CRM-1 knockdown inhibits extrahepatic cholangiocarcinoma tumor growth by blocking the nuclear export of p27Kip1.
Cholangiocarcinoma is a deadly disease which responds poorly to surgery and conventional chemotherapy or radiotherapy. Early diagnosis is difficult due to the anatomical and biological characteristics of cholangiocarcinoma. Cyclin-dependent kinase inhibitor 1B (p27Kip1) is a cyclin‑dependent kinase inhibitor and in the present study, we found that p27Kip1 expression was suppressed in the nucleus and increased in the cytoplasm in 53 samples of cholangiocarcinoma from patients with highly malignant tumors (poorly-differentiated and tumor-node-metastsis (TNM) stage III-IV) compared with that in samples from 10 patients with chronic cholangitis. The expression of phosphorylated (p-)p27Kip1 (Ser10), one of the phosphorylated forms of p27Kip1, was increased in the patient samples with increasing malignancy and clinical stage. Coincidentally, chromosome region maintenance 1 (CRM-1; also referred to as exportin 1 or Xpo1), a critical protein responsible for protein translocation from the nucleus to the cytoplasm, was also overexpressed in the tumor samples which were poorly differentiated and of a higher clinical stage. Through specific short hairpin RNA (shRNA)-mediated knockdown of CRM-1 in the cholangiocarcinoma cell line QBC939, we identified an elevation of cytoplasmic p27Kip1 and a decrease of nuclear p27Kip1. Furthermore, the viability and colony formation ability of QBC939 cells was largely reduced with G1 arrest. Consistent with the findings of the in vitro experiments, in a xenograft mouse model, the tumors formed in the CRM-1 knockdown group were markedly smaller and weighed less than those in the control group in vivo. Taken together, these findings demonstrated that the interplay between CRM-1 and p27Kip1 may provide potentially potent biomarkers and functional targets for the development of future cholangiocarcinoma treatments.
Department of Geriatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China.
Jian
J
Luo
Department of Bile Duct and Pancreatic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China.
Yongjun
Y
Chen
Department of Gynecology and Obstetrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China.
Qiang
Q
Li
Department of Bile Duct and Pancreatic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China.
Bing
B
Wang
Department of Geriatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China.
Yanqiong
Y
Zhou
Department of Geriatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China.
Hongzhen
H
Lan
D021581:Active Transport, Cell Nucleus; D000328:Adult; D000368:Aged; D000818:Animals; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism*; D049109:Cell Proliferation; D018281:Cholangiocarcinoma / Q000378:metabolism* / Q000473:pathology*; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism*; D015536:Down-Regulation; D005260:Female; D055785:Gene Knockdown Techniques; D006801:Humans; D028884:Karyopherins / Q000378:metabolism*; D008297:Male; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008875:Middle Aged; D010766:Phosphorylation; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism; D014410:Tumor Stem Cell Assay; D000097606:Exportin 1 Protein
D050760:Cyclin-Dependent Kinase Inhibitor p27; D028884:Karyopherins; D018160:Receptors, Cytoplasmic and Nuclear; D000097606:Exportin 1 Protein