Prostate cancer develops in the prostate, which is a gland in the male reproductive system. Prostate cancers generally grow slowly. However, aggressive prostate cancers do occur, which are capable of metastasizing from the prostate to other parts of the body, particularly the bones and lymph nodes. Transforming growth factor β (TGFβ) signaling pathway has been shown to play a critical role in the tumorigenesis of prostate cancer. TGFβ signaling pathways are involved in many biological events. SMAD2 and SMAD3 are key plays that typically mediate TGFβ receptor signaling. They are phosphorylated by the activated TGFβ receptor I in the cytosol (pSMAD2 and pSMAD3) and then translocate into the nucleus to exert many biological functions through directly binding to the DNA. Specifically, pSMAD2 and pSMAD3 have been shown to inhibit cell growth through regulation of cell-cycle controllers.Moreover, they may regulate matrix metalloproteinases (MMPs) to control cell metastasis.
Ginsenoside Rh2 (GRh2) is one of the characteristic components in red ginseng with potential bioactivity. GRh2 has been shown to have potentially therapeutic effects on various cancers and on enteritis. Nevertheless, the exact molecular basis of the anti-tumor effect of GRh2 remains unclear. Here, we show that GRh2 can substantially inhibit the growth of prostatic cancer in vivo and in vitro, resulting from a combined inhibitory effect on tumor cell proliferation and tumor cell invasiveness. Further, GRh2 seemed to activate TGFβ receptor signaling in prostatic cancer cells, which subsequently inhibits cell proliferation and invasion through regulating cell cycle controllers and MMPs, respectively.
Materials and methods
Culture and label human prostatic cancer cell line with a luciferase reporter Human prostatic cancer cell line PC3 has been described before and was maintained in Dulbecco’s modified Eagle’s medium (DMEM) supplemented with 10 % fetal bovine serum. To trace the PC3 cells in vivo, we infected the cells with a recombinant lentivirus expressing luciferease and GFP under the control of CMV promoter at MOI 100 and resulted in nearly 100 % infection efficiency based on green fluorescence. The reporter-carrying PC3 cells were termed PC3-luc. GRh2 (0.1 mg/ml) was given to the cultured cells for intervention.
Twelve-week-old male nude mice were used for experiments. GRh2 (1 mg/kg body weight) was injected from the tail vein of the mice twice per week for 4 weeks until the end of the experiment. Controlmice received saline injection of same volume.
Induction of prostatic cancer
PC3-luc cells (105) were stereotactically implanted into the prostate of 12-week-old male nude mice as has been previously described. One month after, the animals were examined of tumor growth by luciferin assay.
GRh2 efficiently inhibited the growth of prostatic cancer in vivo Human prostatic cancer cell line PC3 has been described before and was used in the current study. To trace the PC3 cells in vivo, we infected the cells with a recombinant lentivirus expressing luciferease and GFP under the control of CMV promoter at MOI 100 and resulted in nearly 100 % infection efficiency based on green fluorescence. The reporter-carrying PC3-luc cells were stereotactically injected into the prostate of 12-week-old male nude mice. GRh2 was then intravenously administrated at a concentration of 1mg/kg body weight to the mice, twice per week for 4 weeks. The control mice received injection of saline of same volume. After 4 weeks, the animals were examined of tumor growth by luciferin assay. We found that the bioluminescence levels in the GRh2-treated mice were lower than those in control mice by 83.5±10.5 %, suggesting that GRh2 efficiently inhibited the growth of prostatic cancer in vivo.
Qingchuan Zhang & Bin Hong & Songhua Wu & Tianli Niu. Tumor Biol. (2015) 36:2377–2381