Jeng YJ, Suarez VR, Izban MG, Wang HQ, Soloff MS. Progesterone-induced sphingosine kinase-1 expression in the rat uterus during pregnancy and signaling consequences. Am J Physiol Endocrinol Metab 292: E1110 -E1121, 2007. First published December 12, 2006; doi:10.1152/ajpendo.00373.2006.-Sphingosine 1-phosphate (Sph-1-P), a product of sphingomyelin metabolism, can act via a family of cognate G protein-coupled receptors or as an intracellular second messenger for agonists acting through their membrane receptors. In view of the general growth promoting and developmental effects of Sph-1-P on target cells, we hypothesized that it plays a role in adaptation of the uterus to pregnancy. We analyzed its potential role and that of the related lysophospholipid lysophosphatidic acid in the pregnant rat uterus by examining changes in mRNA levels of cognate receptors and enzymes involved in their turnover. Of these, only sphingosine kinase-1 (SphK1) was markedly changed (ϳ30-fold increase), being localized in the glandular epithelium, vasculature, and the myometrium. Uterine SphK1 mRNA and protein levels paralleled those of serum progesterone, and treatment with progesterone or an antagonist elevated or reduced SphK1 mRNA expression, respectively. Progesterone also increased SphK1 mRNA steady-state levels in a rat myometrial/leiomyoma cell line (ELT3). Overexpressing human SphK1 in these cells resulted in increased levels of the cell cycle regulator cyclin D1 and increased myosin light-chain phosphorylation. Ectopic expression of SphK1 also resulted in increased proliferation rates, possibly in conjunction with increased cyclin D1 expression. These studies suggest that the uterine expression of SphK1 mediates processes involved in growth and differentiation of uterine tissues during pregnancy. ELT3 cells; myosin light-chain phosphorylation; cyclin D1; lysophospholipids; sphingosine 1-phosphate; sphingosine-1-phosphate lyase THE BIOACTIVE LYSOPHOSPHOLIPIDS sphingosine 1-phosphate (Sph-1-P) and lysophosphatidic acid (LPA) are growth factors that act through a family of G protein-coupled receptors (GPCRs), S1P 1 through S1P 5 and LPA 1 through LPA 4 , respectively (25), causing a broad array of effects on target cells, including cell proliferation, survival, migration, adhesion molecule expression, and morphogenesis (26,31,44,47,52). Sph-1-P also plays a role in vasculogenesis in the mouse embryo (4, 27). Both lysophospholipids increase myosin lightchain phosphorylation in platelets and endothelial cells (10, 37) by inhibiting myosin light-chain phosphatase (43). They also stimulate DNA synthesis in human myometrial cells in primary culture (20,32). Platelets are the major source of circulating Sph-1-P and LPA, releasing the lysophospholipids in response to prothrombotic stimuli (47, 54). Circulating Sph-1-P also arises by constitutive secretion by cells of hemangioblastic lineage, such as monocytes, and by mast, endothelial, and red blood cells (54).Intracellular Sph-1-P is synthesized by a variety of cell types and acts as a...

Purpose:The risk of developing breast cancer is positively correlated with exposure to increased levels of estrogen and/or an increased duration of estrogen exposure. Many different mechanisms have been proposed to explain the association of estrogens with breast cancer risk; however, the well-documented immune modulatory properties of estrogen have received little attention. In part, this is due to a lack of suitable models for studying this relationship. Experimental Design: We have developed an animal model using estrogen receptor (ER)-negative human breast cancer cell line, MDA-MB-468, xenografted into severe combined immunodeficient (SCID) mice. We also generated the ER-a knockout (ER-aKO) mice on the SCID background and then tested the ability of 17h-estradiol to stimulate growth of xenografted ER-negative human breast cancer tumors in wild-type and ER-aKO SCID mice. We quantified vascularization of tumors, macrophage recruitment to the tumor site by immunocytochemistry, and inflammatory cytokine production. Results: We show that estrogen treatment of C57BL/6/SCID mice promotes the growth of xenografted ER-negative tumors in wild-type mice and this estrogen-induced tumor growth is abrogated in ER-aKO mice. Tumor neovascularization of estrogen-treated mice was unchanged versus control; however, estrogen treatment of the C57BL/6/SCID host suppressed macrophage recruitment to and inflammatory cytokine production at the tumor site. Conclusions: These data are consistent with estrogen modulation of the inflammatory response as a contributing factor in estrogen-stimulated growth of an ER-negative tumor.This effect on the host innate immune response was mediated by ER-a.

Transfection of tumor cells with a vector containing the entire coding sequence of human interleukin-2 (hIL-2) was previously shown to convert the tumorigenic murine fibrosarcoma line CMS-5 into a non-tumorigenic line. The failure of the IL-2-secreting tumor to grow in conventional (immunocompetent) mice was attributed to the activation of CD8+ T cells that exhibited tumor specificity and memory. In order to determine whether or not the IL-2 produced by the tumor may be activating tumor cytotoxic effector cells other than B or T cells we have repeated this study using immunodeficient SCID and SCID-beige mice as syngeneic tumor recipients. In contrast to the rapid growth of the wild-type tumor, the hIL-2-transfected cells (N2A/IL2/CMS5) did not grow, or grew more slowly and regressed, in the mice that lack functional B and T cells. The inhibition of tumor growth associated with the local release of IL-2 was reversed in mice treated with antiasialo-GM1 antibodies specific for natural killer (NK) lineage cells. In contrast to the studies with conventional mice, the IL-2-dependent effector cells in the immunodeficient mice exhibited no evidence of memory. In vitro analysis of spleen cells from tumor-bearing mice revealed the presence of effector cells able to lyse YAC-1 target cells as well as the wild-type CMS-5 and the IL-2-transfected variant tumor lines but unable to lyse P815 cells. The pattern of selective target cell killing and the kinetics of killing were indistinguishable from those observed using tumor necrosis factor alpha (TNF alpha) the mediator associated with natural cytotoxicity cell killing of tumor cells. Histopathology of the IL-2-secreting tumors in SCID mice reveals the presence of infiltrating lymphoid cells and macrophages that were not observed in the CMS-5 tumors. Consistent with the notion that the tumor killing in the SCID mice was mediated by TNF alpha, mice bearing IL-2-secreting tumors had elevated levels of serum TNF alpha and little or no effector cell activity, or TNF alpha was found in tumor-bearing mice treated with anti-asialo-GM1 antibody. The results indicate that the cytokine-induced tumor regression observed in the IL-2-transfected tumors is a more complex phenomenon than previously recognized and one that is mediated by effector cells of the NK cell and/or monocyte/macrophage lineages, in addition to CD8+ T cells.

Human villous adenomas are thought to represent premalignancies that subsequently give rise to colorectal adenocarcinomas. Currently there is no in vivo model in which to study the dedifferentiation and malignant transformation of these tumors. We establish here that human villous adenomas can be successfully engrafted into severe combined immunodeficient (scid) mice. Furthermore, these xenografts remain viable for up to 18 mo after either a subcutaneous or intraperitoneal inoculation of the human tissue. Tumors grew slowly and secreted a clear mucinous fluid. Examination of the tumors histologically at 1, 4, and 12 mo after implantation revealed that the villous polypoid structure was maintained and islands of atypical cells were observed within pockets of mucin surrounding the adenomatous tissue. No gross or histologic evidence of malignancy was detected throughout the 20-mo observation period. The human identity of the cells in the graft was confirmed by DNA in situ hybridization with a human-specific probe. We conclude that the human-scid xenograft described here represents a viable animal model with which to study the potential malignant dedifferentiation of villous adenomas over a prolonged period of time and to evaluate the possible contribution of selected oncogenic vectors on the malignant transformation of these adenomas. (J. Clin. Invest. 1994Invest. . 94:2153Invest. -2157

IntroductionGastric cancer is one of the most common malignant tumor, and gastric cancer is the second most common cause of cancer mortality worldwide. Although chemotherapy is one of the most important treatment options for gastric cancer, and could improve the overall survival rate and quality of live, one significant reason for its failure is multidrug resistance (MDR).AimTo study the effect of tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) combined with chemotherapeutic drug cisplatin (DDP) on the expression of multidrug resistance gene 1 (MDR1) in the gastric cancer cell line SGC-7901/VCR.Material and methodsSGC-7901/VCR cells were cultured with DDP and TRAIL in various concentrations. The apoptosis rate was separately measured by a flow cytometer in DDP (sub-toxic dose) alone, TRAIL (200 µg/l) alone and in a combination of the two. Expression levels of MDR1 mRNA and P-glycoprotein (P-gp) were detected by RT-PCR and ELISA analysis, respectively.ResultsThe apoptosis rate in the combination group was significantly higher than that in the other groups (p < 0.05). According to the results of RT-PCR and ELISA, the expressions of MDR1 mRNA and P-gp in the combination group were statistically significant different compared with other groups (p < 0.05).ConclusionsThe combination of TRAIL with DDP could reverse MDR phenotype in gastric cancer cell line SGC7901/VCR. The mechanism may be involved in the down-regulation of MDR1 mRNA and P-gp, which may play an essential role in overcoming the chemotherapeutic resistance of gastric cancer cells. This study indicates that a combination of chemotherapy and TRAIL may be an effective strategy to treat MDR gastric cancer.