BACKGROUND: Signal regulatory protein alpha1 (Sirpα1) is a negative regulatory factor, and inhibits receptor tyro- sine kinase-dependent cell proliferating signal. This study was undertaken to observe the effect of signal regulatory proteinα1 ( Sirpα1) on gankyrin, cyclin D1, CDK4 and Fas expression in Sk-hep1 mouse hepatoma carcinoma cell line. METHODS: BOSC 23 packed cells were respectively trans- fected by means of recombinated retrovirus including pLX- SN, pLXSN-Sirpα1 and pLXSN-Sirpα1Δ4Y2 with lipofec- tin, and various plasmid virus media (viral titer 2.1 × 106 CFU/ml) were collected and infected respectively in 80% confluent Sk-hepl cells. Transfected Sk-hep1 cells were se- lectively screened with G418 (1200 μg/ml), and Sk-hep1 cell lines transfected with various plasmids were obtained. The protein expressions of gankyrin, cyclin D1, CDK4 and Fas in various Sk-hep1 lines were determined by Western blotting. Various Sk-hep1 lines were recovered to culture with 10% fetal bovine serum at 12 hours and 24 hours after starving culture with free serum for 72 hours, and cells were collected to determine the percentage of S phase cells of proliferating cycle by flow cytometry. RESULTS: Sirpα1 transfection remarkably downregulated gankyrin and cyclin D1 expression. Sirpα1Δ4Y2 downregu- lation of gankyrin expression was greater than that of Sirpα1(P <0.05), but no significant effect of Sirpα1 and Sirpα1Δ4Y2 on CDK4 and Fas protein expression was ob- served in transfected Sk-hep1 lines (P >0.05). The per- centage of S phase cells significantly decreased in Sk-hep1 cells transfected with Sirpα1 and Sirpα1Δ4Y2 plasmids (vs pLXSN Sk-hep1, P <0.05). The percentage of S phase cells in various Sk-hep1 cells increased when recovering to culture with 10% fetal bovine serum at 12 hours, but the percentage of S phase cells in Sk-hep1 cells transfected with Sirpα1 was the lowest ( vs pLXSN and Sirpα1Δ4Y2 Sk- hepl, P<0.05). The percentage of S phase cells in trans- fected pLSXN Sk-hep1 cells was the largest (v
Jian-Min Qin, He-Xin Yan, Xing-Wang Wan, Shu-Qin Liu, Jin-Zhang Zeng, Hui-Fang Cao, Meng-Chao Wu and Hong-Yang Wang Shanghai, China International Cooperative Laboratory on Signal Trans- duction, Eastern Hepatobiliary Surgery Institute, Second Military Medical University, Shanghai 200438, China
