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.