Isolation of a distinct class of gain-of-function SHP-2 mutants with oncogenic RAS-like transforming activity from...

Area of Science:

• Oncology
• Molecular Biology
• Biochemistry

Background:

• SHP-2 protein tyrosine phosphatase, encoded by PTPN11, is crucial for RAS signaling.
• Gain-of-function PTPN11 mutations are implicated in Noonan syndrome and childhood leukemias, establishing SHP-2 as an oncoprotein.
• The role of SHP-2 mutations in solid tumors is largely unknown.

Purpose of the Study:

• To investigate the role of SHP-2 mutations in non-hematological malignancies.
• To identify and characterize novel PTPN11 mutations in solid tumors.
• To determine the oncogenic potential of a newly identified SHP-2 mutant.

Main Methods:

• Screening of PTPN11 mutations in primary solid tumors.
• Characterization of a novel T507K SHP-2 mutant's enzymatic activity and substrate specificity.
• In vitro transformation assays using NIH3T3 cells expressing wild-type and mutant SHP-2.
• In vivo tumor formation studies in nude mice.

Main Results:

• A 1520C>A mutation leading to T507K substitution in SHP-2 was identified in a hepatocellular carcinoma case.
• T507K SHP-2 displayed altered substrate specificity and increased basal phosphatase activity.
• NIH3T3 cells expressing T507K SHP-2 exhibited foci formation, anchorage-independent growth, and tumor development in vivo.
• Wild-type, Noonan-specific, and leukemia-specific SHP-2 mutants did not induce similar transforming effects.

Conclusions:

• Altered phosphatase activity (quantitative/qualitative) dictates the transforming potential and tissue tropism of SHP-2 mutants.
• The T507K SHP-2 mutant represents a distinct class with RAS-like oncogenic transforming activity.
• This finding suggests a potential role for specific SHP-2 mutants in the pathogenesis of solid tumors, albeit rare.