Proteomic analysis of elF-5A in lung adenocarcinomas

We examined the elF-5A protein expression in 93 lung adenocarcinomas and 10 uninvolved lung samples using quantitative two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) analysis with identification by mass spectrometry and 2-D Western blots. The same tissue samples were examined for the elF-5A mRNA expression using oligonucleotide microarrays, and the cellular localization of the elF-5A protein was examined using immunohistochemical analysis on tissue arrays. Higher elF-5A protein expression was present in tumors showing poor differentiation, 12/13^th codon K-ras mutations, p53 nuclear accumulation, and tumors with positive lymphocytic response. The elF-5A mRNA was also significantly increased in lung adenocarcinomas compared to normal lung, but the elF-5A protein expression was not correlated to its mRNA levels indicating that the increase in the elF-5A protein expression in lung tumors is post-transcriptionally/translationally/post-translationally regulated. Patients having a higher elF-5A protein expression showed a relatively poorer survival suggesting the use of elF-5A as prognostic marker in lung adenocarcinoma. Moreover, the investigation on agents that inhibit elF-5A function is encouraged.