Among the genes identified, in a comparison of the global gene expression profile of metastatic colorectal cancer to that of primary cancers, benign colorectal tumors, and normal colorectal epithelium, the PRL-3 protein tyrosine phosphatase gene was of particular interest. It was expressed at high levels in each of 18 cancer metastases studied but at lower levels in non-metastatic tumors and normal colorectal epithelium. In three of twelve metastases examined, multiple copies of the PRL-3 gene were found within a small amplicon located at chromosome 8q24.3. These data suggest that the PRL-3 gene is important for colorectal cancer metastasis and provides a new therapeutic target for these intractable lesions.

The John Hopkins University

Phosphatase associated with metastasis

Tyrosine phosphorylation, regulated by protein tyrosine phosphatases (PTPs) and kinases (PTKs), is important in signaling pathways underlying tumorigenesis. A mutational analysis of the tyrosine phosphatase gene superfamily in human cancers identified 83 somatic mutations in six PTPs (PTPRF, PTPRG, PTPRT, PTPN3, PTPN13, PTPN14), affecting 26% of colorectal cancers and a smaller fraction of lung, breast and gastric cancers. Fifteen mutations were nonsense, frameshift or splice site alterations predicted to result in truncated proteins lacking phosphatase activity. Five missense mutations in the most commonly altered PTP (PTPRT) were biochemically examined and found to reduce phosphatase activity. Expression of wild-type but not a mutant PTPRT in human cancer cells inhibited cell growth. These observations suggest that the tyrosine phosphatase genes are tumor suppressor genes, regulating cellular pathways that may be amenable to therapeutic intervention.

Wang; Zhenghe

Velculescu; Victor

Kinzler; Kenneth W.

Vogelstein; Bert

The Johns Hopkins University

Protein tyrosine phosphatase mutations in cancers

Tyrosine phosphorylation, regulated by protein tyrosine phosphatases (PTPs) and kinases (PTKs), is important in signaling pathways underlying tumorigenesis. A mutational analysis of the tyrosine phosphatase gene superfamily in human cancers identified 83 somatic mutations in six PTPs (PTPRF, PTPRG, PTPRT, PTPN3, PTPN13, PTPN14) affecting 26% of colorectal cancers and a smaller fraction of lung, breast and gastric cancers. Fifteen mutations were nonsense, frameshift or splice site alterations predicted to result in truncated proteins lacking phosphatase activity. Five missense mutations in the most commonly altered PTP (PTPRP) were biochemically examined and found to reduce phosphatase activity. Expression of wild-type but not a mutant PTPRT in human cancer cells inhibited cell growth. These observations suggest that the tyrosine phosphatase genes are tumor suppressor genes, regulating cellular pathways that may be amenable to therapeutic intervention.

colorectal neoplasms/phosphatase

Phosphatase associated with metastasis

Protein tyrosine phosphatase mutations in cancers

Protein tyrosine phosphatase mutations in cancers

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