The human homolog of the JE gene encodes a monocyte secretory protein

Heterotypic signaling of cancer-associated fibroblasts in shaping the cancer cell drug resistance

The context-dependent reciprocal interaction between the cancer cells and surrounding fibroblasts is imperative for regulating malignant potential, metabolic reprogramming, immunosuppression, and ECM deposition. However, recent evidence also suggests that cancer-associated fibroblasts induce chemoresistance in cancer cells to various anticancer regimens. Because of the protumorigenic function of cancer-associated fibroblasts, these stromal cell types have emerged as fascinating therapeutic targets for cancer. However, this notion was recently challenged by studies that targeted cancer-associated fibroblasts and highlighted the underlying heterogeneity by identifying a subset of these cells with tumor-restricting functions. Hence, it is imperative to understand the heterogeneity and heterotypic signaling of cancer-associated fibroblasts to target tumor-promoting signaling processes by sparing tumor-restricting ones. In this review, we discuss the heterogeneity and heterotypic signaling of cancer-associated fibroblasts in shaping drug resistance and also list the cancer-associated fibroblast-targeting therapeutics.

High endogenous CCL2 expression promotes the aggressive phenotype of human inflammatory breast cancer

Inflammatory Breast Cancer (IBC) is a highly aggressive malignancy with distinct clinical and histopathological features whose molecular basis is unresolved. Here we describe a human IBC cell line, A3250, that recapitulates key IBC features in a mouse xenograft model, including skin erythema, diffuse tumor growth, dermal lymphatic invasion, and extensive metastases. A3250 cells express very high levels of the CCL2 chemokine and induce tumors enriched in macrophages. CCL2 knockdown leads to a striking reduction in macrophage densities, tumor proliferation, skin erythema, and metastasis. These results establish IBC-derived CCL2 as a key factor driving macrophage expansion, and indirectly tumor growth, with transcriptomic analysis demonstrating the activation of multiple inflammatory pathways. Finally, primary human IBCs exhibit macrophage infiltration and an enriched macrophage RNA signature. Thus, this human IBC model provides insight into the distinctive biology of IBC, and highlights potential therapeutic approaches to this deadly disease.

Inflammatory breast cancer (IBC) is an aggressive form of breast cancer with a poor prognosis. Here the authors report the characterization of a human IBC cell line recapitulating the clinical and histopathological features of the human disease, and implicating its high level of CCL2 in macrophage infiltration and tumor progression.

Characterisation of urinary monocyte chemoattractant protein 1: Potential biomarker for patients with overactive bladder

Objective: To investigate urinary monocyte chemoattractant protein 1 (MCP-1) as a potential marker for idiopathic overactive bladder (OAB). This is a quantitative measurement of urinary MCP-1 to establish baseline normal values that could help in future index studies. Normalised urinary MCP-1 levels are measured in female patients with OAB and aged-matched controls. Severity of OAB symptoms is correlated to normalised urinary MCP-1 levels.

Patients and methods: Urinary MCP-1 levels were measured in 29 female patients with OAB and 10 normal female controls. The patients with OAB were either newly diagnosed or off any OAB oral therapy for at least 2 weeks. OAB symptoms were assessed using validated OAB questionnaires. Urinary MCP-1 levels were measured using enzyme-linked immunosorbent assay and normalised by urinary creatinine (Cr) levels.

Results: The baseline urinary MCP-1 levels in female patients with OAB were significantly higher than those of the controls, at a mean of 210.25 vs 48.02 pg/mg Cr (P < 0.001). Patients who had severe OAB bother symptoms had higher levels of urinary MCP-1 (r = 0.03), also patients with OAB-wet had higher levels of urinary MCP-1, at a mean (SEM) of 209.25 (30.5) vs OAB-dry 185.25 (10) pg/mg Cr (P < 0.001).

Conclusion: Urinary MCP-1 levels were higher in female patients with idiopathic OAB. The close association of urinary MCP-1 and OAB bother severity symptoms and OAB-wet suggest that inflammation plays a major role in the pathophysiological mechanisms underlying the sensitisation of bladder afferent nerves. Establishing urinary MCP-1 levels in patients with OAB hopefully will help future studies to confirm the correlation as a baseline and changes with treatments.

Abbreviations: BMI: body mass index; Cr: creatinine; MCP-1: monocyte chemoattractant protein 1; OAB: overactive bladder; OAB-q: Overactive Bladder Questionnaire; PPBC: Patient Perception of Bladder Condition; UI: urinary incontinence

Stromal cells in breast cancer as a potential therapeutic target

Breast cancer in the United States is the second most commonly diagnosed cancer in women. About 1 in 8 women will develop invasive breast cancer over the course of her lifetime and breast cancer remains the second leading cause of cancer-related death. In pursuit of novel therapeutic strategies, researchers have examined the tumor microenvironment as a potential anti-cancer target. In addition to neoplastic cells, the tumor microenvironment is composed of several critical normal cell types, including fibroblasts, vascular and lymph endothelial cells, osteoclasts, adipocytes, and immune cells. These cells have important roles in healthy tissue stasis, which frequently are altered in tumors. Indeed, tumor-associated stromal cells often contribute to tumorigenesis, tumor progression, and metastasis. Consequently, these host cells may serve as a possible target in anti-tumor and anti-metastatic therapeutic strategies. Targeting the tumor associated host cells offers the benefit that such cells do not mutate and develop resistance in response to treatment, a major cause of failure in cancer therapeutics targeting neoplastic cells. This review discusses the role of host cells in the tumor microenvironment during tumorigenesis, progression, and metastasis, and provides an overview of recent developments in targeting these cell populations to enhance cancer therapy efficacy.

The chemokine MCP-1 (CCL2) in the host interaction with cancer: a foe or ally?

Macrophages are one of the most abundant leukocyte populations infiltrating tumor tissues and can exhibit both tumoricidal and tumor-promoting activities. In 1989, we reported the purification of monocyte chemoattractant protein-1 (MCP-1) from culture supernatants of mitogen-activated peripheral blood mononuclear cells and tumor cells. MCP-1 is a potent monocyte-attracting chemokine, identical to the previously described lymphocyte-derived chemotactic factor or tumor-derived chemotactic factor, and greatly contributes to the recruitment of blood monocytes into sites of inflammatory responses and tumors. Because in vitro-cultured tumor cells often produce significant amounts of MCP-1, tumor cells are considered to be the main source of MCP-1. However, various non-tumor cells in the tumor stroma also produce MCP-1 in response to stimuli. Studies performed in vitro and in vivo have provided evidence that MCP-1 production in tumors is a consequence of complex interactions between tumor cells and non-tumor cells and that both tumor cells and non-tumor cells contribute to the production of MCP-1. Although MCP-1 production was once considered to be a part of host defense against tumors, it is now believed to regulate the vicious cycle between tumor cells and macrophages that promotes the progression of tumors.

Live fibroblast harvest reveals surface marker shift in vitro

Current methods for the isolation of fibroblasts require extended ex vivo manipulation in cell culture. As a consequence, prior studies investigating fibroblast biology may fail to adequately represent cellular phenotypes in vivo. To overcome this problem, we describe a detailed protocol for the isolation of fibroblasts from the dorsal dermis of adult mice that bypasses the need for cell culture, thereby preserving the physiological, transcriptional, and proteomic profiles of each cell. Using the described protocol we characterized the transcriptional programs and the surface expression of 176 CD markers in cultured versus uncultured fibroblasts. The differential expression patterns we observed highlight the importance of a live harvest for investigations of fibroblast biology.

Effects of tongxinluo on the neointima formation and expression of inflammatory cytokines in rats after carotid artery balloon injury

Objective:

Tongxinluo (TXL) is a traditional Chinese medicine (TCM). It is used to treat coronary heart disease and atherosclerosis. We investigated the effects of TXL on the neointima formation and expression of inflammatory cytokines in rats after carotid artery balloon injury.

Materials and Methods:

Male Sprague-Dawley rats were randomly divided into four groups: sham operation group (Sham, n = 15), balloon injury group treated with vehicle (Control, n = 15), TXL low-dose group treated with TXL of 0.5 g/kg/d (TXL-L, n = 15), and TXL high-dose group treated with TXL of 1.0 g/kg/d (TXL-H, n = 15). TXL was given by gavage daily. 14 days after injury’, the levels of serum nitric oxide (NO), endothelin-1 (ET-1), monocyte chemoattractant protein-1 (MCP-1), and soluble intercellular adhesion molecule-1 (sICAM-1) were evaluated. The morphology of carotid artery tissue was observed with hematoxylin-eosin staining. Expressions of MCP-1 and ICAM-1 in the artery were detected by real-time polymerase chain reaction (RT-PCR) and western blotting.

Results:

14 days after injury, a significant increase in concentrations of serum ET-1, MCP-1, and sICAM-1 (P < 0.05), as well as a significant decrease in NO serum level were observed in rats subjected to artery injury compared to the sham rats (P < 0.05). TXL significantly decreased ET-1, MCP-1 and sICAM-1 serum levels (P < 0.05), whereas significantly increased NO serum level compared with the control (P < 0.05). TXL significantly reduced the neointimal thickening at day14 after injury (P < 0.05). In addition, TXL significantly reduced mRNA and protein expressions of ICAM-1 and MCP-1 in injured artery (P < 0.05).

Conclusions:

This study demonstrates that TXL is effective in improving endothelial function, attenuating neointimal formation of artery after balloon injury, and reducing expression of inflammatory cytokine MCP-1 and ICAM-1. It may be a useful agent for protecting the artery against injury.

Vimentin is a target of PKCβ phosphorylation in MCP-1-activated primary human monocytes

OBJECTIVE AND DESIGN

We designed a study to detect downstream phosphorylation targets of PKCβ in MCP-1-induced human monocytes.

METHODS

Two-dimensional gel electrophoresis was performed for monocytes treated with MCP-1 in the presence or absence of PKCβ antisense oligodeoxyribonucleotides (AS-ODN) or a PKCβ inhibitor peptide, followed by phospho- and total protein staining. Proteins that stained less intensely with the phospho-stain, when normalized to the total protein stain, in the presence of PKCβ AS-ODN or the PKCβ inhibitor peptide, were sequenced.

RESULTS

Of the proteins identified, vimentin was consistently identified using both experimental approaches. Upon (32)P-labeling and vimentin immunoprecipitation, increased phosphorylation of vimentin was observed in MCP-1 treated monocytes as compared to the untreated monocytes. Both PKCβ AS-ODN and the PKCβ inhibitor reduced MCP-1-induced vimentin phosphorylation. The IP of monocytes with anti-vimentin antibody and immunoblotting with a PKCβ antibody revealed that increased PKCβ becomes associated with vimentin upon MCP-1 activation. Upon MCP-1 treatment, monocytes were shown to secrete vimentin and secretion depended on PKCβ expression and activity.

CONCLUSIONS

We conclude that vimentin, a major intermediate filament protein, is a phosphorylation target of PKCβ in MCP-1-treated monocytes and that PKCβ phosphorylation is essential for vimentin secretion. Our recently published studies have implicated vimentin as a potent stimulator of the innate immune receptor Dectin-1 as reported by Thiagarajan et al. (Cardiovasc Res 99:494-504, 2013). Taken together our findings suggest that inhibition of PKCβ regulates vimentin secretion and, thereby, its interaction with Dectin-1 and downstream stimulation of superoxide anion production. Thus, PKCβ phosphorylation of vimentin likely plays an important role in propagating inflammatory responses.

Regulation of MCP-1 chemokine transcription by p53

BACKGROUND

Our previous studies showed that the expression of the monocyte-chemoattractant protein (MCP)-1, a chemokine, which triggers the infiltration and activation of cells of the monocyte-macrophage lineage, is abrogated in human papillomavirus (HPV)-positive premalignant and malignant cells. In silico analysis of the MCP-1 upstream region proposed a putative p53 binding side about 2.5 kb upstream of the transcriptional start. The aim of this study is to monitor a physiological role of p53 in this process.

RESULTS

The proposed p53 binding side could be confirmed in vitro by electrophoretic-mobility-shift assays and in vivo by chromatin immunoprecipitation. Moreover, the availability of p53 is apparently important for chemokine regulation, since TNF-alpha can induce MCP-1 only in human keratinocytes expressing the viral oncoprotein E7, but not in HPV16 E6 positive cells, where p53 becomes degraded. A general physiological role of p53 in MCP-1 regulation was further substantiated in HPV-negative cells harboring a temperature-sensitive mutant of p53 and in Li-Fraumeni cells, carrying a germ-line mutation of p53. In both cases, non-functional p53 leads to diminished MCP-1 transcription upon TNF-alpha treatment. In addition, siRNA directed against p53 decreased MCP-1 transcription after TNF-alpha addition, directly confirming a crosstalk between p53 and MCP-1.

CONCLUSION

These data support the concept that p53 inactivation during carcinogenesis also affects immune surveillance by interfering with chemokine expression and in turn communication with cells of the immunological compartment.

Effects of synthetic monocyte chemotactic protein-1 fragment 65-76 on neointima formation after carotid artery balloon injury in rats

The effects of the synthetic monocyte chemotactic protein-1 (MCP-1) peptide fragment 65-76 (peptide X) on the development of neointima after balloon injury to the carotid artery were studied. The agent was given i.m. at a dose of 33 microg/kg once daily for 28 days after balloon injury. Animals given peptide showed significant suppression of neointima growth 4 and 7 days after lesioning, as indicated by morphometric analysis of sections of lesioned arteries. On days 14 and 28, there were no significant differences in neointima formation in rats given and not given peptide. Peptide administration was not accompanied by any changes in C-reactive peptide concentrations, leukocyte counts, or the population composition of peripheral blood lymphocytes. Use of synthetic peptide X as an inhibitor of leukocyte migration during angioplasty may, along with traditional treatments, decrease the risk of restenosis.

Antibody array-generated profiles of cytokine release from THP-1 leukemic monocytes exposed to different amphotericin B formulations

Cytokine antibody arrays were used to establish the profiles of cytokine release from THP-1 monocytes exposed to different amphotericin B (AMB) drug delivery systems. Fungizone (FZ) and Amphotec (ABCD) caused the release of significantly more inflammatory molecules and the release of inflammatory molecules at higher levels than either AmBisome (L-AMB) or Abelcet (ABLC) after 6 h of treatment. Specifically, tumor necrosis factor alpha (TNF-alpha), interleukin-8 (IL-8), GRO-(alphabetagamma), monocyte chemoattractant protein-1 (MCP-1), RANTES, IL-10, and IL-6 were detected and semiquantified with a chemiluminscence imaging system. TNF-alpha, IL-8, and MCP-1 were the most predominant; however, little if any TNF-alpha was present in ABLC- or L-AMB-treated cultures. The TNF- alpha and IL-8 levels determined by quantitative enzyme-linked immunosorbent assay correlated with the relative cytokine levels measured by using the antibody arrays. Although the viabilities of THP-l monocytes in all AMB-treated cultures were similar by trypan blue exclusion, the amount of lactic dehydrogenase released was significantly larger in FZ- and ABCD-treated cultures than in L-AMB- and ABLC-treated cultures, indicating more membrane perturbations with those formulations. Membrane cation channel formation was also measured in model cholesterol-containing large unilamellar vesicles to directly assess the ion channel formation ability of the system. Only FZ and ABCD induced significant ion currents at concentrations less than 1.5 x 10(-5) M. These results may help provide rationales for the immediate cytokine-mediated side effects observed with FZ and ABCD and the reduced side effects observed with L-AMB and ABLC.

Differential transcriptional regulation of the monocyte-chemoattractant protein-1 (MCP-1) gene in tumorigenic and non-tumorigenic HPV 18 positive cells: the role of the chromatin structure and AP-1 composition

The expression of the monocyte-chemoattractant-protein-1 (MCP-1) is closely linked with a non-tumorigenic phenotype in somatic cell hybrids made between the human papillomavirus type 18 (HPV 18) positive cervical carcinoma cell line HeLa and normal human fibroblasts. In contrast, MCP-1 transcription is absent in tumorigenic segregants derived from the same hybrids or in parental HeLa cells. Selectivity of MCP-1 transcription, which is regulated at the level of initiation of transcription, is mainly based on differences in the location and extension of DNAse I-hypersensitive regions (DHSR) at both ends of the gene. While TNF-alpha only moderately increases the sensitivity of pre-existing 5'-DHSRs, a 3'-end DHSR became strongly induced exclusively in non-malignant hybrids. DNA sequencing showed that the 3'-DHSR coincides with an additional AP-1 site located approximately 600 bp downstream of the polyadenylation site. Analyses of AP-1 composition revealed that MCP-1 is only expressed in those cells where jun-family members were mainly heterodimerized with the fos-related protein fra-1. In contrast, in tumorigenic cells the 1: 1 ratio between jun and fra-1 is disturbed and the MCP-1 gene is no longer expressed. Hence, alterations in the heterodimerization pattern of AP-1 and its selective accessibility to opened chromatin may represent a novel regulatory pathway in the regulation of chemokines in malignant and non-malignant HPV-positive cells.

Identification of a novel dexamethasone-sensitive RNA-destabilizing region on rat monocyte chemoattractant protein 1 mRNA

Glucocorticoids are potent anti-inflammatory agents widely used in the treatment of human disease. We have previously shown that the inflammatory cytokine monocyte chemoattractant protein 1 (MCP-1) is regulated posttranscriptionally by glucocorticoids in arterial smooth muscle cells (SMC). To elucidate the mechanism mediating this effect, in vitro-transcribed radiolabeled MCP-1 mRNA was incubated with cytoplasmic extracts from SMC and analyzed by gel electrophoresis. Extracts from SMC treated with platelet-derived growth factor (PDGF) did not degrade the transcripts for up to 3 h. In contrast, extracts from cells treated with 1 microM dexamethasone (Dex) alone or in combination with PDGF degraded the probe with a half-life of approximately 15 min. Dex had maximal effect at concentrations above 0.01 microM and was effective on both rat and human MCP-1 transcripts. By deletion analysis, the Dex-sensitive region of the MCP-1 mRNA was localized to the initial 224 nucleotides (nt) at the 5' end and did not involve an AU-rich sequence in the 3' untranslated end. The 224-nt region conferred Dex sensitivity to heterologous mRNA. These studies provide new insights into the molecular mechanisms underlying the effect of glucocorticoids on gene expression.

Differential Monocyte Chemoattractant Protein-1 and Chemokine Receptor 2 Expression by Murine Lung Fibroblasts Derived from Th1- and Th2-Type Pulmonary Granuloma Models

Recent studies suggest that monocyte chemoattractant protein-1 (MCP-1) is involved in fibrosis through the regulation of profibrotic cytokine generation and matrix deposition. Changes in MCP-1, C-C chemokine receptor 2 (CCR2), procollagen I and III, and TGF β were examined in fibroblasts cultured from normal lung and from nonfibrotic (i.e., Th1-type) and fibrotic (i.e., Th2-type) pulmonary granulomas. Th2-type fibroblasts generated 2-fold more MCP-1 than similar numbers of Th1-type or normal fibroblasts after 24 h in culture. Unlike normal and Th1-type fibroblasts, Th2-type fibroblasts displayed CCR2 mRNA at 24 h after IL-4 treatment. By flow cytometry, CCR2 was present on 40% of untreated Th2-type fibroblasts, whereas CCR2 was present on &lt;20% of normal and Th1-type fibroblasts after similar treatment. IL-4 increased the number of normal fibroblasts with cell-surface CCR2 but IFN-γ-treatment of normal and Th2-type fibroblasts significantly decreased the numbers of CCR2-positive cells in both populations. Western blot analysis showed that total CCR2 protein expression was markedly increased in untreated Th2-type fibroblasts compared with normal and Th1-type fibroblasts. IL-4 treatment enhanced CCR2 protein in Th1- and Th2-type fibroblasts whereas IFN-γ treatment augmented CCR2 protein in normal and Th1-type fibroblasts. All three fibroblast populations exhibited MCP-1-dependent TGF-β synthesis, but only normal and Th2-type fibroblasts showed a MCP-1 requirement for procollagen mRNA expression. Taken together, these findings suggest that lung fibroblasts are altered in their expression of MCP-1, TGF-β, CCR2, and procollagen following their participation in pulmonary inflammatory processes, and these changes may be important during fibrosis.

Platelet-derived growth factor-stimulated expression of the MCP-1 immediate-early gene involves an inhibitory multiprotein complex

We have demonstrated previously that the seven-nucleotide (nt) motif TTTTGTA (the heptamer) that is present within the proximal 3' untranslated sequences of numerous immediate-early genes is essential for platelet-derived growth factor (PDGF)-stimulated induction of the MCP-1 immediate-early gene. On this basis, the heptamer was suggested to be a conserved regulatory element involved in immediate-early gene expression, although its mechanism of action was unknown. Herein, we demonstrate that the heptamer functions to remove an inhibition of PDGF induction of MCP-1 maintained by two independently acting inhibitory elements present in the MCP-1 5' flanking sequences (designated I* elements). PDGF treatment relieves the I*-mediated inhibition of MCP-1 expression only if the heptamer is also present. One inhibitory element is contained within a 59-nt portion of MCP-1 5' flanking sequences and functions in an orientation-independent and heptamer-regulated manner. Significantly, proteins binding to two DNA sequences contribute to the formation of a single multiprotein complex on the 59-nt I* element. The I*-binding complex contains Sp3, an Sp1-like protein, and a novel DNA-binding protein. Moreover, the complex does not form on two 59-nt sequences containing mutations that reverse the inhibition of PDGF induction maintained by the wild-type I* element. We propose to call the multiprotein I*-binding complex a repressosome and suggest that it acts to repress PDGF-stimulated transcription of MCP-1 in the absence of the heptamer TTTTGTA.

A Complex Element Regulates IFN-γ-Stimulated Monocyte Chemoattractant Protein-1 Gene Transcription

Monocyte chemoattractant protein-1 (MCP-1) is induced in chronic osseous inflammation, and is temporally and spatially correlated with monocyte recruitment. We investigated the mechanism of MCP-1 regulation in a human osteoblastic cell line in response to IFN-γ, a potent mediator of the immune inflammatory response. Nuclear run-on and stability studies demonstrated that IFN-γ stimulated MCP-1 transcription and did not enhance mRNA stabilization. Using MCP-1 promoter/reporter gene constructs, we determined that IFN-γ-enhanced MCP-1 transcription is regulated by a 29-bp element located at −227 relative to the ATG start codon. This element contains a 13-bp CT-rich sequence (GCTTCCCTTTCCT) adjacent to a IFN-γ activation site (GAS). Since deletion of the CT sequence enhanced both the magnitude and duration of IFN-γ-stimulated, GAS-mediated transcription, we have termed it the IFN response-inhibitory sequence (IRIS). The combined IRIS/GAS sequence is highly conserved in mouse, rat, and bovine MCP-1 genes. In gel-shift assays, nuclear extracts from IFN-γ-stimulated osteoblastic cells formed two specific inducible bands with labeled IRIS/GAS DNA. Both bands were supershifted by anti-STAT1 Abs, but not by Abs to STAT2, p48(ISGF-3γ), IFN-regulatory factor-1, or IFN-regulatory factor-2. Formation of one of the bands required the presence of the IRIS moiety. IRIS/GAS DNA also formed a number of specific complexes with constitutively expressed factors, none of which were affected by the above Abs. These studies establish a mechanism for IFN-γ-stimulated MCP-1 expression and identify a complex element that regulates MCP-1 gene transcription.

Posttranslational Modifications Affect the Activity of the Human Monocyte Chemotactic Proteins MCP-1 and MCP-2: Identification of MCP-2(6–76) as a Natural Chemokine Inhibitor

Chemokines are important mediators in infection and inflammation. The monocyte chemotactic proteins (MCPs) form a subclass of structurally related C-C chemokines. MCPs select specific target cells due to binding to a distinct set of chemokine receptors. Recombinant and synthetic MCP-1 variants have been shown to function as chemokine antagonists. In this study, posttranslationally modified immunoreactive MCP-1 and MCP-2 were isolated from mononuclear cells. Natural forms of MCP-1 and MCP-2 were biochemically identified by Edman degradation and mass spectrometry and functionally characterized in chemotaxis and Ca2+-mobilization assays. Glycosylated MCP-1 (12 and 13.5 kDa) was found to be two- to threefold less chemotactic for monocytes and THP-1 cells than nonglycosylated MCP-1 (10 kDa). Natural, NH2-terminally truncated MCP-1(5–76) and MCP-1(6–76) were practically devoid of bioactivity, whereas COOH-terminally processed MCP-1(1–69) fully retained its chemotactic and Ca2+-inducing capacity. The capability of naturally modified MCP-1 forms to desensitize the Ca2+ response induced by intact MCP-1 in THP-1 cells correlated with their agonistic potency. In contrast, naturally modified MCP-2(6–76) was devoid of activity, but could completely block the chemotactic effect of intact MCP-2 as well as that of MCP-1, MCP-3, and RANTES. Carboxyl-terminally processed MCP-2(1–74) did retain its chemotactic potency. Although comparable as a chemoattractant, natural intact MCP-2 was found to be 10-fold less potent than MCP-1 in inducing an intracellular Ca2+ increase. It can be concluded that under physiologic or pathologic conditions, posttranslational modification affects chemokine potency and that natural MCP-2(6–76) is a functional C-C chemokine inhibitor that might be useful as an inhibitor of inflammation.

Hyaluronan (HA) fragments induce chemokine gene expression in alveolar macrophages. The role of HA size and CD44

Hyaluronan (HA) is a glycosaminoglycan constituent of extracellular matrix. In its native form HA exists as a high molecular weight polymer, but during inflammation lower molecular weight fragments accumulate. We have identified a collection of inflammatory genes induced in macrophages by HA fragments but not by high molecular weight HA. These include several members of the chemokine gene family: macrophage inflammatory protein-1alpha, macrophage inflammatory protein-1beta, cytokine responsive gene-2, monocyte chemoattractant protein-1, and regulated on activation, normal T cell expressed and secreted. HA fragments as small as hexamers are capable of inducing expression of these genes in a mouse alveolar macrophage cell line, and monoclonal antibody to the HA receptor CD44 completely blocks binding of fluorescein-labeled HA to these cells and significantly inhibits HA-induced gene expression. We also investigated the ability of HA fragments to induce chemokine gene expression in human alveolar macrophages from patients with idiopathic pulmonary fibrosis and found that interleukin-8 mRNA is markedly induced. These data support the hypothesis that HA fragments generated during inflammation induce the expression of macrophage genes which are important in the development and maintenance of the inflammatory response.

The cis-acting phorbol ester "12-O-tetradecanoylphorbol 13-acetate"-responsive element is involved in shear stress-induced monocyte chemotactic protein 1 gene expression

Vascular endothelial cells, serving as a barrier between vessel and blood, are exposed to shear stress in the body. Although endothelial responses to shear stress are important in physiological adaption to the hemodynamic environments, they can also contribute to pathological conditions--e.g., in atherosclerosis and reperfusion injury. We have previously shown that shear stress mediates a biphasic response of monocyte chemotactic protein 1 (MCP-1) gene expression in vascular endothelial cells and that the regulation is at the transcriptional level. These observations led us to functionally analyze the 550-bp promoter region of the MCP-1-encoding gene to define the cis element responding to shear stress. The shear stress/luciferase assay on the deletion constructs revealed that a 38-bp segment (-53 to -90 bp relative to the transcription initiation site) containing two divergent phorbol ester "12-O-tetradecanoylphorbol 13-acetate" (TPA)-responsive elements (TRE) is critical for shear inducibility. Site-specific mutations on these two sites further demonstrated that the proximal one (TGACTCC) but not the distal one (TCACTCA) was shear-responsive. Shear inducibility was lost after the mutation or deletion of the proximal site. This molecular mechanism of shear inducibility of the MCP-1 gene was functional in both the epithelial-like HeLa cells and bovine aortic endothelial cells (BAEC). In a construct with four copies of the TRE consensus sequences TGACTACA followed by the rat prolactin minimal promoter and luciferase gene, shear stress induced the reporter activities by 35-fold and 7-fold in HeLa cells and BAEC, respectively. The application of shear stress on BAEC also induced a rapid and transient phosphorylation of mitogen-activated protein kinases. Pretreatment of BAEC with TPA attenuated the shear-induced mitogen-activated protein kinase phosphorylation, suggesting that shear stress and TPA share a similar signal transduction pathway in activating cells. The present study provides a molecular basis for the transient induction of MCP-1 gene by shear stress.

A new platelet-derived growth factor-regulated genomic element which binds a serine/threonine phosphoprotein mediates induction of the slow immediate-early gene MCP-1

The MCP-1 chemokine gene belongs to a cohort of immediate-early genes that are induced with slower kinetics than c-fos. In this study, we identified a cluster of four platelet-derived growth factor (PDGF)-responsive elements within a 240-bp enhancer found in the distal 5' flanking MCP-1 sequences. Two of the elements bind one or more forms of the transcription factor NF-kappa B. We focused on the other two elements which are hitherto unreported, PDGF-regulated genomic motifs. One of these novel elements, detected as a 28-mer by DNase I footprinting, restores PDGF inducibility when added in two copies to a 5' truncated MCP-1 gene. A single copy of the second novel element, a 27-mer, restores PDGF inducibility to a 5' truncated MCP-1 gene. The 27-base element interacts with a PDGF-activated serine/threonine phosphoprotein that is detected only within the nucleus of PDGF-treated 3T3 cells. DNA binding of this phosphoprotein is activated by PDGF treatment with slow kinetics that match the time course of MCP-1 gene expression, and activation is not inhibited by cycloheximide. PDGF-activated binding to the 27-mer is shown to involve a single 30-kDa protein by UV-cross-linking analysis.

Fluid shear stress induces a biphasic response of human monocyte chemotactic protein 1 gene expression in vascular endothelium

The focal distribution of atherosclerotic lesions in the arterial tree is related to the local shear stress generated by blood flow, but the molecular basis of the atherogenic response of endothelial cells in these lesion-prone areas is still unclear. We report that shear stress mediates a biphasic response of monocyte chemotactic protein 1 (MCP-1) gene expression in vascular endothelial cells (EC). Northern blot analysis indicated that the level of MCP-1 mRNA in human umbilical vein EC (HUVEC) subjected to a shear stress of 16 dynes/cm2 (1 dyne = 10 microN) for 1.5 hr increased by 2- to 3-fold when compared with static cells. The MCP-1 gene expression decreased to the basal level at 4 hr and then declined further to become completely quiescent at 5 hr after the onset of shear. Once the gene expression was fully suppressed, it remained quiescent even after static incubation for 1.5 hr and would not respond to reshearing after this static incubation. However, if the postshearing incubation extended from 1.5 to 24 hr, the MCP-1 mRNA returned to the basal level and was then able to increase after the reapplication of shear stress. Nuclear run-on experiments showed that the shear-induced increased MCP-1 mRNA in HUVEC was regulated at the transcriptional level. By using cycloheximide, it was shown that de novo protein synthesis was not necessary for the induction of MCP-1 by shear stress. The biphasic response of MCP-1 gene expression was found in experiments in which the applied shear stress was 6, 16, or 32 dynes/cm2, and it was observed not only in HUVEC but also in HeLa cells, glioma cell lines, and skin fibroblasts. This in vitro study demonstrates that the response of MCP-1 gene to shear stress represents an immediate early gene activation and suggests that this gene is probably suppressed in EC that have been exposed to a constant shear stress.

Lysophosphatidylcholine transcriptionally induces growth factor gene expression in cultured human endothelial cells

Lysophosphatidylcholine (lyso-PC) is a major phospholipid component of atherogenic lipoproteins (e.g., oxidized LDL and beta-VLDL) and also can be generated through the action of leukocyte-secreted phospholipase A2 at sites of inflammation. We have previously reported that lyso-PC can activate cultured endothelia, resulting in the selective upregulation of adhesion molecules, such as vascular cell adhesion molecule-1 and intercellular adhesion molecule-1. In this study, we have found that lyso-PC increased steady state mRNA levels for two smooth muscle/fibroblast-directed growth factors, the A and B chains of PDGF and heparin-binding EGF-like protein (HB-EGF), in cultured human endothelial cells. Lyso-PC did not upregulate the expression of certain other inducible endothelial genes, including E-selectin, IL-8, or monocyte chemoattractant protein-1 in the same cells, in contrast to the coordinate pattern of activation typically observed with other stimuli, such as TNF alpha, bacterial endotoxin, or PMA. Nuclear runoff assays documented an increased transcriptional rate for the HB-EGF gene in lyso-PC-treated cells. Northern blot analyses, after actinomycin D treatment, further indicated that the increased amounts of mRNA for HB-EGF, PDGF A and B chains, and intercellular adhesion molecule-1 were not dependent upon message stabilization. We conclude that lyso-PC can induce growth factor gene expression in cultured endothelial cells and thus may contribute to the migration and proliferation of smooth muscle cells and fibroblasts in various response-to-injury settings in vivo.

Human monocyte colony-stimulating factor stimulates the gene expression of monocyte chemotactic protein-1 and increases the adhesion of monocytes to endothelial monolayers

The stimulation of the human umbilical vein endothelial cell (HUVEC) with recombinant human monocyte-derived colony-stimulating factor (MCSF) increased the gene expression of monocyte chemotactic protein (MCP-1). Northern blot analysis indicated that 50 U/ml of MCSF is the optimal concentration for this effect. The elevation of MCP-1 mRNA started as early as 1 h after stimulation and was maintained for at least 8 h. An increased MCP-1 level in MCSF-treated HUVEC was also demonstrated at the protein level by immunocytochemical staining using a polyclonal MCP-1-specific antibody. HUVEC activated by 50 U/ml of MCSF for 5 h showed a stronger immunofluorescence staining than control cells. Micropipette separation of THP-1 monocytes from HUVEC showed that the activation of both THP-1 and endothelium by MCSF led to an increase in the separation force by more than three times (36.2 +/- 6.7 x 10(-4) vs. 9.6 +/- 3.6 x 10(-4) dyn). An increased adhesiveness was also observed after MCSF activation of peripheral blood monocytes and HUVEC (16.7 +/- 2.7 x 10(-4) vs. 5.2 +/- 0.9 x 10(-4) dyn). The increased adhesive force in both systems was blocked by the use of anti-MCP-1 (5.5 +/- 0.8 x 10(-4) and 6.8 +/- 1.1 x 10(-4) dyn). Similar results were obtained in experiments in which only HUVEC, but not monocytes, were activated by MCSF. This increased adhesion of untreated monocytes to MCSF-activated HUVEC was also blocked by the addition of anti-MCP-1. In contrast, experiments in which only THP-1 or peripheral blood monocytes, but not HUVEC, were treated with MCSF did not show a significant increase of adhesion between these cells. These results indicate that MCSF augments monocyte-endothelium interaction primarily by its action on the endothelial cell and that this function is probably mediated through an increased expression of MCP-1. The MCSF/MCP-1-dependent adhesive mechanism might be operative in the arterial wall in vivo to lead to the trapping of the infiltrated monocyte-macrophage in the subendothelial space during atherogenesis.

Oxygen radicals as second messengers for expression of the monocyte chemoattractant protein, JE/MCP-1, and the monocyte colony-stimulating factor, CSF-1, in response to tumor necrosis factor-alpha and immunoglobulin G. Evidence for involvement of reduced nicotinamide adenine dinucleotide phosphate (NADPH)-dependent oxidase

The potential involvement of reactive oxygen species in the expression of genes involved in immune response was examined in mesangial cells. Tumor necrosis factor (TNF-alpha) and aggregated (aggr.) IgG increased mRNA levels for the monocyte chemoattractant protein, JE/MCP-1, and the colony-stimulating factor, CSF-1. Scavengers for free radicals such as di- and tetra-methylthiourea (DMTU and TMTU) attenuated the increase in mRNA levels in response to TNF-alpha and aggr. IgG. Generation of superoxide anion by xanthine oxidase and hypoxanthine increased mRNA levels of these genes, but exogenous H2O2 did not. Addition of NADPH to activate a membrane-bound NADPH-oxidase generated superoxide and caused a dose-dependent increase in mRNA levels and further enhanced the stimulation by TNF-alpha or aggr. IgG. An inhibitor of NADPH-dependent oxidase 4'-hydroxy-3'-methoxy-acetophenone attenuated the rise in mRNA levels in response to TNF-alpha and aggr. IgG. By nuclear run-on experiments TNF-alpha, aggr. IgG and NADPH increased the transcription rates for JE/MCP-1 and CSF-1, effects inhibited by TMTU. We conclude that generation of reactive oxygen species, possibly by NADPH-dependent oxidase, are involved in the induction of the JE/MCP-1 and CSF-1 genes by TNF-alpha and IgG complexes. The concerted expression of leukocyte-directed cytokines represents a general response to tissue injury.

Early and persistent induction of monocyte chemoattractant protein 1 in rat cardiac allografts

The early response gene for monocyte chemoattractant protein 1 (MCP-1) encodes a potent chemotactic factor that is specific for monocytes. To determine whether MCP-1 is involved in macrophage recruitment in cardiac allografts, we studied time-dependent MCP-1 gene and protein expression patterns in the heterotopic, Lewis to F-344 rat transplantation model (by reverse transcription-PCR and immunohistochemistry). There was a significant increase (8- to 12-fold) in MCP-1 gene transcripts in cardiac allografts compared with host hearts at 7, 14, and 28 days after transplantation. This induction was not observed with syngeneic transplants or hosts exposed to the same circulating cells and blood products. The MCP-1 gene product was expressed predominantly by mononuclear cells that double-stained with antimacrophage antibody (ED1) and localized to the interstitial and vascular spaces of the allografts. Immunocytochemical cell counting revealed significant increases in both MCP-1- and ED1-immunopositive cells in 7-, 14-, and 28-day allografts (in comparison with day 0 hearts). The absolute number of MCP-1-positive cells (5-7%) was lower than that of ED1-positive cells (25-34%) at all time points, suggesting that MCP-1-positive cells represent a subpopulation of activated macrophages. The persistent expression of MCP-1 in association with increased macrophage localization suggests that this inducible mediator contributes to the chronic inflammatory response following cardiac transplantation and that it may play a role in the pathogenesis of transplant arteriosclerosis.

The product of a novel growth factor-activated gene, fic, is a biologically active "C-C"-type cytokine

We have characterized a new member of the superfamily of proinflammatory peptides encoded by a growth factor-inducible gene, fic, previously isolated by differential screening of a cDNA library of mRNA from serum-stimulated NIH 3T3 cells. Immunoprecipitation analyses showed that the protein was rapidly induced following serum stimulation and secreted unglycosylated into the medium. The fic protein, FIC, shows highest sequence homology (57%) to human and rabbit monocyte chemoattractant protein 1 (MCP-1), an established monocyte activator. To determine the biological activity of FIC and to compare it with that of mouse MCP-1 (muMCP-1), both proteins were expressed in the baculovirus system. FIC and muMCP-1 were purified to near homogeneity by a two-step chromatography protocol. Both proteins elicited changes in intracellular calcium concentration in human monocytes. The effect was dependent on external Ca2+ and was inhibited by pretreatment of cells with pertussis toxin. FIC did not desensitize human monocytes to the three related cytokines muMCP-1, human MCP-1 (huMCP-1), and huMCP-2. However, pretreatment with muMCP-1 or huMCP-1, but not with huMCP-2, desensitized human monocytes to FIC. Specific binding of [125I]FIC was found in human monocytes, mouse monocytic cultured cells, and human endothelial cells but not in lymphocytes, neutrophils, or primary mouse fibroblasts. Scatchard analysis of the binding of [125I]FIC to human monocytes showed the presence of two classes of receptors, with apparent KdS of 1.2 and 7.7 nM and receptor numbers per cell of 2,400 and 6,300, respectively. FIC, muMCP-1, and huMCP-1 competed to the same extent for the binding of [125I]FIC to human monocytes, contrary to huMCP-2, which competed very ineffectively, if at all.

The product of a novel growth factor-activated gene, fic, is a biologically active "C-C"-type cytokine

We have characterized a new member of the superfamily of proinflammatory peptides encoded by a growth factor-inducible gene, fic, previously isolated by differential screening of a cDNA library of mRNA from serum-stimulated NIH 3T3 cells. Immunoprecipitation analyses showed that the protein was rapidly induced following serum stimulation and secreted unglycosylated into the medium. The fic protein, FIC, shows highest sequence homology (57%) to human and rabbit monocyte chemoattractant protein 1 (MCP-1), an established monocyte activator. To determine the biological activity of FIC and to compare it with that of mouse MCP-1 (muMCP-1), both proteins were expressed in the baculovirus system. FIC and muMCP-1 were purified to near homogeneity by a two-step chromatography protocol. Both proteins elicited changes in intracellular calcium concentration in human monocytes. The effect was dependent on external Ca2+ and was inhibited by pretreatment of cells with pertussis toxin. FIC did not desensitize human monocytes to the three related cytokines muMCP-1, human MCP-1 (huMCP-1), and huMCP-2. However, pretreatment with muMCP-1 or huMCP-1, but not with huMCP-2, desensitized human monocytes to FIC. Specific binding of [125I]FIC was found in human monocytes, mouse monocytic cultured cells, and human endothelial cells but not in lymphocytes, neutrophils, or primary mouse fibroblasts. Scatchard analysis of the binding of [125I]FIC to human monocytes showed the presence of two classes of receptors, with apparent KdS of 1.2 and 7.7 nM and receptor numbers per cell of 2,400 and 6,300, respectively. FIC, muMCP-1, and huMCP-1 competed to the same extent for the binding of [125I]FIC to human monocytes, contrary to huMCP-2, which competed very ineffectively, if at all.

A novel 7-nucleotide motif located in 3' untranslated sequences of the immediate-early gene set mediates platelet-derived growth factor induction of the JE gene

A cohort of the serum and growth factor regulated immediate-early gene set is induced with slower kinetics than c-fos. Two of the first immediate-early genes characterized as such, c-myc and JE, are contained within this subset. cis-acting genomic elements mediating induction of the slower responding subset of immediate-early genes have never been characterized. Herein we characterize two widely separated genomic elements which are together essential for induction of the murine JE gene by platelet-derived growth factor, serum, interleukin-1, and double-stranded RNA. One of these elements is novel in several regards. It is a 7-mer, TTTTGTA, found in the proximal 3' sequences downstream of the JE stop codon. The 3' element is position dependent and orientation independent. It does not function in polyadenylation, splicing, or destabilization of the JE transcript. Copies of the 7-mer or its inverse are found at comparable 3' sites in 25 immediate-early genes that encode transcription factors or cytokines. Given its general occurrence, the 7-mer may be a required cis-acting control element mediating induction of the immediate-early gene set.

Immunoglobulin E plus antigen challenge induces a novel intercrine/chemokine in mouse mast cells

In an attempt to characterize genes participating in the allergic late phase reaction, we have isolated a novel intercrine/chemokine (called MARC) from a cDNA library of the stimulated mouse mast cell line, CPII. As measured by Northern blotting, it is strongly upregulated at the mRNA level after the physiological challenge of the cells with immunoglobulin (Ig)E plus antigen. Unstimulated cells completely lack significant, stable expression, as do a number of other, different cell lines (uninduced and induced) and mouse tissues. In contrast to the Northern blot analysis, a polymerase chain reaction (PCR) analysis, performed on CPII cells and on Percoll gradient purified mouse peritoneal mast cells, revealed a basal level of transcription in the uninduced stage. After 2 h of IgE plus antigen challenge, a quantitative reverse transcriptase-PCR, using a spiked in MIMIC, showed a level of transcripts more than 100-fold higher in the CPII cells and 5-20-fold higher in purified mouse peritoneal cavity mast cells. This rapid induction after the Fc epsilon RI challenge, the identification of the gene as a member of the chemokine family, and its upregulated expression in peritoneal mast cells, all suggest an involvement in certain acute and chronic pathological mast cell-driven diseases.

A novel 7-nucleotide motif located in 3' untranslated sequences of the immediate-early gene set mediates platelet-derived growth factor induction of the JE gene

A cohort of the serum and growth factor regulated immediate-early gene set is induced with slower kinetics than c-fos. Two of the first immediate-early genes characterized as such, c-myc and JE, are contained within this subset. cis-acting genomic elements mediating induction of the slower responding subset of immediate-early genes have never been characterized. Herein we characterize two widely separated genomic elements which are together essential for induction of the murine JE gene by platelet-derived growth factor, serum, interleukin-1, and double-stranded RNA. One of these elements is novel in several regards. It is a 7-mer, TTTTGTA, found in the proximal 3' sequences downstream of the JE stop codon. The 3' element is position dependent and orientation independent. It does not function in polyadenylation, splicing, or destabilization of the JE transcript. Copies of the 7-mer or its inverse are found at comparable 3' sites in 25 immediate-early genes that encode transcription factors or cytokines. Given its general occurrence, the 7-mer may be a required cis-acting control element mediating induction of the immediate-early gene set.

Enhanced production of monocyte chemoattractant protein-1 in rheumatoid arthritis

Cells within the synovial tissue may recruit mononuclear phagocytes into the synovial fluid and tissues of arthritic patients. We investigated the production of the chemotactic cytokine monocyte chemoattractant protein-1 (MCP-1) using sera, synovial fluid, synovial tissue, as well as macrophages and fibroblasts isolated from synovial tissues from 80 arthritic patients. MCP-1 levels were significantly higher (P less than 0.05) in synovial fluid from RA patients (mean 25.5 +/- 8.1 ng/ml [SE]) compared to synovial fluid from osteoarthritis (OA) patients (0.92 +/- 0.08), or from patients with other arthritides (2.9 +/- 1.5). MCP-1 levels in RA sera (8.44 +/- 2.33) were significantly greater than MCP-1 in normal sera (0.16 +/- 0.06). The quantities of RA synovial fluid IL-8, which is chemotactic for neutrophils and lymphocytes, and MCP-1 were strongly positively correlated (P less than 0.05). To examine the cellular source of MCP-1, RA synovial tissue macrophages and fibroblasts were isolated. Synovial tissue fibroblasts did not express MCP-1 mRNA, but could be induced to produce MCP-1 by stimulation with either IL-1 beta, tumor necrosis factor-alpha (TNF-alpha), or LPS. In contrast, unlike normal peripheral blood monocytes or alveolar macrophages, RA synovial tissue macrophages constitutively expressed MCP-1 mRNA and antigen. Immunohistochemical analysis of synovial tissue showed that a significantly greater percentage of RA macrophages (50 +/- 8%) as compared to either OA macrophages (5 +/- 2) or normal macrophages (1 +/- 0.3) reacted with anti-MCP-1 antibodies. In addition, the synovial lining layer reacted with MCP-1 in both RA and OA synovial tissues. In contrast, only a minority of synovial fibroblasts (18 +/- 8%) from RA synovium were positive for immunolocalization of MCP-1. These results suggest that synovial production of MCP-1 may play an important role in the recruitment of mononuclear phagocytes during inflammation associated with RA and that synovial tissue macrophages are the dominant source of this cytokine.

Expression of monocyte chemoattractant protein 1 mRNA in human idiopathic pulmonary fibrosis

Macrophages are thought to play an important role in the pathologic changes associated with idiopathic pulmonary fibrosis (IPF). The mechanisms for increased monocyte/macrophage recruitment in IPF are unknown. Monocyte chemoattractant protein 1 (MCP-1) is the predominant monocyte chemoattractant secreted by a variety of different cell types in culture. We examined the expression of MCP-1 mRNA and its protein product in vivo in IPF and non-IPF lung specimens by in situ hybridization and immunocytochemistry. The cell types expressing MCP-1 in vivo were identified by immunostaining with specific antibodies. We demonstrated the expression of MCP-1 mRNA in pulmonary epithelial cells, in monocytes/macrophages, and in vascular endothelial and smooth muscle cells. Lung epithelial cells in patients with IPF strongly expressed MCP-1 mRNA and its protein product. In contrast, epithelial cells in non-IPF specimens did not express MCP-1 mRNA. Macrophages and vascular endothelial and smooth muscle cells were shown to express MCP-1 in both IPF and non-IPF lung specimens. These findings provide a basis for the understanding of the in vivo physiologic processes that mediate monocyte/macrophage recruitment and infiltration in the lung interstitium and the pathologic state contributing to an increased alveolar monocyte/macrophage population and inflammation in IPF.

Receptors for IgG complexes activate synthesis of monocyte chemoattractant peptide 1 and colony-stimulating factor 1

The chemotactic factors responsible for complement-independent macrophage accumulation in immune-complex diseases such as glomerulonephritis remain unknown. Fc receptors for IgG complexes are found on mesangial cells of the kidney, which produce the macrophage growth factor colony-stimulating factor 1 (CSF-1). We therefore investigated the possible stimulation of mesangial-cell expression of CSF-1 and the recently identified monocyte-specific chemoattractant protein 1 (MCP-1) by IgG complexes. IgG complexes, but not monomeric IgG or F(ab')2 fragments of IgG, rapidly (2-8 h) increased mRNA for both CSF-1 (10-fold) and MCP-1 (20-fold) in cultured mouse mesangial cells. The increase of mRNA for CSF-1 and MCP-1 was not reduced by either cytochalasin B or D, indicating that Fc receptor occupancy is sufficient for signaling and that phagocytosis is not required to elicit this response. IgG complexes also caused a 10-fold increase in the secretion of CSF-1 and a 3- to 5-fold increase in secretion of MCP-1 into the cell culture medium. The synthesis and release of CSF-1 and MCP-1 by mesangial cells as a consequence of Fc receptor occupancy may be responsible for macrophage recruitment and activation at sites of immune-complex deposition.

Cloning of a growth arrest-specific and transforming growth factor beta-regulated gene, TI 1, from an epithelial cell line

By cDNA cloning and differential screening, five genes that are regulated by transforming growth factor beta (TGF beta) in mink lung epithelial cells were identified. A novel membrane protein gene, TI 1, was identified which was downregulated by TGF beta and serum in quiescent cells. In actively growing cells, the TI 1 gene is rapidly and transiently induced by TGF beta, and it is overexpressed in the presence of protein synthesis inhibitors. It appears to be related to a family of transmembrane glycoproteins that are expressed on lymphocytes and tumor cells. The four other genes were all induced by TGF beta and correspond to the genes of collagen alpha type I, fibronectin, plasminogen activator inhibitor 1, and the monocyte chemotactic cell-activating factor (JE gene) previously shown to be TGF beta regulated.

Cloning of a growth arrest-specific and transforming growth factor beta-regulated gene, TI 1, from an epithelial cell line

By cDNA cloning and differential screening, five genes that are regulated by transforming growth factor beta (TGF beta) in mink lung epithelial cells were identified. A novel membrane protein gene, TI 1, was identified which was downregulated by TGF beta and serum in quiescent cells. In actively growing cells, the TI 1 gene is rapidly and transiently induced by TGF beta, and it is overexpressed in the presence of protein synthesis inhibitors. It appears to be related to a family of transmembrane glycoproteins that are expressed on lymphocytes and tumor cells. The four other genes were all induced by TGF beta and correspond to the genes of collagen alpha type I, fibronectin, plasminogen activator inhibitor 1, and the monocyte chemotactic cell-activating factor (JE gene) previously shown to be TGF beta regulated.

Suppression of tumor formation in vivo by expression of the JE gene in malignant cells

The early growth response gene JE encodes a monocyte chemoattractant, MCP-1. The JE/MCP-1 protein attracts and stimulates human monocytes and induces monocyte-mediated inhibition of tumor cell growth in vitro. Expression of human or murine JE/MCP-1 in Chinese hamster ovary (CHO) cells completely suppressed their ability to form tumors in nude mice. Coinjection of JE/MCP-1-expressing cells with nonexpressing CHO cells or with HeLa cells also prevented tumor formation. Since JE/MCP-1 expression had no discernible effect on the tranformed phenotype of these cells in vitro, the suppressive effect depends on host animal factors. These factors are likely to be components of the inflammatory response, because JE/MCP-1-expressing cells elicited a predominantly monocytic infiltrate at the site of injection. Our results suggest that JE/MCP-1 protein may be useful in cancer therapy.

Minimally modified low density lipoprotein is biologically active in vivo in mice

Minimally modified low density lipoprotein (MM-LDL), derived by mild iron oxidation or prolonged storage at 4 degrees C, has been shown to induce certain inflammatory responses in vascular cells in tissue culture. These include induction of monocyte (but not neutrophil) adherence to endothelial cells (EC), induction of EC production of colony stimulating factors (CSF), and induction of EC and smooth muscle cell production of monocyte chemotactic protein (MCP-1). To test for biologic activity in vivo, microgram quantities of MM-LDL were injected into mice, sera were assayed for CSF activity, and tissues were subjected to Northern analysis. After injection of MM-LDL, CSF activity increased approximately 7-26-fold but remained near control levels after injection of native LDL. Essentially all of the induced CSF activity was due to macrophage CSF as judged by antibody inhibition. Injection of MM-LDL into a mouse strain (C3H/HeJ) that is resistant to bacterial LPS gave similar results, indicating that the induction of CSF was not due to contaminating LPS and suggesting that there are differences in the pathways by which LPS and MM-LDL trigger cytokine production. In addition, after injection of MM-LDL, mRNA for JE, the mouse homologue of MCP-1, was markedly induced in various tissues, but was not induced after injection of native LDL. We conclude, therefore, that MM-LDL is biologically active in vivo and may contribute to the early stages of atherosclerosis by acting as an inflammatory agent.

Suppression of tumor formation in vivo by expression of the JE gene in malignant cells

The early growth response gene JE encodes a monocyte chemoattractant, MCP-1. The JE/MCP-1 protein attracts and stimulates human monocytes and induces monocyte-mediated inhibition of tumor cell growth in vitro. Expression of human or murine JE/MCP-1 in Chinese hamster ovary (CHO) cells completely suppressed their ability to form tumors in nude mice. Coinjection of JE/MCP-1-expressing cells with nonexpressing CHO cells or with HeLa cells also prevented tumor formation. Since JE/MCP-1 expression had no discernible effect on the tranformed phenotype of these cells in vitro, the suppressive effect depends on host animal factors. These factors are likely to be components of the inflammatory response, because JE/MCP-1-expressing cells elicited a predominantly monocytic infiltrate at the site of injection. Our results suggest that JE/MCP-1 protein may be useful in cancer therapy.

Novel expression pattern of a new member of the MIP-1 family of cytokine-like genes

Granulocyte/macrophage colony-stimulating factor (GM-CSF) specifically induces the growth of myeloid progenitors and their maturation into neutrophils and macrophages. We have identified a series of previously uncharacterized hematopoietic-specific mRNAs that are expressed in myelopoietic mouse bone marrow cultures stimulated by GM-CSF. One of these messages, C10, encodes a new member of the family of cytokine-like genes related to macrophage inflammatory protein-1 (MIP-1). Members of this family are all induced by one or more stimuli related to inflammation, wound repair, or immune response. In contrast, C10 mRNA showed little or no accumulation in response to such activating agents and was greatly reduced on activation of a T-cell line. On the other hand, C10 mRNA, unlike MIP-1, was acutely stimulated during the first day of bone marrow culture in GM-CSF, and it was also strongly elevated during the induction of neutrophilic differentiation of 32D cl3 cells by granulocyte colony-stimulating factor. The implications of this unusual expression pattern are discussed.

Expression of cyr61, a growth factor-inducible immediate-early gene

A set of immediate-early genes that are rapidly activated by serum or purified platelet-derived growth factor in mouse 3T3 fibroblasts has been previously identified. Among these genes, several are related to known or putative transcription factors and growth factors, supporting the notion that some of these genes encode regulatory molecules important to cell growth. We show here that a member of this set of genes, cyr61 (originally identified by its cDNA 3CH61), encodes a 379-amino-acid polypeptide rich in cysteine residues. cyr61 can be induced through protein kinase C-dependent and -independent pathways. Unlike many immediate-early genes that are transiently expressed, the cyr61 mRNA is accumulated from the G0/G1 transition through mid-G1. This expression pattern is due to persistent transcription, while the mRNA is rapidly turned over during the G0/G1 transition and in mid-G1 at the same rate. In logarithmically growing cells, the cyr61 mRNA level is constant throughout the cell cycle. Cyr61 contains an N-terminal secretory signal sequence; however, it is not detected in the culture medium by immunoprecipitation. Cyr61 is synthesized maximally at 1 to 2 h after serum stimulation and has a short half-life within the cell.

Expression of cyr61, a growth factor-inducible immediate-early gene

A set of immediate-early genes that are rapidly activated by serum or purified platelet-derived growth factor in mouse 3T3 fibroblasts has been previously identified. Among these genes, several are related to known or putative transcription factors and growth factors, supporting the notion that some of these genes encode regulatory molecules important to cell growth. We show here that a member of this set of genes, cyr61 (originally identified by its cDNA 3CH61), encodes a 379-amino-acid polypeptide rich in cysteine residues. cyr61 can be induced through protein kinase C-dependent and -independent pathways. Unlike many immediate-early genes that are transiently expressed, the cyr61 mRNA is accumulated from the G0/G1 transition through mid-G1. This expression pattern is due to persistent transcription, while the mRNA is rapidly turned over during the G0/G1 transition and in mid-G1 at the same rate. In logarithmically growing cells, the cyr61 mRNA level is constant throughout the cell cycle. Cyr61 contains an N-terminal secretory signal sequence; however, it is not detected in the culture medium by immunoprecipitation. Cyr61 is synthesized maximally at 1 to 2 h after serum stimulation and has a short half-life within the cell.

Two inflammatory mediator cytokine genes are closely linked and variably amplified on chromosome 17q

Mitogenic stimulation of resting T cells results in the de novo transcription of a large number of genes including those encoding regulatory molecules such as lymphokines. The genomic organization of two newly described induced lymphokine genes, 464.1 and 744.1, has been determined. 464.1 and 744.1 appear to be the human homologues of the recently cloned murine macrophage inflammatory proteins, MIP-1 alpha and MIP-1 beta, respectively. The 464.1 and 744.1 genes share 55% amino acid homology and demonstrate parallel regulation of induced expression in T cells. It was therefore of interest to observe that these genes are closely linked in the human genome, separated by 14 kb, and are organized in a head to head fashion. Each of the genes is present in an additional nonallelic copy (referred to as 464.2 and 744.2) as part of an apparent amplification unit in the genome of many individuals. The 464.2 gene is expressed and potentially encodes a protein highly related to 464.1, varying in 5 of 92 amino acids. As expected, 464.2 and 744.2 are also closely linked to each other as determined by population linkage disequilibrium studies. Individuals bearing a chromosome with a third amplification event, involving a 464-related gene but not a 744-related gene, are also infrequently observed. These genes are all located on chromosome 17 in bands q11-q21, the region implicated in von Recklinghausen neurofibromatosis (NF1) and in acute promyelocytic leukemia (AML-M3).