CD40L induces matrix-metalloproteinase-9 but not tissue inhibitor of metalloproteinases-1 in cervical carcinoma cells: imbalance between NF-kappaB and STAT3 activation

Local and Systemic STAT3 and p65 NF-KappaB Expression as Progression Markers and Functional Targets for Patients With Cervical Cancer

Cervical cancer, which main etiologic factor is Human Papillomavirus (HPV) infection, continues to be a burden for public health systems in developing countries. Our laboratory has been working with the hypothesis that signals generated in the tumor microenvironment can modulate local and systemic immune responses. In this context, it would be reasonable to think that tumors create pro-tumoral bias in immune cells, even before they are recruited to the tumor microenvironment. To understand if and how signaling started in the tumor microenvironment can influence cells within the tumor and systemically, we investigated the expression of key proteins in signaling pathways important for cell proliferation, viability, immune responses and tolerance. Besides, we used detection of specific phosphorylated residues, which are indicative of activation for Akt, CREB, p65 NFκB, and STAT3. Our findings included the observation of a significant STAT3 expression increase and p65 NFκB decrease in circulating leukocytes in correlation with lesion grade. In light of those observations, we started investigating the result of the inhibition of STAT3 in a tumor experimental model. STAT3 inhibition impaired tumor growth, increased anti-tumor T cell responses and decreased the accumulation of myeloid cells in the spleen. The concomitant inhibition of NFκB partially reversed these effects. This study indicates that STAT3 and NFκB are involved in immunomodulatory tumor effects and STAT3 inhibition could be considered as therapy for patients with cervical cancer.

Cd40 Activation as Potential Tool in Malignant Neoplasms

Background

CD40, a cell surface molecule, is expressed on B-cell malignancies and many different solid tumors. It is capable of mediating diverse biological phenomena such as the induction of apoptosis in tumors and stimulation of the immune response. It has thus been studied as a possible target for antitumor therapy. The general aim of this review is to focus the attention of clinical oncologists on the involvement of CD40 in tumors and the rationale of CD40-activation-based therapies in new, biologically oriented antitumor protocols.

Methods

A Medline review of published papers about the role of CD40 activation in cancer therapy.

Results

Many authors have shown that CD40 activation promotes apoptotic death of tumor cells and that the presence of the molecule on the surface of carcinoma lines is an important factor in the generation of tumor-specific T-cell responses that contribute to tumor cell elimination. The CD40 ligand (CD40L) is the natural ligand for CD40; it is expressed primarily on the surface of activated T lymphocytes. Preclinical studies suggest that CD40-CD40L interaction could be useful for cytotoxicity against CD40-expressing tumors and for immune stimulation. Tumor inhibition was observed when tumor cells were treated with agonistic anti-CD40 monoclonal antibodies or with the soluble form of CD40L. The results of the first phase I clinical trial to treat cancer patients with subcutaneous injection of recombinant human CD40L have been recently reported. Immunohistochemical studies have revealed that detection of CD40 in primary cutaneous malignant melanoma and lung cancer may have a negative prognostic value. Interestingly, up-regulation of CD40 was observed in the tumor vessels of renal carcinomas and Kaposi's sarcoma, suggesting possible involvement of CD40 in tumor angiogenesis. Recently, it has also been shown that CD40 engagement on endothelial cells induces in vitro tubule formation and expression of matrix metalloproteinases, two processes involved in the neovascularization and progression of tumors.

Conclusions

CD40 activation represents an exciting target for hematological malignancies and solid tumors expressing the molecule, but its functional role in cancer development still remains unclear and controversial.

Cervical cancer cell-derived interleukin-6 impairs CCR7-dependent migration of MMP-9-expressing dendritic cells

Cervical carcinogenesis is a consequence of persistent infection with high-risk human papillomaviruses (HPVs). Recent studies indicate that HPV-transformed cells actively instruct their microenvironment to promote carcinogenesis. Here, we demonstrate that cervical cancer cells activate monocytes to produce their own CCL2 for further monocyte recruitment and reprogram their function during differentiation and maturation to dendritic cells (DCs). Our data show that cervical cancer cells suppress the induction of the chemokine receptor CCR7 in phenotypically mature DCs and impair their migration toward a lymph node homing chemokine, required to initiate adaptive immune responses. We confirmed the presence of CD83(+)CCR7(low) DCs in cancer biopsies. The second factor essential for DC migration, matrix-metalloproteinase MMP-9, which also has vasculogenic and protumorigenic properties, is not suppressed but upregulated in immature as well as mature DCs. We identified interleukin-6 (IL-6) as a crucial cervical cancer cell-derived mediator and nuclear factor kappaB (NF-jB) as the central signaling pathway targeted in DCs. Anti-IL-6 antibodies reverted not only NF-jB inhibition and restored CCR7-dependent migration but also blocked MMP-9 induction. This is the first report demonstrating the dissociation of CCR7 and MMP-9 expression in phenotypically mature CD83(+) DCs by cancer cells. Our results show that cervical cancer cells actively shape the local microenvironment. They induce the accumulation of myeloid cells and skew their function from immune activation to local production of protumorigenic MMP-9. Neutralizing anti-IL-6 antibodies can counteract this functional dysbalance and should therefore be considered for adjuvant cervical cancer therapy.

Gelatinase B/MMP-9 in Tumour Pathogenesis and Progression

Since its original identification as a leukocyte gelatinase/type V collagenase and tumour type IV collagenase, gelatinase B/matrix metalloproteinase (MMP)-9 is now recognised as playing a central role in many aspects of tumour progression. In this review, we relate current concepts concerning the many ways in which gelatinase B/MMP-9 influences tumour biology. Following a brief outline of the gelatinase B/MMP-9 gene and protein, we analyse the role(s) of gelatinase B/MMP-9 in different phases of the tumorigenic process, and compare the importance of gelatinase B/MMP-9 source in the carcinogenic process. What becomes apparent is the importance of inflammatory cell-derived gelatinase B/MMP-9 in tumour promotion, early progression and triggering of the "angiogenic switch", the integral relationship between inflammatory, stromal and tumour components with respect to gelatinase B/MMP-9 production and activation, and the fundamental role for gelatinase B/MMP-9 in the formation and maintenance of tumour stem cell and metastatic niches. It is also apparent that gelatinase B/MMP-9 plays important tumour suppressing functions, producing endogenous angiogenesis inhibitors, promoting inflammatory anti-tumour activity, and inducing apoptosis. The fundamental roles of gelatinase B/MMP-9 in cancer biology underpins the need for specific therapeutic inhibitors of gelatinase B/MMP-9 function, the use of which must take into account and substitute for tumour-suppressing gelatinase B/MMP-9 activity and also limit inhibition of physiological gelatinase B/MMP-9 function.

Platelet shedding of CD40L is regulated by matrix metalloproteinase-9 in abdominal sepsis

BACKGROUND AND OBJECTIVES

Platelet-derived CD40L is known to regulate neutrophil recruitment and lung damage in sepsis. However, the mechanism regulating shedding of CD40L from activated platelets is not known. We hypothesized that matrix metalloproteinase (MMP)-9 might cleave surface-expressed CD40L and regulate pulmonary accumulation of neutrophils in sepsis.

METHODS

Abdominal sepsis was induced by cecal ligation and puncture (CLP) in wild-type and MMP-9-deficient mice. Edema formation, CXC chemokine levels, myeloperoxidase levels, neutrophils in the lung and plasma levels of CD40L and MMP-9 were quantified.

RESULTS

CLP increased plasma levels of MMP-9 but not MMP-2. The CLP-induced decrease in platelet surface CD40L and increase in soluble CD40L levels were significantly attenuated in MMP-9 gene-deficient mice. Moreover, pulmonary myeloperoxidase (MPO) activity and neutrophil infiltration in the alveolar space, as well as edema formation and lung injury, were markedly decreased in septic mice lacking MMP-9. In vitro studies revealed that inhibition of MMP-9 decreased platelet shedding of CD40L. Moreover, recombinant MMP-9 was capable of cleaving surface-expressed CD40L on activated platelets. In human studies, plasma levels of MMP-9 were significantly increased in patients with septic shock as compared with healthy controls, although MMP-9 levels did not correlate with organ injury score.

CONCLUSIONS

Our novel data propose a role of MMP-9 in regulating platelet-dependent infiltration of neutrophils and tissue damage in septic lung injury by controlling CD40L shedding from platelets. We conclude that targeting MMP-9 may be a useful strategy to limit acute lung injury in abdominal sepsis.

Platelet soluble CD40L and matrix metalloproteinase 9 activity are proinflammatory mediators in Behçet disease patients

Platelets are the major source of plasma-soluble CD40L (sCD40L), an important inflammatory mediator. This study explored the impact of platelet-derived sCD40L on Behçet disease (BD), an autoinflammatory vasculitis. We also searched for influences by platelet matrix metalloproteinases (MMP) -2 and MMP-9, implicated in several inflammatory diseases, on CD40L shedding from platelet membrane. Platelet activation were studied by flow cytometry and aggregometry, surface expression of CD40L and platelet-leukocyte aggregates by flow cytometry, sCD40L by ELISA, cellular CD40L and CD40 levels by Western blot and MMPs activity by gelatin zymography. The effect of sCD40L on MMP9 expression was studied in cultured MEG-01 cells. Plasma and platelet-released sCD40L levels were higher in BD patients. No differences in platelet activation and in platelet-leukocyte aggregates formation were observed between BD patients and controls. Plasma and platelet MMP-9 levels were increased in BD patients, whereas there was no difference in platelet MMP-2 activity. Since a correlation between plasma sCD40L and platelet MMP-9 activity was observed, we studied the influence of sCD40L on MMP-9 levels in the megakaryoblastic cell line MEG-01. Treatment of MEG-01 cells with recombinant sCD40L increased MMP-9 but did not change MMP-2 levels. In conclusion, sCD40L release from platelets was mediated by MMP-9, and MMP-9 expression was in turn upregulated by sCD40L in the MEG-01 cell line. We conclude that platelets and megakaryocytes might participate in a positive feedback loop occurring between sCD40L and MMP-9 which would contribute to the proinflammatory state observed in BD.

Molecular pathobiology of human cervical high-grade lesions: paracrine STAT3 activation in tumor-instructed myeloid cells drives local MMP-9 expression

In many tumors, the switch from precancerous lesions to malignancy critically relies on expression of the matrix-metalloprotease MMP-9, which is predominantly provided by infiltrating inflammatory cells. Our study defines a novel molecular cascade, how human neoplastic cells instruct tumor-associated myeloid cells to produce MMP-9. In biopsies of human papillomavirus-associated precancerous cervical intraepithelial neoplasia (CIN III lesions), we show broad activation of the transcription factor STAT3 and coexpression of MMP-9 in perivascular inflammatory cells. For the first time, we establish a causative link between tumor-mediated paracrine STAT3 activation and MMP-9 production by human tumor-instructed monocytes, whereas NF-κB activation is dispensable for this response. Our data provide evidence that STAT3 does not directly induce MMP-9 but first leads to a strong production of the monocyte chemoattractant protein-1 (CCL2) in the nanogram range. In a second phase, autocrine stimulation of the CCR2 receptor in the tumor-instructed monocytes amplifies MMP-9 expression via intracellular Ca(2+) signaling. These findings elucidate a critical mechanism in the molecular pathobiology of cervical carcinogenesis at the switch to malignancy. Particularly in tumors, which are associated with infectious agents, STAT3-driven inflammation may be pivotal to promote carcinogenesis, while at the same time limit NF-κB-dependent immune responses and thus rejection of the infected preneoplastic cells. The molecular cascade defined in this study provides the basis for a rational design of future adjuvant therapies of cervical precancerous lesions.

CD40/CD40L signaling and its implication in health and disease

CD40, a transmembrane receptor of the tumor necrosis factor gene superfamily is expressed on a variety of cells, such as monocytes, B-cells, antigen presenting cells, endothelial, smooth muscle cells, and fibroblasts. The interaction between CD40 and CD40 ligand (CD40L) enhances the expression of cytokines, chemokines, matrix metalloproteinases, growth factors, and adhesion molecules, mainly through the stimulation of nuclear factor kappa B. The aim of this review is to summarize the molecular and cellular characteristics of CD40 and CD40L, the mechanisms that regulate their expression, the cellular responses they stimulate and finally their implication in the pathophysiology of inflammatory and autoimmune diseases.

Molecular characterization of Helicobacter pylori VacA induction of IL-8 in U937 cells reveals a prominent role for p38MAPK in activating transcription factor-2, cAMP response element binding protein, and NF-kappaB activation

Helicobacter pylori VacA induces multiple effects on susceptible cells, including vacuolation, mitochondrial damage, inhibition of cell growth, and enhanced cyclooxygenase-2 expression. To assess the ability of H. pylori to modulate the production of inflammatory mediators, we examined the mechanisms by which VacA enhanced IL-8 production by promonocytic U937 cells, which demonstrated the greatest VacA-induced IL-8 release of the cells tested. Inhibitors of p38 MAPK (SB203580), ERK1/2 (PD98059), IkappaBalpha ((E)-3-(4-methylphenylsulfonyl)-2-propenenitrile), Ca(2+) entry (SKF96365), and intracellular Ca(2+) channels (dantrolene) blocked VacA-induced IL-8 production. Furthermore, an intracellular Ca(2+) chelator (BAPTA-AM), which inhibited VacA-activated p38 MAPK, caused a dose-dependent reduction in VacA-induced IL-8 secretion by U937 cells, implying a role for intracellular Ca(2+) in mediating activation of MAPK and the canonical NF-kappaB pathway. VacA stimulated translocation of NF-kappaBp65 to the nucleus, consistent with enhancement of IL-8 expression by activation of the NF-kappaB pathway. In addition, small interfering RNA of activating transcription factor (ATF)-2 or CREB, which is a p38MAPK substrate and binds to the AP-1 site of the IL-8 promoter, inhibited VacA-induced IL-8 production. VacA activated an IL-8 promoter containing an NF-IL-6 site, but not a mutated AP-1 or NF-kappaB site, suggesting direct involvement of the ATF-2/CREB binding region or NF-kappaB-binding regions in VacA-induced IL-8 promoter activation. Thus, in U937 cells, VacA directly increases IL-8 production by activation of the p38 MAPK via intracellular Ca(2+) release, leading to activation of the transcription factors, ATF-2, CREB, and NF-kappaB.

DNA tumour viruses promote tumour cell invasion and metastasis by deregulating the normal processes of cell adhesion and motility

Approximately 15-20% of global cancer incidence is causally linked to viral infection, yet the low incidence of cancers in healthy infected individuals suggests that malignant conversion of virus-infected cells occurs after a long period as a result of additional genetic modifications. There are four families of viruses that are now documented to be involved in the development of human cancers which include members of the polyomavirus, hepadnavirus, papillomavirus and herpesvirus families. Although a number of these viruses are implicated in the aetiology of lymphomas or leukaemias, the vast majority are associated with malignancies of epithelial cells. In epithelial tissues, several classes of proteins are involved in maintaining tissue architecture, including those that promote cell-cell adhesion, and others, which mediate cell-matrix interactions. Proteins representative of all classes are frequently altered in malignant tumour cells that possess invasive and metastatic properties. Malignant tumour cells acquire mechanisms to degrade basement membranes and invade the underlying tissue. Many viruses encode proteins which engage signalling pathways that affect one or more of these mechanisms. It is believed that activation of these processes by chronic viral infection can, under certain circumstances, promote tumour cell invasion and metastasis. This review will take a brief look at the current knowledge of viral-induced alterations in cell motility and invasiveness in the context of tumour invasion and metastasis.

Signal transducer and activator of transcription 3 activation promotes invasive growth of colon carcinomas through matrix metalloproteinase induction

Signal transducer and activator of transcription 3 (STAT3) is aberrantly activated in colorectal carcinomas (CRCs). Here, we define the relationship between STAT3 function and the malignant properties of colon carcinoma cells. Elevated activation of STAT3 enhances invasive growth of the CRC cell lines. To address mechanisms through which STAT3 influences invasiveness, the protease mRNA expression pattern of CRC biopsies was analyzed and correlated with the STAT3 activity status. These studies revealed a striking coincidence of STAT3 activation and strong expression of matrix metalloproteinases MMP-1, -3, -7, and -9. Immunohistological examination of CRC tumor specimens showed a clear colocalization of MMP-1 and activated STAT3. Experimentally induced STAT3 activity in CRC cell lines enhanced both the level of MMP-1 mRNA and secreted MMP-1 enzymatic activity. A direct connection of STAT3 activity and transcription from the MMP-1 promoter was shown by reporter gene experiments. Moreover, high-affinity binding of STAT3 to STAT recognition elements in both the MMP-1 and MMP-3 promoter was demonstrated. Xenograft tumors arising from implantation of CRC cells into nude mice showed simultaneous appearance and colocalization of p-Y-STAT3 and MMP-1 expression. Our results link aberrant activity of STAT3 in CRC to malignant tumor progression through upregulated expression of MMPs.

Higher expression and activity of metalloproteinases in human cervical carcinoma cell lines is associated with HPV presence

Matrix metalloproteinases (MMPs) MMP-2, MMP-9, and MT1-MMP are required for basement membrane degradation in cervical carcinoma. We evaluated the expression and activity of MMPs and their inhibitors RECK and TIMP-2 in 3 human invasive cervical carcinoma cell lines. Two HPV16-positive cell lines (SiHa and CaSki) and an HPV-negative cell line (C33A) were cultured either onto a type-I collagen gel, Matrigel, or plastic, to recreate their three-dimensional growth environment and evaluate the expression of these genes using quantitative real-time PCR. We also analyzed the gelatinolytic activity of MMP-2 and MMP-9 by zymography. We found that HPV (human papillomavirus)-positive cell lines express higher levels of MMP-2, MT1-MMP, and TIMP-2 than the HPV negative cell line. In addition, MMP-9 was expressed at very low levels in both HPV-negative and HPV-positive cell lines. We also observed that the expression of the RECK gene is higher in CaSki cells, being associated with higher pro-MMP-2 activity. Furthermore, Matrigel substrate influences MMP-2 expression in both SiHa and CaSki cells. On the other hand, we found that type-I collagen gel, but not Matrigel, can enhance pro-MMP-2 activity in all cell lines. Our results suggest that the presence of HPV is related to increased expression of MMP-2, MT1-MMP, and TIMP-2, and that pro-MMP-2 activity is higher in HPV-positive than in HPV-negative cells.

High serum levels of soluble CD40-L in patients with undifferentiated nasopharyngeal carcinoma: pathogenic and clinical relevance

BACKGROUND

Engagement of CD40 promotes survival of undifferentiated nasopharyngeal carcinoma (UNPC) cells and similar effects are induced by the EBV oncoprotein LMP-1 that is expressed in a fraction of cases. Considering that CD40 may be activated also by the soluble isoform of CD40L (sCD40L), we investigated the serum levels of sCD40L in a series of 61 UNPC patients from Italy, a non-endemic area for this disease.

RESULTS

At diagnosis, serum samples of UNPC patients contained significantly higher levels of sCD40L than age-matched healthy controls (p < 0.001). High levels of sCD40L (i.e., >18 ng/ml) were more frequently found in patients <40 years of age (p = 0.03) and with distant metastases at presentation (p = 0.03). Serum levels of sCD40L were inversely associated with the expression of the EBV oncoprotein LMP-1 (p = 0.03), which mimics a constitutively activated CD40. The amount of sCD40L decreased in a fraction of patients treated with local radiotherapy alone. Moreover, CD40L+ lymphoid cells admixed to neoplastic UNPC cells were detected in cases with high serum levels of sCD40L, suggesting that sCD40L is probably produced within the tumor mass.

CONCLUSION

sCD40L may contribute to CD40 activation in UNPC cells, particularly of LMP-1-negative cases, further supporting the crucial role of CD40 signalling in the pathogenesis of UNPC. sCD40L levels may be useful to identify UNPC patients with occult distant metastases at presentation.

N-Acetyl-L-cysteine and pyrrolidine dithiocarbamate inhibited nuclear factor-kappaB activation in alveolar macrophages by different mechanisms

AIM

To study the effects of N-acetyl-L-cysteine (NAC) and pyrrolidine dithiocarbamate (PDTC) on the phosphorylation of IkappaB kinase (IKK) beta, IKK alpha, and IkB alpha in alveolar macrophages (AM), and to explore the pharmacological mechanisms of NAC and PDTC as inhibitors of NF-kappaB activation.

METHODS

AM were collected from bronchoalveolar lavage fluid from the patients with chronic obstructive pulmonary disease. The AM were incubated for 1.5 h with NAC and PDTC, and then stimulated for 90 min by either tumor necrosis factor (TNF)- alpha or interleukin (IL)-1. Western blotting was used to detect the protein phosphorylation levels of IKKbeta, IKK alpha, and IkappaB alpha. NF-kappaB activity was analyzed by using an electrophoretic mobility shift assay.

RESULTS

NAC inhibited the phosphorylation of IKKbeta, IKK alpha, and IkappaB alpha induced by TNF-a, but had no effect on the phosphorylation of IKKbeta, IKK alpha and IkappaB alpha induced by IL-1. PDTC did not inhibit the phosphorylation of IkappaB alpha induced by TNF- alpha or IL-1. Similarly, NAC inhibited the activation of NF-kB induced by TNF- alpha, but had no effect on the activation of NF-kappaB induced by IL-1. PDTC significantly inhibited the activation of NF-kappa B induced by TNF- alpha and IL-1. The electrophoretic mobility shift assay also showed that PDTC and NAC do not directly inhibit NF-kappa B DNA binding activity in vitro.

CONCLUSION

PDTC prevents the degradation of IkappaB alpha via the ubiquitylation-proteasome proteolytic pathway. NAC can inhibit the processes upstream of IKK activation induced by TNF- alpha, which results in the decline of NF-kappaB activity.

Transfection and ligation of CD40 in human oral keratinocytes affect proliferation, adhesion and migration but not apoptosis in vitro

AIMS

CD40 expression is restricted to Keratinocytes of normal epidermis or stratified squamous epithelium of oral mucosa. Ligation of CD40 inhibits keratinocyte proliferation and apoptosis. The aim of this study was to investigate the functional significance of CD40 in the proliferation, apoptosis, adhesion and migration of human oral keratinocytes in vitro.

METHODS

The CD40-negative oral keratinocyte line OSC19, its CD40-positive transfected derivative (OSC19T-CD40) and null transfectants (OSC19T-control), with and without stimulation by soluble protein CD40 ligand (sCD40L) or anti-CD40 antibodies were used.

RESULTS

OSC19T-CD40 showed significantly (P < 0.001) slower growth than the null transfectants and parent cells. OSC19T-CD40 proliferation was inhibited by ligation with sCD40L and blocking by two anti-CD40 antibodies, but stimulated by a third. Binding of CD40 with ligand or antibody had no effect on keratinocyte apoptosis in any cell line. The capacity of OSC19T-CD40 cells to adhere to CD40L-coated wells was significantly greater (P < 0.001) than that of parent OSC19 and OSC19T-control cells, and the migration rate of OSC19T-CD40 cells was significantly higher than parent OSC19 (P = 0.038 on fibronectin, P = 0.004 on Matrigel) or OSC19T-control (P =0.017 on fibronectin, P = 0.013 on Matrigel) cells.

CONCLUSIONS

CD40 is an important molecule in keratinocyte homeostasis, and has more than one ligand. The ligand that is bound may be critical in oral epithelial homeostasis, the development of malignancy and the behaviour of the subsequent tumour.

Expression of membrane type 1 matrix metalloproteinase in papillomavirus-positive cells: role of the human papillomavirus (HPV) 16 and HPV8 E7 gene products

Matrix metalloproteinases (MMPs) degrade extracellular matrix. They are involved in cellular proliferation, migration, angiogenesis, invasion and metastasis. MT-1 MMP, a membrane-bound MMP, is expressed in carcinomas of the uterine cervix in vivo. This type of cancer is associated with human papillomavirus (HPV) infection. Here it was shown that keratinocytes transformed with HPV16 or HPV18 in vitro, and HPV-positive cervical carcinoma cell lines, constitutively expressed MT-1 MMP. Expression of the E7 protein from the mucosal and cutaneous high-risk types HPV16 and HPV8, but not from the cutaneous low-risk type HPV1, was sufficient to induce MT-1 MMP expression in primary human keratinocytes and HaCaT cells. As a consequence, MMP-2 was activated. MT-1 MMP expression might play a role in the HPV life cycle by promoting proliferation of host cells and might contribute to their invasive phenotype during malignant progression.

Leukemia inhibitory factor triggers activation of signal transducer and activator of transcription 3, proliferation, invasiveness, and altered protease expression in choriocarcinoma cells

Extravillous trophoblast cells resemble cancer cells with regard to their intrinsic invasiveness. They invade decidual tissue, but, unlike tumor cells, shut down their invasive properties, when they become inappropriate. Stimuli involved in the modulation of invasion, as well as their underlying signaling mechanisms require further clarification. We were especially interested in discovering signals capable of stimulating invasion in otherwise low-invasive cells involved in reproduction. Using the choriocarcinoma cell line Jeg-3 as a model, we have addressed the potential role of cytokine/growth factor-driven activation of signal transducer and activator of transcription 3 (STAT3) in this process. Jeg-3 cells were treated with various factors known to induce trophoblast proliferation, differentiation, migration, or invasiveness (insulin-like-growth-factor-II (IGF-II), hepatocyte growth factor (HGF), interleukin-6 (IL-6), and leukemia inhibitory factor (LIF)). Only LIF elicited strong tyrosine phosphorylation and specific DNA-binding activity of STAT3. It induced a significant acceleration of cell proliferation and promoted the capability of Jeg-3 cells to invade into an artificial extracellular matrix. Moreover, LIF influenced the expression pattern of proteases and protease inhibitors with potential relevance for invasiveness (downregulation of mRNA for tissue inhibitor of metalloproteinase 1 (TIMP-1) and upregulation of mRNA for caspase-4). In conjunction with earlier work, in which we found that STAT3 DNA-binding activity was increased in invasive cells (choriocarcinoma, first trimester trophoblasts) and absent in non-invasive cells (term trophoblasts), these findings suggest a connection between LIF-driven STAT3 activity and invasiveness of choriocarcinoma and trophoblast cells.

Activation of the c-Met receptor complex in fibroblasts drives invasive cell behavior by signaling through transcription factor STAT3

c-Met is the receptor for hepatocyte growth factor/scatter factor (HGF/SF). It mediates multiple cellular responses in development and adult life, and c-Met hyperactivity is associated with malignant transformation of cells and the acquisition of metastatic properties. Signal transducer and activator of transcription 3 (STAT3) has been shown to contribute to c-Met-mediated cell motility and is, thus, potentially involved in the control of invasive cell behavior. We have functionally reconstituted c-Met-dependent signal transduction in fibroblasts with the aim of studying Met-driven cell invasiveness and the role of STAT3 in this phenomenon. Activation of the system was achieved by means of a hybrid receptor comprising the extracellular domain of the nerve growth factor (NGF) receptor TrkA, the cytoplasmic part of c-Met and a C-terminally fused blue fluorescent protein (BFP). In addition, a GFP-tagged derivative of adaptor protein Gab1 was expressed. NGF-stimulation of mouse fibroblasts expressing tagged versions of both Trk-Met and Gab1 with NGF resulted in anchorage-independent growth and enhanced invasiveness. By freeze-fracture cytochemistry and electron microscopy, we were able to visualize the ligand-induced formation of multivalent receptor complex assemblies within the cell membrane. NGF-stimulation of the heterologous receptor system evoked activation of STAT3 as evidenced by tyrosine phosphorylation and the formation of STAT3 clusters at the cell membrane. siRNA-mediated ablation of STAT3 expression resulted in a drastic reduction of c-Met-driven invasiveness, indicating an important role of STAT3 in the control of this particularly relevant property of transformed cells.

Prognostic Value of CD40 in Adult Soft Tissue Sarcomas

PURPOSE

The purpose is to evaluate the expression of CD40, a membrane protein predominantly expressed on B cells, dendritic cells, and macrophages, in a series of adult soft tissue sarcomas and to test its possible prognostic value.

EXPERIMENTAL DESIGN

CD40 expression was studied by immunohistochemistry. Correlations with other baseline characteristics of patients and tumors were analyzed with chi(2) test. The prognostic value was studied with univariable and multivariable analysis adjusted by age, sex, tumor size, grade, location, and distant metastases.

RESULTS

Eighty-two patients, between January 1994 and May 2001, were analyzed. Membrane or cytoplasmic staining for CD40 protein was absent in 30% of the tumors but present in <10% of cells in 22 (27%), in 10% to 50% in 23 (28%), and in >50% of cells in 12 (15%) tumors. There was no correlation between CD40 expression and age, sex, size, grade, and location of the primary tumor and distant metastases. With 61 patients (74.4%) progressed and 31 (37.8%) dead, CD40 expression was a significant prognostic factor for disease-free and overall survival at univariable and multivariable analysis. Patients with tumors expressing CD40 in >50% of cells had a dramatically unfavorable prognosis with median disease-free and overall survival of 7 and 17 months, respectively, and hazard ratios of relapse and death as compared with patients with CD40-negative tumors of 2.89 (95% confidence interval: 1.26-6.60) and 6.92 (95% confidence interval: 2.18-22.0), respectively.

CONCLUSIONS

These data suggest that expression of CD40 protein in >50% of cells might indicate an unfavorable prognosis in adult soft tissue sarcomas.

Effect of ubiquitin-proteasome pathway on mouse blastocyst implantation and expression of matrix metalloproteinases-2 and -9

Previous studies have documented that ubiquitin-related proteins are present in human, baboon, rhesus monkey, cow, sheep, and mouse pregnant uteri, indicating that the ubiquitin-proteasome pathway (UPP) may be involved in the extensive uterine remodeling during mammalian early pregnancy, but there is still no direct evidence. A mouse intrauterine injection model was employed to study the direct effect of the UPP on mouse embryo implantation and its possible mechanisms. On Day 3 of pregnancy in each mouse, one of the uterine horns in each mouse was injected with different concentrations of lactacystin, a specific proteasome inhibitor, or anti-ubiquitin antibody, and the other side was used as a control. On days 5, 6, and 7, the number of implanted embryos was counted and the expression and gelatinolytic activities of matrix metalloproteinase-2 (MMP-2) and MMP-9 were studied. Results presented here illustrate that injection of lactacystin and anti-ubiquitin antibody significantly inhibited mouse embryo implantation. Further investigations by reverse transcription-polymerase chain reaction and gelatin zymography showed that MMP-2 and MMP-9 mRNA expression, as well as the gelatinolytic activity of MMP-9 in the lactacystin-treated uterine horn, significantly decreased, whereas the activity of MMP-2 was not significantly affected. The results obtained from this study, together with previous reports, suggest that the UPP is involved in mouse embryo implantation, and UPP's effect on embryo implantation is achieved at least in part by regulating MMP-2 and MMP-9 mRNA expression and the gelatinolytic activity of MMP-9.

Binding of gastrointestinal tumor cells to endothelial E- and P-selectin adhesion receptors leads to transient down-regulation of sLeX ligands in vitro

BACKGROUND AND AIMS

The prognostic relevance of sialyl Lewis X (sLeX) expression in colorectal and gastric cancer and its relevance to the hematogenous phase of tumor invasion is controversial. This study was designed to evaluate sLeX expression during tumor cell-endothelial cell interaction in vitro.

METHODS

Adhesion and transendothelial penetration of MKN45, PaCa-2, WiDr, or Dan-G cells was analyzed by combined phase contrast-reflection interference contrast microscopy. In parallel, kinetics of membranous sLeX expression were examined fluorimetrically. To identify factor(s) which may be responsible for sLeX expression during tumor invasion tumor cells were treated with soluble immunomodulators, isolated endothelial plasma membranes, or E-selectin or P-selectin IgG fusion proteins. sLeX was then analyzed by flow cytometry.

RESULTS

Fluorometric quantification of sLeX demonstrated an inverse correlation between basal sLeX expression level and adhesion capacity of the tumor cells. Unexpectedly, sLeX was strongly down-regulated on tumor cell membranes in the course of heterophilic cell-cell contacts. The process occurred transiently, with a maximum effect 30-60 min after introducing tumor cells to the endothelial monolayer. Binding of tumor cells to immobilized E- and P-selectin IgG globulin chimeras was shown to be responsible for this phenomenon.

CONCLUSION

A transient loss of sLeX is necessary for gastrointestinal tumor cells to invade endothelial cells. Due to the transient nature of the decrease in sLeX the controversy about the prognostic relevance of sLeX expression in colorectal and gastric cancer may be rooted in the stage of tumor invasion at the time of sLeX measurement.