Objective: To investigate the differential protein expression profiles of human prostatic carcinoma cells with different metastatic tendency and to screen the osseous metastasis associated proteins and investigate their function.
Methods: Proteomics and Western blotting were applied to screen and identify the differentially expressed proteins in the prostatic carcinoma cells of different lines: line T3B with high osseous metastasis potential, line P2-4 with high lymphatic metastasis potential, and their common parent cell line PC-3. The eukaryotic expression vector carrying human Pgenesil-1/HMGB1 siRNA was constructed and transfected into T3B cells by Lipofectamine 2000 and the positive clones was screened by G418. Pgenesil-1/HMGB1 siRNA/T3B, Pgenesil-1/T3B, and T3B cells were inoculated into the left ventricles of nude mice. Twelve weeks later the mice were killed. The number of osseous metastatic nodules and osseous metastasis inhibition rate were calculated. The mice metastatic tumor cells were identified by immunohistochemistry.
Result: Six differential expressed proteins, correlated with cytoskeleton, transcriptional control, cellular metabolism, and phosphorylation were identified by proteomics and Western blotting. The recombinant plasmid Pgenesil-1/HMGB1 siRNA was successfully constructed. The HMGB1 expression of the T3B cells transfected with Pgenesil-1/HMGB1 siRNA was significantly lower than those of the other 2 groups (both P <0.05). The number of osseous metastatic nodules of the mice inoculated with Pgenesil-1/HMGB1 siRNA/T3B was significantly less than those of the other 2 groups (both P < 0.05). The metastatic osseous tumor cells were identified as the human prostatic carcinoma cells.
Conclusion: Osseous metastasis associated proteins exist in prostatic carcinoma cells of the line with high osseous metastasis potential. HMGB1 is closely related to the osseous metastasis of human prostatic carcinoma cells. siRNA targeting HMGB1 specifically suppresses the expression of HMGB1 gene in the human prostatic carcinoma cells with high osseous metastasis potential and effectively inhibits the osseous metastasis.