Monoclonal antibodies target intracellular PRL phosphatases to inhibit cancer metastases in mice

PRL-1 (phosphatase of regenerating liver-1), PRL-2, and PRL-3 are protein tyrosine phosphatases with a C-terminal prenylation motif that are localized to the inner leaflet of the plasma membrane and early endosomes. A variety of metastatic PRL-overexpressing cancers have been reported. Therefore, th...

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Bibliographic Details
Published in:Cancer biology & therapy 2008-05, Vol.7 (5), p.750-757
Main Authors: Guo, Ke, Li, Jie, Ping Tang, Jing, Bobby Tan, Cheng Peow, Wang, Haihe, Zeng, Qi
Format: Article
Language:English
Subjects:
Animals
Antibodies, Monoclonal - chemistry
Antineoplastic Agents - pharmacology
Binding
Biology
Bioscience
Calcium
Cancer
Cell
Cell Cycle Proteins - chemistry
Cell Line, Tumor
CHO Cells
Cricetinae
Cricetulus
Cycle
Gene Expression Regulation, Neoplastic
Humans
Landes
Membrane Proteins - chemistry
Mice
Microscopy, Confocal
Neoplasm Metastasis
Neoplasm Transplantation
Organogenesis
Protein Tyrosine Phosphatases - chemistry
Proteins
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Summary:PRL-1 (phosphatase of regenerating liver-1), PRL-2, and PRL-3 are protein tyrosine phosphatases with a C-terminal prenylation motif that are localized to the inner leaflet of the plasma membrane and early endosomes. A variety of metastatic PRL-overexpressing cancers have been reported. Therefore, the three PRL-phosphatases represent an intriguing group of proteins being validated as biomarkers and therapeutic targets in cancer. Targeting intracellular PRLs to prevent cancer metastasis by exogenous reagents is a challenging task. In an attempt to destroy PRL-overexpressing cancer cells with their respective PRL-antibodies, we generated an animal model that allows rapid formation of aggressive metastatic tumors caused by inoculation of PRL-1- or PRL-3-expressing cells. Surprisingly, mice treated with PRL-1 or PRL-3 mAbs show inhibition of tumor formation by ~90% compared to untreated mice. Here we provide the first examples that PRL-1 and PRL-3 mAbs are able to target their respective phosphatases specifically and efficiently despite their intracellular localization to block cancer metastasis in experimental animals. Furthermore, we also demonstrate that PRL-1 mAb specifically blocks the formation of metastatic tumors formed by PRL-1- (but not PRL-3-) expressing cells; while PRL-3 mAb specifically blocks tumor formation of PRL-3- (but not PRL-1-) expressing cells. More importantly, we show that metastatic tumor formation by A2780 human ovarian cancer cells that express endogenous PRL-3 is dramatically blocked by PRL-3 antibodies. In contrast, the PRL-3 antibody treatment has no effect on tumor formation of CT26 mouse colon cancer cells which do not naturally express PRL-3 protein. Our data provide hope for the treatment of PRL-expressing cancers and will prompt a reevaluation of a wide spectrum of intracellular oncoproteins as possible targets with mAbs for anticancer therapy.
ISSN:1538-4047
1555-8576
DOI:10.4161/cbt.7.5.5764