title: [The expression and clinical significance of keratin 19, 20 mRNA in different tumor cell lines and tumor tissues].
abstract: OBJECTIVE
  To study the expression of keratin 19, 20 (K19, K20) in different tumor cell lines and tumor tissues and its clinical implication.
  
  
  METHODS
  Quantitative reverse transcription-polymerase chain reaction (RT-PCR) was employed to examine the specific expression of K19 and K20 mRNA in eleven tumor cell lines and 33 corresponding tumor tissue specimens.
  
  
  RESULTS
  The expression of K19 mRNA was detected in 4 kinds of tumor cell lines and all tumor tissues examined, but the magnitude of expression differed, with a difference ranging from 1.7 to 10 folds for the same type of cancer. In some patients, the level of expression was as low as 12% of the positive control. K20 mRNA expression was negative for lung and esophageal tumor cell lines and the corresponding carcinoma specimens. In one of 6 bladder cancer specimens and in 4 of 5 colorectal cancer tissues, K20 expression was positive, at a level of 41%-77% of the positive control. There was no expression of K20 in bladder tumor cell line EJ1 and colorectal tumor cell line SW480.
  
  
  CONCLUSIONS
  These results demonstrate that K19 and K20 may be used as a valuable marker for detecting circulating cancer cells, but the low level of expression in some cases of carcinoma would probably result in false negative results.
authors.affiliation: Department of Immunology, Institute of Clinical Medical Sciences, China-Japan Friendship Hospital, Beijing 100029, China.
authors.forename: L
authors.initials: L
authors.lastname: Qhiu
authors.forename: X
authors.initials: X
authors.lastname: Cong
authors.forename: L
authors.initials: L
authors.lastname: Ja
mesh_terms: D014408:Biomarkers, Tumor / Q000096:biosynthesis*; D015179:Colorectal Neoplasms / Q000378:metabolism; D015536:Down-Regulation; D004938:Esophageal Neoplasms / Q000378:metabolism; D006801:Humans; D007381:Intermediate Filament Proteins / Q000096:biosynthesis* / Q000235:genetics; D053554:Keratin-20; D007633:Keratins / Q000096:biosynthesis* / Q000235:genetics; D008175:Lung Neoplasms / Q000378:metabolism; D009369:Neoplasms / Q000378:metabolism*; D009360:Neoplastic Cells, Circulating / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured / Q000378:metabolism; D001749:Urinary Bladder Neoplasms / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; D007381:Intermediate Filament Proteins; C507499:KRT20 protein, human; D053554:Keratin-20; D012333:RNA, Messenger; D007633:Keratins