salinomycin and Nasopharyngeal-Neoplasms

The aim of this study was to investigate the effects of salinomycin (Sal) on expressions of baculoviral IAP repeat-containing 5 (BIRC5) and Nei endonuclease VIII-like 2 (NEIL2) and radiotherapy sensitivity of nasopharyngeal carcinoma (NPC).. Human NPC CNE-2 cell lines were used as research objects in this study. Subsequently, the cells received intervention with Sal at different concentrations, radioactive rays at different doses and Sal combined with radioactive rays. The growth inhibition rate of CNE-2 cells was detected via methyl thiazolyl tetrazolium (MTT) assay. The dose-effect relations of Sal, radioactive rays and combination therapy with the inhibitory effect on CNE-2 cells were obtained. CNE-2 cells receiving intervention with Sal at an appropriate concentration or radioactive rays at an appropriate dose alone and Sal combined with radioactive rays were used as intervention groups (Sal group, Radiation group and Combination group). However, those added with an equal amount of DMSO were set as Control group. Next, the cycle, apoptosis and apoptotic morphology of CNE-2 cells were observed via flow cytometry and Hoechst assay, respectively. Moreover, the expressions of apoptosis-related proteins Caspase-3, B-cell lymphoma-2 (Bcl-2) and Bcl-2 associated X protein (Bax), as well as BIRC5 and NEIL2 proteins in CNE-2 cells were determined using Western blotting.. Under the intervention with Sal or radioactive rays alone, the growth inhibition rate of CNE-2 cells rose in a concentration/dose-dependent manner. With the increase in Sal concentration in combination therapy, the growth inhibition rate of CNE-2 cells significantly increased (p<0.05). Compared with Control group, Sal group, Radiation group, and Combination group exhibited remarkably lower colony formation rate, higher proportion of CNE-2 cells in the G2/M phase, enhanced apoptosis of CNE-2 cells with nuclear fragmentation, increased expressions of pro-apoptotic proteins Caspase-3 and Bax, decreased expression of anti-apoptotic protein Bcl-2, and lower protein expressions of BIRC5 and NEIL2 in cells (p<0.05). Compared with Radiation group, the Combination group had significantly decreased colony formation rate, increased proportion of CNE-2 cells in the G2/M phase, enhanced apoptosis of CNE-2 cells with more nuclear fragmentation and other apoptosis characteristics, increased expressions of pro-apoptotic proteins Caspase-3 and Bax, decreased expression of anti-apoptotic protein Bcl-2, and decreased protein expressions of BIRC5 and NEIL2 in cells (p<0.05).. Sal enhances the radiotherapy sensitivity of NPC and reduces the protein expressions of BIRC5 and NEIL2 in cells.

Topics: Antineoplastic Agents; Apoptosis; Cell Proliferation; DNA Glycosylases; DNA-(Apurinic or Apyrimidinic Site) Lyase; Humans; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Pyrans; Survivin; Tumor Cells, Cultured

Although salinomycin sodium (SS) has shown in-vitro potential to inhibit cancer stem cell growth and development, its low water solubility makes it a poor candidate as an oral chemotherapeutic agent. To improve the bioavailability of SS, SS was encapsulated here using D-α-tocopherol polyethylene glycol succinate (TPGS)-emulsified poly(lactic-co-glycolic acid) (PLGA) nanoparticles and compared with its parent SS in terms of absorption, pharmacokinetics, and efficacy in suppressing nasopharyngeal carcinomas stem cells. The pharmacokinetics of SS and salinomycin sodium-loaded D-α-tocopherol polyethylene glycol succinate-emulsified poly(lactic-co-glycolic acid) nanoparticles (SLN) prepared by nanoprecipitation were analyzed in-vivo by timed-interval blood sampling and oral administration of SS and SLN to rats. Sensitive liquid chromatography-mass spectrometry (LC-MS) was developed to quantify plasma drug concentrations. SS and SLN transport in Caco-2 cells was also investigated. The therapeutic efficacy of SS and SLN against cancer stem cells was determined by orally administering the drugs to mice bearing CNE1 and CNE2 nasopharyngeal carcinoma xenografts and then evaluating CD133 cell proportions and tumorsphere formation. The in-vivo trial with rats showed that the Cmax, AUC(0-t), and Tmax for orally administered SLN were all significantly higher than those for SS (P<0.05). These findings were corroborated by a Caco-2 cell Transwell assay showing that relative SLN absorption was greater than that of SS on the basis of their apparent permeability coefficients (Papp). Significantly, therapeutic SLN efficacy against nasopharyngeal carcinoma stem cells was superior to that of SS. TPGS-emulsified PLGA nanoparticles effectively increase SS solubility and bioavailability. SLN is, therefore, promising as an oral chemotherapeutic agent against cancer stem cells.

Topics: alpha-Tocopherol; Animals; Caco-2 Cells; Emulsions; Humans; Intestinal Absorption; Male; Mice; Mice, Inbred BALB C; Nanoparticles; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Neoplastic Stem Cells; Polyethylene Glycols; Polylactic Acid-Polyglycolic Acid Copolymer; Pyrans; Random Allocation; Rats; Rats, Sprague-Dawley; Succinates

Radiotherapy is the most important treatment for nasopharyngeal carcinoma (NPC). Radioresistant cancer cells have been shown to potentially result in residual disease that can lead to recurrence and metastasis. Salinomycin (SAL) has been identified as a promising anticancer drug during chemical screening, but it is unclear whether SAL plays a role in radioresistance. The nuclear factor erythroid-2-related factor 2 (Nrf2) is a crucial regulator of the cellular antioxidant system. There are currently numerous data indicating that Nrf2 has an important role in cancer radioresistance. In the present study, we found that SAL can reverse radioresistance in radioresistant SUNE1 (SUNE1IR) cells using a clone formation assay. In addition, SAL promoted radiation-induced apoptosis in radioresistant NPC cells. Our data show that radioresistant SUNE1IR cells exhibited a significant increase in the protein level of Nrf2 compared to parental cells, and SAL inhibited increased Nrf2 in SUNE1IR cells. Moreover, we knocked down Nrf2 with shRNA in CNE2 cells and Western blot analysis demonstrated that irradiation (IR)-induced increase in Nrf2 protein expression was significantly downregulated by SAL. The clone formation assay showed that Nrf2-deficient CNE2 cells were more sensitive to IR than parental cells. Importantly, we confirmed that combination treatment of Nrf2-deficient CNE2 cells with SAL and IR markedly increased the level of reactive oxygen species (ROS) and DNA damage. Taken together, our findings demonstrate, for the first time, that SAL sensitized radioresistant cells to IR by inhibition of Nrf2 and the promotion of ROS generation in NPC. These results may contribute to the development of SAL-based therapy for NPC patients.

Topics: Apoptosis; Carcinoma; Cell Line, Tumor; DNA Damage; Humans; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; NF-E2-Related Factor 2; Pyrans; Radiation Tolerance; Radiation, Ionizing; Reactive Oxygen Species

Nasopharyngeal carcinoma (NPC) is primarily treated by chemoradiation. However, how to promote radiation sensitivity in NPC remains a challenge. Salinomycin is potentially useful for the treatment of cancer. This study aimed to explore the radiosensitivity of salinomycin on human nasopharyngeal carcinoma cell line CNE-2. CNE-2 were treated with salinomycin or irradiation, alone or in combination. The cytotoxicity effects of salinomycin were measured using CCK-8 assay. Clonogenic survival assay was used to evaluate the effects of salinomycin on the radiosensitivity of CNE-2. The changes of cell cycle distribution and apoptosis were assayed using flow cytometry. The expression of Caspase3/Bax/Bal-2 was detected by Western blotting. DNA damage was detected via γ-H2AX foci counting. The results showed that salinomycin induced apoptosis and G2/M arrest, increased Bax and cleaved Caspase3, decreased Bcl-2 expression, and increased the formation of γ-H2AX nuclear foci. These data suggest that salinomycin may be a radiosensitizer for NPC radiotherapy.

Topics: Apoptosis; bcl-2-Associated X Protein; Carcinoma; Caspase 3; Cell Cycle; Cell Line, Tumor; Cell Separation; Dose-Response Relationship, Radiation; Flow Cytometry; Histones; Humans; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Proto-Oncogene Proteins c-bcl-2; Pyrans; Radiation Tolerance; Radiation-Sensitizing Agents

Salinomycin (Sal) is a polyether ionophore antibiotic that has recently been shown to induce cell death in various human cancer cells. However, whether salinomycin plays a functional role in nasopharyngeal carcinoma (NPC) has not been determined to date. The present study investigated the chemotherapeutic efficacy of salinomycin and its molecular mechanisms of action in NPC cells. Salinomycin efficiently inhibited proliferation and invasion of 3 NPC cell lines (CNE-1, CNE-2, and CNE-2/DDP) and activated a extensive apoptotic process that is accompanied by activation of caspase-3 and caspase-9, and decreased mitochondrial membrane potential. Meanwhile, the protein expression level of the Wnt coreceptor lipoprotein receptor related protein 6 (LRP6) and β-catenin was down-regulated, which showed that the Wnt/β-catenin signaling was involved in salinomycin-induced apoptosis of NPC cells. In a nude mouse NPC xenograft model, the anti-tumor effect of salinomycin was associated with the downregulation of β-catenin expression. The present study demonstrated that salinomycin can effectively inhibit proliferation and invasion, and induce apoptosis of NPC cells in vitro and inhibit tumor growth in vivo, probably via the inhibition of Wnt/β-catenin signaling, suggesting salinomycin as a potential candidate for the chemotherapy of NPC.

Topics: Animals; Antineoplastic Agents; Apoptosis; Catenins; Cell Line, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; Humans; Male; Mice; Mice, Inbred BALB C; Mice, Nude; Nasopharyngeal Neoplasms; Pyrans; Wnt Signaling Pathway