Mice deficient in tumor necrosis factor-alpha are resistant to skin carcinogenesis.

Given the associations between chronic inflammation and epithelial cancer, we studied susceptibility to skin carcinogenesis in mice deficient for the pro-inflammatory cytokine TNF-alpha (refs. 5,6). TNF-alpha(-/-) mice were resistant to development of benign and malignant skin tumors, whether induced by initiation with DMBA and promotion with TPA or by repeated dosing with DMBA. TNF-alpha(-/-) mice developed 5-10% the number of tumors developed by wild-type mice during initiation/promotion and 25% of those in wild-type mice after repeated carcinogen treatment. TNF-alpha could influence tumor and stromal cells during tumor development. The early stages of TPA promotion are characterized by keratinocyte hyperproliferation and inflammation. These were diminished in TNF-alpha(-/-) mice. TNF-alpha was extensively induced in the epidermis, but not the dermis, in TPA-treated wild-type skin, indicating that dermal inflammation is controlled by keratinocyte TNF-alpha production. Deletion of a TNF-alpha inducible chemokine also conferred some resistance to skin tumor development. TNF-alpha has little influence on later stages of carcinogenesis, as tumors in wild-type and TNF-alpha(-/-) mice had similar rates of malignant progression. These data provide evidence that a pro-inflammatory cytokine is required for de novo carcinogenesis and that TNF-alpha is important to the early stages of tumor promotion. Strategies that neutralize TNF-alpha production may be useful in cancer treatment and prevention.

Immune human lymphocytes produce an acid-labile alpha-interferon.

We have described in this paper a novel human interferon (IFN) with antigenic and cross-species reactivity of alpha-IFN and physicochemical properties of gamma-IFN. This IFN is produced by normal peripheral blood mononuclear cells during an immune response but has also been associated with autoimmune disease (10). The system described here will be useful in elucidating the biological significance and cell of origin of this IFN.

Guidelines for the welfare and use of animals in cancer research.

Animal experiments remain essential to understand the fundamental mechanisms underpinning malignancy and to discover improved methods to prevent, diagnose and treat cancer. Excellent standards of animal care are fully consistent with the conduct of high quality cancer research. Here we provide updated guidelines on the welfare and use of animals in cancer research. All experiments should incorporate the 3Rs: replacement, reduction and refinement. Focusing on animal welfare, we present recommendations on all aspects of cancer research, including: study design, statistics and pilot studies; choice of tumour models (e.g., genetically engineered, orthotopic and metastatic); therapy (including drugs and radiation); imaging (covering techniques, anaesthesia and restraint); humane endpoints (including tumour burden and site); and publication of best practice.

A clinical study assessing the tolerability and biological effects of infliximab, a TNF-alpha inhibitor, in patients with advanced cancer.

BACKGROUND: Tumour necrosis factor-alpha (TNF-alpha) is an important regulator of the chronic inflammation contributing to tumour progression. Infliximab, an anti-TNF-alpha monoclonal antibody was investigated in this trial of patients with advanced cancer. The primary objectives were to determine the safety profile and biological response of infliximab in a cancer population. Clinical response was a secondary objective. PATIENTS AND METHODS: Forty-one patients received infliximab at 5 mg/kg (n = 21) or 10 mg/kg (n = 20) i.v. at 0 and 2 weeks and then every 4 weeks. Post-treatment samples were measured for changes in plasma and serum TNF-alpha, CCL2, IL-6 and C-reactive protein (CRP). RESULTS: Infliximab was well tolerated with no dose-limiting toxic effects. At both doses of infliximab, neutralisation of serum TNF-alpha was observed after 1 h while plasma CCL2, IL-6 and serum CRP were decreased 24 and 48 h following infliximab administration. Seven patients experienced disease stablisation (range 10-50+ weeks). There was no evidence of disease acceleration in any patient. CONCLUSIONS: Infliximab treatment was safe and well tolerated in patients with advanced cancer. There was evidence of biological activity with baseline TNF-alpha and CCL2 being correlated with infliximab response.

Human ovarian surface epithelial cells immortalized with hTERT maintain functional pRb and p53 expression.

OBJECTIVE: Cell immortalization is considered to be a prerequisite status for carcinogenesis. Normal human ovarian surface epithelial (OSE) cells, which are thought to be the origin of most of human ovarian carcinomas, have a very limited lifespan in culture. Establishment of immortalized OSE cell lines has, in the past, required inactivation of pRb and p53 functions. However, this often leads to increased chromosome instability during prolonged culture. MATERIALS AND METHODS: In this study, we have used a retroviral infection method to overexpress human telomerase reverse transcriptase (hTERT) gene, in primary normal OSE cells, under optimized culture conditions. RESULTS: In vitro and in vivo analysis of hTERT-immortalized cell lines confirmed their normal epithelial characteristics. Gene expression profiles and functional analysis of p16(INK4A), p15(INK4B), pRb and p53 confirmed the presence of their intact functions. Our study suggests that inactivation of pRb and p53 is not necessary for OSE immortalization. Furthermore, down-regulation of p15(INK4B) in the immortalized cells may indicate a functional role for this protein in them. CONCLUSION: These immortal OSE cell lines are likely to be an important tool for studying human OSE biology and carcinogenesis.

Tumor necrosis factor and its receptors in human ovarian cancer. Potential role in disease progression.

The gene for tumor necrosis factor, TNF, was expressed in 45 out of 63 biopsies of human epithelial ovarian cancer. In serous tumors, there was a positive correlation between level of TNF expression and tumor grade. TNF mRNA was found in epithelial tumor cells and infiltrating macrophages, whereas TNF protein localized primarily to a subpopulation of macrophages within and in close proximity to tumor areas. mRNA and protein for the p55 TNF receptor gene localized to the tumor epithelium and tumor, but not to stromal macrophages. The p75 TNF receptor was confined to infiltrating cells. Cells expressing TNF mRNA were also found in ovarian cancer ascites and TNF protein was detected in some ascitic fluids. In 2 out of 12 biopsies of normal ovary, TNF mRNA was detected in a minority of cells in the thecal layer of the corpus luteum. Serum levels of TNF and its soluble receptor did not correlate with extent of TNF expression in matched biopsies. Northern and Southern analysis revealed no gross abnormality of the TNF gene. The coexpression of TNF and its receptor in ovarian cancer biopsies suggests the capacity for autocrine/paracrine action. TNF antagonists may have therapeutic potential in this malignancy.

The detection and localization of monocyte chemoattractant protein-1 (MCP-1) in human ovarian cancer.

Chemokines may control the macrophage infiltrate found in many solid tumors. In human ovarian cancer, in situ hybridization detected mRNA for the macrophage chemokine monocyte chemoattractant protein-1 (MCP-1) in 16/17 serous carcinomas, 4/4 mucinous carcinomas, 2/2 endometrioid carcinomas, and 1/3 borderline tumors. In serous tumors, mRNA expression mainly localized to the epithelial areas, as did immunoreactive MCP-1 protein. In the other tumors, both stromal and epithelial expression were seen. All tumors contained variable numbers of cells positive for the macrophage marker CD68. MCP-1 mRNA was also detected in the stroma of 5/5 normal ovaries. RT-PCR demonstrated mRNA for MCP-1 in 7/7 serous carcinomas and 6/6 ovarian cancer cell lines. MCP-1 protein was detected by ELISA in ascites from patients with ovarian cancer (mean 4.28 ng/ml) and was produced primarily by the cancer cells. Human MCP-1 protein was also detected in culture supernatants from cell lines and in ascites from human ovarian tumor xenografts which induce a peritoneal monocytosis in nude mice. We conclude that the macrophage chemoattractant MCP-1 is produced by epithelial ovarian cancer and that the tumor cells themselves are probably a major source. MCP-1 may contribute to the accumulation of tumor-associated macrophages, which may subsequently influence tumor behavior.

Interferons and cytokines on a grand scale.

The first joint meeting of the International Cytokine Society and the International Society for Interferon and Cytokine Research was held in Geneva on 6-10 October 1996. In this report, Fran Balkwill and Paula Pitha relate how signal transduction, molecular genetics and structural biology have helped to provide a unifying focus to presentations dealing with 100+ cytokines and an even larger assortment of receptors and associated signal transducers.

Phase I study of bryostatin 1: assessment of interleukin 6 and tumor necrosis factor alpha induction in vivo. The Cancer Research Campaign Phase I Committee.

BACKGROUND: Many oncogenes have been shown to code for growth factor receptors that are involved in regulation of cell growth and proliferation and can activate transcription via protein kinase C. Bryostatin 1, a partial agonist of protein kinase C, has demonstrated potent antitumor activity in vitro and in vivo in human tumor xenografts. PURPOSE: The aim of this phase I study was to determine the optimal dosage and toxicity profile of bryostatin 1 and its influence on cytokine release in vivo. METHODS: Three successive cohorts consisting of 35 patients with various malignant tumors were treated with bryostatin 1 by intravenous infusion over 1 hour as follows: cohort A--35 micrograms/m2 (three patients) or 50 micrograms/m2 (eight patients) once every 2 weeks; cohort B--25 micrograms/m2 once a week (eight patients); and cohort C--25 micrograms/m2 once a week for 3 weeks, with no treatment during the 4th week (16 patients). Plasma levels of tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) were measured by immunoradiometric assay and by radioimmunoassay, respectively. RESULTS: The dose-limiting toxicity was grade 3 or 4 myalgia in four of 11 patients in cohort A, in two of eight in cohort B, and in none of 16 in cohort C. Occurrence of myalgia was dose related. There was no significant myelosuppression, apart from a small and transient fall in platelet count. Six patients experienced acute but transient skin flushing, dyspnea, hypotension, and bradycardia, probably related to the bryostatin 1 vehicle. TNF-alpha and IL-6 were detected in plasma at 2 and 24 hours after treatment, respectively, and the levels were dose related (P = .02). Two patients with metastatic malignant melanoma had partial remission after three or four cycles of therapy; remission lasted 6 weeks and 10+ months, respectively. CONCLUSIONS: The dose-limiting toxicity of bryostatin 1 was myalgia. Plasma IL-6 and TNF-alpha concentrations were increased within 24 hours of therapy. Antitumor activity against malignant melanoma was observed early in the course of treatment. IMPLICATIONS: The recommended dosage of bryostatin 1 for phase II studies is 25 micrograms/m2 by intravenous infusion for 1 hour once a week for 3 weeks, with no treatment in the 4th week. IL-6 and TNF-alpha plasma concentrations may be useful in monitoring biological activity of bryostatin 1. Future studies should explore use of this drug with other conventional immune modulators and conventional cytotoxic drugs.

Positive interactions between human interferon and cyclophosphamide or adriamycin in a human tumor model system.

Human lymphoblastoid interferon strongly increased the anti-tumor activity of suboptimal doses of two commonly used anti-cancer drugs, cyclophosphamide and Adriamycin, on a human breast tumor xenograft growing in nude mice. A combination of human lymphoblastoid interferon with either of these agents caused regression and in some cases total disappearance of tumors at doses of drug and interferon that, used singly, were capable only of inhibiting tumor growth. The combined therapy also resulted in a greatly increased survival. Studies with interferon and cyclophosphamide indicated that the antitumor activity was greatest when the two agents were administered simultaneously rather than sequentially.

Investigation of cytokine gene expression in human colorectal cancer.

RNA was extracted from 28 samples of colorectal cancer and 26 samples of adjacent normal bowel. Northern blotting analysis showed the presence of mRNA for tumor necrosis factor (TNF) in 15 of 28 cancer samples and 6 of 26 matched normal areas. In 10 patients, TNF mRNA was found only in the tumor; in 5, TNF mRNA was seen in tumor and normal areas; and in only 1 was TNF mRNA seen in the normal, but not the malignant, area. The expression of TNF mRNA was not related to the stage of disease, degree of lymphocyte infiltration, or necrosis in the tumor. Blots were reprobed for gamma-interferon, interleukin (IL) 1 alpha and beta, IL-6, and transforming growth factor beta 1 mRNA. One tumor sample was positive for IL-1 beta, and one normal sample expressed interferon gamma mRNA. All samples had transforming growth factor beta 1 mRNA, and there was no obvious difference between levels in tumor tissues or adjacent normal areas. In situ hybridization studies with a TNF riboprobe showed that TNF mRNA was only detectable in a small minority of mononuclear and predominantly stromal cells. Immunohistochemistry on sequential sections showed that CD4- and CD8-positive lymphocytes, and macrophages, were present in the stroma. An antibody to the macrophage C3b receptor identified a minority population whose distribution corresponded closely to the cells labeled with the TNF riboprobe.

Matrix metalloprotease 2 (MMP-2) and matrix metalloprotease 9 (MMP-9) type IV collagenases in colorectal cancer.

Using quantitative zymography, we measured activity of the type IV collagenases metalloprotease 2 (MMP-2) and MMP-9 in 192 biopsies from colorectal carcinomas, adenomas, and normal bowel. The median level of MMP-9 in samples from Dukes' stage A (n = 18) or C (n = 48) tumors was significantly higher than in stage B carcinomas (n = 65), adenomas (n = 25), and normals (n = 36; P = 0.0001). The median level of active MMP-2 was significantly higher in stage A or C compared with adenomas (P = 0.0001) and normals (P = 0.0001). The median level of inactive MMP-2 was higher in all Dukes' stages compared with normals and adenomas (P = 0.0001). There was a significant increase in inactive MMP-2 from Jass prognostic groups I-IV (P = 0.006) but no correlation with the active enzyme. MMP activity was not related to tumor differentiation, colon versus rectal location, or disease-free, 5-year survival. All groups expressed mRNA for both enzymes, but there were quantitative and locational differences in MMP-2 mRNA expression between normal, benign, and malignant tissues. Thus MMP-2 is controlled at the level of mRNA and protein production and activation in colorectal cancer, and active MMP-2 and MMP-9 enzymes are associated strongly with Dukes' A and C stages of the disease. Variations in MMP levels with the stage or prognostic group of colorectal cancer reflect their differing stromal content.

Enhancement of metastatic potential by gamma-interferon.

Preincubation of murine colon 26 colon adenocarcinoma cells with gamma-interferon (IFN-gamma), but not alpha-interferon, produced a significant increase in experimental pulmonary metastases in syngeneic BALB/c and T-cell-deficient BALB/c nude mice. The enhancement was seen after as little as 1 h of exposure to 1 unit/ml of IFN-gamma and persisted for at least 72 h following removal of the cytokine. IFN-gamma exerted its effects by increasing the pulmonary retention of cells during the first 6 h following tumor cell injection. During this period all cells visualized in the lung were trapped in pulmonary capillaries. The enhancement was not due to modulations in class I major histocompatibility complex surface antigen expression; nor was it due to alterations in cell size, adhesion to components of the extracellular matrix in vitro, heterotypic or homotypic adhesion, sensitivity to lysis by activated peritoneal macrophages, osmotic fragility, enhancement of surface class II major histocompatibility complex antigen expression, or enhancement of intercellular adhesion molecule-1 (ICAM-1). Colon 26 was completely resistant to natural killer cell-mediated lysis in vitro, and IFN-gamma did not modulate the ability of colon 26 to form conjugates with isolated splenocytes. In vivo elimination of anti-asialo GM1 + cells increased pulmonary metastasis, and in such mice, there was no longer a difference in metastatic potential between control and IFN-gamma-treated cells. We conclude that low doses of IFN-gamma generated at the site of the tumor by host-infiltrating cells or during cytokine therapy could enhance the survival of tumor cells in the circulation and enhance their metastatic potential.

Intraperitoneal xenografts of human epithelial ovarian cancer in nude mice.

Using continuous human ovarian cancer cell lines, i.p. xenografts were successfully established in nude mice from four of four attempts. When primary tumor material was used, xenografts grew in 8 of 10 attempts. From these eight, three passageable xenograft cell lines have been established. To our knowledge, this is the first report published of such xenografts. I.p. xenografts closely mimic the clinical behavior of human ovarian cancer, and those developed from primary tumor material maintain close morphological similarity to the parent primary tumor. When expression of placental alkaline phosphatase and the tumor associated antigens defined by the monoclonal antibodies HMFG1, HMFG2, AUA1, and F36/22 by these models was determined, those i.p. xenografts derived from primary tumor material exactly matched the original tumor, while none of the xenografts derived from the cell lines expressed these antigens. These models will be useful for investigating the biology and treatment of ovarian cancer.

Enhancement by gamma-interferon of in vivo tumor radiolocalization by a monoclonal antibody against HLA-DR antigen.

Athymic nu/nu (nude) mice bearing s.c. human breast tumors were treated systemically with recombinant human gamma-interferon. These tumors were phenotypically negative for HLA-DR prior to therapy, but after 4 days of treatment, 80% of the cells expressed this antigen in vivo as assessed by immunoperoxidase (F. R. Balkwill et al., Eur. J. Cancer Clin. Oncol., in press, 1986). A radioiodine-labeled murine monoclonal antibody (TAL-1B5) against HLA-DR specifically localized to the tumors in recombinant human gamma-interferon-treated but not in control mice. An isotype-identical murine monoclonal antibody that did not react with control or recombinant human gamma-interferon-treated tumors did not show any specific localization. These results demonstrate that specific localization to tumors of radio-labeled monoclonal antibodies to HLA-DR can be facilitated by systemic therapy with gamma-interferon.

Therapeutic potential of tumor necrosis factor-alpha and gamma-interferon in experimental human ovarian cancer.

We have studied the activity of recombinant human gamma-interferon and recombinant human tumor necrosis factor alpha against four human ovarian cancer i.p. xenografts OS, LA, HN, and DO derived from primary tumor material. In the OS xenograft all control mice died by 42 days and therapy starting 7 days after tumor cell injection with 5 X 10(4) units recombinant human gamma-interferon or 1 microgram recombinant human tumor necrosis factor alpha alone had no significant effect on cumulative survival in three separate experiments. However, a combination of the two agents resulted in 85% cumulative survival at 150 days. This combination therapy also significantly increased survival of mice treated as late as 21 days after tumor cell injection. In the LA xenograft (where control mice were all dead by 23 days) therapy with either agent alone, or a combination, more than doubled survival time of mice. In the HN xenograft all control mice were dead at 22 days whereas either therapy alone or in combination gave +85% cumulative survival at 100 days. In a fourth xenograft, DO, survival of mice in the combination therapy group was significantly increased. Thus these two biological therapies, alone or in combination, show significant activity against human ovarian cancer cells.

A synthetic matrix metalloproteinase inhibitor decreases tumor burden and prolongs survival of mice bearing human ovarian carcinoma xenografts.

We have examined the effect of a synthetic low-molecular-weight matrix metalloproteinase inhibitor, [4-(N-hydroxyamino)-2R-isobutyl-3S- (thiopen-2-ylthiomethyl)-succinyl]-L-phenylalanine-N-meth yla mide (BB-94), on human ovarian carcinoma xenografts growing in nude mice. The xenografts grew as thick intraperitoneal mucinous ascites containing free-floating tumor cell clumps. The ascites increased in volume, causing death approximately 3 weeks after introduction. Treatment with BB-94 caused resolution of ascitic disease. Tumor burden was dramatically reduced, and survival increased 5-6-fold. The increase in survival was dose dependent. The effects observed with BB-94 appeared to be due to its matrix metalloproteinase inhibiting effects, inasmuch as its inactive diastereoisomer had no effect on tumor biology. Following treatment with BB-94, free-floating clumps of tumor cells became surrounded by a capsule of host cells. These clumps of tumor cells typically formed one small (approximately 8 mm) avascular tumor of bright white appearance loosely attached to fat in the peritoneum. Tumor cells within these capsules often appeared to be necrotic. Gel substrate analysis demonstrated that activated Mr 92,000 type IV collagenase was present in the xenografts. We propose that inhibition of this enzyme causes the transition of ascites to solid tumors, concomitantly slowing tumor cell growth and allowing the development of tumor stroma.

Antitumor activity of gamma-interferon in ascitic and solid tumor models of human ovarian cancer.

We have investigated the action of recombinant human gamma-interferon (rHuIFN-gamma) against human ovarian cancer xenografts growing as ascites or as bulky solid i.p. tumors in nude mice. Both forms of the disease responded to i.p. rHuIFN-gamma with significant increases in mouse survival time, and in 2 of 3 ascitic models the mice were cured of peritoneal disease. The activity of rHuIFN-gamma was dose and schedule dependent, and xenografts derived from 3 different patients showed a heterogeneity of response. Peak i.p. levels of rHuIFN-gamma in nude mice bearing multiple i.p. solid tumors were similar to those found in ovarian cancer patients receiving i.p. rHuIFN-gamma, but clearance was more rapid in the mice. Rat gamma-interferon had no antitumor activity at the same doses and schedules although it had some biological activity in the nude mice. Histological examination of treated tumors revealed increased necrosis and loss of cellular organization with large areas of hypocellular epithelial mucin. These changes were preceded by a fall in tumor tryptophan and a rise in tumor kynurenine. We conclude that rHuIFN-gamma has a direct dose related antitumor effect on ovarian cancer xenografts that is preceded by increased metabolism of tryptophan.

Epithelial cancer cell migration: a role for chemokine receptors?

We investigated the possibility that chemokine gradients influence migration of human ovarian epithelial tumor cells. Of 14 chemokine receptors investigated, only CXCR4 was expressed on ovarian cancer cells. CXCR4 mRNA localized to a subpopulation of tumor cells in ovarian cancer biopsies. Ovarian cancer cell lines and cells freshly isolated from ascites expressed CXCR4 protein. The CXCR4 ligand, CXCL12, was found in ascites from 63 patients. CXCL12 elicited intracellular calcium flux and directed migration and changes in integrin expression in ovarian cancer cells. CXCR4 may influence cell migration in the peritoneum, a major route for ovarian cancer spread, and could be a therapeutic target.

Human tumor xenografts treated with recombinant human tumor necrosis factor alone or in combination with interferons.

We have studied the activity of recombinant human tumor necrosis factor (rHuTNF) on six different human tumor xenografts derived from primary breast and bowel tumors and maintained by passage in nude mice. When 5 micrograms rHuTNF was given daily intratumorally to mice with established (approximately, 0.5 cm) tumors, total tumor regression was observed by 3-4 weeks in three of six xenograft lines. In a further two lines tumor stasis or significant slowing of growth was seen. This antitumor action was not accompanied by any consistent macroscopic change in the tumor such as necrosis, but histological examination revealed tumor cell degeneration and a large peritumoral infiltration of host inflammatory cells after 4-7 days therapy. In contrast to these data, little effect was seen when the same dose of rHuTNF was administered i.p. to nude mice bearing these tumors. In only two of six lines was any significant slowing of tumor growth seen. A 5-fold increase in the i.p. dose resulted in improved activity on only one of two xenograft lines tested. Efficacy of the i.p. rHuTNF dose could, however, be enhanced by simultaneous administration of human interferon, alpha or gamma. No obvious signs of toxicity were observed at all rHuTNF doses administered and weights of control and treated mice at the end of the experiments were comparable.