Cloning and characterization of a novel member of the transforming growth factor-beta/bone morphogenetic protein family

Adaptive induction of growth differentiation factor 15 attenuates endothelial cell apoptosis in response to high glucose stimulus

Growth differentiation factor 15 (GDF15), a direct target gene of p53, is a multifunctional member of the TGF-β/BMP superfamily. GDF15 can be induced and is implicated as a key secretory cytokine in response to multiple cellular stimuli. Accumulating evidence indicates that GDF15 is associated with the development and prognosis of diabetes mellitus, while whether GDF15 can be induced by high glucose is unknown. In the present study, we revealed that high glucose could induce GDF15 expression and secretion in cultured human umbilical vein endothelial cells in a ROS- and p53-dependent manner. Inhibition of high glucose-induced GDF15 expression by siRNA demonstrated that adaptively induced GDF15 played a protective role against high glucose-induced human umbilical vein endothelial cell apoptosis via maintaining the active state of PI3K/Akt/eNOS pathway and attenuating NF-κB/JNK pathway activation. The protective effects of GDF15 were probably achieved by inhibiting ROS overproduction in high glucose-treated human umbilical vein endothelial cells in a negative feedback manner. Our results suggest that high glucose can promote GDF15 expression and secretion in human umbilical vein endothelial cells, which in turn attenuates high glucose-induced endothelial cell apoptosis.

The diverse roles of nonsteroidal anti-inflammatory drug activated gene (NAG-1/GDF15) in cancer

Nonsteroidal anti-inflammatory drug (NSAID) activated gene-1, NAG-1, is a divergent member of the transforming growth factor-beta (TGF-β) superfamily that plays a complex but poorly understood role in several human diseases including cancer. NAG-1 expression is substantially increased during cancer development and progression especially in gastrointestinal, prostate, pancreatic, colorectal, breast, melanoma, and glioblastoma brain tumors. Aberrant increases in the serum levels of secreted NAG-1 correlate with poor prognosis and patient survival rates in some cancers. In contrast, the expression of NAG-1 is up-regulated by several tumor suppressor pathways including p53, GSK-3β, and EGR-1. NAG-1 expression is also induced by many drugs and dietary compounds which are documented to prevent the development and progression of cancer in mouse models. Studies with transgenic mice expressing human NAG-1 demonstrated that the expression of NAG-1 inhibits the development of intestinal tumors and prostate tumors in animal models. Laboratory and clinical evidence suggest that NAG-1, like other TGF-β family members, may have different or pleiotropic functions in the early and late stages of carcinogenesis. Upon understanding the molecular mechanism and function of NAG-1 during carcinogenesis, NAG-1 may serve as a potential biomarker for the diagnosis and prognosis of cancer and a therapeutic target for the inhibition and treatment of cancer development and progression.

Growth differentiation factor-15 upregulates interleukin-6 to promote tumorigenesis of prostate carcinoma PC-3 cells

Growth differentiation factor-15 (GDF15), a member of the transforming growth factor-β superfamily, is associated with human cancer progress. We evaluated the role GDF15 plays in tumorigenesis of prostate carcinoma PC-3 cells. Results from real-time RT-PCR and ELISA revealed that expression of GDF15 was approximately threefold higher in LNCaP cells than in PC-3 cells. Other prostate cell lines (PZ-HPV-7, CA-HPV-10, and DU145 cells) expressed extremely low levels of GDF15. Stable overexpression of GDF15 in PC-3 cells enhanced the degree of cell proliferation and invasion as shown in the (3)H-thymidine incorporation assay and in the Matrigel invasion assay respectively. Soft agar assays and xenograft animal studies indicated that overexpression of GDF15 in PC-3 cells increased tumorigenesis in vitro and in vivo. Results from RT-PCR, immunoblot, and reporter assays revealed that overexpression of GDF15 resulted in decreased expression of maspin and upregulation of interleukin-6 (IL6), matriptase, and N-myc downstream-regulated gene 1 (NDRG1) expression. Further studies revealed that overexpression of IL6 enhanced GDF15 expression in LNCaP cells while knockdown of IL6 blocked the expression of GDF15 in PC-3 cells, suggesting that expression of GDF15 is upregulated by IL6. This study demonstrated that expression of GDF15 induces cell proliferation, invasion, and tumorigenesis of prostate carcinoma PC-3 cells. The enhancement of tumorigenesis and invasiveness of prostate carcinoma cells that stably overexpress GDF15 may be caused by the dysregulation of maspin, matriptase, and IL6 gene expression. The expression of GDF15 and IL6 is controlled via a positive feedback loop in PC-3 cells.

Expression of NSAID-activated gene-1 by EGCG in head and neck cancer: involvement of ATM-dependent p53 expression

Epigallocatechin-3-gallate (EGCG), a major polyphenolic constituent of green tea, possesses remarkable chemopreventive and therapeutic potential against various types of cancer, including head and neck squamous cell carcinoma (HNSCC). However, the molecular mechanism involved is not completely understood. Nonsteroidal anti-inflammatory drug-activated gene-1 (NAG-1), a transforming growth factor β superfamily protein, is shown to be induced by several antitumorigenic compounds and to exhibit proapoptotic and antitumorigenic activities. In this report, we demonstrate that EGCG transcriptionally induced the expression of NAG-1 during EGCG-induced apoptosis of HNSCC cells. Reporter assays, using the luciferase constructs containing the NAG-1 promoter, demonstrate that p53 is required for EGCG-mediated activation of NAG-1. Overexpression of NAG-1 enhanced the apoptotic effect of EGCG, whereas suppression of NAG-1 expression by small interfering RNA attenuated EGCG-induced apoptosis in HNSCC cells. Subsequently, we found that ataxia-telangiectasia mutated (ATM) plays an important role in activating these proapoptotic proteins (NAG-1 and p53) and cell cycle inhibitor (p21). Furthermore, EGCG significantly inhibited tumor formation as assessed by xenograft models, and this result is accompanied with induction of apoptotic cells and NAG-1 expression in tumor tissue samples. Taken together, these results demonstrate for the first time that EGCG induces apoptosis via ATM/p53-dependent NAG-1 expression in HNSCC, providing an additional mechanistic explanation for the apoptotic activity of EGCG.

Differentiated embryo-chondrocyte expressed gene 1 regulates p53-dependent cell survival versus cell death through macrophage inhibitory cytokine-1

Activation of p53 upon DNA damage induces an array of target genes, leading to cell cycle arrest and/or apoptosis. However, the mechanism by which the cell fate is controlled by p53 remains to be clarified. Previously, we showed that DEC1, a basic helix-loop-helix transcription factor and a target of p53, is capable of inducing cell cycle arrest and mediating DNA damage-induced premature senescence. Here, we found that ectopic expression of DEC1 inhibits, whereas knockdown of DEC1 enhances, DNA damage-induced cell death. Surprisingly, we showed that the anti-cell-death activity of DEC1 is p53 dependent, but DEC1 does not directly modulate p53 expression. Instead, we showed that DEC1 inhibits the ability of p53 to induce macrophage inhibitory cytokine-1 (MIC-1), but not other prosurvival/proapoptotic targets, including p21 and Puma. Importantly, we showed that upon binding to their respective response elements on the MIC-1 promoter, DEC1 and p53 physically interact on the MIC-1 promoter via the basic helix-loop-helix domain in DEC1 and the tetramerization domain in p53, which likely weakens the DNA-binding activity of p53 to the MIC-1 promoter. Finally, we found that depletion of MIC-1 abrogates the ability of DEC1 to attenuate DNA damage-induced cell death. Together, we hypothesize that DEC1 controls the response of p53-dependent cell survival vs. cell death to a stress signal through MIC-1.

The H6D variant of NAG-1/GDF15 inhibits prostate xenograft growth in vivo

BACKGROUND

Non-steroidal anti-inflammatory drug-activated gene (NAG-1), a divergent member of the transforming growth factor-beta superfamily, has been implicated in many cellular processes, including inflammation, early bone formation, apoptosis, and tumorigenesis. Recent clinical studies suggests that a C to G single nucleotide polymorphism at position 6 (histidine to aspartic acid substitution, or H6D) of the NAG-1 protein is associated with lower human prostate cancer incidence. The objective of the current study is to investigate the activity of NAG-1 H6D variant in prostate cancer tumorigenesis in vivo.

METHODS

Human prostate cancer DU145 cells expressing the H6D NAG-1 or wild-type (WT) NAG-1 were injected subcutaneously into nude mice and tumor growth was monitored. Serum and tumor samples were collected for subsequent analysis.

RESULTS

The H6D variant was more potent than the WT NAG-1 and inhibited tumor growth significantly compared to control mice. Mice with tumors expressing the WT NAG-1 have greater reduced both body weight and abdominal fat than mice with H6D variant tumors suggesting different activities of the WT NAG-1 and the H6D NAG-1. A significant reduction in adiponectin, leptin, and IGF-1 serum levels was observed in the tumor-bearing mice with a more profound reduction observed with expression of H6D variant. Cyclin D1 expression was suppressed in the tumors with a dramatic reduction observed in the tumor expressing the H6D variant.

CONCLUSION

Our data suggest that the H6D variant of NAG-1 inhibits prostate tumorigenesis by suppressing IGF-1 and cyclin D1 expression but likely additional mechanisms are operative.

Tolfenamic acid induces apoptosis and growth inhibition in head and neck cancer: involvement of NAG-1 expression

Nonsteroidal anti-inflammatory drug-activated gene-1 (NAG-1) is induced by nonsteroidal anti-inflammatory drugs and possesses proapoptotic and antitumorigenic activities. Although tolfenamic acid (TA) induces apoptosis in head and neck cancer cells, the relationship between NAG-1 and TA has not been determined. This study investigated the induction of apoptosis in head and neck cancer cells treated by TA and the role of NAG-1 expression in this induction. TA reduced head and neck cancer cell viability in a dose-dependent manner and induced apoptosis. The induced apoptosis was coincident with the expression of NAG-1. Overexpression of NAG-1 enhanced the apoptotic effect of TA, whereas suppression of NAG-1 expression by small interfering RNA attenuated TA-induced apoptosis. TA significantly inhibited tumor formation as assessed by xenograft models, and this result accompanied the induction of apoptotic cells and NAG-1 expression in tumor tissue samples. Taken together, these results demonstrate that TA induces apoptosis via NAG-1 expression in head and neck squamous cell carcinoma, providing an additional mechanistic explanation for the apoptotic activity of TA.

COX inhibitors directly alter gene expression: role in cancer prevention?

Inflammation is an important contributor to the development and progression of human cancers. Inflammatory lipid metabolites, prostaglandins, formed from arachidonic acid by prostaglandin H synthases commonly called cyclooxygenases (COXs) bind to specific receptors that activate signaling pathways driving the development and progression of tumors. Inhibitors of prostaglandin formation, COX inhibitors, or nonsteroidal anti-inflammatory drugs (NSAIDs) are well documented as agents that inhibit tumor growth and with long-term use prevent tumor development. NSAIDs also alter gene expression independent of COX inhibition and these changes in gene expression also appear to contribute to the anti-tumorigenic activity of these drugs. Many NSAIDs, as illustrated by sulindac sulfide, alter gene expressions by altering the expression or phosphorylation status of the transcription factors specificity protein 1 and early growth response-1 with the balance between these two events resulting in increases or decreases in specific target genes. In this review, we have summarized and discussed the various genes altered by this mechanism after NSAID treatment and how these changes in expression relate to the anti-tumorigenic activity. A major focus of the review is on NSAID-activated gene (NAG-1) or growth differentiation factor 15. This unique member of the TGF-β superfamily is highly induced by NSAIDs and numerous drugs and chemicals with anti-tumorigenic activities. Investigations with a transgenic mouse expressing the human NAG-1 suggest it acts to suppress tumor development in several mouse models of cancer. The biochemistry and biology of NAG-1 were discussed as potential contributor to cancer prevention by COX inhibitors.

Inflammation-associated regulation of the macrophage inhibitory cytokine (MIC-1) gene in prostate cancer

Macrophage inhibitory cytokine-1 (MIC-1), also known as prostate-derived factor (PDF), is a molecule of the TGF-β superfamily and has been associated with the progression of various types of diseases including prostate cancer. Initially identified from activated macrophages, the MIC-1 gene may provide a potential link between inflammation and prostate cancer. In this context, we performed MIC-1 expression analysis using mouse prostate tissues to determine whether there was any correlation with age and inflammation. Reverse transcription PCR analysis on RNA samples isolated from prostate lobes from prostate-specific antigen transgenic mice of varying ages revealed that MIC-1 gene expression is extremely low to non-detectable in the prostate tissues obtained from young mice, while its expression increases in the prostate tissues harvested from elderly mice. Increased MIC-1 gene expression in the mouse prostate was found to be associated with an increased level of infiltrating lymphocytes. To confirm this observation, we showed that inflammation-associated cytokines (IL-1β and TNF-α) significantly upregulate the secretion of the MIC-1 protein in a human prostate cancer cell line (LNCaP cells), while cytokines IL-6 and granulocyte macrophage colony-stimulating factor were less effective. Taken together, these data indicated that inflammation-associated cytokines may play a critical role in the functional regulation of the MIC-1 gene in the early stages of prostate cancer development. More studies are required to understand the biological activity of MIC-1 gene regulation in the development and progression of prostate cancer.

Elevated plasma growth differentiation factor-15 correlates with lymph node metastases and poor survival in endometrial cancer

PURPOSE

The study objective was to investigate and validate plasma growth differentiation factor-15 (GDF-15) as a predictor of lymph node metastasis and a poor prognosis in primary endometrial cancer.

EXPERIMENTAL DESIGN

Plasma samples from 510 women treated for endometrial cancer in a primary investigation cohort (n = 44) and a secondary validation cohort (n = 466) were analyzed for GDF-15. Plasma from healthy premenopausal (n = 20) and postmenopausal (n = 20) women, women with borderline (n = 43), benign (n = 144), and malignant ovarian tumors (n = 125) were used for comparison.

RESULTS

Median plasma GDF-15 concentration for the endometrial cancer group was elevated (1,077 ng/L) as compared with pre- and postmenopausal controls (590 and 684 ng/L) and women with benign (591 ng/L) or borderline ovarian tumors (718 ng/L; all P < 0.001), but similar to the ovarian cancer group. In the large validation cohort of endometrial carcinomas, high plasma GDF-15 was significantly associated with International Federation of Gynecology and Obstetrics (FIGO) stage III/IV disease, nonendometrioid histology, high grade, older age, postmenopausal status, and lymph node metastases (all P ≤ 0.001). High GDF-15 was also an independent predictor of poor disease-specific and recurrence-free survival.

CONCLUSIONS

Based on findings indicated in a primary investigation set and confirmed in the large secondary validation set, we report for the first time plasma GDF-15 as a biomarker for endometrial cancer phenotype, including presence of lymph node metastasis and reduced survival. Its applicability as a predictor of metastatic nodes and in monitoring treatment of endometrial cancer needs to be further studied.

The role of NAG-1/GDF15 in the inhibition of intestinal polyps in APC/Min mice by sulindac

The antitumor effects of nonsteroidal anti-inflammatory drugs (NSAID) are assumed to be due to the inhibition of COX activity, but COX-independent mechanisms may also play an important role. NSAID-activated gene (NAG-1/GDF15) is induced by NSAIDs and has antitumorigenic activities. To determine the contribution of COX-2 inhibition and NAG-1/GDF15 expression to the prevention of colon carcinogenesis by NSAIDs, we evaluated several sulindac derivatives [des-methyl (DM)-sulindac sulfide and its prodrug DM-sulindac] that do not inhibit COX-2 activity. Sulindac sulfide and DM-sulindac induced the expression of NAG-1/GDF15 in HCT116 cells as determined by quantitative real-time PCR and Western blot. We fed APC/Min mice with 320 ppm of sulindac and doses of DM-sulindac. Only sulindac significantly inhibited tumor formation inAPC/Min mice. To determine the pharmacokinetic properties of sulindac and DM-sulindac in vivo, wild-type C57/B6 mice were fed with sulindac and DM-sulindac at 80, 160, and 320 ppm. High-performance liquid chromatography analysis revealed that the conversion of DM-sulindac to DM-sulindac sulfide (active form) was less efficient than the conversion of sulindac to sulindac sulfide (active form) in the mice. Lower levels of DM-sulindac sulfide accumulated in intestinal and colon tissues in comparison with sulindac sulfide. In addition, NAG-1/GDF15 was induced in the liver of sulindac-fed mice but not in the DM-sulindac-fed mice. Collectively, our results suggest that the tumor-inhibitory effects of sulindac in APC/Min mice may be due to, in part, NAG-1/GDF15 induction in the liver. Our study also suggests that pharmacologic properties should be carefully evaluated when developing drug candidates.

Activation of NAG-1 via JNK signaling revealed an isochaihulactone-triggered cell death in human LNCaP prostate cancer cells

Background

We explored the mechanisms of cell death induced by isochaihulactone treatment in LNCaP cells.

Methods

LNCaP cells were treated with isochaihulactone and growth inhibition was assessed. Cell cycle profiles after isochaihulactone treatment were determined by flow cytometry. Expression levels of cell cycle regulatory proteins, caspase 9, caspase 3, and PARP were determined after isochaihulactone treatment. Signaling pathway was verified by inhibitors pre-treatment. Expression levels of early growth response gene 1 (EGR-1) and nonsteroidal anti-inflammatory drug-activated gene 1 (NAG-1) were determined to investigate their role in LNCaP cell death. NAG-1 expression was knocked down by si-NAG-1 siRNA transfection. Rate of cell death and proliferation were obtained by MTT assay.

Results

Isochaihulactone caused cell cycle arrest at G2/M phase in LNCaP cells, which was correlated with an increase of p53 and p21 levels and downregulation of the checkpoint proteins cdc25c, cyclin B1, and cdc2. Bcl-2 phosphorylation and caspase activation were also observed. Isochaihulactone induced phosphorylation of c-Jun-N-terminal kinase (JNK), and JNK inhibitor partially reduced isochaihulactone-induced cell death. Isochaihulactone also induced the expressions of EGR-1 and NAG-1. Expression of NAG-1 was reduced by JNK inhibitor, and knocking down of NAG-1 inhibited isochaihulactone-induced cell death.

Conclusions

Isochaihulactone apparently induces G2/M cell cycle arrest via downregulation of cyclin B1 and cdc2, and induces cellular death by upregulation of NAG-1 via JNK activation in LNCaP cells.

Growth/differentiation factor-15 is an abundant cytokine in human seminal plasma

BACKGROUND

Transforming growth factor-β cytokines have various biological effects in female reproductive tissue, including modulation of inflammatory response and induction of immune tolerance to seminal antigens in the reproductive tract. However, no studies have analyzed the presence of growth/differentiation factor-15 (GDF-15/macrophage inhibitory cytokine-1) in seminal fluid or demonstrated the quantity and form of GDF-15, its possible role or the relationship between its concentration and semen quality.

METHODS

The form and the concentration of GDF-15 were determined in 53 seminal plasma samples of both fertile and infertile men by ELISA and western blot. The sperm cells of three volunteers were treated with recombinant GDF-15, and cell viability and apoptosis were assessed by flow cytometry. The effect of GDF-15 on vaginal epithelial cells and peripheral blood mononuclear cells (PBMCs) was analyzed by quantitative RT-PCR.

RESULTS

The GDF-15 concentration in seminal plasma ranged from 0.2 to 6.6 μg/ml as determined by ELISA. Western blot analysis revealed that GDF-15 is present in the active form. In vitro cultivation of sperm cells with GDF-15 did not affect their viability or rates of apoptosis; however, it did inhibit proliferation of PBMCs and induce expression of FOXP3 in CD4+CD25+ cells.

CONCLUSIONS

To the best of our knowledge, this is the first demonstration that GDF-15 is an abundant cytokine in seminal plasma, although its concentration is not associated with semen quality or the fertility/infertility status of the donors. Moreover, our data show that GDF-15 displays immunosuppressive characteristics.

Increased expression of growth differentiation factor-15 in systemic sclerosis-associated pulmonary arterial hypertension

BACKGROUND

Growth differentiation factor (GDF)-15 is a secreted member of the transforming growth factor-β cytokine superfamily. GDF-15 levels are elevated in the serum of patients with cardiovascular diseases. We hypothesized that GDF-15 levels would also be increased in the plasma and lung tissue of patients with systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH).

METHODS

GDF-15 levels were measured in plasma in subjects with SSc-PAH (n = 30) and compared with subjects with systemic sclerosis (SSc) without pulmonary arterial hypertension (PAH) (n = 24). Patients with idiopathic PAH (IPAH) (n = 44) and normal individuals (n = 13) served as control subjects. Immunohistochemistry and immunofluorescence assay identified GDF-15 protein in lung tissue from patients with SSc-PAH and IPAH.

RESULTS

Patients with SSc-PAH had significantly higher mean circulating levels of GDF-15 in plasma compared with patients with SSc without PAH (422.3 ± 369.5 pg/mL vs 108.1 ± 192.8 pg/mL, P = .004). GDF-15 levels correlated positively with estimated right ventricular systolic pressure on echocardiogram and plasma levels of the amino terminal propeptide form of brain natriuretic peptide. There was an inverse correlation between circulating GDF-15 and diffusing capacity of the lung for carbon monoxide (Dlco) and a positive correlation with the FVC to Dlco ratio on pulmonary function test. GDF-15 levels > 125 pg/mL were associated with reduced survival. GDF-15 protein expression was increased in lung tissue from patients with SSc-PAH.

CONCLUSIONS

GDF-15 may be a useful biomarker in PAH associated with SSc. Its presence in lung tissue may suggest a role in the pathology of the disease.

Divergent molecular mechanisms underlying the pleiotropic functions of macrophage inhibitory cytokine-1 in cancer

Multifunctional macrophage inhibitory cytokine-1, MIC-1, is a member of the transforming growth factor-beta (TGF-beta) superfamily that plays key roles in the prenatal development and regulation of the cellular responses to stress signals and inflammation and tissue repair after acute injuries in adult life. The stringent control of the MIC-1 expression, secretion, and functions involves complex regulatory mechanisms and the interplay of other growth factor signaling networks that control the cell behavior. The deregulation of MIC-1 expression and signaling pathways has been associated with diverse human diseases and cancer progression. The MIC-1 expression levels substantially increase in cancer cells, serum, and/or cerebrospinal fluid during the progression of diverse human aggressive cancers, such as intracranial brain tumors, melanoma, and lung, gastrointestinal, pancreatic, colorectal, prostate, and breast epithelial cancers. Of clinical interest, an enhanced MIC-1 expression has been positively correlated with poor prognosis and patient survival. Secreted MIC-1 cytokine, like the TGF-beta prototypic member of the superfamily, may provide pleiotropic roles in the early and late stages of carcinogenesis. In particular, MIC-1 may contribute to the proliferation, migration, invasion, metastases, and treatment resistance of cancer cells as well as tumor-induced anorexia and weight loss in the late stages of cancer. Thus, secreted MIC-1 cytokine constitutes a new potential biomarker and therapeutic target of great clinical interest for the development of novel diagnostic and prognostic methods and/or cancer treatment against numerous metastatic, recurrent, and lethal cancers.

Growth differentiation factor-15 as a prognostic biomarker in ovarian cancer

OBJECTIVES

There is a need for identification of new biomarkers improving our understanding, diagnosis, and follow-up of ovarian cancer. Growth differentiation factor-15 (GDF-15) is a member of the transforming growth factor-beta superfamily, and GDF-15 overexpression has been found in several cancer forms but has not been explored in ovarian cancer. The aim of the study was to explore preoperative plasma concentration and tissue expression of growth differentiation factor (GDF)-15 in ovarian tumors.

METHODS

GDF-15 concentration was measured by immunoradiometric assay in plasma samples from patients with invasive ovarian cancer (n=125), borderline ovarian tumor (BOT, n=43), and benign ovarian tumor (n=144), from healthy women (n=40), as well as in effusion samples (n=44) from women with advanced ovarian cancer. Sections of ovarian carcinoma (n=20), BOT (n=9), and cystadenoma (n=7) were immunostained for GDF-15.

RESULTS

Median plasma GDF-15 concentration was elevated in ovarian cancer as compared to healthy controls and women with benign ovarian tumors or BOT (p<0.001). GDF-15 plasma concentration correlated inversely with survival time and was an independent predictor of survival, after correction for FIGO stage and age (p=0.01). GDF-15 protein was cytoplasmatically expressed in serous tumor cells and detectable in high concentrations in effusion samples.

CONCLUSION

GDF-15 emerges as a new potential biomarker in ovarian cancer.

GDF-15 contributes to proliferation and immune escape of malignant gliomas

PURPOSE

Growth and differentiation factor (GDF)-15 is a member of the transforming growth factor (TGF)-beta family. GDF-15 is necessary for the maintenance of pregnancy but has also been linked to other physiologic and pathologic conditions.

EXPERIMENTAL DESIGN

The expression of GDF-15 in glioma cell lines was assessed by quantitative reverse transcriptase-PCR and immunoblot. GDF-15 levels in situ and in the peripheral blood of glioma patients were examined by immunohistochemistry and enzyme-linked immunosorbent assay, respectively. The effects of short hairpin RNA-mediated GDF-15 inhibition on proliferation and immunogenicity of SMA-560 glioma cells were investigated by [methyl-(3)H]thymidine incorporation and immune-mediated target cell lysis. The impact of GDF-15 on glioma growth in vivo was assessed in syngeneic mice.

RESULTS

GDF-15 is expressed by gliomas of different WHO grades as assessed by immunohistochemistry. The high expression of GDF-15 in tumor tissue translates into elevated GDF-15 serum levels in glioblastoma patients compared with healthy controls. GDF-15 mRNA and protein are also detectable in human and mouse glioma cells in vitro. Silencing of GDF-15 by RNA interference reduces the proliferation of malignant glioma cells. Immunologically, the depletion of glioma-derived GDF-15 enhances the susceptibility of mouse glioma cells towards syngeneic natural killer cells and splenocytes. This results in a reduced in vivo tumorigenicity and increased T-cell infiltration of GDF-15-deficient glioma cells in syngeneic mice.

CONCLUSIONS

Although previous studies focusing on ectopic overexpression of GDF-15 have proposed unclear or antitumorigenic effects of GDF-15 in glioma cells, we here show that GDF-15 at endogenous levels contributes to proliferation and immune escape of malignant gliomas in an immunocompetent host.

Macrophage inhibitory cytokine-1 transactivates ErbB family receptors via the activation of Src in SK-BR-3 human breast cancer cells

The function of macrophage inhibitory cytokine-1 (MIC-1) in cancer remains controversial, and its signaling pathways remain poorly understood. In this study, we demonstrate that MIC-1 induces the transactivation of EGFR, ErbB2, and ErbB3 through the activation of c-Src in SK-BR-3 breast cells. MIC-1 induced significant phosphorylation of EGFR at Tyr845, ErbB2 at Tyr877, and ErbB3 at Tyr1289 as well as Akt and p38, Erk1/2, and JNK mitogen-activated protein kinases (MAPKs). Treatment of SK-BR-3 cells with MIC-1 increased the phosphorylation level of Src at Tyr416, and induced invasiveness of those cells. Inhibition of c-Src activity resulted in the complete abolition of MIC-1-induced phosphorylation of the EGFR, ErbB2, and ErbB3, as well as invasiveness and matrix metalloproteinase (MMP)-9 expression in SK-BR-3 cells. Collectively, these results show that MIC-1 may participate in the malignant progression of certain cancer cells through the activation of c-Src, which in turn may transactivate ErbB-family receptors.

Overexpression of macrophage inhibitory cytokine-1 induces metastasis of human prostate cancer cells through the FAK-RhoA signaling pathway

An elevated level of macrophage inhibitory cytokine-1 (MIC-1) is reported in the sera of patients with metastatic prostate cancer compared with that of benign diseases and healthy adults. We investigated the mechanistic role of MIC-1 overexpression in the metastasis of prostate cancer cells. Our study showed a progressive increase in secretory MIC-1 production correlated with the increase in the metastatic potential of PC-3 and LNPCa prostate cancer metastatic variants. Further, the in vitro studies using 'loss-' and 'gain'-of-function approaches showed that ectopic overexpression of MIC-1 (PC-3-MIC-1) and forced downregulation of MIC-1(PC-3M-siMIC-1) enhanced and reduced the motility and invasiveness of these cells, respectively. Supporting our in vitro observations, all the mice orthotopically implanted with PC-3-MIC-1 cells developed metastasis compared with none in the PC-3-vector group. Our results showed that MIC-1 overexpression was associated with apparent changes in actin organization. In addition, an enhanced phosphorylation of focal adhesion kinase (FAK) and guanosine-5'-triphosphate (GTP)-bound RhoA was also seen; however, no significant change was observed in total FAK and RhoA levels in the PC-3-MIC-1 cells. Altogether, our findings show that MIC-1 has a role in prostate cancer metastasis, in part, by promoting the motility of these cells. Activation of the FAK-RhoA signaling pathway is involved in MIC-1-mediated actin reorganization, and thus, leads to an increase in the motility of prostate cancer cells.

Elevated levels of MIC-1/GDF15 in the cerebrospinal fluid of patients are associated with glioblastoma and worse outcome

For patients with brain tumors identification of diagnostic and prognostic markers in easy accessible biological material, such as plasma or cerebrospinal fluid (CSF), would greatly facilitate patient management. MIC-1/GDF15 (growth differentiation factor 15) is a secreted protein of the TGF-beta superfamily and emerged as a candidate marker exhibiting increasing mRNA expression during malignant progression of glioma. Determination of MIC-1/GDF15 protein levels by ELISA in the CSF of a cohort of 94 patients with intracranial tumors including gliomas, meningioma and metastasis revealed significantly increased concentrations in glioblastoma patients (median, 229 pg/ml) when compared with control cohort of patients treated for non-neoplastic diseases (median below limit of detection of 156 pg/ml, p < 0.0001, Mann-Whitney test). However, plasma MIC-1/GDF15 levels were not elevated in the matching plasma samples from these patients. Most interestingly, patients with glioblastoma and increased CSF MIC-1/GDF15 had a shorter survival (p = 0.007, log-rank test). In conclusion, MIC-1/GDF15 protein measured in the CSF may have diagnostic and prognostic value in patients with intracranial tumors.

Vitamin D and differentiation in cancer

This paper reviews the current understanding of the vitamin D-induced differentiation of neoplastic cells, which results in the generation of cells that acquire near-normal, mature phenotype. Examples of the criteria by which differentiation is recognized in each cell type are provided, and only those effects of 1alpha,25-dihydroxyvitamin D(3) (1,25D) on cell proliferation and survival that are associated with the differentiation process are emphasized. The existing knowledge, often fragmentary, of the signaling pathways that lead to vitamin D-induced differentiation of colon, breast, prostate, squamous cell carcinoma, osteosarcoma, and myeloid leukemia cancer cells is outlined. The important distinctions between the different mechanisms of 1,25D-induced differentiation that are cell-type and cell-context specific are pointed out where known. There is a considerable body of evidence that the principal human cancer cells can be suitable candidates for chemoprevention or differentiation therapy with vitamin D. However, further studies are needed to fully understand the underlying mechanisms in order to improve the therapeutic approaches.

Increased serum concentrations of macrophage inhibitory cytokine-1 in patients with obesity and type 2 diabetes mellitus: the influence of very low calorie diet

OBJECTIVE

Macrophage inhibitory cytokine-1 (MIC-1) is a novel regulator of energy homeostasis. We explored whether alterations in MIC-1 levels contribute to metabolic disturbances in patients with obesity and/or obesity and type 2 diabetes mellitus (T2DM).

DESIGN

We measured serum MIC-1 levels and its mRNA expression in subcutaneous and visceral adipose tissue of 17 obese nondiabetic women, 14 obese women with T2DM and 23 healthy lean women. We also explored the relationship of MIC-1 with anthropometric and biochemical parameters and studied the influence of 2-week very low calorie diet (VLCD) on serum MIC-1 levels.

METHODS

Serum MIC-1 levels were measured by ELISA and its mRNA expression was determined by RT-PCR.

RESULTS

Both obese and T2DM group had significantly elevated serum MIC-1 levels relative to controls. T2DM group had significantly higher serum MIC-1 levels relative to obese group. Serum MIC-1 positively correlated with body weight, body fat, and serum levels of triglycerides, glucose, HbAlc, and C-reactive protein and it was inversely related to serum high-density lipoprotein cholesterol. Fat mRNA MIC-1 expression did not significantly differ between lean and obese women but it was significantly higher in subcutaneous than in visceral fat in both groups. VLCD significantly increased serum MIC-1 levels in obese but not T2DM group.

CONCLUSION

Elevated MIC-1 levels in patients with obesity are further increased by the presence of T2DM. We suggest that in contrast to patients with cancer cachexia, increased MIC-1 levels in obese patients and diabetic patients do not induce weight loss.

Metabolism and regulation of gene expression by 4-oxoretinol versus all-trans retinoic acid in normal human mammary epithelial cells

We previously demonstrated that 4-oxoretinol (4-oxo-ROL) activated retinoic acid receptors (RARs) in F9 stem cells. We showed that 4-oxo-ROL inhibited the proliferation of normal human mammary epithelial cells (HMECs). To understand the mechanisms by which 4-oxo-ROL regulates HMEC growth we examined gene expression profiles following 4-oxo-ROL or all-trans retinoic acid (tRA). We also compared growth inhibition by tRA, 4-oxo-ROL, or 4-oxo-RA. All three retinoids inhibited HMEC proliferation. Gene expression analyses indicated that 4-oxo-ROL and tRA modulated gene expression in closely related pathways. The expression of many genes, e.g. ATP-binding cassette G1 (ABCG1); adrenergic receptorbeta2 (ADRB2); ras-related C3 botulinum toxin substrate (RAC2); and short-chain dehydrogenase/reductase 1 gene (SDR1) was changed after 4-oxo-ROL or tRA. Metabolism of these retinoids was analyzed by high-performance liquid chromatography (HPLC). In 1 microM tRA treated HMECs all of the tRA was found intracellularly, and tRA was the predominant intracellular retinoid. In 1 microM 4-oxo-ROL treated HMECs most 4-oxo-ROL was esterified to 4-oxoretinyl esters, no tRA was detected, and 4-oxo-ROL and 4-oxo-RA were observed intracellularly. In 1 microM 4-oxoretinoic acid (4-oxo-RA) treated HMECs little intracellular 4-oxo-RA was detected; most 4-oxo-RA was in the medium. Our results indicate that: (a) 4-oxo-ROL regulates gene expression and inhibits proliferation of HMECs; (b) 4-oxo-ROL and tRA regulate some of the same genes; (c) more tRA is found in cells, as compared to 4-oxoretinoic acid, when each drug is added at the same concentration in the medium; and (d) the mechanism by which 4-oxo-ROL exerts its biological activity does not involve intracellular tRA production.

Circulating and placental growth-differentiation factor 15 in preeclampsia and in pregnancy complicated by diabetes mellitus

Growth-differentiation factor 15 (GDF-15), a stress-responsive transforming growth factor-beta-related cytokine, is emerging as a new risk marker in patients with cardiovascular disease. We explored GDF-15 in preeclampsia and in diabetic pregnancies, because these conditions are associated with augmented risk for cardiovascular disease, both in mother and in offspring. Plasma from pregnant women (n=267; controls: n=59, preeclampsia: n=85, diabetes mellitus: n=112, and superimposed preeclampsia in diabetes mellitus: n=11), fetal plasma (n=72), and amniotic fluid (n=99) were analyzed by immunoassay for GDF-15. Placental GDF-15 mRNA and protein expression levels were analyzed by quantitative real-time PCR and immunoblots in 78 and 18 pregnancies, respectively. Conditioned media from preeclamptic (n=6) and control (n=6) villous placenta explants were analyzed by immunoassay for GDF-15. Median maternal GDF-15 concentration was elevated in those with diabetes mellitus, as compared with controls (91 549 versus 79 875 ng/L; P=0.02). Median GDF-15 concentration was higher in patients with preeclampsia than in controls in term maternal blood samples (127 061 versus 80 319 ng/L; P<0.001). In the fetal circulation and amniotic fluid, GDF-15 was elevated in preeclampsia and superimposed preeclampsia in diabetes mellitus, as compared with controls. GDF-15 placental mRNA expression was elevated in preeclampsia, as compared with controls (P=0.002). Placenta immunoblots confirmed a single GDF-15 protein band, and a time-dependent increase in GDF-15 protein was detected in the conditioned media. Our study is the first to show that GDF-15 is dysregulated, both in preeclampsia and in diabetic pregnancies. The mechanisms and diagnostic implications of these findings remain to be explored.

Expression of macrophage inhibitory cytokine-1 in prostate cancer bone metastases induces osteoclast activation and weight loss

BACKGROUND

Macrophage inhibitory cytokine-1 (MIC-1) belongs to the bone morphogenic protein/transforming growth factor-beta (BMP/TGF-beta) superfamily. Serum MIC-1 concentrations are elevated in patients with advanced prostate cancer. The effects of MIC-1 on prostate cancer bone metastases are unknown.

METHODS

In vitro effects of MIC-1 on osteoblast differentiation and activity were analyzed with alkaline phosphatase and mineralization assays; osteoclast numbers were counted microscopically. MIC-1 effects on TLR9 expression were studied with Western blotting. Human Du-145 prostate cancer cells were stably transfected with a cDNA encoding for mature MIC-1 or with an empty vector. The in vivo growth characteristics of the characterized cells were studied with the intra-tibial model of bone metastasis. Tumor associated bone changes were viewed with X-rays, histology, and histomorphometry. Bone formation was assayed by measuring serum PINP.

RESULTS

MIC-1 induced osteoblast differentiation and activity and osteoclast formation in vitro. These effects were independent of TLR9 expression, which was promoted by MIC-1. Both MIC-1 and control tumors induced mixed sclerotic/lytic bone lesions, but MIC-1 increased the osteolytic component of tumors. Osteoclast formation at the tumor-bone interface was significantly higher in the MIC-1 tumors, whereas bone formation was significantly higher in the control mice. At sacrifice, the mice bearing MIC-1 tumors were significantly lighter with significantly smaller tumors.

CONCLUSIONS

MIC-1 up-regulates TLR9 expression in various cells. MIC-1 stimulates both osteoblast and osteoclast differentiation in vitro, independently of TLR9. MIC-1 over-expressing prostate cancer cells that grow in bone induce osteoclast formation and cachexia.

Identification of macrophage inhibitory cytokine-1 in adipose tissue and its secretion as an adipokine by human adipocytes

Macrophage inhibitory cytokine-1 (MIC-1), a divergent member of the TGF-beta superfamily, is involved in the control of multiple cellular processes and mediates cachexia through the inhibition of appetite. Adipose tissue as an endocrine organ secretes proteins (adipokines) that regulate energy homeostasis and other cellular functions. This study investigated whether MIC-1 is expressed in adipose tissue and whether MIC-1 is a secretory product of adipocytes. Mouse and human adipose tissues were collected from different depots. 3T3-L1 preadipocytes and human preadipocytes were induced to differentiate into adipocytes in cell culture. MIC-1 mRNA was detected in the major mouse adipose depots (epididymal, perirenal, sc). In these depots, MIC-1 gene expression was evident in both isolated mature adipocytes and stromal-vascular cells. In 3T3-L1 adipocytes, MIC-1 mRNA was detected before and after differentiation. MIC-1 mRNA and protein secretion were evident in human preadipocytes as well as differentiated adipocytes. MIC-1 production by human adipocytes was stimulated by H(2)O(2) and 15d-prostaglandin J(2). In addition, recombinant MIC-1 increased adiponectin secretion by differentiated human adipocytes. MIC-1 mRNA and protein were also observed in human sc and visceral fat. MIC-1 mRNA levels were positively correlated with adiponectin mRNA. Moreover, MIC-1 mRNA was negatively associated with body mass index and body fat mass in human subjects. We conclude that MIC-1 is expressed in adipose tissue and secreted from adipocytes and is therefore a new adipokine. MIC-1 may have a paracrine role in the modulation of adipose tissue function and body fat mass.

Macrophage inhibitory cytokine MIC-1 is upregulated by short-wavelength light in cultured normal human dermal fibroblasts

To better understand dermal response to visible light, we used DNA microarray analysis to search genes induced by blue or near-UV light in normal human dermal fibroblasts. Of about 12800 transcripts analyzed, near-UV light most prominently upregulated the transcript level of Mic-1, a gene encoding a TGF-beta superfamily protein. Quantitative RT-PCR and immunoblot analyses revealed that mRNA and protein levels of Mic-1 were upregulated by both short-wavelength light but not by green or red light. These results suggest that the human dermis is a site for macrophage inhibitory cytokine-1 (MIC-1) production and that visible light activates a dermal transcription cascade. Considering the role of MIC-1 in immune regulation and appetite control, photic MIC-1 regulation is of physiological importance.

Influence of inflammation and aging on macrophage inhibitory cytokine-1 gene expression in rat ventral prostate

OBJECTIVES

We have previously reported that the macrophage inhibitory cytokine-1 (MIC-1) gene is downregulated in human symptomatic benign prostatic hyperplasia. The aim of this study was to investigate the histologic changes and MIC-1 gene expression in the prostate of young nonbacterial prostatitis model (Y-NBP) and aging rats.

METHODS

A total of 35 Wistar male rats, 13 weeks old, were castrated and subjected to (a) castration alone for 14 days, (b) Y-NBP-14d (0.25 mg/2 mL/kg beta-estradiol injection for 14 days), or (c) Y-NBP-30d (beta-estradiol injection for 30 days). A total of 5 male rats, 10 months old, were also analyzed. We used 21 male rats, 13 weeks old, who had undergone sham surgery as the controls. The ventral lobes of the prostate were histologically examined with Masson's trichrome staining or immunostaining using an anti-macrophage antibody. The MIC-1 mRNA levels were quantitatively assessed using real-time reverse transcriptase-polymerase chain reaction.

RESULTS

The MIC-1 gene mRNA levels in the castration alone, Y-NBP-14d, and Y-NBP-30d rat prostates were greater than those in the control rats (P < .005). In contrast, those of the 10-month-old rats were lower than those of the controls (P = .0093). The mean stroma-to-epithelium ratio in the Y-NBP-30d rats, 10-month-old rats, and 13-week-old controls was 1.28, 0.26, and 0.10, respectively (Y-NBP-30d vs 10-month-old rats, P = .0008; 10-month-old vs 13-week-old rats, P = .001). The number of infiltrating macrophages in the Y-NBP-14d, Y-NBP-30d, and 10-month-old rats was greater than that of the 13-week-old controls (P < .001).

CONCLUSIONS

Castration causes induction of MIC-1 gene expression. Estradiol treatment has little effect on MIC-1 gene expression but causes a significant increase in the stroma-to-epithelium ratio. The aging rat prostate is more similar to human benign prostatic hyperplasia than is the Y-NBP model in light of MIC-1 gene expression and histologic changes.

Macrophage inhibitory cytokine-1: possible bridge molecule of inflammation and prostate cancer

There is emerging evidence that inflammation may lead to prostate cancer development. Although inflammation is an essential response to injury or infection, chronic inflammation is harmful and causes tissue damage. Increasing evidence suggests that inflammation leads to the development of epithelial cancers; however, studies on inflammation-targeted genes that might contribute to the development of cancer are at the beginning stage. Here, we describe macrophage inhibitory cytokine-1, which provides a potential link between inflammation and prostate cancer. Understanding the regulation of macrophage inhibitory cytokine-1 in response to inflammation may have potential for novel therapeutic strategies.

p53 controls prostate-derived factor/macrophage inhibitory cytokine/NSAID-activated gene expression in response to cell density, DNA damage and hypoxia through diverse mechanisms

The p53 tumor suppressor modulates cellular response to stress through both transcriptional and post-transcriptional mechanisms. Elucidation of the downstream targets of p53 following cell stress will aid in our understanding of the pathways involved in cellular adaptation to stressful stimuli. Here, we demonstrate that the TGF-beta superfamily member, and putative tumor suppressor, prostate-derived factor (PDF)/NSAID-activated gene (NAG)-1/macrophage inhibitory cytokine (MIC)-1 is induced in LNCaP human prostate cancer cells following treatment with the DNA-damaging agent, doxorubicin, culture under hypoxic conditions and by the hypoxia mimetic, cobalt chloride. Additionally, PDF expression was induced by increasing cell density. Expression of dominant negative p53 in LNCaP cells blocked induction of PDF mRNA and protein demonstrating the requirement for functional p53 in PDF induction by these stimuli. DNA damage and hypoxia resulted in increased p53 protein accumulation indicating that PDF expression may be controlled by cellular levels of p53. We also show the requirement for de novo protein synthesis in PDF induction by hypoxia and DNA damage. Increased PDF mRNA stability in response to hypoxia and cobalt chloride, but not doxorubicin, indicates that p53-dependent induction of PDF expression occurs via diverse mechanisms. Thus, PDF may represent a novel target of p53 in response to cell stress.

Upregulation and secretion of macrophage inhibitory cytokine-1 (MIC-1) in gastric cancers

BACKGROUND

Macrophage inhibitory cytokine-1 (MIC-1), a distant member of the transforming growth factor (TGF)-beta superfamily, has been reported to be upregulated and secreted from several cancers. We examined MIC-1 expression and secretion in gastric cancers.

METHODS

MIC-1 mRNA and protein levels in cancer tissues and cell lines were analyzed by RT-PCR and Western blot. MIC-1 expression in cancer tissues and its secretion in serum were analyzed using immunohistochemistry and ELISA.

RESULTS

MIC-1 was significantly upregulated in gastric cancer tissues and cell lines. MIC-1 was secreted from gastric SNU620 cells and its levels in the serum of cancer patients were 10-fold higher than those of healthy controls. In addition, the staining of MIC-1 expression was strongly increased in metastatic gastric cancers.

CONCLUSIONS

MIC-1 was obviously overexpressed in gastric cancers and MIC-1 secretion into blood may be useful for the prediction of gastric cancer progression.

Modulation of bone morphogenetic protein-9 expression and processing by insulin, glucose, and glucocorticoids: possible candidate for hepatic insulin-sensitizing substance

Bone morphogenetic protein 9 (BMP-9), a member of the TGF-beta superfamily predominantly expressed in nonparenchymal liver cells, has been demonstrated to improve glucose homeostasis in diabetic mice. Along with this therapeutic effect, BMP-9 was proposed as a candidate for the hepatic insulin-sensitizing substance (HISS). Whether BMP-9 plays a physiological role in glucose homeostasis is still unknown. In the present study, we show that BMP-9 expression and processing is severely reduced in the liver of insulin-resistant rats. BMP-9 expression and processing was directly stimulated by in situ exposition of the liver to the combination of glucose and insulin and oral glucose in overnight fasted rats. Additionally, prolonged fasting (72 h) abrogated refeeding-induced BMP-9 expression and processing. Previous exposition to dexamethasone, a known inductor of insulin resistance, reduced BMP-9 processing stimulated by the combination of insulin and glucose. Finally, we show that neutralization of BMP-9 with an anti-BMP-9 antibody induces glucose intolerance and insulin resistance in 12-h fasted rats. Collectively, the present results demonstrate that BMP-9 plays an important role in the control of glucose homeostasis of the normal rat. Additionally, BMP-9 is expressed and processed in an HISS-like fashion, which is impaired in the presence of insulin resistance. BMP-9 regulation according to the feeding status and the presence of diabetogenic factors reinforces the hypothesis that BMP-9 might exert the role of HISS in glucose homeostasis physiology.

Regulation of growth differentiation factor 15 expression by intracellular iron

Growth differentiation factor 15 (GDF15) is a divergent member of the transforming growth factor-beta superfamily and has been identified in different contexts as a hypoxia-inducible gene product and as a molecule involved in hepcidin regulation. The biology of iron and oxygen is closely related, and known regulatory pathways involving hypoxia-inducible factor (HIF) and iron-regulatory proteins (IRPs) are responsive to both these stimuli. We therefore sought to characterize the regulation of GDF15 by iron and oxygen and to define the involvement or otherwise of HIF and IRP pathways. Here we show that GDF15 is strongly up-regulated by stimuli that deplete cells of iron and that this response is specifically antagonized by the reprovision of iron. GDF15 exhibits greater sensitivity to iron depletion than hypoxia, and responses to hypoxia and iron depletion are independent of HIF and IRP activation, suggesting a novel mechanism of regulation. We also report significant induction of serum GDF15 in iron-deficient subjects and after administration of an iron chelator to normal subjects. These findings indicate that GDF15 can be induced by pathophysiologic changes in iron availability, raising important questions about the mechanism of regulation and its role in iron homeostasis.

Effect of sulindac on apoptosis and related gene expression profile of human colon cancer cells

AIM: To observe the changes of cell apoptosis and gene expression profile of human colon carcinoma cell line Lovo after sulindac treatment.

METHODS: Transmission electron microscopy and flow cytometry were used to observe the apoptosis changes of LoVo cells 48 and 72 h after sulindac treatment; meanwhile, cDNA microarray was used to detect the genes differetially expressed in LoVo cells.

RESULTS: Apoptotic bodies were found and the apoptotic rates of LoVo cells increased greatly after treatment with 0.6, 0.9 and 1.2 mmol/L sulindac in comparison with those of control cells (48 h: 4.2 ± 1.04, 4.26 ± 0.28, 7.51 ± 2.09 vs 1.81 ± 0.91; 72 h: 6.21 ± 0.56, 7.48 ± 1.45, 10.40 ± 1.30 vs 2.06 ± 1.43; all P < 0.05). Hybridization with cDNA microarray containing 17101 genes screened 1013 differetially expressed genes, of which 178 genes (17.87%) were associated with cell apoptosis. Of the 178 genes, 82 were up-regulated while 96 were down-regulated.

CONCLUSION: Sulindac can induce apoptosis of LoVo cells, and its mechanism may attribute to up-regulation or down-regulation of some apoptosis-related genes.

Macrophage inhibitory cytokine-1 is overexpressed in malignant melanoma and is associated with tumorigenicity

The incidence of malignant melanoma has increased dramatically over the past four decades. Metastatic melanoma is associated with poor prognosis, as the current treatments do not have a significant impact on prolonging survival or decreasing mortality. We have identified a member of the transforming growth factor-beta superfamily, macrophage inhibitory cytokine (MIC)-1, which is highly expressed in melanoma cells. Of 53 melanoma cell lines that were examined for relative MIC-1 expression by western blot analysis, 35 (66%) showed significantly higher levels of MIC-1 compared to normal melanocytes. Primary melanoma biopsies (15 of 22) were found to contain cells expressing low levels of MIC-1 as determined by immunohistochemistry. In contrast, all metastatic melanoma biopsies examined (16 of 16) had strong expression of MIC-1. Expression of MIC-1 was found to be dependent on the mitogen-activated protein kinase pathway, and is a transcriptional target of the microphthalmia-associated transcription factor. Knockdown of MIC-1 expression using stable short-hairpin RNA in three melanoma cell lines showed a significant decrease in tumorigenicity (P<0.0001). These results indicate that MIC-1 may function to promote development of more aggressive melanoma tumors. MIC-1 may be suitable for development as a serum diagnostic and is a possible target for the treatment of metastatic melanoma.

The in vivo gene expression signature of oxidative stress

How higher organisms respond to elevated oxidative stress in vivo is poorly understood. Therefore, we measured oxidative stress parameters and gene expression alterations (Affymetrix arrays) in the liver caused by elevated reactive oxygen species induced in vivo by diquat or by genetic ablation of the major antioxidant enzymes CuZn-superoxide dismutase (Sod1) and glutathione peroxidase-1 (Gpx1). Diquat (50 mg/kg) treatment resulted in a significant increase in oxidative damage within 3-6 h in wild-type mice without any lethality. In contrast, treatment of Sod1(-/-) or Gpx1(-/-) mice with a similar concentration of diquat resulted in a significant increase in oxidative damage within an hour of treatment and was lethal, i.e., these mice are extremely sensitive to the oxidative stress generated by diquat. The expression response to elevated oxidative stress in vivo does not involve an upregulation of classic antioxidant genes, although long-term oxidative stress in Sod1(-/-) mice leads to a significant upregulation of thiol antioxidants (e.g., Mt1, Srxn1, Gclc, Txnrd1), which appears to be mediated by the redox-sensitive transcription factor Nrf2. The main finding of our study is that the common response to elevated oxidative stress with diquat treatment in wild-type, Gpx1(-/-), and Sod1(-/-) mice and in untreated Sod1(-/-) mice is an upregulation of p53 target genes (p21, Gdf15, Plk3, Atf3, Trp53inp1, Ddit4, Gadd45a, Btg2, Ndrg1). A retrospective comparison with previous studies shows that induction of these p53 target genes is a conserved expression response to oxidative stress, in vivo and in vitro, in different species and different cells/organs.

NCX 4040, an NO-donating acetylsalicylic acid derivative: efficacy and mechanisms of action in cancer cells

Non-steroidal anti-inflammatory drugs (NSAIDs) have repeatedly shown to be effective in tumor prevention, but important side-effects limit their wide clinical use. Nitric oxide-releasing derivatives (NO-NSAIDs) are a promising class of compounds synthesized by combining a classic NSAID molecule with an NO-releasing moiety to counteract side-effects. These new chemical entities exhibit a significantly higher activity and much lower toxicity with respect to the parental drug. In the present paper, we report the results obtained from in in vitro experimental systems aimed to evaluate the activity and mechanisms of action of the novel NO-releasing aspirin derivative, NCX 4040. The in vitro studies were carried out on a panel of human colon (LoVo, LoVo Dx, WiDr, LRWZ), bladder (HT1376, MCR), and pancreatic (Capan-2, MIA PaCa-2, T3M4) cancer cell lines. With regard to colon cancer, NCX 4040 activity was also investigated in vitro in combination with drugs currently used in clinical practice and was validated in vivo on tumor-bearing mice xenografted with the aforementioned colon cancer cell lines. The in vitro studies showed a high cytotoxic activity of NCX 4040 in all tumor histotypes and demonstrated the pivotal role of the NO component in drug activity. It was also observed that NCX 4040 exerts a pro-apoptotic activity via a mitochondria-dependent pathway. Moreover, the in vivo studies on xenografted mice further confirmed the antitumor efficacy and low toxicity of NCX 4040 in colon cancer and highlighted its role as sensitizing agent of oxaliplatin cytotoxicity.

Expression of nonsteroidal anti-inflammatory drug-activated gene-1 (NAG-1) inversely correlates with tumor progression in gastric adenomas and carcinomas

PURPOSE

The expression of nonsteroidal anti-inflammatory drug-activated gene-1 (NAG-1), one of TGF-beta superfamily gene, is reported to be responsible for NSAID-induced apoptosis. We analyzed NAG-1 expression in gastric cancer and adenoma to find out its clinical implication.

METHODS

Immunostaining was performed using standard procedures with antibody to NAG-1 on gastric tissue microarrays of tissue specimens obtained by gastrectomy. The immunoreactivity of normal and tumor tissues was graded as no, weak, moderate, and strong expression.

RESULTS

The NAG-1 expression was stronger in intestinal metaplasia and adenoma than normal gastric epithelium. 47 (74.6%) of 63 normal gastric epithelium showed no or weak expression, but 33 (56.9%) of 58 and 13 (86.7%) of 15 intestinal metaplsia and adenoma showed moderate or strong expression. Only NAG-1 expression in diffuse type gastric cancer was weaker than in normal gastric tissue. Compared to intestinal metaplasia, both intestinal and diffuse type gastric cancer showed weaker expression. The intensity of NAG-1 expression inversely correlated with tumor differentiation and T and N stage status. While only 1 (2.2%) of 45 T1 stage cases lacked NAG-1 expression, 27 (45.8%) of 59 T3 stage cases lacked NAG-1 expression. Likewise, in N0 stage tumors only 10 (15.4%) of 65 cases lacked NAG-1 expression, but 17 (63.0%) of 27 N3 cases lacked NAG-1 expression.

CONCLUSIONS

The NAG-1 was expressed strongly in intestinal metaplasia and adenoma, and inversely correlated to tumor stages. This interesting finding may provide new targets for chemoprevention and future development of drugs.

Macrophage inhibitory cytokine-1 activates AKT and ERK-1/2 via the transactivation of ErbB2 in human breast and gastric cancer cells

Macrophage inhibitory cytokine-1 (MIC-1) is a member of the transforming growth factor-beta superfamily, which is overexpressed in a variety of human cancers, including breast and gastric cancer. The function of MIC-1 in cancer remains controversial and its signaling pathways remain poorly understood. In this study, we demonstrate that MIC-1 induces the transactivation of ErbB2 in SK-BR-3 breast and SNU-216 gastric cancer cells. MIC-1 induced a significant phosphorylation of Akt and ERK-1/2, and also effected an increase in the levels of tyrosine phosphorylation of ErbB1, ErbB2 and ErbB3 in SK-BR-3 and SNU-216 cells. The treatment of these cells with AG825 and AG1478, inhibitors specific for ErbB2 tyrosine kinase, resulted in the complete abolition of MIC-1-induced Akt and ERK-1/2 phosphorylation. Furthermore, the small-interfering RNA-mediated downregulation of ErbB2 significantly reduced not only the phosphorylation of Akt and ERK-1/2 but also the invasiveness of the cells induced by MIC-1. Our results show that ErbB2 activation performs a crucial function in MIC-1-induced signaling pathways. Further investigations revealed that MIC-1 induced the expression of the hypoxia inducible factor-1alpha protein and the expression of its target genes, including vascular endothelial growth factor, via the activation of the mammalian target of rapamycin (mTOR) signaling pathway. Stimulation of SK-BR-3 with MIC-1 profoundly induces the phosphorylation of mTOR and its downstream substrates, including p70S6K and 4E-BP1. Collectively, these results show that MIC-1 may participate in the malignant progression of certain human cancer cells that overexpress ErbB2 through the transactivation of ErbB2 tyrosine kinase.

Effect of in vivo loss of GDF-15 on hepatocellular carcinogenesis

BACKGROUND

Growth/differentiation factor-15(GDF-15) is a divergent TGF-beta family member that is expressed following liver injury and carcinogen exposure. GDF-15 expression is highly associated with gastrointestinal cancer stage, size, and metastasis and has been implicated in inhibition of tumor growth and increased tumor invasiveness. The current study sought to determine the effect of GDF-15 ablation on the development of hepatocellular carcinoma (HCC) in vivo.

MATERIALS AND METHODS

Male mice genetically deleted for the gene encoding GDF-15 (Gdf15 (-/-) mice) and wild-type controls were exposed to the hepatocarcinogen diethylnitrosamine (DEN). Mice were killed at 6 months of age and their livers dissected and processed for histology. Tumor number and size relative to total liver area examined were determined.

RESULTS

At 6 months of age, tumors were identified in 16 of 20 (80%) Gdf15 (-/-) mice and 16 of 19 wild-type mice (84%). No significant difference in tumor-occupied area was observed in Gdf15 (-/-) mice versus wild-type mice. In addition, no difference in invasiveness was observed in HCC arising in Gdf15 (-/-) as compared to wild-type mice. In wild type mice strong immunohistochemical staining for GDF-15 was noted on small HCC foci, whereas a loss of GDF-15 expression was found in a number of advanced HCC tumors.

CONCLUSIONS

Although highly expressed in association with multiple gastrointestinal cancers, and lost in some advanced HCC, genetic ablation of GDF-15 has no apparent effect on HCC tumor formation rate, growth rate or invasiveness in diethylnitrosamine-induced HCC in vivo.

Study of molecular mechanisms of pro-apoptotic activity of NCX 4040, a novel nitric oxide-releasing aspirin, in colon cancer cell lines

Background

Despite numerous studies aimed at verifying the antitumor activity of nitric oxide-releasing nonsteroidal antiflammatory drugs (NO-NSAIDs), little is known about the molecular targets responsible for their antineoplastic properties. In the present study, we investigated the mechanisms underlying the cytotoxicity of NCX 4040, a novel NO-aspirin with promising antineoplastic action, in in vitro human colon cancer models.

Methods

The effect on tumor growth was evaluated in four human colon cancer cell lines (LoVo, LRWZ, WiDr and LoVo Dx) by sulforhodamine B assay, oxidative stress by immunohistochemistry, apoptosis by laddering assay, mitochondrial membrane potential (ΔΨ_m) by flow cytometry, and apoptosis- and chemoresistance-related markers by western-blot and real-time method, respectively. Prostaglandin E₂ levels were determined by ELISA.

Results

NCX 4040 produced a higher cytotoxic effect in all the cell lines than that produced by other NO donors tested. In particular, in LoVo and LRWZ cells, NCX 4040 induced a cytocidal effect and apoptosis through p53 and NAG-1 expression, an early ΔΨ_m collapse, and a sequential release of cytoplasmatic cytochrome c and caspase -9 and -3 active forms. 8-hydroxyguanine lesions, indicative of oxidative stress, were also observed. Conversely, in WiDr line, the drug caused a cytocidal effect, albeit not through apoptosis, and a concomitant increase in COX-2 activity. In LoVo Dx line, characterized by high levels drug resistance and DNA repair-related markers, only a cytostatic effect was observed, again in concomitance with the increase in COX-2 enzyme activity.

Conclusion

This study highlights the multiplicity of mechanisms involved in sensitivity or resistance to NCX 4040 and could provide useful indications for tailored therapy by identifying potentially drug-responsive tumors.

TAp63-dependent induction of growth differentiation factor 15 (GDF15) plays a critical role in the regulation of keratinocyte differentiation

Since p63-deficient mice display severe defects in formation of epidermis, p63 has been considered to be a multi-isoform p53 family member essential for epidermal development. However, it is still unclear how p63 could contribute to keratinocyte differentiation. In the present study, we have found that TAp63alpha is induced in association with the upregulation and a secretion of growth differentiation factor 15 (GDF15) during the keratinocyte differentiation of HaCaT cells bearing p53 mutation. Short interference RNA-mediated knockdown of the endogenous TAp63 resulted in a remarkable reduction of GDF15. Luciferase reporter assay and reverse transcription-PCR analysis demonstrated that enforced expression of TAp63alpha significantly increases the luciferase activity driven by GDF15 promoter and the expression of GDF15. Consistent with these results, the proximal p53/p63-binding site within the GDF15 promoter region was required for the TAp63alpha-mediated transcriptional activation of GDF15, and TAp63alpha was recruited onto this site. Furthermore, siRNA-mediated knockdown of the endogenous GDF15 permitted cell growth and inhibited the expression of the differentiation markers such as keratin 10 and involucrin in response to differentiation stimuli. Taken together, our present results provide a novel insight into understanding the molecular mechanisms behind TAp63alpha-mediated keratinocyte differentiation.

Activation of p53 by MEG3 non-coding RNA

MEG3 is a maternally expressed imprinted gene suggested to function as a non-coding RNA. Our previous studies suggest that MEG3 has a function of tumor suppression. The tumor suppressor p53 plays a central role in tumor suppression and mediates the functions of many other tumor suppressors. Therefore, we hypothesized that MEG3 functions through activation of p53. We found that transfection of expression constructs for MEG3 and its isoforms results in a significant increase in p53 protein levels and dramatically stimulates p53-dependent transcription from a p53-responsive promoter. Using this as the functional assay, we demonstrated that the open reading frames encoded by MEG3 transcripts are not required for MEG3 function, and the folding of MEG3 RNA is critical to its function, supporting the concept that MEG3 functions as a non-coding RNA. We further found that MEG3 stimulates expression of the growth differentiation factor 15 (GDF15) by enhancing p53 binding to the GDF15 gene promoter. Interestingly, MEG3 does not stimulate p21(CIP1) expression, suggesting that MEG3 can regulate the specificity of p53 transcriptional activation. p53 degradation is mainly mediated by the mouse double minute 2 homolog (MDM2). We found that MDM2 levels were down-regulated in cells transfected with MEG3, suggesting that MDM2 suppression contributes at least in part to p53 accumulation induced by MEG3. Finally, we found that MEG3 is able to inhibit cell proliferation in the absence of p53. These data suggest that MEG3 non-coding RNA may function as a tumor suppressor, whose action is mediated by both p53-dependent and p53-independent pathways.

NAG-1 up-regulation mediated by EGR-1 and p53 is critical for quercetin-induced apoptosis in HCT116 colon carcinoma cells

Quercetin, a flavonoid molecule ubiquitously present in nature, has multiple effects on cancer cells, including the inhibition of cell proliferation and migration. However, the responsible molecular mechanisms are not fully understood. We found that quercetin induces the expression of NAG-1 (Non-steroidal anti-inflammatory drug activated gene-1), a TGF-beta superfamily protein, during quercetin-induced apoptosis of HCT116 human colon carcinoma cells. Reporter assays using the luciferase constructs containing NAG-1 promoter region demonstrate that early growth response-1 (EGR-1) and p53 are required for quercetin-mediated activation of the NAG-1 promoter. Overexpression of NAG-1 enhanced the apoptotic effect of quercetin, but suppression of quercetin-induced NAG-1 expression by NAG-1 siRNA attenuated quercetin-induced apoptosis in HCT116 cells. Taken together, the present study demonstrates for the first time that quercetin induces apoptosis via NAG-1, providing a mechanistic basis for the apoptotic effect of quercetin in colon carcinoma cells.