gambogic-acid and Carcinoma--Renal-Cell

Gambogic acid (GA) is a natural compound derived from brownish gamboge resin that shows a range of bioactivity, such as antitumor and antimicrobial properties. Although, GA is already known to induce cell death in a variety of cancer cells, the molecular basis for GA-induced cell death in renal cancer cells is unclear. In this study, a treatment with GA induced cell death in human renal carcinoma Caki cells in a dose-dependent manner. Treatment of Caki cells with GA decreased the levels of antiapoptotic proteins, such as Bcl-2 and XIAP in a dose-dependent manner. In addition, GA decreased the expression of the cFLIPL protein, which was downregulated at the transcriptional level without any change in the levels of cFLIPs expression. z-VAD (pan-caspase inhibitor) partially blocked GA-mediated cell death. GA-induced apoptotic cell death in Caki cells is mediated partly by the AIF translocation from the mitochondria into the nucleus via a caspase-independent pathway. In contrast, N-acetylcysteine (NAC), a ROS scavenger, had no effect on GA-induced cell death. The restoration of cFLIPL attenuated GA-induced cell death in Caki cells. Furthermore, a sub-toxic dose of GA sensitized TRAIL-mediated apoptosis in Caki cells. Pretreatment with z-VAD completely blocked GA plus TRAIL-mediated apoptosis. On the contrary, pretreatment with NAC partially inhibited GA plus TRAIL-induced apoptosis. Our findings suggested that GA induces apoptosis via the downregulation of cFLIPL and sensitized TRAIL-mediated apoptosis in Caki cells.

Topics: Acetylcysteine; Apoptosis; Carcinoma, Renal Cell; CASP8 and FADD-Like Apoptosis Regulating Protein; Cell Line, Tumor; Cell Proliferation; Gene Expression Regulation, Neoplastic; Humans; Reactive Oxygen Species; TNF-Related Apoptosis-Inducing Ligand; Xanthones

To evaluated the effect of the gambogic acid (GA), one of the effective components of Garcinia, in combination with a new multi-targeted oral medication, sunitinib (SU) on renal cancer cell proliferation in vitro and on tumor growth in vivo.. After treatment with GA or SU, either alone or in combination, MTT and FACS analysis were used to examine cell viability and cycle distribution of the renal carcinoma cell lines 786-0 and Caki-1. Western blotting was employed to examine the expression of proteins related to the cell cycle and vascular formation. Furthermore, a xenograft model was applied to study the antitumor efficacy of SU or GA alone or in combination, with immunohistochemistry to detect expression of proteins related to xenograft growth and angiogenesis. Western blotting was used to examine NF-?B signaling pathway elements in xenografts.. Treatment of 786-0 and Caki-1 cells with GA or SU resulted in decreased tumor cell proliferation, especially with joint use. Cells accumulated more strongly in the sub-G1 phase after joint treatment with GA and SU than treatment of GA and SU alone. Western blotting arrays showed 1 protein significantly upregulated, 2 proteins downregulated, and 2 proteins unchanged. Moreover, combined use of GA and SU inhibited the growth and angiogenesis of xenografts generated from Caki-1 significantly. Immunohistochemistry arrays showed downregulation of the expression of proteins promoting xenograft growth and angiogenesis, and Western blotting showed inhibition of the NF-?B signaling pathway after treatment by GA alone and in combination with SU in xenografts.. Our results show that the joint use of GA and SU can provide greater antitumor efficacy compared to either drug alone and thus may offer a new treatment strategy for renal cell carcinoma.

Topics: Animals; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Carcinoma, Renal Cell; Cell Line, Tumor; Cell Proliferation; Cell Survival; Down-Regulation; G1 Phase; Indoles; Kidney Neoplasms; Male; Mice, Inbred BALB C; Mice, Nude; Neovascularization, Pathologic; NF-kappa B; Pyrroles; Signal Transduction; Sunitinib; Up-Regulation; Xanthones; Xenograft Model Antitumor Assays