Effect of IL-1 on experimental bone/bone-marrow metastases

Mechanisms Supporting the Use of Beta-Blockers for the Management of Breast Cancer Bone Metastasis

Simple Summary

Bone represents the most common site of metastasis for breast cancer and the establishment and growth of metastatic cancer cells within the skeleton significantly reduces the quality of life of patients and their survival. The interplay between sympathetic nerves and bone cells, and its influence on the process of breast cancer bone metastasis is increasingly being recognized. Several mechanisms, all dependent on β-adrenergic receptor signaling in stromal bone cells, were shown to promote the establishment of disseminated cancer cells into the skeleton. This review provides a summary of these mechanisms in support of the therapeutic potential of β-blockers for the early management of breast cancer metastasis.

Abstract

The skeleton is heavily innervated by sympathetic nerves and represents a common site for breast cancer metastases, the latter being the main cause of morbidity and mortality in breast cancer patients. Progression and recurrence of breast cancer, as well as decreased overall survival in breast cancer patients, are associated with chronic stress, a condition known to stimulate sympathetic nerve outflow. Preclinical studies have demonstrated that sympathetic stimulation of β-adrenergic receptors in osteoblasts increases bone vascular density, adhesion of metastatic cancer cells to blood vessels, and their colonization of the bone microenvironment, whereas β-blockade prevented these events in mice with high endogenous sympathetic activity. These findings in preclinical models, along with clinical data from breast cancer patients receiving β-blockers, support the pathophysiological role of excess sympathetic nervous system activity in the formation of bone metastases, and the potential of commonly used, safe, and low-cost β-blockers as adjuvant therapy to improve the prognosis of bone metastases.

Skewed Signaling through the Receptor for Advanced Glycation End-Products Alters the Proinflammatory Profile of Tumor-Associated Macrophages

Tumors are complex tissues composed of variable amounts of both non-cellular components (matrix proteins) and a multitude of stromal cell types, which are under an active cross-talk with tumor cells. Tumor-associated macrophages (TAMs) are the major leukocyte population among the tumor-infiltrating immune cells. Once they are infiltrated into tumor stroma they undergo a polarized activation, where the M1 and M2 phenotypes represent the two extreme of the polarization heterogeneity spectrum. It is known that TAMs acquire a specific phenotype (M2), oriented toward tumor growth, angiogenesis and immune-suppression. A growing body of evidences supports the presence of tuning mechanisms in order to skew or restraint the inflammatory response of TAMs and thus forces them to function as active tumor-promoting immune cells. The receptor of advanced glycation end-products (RAGE) is a member of the immunoglobulin protein family of cell surface molecules, being activated by several danger signals and thus signaling to promote the production of many pro-inflammatory molecules. Interestingly, this receptor is paradoxically expressed in both M1 and M2 macrophages phenotypes. This review addresses how RAGE signaling has been drifted away in M2 macrophages, and thus taking advantage of the abundance of RAGE ligands at tumor microenvironment, particularly HMGB1, to reinforce the supportive M2 macrophages strategy to support tumor growth.

β2ARs stimulation in osteoblasts promotes breast cancer cell adhesion to bone marrow endothelial cells in an IL-1β and selectin-dependent manner

Progression and recurrence of breast cancer, as well as reduced survival of patients with breast cancer, are associated with chronic stress, a condition known to impact the hypothalamic-pituitary axis and the autonomic nervous system. Preclinical and clinical evidence support the involvement of the sympathetic nervous system in the control of bone remodeling and in pathologies of the skeleton, including bone metastasis. In experimental mouse models of skeletal metastasis, administration of the βAR agonist isoproterenol (ISO), used as a surrogate of norepinephrine, the main neurotransmitter of sympathetic neurons, was shown to favor bone colonization of metastatic breast cancer cells via an increase bone marrow vascularity. However, successful extravasation of cancer cells into a distant organ is known to be favored by an activated endothelium, itself stimulated by inflammatory signals. Based on the known association between high sympathetic outflow, the expression of inflammatory cytokines and bone metastasis, we thus asked whether βAR stimulation in osteoblasts may alter the vascular endothelium to favor cancer cell engraftment within the skeleton. To address this question, we used conditioned medium (CM) from PBS or ISO-treated bone marrow stromal cells (BMSCs) in adhesion assays with bone marrow endothelial cells (BMECs) or the endothelial cell line C166. We found that ISO treatment in differentiated BMSCs led to a robust induction of the pro-inflammatory cytokines interleukin-1 beta (IL-1β) and interleukin-6 (IL-6). The CM from ISO-treated BMSCs increased the expression of E- and P-selectin in BMECs and the adhesion of human MDA-MB-231 breast cancer cells to these cells in short-term static and dynamic adhesion assays, and a blocking antibody against IL-1β, but not IL-6, reduced this effect. Direct IL-1β treatment of BMECs had a similar effect, whereas the impact of IL-6 treatment on the expression of adhesion molecules by BMECs and on the adhesion of cancer cells to BMECs was negligible. Collectively, these in vitro results suggest that in the context of the multicellular and dynamic bone marrow environment, sympathetic activation and subsequent βAR stimulation in osteoblasts may profoundly remodel the density but also the activation status of bone marrow vessels to favor the skeletal engraftment of circulating breast cancer cells.

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β2AR activation in osteoblasts increases the expression of pro-inflammatory cytokines IL-1β and IL-6.

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IL-1β promotes the adhesion of breast cancer cells to endothelium via an endothelial increase in E- and P-selectin expression.

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IL-1β blockade and selectin inhibition inhibits breast cancer cell adhesion to endothelial cells.

Report of a phase I evaluation of dose and schedule of interleukin-1 alpha and cyclophosphamide in patients with advanced tumors: An Eastern Cooperative Oncology Group study (PX990) and review of IL-1-based studies of hematopoietic reconstitution

Interleukin-1 (IL-1) is a cytokine critical to inflammation, immunological activation, response to infection, and bone marrow hematopoiesis. Cyclophosphamide downmodulates immune suppressor cells and is cytotoxic to a variety of tumors. A phase I trial of IL-1 and cyclophosphamide was conducted by the Eastern Cooperative Oncology Group. This study evaluated 3 dose levels and 3 schedules in patients with solid tumors. The goal was to evaluate the hematopoietic supportive care effect and possible antitumor effect. Toxicity was fever, chills, hypotension, nausea/emesis, hepatic, and neutropenia. Toxicity increased with dose increases of interleukin-1. Treatment at all dose levels resulted in significant increases in total white blood cell (WBC) counts above baseline. Nadir WBC and nadir absolute neutrophil counts were not significantly different by dose level of IL-1 or schedule of IL-1. Toxicity due to IL-1 at higher doses prohibited further evaluation of this agent for hematopoietic support, particularly in view of the activity and tolerability of more lineage-specific hematopoietic cytokines. Therapeutic interventions in the role of IL-1 in inflammatory conditions and cancer may be further informed by our definition of its clinical and biological effects in this evaluation of dose and schedule.

Bone recurrence after curative resection of gastric cancer

BACKGROUND

Standard follow up for bone recurrence has not yet been established for gastric cancer after surgical resection. The aim of this study was to investigate the incidence of and related risk factors for bone recurrence after surgical resection of gastric cancer.

METHODS

A cohort of 3035 gastric cancer patients after curative resection was reviewed. We analyzed the patients who had bone scintigraphy before the surgery as well as during the follow-up period. The incidence of and the risk factors for bone recurrence after surgical resection of gastric cancer were investigated.

RESULTS

In a total of 1683 patients analyzed, bone recurrence was detected in 30 patients (1.8%). The incidence of bone recurrence was significantly higher in advanced gastric cancers than in early lesions (3.5 vs. 0.4%, p < 0.01). The most common recurrence site was the spine, followed by pelvic bone and rib. Most patients had multiple bone metastases. The median time for recurrence was 28 months (range 4-111) from the surgery. In univariate analysis, the recurrence rate was higher in the tumors with large size, undifferentiated pathology, location in the body, and advanced stage. In multivariate analysis, lymph node metastasis (N2/N3 vs. N0/N0I) was the most predictable risk factor for bone recurrence [hazard ratio [HR] 1.44 (95% confidence interval [CI] 1.217-1.694)] and depth of invasion (T2-4 vs. T1) was also independently associated with bone recurrence.

CONCLUSIONS

The incidence of bone recurrence was low after curative surgery in patients with gastric cancer. Intensive follow up with bone scintigraphy seems to be unnecessary in these patients.

Targeting of the innate immunity/inflammation as complementary anti-tumor therapies

Different types of cancer take advantage of inflammatory components to improve their life-span in the organs. A sustenance of growth factors and cytokines (e.g. interleukin (IL)-1, tumor necrosis factor, IL-6, vascular endothelial growth factor) supports malignant cell progression and contributes to suppress the body immune defense. Strategies to modulate the host micro-environment offer new approaches for anti-cancer therapies. For these reasons new molecules with anti-tumor and anti-inflammatory features (e.g. trabectedin) are looked at with new eyes in the light of the crucial link between inflammation and cancer.

Vascular endothelial growth factor regulates melanoma cell adhesion and growth in the bone marrow microenvironment via tumor cyclooxygenase-2

BACKGROUND

Human melanoma frequently colonizes bone marrow (BM) since its earliest stage of systemic dissemination, prior to clinical metastasis occurrence. However, how melanoma cell adhesion and proliferation mechanisms are regulated within bone marrow stromal cell (BMSC) microenvironment remain unclear. Consistent with the prometastatic role of inflammatory and angiogenic factors, several studies have reported elevated levels of cyclooxygenase-2 (COX-2) in melanoma although its pathogenic role in bone marrow melanoma metastasis is unknown.

METHODS

Herein we analyzed the effect of cyclooxygenase-2 (COX-2) inhibitor celecoxib in a model of generalized BM dissemination of left cardiac ventricle-injected B16 melanoma (B16M) cells into healthy and bacterial endotoxin lipopolysaccharide (LPS)-pretreated mice to induce inflammation. In addition, B16M and human A375 melanoma (A375M) cells were exposed to conditioned media from basal and LPS-treated primary cultured murine and human BMSCs, and the contribution of COX-2 to the adhesion and proliferation of melanoma cells was also studied.

RESULTS

Mice given one single intravenous injection of LPS 6 hour prior to cancer cells significantly increased B16M metastasis in BM compared to untreated mice; however, administration of oral celecoxib reduced BM metastasis incidence and volume in healthy mice, and almost completely abrogated LPS-dependent melanoma metastases. In vitro, untreated and LPS-treated murine and human BMSC-conditioned medium (CM) increased VCAM-1-dependent BMSC adherence and proliferation of B16M and A375M cells, respectively, as compared to basal medium-treated melanoma cells. Addition of celecoxib to both B16M and A375M cells abolished adhesion and proliferation increments induced by BMSC-CM. TNFα and VEGF secretion increased in the supernatant of LPS-treated BMSCs; however, anti-VEGF neutralizing antibodies added to B16M and A375M cells prior to LPS-treated BMSC-CM resulted in a complete abrogation of both adhesion- and proliferation-stimulating effect of BMSC on melanoma cells. Conversely, recombinant VEGF increased adherence to BMSC and proliferation of both B16M and A375M cells, compared to basal medium-treated cells, while addition of celecoxib neutralized VEGF effects on melanoma. Recombinant TNFα induced B16M production of VEGF via COX-2-dependent mechanism. Moreover, exogenous PGE2 also increased B16M cell adhesion to immobilized recombinant VCAM-1.

CONCLUSIONS

We demonstrate the contribution of VEGF-induced tumor COX-2 to the regulation of adhesion- and proliferation-stimulating effects of TNFα, from endotoxin-activated bone marrow stromal cells, on VLA-4-expressing melanoma cells. These data suggest COX-2 neutralization as a potential anti-metastatic therapy in melanoma patients at high risk of systemic and bone dissemination due to intercurrent infectious and inflammatory diseases.

Loss of osteoclasts contributes to development of osteosarcoma pulmonary metastases

We conducted a transcriptomic screen of osteosarcoma (OS) biopsies and found that expression of osteoclast-specific tartrate-resistant acid phosphatase 5 (ACP5/TRAP) is significantly downregulated in OS compared with nonmalignant bone (P < 0.0001). Moreover, lesions from OS patients with pulmonary metastases had 2-fold less ACP5/TRAP expression (P < 0.018) than lesions from patients without metastases. In addition, we found a direct correlation (P = 0.0166) between ACP5/TRAP expression and time to metastasis. Therefore, we examined whether metastasis-competent (MC) OS cells could induce loss of ACP5(+) osteoclasts and contribute to metastasis. We found that MC OS cell lines can inhibit osteoclastogenesis in vitro and in vivo. In addition, osteoclasts can inhibit the migration of MC OS cells in vitro. Finally, ablation of osteoclasts with zoledronic acid increases the number of metastatic lung lesions in an orthotopic OS model, whereas fulvestrant treatment increases osteoclast numbers and reduces metastatic lesions. These data indicate that the metastatic potential of OS is determined early in tumor development and that loss of osteoclasts in the primary lesion enhances OS metastasis.

Why not treat human cancer with interleukin-1 blockade?

The clinical successes of targeting angiogenesis provide a basis for trials of interleukin-1 (IL-1) blockade and particularly anti-IL-1beta as an add-on therapy in human metastatic disease. In animal studies for over 20 years, IL-1 has been demonstrated to increase adherence of tumor cells to the endothelium in vitro, and administration of IL-1 to mice increases the number of metastatic colonies and tumor growth. Importantly, reducing endogenous IL-1 activity, particularly IL-1beta, with the naturally occurring IL-1 receptor antagonist (IL-1Ra) reduces both metastasis as well as tumor burden. Inhibition of IL-1 activity prevents in vivo blood vessel formation induced by products released from hypoxic macrophages or vascular endothelial cell growth factor itself. Mice deficient in IL-1beta do not form blood vessels in matrigels embedded with vascular endothelial cell growth factor or containing products of macrophages. Recombinant IL-1Ra (anakinra) has been administered to over 1,000 patients with septic shock resulting in a consistent reduction in all-cause 28-day mortality. Approved for treatment of rheumatoid arthritis, anakinra has a remarkable safety record. Anakinra resulted in decreased blood vessels in the pannus of affected joints in patients with rheumatoid arthritis. Neutralizing monoclonal antibodies to IL-1beta and a soluble receptor to IL-1 are approved for treating chronic inflammatory diseases. Given the availability of three therapeutic agents for limiting IL-1 activity, the safety of blocking IL-1, and the clear benefit of blocking IL-1 activity in animal models of metastasis and angiogenesis, clinical trials of IL-1 blockade should be initiated, particularly as an add-on therapy of patients receiving antiangiogenesis-based therapies.

Inhibition of bone resorption and growth of breast cancer in the bone microenvironment

Breast cancer frequently metastasizes to bone, where tumor cells induce osteoclasts to locally destroy bone. During bone resorption, growth factors are locally released that may support bone metastatic growth. Differently from most other tissues, drugs that can limit local turnover, such as bisphosphonates and osteoprotegerin (OPG), are available for bone. We examined the hypothesis that inhibition of bone resorption by two different mechanisms may also affect the growth of cancer cells in bone. For this, we tested the effects of high doses of OPG and zoledronic acid (ZOL) on progression of MDA-231-B/Luc+ breast cancer cells in the bone microenvironment using whole body bioluminescent reporter imaging (BLI). Both treatments significantly inhibited the development of radiographically detectable osteolytic lesions. Histologic examination corroborated the radiographic findings, showing that both treatments preserved the integrity of bone trabeculae and prevented bone destruction (significantly higher trabecular bone volumes vs. vehicle). However, whereas practically no TRAcP-positive osteoclasts were observed in tibiae preparations of animals treated with Fc-OPG, TRAcP-positive osteoclasts were still present in the animals treated with ZOL. Intra-bone tumor burden was reduced with ZOL and Fc-OPG treatment. Although there appeared to be a trend for less overall total tumor burden upon treatment with both compounds, this was not significant as assessed by BLI and histomorphometric analysis due to the extramedullary growth of cancer cells which was not affected by these treatments. Collectively, anti-resorptive agents with different mechanisms of action - ZOL and OPG - significantly reduced cancer-induced osteolysis and intra-osseous tumor burden, but failed to restrain local tumor growth. However, interference with the bone micro-environmental growth support could still be of therapeutic relevance when given to patients early in the course of bone metastatic disease.

Osteotropic cancers: from primary tumor to bone

It has long been recognized that primary cancers spread to distant organs with characteristic preference. Bone metastases occur in approximately 70% of patients with advanced breast and prostate cancer, causing severe morbidity and hospitalization. In the last decade, we have gained a better understanding of the mechanisms by which certain tumor types tend to metastasize specifically to bone. It appears that the interaction between the organ microenvironment and cancer cells is fundamental for establishing metastatic growth. Accordingly, Stephen Paget's 'seed and soil' hypothesis - stating that circulating cancer cells (the 'seeds') disperse in all directions, but can accomplish metastases only in organs where the microenvironment (the 'soil') is permissive for their growth - still holds forth today. For this reason, this review uses the 'seed and soil' hypothesis as a template to discuss novel insight and developments in the bone metastasis field.

Interference with the Microenvironmental Support Impairs the De novo Formation of Bone Metastases In vivo

Interference with the microenvironmental growth support is an attractive therapeutic strategy for repressing metastatic tumor growth. Bone is a highly dynamic tissue that is continuously remodeled by bone resorption and subsequent bone formation. Growth factors supporting bone metastatic growth are released especially during bone resorption. Differently from most other tissues, drugs that can limit local turnover, such as bisphosphonates, are available for bone. In the present study, we tested the hypothesis that inhibition of bone turnover can affect development and growth progression of experimental bone metastasis. Whole-body bioluminescent reporter imaging was used for the detection, monitoring, and quantification in vivo of the growth progression of bone metastases induced by intracardiac or intraosseous injection of luciferase-transfected breast cancer cells (MDA-231-B/luc+) to nude mice. Suppression of bone turnover by bisphosphonates, before bone colonization by cancer cells, inhibited by a great extent the number of developing bone metastasis. Tumor growth in the few, but still developing, bone metastases was affected only transiently. Reduction of bone turnover had no effect on growth progression of bone metastases, which were already established when bisphosphonate treatment was initiated, despite a substantial reduction in osteolysis. Therefore, cancer cells metastatic to bone, after an initial growth phase that depends on the interaction with the local stroma, become independent of microenvironmental growth factor support and progress autonomously. Inhibition of bone turnover may represent a useful adjuvant therapy especially for cancer patients at risk to develop bone metastasis.

Regulation of dihydropyrimidine dehydrogenase and pyrimidine nucleoside phosphorylase activities by growth factors and subsequent effects on 5-fluorouracil sensitivity in tumor cells

Dihydropyrimidine dehydrogenase (DPD) and pyrimidine nucleoside phosphorylase (PyNPase) are the first and rate-limiting enzymes that regulate 5-fluorouracil (5-FU) metabolism, and tumoral DPD activity appears to be a promising predictor of 5-FU sensitivity. However, the regulatory mechanisms determining these enzyme activities have not been fully understood. We investigated the biological effects of epidermal growth factor (EGF) and transforming growth factor (TGF)-alpha on cell growth and tumoral DPD and PyNPase activities, and the subsequent effects on 5-FU sensitivity in uterine cervical carcinoma SKG-IIIb cells. The treatment of tumor cells with EGF or TGF-alpha resulted in a concentration-dependent increase in tumor cell growth and PyNPase activity, whereas tumoral DPD activity was inhibited. Their stimulatory effects on tumor cell growth correlated well with PyNPase activity, but were inversely related to DPD activity (P < 0.01). 5-FU sensitivity of tumor cells increased in the presence of EGF or TGF-alpha. These growth factors were shown to stimulate the first, rate-limiting enzyme activity in 5-FU anabolism and to inhibit that in 5-FU catabolism, leading to enhancement of the antiproliferative action of 5-FU at achievable therapeutic levels. The tumor environmental factors, EGF and TGF-alpha, may act as intrinsic regulators of DPD and PyNPase activities that affect the 5-FU sensitivity of individual tumors.

Neurophysiology of Cancer Pain: From the Laboratory to the Clinic

Pain is one of the most distressing symptoms associated with cancer. Basic science research has provided much insight into the mechanisms of peripheral and central pain and the actions of new drugs. Despite these advances, pain accompanying malignancy can be difficult to treat. Pain most commonly presents when the tumor has invaded somatic,visceral, or neural structures. An understanding of pain mechanisms is essential when deciding on the appropriate treatment. New therapeutic options have been developed and will hopefully provide clinicians with tools to successfully alleviate cancer pain.

Interleukin-1 alpha induced cyclooxygenase-2 expression in bone-derived endothelial cells

Histological studies have suggested that vascular endothelial cells in bone are members of a complex network that regulates bone development and remodeling by producing soluble factors or by mediating cell-cell adhesion. To clarify the role of bone-derived endothelial cell lines (BDECs) in bone remodeling, we established several clones of BDECs from the femurs of BALB/c mice after transformation with the SV40 virus. Then we examined the response of these clones to interleukin-1alpha (IL-1alpha). IL-1alpha is known to induce bone resorption in part by increasing the expression of cyclooxygenase-2 (COX-2) that is associated with the production of PGE2 in osteoblast-lineage cells. Treating the primary and established BDECs with IL-1alpha induced COX-2 mRNA expression. A transcriptional activation assay revealed that the treatment with IL-1alpha increased COX-2 promoter activity in a dose-dependent manner, and IL-1alpha promoted COX-2 protein expression in BDECs. Treatment with IL-1alpha promoted PGE2 production from BDECs in a dose-dependent manner. These results indicate that IL-1alpha stimulates PGE2 synthesis largely by inducing BDECs to express COX-2. Because PGE2 stimulates bone resorption, these vascular endothelial cells, as well as osteoblast cells, play important roles in bone remodeling.

Effects of sex steroids and growth factors on invasive activity and 5'-deoxy-5-fluorouridine sensitivity in ovarian adenocarcinoma OMC-3 cells

Effects of sex steroids (estradiol-17 beta, E2; progesterone, Prog) and growth factors (epidermal growth factor, EGF; transforming growth factor-alpha, TGF-alpha) on invasive activity and 5'-deoxy-5-fluorouridine (5'-dFUrd) sensitivity of ovarian adenocarcinoma OMC-3 cells were investigated. Tumor cell migration along a gradient of substratum-bound fibronectin and invasion into reconstituted basement membrane were inhibited by 10 microM Prog, but stimulated by 0.1-10 nM EGF and TGF-alpha in a concentration-dependent manner. E2 did not have any effect on tumor cell migration or invasion. The zymography of tumor conditioned medium showed that the treatment of OMC-3 cells with EGF and TGF-alpha resulted in increases of type IV collagenase, stromelysin and urokinase-type plasminogen activator (uPA). EGF and TGF-alpha up-regulated thymidine phosphorylase (dThdPase) expression of tumor cells and consequently enhanced the antiproliferative action of 5'-dFUrd, which is converted to 5-fluorouracil by dThdPase. E2 and Prog did not have significant effects on the expression of proteolytic enzymes and dThdPase, or on the 5'-dFUrd sensitivity of tumor cells. The inhibitory effect of Prog on tumor cell invasion may depend on its inhibitory action on the motility of tumor cells. These results suggest that EGF and TGF-alpha simultaneously up-regulate the potential of ovarian adenocarcinoma cells to invade extracellular matrices and their dThdPase expression, both of which are associated with the specific action of 5'-dFUrd selectively to kill tumor cells with high invasive and metastatic potential.

Mannose receptor-mediated endothelial cell activation contributes to B16 melanoma cell adhesion and metastasis in liver

The role of mannose receptors from hepatic sinusoidal endothelium (HSE) in liver colonization by B16 melanoma (B16M) cells was studied. The expression of high mannose-type oligosaccharides on the surface of B16M cells was enhanced by in vitro treatment with 1-deoximannojirimycin (1-DMM). There was a significant (P < 0.01) enhancement of hepatic metastasis when B16M cells were 1-DMM-treated before being intrasplenically injected into C57BL/6J mice. Intraperitoneal administration of 5 mg/kg recombinant human interleukin-1 receptor antagonist (rHuIL-1Ra) inhibited the 1-DMM-induced enhancement of metastasis. Expression of high mannose-type oligosaccharides on the surface of 1-DMM-treated B16M cells and their in vitro adhesion to the HSE was significantly correlated (R = 0.82). The addition of either 100 microg/ml mannan or paraformaldehyde (PFA)-fixed 1-DMM-treated B16M cells to cultured HSE for a period of 12 h significantly (P < 0.01) increased the release of IL-1beta from the HSE compared to that liberated by the HSE incubated with either basal medium or PFA-fixed untreated B16M cells. The same HSE treatments also significantly (P < 0.01) increased the degree of adhesion of other B16M cells to HSE, being abrogated by anti-mouse vascular cell adhesion molecule-1 (VCAM-1) antibodies. The conditioned media from HSE cultures, activated by PFA-fixed, 1-DMM-treated B16M cells significantly (P < 0.01) increased B16M cell proliferation when compared to conditioned media from HSE cultures incubated with PFA-fixed, untreated B16M cells. Thus, 1-DMM treatment of B16M cells enhanced the development of hepatic metastasis by IL-1-dependent mechanisms. The mechanism is consistent with in vitro mannose receptor-mediated melanoma cell attachment to the HSE, which subsequently upregulates IL-1beta release, VCAM-1-dependent adherence, and melanoma growth factor(s) release by HSE.

Stimulatory effects of EGF and TGF-alpha on invasive activity and 5'-deoxy-5-fluorouridine sensitivity in uterine cervical-carcinoma SKG-IIIb cells

We investigated the effects of epidermal growth factor (EGF) and transforming growth factor (TGF)-alpha on migration, invasion and matrix metalloproteinase (MMP) expression of uterine cervical-carcinoma SKG-IIIb cells, and whether these growth factors affect pyrimidine-nucleoside-phosphorylase (PyNPase) activity and 5'-deoxy-5-fluorouridine (5'-dFUrd) sensitivity of tumor cells. Tumor-cell migration along a gradient of substratum-bound fibronectin and invasion into reconstituted basement membrane were stimulated by 0.1 to 100 ng/ml of EGF and TGF-alpha in a concentration-dependent manner. The zymography of tumor-conditioned medium showed that the treatment of tumor cells with EGF and TGF-alpha resulted in an increase of the 92-kDa type-IV collagenase (MMP-9), which was confirmed by immunoblot analysis. These growth factors also up-regulated the expression of PyNPase activity of tumor cells and consequently enhanced the anti-proliferative action of 5'-dFUrd, a cytostatic that is biotransformed to 5-fluorouracil (5-FUra) by PyNPase. However, EGF and TGF-alpha did not have significant effects on the 5-FUra sensitivity of tumor cells. These results suggest that EGF and TGF-alpha, tumor environmental factors, simultaneously up-regulate the potential of uterine cervical-carcinoma cells to invade extracellular matrices and their PyNPase activity, which are subsequently associated with the specific action of 5'-dFUrd selectively killing tumor cells of gynecological origin with high invasive and metastatic potential.

Interleukin 1-dependent and -independent mouse melanoma metastases

BACKGROUND

The adhesion of cancer cells to the endothelial lining of blood vessels, which is important for metastasis, is promoted by the action of interleukin 1 (IL-1) and other cytokines.

PURPOSE

IL-1-producing melanoma cells were used to induce metastases in mice to test whether melanoma metastasis--wherever it occurs--depends on the action of IL-1.

METHODS

We used the following experimental designs in this study: 1) Male C57BL/6J mice were inoculated in the left cardiac ventricle with 5 x 10(4) murine B16 melanoma cells, and no treatment was given (control animals). 2) Mice received an intraperitoneal injection of either saline (control animals) or recombinant human IL-1 receptor antagonist (rHuIL-1Ra) 2 hours before the injection of cancer cells; thereafter, they received an additional injection of saline or rHuIL-1Ra daily for 20 days. 3) Mice received an intravenous injection of either saline or rHuIL-1Ra; 15 minutes later, mice that received saline were given either a second injection of saline (control animals) or an injection of bacterial lipopolysaccharide (LPS) to stimulate host IL-1 production and endothelial cell activation. The mice that received rHuIL-1Ra were also given an injection of LPS at this time. Six hours later, all mice were inoculated with cancer cells, followed by no further treatment. In all experiments, the mice were killed 20 days after the injection of cancer cells, and metastases were counted in multiple organs and bones. Metastasis incidence values (relating to the frequency that a given site was positive for metastasis) and metastasis development index values (relating to the extent of metastasis at a given site) were calculated. A hierarchical cluster analysis was performed to determine whether groups of organs exhibited characteristic changes in their metastasis development index values in response to the three treatments given (i.e., rHuIL-1Ra, LPS, or rHuIL-1Ra plus LPS). Reported P values are two-sided.

RESULTS AND CONCLUSIONS

Treatment with rHuIL-1Ra alone significantly (P<.05) reduced the occurrence of metastasis in the bone marrow, spleen, liver, lung, pancreas, skeletal muscle, adrenal gland, and heart, indicating that host- and/or melanoma-derived IL-1 promoted metastasis in these organs; treatment with rHuIL-1Ra had no effect on metastasis in the kidney, testis, brain, skin, and gastrointestinal tract, suggesting that metastasis in these latter organs was IL-1 independent. Treatment with LPS alone significantly (P<.05) enhanced metastasis in the same organs for which rHuIL-1Ra treatment reduced metastasis, except for the heart and the adrenal gland. Treatment with rHuIL-1Ra 15 minutes before LPS treatment abrogated the LPS-mediated enhancement of metastasis. Two independent organ groups for which IL-1 promoted melanoma metastasis were identified in the cluster analysis.

Experimental study on the role of osteoclasts and free radicals in the mandibular invasion of VX2 carcinoma in Japanese white rabbits

Oxygen-derived free radicals are stimulators of bone resorption in vitro and in vivo. We hypothesized that oxygen-derived free radicals or reactive oxygen species (ROS) generated around bone matrix invaded by cancer cells might be associated with the activation or formation of osteoclasts in bone metastasis, and thus the administration of an ROS scavenger or a free-radical scavenger might control osteoclastic bone destruction in tumor metastasis. We examined the ability of VX2 carcinoma cells to generate superoxide anion (O2-) as well as the effects of the O2- scavenger superoxide dismutase (SOD) and the hydrogen peroxide (H2O2) scavenger catalase (CAT) on the activation and formation of osteoclasts in VX2 carcinoma tissue of rabbits. VX2 carcinoma cells generated more O2- than tartrate-resistant acid phosphatase-positive (TRAP+) cells. The TRAP activity from TRAP+ cells in the presence of VX2 carcinoma cells was higher than that from TRAP+ cells in the absence of the carcinoma cells. The addition of SOD but not of CAT into the incubation medium inhibited the TRAP activity from TRAP+ cells in the presence or absence of VX2 carcinoma cells. Similar inhibitory effects were also observed with SOD plus CAT on TRAP+ cells in the presence or absence of carcinoma cells. Intravenous administration of SOD and SOD plus CAT, but not of CAT, caused a decrease in the number of osteoclasts in mandibles implanted with VX2 carcinoma cells, and showed a predominant occupation by osteoclasts with poorly developed ruffled borders in lesions of bone resorption. In contrast, the administration of CAT, but not of SOD and SOD plus CAT, decreased the more mature forms of osteoclasts in implanted mandibles. From the results obtained, it is suggested that O2- may stimulate bone resorption by increasing the activity and number of osteoclasts, and H2O2 may stimulate resorption by enhancing the formation of mature osteoclasts in tumor metastasis. The administration of some ROS or free-radical scavengers to patients with cancer may provide a defense against bone destruction in bone metastatic lesions.

IL-1alpha gene-transfected human melanoma cells increase tumor-cell adhesion to endothelial cells and their retention in the lung of nude mice

The interleukin-1alpha(IL-1) gene was introduced by retroviral gene transfer into the A375P human melanoma cell line. Two hygromycin-resistant colonies, colony 3 and colony 6, which respectively do not and do express and release IL-1, were selected on the basis of Northern blot and ELISA. Both colonies adhered to resting human endothelial cells (EC) to the same extent. Pre-treatment of EC for 6 hr with conditioned medium (CM) from colony 6, but not from colony 3, increased the adhesion of A375P melanoma and HT-29 colon-carcinoma cells to EC. This increase was blocked by adding interleukin-l-receptor antagonist (IL-1ra) to the EC monolayer. Treatment of EC with colony-6-CM increased the expression of intercellular-adhesion molecule I (ICAM-1), vascular-cell-adhesion molecule I (VCAM-1) and E-selectin. Co-cultivation of colony-6 but not colony-3 melanoma cells with EC caused time-dependent increased expression of these adhesion proteins, reflecting their kinetics of expression on EC. Treating the EC with monoclonal antibodies to VCAM-1 and E-selectin abolished the colony-6-CM-induced increase in adhesion respectively to A375P melanoma and HT-29 colon-carcinoma cells. In vivo, i.v. injection of colony-6 cells in nude mice increased the expression of VCAM-1 on lung microvascular EC. The retention of radiolabeled A375P melanoma cells in the lung was increased in nude mice primed with colony-6 cells, but not with colony-3 cells, injected 6 hr earlier. These results demonstrate that IL-1 produced constitutively by transformed A375P melanoma cells is functionally active, inducing adhesion molecules on EC that enhance their adhesiveness for tumor cells and increase tumor-cell retention in the lung of nude mice.

Effect of osteoblast supernatants on cancer cell migration and invasion

Malignant tumor cells of different origin seem to have preferential sites for metastasis. Breast cancer, prostate cancer and certain melanomas have bone as one of their preferential targets for metastasis. Bone is continuously being remodelled, a process largely controlled by local growth factors. A possible explanation for malignant cell recruitment to bone is that osteoblast products, directly secreted or released from the matrix by osteoclast resorbing activity, are able to stimulate cancer cell migration. To test this hypothesis we have utilized an in vitro system of differentiating osteoblasts which in culture progress all the way to the formation of mineralized nodules. Conditioned media obtained from these osteoblast cultures at different stages were able to induce chemotactic migration and invasion of both melanoma and breast cancer cells. The migratory and invasive phenotype was accompanied by enhanced gelatinolytic activity of osteoblast stimulated cancer cells. Our data suggest that osteoblasts secrete potent factors able to direct tumor cell migration towards remodelling bone.

Selective inhibition of spontaneous pulmonary metastasis of Lewis lung carcinoma by 5'-deoxy-5-fluorouridine

5'-deoxy-5-fluorouridine (5'-FUdR) is a cytostatic that is biotransformed to 5-fluorouracil (5-FUra) by pyrimidine nucleoside phosphorylase (PyNPase), the expression of which is up-regulated by tumor necrosis factor alpha (TNF alpha), interleukin-1 alpha (IL-1 alpha) and interferon gamma (IFN gamma). In Lewis lung carcinoma (LLC) cell cultures, these inflammatory cytokines up-regulated the expression of type-IV collagenase, metastatic factor, as well as PyNPase and consequently enhanced the antiproliferative activity of 5'-FUdR. However, the activity of 5-FUra was not enhanced. It appears that 5'-FUdR selectively kills highly metastatic cells which are exposed to these intrinsic cytokines in tumor tissues, because of their high PyNPase activity. In fact, 5'-FUdR inhibited the spontaneous metastasis of LLC from the s.c. inoculation site to the lung. When 5'-FUdR was given during the process of metastasis it greatly reduced the number of tumor nodules in the lung even at doses 46 times lower than those inhibiting the primary tumor growth. In addition, 5'-FUdR, but not 5-FUra, lowered type-IV collagenase levels in the tumors at the low dose showing only anti-metastatic activity. On the other hand, 5-FUra showed anti-metastatic activity at doses similar to or only several times lower than those inhibiting the primary tumor growth.

On the inhibition of prostanoid formation by SK&F 96365, a blocker of receptor-operated calcium entry

1. The proposed blocker of receptor-operated calcium channels, SK&F 96365 was shown to inhibit formation of prostaglandin E2 in two osteoblast-like cell lines, MC3T3-E1 and UMR-106 in a dose-dependent manner at an IC50 of 3-4 microM. Inhibition was observed with various stimuli (arachidonic acid, bradykinin and calcium ionophore A23187). 2. This effect was also observed in human platelets, where SK&F 96365 dose-dependently blocked thromboxane biosynthesis and formation of 12-hydroxy-heptadecatrienoic acid after stimulation with arachidonic acid (IC50 = 4 microM). 3. The compound had no effect on 12-hydroxy-eicosatetraenoic acid production by human platelets. Additionally, linoleic acid oxidation by soybean 15-lipoxidase was not impaired by SK&F 96365. The results thus provide evidence for cyclo-oxygenase inhibition by SK&F 96365 at concentrations used to block receptor-operated calcium influx.

The relative roles of vitronectin receptor, E-selectin and alpha 4 beta 1 in cancer cell adhesion to interleukin-1-treated endothelial cells

Adhesion of cancer cells to endothelium is thought to be a prerequisite to extravasation during the haematogenous phase of metastasis, and is enhanced after perturbation of the endothelium by interleukin-1 (IL-1). The inducible endothelial adhesion molecules, E-selectin, VCAM-1/alpha 4 beta 1 and vitronectin receptor have been reported to mediate attachment of cancer cells to IL-1-treated endothelial cells. We have examined the relative contribution of these molecules by quantifying the adhesion of a panel of 22 human, 125I-labelled cancer cells and the rat W256 tumour to untreated and IL-1-treated endothelial monolayers in the presence of relevant neutralising antibodies. Antibodies against E-selectin inhibited the adhesion of HL-60 leukaemia cells and two colon carcinomas. Anti-alpha 4 beta 1 antibodies blocked adhesion of four melanomas, five sarcomas and one lung carcinoma. Anti-vitronectin receptor antibodies inhibited adhesion of 14 of the 22 human cell lines to IL-1-treated endothelial cells. Adhesion of seven cell lines was inhibited by more than a single antibody. In contrast, adhesion of one of the cancer cell lines was unaffected by any of the antibodies, suggesting involvement of other IL-1-inducible endothelial adhesion molecules. Moreover, none of the antibodies altered the attachment of cancer cells to unstimulated endothelial monolayers. We conclude that the mechanisms of cancer cell adhesion to the endothelium are influenced by endothelial activation and by the adhesive repertoire of the cancer cell.

Adhesion molecules and their role in cancer metastasis

This article describes various adhesion molecules and reviews evidence to support a mechanistic role for adhesion molecules in the process of cancer metastasis. A variety of evidence supports the involvement of specific adhesion molecules in metastasis. 1. For example, some cancer cells metastasize to specific organs, irrespective of the first organ encountered by the circulating cancer cells. This ability to colonize a specific organ has been correlated with the preferential adhesion of the cancer cells to endothelial cells derived from the target organ. This suggests that cancer cell/endothelial cell adhesion is involved in cancer cell metastasis and that adhesion molecules are expressed on the endothelium in an organ-specific manner. 2. Further, inclusion of peptides that inhibit cell adhesion, such as the YIGSR- or RGD-containing peptides, is capable of inhibiting experimental metastasis. 3. Metastasis can be enhanced by acute or chronic inflammation of target vessels, or by treatment of animals with inflammatory cytokines, such as interleukin-1. In vitro, cancer cell/endothelial cell adhesion can be enhanced by pretreating the endothelial cell monolayer with cytokines, such as interleukin-1 or tumor necrosis factor-alpha. This suggests that, in addition to organ-specific adhesion molecules, a population of inducible endothelial adhesion molecules is involved and is relevant to metastasis. 4. Further support for this model is found in the comparison to leukocyte/endothelial adhesion during leukocyte trafficking. Convincing evidence exists, both in vivo and in vitro, to demonstrate an absolute requirement for leukocyte/endothelial adhesion before leukocyte extravasation can occur. The relevance of this comparison to metastasis is reinforced by the observation that some of the adhesion molecules involved in leukocyte/endothelial adhesion are also implicated in cancer cell/endothelial adhesion. The involvement of adhesion molecules suggests a potential therapy for metastasis based on interrupting adhesive interactions that would augment other treatments for primary tumors.