title: Myosin light chain kinase is responsible for high proliferative ability of breast cancer cells via anti-apoptosis involving p38 pathway.
abstract: OBJECTIVE
  To investigate whether myosin light chain kinase (MLCK) contributed to the high proliferative ability of breast cancer cells.
  
  
  METHODS
  Soft agar colony formation on the MCF-7 and LM-MCF-7 cell lines was determined. The cell cycles of MCF-7 and LM-MCF-7 were detected using flow cytometry analysis. Western blot analysis was performed to detect the expression levels of p-ERK1/2, total-ERK1/2, p-p38, total p38, p-JNK, total-JNK, survivin, Bcl-2, p-MLC, caspase-9, cleaved caspase-9, and MLCK. After treatment with adriamycin (ADR), ML-7 and SB203580, apoptosis was examined using flow cytometry analysis and Annexin V-FITC fluorescence microscopy.
  
  
  RESULTS
  The breast cancer LM-MCF-7 cell line with high metastasis potential (a metastitic sub-clone of MCF-7) had higher anti-apoptosis ability relative to MCF-7 cells in response to adriamycin treatment (apoptosis rate: 6.76% vs 28.58%, P<0.05). Moreover, the expression level of MLCK was upregulated and the level of phosphorylated p38 (p-p38) was decreased in LM-MCF-7 cells. Flow cytometry analysis showed that ML-7, selective inhibitor of MLCK, could induce apoptosis of the LM-MCF-7 cells, in which the level of p-p38 was increased. Meanwhile, the expression levels of Bcl-2 and survivin were downregulated, while the caspase-9 was upregulated suggesting that the cells were undergone apoptosis. Flow cytometry analysis showed that SB203580, an inhibitor of p38, abolished ML-7-induced apoptosis, which resulted in the upregulation of Bcl-2 and survivin, and downregulation of caspase-9, suggesting that Bcl-2, survivin and caspase-9 are downstream effectors of p38.
  
  
  CONCLUSIONS
  MLCK is responsible for high proliferative ability of breast cancer cells through anti-apoptosis, in which p38 pathway was involved.
authors.affiliation: Department of Biochemistry, the Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China.
authors.forename: Wen-jing
authors.initials: WJ
authors.lastname: Cui
authors.forename: Yi
authors.initials: Y
authors.lastname: Liu
authors.forename: Xiao-lei
authors.initials: XL
authors.lastname: Zhou
authors.forename: Feng-ze
authors.initials: FZ
authors.lastname: Wang
authors.forename: Xiao-dong
authors.initials: XD
authors.lastname: Zhang
authors.forename: Li-hong
authors.initials: LH
authors.lastname: Ye
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D017209:Apoptosis; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000201:enzymology* / Q000473:pathology*; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004317:Doxorubicin / Q000494:pharmacology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D020935:MAP Kinase Signaling System; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism*; D009362:Neoplasm Metastasis; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D000903:Antibiotics, Antineoplastic; D004317:Doxorubicin; D009219:Myosin-Light-Chain Kinase; D048051:p38 Mitogen-Activated Protein Kinases; D020169:Caspases
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