The antimetabolite Tiazofurin (TR) inhibits glycoconjugate biosynthesis and invasiveness of tumour cells

We investigated the effect of Tiazofurin (TR-2-beta-D-furanosylthiazole-4-carbamide) on tumour cell invasion using metastatic 3LL-HH murine lung carcinoma and HT168-M1 human melanoma as experimental models. TR pretreatment of 3LL-HH cells, in a dose range of 15-60 microM, caused inhibition of cell proliferation, adhesion to plastic and extracellular matrix proteins. The TR-induced altered matrix interactions of 3LL-HH cells were reflected in decreased migration through matrix-covered filters. Analysis of the expression of certain invasion markers indicated that TR suppressed the expression of alpha v beta 3 integrin and MMP2 metalloproteinase. Biochemical studies indicated that 24 h 60 microM TR treatment of 3LL-HH cells inhibited glycosylation of a wide range of glycoproteins with the most pronounced effect on proteoglycans. TR pretreatment of 3LL-HH tumour cells resulted in the loss of lung colonisation potential in vivo. Furthermore, in vivo TR treatment inhibited the formation of liver metastases of 3LL-HH murine carcinoma. TR treatment also induced inhibition of integrin and MMP2 expression, migration and liver colonisation of the human melanoma HT168-M1 cell line. Since the TR concentration which inhibited various cellular functions was much lower for cell adhesion and lung colonisation than for cell proliferation, we suggest that the predominant effect of TR is the inhibition of metastasis in these model systems. We also suggest that both the effect of TR on tumour cell proliferation and on extracellular matrix interaction contribute to its remarkable antimetastatic potential in vivo.

Small bowel obstruction caused by a medication bezoar: report of a case

We report herein the rare case of a 26-year-old woman who developed a small-bowel obstruction caused by a medication "bezoar" or enterolith, following the long-term ingestion of magnesium oxide cathartics for constipation. Medication bezoars resulting from laxatives or cathartics have rarely been reported and we were only able to find two other such cases in the literature.

Modulation of heparan-sulphate/chondroitin-sulphate ratio by glycosaminoglycan biosynthesis inhibitors affects liver metastatic potential of tumor cells

Previous data have indicated that the proteoglycan (PG) pattern is different on tumor cells with different liver metastatic potential. We selected "conventional" glycosaminoglycan (GAG) biosynthesis inhibitors, beta-D-xyloside (BX), 2-deoxy-D-glucose (2-DG), ethane-l-hydroxy-l,l-diphosphonate (ETDP) and the newly discovered 5-hexyl-2-deoxyuridine (HUdR), to modulate PGs on highly metastatic/liver-specific 3LL-HH murine carcinoma and HT168 human melanoma cells and to influence their liver colonization potential. These compounds all induced remarkable changes in GAG biosynthesis, but to varying degrees: glucosamine labelling was affected mainly by 2-DG, and HUdR and sulphation by BX and HUdR. Furthermore, the ratio of heparan sulphate/chondroitin sulphate (HS/CS) of PGs was increased by ETDP and decreased after treatment by HUdR. In addition to changes in PG metabolism, tumor-cell proliferation and adhesion to fibronectin were affected; BX and 2-DG stimulated cell proliferation and adhesion, while HUdR inhibited both proliferation and adhesion. Most interestingly, HUdR, the most effective inhibitor of HS/HSPG, depressed the formation of liver colonies, while ETDP, the most effective inhibitor of CS/CSPG, stimulated the appearance of liver colonies. These observations indicated that, at least in these experimental systems, tumor cells with a high HS/CS ratio are more likely to form liver metastases; consequently, anti-HS agents could also be anti-metastatic.

Metastasizing rat nephroblastoma. A rodent Wilms' tumour model

In newborn F344 rats, immunosuppressed with antithymocyte sera and xenografted with various human tumours (lymphomas and melanomas), regular development of nephroblastomas was observed. Transplantation experiments and chromosome analysis proved the rat origin of the tumours. The histological appearance of these rat nephroblastomas closely resemble that of the human Wilms' tumour, in which three basic components: blastema, stroma and immature epithelium can be distinguished. With serial subcutaneous-, lung-subcutaneous transplantations in immunocompetent newborn animals a spontaneously metastatic line to the lung was selected. In adult hosts, lung metastasis occurred only following orthotopic (subrenal capsule) implantation. The histogenesis and the morphological features of this rat nephroblastoma and its metastases are described.

Morphological aspects of angiogenesis in experimental liver metastases

In this work we describe the process of angiogenesis in liver metastases of high- and low-metastatic 3LL mouse carcinoma lines. Fourteen days after intrasplenic inoculation of the tumor lines, two types of metastases were observed; a sinusoidal type, containing large convoluted vessels and devoid of immunohistochemically detectable basement membrane, and a portal type, located in the vicinity of portal tracts, characterized by numerous small vessels, and staining positively for basement membrane components. After intrasplenic inoculation of the high-metastatic tumor cells (portal route) only 18.2% of the metastases were portal type, whereas when the tumor cells were injected into the left ventricle (arterial route), a significantly higher percentage of the metastases (33.2%) proved to be portal type. Detailed analysis of the process of angiogenesis were performed only concerning the main, sinusoidal type metastases. After intrasplenic inoculation of tumor cells, vascularization of tumor colonies started on day 6 by the appearance of intratumoral sinusoids lined by endothelial cells. These sinusoids were directly connected with liver sinusoids. Afterward (11 to 14 days), large convoluted vessels developed within the metastases, in which tumor globules protruded. These globules were covered by factor VIII-related antigen-positive endothelial cells. The functioning vascular nature of these vessels were proven by supravital staining with Hoechst 33342 dye and by bromodeoxyuridine labeling. The first event of the angiogenesis in sinusoids and veins seemed to be the separation of the endothelial cells from their basement membrane, demonstrated by electron microscopic immunohistochemistry (laminin, fibronectin). This process elicited vigorous proliferation of the matrix-deprived endothelial cells, shown by the increased bromodeoxyuridine labeling index and by the increased number of endothelial cell nuclei per mm vessel length. Morphometric analysis of the sinusoids in the perimetastatic zone (up to 100 mu) and in the normal liver parenchyma showed neither dilatation of the vessels nor sprouting of new vessels in the former region. There was no difference in the neovascularization of the liver metastases of the high- and low-metastatic carcinoma lines. The dominant type of angiogenesis in liver metastases can be determined by the unique basement membrane architecture of the liver and by the high affinity of 3LL tumor cells to the endothelial side of basement membrane during invasion.

First steps of tumor-related angiogenesis

We present morphological data of the early steps of tumor-induced angiogenesis and show the distribution of the three main components of the basal lamina (BL), laminin, collagen IV, and fibronectin during these early processes. Tumor cells of a line of BSp73 AS a nonmetastasizing tumor isolated from a pancreatic adenocarcinoma were injected subcutaneously into the back of BDX rats. Two days after tumor inoculation, the BL of the dilated mother vessels around the whole circumference of the vessel has either disappeared, become fragmented, or developed several successive layers. By immunoelectron microscopy, we demonstrate that the fragmented and multilayered BL is strongly stained for laminin and collagen IV but less strongly for fibronectin. Around the surface of the dilated mother vessels which are free of any detectable BL material (by electron microscopy standards), we can see accumulation of all three components in the connective tissue. Simultaneously with the alteration of the BL, the proliferation of the endothelial cells (EC) and the pericytes and the migration of the EC from the wall of the mother vessel have started. EC migration begins in two different ways. Either one EC migrates from the wall of the mother vessel into the surrounding connective tissue, or two or more EC form nearly parallel processes toward the connective tissue. The tips of these processes are connected by intracellular junctions. Around the cellular protrusions of these cells material of the BL deposited into the nearby connective tissue can be observed neither by conventional nor by immunoelectron microscopy. During the outgrowth and migration, the EC remain in contact via junctions with the EC of the original vessel. When migration during which the EC retain their polarization continues, a slit-like lumen forms immediately between the migrating EC. This lumen always remains in direct connection with the lumen of the mother vessel. It is sealed at its border by intercellular junctions. Such junctional complexes can develop a length (in sections) of several hundred micrometers. A BL detectable in the electron microscope can neither be found around the tip of the migrating EC nor around young capillaries not yet surrounded by pericytes. By immunoelectron microscopy, however, only the cellular protrusions at the tip of migrating EC are free of deposited material of the BL. The basal surface of longer (new) capillaries is covered by a continuous layer of amorphous material.(ABSTRACT TRUNCATED AT 400 WORDS)

Selection and characterization of human melanoma lines with different liver-colonizing capacity

Two human melanoma lines with low (HT168) and high (HT168-MI) liver metastatic capacity in immunosuppressed mice were selected in vivo from the A2058 cell line. After i.v. injection of the 2 tumor lines there was no significant difference either in the number of lung colonies or in the frequency and tissue distribution of extrapulmonary tumor deposits. These findings suggest that the selection in the spleen-liver system did not result in an overall increase in the metastatic potential of the melanoma cells, but rather that it represented an organ-preferential selection. The HT168-MI cells did not acquire an increased growth rate in vitro or in vivo, suggesting that other phenotypic alterations are responsible for the enhanced metastatic capacity. The 2 tumor lines were characterized by similar expression of HLA-A,B,C, transferrin receptor and melanoma-associated proteoglycan antigen. HT168 contained more NGF receptor, while HLA-DR appeared only on HT168-MI cells. This human metastasis model could be useful in studying the mechanisms of liver metastasis formation, as well as in revealing possible new targets of antimetastatic therapy.

Ultrastructure of invasion in different tissue types by Lewis lung tumour variants

Ultrastructural studies on the interactions of low and highly metastatic 3LL tumour lines with the basement membranes (BMs) of capillaries, veins, muscles, nerves and adipose tissue were performed by injecting tumour cells into the foot pad of mice. Haematogenous dissemination is the principle route of metastasis formation. Cells from the highly metastatic line were able to penetrate the blood vessels more efficiently than those from the low metastatic line. This difference was mainly due to a more pronounced diapedesis-like activity of the 3LL-HH cells, and partly to the altered intratumour vessel architecture in the highly metastatic tumour line. There was no difference between the two lines in the ultrastructure and frequency of invasion of nerves and adipose tissue BMs. However, in the highly metastatic line an extremely efficient penetration of muscle cell BM was observed. These results provide further evidence that the interaction of tumour cells with the BMs of different tissue types is one of the main determinants in local and distant dissemination.

[Effect of AS-4370 on gastric emptying--double-blind clinical pharmacological study]

The effect of AS-4370 given in single doses of 2.5, 5 and 10 mg on gastric emptying was investigated using 99mTc-DTPA in healthy volunteers in the placebocontrolled double-blind crossover design. There was no difference in percent activity throughout the period of measurement between AS-4370 2.5 mg and placebo. The percent activity decreased after administration of 5 and 10 mg of AS-4370 in comparison with placebo: the decrease was found during the period from 10 to 18 minutes after start of recording at 5 mg and from 8 to 18 minutes after start of recording at 10 mg. These results demonstrated that AS-4370 at these dose levels apparently accelerated gastric emptying. The analysis of the half emptying time by the crossover method showed that only the time effect was found at 2.5 mg, whereas the half emptying time was obviously shortened at 5 and 10 mg. There was no difference between 5 mg and 10 mg. There was no finding that might warrant a caution in terms of safety. In conclusion, AS-4370 did not affect gastric emptying at 2.5 mg but apparently accelerated gastric emptying at 5 and 10 mg in healthy volunteers.

Glycosaminoglycans as novel target in antitumor therapy

Considering the importance of intercellular contacts in the metastasis of malignant tumours drug action on glycosaminoglycan production as one of the underlying mechanisms in metastasis was investigated. 5-hexyl-2-deoxyuridine/HUdR/was shown to inhibit the conversion of glucosamine to UDP-sugars. Consequently various glycoconjugates were affected, especially the synthesis of heparan sulfate was reduced. It is noteworthy that HUdR inhibited the synthesis of glycosaminoglycans in tumour cells with high metastatic capacity. The biological consequence of the alterations in glycosaminoglycan production was studied on measuring HUdR action on cell surface markers, microinvasion and tumour metastasis in experimental systems. It was concluded that HUdR has remarkable antimetastatic activity which by all probability is due to the inhibition of heparane sulfate synthesis.

[Effects of cisapride on gastric emptying]

To evaluate the effects of cisapride on gastric emptying, gastric emptying was measured in six healthy volunteers using radioisotopic techniques which were established three areas of interest, i.e. the whole stomach, the proximal stomach and the antrum. Following results were obtained. 1. At the half emptying times, cisapride induced a more rapid gastric emptying than did placebo in 5 of 6 volunteers. 2. By analyzing gastric emptying curves obtained from three areas of interest, it was suggested that cisapride enhanced the transfer of gastric contents from the proximal stomach to the antrum together with the antral emptying, so that gastric emptying was accelerated.

Effectiveness of tiazofurin (NSC 286193) in treating disseminated tumor cells and micrometastases in mice

The authors studied the metastasis-inhibiting effect of various dosages of tiazofurin in mice inoculated with a low (LLT) and a highly (LLT-HH) metastatic variant of the Lewis lung carcinoma. The tumor cells were inoculated intravenously (lung colony assay), intramuscularly (muscle-lung metastasis model), and intrasplenically (spleen-liver metastasis model), respectively. In the lung colony assay the tiazofurin proved to be curative. In the muscle-lung and the spleen-liver model the tiazofurin treatment, started after the removal of the parent tumor, drastically decreased the number of metastases in both model systems and brought about a significant prolongation of the survival time in the spleen-liver model. Authors suggest that tiazofurin as one of the most promising candidates for metastasis prevention and inhibition in human beings, too.

Demonstration of the organ preference of liver selected 'high metastatic' Lewis lung tumor cell line

The experimental metastasis patterns of 'low metastatic' Lewis lung tumor (LLT) and liver selected 'high metastatic' LLT-HH were studied following their arterial dissemination. In previous reports it was shown that both tumor lines develop metastases only in the first encountered organ. Here the liver preference of the liver selected cell line is demonstrated. The model of two LLT cell lines can provide experimental evidence for both the 'mechanical' and 'seed and soil' theories of metastasis formation, depending on the site of tumor cell injection.

Two human melanoma xenografts with different metastatic capacity and glycosaminoglycan pattern

Two human melanoma xenografts were compared with respect to their in vivo growth and metastatic potentials as well as glycosaminoglycan patterns. The less differentiated HT 168 tumor showed faster growth at primary sites and a more pronounced capacity for metastasis into the liver. Although chondroitin sulfate was the dominant glycosaminoglycan subtype in both tumors, the more invasive xenograft had a higher heparan sulfate/chondroitin sulfate (HS/CS) ratio. We suggest that tumor progression is influenced by this ratio in this human melanoma system.

Endothelialization of embolized tumor cells during metastasis formation

The reaction of the endothelial barrier to tumor cell extravasation has been studied using electron microscopy. The model system was pulmonary metastases produced by intravenous injection of B16-F10 melanoma cells. A striking difference was observed in the behavior of the endothelial lining of arterioles versus that of capillaries. In capillaries, partial retraction of endothelial cells took place following the attachment of tumor cells. The tumor cells then immediately attached to the basement membrane and the basolateral surface of the retracted endothelial cells. The endothelial cells extended to cover the tumor cells prior to complete extravasation. In the arterioles, on the other hand, endothelial retraction did not occur following tumor cell attachment. Instead the attached tumor cell emboli became encompassed by endothelial cells, outgrowing from the intact endothelial lining of the arteriole. Owing to the proliferation of the tumor cells, tumor colonies encompassed by endothelial cells expanded within the lumen. When these intravascular growths completely filled the lumen, the tumor cells extravasated from the vessel only after the original endothelial layer became mechanically disrupted and the tumor cells thereby came into contact with the basement membrane.

Hemodynamic measurements in a sheep model with a hollow fiber artificial kidney containing modified cellulose

HFAK-RC caused pronounced leukopenia, increase in TXB2 levels in plasma and hemodynamic pressure changes as a reflection of complement activation during EC in sheep. In contrast no increase in TXB2 levels and no changes in hemodynamics are observed with HFAK-MC. The leukopenia and granulocytopenia in the latter is much less pronounced and probably reflects the phenomenon "frustrated phagocytosis".

Fatty degeneration in cultured hepatocytes. A new experimental model

In co-cultures of adult rat hepatocytes and a neonatal rat liver cell line, severe fatty degeneration was induced by the addition of 50% rat serum. The light and electron microscopic patterns did not differ significantly from those of in vivo fatty degeneration and the changes were reversible on removal of the serum. The in vitro system is considered to simulate some forms of fatty degeneration of the liver and to be suitable for testing the effects of liver-protecting agents.

Ultrastructural analysis of experimentally induced invasion in the rat lung by tumor cells metastasizing lymphatically

The colonization of the lung by the rat tumor cells BSp73 ASML which have the ability to metastasize via the lymphatic system was studied at the ultrastructural level. Tumor cells arriving in the lung after i.v. injection become transiently embolized; within hours, however, they begin to extravasate from the blood capillaries. Swelling cellular protrusions open a limited area between endothelium and basal lamina through which tumor cells erupt. Tumor cells then form metastases in the interstitial tissue and, in an apparently lymphotropic action, intravasate the lymphatic vessels in a similar manner to a reverse diapedesis-like process. Within the lympatic system they settle, spread, and build up extensive tumor foci particularly in the subpleural region.

Ultrastructural studies on the lung colonization by nonmetastatic rat tumor cells

The events during the settlement of BSp73AS (AS) tumor cells in the syngeneic rat lung are described. Although AS cells show highly invasive behavior in vitro, subcutaneous primary tumors grow solidly without detectable metastatic spreading. However, AS cells when applied to the syngeneic rats via the tail vein give rise to lung colonies which grow rapidly at the site of the cells' primary arrest in the capillaries. The colonization comprises formation of microemboli, penetration of the endothelium including the basal lamina, and invasion of the lung tissue. Within two weeks, large colonies develop, thereby compressing, invading, and destroying their surroundings without detectable preference in direction. This establishment of AS tumors in the lung reflects the high invasive potential of AS cells and displays many of the morphological features observed during the formation of colonies of metastatic cell lines. Thus, we conclude that a nonmetastatic tumor cell line, such as AS, may possess almost the whole set of properties necessary for successful metastasis.

Experimental approaches to problems of invasion and metastasis

The highly metastasizing ASML cells and the non-metastasizing AS cells, arisen as spontaneous tumors of the rat, were confronted with rat lung tissue in vitro. Small cubes of the lung were allowed to heal their cut edges, then tumor cells were added. Both tumor cell types adapted their shape to the environment, penetrated the superficial layer of lung cells, either of epithelial or of fibroblastoid character and settled on the basal lamina, which, however, was not pierced. In a second set of experiments the tumor cells were inoculated intravenously into the living animal. The lung loaded with tumor cells was excised and cut into cubes which were then incubated in vitro. Here also both tumor cell types exhibited an invasive behavior but the basal lamina of the vessels in which the tumor cells have been arrested was not penetrated. These data indicate that tumor cell behavior is strongly dependent on the environment and the complete invasion or extravasation must be considered as an inducible process.

Invasive activities of metastasizing and nonmetastasizing tumor cell variants in vitro. II. Studies on confrontations with aorta, vein, ductus thoracicus, diaphragm, and lung

In continuation of a previous paper (1), we have prolonged the time of confrontation of two rat tumor cell variants (BSp73 AS and ASML) with normal epithelial cells and broadened the spectrum of confrontation partners. In addition to the aorta we have also used small veins, the ductus thoracicus as a lymphatic vessel, the diaphragm, and lung fragments. The organ sections were preserved for a longer period of time by incubating them in a gyratory shaker. Under these conditions the vessel material and diaphragm remained morphologically intact for up to 12 hrs; lung cubes concealed the cut surfaces by immediate wound healing, and were preserved intact for up to 40 days. All endothelia and the mesothelium of the diaphragm were destroyed by the nonmetastasizing AS cells, but the basal lamina remained intact by morphological criteria even after 18 hrs of exposure to the AS cells. The metastasizing ASML cells attached by filopodia mostly to the basal lamina of the vessels, but were unable to destroy neither the endothelia nor the basal lamina. The superficial cell layers of the lung cubes, however, were penetrated by the cells of both tumor lines, but to a different degree.