Angiogenesis and the unique nature of tumor matrix

In this article we consider the factors responsible for the unique nature of the pericellular matrix of solid tumors and we discuss the role of alterations of tumor blood vessel structure. We examine the role of VEGF (vascular endothelial growth factor), a factor controlling permeability of capillaries, plasma protein extravasation, and the formation of a fibrin barrier. We discuss how this barrier could be destroyed by metalloproteinases bound on the surface of endothelial cells migrating through the matrix and how these enzymes are responsible for the activation of gelatinases that destroy basement membranes. The process called tubulogenesis, which gives rise to hyperpermeable tumor capillaries, will also be described. Alterations of the blood vessel structure leading to hypoxia of the matrix, and accumulation of plasma proteins and of blood cells will be treated. Finally, we review some of the strategies that might exploit this knowledge about the nature of the tumoral matrix for designing novel anticancer treatments.

Poly-L-lysine/heparin stimulates angiogenesis in chick embryo chorioallantoic membrane

The effects of heparin on angiogenesis are controversial, with some studies claiming stimulatory and other studies claiming inhibitory effects. Since heparin in human plasma is complexed with basic peptides and proteins, we studied the angiogenic effect of complexes resulting by mixing poly-L-lysine (a basic heparin-binding polypeptide) and heparin. Angiogenesis was investigate by chorioallantoic membrane assay. In specimens treated with PBS (negative control), or poly-L-lysine, no significant vascular reaction was detectable. Heparin induced only moderate angiogenic response. However, neutral complexes purified from a mixture of poly-L-lysine and heparin (20/1, w/w) induced a very strong angiogenic response. These results demonstrate that the angiogenic effect of heparin was associated with neutralization of electric charge when the polysaccharide was complexed with a basic peptide.

Isolation of endogenous anticoagulant N-sulfated glycosaminoglycans in human plasma from healthy subjects

Endogenous N-sulfated glycosaminoglycans (GAGs) comigrating with standard heparin and sensitive to nitrous acid treatment were isolated from plasma of healthy donors. The amount of these compounds was 7-10 microg/ml, and activated partial thromboplastin time, anti-Xa and anti-IIa activities were similar to those of standard heparin of high molecular mass. Analysis with gradient PAGE of the putative endogenous heparin showed a mean molecular mass of 12 kD. These N-sulfated GAGs could be isolated only after removal of binding peptides that impaired purification by ion-exchange chromatography. We used SDS-PAGE as a tool to separate peptides from endogenous GAGs. N-sulfated GAGs exited the gel before peptides when the electrophoresis was overrun. Endogenous GAGs could be recovered by ion-exchange chromatography of the SDS-PAGE buffer, 'free' from associating peptides. These results strongly support the hypothesis that endogenous heparin is associated in vitro with a variety of proteins and that this association could be responsible for modification of both heparin and protein activities.

Molecular polarity in endothelial cells and tumor-induced angiogenesis

Endothelial cells expose receptors for vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) at the abluminal, basal surface that work as basic regulators of tumor-induced angiogenesis. Their specific localization makes them susceptible to the activity of tumor-released stimulatory factors, like VEGF/VPF, which induce proliferation of the endothelial cell toward the extracellular matrix. At the same time, VEGF/VPF stimulates endothelial cells to expose tissue factor (TF), the high-affinity transmembrane receptor and cofactor for cellular initiation of the plasma coagulation protease cascades through the extrinsic pathway, so generating thrombin. Thrombin exerts a number of activities: it forms an extracellular fibrin barrier from the VEGF/VPF-dependent fibrinogen extravasation; it activates progelatinase-A (pro-MMP-2), which destroys the basal membrane, allowing proliferation of endothelial cells (ECs) in the novel tumoral fibrin matrix; finally, it induces EC proliferation, potentiating the VEGF effect. Another important factor exposed at the abluminal endothelial cell surface is membrane type 1 matrix metalloproteinase (MT1-MMP), a membrane-bound metalloproteinase, which also activates progelatinase-A, allowing an alternative pathway to that of thrombin to destroy the basal membrane. In addition, we will see that MT1-MMP is also engaged in a direct, cell-associated fibrinolytic activity, essential for tubulogenesis of the novel outsprouting capillary.

A method for separation of heparin species from biological samples by ethanol precipitation of compounds solubilized in guanidine hydrochloride

In this paper we describe a procedure to determine glycosaminoglycan and oligosaccharide composition of biological samples such as cell cultures or tissue explants. We demonstrate that heparin species of different molecular mass can be easily fractionated by sequential ethanol precipitation in 4.0 M guanidine hydrochloride. We studied by gradient polyacrylamide gel electrophoresis fractionation of standard heparin and heparin-derived oligosaccharides by anion-exchange chromatography on DEAE-Sephacel resin eluted by increasing concentration of guanidine hydrochloride. The use of guanidine salts followed by sequential precipitation by increasing ethanol concentration allowed recovery of heparin and heparin-derived oligosaccharides.

Influence of static magnetic field on the antiproliferative effects of vitamin D on human breast cancer cells

We describe the effect of a 0.2 tesla (T) static magnetic field generated by a magnetic resonance tomograph and of vitamin D treatment on a human breast cancer cell line (MCF-7). Cell damage and proliferation were monitored by measuring the incorporation of [3H]thymidine in duplicating DNA and by the clonogenic assay. [3H]Thymidine incorporation in MCF-7 was stimulated by vitamin D at low doses (10(-12)-10(-10) M), whereas it was inhibited at higher concentrations (10(-9)-10(-6) M). Magnetic field treatment (0.2 T) decreased [3H]thymidine incorporation in human breast cancer cells, eliminating the proproliferative effect of low doses of vitamin D, and enhanced the vitamin D antiproliferative effect, further reducing [3H]thymidine incorporation, from -12.5% (P < 0.05) to -66.7% (P < 0.001), over the range of 10(-9) to 10(-6) M. In the clonogenic assay, ability of MCF-7 to form colonies was inhibited by vitamin D 10(-9) M and above, whereas 3-h exposure to 0.2 T magnetic field had no effect on the number of cell colonies formed. In conclusion, vitamin D treatment yields a permanent antiproliferative effect, while magnetic field exposure only temporarily slows down cellular growth. These findings suggest that therapy with vitamin D may prove beneficial for chemoprevention or treatment of breast cancer. Static magnetic field, alone or in combination, does not appear to represent an effective candidate for breast cancer therapy, at least at the intensity used in the present study.

Heparin binding peptides co-purify with glycosaminoglycans from human plasma

Glycosaminoglycans (GAGs) are complexed with plasma proteins and proteolysis of plasma reduced the protein-GAG ratio about 140-fold. After dialysis, analysis by gradient PAGE revealed heparinase-1-sensitive GAGs, thus suggesting that heparin could be among the plasma GAGs. However, after dialysis most of the plasma GAGs were still not 'free'. PAGE of peptides resistant to proteolysis showed high molecular weight bands on the two sides of the dialysis membrane despite the 3.5 kDa molecular weight cut-off. Progressive dilution of the sample allowed passage of peptides appearing as high molecular weight bands in the diffusate. We interpret this phenomenon as the presence of low molecular weight peptides that aggregate when concentrated. Peptides on both sides of the membranes bound heparin.

Bone mineral density and anthropometric measures in normal and osteoporotic men

In an ethnically homogeneous men population living in Tuscany, Italy, the relationship between age, height, body weight and bone mineral density were studied. In 50 men bone mineral density was measured by Dual Energy X ray Absorptiometry (DEXA). 13 subjects (26%) were osteoporotic. Age and bone mineral density were not related (R2 = 0.052). Bone mineral density was associated with body weight (R2 = 0.303), and height (R2 = 0.155). In osteoporotic men, mean (+/- SD) body weight was Kg. 65.8 +/- 11.2, lower than that recorded in non osteoporotic men, Kg. 77.3 +/- 10.2, (p = 0.0013). Age in osteoporotic and non-osteoporotic men did not differ (53.8 +/- 13.6 yrs and 60.9 +/- 11.8 yrs, respectively; p = 0.077). In conclusion, anthropometric factors, as predictors of bone disease, behave differently in women and men.

Effect of 0.2 T static magnetic field on human neurons: remodeling and inhibition of signal transduction without genome instability

We describe the effect of the static magnetic field generated by a 0.2 T magnetic resonance tomograph on a normal human neuronal cell culture (FNC-B4). After 15 min exposure cells showed dramatic changes of morphology: they formed vortexes of cells and exposed branched neurites featuring synaptic buttons. At the same time, thymidine incorporation and inositol lipid signaling were significantly reduced. Control (sham exposed) or non-neuronal cells (mouse leukemia, and human breast carcinoma cells) did not show any alteration following exposure. Endothelin-1 release from FNC-B4 cells was also dramatically reduced after 5 min exposure. However, PCR analysis of 12 DNA microsatellites selected as gauges of genome instability, did not reveal any alteration following exposure, thus ruling out a direct effect of the magnetic field on DNA stability. These data can be interpreted as a specific effect of the static magnetic field on human neuronal cells and are consistent with the induction of remodeling and differentiation; they demonstrate that fields below 0.5 T have significant biological effects on human neurons.

Association between vitamin D receptor gene polymorphism and nephrolithiasis

AIMS

To study the distribution of vitamin D receptor (VDR) gene alleles in hypercalciuric and nonhypercalciuric nephrolithiasis patients, hypothesizing that distinct biochemical parameters would be associated with different VDR genotypes.

METHODS

12 hypercalciuric, 15 normocalciuric nephrolithiasis patients, and 150 healthy subjects were recruited. The individual genetic pattern for VDR was evaluated by DNA extraction followed by polymerase chain reaction amplification of the VDR gene and digestion with the restriction enzyme BsmI.

RESULTS

In the hypercalciuric group, Bb patients represented 50% (6/12); bb patients 33% (4/12), and BB cases were 16% (2/12). The VDR frequency distribution was not statistically different in hypercalciuric patients and controls (Bb 72%; bb 16%; BB 12%). In the nonhypercalciuric group, the prevalence of the bb genotype (7/15; 47%) was thrice the percentage of control subjects, while the percentage of BB patients was similar to that of the control group (2/15; 13%). Patients with the bb haplotype exhibited a higher daily urinary calcium excretion. Among hypercalciuric patients, after a calcium-restricted diet, bb patients showed a 39% reduction in daily urinary calcium excretion in comparison with a nonsignificant 13% reduction observed in BB subjects (p = 0.004).

CONCLUSIONS

The effects of VDR gene polymorphism on calcium metabolism contribute to the understanding of the pathogenesis of urinary calculi.

Lack of association between body weight, bone mineral density and vitamin D receptor gene polymorphism in normal and osteoporotic women

In an ethnically homogeneous population of women living in Tuscany, Italy, the relationships between age, body weight, bone mineral density and the vitamin D receptor (VDR) gene polymorphism were studied, with the objective of recognizing patients at risk for osteoporosis. In 275 women bone mineral density was measured by Dual Energy X-rays Absorptiometry (DEXA). In 50 of them the individual genetic pattern for VDR was evaluated by DNA extraction followed by PCR amplification of the VDR gene, and digestion with the restriction enzyme BsmI. Age and bone mineral density were inversely related (R2 = 0.298). Body weight was associated with bone mineral density (R2 = 0.059), but not with age. In osteoporotic women, mean (+/- SD) body weight was 59.9 +/- 6.5 Kg, lower than that recorded in non osteoporotic women (64.2 +/- 9.4 Kg), even though not significantly different (p = 0.18). No association was found between VDR gene polymorphism, bone density or body weight. The performance of anthropometric and genetic components appear to be poor, and, at least for the time being, bone mineral density measurement by means of MOC-DEXA represents the optimal method to detect women at risk for postmenopausal osteoporosis.

Distribution and characteristics of synoviocytes in the rabbit knee joint: a scanning/transmission electron microscopic study

The distribution and the characteristics of A and B synoviocytes were investigated using scanning and transmission electron microscopy in the study of the three types of synovial membranes (fibrous, areolar, adipose) of the rabbit knee joint. The scanning electron microscope showed that the B-synoviocytes had dendritic processes and were separated by wide spaces in the fibrous synovium. The areolar synovium was covered by numerous B-synoviocytes of fibroblastoid-shape. The B-synoviocytes of the adipose synovium were characterized by short cytoplasmic processes. The transmission electron microscope revealed that the B-cells showed signs of intense synthetic activity such as the presence of an evident rough endoplasmic reticulum, the Golgi apparatus and many peripheric vesicles. Our study also revealed that cells with morphological and ultrastructural characteristics of macrophages, the so-called A-synoviocytes, were present in the areolar membrane. We concluded that B-synoviocytes can show variable shape under normal conditions: in particular, dendritic morphology seems to be a normal characteristic of the synoviocytes of the fibrous membrane. Moreover, our results demonstrate that A and B synoviocytes are ultrastructurally and morphologically distinct cells and that each type has different functions.

Cardiac magnetic resonance imaging: technique and anatomy

Recent advances achieved in Magnetic Resonance Imaging equipment and procedures allow a thorough study of the heart, yielding anatomic, functional and angiographic information. Spin-echo sequences are specific for heart morphology while gradient-echo sequences are fundamental to the functional study. Fast sequences reduce the examination times with the possibility of single breath-hold images. Coronary arteries can be directly visualized and cardiac perfusion can be assessed. Velocity encoded images allow flow quantification and with myocardial tagging, cardiac mechanics is accurately defined.

Vitamin D receptor gene polymorphism is associated with metastatic breast cancer

The vitamin D receptor (VDR) has been detected in breast tumor cells. We tested the hypothesis that VDR gene polymorphism might influence the outcome of women affected by breast cancer. A total of 88 breast cancer patients were recruited: 50 women were affected by newly diagnosed breast cancer whereas 38 women suffered from relapsing disease. The individual genetic pattern for VDR was evaluated by DNA extraction followed by PCR amplification of the VDR gene, and digestion with the restriction enzyme BsmI. In 167 healthy women, participating in the osteoporosis prevention trial and being used as a control, we detected 121 Bb heterozygotes (72%), 26 homozygotes for the bb alleles (16%), and 20 homozygotes for the BB alleles (12%). In the newly diagnosed breast cancer group the occurrence of Bb patients was 58% (29/50); bb patients represented 22% (11/50), and BB cases were 20% (10/50). The VDR frequency distribution in the control and primary disease patient groups was not statistically different. In the metastatic cancer group, the prevalence of the bb genotype (14/38; 37%) was double the percentage of control subjects, whereas the percentage of BB women with metastases was half the control group (2/38; 5%). Women who were homozygous bb appeared to have almost a four times higher risk of developing metastases than BB women. Whatever the molecular mechanisms underlying the VDR effects in cancer cells, we believe that the VDR gene polymorphism may represent an important determinant in the evaluation of women affected by breast cancer and might help design targeted therapy.

The old and the new in p53 functional regulation

The gene termed p53 is one of the most extensively studied for the past 18 years and the amount of literature published on this gene reflects its relevance in the field of molecular oncology; thus, loss or mutation of this oncosuppressor gene is probably the molecular lesion most frequently observed in human tumors. The aim of this minireview is to report, discuss, and interpret some recent observations on this topic: (I) The relationship with the Ataxia-Telangectasia gene and with the signaling enzyme phosphatidylinositol 3-kinase (PI3K). (II) The relationship between DNA damage, p53, and sensitivity to anticancer therapies. (III) The gain of function caused by mutations that transform the oncosuppressor p53 gene into a dominant transforming oncogene and (IV) The phosphorylative regulation of p53 and its relationship with the mitogenic signaling cascade involving protein kinase C and tumor promoters.

Cellular proliferation and second messenger formation altered by dialysis membranes

BACKGROUND

In this study we investigated the effect of different dialysis membranes on the clonal murine haematopoietic cell line 32D cells transmembrane signalling machinary, monitored by 1,2-diacylglycerol (DAG) formation, and on their ability to respond to the physiological growth factor interleukin-3 (IL-3).

METHODS

Cells were exposed to dialysers (cuprophane, CU; polysulphone, PS; cellulose diacetate, CA; polyacrylonitrile, AN69; polymethylmethacrylate, PMMA; cellulose triacetate, CT; polyamide, PA; and polycarbonate, PC); they were collected, counted, and treated with physiological amount of IL-3. Cell proliferation was monitored as incorporation of radioactivity in duplicating DNA. DAG was measured by thin-layer chromatography in cell labelled with tritiated glycerol overnight.

RESULTS

CU and PA stimulated cell proliferation in comparison with resting cells. PS and TC did not significantly affect thymidine incorporation either in IL-3-stimulated, or in resting cells. Cells exposed to AN69, PC, and CA showed depressed basal incorporation of thymidine (70, 54 and 56% of controls respectively) but retained the ability to respond to IL-3 in a manner not statistically different from controls. PMMA reduced thymidine incorporation both in basal condition and after IL-3 stimulation CU and PC activated early cell signalling (1.95 x and 1.31 x respectively, DAG increase over control), while PA and TC depressed DAG generation (0.38 x and 0.47 x respectively, DAG increase over control). PS, CA, AN69, and PMMA did not stimulate DAG generation.

CONCLUSIONS

Alternations of intracellular mitogenic signalling appear to correlate with the ability to make a cell competent for function. These results might help to elucidate the effect of different dialysers, at the molecular level, on the blood cell behaviour in vivo.

[The determination of BB genotype of vitamin D receptors identifies patients at risk for osteoporosis]

The gene responsible for peak bone mass has been recently identified as the gene coding for the Vitamin D Receptor (VDR); there exist two alleles, termed "B" and "b", determining a typical allelic polymorphism. We determined the VDR genotype of 50 young post-menopausal women (mean age: 56 years), and measured bone density by Dual Energy X ray Absorptiometry (DEXA) twice: at the beginning of the study and after one year. VDR genotype was determined using the DNA extracted from hair cells, thus avoiding the use of blood samples. The frequency of VDR genotypes (BB or bb homozygous; Bb heterozygous) was approximately the same in the two groups of subjects (i.e., normal controls and osteoporotic women). The bone density of normal subjects (36) was measured for the second time one year after the first measurement. All BB homozygous subjects showed significantly decreased bone density values; 50% of them showed values below 0.750 g/cm2 at the second measurement, thus being classified as osteoporotic. However, neither bb homozygous nor Bb heterozygous subjects showed any significant decrease in bone density values (about 4% of the initial value). Therefore, determining the VDR genotype was critical for identifying the subjects who were normal at the first measurement, but had markedly decreased bone density values later, thus being at risk of developing osteoporosis.

Intracellular diacylglycerol: a mitogenic second messenger proposable as marker of transformation in squamous cell carcinoma of the lung

In this study, we examined 50 patients with documented lung cancer projecting in the bronchial lumen unilaterally. Bronchial lavage from the affected and unaffected sides provided neoplastic and normal cells in which we studied an intracellular mitogenic second messenger, diacylglycerol, associated with transformation. The levels of diacylglycerol in cells from the affected side were compared with that from the healthy side, thus providing an internal control for each patient. Our data show that the levels of diacylglycerol in lavage fluid relative to affected bronchus are elevated in 56% of all the patients examined. This elevation reaches 77% in patients with squamous cell carcinoma, a value of sensitivity higher than 'traditional' markers for cancer of the lung. Thus, these findings may have significant implications for the use of diacylglycerol measurement as a novel biomarker for early detection of lung cancer, and for monitoring recurrences after treatment.

In vitro effects of some differentiation inductors in metaplastic epithelium of the human nasal cavity

The alterations in the mucociliary unit in the course of chronic inflammation of the upper respiratory tract correspond to morphologic anomalies of the respiratory epithelium and induce cuboidal and squamous metaplasia. While the squamous pattern is most probably irreversible, it is still not clear whether it is possible to restore ciliogenesis in cuboidal metaplasia. In the present study, the action of different inductors of differentiation was evaluated in vitro in isolated cells and explants from human nasal metaplastic epithelium. Polar/apolar compounds induced secretory activity, whereas retinoic acid was able to induce ciliogenesis in some cases. Therefore, the cuboidal metaplastic condition appears to be reversible, and two distinct pathways of differentiation, secretory and ciliogenetic, are identifiable.