BACKGROUND: Prostate cancer, non-cutaneous malignant tumor, is the second common cause of cancer related mortalities in American men and is responsible for 13% of deaths related to cancer. The present study investigated the anti-cancer effects of 3,6-diazabicyclo[3.3.1]heptane on LNCaP and PC3 prostate cancer cells in vitro and on tumor growth in vivo in BALB/C nude mice.

MATERIAL AND METHODS: Reduction of cell viability by 3,6-diazabicyclo[3.3.1]heptane was evaluated by sulphorhodamine-B staining and apoptosis onset using annexin V and propidium iodide (PI) staining. The 2’,7’-dichlorofluorescein-diacetate stain was used for assessment of reactive oxygen species (ROS) formation while as western blotting for analysis of protein expression.

RESULTS: The viability of LNCaP and PC3 cells was reduced significantly (P<0.05) by 3,6-diazabicyclo[3.3.1]heptane in dose-based manner. At 30 µM of 3,6-diazabicyclo[3.3.1]heptane the viability of LNCaP and PC3 cells was reduced to 32 and 28%, respectively. The 3,6-diazabicyclo[3.3.1]heptane treatment increased apoptosis in LNCaP cells to 43.31% at 30 µM. The cell cycle in LNCaP cells was arrested in G1 phase on treatment with 3,6-diazabicyclo[3.3.1]heptane. The expression of cyclin D1 and p21 proteins was significantly increased by 3,6-diazabicyclo[3.3.1]heptane in LNCaP and PC3 cells. The growth of prostate tumor was also suppressed in vivo in mice by 3,6-diazabicyclo[3.3.1]heptane treatment.

CONCLUSIONS: In summary, the study demonstrated that LNCaP and PC3 prostate cancer cell viability is suppressed by 3,6-diazabicyclo[3.3.1]heptane treatment. The suppression of prostate cancer cell viability by 3,6-diazabicyclo[3.3.1]heptane involves apoptosis induction, cell cycle arrest and upregulation of p21 expression. Therefore, 3,6-diazabicyclo[3.3.1]heptane can be a potential chemotherapeutic agent for prostate cancer.

Keywords: Cyclin-Dependent Kinase 4, Bridged Bicyclo Compounds, Heterocyclic, Cell Cycle Checkpoints, Cyclin-Dependent Kinase Inhibitor p21, Dose-Response Relationship, Drug, Heptanes, PC-3 cells, Prostate, Prostatic Neoplasms