Increased expression of iASPP, regulated by hepatitis B virus X protein-mediated NF-κB activation, in hepatocellular carcinoma.
OBJECTIVE
iASPP is an inhibitory member of the ankyrin-repeat-, SH3-domain- and proline-rich-region-containing protein (ASPP) family; iASPP expression is up-regulated in different human tumor types. We explored the molecular mechanism increased expression of iASPP and its role in hepatocellular carcinoma (HCC).


METHODS
iASPP expression levels in human liver samples and cell lines were determined by polymerase chain reaction, immunoblot, and immunohistochemical analyses. Luciferase reporter, chromatin immunoprecipitation, and electrophoretic mobility shift assays were used to measure transcriptional activation by nuclear factor-κB (NF-κB). Effects on tumor growth were characterized with MTS, soft agar colony formation, and flow cytometry analyses. Tumorigenicity of cells was studied in nude mice.


RESULTS
Compared with normal liver cells or tissues, iASPP was expressed at significantly higher levels in HCC cell lines (9/14) and liver samples from patients with HCC, cirrhosis, or hepatitis B virus infection. Increased expression of iASPP was significantly associated with time to recurrence and survival time of patients with HCC. NF-κB activation increased the expression of iASPP through p65/p50 binding to a putative NF-κB-binding site in the iASPP promoter; hepatitis B virus X gene product might up-regulate expression of iASPP. Transgenic expression of iASPP promoted tumor cell proliferation and resistance to chemotherapeutic drugs in vitro and in vivo.


CONCLUSIONS
iASPP is up-regulated in HCC; it is a direct transcription target of NF-κB. Increased iASPP expression contributes to tumor progression by proliferative and antiapoptotic effects. iASPP might be developed as an HCC therapeutic target or to sensitize cancer cells to chemotherapeutic drugs; it might also be used as a prognostic factor.
Lu
Bin
B
International Joint Cancer Institute, The Second Military Medical University, Shanghai, China.
Guo
Huaizu
H
Zhao
Jian
J
Wang
Chong
C
Wu
Guobin
G
Pang
Mingshu
M
Tong
Xin
X
Bu
Fangfang
F
Liang
Anmin
A
Hou
Sheng
S
Fan
Xiaoyu
X
Dai
Jianxin
J
Wang
Hao
H
Guo
Yajun
Y
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy / Q000235:genetics / Q000821:virology; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology; D015967:Gene Expression Regulation, Viral / Q000502:physiology; D019694:Hepatitis B, Chronic / Q000150:complications*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics*; D008113:Liver Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000821:virology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D016328:NF-kappa B / Q000378:metabolism*; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000502:physiology; D012097:Repressor Proteins / Q000235:genetics*; D015534:Trans-Activators / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology; D054334:Viral Regulatory and Accessory Proteins; D023041:Xenograft Model Antitumor Assays
D000970:Antineoplastic Agents; D047908:Intracellular Signaling Peptides and Proteins; D016328:NF-kappa B; C119612:PPP1R13L protein, human; D012097:Repressor Proteins; D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein