Identification of metastasis associated proteins in human lung squamous carcinoma using two-dimensional difference gel electrophoresis and laser capture microdissection.

A quantitative proteomic approach was used to discover potential protein markers associated with lymph node metastasis (LNM) in human lung squamous carcinoma (LSC). Laser capture microdissection was performed to purify LSC cells with LNM (LNM LSC) and LSC without LNM (non-LNM LSC). The differentially expressed proteins between pooled microdissected non-LNM LSC and LNM LSC cells were identified by two-dimensional difference gel electrophoresis (2D-DIGE) coupled with mass spectrometry (MS). 14 proteins were found to be differentially expressed between non-LNM LSC and LNM LSC. Among these proteins, ten proteins were overexpressed in LNM LSC compared with non-LNM LSC, and four proteins were downregulated in LNM LSC. Some of these identified proteins (Annexin A2, HSP27, CK19, and 14-3-3sigma) were further confirmed by Western blotting and immunohistochemical analysis. These results show the value of LCM coupled with 2D-DIGE in identifying potential markers for lymph node metastasis of LSC, and also provide further insights into the prognosis of LSC.