Disturbed expression of type 1 iodothyronine deiodinase splice variants in human renal cancer.
BACKGROUND
Alternative splicing, one of the sources of protein diversity, is often disturbed in cancer. Type 1 iodothyronine deiodinase (DIO1) catalyzes deiodination of thyroxine generating triiodothyronine, an important regulator of cell proliferation and differentiation. The expression of DIO1 is disturbed in different types of cancer. The aim of the study was to analyze the alternative splicing of DIO1 and its possible disturbance in renal cancer.


METHODS
Using real-time PCR, we analyzed 19 tissue samples (T) of renal cancer and 19 matched control samples (C) of the opposite pole of the kidney, not infiltrated by tumor, and 6 control samples (N) (nonneoplastic kidney abnormalities).


RESULTS
Cloning of DIO1 mRNA isoforms revealed 11 different transcripts, among them 7 new splice variants, not previously reported. The expression of all variants of DIO1 was dramatically (>90%) and significantly (p < or = 0.0003) lowered in samples T compared to control samples C. The ratio of mRNA isoforms encoding DIO1 protein variants possessing or lacking the active center was lowered in samples T compared with control samples C, suggesting disturbed alternative splicing of DIO1. The expression of mRNA of splicing factors SF2/ASF (splicing factor-2/alternative-splicing factor) and hnRNPA1 (heterogeneous ribonucleoprotein A1), regulating 5'-splice site selection, was significantly but not proportionally lowered in samples T compared to samples C. The mRNA ratio of splicing factors SF2/ASF and hnRNPA1 correlated with the ratio of mRNA isoforms encoding DIO1 protein variants possessing or lacking the active center in controls C but not in samples T.


CONCLUSIONS
Our results show that the expression and alternative splicing of DIO1 mRNA is disturbed in renal cancer, possibly due to changes in expression of splicing factors SF2/ASF and hnRNPA1.
Piekielko-Witkowska
Agnieszka
A
Department of Biochemistry and Molecular Biology, The Medical Center of Postgraduate Education, 01-813 Warsaw, Poland.
Master
Adam
A
Wojcicka
Anna
A
Boguslawska
Joanna
J
Brozda
Izabela
I
Tanski
Zbigniew
Z
Nauman
Alicja
A
D003001:Cloning, Molecular; D017931:DNA Primers; D030541:Databases, Genetic; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics*; D006801:Humans; D007453:Iodide Peroxidase / Q000235:genetics*; D007680:Kidney Neoplasms / Q000235:genetics*; D020033:Protein Isoforms / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017931:DNA Primers; D020033:Protein Isoforms; D012333:RNA, Messenger; C109812:iodothyronine deiodinase type I; D007453:Iodide Peroxidase