Expression of tumor necrosis factor by different tumor cell lines results either in tumor suppression or augmented metastasis

The Role of Pro-Resolving Lipid Mediators in Colorectal Cancer-Associated Inflammation: Implications for Therapeutic Strategies

Inflammation is a recognized hallmark of cancer that contributes to the development and progression of colorectal cancer (CRC). Anti-inflammatory drugs currently used for the treatment of CRC show many adverse side effects that prompted researchers to propose the polyunsaturated fatty acids-derived specialized pro-resolving mediators (SPMs) as promoters of resolution of cancer-associated inflammation. SPMs were found to inhibit the CRC-associated pro-inflammatory milieu via specific G-coupled protein receptors, although clinical data are still lacking. This review aims to summarize the state-of-the-art in this field, ultimately providing insights for the development of innovative anti-CRC therapies that promote the endogenous lipid-mediated resolution of CRC-associated inflammation.

Significance of Serum Tumor Necrosis Factor-Alpha and its Combination with Her-2 Codon 655 Polymorphism in the Diagnosis and Prognosis of Breast Cancer

Purpose

The present study was conducted to clarify the diagnostic and prognostic significance of TNF-alpha and its combination with HER-2 Ile655Val SNP in breast cancer.

Methods

In this case-control study, 56 consecutive patients with primary breast cancer were prospectively evaluated. The control group consisted of 45 healthy women. Serum concentrations of TNF-alpha were measured by quantitative sandwich enzyme immunoassay (ELISA). HER-2 SNP was genotyped using the PCR-RFLP method.

Results

Serum TNF-alpha was significantly increased in patients compared to controls. ROC analysis indicated a cutoff point of 11.00 pg/mL to classify breast cancer patients (sensitivity, 86%; specificity, 71%). Elevated TNF-alpha levels were associated with larger, poorly differentiated, invasive and advanced-stage tumors, and >3 positive lymph nodes. Regarding HER-2 SNP, patients with Ile-Val and Val-Val genotypes had significant TNF-α elevation compared with homozygous Ile-Ile patients. In multivariate analysis, high serum TNF-alpha remained an independent prognostic factor of worse overall survival; its combination with Val-Val genotype predicted a worse prognosis than high TNF-alpha alone.

Conclusions

Serum TNF-a could be used clinically as a useful tumor marker for diagnosis, disease extent and outcome of breast cancer. The negative impact on survival seems to be enhanced through the interaction with HER-2 Ile655Val SNP.

An integrated method for the identification of novel genes related to oral cancer

Cancer is a significant public health problem worldwide. Complete identification of genes related to one type of cancer facilitates earlier diagnosis and effective treatments. In this study, two widely used algorithms, the random walk with restart algorithm and the shortest path algorithm, were adopted to construct two parameterized computational methods, namely, an RWR-based method and an SP-based method; based on these methods, an integrated method was constructed for identifying novel disease genes. To validate the utility of the integrated method, data for oral cancer were used, on which the RWR-based and SP-based methods were trained, thereby building two optimal methods. The integrated method combining these optimal methods was further adopted to identify the novel genes of oral cancer. As a result, 85 novel genes were inferred, among which eleven genes (e.g., MYD88, FGFR2, NF-κBIA) were identified by both the RWR-based and SP-based methods, 70 genes (e.g., BMP4, IFNG, KITLG) were discovered only by the RWR-based method and four genes (L1R1, MCM6, NOG and CXCR3) were predicted only by the SP-based method. Extensive analyses indicate that several novel genes have strong associations with cancers, indicating the effectiveness of the integrated method for identifying disease genes.

Myeloid-derived suppressor cells promote B-cell production of IgA in a TNFR2-dependent manner

Myeloid-derived suppressor cells (MDSCs) are well known for their capacity to suppress antitumor T-cell responses, but their effects on B-cell function and antibody production remain unclear. Here, we found that MDSCs that accumulated around the germinal center in the spleen of tumor-bearing mice co-located with B cells. In the presence of MDSCs, the antibody reaction to a surrogate antigen was significantly enhanced in mice, especially the immunoglobulin (Ig)A subtype. Co-culture with MDSCs promoted both proliferation and differentiation of B cells into IgA-producing plasma cells in vitro. Interestingly, the cross talk between MDSCs and B cells required cell-cell contact. MDSCs from tumor necrosis factor receptor (TNFR) 2^-/- mice, but not from TNFR1^-/- mice, failed to promote B-cell responses. Further investigation suggested that interleukin-10 and transforming growth factor-β1 were crucial for the MDSC-mediated promotion of IgA responses. These results demonstrate a novel mechanism of MDSC-mediated immune regulation during tumor growth.

A model for cancer-suppressive inflammation

In oncology, inflammation is generally regarded as a cancer-promoting process only. Here, we argue that this view may represent a misleading oversimplification. We present evidence from our own work and from the literature documenting cancer-suppressive aspects of inflammation. We propose that specific types of inflammation, in particular inflammation driven by tumor-specific Th1 cells, may repress rather than promote cancer. Th1 cells collaborate with tumor-infiltrating M1 macrophages to efficiently recognize and eliminate malignant cells. In a Th1 environment, pro-inflammatory cytokines such as interleukin (IL)-1α, IL-1β, IL-6 and tumor-necrosis factor α (TNFα) enhance anti-cancer immunity. Inducing Th1-type inflammation may significantly improve immunotherapeutic strategies against cancer.

Transmembrane TNF-α promotes suppressive activities of myeloid-derived suppressor cells via TNFR2

It has been reported that TNFR2 is involved in regulatory T cell induction and myeloid-derived suppressor cell (MDSC) accumulation, two kinds of immunosuppressive cells contributing to tumor immune evasion. Because transmembrane TNF-α (tmTNF-α) is the primary ligand for TNFR2, we hypothesized that tmTNF-α is mainly responsible for the activation of MDSCs. Indeed, we found that tmTNF-α, rather than secretory TNF-α (sTNF-α), activated MDSCs with enhanced suppressive activities, including upregulating arginase-1 and inducible NO synthase transcription, promoting secretion of NO, reactive oxygen species, IL-10, and TGF-β, and enhancing inhibition of lymphocyte proliferation. This effect of tmTNF-α was mediated by TNFR2, as TNFR2 deficiency significantly impaired tmTNF-α-induced release of IL-10 and NO and inhibition of T cell proliferation by MDSC supernatant. Furthermore, tmTNF-α caused p38 phosphorylation and NF-κB activation, whereas inhibition of NF-κB or p38 with an inhibitor pyrrolidine dithiocarbamate or SB203580 abrogated tmTNF-α-mediated increased suppression of lymphocyte proliferation by MDSCs. Consistently, our in vivo study showed that ectopic expression of uncleavable tmTNF-α mutant by 4T1 cells significantly promoted tumor progression and angiogenesis, accompanied with more accumulation of MDSCs and regulatory T cells in the tumor site, increased production of NO, IL-10, and TGF-β, as well as poor lymphocyte infiltration. In contrast, enforced expression of sTNF-α mutant by 4T1 cells that only released sTNF-α without expression of surface tmTNF-α markedly reduced MDSC accumulation and induced more lymphocyte infiltration instead, showing obvious tumor regression. Our data suggest that tmTNF-α acts as a potent activator of MDSCs via TNFR2 and reveals another novel immunosuppressive effect of this membrane molecule that promotes tumor immune escape.

TNFR-1 on tumor cells contributes to the sensitivity of fibrosarcoma to chemotherapy

Impaired tumor necrosis factor receptor-1 (TNFR-1) signaling has been found in some malignant tumors with poor prognosis. However, the exact role of TNFR-1 signaling in fibrosarcoma remains unclear. Here, we explored the question by comparing the growth of TNFR-1 deficient (Tnfr1 (-)) and TNFR-1 competent (Tnfr1 (+)) fibrosarcoma FB61 cells (FB61-m and FB61-R1) in mice. TNFR-1 expression on fibrosarcoma cells delayed their growth in vivo but not in vitro. Moreover, reduced FB61-R1 tumor growth was also obtained in TNFR-1 knockout mice. The mechanism relies mainly on the TNFR-1-mediated downregulation of vascular endothelial growth factor (VEGF) production by tumor cells. Importantly, treatment of FB61-m tumors with melphalan resulted in a short delay of tumor growth, followed by a quick remission. However, when FB61-R1 tumors were treated with melphalan, tumor growth was similarly delayed at first and then completely rejected. Our results reveal evidence for TNFR-1 on tumor cells as a prerequisite in chemotherapy for fibrosarcoma, and provide novel insight into the therapeutic approach against some types of tumors using TNFR-1 angonist.

Tumor necrosis factor receptor 2-dependent homeostasis of regulatory T cells as a player in TNF-induced experimental metastasis

The cytokine tumor necrosis factor (TNF) has pleiotropic functions both in normal physiology and disease. TNF signals by the virtue of two cell surface receptors, TNF receptor 1 (TNFR1) and TNF receptor 2 (TNFR2). Exogenous TNF promotes experimental metastasis in some models, yet the underlying mechanisms are poorly understood. To study the contribution of host TNFR1 and TNFR2 on tumor cell progression and metastasis, we employed a syngeneic B16F10 melanoma mouse model of lung metastasis combined with in vivo bioluminescence imaging. Treatment of tumor-bearing mice with recombinant human TNF resulted in a significant increase in tumor burden and metastatic foci. This correlated with an increase in pulmonary regulatory CD4(+)/Foxp3(+) T cells. TNF caused an expansion of regulatory T (Treg) cells in vitro in a TNFR2-dependent manner. To assess the contribution of immune cell expression of endogenous TNF and its two receptors on B16F10 metastasis, we generated bone marrow chimeras by reconstituting wild-type mice with bone marrow from different knockout mice. Loss of either TNF or TNFR2 on immune cells resulted in decreased B16F10 metastasis and lower numbers of Treg cells within the lungs of these animals. Selective depletion of Treg cells attenuated metastasis even in conjunction with TNF treatment. We propose a novel mechanism in which TNF activates TNFR2 on Treg cells and thereby expands this immunosuppressive immune cell population. Loss of either TNF or TNFR2 prevents the accumulation of Treg cells and results in a less tolerogenic environment, enabling the immune system to control B16F10 tumor metastasis and growth.

TNF signaling drives myeloid-derived suppressor cell accumulation

TNF, an inflammatory cytokine that is enriched in the tumor microenvironment, promotes tumor growth and subverts innate immune responses to cancer cells. We previously reported that tumors implanted in TNF receptor-deficient (Tnfr-/-) mice are spontaneously rejected; however, the molecular mechanisms underlying this rejection are unclear. Here we report that TNF signaling drives the peripheral accumulation of myeloid-derived suppressor cells (MDSCs). MDSCs expand extensively during inflammation and tumor progression in mice and humans and can enhance tumor growth by repressing T cell-mediated antitumor responses. Peripheral accumulation of MDSCs was drastically impaired in Tnfr-/- mice. Signaling of TNFR-2, but not TNFR-1, promoted MDSC survival through upregulation of cellular FLICE-inhibitory protein (c-FLIP) and inhibition of caspase-8 activity. Loss of TNFRs impaired the induction of MDSCs from bone marrow cells, but this could be reversed by treatment with caspase inhibitors. These results demonstrate that TNFR-2 signaling promotes MDSC survival and accumulation and helps tumor cells evade the immune system.

Tumor necrosis factor-α is associated with positive lymph node status in patients with recurrence of colorectal cancer-indications for anti-TNF-α agents in cancer treatment

INTRODUCTION

The progressive growth of malignancies is accompanied by a decline in the immune response through mechanisms which are poorly understood. Apoptosis and induction of inflammation by tumor released cytokines as tumor escape mechanisms have been proposed to play an important role in colorectal carcinogenesis.

METHODS

Expression of Tumor necrosis factor-alpha (TNF-α) was analyzed in colorectal cancer specimen and the cancer cell line HT-29 by immunohistochemistry and RT-PCR. TNF-α expression on protein and mRNA level were correlated with clinical characteristics and impact on survival. TNFR-1 was co-labelled with TNF-α and CD8+ cytotoxic T cells in immunofluorescence double staining experiments.

RESULTS

94% (n = 98/104) of the patients with CRC expressed TNF-α. High TNF-α expression was significantly associated with positive lymph node stage and recurrence of the tumor. Multivariate analysis revealed high TNF-α expression as an independent prognostic factor. Immunohistochemistry was correlated with RT-PCR results (т = 0.794). Immunofluorescence double staining experiments revealed increased TNFR-1 expression by CD8+ cells.

CONCLUSIONS

TNF-α expression by tumor cells may be an efficient immunological escape mechanism by inflammation-enhanced metastases and probably by induction of apoptosis in tumor-infiltrating CD8+ immune cells resulting in a down regulation of the tumoral immune response. Our data support the role of tumor-derived TNF-α expression as an important promoter of tumoral immune escape mechanisms and malignant progression, and suggest that analysis on either protein (immunohistochemistry) or RNA level (RT-PCR) can be used effectively in this respect. Targeting TNF-α may be a promising option, especially in cases with high TNF-α expression and positive lymph node metastases.

Gambogic acid inhibits TNF-α-induced invasion of human prostate cancer PC3 cells in vitro through PI3K/Akt and NF-κB signaling pathways

AIM

To investigate the mechanisms underlying the inhibitory effect of gambogic acid (GA) on TNF-α-induced metastasis of human prostate cancer PC3 cells in vitro.

METHODS

TNF-α-mediated migration and invasion of PC3 cells was examined using migration and invasion assays, respectively. NF-κB transcriptional activity and nuclear translocation were analyzed with luciferase reporter gene assays, immunofluorescence assays and Western blots. The ability of p65 to bind the promoter of Snail, an important mesenchymal molecular marker, was detected using a chromatin immunoprecipitation (ChIP) assay. After treatment with Snail-specific siRNA, the expression of invasiveness-associated genes was measured using quantitative real-time PCR and Western blot.

RESULTS

GA significantly inhibited the viability of PC3 cells at 1-5 μmol/L, but did not produce cytotoxic effect at the concentrations below 0.5 μmol/L. GA (0.125-0.5 μmol/L) dose-dependently inhibited the migration and invasion of PC3 cells induced by TNF-α (10 ng/mL). Moreover, the TNF-α-mediated activation of phosphatidylinositol-3-OH kinase/protein kinase B (PI3K/Akt) and NF-κB pathways was suppressed by GA (0.5 μmol/L). Furthermore, this anti-invasion effect of GA was associated with regulation of Snail. Snail expression was significantly down-regulated by treatment with GA (0.5 μmol/L) in the TNF-α-stimulated PC3 cells.

CONCLUSION

GA inhibits TNF-α-induced invasion of PC3 cells via inactivation of the PI3K/Akt and NF-κB signaling pathways, which may offer a novel approach for the treatment of human prostate cancer.

Bronchoalveolar lavage fluid alteration in antioxidant and inflammatory status in lung cancer patients

BACKGROUND

Increased oxidative and inflammatory markers have been reported in lung cancer patients, but relatively few studies have investigated the presence of antioxidants both in the local lung environment and in the systemic circulation. Furthermore, it is hypothesized that the immune system activation in vivo is regulated by the redox environment.

OBJECTIVES

To investigate local and systemically circulating antioxidant and inflammatory mediators in lung cancer patients and potential correlations between them.

METHODS

Forty two male patients (mean age 65±8years) with primary lung cancer were studied. Sixteen age and smoking history matched male subjects without any evidence of malignancy served as controls. Total antioxidant status (TAS) and glutathione (GSH), as well as interleukin-1a (IL-1a), interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) were measured in bronchoalveolar lavage fluid (BALF) and serum samples.

RESULTS

A statistically significant increase of TAS and GSH in BALF was observed in lung cancer patients compared to healthy subjects (0.27±0.24 vs. 0.12±0.02mmol/L, p=0.02 and 7.56±4.29 vs. 4.62±2.23μmol/L, p=0.01 respectively). Statistically significant correlations in cancer patients were observed in BALF between TAS and a. IL-1α (r=0.87, p<0.001), b. IL-6 (r=0.52, p=0.001) and c. TNF-α (r=0.67, p<0.001).

CONCLUSIONS

Alteration in antioxidant and inflammatory mediator status was found in lung cancer patients both in serum and in BALF compared to healthy subjects matched for smoking history. Moreover, a positive correlation was observed between antioxidants and pro-inflammatory cytokines, but only locally and not systematically.

TNFR2 expression on non-bone marrow-derived cells is crucial for lipopolysaccharide-induced septic shock and downregulation of soluble TNFR2 level in serum

Persistently high serum levels of soluble tumor-necrosis factor (TNF) receptor 2 (sTNFR2) have been observed in septic shock and many inflammatory diseases. However, its origin and regulation during these pathological processes are still largely unknown. In this study, murine bone marrow (BM) chimeras selectively expressing TNFR2 on either BM-derived or non-BM-derived cells were generated and challenged with lipopolysaccharide (LPS). The results show that TNFR2 expression on non-BM-derived cells is crucial for both the sensitivity of mice to LPS and the downregulation of sTNFR2 in serum. Most importantly, sTNFR2 was released from both BM- and non-BM-derived cells. Non-BM TNFR1 expression influenced the sensitivity of mice to LPS challenge but not the level of serum sTNFR2. These results provide the first in vivo evidence for the origin and regulation of sTNFR2 in serum and could aid in the development of novel anti-TNF strategies against septic shock.

The role of TNF genetic variants and the interaction with cigarette smoking for gastric cancer risk: a nested case-control study

BACKGROUND

The aim of this study was to investigate the role of TNF genetic variants and the combined effect between TNF gene and cigarette smoking in the development of gastric cancer in the Korean population.

METHODS

We selected 84 incident gastric cancer cases and 336 matched controls nested within the Korean Multi-Center Cancer Cohort. Six SNPs on the TNF gene, TNF-alpha-238 G/A, -308 G/A, -857 C/T, -863 C/A, -1031 T/C, and TNF-beta 252 A/G were genotyped. The ORs (95% CIs) were calculated using unconditional logistic regression model to detect each SNP and haplotype-pair effects for gastric cancer. The combined effects between the TNF gene and smoking on gastric cancer risk were also evaluated. Multi dimensionality reduction (MDR) analyses were performed to explore the potential TNF gene-gene interactions.

RESULTS

TNF-alpha-857 C/T containing the T allele was significantly associated with an increased risk of gastric cancer and a linear trend effect was observed in the additive model (OR = 1.6, 95% CI 1.0-2.5 for CT genotype; OR = 2.6, 95% CI 1.0-6.4 for TT genotype). All haplotype-pairs that contained TCT or CCC of TNF-alpha-1031 T/C, TNF-alpha-863 C/A, and TNF-alpha-857 C/T were associated with a significantly higher risk for gastric cancer only among smokers. In the MDR analysis, regardless of smoking status, TNF-alpha-857 C/T was included in the first list of SNPs with a significant main effect.

CONCLUSION

TNF-alpha-857 C/T polymorphism may play an independent role in gastric carcinogenesis and the risk for gastric cancer by TNF genetic effect is pronounced by cigarette smoking.

The role of TNF in cancer

Tumor necrosis factor (TNF) is an extraordinarily pleiotropic cytokine with a central role in immune homeostasis, inflammation, and host defense. Dependent on the cellular context, it can induce such diverse effects as apoptosis, necrosis, angiogenesis, immune cell activation, differentiation, and cell migration. These processes are of great relevance in tumor immune surveillance, and also play crucial roles in tumor development and tumor progression. It is therefore no surprise that TNF in a context-dependent manner displays pro- and antitumoral effects. Modulation of the activity of the TNF-TNF receptor system thus offers manifold possibilities for cancer therapy. In fact, TNF in combination with melphalan is already an established treatment option in the therapy of advanced soft tissue sarcoma of the extremities and many preclinical data suggest that TNF neutralization could also be exploited to fight cancer or cancer-associated complications.

Tumor Necrosis Factor Receptor 2–Mediated Tumor Suppression Is Nitric Oxide Dependent and Involves Angiostasis

Tumor necrosis factor (TNF) binds to two different receptors. Although most of its functions are attributed to TNF receptor 1 (TNFR1), the independent role of TNFR2 is still largely unknown. Using TNFR single or double knock-out mice, we show here that the expression of TNFR2 alone on host cells was sufficient to suppress the growth of TNF-secreting tumors in both immune competent and T/B lymphocyte-deficient severe combined immunodeficiency (SCID) mice. Histologic studies showed that TNF recruited, via TNFR2, large numbers of macrophages and efficiently inhibited angiogenesis in the tumor. In vitro, TNF activated TNFR1-deficient macrophages to produce nitric oxide (NO). Treatment of TNFR1 knock-out mice with L-NAME, a specific NO synthase inhibitor, almost completely eliminated TNF-induced angiostasis and tumor suppression. Moreover, L-NAME acted only during the first few days of tumor growth. Our results show for the first time that TNFR2 expressed on host innate immune cells is sufficient to mediate the antitumor effect of TNF, and NO is necessary for this process, possibly by inhibition of angiogenesis in the tumor.

Tumour necrosis factor-alpha as a tumour promoter

It is becoming more evident that many aspects of tumour promotion arise from persistent and unresolving inflammation. One of the key molecules mediating the inflammatory processes in tumour promotion is the cytokine, tumour necrosis factor-alpha (TNF-alpha). Clinically, elevated serum concentrations and increased expression of TNF-alpha are present in various pre-neoplastic and malignant diseases, compared with serum and tissue from healthy individuals. Although over the last few decades high-dose administration of TNF-alpha has been used as a cytotoxic agent, recent pre-clinical cancer models have provided critical evidence to support the link between chronic, low level TNF-alpha exposure and the acquisition of pro-malignant phenotype (i.e., increased growth, invasion and metastasis). Furthermore, sophisticated cellular systems are being utilised to dissect the crucial role TNF-alpha plays in the communication of stromal/inflammatory cells and tumour cells. Understanding the intricate roles of TNF-alpha in the process of tumour promotion will assist in the development of novel cancer therapeutics.

Selective inhibition of TNF-alpha-induced activation of mitogen-activated protein kinases and metastatic activities by gefitinib

We have reported that the selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, gefitinib (‘Iressa’, ZD1839), suppressed intrahepatic metastasis of hepatocellular carcinoma CBO140C12 cells. In this study, we focused on the tumour necrosis factor-α (TNF-α) signalling pathways. Real-time reverse transcription–polymerase chain reaction showed that TNF-α mRNA was expressed in large quantities in the implanted tumour. Gefitinib inhibited EGF- but not hepatocyte growth factor (HGF)-induced activation of mitogen-activated protein kinase (MAPK) cascades, suggesting selectivity of the inhibitor. However, gefitinib inhibited the TNF-α-induced activation of MAPKs and Akt. In addition, TNF-α-induced metastatic properties including adhesion to fibronectin, mRNA expression of integrin αv, production of matrix metalloproteinase-9 and invasion were inhibited by gefitinib without affecting cell proliferation. Furthermore, the TNF-α-induced responses except for NF-κB activation were blocked by metalloprotease inhibitors, suggesting that gefitinib inhibited the transactivation of EGFR induced by TNF-α. These results suggest that the TNF-α signalling pathway is a possible target of gefitinib in suppressing the intrahepatic metastasis of hepatocellular carcinoma.

Tenascin-W is found in malignant mammary tumors, promotes alpha8 integrin-dependent motility and requires p38MAPK activity for BMP-2 and TNF-alpha induced expression in vitro

Tenascins represent a family of extracellular matrix glycoproteins with distinctive expression patterns. Here we have analyzed the most recently described member, tenascin-W, in breast cancer. Mammary tumors isolated from transgenic mice expressing hormone-induced oncogenes reveal tenascin-W in the stroma around lesions with a high likelihood of metastasis. The presence of tenascin-W was correlated with the expression of its putative receptor, alpha8 integrin. HC11 cells derived from normal mammary epithelium do not express alpha8 integrin and fail to cross tenascin-W-coated filters. However, 4T1 mammary carcinoma cells do express alpha8 integrin and their migration is stimulated by tenascin-W. The expression of tenascin-W is induced by BMP-2 but not by TGF-beta1, though the latter is a potent inducer of tenascin-C. The expression of tenascin-W is dependent on p38MAPK and JNK signaling pathways. Since preinflammatory cytokines also act through p38MAPK and JNK signaling pathways, the possible role of TNF-alpha in tenascin-W expression was also examined. TNF-alpha induced the expression of both tenascin-W and tenascin-C, and this induction was p38MAPK- and cyclooxygenase-dependent. Our results show that tenascin-W may be a useful diagnostic marker for breast malignancies, and that the induction of tenascin-W in the tumor stroma may contribute to the invasive behavior of tumor cells.

Activation-induced cell death limits effector function of CD4 tumor-specific T cells

A number of studies have documented a critical role for tumor-specific CD4(+) cells in the augmentation of immunotherapeutic effector mechanisms. However, in the context of an extensive tumor burden, chronic stimulation of such CD4(+) T cells often leads to the up-regulation of both Fas and Fas ligand, and coexpression of these molecules can potentially result in activation-induced cell death and the subsequent loss of effector activity. To evaluate the importance of T cell persistence in an experimental model of immunotherapy, we used DO11 Th1 cells from wild-type, Fas-deficient, and Fas ligand-deficient mice as effector populations specific for a model tumor Ag consisting of an OVA-derived transmembrane fusion protein. We found that the prolonged survival of Fas-deficient DO11 Th1 cells led to a more sustained tumor-specific response both in vitro and in vivo. Importantly, both Fas- and Fas ligand-deficient Th1 cells delayed tumor growth and cause regression of established tumors more effectively than wild-type Th1 cells, indicating that resistance to activation-induced cell death significantly enhances T cell effector activity.

Ectopic expression of CCL19 impairs alloimmune response in mice

Initiation of an antitumour immune response is characterized by a complex process of chemokine-mediated cell migration and cell-cell interactions. Overexpression of chemokine CCL19 in tumour cells has been shown to result in accelerated tumour rejection under certain experimental conditions, suggesting a novel approach in the therapy of neoplastic malignancies. To investigate CCL19-mediated modulations of cellular immune responses in vivo, we generated a chimeric CCL19-immunoglobulin G2b (IgG2b) Fc fusion protein, which binds to the chemokine receptor CCR7 comparable to native CCL19. CCL19-IgG2b possesses a long-lasting potent chemotactic activity as a result of the extended half-life of Fc fusion proteins. Stable overexpression of CCL19-IgG2b in BALB/c-derived J558L tumour cells fails to support tumour cell rejection following transplantation in syngeneic mice. Moreover, overexpression of CCL19-IgG2b hinders tumour rejection in allogeneic C57BL/6 mice. This phenomenon was accompanied by a six-fold increase of dendritic cells (DCs) isolated from CCL19-IgG2b-secreting tumours when compared to the number of DCs isolated from control parental J558L tumours. While mice bearing the allogeneic parental tumour showed an intense hypercellularity in the draining lymph nodes, no such response could be observed in the draining lymph nodes of mice carrying the CCL19-IgG2b-secreting tumour. We could demonstrate that overexpression of CCL19-IgG2b in tumour cells retains antigen-presenting cells in the tumour mass and prevents DCs from migrating into draining lymph nodes to present antigens and to activate T cells, resulting in an impaired immune response against the tumour.

TNF autovaccination induces self anti-TNF antibodies and inhibits metastasis in a murine melanoma model

TNF is a proinflammatory cytokine involved in the pathogenesis of chronic inflammatory diseases, but also in metastasis in certain types of cancer. In terms of therapy, TNF is targeted by anti-TNF neutralising monoclonal antibodies or soluble TNF receptors. Recently, a novel strategy based on the generation of self anti-TNF antibodies (TNF autovaccination) has been developed. We have previously shown that TNF autovaccination successfully generates high anti-TNF antibody titres, blocks TNF and ameliorates collagen-induced arthritis in DBA/1 mice. In this study, we examined the ability of TNF autovaccination to generate anti-TNF antibody titres and block metastasis in the murine B16F10 melanoma model. We found that immunisation of C57BL/6 mice with TNF autovaccine produces a 100-fold antibody response to TNF compared to immunisation with phosphate-buffered saline vehicle control and significantly reduces both the number (P<0.01) and size of metastases (P<0.01) of B16F10 melanoma cells. This effect is also observed when an anti-TNF neutralising monoclonal antibody is administered, confirming the essential role TNF plays in metastasis in this model. This study suggests that TNF autovaccination is a cheaper and highly efficient alternative that can block TNF and reduce metastasis in vivo and trials with TNF autovaccination are already underway in patients with metastatic cancer.

Tumour necrosis factor alpha: a potential target for the therapy of solid tumours

Tumour necrosis factor alpha (TNFalpha), named for its antitumour properties, was isolated almost 30 years ago. It is a vital member of the multifunctional TNF superfamily and has important roles in immunity and cellular remodelling as well as influencing apoptosis and cell survival. Its central role in inflammation has led to the development of TNFalpha antagonists as effective therapies for rheumatoid arthritis and inflammatory bowel disease. In this review, we discuss the evidence which has accumulated during the past decade that implicates TNFalpha in inflammatory pathways that increase tumorigenesis. There is convincing evidence that under specific conditions TNFalpha is a tumour promoter and helps to produce the toxic effects associated with conventional cancer therapy, such as the cytokine release syndrome and cisplatin-induced nephrotoxicity. Several trials have been set up to investigate the role of TNFalpha antagonists in cancer. It is hoped that these agents inhibit the neoplastic process either alone or in combination with other agents, and ameliorate the side effects of cancer therapy.

Potential of p38 MAP kinase inhibitors in the treatment of cancer

The involvement of chronic inflammation in tumor development and progression is reviewed. Based on the natural history of certain diseases and epidemiology studies, a strong association has been established between particular chronic inflammatory conditions and eventual tumor appearance. Solid tumors require a stroma for their growth and recruit macrophages to synthesize essential growth and angiogenic factors that they do not have the capacity to produce. The microenvironment of the local host tissue appears to be an active participant in exchanging cytokines and enzymes with tumor cells that modify the local extracellular matrix, stimulate migration, and promote tumor angiogenesis, proliferation and survival. The role of p38 MAP kinase as a therapeutic target for treating cancer is discussed.

Interleukin-17 inhibits tumor cell growth by means of a T-cell-dependent mechanism

Interleukin 17 (IL-17) is a proinflammatory cytokine produced by activated CD4(+) memory T cells. We previously showed that IL-17 increased the growth rate of human cervical tumors transplanted into athymic nude mice. To address the possible role of T cells in the biologic activity of IL-17 for tumor control, we grafted 2 murine hematopoietic immunogenic tumors (P815 and J558L) transfected with a complementary DNA encoding murine IL-17 into syngeneic immunocompetent mice. We found that growth of the 2 IL-17-producing tumors was significantly inhibited compared with that of mock-transfected tumors. In contrast to the antitumor activity of IL-17 observed in immunocompetent mice, we observed no difference in the in vivo growth of IL-17-transfected or mock-transfected P815 cells (P815-IL-17 and P815-Neo, respectively) transplanted into nude mice. We then showed that IL-17 increased generation of specific cytolytic T lymphocytes (CTLs) directed against the immunodominant antigens from P815 called A, B, C, D, and E, since all mice injected with P815-IL-17 developed a P815-specific CTL response, whereas only 6 of 16 mice immunized with P815-Neo had a specific CTL response against the antigens. The induction of CTLs was associated with establishment of a tumor-protective immunity. These experiments suggest that T lymphocytes are involved in the antitumor activity of IL-17. Therefore, IL-17, like other cytokines, appears to be a pleiotropic cytokine with possible protumor or antitumor effects on tumor development, which often depends on the immunogenicity of tumor models.

Down-regulation of tumor necrosis factor alpha expression by activating transcription factor 2 increases UVC-induced apoptosis of late-stage melanoma cells

To identify mechanisms whereby activating transcription factor 2 (ATF2) alters the radiation resistance of human melanoma cells, we examined the possible role of ATF2 in UVC-induced apoptosis. Forced expression of full-length or truncated (Delta1-195 amino acids) forms of ATF2 in LU1205, a late-stage human melanoma cell line, elevated the levels of UVC-induced apoptosis. At the same time, either truncated or full-length forms of ATF2 reduced UVC-induced activation of the tumor necrosis factor-alpha (TNFalpha) promoter and decreased expression of TNFalpha. Forced expression of c-Jun in ATF2-expressing melanoma cells restored TNFalpha expression, suggesting that both forms of ATF2 sequestered transcription factors that positively regulate TNFalpha expression in response to UV irradiation. Antagonistic antibodies to Fas, but not to TNFR1, efficiently suppressed UVC-induced apoptosis, suggesting that the Fas pathway mediates the primary apoptotic signal in melanoma cells whereas the TNFR1 pathway elicits a survival signal. Indeed, treatment of melanoma cells with TNFalpha before UVC irradiation partially suppressed UVC-induced apoptosis, further supporting the protective role of TNFalpha in UVC-treated melanoma cells. Taken together, our findings suggest that ATF2 contributes to UVC-induced apoptosis through transcriptional silencing of TNFalpha, which balances Fas-mediated cell death in melanoma.

Synergistic antitumor interaction of human monocyte chemotactant protein-1 gene transfer and modulator for tumor-infiltrating macrophages

PURPOSE

In order to evaluate the possibility of synergistic antitumor gene therapy by the gene delivery of monocyte chemotactant protein-1 (MCP-1/MCAF/IE), the effect of a biological response modulater for macrophages on tumor progression of gene transfected tumor cells was studied.

METHODS

Cachexia-inducing adenocarcinoma cells (cell line colon 26, clone 20) were transfected with either a control plasmid or MCP-1 cDNA.

RESULTS

The production of MCP-1 reached 70-80 ng/ml in vitro when transfectant cells were cultured at a cell density of 1 x 10(5) cells/ml for 3 days. Transfection of MCP-1 cDNA did not affect the growth rate in vitro. Also, MCP-1-transfectants formed tumors after intra-footpad inoculation similar in size to the parental cells. The number of infiltrating macrophages in the primary tumor of the transfectant rapidly increased from the 3rd to 5th day after inoculation as revealed by immunohistochemical staining using an antibody against mouse macrophages. An earlier, greater, but no longer-lasting increase in tumor-infiltrating macrophages was induced in tumors by MCP-1 transfection was compared to that induced by the parent cells. On the 10th day after the inoculation, the tumor-infiltrating macrophages in mice inoculated MCP-1 transfectants were decreased to a level similar to that of the parent cells. Groups of mice were treated intraperitoneally with LPS at different times after the inoculation. Tumor cells producing high levels of MCP-1 were significantly lysed by macrophages treated with LPS, whereas parental or control transfected cells were not. Conclusions. Combination immunotherapy can provide a rationale for the application of MCP-1 treatment to increase immunological responses to cancer.

Immunostimulatory cytokines in somatic cells and gene therapy of cancer

The use of immunostimulatory cytokines has become an increasingly promising approach in cancer immunotherapy. The major goal is the activation of tumour-specific T lymphocytes capable of rejecting tumour cells from patients with low tumour burden or to protect patients from a recurrence of the disease. Strategies that provide high levels of immunostimulatory cytokines locally at the site of antigen have demonstrated pre-clinical and occasional clinical efficacy. Animal models using poorly immunogenic tumours revealed that tumour cells genetically engineered to produce cytokines like IL-2, IL-4, IL-7, IL-12, IFNs, GM-CSF or TNF-alpha were found to be effective in eradicating disseminated tumours. Experimental data obtained from these different animal models are reviewed here to provide an overview of this rapidly evolving field. The data obtained so far from clinical trials involving cytokine gene-modified cells have provided important information regarding the feasibility, safety, immunological effects and occasional clinical responses.

Minimal residual disease: detection, clinical relevance, and treatment strategies

Improvement of established treatment strategies for cancer has resulted in increased survival times for patients with malignancies. However, success of surgery, chemotherapy, and radiotherapy is limited, as even combined and repeated therapy regimens and high-dose chemotherapy can only reduce tumor burden by several logarithmic steps and are not able to completely eradicate all neoplastic cells. If clinically complete remission is achieved--that is, if no sign of the tumor is detectable by standard diagnostic procedures, remaining minimal residual disease (MRD) can eventually give rise to clinically manifest relapse. More sensitive methods are, therefore, necessary to detect single tumor cells for exact staging, to assess the metastatic potential of an individual tumor, to evaluate the sensitivity to prior therapy, and to detect MRD-positive patients with remaining malignant cells who are at higher risk for relapse. Novel treatment approaches must be created to eradicate minimal residual disease after conventional therapy.

Modulation of the plasminogen activation system by inflammatory cytokines in human colon carcinoma cells

Inflammation may promote malignant invasion by enhancing cancer cell-associated proteolysis. Here we present the effect of inflammatory cytokines on the plasminogen activation system of eight human colon carcinoma cell lines. Tumour necrosis factor alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) increased in several, but not all, cell lines the production of urokinase-type plasminogen activator (uPA), tissue-type PA (tPA) and plasminogen activator inhibitor type 1 (PAI-1) as analysed by zymography, enzyme immunoassays and Northern analysis. Interleukin 6 (IL-6) had no effect. uPA receptor (uPAR) mRNA levels were also upregulated. However, each individual cell line responded differently following exposure to TNF-alpha or IL-1 beta. For example, there was a dose-dependent up-regulation of uPA and PAI-1 in SW 620 cells, whereas increased uPA production in SW 1116 cells was not accompanied by an increase in PAI-1. The TNF-alpha stimulatory effect was blocked by anti-TNF-alpha Fab fragments. All cell lines expressed both types of TNF receptor mRNAs, whereas no transcript for TNF-alpha, IL-1 beta, IL-6, IL-6 receptor or the IL-1 receptors was found. Our results demonstrate that TNF-alpha and IL-1 beta stimulate the plasminogen activation system in tumour cell but the responses differed even in cells derived from the same tissue origin.

TNF promotes metastasis by impairing natural killer cell activity

Inflammatory mediators such as tumor necrosis factor (TNF) and interleukin-1 enhance tumor colony formation in different models of experimental and spontaneous metastasis. The involvement of the natural killer (NK) cell system in this process was investigated. Tumor necrosis factor does not appear to act directly on tumor cells by reducing their susceptibility to the cytotoxic action of NK cells but rather impairs NK activity in tumor-bearing mice. Such impairment of the natural killer system might be one means by which TNF supports tumor colony formation. Even though the metastasis- enhancing effect of TNF remained detectable in mice which have a greatly reduced NK cell cytotoxic activity due to a defect in the bg locus, normal mice which were depleted of NK cells by antibody treatment did not show enhanced metastasis after TNF injection. Therefore, the TNF-enhanced metastasis can only be seen as long as some NK cell function is operating in the animals.

Tumor necrosis factor-alpha expression in human primary malignant malanoma and it relationship to tumor infiltration by CD3+ cells

Optimal conditions for immunohistochemical staining of tumor necrosis factor-alpha (TNF-alpha) in paraffin-embedded tissue sections were established to investigate TNF-alpha expression in human primary malignant melanomas. Seventeen malignant melanomas of the nodular (NMM) and superficially spreading (SSM) subtypes were analyzed. Twelve of these were TNF-alpha+, while 5 did not stain for the cytokine. To evaluate how TNF-alpha expression affected the immune response to the tumors, infiltration by CD3+ and mac387+ cells was investigated in NMM. TNF-alpha expression seemed to selectively affect the capability of T cells to infiltrate the tumors since TNF-alpha+ tumors were found to have significantly lower levels of infiltrating CD3+ cells, while there was no difference in numbers of mac387+ cells. These results demonstrate that TNF-alpha is variably expressed in primary malignant melanoma in vivo and that the T-cell response to TNF-alpha-expression NMM is inhibited.

NO2/NO3 and cytokine plasma profiles under different postoperative parenteral nutrition regimens

Both nitric oxide and cytokines are considered mediators of the acute-phase response in humans, and their early postoperative period plasma levels have been found to be of prognostic value. On the other hand, it has been suggested that the fatty emulsions used in total parenteral nutrition (TPN) may induce changes in macrophage function. In the present study we investigated the postoperative evolution of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), interleukin-6 (IL-6), and nitrate/nitrite plasma levels under three different TPN regimens. Twenty-one patients diagnosed with upper digestive tract neoplasm, without preoperative TPN, and having undergone radical surgery, were randomly assigned to three groups: Group I, all nonprotein calories supplied by hypertonic glucose solution: Group II, 55% of the nonprotein calories supplied by glucose and 45% by 20% long-chain triacylglycerides emulsion (LCT) (Intralipid 20%, Kabi-Pharmacia); Group III, same as Group II, but a 20% emulsion of a mixture of medium-chain and long-chain triacylglycerides (MCT/LCT) (Lipofundina MCT/LCT 20%, B. Braun) was used instead of LCT. Blood samples were obtained on postoperative Days 1-5 and 10, 3 h after ending the lipid infusion. In all the three groups IL-1, IL-6, and TNF-alpha levels rose after surgery, peaking at Day 2, whereas NO2/NO3 levels had their peak at Day 3. Day-to-day comparison of plasma levels of cytokines and NO2/NO3 between the investigated groups did not show any statistical significance. Differences between group means were not found when the areas under the curve over the first 5 postoperative days were compared (1.72 +/- 0.25, Group I; 1.88 +/- 0.34, Group II; and 2.52 +/- 0.50, Group III, for TNF-alpha; 1.79 +/- 0.12, Group I; 1.92 +/- 0.18, Group II; and 1.50 +/- 0.12, Group III, for NO2/NO3). We conclude that the different parenteral nutrition regimens studied do not evoke alterations in cytokine and NO2 + NO3 levels in the patient groups investigated in this study.

The thymidine kinase/ganciclovir-mediated "suicide" effect is variable in different tumor cells

The herpes simplex virus thymidine kinase (HSV-TK) converts ganciclovir (GCV) into a toxic product and allows selective elimination of TK+ cells in vitro and in vivo. It is currently being used in clinical gene therapy trials as a therapeutic gene or as a safety marker. We have analyzed the susceptibility of different tumor cell lines to the TK/GCV-mediated "suicide" effect. Therefore, tumor cells TSA, J558L, EB, and ESB and, as a control, NIH-3T3 cells were infected with a retrovirus containing a hygromycin/TK fusion gene. All cell lines were sensitive to GCV in vitro; however, the concentration of GCV and the time needed to eliminate tumor cells completely considerably varied between different tumor cell lines. TSA-TK cells were completely eliminated within 10 days in 1 microg/ml GCV, whereas ESB-TK cells required 22 days in 10 microg/ml GCV. When two cell lines were examined, the differing sensitivity to GCV in vitro correlated with the ability to eradicate TK+ tumors in vivo. TSA-TK tumors could be eliminated in almost all animals by systemic GCV administration, whereas ESB-TK tumors were completely resistant. Different sensitivity to GCV was not due to different TK expression levels because the cells were similarly resistant to hygromycin, and Western blot analysis with an anti-TK antiserum revealed similar protein amounts in TSA/TK and ESB-TK cells. Together, the results demonstrate that tumor cells are highly different concerning the susceptibility to the TK/GCV effect, which, however, may be tested for in vitro.

Cytokine modulation of epidermal growth factor receptor expression on bladder cancer cells is not a major contributor to the antitumour activity of cytokines

Epidermal growth factor is a potential mitogen for many different human tumours. Its effect is mediated via a bispecific receptor (EGFR), the expression of which correlates well with invasive disease. We investigated the modulation of EGFR by cytokines produced following bacillus Calmette Guerin (BCG)-immunotherapy. Our data demonstrate the IFN gamma, TNF alpha and IL-1 alpha can decrease the expression of EGFR on some bladder tumour cell lines. IFN gamma reduced EGFR expression on two of eight cell lines (RT4, SD). However, IL-1 and TNF did not share this activity. When cells were treated with a combination of all three cytokines, EGFR was decreased on three cell lines (RT4, RT112, SD) and furthermore, the change in the receptor expression was even more marked. Treatment with phorbol ester (thereby activating protein kinase C) resulted in rapid disappearance of the receptor from the cell surface. Interestingly, the decrease of EGFR expression did not require protein synthesis. Although the cytokines studied could down modulate EGFR, this only occurred on three out of eight cell lines; therefore, it is unlikely that the suppression of proliferative activity caused by cytokine-induced decrease of EGFR expression is central to the antitumour action of BCG therapy, but in a proportion of tumours this mechanism may be involved.

Promotion of experimental liver metastasis by tumor necrosis factor

Models for experimental metastasis were established to investigate the influence of rmTNF on tumor-colony formation in the liver. Highly metastatic lymphoma tumor cells were either injected i.v. or inoculated s.c. to form spontaneous metastases. In both systems, administration of rmTNF to the animals led to significant enhancement of the number of liver metastases in comparison with control groups. The number of metastatic tumor-cell colonies at an early stage of metastasis was increased, as well as the number of surface metastases in a late stage. Consequently, TNF-treated animals revealed a higher mortality. The optimal time for TNF to exert this metastasis-enhancing effect was found to be 7 days after tumor inoculation. In vitro adhesion of the lymphoma tumor cells to a mouse endothelioma cell line was strongly inhibited by monoclonal antibodies interfering with the interaction of VCAM-1 with VLA-4. These results support and extend earlier results with a fibrosarcoma lung colonization model. In addition, they show that stimulation of the immune system in tumor-bearing hosts activates tumor-promoting pathways, in addition to having possible beneficial effects.

Overcoming the metastasis-enhancing potential of human tumor necrosis factor alpha by introducing the cell-adhesive Arg-Gly-Asp sequence

A mutein, F4168, of human tumor necrosis factor alpha (hTNF-alpha) containing the cell-adhesive Arg-Gly-Asp (RGD) sequence near the N terminus was constructed. In contrast to hTNF-alpha, the mutein had binding activity to B16F10/L5 melanoma cells similar to that of fibronectin or laminin, indicating that the adhesive nature of the RGD sequence is conferred upon hTNF-alpha. Introduction of the RGD sequence did not alter the antitumor potential of hTNF-alpha. Simultaneous injection of F4168 and B16F10/L5 melanoma cells into mice did not enhance metastasis formation in lungs, whereas hTNF-alpha significantly promoted it. Enhancement of spontaneous lymph node metastasis of B16F10/L5 cells was also evident in TNF-alpha- but not in F4168-treated mice. In the spontaneous lymph node metastasis model of MethA fibrosarcoma, F4168 injection inhibited metastasis formation more effectively than hTNF-alpha. B16F10/L5 melanoma cells treated with hTNF-alpha enhanced not only their binding activity to laminin but also their invasive potential into Matrigel, whereas F4168 showed no such enhancement. These results suggest that F4168 is a low-toxicity mutein of hTNF-alpha.

Production of cytokines by human melanoma cells and melanocytes

Experimental animal models have shown that various cytokines, depending of their specific properties, may support growth and metastasis of tumor cells or even lead to tumor rejection. The analysis of expression of cytokine genes by melanoma cell lines indicated that melanoma cells constitutively produce both autostimulatory and inhibitory cytokines. Using reverse transcriptase polymerase chain reaction analysis, simultaneous expression of several cytokines, including interleukin-1 beta (IL-1 beta), IL-6, IL-8, tumor necrosis factor-alpha, and granulocyte-macrophage colony-stimulating factor, by melanoma cells was found. The same cytokine transcripts were detected in melanocytes, suggesting that cells of the melanocytic lineage express a specific pattern of cytokines in vitro. All these cytokines are known to be able to stimulate effector cells of the host. Additionally, production of mRNA for IL-10, a cytokine with potential immunosuppressive properties, was detected in melanoma cells and melanocytes. These and other cytokines are likely to be involved in the immune response to cancer and at this time it is unknown what the net effects of multiple cytokines are on the outcome of the host response to tumor.

Tumor necrosis factor-alpha mRNA and protein in endometrial tumors: analysis by in situ hybridization and immunocytochemistry

Abnormal expression of polypeptide growth factors and their receptors is closely associated with tumorigenic transformation. In this study tumor necrosis factor-alpha (TNF-alpha) mRNA and protein were analyzed in polyps and proliferative lesions of endometrium as well as in low and high grade endometrial tumors by using in situ hybridization and immunocytochemistry. All samples contained products of the TNF-alpha gene. Histochemical scores (HS), which reflect the proportion of cells positive for TNF-alpha message or protein and the intensities of the signals, were higher for epithelial than for stromal cells. Benign lesions (endometrial polyps) contained little TNF-alpha mRNA or protein, whereas specific message was abundant in proliferative lesions (hyperplasia, adenofibroma). Although neoplastic cells in both low and high grade endometrial tumors contained TNF-alpha mRNA, two major differences were observed: HS for TNF-alpha mRNA were significantly less in low grade than in high grade neoplasms, and TNF-alpha message was restricted to the nucleus in low grade adenocarcinoma cells but was abundant in the cytoplasm of high grade tumor cells. In contrast to cells in benign and proliferative lesions, TNF-alpha protein scores in endometrial tumor cells were inversely rather than positively correlated with TNF-alpha mRNA scores. Collectively, the findings in this study are consistent with the postulate that TNF-alpha is useful to endometrial tumor cells and suggest that production may increase as cells diverge from normal.

Retrovirus-mediated gene transfer in cancer therapy

Retroviral vectors are one of the most promising systems for the transfer and the expression of therapeutic genes in human gene therapy protocols. This review will focus both on the advantages and intricacies of retroviral vectors themselves as well as on the application of these vector systems in experimental and clinical cancer therapy protocols. Therefore, the retrovirus life cycle and the general features of retroviral vectors, including possible targeting strategies with retroviral vectors, are overviewed. These topics are followed by the presentation of genes with emphasis on their potential as tools in somatic cell cancer therapy (cytokines, lymphokines, colony-stimulating growth factors, suppressor genes, antisense oncogenes, suicide genes). Finally, a prospect on the application of retroviral vectors will be described.

Nitrite/nitrate and cytokine levels in bronchoalveolar lavage fluid of lung cancer patients

BACKGROUND

Cytokines are produced by tumor cells in vitro, but evidence for in vivo increased production of cytokines in cancer patients is controversial. Conversely, nitric oxide (NO) is implicated increasingly in the mediation of cytokine effects. Lung cancer patients may show an increased local production of cytokines and NO, and chronic paracrine exposure of epithelial lung cells to these medicators may influence the production of surfactant phosphatidylcholine.

METHODS

The presence of the cytokine tumor necrosis factor (TNF alpha), interleukin-1 (IL-1), and interleukin-6 (IL-6), as well as NO, cyclic guanosine 3'5' monophosphate (cGMP) and phosphatidylcholine levels in bronchoalveolar lavage fluid (BLF) of lung cancer patients were investigated. Bronchoalveolar lavage fluid was obtained from 30 male smokers: 22 patients with squamous cell lung cancer and 8 subjects without cancer.

RESULTS

When compared with the control subjects, the cancer patients had elevated BLF levels of TNF alpha (1.58 +/- 0.47 vs. 0.04 +/- 0.02 pg/microgram protein, P < 0.001), IL-6 (1.39 +/- 0.29 vs. 0.04 +/- 0.02 pg/microgram protein, P < 0.001), and NO2-/NO3- (23.3 +/- 5.6 vs 1.1 +/- 0.6 nmol/mg protein, P < 0.001). However, phosphatidylcholine levels were lower in those with cancer than in the control subjects (3.0 +/- 1.2 vs. 24.8 +/- 6.4 micrograms protein, P < 0.001).

CONCLUSIONS

The results showed in vivo production of inflammatory cytokines in human lung cancer and increased tumor-associated NO production, as suggested by increased levels of nitrite/nitrate in the BLF. A decreased phosphatidylcholine content in the BLF also was found in patients with lung cancer.

Treatment of established lung metastases with tumor-infiltrating lymphocytes derived from a poorly immunogenic tumor engineered to secrete human TNF-alpha

The growth of a poorly immunogenic methylcholanthrene (MCA)-induced murine (m) sarcoma genetically engineered to secrete human (h) TNF-alpha (MCA-102-hTNF) was studied. MCA-102-hTNF tumor cells were implanted in animals bearing three- or 7-day pulmonary metastases established with the parental line MCA-102-WT (wild type). This model approximates the clinical situation in which patients with metastatic cancer would be vaccinated with autologous tumor genetically modified to stimulate the host immune response. Reduction in the number of pulmonary metastases was occasionally seen but was not consistently reproducible. Other cytokine-producing tumors had either no effect on distant pulmonary metastases (mIL-4, IFN-gamma) or a mild, inconclusive effect similar to hTNF-alpha (mTNF-alpha). Significant growth inhibition of MCA-102-hTNF was noted in animals bearing pulmonary metastases. This inhibition was: 1) tumor specific (regression occurred only in animals bearing pulmonary metastases from the same parental line), 2) TNF specific (it was inhibited by in vivo administration of anti hTNF mAbs), 3) dependent on cellular immunity (immune-depletion with anti-CD4 or CD8 mAbs permitted growth). Tumor-infiltrating lymphocytes (TIL) could not be grown from MCA-102-WT or MCA-102-hTNF tumors nor from MCA-102-WT subcutaneous implants in mice bearing MCA-102-WT pulmonary metastases. However, TIL could be grown from hTNF-secreting tumors implanted in mice bearing MCA-102-WT metastases. These TIL were therapeutic against established lung metastases from the parental tumor in adoptive immunotherapy models. These studies suggest a strategy for using gene modified tumors for the therapy of established cancer.