title: Interaction of cyclophilin A with a novel binding protein, SR-25, and characterization of their expression pattern in Chinese hepatocellular carcinoma patients.
abstract: Cyclophilin (Cyp) A has been reported to be overexpressed in the majority of cancer cells, including hepatocellular carcinoma (HCC). However, the biological functions of CypA in HCC are far from being understood. To determine the biological functions of CypA in HCC, the present study screened human fetal liver complementary DNA for proteins interacting with CypA using the yeast two-hybrid system. A nuclear protein, serine/arginine-rich (SR)-25, was isolated as a novel CypA-binding protein that is distinct from those previously described in the literature. Binding assays and co-immunoprecipitation confirmed the physical association between CypA and SR-25. The present study demonstrated that CypA may interact with SR-25 through its peptidyl-prolyl isomerase domain. In addition, CypA may induce the expression of SR-25 in Hep3B cells. The messenger RNA levels of CypA and SR-25 in HCC indicated that there was a significant correlation between the expression of CypA and the expression of SR-25 in HCC. It can be speculated that the interaction between CypA and SR-25 proteins may be involved in potential carcinogenic functions of CypA in HCC. Further studies will focus on elucidating in detail the molecular mechanisms of the interaction between CypA and SR-25.
authors.affiliation: Department of Oncology, Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong 264000, P.R. China; Central Laboratory, Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong 264000, P.R. China.
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
authors.affiliation: Central Laboratory, Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong 264000, P.R. China.
authors.forename: Ning
authors.initials: N
authors.lastname: Li
authors.affiliation: Central Laboratory, Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong 264000, P.R. China.
authors.forename: Peiwen
authors.initials: P
authors.lastname: Lian
authors.affiliation: Central Laboratory, Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong 264000, P.R. China.
authors.forename: Jiahui
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Oncology, Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong 264000, P.R. China.
authors.forename: Peng
authors.initials: P
authors.lastname: Li
authors.affiliation: Department of Oncology, Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong 264000, P.R. China.
authors.forename: Zhaohua
authors.initials: Z
authors.lastname: Gong
authors.affiliation: Department of Gastrointestinal Surgery, Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong 264000, P.R. China.
authors.forename: Lixin
authors.initials: L
authors.lastname: Jiang
keywords: CypA; PPIase; SR-25; hepatocellular carcinoma