Expression of L-selectin ligands by transformed endothelial cells enhances T cell-mediated rejection.
Recent immunohistochemical studies have suggested that L-selectin ligands may be implicated in the infiltration of tumors and rejected transplants by lymphocytes. In the present study, polyoma-middle T Ag-transformed endothelial cells (H.end), which typically form in vivo immunogenic vascular tumors resembling Kaposi's sarcoma, were engineered to express L-selectin ligands by stable transfection with a cDNA encoding alpha(1,3/4)-fucosyltransferase (H.endft). The ability of these cells to form tumors in the s.c. tissues of normal and immunocompromised mice was then compared with that of H.end cells transfected with the hygromycin-resistance vector only (H. endhygro). H.endhygro cells rapidly formed local and metastatic tumors in normal syngeneic mice, leading to death within 2-3 mo postinjection. By contrast, tumors derived from H.endft cells displayed a slower rate of growth, an absence of metastasis, and marked lymphocyte infiltration. Animals bearing these tumors survived for a significantly longer duration than animals injected with H.endhygro cells. Alternatively, H.endft and H.endhygro cells formed tumors with comparable aggressiveness in immunocompromised mice, resulting in animal death within 3 wk of injection. H.endft but not H.endhygro cells supported L-selectin-dependent adhesion and cytolytic T cell activity in vitro. Taken together, our observations indicate that the in situ expression of fucosyltransferase may significantly influence the cellular immune response in endothelioma tumors. These results may be relevant in understanding the development of vascular opportunistic tumors such as Kaposi's sarcoma. (+info)
In vivo gene therapy with interleukin-12 inhibits primary vascular tumor growth and induces apoptosis in a mouse model.
Interleukin-12 is proposed to have anti-neoplastic activity on the basis of both its anti-angiogenic and immunologic effects. Gene gun therapy with interleukin-12 cDNA into the peritumoral area of immunocompetent 129/J mice with life-threatening primary vascular tumors reduced tumor volume 7.5-fold and almost tripled the duration of mouse survival, in contrast with luciferase-bombarded control mice. Epidermal expression of mouse interleukin-12 elevated tumoral and serum levels of interferon-gamma and tumor necrosis factor-alpha, increased the tumoral populations of T lymphocyte and natural killer cells, and induced tumor apoptosis. Gene transfer of interleukin-12 had little effect on tumor volumes and survival of tumor-bearing athymic nude mice, emphasizing the requirement for T cell directed cellular immunity. Peritumoral gene gun introduction of interleukin-12 may be a novel, cost-effective approach to limit the growth and associated mortality of life-threatening tumors. (+info)
Formation of transformed endothelial cells in the absence of VEGFR-2/Flk-1 by Polyoma middle T oncogene.
The middle T antigen of murine Polyomavirus (PymT) rapidly transforms endothelial cells leading to vascular malformations reminiscent of endothelial tumors or hemangiomas. Flk-1, a receptor tyrosine kinase which is activated upon binding of its ligand VEGF, is predominantly expressed in endothelial cells and essential for the formation of blood vessels since absence of Flk-1 prevents the development of mature endothelial cells in mice and in ES-cell differentiation experiments. To investigate the role of Flk-1 in PymT-induced vascular tumor formation, we studied the expression of Flk-1 and VEGF in PymT-transformed endothelial cells (Endothelioma cells, END. cells). The receptor and its ligand were both expressed in END. cells suggesting that a VEGF/Flk-1 autocrine loop might be causally involved in the formation of vascular tumors. To test this hypothesis, ES cells lacking Flk-1 were generated and the transforming potential of PymT was analysed after in vitro differentiation. Flk-1(-/-) END. cell lines were established which are morphologically identical to flk-1(+/+) END. cells and which express several markers characteristic for endothelial cells. This result suggests that PymT functionally replaces the requirement of Flk-1 in expansion and/or survival of endothelial progenitor cells. Therefore, flk-1(-/-) END. cells provide a powerful tool to dissect the downstream signaling pathways of Flk-1. (+info)
The generation of endostatin is mediated by elastase.
Endostatin, a potent inhibitor of angiogenesis and tumor growth, is a COOH-terminal fragment of collagen XVIII derived through cleavage of an Ala-His linkage by an as yet unidentified endostatin-processing enzyme. Endostatin was originally isolated from the conditioned medium of hemangioendothelioma (EOMA) cells. By investigating the processing of collagen XVIII to endostatin by EOMA cells, we show here that the generation of endostatin can be mediated by an elastase activity. We also show that several members of the elastase family can act as an endostatin-processing enzyme by specifically cleaving the Ala-His linkage and releasing endostatin from a precursor molecule. We further suggest that the generation of endostatin from collagen XVIII is at least a two-step process, involving a metal-dependent early step and an elastase activity-dependent final step. (+info)
Hemangioendothelioma of the parotid gland in infants: sonography and correlative MR imaging.
BACKGROUND AND PURPOSE: Hemangioendothelioma is the most common parotid gland tumor of childhood, and is diagnosed on clinical grounds, supported by imaging findings. Previous work has suggested that MR is the best imaging technique for assessment of parotid hemangioendothelioma. Demonstration of a reliable sonographic appearance would reduce the need for MR imaging in infants with this lesion. METHODS: We performed high-frequency sonography (including color Doppler and power Doppler imaging) in three patients, each with a diagnosis of parotid hemangioendothelioma confirmed by clinical follow-up. Two patients were also examined with MR imaging and labeled red cell scintigraphy. RESULTS: All sonographic studies showed a homogeneous mass enlarging and replacing most or all of the visualized parotid gland, with a lobular internal structure, fine echogenic internal septations, and a mildly lobulated contour. Color Doppler and power Doppler imaging showed extremely high vascularity within the mass. Correlative MR images in two infants showed a well-defined lesion with uniform intense contrast enhancement. Labeled red cell scintigraphy showed a well-defined area of intense activity. CONCLUSION: In the presence of a typical clinical history, sonography and clinical follow-up alone may prove to be sufficient for safe management of parotid hemangioendothelioma. MR imaging or labeled red cell scintigraphy may only be required if the sonographic features are atypical. These findings require confirmation in a larger series of patients. (+info)
Vascular endothelial growth factor receptor-3 (VEGFR-3): a marker of vascular tumors with presumed lymphatic differentiation, including Kaposi's sarcoma, kaposiform and Dabska-type hemangioendotheliomas, and a subset of angiosarcomas.
Recently, a novel monoclonal antibody to vascular endothelial growth factor receptor 3 (VEGFR-3), a tyrosine kinase receptor expressed almost exclusively by lymphatic endothelium in the adult, has been shown to react with a small number of cases of Kaposi's sarcoma (KS) and cutaneous lymphangiomas. We sought to extend these studies to a large number of well-characterized vascular neoplasms to evaluate diagnostic uses of this antibody and to determine whether it defines them in a thematic fashion. Formalin-fixed, paraffin-embedded sections from 70 vascular tumors were immunostained with antibodies to VEGFR-3 von Willebrand factor (vWF), and CD31. Anti-VEGFR-3 was positive in 23 of 24 KS, 8 of 16 angiosarcomas (AS), 6 of 6 kaposiform hemangioendotheliomas, 4 of 4 Dabska tumors, and 2 of 13 hemangiomas. Positively staining angiosarcomas were characterized either by a prominent lymphocytic component, a hobnail endothelial cell similar to that encountered in the Dabska tumor, or spindled areas resembling KS. No VEGFR-3 expression was noted in any cases of epithelioid hemangioendothelioma, pyogenic granuloma, littoral angioma, or stasis dermatitis. vWF expression was seen in 10 of 13 KS; 13 of 14 AS; 4 of 5 kaposiform hemangioendotheliomas; and all Dabska tumors, hemangiomas, lymphangiomas, epithelioid hemangioendotheliomas, vascular malformations, stasis dermatitis, and splenic littoral angiomas. CD31 expression was present in 12 of 13 KS, 13 of 14 AS, and in all other cases. Expression of VEGFR-3 is a very sensitive marker of KS, kaposiform, and Dabska-type hemangioendotheliomas, suggesting that all show at least partial lymphatic endothelial differentiation. Expression of VEGFR-3 does not reliably discriminate KS from AS. However, the expression of VEGFR-3 by certain AS having Kaposi-like areas, a prominent lymphocytic infiltrate, or hobnail endothelium may define subset(s) having phenotypic, if not pathogenetic and biologic, differences. (+info)
Sedation for intractable distress of a dying patient: acute palliative care and the principle of double effect.
Shortly before his death in 1995, Kenneth B. Schwartz, a cancer patient at Massachusetts General Hospital (MGH), founded the Kenneth B. Schwartz Center at MGH. The Schwartz Center is a nonprofit organization dedicated to supporting and advancing compassionate health care delivery, which provides hope to the patient, support to caregivers, and encourages the healing process. The Center sponsors the Schwartz Center Rounds, a monthly multidisciplinary forum where caregivers reflect on important psychosocial issues faced by patients, their families, and their caregivers, and gain insight and support from fellow staff members. The case presented is of a young man dying of recurrent epithelioid hemangioendothelioma, distressed with stridor and severe pain, whose poorly controlled symptoms were successfully treated with an infusion of propofol, titrated to provide effective comfort in the last few hours of the patient's life. The tenet of double effect, which allows aggressive treatment of suffering in spite of foreseeable but unintended consequences, is reviewed. The patient's parents were invited and contributed to the Rounds, providing compelling testimony to the power of the presence of clinicians at the time of death and the importance of open communication about difficult ethical issues. (+info)
Treatment options for other hepatic malignancies.
1. Resection rates for cholangiocarcinoma (unrelated to primary sclerosing cholangitis) have increased to 54% to 79%, and the subsequent 5-year survival rates are 24% to 31%. 2. Multimodality approaches involving various combinations of chemotherapy, irradiation, and surgery increasingly are being used to treat cholangiocarcinoma. 3. The role of liver transplantation in the management of cholangiocarcinoma is limited by the perception that it is inappropriate to use scarce organs when 5-year survival rates are 25%. 4. Liver transplantation is an important intervention in patients with tumors that remain unresectable after chemotherapy. The role of liver transplantation in patients with extrahepatic disease that responds to chemotherapy is controversial. Careful timing of surgery is required to avoid secondary drug resistance. 5. Liver transplantation has been successfully applied to a range of rare hepatic malignancies, but small numbers preclude strong recommendations on the appropriateness of this practice. (+info)