The immunomodulatory, antitumor and antimetastatic responses of melanoma-bearing normal and alcoholic mice to sunitinib and ALT-803: a combinatorial treatment approach

ALT-803, a novel IL-15/IL-15 receptor alpha complex, and the tyrosine kinase inhibitor, sunitinib, were examined for their single and combined effects on the growth of subcutaneous B16BL6 melanoma and on lymph node and lung metastasis. The study was conducted in immunocompetent C57BL/6 mice drinking water (Water mice) and in mice that chronically consumed alcohol (Alcohol mice), which are deficient in CD8(+) T cells. Sunitinib inhibited melanoma growth and was more effective in Alcohol mice. ALT-803 did not alter tumor growth or survival in Water or Alcohol mice. Combined ALT-803 and sunitinib inhibited melanoma growth and increased survival, and these effects were greater than sunitinib alone in Water mice. ALT-803 and alcohol independently suppressed lymph node and lung metastasis, whereas sunitinib alone or in combination with ALT-803 increased lymph node and lung metastasis in Water and Alcohol mice. Initially, ALT-803 increased IFN-γ-producing CD8(+)CD44(hi) memory T cells and CD8(+)CD44(hi)CD62L(lo) effector memory T cells and sunitinib decreased immunosuppressive MDSC and T regulatory cells (Treg). However, the impact of these treatments diminished with time. Subcutaneous tumors from Water mice showed increased numbers of CD8(+) T cells, CD8(+)CD44(hi) T cells, NK cells, and MDSC cells and decreased Treg cells after ALT-803 treatment.

Abstract 1345: Antitumor and antimetastatic response of melanoma-bearing normal and alcoholic mice to Sunitinib and ALT-803 treatment

Chronic alcohol consumption (CAC) is a risk factor for melanoma as well as other cancers and can result in decreased patient survival. We previously showed that CAC increases the percentage of IFN-γ-producing CD8+ T cells exhibiting a memory phenotype (CD44hi) in the early stage of primary B16BL6 melanoma development; however, these cells rapidly decrease with continued tumor growth. CAC also results in decreased cells producing IL-15, a cytokine essential for sustained proliferation and survival of CD8+ T cells. In addition, myeloid derived suppressor cells (MDSC), which can inhibit CD8+ T cell proliferation and activation and thus suppress antitumor immune responses, also increase in the blood of melanoma-bearing mice during CAC. Herein, we examined the single and combined effects of ALT-803, a novel IL-15/IL-15 receptor alpha complex designed to increase CD8+ T cell proliferation and activation and Sunitinib, known to inhibit MDSC, on primary melanoma growth and metastasis in female C57BL/6 mice inoculated s.c. with B16BL6 melanoma and given continuous water or 20% w/v alcohol. Both drugs are being evaluated separately in human melanoma clinical trials. ALT-803 did not inhibit primary tumor growth or increase survival when given weekly at a dose of 0.2 mg/kg but did inhibit tumor growth and increase survival at a dosage of 1.5-2.0 mg/kg. Sunitinib (40 mg/kg daily) given alone and in combination with ALT-803 inhibited tumor growth compared to untreated water and alcohol controls. Sunitinib had a greater effect on tumor growth and final tumor weight in alcohol drinking mice compared to water drinking mice. Sunitinib increased survival and in combination with ALT-803 extended survival further. MDSC, which increased with tumor growth in untreated mice, were initially suppressed by Sunitinib; however, continued tumor growth overcame the initial suppressive effect. ALT-803 increased levels of CD8+ T cells, CD8+CD44hi T cells, and IFN-γ-producing CD8+ T cells. This effect decreased with continued tumor growth. ALT-803 inhibited and Sunitinib increased lymph node and lung metastasis in mice inoculated s.c. with melanoma. The Sunitinib effect on metastasis was not abrogated in combination with ALT-803. Further studies to investigate the mechanisms associated with these findings are warranted. Supported by NIH Grants K05AA017149 and R21AA022098 to GGM and HZ and NSF pre-doctoral fellowship DGE-1347973 to KAG.

Citation Format: Kari A. Gaither, Alexander A. Little, Alisha A. McBride, Savanna Castillo, Kiran K. Brar, Amity Platt, Zhaohui Zhu, Faya Zhang, Dung Luong, Hui Zhang, Gary G. Meadows. Antitumor and antimetastatic response of melanoma-bearing normal and alcoholic mice to Sunitinib and ALT-803 treatment. [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 1345. doi:10.1158/1538-7445.AM2015-1345

Chronic alcohol consumption inhibits melanoma growth but decreases the survival of mice immunized with tumor cell lysate and boosted with α-galactosylceramide

Alcohol consumption increases the incidence of multiple types of cancer. However, how chronic alcohol consumption affects tumor progression and host survival remains largely unexplored. Using a mouse B16BL6 melanoma model, we studied the effects of chronic alcohol consumption on s.c. tumor growth, iNKT cell antitumor immune response, and host survival. The results indicate that although chronic alcohol consumption inhibits melanoma growth, this does not translate into increased host survival. Immunizing mice with a melanoma cell lysate does not significantly increase the median survival of water-drinking, melanoma-bearing mice, but significantly increases the median survival of alcohol-consuming, melanoma-bearing mice. Even though survival is extended in the alcohol-consuming mice after immunization, the median survival is not different from the immunized mice in the water-drinking group. Immunization with tumor cell lysate combined with α-galatosylceramide activation of iNKT cells significantly increases host survival of both groups of melanoma-bearing mice compared to their respective non-immunized counterparts; however, the median survival of the alcohol-consuming group is significantly lower than that of the water-drinking group. Alcohol consumption increases NKT cells in the thymus and blood and skews NKT cell cytokine profile from Th1 dominant to Th2 dominant in the tumor-bearing mice. In summary, these results indicate that chronic alcohol consumption activates the immune system, which leads to the inhibition of s.c. melanoma growth and enhances the immune response to immunization with melanoma lysate. With tumor progression, alcohol consumption accelerates iNKT cell dysfunction and compromises antitumor immunity, which leads to decreased survival of melanoma-bearing mice.

Chronic alcohol consumption enhances iNKT cell maturation and activation

Alcohol consumption exhibits diverse effects on different types of immune cells. NKT cells are a unique T cell population and play important immunoregulatory roles in different types of immune responses. The effects of chronic alcohol consumption on NKT cells remain to be elucidated. Using a mouse model of chronic alcohol consumption, we found that alcohol increases the percentage of NKT cells, especially iNKT cells in the thymus and liver, but not in the spleen or blood. Alcohol consumption decreases the percentage of NK1.1(-) iNKT cells in the total iNKT cell population in all of the tissues and organs examined. In the thymus, alcohol consumption increases the number of NK1.1(+)CD44(hi) mature iNKT cells but does not alter the number of NK1.1(-) immature iNKT cells. A BrdU incorporation assay shows that alcohol consumption increases the proliferation of thymic NK1.1(-) iNKT cells, especially the NK1.1(-)CD44(lo) Stage I iNKT cells. The percentage of NKG2A(+) iNKT cells increases in all of the tissues and organs examined; whereas CXCR3(+) iNKT cells only increases in the thymus of alcohol-consuming mice. Chronic alcohol consumption increases the percentage of IFN-γ-producing iNKT cells and increases the blood concentration of IFN-γ and IL-12 after in vivo α-galactosylceramide (αGalCer) stimulation. Consistent with the increased cytokine production, the in vivo activation of iNKT cells also enhances the activation of dendritic cells (DC) and NK, B, and T cells in the alcohol-consuming mice. Taken together the data indicate that chronic alcohol consumption enhances iNKT cell maturation and activation, which favors the Th1 immune response.

Abstract 3660: Chronic alcohol consumption inhibits iNKT cell activation-induced antitumor response in B16BL6 melanoma-bearing mice

Alcohol consumption increases the incidence of many types of cancer including melanoma. It is not well understand how chronic alcohol consumption affects tumor progression and survival. We previously found that chronic alcohol consumption activates CD8+ T cells in the non-tumor injected mice and at the early stage after tumor inoculation; however, it accelerates CD8+T cell dysfunction during further tumor growth. The underlying mechanism regarding modulation of CD8+ T cells by alcohol and how the functional changes in the immune response affect tumor growth and survival remain to be elucidated. Herein, we investigated how alcohol modulates iNKT cells in melanoma-bearing mice and how different immune treatment regimens affect tumor growth and survival. We found that alcohol increases iNKT cells in non-tumor injected mice, and that activation of these iNKT cells induces a Th1 response. With tumor progression, alcohol reverses iNKT cell cytokine profile to aTh2-dominant one. Chronic alcohol consumption inhibits melanoma growth, but this is does associated with increased survival. Immunization with a melanoma cell lysate significantly inhibits tumor growth and increases survival compared to the non-immunized alcohol-consuming, tumor-bearing mice. Immunization in the water-drinking control mice did not significantly increase survival compared to respective non-immunized mice. Immunization coupled with iNKT cell activation with alpha GalCer significantly increases the survival of water-drinking melanoma-bearing mice. However, the survival of mice consuming alcohol was significantly decreased compared to their water-drinking counterparts. Collectively, chronic alcohol consumption interacting with melanoma alters the iNKT cell cytokine profile from Th1-dominant to Th2- dominant, which in turn contributes to inhibition of antitumor immunity and decreases survival of melanoma-bearing mice. Supported by NIH grants R01AA07293 and K05AA017149 and funds provided for medical and biological research by the State of Washington Initiative Measure No. 171.

Citation Format: Hui Zhang, Faya Zhang, ZhaoHui Zhu, Gary G. Meadows. Chronic alcohol consumption inhibits iNKT cell activation-induced antitumor response in B16BL6 melanoma-bearing mice. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3660. doi:10.1158/1538-7445.AM2014-3660

A novel approach to identify driver genes involved in androgen-independent prostate cancer

BACKGROUND

Insertional mutagenesis screens have been used with great success to identify oncogenes and tumor suppressor genes. Typically, these screens use gammaretroviruses (γRV) or transposons as insertional mutagens. However, insertional mutations from replication-competent γRVs or transposons that occur later during oncogenesis can produce passenger mutations that do not drive cancer progression. Here, we utilized a replication-incompetent lentiviral vector (LV) to perform an insertional mutagenesis screen to identify genes in the progression to androgen-independent prostate cancer (AIPC).

METHODS

Prostate cancer cells were mutagenized with a LV to enrich for clones with a selective advantage in an androgen-deficient environment provided by a dysregulated gene(s) near the vector integration site. We performed our screen using an in vitro AIPC model and also an in vivo xenotransplant model for AIPC. Our approach identified proviral integration sites utilizing a shuttle vector that allows for rapid rescue of plasmids in E. coli that contain LV long terminal repeat (LTR)-chromosome junctions. This shuttle vector approach does not require PCR amplification and has several advantages over PCR-based techniques.

RESULTS

Proviral integrations were enriched near prostate cancer susceptibility loci in cells grown in androgen-deficient medium (p < 0.001), and five candidate genes that influence AIPC were identified; ATPAF1, GCOM1, MEX3D, PTRF, and TRPM4. Additionally, we showed that RNAi knockdown of ATPAF1 significantly reduces growth (p < 0.05) in androgen-deficient conditions.

CONCLUSIONS

Our approach has proven effective for use in PCa, identifying a known prostate cancer gene, PTRF, and also several genes not previously associated with prostate cancer. The replication-incompetent shuttle vector approach has broad potential applications for cancer gene discovery, and for interrogating diverse biological and disease processes.

Synthesis and anticancer activity of new flavonoid analogs and inconsistencies in assays related to proliferation and viability measurements

Flavonoids have been studied intensely for their ability to act as anti-carcinogenic, anti-inflammatory, anti-viral and anti-aging agents and are often marketed as supplements related to their anti-inflammatory activity. Previous studies have primarily focused on the effects of polar natural flavonoids. We examined the activity of novel hydrophobic and lipophilic flavonols against human DU-145 and PC-3 prostate cancer cell lines. All flavonol analogs were more active than the naturally occurring flavonols quercetin, kaempferol, kaempferide and galangin. The most potent analogs were 6.5-fold more active against DU-145 and PC-3 cells than quercetin and fell within the biologically relevant concentration range (low micromolar). We also evaluated the potential toxic effects of flavonol analogs on normal cells, an assessment that has frequently been ignored when studying the anticancer effects of flavonoids. During these analyses, we discovered that various metabolic and DNA staining assays were unreliable methods for assessing cell viability of flavonoids. Flavonoids reduce colorimetric dyes such as MTT and Alamar Blue in the absence of cells. We showed that flavonol-treated prostate cancer cells were stained less intensely with crystal violet than untreated cells at non-toxic concentrations. The trypan blue exclusion assay was selected as a reliable alternative for measuring cell viability.

Abstract 4716: Chronic alcohol consumption activates the LiTAF pathway in melanoma-bearing mice

We previously reported that chronic alcohol consumption increases myeloid-derived suppressor cells (MDSC) and compromises melanoma-specific CD8+ T cells in B16BL6 melanoma-bearing mice; however, the underlying mechanism has not been elucidated. Activation of LPS-induced TNF-α factor (LiTAF) gene leads to up-regulation in the expression of various cytokines, chemokines and growth factors such as TNF-α, IL-1β, and VEGF, which are inducers of MDSC. Alcohol consumption is associated with the leakage of LPS into the blood. However, it is not known whether alcohol consumption modulates the expression of LiTAF. Herein, we examined the effects of alcohol and subcutaneous inoculation of melanoma in mice on the expression of LiTAF and its downstream cytokines, chemokines and growth factors. Female C57BL/6 mice were given 20% (w/v) alcohol for three to six months followed by subcutaneous inoculation of 2x105 B16BL6 melanoma cells. Two weeks after tumor inoculation, the expression of LiTAF and related cytokine genes in the spleen were examined by RT-PCR. Chronic alcohol consumption dramatically up regulated the expression of LiTAF in the spleen of melanoma-bearing mice; however, expression was almost undetectable in the spleen of corresponding water-drinking mice. The expression of IL-1β, IL-10, TNF-α, CCL5, and VEGF-β was also significantly up regulated by alcohol. These results indicate that chronic alcohol consumption activates the LiTAF pathway and up regulates the expression of the downstream cytokines, chemokines and growth factors. The up regulation of these cytokines could contribute to the induction of MDSC and inhibition on CD8+ T cells.

(Supported by funds received from the Summer Undergraduate Research Fellowship (SURF) Program, from NIH grants R01 AA07193 and K05AA017149, and from funds provided for medical and biological research by the State of Washington Initiative Measure No. 171).

Citation Format: Andrew Marron, Hui Zhang, Zhaohui Zhu, Gary G. Meadows. Chronic alcohol consumption activates the LiTAF pathway in melanoma-bearing mice. [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 4716. doi:10.1158/1538-7445.AM2013-4716

Amelioration of behavioral abnormalities in BH(4)-deficient mice by dietary supplementation of tyrosine

This study reports an amelioration of abnormal motor behaviors in tetrahydrobiopterin (BH4)-deficient Spr (-/-) mice by the dietary supplementation of tyrosine. Since BH4 is an essential cofactor for the conversion of phenylalanine into tyrosine as well as the synthesis of dopamine neurotransmitter within the central nervous system, the levels of tyrosine and dopamine were severely reduced in brains of BH4-deficient Spr (-/-) mice. We found that Spr (-/-) mice display variable 'open-field' behaviors, impaired motor functions on the 'rotating rod', and dystonic 'hind-limb clasping'. In this study, we report that these aberrant motor deficits displayed by Spr (-/-) mice were ameliorated by the therapeutic tyrosine diet for 10 days. This study also suggests that dopamine deficiency in brains of Spr (-/-) mice may not be the biological feature of aberrant motor behaviors associated with BH4 deficiency. Brain levels of dopamine (DA) and its metabolites in Spr (-/-) mice were not substantially increased by the dietary tyrosine therapy. However, we found that mTORC1 activity severely suppressed in brains of Spr (-/-) mice fed a normal diet was restored 10 days after feeding the mice the tyrosine diet. The present study proposes that brain mTORC1 signaling pathway is one of the potential targets in understanding abnormal motor behaviors associated with BH4-deficiency.

Establishment of an immunodeficient alcohol mouse model to study the effects of alcohol on human cells in vivo

OBJECTIVE

The effects of alcohol (ethanol) are well documented and contribute to significant health problems and financial burden on the health care system. Several mouse models have been described that facilitate studies of the effects of alcohol on the mouse immune system. Our goal was to establish a chronic alcohol mouse model using the immunodeficient NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mouse. This severely immunodeficient model has previously been shown to allow efficient engraftment of human hematopoietic repopulating cells and cancer cells, thereby facilitating diverse studies on human hematopoiesis, immune cell function, and oncogenesis in vivo.

METHOD

NSG mice were provided ethanol in their drinking water as the only available fluid, starting at 5% weight/volume (w/v) and subsequently were increased to 10%, 15%, and 20% w/v. Mice were then maintained at 20% w/v, a level that models chronic alcohol use in humans. Alcohol consumption and weight were monitored.

RESULTS

NSG mice readily consumed alcohol throughout the study and showed no adverse effects. No significant difference between group mean weights was identified the day before increasing the ethanol dose or at the end of 5 weeks at 20% w/v (p > .28). While the mice were maintained at 20% w/v ethanol, the mean daily ethanol intake was 27.2 g/kg of body weight, 32% of caloric intake.

CONCLUSIONS

Here we have established a chronic alcohol mouse model using the powerful immunodeficient NSG mouse. This model should allow for novel studies on the effects of alcohol on engrafted human cells, including studies on the effects of alcohol on hematopoiesis, immunity, and cancer.

Chronic alcohol consumption impairs distribution and compromises circulation of B cells in B16BL6 melanoma-bearing mice

Accumulating research indicates that B cells are involved in anti-tumor immunity. Chronic alcohol consumption is associated with decreased survival of cancer patients. The effect of alcohol consumption on B cells in tumor-bearing hosts is unknown. Results in melanoma-bearing mice showed that chronic alcohol consumption did not alter the percentage and number of B cells in bone marrow, spleen, and lymph nodes but dramatically decreased B cells in the peripheral blood. Alcohol consumption did not alter the development of B cells in the bone marrow and did not affect follicular B cells in the spleen; however, it increased T1 B cells and decreased marginal zone B cells in the spleen. Alcohol consumption also decreased mature B cells in the blood. It did not alter the chemotactic capacity of plasma to facilitate migration of splenocytes or the chemotactic response of splenocytes to CXCL13 and CCL21. However, the response of splenocytes to sphingosine-1-phosphate was impaired in alcohol-consuming, melanoma-bearing mice. The expression of sphingosine-1-phosphate receptor-1 (S1PR1) and sphingosine-1-phosphate lyase-1 (SPL1) in splenocytes was downregulated. Taken together, these results indicate that chronic alcohol consumption decreases peripheral blood B cells by compromising B cell egress from the spleen. The downregulation of S1PR1 and SPL1 expression in alcohol-consuming, melanoma-bearing mice could be associated with compromised egress of B cells from the spleen.

Abstract 314: The interaction between chronic alcohol consumption and melanoma skews the iNKT cell cytokine profile towards IL-4 dominance

Despite the growing evidence that alcohol consumption is associated with the incidence of many different types of cancer, there is little research regarding the effect of continued alcohol consumption on growth, progression and subsequent survival of cancer patients. Using a well-established mouse model we previously found that chronic alcohol consumption impairs the anti-melanoma functions of CD8+T cells and NK cells, and this leads to decreased survival of melanoma-bearing mice. The underlying mechanism for these effects is not known. Herein we examined the relationship of NKT cells to regulation of anti-tumor responses in alcohol consuming mice since NKT cells play important roles in the regulation of the anti-tumor immune response. The phenotype and function of invariant (i)NKT cells were examined in female B16BL6-bearing C57BL6 mice given 20% alcohol for three months. We found that alcohol consumption increased iNKT cells in the liver of mice not inoculated with melanoma, but did not alter iNKT cells in other organs. iNKT cells were dramatically increased in the blood and liver of chronic alcohol consuming, melanoma-bearing mice; however, these cells were not increased in the spleen or draining lymph nodes. Immature NK1.1- iNKT cells decreased 2-4 fold in the blood, spleen and liver of the alcohol-consuming, melanoma-bearing mice, suggesting that alcohol interacting with the melanoma tumors stimulates iNKT cells maturation. Upon activation, fewer iNKT cells produced IFN-gamma in these mice compared to water-drinking, melanoma-bearing mice. The ratio of IL-4:IFN-gamma-producing iNKT cells increased 2-fold as a result of the alcohol/tumor interaction, thus skewing the cytokine profile toward Th2 dominance. The Th2 dominant cytokine profile could negatively regulate the anti-tumor activities of CD8+ T cell and NK cells as well as increase myeloid derived suppressor cells, which we previously reported. Collectively, these data support an important role for iNKT cells in regulation of melanoma progression. (Supported by NIH grants R01AA07293 and K05AA017149, and WSU Alcohol and Drug Abuse Research Program grant 13B-2957-1246).

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 314. doi:1538-7445.AM2012-314

Prenatal alcohol exposure alters the course and severity of adjuvant-induced arthritis in female rats

Prenatal alcohol exposure (PAE) has adverse effects on the development of numerous physiological systems, including the hypothalamic-pituitary-adrenal (HPA) axis and the immune system. HPA hyper-responsiveness and impairments in immune competence have been demonstrated. The present study investigated immune function in PAE females utilizing an adjuvant-induced arthritis (AA) model, widely used as a model of human rheumatoid arthritis. Given the effects of PAE on HPA and immune function, and the known interaction between HPA and immune systems in arthritis, we hypothesized that PAE females would have heightened autoimmune responses, resulting in increased severity of arthritis, compared to controls, and that altered HPA activity might play a role in the immune system changes observed. The data demonstrate, for the first time, an adverse effect of PAE on the course and severity of AA in adulthood, indicating an important long-term alteration in functional immune status. Although overall, across prenatal treatments, adjuvant-injected animals gained less weight, and exhibited decreased thymus and increased adrenal weights, and increased basal levels of corticosterone and adrenocorticotropin, PAE females had a more prolonged course of disease and greater severity of inflammation compared to controls. In addition, PAE females exhibited blunted lymphocyte proliferative responses to concanavalin A and a greater increase in basal ACTH levels compared to controls during the induction phase, before any clinical signs of disease were apparent. These data suggest that prenatal alcohol exposure has both direct and indirect effects on inflammatory processes, altering both immune and HPA function, and likely, the normal interactions between these systems.

Activation of the aryl hydrocarbon receptor by TCDD inhibits mammary tumor metastasis in a syngeneic mouse model of breast cancer

Treatment with aryl hydrocarbon receptor (AhR) agonists can slow or reverse the growth of primary mammary tumors in rodents, which has fostered interest in developing selective AhR modulators for treatment of breast cancer. However, the major goal of breast cancer therapy is to inhibit metastasis, the primary cause of mortality in women with this disease. Studies conducted using breast cancer cell lines have demonstrated that AhR agonists suppress proliferation, invasiveness, and colony formation in vitro; however, further exploration using in vivo models of metastasis is warranted. To test the effect of AhR activation on metastasis, 4T1.2 mammary tumor cells were injected into the mammary gland fat pad of syngeneic Balb/c mice treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Primary tumor growth was monitored for 4 weeks, at which time metastasis was determined. TCDD treatment suppressed metastasis by approximately 50%, as measured both in the lung and in mammary glands at sites distant from the primary tumor. Primary tumor growth was not suppressed by TCDD exposure nor was proliferation of 4T1.2 cells affected by TCDD treatment in vitro. Taken together, these results suggest that the protective effect of AhR activation was selective for the metastatic process and not simply the result of a direct decrease in tumor cell proliferation or survival at the primary site. These observations in immunologically intact animals warrant further investigation into the mechanism of the protective effects of AhR activation and support the promise for use of AhR modulators to treat breast cancer.

Autophagy induction by tetrahydrobiopterin deficiency

Tetrahydrobiopterin (BH₄) deficiency is a genetic disorder associated with a variety of metabolic syndromes such as phenylketonuria (PKU). In this article, the signaling pathway by which BH₄ deficiency inactivates mTORC1 leading to the activation of the autophagic pathway was studied utilizing BH₄-deficient Spr(-/-) mice generated by the knockout of the gene encoding sepiapterin reductase (SR) catalyzing BH₄ synthesis. We found that mTORC1 signaling was inactivated and autophagic pathway was activated in tissues from Spr(-/-) mice. This study demonstrates that tyrosine deficiency causes mTORC1 inactivation and subsequent activation of autophagic pathway in Spr(-/-) mice. Therapeutic tyrosine diet completely rescued dwarfism and mTORC1 inhibition but inactivated autophagic pathway in Spr(-/-) mice. Tyrosine-dependent inactivation of mTORC1 was further supported by mTORC1 inactivation in Pah(enu2) mouse model lacking phenylalanine hydroxylase (Pah). NIH3T3 cells grown under the condition of tyrosine restriction exhibited autophagy induction. However, mTORC1 activation by RhebQ64L, a positive regulator of mTORC1, inactivated autophagic pathway in NIH3T3 cells under tyrosine-deficient conditions. In addition, this study first documents mTORC1 inactivation and autophagy induction in PKU patients with BH₄ deficiency.

Abstract 3792: Specific amino acid restriction differentially induces autophagy in DU145 and PC3 human prostate cancer cell lines

We previously found that selective amino acid restriction differentially induces death of DU145 and PC3 human prostate cancer cells. Herein we examined the hypothesis that this differential cell death was associated with induction of autophagy. By detecting the immunofluorescence of microtubule-associated protein 1A/1B light chain 3 (LC3) by confocal microscopy, this study shows that selective amino acid restriction also differentially induces autophagy in DU145 and PC3 human prostate cancer cell lines.

In DU145 cells, restriction of tyrosine and phenylalanine (Tyr/Phe), glutamine (Gln), and methionine (Met) induces autophagy. Addition of pyruvate significantly increases Tyr/Phe restriction-induced autophagy and significantly reduces Met and Gln restriction-induced autophagy. All of the amino acid restrictions induce cell death in DU145 cells. Pyruvate, a major metabolite of glucose metabolism, significantly reduces Tyr/Phe and Gln restriction-mediated cell death, but not Met restriction-medicated cell death.

Tyr/Phe and Gln restriction induces autophagy in PC3 cells. Addition of pyruvate does not alter Tyr/Phe restriction-induced autophagy but significantly increases Met and Gln restriction-induced autophagy. Only Met restriction induces cell death in this cell line, and pyruvate addition reverses this effect.

In summary, the present study indicates 1) cell line specific differences between DU145 and PC3 cells in the induction of autophagy by specific amino acid restriction, 2) lack of association between induction of autophagy and cell death, and 3) differential effects of pyruvate on autophagy and cell death. (This study was supported by grant R01CA101035 from the National Cancer Institute).

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 3792. doi:10.1158/1538-7445.AM2011-3792

Differential effects of specific amino acid restriction on glucose metabolism, reduction/oxidation status and mitochondrial damage in DU145 and PC3 prostate cancer cells

Selective amino acid restriction targets mitochondria to induce apoptosis of DU145 and PC3 prostate cancer cells. Biochemical assays and flow cytometry were uitilized to analyze the glucose consumption, lactate production, pyruvate dehydrogenase (PDH), nicotinamide adenine dinucleotide (NAD)/NADH and nicotinamide adenine dinucleotide phosphate (NADP)/NADPH ratios, mitochondrial glutathione peroxidase (GPx), manganese superoxide dismutase (SOD), glutathione, reactive oxygen species (ROS) and DNA damage in DU145 and PC prostate cancer cells cultured under various amino acid deprived conditions. Restriction of tyrosine and phenylalanine (Tyr/Phe), glutamine (Gln) or methionine (Met) differentially modulated glucose metabolism and PDH and antioxidant enzyme activity in the mitochondria of the two prostate cancer cell lines. In DU145 cells, Gln and Met restriction increased glucose consumption and decreased lactate production, but Tyr/Phe restriction did not. The examined restrictions increased mitochondrial PDH activity and accumulation of ROS. Gln and Met restriction increased GPx activity. Tyr/Phe and Met restriction increased SOD during the first 2 days of the restriction, and the activity returned to the basal level on day 4. All amino acid restrictions decreased reduced glutathione (GSH) and induced mitochondrial DNA damage. In PC3 cells, all amino acid restrictions reduced glucose consumption and lactate production. Gln restriction increased ROS and elevated GPx activity. Tyr/Phe restriction increased SOD activity. The amino acid restriction decreased GSH, but did not cause mitochondrial DNA damage. Specific amino acid dependency differentially regulates glucose metabolism, oxidation-reduction reactions of mitochondria and mitochondrial damage in DU145 and PC3 prostate cancer cell lines.

IFN-γ is essential for the inhibition of B16BL6 melanoma lung metastasis in chronic alcohol drinking mice

We previously found that chronic alcohol consumption (20% w/v in drinking water) that models the level consumed by human alcoholics, when administered to female C57BL/6 mice inhibits B16BL6 melanoma metastasis to the lung; however, the mechanism is not known. Chronic alcohol consumption increases IFN-γ producing NK, NKT, CD4(+), and CD8(+) T cells. To examine the impact of IFN-γ on metastasis, we inoculated B16BL6 melanoma cells i.v. into control and chronic alcohol drinking IFN-γ knockout (KO) mice. Knockout of the ifn-γ gene abrogated the anti-metastatic effects associated with alcohol consumption. We examined metastasis in common gamma-chain (γC) KO mice, which are deficient in NK, NKT and CD8(+) T cells, and in Vα14Jα281(-/-) KO mice, which are deficient in invariant NKT (iNKT) cells, in order to assess the importance of specific IFN-γ producing cell types to this effect. We found that the antimetastatic effect of alcohol was still present in γC KO mice and also in γC KO mice depleted of Gr-1(+) cells. Knockout of iNKT cells reduced the degree but not the antimetastatic effect associated with alcohol. These results indicate that the antimetastatic effect induced by chronic alcohol consumption is IFN-γ dependent and that multiple IFN-γ producing cell types contribute to this effect.

Chronic alcohol consumption decreases the percentage and number of NK cells in the peripheral lymph nodes and exacerbates B16BL6 melanoma metastasis into the draining lymph nodes

NK cells in the lymph nodes play important roles in inhibiting tumor metastasis into draining lymph nodes. Previously, we reported that chronic alcohol consumption interferes with NK cell trafficking from the bone marrow to the spleen. Herein, we found that alcohol consumption decreases the numbers of NK cells in lymph nodes. Adoptive transfer experiments indicated that continued exposure of donor splenocytes to alcohol inhibits NK but not T cell trafficking to lymph nodes. Alcohol did not negatively affect CCR7(+) and CXCR3(+) NK cells, but decreased the percentage and number of CD62L(+) NK cells in the spleen, which are an important source of NK cell trafficking into the lymph nodes. These data suggest that modulation of the microenvironment associated with alcohol consumption impairs the trafficking of NK cells to lymph nodes. The decreased number of NK cells in the lymph nodes was associated with increased melanoma metastasis into the draining lymph nodes.

Laboratory models available to study alcohol-induced organ damage and immune variations: choosing the appropriate model

The morbidity and mortality resulting from alcohol-related diseases globally impose a substantive cost to society. To minimize the financial burden on society and improve the quality of life for individuals suffering from the ill effects of alcohol abuse, substantial research in the alcohol field is focused on understanding the mechanisms by which alcohol-related diseases develop and progress. Since ethical concerns and inherent difficulties limit the amount of alcohol abuse research that can be performed in humans, most studies are performed in laboratory animals. This article summarizes the various laboratory models of alcohol abuse that are currently available and are used to study the mechanisms by which alcohol abuse induces organ damage and immune defects. The strengths and weaknesses of each of the models are discussed. Integrated into the review are the presentations that were made in the symposium "Methods of Ethanol Application in Alcohol Model-How Long is Long Enough" at the joint 2008 Research Society on Alcoholism (RSA) and International Society for Biomedical Research on Alcoholism (ISBRA) meeting, Washington, DC, emphasizing the importance not only of selecting the most appropriate laboratory alcohol model to address the specific goals of a project but also of ensuring that the findings can be extrapolated to alcohol-induced diseases in humans.

Chronic alcohol consumption enhances myeloid-derived suppressor cells in B16BL6 melanoma-bearing mice

We previously found that chronic alcohol consumption decreases the survival of mice bearing subcutaneous B16BL6 melanoma. The underlying mechanism is still not completely understood. Antitumor T cell immune responses are important to inhibiting tumor progression and extending survival. Therefore, we examined the effects of chronic alcohol consumption on the functionality and regulation of these cells in C57BL/6 mice that chronically consumed 20% (w/v) alcohol and subsequently were inoculated subcutaneously with B16BL6 melanoma cells. Chronic alcohol consumption inhibited melanoma-induced memory T cell expansion and accelerated the decay of interferon (IFN)-gamma producing T cells in the tumor-bearing mice. Foxp3(+)CD4(+)CD25(+) regulatory T cells were not affected; however, the percentage of myeloid-derived suppressor cells (MDSC) was significantly increased in the peripheral blood and spleen. T cell proliferation as determined by carboxyfluorescein succinimidyl ester labeling experiments in vitro was inhibited by alcohol consumption relative to control water-drinking melanoma-bearing mice. Collectively, these data show that chronic alcohol consumption inhibits proliferation of memory T cells, accelerates the decay of IFN-gamma producing CD8(+) T cells, and increases MDSC, all of which could be associated with melanoma progression and reduced survival.

Abstract 39: Specific amino acid restriction affects glucose metabolism and induces oxidative damage of mitochondria in prostate cancer cells

The purpose of this study was to examine how specific amino acid restriction targets mitochondria to induce apoptosis in DU145 and PC3 prostate cancer cells. This study shows that restriction of tyrosine and phenylalanine (Tyr/Phe), glutamine (Gln), and methionine (Met) differentially modulates glucose metabolism, the activity of pyruvate dehydrogenase (PDH) and antioxidant status in the mitochondria of these two cell lines. In DU145 cells, Gln and Met restriction but not Tyr/Phe restriction, increase glucose consumption and decrease lactate production. All the examined restrictions increase mitochondrial PDH activity and reactive oxygen species (ROS). Gln and Met restriction increase mitochondrial activity of glutathione peroxidase (GPx). Tyr/Phe and Met restriction increase mitochondrial activity of manganese superoxide dismutase (SOD) in the first 2 days of the restriction, and the activity returns to basal level on day 4 of restriction. Moreover, all the examined restrictions decrease reduced glutathione (GSH) and cause mitochondrial DNA damage. In PC3 cells, all of the examined restrictions reduce glucose consumption and lactate production; however, they do not alter mitochondrial PDH activity. Gln restriction increases accumulation of ROS and elevates mitochondrial GPx activity. Tyr/Phe restriction increases mitochondrial activity of SOD during the entire restriction period. Although all the restrictions decrease GSH in PC3 cells, they do not cause mitochondrial DNA damage. The data indicate that specific amino acid dependency differentially regulates glucose metabolism, oxidation-reduction reactions of mitochondria, and oxidative damage in mitochondria of these two cell lines. This partially explains how selective amino acid restriction targets mitochondria to induce apoptosis. (The project described was supported by Award Number R01CA101035 from the National Cancer Institute. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Cancer Institute or the National Institutes of Health).

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 39.

Chronic alcohol consumption decreases NK cells in the peripheral lymph nodes and exacerbates B16BL6 melanoma metastasis into the draining lymph nodes (40.5)

Chronic alcohol consumption decreases NK cells in the spleen (SP) and compromises their release from the bone marrow (BM). NK cells in the lymph nodes (LN) are important to T cell priming and polarization. Little is known as to how alcohol consumption affects NK cells in the LN. To address this issue, female C57BL/6 mice were given 20% (w/v) alcohol in drinking water for 3-6 months. The percentage, number, phenotype and functions of NK cells in the peripheral LN were studied. Alcohol consumption decreased the percentage and numbers of NK cells in the LN without altering the degree of NK cell apoptosis. Ly49H+, Ly49D+ and Ly49G2+ NK cells also decreased in the LN. The decrease in these cell populations was more pronounced in the SP, and there were no changes in the BM. The results from normal SP cell transfer experiments indicated a time-dependent decrease in accumulation of NK cells into the LN of alcohol consuming as compared to water drinking mice. Alcohol consumption increased the percentage of CXCR3+CD3- and decreased CD62L+CD3-NK cells in the SP and BM. The percentage of CXCR3+CD3+ T cells and CD62L+CD3+ T cells did not change. Consistent with the decrease of NK cells in the LN, alcohol consumption enhanced melanoma metastasis in the draining LN. The results indicate that decreased NK cells in the LN are associated with decreased CD62L+ NK cells in the SP and BM, which impairs NK cell migration to the LN.

Supported by R01 AA07293.

Exogenous IL-15 in combination with IL-15R alpha rescues natural killer cells from apoptosis induced by chronic alcohol consumption

BACKGROUND

Chronic alcohol consumption reduces the percentage and number of peripheral natural killer (NK) cells in mice and in humans. The underlying mechanism for these changes is only partly known. We recently found that chronic alcohol consumption inhibits NK cell release from the bone marrow (BM) and that this is associated with a decrease in splenic NK cells. The number of peripheral NK cells is tightly controlled by homeostatic proliferation. It is not known whether this mechanism is initiated in response to the reduction in splenic NK cells, or if so, why the steady state levels of NK cells are not restored.

METHODS

To examine this mechanism, female C57BL/6 mice were given 20% w/v alcohol in the drinking water for 3 months. NK cell proliferation and apoptosis were determined before and after treatment with IL-15 alone or combined with its alpha receptor.

RESULTS

Chronic alcohol consumption invoked homeostatic proliferation of splenic NK cells in an attempt to return NK cells to normal levels; however, this did not happen due to enhanced apoptosis of NK cells relative to proliferation. Chronic alcohol consumption decreased IL-15 producing cells in the spleen but not in the BM. The numbers of NK cells in the alcohol-consuming mice returned to normal levels in the spleen and were higher than normal in the BM after 2 daily injections of IL-15; however, the enhanced rate of apoptosis due to alcohol consumption was not decreased in the spleen or BM. Combined IL-15 and IL-15R alpha treatment decreased apoptosis of NK cells from alcohol-consuming mice to levels similar to untreated water-drinking mice and greatly increased the percentage and number of NK cells in both the spleen and BM.

CONCLUSION

Chronic alcohol consumption causes a self-unrecoverable loss of NK cells in the spleen by compromising NK cell release from the BM and enhancing splenic NK cell apoptosis that can be reversed with IL-15/IL-15R alpha treatment.

Selective amino acid restriction differentially affects the motility and directionality of DU145 and PC3 prostate cancer cells

We previously found that selective restriction of amino acids inhibits invasion of two androgen-independent human prostate cancer cell lines, DU145 and PC3. Here we show that the restriction of tyrosine (Tyr) and phenylalanine (Phe), methionine (Met) or glutamine (Gln) modulates the activity of G proteins and affects the balance between two actin-binding proteins, cofilin and profilin, in these two cell lines. Selective amino acid restriction differentially reduces G protein binding to GTP in DU145 cells. Tyr/Phe deprivation reduces the amount of Rho-GTP and Rac1-GTP. Met deprivation reduces the amount of Ras-GTP and Rho-GTP, and Gln deprivation decreases Ras-GTP, Rac-GTP, and Cdc42-GTP. Restriction of these amino acids increases the amount of profilin, cofilin and phosphorylation of cofilin-Ser(3). Increased PAK1 expression and phosphorylation of PAK1-Thr(423), and Ser(199/204) are consistent with the increased phosphorylation of LIMK1-Thr(508). In PC3 cells, Tyr/Phe or Gln deprivation reduces the amount of Ras-GTP, and all of the examined amino acid restrictions reduce the amount of profilin. PAK1, LIMK1 and cofilin are not significantly altered. These data reveal that specific amino acid deprivation differentially affects actin dynamics in DU145 and PC3. Modulation on Rho, Rac, PAK1, and LIMK1 likely alter the balance between cofilin and profilin in DU145 cells. In contrast, profilin is inhibited in PC3 cells. These effects modulate directionality and motility to inhibit invasion.

Transferrin reverses the anti-invasive activity of human prostate cancer cells that overexpress sema3E

In vitro invasion and adhesion of stably semaphorin (sema) 3E-transfected PC-3 prostate cancer cells were determined in the presence and absence of transferrin. Invasion and adhesion decreased compared to untransfected cells; however, transferrin reversed the effects. Transferrin differentially regulated E-cadherin and beta-catenin in these cells. Insulin growth factor 3 (IGFBP3) negated the invasive and adhesive effects of transferrin. Transferrin increased binding of insulin growth factor (IGF)-1 to the activated IGF-1 receptor, and IGF-1 mimicked the invasive and adhesive effects of transferrin. These data suggest that transferrin modulates sema3E-transfected cells through an IGFBP3/IGF-1-dependent pathway, in part, by regulation of adhesion proteins.

Chronic alcohol consumption perturbs the balance between thymus-derived and bone marrow-derived natural killer cells in the spleen

Alcohol consumption reduces peripheral NK cell numbers and compromises NK cell cytolytic activity; however, the underlying mechanism is not understood completely. It was found recently that the peripheral NK cell pool consists largely of bone marrow (BM)-derived and thymus-derived cells, which are phenotypically and functionally different. The effects of alcohol consumption on these subpopulations have not been studied previously. Using a well-established alcohol-feeding model, we found that chronic alcohol consumption decreases the percentage and number of peripheral NK cells, especially those expressing a mature phenotype. Alcohol consumption did not alter NK cells in the thymus. NK cells in the BM were increased significantly; however, proliferation rate was not altered by alcohol consumption, which increased CD127+ and decreased Ly49D+ NK cells in the spleen but not in the BM. Chronic alcohol consumption increased IFN-gamma-producing NK cells and GATA-3 expression in splenic NK cells. Collectively, these results indicate that chronic alcohol consumption perturbs the balance between thymus-derived and BM-derived NK cells. The increased proportion of thymus-derived NK cells in the spleen likely results from impaired NK cell release from the BM.

Specific amino acid dependency regulates the cellular behavior of melanoma

Relative specific amino acid dependency is one of the metabolic abnormalities of melanoma cells and metabolic studies of this dependency are in their infancy. Herein, we review the current studies in this area and present new information that adds to the understanding of how tyrosine (Tyr) and phenylalanine (Phe) dependency as well as other amino acids regulate the cell behaviors of melanoma cells. Amino acid dependency of human melanoma cells is multifactorial and restricting Tyr and Phe to melanoma triggers a series of alterations in metabolic and signaling pathways in a time-ordered fashion to alter different cellular behaviors. For example, at early time points, the reduction of Tyr and Phe alters metabolic reactions quantitatively or qualitatively. The alterations include modulation of integrin/focal adhesion kinase (FAK)/G protein pathways and the plasminogen activator (PA)/PA inhibitor pathways to inhibit tumor cell invasion. At later time periods, a further drop in intracellular amino acids induces more metabolic alterations to impact the FAK/Ras/Raf and Bcl-2 pathways leading to apoptosis. The threshold effects and the targeting of multiple pathways by restriction of specific amino acids provide a connection between the metabolic alterations and signaling pathways that modulate the cellular behaviors of melanoma cells. Decoding the metabolic alterations that connect amino acid concentration to the crucial step(s) in signaling is important and an exciting area of cancer research.

Increased class 3 semaphorin expression modulates the invasive and adhesive properties of prostate cancer cells

The class 3 semaphorins, sema3A and sema3C, provide important guidance cues in cell development and in cancer; however, the role of these semaphorins in prostate cancer is not known. We report here that sema3A transfected cells exhibit decreased invasion and adhesion in Matrigel-based assays and that sema3C transfected cells exhibit increased invasive and adhesive characteristics. Important adhesion proteins were differentially modulated in sema3A and sema3C cells in a manner consistent with their subsequent invasive and adhesive characteristics. E-cadherin expression as determined by Western blot analysis was strongly upregulated in sema3A transfected cells, but strongly downregulated in sema3C transfected cells compared to untransfected and mock empty vector-transfected PC-3 cells. beta-catenin levels were not changed in sema3A transfected cells; however, sema3C transfected cells had lower expression of this protein. Sema3C transfected cells exhibited greater cellular membrane expression of certain alpha integrins as compared to untransfected and sema3A transfected cells, a characteristic associated with increased adhesion and invasion. These data indicate that the invasive ability of sema3A and sema3C transfected PC-3 cells is, in part, correlated with adhesion protein expression and adhesive ability to constituents of neighboring cells and the extracellular matrix.

Selective amino acid restriction targets mitochondria to induce apoptosis of androgen-independent prostate cancer cells

Relative specific amino acid dependency is one of the metabolic abnormalities of cancer cells, and restriction of specific amino acids induces apoptosis of prostate cancer cells. This study shows that restriction of tyrosine and phenylalanine (Tyr/Phe), glutamine (Gln), or methionine (Met), modulates Raf and Akt survival pathways and affects the function of mitochondria in DU145 and PC3, in vitro. These three restrictions inhibit energy production (ATP synthesis) and induce generation of reactive oxygen species (ROS). Restriction of Tyr/Phe or Met in DU145 and Met in PC3 reduces mitochondrial membrane potential (DeltaPsim) and induces caspase-dependent and -independent apoptosis. In DU145, Tyr/Phe or Met restriction reduces activity of Akt, mitochondrial distribution of phosphorylated Raf and apoptosis inducing factor (AIF), and increases mitochondrial distribution of Bak. Mitochondrial Bcl-XL is increased in Tyr/Phe-restricted but decreased in Met-restricted cells. Under Tyr/Phe or Met restriction, reduced mitochondrial Raf does not inactivate the pro-apoptotic function of Bak. Tyr/Phe restriction also inhibits Bcl-2 and Met restriction inhibits Bcl-XL in mitochondria. These comprehensive actions damage the integrity of the mitochondria and induce apoptosis of DU145. In PC3, apoptosis induced by Met restriction was not associated with alterations in intracellular distribution of Raf, Bcl-2 family proteins, or AIF. All of the amino acid restrictions inhibited Akt activity in this cell line. We conclude that specific amino acid restriction differentially interferes with homeostasis/balance between the Raf and Akt survival pathways and with the interaction of Raf and Bcl-2 family proteins in mitochondria to induce apoptosis of DU145 and PC3 cells.

Resveratrol is rapidly metabolized in athymic (nu/nu) mice and does not inhibit human melanoma xenograft tumor growth

Resveratrol has been shown to have anticarcinogenic activity. We previously found that resveratrol inhibited growth and induced apoptosis in 2 human melanoma cell lines. In this study we determined whether resveratrol would inhibit human melanoma xenograft growth. Athymic mice received control diets or diets containing 110 micromol/L or 263 micromol/L resveratrol, 2 wk prior to subcutaneous injection of the tumor cells. Tumor growth was measured during a 3-wk period. Metabolism of resveratrol was assayed by bolus gavage of 75 mg/kg resveratrol in tumor-bearing and nontumor-bearing mice. Pellets containing 10-100 mg resveratrol were implanted into the mice, next to newly palpated tumors, and tumor growth determined. We also determined the effect of a major resveratrol metabolite, piceatannol, on experimental lung metastasis. Resveratrol, at any concentration tested, did not have a statistically significant effect on tumor growth. The higher levels of resveratrol tested (0.006% in food or 100 mg in slow-release pellets) tended to stimulate tumor growth (P = 0.08-0.09). Resveratrol and its major metabolites, resveratrol glucuronide and piceatannol, were found in serum, liver, skin, and tumor tissue. Piceatannol did not affect the in vitro growth of a murine melanoma cell line, but significantly stimulated the number of lung metastases when these melanoma cells were directly injected into the tail vein of the mouse. These results suggest that resveratrol is not likely to be useful in the treatment of melanoma and that the effects of phytochemicals on cell cultures may not translate to the whole animal system.

PPAR-γ ligands and amino acid deprivation promote apoptosis of melanoma, prostate, and breast cancer cells

The PPAR-gamma ligands, 15-deoxy-Delta(12,14)-prostaglandin J(2) and ciglitazone, and the PPAR-alpha ligand, WY-14643, were examined for their effects on proliferation and apoptosis of A375 melanoma, DU145 and PC3 prostate cancer, and MB-MDA-231 breast cancer. While 15-deoxy-Delta(12,14)-prostaglandin J(2) inhibited proliferation of A375 melanoma, ciglitazone was inactive against this and the other cell lines. Restriction of specific amino acids known to inhibit proliferation and induce apoptosis sensitized all cell lines to ciglitazone, and the combined effects were greater than the individual effects of either treatment. WY-14643 alone or in combination with amino acid deprivation was inactive. Normal fibroblasts were resistant to the treatments.

Chronic alcohol consumption in mice increases the proportion of peripheral memory T cells by homeostatic proliferation

This study examined the mechanism underlying the increase of peripheral memory phenotype T cells that occurs during chronic alcohol consumption in mice. Female C57BL/6 mice were given 20% (w/v) alcohol in the drinking water for 2 weeks to 6 months. Chronic alcohol consumption significantly induced peripheral T cell lymphopenia; up-regulated expression of CD44 on T cells and increased the percentage of CD4+CD44int/hi and CD8+CD44int/hi Ly6C+ T cells; up-regulated the expression of CD43 on CD8+ T cells; increased the percentage of interferon--producing T cells; decreased the percentage of CD8+CD28+ T cells; and down-regulated the expression of CD28 on CD4+ T cells. Expression of CD25 and CD69 on peripheral CD8+ T cells was not affected and inconsistently expressed on CD4+ T cells. Neither cell type showed altered expression of CD137 or CD153. Alcohol withdrawal did not abrogate the increase in CD8+Ly6C+cells induced by alcohol consumption. In vivo bromodeoxyuridine incorporation experiments demonstrated that chronic alcohol consumption decreases naïve T cells that are presumed to have emigrated from the thymus and increases proliferation of memory T cells, but accelerates peripheral T cell turnover. Together these results indicate that chronic alcohol consumption results in T cell lymphopenia, which in turn induces T cell homeostatic proliferation that increases the proportion of peripheral memory T cells relative to naïve T cells.

Specific amino acid restriction inhibits attachment and spreading of human melanoma via modulation of the integrin/focal adhesion kinase pathway and actin cytoskeleton remodeling

We had previously found that selective restriction of amino acids inhibits invasion of human A375 melanoma. Integrins, cell surface receptors for the components of extracellular matrix (ECM), are activated during cell adhesion and spreading, and initiate signaling pathways that control growth and invasion of tumor cells. We examined the effect of tyrosine (Tyr) and phenylalanine (Phe), methionine (Met) or glutamine (Gln) restriction on attachment and spreading of A375 and MeWo melanoma cell lines on fibronectin and laminin. In A375 cells, restriction of Tyr/Phe or Met inhibited attachment to and spreading on laminin and fibronectin, inhibited alpha3 and alpha4 integrin expression, and inhibited accumulation of FAK-Tyr397 and F-actin at leading edges of cell protrusions. Tyr/Phe restriction also inhibited attachment-induced autophosporylation of FAK-Tyr397. In MeWo cells, the order of inhibition by amino acid restriction on cell attachment and spreading was as follows: Gln > Tyr/Phe > Met. Restriction of Gln reduced alpha5 integrin expression. All amino acid restrictions similarly inhibited phosphorylation of FAK-Tyr397, FAK-Tyr577, FAK-Tyr861 and paxillin-Tyr31. Gln restriction exhibited the strongest inhibition of actin cytoskeleton remodeling during the cell spreading. The present study reveals that specific amino acid restriction inhibits attachment and spreading of melanoma via inhibition of specific integrin expression, inhibition of integrin-mediated FAK phosphorylation, and modulation of actin cytoskeleton remodeling. These data provide additional understanding of the mechanism by which specific amino acid restriction controls invasion and migration of melanoma.

Determination of piceatannol in rat serum and liver microsomes: pharmacokinetics and phase I and II biotransformation

A method of analysis of piceatannol in biological fluids is necessary to study the kinetics of in vitro and in vivo metabolism and determine its concentration in foodstuffs. A novel and simple high-performance liquid chromatographic method was developed for simultaneous determination of piceatannol and products of its metabolism in rat serum and liver microsomes. Serum, or microsomes (0.1 mL), were precipitated with acetonitrile after addition of the internal standard, 4-methylumbelliferone. Separation was achieved on a phenomenex C(18) column (250 x 4.6 mm i.d., 5 microm) equipped with a phenomenex C(18) (4 x 3.0 mm i.d., 5 microm) guardcolumn with fluorescence excitation at 320 nm and emission at 420 nm. Separation was also possible with UV detection at 310 nm. The fluorescent calibration curves were linear ranging from 0.05 to 100 microg/mL. The mean extraction efficiency was >95%. Precision of the assay was <10% (coefficient of variation), and was within 10% at the limit of quantitation (0.05 ng/mL). Bias of the assay was lower than 7%. The limit of detection was 50 ng/mL for a 0.1 mL sample. The assay was applied successfully to the in vitro kinetic study of metabolism of piceatannol in rat liver microsomes and pharmacokinetics in rats. Three metabolites of piceatannol have been identified. .

Daxx-mediated transcriptional repression of MMP1 gene is reversed by SPOP

Daxx-mediated transcriptional repression was modulated by a speckled POZ domain protein SPOP which was first identified as an autoantigen from the serum of a scleroderma patient. This is the first report on the biochemical and functional interactions between Daxx and SPOP. The COOH-terminal region of Daxx interacts with the NH2-terminal region of SPOP. SPOP reversed the transcriptional repression mediated by Daxx which binds with ETS1 transcription factor to repress ETS1-responsive gene expression. Mutagenesis study suggests that the ability of SPOP to self-associate as well as its ability to bind with Daxx was important for the modulation of Daxx-mediated transcriptional repression.

Leptin and cellular and innate immunity in abstinent alcoholics and controls

BACKGROUND

Basic studies indicate that in vitro and in vivo doses of leptin modulate cellular immune responses. Given evidence that concentrations of leptin are altered in alcoholics who also show immune abnormalities, this study examined the relationships between circulating levels of leptin and markers of cellular and innate immunity.

METHODS

Circulating levels of leptin, natural killer cell (NK) activity, interleukin-2 (IL-2)-stimulated NK activity, and concanavalin A-stimulated production of IL-2, IL-6, IL-10, and IL-12 were compared between abstinent DSM-IV alcohol-dependent men (n = 27) and age- and gender-matched controls (n = 34).

RESULTS

As compared with controls, alcoholics showed lower NK activity (p < 0.01) and a trend for lower levels of leptin (p = 0.055). In the total sample, leptin predicted NK activity (beta = 0.33; p < 0.05) after controlling for the confounding influence of body mass index, alcohol intake, and smoking. Leptin was not correlated with any of the cytokine measures. To examine whether the effects of leptin were mediated by its direct action on NK, additional studies examined in vitro effects of leptin on NK activity in healthy volunteers (n = 10); leptin doses (0.1, 1, and 10 nM) yielded levels of NK activity comparable to those with media alone.

CONCLUSIONS

These data show that circulating levels of leptin are associated with NK activity in humans and suggest that abnormal in vivo concentrations of leptin may contribute to the declines of NK activity in alcoholics who are at risk for infectious diseases.

Specific amino acid dependency regulates invasiveness and viability of androgen-independent prostate cancer cells

Androgen-independent prostate cancer is resistant to therapy and is often metastatic. Here we studied the effect of deprivation of tyrosine and phenylalanine (Tyr/Phe), glutamine (Gln), or methionine (Met), in vitro on human DU145 and PC3 androgen-independent prostate cancer cells, and on nontumorigenic human infant foreskin fibroblasts and human prostate epithelial cells. Deprivation of the amino acids similarly inhibited growth of DU145 and PC3 cells, arresting the cell cycle at G0/G1. Met and Tyr/Phe deprivation induces apoptosis in DU145, but only Met deprivation induces apoptosis in PC3 cells. The growth of normal cells is inhibited, but no apoptosis is induced by amino acid deprivation. Tyr/Phe deprivation inhibits expression and phosphorylation of focal adhesion kinase (FAK) and extracellular-regulated kinase (ERK) in DU145 but not PC3 or normal cells. Met deprivation inhibits phosphorylation but not protein expression of FAK and ERK in PC3. Therefore, apoptosis of DU145 and PC3 cells by amino acid restriction is FAK and ERK dependent. Tyr/Phe and Met deprivation inhibits invasion of DU145 and PC3, but Gln deprivation only inhibits invasion of DU145 cells. This indicates that the inhibition of invasion is not dependent on induction of apoptosis. The inhibition of invasion by Tyr/Phe restriction in DU145 and Met restriction in PC3 is consistent with the inhibition on FAK/ERK signaling. The inhibition of Tyr/Phe restriction in PC3 and Gln restriction in DU145 is not associated with inhibition of FAK/ERK. This indicates that FAK/ERK-dependent and independent pathways are modulated by specific amino acid restriction. This study shows the potential for specific amino acid restriction to treat prostate cancer.

Dephosphorylation of p53 during cell death by N-alpha-tosyl-L-phenylalanyl chloromethyl ketone

The apoptotic function of N-alpha-tosyl-L-phenylalanyl chloromethyl ketone (TPCK) was investigated in cultured human colorectal carcinoma cells (HCT116). TPCK-induced apoptosis was shown to be p53-dependent in HCT116 cells during the early stage of incubation. The function of p53 was required for TPCK-induced activation of caspase-3 and caspase-7. TPCK promoted dephosphorylation of p53 on serine residues at 6, 9, 46, 376, and 378 in parallel with the activation of p53 transcriptional activity. HCT116 p53-/- cells expressing p53 mutant, in which serine residues at 6, 9, 46, 376, and 378 were replaced by aspartic acids, were resistant to TPCK-induced apoptosis suggesting the requirement of dephosphorylation of p53 on serine residues during TPCK-induced apoptosis.

Cleavage of 14-3-3 protein by caspase-3 facilitates bad interaction with Bcl-x(L) during apoptosis

The 14-3-3 epsilon protein was identified as one of the caspase-3 substrates by the modified yeast two-hybrid system. The cellular 14-3-3 epsilon protein was also cleaved in response to the treatment of apoptosis inducers in cultured mammalian cells. Asp238 of the 14-3-3 epsilon protein was determined as the site of cleavage by caspase-3. The affinity of the cleaved 14-3-3 mutant protein (D238) to Bad, a death-promoting Bcl-2 family protein, was lower than that of wild type or the uncleavable mutant 14-3-3 epsilon protein (D238A). However, Bad associated with the cellular Bcl-x(L) more effectively in human 293T cells co-expressing Bad with the truncated form of the 14-3-3 epsilon protein (D238) than in control cells co-expressing Bad with wild type or the uncleavable mutant 14-3-3 epsilon protein (D238A). The present study suggests that the cleavage of 14-3-3 protein during apoptosis promotes cell death by releasing the associated Bad from the 14-3-3 protein and facilitates Bad translocation to the mitochondria and its interaction with Bcl-x(L).

Alcohol consumption decreases IL-2-induced NF-kappaB activity in enriched NK cells from C57BL/6 mice

Previously we showed that ethanol (EtOH) consumption suppressed IL-2-induced cytolytic activity of murine splenic natural killer (NK) cells. Although IL-2 receptor signaling is involved in activation of NK cells, neither the mechanism for this activation nor the role of EtOH consumption in modulating activation is completely understood. In this study we show by electrophoretic mobility-shift assay (EMSA) that enriched splenic NK cells from EtOH-consuming C57BL/6 mice exhibit reduced NF-kappaB and AP-1 binding activity in response to IL-2 stimulation as compared to the water-drinking mice. Semiquantitative RT-PCR and real-time PCR analyses indicated that EtOH consumption inhibits the induction of perforin, granzyme A, and granzyme B in response to IL-2. Pyrrolidine dithiocarbamate (PDTC) and N-tosyl-L-phenylalanine chloromethyl ketone (TPCK) blocked NFkappaB and AP-1 binding activity in nuclear extracts of IL-2-stimulated NK cells in an EMSA and also inhibited the IL-2-induced expression of perforin, granzyme A, and granzyme B gene expression in enriched NK cells. These inhibitors dramatically suppressed IL-2-stimulated NK cytolytic activity against YAC-1 lymphoma target cells. Taken together, these results suggest that NFkappaB and AP-1 are important regulators of NK cell cytolytic function through regulation of perforin, granzyme A, and granzyme B gene expression. The findings further suggest that the decreased cytolytic activity of IL-2-stimulated NK cytolytic activity in EtOH-consuming mice is due at least in part to impaired transactivation of these and possibly other genes involved in control of NK-cell target lysis.

Resveratrol is a potent inducer of apoptosis in human melanoma cells

Resveratrol is a plant polyphenol found in grapes and red wine. It has been found to have beneficial effects on the cardiovascular system. Resveratrol also inhibits the growth of various tumor cell lines in vitro and inhibits carcinogenesis in vivo. In this study we examined the effect of resveratrol on growth of two human melanoma cell lines. We found that this plant polyphenol inhibited growth and induced apoptosis in both cell lines, with the amelanotic cell line A375 being more sensitive. The potential involvement of different MAP kinases in the action of resveratrol was also examined. Although resveratrol did not alter the phosphorylation of p38 or JNK MAP kinases in either cell line, it induced phosphorylation of ERK1/2 in A375, but not in SK-mel28 cells. These results suggest that in vivo studies of the effect of resveratrol on melanoma are warranted and that this plant polyphenol might have effectiveness as either a therapeutic or chemopreventive agent against melanoma.

Beta-endorphin modulation of lymphocyte proliferation: effects of ethanol

BACKGROUND

We have previously shown that alcohol suppresses the natural killer (NK) cell activity of splenic lymphocytes partly by reducing the secretion of opioid peptide beta-endorphin (beta-EP) and its positive influence on NK-cell cytolytic activity in rats. The inhibition of NK-cell cytolytic activity was also associated with a reduced number of NK cells after chronic ethanol administration. Hence, the possibility arises that chronic ethanol may alter NK cell proliferation, survival, or both. In this study, we investigated whether ethanol treatment for 1 to 4 weeks reduces the proliferation of other lymphocyte subsets and whether beta-EP regulates ethanol's effect on lymphocyte proliferation.

METHODS

Male rats were ad libitum-fed rat chow, pair-fed with isocaloric liquid diet, or fed with ethanol-containing liquid diet for 1, 2, 3, or 4 weeks. Groups of these rats were infused with beta-EP with or without the delta-receptor antagonist naltrindol into the paraventricular nucleus of the hypothalamus. Splenocytes were isolated and used for flow cytometric analysis of the changes in the number of various lymphocyte subsets. Lymphocyte proliferation was determined by mitogen stimulation assays.

RESULTS

Ethanol consumption resulted in a reduction of the number of CD161+ NK cells, CD3+ T lymphocytes, CD4+ T-helper cells, and CD8a+ cytotoxic T cells in a time-dependent fashion. Alcohol consumption also suppressed the proliferative response of lymphocyte subsets to concanavalin A, phytohemagglutinin, and lipopolysaccharide. Beta-EP promoted the lymphocytes' proliferative response to mitogens, whereas naltrindol blocked the effects of the opioid. Chronic alcohol consumption reduced the proliferative response of lymphocytes to beta-EP.

CONCLUSIONS

These results suggest that chronic alcohol administration reduces immune function partly by decreasing the opioid-regulated mitogen-stimulated proliferation of lymphocyte subsets.

A role for NF-kappa B activation in perforin expression of NK cells upon IL-2 receptor signaling

Optimal NK cell development and activation as well as cytolytic activity involves IL-2R beta signals that also up-regulate expression of the pore-forming effector molecule perforin. Although the Jak/Stat pathway and specifically Stat5 transcription factors are required to promote many of the respective downstream events, the role of additional signaling pathways and transcription factors remains to be clarified. This report investigates the role of NF-kappa B activation for perforin expression by NK cells. It is demonstrated that IL-2-induced up-regulation of perforin in primary NK cells and in a model cell line is blocked by two pharmacological agents known to inhibit NF-kappa B activation. Direct evidence for the activation of the NF-kappa B pathway by IL-2R signals in NK cells involves activation of the IKK alpha kinase, inhibitory protein kappa B alpha degradation, nuclear translocation of p50/p65 complexes, and ultimately, transcriptional activation of the perforin gene via an NF-kappa B binding element in its upstream enhancer. Taken together, these observations strongly suggest that IL-2R signals can activate a pathway leading to NF-kappa B activation in NK cells and that this pathway is involved in the control of perforin expression.