[Up-regulation of Stathmin and CrkL protein expressions in adriamycin-resistant leukemia cell line K562/A02].

The purpose of this study was to compare the differences of the protein expression profiles between human myeloid leukemia K562 cells and adriamycin-resistant K562/A02 cells, as well as to select novel resistance-related proteins in myeloid leukemia by means of proteomics. The total cellular proteins were separated from K562 and adriamycin-resistant K562/A02 cells by using technique of two dimensional difference in gel electrophoresis (2D-DIGE). Differentially expressed proteins were analyzed by matrix-assisted laser desorption ionization/time of flight-mass spectrometry (MALDI-TOF/MS), and by protein database searching. Moreover, the differentially expressed proteins were verified at protein and mRNA levels by Western blot assay and quantitative real time PCR. The results showed that 8 proteins differentially expressed in adriamycin-resistant K562/A02 cells, among them 2 proteins were identified to be down-regulated and 6 to be up-regulated. These identified proteins involved in the cell energy metabolism, cell proliferation, cell apoptosis, signal transduction, gene transcription and translation respectively. The results assayed by Western blot were similar to those detected by 2D-PAGE. Two up-regulated proteins Stathmin and CrkL were selected for verification in K562 and K562/A02 cells. As a result, the results detected by Western blot were identical with results from 2D-DIGE; real time quantitative PCR assay showed that the changes of CrkL at mRNA level were identical with changes at protein level, but no complete identity of Stathmin changes at mRNA level and protein level was observed. It is concluded that the difference of protein expression profile exists in K562 and K562/A02 cells. Stathmin and CrkL proteins may be involved in the drug resistance and suggest a novel clue for the resistant mechanisms in myeloid leukemia, which is worth further to explore.