Richard Waters posted an update 1 week, 4 days ago
A standard drug that has been extensively employed for over 2000 years in China (Chen et al., 1996; Aposhian, 1997; Miller Jr et al., 2002). Lately, clinical information have shown that As2O3 induces total remission of acute promyelocytic leukemia (APL) without having any significant unwanted effects (Shen et al., 1997; Soignet et al., 1998; Zhang et al., 2001). You’ll find a lot of reports on the proapoptotic effects of As2O3 in malignant cell lines via complicated signaling pathways, with a number of clinic trials being conducted on hematopoietic malignancies and strong tumors (Shen et al., 1997; Wang et al., 1998; Bazarbachi et al., 1999; Jing et al., 1999; Rousselot et al., 1999; Perkins et al., 2000; Anderson et al., 2002; Miller Jr et al., 2002). Remarkably, it has been suggested that arsenite may well directly target mitochondrial PTP to induce apoptosis in cancerous cells (Petronilli et al., 1994; Costantini et al., 1996; Larochette et al., 1999), though the precise molecular mechanism continues to be elusive. Right here, we supply for the initial time the genetic and biochemical proof that VDAC is amongst the biological targets responsible for induction of cyto cNIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptOncogene. Author manuscript; accessible in PMC 2010 August 2.Zheng et al.Pagerelease and apoptosis by As2O3. A complete understanding of your molecular mechanism of this ancient remedy may be helpful to develop superior therapeutic drugs for fighting cancer.NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptResultsAs2O3 induces apoptosis, reduction of m, and release of cyto c from mitochondria in a Bcl-2 inhibitable manner We employed a clinically relevant concentration of As2O3 to treat a many myeloma cell line IM-9 for 24 h and assayed for the exposure of phosphotydyl-serine on the plasma membrane, indicative of apoptosis. FACS analysis showed that As2O3 induced a important boost on the population of Annexin Vhigh/PIlow IM-9 cells (Figure 1a). This outcome clearly demonstrated that As2O3 could properly induce apoptosis in many myeloma cells. Overexpression of Bcl-2 in IM-9/Bcl-2 cells, which we’ve shown previously to suppress ionizing radiation-induced apoptosis (Chen et al., 2000, 2003), also inhibited As2O3-induced apoptosis (Figure 1a). Furthermore, the detection of cytoplasmic cyto c from IM-9 cells TAK-700 Cancer treated with 2 As2O3 showed the appearance of cyto c starting 12 h following treatment (Figure 1c), concomitant with all the reduction of m (Figure 1b), the onset of caspase three activity (information not shown), and Annexin V positivity. However, As2O3-induced release of cyto c in the IM-9/Bcl-2 cell line was considerably reduced plus the reduction of m was prevented (Figure 1b, c), though greater doses of As2O3 abrogated the potential of Bcl-2 to suppress apoptosis (data not shown). These final results recommend that As2O3 evokes a specific apoptotic pathway associated to mitochondrial functions. To test this straight, we incubated isolated mouse liver mitochondria with clinically relevant concentrations of As2O3 and measured the release of cyto c from mitochondria. Indeed, As2O3 induced the release of cyto c in a dose-(Figure 2a) and time-(Figure 2b) dependent manner. The release of cyto c from isolated mitochondria upon remedy with 5 As2O3 started at 15 min, with mitochondrial cyto c becoming exhausted at 60 min (Figure 2b).