Phenotypic and functional characteristics of endothelial cells derived from human liver cancer

Objective: To analyze the phenotypic and functional characteristics of endothelial (T3A) cells derived from human hepatocellular cell carcinoma.

Methods: Endothelial cells were isolated from human hepatocellular carcinoma specimens. The identification of T3A cells was performed by checking von Willebrand Factor (vWF), CD31, CD34 and Dil-Ac-LDL uptake. The cell surface fenestrations, a specific morphological feature of tumor derived EC, were investigated by scanning and transmission electron microscopy. The phenotypic characteristics of T3A cells were analyzed by fluorescence-activated cell sorter (FACS) and were further conformed by real-time PCR at transcription level. Furthermore, tumor necrosis factor alpha (TNFalpha)-induced cytotoxicity was evaluated by 3-(4, 5-dimethythiazolyl) -2, -diphenyl-2H-tetrazolium-bromide (MTT) assay; Matrix metalloproteinase secretion was detected by zymography; Angiogenic ability in vitro was analyzed by culturing T3A cells in three-dimensional Matrigel plug. Coagulant and fibrinolytic activities were detected by enzyme-linked immunosorbent assay (ELISA).

Results: The isolated T3A cells exhibited classic "spindle-shape" morphology and monolayer growth and contact inhibition properties. Immunofluorescent staining showed that T3A cells expressed vWF, CD31, CD34, and uptake of Dil-Ac-LDL at a high level. The cell surface fenestrations were observed on T3A cells by scanning and transmission electron microscopy. By FACS and real-time PCR, T3A cells were found to express alphav3, alphavbeta5 and TNF receptor p75 at high levels, and TNF receptor p55 and ICAM-1 at low levels, as compared with those in human liver sinusoidal endothelial cells (LSEC). In response to TNFalpha, LSEC exhibited a dose-dependent cytotoxicity, while T3A cells were resistant. Gelatin zymography showed that MMP-2 activity was higher in T3A cells than that in LSEC. In a three-dimensional plug of Matrigel, T3A cells exhibited stronger angiogenic ability as compared with LSEC. In addition, T3A cells released more tissue factor (TF), tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor (PAI-1) and urine plasminogen activator (u-PA) than LSEC in response to TNFalpha.

Conclusions: Tumor-derived endothelial cells are phenotypically and functionally different from those derived from normal liver tissue.