1. Protein tyrosine phosphatase PRL-3 in malignant cells and endothelial cells: expression and function.
- Author
-
Rouleau C, Roy A, St Martin T, Dufault MR, Boutin P, Liu D, Zhang M, Puorro-Radzwill K, Rulli L, Reczek D, Bagley R, Byrne A, Weber W, Roberts B, Klinger K, Brondyk W, Nacht M, Madden S, Burrier R, Shankara S, and Teicher BA
- Subjects
- Endothelial Cells drug effects, Endothelial Cells enzymology, Gene Expression drug effects, Humans, Neoplasms genetics, Oligonucleotide Array Sequence Analysis, RNA, Messenger analysis, RNA, Messenger metabolism, Salivary Proteins and Peptides analysis, Tetradecanoylphorbol Acetate pharmacology, Up-Regulation, Gene Expression Regulation, Neoplastic, Genes, Neoplasm genetics, Neoplasms enzymology, Salivary Proteins and Peptides genetics
- Abstract
Protein tyrosine phosphatase PRL-3 mRNA was found highly expressed in colon cancer endothelium and metastases. We sought to associate a function with PRL-3 expression in both endothelial cells and malignant cells using in vitro models. PRL-3 mRNA levels were determined in several normal human endothelial cells exposed or unexposed to the phorbol ester phorbol 12-myristate 13-acetate (PMA) and in 27 human tumor cell lines. In endothelial cells, PRL-3 mRNA expression was increased in human umbilical vascular endothelial cells and human microvascular endothelial cells (HMVEC) exposed to PMA. An oligonucleotide microarray analysis revealed that PRL-3 was among the 10 genes with the largest increase in expression on PMA stimulation. Phenotypically, PMA-treated HMVEC showed increased invasion, tube formation, and growth factor-stimulated proliferation. A flow cytometric analysis of cell surface markers showed that PMA-treated HMVEC retained endothelial characteristics. Infection of HMVEC with an adenovirus expressing PRL-3 resulted in increased tube formation. In tumor cells, PRL-3 mRNA levels varied markedly with high expression in SKNAS neuroblastoma, MCF-7 and BT474 breast carcinoma, Hep3B hepatocellular carcinoma, and HCT116 colon carcinoma. Western blotting analysis of a subset of cell line lysates showed a positive correlation between PRL-3 mRNA and protein levels. PRL-3 was stably transfected into DLD-1 colon cancer cells. PRL-3-overexpressing DLD-1 subclones were assessed for doubling time and invasion. Although doubling time was similar among parental, empty vector, and PRL-3 subclones, invasion was increased in PRL-3-expressing subclones. In models of endogenous expression, we observed that the MCF-7 cell line, which expresses high levels of PRL-3, was more invasive than the SKBR3 cell line, which expresses low levels of PRL-3. However, the MDA-MB-231 cell line was highly invasive with low levels of PRL-3, suggesting that in some models invasion is PRL-3 independent. Transfection of a PRL-3 small interfering RNA into MCF-7 cells inhibited PRL-3 expression and cell invasion. These results indicate that PRL-3 is functional in both endothelial cells and malignant cells and further validate PRL-3 as a potentially important molecular target for anticancer therapy.
- Published
- 2006
- Full Text
- View/download PDF