Expression of a truncated 100 kDa HER2 splice variant acts as an endogenous inhibitor of tumour cell proliferation.

Overexpression of the HER2 (neu/c-erbB-2) oncogene frequently coincides with an aggressive clinical course of certain human adenocarcinomas. Expression and secretion of aberrant HER2 splice variants has been reported in various cell lines and tissues and can interfere with the oncogenic HER2 activity. Here we demonstrate, using two different approaches, that expression of a truncated 100 kDa HER2 variant which encodes the extracellular domain of HER2 (HER-ECD) inhibits growth factor-mediated tumour cell proliferation.