benzyloxycarbonylvalyl-alanyl-aspartyl-fluoromethyl-ketone and Nasopharyngeal-Carcinoma

Mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase and a key element in the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway. Moreover, it is a negative regulator of autophagy and acts as a central regulator in cell growth. For the treatment of cancer, mTOR is a novel and validated therapeutic target. Previous studies have shown that Akt is frequently activated in nasopharyngeal carcinoma (NPC) tissues; thus, the inhibition of mTOR may be a treatment strategy for this tumor type. To evaluate the effect of the mTOR inhibitor RAD001 on NPC cell lines, we performed 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate (WST-1) assays, lactate dehydrogenase (LDH) assays, western blotting and flow cytometry to evaluate the mechanisms of cell death. The growth of both CNE-1 and HONE-1 cells was inhibited in a time- and dose-dependent manner. CNE-1 was more sensitive, with a 50% growth inhibition (GI50) of 30.0±1.0 µM compared to HONE-1, cells which had a GI50 of 56.9±13.1 µM. RAD001 induced apoptosis and autophagy in both cell lines. RAD001 induced a significant increase in growth inhibition in the two cell lines when used in combination with the autophagy inhibitor, 3-methyladenine; however, the percentages of apoptotic cells decreased when RAD001 was combined with the caspase inhibitor, z-VAD-fmk. In conclusion, the main mechanism of the mTOR inhibitor RAD001 in these two NPC cells was apoptotic, not autophagic cell death. The combination of RAD001 with autophagy inhibitors may be a useful therapeutic strategy for nasopharyngeal carcinoma.

Topics: Amino Acid Chloromethyl Ketones; Analysis of Variance; Antineoplastic Agents; Apoptosis; Autophagy; Carcinoma; Cell Line, Tumor; Cell Proliferation; Cell Shape; Everolimus; Flow Cytometry; Humans; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Sirolimus; TOR Serine-Threonine Kinases

Longikaurin A is a natural ent-kaurene diterpenoid isolated from Isodon genus. The ent-kaurene diterpenoids isolated from medicinal plants have been shown to have anti-disease effects. The present study was designed to examine the anti-tumour effects of longikaurin A (LK-A) in nasopharyngeal carcinoma in vitro and in vivo.. Apoptosis and cell cycle arrest were determined by flow cytometry analysis of the cells treated with Longikaurin A. The proteins of apoptosis signaling pathway were detected by western blotting analysis. Finally, we examined whether LK-A exhibits anti-tumour activity in xenograft models.. Longikaurin A inhibited the cell growth by inducing apoptosis and cell cycle arrest. At low concentrations, longikaurin A induced S phase arrest and at higher concentrations, longikaurin A induced caspase-dependent apoptosis by regulating apoptotic molecules. Finally, longikaurin A significantly inhibited the tumour growth of CNE2 xenografts in vivo and showed no obvious effect on the body weights of the mice.. Our results suggest that Longikaurin A exhibited anti-tumour activity in nasopharyngeal carcinoma in vitro and in vivo.

Topics: Amino Acid Chloromethyl Ketones; Animals; Antineoplastic Agents; Apoptosis; Apoptosis Regulatory Proteins; Carcinoma; Caspase 3; Caspase 9; Cell Line, Tumor; Cell Survival; Diterpenes, Kaurane; Mice; Mice, Nude; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Poly(ADP-ribose) Polymerases; S Phase; Signal Transduction; Tumor Stem Cell Assay; Up-Regulation; Xenograft Model Antitumor Assays