IL-6 as an intracrine growth factor for renal carcinoma cell lines

Characterization of primary renal carcinoma cultures

PURPOSE

For a better understanding of the factors contributing to tumor progression in metastatic renal cell carcinoma and to identify possible targets for immunotherapeutic approaches, we characterized several primary cultures from renal cell carcinoma.

MATERIALS AND METHODS

Cell cultures were tested for activity of telomerase, secretion of immunosuppressive cytokines and others. The induction of cytotoxic activity against the autologous tumor was tested in a cytotoxicity assay after coculture of immunological effector cells with antigen-pulsed dendritic cells. The data were tested for influence on survival.

RESULTS

We were able to establish primary cell cultures from 58 patients with renal cell carcinoma and their metastasis. 48/58 were positive for telomerase activity and all secreted IL-6, TGF-beta, VEGF and IL-8. High TGF-beta secretion, the activity of telomerase and the induction of a telomerase-specific immune response against telomerase peptides in telomerase-positive tumors had a significant impact on survival.

CONCLUSION

TGF-beta secretion, activity of telomerase in telomerase-positive tumors and the ability to generate a telomerase-specific immune response might serve as a prognostic marker for RCC. New approaches might focus on attacking the TGF-beta pathway and on induction of telomerase-specific immune cells.

Significance of autologous interleukin-6 production in the HA22T/VGH cell model of hepatocellular carcinoma

Cancer cells may often support their own growth, survival, and drug resistance by autocrine/paracrine loops based on the production of different factors; results from us and others have shown that similar interleukin-6 (IL-6)-related loops are operative in multiple myeloma and prostate or renal cancer. Because this aspect has not been investigated in detail for hepatocellular carcinoma (HCC), we have examined it in HA22T/VGH cells. These differ from other primary liver cancer cell lines (that is, HepG2, HuH-6, and HuH-7) in that enzyme-linked immunosorbent assay (ELISA) showed the HA22T/VGH cells to secrete remarkable amounts of IL-6 (16.8 ng/10(6) cells/24 h); this production, due to constitutive activation of NF-kappaB, is inhibited by agents like curcumin and dehydroxymethylepoxyquinomicin (DHMEQ), which interfere with the transcription factor. Flow cytometry, ELISA, mRNA, and Western blotting analyses were performed to characterize the status of the IL-6 receptor in HA22T/VGH cells. Two transmembrane glycoproteins that form the functional IL-6 receptor have been identified: the ligand-binding gp80 and the signal-transducer gp130. Soluble forms of gp80 also trigger membrane gp130 signaling when complexed with IL-6, while soluble forms of gp130 inhibit the same process. Our results showed that HA22T/VGH cells express gp130 at their surface, but release only traces of its soluble form. For gp80, the cells produced the mRNAs of both its membrane and soluble form. However, in immunoblotting they exhibited a very faint content of the same subunit, which, in addition, was neither expressed at the cell surface nor secreted. In MTT assays, incubation with a neutralizing anti-IL-6 antibody for up to 7 days did not affect the growth of HA22T/VGH cells. Also, other specific anti-IL-6 approaches (siRNA or AODN) failed to produce this result. In conclusion, autostimulatory loops mediated by IL-6 are less likely to occur in HCC than in other kinds of cancer. However, since release of IL-6 is frequent in HCC, especially in its more advanced stages, the use of agents like curcumin or DHMEQ might be beneficial to counteract its adverse systemic effects (e.g., cachexia).

Intratumoral cytokines/chemokines/growth factors and tumor infiltrating dendritic cells: friends or enemies?

The tumor microenvironment consists of a variable combination of tumor cells, stromal fibroblasts, endothelial cells and infiltrating leukocytes, such as macrophages, T lymphocytes, and dendritic cells. A variety of cytokines, chemokines and growth factors are produced in the local tumor environment by different cells accounting for a complex cell interaction and regulation of differentiation, activation, function and survival of multiple cell types. The interaction between cytokines, chemokines, growth factors and their receptors forms a comprehensive network at the tumor site, which is primary responsible for overall tumor progression and spreading or induction of antitumor immune responses and tumor rejection. Although the general thought is that dendritic cells are among the first cells migrating to the tumor site and recognizing tumor cells for the induction of specific antitumor immunity, the clinical relevance of dendritic cells at the site of the tumor remains a matter of debate regarding their role in the generation of successful antitumor immune responses in human cancers. While several lines of evidence suggest that intratumoral dendritic cells play an important role in antitumor immune responses, understanding the mechanisms of dendritic cell/tumor cell interaction and modulation of activity and function of different dendritic cell subtypes at the tumor site is incomplete. This review is limited to discussing the role of intratumoral cytokine network in the understanding immunobiology of tumor-associated dendritic cells, which seems to possess different regulatory functions at the tumor site.

Establishment of a new interleukin-6 (IL-6) receptor inhibitor applicable to the gene therapy for IL-6-dependent tumor

Interleukin-6 (IL-6) is a key molecule involved in the pathogenesis of several inflammatory diseases and malignancies. Treatments that inhibit IL-6 mitigate the clinical conditions of such diseases. Here, we report on the development of a new receptor inhibitor of IL-6 (NRI) by genetically engineering tocilizumab, a humanized anti-IL-6 receptor monoclonal antibody which specifically blocks IL-6 signaling. This NRI consists of VH and VL of tocilizumab in a single-chain fragment format dimerized by fusing to the Fc portion of human immunoglobulin G(1). The binding activity to IL-6 receptor and the biological activity of the purified NRI were found to be similar to those of parental tocilizumab. Because NRI is encoded on a single gene, it is easily applicable to a gene delivery system using virus vehicles. We administered an adenovirus vector encoding NRI to mouse i.p. and monitored the serum NRI level and growth reduction property on S6B45, an IL-6-dependent multiple myeloma cell line, in vivo. Adequate amount of the serum NRI level to exert anti-IL-6 action could be obtained by the NRI gene introduction combined with adenovirus gene delivery, and this treatment inhibited the in vivo S6B45 cell growth significantly. These findings indicate that NRI is a promising agent applicable to the therapeutic gene delivery approach for IL-6-driven diseases.

Interleukin-4 Promoter Polymorphisms: A Genetic Prognostic Factor for Survival in Metastatic Renal Cell Carcinoma

Purpose

Renal cell carcinoma (RCC) is considered a cytokine-responsive tumor. The clinical course of a patient may thus be influenced by the patient's capacity to produce distinct cytokines. Therefore, cytokine gene polymorphisms in RCC patients were analyzed to determine haplotype combinations with prognostic significance.

Patients and Methods

A selection of 21 single nucleotide polymorphisms within the promoter regions of 13 cytokine genes were analyzed in a cross-sectional single-center study of 80 metastatic RCC patients. Univariate and multivariate analyses and the Cox forward-stepwise regression model were chosen to assess genetic risk factors.

Results

Multivariate Cox regression analysis confirmed by a bootstrap technique identified the heterozygous IL4 genotype −589T−33T/−589C−33C as an independent prognostic risk factor (risk ratio, 3.1; P < .01; 95% CI, 1.4 to 6.9; adjusted for age, sex, and nuclear grading) in metastatic RCC patients. IL4 haplotype −589T−33T and −589C−33C were found with a frequency of 0.069 and 0.925, respectively, which represents a two-fold decrease of IL4 haplotype −589T−33T (P < .01) and an increase of IL4 haplotype −589C−33C frequency (P < .05) in metastatic RCC compared with other white reference study populations. The median overall survival was decreased 3.5-fold (P < .05) in heterozygote patients carrying IL4 haplotype −589T−33T and −589C−33C (3.78 months) compared with patients homozygote for IL4 haplotype −589C−33C (13.44 months). In addition, a linkage disequilibrium between the IL4 gene and the KIF3A gene was detected.

Conclusion

Our findings indicate that IL4 promoter variants influence prognosis in patients with metastatic RCC and suggest that genetically determined interleukin-4 (IL-4) production affects the clinical course of the disease possibly through regulation of immune surveillance.

Interleukin-6 and vascular endothelial growth factor release by renal cell carcinoma cells impedes lymphocyte-dendritic cell cross-talk

Anti-tumour T cell response requires antigen presentation via efficient immunological synapse between antigen presenting cells, e.g. dendritic cells (DC), and specific T cells in an adapted Th1 cytokine context. Nine renal cell carcinoma (RCC) primary culture cells were used as sources of tumour antigens which were loaded on DC (DC-Tu) for autologous T cell activation assays. Cytotoxic activity of lymphocytes stimulated with DC-Tu was evaluated against autologous tumour cells. Assays were performed with 75 grays irradiated tumour cells (Tu irr) and with hydrogen peroxide +/- heat shock (Tu H(2)O(2) +/- HS) treated cells. DC-Tu irr failed to enhance cytotoxic activity of autologous lymphocytes in seven of 13 assays. In all these defective assays, irradiated tumour cells displayed high interleukin (IL)-6 and vascular endothelial growth factor (VEGF) release. Conversely, when tumour cells released low IL-6 levels (n = 4), DC-Tu irr efficiently enhanced CTL activity. When assays were performed with the same RCC cells treated with H(2)O(2) + HS, DC-Tu stimulation resulted in improved CTL activity. H(2)O(2) + HS treatment induced post-apoptotic cell necrosis of tumour cells, totally abrogated their cytokine release [IL-6, VEGF, transforming growth factor (TGF)-beta1] and induced HSP70 expression. Taken together, data show that reduction in IL-6 and VEGF release in the environment of the tumour concomitantly to tumour cell HSP expression favours induction of a stronger anti-tumour CTL response.

IL-4 inhibits the TNF-alpha induced proliferation of renal cell carcinoma (RCC) and cooperates with TNF-alpha to induce apoptotic and cytokine responses by RCC: implications for antitumor immune responses

OBJECTIVE

While previous reports clearly demonstrated antiproliferative effects of IL-4 on renal cell carcinoma (RCC) in vitro, the administration of IL-4 to patients with metastatic RCC in clinical trials could not recapitulate the promising preclinical results. In the present study we wanted to examine the context of IL-4 action and to establish conditions of enhanced IL-4 efficacy.

METHODS

Primary and permanent human RCC cells were cultured in either serum-supplemented or chemically defined, serum-free culture medium in the presence or absence of cytokines. Cell proliferation was assessed as [(3)H]-thymidine incorporation. Cell apoptosis was measured using the fluorescent DNA intercalator 7-aminoactinomycin D and flow cytometry. In addition, culture media conditioned by RCC were subjected to cytokine antibody array and cytokine multiplex analysis.

RESULTS

Our results indicate that the previously reported antiproliferative effects of IL-4 are serum-dependent. Under serum-free conditions, IL-4 failed to exhibit growth-inhibitory effects or was even growth-stimulatory. In a chemically defined, serum-free medium (AIM-V), however, IL-4 inhibited the TNF-alpha induced proliferation of RCC. IL-4 and TNF-alpha synergistically induced apoptosis of RCC as well as a complex cytokine response by RCC, which included the synergistic upregulation of RANTES and MCP-1.

CONCLUSIONS

IL-4 alone has little effect on the spontaneous proliferation of RCC but can prevent the enhancement of proliferation induced by growth promoters like FBS and TNF-alpha. The concomitant growth inhibitory, apoptosis-inducing, and cytokine-enhancing effects of IL-4 in combination with TNF-alpha on RCC support the view that Th2 cytokines may be required for productive immune responses against RCC.

Overexpression of tumor necrosis factor alpha by a recombinant rabies virus attenuates replication in neurons and prevents lethal infection in mice

The effect of tumor necrosis factor alpha (TNF-alpha) on rabies virus (RV) infection of the mouse central nervous system (CNS) was studied, using recombinant RV engineered to express either soluble TNF-alpha [SPBN-TNF-alpha+] or insoluble membrane-bound TNF-alpha [SPBN-TNF-alpha(MEM)]. Growth curves derived from infections of mouse neuroblastoma NA cells revealed significantly less spread and production of SPBN-TNF-alpha+ than of SPBN-TNF-alpha(MEM) or SPBN-TNF-alpha-, which carries an inactivated TNF-alpha gene. The expression of soluble or membrane-bound TNF-alpha was not associated with increased cell death or induction of alpha/beta interferons. Brains of mice infected intranasally with SPBN-TNF-alpha+ showed significantly less virus spread than did mouse brains after SPBN-TNF-alpha- infection, and none of the SPBN-TNF-alpha+-infected mice succumbed to RV infection, whereas 80% of SPBN-TNF-alpha- -infected mice died. Reduced virus spread in SPBN-TNF-alpha+-infected mouse brains was paralleled by enhanced CNS inflammation, including T-cell infiltration and microglial activation. These data suggest that TNF-alpha exerts its protective activity in the brain directly through an as yet unknown antiviral mechanism and indirectly through the induction of inflammatory processes in the CNS.

The intracrine hypothesis: an update

The intracellular actions of peptide hormones, growth factors, as well as of extracellular-signaling enzymes and DNA-binding proteins, either within target cells or within their cells of synthesis has been called intracrine action. Although these intracrine moieties are structurally diverse, they share certain characteristics of synthesis and function. This has given rise to the development of a theory of intracrine action which permits testable predictions to be made regarding the functioning of these peptides/proteins. Here the intracrine hypothesis is briefly described and then recent experimental findings which bear on predictions made earlier on the basis of the theory are discussed. These findings provide new support for the intracrine hypothesis.

Interleukin-6 and new strategies for the treatment of cancer, hyperproliferative diseases and paraneoplastic syndromes

Interleukin-6 (IL-6) is a pleiomorphic cytokine whose growth factor properties play an important role in the development and progression of many types of cancer. IL-6 is produced in response to a variety of stimuli, and is required for the development of T and B lymphocytes to effector cells. In certain neoplasias, such as multiple myeloma, IL-6 is both produced and required for survival by the cancer cell itself. In other neoplasias, IL-6 may come from tissue surrounding the tumour. Thus, therapeutic strategies aimed at inhibiting the production, expression or action of IL-6 would be quite beneficial in the treatment of cancer. Moreover, IL-6 is a pathophysiological factor in several hyperproliferative diseases and the paraneoplastic syndromes that often accompany cancer, such as cachexia and osteoporosis; thus, anti-IL-6 therapy would be useful in treating these entities as well. This expert opinion acquaints the reader with IL-6, its physiological responses, the cancer types with which it is associated, and discusses the current state of therapy aimed at inhibiting it.

A Spliced Isoform of Interleukin 6 mRNA Produced by Renal Cell Carcinoma Encodes for an Interleukin 6 Inhibitor

Interleukin 6 (IL-6) is a multifunctional and pleiotropic cytokine and in renal cell carinoma (RCC), this cytokine exerts proinflammatory, immunosuppressive and growth stimulating properties. A spliced isoform of IL-6 mRNA has been described in peripheral blood mononuclear cells and encodes for a potential protein lacking IL-6 activity. In the present study, a novel spliced form of IL-6 mRNA was found detectable in RCC cell lines, normal renal cells, but not in other tumor cells. This splicing resulted in a frameshift and the generation of multiple stop codon in the spliced IL-6 mRNA. However, two ATG of the third IL-6 exon were identified as translation initiation sites and two truncated IL-6 (tIL-6) with the expected molecular weight were recovered from transfected cell supernatant. The cDNA of a spliced form of IL-6 mRNA detected in RCC lines was cloned, and expressed in a baculovirus expression vector. The functional properties of the tIL-6 were investigated and this protein blocked IL-6 bioactivity, including mitogenic activity on tumor cells. In conclusion, this spliced form of IL-6 mRNA detected in RCC encodes for a truncated IL-6 with IL-6 antagonist properties.