Identification of a human TFPI-2 splice variant that is upregulated in human tumor tissues.
BACKGROUND
Previous studies have shown that the expression of tissue factor pathway inhibitor-2 (TFPI-2), a matrix-associated Kunitz-type serine proteinase inhibitor, is markedly down-regulated in several tumor cells through hypermethylation of the TFPI-2 gene promoter. In the present study, RT-PCR analysis of total RNA from both human normal and tumor cells revealed a novel 289 nucleotide splice variant of the TFPI-2 transcript designated as aberrantly-spliced TFPI-2 (asTFPI-2).


RESULTS
Nucleotide sequence analyses indicated that asTFPI-2 consists of complete exons II and V, fused with several nucleotides derived from exons III and IV, as well as six nucleotides derived from intron C. 5'- and 3'-RACE analyses of total RNA amplified exclusively the wild-type TFPI-2 transcript, indicating that asTFPI-2 lacks either a 5'-untranslated region (UTR) or a 3'-poly (A)+ tail. Quantitative real-time RT-PCR analyses revealed that several human tumor cells contain 4 to 50-fold more copies of asTFPI-2 in comparison to normal cells. In spite of the absence of a 5'-UTR or poly (A)+ tail, the asTFPI-2 variant exhibited a half-life of ~16 h in tumor cells.


CONCLUSIONS
Our studies reveal the existence of a novel, aberrantly-spliced TFPI-2 transcript predominantly expressed in tumor cells and provides suggestive evidence for an additional mechanism for tumor cells to down-regulate TFPI-2 protein expression enhancing their ability to degrade the extracellular matrix.
Kempaiah
Prakasha
P
Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM, USA. pkempaiah@salud.unm.edu
Chand
Hitendra S
HS
Kisiel
Walter
W
D020121:5' Untranslated Regions / Q000235:genetics; D045744:Cell Line, Tumor / Q000187:drug effects / Q000378:metabolism; D003609:Dactinomycin / Q000494:pharmacology; D005091:Exons / Q000235:genetics; D006023:Glycoproteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D006207:Half-Life; D006801:Humans; D007438:Introns / Q000235:genetics; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D009928:Organ Specificity; D011061:Poly A / Q000235:genetics; D012326:RNA Splicing; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D012334:RNA, Neoplasm / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic / Q000187:drug effects; D015854:Up-Regulation; D014781:Viscera / Q000378:metabolism
D020121:5' Untranslated Regions; D006023:Glycoproteins; D009363:Neoplasm Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D012333:RNA, Messenger; D012334:RNA, Neoplasm; C021240:tissue-factor-pathway inhibitor 2; D003609:Dactinomycin; D011061:Poly A