RESUMEN
The recently emerged concept of cancer stem cell (CSC) has led to a new hypothesis on the basis for tumor progression. Basically, the CSC theory hypothesizes the presence of a hierarchically organized and relatively rare cell population, which is responsible for tumor initiation, self-renewal, and maintenance, in addition to accumulation of mutation and resistance to chemotherapy. CSCs have recently been described in breast cancer. Different genetic markers have been used to isolate breast CSCs, none of which have been correlated with the tumorigenicity or metastatic potential of the cells, limiting their precise characterization and clinical application in the development of therapeutic protocols. Here, we sought for subpopulations of CSCs by analyzing 10 judiciously chosen stem cell markers in a normal breast cell line (MCF10-A) and in four human breast cancer cell lines (MCF-7, MDA-MB-231, MDA-MB-435, and Hs578-T) displaying different degrees of metastatic and invasiveness potential. We were able to identify two markers, which are differentially expressed in nontumorigenic versus tumor cells. The CD90 marker was highly expressed in the malignant cell lines. Interestingly, the CD14 molecule displayed higher expression levels in the nontumorigenic cell line. Therefore, we demonstrated that these two markers, which are more commonly used to isolate and characterize stem cells, are differentially expressed in breast tumor cells, when compared with nontumorigenic breast cells.
Asunto(s)
Regulación Neoplásica de la Expresión Génica , Receptores de Lipopolisacáridos/análisis , Células Madre Neoplásicas/química , Antígenos Thy-1/análisis , Biomarcadores de Tumor/análisis , Neoplasias de la Mama/diagnóstico , Neoplasias de la Mama/genética , Femenino , Citometría de Flujo , Humanos , Receptores de Lipopolisacáridos/genética , Células MCF-7 , Metástasis de la Neoplasia , Células Madre Neoplásicas/patología , ARN Mensajero/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Antígenos Thy-1/genéticaRESUMEN
BACKGROUND: The expression levels of the clotting initiator protein Tissue Factor (TF) correlate with vessel density and the histological malignancy grade of glioma patients. Increased procoagulant tonus in high grade tumors (glioblastomas) also indicates a potential role for TF in progression of this disease, and suggests that anticoagulants could be used as adjuvants for its treatment. OBJECTIVES: We hypothesized that blocking of TF activity with the tick anticoagulant Ixolaris might interfere with glioblastoma progression. METHODS AND RESULTS: TF was identified in U87-MG cells by flow-cytometric and functional assays (extrinsic tenase). In addition, flow-cytometric analysis demonstrated the exposure of phosphatidylserine in the surface of U87-MG cells, which supported the assembly of intrinsic tenase (FIXa/FVIIIa/FX) and prothrombinase (FVa/FXa/prothrombin) complexes, accounting for the production of FXa and thrombin, respectively. Ixolaris effectively blocked the in vitro TF-dependent procoagulant activity of the U87-MG human glioblastoma cell line and attenuated multimolecular coagulation complexes assembly. Notably, Ixolaris inhibited the in vivo tumorigenic potential of U87-MG cells in nude mice, without observable bleeding. This inhibitory effect of Ixolaris on tumor growth was associated with downregulation of VEGF and reduced tumor vascularization. CONCLUSION: Our results suggest that Ixolaris might be a promising agent for anti-tumor therapy in humans.