Proteomic analysis of eIF‐5A in lung adenocarcinomas

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Abstract
We examined the eIF‐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 eIF‐5A mRNA expression using oligonucleotide microarrays, and the cellular localization of the eIF‐5A protein was examined using immunohistochemical analysis on tissue arrays. Higher eIF‐5A protein expression was present in tumors showing poor differentiation, 12/13th codon K‐ras mutations, p53 nuclear accumulation, and tumors with positive lymphocytic response. The eIF‐5A mRNA was also significantly increased in lung adenocarcinomas compared to normal lung, but the eIF‐5A protein expression was not correlated to its mRNA levels indicating that the increase in the eIF‐5A protein expression in lung tumors is post‐transcriptionally/translationally/post‐translationally regulated. Patients having a higher eIF‐5A protein expression showed a relatively poorer survival suggesting the use of eIF‐5A as prognostic marker in lung adenocarcinoma. Moreover, the investigation on agents that inhibit eIF‐5A function is encouraged.