Antitumor effects of a novel benzonaphthofurandione derivative (8e) on the human colon cancer cells in vitro and in vivo through cell cycle arrest accompanied with the modulation of EGFR and mTOR signaling

Benzonaphthofurandione has been considered as an important class of naturally occurring and synthetic compounds having a variety of biological functions. In this study, we evaluated the antitumor effects of 3-[2-(dimethylamino)isopropoxy]-1-hydroxybenzo[b]naphtho[2,3-d]furan-6,11-dione (8e), a novel benzonaphthofurandione derivative, on the growth of colorectal cancer HCT 116 cells both in vitro culture and an in vivo animal model.Compound 8e exhibited the potential growth inhibition of the colon cancer cells in a concentration-dependent manner. The anti-proliferative activity of 8e was also associated with the induction of cell cycle arrest in the G₀/G₁ phase. The 8e-induced cell cycle arrest was well correlated with the suppression of cyclin-dependent kinase 2 (CDK2), CDK4, cyclin D1, cyclin E, c-Myc, and phosphorylated retinoblastoma protein (pRb). The tumor growth in xenograft nude mice bearing HCT 116 cells by compound 8e (10 mg/kg) also significantly inhibited without any overt toxicity. In addition, the down-regulation of epidermal growth factor receptor (EGFR), Akt, and mTOR signalings were associated with the anti-proliferative activity of compound 8e in colon cancer cells. Taken together, these findings suggested that cell cycle arrest and modulation of cell signal transduction pathways might be the plausible mechanisms of actions for the anti-proliferative activity of 8e, and thus 8e might be used as an effective chemotherapeutic agent in human colon cancer.