[Effect of tyrosine kinase inhibitor imatinib mesylate on K562 cell invasion by PTEN pathway].

AIM: To investigate the effect of tyrosine kinase inhibitor imatinib mesylate on the PTEN signaling pathway and the cell invasion in K562 cells. METHODS: K562 cells were treated with different concentrations of imatinib mesylate. After different time periods, the mRNA levels of BCR/ABL, PTEN and FAK were detected by real-time fluorescent quantitative PCR (FQ-PCR) to analyze their relationships. The protein level of FAK was detected by immunocytochemistry. The cell invasive ability was examined by Transwell (Boyden chamber) assay. RESULTS: In the initial 36 h, the expression level of PTEN mRNA was up-regulated and the FAK mRNA was down-regulated with the reduction of BCR/ABL fusion gene expression and the cell invasive ability of K562 cells was inhibited by 2 µg/mL imatinib mesylate. 48 h later, the PTEN mRNA expression level decreased and the FAK mRNA expression level was elevated with the restore of BCR/ABL fusion gene. BCR/ABL mRNA level presented a positive correlation with PTEN mRNA expression level, and a negative correlation with FAK mRNA. CONCLUSION: Tyrosine kinase inhibitor imatinib mesylate can regulate PTEN/FAK pathway and inhibit the leukemia K562 cell invasive ability via restraining BCR/ABL fusion gene.

[Regulation of wild type PTEN gene on Survivin, Xiap and Smac in chronic leukemia cells].

OBJECTIVE: To explore the effects of tumor-suppressing gene wild type PTEN on the cell proliferation, apoptosis and the possible regulations of apoptosis-related molecules Survivin, Xiap and Smac gene in human chronic myeloid leukemia (CML) and cell line K562 cells. METHODS: (1) The recombinant adenovirus containing green fluorescent protein (GFP) and PTEN (Ad-PTEN-GFP) or empty vector (Ad-GFP) was transfected into K562 cells. The growth of K562 cells was observed by MTT assay while cell cycle and apoptotic rate were assessed by flow cytometry (FCM). PTEN, Survivin, Xiap and Smac mRNA levels were detected by real-time fluorescent relative-quantification reverse transcriptional PCR (FQ-PCR) while PTEN protein levels analyzed by Western blot. (2) The expression levels of PTEN, Survivin, Xiap and Smac mRNA were detected in 10 chronic myelogenous leukemia (CML) patients in chronic phase (CML-CP), 10 CML patients in blast crises (CML-BC) and 10 normal control marrow mononuclear cells (MMNC). RESULTS: The growth of K562 cells was suppressed markedly. And the maximal growth inhibition rate was 38.6% after the transfection of PTEN. Survivin, Xiap, Smac mRNA expression levels were down-regulated by around 6.14, 7.44 and 2.95 folds respectively (0.0700 ± 0.0059, 0.0089 ± 0.0006, 0.0600 ± 0.0039 vs 0.4370 ± 0.0790, 0.0661 ± 0.0072, 0.1580 ± 0.0078 vs 0.4530 ± 0.0810, 0.0700 ± 0.0079, 0.1770 ± 0.0085, all P < 0.01). The mRNA expression level of PTEN in CML-BC patients was lower than that in CML-CP patients and normal control. But Survivin, Xiap, Smac mRNA expression levels were higher in CML-BC patients than those in CML-CP and normal control. CONCLUSION: The over-expression of PTEN gene may inhibit the proliferation of K562 cells and promote cell apoptosis via the regulation of Survivin, Xiap and Smac genes.