Proteome profiling of immortalization-to-senescence transition of human breast epithelial cells identified MAP2K3 as a senescence-promoting protein which is downregulated in human breast cancer.
OBJECTIVE
immortalization is one of the first changes in cells undergoing carcinogenic transformation. Proteome profiling of the immortalization-senescence transition is expected to provide insights into the molecular mechanisms of early tumorigenesis.


METHODS
2-DE and MALDI-MS were used to identify proteins in primary human breast epithelial cells, relevant to the immortalization-senescence transition. Cell and molecular biology and immunohistochemistry were used to validate involvement of mitogen-activated protein kinase kinase 3 (MAP2K3) in the immortalization-senescence transition.


RESULTS
we identified 71 proteins whose expression changed upon induction of senescence. The identified proteins include regulators of cell growth, death, cell assembly and organization. Analysis of the network formed by the identified proteins suggested that the immortalization-to-senescence transition could affect regulators of the cell cycle, protein synthesis, transport, post-translational modifications, DNA recombination and repair, and lipid and amino acid metabolism. We observed that MAP2K3 was downregulated in immortal human breast epithelial cells and that upregulation of MAP2K3 expression promoted cell senescence. Decreased expression of MAP2K3 was observed in human breast infiltrating ductal carcinomas, as compared to non-cancerous human breast tissues.


CONCLUSIONS
we described a proteome profile of the immortalization-to-senescence transition for human breast epithelial cells, and identified MAP2K3 as a protein that promotes senescence in these cells.
Karolinska Biomics Center, Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden.
Min
M
Jia
Nazariy
N
Souchelnytskyi
Ulf
U
Hellman
Michael
M
O'Hare
Parmjit S
PS
Jat
Serhiy
S
Souchelnytskyi
D001940:Breast / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D002471:Cell Transformation, Neoplastic / Q000378:metabolism / Q000473:pathology; D016922:Cellular Senescence; D015536:Down-Regulation; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D048371:MAP Kinase Kinase 3 / Q000378:metabolism*; D020543:Proteome / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014407:Tumor Cells, Cultured
D020543:Proteome; D048371:MAP Kinase Kinase 3; C482530:MAP2K3 protein, human