title: Expression of Polo-Like Kinase (PLK1) in non-Hodgkin's lymphomas.
abstract: Polo-like kinases (PLKs) are protein serine/threonine kinases that play important roles in cell division. Expression of PLK1 might, moreover, play a role in the pathogenesis of human neoplasms. The expression of PLK1 mRNA is closely correlated with survival in patients with malignant tumors. We investigated the expression of PLK1 in non-Hodgkin's lymphomas (NHLs) and analyzed the relationships between expression of PLK1, histological grade, and prognosis. We analyzed various types of NHLs from 118 patients using monoclonal antibodies against PLK1 and Ki-67. The levels of expression of PLK1 and Ki-67 were significantly lower in low-grade NHLs than in high-grade and intermediate-grade NHLs (P < 0.001). Moreover, when patients were grouped in terms of 5-year overall survival ( > 70%, group A; 50 - 70%, group B; 30 - 49%, group C; and < 30%, group D), levels of expression of PLK1 and Ki-67 were found to be significantly higher in group D than in group A and they were also significantly higher in group C than in group A (P < 0.001). Conversely, the level of expression, of Ki-67 was significantly lower in group D than in group C (P < 0.05). The labeling indices specific for PLK1 were generally higher than those specific for Ki-67. Once we divided all patients into two groups in terms of the expression levels, high-level expression group of PLK1 (PLK1 index of 70%) and Ki-67 (Ki-67 indices of 60%) and low-level expression, one of these markers (PLK1 index of >/= 70%, Ki-67 indices of >/= 60%) had a similar prognosis, an observation that can be explained by the fact that rapidly proliferating group is more drug-sensitive than the other. Our study demonstrates that expression of PLK1 might reflect the malignant potential of NHLs and that PLK1 might be more useful than Ki-67 for the detection of proliferative cells.
authors.affiliation: Department of Pathology, Faculty of Medicine, Oita University, Japan. kmito@med.oita-u.ac.jp
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Mito
authors.forename: Kenji
authors.initials: K
authors.lastname: Kashima
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kikuchi
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Daa
authors.forename: Iwao
authors.initials: I
authors.lastname: Nakayama
authors.forename: Shigeo
authors.initials: S
authors.lastname: Yokoyama
mesh_terms: D000951:Antigens, Neoplasm / Q000032:analysis; D018797:Cell Cycle Proteins / Q000032:analysis / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D019394:Ki-67 Antigen / Q000032:analysis; D008228:Lymphoma, Non-Hodgkin / Q000737:chemistry / Q000175:diagnosis / Q000201:enzymology* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011494:Protein Kinases / Q000032:analysis / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000235:genetics*; D012334:RNA, Neoplasm / Q000032:analysis; D012189:Retrospective Studies; D016019:Survival Analysis; D000097869:Polo-Like Kinase 1
chemical_list: D000951:Antigens, Neoplasm; D018797:Cell Cycle Proteins; D019394:Ki-67 Antigen; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D012334:RNA, Neoplasm; D000097869:Polo-Like Kinase 1