Primary tumors were surgically removed 15 days after tumor cell injection. Mice were treated with LCL85 over time after surgery. This procedure thus mimics human breast cancer patient treatment. Analysis of lungs indicated that LCL85 significantly suppresses more breast can cer spontaneous lung metastasis. Taken together, our data demonstrated that LCL85 at a subtoxic dose is effective in suppression of colon and breast cancer metastasis. Discussion Ceramide mediates apoptosis through multiple mecha nisms. It has been reported that ceramide mediates Fas receptor clustering, capping and activation to promote Fas mediated apoptosis. Ceramide has also been shown to regulate Bcl x alternative splicing to decrease Bcl xL level, and Inhibitors,Modulators,Libraries mediates Bak, Bax and Bcl 2 functions in the intrinsic apoptosis pathway.

The effects of ceramide on these apoptosis mediators are apparently cell type or Inhibitors,Modulators,Libraries cellular context dependent since LCL85 only alters the expression level of Bcl xL in human colon and Inhibitors,Modulators,Libraries breast cancer cells. Here, we identified xIAP and cIAP1 as targets of the ceramide signaling pathways in both metastatic human colon and breast cancer cells. We observed that LCL85 effectively decreased cIAP1 and xIAP protein levels in metastatic human colon and breast cancer cells. Inhibitors,Modulators,Libraries Consistent with the decreased xIAP1 and cIAP1 protein levels, metastatic human colon carcinoma cells exhibited increased sensitivity to FasL induced apop tosis. Furthermore, treatment of metastatic human colon carcinoma cells with cIAP1 and xIAP specific inhibitor BV6 also significantly increased tumor cell sensitivity to FasL induced apoptosis.

Therefore, our data suggest that xIAP1 and cIAP1 proteins are responsible, at least in part, for the apoptosis resistant phenotype in metastatic human colon and breast cancers, and LCL85 overcomes metastatic human colon and breast cancer cell resistance to Fas mediated apoptosis at least partially through indu cing proteasomal degradation of xIAP and cIAP1 proteins. Inhibitors,Modulators,Libraries It has been well documented that Smac mimetic BV6 specifically targets cIAP1 and cIAP2 proteins to induce apoptosis through activating the TNF signaling pathway. However, it has also been shown that xIAP, rather than cIAP1 and cIAP2, is the critical target of BV6 in Fas mediated apoptosis. Strikingly, we observed that LCL85 also sensitizes tumor cells to Fas mediated apoptosis through inducing proteasomal degradation of xIAP.

LCL85 treatment increased endogenous C16 cer amide level and exogenous C16 ceramide is effective in sensitizing the apoptotic resistant metastatic human colon carcinoma cells to Fas mediated apoptosis. Therefore, it is possible that www.selleckchem.com/products/BI6727-Volasertib.html LCL85 sensitizes tumor cells to Fas mediated apoptosis at least in part through inducing C16 ceramide accumulation, resulting in ceramide mediated xIAP and cIAP1 proteasomal degradation.