Protein tyrosine phosphatase PRL-3 in malignant cells and endothelial cells: expression and function.
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.
Rouleau
Cecile
C
Genzyme Corp., 1 Mountain Road, Framingham, MA 01701, USA.
Roy
Andre
A
St Martin
Thia
T
Dufault
Michael R
MR
Boutin
Paula
P
Liu
Dapei
D
Zhang
Mindy
M
Puorro-Radzwill
Kristin
K
Rulli
Lori
L
Reczek
Dave
D
Bagley
Rebecca
R
Byrne
Ann
A
Weber
William
W
Roberts
Bruce
B
Klinger
Katherine
K
Brondyk
William
W
Nacht
Mariana
M
Madden
Steve
S
Burrier
Robert
R
Shankara
Srinivas
S
Teicher
Beverly A
BA
D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology; D015870:Gene Expression / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic; D052138:Genes, Neoplasm / Q000235:genetics*; D006801:Humans; D009369:Neoplasms / Q000201:enzymology* / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D012471:Salivary Proteins and Peptides / Q000032:analysis / Q000235:genetics*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D015854:Up-Regulation
D012333:RNA, Messenger; C408143:SMR3B protein, human; D012471:Salivary Proteins and Peptides; D013755:Tetradecanoylphorbol Acetate