Kathi Tognazzi

Expression of vascular permeability factor (vascular endothelial growth factor) and its receptors in breast cancer

Solid tumors must induce a vascular stroma to grow beyond a minimal size, and the intensity of the angiogenic response has been correlated with prognosis in breast cancer patients. Vascular permeability factor (VPF), also known as vascular endothelial growth factor (VEGF), is a secreted protein that has been implicated in tumor-associated angiogenesis. Vascular permeability factor directly stimulates endothelial cell growth and also increases microvascular permeability, leading to the extravasation of plasma proteins, which alter the extracellular matrix in a manner that promotes angiogenesis. To determine whether VPF has a role in breast cancer, we used in situ hybridization to study VPF mRNA expression in normal breast tissue (13 specimens), comedo-type ductal carcinoma in situ (DCIS) (four specimens), infiltrating ductal carcinoma (12 specimens), infiltrating lobular carcinoma (two specimens), metastatic ductal carcinoma (three specimens) and metastatic lobular carcinoma (one specimen). Vascular permeability factor mRNA was expressed at a low level by normal duct epithelium but was expressed at high levels in tumor cells in all cases of comedo-type DCIS, infiltrating ductal carcinoma, and metastatic ductal carcinoma. In contrast, VPF mRNA was not expressed at high levels in infiltrating lobular carcinoma. We also used in situ hybridization to study the expression of two recently described endothelial cell surface VPF receptors, flt-1 and kdr. Vascular permeability factor receptor mRNA was strongly expressed in endothelial cells of small vessels adjacent to malignant tumor cells in DCIS, infiltrating ductal carcinoma, and metastatic ductal carcinoma. In contrast, no definite labeling for receptor mRNA was detected in infiltrating lobular carcinoma or nonmalignant breast tissue. The intense expression of VPF mRNA by breast carcinoma cells and of VPF receptor mRNA by endothelial cells of adjacent small blood vessels provides strong evidence linking VPF expression to the angiogenesis associated with comedo-type DCIS, infiltrating ductal, and metastatic ductal breast carcinoma.

Expression of Tie1, Tie2, and Angiopoietins 1, 2, and 4 in Kaposi's Sarcoma and Cutaneous Angiosarcoma

The angiopoietins are recently described growth factors for vascular endothelium. The Tie1 and Tie2 receptors are expressed by endothelium. Acquired immune deficiency syndrome (AIDS)-associated Kaposis sarcoma (KS) and cutaneous angiosarcoma are malignancies of endothelial origin. KS involves primarily the skin and mucosal surfaces and is common in AIDS patients. In an effort to determine whether the angiopoietins and Tie receptors play a role in the pathobiology of angiosarcoma and KS, we studied the expression of angiopoietin-1, angiopoietin-2, angiopoietin-4, Tie1, and Tie2 mRNAs in biopsies of KS from 12 AIDS patients, in biopsies of cutaneous angiosarcoma from two patients, and in control biopsies of normal skin from three volunteers by in situ hybridization. Strong expression of angiopoietin-2, Tie1, and Tie2 mRNAs was detected in the tumor cells of KS and cutaneous angiosarcomas, in contrast to the focal low-level expression in normal skin biopsies. Focal low-level expression of angiopoietin-1 was seen in KS, cutaneous angiosarcomas, and in normal skin. Focal low-level expression of angiopoietin-4 was identified in a minority of KS lesions. These findings suggest that the angiopoietins and Tie receptors may play an important role in the pathobiology of KS and cutaneous angiosarcoma and identify additional potential targets for therapeutic intervention in these vascular malignancies.

Expression of vascular permeability factor (vascular endothelial growth factor) and its receptors in endometrial carcinoma

Solid tumors, including endometrial carcinomas, must induce a vascular stroma to grow beyond a minimal size. The mechanisms responsible for angiogenesis in endometrial carcinoma, however, are not well defined. Vascular permeability factor (VPF), also known as vascular endothelial growth factor (VEGF), is a multifunctional cytokine that is an important regulator of tumor angiogenesis. We evaluated VPF/VEGF mRNA and protein expression, as well as VPF/VEGF receptor mRNA expression, in endometrial carcinoma.

Cloning of DLM-1, a novel gene that is up-regulated in activated macrophages, using RNA differential display

Tumors interact with their environment, reprogramming host cells to induce responses such as angiogenesis, inflammation, immunity and immune suppression. To understand these processes, it is important to identify and isolate new genes whose expression is induced in host tissues in response to tumors. Ascites tumors offer an attractive model for isolating such genes, because responding host peritoneal lining tissues can be cleanly separated from tumor cells growing in suspension within the peritoneal cavity. We here report the cloning by differential display of a novel gene, DLM-1, that is highly up-regulated in the peritoneal lining tissue of mice bearing MOT ascites tumors. Mouse peritoneal macrophages, stimulated by IFN-gamma or LPS, also expressed significant amounts of DLM-1. Up-regulation of DLM-1 became evident by 4h after stimulation with IFN-gamma and was not blocked by cycloheximide, suggesting the presence of IFN responding elements in its transcription regulation region. DLM-1 RNA was detected at significant levels in normal mouse lung, intestinal epithelium, liver and thymus by Northern blot analysis. In situ hybridization of MOT and HT-29 mouse subcutaneous transplanted solid tumors revealed strong DLM-1 expression in the host reactive stromal cells, but not the tumor cells. Sequence analysis of the full-length cDNA clone revealed that it encodes a protein of approx. M(r) 44330 with multiple potential protein kinase C and casein kinase II phosphorylation sites. Our data suggest that DLM-1 plays a role in such important processes as host response in neoplasia.

Vascular Permeability Factor/Vascular Endothelial Growth Factor and Vascular Stroma Formation in Neoplasia: Insights from In Situ Hybridization Studies

The formation of vascular stroma plays an important role in the pathophysiology of malignancy. We describe the use of in situ hybridization in our laboratory as a tool to study the role of vascular permeability factor/vascular endothelial growth factor in the angiogenesis associated with malignancy.