Cloning and Characterization of a Cell Senescence Gene for Breast Cancer Cells

摘要

Applying a functional strategy, starting with the transfer of an intact chromosome 16 into breast tumor cells, we identified a replicative senescence gene, SENl6, at l6q24.3. Positional information led to the isolation of a BAC clone that restores normal growth pattern and senescence in immortal breast tumor cells. The nucleotide sequences of cDNA clones, located on the BAC, were compared to recognize overlapping clones. Four full- length cDNAs, representing three genes, were assembled from the sequence of partial cDNAs and cloned into a mammalian cell expression vector. Ectopic expression of one of the full-length cDNA led to growth inhibition and senescence in breast cancer cells. In silico analysis of the gene revealed that predicted protein is a part of an ubiquitin-ligase complex involved in protein degradation pathway. Malfunctioning of an ubiquitin dependent protein degradation pathway may contribute to the development of cancer through the deregulation of cell cycle control mechanisms. Our data show that SENl6 is a growth regulatory gene involved in the etiology of breast cancer. Further characterization of SENl6, for the identification of signaling pathways will afford insight into the regulation of cell growth and senescence, which eventually may lead to the development of new diagnostic and therapeutic strategies.