Vascular gene expression in nonneoplastic and malignant brain.

Malignant gliomas are uniformly lethal tumors whose morbidity is mediated in large part by the angiogenic response of the brain to the invading tumor. This profound angiogenic response leads to aggressive tumor invasion and destruction of surrounding brain tissue as well as blood-brain barrier breakdown and life-threatening cerebral edema. To investigate the molecular mechanisms governing the proliferation of abnormal microvasculature in malignant brain tumor patients, we have undertaken a cell-specific transcriptome analysis from surgically harvested nonneoplastic and tumor-associated endothelial cells.

Murine endothelial cell lines as models of tumor endothelial cells.

Identification of appropriate models for in vivo and in vitro preclinical testing of inhibitors of tumor angiogenesis and progression is vital to the successful development of anticancer therapeutics. Although the focus is on human molecular targets, most preclinical in vivo efficacy testing occurs in mice. The goal of the current studies was to identify a murine endothelial cell line to model tumor endothelium for studying the antiangiogenic activity of therapeutic compounds in vitro.

Identification of genes expressed in malignant cells that promote invasion.

To systematically identify genes related to invasion a three-dimensional multicellular matrix invasion assay was used to classify human tumor cell lines as stromal invasion positive or stromal invasion negative. Cells from two of the primary cell types of the stromal compartment [endothelial cells (HMVEC) and myofibroblasts (HDF)] were assayed for invasion into tumor cell clusters (breast carcinoma, ovarian carcinoma, prostate carcinoma, lung carcinoma, and melanoma). Four tumor cell lines (MDA-MB231, SKOV-3, A375, and MEL624) scored invasion positive, and four tumor cell lines (LNCaP, DU145, PC3, and A549) scored invasion negative.

Endothelial precursor cells as a model of tumor endothelium: characterization and comparison with mature endothelial cells.

Human umbilical vein endothelial cells (HUVEC) and human microvascular endothelial cells (HMVEC) have been the standards for cell-based assays in the field of angiogenesis research and in antiangiogenic drug discovery. These normal mature endothelial cells may not be most representative of human tumor endothelial cells. Human AC133+/CD34+ bone marrow progenitor cells were established in cell culture media containing vascular endothelial growth factor, basic fibroblast growth factor (bFGF), and heparin to drive differentiation toward the endothelial phenotype.

Myofibroblasts enable invasion of endothelial cells into three-dimensional tumor cell clusters: a novel in vitro tumor model.

Purpose: In an effort to study the importance of stromal involvement in angiogenesis, we developed a novel, multicellular model that utilizes three of the primary cell types involved in tumor angiogenesis.

Methods: Fluorescently labeled human microvascular endothelial cells (HMVECs), 10T1/2 cells and myofibroblasts were incubated in the presence of a three-dimensional tumor cell cluster resuspended in collagen and embedded in Matrigel.

Results: HMVECs cultured in the presence of a human SKOV-3 ovarian carcinoma tumor cell cluster, surrounded the tumor cell cluster, while myofibroblasts invaded the cluster, localizing within the tumor cell mass.