title: Biological characterization of bovine mammary epithelial cell lines immortalized by HPV16 E6/E7 and SV40T.
abstract: Primary bovine mammary epithelial cells are not ideal models for long-term studies, because primary cells undergo a limited number of proliferations in vitro and enter into a growth-arrest stage called cell replicative senescence; we therefore must establish the immortalized bovine mammary epithelial cells (BMECs) in vitro. More importantly, the mechanisms of the relationship between immortalized and apoptotic cell remain unknown in BMECs. We therefore sought to elucidate the mechanisms of which immortalized cells escape the pathway of apoptotic signal. These cells were successfully immortalized without any signs of senescence. The maximum number of BMEC and E6E7 immortalized cells were reached after 6 d of culture. At this point, there were significantly more E6E7 immortalized cells than primary BMECs (P < 0.01). The population-doubling times of the E6E7 and SV40T immortalized cells were lowest at 48 and 72 h. We failed to detect the expression of the epithelial cell marker E-cadherin in BMECs; however, immortalized cells had low expression of E-cadherin. The expression of β-catenin was markedly expressed in immortalized cells than in BMECs (P < 0.01). Caspase-3, caspase-9, and poly ADP-ribose polymerase (PARP) were detected; however, the cleavage of caspase-3 and PARP was not observed. Our data demonstrate that the expressions of caspase-9, caspase-3, and PARP are not sufficient for the apoptosis of immortalized cells and suggest that E-cadherin and β-catenin might be an important indicator of the development of cancer.
authors.affiliation: College of Animal Science and Technology, Yangzhou University, Yangzhou, 225009, China.
authors.forename: Kang
authors.initials: K
authors.lastname: Zhan
authors.affiliation: College of Animal Science and Technology, Yangzhou University, Yangzhou, 225009, China.
authors.forename: Miao
authors.initials: M
authors.lastname: Lin
authors.affiliation: College of Animal Science and Technology, Yangzhou University, Yangzhou, 225009, China.
authors.forename: Qian-Ming
authors.initials: QM
authors.lastname: Zhao
authors.affiliation: College of Animal Science and Technology, Yangzhou University, Yangzhou, 225009, China.
authors.forename: Jin-Shun
authors.initials: JS
authors.lastname: Zhan
authors.affiliation: College of Animal Science and Technology, Yangzhou University, Yangzhou, 225009, China. gqzhao@yzu.edu.
authors.forename: Guo-Qi
authors.initials: GQ
authors.lastname: Zhao
mesh_terms: D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000378:metabolism*; D017209:Apoptosis; D015415:Biomarkers / Q000378:metabolism; D002417:Cattle; D002461:Cell Line, Transformed; D049109:Cell Proliferation; D004847:Epithelial Cells / Q000378:metabolism*; D005260:Female; D005455:Fluorescent Antibody Technique; D008321:Mammary Glands, Animal / Q000166:cytology*; D009856:Oncogene Proteins, Viral / Q000378:metabolism*; D050725:Papillomavirus E7 Proteins / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism*
chemical_list: D000952:Antigens, Polyomavirus Transforming; D015415:Biomarkers; C068651:E6 protein, Human papillomavirus type 16; D009856:Oncogene Proteins, Viral; D050725:Papillomavirus E7 Proteins; D012097:Repressor Proteins; C059731:oncogene protein E7, Human papillomavirus type 16
keywords: Apoptosis; Bovine; Growth; Immortalized