Caveolin-1 (CAV1) enhanced migration, invasion, and
metastasis of
cancer cells is inhibited by co-expression of the
glycoprotein E-cadherin. Although the two
proteins form a multiprotein complex that includes β-
catenin, it remained unclear how this would contribute to blocking the
metastasis promoting function of CAV1. Here, we characterized by mass spectrometry the
protein composition of CAV1 immunoprecipitates from B16F10 murine
melanoma cells expressing or not
E-cadherin. The novel
protein tyrosine phosphatase PTPN14 was identified by mass spectrometry analysis exclusively in co-immunoprecipitates of CAV1 with
E-cadherin. Interestingly, PTPN14 is implicated in controlling
metastasis, but only few known PTPN14 substrates exist. We corroborated by western blotting experiments that PTPN14 and CAV1 co-inmunoprecipitated in the presence of
E-cadherin in B16F10
melanoma and other
cancer cells. Moreover, the CAV1(Y14F)
mutant protein was shown to co-immunoprecipitate with PTPN14 even in the absence of
E-cadherin, and overexpression of PTPN14 reduced CAV1 phosphorylation on tyrosine-14, as well as suppressed CAV1-enhanced cell migration, invasion and Rac-1 activation in B16F10, metastatic colon [HT29(US)] and
breast cancer (MDA-MB-231) cell lines. Finally, PTPN14 overexpression in B16F10 cells reduced the ability of CAV1 to induce
metastasis in vivo. In summary, we identify here CAV1 as a novel substrate for PTPN14 and show that overexpression of this
phosphatase suffices to reduce CAV1-induced
metastasis.