The neurotransmitter dopamine inhibits angiogenesis induced by vascular permeability factor/vascular endothelial growth factor.

Angiogenesis has an essential role in many important pathological and physiological settings. It has been shown that vascular permeability factor/vascular endothelial growth factor (VPF/VEGF), a potent cytokine expressed by most malignant tumors, has critical roles in vasculogenesis and both physiological and pathological angiogenesis. We report here that at non-toxic levels, the neurotransmitter dopamine strongly and selectively inhibited the vascular permeabilizing and angiogenic activities of VPF/VEGF. Dopamine acted through D2 dopamine receptors to induce endocytosis of VEGF receptor 2, which is critical for promoting angiogenesis, thereby preventing VPF/VEGF binding, receptor phosphorylation and subsequent signaling steps. The action of dopamine was specific for VPF/VEGF and did not affect other mediators of microvascular permeability or endothelial-cell proliferation or migration. These results reveal a new link between the nervous system and angiogenesis and indicate that dopamine and other D2 receptors, already in clinical use for other purposes, might have value in anti-angiogenesis therapy.

Heterogeneity of the cellular immune response. I. Kinetics of lymphocyte stimulation during sensitization and recovery from tolerance.

Lymph node cells from guinea pigs immunized with HSA in complete Freund's adjuvant were grown in cultures containing different concentrations of specific antigen. Stimulation of thymidine incorporation was induced with progressively lower concentrations of HSA at successive intervals after sensitization. Moreover, the intensity of delayed skin reactions and the magnitude of stimulation in vitro increased over the same interval. These events are considered compatible with an evolution of the cellular immune response resulting from the selection of lymphoid cells by decreasing concentrations of antigen in vivo. Cells from animals rendered tolerant to HSA failed to respond to specific antigen in culture. As tolerance waned, stimulation was achieved at high but not low antigen concentrations. Tolerance, measured by cutaneous reactivity or by lymphocyte stimulation, was less readily induced in animals sensitized with adjuvant containing a reduced concentration of mycobacteria. Lymph nodes from these animals contained a large population of cells reactive at high antigen concentration, presumably less susceptible to the toleragenic effect of intravenous antigen. The dissociation of delayed hypersensitivity and antibody formation observed early in the immune response and upon recovery from tolerance has permitted correlation of lymphocyte stimulation with delayed hypersensitivity and cutaneous basophil hypersensitivity respectively.

Rejection of first-set skin allografts in man. the microvasculature is the critical target of the immune response.

Recent reports of microvascular injury in delayed hypersensitivity skin reactions prompted us to reexamine the pathogenesis of first-set skin allograft rejection in man using morphologic techniques that allowed both extensive vessel sampling and unequivocal evaluation of microvascular endothelium. We here report that widespread microvascular damage is a characteristic, early consequence of the cellular immune response to first-set human skin allografts and is qualitatively similar to, but substantially more extensive than, that occurring in delayed hypersensitivity reactions. Microvascular damage in invariably preceded significant epithelial necrosis and affected initially and primarily those venules, arterioles, and small veins enveloped by lymphocytes. Vessels of both the allograft itself and the underlying graft bed (recipient tissue) were equally affected. These data suggest that endothelial cells of the microvasculature are the critical target of the immune response in first-set vascularized skin allograft rejection in man and that rejection can be attributed largely to ischemic infarction resulting from extensive microvascular damage. Other mechanisms, such as direct cellular contacts between infiltrating lymphocytes and epithelium, apparently played only a minor role. The findings presented here indicate that the rejection of first-set vascularized skin allografts, though induced by immunologically specific mechanisms, is primarily effected by final pathways that are relatively nonspecific and that may cause damage to both foreign and host vessels and cells. Rather than contradicting studies demonstrating the exquisite specificity of allograft rejection in other systems, these findings provide a further example of the heterogeneity of the cellular immune response. Recognition of the critical role of immunologically mediated microvascular injury may prove important both for an understanding of the biology of allograft rejection and for strategies aimed at prolonging allograft survival.

Distribution of vascular permeability factor (vascular endothelial growth factor) in tumors: concentration in tumor blood vessels.

Vascular permeability factor (VPF) is a highly conserved 34-42-kD protein secreted by many tumor cells. Among the most potent vascular permeability-enhancing factors known, VPF is also a selective vascular endothelial cell mitogen, and therefore has been called vascular endothelial cell growth factor (VEGF). Our goal was to define the cellular sites of VPF (VEGF) synthesis and accumulation in tumors in vivo. Immunohistochemical studies were performed on solid and ascites guinea pig line 1 and line 10 bile duct carcinomas using antibodies directed against peptides synthesized to represent the NH2-terminal and internal sequences of VPF. These antibodies stained tumor cells and, uniformly and most intensely, the endothelium of immediately adjacent blood vessels, both preexisting and those newly induced by tumor angiogenesis. A similar pattern of VPF staining was observed in autochthonous human lymphoma. In situ hybridization demonstrated VPF mRNA in nearly all line 10 tumor cells but not in tumor blood vessels, indicating that immunohistochemical labeling of tumor vessels with antibodies to VPF peptides reflects uptake of VPF, not endogenous synthesis. VPF protein staining was evident in adjacent preexisting venules and small veins as early as 5 h after tumor transplant and plateaued at maximally intense levels in newly induced tumor vessels by approximately 5 d. VPF-stained vessels were also hyperpermeable to macromolecules as judged by their capacity to accumulate circulating colloidal carbon. In contrast, vessels more than approximately 0.5 mm distant from tumors were not hyperpermeable and did not exhibit immunohistochemical staining for VPF. Vessel staining disappeared within 24-48 h of tumor rejection. These studies indicate that VPF is synthesized by tumor cells in vivo and accumulates in nearby blood vessels, its target of action. Because leaky tumor vessels initiate a cascade of events, which include plasma extravasation and which lead ultimately to angiogenesis and tumor stroma formation, VPF may have a pivotal role in promoting tumor growth. Also, VPF immunostaining provides a new marker for tumor blood vessels that may be exploitable for tumor imaging or therapy.

Expression and distribution of osteopontin in human tissues: widespread association with luminal epithelial surfaces.

Osteopontin, a glycoprotein with a glycine-arginine-glycine-aspartate-serine (GRGDS) cell-binding domain, has been described in bone and is also known to be expressed in other organs, particularly kidney. The goal of the present work was to define the distribution of osteopontin synthesis and deposition in a wide variety of normal adult human tissues using a multifaceted approach that included immunohistochemistry, in situ hybridization, and Northern analysis. Immunohistochemical studies have revealed the unexpected finding that osteopontin is deposited as a prominent layer at the luminal surfaces of specific populations of epithelial cells of the gastrointestinal tract, gall bladder, pancreas, urinary and reproductive tracts, lung, breast, salivary glands, and sweat glands. Northern analyses identified gallbladder as a major site of osteopontin gene transcription comparable in magnitude with that of kidney, and immunoblotting identified osteopontin in bile. In situ hybridization localized osteopontin gene transcripts predominantly to the epithelium of a variety of organs as well as to ganglion cells of bowel wall. Osteopontin of epithelial cell origin, like bone-derived osteopontin, promoted GRGDS-dependent cell spreading in attachment assays. We postulate that osteopontin secreted by epithelium binds integrins on luminal surfaces. Collectively, these findings suggest an important role for osteopontin on many luminal epithelial surfaces communicating with the external environment.

Pathogenesis of desmoplasia. I. Immunofluorescence identification and localization of some structural proteins of line 1 and line 10 guinea pig tumors and of healing wounds.

The structural proteins of the scirrhous line 1 and the medullary line 10 bile duct carcinomas, both syngeneic in strain 2 Sewall-Wright inbred guinea pigs, were studied. Tumor structural proteins were compared with those of healing wounds. A provisional stromal matrix of cross-linked fibrin and fibronectin was initially deposited in both tumors and wounds and was subsequently replaced by granulation tissue containing collagen types I and III. The amounts of stromal fibrin-fibronectin and collagen were characteristic of each tumor: Line 1 contained significantly greater amounts than line 10. These differences were augmented when line 1 tumor rejection was prevented with cyclosporine, permitting time for stromal maturation. In tumors and wounds laminin and collagen type IV were found only in basement membranes. The findings suggest that 1) tumor desmoplasia is analogous to wound healing, 2) both processes involve replacement of an antecedent fibrin-fibronectin provisional matrix, 3) the extent of fibrin-fibronectin is characteristic of each tumor, and 4) tumor desmoplasia correlates with the amount of fibrin-fibronectin matrix deposited.

Fibrin gel investment associated with line 1 and line 10 solid tumor growth, angiogenesis, and fibroplasia in guinea pigs. Role of cellular immunity, myofibroblasts, microvascular damage, and infarction in line 1 tumor regression.

Line 1 and line 10 tumors became invested in a fibrin-gel cocoon within hours after transplantation to the subcutaneous spaces of unsensitized syngeneic inbred Sewall Wright strain 2 guinea pigs. The fibrin gel comprised more than 80% of the line 1 tumor mass and, after day 3, became organized and was subsequently replaced by fibrous connective tissue, which gave the tumor the appearance of a scirrhous carcinoma. A cellular infiltrate of lymphocytes and basophils developed at the periphery of line 1 tumors after day 8, and tumors regressed by day 13. The fibrin gel investing the highly malignant line 10 tumors accounted for less than 10% of the tumor mass and persisted without fibrous organization as a tumor grew progressively and invaded adjacent tissues. These data provide new and potentially important insights into the biology of solid tumor growth and the mechanisms of immunologic tumor rejection. Envelopment of tumors in a fibrin gel created an anatomic barrier separating the tumors from the host. Neovascularization mimicking that about line 1 and line 10 tumors was induced by sc fibrin implants; these data suggest that activation of the clotting and/or fibrinolytic systems by tumor cells may itself provide sufficient stimulus for induction of tumor angiogenesis without requiring a separate tumor angiogenesis factor. The scirrhous pattern of growth characteristic of line 1 tumors apparently was achieved by organization of an abundant fibrin gel. Line 1 tumor regression did not for the most part involve direct contacts between tumor cells and any type of inflammatory cell, including macrophages; rather, tumor destruction was effected by ischemic necrosis secondary to widespread microvascular injury. The mechanisms of such injury are uncertain, but tumor rejection was correlated with evidence of developing cellular immunity and anatomic associations between lymphocytes and myofibroblasts. Further experiments will be necessary before these findings can be generalized to other tumor systems.

Human breast carcinoma: fibrin deposits and desmoplasia. Inflammatory cell type and distribution. Microvasculature and infarction.

Study of 14 human infiltrating breast carcinomas revealed new features that shed light on the pathogenesis of tumor stroma formation and on host immunologic defense mechanisms. Fibrin deposits were observed in the stroma of all tumors, particularly at their growing edge. Fibrin may have contributed both to tumor angiogenesis and, with organization, to the formation of the fibrous stroma characteristic of these and other scirrhous carcinomas. We previously proposed similar mechanisms for several animal tumors. All breast carcinomas studied elicited some degree of lymphocytic response at the tumor periphery; lymphocytes penetrated the fibrous tumor stroma poorly, did not exit in significant numbers from central tumor vessels, and, even when greatly outnumbering tumor cells locally, appeared relatively ineffective at tumor cell killing. Microvascular endothelial cell damage was frequently observed and may have been responsible for zones of tumor infarction. Similar observations have been made in skin allografts and animal tumors where rejection was effected principally by microvascular damage and subsequent tissue infarction, not by lymphocyte contact with individual epithelial target cells.

Vascular permeability factor/vascular endothelial growth factor-mediated signaling in mouse mesentery vascular endothelium.

Vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) is a multifunctional cytokine and growth factor that has important roles in both pathological and physiological angiogenesis. VPF/VEGF induces vascular hyperpermeability, cell division, and other activities by interacting with two specific receptor tyrosine kinases, KDR/Flk-1 and Flt-1, that are selectively expressed on vascular endothelium. The signaling cascade that follows VPF/VEGF interaction with cultured endothelium is only partially understood but is known to result in increased intracellular calcium, activation of protein kinase C, and tyrosine phosphorylations of both receptors, phospholipase C-gamma (PLC-gamma) and phosphatidylinositol 3'-kinase. For many reasons, signaling events elicited in cultured endothelium may not mimic mediator effects on intact normal or tumor-induced microvessels in vivo. Therefore, we developed a system that would allow measurement of VPF/VEGF-induced signaling on intact microvessels. We used mouse mesentery, a tissue whose numerous microvessels are highly responsive to VPF/VEGF and that we found to express Flk-1 and Flt-1 selectively. At intervals after injecting VPF/VEGF i.p., mesenteries were harvested, extracted, and immunoprecipitated. Immunoblots confirmed that VPF/VEGF induced tyrosine phosphorylation of several proteins in mesenteric microvessels as in cultured endothelium: Flk-1; PLC-gamma; and mitogen-activated protein kinase. Similar phosphorylations were observed when mesentery was exposed to VPF/VEGF in vitro, or when mesenteries were harvested from mice bearing the mouse ovarian tumor ascites tumor, which itself secretes abundant VPF/VEGF. Other experiments further elucidated the VPF/VEGF signaling pathway, demonstrating phosphorylation of both PYK2 and focal adhesion kinase, activation of c-jun-NH2-kinase with phosphorylation of c-Jun, and an association between Flk-1 and PLC-gamma. In addition, we demonstrated translocation of mitogen-activated protein kinase to the cell nucleus in cultured endothelium. Taken together, these experiments describe a new model system with the potential for investigating signaling events in response to diverse mediators on intact microvessels in vivo and have further elucidated the VPF/VEGF signaling cascade.

Expression of vascular permeability factor/vascular endothelial growth factor by melanoma cells increases tumor growth, angiogenesis, and experimental metastasis.

Vascular permeability factor (VPF)/vascular endothelial growth factor (VEGF) is an angiogenic cytokine expressed by many human and animal tumors. Hypoxia often up-regulates VPF/VEGF expression further. To better define the role of VPF/VEGF in tumor biology, we screened tumorigenic lines for those expressing minimal constitutive and hypoxia-inducible VPF/VEGF. Human melanoma SK-MEL-2 cells best fit these criteria and formed small, poorly vascularized tumors in immunodeficient mice. We transfected SK-MEL-2 cells stably with sense or antisense mouse VPF/VEGF cDNA or with vector alone. Cells transfected with sense VPF/VEGF (V+) expressed and secreted large amounts of mouse VPF/VEGF and formed well-vascularized tumors with hyperpermeable blood vessels and minimal necrosis in nude/SCID mice. Antisense-transfected VPF/VEGF (V-) cells expressed reduced constitutive VPF/VEGF and no detectable mouse VPF/VEGF, and formed small, minimally vascularized tumors exhibiting extensive necrosis. Vector-alone transfectants (N1 cells) behaved like parental cells. V+ cells formed numerous lung tumor colonies in SCID mice, approximately 50-fold more than N1 cells, whereas V- cells formed few or none. These experiments demonstrate that VPF/VEGF promotes melanoma growth by stimulating angiogenesis and that constitutive VPF/VEGF expression dramatically promotes tumor colonization in the lung.

Expression of vascular permeability factor (vascular endothelial growth factor) and its receptors in adenocarcinomas of the gastrointestinal tract.

Vascular permeability factor (VPF) is one of the most potent known inducers of microvascular hyperpermeability; in addition, it is a selective endothelial cell growth factor, hence its alternate name, vascular endothelial growth factor. VPF exerts its actions on the microvasculature by interacting with specific endothelial cell receptors. VPF is expressed by many transplantable animal tumors, by tumor cell lines in culture, and by certain normal cells in situ. The purpose of the present investigation was to determine whether and with what consistency VPF and its endothelial cell receptors are expressed in primary autochthonous human tumor of gastrointestinal tract origin, as determined by in situ hybridization and immunohistochemistry. Twenty-one primary adenocarcinomas (17 colon, 2 stomach, 1 small bowel, and 1 pancreas) were studied. The malignant epithelial cells expressed VPF mRNA strongly, in contrast to normal epithelium, hyperplastic polyps, and adenomas, which expressed little or no VPF mRNA. VPF expression was further increased in tumor cells immediately adjacent to zones of tumor necrosis; in such areas, occasional stromal cells also expressed VPF mRNA. In the ten colon carcinomas studied, tumor cells stained for VPF protein by immunohistochemistry. The endothelial cells of nearby stromal blood vessels also stained for VPF by immunohistochemistry and in addition expressed mRNAs encoding the VPF receptors flt-1 and kdr as determined by in situ hybridization. Endothelial cells away from the tumor did not stain for VPF and no definite mRNA expression for flt-1 or kdr was detected by in situ hybridization. The ganglion cells of the myenteric plexus of normal bowel expressed VPF mRNA and protein. These data indicate that primary autochthonous human tumors of gastrointestinal origin regularly express both VPF mRNA and VPF protein and that adjacent stromal vessels express mRNAs for both known VPF receptors. VPF is likely to contribute to tumor growth by promoting angiogenesis and stroma formation, both directly, through its action as an endothelial cell growth factor, and indirectly, by increasing vascular permeability, thereby leading to plasma protein extravasation, fibrin deposition, and the eventual replacement of the resulting matrix with vascularized stroma.

Pathogenesis of ascites tumor growth: angiogenesis, vascular remodeling, and stroma formation in the peritoneal lining.

In the accompanying papers, we demonstrated that two murine ascites tumors (MOT and TA3/St) induced peritoneal lining blood vessels to become hyperpermeable to plasma proteins, leading to extravasation of fibrinogen and its clotting to cross-linked fibrin in peritoneal lining tissues (peritoneal wall, mesentery, and diaphragm). In solid tumors, vascular hyperpermeability and fibrin deposition lead to the generation of vascularized connective tissue. In order to determine whether fibrin had similar consequences in ascites tumors, the vasculature and stroma of peritoneal lining tissues were analyzed at successive intervals after i.p. tumor cell injection. In both MOT and TA3/St ascites tumors, the size and number of peritoneal lining microvessels increased significantly by 5-8 days. Subsequently, peritoneal lining vessels increased in cross-sectional area by as much as 15-fold and peritoneal vascular frequency increased by up to 11-fold. Incorporation of [3H]thymidine by mesenteric blood vessels was negligible in control animals but came to involve 20 and 40% of endothelial cells lining mesenteric vessels in MOT and TA3/St ascites tumor-bearing mice, respectively. After an early dramatic increase in cross-sectional area, peritoneal lining microvessels subsequently underwent a novel form of remodeling to smaller average size as the result of transvascular bridging by endothelial cell cytoplasmic processes. Thus, both of the ascites tumors studied here induced angiogenesis and stroma similar to that elicited when these same tumors were grown in solid form. However, stroma developed more slowly in ascites than in solid tumors and was entirely confined to a compartment (peritoneal lining tissues) that was distinct from that (peritoneal cavity) containing the majority of tumor cells and ascites fluid. These findings are consistent with the hypothesis that vascular hyperpermeability, induced in both solid and ascites tumors by tumor cell-secreted vascular permeability factor, is a common early step in tumor angiogenesis, resulting in fibrinogen extravasation, fibrin deposition, and likely other alterations of the extracellular matrix that together stimulate new vessel and fibroblast ingrowth.

Ultrastructural localization of the vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) receptor-2 (FLK-1, KDR) in normal mouse kidney and in the hyperpermeable vessels induced by VPF/VEGF-expressing tumors and adenoviral vectors.

Vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) interacts with two high-affinity tyrosine kinase receptors, VEGFR-1 and VEGFR-2, to increase microvascular permeability and induce angiogenesis. Both receptors are selectively expressed by vascular endothelial cells and are strikingly increased in tumor vessels. We used a specific antibody to localize VEGFR-2 (FLK-1, KDR) in microvascular endothelium of normal mouse kidneys and in the microvessels induced by the TA3/St mammary tumor or by infection with an adenoviral vector engineered to express VPF/VEGF. A pre-embedding method was employed at the light and electron microscopic levels using either nanogold or peroxidase as reporters. Equivalent staining was observed on both the luminal and abluminal surfaces of tumor- and adenovirus-induced vascular endothelium, but plasma membranes at interendothelial junctions were spared except at sites connected to vesiculovacuolar organelles (VVOs). VEGFR-2 was also localized to the membranes and stomatal diaphragms of some VVOs. This staining distribution is consistent with a model in which VPF/VEGF increases microvascular permeability by opening VVOs to allow the transendothelial cell passage of plasma and plasma proteins.

Osteopontin is strongly expressed by histiocytes in granulomas of diverse etiology.

Granulomatous inflammation is associated with a variety of important pathologic conditions. Osteopontin (OPN), a ligand for the alpha v beta 3 integrin, is a secreted glycoprotein with a glycine-arginine-glycine-aspartate-serine cell-binding domain. In this study, we examined expression of OPN in 22 cases of granulomatous inflammation including cases of sarcoidosis, granulomatous temporal arteritis, histoplasmosis, rheumatoid nodule, granuloma annulare, erythema nodosum, granulomatous gastritis, foreign body giant-cell granulomatous reactions, and lipogranulomas. Strong expression of OPN mRNA and protein was seen in the epithelioid histiocytes and multinucleate histiocytic giant cells in granulomas by in situ hybridization and immunostaining. OPN may play an important role in granulomatous inflammation through the regulation of processes such as histiocyte migration, cell adhesion, and cellular functions including phagocytosis.

Expression of vascular permeability factor (VPF/VEGF) is altered in many glomerular diseases.

Vascular permeability factor (VPF), also known as vascular endothelial growth factor (VEGF), is a potent enhancer of microvascular permeability and a selective endothelial cell growth factor. In normal human kidney, VPF/VEGF mRNA and protein are strongly expressed by visceral glomerular epithelial cells, and VPF/VEGF may be an important regulator of glomerular endothelial cell function. This study examined 47 renal biopsies from patients with a variety of glomerular diseases for expression of VPF/VEGF mRNA and protein by in situ hybridization and immunohisto-chemistry. In many glomerular diseases, VPF/VEGF-expressing cells were decreased in number or absent in areas of focal or global glomerular sclerosis. Decreased numbers of VPF/VEGF-expressing cells in glomeruli were also noted in amyloidosis, diabetes, crescentic glomerulonephritis, and diffuse endocapillary proliferative glomerulonephritis associated with systemic lupus erythematosus. Normally, release of VPF/ VEGF must be under strict control because it is some 50,000 times more potent than histamine as an inducer of microvascular permeability. Damage to visceral epithelial cells in a variety of glomerular diseases has the potential for releasing relatively large amounts of VPF/VEGF locally, leading to increased glomerular permeability. In addition, because VPF/ VEGF is also an endothelial growth factor, the loss of normal, controlled secretion of VPF/VEGF after damage to visceral epithelial cells could lead to important alterations in glomerular endothelial cell function.

Systemic expression of cutaneous basophil hypersensitivity.

Guinea pigs primed for cutaneous basophil hypersensitivity (CBH) with several soluble proteins or with sheep erythrocytes developed a systemic, delayed-onset, maculopapular rash when challenged parenterally with specific antigen. The rash was most readily induced 5 to 7 days after immunization, at a time when local CBH skin test reactivity was also optimal. Miscroscopically, the rash resembled local CBH skin test reactions, being comprised of a papillary dermal infiltrate of basophils and lymphocytes and a striking dilatation and compaction of superficial venules. In addition to the systemic rash, animals expressing systemic CBH (SCBH) exhibited a striking eosinophilia at 24 hr which gave way to basophilia at 48 hr. Focal collections of eosinophils, and of smaller numbers of basophils, were found in the lungs and spleen; both eosinophils and basophils infiltrated the medulla of the thymus. Thus, basophil-rich infiltrations are favored in the skin even after systemic challenge with antigen and occur only to a much smaller extent in other organs where eosinophils may predominate. These differences in the response of various organs to challenge with parenteral antigen suggest that as yet unidentified local factors play a determinative role in regulating the inflammatory response. The pathogenesis of SCBH is not yet established, but it shares many of the properties of local CBH: histology, carrier specificity, development early after sensitization in the absence of detectable antibodies. Passive transfer has not been accomplished with serum alone but has been achieved irregularly with cells plus serum. SCBH may serve as a useful model for several disease states in man characterized by a systemic rash and eosinophilia, including certain types of drug reaction.

Expression of vascular permeability factor/vascular endothelial growth factor by human granulosa and theca lutein cells. Role in corpus luteum development.

Vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) is a cytokine that is overexpressed in many tumors, in healing wounds, and in rheumatoid arthritis. VPF/VEGF is thought to induce angiogenesis and accompanying connective tissue stroma in two ways: 1), by increasing microvascular permeability, thereby modifying the extracellular matrix and 2), as an endothelial cell mitogen. VPF/VEGF has been reported in animal corpora lutea and we investigated the possibility that it might be present in human ovaries and have a role in corpus luteum formation. We here report that VPF/VEGF mRNA and protein are expressed by human ovarian granulosa and theca cells late in follicle development and, subsequent to ovulation, by granulosa and theca lutein cells. Therefore, VPF/VEGF is ideally positioned to provoke the increased permeability of thecal blood vessels that occurs shortly before ovulation. VPF/VEGF likely also contributes to the angiogenesis and connective tissue stroma generation that accompany corpus luteum/corpus albicans formation. Finally, VPF/VEGF was overexpressed in the hyperthecotic ovarian stroma of Stein-Leventhal syndrome in which it may also have a pathophysiological role.

Osteopontin expression and distribution in human carcinomas.

Osteopontin (OPN), a secreted adhesive glycoprotein, is significantly overexpressed in a variety of experimental models of malignancy. Moreover, increased levels of OPN have been detected in the blood of patients with metastatic carcinoma. To investigate OPN expression and distribution in human carcinomas directly, we studied a wide variety of common tumors by Northern analysis, in situ hybridization, and immunohistochemistry. All 14 tumors studied by Northern analysis showed very substantial increases in OPN messenger (m)RNA when compared to corresponding normal tissues. Moreover, intense labeling for OPN mRNA was detected in 71 of 76 carcinomas studied by in situ hybridization. In most of the carcinomas studied (colon, stomach, duodenum, pancreas, breast, lung, bladder, prostate, ovary, thyroid, and melanoma), tumor cells did not label detectably for OPN mRNA; however, macrophages intimately associated with tumor cells labeled strongly for the OPN transcript. In carcinomas of the kidney and endometrium, both tumor cells and host macrophages labeled strongly for OPN mRNA. The presence of OPN mRNA in macrophages was particularly pronounced at the edge of tumors (ie, the tumor/stroma interface) and in areas of tumor necrosis. Although in most cases tumor cells did not label detectably for OPN mRNA, both tumor cells and macrophages stained for OPN protein, suggesting that OPN secreted by macrophages may bind to tumor cells, possibly through the glycine-arginine-glycine-aspartate-serine cell binding domain in OPN. Collectively, these data suggest that OPN functions in adhesive interactions at the tumor/host interface and thereby may influence processes such as invasion and metastasis.

Increased expression of vascular permeability factor (vascular endothelial growth factor) and its receptors in kidney and bladder carcinomas.

Vascular permeability factor (VPF), also known as vascular endothelial growth factor, is a secreted protein implicated in tumor-associated microvascular hyperpermeability and angiogenesis. Tumor cells in 11 of 12 renal cell carcinomas expressed high levels of VPF messenger RNA (mRNA) by in situ hybridization, the only exception being a case of the relatively avascular papillary variant. Expression was further accentuated adjacent to areas of necrosis. Both tumor cells and endothelial cells in small vessels adjacent to tumor stained strongly for VPF protein by immunohistochemistry. Endothelial cells did not express detectable VPF mRNA, but did express high levels of mRNA for the VPF receptors flt-1 and KDR indicating that the endothelial cell staining likely reflects binding of VPF secreted by adjacent tumor cells. Three transitional cell carcinomas also labeled strongly for VPF mRNA. These data suggest an important role for VPF in the vascular biology of these two common human malignancies.

Vascular permeability factor mRNA and protein expression in human kidney.

Vascular permeability factor (VPF), also known as vascular endothelial growth factor (VEGF), is a potent microvascular permeability-enhancing mediator as well as a selective mitogen for vascular endothelium. In this study, in situ hybridization and immunohistochemistry co-localized VPF mRNA and protein to glomerular visceral epithelial cells in human kidneys. Northern analysis confirmed the presence of VPF mRNA of expected size. The finding of VPF in renal glomerular epithelium identifies a potent mediator of permeability and endothelial proliferation whose role in renal physiology and pathology requires investigation.