sirolimus and Nasopharyngeal-Neoplasms

Radio-resistance is a leading cause of nasopharyngeal carcinoma (NPC) treatment failure and identification of sensitising therapeutic targets is an unmet need to enhance clinical management. Given that the mammalian target of rapamycin (mTOR) signalling confers resistance to cancer therapy, we investigated whether mTOR contributes to radio-resistance in NPC and pharmacological inhibition of mTOR can overcome radio-resistance. We found that mTOR mRNA and protein levels, and phosphorylation of its downstream effector were increased in radio-resistant NPC compared with parental cells. mTOR inhibitor temsirolimus inhibits proliferation and induces apoptosis in a panel of NPC cell lines. Importantly, temsirolimus acts synergistically with radiation and is effective against radio-resistant cells. Using radio-resistant xenograft mouse model, we validated the efficacy of temsirolimus in preventing tumour formation and inhibiting tumour growth. Temsirolimus overcome radio-resistance in NPC via inhibiting mTOR signalling. Our work provides the pre-clinical evidence that the combination of radiation and mTOR inhibitor may be a therapeutic strategy in NPC. Our findings might accelerate the initiation of clinical trials on radio-resistant NPC patients using temsirolimus.

Topics: Animals; Cell Line, Tumor; Cell Proliferation; Humans; Mammals; Mice; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Sirolimus; TOR Serine-Threonine Kinases

Juvenile nasopharyngeal angiofibroma (JNA) is a pathologically benign yet locally aggressive and destructive tumor that develops in the choana and nasopharynx. Historical treatment of JNA has included embolization, surgical resection, and radiation. Here, we describe three patients who received therapy with the mTOR inhibitor sirolimus with improvement in clinical symptoms, imaging, and overall well-being.

Topics: Adolescent; Angiofibroma; Antibiotics, Antineoplastic; Child; Humans; Male; Nasopharyngeal Neoplasms; Sirolimus; Treatment Outcome

Epithelial cell adhesion molecule (EpCAM) is known to be highly expressed in a variety of epithelial carcinomas, and it is involved in cell adhesion and proliferation. However, its expression profile and biological function in nasopharyngeal carcinoma (NPC) remains unclear. In this study, higher expression of EpCAM was found in NPC samples compared with non-cancer nasopharyngeal mucosa by qRT-PCR. Additionally, immunohistochemistry (IHC) analysis of NPC specimens from 64 cases showed that high EpCAM expression was associated with metastasis and shorter survival. Multivariate survival analysis identified high EpCAM expression as an independent prognostic factor. Ectopic EpCAM expression in NPC cells promoted epithelial-mesenchymal transition (EMT), induced a cancer stem cell (CSC)-like phenotype, and enhanced metastasis in vitro and in vivo without an effect on cell proliferation. Notably, EpCAM overexpression reduced PTEN expression and increased the level of AKT, mTOR, p70S6K and 4EBP1 phosphorylation. Correspondingly, an AKT inhibitor and rapamycin blocked the effect of EpCAM on NPC cell invasion and stem-like phenotypes, and siRNA targeting PTEN rescued the oncogenic activities in EpCAM knockdown NPC cells. Our data demonstrate that EpCAM regulates EMT, stemness and metastasis of NPC cells via the PTEN/AKT/mTOR pathway.

Topics: Adaptor Proteins, Signal Transducing; Adult; Animals; Cadherins; Cell Cycle Proteins; Cell Line, Tumor; Cell Movement; Epithelial Cell Adhesion Molecule; Epithelial-Mesenchymal Transition; Female; Humans; Kaplan-Meier Estimate; Male; Mice; Mice, Nude; Middle Aged; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Phosphoproteins; Proportional Hazards Models; Proto-Oncogene Proteins c-akt; PTEN Phosphohydrolase; RNA Interference; RNA, Small Interfering; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases

Rapamycin, a mammalian target of rapamycin (mTOR) signaling inhibitor, inhibits cancer cell proliferation and tumor formation, including in nasopharyngeal carcinoma (NPC), which we proved in a previous study. However, whether rapamycin affects cancer stem cells (CSCs) is unclear. In examining samples of NPCs, we found regions of CD44-positive cancer cells co-expressing the stem cell biomarker OCT4, suggesting the presence of CSCs. Following this, we used double-label immunohistochemistry to identify whether the mTOR signaling pathway was activated in CD44-positive CSCs in NPCs. We used a CCK-8 assay and western blotting to explore whether the stem cell biomarkers CD44 and SOX2 and the invasion protein MMP-2 could be suppressed by treatment with rapamycin in cultured primary NPC cells and secondary tumors in BALB/c nude mice. Interestingly, we found that rapamycin inhibited mTOR signaling in addition to simultaneously downregulating the expression of CD44, SOX2 and MMP-2 and that it affected cell growth and tumor size and weight both in vitro and in vivo. Collectively, we confirmed for the first time that CSC properties are reduced and invasion potential is restrained in response to mTOR signaling inhibition in NPC. This evidence indicates that the targeted inhibition of CSC properties may provide a novel strategy to treat cancer.

Topics: Animals; Antibiotics, Antineoplastic; Biomarkers, Tumor; Cell Line, Tumor; Cell Proliferation; Gene Expression Regulation, Neoplastic; Humans; Mice; Nasopharyngeal Neoplasms; Neoplastic Stem Cells; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases; Xenograft Model Antitumor Assays

To study the mTOR expression of cancer stem cells(CSCs) in nasopharyngeal carcinoma and preliminarily explore the mechanism of inhibiting its proliferation with rapamycin.. Nasopharyngeal carcinoma spherical cells were gathered by using serum-free suspension culture method, CCK8 assay was used to detect cell proliferation, Western blot assay was used to detect the expression of CD44, OCT4, SOX2 and mTOR signaling. The spherical cells and CNE2 were treated with rapamycin in concentrations of 0, 0.1, 1.0, 10.0, 100.0, 1000.0 nmol/L, CCK8 assay was used to detect cell inhibition ratio, Western blot assay was used to detect the expression of mTOR signaling of nasopharyngeal carcinoma spherical cells.. Compared with CNE2, the spherical cells exhibited a high proliferation rate in RPMI 1640 medium supplemented with fetal bovine serum, and overexpressed in OCT4, SOX2 (P < 0.05), but not that of CD44 (P > 0.05). Although the expression levels of mTOR, P70S6, 4EBP1 were not significantly different between the two kinds of cells (P > 0.05) the proteins of phosphorylation activation form of them (P-mTOR, P-P70S6, P-4EBP1) were highly expressed in spherical cells (P < 0.05). The spherical cells and CNE2 were treated with rapamycin in different concentrations, the concentrations for 50% of maximal effect of spherical cells and CNE2 were 2.59 nmol/L and 78.12 nmol/L respectively, rapamycin inhibited the spherical cells more strongly compared with CNEZ. The expression levels of P-mTOR, P-70S6, P-4EBP1 in spherical cells were gradually decreased with increasing of the concentrations of rapamycin, but the difference of the expression levels of mTOR, P70S6, 4EBP1 were not significant.. The proteins of mTOR signaling pathway of CSCs in nasopharyngeal carcinoma are overexpressed, and rapamycin can effectively inhibit cell proliferation of CSCs in nasopharyngeal carcinoma by blocking mTOR signaling pathway.

Topics: Adaptor Proteins, Signal Transducing; Carcinoma; Cell Cycle Proteins; Cell Proliferation; Humans; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Neoplastic Stem Cells; Phosphoproteins; Phosphorylation; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases; Tumor Cells, Cultured

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

The aim of the present study was to investigate the role of autophagy in response to ionizing radiation (IR) in CNE-2 human nasopharyngeal carcinoma cells and to demonstrate the function of poly(ADP-ribose) polymerase-1 (PARP-1) in the regulation of IR-induced autophagy. Microtubule-associated protein 1 light chain 3 (LC3) and poly(ADP-ribose) (PAR) were assessed using western blotting. Ultrastructural analysis was performed using transmission electron microscopy (TEM). The percentage of apoptotic cells was assessed by flow cytometry. The MTT method was used to detect cell viability of CNE-2 cells at different time points after IR. Clonogenic survival assays were used to evaluate the radiosensitivity of nasopharyngeal carcinoma cells treated with IR and IR combined with autophagy inhibitor (chloroquine phosphate), with autophagy inducer (rapamycin) or with PARP-1 inhibitor 3-amino benzamide (3AB). IR induced a massive accumulation of autophagosomes detected by TEM and intensified the conversion of cytosolic LC3-I to LC3-II. PARP-1 activation was accompanied by strong upregulation of PAR and LC3-II expression in CNE-2 cells. Compared with radiation alone, chloroquine phosphate (CDP) or 3AB combined with IR significantly decreased cell viability, as well as the autophagic ratio and LC3-II protein levels. Inhibition of autophagy increased radiation-induced apoptosis; rapamycin (RAPA) significantly decreased cell viability as well, but RAPA increased the autophagic ratio and LC3-II protein levels; induction of autophagy increased radiation-induced apoptosis. To conclude, PARP-1 regulates IR-induced autophagy, and PARP-1 inhibitor contributes to the radiation sensitization of CNE-2 cells. Blockade of autophagy with CDP enhanced the cytotoxicity of radiotherapy in CNE-2 cells. This suggests that inhibition of autophagy or PARP-1 may be used as an adjuvant therapy to treat nasopharyngeal carcinoma.

Topics: Antineoplastic Agents; Apoptosis; Autophagy; Benzamides; Carcinoma; Cell Line, Tumor; Cell Survival; Chloroquine; Humans; Microtubule-Associated Proteins; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Phagosomes; Poly (ADP-Ribose) Polymerase-1; Poly Adenosine Diphosphate Ribose; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Radiation Tolerance; Radiation-Sensitizing Agents; Sirolimus

The mammalian target of rapamycin (mTOR) signaling is a key pathway in the progression of different cancers and in the homeostasis of stem cells. Here, we investigated the link between mTOR signaling and cancer stem cells (CSCs) in nasopharyngeal carcinoma (NPC). We found that human primary NPC expressed embryonic stem cell (ESC) markers: CD133, SOX2 and OCT4 as well as pmTOR and pS6. Primary ESC-positive NPC cells could form secondary NPC in BALB/c nude mice. Rapamycin, an mTOR inhibitor, significantly suppressed ESC-positive NPC cell growth in vitro and tumor formation in vivo. Our findings suggest that mTOR signaling is activated in CSC-like cells and plays an important role in NPC growth.

Topics: AC133 Antigen; Animals; Antibiotics, Antineoplastic; Antigens, CD; Blotting, Western; Carcinoma; Cell Survival; Dose-Response Relationship, Drug; Enzyme Activation; Glycoproteins; Humans; Immunohistochemistry; Male; Mice; Mice, Inbred BALB C; Mice, Nude; Middle Aged; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Neoplastic Stem Cells; Octamer Transcription Factor-3; Peptides; Signal Transduction; Sirolimus; SOXB1 Transcription Factors; Time Factors; TOR Serine-Threonine Kinases; Tumor Burden; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

Radioresistance of EBV-associated nasopharyngeal carcinoma (NPC) is associated with poor prognosis for patients with this form of cancer. Here, we found that NPC patients had increased serum levels of leukemia inhibitory factor (LIF) and that higher LIF levels correlated with local tumor recurrence. Furthermore, in vitro studies with NPC cells and in vivo xenograft mouse studies demonstrated that LIF critically contributes to NPC tumor growth and radioresistance. Using these model systems, we found that LIF treatment activated the mTORC1/p70S6K signaling pathway, enhanced tumor growth, inhibited DNA damage responses, and enhanced radioresistance. Treatment with either soluble LIF receptor (sLIFR), a LIF antagonist, or the mTOR inhibitor rapamycin reversed LIF-mediated effects, resulting in growth arrest and increased sensitivity to γ irradiation. Immunohistochemical (IHC) analyses of human NPC biopsies revealed that LIF and LIFR were overexpressed in tumor cells and that LIF expression correlated with the presence of the activated p-p70S6K. Finally, we found that the EBV-encoded protein latent membrane protein 1 (LMP1) enhances LIF production. Together, our findings indicate that LIF promotes NPC tumorigenesis and suggest that serum LIF levels may predict local recurrence and radiosensitivity in NPC patients.

Topics: Animals; Carcinoma; Disease Progression; DNA Damage; Gamma Rays; Gene Expression Regulation, Viral; Heterografts; Humans; Leukemia Inhibitory Factor; Mechanistic Target of Rapamycin Complex 1; Mice; Mice, Inbred NOD; Mice, SCID; Multiprotein Complexes; Nasopharyngeal Neoplasms; Neoplasm Proteins; Neoplasm Recurrence, Local; Prognosis; Radiation Tolerance; Receptors, OSM-LIF; Ribosomal Protein S6 Kinases, 70-kDa; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases; Tumor Cells, Cultured; Tumor Microenvironment; Viral Matrix Proteins

Phosphorylated (pi-) protein kinase B (AKT) is commonly expressed in nasopharyngeal carcinoma (NPC) cell lines and tissues, suggesting the involvement of AKT-mammalian target of rapamycin (mTOR) signaling in NPC carcinogenesis. This study evaluated the activity of an mTOR inhibitor, RAD001 (Everolimus, Novartis Pharma AG, Switzerland), in 5 NPC cell lines (HK1, HONE-1, CNE-1, CNE-2, C666-1), 2 cisplatin-resistant NPC cell lines and their respective parental cell lines (HK1-LMP1, HONE-1-EBV). RAD001 inhibited cell growth in a dose-dependent manner at nanomolar concentrations in all cell lines. HONE-1 was most sensitive to RAD001 (IC(50) = 0.63 nM, 60% maximal inhibition), while Het-1A (a normal esophageal epithelial cell line) was relatively resistant. No consistent relationship between sensitivity to RAD001 and basal expression of pi-mTOR and pi-p70S6 Kinase-1 (p70S6K) was found. Exposure to RAD001 at picomolar concentrations for 48 h resulted in reduction of pi-mTOR and pi-p70S6K1 expression, but increase in pi-AKT (Ser473) expression in HONE-1 and CNE-1 cell lines. RAD001 significantly induced apoptosis in HONE-1 cells, but has no effect on cell cycle progression. RAD001 exerted an additive to synergistic effect on cisplatin-induced growth inhibition in CNE-1 and HONE-1 cells, and could inhibit the growth of both cisplatin-resistant and cisplatin-sensitive NPC cell lines. In summary, combination of RAD001 and cisplatin maybe a useful therapeutic strategy in NPC. AKT upregulation following RAD001 treatment suggests the presence of a feedback loop on AKT signaling in NPC which warrants further investigation.

Topics: Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Cell Cycle; Cell Line, Tumor; Cell Survival; Cisplatin; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Drug Synergism; Everolimus; Humans; Intracellular Signaling Peptides and Proteins; Nasopharyngeal Neoplasms; Phosphatidylinositol 3-Kinases; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins c-akt; Ribosomal Protein S6 Kinases, 70-kDa; Sirolimus; TOR Serine-Threonine Kinases

Activated mTOR was implicated to play a role in the carcinogenesis of nasopharyngeal carcinoma (NPC). However, the mechanism of activated mTOR/Complex1(mTORC1) signaling pathway in NPC development has not been well established. In this study, we correlated the expression of mTORC1 signal molecules and Cyclin D1 in NPC. We also investigated the effect of blocking mTORC1 signal with rapamycin and mTOR siRNA on Cyclin D1 expression in CNE-2 cells, as well as cell apoptosis and viability. We found a positive association of mTORC1 signal molecules and Cyclin D1 in NPC. Also, we found blockage mTORC1 inhibited Cyclin D1 expression in CNE-2 cells and enhanced cell apoptosis. Our results suggested that mTORC1 signal pathway might be a potential target for NPC therapy.

Topics: Adaptor Proteins, Signal Transducing; Adult; Apoptosis; Carcinoma; Case-Control Studies; Cell Cycle Proteins; Cell Line, Tumor; Cell Survival; Cyclin D1; Dose-Response Relationship, Drug; Female; Humans; Male; Middle Aged; Multiprotein Complexes; Nasopharyngeal Neoplasms; Phosphoproteins; Phosphorylation; Protein Kinases; RNA Interference; RNA, Small Interfering; Signal Transduction; Sirolimus; Time Factors; TOR Serine-Threonine Kinases; Transfection; Up-Regulation