Genomic modelling of the ESR1 Y537S mutation for evaluating function and new therapeutic approaches for metastatic breast cancer.

Drugs that inhibit estrogen receptor-α (ER) activity have been highly successful in treating and reducing breast cancer progression in ER-positive disease. However, resistance to these therapies presents a major clinical problem. Recent genetic studies have shown that mutations in the ER gene are found in >20% of tumours that progress on endocrine therapies. Remarkably, the great majority of these mutations localize to just a few amino acids within or near the critical helix 12 region of the ER hormone binding domain, where they are likely to be single allele mutations. Understanding how these mutations impact on ER function is a prerequisite for identifying methods to treat breast cancer patients featuring such mutations. Towards this end, we used CRISPR-Cas9 genome editing to make a single allele knock-in of the most commonly mutated amino acid residue, tyrosine 537, in the estrogen-responsive MCF7 breast cancer cell line. Genomic analyses using RNA-seq and ER ChIP-seq demonstrated that the Y537S mutation promotes constitutive ER activity globally, resulting in estrogen-independent growth. MCF7-Y537S cells were resistant to the anti-estrogen tamoxifen and fulvestrant. Further, we show that the basal transcription factor TFIIH is constitutively recruited by ER-Y537S, resulting in ligand-independent phosphorylation of Serine 118 (Ser118) by the TFIIH kinase, cyclin-dependent kinase (CDK)7. The CDK7 inhibitor, THZ1 prevented Ser118 phosphorylation and inhibited growth of MCF7-Y537S cells. These studies confirm the functional importance of ER mutations in endocrine resistance, demonstrate the utility of knock-in mutational models for investigating alternative therapeutic approaches and highlight CDK7 inhibition as a potential therapy for endocrine-resistant breast cancer mediated by ER mutations.

Interleukin-1B-31 gene polymorphism in Hakka gastric cancer patients in Guangdong, China.

The aim of this study was to examine the interleukin-1B (IL-1B) gene promoter region -31 (IL-1B-31) polymorphism distribution characteristic of Hakka gastric cancer patients in Guangdong Province and to explore its association with gastric cancer. We used the 1:1 case-control method, matrix-assisted laser desorption ionization flight time mass spectrometry, and MassARRAY-IPLEX technology to genotype IL-1B-31 (-31C> T) in 52 Hakka gastric cancer patients and 52 Hakka control subjects in Meizhou. Three genotypes - CT, TT, and CC - of IL-1B-31 were found in the Meizhou Hakka population. Their distribution frequencies in the gastric cancer group were 40.38, 40.38, and 19.23%, respectively, whereas the frequencies in control subjects were 57.69, 17.31, and 25.00%, respectively. The differences in frequency distributions of the genotypes between the 2 groups were statistically significant (chi-square = 6.78, P < 0.05). Subjects with the TT genotype had a higher risk of gastric cancer compared with that in subjects carrying the CT genotype (odds ratio = 2.857, 95% confidence interval = 1.114-7.328). This risk was more apparent in male subjects. IL-1B-31 locus polymorphism may be associated with gastric cancer susceptibility in this population, but additional studies with larger sample size are needed to confirm the conclusions.

High output cardiac failure in a parturient with hereditary haemorrhagic telangiectasia.

Hereditary haemorrhagic telangiectasia is a genetic condition which results in arteriovenous malformations involving the skin, mucous membranes, lung, brain, gastrointestinal tract, liver and spinal canal. The shunting of blood through arteriovenous malformations, especially in the liver,; leads to maldistribution of cardiac output. In order to supply blood to vital organs, cardiac output is increased through vasodilation, elevated stroke volume and elevated heart rate. Pregnancy can worsen the effects of the arteriovenous malformations. We present the peripartum management of a woman with hereditary haemorrhagic telangiectasia predominantly involving the liver that resulted in high output cardiac failure during two consecutive pregnancies.

Elevated C-reactive protein level in hemodialysis patients with moderate/severe uremic pruritus: a potential mediator of high overall mortality.

BACKGROUND: Dialysis patients with uremic pruritus have worse outcomes. However, the pathophysiology of the high mortality in these patients remains inconclusive except for links with calcium/phosphate imbalance and sleep disturbance. Whether inflammation, an outcome predictor in dialysis patients, plays a role is unknown. METHODS: This prospective study included 321 chronic hemodialysis (HD) patients (>3 months) for survival analysis. A visual analog scale (VAS) was used to measure the severity of itching, and the patients were divided into four groups: no pruritus (VAS = 0, N = 118), mild (VAS 1-3, N = 76), moderate (VAS 4-7, N = 89) and severe pruritus (VAS 8-10, N = 38). The Pittsburgh Sleep Quality Index (PSQI) was used to define sleep disturbance, while high-sensitive C-reactive protein (hs-CRP) and tumor necrosis factor α (TNF-α) were used to evaluate inflammation. The patients were followed-up for 30 months. RESULTS: Patients with moderate/severe pruritus had higher hs-CRP, but similar TNF-α levels; they also had a worse survival rate (P = 0.0197, log rank test). By stratifying hs-CRP levels, those with higher hs-CRP had worse survival regardless of the severity of uremic pruritus. In a Cox proportional hazard model, hs-CRP levels and moderate/severe uremic pruritus were independent predictors of mortality after adjusting for age, poor sleeper (PSQI > 5), diabetes, albumin, phosphate, hemoglobin and parathyroid hormone levels and (hs-CRP) × (moderate/severe uremic pruritus) (all P < 0.05). CONCLUSION: In moderate/severe pruritic HD patients, those with higher hs-CRP suffer from worse overall mortality. Inflammation may bridge uremic pruritus to high mortality, and elevated hs-CRP predicts a worse outcome in this population.

Enhanced light output from a nitride-based power chip of green light-emitting diodes with nano-rough surface using nanoimprint lithography.

Enhanced light extraction from a GaN-based power chip (PC) of green light-emitting diodes (LEDs) with a rough p-GaN surface using nanoimprint lithography is presented. At a driving current of 350 mA and with a chip size of 1 mm × 1 mm packaged on transistor outline (TO)-cans, the light output power of the green PC LEDs with nano-rough p-GaN surface is enhanced by 48% when compared with the same device without a rough p-GaN surface. In addition, by examining the radiation patterns, the green PC LED with nano-rough p-GaN surface shows stronger light extraction with a wider view angle. These results offer promising potential to enhance the light output powers of commercial light-emitting devices by using the technique of nanoimprint lithography under suitable nanopattern design.

Nerve growth factor activates persistent Rap1 signaling in endosomes.

We investigated a role for endogenous Rap1, a small monomeric GTP-binding protein of the Ras family, in nerve growth factor (NGF) signaling in PC12 cells. Although both epidermal growth factor (EGF) and NGF caused transient activation of Ras, only NGF induced the activation of Rap1. Moreover, Rap1 activation was sustained for hours, an effect that matched the sustained activation of the mitogen-activated protein kinase (MAPK) pathway. To investigate the molecular basis for Rap1 activation, we examined complexes containing C3G, a guanine nucleotide exchange factor for Rap1, and CrkL, an adapter protein known to influence Rap1 signaling. NGF induced the formation of a long-lived complex containing C3G/CrkL/Shp2/Gab2/TrkA. Linking the complex to Rap1 activation, we coprecipitated activated TrkA and activated MAPK with activated Rap1 in NGF-treated cells. Confocal microscopy and subcellular fractionation showed that activated Rap1 and the other proteins of the signaling complex were present in endosomes. Pretreatment of PC12 cells with brefeldin A (BFA), which disrupts the Golgi and endosomal compartments, had little effect on Ras activation but strongly inhibited NGF-induced Rap1 activation and continuing MAPK activation. We propose that endosomes are a site from which NGF induces the prolonged activation of Rap1 and MAPK.

In vitro and in vivo induction of bone formation using a recombinant adenoviral vector carrying the human BMP-2 gene.

It has been well established that bone morphogenetic protein-2 (BMP-2) can induce bone formation both in vivo and in vitro, although high concentrations (up to milligrams) of BMP-2 have been required to achieve this effect in vivo. Further, clinical applications are usually limited to a single dose at the time of implantation. In an attempt to prolong the transforming effect of BMP-2 we used a recombinant adenoviral vector carrying the human BMP-2 gene (Adv-BMP2) to transduce marrow-derived mesenchymal stem cells (MSC) of skeletally mature male New Zealand white rabbits. The pluripotential MSC were incubated with Adv-BMP2 overnight followed by culture in growth medium for 1 week. Assays on tissue cultures demonstrated that these Adv-BMP2 transduced MSC produced BMP-2 protein, differentiated into an osteoprogenitor line, and induced bone formation in vitro. These MSC had increased alkaline phosphatase activity, increased expression of type I collagen, osteopontin, and osteocalcin mRNA, and induced matrix mineralization compared with both non-transduced cells and cells transduced with a control adenoviral construct. To analyze the osteogenic potential in vivo, Adv-BMP2-transduced MSC were autologously implanted into the intertransverse process space between L5 and L6 of the donor rabbits. The production of new bone was demonstrated by radiographic examination 4 weeks later in areas implanted with cells transduced with Adv-BMP2, whereas no bone was evident at sites implanted with cells transduced with the control adenoviral construct. Histological examination further confirmed the presence of new bone formation. These accumulated data indicate that it is possible to successfully transduce mesenchymal stem cells with a recombinant adenoviral vector carrying the gene for BMP-2 such that these cells will produce BMP-2, differentiate into an osteoprogenitor line, and induce bone formation both in vitro and in vivo. Moreover, incubation of the Adv-BMP2-transduced cells for an additional 7 days in culture before transplantation enhances the success rate in bone formation (three out of three) as compared with our previous report (one out of five, Calcif Tissue Int 63:357-360, 1998).

Erk is essential for growth, differentiation, integrin expression, and cell function in human osteoblastic cells.

Extracellular signal-regulated kinases (Erks), members of the mitogen-activated protein kinase superfamily, play an important role in cell proliferation and differentiation. In this study we employed a dominant negative approach to determine the role of Erks in the regulation of human osteoblastic cell function. Human osteoblastic cells were transduced with a pseudotyped retrovirus encoding either a mutated Erk1 protein with a dominant negative action against both Erk1 and Erk2 (Erk1DN cells) or the LacZ protein (LacZ cells) as a control. Both basal and growth factor-stimulated MAPK activity and cell proliferation were inhibited in Erk1DN cells. Expression of Erk1DN protein suppressed both osteoblast differentiation and matrix mineralization by decreasing alkaline phosphatase activity and the deposition of bone matrix proteins. Cell adhesion to collagen, osteopontin, and vitronectin was decreased in Erk1DN cells as compared with LacZ cells. Cell spreading and migration on these matrices were also inhibited. In Erk1DN cells, expression of alphabeta(1), alpha(v)beta(3), and alpha(v)beta(5) integrins on the surface was decreased. Metabolic labeling indicated that the synthesis of these integrins was inhibited in Erk1DN cells. These data suggest that Erks are not only essential for the growth and differentiation of osteoblasts but also are important for osteoblast adhesion, spreading, migration, and integrin expression.

Bone mineralization and osteoblast differentiation are negatively modulated by integrin alpha(v)beta3.

Numerous bone matrix proteins can interact with alpha(v)-containing integrins including alpha(v)beta3. To elucidate the net effects of the interaction between these proteins and alpha(v)beta3 on osteoblast function, we developed a murine osteoblastic cell line that overexpressed human alpha(v)beta3. Human alpha(v)beta3-integrin was expressed on cell membrane, in which its presence did not alter the surface level of endogenous mouse alpha(v)beta3. The expressed human alpha(v)beta3 was functional because cell adhesion to osteopontin was increased and this increment was abolished by antibody against human alpha(v)beta3. The proliferation rate of cells overexpressing alpha(v)beta3 (alpha(v)beta3-cells) was increased whereas matrix mineralization was decreased. To elucidate the mechanisms leading to inhibition of matrix mineralization, the expression of proteins important for mineralization was analyzed. Alkaline phosphatase activity and the expression of osteocalcin, type I collagen, and bone sialoprotein (BSP) were decreased whereas osteopontin was stimulated in alpha(v)beta3-cells. The regulation of osteopontin, osteocalcin, and BSP expression was mediated via transcriptional mechanism because their promoter activities were altered. Examination of molecules involved in integrin signaling indicated that activator protein-1 (AP-1) and extracellular signal-regulated kinase (Erk) activities were enhanced whereas c-jun N-terminal kinase (JNK) activity was decreased in alpha(v)beta3-cells. The activity of p38 and the levels of focal adhesion kinase (FAK) and vinculin were not altered. Moreover, the adhesions of alpha(v)beta3-cells to type I collagen and fibronectin were inhibited, which was attributed to decreased beta1-integrin levels on cell surface. In conclusion, overexpressing alpha(v)beta3-integrin in osteoblasts stimulated cell proliferation but retarded differentiation, which were derived via altered integrin-matrix interactions, signal transduction, and matrix protein expression.

In Vitro andIn Vivo induction of bone formation using a recombinant adenoviral vector carrying the human BMP-2 gene.

It has been well established that bone morphogenetic protein-2 (BMP-2) can induce bone formation bothin vivo andin vitro, although high concentrations (up to milligrams) of BMP-2 have been required to achieve this effectin vivo. Further, clinical applications are usually limited to a single dose at the time of implantation. In an attempt to prolong the transforming effect of BMP-2 we used a recombinant adenoviral vector carrying the human BMP-2 gene (Adv-BMP2) to transduce marrow-derived mesenchymal stem cells (MSC) of skeletally mature male New Zealand white rabbits. The pluripotential MSC were incubated with Adv-BMP2 overnight followed by culture in growth medium for 1 week. Assays on tissue cultures demonstrated that these Adv-BMP2 transduced MSC produced BMP-2 protein, differentiated into an osteoprogenitor line, and induced bone formationin vitro. These MSC had increased alkaline phosphatase activity, increased expression of type I collagen, osteopontin, and osteocalcin mRNA, and induced matrix mineralization compared with both nontransduced cells and cells transduced with a control adenoviral construct. To analyze the osteogenic potentialin vivo, Adv-BMP2-transduced MSC were autologously implanted into the intertransverse process space between L5 and L6 of the donor rabbits. The production of new bone was demonstrated by radiographic examination 4 weeks later in areas implanted with cells transduced with Adv-BMP2, whereas no bone was evident at sites implanted with cells transduced with the control adenoviral construct. Histological examination further confirmed the presence of new bone formation. These accumulated data indicate that it is possible to successfully transduce mesenchymal stem cells with a recombinant adenoviral vector carrying the gene for BMP-2 such that these cells will produce BMP-2, differentiate into an osteoprogenitor line, and induce bone formation bothin vitro andin vivo. Moreover, incubation of the Adv-BMP2-transduced cells for an additional 7 days in culture before transplantation enhances the success rate in bone formation (three out of three) as compared with our previous report (one out of five, Calcif Tissue Int 63:357-360, 1998).

A retrospective analysis of complications in the treatment of nevus of Ota with the Q-switched alexandrite and Q-switched Nd:YAG lasers.

BACKGROUND: Studies on the use of Q-switched alexandrite (QS alex) and QS Nd:YAG lasers in the treatment of nevus of Ota were limited to case reports and small series. There was no study that looked at the complication rate of these systems. OBJECTIVE: To retrospectively study the complication rate of nevus of Ota patients that were treated with QS alex laser, QS Nd:YAG laser, or a combination of both. METHODS: The study was performed in a teaching hospital and a private hospital, where 513 patients with nevus of Ota had been treated since 1993. The 171 patients with 211 treatment sites were evaluated retrospectively following treatment with QS alex laser only (n = 58), QS Nd:YAG laser (n = 105) only, or a combination of both systems (n = 48). Patients were called back to be interviewed and examined by two independent clinicians to look for evidence of complications. RESULTS: Of the treatment sites, 15. 3% had hypopigmentation, 2.9% had hyperpigmentation, and texture changes and scarring were seen in 2.9% and 1.9%, respectively. The combined treatment group was associated with a significantly higher risk of complications. Thirteen patients had recurrence of their nevus after complete or near-complete clearance with laser treatment. CONCLUSION: Hypopigmentation is common after the use of QS laser for lightening of nevus of Ota. This particularly applies when alternate treatment with QS alex and QS Nd:YAG is used. Recurrence is an important issue and must be taken into consideration, especially when children are treated.

Transforming growth factor-beta up-regulates the beta 5 integrin subunit expression via Sp1 and Smad signaling.

Integrin-mediated cell-matrix interactions play important roles in regulating cell function. Since transforming growth factor-beta (TGF-beta) modulates many osteoblast activities, we hypothesized that the growth factor acts in part by modulating integrin expression. TGF-beta increased cell adhesion to vitronectin and up-regulated the surface level of alpha(v)beta(5) via increasing beta(5) protein synthesis by a transcriptional mechanism. Promoter activity analysis demonstrated that a TGF-beta-responsive element resides between nucleotides -63 and -44. Electrophoretic mobility shift assay and immunoprecipitation/Western studies indicated that the nuclear complex formed using the -66/-42 oligonucleotide contained both Sp1/Sp3 and Smad proteins. Since nuclear Sp1/Sp3 levels were not altered, whereas Smad levels were increased by TGF-beta, we investigated the roles of Smad proteins in the up-regulation of beta(5) gene activation. Co-transfection of cells with beta(5) promoter reporter construct and expression vectors for Smad3, Smad4, and Sp1 increased the stimulatory effect of TGF-beta. Furthermore, expression of dominant negative Smad3 or Smad4 in cells decreased or abolished the stimulation of beta(5) promoter activity by TGF-beta. Smad4 mutant also inhibited the up-regulation of surface beta(5) level by TGF-beta. Thus, TGF-beta increases expression of the integrin beta(5) gene by mechanisms involving Sp1/Sp3 and Smad transcription factors.

Sp1/Sp3 and PU.1 differentially regulate beta(5) integrin gene expression in macrophages and osteoblasts.

Murine osteoclast precursors and osteoblasts express the integrin alpha(v)beta(5), the appearance of which on the cell surface is controlled by the beta(5), and not the alpha(v), subunit. Here, we show that a 173-base pair proximal region of the beta(5) promoter mediates beta(5) basal transcription in macrophage (osteoclast precursor)-like and osteoblast-like cells. DNase I footprinting reveal four regions (FP1-FP4) within the 173-base pair region, protected by macrophage nuclear extracts. In contrast, osteoblast nuclear extracts protect only FP1, FP2, and FP3. FP1, FP2, and FP3 bind Sp1 and Sp3 from both macrophage and osteoblast nuclear extracts. FP4 does not bind osteoblast proteins but binds PU.1 from macrophages. Transfection studies show that FP1 and FP2 Sp1/Sp3 sites act as enhancers in both MC3T3-E1 (osteoblast-like) and J774 (macrophage-like) cell lines, whereas the FP3 Sp1/Sp3 site serves as a silencer. Mutation of the FP2 Sp1/Sp3 site totally abolishes promoter activity in J774 cells, with only partial reduction in MC3T3-E1 cells. Finally, we demonstrate that PU.1 acts as a beta(5) silencer in J774 cells but plays no role in MC3T3-E1 cells. Thus, three Sp1/Sp3 sites regulate beta(5) gene expression in macrophages and osteoblast-like cells, with each element exhibiting cell-type and/or activation-suppression specificity.

Regulation of alphaVbeta3 and alphaVbeta5 integrins by dexamethasone in normal human osteoblastic cells.

Long-term administration of pharmacological doses of glucocorticoids inhibits bone formation and results in osteoporosis. Since integrin-mediated cell-matrix interactions are essential for osteoblast function, we hypothesized that the detrimental effect of glucocorticoids on bone derived, at least in part, from decreased integrin-matrix interactions. Because alphavbeta3 and alphavbeta5 integrins can interact with several bone matrix proteins, we analyzed the effects of dexamethasone (Dex) on the expression of these integrins in normal human osteoblastic cells. We found adhesion of these cells to osteopontin and vitronectin to be dependent on alphavbeta3 and alphavbeta5, respectively; this ligand specificity was not altered by Dex. The effects of Dex on the adhesion of human osteoblastic cells to osteopontin and vitronectin were biphasic with an increase after 2 days, followed by a decrease after 8 days of treatment. Consistently, surface alphavbeta3 and alphavbeta5 integrins, which were increased after 2 days of Dex treatment, were decreased after 8 days. Similarly, total cellular alphav, beta3, and beta5 proteins, which were increased by Dex early in the culture, were diminished after 8 days. Metabolic labeling studies indicated that Dex exhibited biphasic regulation on the biosynthesis of alphavbeta5, with stimulation observed during the second day of treatment, followed by inhibition during the 8th day of exposure. By contrast, the biosynthesis of alphavbeta3 was inhibited by Dex on day 1 and remained inhibited on day 8. Analysis of the mRNA indicated that alphav and beta5 levels were increased by Dex during early exposure (1-3 days), followed by inhibition after prolonged exposure (>/=7 days). By contrast, Dex decreased beta3 mRNA level at all the time points analyzed. Consistently, Dex decreased beta3 promoter activity after 1 day and persisted over 8-day period. By contrast, Dex stimulated beta5 promoter activity after 1 or 2 days but had no effect after 8 days. To further evaluate mechanism(s) leading to the decreased integrin expression after prolonged Dex treatment, mRNA stability was analyzed. Dex was found to accelerate the degradation of alphav, beta3 and beta5 mRNA after an 8-day treatment. Thus, the regulation of alphavbeta3 was dependent on transcription and posttranscriptional events whereas the expression of alphavbeta5 was dependent mainly on posttranscriptional events after prolonged Dex treatment. In conclusion, Dex exhibited time-dependent regulation on the expression of alphavbeta3 and alphavbeta5 integrins in normal human osteoblastic cells. Short-term exposure to Dex increased the levels of alphavbeta3 and alphavbeta5 on the surface and cell adhesion to osteopontin and vitronectin whereas long-term exposure to Dex decreased the expression of both integrins and inhibited the cell adhesion to matrix proteins.

The STAT3-independent signaling pathway by glycoprotein 130 in hepatic cells.

Interleukin (IL)-6 is a major regulator of hepatic acute-phase plasma protein (APP) genes. The membrane-proximal 133-amino acid cytoplasmic domain of glycoprotein (gp) 130, containing one copy of the Box3 motif, is sufficient to transmit a productive signal to endogenous APP genes in rat hepatoma H-35 cells. In contrast, a mutant gp130 domain lacking the Box3 motif activates Janus kinases to a normal level but fails to activate signal transducer and activator of transcription 3 and to up-regulate a number of APP genes, including thiostatin, fibrinogen, hemopexin, and haptoglobin. However, in the absence of Box3, gp130 still stimulates the expression of alpha2-macroglobulin and synergizes with IL-1 to up-regulate alpha1-acid glycoprotein. The Box3 motif is not required for activation of the SH2-containing protein tyrosine phosphatase 2 or the mitogen-activated protein kinase (MAPK), nor is the immediate induction of egr-1 and junB significantly altered. Surprisingly, gp130 without any functional Box3 stimulates prolonged activation of MAPK, leading to an extended period of up-regulation of egr-1 and to an extracellularly regulated kinase-mediated reduction in the IL-6-stimulated production of thiostatin. IL-6 reduces proliferation of H-35 cells through signaling by the Box3. In addition, cells expressing Box3-deficient gp130 showed distinct morphologic changes upon receptor activation. Taken together, these results indicate that Box3-derived and Box3-independent signals cooperate in the control of hepatic APP genes and that Box3 may be involved in the modulation of MAPK activity in gp130 signaling.

Characterization of interleukin-10 receptor expression on B-cell chronic lymphocytic leukemia cells.

B-cell chronic lymphocytic leukemia (B-CLL) cells accumulate in vivo in the G0/G1 phase of the cell cycle, suggesting that their malignant expansion is due, at least in part, to a delay in cell death. However, the cellular or molecular factors responsible for a delay in B-CLL cell death are unknown. B-CLL cells do express receptors for interferon-alpha (IFN-alpha) and IFN-gamma, and activation of both has been shown to promote B-CLL survival in vitro by preventing apoptosis. The interleukin-10 (IL-10) receptor is another member of the IFN receptor family, but its ligand, IL-10, has been reported to induce apoptosis in B-CLL cells. In the current study, we undertook a biochemical analysis of IL-10 receptor expression on freshly isolated B-CLL cells and characterized the functional responsiveness of IL-10 binding to its constitutively expressed receptor. We show that B-CLL cells bind IL-10 with significant specificity and express between 47 and 127 IL-10 receptor sites per cell, with a dissociation constant in the range of 168 to 426 x 10(-12) mol/L. Ligand binding and activation of the IL-10 receptor expressed on B-CLL cells results in the phosphorylation of signal transducer and activator of transcription 1 (STAT1) and STAT3 proteins. This pattern of STAT protein phosphorylation is identical to IL-10 receptor activation on normal cells and similar to IFN-alpha (STAT1 and STAT3) and IFN-gamma (STAT1) receptor activation in CLL. Further, in consecutive samples of fresh blood obtained from patients with B-CLL cells, the addition of IL-10 inhibited B-CLL proliferation, enhanced B-CLL differentiation, but did not induce apoptosis. Indeed, IL-10, like IFN-gamma, was able to significantly reduce the amount of B-CLL cell death caused by hydrocortisone-induced apoptosis. We conclude that cytokines, which signal through the interferon family of receptors, have comparable functional effects on B-CLL cells.