Abstract 2500: Radiosensitizing effects of neem leaf extract in human neuroblastoma xenograft is through modulation of apoptotic pathway

Abstract

Induction of apoptosis is directly correlated with the biological effectiveness of radiation (IR). Recently we have shown in neuroblastoma (NB) cells that IR modulates apoptotic signaling cascade and further demonstrated that fractionation relatively impede IR-induced cell death. It is therefore important to identify bioactive compounds that enhance IR-induced cell death and potentiate the use of radiotherapy in NB patients. In this study, we investigated the efficacy of neem leaf extract (NLE) on IR-associated apoptotic transcriptional modulation and cell death. NB xenografts developed in athymic NCr-nu/nu nude mice with human SK-N-MC cells were exposed to SDR (10Gy) or FIR (2Gy/Day for 5days) with or without NLE. IR exposures were limited to the tumor in flank region, while rest of the animal was protected by a specially designed cerrobend shield. Transcriptional activation of 84 apoptotic pathway focused genes was assessed using QPCR profiling. Cell death was measured using TdT nick end labeling. The results revealed that FIR significantly induced 55 genes and suppressed 10 genes, while SDR induced 49 and suppressed 5 genes. Of these, 46 genes were upregulated and 4 genes were downregulated after FIR and SDR, respectively. NLE inhibited 14 FIR-induced and 15 SDR-induced genes in human NB xenograft. To that end, NLE significantly inhibits anti-apoptotic NAIP, Birc6, Birc8, NOL3 after both SDR and FIR. Conversely, NLE significantly enhanced FIR- and SDR-induced pro-apoptotic BAK1, BAX, BCL10, Casp1, Casp10 CARD8 and CRADD in this setting. Furthermore, compared to mock-IR, DNA fragmentation analysis revealed that FIR and SDR significantly increased cell death. More importantly, NLE robustly and significantly conferred FIR- and SDR-induced cell death. Together, these data imply that NLE may exert radiosensitization mutually by activating pro-apoptotic signaling and negating survival signaling and, may thus serve as a potential “deliverable” to further potentiate radiotherapy in mitigating NB progression and relapse. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2500. doi:10.1158/1538-7445.AM2011-2500

Forkhead Box F1 represses cell growth and inhibits COL1 and ARPC2 expression in lung fibroblasts in vitro

“…Three genes putatively upregulated by FOXF1 were MMP10 (a matrix metalloprotease degrading fibronectin) and the proteoglycans SLC38A7 and CARD8. Whether CARD8 possesses pro-or antiapoptotic functions is controversial (4,32,43).…”

Neem components as potential agents for cancer prevention and treatment

“…Since loss of p53 function is a common deficiency in majority of cancers, neem may provide unique clinical benefits compared to most chemotherapeutic agents that rely on p53 function to induce apoptosis in tumor cells. Ionizing radiation-induced apoptosis is further enhanced by concurrent treatment of neuroblastoma cells with NLE [39]. This is likely due to the fact that the combination of neem extract and ionizing radiation enhances transcription of genes encoding proapoptotic proteins including Bak, Bax, and caspases to a greater extent compared to radiation alone.…”

“…Therefore, neem-induced suppression of NF-κB activation is likely to increase the radiosensitivity of tumor cells, which could potentially improve the clinical effectiveness of radiation therapy. Studies in pancreatic cancer cells show that treatment with NLE suppresses the radiation-induced activation of NF-κB signaling, resulting in increased caspase activity and cell death compared to the cells receiving radiation alone [39]. In addition, radiation-induced apoptosis of neuroblastoma cells is enhanced by the concurrent treatment with NLE through increasing the expression of proapoptotic proteins [39].…”

“…Studies in pancreatic cancer cells show that treatment with NLE suppresses the radiation-induced activation of NF-κB signaling, resulting in increased caspase activity and cell death compared to the cells receiving radiation alone [39]. In addition, radiation-induced apoptosis of neuroblastoma cells is enhanced by the concurrent treatment with NLE through increasing the expression of proapoptotic proteins [39]. However, it is unclear whether suppression of NF-κB signaling mediates this effect or other signaling also contributes to increased apoptosis [39].…”

Development of Nimbolide from Seeds of Azadirachta Indica Extract Assisted by Molecular Docking to Cyclin E, against Cervical Cancer

“…Azadirachta indica is evergreen, tropical, possessing oblique shaped green leaves and trunk of timber with insect repellent properties [2] . Roughly speaking, Azadirachta indica showed an anticancer activity by promoting the antioxidant enzyme, and modifying the intracellular components essential for cancer growth and development; such as Cyclin D, Cyclin B, Cyclin B1, Cyclin1, Cyclin E, P53, PCNA, P21,GST-P. Nimbolide was found to interact with the cell cycle kinetics in cancer cells by promoting the cell cycle arrest at G1/S or G2/M phase through suppression of Cyclin, CDKs and PCNA [3,4,5,6] . Nimbolide can be extracted from Azadirachta indica kernel powder by using an organic solvent such as ethyl acetate for microwave-assisted extraction, and it is refluxed for 15 hrs.…”