The role of cytokines in the epithelial cancer microenvironment

A phase II study of etanercept (Enbrel), a tumor necrosis factor alpha inhibitor in patients with metastatic breast cancer

PURPOSE

Tumor necrosis factor (TNF) alpha is a key player in the tumor microenvironment and is involved in the pathogenesis of breast cancer. Etanercept is a recombinant human soluble p75 TNF receptor that binds to TNF-alpha and renders it biologically unavailable. In the current study, we sought to determine the toxicity, biological activity, and therapeutic efficacy of Etanercept in metastatic breast cancer.

EXPERIMENTAL DESIGN

We initiated a Phase II, nonrandomized, open-labeled study in patients with progressive metastatic breast cancer refractory to conventional therapy (Phase I toxicity data were available in patients with rheumatoid arthritis). Etanercept was administered subcutaneously at a dose of 25 mg twice weekly until disease progression.

RESULTS

Sixteen patients were recruited [median age 53 years (range, 34 to 74)]. A total of 141.6 weeks of therapy was administered (median of 8.1 weeks). Seven patients received > or =12 weeks of therapy. The most common side effects were injection site reactions (6), fatigue (5), loss of appetite (2), nausea (1), headache (1), and dizziness (1). Brief period of disease stabilization was seen in 1 patient lasting for 16.4 weeks. Immunoreactive TNF-alpha was elevated within 24 hours of therapy and persisted until the end of treatment (days 7, 28, 56, and 84). Phytohemagglutinin stimulates the production of interleukin-6 and CCL2 in peripheral blood cells, and the ability of Etanercept to modulate this response was assessed in a cytokine release assay. A consistent decrease in interleukin-6 and CCL2 level was seen compared with pretreatment values in serial blood samples (days 1, 7, 28, 56, and 84).

CONCLUSIONS

Our study shows the safety and biological activity of Etanercept in breast cancer and provides data to assess pharmacodynamic endpoints of different schedules of Etanercept and combinations with chemotherapy or other biological therapies.

Inhibition of NF-kappaB in cancer cells converts inflammation- induced tumor growth mediated by TNFalpha to TRAIL-mediated tumor regression

We used an experimental murine cancer metastasis model in which a colon adenocarcinoma cell line generates lung metastases, whose growth is stimulated in response to injection of bacterial lipopolysaccharide (LPS), to investigate the role of NF-kappaB in inflammation-induced tumor growth. We found that LPS-induced metastatic growth response in this model depends on both TNFalpha production by host hematopoietic cells and NF-kappaB activation in tumor cells. Inhibition of NF-kappaB in both colon and mammary carcinoma cells converts the LPS-induced growth response to LPS-induced tumor regression. The latter response is TNFalpha-independent, but depends on another member of the TNF superfamily, TRAIL, whose receptor is induced in NF-kappaB-deficient cancer cells.

Advantages of assaying telomerase activity in ascites for diagnosis of digestive tract malignancies

AIM: To evaluate the diagnostic value of assaying telomerase activity in ascites cells for the differential diagnosis of malignant and non-malignant ascites.

METHODS: Ascites from 40 patients with hepatocellular carcinoma (HCC), 31 with non-HCC gastrointestinal carcinoma (CA), and 24 with liver cirrhosis (LC) were analyzed for telomerase activity. The telomerase activities in cell pellets from ascites were measured according to the Telomeric Repeat Amplification Protocol (TRAP) and quantified with a densitometer.

RESULTS: Positive telomerase activity was detected in 16 of 31 (52%) CA patients, 10 of 40 (25%) HCC patients, and 1 of 24 (4%) LC patients (P < 0.001). The telomerase activity was higher in the ascites of CA patients than in the ascites of HCC or LC patients (CA: 22.9 ± 5.8, HCC: 6.7 ± 2.5, LC: 1.3 ± 1.3, P = 0.001). Cytology was positive in 18 CA patients (58%) and 1 HCC patient (2.5%), respectively. The positive telomerase activity was not related to patients’ age, gender, and ascitic protein concentration, but to white blood count (r = 0.31, P = 0.002), neutrophil count (r = 0.29, P = 0.005), and the C-reactive protein level (r = 0.29, P = 0.018). When the results of both cytological examination and telomerase assay were considered together, the sensitivity increased to 77% for CA patients, 25% for HCC patients, and 48% for all 71 gastrointestinal cancer patients.

CONCLUSION: Combining cytological examination of ascites with telomerase activity assay significantly improves the differential diagnosis between malignant and non-malignant ascites.

NF-kappaB functions as a tumour promoter in inflammation-associated cancer

The causes of sporadic human cancer are seldom recognized, but it is estimated that carcinogen exposure and chronic inflammation are two important underlying conditions for tumour development, the latter accounting for approximately 20% of human cancer. Whereas the causal relationship between carcinogen exposure and cancer has been intensely investigated, the molecular and cellular mechanisms linking chronic inflammation to tumorigenesis remain largely unresolved. We proposed that activation of the nuclear factor kappaB (NF-kappaB), a hallmark of inflammatory responses that is frequently detected in tumours, may constitute a missing link between inflammation and cancer. To test this hypothesis, we studied the Mdr2-knockout mouse strain, which spontaneously develops cholestatic hepatitis followed by hepatocellular carcinoma, a prototype of inflammation-associated cancer. We monitored hepatitis and cancer progression in Mdr2-knockout mice, and here we show that the inflammatory process triggers hepatocyte NF-kappaB through upregulation of tumour-necrosis factor-alpha (TNFalpha) in adjacent endothelial and inflammatory cells. Switching off NF-kappaB in mice from birth to seven months of age, using a hepatocyte-specific inducible IkappaB-super-repressor transgene, had no effect on the course of hepatitis, nor did it affect early phases of hepatocyte transformation. By contrast, suppressing NF-kappaB inhibition through anti-TNFalpha treatment or induction of IkappaB-super-repressor in later stages of tumour development resulted in apoptosis of transformed hepatocytes and failure to progress to hepatocellular carcinoma. Our studies thus indicate that NF-kappaB is essential for promoting inflammation-associated cancer, and is therefore a potential target for cancer prevention in chronic inflammatory diseases.

A Sense of Danger from Radiation1

Tissue damage caused by exposure to pathogens, chemicals and physical agents such as ionizing radiation triggers production of generic "danger" signals that mobilize the innate and acquired immune system to deal with the intrusion and effect tissue repair with the goal of maintaining the integrity of the tissue and the body. Ionizing radiation appears to do the same, but less is known about the role of "danger" signals in tissue responses to this agent. This review deals with the nature of putative "danger" signals that may be generated by exposure to ionizing radiation and their significance. There are a number of potential consequences of "danger" signaling in response to radiation exposure. "Danger" signals could mediate the pathogenesis of, or recovery from, radiation damage. They could alter intrinsic cellular radiosensitivity or initiate radioadaptive responses to subsequent exposure. They may spread outside the locally damaged site and mediate bystander or "out-of-field" radiation effects. Finally, an important aspect of classical "danger" signals is that they link initial nonspecific immune responses in a pathological site to the development of specific adaptive immunity. Interestingly, in the case of radiation, there is little evidence that "danger" signals efficiently translate radiation-induced tumor cell death into the generation of tumor-specific immunity or normal tissue damage into autoimmunity. The suggestion is that radiation-induced "danger" signals may be inadequate in this respect or that radiation interferes with the generation of specific immunity. There are many issues that need to be resolved regarding "danger" signaling after exposure to ionizing radiation. Evidence of their importance is, in some areas, scant, but the issues are worthy of consideration, if for no other reason than that manipulation of these pathways has the potential to improve the therapeutic benefit of radiation therapy. This article focuses on how normal tissues and tumors sense and respond to danger from ionizing radiation, on the nature of the signals that are sent, and on the impact on the eventual consequences of exposure.

The pattern of cytokine gene expression in human colorectal carcinoma

Systemic and local cytokine environment may modulate the immunogenicity of colorectal cancer cells, and affect anti-tumor immune functions of tumor-infiltrating lymphocytes. We therefore investigated cytokine mRNA expression patterns in tumors and peripheral blood mononuclear cells (PBMC) from patients with colorectal adenocarcinoma. IL-2, IFN-gamma, tumor necrosis factor-alpha (TNF-alpha), IL-4, IL-6, IL-8, IL-10 and IL-1 beta mRNAs in single cell suspension of freshly isolated colorectal cancer tissue were studied by RT-PCR. Frequencies of cytokine gene expression were compared to those in normal colonic mucosa from tumor patients. The frequencies of IL-2, IFN-gamma, IL-4 and IL-10 gene expression were also determined in peripheral blood mononuclear cells from patients with colorectal adenocarcinoma and compared to those of healthy individuals. Tumor samples were more frequently positive for IFN-gamma, IL-2, TNF-alpha and IL-10 gene expression than normal mucosa (p=0.0001, p=0.0118, p=0.001 and p<0.0001, respectively). Frequencies of IL-2 and TNF-alpha gene expressions were significantly higher in tumors with a diameter <5 cm, than in those with a diameter >5 cm. The genes for IL-6, IL-1 beta and IL-8 were commonly expressed in both tumor tissue and normal colonic mucosa. IFN-gamma transcripts were detected in more PBMC samples from patients with colorectal cancer than those from normal controls (p=0.0449). Thus, colorectal cancer tissue is characterized by a specific pattern of cytokine gene expression. It is likely that multiple interactions between pro- and anti-inflammatory cytokines regulate tumor growth and the functional activity of tumor-infiltrating lymphocytes.

Identification of an autoregulatory feedback pathway involving interleukin-1alpha in induction of constitutive NF-kappaB activation in pancreatic cancer cells

We previously reported that NF-kappaB is constitutively activated in most human pancreatic cancer tissues and cell lines but not in normal pancreatic tissues and immortalized pancreatic ductal epithelial cells. IkappaBalphaM-mediated inhibition of constitutive NF-kappaB activity in human pancreatic cancer cells suppressed tumorigenesis and liver metastasis in an orthotopic nude mouse model, suggesting that constitutive NF-kappaB activation plays an important role in pancreatic tumor progression and metastasis. However, the underlying mechanism by which NF-kappaB is activated in pancreatic cancer remains to be elucidated. In this study, we found that an autocrine mechanism accounts for the constitutive activation of NF-kappaB in metastatic human pancreatic cancer cell lines. Further investigation showed that interleukin-1alpha was the primary cytokine secreted by these cells that activates NF-kappaB. Neutralization of interleukin-1alpha activity suppressed the constitutive activation of NF-kappaB and the expression of its downstream target gene, urokinase-type plasminogen activator, in metastatic pancreatic cancer cell lines. Our results demonstrate that regulation of interleukin-1alpha expression is primarily dependent on AP-1 activity, which is in part induced by signaling pathways that are epidermal growth factor receptor-dependent and -independent. In conclusion, our findings suggest a possible mechanism for the constitutive activation of NF-kappaB in metastatic human pancreatic cancer cells and a possible missing mechanistic link between inflammation and cancer.

p53- and Mdm2-independent repression of NF-kappa B transactivation by the ARF tumor suppressor

One mechanism by which a cell affords protection from the transforming effects of oncogenes is via the action of the tumor suppressor, ARF, which activates p53 by inactivating Mdm2. Many oncogenes have also been shown to activate the transcription factor NF-kappa B, which can contribute toward the malignant phenotype in many ways, including an ability to antagonize p53. Here we find that ARF inhibits NF-kappa B function and its antiapoptotic activity independent of Mdm2 and p53. ARF represses the transcriptional activation domain of the NF-kappa B family member RelA by inducing its association with the histone deacetylase, HDAC1. Further, we show that the response of NF-kappa B to the oncogene Bcr-Abl is determined by the ARF status of the cell. These results reveal an important function of ARF that can regulate the NF-kappa B response to oncogene activation.

Inhibitors that target protein kinases for the treatment of ovarian carcinoma

OBJECTIVE

Ovarian cancer is the leading cause of death from gynecologic malignancies in the United States. In an attempt to develop drugs that suppress ovarian cancer cells, we examined the effect of selective inhibitors of protein tyrosine kinases-tyrphostins, which are likely to play a role in ovarian cancer cells.

STUDY DESIGN

We examined the cellular and biochemical effects of tyrphostins AG1478, PP2, AGL2592, and AG490 from four different families on the ovarian carcinoma cell line OV1063.

RESULTS

We found that the AG1478, PP2, AGL2592, and AG490 tyrphostins suppressed cell proliferation and altered cell cycle distribution of the OV1063 cells in a dose- and time-dependent manner. Immunoblotting analysis indicated that AG1478 effectively inhibited epidermal growth factor receptor autophosphorylation, that AG490 decreased the level of Jak2 and phosphorylated Stat3, and that PP2 decreased the level of pp60Src protein. AGL2592 decreased the level of constitutive activated epidermal growth factor receptor and pStat3, but its molecular targets have not been identified completely.

CONCLUSION

The growth-arresting properties of these tyrphostins identify them as possible candidates for signal transduction therapy.

Gene Therapy Applications to Cancer Treatment

Over the past ten years significant advances have been made in the fields of gene therapy and tumour immunology, such that there now exists a considerable body of evidence validating the proof in the principle of gene therapy based cancer vaccines. While clinical benefit has so far been marginal, data from preclinical and early clinical trials of gene therapy combined with standard therapies are strongly suggestive of additional benefit. Many reasons have been proposed to explain the paucity of clinical responses to single agent vaccination strategies including the poor antigenicity of tumour cells and the development of tolerance through down-regulation of MHC, costimulatory, signal transduction, and other molecules essential for the generation of strong immune responses. In addition, there is now evidence from animal models that the growing tumour may actively inhibit the host immune response. Removal of the primary tumour prior to T cell transfer from the spleen of cancer bearing animals, led to effective tumour cell line specific immunity in the recipient mouse suggesting that there is an ongoing tumour-host interaction. This model also illustrates the potential difficulties of clinical vaccine trials in patients with advanced stage disease.

MMP9 potentiates pulmonary metastasis formation

Tumor cell dissemination to distant organ sites is a complex process involving multiple cell types, soluble growth factors, adhesion receptors, and tissue remodeling. A new study in this issue of Cancer Cell shows that MMP9-expressing tumor-associated macrophages play a key role in prepping premetastatic sites for eventual malignant cell growth in a manner dependent upon vascular endothelial growth factor receptor-1 (VEGFR-1).