Primary structure of the brain alpha-spectrin.

We have determined the nucleotide sequence coding for the chicken brain alpha-spectrin. It is derived both from the cDNA and genomic sequences, comprises the entire coding frame, 5' and 3' untranslated sequences, and terminates in the poly(A)-tail. The deduced amino acid sequence was used to map the domain structure of the protein. The alpha-chain of brain spectrin contains 22 segments of which 20 correspond to the repeat of the human erythrocyte spectrin (Speicher, D. W., and V. T. Marchesi. 1984. Nature (Lond.). 311:177-180.), typically made of 106 residues. These homologous segments probably account for the flexible, rod-like structure of spectrin. Secondary structure prediction suggests predominantly alpha-helical structure for the entire chain. Parts of the primary structure are excluded from the repetitive pattern and they reside in the middle part of the sequence and in its COOH terminus. Search for homology in other proteins showed the presence of the following distinct structures in these nonrepetitive regions: (a) the COOH-terminal part of the molecule that shows homology with alpha-actinin, (b) two typical EF-hand (i.e., Ca2+-binding) structures in this region, (c) a sequence close to the EF-hand that fulfills the criteria for a calmodulin-binding site, and (d) a domain in the middle of the sequence that is homologous to a NH2-terminal segment of several src-tyrosine kinases and to a domain of phospholipase C. These regions are good candidates to carry some established as well as some yet unestablished functions of spectrin. Comparative analysis showed that alpha-spectrin is well conserved across the species boundaries from Xenopus to man, and that the human erythrocyte alpha-spectrin is divergent from the other spectrins.

Kaposi's sarcoma-associated herpesvirus-encoded v-cyclin triggers apoptosis in cells with high levels of cyclin-dependent kinase 6.

Kaposi's sarcoma-associated herpesvirus (KSHV) has a key etiological role in development of Kaposi's sarcoma (KS). v-Cyclin is a KSHV-encoded homologue to D-type cyclins that associates with cellular cyclin-dependent kinase 6 (CDK6). v-Cyclin promotes S-phase entry of quiescent cells and has been suggested to execute functions of both D- and E-type cyclins. In this study, expression of v-cyclin in cells with elevated levels of CDK6 led to apoptotic cell death after the cells entered S phase. The cell death required the kinase activity of CDK6 because cells expressing a kinase-deficient form of CDK6 did not undergo apoptosis upon v-cyclin expression. Studies on the mechanisms involved in this caspase-3-mediated apoptosis indicated that it was independent of cellular p53 or pRb status, and it was not suppressed by Bcl-2. In contrast, the KSHV-encoded v-Bcl-2 efficiently suppressed v-cyclin-/CDK6-induced apoptosis, demonstrating a marked difference in the antiapoptotic properties of c-Bcl-2 and v-Bcl-2. In KS lesions, high CDK6 expression was confined to a subset of cells, some of which displayed signs of apoptosis. These results suggest that v-cyclin may exert both growth-promoting and apoptotic functions in KS, depending on factors regulating CDK6 and v-Bcl-2 levels.

Lymphatic endothelium and Kaposi's sarcoma spindle cells detected by antibodies against the vascular endothelial growth factor receptor-3.

Lymphatic vessels have been difficult to study in detail in normal and tumor tissues because of the lack of molecular markers. Here, monoclonal antibodies against the extracellular domain of the vascular endothelial growth factor-C receptor that we have named VEGFR-3 were found to specifically stain endothelial cells of lymphatic vessels and vessels around tumors such as lymphoma and in situ breast carcinoma. Interestingly, the spindle cells of several cutaneous nodular AIDS-associated Kaposi's sarcomas and the endothelium around the nodules were also VEGFR-3 positive. The first specific molecular marker for the lymphatic endothelium should provide a useful tool for the analysis of lymphatic vessels in malignant tumors and their metastases and the cellular origin and differentiation of Kaposi's sarcomas.

Leukocytes and platelets of patients with cancer contain high levels of vascular endothelial growth factor.

Vascular endothelial growth factor (VEGF) is a secreted endothelial cell-specific mitogen and permeability factor. Malignant human tumors have been shown to produce VEGF. Elevated levels of VEGF have been detected in sera of cancer patients, but its origin is unsettled. We analyzed VEGF concentrations in serum, plasma, whole blood, and peripheral blood mononuclear cells (PBMNCs) and platelets in 56 cancer patients and 52 healthy controls using ELISA. The VEGF concentrations in the lysed whole blood samples [blood VEGF (B-VEGF)] were higher in cancer patients than in healthy controls (median, 464 versus 298 pg/ml; P<0.0001). The highest B-VEGF values were found in disseminated cancer. In cancer patients, a high B-VEGF concentration was associated with a high peripheral blood leukocyte count (P = 0.0012) and platelet count (P = 0.019). In healthy individuals, a high B-VEGF was associated with a high leukocyte count (P = 0.0001) but not with the platelet count (P>0.1). The cancer patients regularly had higher B-VEGF concentrations than healthy individuals with comparable leukocyte or platelet counts. The VEGF content of isolated PBMNCs and platelets was severalfold higher in cancer patients than in healthy controls (median, 10.6 versus 0.9 pg per 10(6) PBMNCs, and median, 1.6 versus 0.5 pg per 10(6) platelets; P<0.0001 and P = 0.0008, respectively). Serum VEGF and B-VEGF correlated strongly (P<0.0001). Very little or no VEGF was found in the plasma. The results indicate that VEGF in the bloodstream is transported by blood cells, including leukocytes and platelets. The blood cells of cancer patients contain greatly elevated amounts of this major angiogenic growth factor, and this reservoir of VEGF may have a role in tumor angiogenesis and metastasis formation. VEGF in serum samples originates from blood cells, and the use of VEGF of whole blood or of isolated blood cells may improve the clinical value of VEGF measurements.

Serum vascular endothelial growth factor is often elevated in disseminated cancer.

In adults, marked angiogenesis takes place only during the female reproductive cycles, during wound healing, and accompanying some disease processes, such as tumor development. Vascular endothelial growth factor (VEGF) is a secreted, endothelial cell-specific growth factor, which is induced by tissue hypoxia and is angiogenic in vivo. We measured serum VEGF (S-VEGF) concentrations by ELISA in patients with a variety of types of cancer, as well as in healthy volunteers, and in patients with diabetes or rheumatoid arthritis. Elevated S-VEGF concentrations were found in patients with locoregional (n = 39; median, 158 pg/ml; range, 8-664 pg/ml) or disseminated (n = 58; median, 214 pg/ml; range, 17-1711 pg/ml) cancer in comparison to individuals without cancer (n = 113; median, 17 pg/ml; range, 1-177 pg/ml; P < 0.0001 for both comparisons). Values higher than 200 pg/ml were observed in 74% of patients with untreated metastatic cancer, and high serum levels were measured regardless of the histological type of cancer. S-VEGF levels were found to be higher in untreated patients with disseminated cancer than in those with local cancer (P = 0.006), and patients undergoing cancer therapy had lower values than those without cancer therapy (P = 0.03). The results indicate that both patients with locoregional cancer and patients with disseminated cancer may have elevated S-VEGF levels, regardless of the histological type of cancer, and that S-VEGF is often elevated in cancer with distant metastases.

Interferon alpha-2a therapy in 18 hemangioblastomas.

Multiple hemangioblastomas (HBs) of the central nervous system (CNS) and retina are associated with von Hippel-Lindau disease (VHL) and also predispose individuals to renal cell carcinomas and visceral cysts. In VHL, microsurgery or radiosurgery cannot prevent new HBs from arising in the CNS or coagulation of retinal HBs. Multiple but thus far asymptomatic HBs pose a therapeutic problem. IFN-alpha-2a has antiangiogenic activity with an especially favorable effect on life-threatening hemangiomas of the liver in children. This is the first study to assess the efficacy of IFN-alpha-2a in treatment of asymptomatic HBs of the CNS and retina. Four patients (three with VHL) with a combined total of 15 HBs of the CNS, 3 HBs of the retina, and 14 renal and 2 pancreatic cysts were treated with s.c. IFN-alpha-2a for 12 months at 3 x 10(6) IU, 3 times/week. Baseline workup consisted of detailed neurological, ophthalmological, and radiological examinations. Follow-up studies at 3, 13, and 21 months were used to monitor the response. No de novo HBs were detected during the therapy, but one appeared 9 months after cessation of IFN-alpha-2a therapy. HBs of the CNS did not shrink markedly during the therapy. IFN-alpha-2a may decrease blood flow in HBs as suggested by shrinkage and diminished leakage of two retinal HBs. However, the therapy did not prevent visceral cysts from growing. The systemic response was also monitored by measurement of serum levels of vascular endothelial growth factor and erythropoietin, which remained essentially unchanged during the treatment. No serious side effects were recorded.

Peripheral blood platelets express VEGF-C and VEGF which are released during platelet activation.

VEGF-C is a recently characterised endothelial growth factor structurally related to vascular endothelial growth factor (VEGF). We studied the expression of VEGF-C and VEGF in the cells of peripheral blood and in the umbilical cord blood CD 34+ cells, representing haematopoietic progenitor cells. Expression of VEGF-C was detected in the CD34+ cells. In peripheral blood VEGF-C mRNA was restricted to platelets and T-cells. In contrast to the expression pattern of VEGF-C, VEGF mRNA was detected in all peripheral blood cell fractions studied, and also in CD34+ cells. VEGF-C mRNA was also detected in fresh bone marrow samples of acute leukaemia patients, but the expression did not show lineage specificity. VEGF-C and VEGF polypeptides were present in platelets and they were released from activated platelets together with the release of beta-thromboglobulin, suggesting that VEGF-C and VEGF reside in the alpha-granules of platelets. VEGF-C and VEGF, released from activated platelets, may have a role in angiogenesis during wound healing, and possibly also in other pathological conditions, such as atherosclerosis, tumour growth, and metastasis formation.

Major surgery increases serum levels of vascular endothelial growth factor only temporarily.

BACKGROUND: Vascular endothelial growth factor (VEGF) is a hypoxia-induced endothelial cell-specific mitogen, which is angiogenic in vivo and up-regulated in several malignancies. VEGF can be used as a prognostic marker, but the effect of surgical trauma on serum VEGF (S-VEGF) concentrations is unknown and might reduce the value of VEGF as a serum marker. METHODS: We monitored S-VEGF levels by enzyme-linked immunosorbent assay in patients undergoing surgery. RESULTS: Eighteen patients with major surgery had slightly elevated S-VEGF compared with the preoperative level (median 9.5 pg/mL) on the first (median 35 pg/mL; P = 0.0002) and third (median 19 pg/mL; P = 0.004) postoperative day, but not in later samples. The levels measured in 8 patients after minor surgery did not differ from the preoperative levels (P = 0.14). CONCLUSIONS: Even major surgery is associated only with a slight and transient increase in S-VEGF levels, and, therefore, is unlikely to interfere markedly with the use of VEGF as a prognostic marker.

Angiogenesis in lymphoproliferative disorders.

In this review, the cellular and molecular mechanisms underlying angiogenesis in lymphoproliferative disorders are summarized, alongside with possible therapeutic applications. Although most of the initial studies in angiogenesis were done on solid tumors, recent data demonstrate the importance of angiogenesis in hematological malignancies including leukemia, lymphoma, and multiple myeloma. Expression of angiogenic polypeptides vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) correlate with clinical characteristics in leukemia and lymphoma, and their serum concentrations serve as predictors of poor prognosis. Antiangiogenic drugs, including thalidomide, arsenic trioxide, endostatin, vasostatin, and neutralizing antibodies to VEGF receptors, used alone or in combination with established chemo- or immunotherapy regimens, constitute a promising approach for the treatment of lymphoproliferative disorders.

A high pretreatment serum basic fibroblast growth factor concentration is an independent predictor of poor prognosis in non-Hodgkin's lymphoma.

Basic fibroblast growth factor (bFGF) is a secreted multifunctional cytokine and a potent stimulator of angiogenesis in vivo. Elevated bFGF concentrations have been detected in the serum and urine of cancer patients. We measured bFGF by enzyme-linked immunosorbent assay from sera taken from 160 non-Hodgkin's lymphoma (NHL) patients before treatment and stored at -20 degrees C. The patients had been observed for at least 5 years or until death. Serum bFGF concentrations (S-bFGF) ranged from undetectable to 34.7 pg/mL (median, 3.3 pg/mL). S-bFGF was detectable with a similar frequency in all subtypes of NHL. A high pretreatment S-bFGF was associated with poor overall survival. The 5-year survival rate of the patients within the highest quartile of S-bFGF concentrations (S-bFGF = 5.5 pg/mL) was only 39%, in contrast to a 60% survival rate of the patients with lower S-bFGF (P =.019). A high S-bFGF (within the highest quartile) was associated with poor outcome also in large-cell diffuse and immunoblastic lymphomas (5-year survival rates of 28% v 56%, respectively; P =.027), which was the largest histologic subgroup (n = 66) within the series. In multivariate analyses, S-bFGF was an independent prognostic factor, both when the highest quartile was used as a cut-off value (P =.0079) and when S-bFGF and the other parameters were entered into the model as continuous variables (P =.024). In the multivariate analyses, S-bFGF had a noticeably stronger prognostic value than serum lactate dehydrogenase and the number of extranodal tumor sites, both of which are currently included as components in the International Prognostic Index.

Enhanced expression of vascular endothelial growth factor in metastatic melanoma.

Tumour growth is dependent on angiogenesis. Vascular endothelial growth factor (VEGF) is a secreted endothelial cell-specific cytokine. VEGF is angiogenic in vivo and it also acts as a vascular permeability factor. VEGF is overexpressed in many skin disorders characterized by angiogenesis and increased vascular permeability. We investigated VEGF expression in 22 primary cutaneous melanomas, 33 melanoma metastases and six naevocellular naevi using immunohistochemistry. VEGF accumulated on the vascular endothelia in the normal dermis, suggesting that a constitutive low level of VEGF expression may regulate skin vessel function under normal physiological conditions. No VEGF was detected in the cells of naevocellular naevi or normal dermis. In contrast, 32% of the primary and 91% of the metastatic melanomas contained melanoma cells staining for VEGF. Expression of VEGF was more frequent in metastases than in primary melanomas (P <0.0001). Tumour-infiltrating inflammatory cells expressed VEGF in all melanomas. A high number of VEGF-expressing inflammatory cells was associated with high VEGF expression in melanoma cells (P = 0.003). Our results suggest that VEGF is up-regulated during the course of melanoma progression and dissemination and that tumour-infiltrating cells expressing VEGF may contribute to the progression of melanoma.

A high pretreatment serum vascular endothelial growth factor concentration is associated with poor outcome in non-Hodgkin's lymphoma.

Vascular endothelial growth factor (VEGF) is a secreted endothelial cell-specific mitogen, which is induced by hypoxia and is angiogenic in vivo. Recently, elevated serum concentrations of VEGF (S-VEGF) have been reported in patients with cancers of various histologies. However, the prognostic significance of S-VEGF in human cancer is unknown and the origin of S-VEGF remains unsettled. We measured S-VEGF by enzyme-linked immunosorbent assay from sera taken from 82 patients with non-Hodgkin's lymphoma before treatment and stored for 9 to 15 years at -20 degrees C. All but one of the patients had been followed-up for at least 5 years or until death. S-VEGF ranged from 15 to 964 pg/mL; median, 228 pg/mL; mean, 291 pg/mL. A higher than the median S-VEGF level was associated with a poor World Health Organization performance status, a high International Prognostic Index, a high serum lactate dehydrogenase level, and a large cell histology. Patients with lower than the median S-VEGF at diagnosis had a 71% 5-year survival rate in comparison with only 49% among those with a higher than the median S-VEGF. We conclude that a high pretreatment S-VEGF level is associated with poor outcome in non-Hodgkin's lymphoma.

Simultaneous elevation in the serum concentrations of the angiogenic growth factors VEGF and bFGF is an independent predictor of poor prognosis in non-Hodgkin lymphoma: a single-institution study of 200 patients.

High serum concentrations of vascular endothelial growth factor (S-VEGF) and basic fibroblast growth factor (S-bFGF) are associated with unfavorable clinical characteristics in cancer. The combined effect of S-VEGF and S-bFGF on the survival of 200 patients with non-Hodgkin lymphoma (NHL) was studied. High S-VEGF and S-bFGF at diagnosis were associated with poor survival with the medians, the highest tertiles, or the highest quartiles as the cutoff values. The highest prognostic power was obtained when S-VEGF and S-bFGF were examined as a combination. Patients who had both S-VEGF and S-bFGF within the highest quartiles had only a 21% 5-year survival rate in contrast to a 64% 5-year survival rate among patients with both factors within the 3 lowest quartiles (P <.0001). Simultaneous elevation of S-VEGF and S-bFGF was associated with poor survival in different grades of lymphomas and in the largest histologic subgroup, the large-cell diffuse and immunoblastic lymphomas. S-VEGF (relative risk [RR], 1.83; P =.019) and S-bFGF (RR, 2.02; P =.0049) had independent influences on survival in multivariate models when tested together with the components of the International Prognostic Index (IPI). Patients with both S-VEGF and S-bFGF within the highest quartiles had nearly 3 times higher risk for death (RR, 2.90; 95% confidence interval [CI], 1.56-5.40; P =.0008) than the rest of the patients. This RR was higher than the relative risks associated with any of the components of the IPI in the same model. The authors conclude that the combination of S-VEGF and S-bFGF is a powerful prognostic variable in NHL. (Blood. 2000;96:3712-3718)

Sedative action of the alpha 2-agonist medetomidine in cats.

Medetomidine, a novel alpha 2-agonist drug intended for small animal sedation, was injected intramuscularly at dose rates of 0.02, 0.06 and 0.18 mg/kg. Xylazine (3.0 mg/kg) and saline were used for comparison. The five treatments were tested in a Latin square design in five cats. Treatments differed significantly in three-way analysis of variance, medetomidine inducing an increase in drowsiness with a corresponding decrease in both aroused waking and sleep determined by polygraphical criteria. The duration of effect was dose-dependent. The effect of 0.18 mg/kg medetomidine was comparable to 3.0 mg/kg of xylazine. The drugs also induced bradycardia.

High pre-treatment serum level of vascular endothelial growth factor (VEGF) is associated with poor outcome in small-cell lung cancer.

Vascular endothelial growth factor (VEGF) is an important regulator of angiogenesis and vascular permeability. Increased serum VEGF concentrations (S-VEGF) have been found in patients with various types of human cancer, including cancer of the lung. However, the clinical and prognostic significance of S-VEGF in cancer is unknown. We measured S-VEGF, using enzyme-linked immunosorbent assay, in sera taken from 68 untreated patients with small-cell lung cancer (SCLC) at the time of diagnosis. The patients were treated with 6 cycles of cisplatin and etoposide, and were randomly assigned to receive recombinant interferon, leukocyte interferon or neither. S-VEGF ranged from 70 to 1738 pg/ml (mean, 527 pg/ml). The patients who achieved partial or complete response to treatment had lower pre-treatment S-VEGF than the non-responding patients (p = 0.0083, Mann-Whitney test). High (>527 pg/ml) S-VEGF was associated with poor survival (p = 0.012, Log Rank Test), and all 3-year survivors had lower than mean pre-treatment S-VEGF. In a multivariate analysis, S-VEGF and stage were the only independent prognostic factors, and the estimated 3-year survival of the patients with limited stage disease and low pretreatment S-VEGF (n = 17, 25% of all patients) was 41% (p = 0.0055, log rank test). These data show that high pretreatment S-VEGF is associated with poor response to treatment and unfavourable survival in patients with SCLC treated with combination chemotherapy with or without interferon.

Vascular endothelial growth factor in squamous cell head and neck carcinoma: expression and prognostic significance.

The growth of solid tumors is dependent on angiogenesis, the formation of new blood vessels. Vascular endothelial growth factor (VEGF) is a secreted endothelial cell-specific growth factor, which is induced by tissue hypoxia and is angiogenic in vivo. We investigated VEGF expression in squamous cell head and neck carcinomas by immunohistochemical techniques. All of the 156 patients studied had been treated with radical surgery and postoperative radiotherapy and were followed up until death or for at least 5 years. Of the tumors examined, 31% showed cytoplasmic staining for VEGF in carcinoma cells. Some of the tumor-infiltrating inflammatory cells, including plasma cells and tissue macrophages, showed high levels of VEGF expression in all of the carcinomas studied. Staining for VEGF was also found in acinic epithelial cells of histologically normal salivary glands and in normal stratified squamous epithelium adjacent to tumor. No association was observed between the VEGF expression of carcinoma cells and histologic grade, TNM stage, tumor microvessel count, or overall survival. These results demonstrate that in squamous cell head and neck cancer, in addition to being expressed by cancer cells VEGF is frequently expressed by tumor infiltrating inflammatory cells and by cells of histologically normal adjacent tissues; this suggests a possible role in tumor angiogenesis. Our results also suggest that angiogenic factors other than VEGF might provide the positive regulatory signals needed for tumor angiogenesis. In squamous cell head and neck cancer, carcinoma cell VEGF expression is not a prognostic marker.

Serum VEGF levels in women with a benign breast tumor or breast cancer.

Vascular endothelial growth factor (VEGF) is an important regulator of angiogenesis and vascular permeability. Many types of malignant human tumors have been shown to produce VEGF. Recently, increased serum concentrations of VEGF (S-VEGF) have been reported in patients with various types of cancer, and high S-VEGF levels have also been associated with unfavorable prognosis. We have now measured S-VEGF in sera taken from 105 patients with a benign breast tumor or breast cancer. None of the women with a benign breast tumor had S-VEGF higher than 328 pg/ml (median, 57 pg/ml) whereas S-VEGF levels in metastatic breast cancer ranged from 7 to 1347 pg/ml (median, 186 pg/ml; P = 0.0018), and in locoregional breast cancer from 11 to 539 pg/ml (median, 104 pg/ml; P = 0.13). S-VEGF was higher in patients with locoregional ductal cancer (median, 107 pg/ml) than in those with locoregional lobular cancer (median, 44 pg/ml; P = 0.029) or in patients with benign breast tumor (median, 57 pg/ml; P = 0.033). Patients with metastatic cancer undergoing therapy had lower S-VEGF than those who had symptomatic treatment only (P = 0.021). The results indicate that dissemination of breast cancer may be accompanied by an elevation of circulating VEGF and that primary ductal cancers are associated with higher S-VEGF levels than lobular cancers or benign breast lesions.

Vascular permeability factor/vascular endothelial growth factor in nasal polyps.

Although the aetiology of polyps is still, for the most part, unknown, the disease is known to involve tissue oedema. Vascular permeability/vascular endothelial growth factor (VPF/VEGF) is a major inducer of angiogenesis and capillary permeability. This study investigated VPF/VEGF expression in biopsies of nasal polyps from 39 patients and in healthy nasal mucosa from 10 patients by immunohistochemical staining. Staining for VPF/VEGF in the mucosal surface and in the glandular epithelium of nasal polyps was weaker than in normal controls. In two patients, strong staining for VPF/VEGF was found in a granular pattern in mast cells, while the mast cells in other polyposis patients appeared to be largely degranulated. VPF/VEGF was not seen in the mast cells of control patients. Although expression of VPF/VEGF was not increased in the epithelium of the nasal polyps, VPF/VEGF secreted from mast cells may take part in nasal polyp formation.

Endothelial Tie growth factor receptor provides antigenic marker for assessment of breast cancer angiogenesis.

Breast cancer prognosis has previously been linked to the degree of tumour vascularisation. In order to establish additional markers for tumour angiogenesis, we have used monoclonal antibodies against the endothelial Tie receptor tyrosine kinase to study the degree of vascularisation of breast carcinomas and the regulation of Tie expression in the vascular endothelial cells. Antibodies were used for Tie detection and the results were correlated with other prognostic markers. Of four monoclonal antibodies directed against different epitopes of the Tie extracellular domain, two reacted against Tie in unfixed histopathological sections of breast carcinomas. One of these antibodies (clone 7e8) was specific for the endothelial cells whereas the other (clone 10f11) also reacted with basement membranes and occasional carcinoma cells. When Tie expression was studied with the antibody clone 7e8, all 27 carcinomas, two in situ carcinomas, samples of histologically normal breast tissue (n = 16) or normal skin or lymph node tissue (n = 5) showed staining. Microvessel counts were higher in carcinomas (median 14; range 3-27) than in fibrodenomas (median 10; range 5-18) or histologically normal breast tissue (median 7; range 3-15, P = 0.0006). A similar result was obtained using antibodies against the CD31 (PECAM) antigen. Microvessel counts in 7e8 staining were not significantly associated with primary tumour size, axillary nodal status, histological grade or staining for oestrogen receptor, progesterone receptor, Ki-67 proliferation marker or p53 oncoprotein.

Vascular endothelial growth factors VEGF-B and VEGF-C are expressed in human tumors.

The growth of solid tumors is dependent on angiogenesis, the formation of new blood vessels. Vascular endothelial growth factor (VEGF) is a secreted endothelial-cell-specific mitogen. We have recently characterized two novel endothelial growth factors with structural homology to VEGF and named them VEGF-B and VEGF-C. To further define the roles of VEGF-B and VEGF-C, we have studied their expression in a variety of human tumors, both malignant and benign. VEGF-B mRNA was detected in most of the tumor samples studied, and the mRNA and the protein product were localized to tumor cells. Endothelial cells of tumor vessels were also immunoreactive for VEGF-B, probably representing the binding sites of the VEGF-B polypeptide secreted by adjacent tumor cells. VEGF-C mRNA was detected in approximately one-half of the cancers analyzed. Via in situ hybridization, VEGF-C mRNA was also localized to tumor cells. All lymphomas studied contained low levels of VEGF-C mRNA, possibly reflecting the cell-specific pattern of expression of the VEGF-C gene in the corresponding normal cells. The expression of VEGF-C is associated with the development of lymphatic vessels, and VEGF-C could be an important factor regulating the mutual paracrine relationships between tumor cells and lymphatic endothelial cells. Furthermore, VEGF-C and VEGF-B can, similarly to VEGF, be involved in tumor angiogenesis.