecules that can regulate cellular physiology as well as induce cytotoxicity, depending on the magnitude, duration, and site of generation. Unlike normal cancer cells, CSCs expel ROS efficiently by upregulating ROS scavengers. This unique redox regulation in CSCs protects them from ROS-mediated cell death and nullifies the effect of radiation, leading to chemoresistance and radioresistance. However, how these CSCs control ROS production by scavenging free radicals and how they maintain low levels of ROS is a challenging to understand and these attributes make CSCs as prime therapeutic targets. Here, we summarize the mechanisms of redox regulation in CSCs, with a focus on therapy resistance, its various pathways and microRNAs regulation, and the potential therapeutic implications of manipulating the ROS levels to eradicate CSCs. A better understanding of these molecules, their interactions in the CSCs may help us to adopt proper control and treatment measures.

Polyamine metabolism impacts T cell dysfunction in the oral mucosa of people living with HIV

Metabolic changes in immune cells contribute to both physiological and pathophysiological outcomes of immune reactions. Here, by comparing protein expression, transcriptome, and salivary metabolome profiles of uninfected and HIV+ individuals, we found perturbations of polyamine metabolism in the oral mucosa of HIV+ patients. Mechanistic studies using an in vitro human tonsil organoid infection model revealed that HIV infection of T cells also resulted in increased polyamine synthesis, which was dependent on the activities of caspase-1, IL-1β, and ornithine decarboxylase-1. HIV-1 also led to a heightened expression of polyamine synthesis intermediates including ornithine decarboxylase-1 as well as an elevated dysfunctional regulatory T cell (T_regDys)/T helper 17 (Th17) cell ratios. Blockade of caspase-1 and polyamine synthesis intermediates reversed the T_regDys phenotype showing the direct role of polyamine pathway in altering T cell functions during HIV-1 infection. Lastly, oral mucosal T_regDys/Th17 ratios and CD4 hyperactivation positively correlated with salivary putrescine levels, which were found to be elevated in the saliva of HIV+ patients. Thus, by revealing the role of aberrantly increased polyamine synthesis during HIV infection, our study unveils a mechanism by which chronic viral infections could drive distinct T cell effector programs and T_reg dysfunction.

Oral immune dysfunction is associated with the expansion of FOXP3+PD-1+Amphiregulin+ T cells during HIV infection

Residual systemic inflammation and mucosal immune dysfunction persist in people living with HIV, despite treatment with combined anti-retroviral therapy, but the underlying immune mechanisms are poorly understood. Here we report that the altered immune landscape of the oral mucosa of HIV-positive patients on therapy involves increased TLR and inflammasome signaling, localized CD4+ T cell hyperactivation, and, counterintuitively, enrichment of FOXP3+ T cells. HIV infection of oral tonsil cultures in vitro causes an increase in FOXP3+ T cells expressing PD-1, IFN-γ, Amphiregulin and IL-10. These cells persist even in the presence of anti-retroviral drugs, and further expand when stimulated by TLR2 ligands and IL-1β. Mechanistically, IL-1β upregulates PD-1 expression via AKT signaling, and PD-1 stabilizes FOXP3 and Amphiregulin through a mechanism involving asparaginyl endopeptidase, resulting in FOXP3+ cells that are incapable of suppressing CD4+ T cells in vitro. The FOXP3+ T cells that are abundant in HIV-positive patients are phenotypically similar to the in vitro cultured, HIV-responsive FOXP3+ T cells, and their presence strongly correlates with CD4+ T cell hyper-activation. This suggests that FOXP3+ T cell dysregulation might play a role in the mucosal immune dysfunction of HIV patients on therapy.

The Role of Dectin-1 Signaling in Altering Tumor Immune Microenvironment in the Context of Aging

An increased accumulation of immune-dysfunction-associated CD4⁺Foxp3⁺ regulatory T cells (T_regs) is observed in aging oral mucosa during infection. Here we studied the function of T_regs during oral cancer development in aging mucosa. First, we found heightened proportions of T_regs and myeloid-derived suppressor cells (MDSC) accumulating in mouse and human oral squamous cell carcinoma (OSCC) tissues. Using the mouse 4-Nitroquinoline 1-oxide(4-NQO) oral carcinogenesis model, we found that tongues of aged mice displayed increased propensity for epithelial cell dysplasia, hyperplasia, and accelerated OSCC development, which coincided with significantly increased abundance of IL-1β, T_regs, and MDSC in tongues. Partial depletion of T_regs reduced tumor burden. Moreover, fungal abundance and dectin-1 signaling were elevated in aged mice suggesting a potential role for dectin-1 in modulating immune environment and tumor development. Confirming this tenet, dectin-1 deficient mice showed diminished IL-1β, reduced infiltration of T_regs and MDSC in the tongues, as well as slower progression and reduced severity of tumor burden. Taken together, these data identify an important role of dectin-1 signaling in establishing the intra-tumoral immunosuppressive milieu and promoting OSCC tumorigenesis in the context of aging.

IL-1β-MyD88-mTOR Axis Promotes Immune-Protective IL-17A+Foxp3+ Cells During Mucosal Infection and Is Dysregulated With Aging

CD4⁺Foxp3⁺T_regs maintain immune homeostasis, but distinct mechanisms underlying their functional heterogeneity during infections are driven by specific cytokine milieu. Here we show that MyD88 deletion in Foxp3⁺ cells altered their function and resulted in increased fungal burden and immunopathology during oral Candida albicans (CA) challenge. Excessive inflammation due to the absence of MyD88 in T_regs coincided with a reduction of the unique population of IL-17A expressing Foxp3⁺ cells (T_reg17) and an increase in dysfunctional IFN-γ⁺/Foxp3⁺ cells (T_regIFN-γ) in infected mice. Failure of MyD88^-/- T_regs to regulate effector CD4⁺ T cell functions correlated with heightened levels of IFN-γ in CD4⁺ T cells, as well as increased infiltration of inflammatory monocytes and neutrophils in oral mucosa in vivo. Mechanistically, IL-1β/MyD88 signaling was required for the activation of IRAK-4, Akt, and mTOR, which led to the induction and proliferation of T_reg17 cells. In the absence of IL-1 receptor signaling, T_reg17 cells were reduced, but IL-6-driven expansion of T_regIFN-γ cells was increased. This mechanism was physiologically relevant during Candida infection in aged mice, as they exhibited IL-1 receptor/MyD88 defect in Foxp3⁺ cells, loss of p-mTOR^highT_reg17 cells and reduced levels of IL-1β in oral mucosa, which coincided with persistent tongue inflammation. Concurrent with T_reg dysfunction, aging was associated with increased CD4⁺ T cell hyperactivation and heightened levels of IL-6 in mice and humans in oral mucosa in vivo. Taken together, our data identify IL-1β/MyD88/T_reg axis as a new component that modulates inflammatory responses in oral mucosa. Also, dysregulation of this axis in an aging immune system may skew host defense towards an immunopathological response in mucosal compartments.

Oxidative Stress and Antioxidant Status in High-Risk Prostate Cancer Subjects

The oxidant/antioxidant balance has been implicated in the pathophysiology of prostate cancer. We investigated oxidative damage and antioxidant status in high-risk prostate cancer subjects. Reduced glutathione (GSH) levels were measured in erythrocytes, 8-hydroxydeoxyguanosine (8-OHdG) in leukocytes and plasma levels of catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GSH-R), glutathione S-transferase (GST), superoxide dismutase (SOD), and lipid peroxide products were measured in high-risk and age-matched healthy subjects. Serum PSA levels were significantly higher (p < 0.0001) in high-risk subjects, whereas GST (p < 0.0001) and GSH (p < 0.002) were higher in healthy controls. Levels of 8-OHdG, an oxidized nucleoside of DNA, were significantly increased (p < 0.0001) in high-risk subjects. No marked difference in the levels of CAT (p = 0.237), GSH-Px (p = 0.74), GSH-R (p = 0.344), SOD (p = 0.109), and lipid peroxide products (p = 0129) were observed between two groups. Pearson's correlation between GST and PSA (r = -0.69 (p < 0.0001)), GST and 8-OHdG (r = -0.62 (p < 0.0004)), GSH and 8-OHdG (r= -0.39 (p = 0.038)), and CAT and GSH-Px (r= -0.33 (p = 0.04)) were found to be negatively correlated, whereas 8-OHdG and PSA were positively associated (r= 0.57 (p < 0.002). These results indicate a significant role of oxidative damage in prostate carcinogenesis, particularly during the early stages of development. In conclusion, our data support the importance of antioxidant defense as a valuable diagnostic and/or prognostic marker in prostate cancer.

Short-chain fatty acids regulate regulatory T cells and intestinal pathology during oral mucosal infection

Complex interactions between the microbial flora and the host exert sophisticated means of immune tolerance and regulation mechanisms. One mechanism is by inducing the accumulation of regulatory T (Treg) cells. Here we show that the depletion of resident bacteria using antibiotics (Abx) causes oral and gut immunopathology during Oropharyngeal Candidiasis (OPC) infection. Abx treatment causes decrease in the frequency of Foxp3+ regulatory cells (Tregs) and IL-17A producing T cells, with a concomitant increase in oral tissue pathology. Although oral C. albicans (CA) is commonly controlled in the oral cavity, Abx treatment led to CA dependent oral and gut inflammation. The combination of short chain fatty acids (SCFA) partially controlled the pathology in Abx treated mice, correlating to an increase in the frequency of Foxp3+, IL-17A+, and Foxp3+IL-17A+ double positive (Treg17) cells in tongue and oral draining lymph nodes. SCFA enabled the restoration of Th17 cells and Treg cells and oral infection clearance, but did not reverse weight loss. Because SCFA treatment did not fully reverse the gut inflammation, it is evident that resident microbiota have SCFA independent homeostatic mechanisms in gut mucosa. We also found that SCFA potently induce Foxp3 and IL-17A expression in CD4+ T cells, depending on the cytokine milieu in vitro. Taken together, our data reveal that SCFA derived from resident bacteria play a critical role in controlling gut immunopathology by regulating T cell cytokines during oral mucosal infections.

Microbiome Dependent Regulation of Tregs and Th17 Cells in Mucosa

Mammals co-exist with resident microbial ecosystem that is composed of an incredible number and diversity of bacteria, viruses and fungi. Owing to direct contact between resident microbes and mucosal surfaces, both parties are in continuous and complex interactions resulting in important functional consequences. These interactions govern immune homeostasis, host response to infection, vaccination and cancer, as well as predisposition to metabolic, inflammatory and neurological disorders. Here, we discuss recent studies on direct and indirect effects of resident microbiota on regulatory T cells (T_regs) and Th17 cells at the cellular and molecular level. We review mechanisms by which commensal microbes influence mucosa in the context of bioactive molecules derived from resident bacteria, immune senescence, chronic inflammation and cancer. Lastly, we discuss potential therapeutic applications of microbiota alterations and microbial derivatives, for improving resilience of mucosal immunity and combating immunopathology.

Role of Short Chain Fatty Acids in Controlling Tregs and Immunopathology During Mucosal Infection

Interactions between mucosal tissues and commensal microbes control appropriate host immune responses and inflammation, but very little is known about these interactions. Here we show that the depletion of resident bacteria using antibiotics (Abx) causes oral and gut immunopathology during oropharyngeal candidiasis (OPC) infection. Antibiotic treatment causes reduction in the frequency of Foxp3+ regulatory cells (T_regs) and IL-17A producers, with a concomitant increase in oral tissue pathology. While C. albicans (CA) is usually controlled in the oral cavity, antibiotic treatment led to CA dependent oral and gut inflammation. A combination of short chain fatty acids (SCFA) controlled the pathology in Abx treated mice, correlating to an increase in the frequency of Foxp3+, IL-17A+, and Foxp3+IL-17A+ double positive (T_reg17) cells in tongue and oral draining lymph nodes. However, SCFA treatment did not fully reverse the gut inflammation suggesting that resident microbiota have SCFA independent homeostatic mechanisms in gut mucosa. We also found that SCFA potently induce Foxp3 and IL-17A expression in CD4+ T cells_, depending on the cytokine milieu in vitro. Depletion of T_regs alone in FDTR mice recapitulated oral inflammation in CA infected mice, showing that Abx mediated reduction of T_regs was involved in infection induced pathology. SCFA did not control inflammation in T_reg depleted mice in CA infected FDTR mice, showing that Foxp3⁺ T cell induction was required for the protective effect mediated by SCFA. Taken together, our data reveal that SCFA derived from resident bacteria play a critical role in controlling immunopathology by regulating T cell cytokines during mucosal infections. This study has broader implications on protective effects of resident microbiota in regulating pathological infections.

Diosmetin suppresses human prostate cancer cell proliferation through the induction of apoptosis and cell cycle arrest

Diosmetin, a plant flavonoid, has been shown to exert promising effects on prostate cancer cells as an anti‑proliferative and anticancer agent. In this study, using western blot analysis for protein expression and flow cytometry for cell cycle analysis, we determined that the treatment of the LNCaP and PC‑3 prostate cancer cells with diosmetin resulted in a marked decrease in cyclin D1, Cdk2 and Cdk4 expression levels (these proteins remain active in the G0‑G1 phases of the cell cycle). These changes were accompanied by a decrease in c-Myc and Bcl-2 expression, and by an increase in Bax, p27Kip1 and FOXO3a protein expression, which suggests the potential modulatory effects of diosmetin on protein transcription. The treatment of prostate cancer cells with diosmetin set in motion an apoptotic machinery by inhibiting X-linked inhibitor of apoptosis (XIAP) and increasing cleaved PARP and cleaved caspase-3 expression levels. On the whole, the findings of this study provide an in-depth analysis of the molecular mechanisms responsible for the regulatory effects of diosmetin on key molecules that perturb the cell cycle to inhibit cell growth, and suggest that diosmetin may prove to be an effective anticancer agent for use in the treatment of prostate cancer in the future.

Identification of Casz1 as a Regulatory Protein Controlling T Helper Cell Differentiation, Inflammation, and Immunity

While T helper (Th) cells play a crucial role in host defense, an imbalance in Th effector subsets due to dysregulation in their differentiation and expansion contribute to inflammatory disorders. Here, we show that Casz1, whose function is previously unknown in CD4+ T cells, coordinates Th differentiation in vitro and in vivo. Casz1 deficiency in CD4+ T cells lowers susceptibility to experimental autoimmune encephalomyelitis, consistent with the reduced frequency of Th17 cells, despite an increase in Th1 cells in mice. Loss of Casz1 in the context of mucosal Candida infection severely impairs Th17 and Treg responses, and lowers the ability of the mice to clear the secondary infection. Importantly, in both the models, absence of Casz1 causes a significant diminution in IFN-γ+IL-17A+ double-positive inflammatory Th17 cells (Th1* cells) in tissues in vivo. Transcriptome analyses of CD4+ T cells lacking Casz1 show a signature consistent with defective Th17 differentiation. With regards to Th17 differentiation, Casz1 limits repressive histone marks and enables acquisition of permissive histone marks at Rorc, Il17a, Ahr, and Runx1 loci. Taken together, these data identify Casz1 as a new Th plasticity regulator having important clinical implications for autoimmune inflammation and mucosal immunity.

Kaposi's sarcoma-associated herpesvirus infection promotes differentiation and polarization of monocytes into tumor-associated macrophages

Tumor associated macrophages (TAMs) promote angiogenesis, tumor invasion and metastasis, and suppression of anti-tumor immunity. These myeloid cells originate from monocytes, which differentiate into TAMs upon exposure to the local tumor microenvironment. We previously reported that Kaposi's sarcoma-associated herpes virus (KSHV) infection of endothelial cells induces the cytokine angiopoietin-2 (Ang-2) to promote migration of monocytes into tumors. Here we report that KSHV infection of endothelial cells induces additional cytokines including interleukin-6 (IL-6), interleukin-10 (IL-10), and interleukin-13 (IL-13) that drive monocytes to differentiate and polarize into TAMs. The KSHV-induced TAMs not only express TAM-specific markers such as CD-163 and legumain (LGMN) but also display a gene expression profile with characteristic features of viral infection. More importantly, KSHV-induced TAMs enhance tumor growth in nude mice. These results are consistent with the strong presence of TAMs in Kaposi's sarcoma (KS) tumors. Therefore, KSHV infection of endothelial cells generates a local microenvironment that not only promotes the recruitment of monocytes but also induces their differentiation and polarization into TAMs. These findings reveal a new mechanism of KSHV contribution to KS tumor development.

Abstract 2225: Green tea polyphenols suppress tumor growth and invasion by targeting matrix metalloproteinases, RECK and TIMP-3, in a mouse model implanted with prostate tumors

Green tea polyphenols (GTP) and its major constituent, epigallocatechin-3-gallate (EGCG) reactivate epigenetically silenced genes in cancer cells that reduces invasiveness and migration capabilities; however, the mechanisms whereby these effects occur are not well understood. RECK, a novel tumor suppressor and the tissue inhibitor of matrix metalloproteinase-3 (TIMP-3) genes negatively regulates matrix metalloproteinases (MMPs) and inhibits tumor invasion, angiogenesis and metastasis. In the present study, we demonstrate that GTP mediate epigenetic induction of RECK and TIMP-3 thereby playing a key role in suppressing invasiveness and gelatinolytic activity of MMP-2 and MMP-9 in vivo in an orthotopic implantation model of human prostate cancer. Athymic nude mice were implanted with human prostate cancer LNCaP tumor in the ventral prostate for 2 weeks and later treated DNA methyltransferase inhibitor, 5-aza-2'-deoxycytidine (AZA), histone deacetylase inhibitor, trichostatin A (TSA) and histone methyltransferase inhibitor, 3-Deazaneplanocin A (DZNep) individually at 0.1 mg/kg body weight intraperitoneally at alternate days/week; and combination of AZA+TSA and DZNep+TSA at similar doses and times; whereas GTP was provided peroral by gavage at 7.5 and 15.0 mg/kg body weight freshly prepared in 100µl PBS. Treatment of mice with GTP resulted in marked decrease in tumor growth and its local invasion in dose dependent manner, compared to treatment with epigenetic inhibitors and their combination after 8 weeks of intervention. GTP treatment significantly reduced serum levels of MMP-2, MMP-9 and VEGF, compared to treatment with epigenetic inhibitors alone. Combination of AZA+TSA exhibited similar effect which was equivalent to the lower dose of GTP treatment. Furthermore, GTP treatment significantly reduced EZH2 and H3K27me3 and class I HDAC protein levels in tumors. GTP partially reversed the hypermethylation status of RECK and TIMP3 gene and significantly enhanced their protein expression in the tumor tissue. Inhibition of VEGF, MMP-2 and MMP-9 levels were also noted after GTP treatment in tumor tissue in dose-dependent manner. Our findings suggest that induction of RECK and TIMP-3 are key epigenetic events modulated by GTP that results in suppression of matrix degradation and angiogenesis to delay prostate cancer invasion and its subsequent progression.

Citation Format: Eswar Shankar, Natarajan Bhaskaran, Rajnee Kanwal, Sanjay Gupta. Green tea polyphenols suppress tumor growth and invasion by targeting matrix metalloproteinases, RECK and TIMP-3, in a mouse model implanted with prostate tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2225. doi:10.1158/1538-7445.AM2017-2225

Abstract 2241: Diosmetin induces apoptosis in human prostate carcinoma cells via the Rictor pathway invitro and inhibits tumor growth in vivo

Cell growth is a fundamental biological process, where mTOR (mammalian target of rapamycin) pathway has its role, regulates cell growth by coordinating energy and nutrient signals with growth factor. mTOR protein kinase have two different complexes; complex-I contains major component raptor; a target of rapamycin and complex II; insensitive to rapamycin, has major component rictor. Rictor is important as it phosphorylates Ser-473 of Akt/PKB, which is essential for full Akt/PKB activation. Reports suggested that overexpression of mTOR in prostate cancer tissues, which may have potential role in prostate cancer progression. The known mTOR inhibitor rapamycin is not specific for mTOR-II complex, as it doesn’t inhibit main component Rictor. We need to have effective chemo-preventive agents, which can modulate Rictor signaling cascade to inhibit prostate cancer. Diosmetin (5, 7-Trihydroxy-4′-methoxyflavone), a natural flavonoid present in citrus plant, has anti-mutagenic and anti-allergic properties. Earlier we demonstrated growth factors Insulin-like growth factor-1 and cytokine (IL-6) induces Rictor expression, and phosphorylated Akt at Ser-473. Using diosmetin in concentration dependent fashion (5-40µM) to LNCaP and PC-3 cells down regulated phosphorylation of Rictor (Thr1135), Akt (Ser-473) and PKCα (Ser-657) expressions. This resulted in downregulation of survival molecules; Survivin and X-linked inhibitor of apoptosis protein, which induced apoptosis and inhibited cells growth. Luciferase tag PC-3 cells orthotopic implant in ventral prostate of nude mice represented significant decrease in tumor volume of diosmetin (20 and 50µg/animal/day) fed mice compared to control mice. Similarly bioluminescence imaging of orthotopically implanted mice represented decreased tumor luciferase activity after diosmetin feeding than control mice. Moreover, diosmetin feeding to tumor bearing nude mice reduced the phosphorylation of Rictor, (Thr1135), Akt (Ser-473) and PKCα (Ser-657) expressions and induced apoptotic events to inhibit tumor growth significantly. Based on results we may suggest diosmetin can be developed as an anticancer agent for prostate cancer.

Citation Format: Riddhi Patel, Rebecca Pakradooni, Ahmad Khalifa, Natarajan Bhaskaran, Sanjeev Shukla. Diosmetin induces apoptosis in human prostate carcinoma cells via the Rictor pathway invitro and inhibits tumor growth in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2241. doi:10.1158/1538-7445.AM2017-2241

Identification of a role for Casz1 in the control of T helper differentiation and inflammation

While T helper (Th) cells constitute a critical arm of adaptive immune system and are important for host defense, unregulated expansion and imbalance in Th effector subsets contribute to inflammatory disorders. Here we show that Casz1, whose function is previously unknown in CD4+ T cells, determines the balance between various Th subsets. As systemic knockout mice are embryonically lethal, we generated conditional CD4 Casz1 knockout mice. Conditional deletion of Casz1 in CD4+ T cells significantly inhibits Th17 cell differentiation, but promotes Th1 differentiation. Loss of Casz1 in CD4+ T cells lowers susceptibility to experimental autoimmune encephalomyelitis, consistent with the reduced frequency of Th17 cells, despite an increase in Th1 cells. These results underscore the critical role of Casz1 in determining Th17 lineage differentiation in vivo. Transcriptome analyses of Casz1 deficient CD4+ T cells show a signature consistent with defective Th17 differentiation but enhanced Th1 differentiation. Taken together, these data reveal Casz1 as a new T helper cell regulator having important clinical implications for autoimmune inflammation.

Abstract 3507: Rhamnetin enhances anti-proliferative and apoptotic effects on prostate cancer cells

Dysregulation of oxidative stress plays important role in both tumor development and response to anticancer drug treatment. Increased oxidative stress induces reactive oxygen species (ROS) which stimulate genes viz. FoxO3a and Klotho. Klotho modulates stress-induced senescence, whereas forkhead transcription factor; FoxO3a is known to involve in antioxidant, anti-proliferative and tumor suppressor functions. We have previously demonstrated that FoxO3a is deregulated in human prostate adenocarcinoma and in transgenic adenocarcinoma of the mouse prostate (TRAMP) model that mimics progressive forms of human disease. Here we demonstrate the potential involvement of Klotho protein in prostate cancer progression and using a natural agent; rhamnetin as anticancer in TRAMP mice modulated Klotho and FoxO3a signaling by altering ROS to inhibit prostate cancer. Per-oral feeding of rhamnetin at 10- and 20-μg/mouse/day (gavaged in 0.2 ml vehicle containing 0.5% methyl cellulose and 0.025% Tween 20) to TRAMP mice for six days per week for 16 weeks, starting at 8 weeks of age, exhibited marked reduction in tumor growth. Rhamnetin intake led to increased antioxidant potentials, which was evident from increased levels of klotho, Nrf2 and with significantly increased expression of Shc66 in the dorso-lateral prostate. Reports suggested that secretory klotho binds to multiple FGFRs (fibroblast growth factor receptors) with different affinity. However, TRAMP mice exhibited significantly increased FGFR1 expression in dorso-lateral prostates, which were reduced significantly after rhamnetin feeding to TRAMP mice. Furthermore, inhibited FGFR1 expression resulted in reduced phospho-Akt (Ser-473) and ERK1/2 phosphorylation in rhamnetin fed mice than control. This modulated signaling cascade decreased nuclear presence of p-Akt (Ser-473), which restricted FoxO3a phosphorylation and led to nuclear retention in dorso-lateral prostate. Increased nuclear presence of FoxO3a elevated transcriptional activity and expression of FoxO-dependent apoptotic protein, Bim. Moreover, rhamnetin feeding to TRAMP mice reduced Alix expression, which further helped in accelerating apoptotic machinery. Similarly rhamnetin treatment to human prostate cancer LNCaP and PC-3 cells also resulted in the restoration of Klotho and FoxO3a in the nucleus. Increase nuclear presence of Klotho and FoxO3a protein may be a decisive factor for increase resistance to oxidative stress and inhibited prostate cancer progression. Our finding suggests that rhamnetin may be developed as a preventive agent in prostate cancer.

Citation Format: Riddhi Patel, Rebecca Pakradooni, Christine Oak, Natarajan Bhaskaran, Sanjeev Shukla. Rhamnetin enhances anti-proliferative and apoptotic effects on prostate cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3507.

Transforming growth factor-β1 sustains the survival of Foxp3(+) regulatory cells during late phase of oropharyngeal candidiasis infection

As CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs) play crucial immunomodulatory roles during infections, one key question is how these cells are controlled during antimicrobial immune responses. Mechanisms controlling their homeostasis are central to ensure efficient protection against pathogens, as well as to control infection-associated immunopathology. Here we studied how their viability is regulated in the context of mouse oropharyngeal candidiasis (OPC) infection, and found that these cells show increased protection from apoptosis during late phase of infection and reinfection. Tregs underwent reduced cell death because they are refractory to T cell receptor restimulation-induced cell death (RICD). We confirmed their resistance to RICD, using mouse and human Tregs in vitro, and by inducing α-CD3 antibody-mediated apoptosis in vivo. The enhanced viability is dependent on increased transforming growth factor-β1 (TGF-β1) signaling that results in upregulation of cFLIP (cellular FLICE (FADD-like IL-1β-converting enzyme)-inhibitory protein) in Tregs. Protection from cell death is abrogated in the absence of TGF-β1 signaling in Tregs during OPC infection. Taken together, our data unravel the previously unrecognized role of TGF-β1 in promoting Treg viability, coinciding with the pronounced immunomodulatory role of these cells during later phase of OPC infection, and possibly other mucosal infections.

Mucosal Regulatory T Cells and T Helper 17 Cells in HIV-Associated Immune Activation

Residual mucosal inflammation along with chronic systemic immune activation is an important feature in individuals infected with human immunodeficiency virus (HIV), and has been linked to a wide range of co-morbidities, including malignancy, opportunistic infections, immunopathology, and cardiovascular complications. Although combined antiretroviral therapy (cART) can reduce plasma viral loads to undetectable levels, reservoirs of virus persist, and increased mortality is associated with immune dysbiosis in mucosal lymphoid tissues. Immune-based therapies are pursued with the goal of improving CD4⁺ T-cell restoration, as well as reducing chronic immune activation in cART-treated patients. However, the majority of research on immune activation has been derived from analysis of circulating T cells. How immune cell alterations in mucosal tissues contribute to HIV immune dysregulation and the associated risk of non-infectious chronic complications is less studied. Given the significant differences between mucosal T cells and circulating T cells, and the immediate interactions of mucosal T cells with the microbiome, more attention should be devoted to mucosal immune cells and their contribution to systemic immune activation in HIV-infected individuals. Here, we will focus on mucosal immune cells with a specific emphasis on CD4⁺ T lymphocytes, such as T helper 17 cells and CD4⁺Foxp3⁺ regulatory T cells (T_regs), which play crucial roles in maintaining mucosal barrier integrity and preventing inflammation, respectively. We hypothesize that pro-inflammatory milieu in cART-treated patients with immune activation significantly contributes to enhanced loss of Th17 cells and increased frequency of dysregulated T_regs in the mucosa, which in turn may exacerbate immune dysfunction in HIV-infected patients. We also present initial evidence to support this hypothesis. A better comprehension of how pro-inflammatory milieu impacts these two types of cells in the mucosa will shed light on mucosal immune dysfunction and HIV reservoirs, and lead to novel ways to restore immune functions in HIV⁺ patients.

Abstract 1913: Rhamnetin inhibits prostate cancer progression in an autochthonous mouse prostate cancer model

Aging increases oxidative stress and cancer risk. Age-regulated genes viz. FoxO3a and Klotho are stimulated by reactive oxygen species (ROS) due to increased oxidative stress. Klotho, an antiaging gene, modulates stress-induced senescence, and decreases with advancing age, whereas forkhead transcription factor, FoxO3a is known to involve in a paradigm that engages in antioxidant, anti-proliferative and tumor suppressor functions. We have previously demonstrated that FoxO3a is deregulated in human prostate adenocarcinoma and in transgenic adenocarcinoma of the mouse prostate (TRAMP) model that mimics progressive forms of human disease. Here we demonstrate the anticancer effects of rhamnetin, a dietary flavonoid present in fruits and vegetables, in modulating Klotho and FoxO3a signaling by suppressing ROS. Per-oral feeding of rhamnetin at 10- and 20-μg/mouse/day (gavaged in 0.2 ml vehicle containing 0.5% methyl cellulose and 0.025% Tween 20) to TRAMP mice for six days per week for 16 weeks, starting at 8 weeks of age, exhibited marked reduction in tumor growth with no signs of metastasis. Rhamnetin feeding to TRAMP resulted in a significant dose-dependent reduction in FoxO3a, in the dorso-lateral prostates. FoxO3a protein was redistributed more in nuclear than the cytosolic compartments after rhamnetin feeding. Simultaneously, decreased FoxO3a phosphorylation (Ser-253) was observed in the dorso-lateral prostate, which correlated with decreased cytoplasmic retention of FoxO3a with no significant changes in 14-3-3 chaperone protein in the cytosol after rhamnetin feeding. Additionally, decreased IGF-1 protein expression with subsequent decrease in p-Akt (Ser-473) and p-Erk1/2 (Thr202/Tyr204) was observed after rhamnetin feeding demonstrating that the decreased nuclear presence of p-Akt (Ser-473) may restrict FoxO3a phosphorylation and its retention in the nucleus along with decreased p-Erk1/2 levels in the dorso-lateral prostate. Furthermore, rhamnetin intake led to increased levels of SOD2 and significantly enhanced the expression of the thioredoxin/peroxiredoxin (Trx/Prx) in the dorso-lateral prostate. Similar findings were recorded in cell culture studies where rhamnetin treatment to human prostate cancer LNCaP and PC-3 cells resulted in the restoration of Klotho and FoxO3a in the nucleus. This increase in Klotho and FoxO3a protein expressions in the nucleus may be a decisive factor for increase resistance to oxidative stress and cancer progression. Our finding suggests that rhamnetin has potential to modulate Klotho and FoxO signaling cascades and could be represented as therapeutic targets in prostate cancer.

Citation Format: Christine Oak, Natarajan Bhaskaran, Sanjay Gupta, Sanjeev Shukla. Rhamnetin inhibits prostate cancer progression in an autochthonous mouse prostate cancer model. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1913. doi:10.1158/1538-7445.AM2015-1913

TLR-2 Signaling Promotes IL-17A Production in CD4+CD25+Foxp3+ Regulatory Cells during Oropharyngeal Candidiasis

Recent studies show that CD4⁺CD25⁺Foxp3⁺ regulatory cells (T_regs) produce effector cytokines under inflammatory conditions. However, the direct role of microbial agents that serve as toll-like receptor (TLR) ligands in the induction of effector cytokines in T_regs is less clear. Here we show that CD4⁺Foxp3⁺T_regs produce the effector cytokine IL-17A during oropharyngeal candidiasis (OPC) and inflammatory bowel disease in a TLR-2/Myd88 signaling dependent manner. TLR-2 ligands promote proliferation in T_regs in the presence and absence of TCR signals and inflammatory cytokines in vitro. The proliferation is directly dependent on TLR-2 expression in T_regs. Consistent with this, Tlr2^−/− mice harbor fewer thymically derived T_regs and peripheral T_regs under homeostatic conditions in vivo. However, under Th17 inducing conditions, IL-6 and TLR-2 signaling both in T_regs as well as antigen presenting cells (APC) are critical for maximal ROR-γt and IL-17A up-regulation in Foxp3⁺ T_regs. The minimal and transient loss of Foxp3 expression and suppressive properties are due to the presence of IL-6 in the milieu, but not the direct effect of TLR-2 signaling in T_regs. Taken together, our data reveal that TLR-2 signaling promotes not only proliferation, but also IL-17A in T_regs, depending on the cytokine milieu. These IL-17A producing T_regs may be relevant in mucosal infections and inflammation.

Th17 inflammation model of oropharyngeal candidiasis in immunodeficient mice

Oropharyngeal Candidiasis (OPC) disease is caused not only due to the lack of host immune resistance, but also the absence of appropriate regulation of infection-induced immunopathology. Although Th17 cells are implicated in antifungal defense, their role in immunopathology is unclear. This study presents a method for establishing oral Th17 immunopathology associated with oral candidal infection in immunodeficient mice. The method is based on reconstituting lymphopenic mice with in vitro cultured Th17 cells, followed by oral infection with Candida albicans (C. albicans). Results show that unrestrained Th17 cells result in inflammation and pathology, and is associated with several measurable read-outs including weight loss, pro-inflammatory cytokine production, tongue histopathology and mortality, showing that this model may be valuable in studying OPC immunopathology. Adoptive transfer of regulatory cells (Tregs) controls and reduces the inflammatory response, showing that this model can be used to test new strategies to counteract oral inflammation. This model may also be applicable in studying oral Th17 immunopathology in general in the context of other oral diseases.

Inflammatory Signaling Involved in High-Fat Diet Induced Prostate Diseases

High-Fat Diet (HFD) has emerged as an important risk factor not only for obesity and diabetes but also for urological disorders. Recent research provides ample evidence that HFD is a putative cause for prostatic diseases including prostate cancer. The mechanisms whereby these diseases develop in the prostate have not been fully elucidated. In this review we discuss signaling pathways intricately involved in HFD-induced prostate disease. We performed a search through PUBMED using key words "high fat diet" and "prostate". Our data and perspectives are included in this review along with research performed by various other groups. HFD is positively associated with an increased risk of benign prostatic hyperplasia (BPH) and prostate cancer. HFD induces oxidative stress and inflammation in the prostate gland, and these adverse influences transform it from a normal to a diseased state. Studies demonstrate that HFD accelerates the generation of reactive oxygen species by driving the NADPH oxidase system, exacerbating oxidative stress in the prostate. HFD also causes a significant increase in the levels of pro-inflammatory cytokines and gene products through activation of two important signaling pathways: the Signal Transducer and Activator of Transcription (STAT)-3 and Nuclear Factor-kappa B (NF-κB). Both these pathways function as transcription factors required for regulating genes involved in proliferation, survival, angiogenesis, invasion and inflammation. The crosstalk between these two pathways enhances their regulatory function. Through its influences on the NF-κB and Stat-3 signaling pathways, it appears likely that HFD increases the risk of development of BPH and prostate cancer.

Differential effects of TLR-2 ligands on CD4+ CD25+ Foxp3+ regulatory cells depending on inflammatory cytokine milieu (IRC4P.489)

The responsiveness of CD4+CD25+Foxp3+ thymic Tregs (tTregs) towards microbial agents that serve as toll-like receptor (TLR) ligands is unclear. This study investigates the effects of TLR ligands on Tregs. We show that TLR-2 ligands promote IL-2 dependent survival and proliferation of tTregs both in the presence or absence of TCR signals and inflammatory cytokines. The proliferation is directly dependent on TLR-2 expression on Tregs showing that TLR-2 ligands may be involved in Treg proliferation in vivo. Consistent with this, Tlr-2-/- mice harbor fewer Tregs in colon and mesenteric lymph nodes in vivo. However, in the presence of IL-6 and TCR signals, Tregs also acquire effector functions by producing IL-17A. However, they retain their suppressive properties and do not lose Foxp3 expression. Their effector function is dependent on TLR signaling by antigen presenting cells, IL-6 and IL-23 in the milieu, but not on direct TLR-2 signaling by Tregs. IL-17A production in Tregs is also relevant in vivo, as CD4+Foxp3+Tregs are capable of producing IL-17A without losing their suppressive properties during oropharyngeal candidiasis and inflammatory bowel disease. These data show that CD4+Foxp3+ tTregs are a stable lineage of cells, and that TLR-2 ligands promote their proliferation without inducing plasticity. Moreover the data show for the first time, the direct and indirect effects of TLR-2 ligands that differentially regulate tTreg proliferation and effector functions.

Isolation of T cells from mouse oral tissues

Background

Utilizing mouse models provides excellent immunological and experimental tools to study oral immune responses. However for functional assays, isolating T lymphocytes from the oral tissues has proved to be challenging due to the absence of reliable methods that yield viable cells with consistency. To study adaptive immune cell interactions in the oral mucosal tissues, it is necessary to isolate T cells with a good viability and study them at the single cell level.

Findings

We have established an improved method to isolate immune cells, including T_regs and Th17 cells from intra-epithelial niches and lamina propria of the tongue, gingival and palatal tissues in the oral mucosa of mice.

Conclusion

This new method of isolating immune cells from oral tissues will enable us to further our understanding of oral tissue immune cells and their role during oral infections and oral inflammation.

Deregulation of FoxO3a accelerates prostate cancer progression in TRAMP mice

BACKGROUND

Forkhead box, class "O" (FoxO) transcription factors are involved in multiple signaling pathways and possess tumor suppressor functions. Loss of PTEN and activation of PI3K/Akt is frequently observed in prostate cancer, which may potentially inactivate FoxO activity. We therefore investigated the role of FoxO transcription factors in prostate cancer progression, in particular FoxO3a, in transgenic adenocarcinoma of the mouse prostate (TRAMP) mice, which mimics progressive forms of human disease.

METHODS

Prostate cancer progression in TRAMP mice was followed from 8 to 28 weeks. Expression patterns of Akt, FoxO1a, FoxO3a, FoxO4, and their phosphorylated form, DNA binding activity and downstream signaling molecules during different stages of disease progression were examined by immunoblotting, immunoprecipitation, enzyme-linked immunoabsorbant assay (ELISA), and immunohistochemistry. Inhibition of FoxO3a activity was attained by using FoxO3a peptide treatment to TRAMP mice.

RESULTS

In TRAMP mice, FoxO3a activity is negatively regulated by Akt/PKB through post-translational modification. Progressive increase in Akt activation during prostate cancer progression led to increase phosphorylation of FoxO3a and binding with 14-3-3, which potentially affected its transcriptional activity in age-specific manner. Furthermore, blocking FoxO3a activity resulted in accelerated prostate cancer progression in these mice, which was associated with the loss of cell cycle control and increased proliferation and survival markers.

CONCLUSIONS

Restoration of FoxO3a activity represents an attractive therapeutic target in the chemoprevention and possibly in inhibition of progression of prostate cancer.

Apigenin inhibits prostate cancer progression in TRAMP mice via targeting PI3K/Akt/FoxO pathway

Forkhead box O (FoxO) transcription factors play an important role as tumor suppressor in several human malignancies. Disruption of FoxO activity due to loss of phosphatase and tensin homolog and activation of phosphatidylinositol-3 kinase (PI3K)/Akt are frequently observed in prostate cancer. Apigenin, a naturally occurring plant flavone, exhibits antiproliferative and anticarcinogenic activities through mechanisms, which are not fully defined. In the present study, we show that apigenin suppressed prostate tumorigenesis in transgenic adenocarcinoma of the mouse prostate (TRAMP) mice through the PI3K/Akt/FoxO-signaling pathway. Apigenin-treated TRAMP mice (20 and 50 μg/mouse/day, 6 days/week for 20 weeks) exhibited significant decrease in tumor volumes of the prostate as well as completely abolished distant organ metastasis. Apigenin treatment resulted in significant decrease in the weight of genitourinary apparatus (P < 0.0001), dorsolateral (P < 0.0001) and ventral prostate (P < 0.028), compared with the control group. Apigenin-treated mice showed reduced phosphorylation of Akt (Ser473) and FoxO3a (Ser253), which correlated with its increased nuclear retention and decreased binding of FoxO3a with 14-3-3. These events lead to reduced proliferation as assessed by Ki-67 and cyclin D1, along with upregulation of FoxO-responsive proteins BIM and p27/Kip1. Complementing in vivo results, similar observations were noted in human prostate cancer LNCaP and PC-3 cells after apigenin treatment. Furthermore, binding of FoxO3a with p27/Kip1 was markedly increased after 10 and 20 μM apigenin treatment resulting in G0/G1-phase cell cycle arrest, which was consistent with the effects elicited by PI3K/Akt inhibitor, LY294002. These results provide convincing evidence that apigenin effectively suppressed prostate cancer progression, at least in part, by targeting the PI3K/Akt/FoxO-signaling pathway.

Abstract 5452: High-fat diet induces inflammation by increasing estrogen levels through Stat3, estrogen receptor alpha and aromatase in the mouse prostate

High-fat diet (HFD), an unfortunate lifestyle choice common in the Western world, is associated with inflammation and thereby is regarded as a risk factor for various diseases including obesity, diabetes, and cancer. The molecular mechanism(s) responsible for HFD-induced inflammation in the prostate gland are not well understood. Estrogen receptor alpha (ER-α), signal transducer and activator of transcription (Stat)-3 and aromatase are important signaling molecules constitutively activated during inflammation and have been shown to be upregulated in prostate cancer. We have previously reported that HFD activates a pro-inflammatory response in the prostate through elevated expression of Stat-3 (Prostate 72:233-43, 2012). In the current study, we sought to investigate a possible link between intraprostatic inflammation, HFD feeding, signaling molecules involved in inflammation viz. ER-α, Stat-3, p-Stat3 (Ser727) and aromatase. C57BL/6 mice were fed either a regular diet (RD) or a HFD for 4, 8 and 12 weeks. Serum, visceral fat and prostate tissues were obtained for analysis. HFD intake caused an increase in fat and serum testosterone levels. No significant changes were observed in the testosterone levels in the prostate. A marked increase in estrogen levels was noted in the prostate and visceral fat at 8 weeks of HFD intake. HFD feeding resulted in a significant increase in the expression of aromatase, ER-α, Stat-3 and p-Stat3 (Ser727) at the message and protein levels. Immunoprecipitation and ChIP analysis demonstrated an increased association between aromatase, p-Stat-3 and ER-α in the HFD group. IHC analysis revealed higher expression of Stat-3, ER-α and aromatase in the prostate, accompanied by the morphologic evidence of increased intraprostatic inflammation in the HFD group. Taken together, our findings suggest that HFD increases estrogen levels by increased binding of ER-α and p-Stat-3 to the promoter of aromatase and their interaction is associated with increased intraprostatic inflammation which might contribute to the initiation and development of prostate cancer.

Citation Format: Natarajan Bhaskaran, Sanjeev Shukla, Vijay S. Thakur, Melissa A. Babcook, Gregory T. MacLennan, Guiming Liu, Firouz Daneshgari, Sanjay Gupta. High-fat diet induces inflammation by increasing estrogen levels through Stat3, estrogen receptor alpha and aromatase in the mouse prostate. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5452. doi:10.1158/1538-7445.AM2013-5452

Abstract 9: Oxidative stress and antioxidant status in high-risk prostate cancer subjects

Prostate cancer is the most commonly diagnosed cancer among men in the United States. Epidemiological, experimental and clinical studies have implicated chronic inflammation and oxidative stress in the development and progression of prostate cancer. Diet, environmental carcinogens, aging, and other inflammatory diseases cause aberration in reactive oxygen species (ROS) which may play critical roles in the development and progression of prostate cancer. Chronic inflammation results in lipid peroxidation and generation of highly reactive products with the potential to damage DNA. The extent of ROS-induced oxidative damage can be determined by measuring reductions in levels of endogenous antioxidant defense enzymes such as glutathione-s-transferase (GST), glutathione peroxidase (GSH-Px), glutathione reductase (GSH-R), catalase (CAT), superoxide dismutase (SOD) and non-protein thiols, which participate in detoxification processes. The aim of this study was to assess the oxidative status and antioxidant defense mechanisms in 20 men, 54-84 years of age, with increased risk of developing prostate cancer because of the presence of high-grade prostatic intraepithelial neoplasia (HGPIN) in their prostate biopsies, as compared to 20 healthy men in the same age range whose prostate biopsies showed no evidence of HGPIN. Total glutathione levels were measured in red blood cells, and plasma levels of GSH-Px, GSH-R, CAT, SOD, and PSA were analyzed. Data obtained after analysis was represented as mean, standard error and box plot. Serum PSA levels were significantly (p&lt;0.0001) higher in men with HGPIN, whereas glutathione (P=0.002) levels were higher in men without HGPIN. Levels of 8-hydroxydeoxyguanosine (8-OHdG), an oxidized nucleoside of DNA that is most often detected in the DNA of white blood cells, were significantly (p&lt;0.00001) increased in men with HGPIN. There was no significant difference in levels of GSH-R, GSH-Px, lipid peroxide products, CAT, and SOD in men with or without HGPIN. A significant association in between CAT and GSH-Px activity [r= -0.33 (P=0.04)]; PSA levels and 8-OHdG [r= 0.57 (P=0.002] and between glutathione and 8-OHdG [r= -0.39 (P=0.038] were noted between men with HGPIN and healthy controls using Pearson correlation coefficient. These findings indicate that oxidative stress induces imbalances in oxidant/antioxidant status. Increased 8-OHdG levels may lead to oxidative damage and may thereby play an important role in the development of prostate cancer.

Citation Format: Sanjeev Shukla, Janmejai K. Srivastava, Rajnee Kanwal, Akbar Nawab, Haripaul Sharma, Natarajan Bhaskaran, Claudia Lillibridge, Lee E. Ponsky, Pingfu Fu, Gregory T. MacLennan, Sanjay Gupta. Oxidative stress and antioxidant status in high-risk prostate cancer subjects. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 9. doi:10.1158/1538-7445.AM2013-9

Abstract 3684: Differential mechanisms of green tea polyphenols-induced apoptosis in human prostate cancer cells: Role of p53

Tumor suppressor gene p53 is frequently inactivated in a variety of human cancers including prostate cancer and is associated with therapeutic resistance. We have previously demonstrated that green tea polyphenols (GTP) induces apoptosis in prostate cancer cells irrespective of p53 status (Carcinogenesis 33:377-84, 2012). However, the molecular mechanisms underlying these observations are not properly understood. In the present study we investigated the mechanisms of GTP-induced apoptosis in human prostate cancer cells with and without functional p53. Human prostate cancer LNCaP cells were stably transfected with short hairpin-53 (LNCaPshp53) and control vector (LNCaPshV), exposed to GTP in dose and time dependent manner. GTP exposure induced p53 stabilization and activation of downstream targets p21/waf1 and Bax in dose-dependent manner specifically in LNCaPshV cells. However, GTP-induced FAS upregulation through the activation of c-jun N-terminal kinase resulting in FADD phosphorylation, caspase-8 activation and truncation of BID leading to apoptosis was common in both LNCaPshV and LNCaPshp53 cells. In parallel, treatment of cells with GTP resulted in inhibition of survival pathway, mediated by Akt deactivation and loss of BAD phosphorylation more prominently in LNCaPshp53 cells. These distinct routes of cell death converged to a common pathway leading to loss of mitochondrial transmembrane potential, cytochrome c release and activation of terminal caspases resulting in PARP cleavage. GTP-induced apoptosis was attenuated with JNK inhibitor, SP600125 in both cell lines; whereas PI3K-Akt inhibitor, LY294002 resulted in increased cell death in LNCaPshp53 cells, establishing the role of two distinct pathways of GTP-mediated apoptosis. Furthermore, GTP exposure resulted in the inhibition of class I HDAC protein, accumulation of acetylated histone H3 in total cellular chromatin resulting in increased accessibility to bind with the promoter sequences of p21/waf1 and Bax irrespective of p53 status of cells, consistent with the effects elicited by HDAC inhibitor, trichostatin A. These results demonstrate that GTP induces prostate cancer cell death by two distinct mechanisms irrespective of p53 status, thus identifying for the first time through defined molecular targets for their chemopreventive and/or therapeutic actions.

Citation Format: Karishma Gupta, Vijay S. Thakur, Natarajan Bhaskaran, Akbar Nawab, Melissa A. Babcook, Mark W. Jackson, Sanjay Gupta. Differential mechanisms of green tea polyphenols-induced apoptosis in human prostate cancer cells: Role of p53. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3684. doi:10.1158/1538-7445.AM2013-3684

Protection against oxidative DNA damage and stress in human prostate by glutathione S-transferase P1

The pi-class glutathione S-transferase (GSTP1) actively protect cells from carcinogens and electrophilic compounds. Loss of GSTP1 expression via promoter hypermethylation is the most common epigenetic alteration observed in human prostate cancer. Silencing of GSTP1 can increase generation of reactive oxygen species (ROS) and DNA damage in cells. In this study we investigated whether loss of GSTP1 contributes to increased DNA damage that may predispose men to a higher risk of prostate cancer. We found significantly elevated (103%; P < 0.0001) levels of 8-oxo-2'-deoxogunosine (8-OHdG), an oxidative DNA damage marker, in adenocarcinomas, compared to benign counterparts, which positively correlated (r = 0.2) with loss of GSTP1 activity (34%; P < 0.0001). Silencing of GSTP1 using siRNA approach in normal human prostate epithelial RWPE1 cells caused increased intracellular production of ROS and higher susceptibility of cells to H2 O2 -mediated oxidative stress. Additionally, human prostate carcinoma LNCaP cells, which contain a silenced GSTP1 gene, were genetically modified to constitutively express high levels of GSTP1. Induction of GSTP1 activity lowered endogenous ROS levels in LNCaP-pLPCX-GSTP1 cells, and when exposed to H2 O2 , these cells exhibited significantly reduced production of ROS and 8-OHdG levels, compared to vector control LNCaP-pLPCX cells. Furthermore, exposure of LNCaP cells to green tea polyphenols caused reexpression of GSTP1, which protected the cells from H2 O2 -mediated DNA damage through decreased ROS production compared to nonexposed cells. These results suggest that loss of GSTP1 expression in human prostate cells, a process that increases their susceptibility to oxidative stress-induced DNA damage, may be an important target for primary prevention of prostate cancer.

Induction of heme oxygenase-1 by chamomile protects murine macrophages against oxidative stress

AIMS

Protection of cells from oxidative insult may be possible through direct scavenging of reactive oxygen species, or through stimulation of intracellular antioxidant defense mechanisms by induction of antioxidant gene expression. In this study we investigated the cytoprotective effect of chamomile and elucidated the underlying mechanisms.

MAIN METHODS

The cytoprotective effect of chamomile was examined on H(2)O(2)-induced cellular stress in RAW 264.7 murine macrophages.

KEY FINDINGS

RAW 264.7 murine macrophages treated with chamomile were protected from cell death caused by H(2)O(2). Treatment with 50μM H(2)O(2) for 6h caused significant increase in cellular stress accompanied by cell death in RAW 264.7 macrophages. Pretreatment with chamomile at 10-20μg/mL for 16h followed by H(2)O(2) treatment protected the macrophages against cell death. Chamomile exposure significantly increased the expression of antioxidant enzymes viz. heme oxygenase-1 (HO-1), peroxiredoxin-1 (Prx-1), and thioredoxin-1 (Trx-1) in a dose-dependent manner, compared with their respective controls. Chamomile increased nuclear translocation of Nrf2 with increased phosphorylated Nrf2 levels, and binding to the antioxidant response element in the nucleus.

SIGNIFICANCE

These molecular findings for the first time provide insights into the mechanisms underlying the induction of phase 2 enzymes through the Keap1-Nrf2 signaling pathway by chamomile, and provide evidence that chamomile possesses antioxidant and cytoprotective properties.

Chamomile confers protection against hydrogen peroxide-induced toxicity through activation of Nrf2-mediated defense response

Oxidative stress plays an important role in the development of various human diseases. Aqueous chamomile extract is used as herbal medicine, in the form of tea, demonstrated to possess antiinflammatory and antioxidant properties. We demonstrate the cytoprotective effects of chamomile on hydrogen peroxide (H₂O₂)-induced cellular damage in macrophage RAW 264.7 cells. Pretreatment of cells with chamomile markedly attenuated H₂O₂-induced cell viability loss in a dose-dependent manner. The mechanisms by which chamomile-protected macrophages from oxidative stress was through the induction of several antioxidant enzymes including NAD(P)H:quinone oxidoreductase, superoxide dismutase, and catalase and increase nuclear accumulation of the transcription factor Nrf2 and its binding to antioxidant response elements. Furthermore, chamomile dose-dependently reduced H₂O₂-mediated increase in the intracellular levels of reactive oxygen species. Our results, for the first time, demonstrate that chamomile has protective effects against oxidative stress and might be beneficial to provide defense against cellular damage.

Abstract 2569: Lyc-O-Mato causes cell cycle arrest and apoptosis in human bladder transitional carcinoma cells

Approximately two thirds of new bladder cancer cases in the United States are superficial papillary transitional cell carcinoma (TCC), the majority of which are low-grade neoplasms. Data suggest that bladder carcinogenesis is a multi-step, multi-focal (field effect) process, possibly involving the spread of pre-malignant clones-all of which are prerequisites for effective preventive and/or interventional approaches. Epidemiological data suggests an inverse relationship between serum levels of carotenoids and risk of bladder cancer which has encouraged further investigation. In this study, we evaluated the effect of Lyc-O-Mato® (a crude tomato extract containing 10% lycopene and other tomato phytonutrients viz. tocopherols, phytoene, phytofluene, beta-carotene, phospholipids and phytosterols) on human bladder cancer cell growth, cell cycle modulation, induction of apoptosis, and associated molecular alterations. Treatment of bladder cancer cell lines (T-24, high-grade TCC and TCC-SUP, high-grade invasive tumor) with Lyc-O-Mato® at doses of 1-60µM resulted in inhibition of cell growth along with a G1 arrest in T24 cells and G2/M arrest in TCCSUP cells at 24 h post-treatment. In other studies, Lyc-O-Mato® treatment strongly induced the expression of p21/waf1 and p27/kip1, and resulted in a decrease in cyclin-dependent kinases (CDKs) and cyclins involved in G1 and G2/M progression in T24 and TCC SUP cells. Lyc-O-Mato® exposure to these cells showed an increased interaction between cyclin dependent kinase inhibitors (CDKIs)-cyclin-dependent kinases (CDKs) and decrease in the interaction of cyclins and CDKs with their respective stages of the cell cycle. Furthermore, Lyc-O-Mato® treatment significantly reduced the phosphorylation of Retinoblastoma at Serine780, although no significant changes were observed in the total levels of this protein. In additional studies, Lyc-O-Mato® showed a dose- and time-dependent apoptotic death in both T24 and TCC SUP cells which was associated with significant downregulation of survivin along with the enhancement of pro-apoptotic protein, Bax. These observations provide a strong rationale for further evaluating preventive and/or intervention strategies for Lyc-O-Mato® in pre-clinical models of bladder cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2569. doi:1538-7445.AM2012-2569

Abstract 2594: Chamomile (Matricaria chamomilla L.) upregulates heme oxygenase-1 through activation of ERK-Nrf2 signaling: Cytoprotective mechanism against oxidative damage

Protection of cells from oxidative insult could be attained by directly scavenging the reactive oxygen species or more significantly by stimulating the intracellular antioxidant defense through induction of antioxidant gene expression. It has been well documented that the transcriptional activation of Nrf2 in response to oxidative stress results in increased nuclear translocation and its binding to the antioxidant response elements (AREs) found in the promoters of genes, encoding antioxidant enzymes. Studies have demonstrated that Mitogen Activated Protein Kinase (MAPK) family is important in modulating ARE driven gene expression via Nrf2 activation. In the present study, we investigated which particular MAPK family member plays an important role in the regulation of chamomile-induced Nrf2-dependent ARE activity and ARE-driven antioxidant gene expression in mouse RAW 264.7 macrophage cells. We used aqueous chamomile extract (5, 10, 20 and 40µg/mL) obtained from dried flowers with and without MAPK pharmacological inhibitors to investigate their effect on Nrf2 activation. Pretreatment of macrophages with chamomile significantly induced the expression of antioxidant gene, heme oxygenase (HO)-1 mRNA and protein in concentration and time dependent manner. Chamomile exposure increased the nuclear Nrf2 levels which correlated with Nrf2 phosphorylation and its dissociation from Keap1 in both concentration and time dependent manner. Furthermore, chamomile treatment increased the phosphorylation of ERK1/2, but not other kinases, which might result in Nrf2 phosphorylation. Treatment of macrophages with 5µM U0126 (ERK1/2 inhibitor) was able to reduce chamomile-induced ERK phosphorylation, as well as Nrf2 phosphorylation, affecting the levels of HO-1. To confirm the role of Nrf2 in the induction of HO-1, knockdown of Nrf2 using siRNA in the macrophages resulted in significant inhibition of HO-1 expression. Furthermore, chamomile protected the cells against H2O2-induced oxidative stress and this protective effect was inhibited by U0126 and ZnPP (Zinc protoporphyrin-10µM), a HO-1 inhibitor. Taken together, these data suggest that chamomile augments cellular antioxidant defense capacity through induction of HO-1 via ERK-Nrf2-ARE signaling pathway, thereby protecting the cells from oxidative stress.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2594. doi:1538-7445.AM2012-2594

High-fat diet activates pro-inflammatory response in the prostate through association of Stat-3 and NF-κB

BACKGROUND

Signal transducer and activator of transcription (Stat)-3 and nuclear factor-kappa B (NF-κB) are important signaling pathways constitutively activated during inflammation. We previously reported that high-fat diet (HFD) intake induces oxidative stress in the prostate through elevated expression of NADPH oxidase subunits causing NF-κB activation. We sought to determine whether Stat-3 is involved in the activation of NF-κB in the prostate as a result of HFD feeding, leading to inflammation.

METHODS

C57BL/6 mice were either fed with regular diet (RD) or HFD for 4 and 8 weeks. Plasma cytokine levels were determined by multiplex analysis. Western blotting was performed to determine the expression of NF-κB, Stat-3, Akt, PDK1, PKCε, and their phosphorylated forms along with pathologic evaluation of the prostate. Immunoprecipitation and electrophoretic mobility shift assay (EMSA) were conducted to study the association between Stat-3 and NF-κB.

RESULTS

C57BL/6 mice fed with HFD showed a significant increase in the plasma levels of IL-1ß, IL-6, IL-17, and TNFα after 4 and 8 weeks of feeding, compared with RD controls. HFD feeding elevated the intraprostatic expression of IL-6 and caused activation of PKCε and Akt, the upstream kinase regulating Stat-3 and NF-κB. Nuclear extracts from the prostates of mice fed with HFD exhibited constitutively activated levels of Stat-3 and NF-κB/p65. Increased association between the activated forms of Stat-3 and NF-κB/p65 was observed in the nucleus as a result of HFD feeding, a finding that was accompanied by morphologic evidence of increased intraprostatic inflammation.

CONCLUSIONS

Our findings suggest that HFD activates Stat-3 and NF-κB/p65 in the prostate, and their interaction is associated with increased inflammation in the prostate.

Abstract 5576: Rhamnetin inhibits human prostate cancer cell growth through cell-cycle arrest by modulating expression and function of key cell-cycle regulators and survival molecules

Development of effective agents for treatment of prostate cancer has become a national medical priority. Rhamnetin (3,5,3,4-tetrahydroxy-7-methoxyflavone), a natural compound known as O-methylated flavonol, abundantly present in cloves, sweet annie, annual wormwood, green vegetables and orchard grass has shown to possess anti-inflammatory and antioxidant properties. However, the anticancer properties of rhamnetin have not been fully elucidated. In the present study we demonstrated the molecular mechanism of cell growth inhibition and induction of apoptosis in human prostate carcinoma LNCaP and PC-3 cells by rhamnetin. Treatment of these cells with rhamnetin resulted in a dose (5, 10, 20, 40 microM) and time (24, 48 and 72 h) dependent inhibition of growth, G2-S phase arrest of the cell cycle and DNA fragmentation. This effect was associated with a marked decrease in the protein expression of cyclin D1, D2, and E and their activating partner, cyclin-dependent kinase (cdk) 2, 4, and 6, with concomitant upregulation of WAF1/p21, KIP1/p27, INK4a/p16, and INK4c/p18. Rhamnetin treatment also resulted in alteration in Bax/Bcl2 ratio in favor of apoptosis, which was associated with the release of cytochrome-c and induction of apoptotic protease-activating factor-1 (Apaf-1). This effect was found to result in a significant increase in cleaved fragments of caspase-9, -3, and poly (ADP-ribose) polymerase (PARP). Further, rhamnetin treatment resulted in down modulation of XIAP, survivin, and c-Myc protein expressions. Taken together, we concluded that molecular mechanisms during rhamnetin-mediated growth inhibition and induction of apoptosis in both androgen-responsive, LNCaP and androgen-refractory, PC-3 cells was due to modulation in cell-cycle machinery, disruption of mitochondrial function, and inhibition of cell survival machinery. For the first time we provide evidence that rhamnetin acts on potential molecular targets of cell cycle regulation and survival to elicit anticancer effects in prostate cancer cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5576. doi:10.1158/1538-7445.AM2011-5576

Abstract 4626: Chamomile confers protection against hydrogen peroxide-induced toxicity through activation of Nrf2-mediated defense response

Cellular damage by reactive oxygen species (ROS) causes aging and remains major factor in the development of various human diseases including diabetes, liver diseases, neurodegenerative and cardiovascular diseases, including cancer. Dietary antioxidants have been considered as an attractive strategy to prevent or attenuate the progression of diseases caused by oxidative stress. Induction of phase 2 detoxifying enzymes in response to naturally occurring agents provides an effective means of protection against oxidative stress. Aqueous extract of chamomile (Matricaria chamomilla) in the form of tea has been used for centuries to treat various inflammatory conditions supporting its traditional use for treating various human ailments. We used aqueous chamomile extract obtained from dried flowers to investigate its effect on Nrf2 activation and induction of phase 2 enzymes in RAW 264.7 murine macrophages and H2O2 as an agent for oxidative stress. Treatment with 50 µM H2O2 for 6 h caused significant increase in cellular stress accompanied by cell death in RAW 264.7 murine macrophages as evident from light microscopy and annexin-V FITC assay. Pre-treatment with chamomile at 10, 20 and 40 µg for 16 h followed by H2O2 treatment protected cell death caused by excessive ROS generation and prevented H2O2-mediated inhibition of cell growth. Chamomile exposure significantly increased the expression of antioxidant enzymes viz. peroxiredoxin (Prx), thioredoxin (Trx) and heme oxygenase (HO-1) in a dose-dependent manner, compared with their respective controls. Furthermore, chamomile exposure to RAW 264.7 murine macrophages increased the nuclear translocation of Nrf2 with increased phosphorylated Nrf2 levels, and it's binding to the antioxidant response element (ARE) in the nucleus. These data provide evidence that chamomile induces the expression of cytoprotective antioxidant enzyme (HO-1) and other redox regulatory enzymes (Prx and Trx) in response to the nuclear translocation of a key redox sensitive transcription factor Nrf2 from the cytoplasm and provide protection from cytotoxicity caused by inflammatory oxidants. Understanding chamomile-mediated molecular events could play a potentially important role in setting up strategies for prevention and treatment of various human diseases including cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4626. doi:10.1158/1538-7445.AM2011-4626

Abstract 5584: Green tea polyphenols inhibit histone deacetylases and modulate p53 transcriptional activities in human prostate cancer cells

Inhibitors of histone deacetylases (HDACs) are emerging as a promising class of anticancer drugs. HDAC inhibitors have been demonstrated to induce cellular activities similar to p53-mediated responses such as induction of cell cycle arrest and apoptosis in various malignant cells. Green tea polyphenols (GTP) have shown protective effects against development and progression of various human cancers. GTP-mediated cellular responses include p53 activation, cell cycle arrest and induction of apoptosis in cancer cells. In the present study, we sought to determine whether GTP-mediated cellular responses are similar to that elicited by HDAC inhibitors. For these studies, we used human prostate cancer LNCaP cells, possessing wild-type p53, infected with short hairpin (sh) RNA vector and sh-p53 RNA vector to generate isogenic cell lines. Knockdown of p53 in LNCaP cells caused an increase in the activity of class I HDACs with specific increase in the protein expression of HDAC viz. 1 and 8, respectively. Treatment of both cell lines with 20, 40 and 80 mcg/mL doses of GTP for 24 h resulted in dose-dependent decrease in the total HDAC activity and protein expression of HDAC 2, 3 and 8 and HDAC 1, albeit at highest GTP dose. Similar dose-dependent responses were achieved by trichostatin A (TSA), a well known pharmacological inhibitor of class I and II HDACs in these cells. Interestingly, chemosensitization by GTP was more pronounced in the cells expressing p53 than the isogenic cell lines lacking p53 as observed by cell cycle analysis and annexin V flow cytometric analysis. Furthermore, GTP treatment resulted in marked increase in acetylation of p53 at its C-terminal amino acid positions K373 and K382, other than K305 along with increase in the acetylated forms of histone H3 and H4 which correlated with increased p53 expression, cell cycle arrest and apoptosis. Taken together, these results suggest that interaction of HDACs with p53 probably results in p53 deacetylation, thereby reducing the transcriptional activity; whereas GTP has the ability to cause deacetylation of p53 by reducing the levels of class I HDACs. This seems likely to be, in part, the mechanism for GTP-mediated p53 activation, a similar response elicited by HDAC inhibitors, which are developed as a promising class of drugs for the treatment of various human malignancies.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5584. doi:10.1158/1538-7445.AM2011-5584

Chamomile: an anti-inflammatory agent inhibits inducible nitric oxide synthase expression by blocking RelA/p65 activity

Chamomile has long been used in traditional medicine for the treatment of inflammation-related disorders. In this study we investigated the inhibitory effects of chamomile on nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression, and explored its potential anti-inflammatory mechanisms using RAW 264.7 macrophages. Chamomile treatment inhibited LPS-induced NO production and significantly blocked IL-1β, IL-6 and TNFα-induced NO levels in RAW 264.7 macrophages. Chamomile caused reduction in LPS-induced iNOS mRNA and protein expression. In RAW 264.7 macrophages, LPS-induced DNA binding activity of RelA/p65 was significantly inhibited by chamomile, an effect that was mediated through the inhibition of IKKβ, the upstream kinase regulating NF-κB/Rel activity, and degradation of inhibitory factor-κB. These results demonstrate that chamomile inhibits NO production and iNOS gene expression by inhibiting RelA/p65 activation and supports the utilization of chamomile as an effective anti-inflammatory agent.

Abstract 1899: Induction of phase 2 antioxidant genes by the aqueous extract of Matricaria chamomilla (Chamomile) through Keap1-Nrf2 signaling pathway

Induction of phase 2 detoxifying enzymes in response to naturally occurring agents provides an effective means of protection against oxidative stress. Increasing lines of evidence show that the Keap1-Nrf2 complex is a key molecular target of phase 2 enzyme inducers. The transcription factor Nrf2 is a member of basic leucine-zipper NF-E2 family and interacts with the antioxidant response element (ARE) in the promoter region of phase 2 detoxifying enzymes. A cytoplasmic actin-binding protein, Keap1, is an inhibitor of Nrf2 and sequesters it in the cytoplasm. Various extracellular stimuli and inducers dissociate this complex, allowing Nrf2 to translocate into the nucleus, binding with ARE and induce the expression of various antioxidant genes. Recently natural compounds have been established as activators of phase 2 antioxidant enzymes through Nrf2 signaling pathway. We used aqueous chamomile extract obtained from dried flowers to investigate its effect on Nrf2 activation and induction of phase 2 enzymes in human prostate cancer PC-3 and LNCaP cells. Treatment of these cells with chamomile at 1-40μM concentration equivalent to aglycone apigenin caused significant dissociation of Keap1 from the Keap1-Nrf2 complex with significant decrease of Keap1 in the cytoplasm in dose- and time- dependent fashion. Similarly, a marked decrease in Nrf2 was observed in the cytoplasm after chamomile treatment. Chamomile treatment further led to increase in phase 2 enzymes including superoxide dismutase, NAD(P)H dehydrogenase [quinone] 1 and catalase in these cells which correlated with nuclear Nrf2 expression in dose- and time- dependent manner. Taken together, these molecular evidences provide an insight into the mechanism underlying the induction of phase 2 enzymes through Keap1- Nrf2 signaling pathway by chamomile, endorsing its antioxidant function.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1899.

Anti-ulcer and antioxidant activity of GutGard

The present study was undertaken to determine the anti-ulcer and antioxidant potential of GutGard, a standardized extract of Glycyrrhiza glabra commonly known as licorice. Effect of various doses (12.5, 25, and 50 mg/kg, po) of GutGard was studied on gastric ulcers in pylorus ligation-, cold-restraint stress- and indomethacin induced gastric mucosal injury in rats. Anti-ulcer activity was evaluated by measuring the ulcer index, gastric content, total acidity, and pH of gastric fluid. GutGard dose dependently decreased gastric content, total acidity, ulcer index and increased pH of gastric fluid in pylorus ligation ulcer model. In cold-restraint stress- and indomethacin induced ulcer models all the doses of GutGard decreased the ulcer index and increased the pH of gastric fluid. The antioxidant activity was evaluated by the oxygen radical absorbance capacity (ORAC) assay. GutGardT exhibited potent antioxidant activity with high hydrophilic and lipophilic ORAC value. GutGard possessed anti-ulcerogenic properties that might be afforded via cytoprotective mechanism by virtue of its antioxidant properties. These results supported the ethnomedical uses of licorice in the treatment of gastric ulcer.

Response of tertiary centres to pressure changes. Is there a mechano-electrical association?

Inactivation of the tumor suppressor gene p53 is commonly observed in human prostate cancer and is associated with therapeutic resistance. We have previously demonstrated that green tea polyphenols (GTP) induce apoptosis in prostate cancer cells irrespective of p53 status. However, the molecular mechanisms underlying these observations remain elusive. Here we investigated the mechanisms of GTP-induced apoptosis in human prostate cancer LNCaP cells stably-transfected with short hairpin-RNA against p53 (LNCaPshp53) and control vector (LNCaPshV). GTP treatment induced p53 stabilization and activation of downstream targets p21/waf1 and Bax in a dose-dependent manner specifically in LNCaPshV cells. However, GTP-induced FAS upregulation through activation of c-jun-N-terminal kinase resulted in FADD phosphorylation, caspase-8 activation and truncation of BID, leading to apoptosis in both LNCaPshV and LNCaPshp53 cells. In parallel, treatment of cells with GTP resulted in inhibition of survival pathway, mediated by Akt deactivation and loss of BAD phosphorylation more prominently in LNCaPshp53 cells. These distinct routes of cell death converged to a common pathway, leading to loss of mitochondrial transmembrane potential, cytochrome c release and activation of terminal caspases, resulting in PARP-cleavage. GTP-induced apoptosis was attenuated with JNK inhibitor, SP600125 in both cell lines; whereas PI3K-Akt inhibitor, LY294002 resulted in increased cell death prominently in LNCaPshp53 cells, establishing the role of two distinct pathways of GTP-mediated apoptosis. Furthermore, GTP exposure resulted in inhibition of class I HDAC protein, accumulation of acetylated histone-H3 in total cellular chromatin, resulting in increased accessibility of transcription factors to bind with the promoter sequences of p21/waf1 and Bax, regardless of the p53 status of cells, consistent with effects elicited by an HDAC inhibitor, trichostatin A. These results demonstrate that GTP induces prostate cancer cell death by two distinct mechanisms regardless of p53 status, thus identifying specific well-defined molecular mechanisms that may be targeted by chemopreventive and/or therapeutic strategies.