2-[5-Selenocyanato-pentyl]-6-amino-benzo[de]isoquinoline-1,3-dione inhibits angiogenesis, induces p53 dependent mitochondrial apoptosis and enhances therapeutic efficacy of cyclophosphamide.

The present study embodies a detailed investigation of the chemoenhancement property of a synthetic organoselenium compound, 2-[5-selenocyanato-pentyl]-7-amino benzo[de]isoquinoline-1,3-dione (ANOS) in tumor bearing Swiss albino mice. The results accumulated from this study illustrated that the administration of ANOS significantly potentiated the therapeutic efficacy of cyclophosphamide by reducing the tumor burden and chemotherapy induced toxicity in the host. Ability of ANOS in inducing apoptosis and inhibiting angiogenesis was thought to be the crucial effecter for enhancing the therapeutic efficacy of cyclophosphamide. Fluorescence microscopic study revealed that ANOS was capable of penetrating tumor cells and distributed in the subcellular compartments. We showed that ANOS-induced apoptosis, as evidenced by the TUNEL assay and cleavage of poly(ADP-ribose) polymerase (PARP), involved ROS production and DNA damage in tumor cells. ROS production subsequently activated p53 phosphorylation at Ser-15. This in turn activated cytochrome c (cyt c) release from mitochondria via Bcl-2 and Bax. Finally activation of caspase 3 led to PARP cleavage and apoptosis. These results suggested that p53 dependent mitochondrial pathway was playing an important role in ANOS induced apoptosis of tumor cells. Administration of ANOS also resulted in significant improvement of tumor vasculature and sprouting of the peritoneal cavity along with the normalization of MMP-9 level in serum and ascites fluid of tumor bearing mice. This potential antiangiogenic activity of ANOS also facilitated the therapeutic efficacy of the combination therapy. Furthermore, ANOS significantly suppressed cyclophosphamide-induced liver, hematopoietic and genetic damages. A concomitant decrease in drug-induced toxicity by ANOS might also have enhanced the efficacy of cyclophosphamide by improving the intrinsic defense machineries of the host.