[Interferon-alpha upregulates thymidine phosphorylase expression via JAK-STAT transcriptional activation and mRNA stabilization in human hepatocellular carcinoma SMMC-7721 cells].
OBJECTIVE
To examine how the thymidine phosphorylase (TP) gene expression is upregulated by interferon-alpha (IFN-alpha) in human hepatocellular carcinoma SMMC-7721 cells.


METHODS
TP mRNA levels were determined by RT-PCR. Whether the JAK-STAT cascade mediates IFN-alpha-induced TP mRNA expression was studied by pretreatment with Janus Kinase (JAK) inhibitor, AG-490. Effects of IFN-alpha on TP mRNA stability were detected with additional actinomycin D.


RESULTS
The expression of TP mRNA was induced by IFN-alpha in a dose- and time-dependent manner in SMMC-7721 (human hepatocellular carcinoma) cells. TP mRNA levels rose at 8 h, reached the peak value at 12 h, and remained at a high level up to 72 h in SMMC-7721 cells treated with IFN-alpha 10000 U/ml. IFN-alpha at a dose of 5000 or 10000 U/ml up-regulated TP expression about 3 fold compared with that of non-treated cells (P < 0.05). Induction of TP mRNA expression by IFN-alpha was significantly inhibited in SMMC-7721 cells by pretreatment with AG-490, in comparison with that treated with IFN-alpha alone. Pretreatment of SMMC-7721 cells with IFN-alpha 10000 U/ml for 24 h caused a substantial stabilization of TP mRNA, with a half-live of 35.8 h, compared with 8.5 hr in the control SMMC-7721 cells.


CONCLUSIONS
IFN-alpha at certain doses upregulates TP mRNA expression via both JAK-STAT transcriptional activation and post-transcriptional mRNA stabilization in human hepatocellular carcinoma SMMC-7721 cells.
Xiao
Yong-sheng
YS
Liver Cancer Institute and Zhongshan Hospital, Fudan University, Shanghai 200032, China.
Zhou
Jian
J
Fan
Jia
J
Sun
Qi-man
QM
Zhao
Yan
Y
Sun
Rui-xia
RX
Liu
Yin-kun
YK
Tang
Zhao-you
ZY
D006528:Carcinoma, Hepatocellular / Q000201:enzymology* / Q000473:pathology; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D016898:Interferon-alpha / Q000008:administration & dosage / Q000494:pharmacology*; D053612:Janus Kinases / Q000378:metabolism; D008113:Liver Neoplasms / Q000201:enzymology* / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D050794:STAT1 Transcription Factor / Q000378:metabolism; D013939:Thymidine Phosphorylase / Q000096:biosynthesis* / Q000235:genetics; D015533:Transcriptional Activation / Q000187:drug effects; D020032:Tyrphostins / Q000494:pharmacology
D004791:Enzyme Inhibitors; D016898:Interferon-alpha; D012333:RNA, Messenger; D050794:STAT1 Transcription Factor; D020032:Tyrphostins; C095512:alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide; D013939:Thymidine Phosphorylase; D053612:Janus Kinases