title: Normal cells, but not cancer cells, survive severe Plk1 depletion.
abstract: We previously reported the phenotype of depletion of polo-like kinase 1 (Plk1) using RNA interference (RNAi) and showed that p53 is stabilized in Plk1-depleted cancer cells. In this study, we further analyzed the Plk1 depletion-induced phenotype in both cancer cells and primary cells. The vector-based RNAi approach was used to evaluate the role of the p53 pathway in Plk1 depletion-induced apoptosis in cancer cells with different p53 backgrounds. Although DNA damage and cell death can occur independently of p53, p53-deficient cancer cells were much more sensitive to Plk1 depletion than cancer cells with functional p53. Next, the lentivirus-based RNAi approach was used to generate a series of Plk1 hypomorphs. In HeLa cells, two weak hypomorphs showed only slight G2/M arrest, a medium hypomorph arrested with 4N DNA content, followed later by apoptosis, and a strong Plk1 hypomorph underwent serious mitotic catastrophe. In well-synchronized HeLa cells, a medium level of Plk1 depletion caused a 2-h delay of mitotic progression, and a high degree of Plk1 depletion significantly delayed mitotic entry and completely blocked cells at mitosis. In striking contrast, normal hTERT-RPE1 and MCF10A cells were much less sensitive to Plk1 depletion than HeLa cells; no apparent cell proliferation defect or cell cycle arrest was observed after Plk1 depletion in these cells. Therefore, these data further support suggestions that Plk1 may be a feasible cancer therapy target.
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Ave., Cambridge, MA 02138, USA. liu13@fas.harvard.edu
authors.forename: Xiaoqi
authors.initials: X
authors.lastname: Liu
authors.forename: Ming
authors.initials: M
authors.lastname: Lei
authors.forename: Raymond L
authors.initials: RL
authors.lastname: Erikson
mesh_terms: D017209:Apoptosis / Q000235:genetics; D002453:Cell Cycle / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D002461:Cell Line, Transformed; D002478:Cells, Cultured; D006367:HeLa Cells; D006801:Humans; D016086:Lentivirus / Q000235:genetics; D008938:Mitosis; D009369:Neoplasms / Q000235:genetics / Q000473:pathology*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D034622:RNA Interference; D012016:Reference Values; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D000097869:Polo-Like Kinase 1
chemical_list: D018797:Cell Cycle Proteins; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D016159:Tumor Suppressor Protein p53; D000097869:Polo-Like Kinase 1