Cytoplasmic immunoreactivity of thyroid transcription factor-1 (clone 8G7G3/1) in hepatocytes: true positivity or cross-reaction?
The nuclear immunoreactivity for thyroid transcription factor-1 (TTF-1) is a useful marker for identification of carcinomas of thyroid and lung origin. Our aim was to determine whether cytoplasmic staining in the liver is a result of cross-reaction of anti-TTF-1 antibody (clone 8G7G3/1, DAKO, Carpinteria, CA) or true positivity resulting from aberrant expression of TTF-1 or products of the alternatively sliced TTF-1 gene. Fresh tissue samples from liver, thyroid, and lung were obtained for H&E-stained sections, TTF-1 immunostaining, and RNA and protein analyses. Western blot revealed an abundant band corresponding to an approximately 160-kd protein from liver but not either thyroid or lung tissue samples. By reverse transcriptase-polymerase chain reaction, messenger RNA of TTF-1 was not detectable in liver tissue. Our study demonstrates that TTF-1 immunoreactivity (clone 8G7G3/1) in the hepatocyte cytoplasm is due to an approximately 160-kd protein; this unique protein is not an alternative splicing product of TTF-1 and neither is it expressed in thyroid and lung tissues.
Gu
Keni
K
Department of Pathology, Medical College of Georgia, Augusta, GA 30912, USA.
Shah
Veena
V
Ma
Chan
C
Zhang
Lixin
L
Yang
Maozhou
M
D017398:Alternative Splicing; D000906:Antibodies / Q000378:metabolism; D003429:Cross Reactions; D003593:Cytoplasm / Q000737:chemistry*; D022781:Hepatocytes / Q000737:chemistry*; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000378:metabolism; D009687:Nuclear Proteins / Q000032:analysis* / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013961:Thyroid Gland / Q000737:chemistry; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors / Q000032:analysis* / Q000276:immunology
D000906:Antibodies; C000614412:NKX2-1 protein, human; D009687:Nuclear Proteins; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors