Novel human alpha-fetoprotein mRNA isoform lacking exon 1 identified in ovarian yolk sac tumor.
OBJECTIVE
Alpha-fetoprotein (AFP) is a major fetal serum protein, the biologic role of which has not been not fully elucidated. Recently, existence of a novel AFP mRNA isoform (del.1 AFP mRNA isoform), which is transcribed from the intron A (the intron between exons 1 and 2), has been reported in murine yolk sac and fetal liver. In the present study, we intended to identify the human homologue of the murine AFP mRNA isoform in the yolk sac tumor.


METHODS
To investigate the existence of the mRNA isoform (which we termed the "AFP-C mRNA isoform"), reverse transcription-polymerase chain reaction (RT-PCR) was used. Moreover, the expression analysis of the AFP-C cDNA isoform using the AFP-negative human cell line was carried out.


RESULTS
RT-PCR revealed the existence of the AFP-C mRNA isoform in the yolk sac tumor and human hepatocellular carcinoma cells. The expression analysis clarified that the molecular size of the AFP-C was approximately 65 kd, and that the protein was not secreted, in contrast to the traditional AFP.


CONCLUSIONS
From these results, the existence of the AFP-C mRNA isoform has been demonstrated for the first time in humans. The AFP-C located in cytoplasm possibly plays physiologic/pathogenic roles distinct from those of the traditional AFP in the yolk sac tumor and hepatocellular carcinoma.
Fukasawa
Hiroko
H
Department of Obstetrics and Gynecology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Nakakoma, Japan.
Iwamoto
Hideki
H
Hirata
Shuji
S
Shoda
Tomoko
T
Yokota
Sadaki
S
Nishi
Shinzo
S
Hoshi
Kazuhiko
K
D000230:Adenocarcinoma / Q000737:chemistry* / Q000473:pathology; D003593:Cytoplasm; D018240:Endodermal Sinus Tumor / Q000737:chemistry* / Q000473:pathology; D005260:Female; D006801:Humans; D010051:Ovarian Neoplasms / Q000737:chemistry* / Q000473:pathology; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured; D000509:alpha-Fetoproteins / Q000032:analysis / Q000737:chemistry*
D020033:Protein Isoforms; D012333:RNA, Messenger; D000509:alpha-Fetoproteins