title: Immortalization of bovine mammary epithelial cells alone by human telomerase reverse transcriptase.
abstract: Immortal bovine mammary epithelial cell lines are useful for providing an efficient indicator for transgene expression and for the technological improvement of genetic modification. The preparation of hTERT (human telomerase reverse transcriptase)-mediated immortalized MECs (mammary epithelial cells) requires a down-regulation of p16(INK4a). Here, we report the establishment of two immortal bovine MEC lines by expression of hTERT gene alone under serum-containing culture conditions. This two cell lines maintain the general characteristics of MECs and have been stably passed more than 200 generations accompanying telomere extension, and were identified as non-malignant transformation. Investigation on transcriptional profile showed a similar down-regulation in both p16(INK4a) and p53. By comparing with non-immortal hTERT-positive MECs, we speculated that there are some spontaneous p16(INK4a)-reduced cells under normal culture conditions and the immortalization required for a co-ordinate repression of p53 and p16(INK4a) signalling pathways. Interestingly, two immortal cell lines showed a significant distinction in proliferation rate, implying that other mechanisms might be involved in proliferation control.
authors.affiliation: National Key Laboratory for Agrobiotechnology, College of biological sciences, China Agricultural University, Yuanmingyuan Xi lu, Haidian District, Beijing 100193, People's Republic of China.
authors.forename: Chen-Fu
authors.initials: CF
authors.lastname: Zhao
authors.forename: Hong-Yu
authors.initials: HY
authors.lastname: Hu
authors.forename: Lu
authors.initials: L
authors.lastname: Meng
authors.forename: Qian-Qian
authors.initials: QQ
authors.lastname: Li
authors.forename: Ai-Xing
authors.initials: AX
authors.lastname: Lin
mesh_terms: D000818:Animals; D002417:Cattle; D002461:Cell Line, Transformed; D049109:Cell Proliferation; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D005260:Female; D006801:Humans; D008321:Mammary Glands, Animal / Q000166:cytology; D015398:Signal Transduction; D019098:Telomerase / Q000235:genetics* / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
chemical_list: D019941:Cyclin-Dependent Kinase Inhibitor p16; D016159:Tumor Suppressor Protein p53; C509186:TERT protein, human; D019098:Telomerase