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Though remissions have been observed following allo-HSCT for the treatment of CLL, many CLL patients are ineligible for transplant due to the lack of HLA-compatible donors. The use of umbilical cord blood (UCB) permits transplantation of many patients who lack HLA-compatible donors due to reduced requirements for stringent HLA matching between graft and recipient; however, disease relapse remains a concern with this modality. The generation of CLL-specific CTL from UCB T-cells, primed and expanded against the leukemic clone, might enhance the GVL effect and improve outcomes with UCB transplantation. Here we report the generation of functional, CLL-specific CTL using CD40-ligated CLL cells to prime partially-HLA matched UCB T-cells. Functionality and specificity were demonstrated by immune synapse assay, IFN-γ ELISpot, multi-parametric intracellular cytokine flow cytometry, and (51)Cr release assay. The use of patient-specific, non-CLL controls demonstrated the generation of both alloantigen and CLL-specific responses. Subsequently, we developed a clinically-applicable procedure permitting separation of alloreactive CTL from leukemia-specific CTL. Leukemia-specific CTL were able to mediate in vivo killing of CLL in humanized mice without concurrent or subsequent development of xenoGVHD. Our results demonstrate that generation of CLL-specific effectors from UCB is feasible and practical, and the results support further exploration of this strategy as a treatment modality for CLL.

B-cell receptor (BCR) signaling has been inferred as an important mechanism for disease progression in chronic lymphocytic leukemia (CLL) and other B-cell malignancies. In response to BCR activation, CLL cells secrete the chemokine CCL3, which fosters interactions between CLL cells and the leukemia microenvironment. CCL3 secretion correlates with expression of the 70-kDa ζ-associated protein (ZAP-70) and responsiveness of the CLL clone to BCR stimulation. Here, we measured CCL3 plasma levels by enzyme-linked immunosorbent assay (ELISA) in 351 CLL patients and examined CCL3 levels for associations with established prognostic markers and time from diagnosis to initial therapy. We found that CCL3 plasma concentrations were strongly associated with established prognostic markers. In a Cox proportional hazards regression model, CCL3 as well as established prognostic markers (immunoglobulin heavy chain variable-region mutation status, CD38 or ZAP-70 cytogenetics, clinical stage) were significantly associated with time to treatment. Multivariable analysis revealed that CCL3 (hazard ratio [HR] = 2.33, P < .0001), advanced clinical stage (HR = 2.75, P = .0025), poor risk cytogenetics (del 17p, HR = 2.38; del11q, HR = 2.36, P = .001), and CD38 expression (HR = 1.43, P = .023) were independent prognostic markers. Collectively, CCL3 is a novel, robust, and independent prognostic marker in CLL that can easily and reliably be measured by ELISA. CCL3 therefore should become useful for risk assessment in patients with CLL.

We evaluated the activity and tolerability of alemtuzumab given as a continuous infusion for 7 d followed by subcutaneous administration for 11 wk as salvage therapy for 10 patients with fludarabine-refractory chronic lymphocytic leukemia. The continuous infusion of alemtuzumab was well tolerated. The typical infusion reaction seen with intravenous alemtuzumab was abolished. Two patients achieved a partial response with an overall response rate of 20%. Alemtuzumab levels were measured in four patients and detectable levels were obtained in three. Clinical activity needs to be confirmed in a larger patient population.

The c-Jun N-terminal kinase (JNK)/stress activated protein kinase is preferentially activated by stress stimuli. Growth factors, particularly ligands for G protein-coupled receptors, usually induce only modest JNK activation, although they may trigger marked activation of the related extracellular signal-regulated kinase. In the present study, we demonstrated that homozygous disruption of glycogen synthase kinase 3beta (GSK-3beta) dramatically sensitized mouse embryonic fibroblasts (MEFs) to JNK activation induced by lysophosphatidic acid (LPA) and sphingosine-1-phosphate, two prototype ligands for G protein-coupled receptors. To a lesser degree, a lack of GSK-3beta also potentiated JNK activation in response to epidermal growth factor. In contrast, the absence of GSK-3beta decreased UV light-induced JNK activation. The increased JNK activation induced by LPA in GSK-3beta null MEFs was insufficient to trigger apoptotic cell death or growth inhibition. Instead, the increased JNK activation observed in GSK-3beta-/- MEFs was associated with an increased proliferative response to LPA, which was reduced by the inhibition of JNK. Ectopic expression of GSK-3beta in GSK-3beta-negative MEFs restrained LPA-triggered JNK phosphorylation and induced a concomitant decrease in the mitogenic response to LPA compatible with GSK-3beta through the inhibition of JNK activation, thus limiting LPA-induced cell proliferation. Mutation analysis indicated that GSK-3beta kinase activity was required for GSK-3beta to optimally inhibit LPA-stimulated JNK activation. Thus GSK-3beta serves as a physiological switch to specifically repress JNK activation in response to LPA, sphingosine-1-phosphate, or the epidermal growth factor. These results reveal a novel role for GSK-3beta in signal transduction and cellular responses to growth factors.

The completion of the human genome project, the evolution of transcriptional profiling and the emergence of proteomics have focused attention on these areas in the pathophysiology and therapy of cancer. The role of lysophospholipids as potential mediators in cancer pathophysiology, screening and management has taken a major leap forward with the recent cloning of several enzymes involved in the metabolism of lysophospholipids. Lysophospholipids, although small molecules, contain a high "informational" content. Differences include the nature of the phosphate head group, the regiochemistry of the fatty acyl chain on the glyceryl backbone, the presence of ether versus ester linkages to the backbone, and the length and saturation of the fatty acyl or alkyl chain. This informational content is sufficient to result in a marked structure function activity relationship at their cognate receptors. Thus the emerging discipline of "functional lipidomics" is likely to prove as important as genomics and proteomics in terms of early diagnosis, prognosis, and therapy. Lysophospholipid levels are elevated in vivo in a number of pathophysiological states including ascitic fluid from ovarian cancer patients indicating a role in the pathophysiology of this devastating disease. Although controversial, levels of specific lysophospholipids may be altered in the blood of cancer patients providing a potential mechanism for early diagnosis. Several of the enzymes involved in the metabolism of lysophospholipids are aberrant in ovarian and other cancers. Further, the enzymes are active in the interstitial space, rendering them readily accessible to the effects of inhibitors including antibodies, proteins, and small molecules. In support of a role for lysophospholipids in the pathophysiology of cancer, expression of receptors for lysophospholipids is also aberrant in cancer cells from multiple different lineages. All of the cell surface receptors for lysophospholipids belong to the G protein coupled receptor family. As over 40% of all drugs in current use target this family of receptors, lysophospholipid receptors are highly "druggable." Indeed, a number of highly specific agonists and antagonists of lysophospholipid receptors have been identified. A number are in preclinical evaluation as therapeutics. We look forward to the next several years when the role of lysophospholipids in physiology and the pathophysiology and management of cancer and other diseases are fully elucidated., (Copyright 2004 Wiley-Liss, Inc.)

A potential role for lysophosphatidic acid (LPA) in human oncogenesis was first suggested by the observation that LPA is present at elevated levels in ascites of ovarian cancer patients. In the current study, we demonstrated that LPA is a potent inducer of interleukin-6 (IL-6) and interleukin-8 (IL-8) production in ovarian cancer cells. Both IL-6 and IL-8 have been implicated in ovarian cancer progression. We characterized the IL-8 gene promoter to ascertain the transcriptional mechanism underlying LPA -induced expression of these cytokines. LPA stimulated the transcriptional activity of the IL-8 gene with little effect on IL-8 mRNA stability. The optimal response of the IL-8 gene promoter to LPA relied on binding sites for NF-kappaB and AP-1, two transcription factors that were strongly activated by LPA in ovarian cancer cell lines. Positive regulators of the NF-kappaB and AP-1 pathways synergistically activated the IL-8 gene promoter. Further, the effect of LPA on IL-6 and IL-8 generation is mediated by the Edg LPA receptors as enforced expression of LPA receptors restored LPA-induced IL-6 and IL-8 production in non-responsive cells and enhanced the sensitivity to LPA in responsive cell lines. The LPA(2) receptor was identified to be the most efficient in linking LPA to IL-6 and IL-8 production although LPA(1) and LPA(3) were also capable of increasing the response to a certain degree. These studies elucidate the transcriptional mechanism and the Edg LPA receptors involved in LPA-induced IL-6 and IL-8 production and suggest potential strategies to restrain the expression of these cytokines in ovarian cancer.

The levels of lysophosphatidic acid (LPA) are consistently elevated in the ascites of ovarian cancer patients, suggesting that ovarian cancer cells are exposed to an LPA replete environment. LPA stimulates cell proliferation, cell survival, resistance to cisplatin, production and activation of proteases, invasiveness and production of the neovascularizing factors, vascular endothelial growth factor, and interleukin 8. Although ovarian cancer cells can produce LPA, this may not be the major reason for altered LPA levels in ascites. We have demonstrated that the major mechanism of degradation of LPA by ovarian cancer cells is through a lipid phosphate phosphatase (LPP)-like activity. We demonstrate herein that LPP-1 mRNA is decreased in the majority of ovarian cancers. This is recapitulated in ovarian cancer cell lines, where LPP-1 RNA levels are lower than those in normal ovarian epithelium and immortalized ovarian epithelial cells. Introduction of LPP-1 into ovarian cancer cell lines results in increased LPA hydrolysis, which is associated with a marked inhibition of cell proliferation and colony-forming activity and a marked increase in apoptosis. Thus, the LPA-rich environment of the ovarian cancer cell in vivo and the subsequent effects of cellular pathophysiology may be a consequence of both increased LPA production and decreased LPA metabolism by ovarian cancer cells.

Cyclin-dependent kinase (CDK) inhibitor p27Kip1 binds to the cyclin E.CDK2 complex and plays a major role in controlling cell cycle and cell growth. Our group and others have reported that anti-HER2 monoclonal antibodies exert inhibitory effects on HER2-overexpressing breast cancers through G1 cell cycle arrest associated with induction of p27Kip1 and reduction of CDK2. The role of p27Kip1 in anti-HER2 antibody-induced cell cycle arrest and growth inhibition is, however, still uncertain. Here we have provided several lines of evidence supporting a critical role for p27Kip1 in the anti-HER2 antibody-induced G1 cell cycle arrest and tumor growth inhibition. Induction of p27Kip1 and G1 growth arrest by anti-HER2 antibody, murine 4D5, or humanized trastuzumab (Herceptin) are concentration-dependent, time-dependent, irreversible, and long-lasting. The magnitude of G1 cell cycle arrest induced by trastuzumab or 4D5 is well correlated with the level of p27Kip1 protein induced. Up-regulation of p27Kip1 and G1 growth arrest could no longer be removed with as little as 14 h of treatment with trastuzumab. Anti-HER2 antibody-induced p27Kip1 protein, G1 arrest, and growth inhibition persist at least 5 days after a single treatment. The magnitude of growth inhibition of breast cancer cells induced by anti-HER2 antibody closely parallels the level of p27Kip1 induced. Induced expression of exogenous p27Kip1 results in a p27Kip1 level-dependent G1 cell cycle arrest and growth inhibition similar to that obtained with anti-HER2 antibodies. Reducing p27Kip1 expression using p27Kip1 small interfering RNA blocks anti-HER2 antibody-induced p27Kip1 up-regulation and G1 arrest. Treatment with anti-HER2 antibody significantly increases the half-life of p27Kip1 protein. Inhibition of ubiquitin-proteasome pathway, but not inhibition of calpain and caspase activities, up-regulates p27Kip1 protein to a degree comparable with that obtained with anti-HER2 antibodies. We have further demonstrated that anti-HER2 antibody significantly decreases threonine phosphorylation of p27Kip1 protein at position 187 (Thr-187) and increases serine phosphorylation of p27Kip1 protein at position 10 (Ser-10). Expression of S10A and T187A mutant p27Kip1 protein increases the fraction of cells in G1 and reduces a further antibody-induced G1 arrest. Consequently, p27Kip1 plays an important role in the anti-HER2 antibody-induced G1 cell cycle arrest and tumor growth inhibition through post-translational regulation. Regulation of the phosphorylation of p27Kip1 protein is one of the post-translational mechanisms by which anti-HER2 antibody upregulates the protein.

Cancer cells in which the PTEN lipid phosphatase gene is deleted have constitutively activated phosphatidylinositol 3-kinase (PI3K)-dependent signaling and require activation of this pathway for survival. In non-small cell lung cancer (NSCLC) cells, PI3K-dependent signaling is typically activated through mechanisms other than PTEN gene loss. The role of PI3K in the survival of cancer cells that express wild-type PTEN has not been defined. Here we provide evidence that H1299 NSCLC cells, which express wild-type PTEN, underwent proliferative arrest following treatment with an inhibitor of all isoforms of class I PI3K catalytic activity (LY294002) or overexpression of the PTEN lipid phosphatase. In contrast, overexpression of a dominant-negative mutant of the p85alpha regulatory subunit of PI3K (Deltap85) induced apoptosis. Whereas PTEN and Delta85 both inhibited activation of AKT/protein kinase B, only Deltap85 inhibited c-Jun NH2-terminal kinase (JNK) activity. Cotransfection of the constitutively active mutant Rac-1 (Val12), an upstream activator of JNK, abrogated Deltap85-induced lung cancer cell death, whereas constitutively active mutant mitogen-activated protein kinase kinase (MKK)-1 (R4F) did not. Furthermore, LY294002 induced apoptosis of MKK4-null but not wild-type mouse embryo fibroblasts. Therefore, we propose that, in the setting of wild-type PTEN, PI3K- and MKK4/JNK-dependent pathways cooperate to maintain cell survival.

Lysophosphatidic acid (LPA) is present at elevated concentrations in the ascites and plasma of ovarian cancer patients. Ovarian cancer cells produce and release LPA both constitutively and after stimulation. LPA can induce proliferation, survival, invasiveness, and resistance to chemotherapy of ovarian cancer cells. This suggests that LPA may be critically important for the development or progression of ovarian cancer and is thus a potential target for therapy. In this study, we demonstrate that introduction of the integral membrane protein, human lipid phosphate phosphohydrolase-3 (hLPP-3) enzyme, which hydrolyzes phosphatidic acid, LPA, sphingosine, and ceramide phosphate in vitro with selectivity for LPA, into SKOV3 and OVCAR-3 ovarian cancer cells decreases colony-forming activity, increases apoptosis, and decreases tumor growth in vitro and in vivo. Strikingly, coculture of hLPP-3-expressing cells with nontransfected parental cells decreased the colony-forming activity of the parental cells, compatible with hLPP-3 decreasing levels of an extracellular mediator, likely LPA. Compatible with this contention, the expression of hLPP-3 was associated with increased rates of extracellular LPA hydrolysis. The effects of hLPP-3 on colony-forming activity were substantially reversed by the LPP-resistant LPA analogue, O-methylphosphothionate. The ability of O-methylphosphothionate to ameliorate the effects of hLPP-3, combined with the inability of an enzymatically inactive hLPP-3 to alter cellular function, suggests that the major effect of hLPP-3 was to increase the hydrolysis of extracellular LPA. Thus genetic or pharmacological manipulation of LPA metabolism, receptor activation, or downstream signaling is an attractive approach for therapy of ovarian cancer.

ARHI, an imprinted putative tumor suppressor gene, encodes a M(r) 26,000 GTP-binding protein that is 60% homologous to ras and rap but has a dramatically different function. ARHI expression is down-regulated in a majority of breast and ovarian cancers. Using a dual adenovirus system, we have reexpressed ARHI in ovarian cancer and breast cancer cells that have lost ARHI expression. Reexpression of ARHI inhibited growth, decreased invasiveness, and induced apoptosis. At 5 days after infection with ARHI adenovirus, 30-45% of MDA-MB-231 breast cancer cells and 5-11% of SKOv3 ovarian cancer cells were apoptotic as judged by a terminal deoxynucleotidyl transferase-mediated nick end labeling assay and by Annexin V staining with flow cytometric analysis. Although poly(ADP-ribose) polymerase could be detected immunohistochemically in the nuclei of apoptotic cells, no activation of the effector caspases (caspase 3, 6, 7, or 12) or the initiator caspases (caspase 8 or 9) could be detected in cell lysates using Western blotting. When gene expression was analyzed on a custom cDNA array that contained 2304 known genes, infection with ARHI adenovirus up-regulated 15 genes relative to control cells infected with LacZ adenovirus. The greatest degree of mRNA up-regulation was observed in a Homo sapiens calpain-like protease. On Western blot analysis, calpain protein was increased 2-3-fold at 3-5 days after infection with ARHI adenovirus. No increase in calpain protein was observed after LacZ adenovirus infection. Calpain cleavage could be detected after ARHI reexpression, and inhibitors of calpain, but not inhibitors of caspase, partially prevented ARHI-induced apoptosis. Consequently, reexpression of ARHI in breast and ovarian cancer cells appears to induce apoptosis through a caspase-independent, calpain-dependent mechanism.

Objective: One potential limitation of gene therapy for epithelial tumors is the lack of tissue or tumor specificity of treatment. Tumor-selective expression of gene therapies may avoid deleterious side effects and improve the efficacy of the treatment. The aim of this study was to evaluate the tissue and tumor specificity of four different potential gene therapy promoters, to determine their usefulness in tissue-specific gene therapy of epithelial ovarian carcinomas., Methods: Three potential epithelial cell-selective (hESE1, SLP1, OSP1) and one potential tumor-selective (hTERT) promoter were placed upstream of a luciferase construct to determine relative activity in a wide variety of normal and malignant cell lines. Transient transfection and luciferase assays were carried out in 12 epithelial ovarian (3 SV40 T antigen-transfected normal and 9 malignant) and 8 control cell lines., Results: Luciferase assays revealed that the hTERT promoter presented the highest tumor selectivity. hESE1 and SLP1 promoters showed strong epithelial cell selectivity (hESE1, 16/17; SLP1, 15/17), with the OSP1 (11/17) promoter exhibiting lower epithelial selectivity. Of the potential promoters for gene therapy, hTERT promoter exhibited the strongest transcriptional activity in most of the tumor cell lines. None of the promoters exhibited strict ovarian epithelium selectivity., Conclusion: The hTERT promoter may be an optimal promoter for a univector gene therapy approach based on its high tumor selectivity. Utilization of multiple epithelial cell-specific promoters may result in a more tissue-selective gene therapy approach. Using a combination of promoters may prevent potential problems due to expression in nonepithelial stem cells that may constitutively express hTERT.

Lysophosphatidic acid (LPA) is a naturally occurring phospholipid that exhibits pleiotrophic biological activities, ranging from rapid morphological changes to long-term cellular effects such as induction of gene expression and stimulation of cell proliferation and survival on a wide spectrum of cell types. LPA binds and activates distinct members of the Edg/LP subfamily of G protein-coupled receptors that link to multiple G proteins including Gi, Gq and G12/13 to elicit cellular responses. LPA plays a critical role as a general growth, survival and pro-angiogenic factor, in the regulation of physiological and pathophysiological processes in vivo and in vitro. Our previous work indicates that abnormalities in LPA metabolism and function in ovarian cancer patients may contribute to the initiation and progression of the disease. Thus, LPA could be a potential target for cancer therapy. This review summarizes evidence that implicates LPA in the pathophysiology of human ovarian cancer and likely other types of human malignancies.

Under resting conditions, the p85 regulatory subunit of phosphatidylinositol 3-kinase (PI3K) serves to both stabilize and inactivate the p110 catalytic subunit. The inhibitory activity of p85 is relieved by occupancy of the NH(2)-terminal SH2 domain of p85 by phosphorylated tyrosine. Src family kinases phosphorylate tyrosine 688 in p85, a process that we have shown to be reversed by the activity of the p85-associated SH2 domain-containing phosphatase SHP1. We demonstrate that phosphorylation of the downstream PI3K target Akt is increased in cells lacking SHP1, implicating phosphorylation of p85 in the regulation of PI3K activity. Furthermore, the in vitro specific activity of PI3K associated with tyrosine- phosphorylated p85 is higher than that associated with nonphosphorylated p85. Expression of wild-type p85 inhibits PI3K enzyme activity as indicated by PI3K- dependent Akt phosphorylation. The inhibitory activity of p85 is accentuated by mutation of tyrosine 688 to alanine and reversed by mutation of tyrosine 688 to aspartic acid, changes that block and mimic tyrosine phosphorylation, respectively Strikingly, mutation of tyrosine 688 to aspartic acid completely reverses the inhibitory activity of p85 on cell viability and activation of the downstream targets Akt and NFkappaB, indicative of the physiological relevance of p85 phosphorylation. Tyrosine phosphorylation of Tyr(688) or mutation of tyrosine 688 to aspartic acid is sufficient to allow binding to the NH(2)-terminal SH2 domain of p85. Thus an intramolecular interaction between phosphorylated Tyr(688) and the NH(2)-terminal SH2 domain of p85 can relieve the inhibitory activity of p85 on p110. Taken together, the data indicate that phosphorylation of Tyr(688) in p85 leads to a novel mechanism of PI3K regulation.

CD26 is a M(r) 110,000 surface glycoprotein with diverse functional properties, including having a potentially significant role in tumor development, and antibodies to CD26 mediate pleomorphic cellular functions. In this report, we show that binding of soluble anti-CD26 monoclonal Ab 1F7 inhibits the growth of the human CD30+ anaplastic large cell T-cell lymphoma cell line Karpas 299 in both in vitro and in vivo experiments. In vitro experiments show that 1F7 induces cell cycle arrest at the G1-S checkpoint, associated with enhanced p21 expression that is dependent on de novo protein synthesis. Furthermore, experiments with a severe combined immunodeficient mouse tumor model demonstrate that 1F7 treatment significantly enhances survival of tumor-bearing mice by inhibiting tumor formation. Our data therefore suggest that anti-CD26 treatment may have potential clinical use for CD26+ hematological malignancies.

The protein kinase B/Akt serine/threonine kinase, located downstream of phosphoinositide 3-kinase (PI-3K), is a major regulator of cellular survival and proliferation. Atypical protein kinase C (aPKC) family members are activated by PI-3K and also contribute to cell proliferation, suggesting that Akt and aPKC might interact to activate signalling through the PI-3K cascade. Here we demonstrate that blocking PKC activity in MDA-MB-468 breast cancer cells increased the phosphorylation and activity of Akt. Functional PI-3K was required for the PKC inhibitors to increase Akt phosphorylation and activation, potentially owing to the activation of specific PKC isoforms by PI-3K. The concentration dependence of the action of the PKC inhibitors implicates aPKC in the inhibition of Akt phosphorylation and activity. In support of a role for aPKC in the regulation of Akt, Akt and PKCzeta or PKClambda/iota were readily co-precipitated from the BT-549 breast cancer cell line. Furthermore, the overexpression of PKCzeta inhibited growth-factor-induced increases in Akt phosphorylation and activity. Thus PKCzeta associates physically with Akt and decreases Akt phosphorylation and enzyme activity. The effects of PKC on Akt were transmitted through the PI-3K cascade as indicated by changes in p70 s6 kinase (p70(s6k)) phosphorylation. Thus PKCzeta, and potentially other PKC isoenzymes, regulate growth-factor-mediated Akt phosphorylation and activation, which is consistent with a generalized role for PKCzeta in limiting growth factor signalling through the PI-3K/Akt pathway.

Lysophosphatidic acid (LPA) is a naturally occurring phospholipid with multiple biological functions. In the present study, we demonstrate that, besides its mitogenic activity, LPA is a potent survival factor, preventing serum-deprivation-induced apoptosis in fibroblasts and other cell types. Both the proliferative effect and survival activity of LPA are sensitive to the action of pertussis toxin (PTX), indicating that both processes are mediated by G(i) protein(s). We therefore focused on the role of G(i)-protein-mediated signalling events in the promotion of cell survival by LPA. In addition to activation of mitogen-activated protein kinase (MAPK), LPA stimulates a modest PTX-sensitive phosphorylation/activation of the serine/threonine kinase Akt, a survival mediator downstream of phosphoinositide 3-kinase (PI3K). Inhibition of PI3K with LY 294002 or wortmannin resulted in a marked inhibition of LPA-induced DNA synthesis, and yet the survival activity of LPA decreased by only 20-30%, suggesting a limited input of the PI3K-Akt cascade in LPA-induced cell survival. In contrast, inhibition of MAPK activation by the MEK-1 inhibitor, PD 98059, blocked both the proliferative and survival effects of LPA. These results indicate that LPA promotes cell survival largely via G(i)-protein-mediated activation of ERK1/ERK2, or other PD 98059-sensitive member(s) of the MAPK family.

Retinoids are potent inhibitors of human bronchial epithelial (HBE) cell growth. Retinoids initiate signaling through activation of nuclear receptors, but the signal transduction pathways that mediate growth inhibition have not been defined. In this study, we investigated the expression of insulin-like growth factor (IGF)-binding protein (IGFBP)-6 as a potential mediator of retinoid actions. IGFBP-6 is a secreted glycoprotein that inhibits the bioavailability of IGFs, which are potent mitogens of HBE cells. IGFBP-6 was detected by immunohistochemical staining in the basal epithelial layer of human bronchial organ cultures, and all-trans-retinoic acid (t-RA) treatment increased the intensity of IGFBP-6 immunostaining. In primary cultures of HBE cells treated with t-RA, IGFBP-6 messenger RNA and protein levels increased within 6 and 24 h, respectively, and IGFBP-6 was detected in the conditioned media at 48 h. The effect of IGFBP-6 on HBE cell growth was investigated with a recombinant adenoviral vector, Ad5CMV-BP6, which expresses IGFBP-6 under the control of a cytomegalovirus promoter. IGFBP-6 overexpression induced a proliferative arrest of HBE cells with no evidence of apoptosis. These findings provide the first evidence that IGFBP-6 is expressed in the bronchial epithelium and that IGFBP-6 may contribute to the biologic effects of retinoids on HBE cells.

Levels of lysophosphatidic acid (LPA) and lysophosphatidylcholine (LPC) are elevated in the plasma and ascites of ovarian cancer patients, but not in most other tumor types. LPA increases cell proliferation, cell survival, resistance to cisplatin, cell shrinkage, and production of vascular endothelial growth factor, urokinase plasminogen activator, and LPA itself in ovarian cancer cells, but not in normal ovarian surface epithelial cells. PSP24 and members of the endothelial differentiation gene (EDG) family (EDG1, EDG2, EDG4, and EDG7) of G protein-coupled receptors mediate LPA signaling. Ovarian cancer cell lines do not express EDG1 mRNA, have variable EDG2 mRNA and protein levels, and frequently exhibit levels of EDG4 mRNA and protein, suggesting that EDG4 may contribute to the deleterious effects of LPA in ovarian cancer. In contrast, activation of the EDG2 LPA receptor on ovarian cancer cells may lead to apoptosis and counter the effects of other LPA receptors. Thus, the development of agonists and antagonists for the appropriate spectrum of LPA receptors may alter proliferation, apoptosis, or response to therapy of ovarian cancer cells. Indeed, over 60% of all current drugs target the G protein-coupled family of receptors, making the LPA receptor family a "drugable" target. LPC, although not as thoroughly studied, increases cellular proliferation and mediates multiple other functions through unique signaling pathways.

Lysophosphatidic acid (LPA) is one of the major growth factors in ascites from ovarian cancer patients and appears to play an important role in proliferation, survival, and invasion of ovarian cancer cells. Recently, several groups have shown that Edg-2, which belongs to the G-protein coupled receptor family, is a functional LPA receptor. Northern blot analysis showed that most ovarian cancer cell lines express Edg-2. Edg-2 expression was especially high in the cisplatin-resistant and slowly proliferating 2780cp cell line and was almost absent from the cisplatin-sensitive and rapidly proliferating A2780 cell line. We thus assessed whether Edg-2 could contribute to changes in cell viability, cell proliferation, or cisplatin resistance. Stable overexpression of Edg-2 in A2780 cells induced an exogenous LPA-independent decrease in proliferation but did not alter cisplatin sensitivity. The LPA-independent decrease in growth rate induced by overexpression of Edg-2 could be explained, at least in part, by Edg-2-induced apoptosis rather than by effects on cell cycle progression. In agreement with the results in stably transfected A2780 cells, transient expression of Edg-2 in Jurkat T cells also induced apoptosis. When cells were separated from the extracellular matrix, they underwent a specialized form of apoptosis called anoikis, which is particularly important in survival of cells in the circulation during metastasis. A2780 cells engineered to overexpress Edg-2 were particularly sensitive to anoikis. These observations suggest that Edg-2 may be a negative regulator for ovarian epithelial cell growth and metastasis.

The PTEN/MMAC1/TEP (PTEN) tumor suppressor gene at 10q23.3 is mutated in multiple types of sporadic tumors including breast cancers and also in the germline of patients with the Cowden's breast cancer predisposition syndrome. The PTEN gene encodes a multifunctional phosphatase capable of dephosphorylating the same sites in membrane phosphatidylinositols phosphorylated by phosphatidylinositol 3'-kinase (PI3K). We demonstrate herein that loss of PTEN function in breast cancer cells results in an increase in basal levels of phosphorylation of multiple components of the P13K signaling cascade as well as an increase in duration of ligand-induced signaling through the P13K cascade. These alterations are reversed by wild-type but not phosphatase inactive PTEN. In the presence of high concentrations of serum, enforced expression of PTEN induces a predominant G1 arrest consistent with the capacity of PTEN to evoke increases in the expression of the p27Kip1 cyclin dependent kinase inhibitor. In the presence of low concentrations of serum, enforced PTEN expression results in a marked increase in cellular apoptosis, a finding which is consistent with the capacity of PTEN to alter the phosphorylation, and presumably function, of the AKT, BAD, p70S6 kinase and GSK3 alpha apoptosis regulators. Under anchorage-independent conditions, PTEN also induces anoikis, a form of apoptosis that occurs when cells are dissociated from the extracellular matrix, which is enhanced in conjunction with low serum culture conditions. Together, these data suggest that PTEN effects on the PI3K signaling cascade are influenced by the cell stimulatory context, and that depending on the exposure to growth factors and other exogenous stimuli such as integrin ligation, PTEN can induce cell cycle arrest, apoptosis or anoikis in breast cancer cells.

The MMAC/PTEN tumor suppressor gene encodes for a phosphatase that recently has been shown to have phosphotidylinositol phosphatase activity, implicating its possible involvement in phosphatidylinositol 3'-kinase-mediated signaling. To investigate possible alterations in growth factor-mediated signal transduction, an adenovirus containing MMAC/PTEN, Ad-MMAC, previously shown to inhibit growth and tumorigenicity in glioma cells, was used to acutely express the transgene. Human glioma cells infected with Ad-MMAC but not with control adenoviruses exhibited an inhibition of phosphorylation of both activating residues of Akt, Ser-473, and Thr-308, along with Akt's serine/threonine kinase activity, without significantly altering Akt expression. The effects of functional MMAC/PTEN expression were relatively specific, because members of several other growth factor-mediated signaling pathways showed no altered responses. The presence of MMAC/PTEN also inhibited phosphorylation of BAD, although no evidence of apoptosis in the in situ treated cells was observed. However, U251 glioma cells infected with Ad-MMAC were induced to undergo anoikis at a significantly higher rate than U251 cels treated with control viruses or mock infected with media. These results demonstrate that the acute administration of MMAC/PTEN results in the inhibition of Akt-mediated signaling, growth inhibition, and anoikis, implying that loss of MMAC/PTEN increases cellular proliferation and significantly augments a cell's survival potential during cellular processes that are associated with malignancy.

p202 is an interferon (IFN)-inducible, primarily nuclear, phosphoprotein (52-kDa) whose overexpression in transfected cells inhibits colony formation. p202 binds to the retinoblastoma tumor suppressor protein and two other members of the pocket family proteins (p107 and p130). Moreover, overexpression of p202 in transfected cells inhibits the transcriptional activity of E2Fs (E2F-1/DP-1 and E2F-4/DP-1), p53, AP-1 c-Fos and c-Jun, NF-kappaB p50 and p65. Here we demonstrate that inhibition of endogenous p202 production in murine AKR-2B fibroblasts did not result in an increase in cell proliferation. Instead, these cells exhibited increased susceptibility to apoptosis in response to decrease in serum concentrations in the growth medium. These observations are consistent with the notion that normal levels of p202 may be needed for the regulation of cell proliferation., (Copyright 1998 Academic Press.)

Optimal T cell activation requires crosslinking of the T cell receptor (TCR) concurrently with an accessory receptor, most efficiently CD28. Crosslinking of CD28 leads to increased interleukin 2 (IL2) production, inhibition of anergy and prevention of programmed cell death. Crosslinking of CD28 leads to rapid increases in tyrosine phosphorylation of specific intracellular substrates including CD28 itself. Since CD28 does not encode an intrinsic tyrosine kinase domain, CD28 must activate an intracellular tyrosine kinase(s). Indeed, crosslinking of CD28 increases the activity of the intracellular tyrosine kinases EMT/ITK and LCK. The phosphatidylinositol 3-kinase (PI3K) and GRB2 binding site in CD28 is dispensable for optimal IL2 production in Jurkat T cells. We demonstrate herein that murine Y170 (equivalent to human Y173) in CD28 is also dispensable for activation of the SRC family tyrosine kinase LCK and the TEC family tyrosine kinase EMT/ITK. In contrast, the distal three tyrosines in CD28 are required for optimal IL2 production as well as for optimal activation of the LCK and EMT/ITK tyrosine kinases. The distal three tyrosines of CD28, however, are not required for recruitment of PI3K to CD28. Furthermore, PI3K is recruited to CD28 in JCaM1 cells which lack LCK and in which EMT/ITK is not activated by ligation of CD28. Thus optimal activation of LCK or EMT/ITK is not obligatory for recruitment of PI3K to CD28 and thus is also not required for tyrosine phosphorylation of the YMNM motif in CD28. Taken together the data indicate that the distal three tyrosines in CD28 are integral to the activation of LCK and EMT/ITK and for subsequent IL2 production.

We have recently established a new Philadelphia chromosome (Ph1)-positive acute lymphoblastic leukemia (ALL) cell line, designated Z-33. This line has L2 morphology, ultrastructural characteristics of lymphoblasts and typical B lineage surface markers identical to those observed in the Ph1-positive ALL patient from whom the line was derived. In addition, a rearranged immunoglobulin heavy-chain gene (JH) band was found in Z-33 cells by Southern blot analysis, confirming B cell clonality. Cytogenetic analysis of the cell line revealed t(9;22)(q34;q11.2). Polymerase chain reaction (PCR)-amplified cDNA from Z-33 cells demonstrated an e1-az BCR-ABL junction, and the p190BCR-ABL protein was detected in them by the immune complex kinase assay. Z-33 cells produce interleukin (IL)-1 beta, IL-6, granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage CSF (GM-CSF), tumor necrosis factor (TNF)-alpha, and transforming growth factor (TGF)-beta, Neither IL-1 beta, G-CSF, TNF-alpha, nor their corresponding antibodies affected the cell line's growth. In contrast, anti-GM-CSF neutralizing antibodies suppressed Z-33 colony formation, and GM-CSF stimulated it in a dose-dependent fashion. In addition, receptor studies with biotinylated GM-CSF demonstrated specific binding to Z-33 cells, indicating that the cells express GM-CSF receptors. Taken together, our data suggest that the Ph1-positive Z-33 ALL cells produce GM-CSF, express GM-CSF receptors, and show an autocrine proliferative response to this cytokine.

Like tumor necrosis factor (TNF), antibodies against the Fas antigen (anti-Fas) are cytotoxic to some and induce proliferation of other Fas-expressing cells. In this study, we compared cellular responses mediated through TNF with anti-Fas using a T cell line (Jurkat) and a macrophage cell line (U-937). These two cell types differed in that the Jurkat cells expressed higher levels of Fas antigen than U-937 cells, whereas the latter expressed higher levels of the p80 form of the TNF receptor than Jurkat cells. Treatment for 72 h with anti-Fas inhibited the growth of both Jurkat and U-937 cells, the 50% inhibitory concentrations (IC50) being 10 and 100 ng/ml, respectively. Under similar conditions, the IC50 for TNF was > 100 and 0.8 ng/ml for Jurkat and U-937 cells, respectively. Like TNF, the cytotoxic effects of anti-Fas were potentiated by cycloheximide, showing they did not require protein synthesis. Interestingly, in the presence of cycloheximide, the kinetics of cell killing was more rapid for TNF than anti-Fas (50% inhibition occurred at 3 versus 6h). Treatment of both cell types with anti-Fas led to time-dependent DNA fragmentation, but TNF-induced DNA fragmentation occurred only in the presence of cycloheximide. Pretreatment of cells with TNF led to resistance to TNF but not to anti-Fas, suggesting that the receptors for the two are not cross-modulated. Furthermore, TNF activated the nuclear transcriptional factor NF-kappa B in both cell types, whereas anti-Fas had no effect. Overall, our results demonstrate that anti-Fas and TNF transduce over-lapping and nonoverlapping signals in macrophage-like and T cell lines through distinct pathways.

Leukemia inhibitory factor (LIF) is a cytokine that was originally described as a differentiation factor of a murine myeloid leukemia cell line and subsequently found to be an important mediator of embryonic development. Although extensively studied in the hematopoietic system, its effects on solid tumors are generally unknown. In the present study we investigated the role of LIF in human breast cancer cells. Using the reverse transcriptase-polymerase chain reaction, we found that the human breast carcinoma MCF-7 cell line expressed the message for both LIF receptor and its signal-transducing protein gp130, suggesting that these receptors might be biologically active. Binding studies with radiolabeled LIF demonstrated that MCF-7 cells interacted with this cytokine, and the ligand binding was specific and time, dose, and temperature dependent. In addition, a Scatchard analysis of the data revealed a single class of high-affinity (Kd 0.27 nM) receptors with a density of approximately 430 sites per cell. MCF-7 cells exposed to LIF internalized and degraded the ligand. LIF stimulated the growth of MCF-7 as well as other estrogen-dependent and independent breast cancer cell lines, but the effect on normal breast epithelial lines was less significant. Likewise, it stimulated colony formation by breast cancer cells obtained from five different breast cancer patients in a dose-dependent fashion. These results overall suggest that human breast tumor cells express functional LIF receptors that play a role in breast cancer cell proliferation.

The limited life span in culture of normal human diploid fibroblasts (HDF) has provided a model of cellular senescence. The short-term growth of these cells in culture is regulated by a number of different cytokines, including tumor necrosis factor (TNF), interleukin-1 (IL-1), and fibroblast growth factor (FGF). However, the effect of senescence on the responsiveness of HDF to these cytokines is not known. In the present report, we examined the effects of TNF on foreskin-derived HDF at different passage levels. We compared the response of HDF cells at population doubling (PD) 23 (young) with that of cells at PD 70 (senescent). Young cells proliferated in response to TNF in a dose-dependent manner. Under these conditions TNF had no effect on senescent HDF. The decrease in TNF responsiveness was found to be dependent on PD. The lack of response of senescent HDF was not unique to TNF, since FGF and IL-1 were also ineffective. In contrast to senescent HDF, TNF-dependent proliferation of young HDF could be further potentiated by IL-1 and FGF, suggesting an independent signaling mechanism. On exposure to TNF, senescent HDF produced IL-6 and IL-8, but to a much lower degree than that produced by young HDF. The diminished responsiveness of senescent HDF to TNF does not appear to be due to the difference in either receptor number or affinity, since senescent cells had two- to threefold higher number of TNF receptors than young HDF but the same affinity. TNF induced the activation of a nuclear transcriptional factor, NF-kappa B, equally in both young and senescent cells, which indicates the lack of a defect in the early events of TNF signal transduction in senescent fibroblasts. Overall, our results indicate that there is an age-dependent decline in TNF-induced proliferation and in the production of interleukins by fibroblasts; this unresponsiveness appears not to be due to TNF receptors or NF-kappa B activation. These results may have importance in understanding the diminished immune response, inflammation, and wound healing associated with aging.

Suramin, a polysulfonated naphthylurea, is an antitrypanosomal and antifilarial drug. Because of its anti-reverse transcriptase activity and antiproliferative activity, suramin is also used for the treatment of acquired immunodeficiency syndrome and cancer. In spite of these uses, very little is known about its effects on the immune system. In this report, we investigated the effects of suramin on peripheral blood mononuclear cells. We found that natural killer (NK) cell-mediated cytotoxicity against human erythroblastoid cell line K562 was completely inhibited by suramin in a dose-dependent manner. It also completely blocked lymphokine-activated killer (LAK) cell-mediated cytotoxicity against the human B lymphoblastoid cell lines Raji and Daudi. The cytotoxicity against the human melanoma tumor cell line A-375 mediated by unstimulated and stimulated monocytes was also suppressed by suramin. Maximum inhibition of monocyte-mediated cytotoxicity was observed when suramin was present during both the activation and the effector phases of cytotoxicity. Besides its effects on cell-mediated cytotoxicity, suramin also inhibited the cytotoxic effects of tumor necrosis factor (TNF) against different tumor cell lines. Furthermore, we found that suramin interferes with the binding of TNF with its receptor. Thus our results indicate that suramin overall downregulates the immune system by inhibiting cell-mediated and TNF-mediated cytotoxicity against different tumor cells.

Previous studies have demonstrated that the expression of tumor-associated antigens can be regulated by cytokines. The purpose of this study was to determine whether tumor necrosis factor alpha (TNF alpha) and gamma-interferon (IFN gamma) were capable of modulating epidermal growth factor receptor (EGFr) immunorecognition on a human melanoma cell line in vitro. DX-3 melanoma cells treated for 24-72 h with various concentrations of each cytokine were incubated with an anti-EGFr monoclonal antibody (Mab) (A108) that recognizes an extracellular domain of the receptor, and differences in binding were analyzed by flow cytometry and radioimmunoassay. A dose- and time-dependent enhancement in EGFr immunorecognition was measurable in TNF alpha- and IFN gamma-treated cells. Combinations of these cytokines enhanced the recognition of EGFr on DX-3 cells to a level greater than that achieved with either TNF alpha or IFN gamma alone. Scatchard analysis of receptor binding curves revealed that there was no significant change in Mab affinity between control and cytokine-treated DX-3 melanoma cells, whereas a 1.5- to 1.8-fold enhancement in the number of Mab binding sites was measurable in TNF alpha- and IFN gamma-treated cells, respectively, when compared with controls. Immune complex kinase assay of EGFr showed threefold higher tyrosine kinase activity in TNF alpha-treated cells, but no change in kinase activity was observed following IFN gamma treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

It is well known that expression of certain growth factors leads to tumorigenesis. However, the role of growth inhibitory molecules in this process is less certain. During the last few years several cytokines with growth inhibitory properties have been identified. In spite of the production of these cytokines by the body's immune system, the growth and progression of the tumor continue. In order to understand the mechanisms by which tumor escapes the host defense system, we have used lymphotoxin (LT), a lymphocyte-derived cytokine that is known to selectively inhibit the growth of certain tumor cells. The effect of LT was investigated on NIH-3T3 mouse fibroblast cells that are highly sensitive to its cytotoxic effects and are also tumorigenic in nude mice. On exposure to 10 units/ml of LT, 50% of these cells are killed within 24 h. A stable variant of NIH-3T3 cells that is completely resistant (LT-R) to even 10,000-fold higher concentration of the cytokine than that of sensitive cells (LT-S) was isolated in vitro by repeated exposure to LT. Both LT-S and LT-R displayed similar characteristics when grown both as a monolayer and in soft agar. No significant difference in LT receptor number or affinity between the two cell types was observed. It was not possible to overcome the resistance to LT by the addition of interferon-gamma but the resistance could be overcome by the presence of various chemotherapeutic agents suggesting a difference in the mechanism of action of these two agents.(ABSTRACT TRUNCATED AT 250 WORDS)

The in vitro immune response to herpes simplex virus (HSV), type 1, strain 539, HSV type 2, strain 316D, and cytomegalovirus was studied in 20 patients (14 with acquired immune deficiency syndrome, four with the acquired immune deficiency syndrome-related symptom complex, and two sexually active asymptomatic homosexuals) and 18 heterosexual healthy controls. Peripheral blood mononuclear cells were cultured with 2 X 10(5) plaque-forming units of heat-inactivated viruses, their lymphocyte blastogenic responses were measured after 5 days in culture by [3H]-thymidine incorporation, their interferon production was measured after 24 hr and 5 days, and natural killer (NK) cell activation was measured after 24 hr and 5 days of culture. Blastogenic responses to viruses were significantly low for only HSV, type 1:1.75 X 10(3) cpm in patients' cells compared to 6.36 for controls. Interferon responses to all three viruses were significantly low at both 24 hr and 5 days; e.g., HSV, type 1:139 IU/ml in patients' cells compared to 777 for controls at 24 hr. NK cell responses of patients were lower than those of controls when tested fresh and after 24 hr of incubation: 6.1 versus 11.7% and 9.2 versus 16.8% target cell lysis, respectively. Exposure to viruses boosted NK cell responses of both patients' and controls' cells, but boosting was generally greater among the normal rather than the patients' cells. The abnormalities of response were present in all three patient groups. Addition of interleukin-2 in vitro increased the patient and control blastogenic and NK responses but did not augment the interferon responses. The in vitro responses to both HSV, type 1, and HSV, type 2, correlated significantly with our conventional assays of the percentage and absolute level of T4+-helper lymphocytes in the blood and the blastogenic responses to mitogens, such as phytohemagglutinin, pokeweed mitogen, and concanavalin A. This system should be useful for the study of host defense in acquired immune deficiency syndrome patients and those in high-risk groups, and also for the in vitro evaluation of immunomodulators.

The effects of a combination of recombinant alpha-interferon (IFN-alpha) and interleukin-2 (IL-2)-activated human killer cells (lymphokine-activated killer or LAK cells) on Hs294T (IFN-sensitive) and A375P (IFN-resistant) human melanoma cell lines were evaluated. Pretreatment of target cells with IFN-alpha for at least 1 day increased their susceptibility to the lytic activity of LAK cells. The combination of the two agents in sequence (IFN-alpha followed by LAK cells) resulted in a true synergystic killing of both IFN-alpha-sensitive and resistant tumor cells. No synergy was observed when the sequence was reversed (LAK cells followed by IFN-alpha). When peripheral blood mononuclear cells were incubated simultaneously with IFN-alpha and IL-2, LAK cell generation and antitumor activity was markedly inhibited when tested against both IFN-treated and -non-treated tumor cells. These studies may be used to plan clinical trials of combination cytokine therapy for human cancer.

Success with rIL-2 immunotherapy of human cancer appears to depend on the administration of high doses which are frequently associated with excessive toxicity. Future use of rIL-2 will require certain modifications based on the use of lower doses of rIL-2 without significant loss of antitumor efficacy. We tested in vitro the possibility of potentiating the activity of rIL-2 in terms of LAK cell generation. We hypothesized that co-incubation of LAK cell precursors with a Chinese herbal extract (F3) of Astragalus membranaceus, (an immune modulator currently under study in our laboratory), along with a low concentration of rIL-2, would generate levels of LAK cell activity equivalent to those generated by high concentrations of rIL-2 alone. We found (1) a 10-fold potentiation of rIL-2 activity manifested by tumor cell-killing activity of 80% resulting from LAK cell generation with F3 plus 100 u/ml of rIL-2 versus 76% generated by 1,000 u/ml of rIL-2 alone; (2) a significant reduction in the number of effector LAK cells required for equicytotoxic reaction following LAK cell generation with F3 plus rIL-2 compared to rIL-2 alone. We conclude that potentiation of antitumor activity mediated by rIL-2 in low concentrations is possible by the concomitant use of another immune modulator such as Astragalus membranaceus.