Tyrosine phosphorylation, regulated by protein tyrosine phosphatases (PTPs) and kinases (PTKs), is important in signaling pathways underlying tumorigenesis.
In this study, researchers performed a mutational analysis of the tyrosine phosphatase gene superfamily in human cancers.
The team identified 83 somatic mutations in 6 PTPs. These mutations affected 26% of colorectal cancers, as well as a proportion of lung, breast, and gastric cancers.
The researchers determined that 15 mutations were nonsense, frameshift, or splice-site alterations. These were predicted to result in truncated proteins lacking phosphatase activity.
|Mutations affected 26% of colorectal cancers.|
To assess whether tumor-specific point mutations altered phosphatase activity, the team biochemically examined the 5 most commonly altered PTPs.
Analysis confirmed that phosphatase activity was reduced.
In addition, the researchers found that expression of wild-type but not a mutant PTPRT in human cancer cells inhibited cell growth.
Dr Zhenghe Wang and colleagues concluded, "These observations suggest that the mutated tyrosine phosphatases are tumor suppressor genes, regulating cellular pathways that may be amenable to therapeutic intervention".