Targeted blocking of EGFR and GLUT1 by compound H reveals a new strategy for treatment of triple-negative breast cancer and nasopharyngeal carcinoma.

BACKGROUND: Cytoplasmic epidermal growth factor receptor (EGFR) is overexpressed in both nasopharyngeal carcinoma (NPC) and triple-negative breast cancer (TNBC), while clinical outcome and prognosis vary greatly among patients treated with gefitinib, and all patients eventually develop resistance to this agent. Therefore, we propose a new concept for synthesizing multitarget compounds and reveal new therapeutic strategies for NPC and TNBC expressing EGFR. METHODS: Compound H was synthesized in our previous study. Molecular docking, and cell thermal shift assays (CETSAs) and drug affinity responsive target stability(DARTS) were used to confirm the binding of compound H to EGFR and GLUT1. Methylthiazolyldiphenyl-tetrazolium bromide(MTT), annexin V-PE assays, mitochondrial membrane potential (MMP) assays, and animal models were used to evaluate the inhibitory effect of compound H on TNBC cell lines. Energy metabolism tests, Western blotting, and immunofluorescence staining were performed to evaluate the synergistic effects on EGFR- and glucose transporter type 1(GLUT1)-mediated energy metabolism. RESULTS: Compound H can simultaneously act on the EGFR tyrosine kinase ATP-binding site and inhibit GLUT1-mediated energy metabolism, resulting in reductions in ATP, MMP, intra-cellular lactic acid, and EGFR nuclear transfer. The anti-tumor activity of compound H is significantly superior to the combination of GLUT1 inhibitor BAY876 and EGFR inhibitor gefitinib. Compound H has remarkable anti-proliferative effects on TNBC MDA-MB231 cells, and importantly, no obvious toxicity effects of compound H were found in vivo. CONCLUSIONS: Synergistic effects of inhibition of EGFR- and GLUT1-mediated energy metabolism by compound H may present a new strategy for the treatment of TNBC and NPC.

Novel anthraquinone derivatives trigger endoplasmic reticulum stress response and induce apoptosis.

Background: Endoplasmic reticulum (ER) stress is a therapeutic target in cancer given its regulation of bioenergetics and cell death. Methodology & results: We synthesized 14 ER stress-triggered anthraquinone derivatives by introducing an amino group at the 3-position side chain of the lead compound obtained previously. Most of the anthraquinone derivatives exhibited good antitumor activity due to their ability to induce ER damage through cytoplasmic vacuoles. The mechanisms of ER stress caused by compound KA-4c were related to increasing the expression levels of the ATF6 and Bip proteins and upregulating CHOP and cleaved PARP. Conclusion: Compound KA-4c triggers ER stress response and induces apoptosis via the ATF6-CHOP signaling pathway.

A novel anthraquinone­quinazoline hybrid 7B blocks breast cancer metastasis and EMT via targeting EGFR and Rac1.

At present, effective therapeutic drugs for triple­negative breast cancer (TNBC) are lacking due to the absence of identified or available targets. Therefore, the present study aimed to identify key molecular targets and a specific targeted therapeutic drug to aid with the development of novel therapeutic strategies for TNBC. Based on the high expression of EGFR and Rac1 in TNBC and inspired by a novel antitumor strategy termed combi­targeting, novel anthraquinone­quinazoline hybrid 7B was synthesized to simultaneously target EGFR and Rac1. It was hypothesized that hybrid 7B may possess enhanced potency compared with its parent compounds. Breast cancer cell viability was detected by performing MTT assays. Flow cytometry was conducted to detect the effects of hybrid 7B on the cell cycle, apoptosis and the mitochondrial outer membrane potential. Ultrastructural alterations were observed by transmission electron microscopy. Cell invasion and migration were assessed by performing Transwell and wound­healing assays, respectively. The expression levels of epithelial­mesenchymal transition (EMT) markers and metastasis­related proteins were detected by western blotting. Compared with Rhein and gefitinib, hybrid 7B displayed superior antiproliferative activity in MDA­MB­231 cells with an IC50 value of 2.31 µM, which was 14­fold higher compared with the EGFR tyrosine kinase inhibitor gefitinib. Further experiments demonstrated that hybrid 7B significantly reduced the mitochondrial membrane potential, enhanced MDA­MB­231 cell apoptosis and induced cell cycle arrest at the G2/M phase compared with the control group. Typical morphological alterations of apoptotic cells were observed in hybrid 7B­treated MDA­MB­231 and MCF­7 cells. Compared with the control group, hybrid 7B significantly inhibited MDA­MB­231 cell invasion and migration by downregulating Rac1, EGFR, matrix metalloproteinases, snail family transcriptional repressor 1, Vimentin and ß­catenin protein expression levels, and upregulating E­cadherin protein expression levels. The present study demonstrated that hybrid 7B inhibited TNBC cell migration and invasion by reversing EMT and targeting EGFR and Rac1; therefore, hybrid 7B may serve as a promising therapeutic agent for TNBC.

Confirming whether novel rhein derivative 4a induces paraptosis-like cell death by endoplasmic reticulum stress in ovarian cancer cells.

Ovarian cancer is the leading cause of death among gynecologic cancer patients. Although platinum-based chemotherapy as a frontline treatment for ovarian cancer has been widely used in clinical settings, its clinical efficacy is not satisfactory due to the resistance of ovarian cancer cells to apoptosis. Therefore, it is of great significance to induce non-apoptotic programed cell death patterns, such as paraptosis, in ovarian cancer. In this study, we aimed to explore the potential anticancer mechanisms of novel rhein derivative 4a, which was modified with rhein as a lead compound. The results showed that a wide range of vacuoles from the endoplasmic reticulum and mitochondria appeared in ovarian SKOV3, SKOV3-PM4, and A2780 cells treated with derivative 4a, and the cell death caused by derivative 4a is a type of non-apoptotic and non-autophagic death, which is caused by expansion and damage of the endoplasmic reticulum or mitochondria, showing the characteristics of para-apoptotic death. Furthermore, derivative 4a stimulated the unfolded protein reaction of ovarian cancer cells by upregulating the expression of Bip78 and activating the PERK-eIF2α-ATF4 pathways. Notably, rhein derivative 4a-induced cell death was positively correlated with activation of p38, ERK, and JNK, and negatively correlated with Alix, a known protein that inhibits paraptosis. In addition, derivative 4a treatment also induced G2/M phase arrest in ovarian cancer cells. Taken together, our study reveals that derivative 4a induces paraptosis, and this finding can serve as a basis in developing a new strategy for the treatment of antiapoptotic ovarian cancer.

Rhein Derivative 4F Inhibits the Malignant Phenotype of Breast Cancer by Downregulating Rac1 Protein.

BACKGROUND: Triple-negative breast cancer is a common malignant tumor with unfavorable prognosis affecting women worldwide; thus, there is an urgent need for novel therapeutic drugs with improved anti-tumor activity. Rac family small GTPase 1 (Rac1) plays an important role in malignant behavior and is a promising therapeutic target. We reported an anthraquinone compound, Rhein, and its derivative, 4F, and investigated their downregulation effects on Rac1 in breast cancer cells in vitro. METHODS: The inhibition of cell proliferation by derivative 4F was investigated in two breast cancer (MDA-MB-231 and MCF-7) and normal breast (MCF-10A) cell lines by cell counting kit-8 assay and growth curves. The role of 4F in cell migration and invasion and cytoskeletal change were assessed by Transwell chamber assay and F-actin staining, respectively. The affinity of Rhein and its derivative for Rac1 protein and the regulation of Rac1 promoter activity were evaluated by molecular docking software and luciferase reporter gene assay, respectively. Rac1 protein expression was determined by western blot assay. RESULTS: Compared to Rhein, derivative 4F more strongly inhibited breast cancer cell proliferation, migration, and invasion and also cause cytoskeletal changes like those in paclitaxel. Derivative 4F not only bound more stably to Rac1 but also inhibited Rac1 promoter activity in cells and downregulated Rac1 protein expression. CONCLUSIONS: Rhein derivative 4F is a new anthraquinone compound with better anti-tumor activity than that of the lead compound Rhein in breast cancer. It down-regulated Rac1 expression and may be a small molecule inhibitor of Rac1.

Rac1: A potential radiosensitization target of human nasopharyngeal carcinoma CNE2 cells.

Radiotherapy has a high cure rate for early nasopharyngeal carcinoma(NPC). However, the radiation resistance of poorly differentiated NPC cells impacts the effectiveness of treatment of early-stage NPC patients. Here, we explored the relationship between Ras-related C3 botulinum toxin substrate 1(Rac1) expression and NPC radiosensitivity. In vitro and in vivo studies revealed that upregulation of Rac1, when combined with X-ray treatment, increased growth inhibition and induced remarkable morphological changes and apoptosis in CNE2 cells. Furthermore, rupturing of the cell and nuclear membranes, degeneration of the cristae and significant swelling of the mitochondria were observed, which were consistent with the high apoptotic rate. The Rac1(+) cells exhibited approximately 50% more migration compared with that of the NC and Rac1(-) cells. The overexpression of Rac1 can increase the radiation sensitivity of NPC CNE2 cells, and the mechanism may be closely related to the oxidative damage of mitochondria. Rac1 might be a potential target for radiosensitization in poorly differentiated NPC.

Novel anthraquinone compounds as anticancer agents and their potential mechanism.

Anthraquinones exhibit a unique anticancer activity. Since their discovery, medicinal chemists have made several structural modifications, resulting in the design and synthesis of a large number of novel anthraquinone compounds with different biological activities. In general, anthraquinone compounds have been considered to have anticancer activity mainly through DNA damage, cycle arrest and apoptosis. However, recent studies have shown that novel anthraquinone compounds may also inhibit cancer through paraptosis, autophagy, radiosensitising, overcoming chemoresistance and other methods. This Review article provides an overview of novel anthraquinone compounds that have been developed as anticancer agents in recent years and focuses on their anticancer mechanism.

Synthesis and screening of novel anthraquinone-quinazoline multitarget hybrids as promising anticancer candidates.

Aim: The EGF receptor (EGFR) is overexpressed in multiple epithelial-derived cancers and is considered to be a vital target closely associated with cancer therapy. In this study, a series of novel anthraquinone-quinazoline hybrids targeting several vital sites for cancer therapy were designed and synthesized. Methodology & results: Most of the synthesized hybrids demonstrated excellent antiproliferative activity and downregulation of the expression of EGFR. The most promising compound 7d showed the strongest antiproliferation activity; this compound significantly downregulated the expression of p-EGFR protein, induced a remarkable apoptosis effect, promoted the rearrangement of F-actin filaments and destruction of cytoskeleton, induced DNA damage and enhanced radiosensitivity of A549 cells. Conclusion: The novel anthraquinone-quinazoline hybrid 7d emerges as an anticancer drug candidate with promising multitargeted biological activities.

An autophagy-dependent cell death of MDA-MB-231 cells triggered by a novel Rhein derivative 4F.

Triple negative breast cancer (TNBC) has very poor prognosis and no efficacious therapeutic options due to the absence of a validated molecular target. Therefore, novel therapeutic strategies against TNBC are urgently needed. Our team synthesized and screened a series of compounds derived from Rhein, of which 4F was selected for further analysis based on its ability to produce the vacuolated appearance of cells. Using Cell counting kit-8 assay, colony-formation assay, cell apoptosis and cell cycle assay, we compared the antitumor effects of 4F, Rhein and Cisplatin on a TNBC cell line MDA-MB-231 in vitro. The vacuoles in MDA-MB-231 cells were observed and analyzed by hematoxylin-eosin staining and transmission electron microscopy. Autophagy and apoptosis-related proteins including p62, Microtubule Light Chain 3 (LC3), Beclin-1 and Caspase-3 were determined by western blot. The tandem mRFP-GFP-LC3 Lentivirus was used for monitoring the maturation step of autophagosomes. Our data revealed that 4F had lower cytotoxicity to normal breast cell line MCF-10A as compared with positive drug Doxorubicin. Although 4F had better cytotoxicity than Rhein, it had no influence on cells apoptosis in 4F-treated cells. Accumulation of autolysosomes and autophagosomes was observed in 4F-treated MDA-MB-231 cells, accompanied by increased level of Beclin-1 protein. Enhanced autophagic flux was verified by higher ratio of LC3-II/LC3-I, the degradation of p62 protein and alteration in red and green fluorescence puncta. These findings suggested that the process of MDA-MB-231 cell death induced by 4F seemed rely mainly on autophagy rather than apoptosis. 4F may be an alternative drug candidate against TNBC and merits more exploration.

Novel Anthraquinone Compounds Induce Cancer Cell Death through Paraptosis.

Novel anthraquinone compounds that induce ER stress and paraptosis-like cell death were designed and synthesized. Compound 4a is the first organic micromolecule to kill tumor cells by only paraptosis, and its mechanism of action has been further explored. Paraptosis does not appear to involve either phosphatidylserine translocation associated with apoptosis or cell cycle arrest. The bisbenzyloxy and N-(2-hydroxyethyl)formamide structures may be two critical pharmacophores for paraptosis. Bisbenzyloxy can induce ER stress, and the N-(2-hydroxyethyl)formamide structure can increase the ratio of LC3II/I and cytoplasmic vacuolization and facilitates paraptosis. Some antitumor drugs fail to eradicate malignant cell lines with impaired apoptotic pathways; paraptosis may be a route to kill such cells and provides a new potential strategy for cancer chemotherapy.

A novel Rhein derivative: Activation of Rac1/NADPH pathway enhances sensitivity of nasopharyngeal carcinoma cells to radiotherapy.

Radiation resistance and recurrent have become the major factors resulting in poor prognosis in the clinical treatment of patients with nasopharyngeal carcinoma (NPC). New strategies to enhance the efficacy of radiotherapy have been focused on the development of radiosensitizers and searching for directly targets that modulated tumor radiosensitivity. A novel potential radiosensitizer 1,8-Dihydroxy -3-(2'-(4″-methylpiperazin-1″-yl) ethyl-9,10-anthraquinone -3-carboxylate (RP-4) was designed and synthesized based on molecular docking technology, which was expected to regulate the radiosensitivity of tumor cells through targeting Rac1. In order to assess the radiosensitization activity of RP-4 on NPC cells, the highly differentiated CNE1 and poorly differentiated CNE2 cells NPC lines were employed. According to the results, RP-4 showed higher binding affinity toward the interaction with Rac1 than lead compounds. We found that RP-4 could inhibit cell viability and proliferation in CNE1 and CNE2 cells and significantly induced apoptosis after non-toxic concentration of RP-4 combined with 2Gy irradiation. RP-4 could effectively modulated the radiosensitivity both CNE1 cells and CNE2 cells through activating Rac1/NADPH signaling pathway and its downstream JNK/AP-1 pathway. What's more, Rac1/NADPH signaling pathway were significantly activated in Rac1-overexpressed CNE1 and CNE2 cells after treated with RP-4. Taken together, Rac1 and its downstream pathway may probably be the direct targets of RP-4 in regulating radiosensitivity of NPC cells, our finding provided a novel strategy for the development of therapeutic agents in response to tumorous radiation resistance.

New Application of Waste Citrus Maxima Peel-Derived Carbon as an Oxygen Electrode Material for Lithium Oxygen Batteries.

Recently, lithium oxygen battery has become a promising candidate to satisfy the current large-energy-storage devices demand because of its amazing theoretical energy density. However, it still faces problems such as poor reversibility and short cycle life. Here, citrus maxima peel (CMP) was used as a precursor to prepare activated and Fe-loading carbon (CMPACs and CMPACs-Fe, respectively) via pyrolysis in nitrogen atmosphere at 900 °C, in which KOH was added as an activator. Electrochemical measurements show that CMPAC-based Li-O2 battery possesses high specific capacity of 7800 mA h/g, steady cycling performance of 466 cycles with a corresponding Coulombic efficiency of 92.5%, good rate capability, and reversibility. Besides, CMPACs-Fe-based O2 electrode delivers even lower overpotential in both charge and discharge processes. We conclude that these excellent electrochemical performances of CMPACs and CMPACs-Fe-based O2 electrode benefit from their cellular porous structure, plenty of active sites, and large specific surface area (900 and 768 m2/g), which suggest that these biomass-derived porous carbons might become promising candidates to achieve efficient lithium oxygen battery.

Facile low-temperature one-step synthesis of pomelo peel biochar under air atmosphere and its adsorption behaviors for Ag(I) and Pb(II).

This study prepared a novel low-cost surface functionalized carbon adsorbent (PPC) from biomass waste (pomelo peel) through a facile low-temperature (250 °C) one-step method under regular air atmosphere. The adsorption performance and mechanism of the carbon material for Ag(I) and Pb(II) were investigated by a range of sorption experiments and characterizations including SEM, EDX, XRD and FTIR. Sorption experimental results suggested that PPC had high adsorption capacities of 137.4 and 88.7 mg/g for Ag(I) and Pb(II), respectively, with adsorbent dosage of 2 g/L at unadjusted solution pH and room temperature (23 ±â€¯1 °C). The characterization results indicated high-efficiency removal of the heavy metals by PPC was attributed to the strong chemical adsorption involving that Ag(I) ions were reduced as metallic Ag particles by oxygenic functional groups and Pb(II) ions were precipitated as Pb5(PO4)3OH crystals by phosphorous functional groups on the carbon surfaces. This study provides the possibility of synthesis high-efficient adsorbent using economic and environmental-friendly approach with low energy consumption.

Identification of side population cells in human lung adenocarcinoma A549 cell line and elucidation of the underlying roles in lung cancer.

The present study aimed to isolate and characterize side population (SP) cells in the human lung cancer A549 cell line, and elucidate the molecular mechanism of SP cells underlying lung cancer. The SP and non-SP (NSP) cells in A549 cells were isolated and their differentiation was analyzed by fluorescence-activated cell sorting. An in vitro plate clone assay, Matrigel® Transwell assay and chemoresistance analysis of the sorted SP and NSP cells were performed. In addition, the sorted SP and NSP cells were injected into BALB/c nude mice to detect their tumorigenic potential in vivo. The expression of ATP-binding cassette sub-family G member 2 (ABCG2) in transplanted tumors was detected by immunohistochemistry. The SP and NSP cells were successfully isolated. The results demonstrated that SP cells accounted for 1.09% of live A549 cells. SP cells produced SP and NSP cells, while NSP cells only produced NSP cells. In addition, SP cells formed more colonies, exhibited improved invasive ability and increased levels of chemoresistance compared with NSP cells in vitro. SP cells demonstrated a higher tumorigenic potential in BALB/c nude mice, and the number of ABCG2-positive cells in the SP xenograft tumors were significantly increased compared with that in the NSP xenograft tumors. The present study indicated that SP cells isolated from the human lung cancer A549 cell line demonstrated increased tumorigenicity, and improved invasive ability and chemoresistance compared with NSP cells. In addition, detection of ABCG2 expression may assist in predicting the chemotherapeutic outcome of patients, and serve as a target for treating lung cancer.

SPARC suppresses lymph node metastasis by regulating the expression of VEGFs in ovarian carcinoma.

Lymph node metastasis is one of the most valuable determinants for the prognosis of ovarian cancer. However, the molecular mechanisms underlying lymphangiogenesis in ovarian cancer is still poorly understood. Secreted protein acidic and rich in cysteine (SPARC), a Ca2+-binding matricellular glycoprotein that modulates cell adhesion, migration and differentiation, is thought to play a decisive role in tumor metastasis. Vascular endothelial growth factor (VEGF)-C and VEGF-D contributes to tumor-associated lymphatic vessel growth, enhancing the metastatic spread of tumor cells to lymph nodes. The aim of the present study was to investigate the relationship among SPARC, VEGFs and lymph node metastasis in ovarian cancer. We found that SKOV3 cells expressed high-level SPARC, much more than SKOV3-PM4 cells (a subline with high directional lymphatic metastatic potentials established from the metastatic lymph node generated by human ovarian carcinoma cell line SKOV3 in nude mice) did at both mRNA and protein levels. A SPARC-overexpressed SKOV3-PM4 cell line was constructed and it was found that upregulation of SPARC expression suppressed the growth, migration and invasion of SKOV3-PM4 cells as well as markedly reduced the expression of VEGF-D at both mRNA and protein level by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot assay. In 47 of ovarian malignant tissues, the expression of SPARC, VEGF-C and VEGF-D were determined by immunohistochemistry. Lymphatic microvessel density (LVD) and microvessel density (MVD) were evaluated by immunostaining with CD34 and D2-40 antibodies, respectively. We found that SPARC expression was significantly lower in tissues with lymph node metastasis as compared to tissues without lymph node metastasis. SPARC expression was inversely associated with the degree of malignancy and it had a negative correlation with VEGF-C expression, VEGF-D expression, LVD and MVD which were actually higher for advanced tumors than for non-advanced tumors. These results suggest SPARC might function as a tumor suppressor inhibiting angiogenesis and lymphangiogenesis in ovarian cancer by reducing the expression of VEGF-C and VEGF-D.

Effects of Rubiadin isolated from Prismatomeris connata on anti-hepatitis B virus activity in vitro.

Prismatomeris connata was a kind of Rubiaceae plant for treatment of hepatitis, hepatic fibrosis and silicosis. Whereas, the effective components of Prismatomeris connata remains unexplored. The aim of this study was to investigate the inhibitory effects and mechanisms of Rubiadin isolated from Prismatomeris connata against HBV using HepG2.2.15 cells. The levels of hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), and hepatitis B core antigen (HBcAg) in the supernatants or cytoplasm were examined using by enzyme-linked immunosorbent assay. HBV DNA was qualified q-PCR. Rubiadin was isolated by silica gel column. The structure of the compound was elucidated by HPLC, FT-IR, 1 H-NMR, 13 C-NMR and identified as 1,3-Dihydroxy-2-methyl-9, 10-anthraquinone. Rubiadin significantly decreased HBeAg,HBcAg secretion level and inhibit HBV DNA replication. Rubiadin inhibits the proliferation of the cells and HBx protein expression in a dose-dependent manner. The intracellular calcium concentration was significantly reduced. These results demonstrated that Rubiadin could inhibit HepG2.2.15 cells proliferation, reduce the level of HBx expression, and intracellular free calcium, which might become a novel anti-HBV drug candidate.

Rhein suppresses matrix metalloproteinase production by regulating the Rac1/ROS/MAPK/AP-1 pathway in human ovarian carcinoma cells.

Matrix metalloproteinases (MMPs) are a family of calcium-dependent zinc-containing endopeptidases, which play an integral role in migration and invasion of ovarian cancer. Rac1 proteins might mostly influence cell migration and invasion by generating endogenous reactive oxygen species. Therefore, inhibiting MMPs and regulating the Rac1/ROS/MAPK/AP-1 pathway may be a new therapeutic strategy for ovarian cancer. In this study, we found that rhein could suppress the invasion and migration of SKOV3-PM4 cells with characteristics of directional highly lymphatic metastasis. Phorbol 12-myristate 13-acetate (PMA), which is a Rac1 activator, significantly enhanced the expression levels of MMP-2, -3, -9 and -19 proteins, whereas the results of rhein and Rac1 inhibitor NSC23766 were just the opposite. The inhibitory effects of rhein were associated with the upregulation of tissue inhibitors of metalloproteinase (TIMP)-1, TIMP-2 and NM23-H1. Subsequent mechanism studies revealed that rhein reduce the production of reactive oxygen species (ROS) and lower NADPH oxidase activity. Furthermore, rhein significantly inhibited JNK, AP-1 phosphorylation in the cells treated with PMA. The results obtained from the cells treated with NSC23766 alone or NSC23766 combined with rhein, were consistent with rhein treatment alone. Taken together, these results indicate that rhein may be a potential inhibitor of Rac1 and can inhibit the migration and invasion of SKOV3-PM4 cells through modulating matrix metalloproteinases and RAC1/ROS/MAPK/AP-1 signaling pathway-associated proteins.

Inhibition of Anaphase-Promoting Complex by Silence APC/CCdh1 to Enhance Radiosensitivity of Nasopharyngeal Carcinoma Cells.

The aim of this study was to investigate the possibility of APC/CCdh1 as a potential therapeutic target in the radiosensitivity of nasopharyngeal carcinoma (NPC) cell CNE-1, and explain the role of APC subunits after silence of Cdh1 combined with radiotherapy. Transfection with Cdh1 shRNA significantly increased the radiosensitivity of CNE-1 cells and the radiation enhancement ratio (RER) of sh-Cdh1 cells was 1.76. Knockdown of Cdh1 in CNE-1 cells increased irradiation induced apoptosis and G2/M phase cell cycle arrest. The levels of CDC20 and CylinB1 increased and the levels of Ku70 and APC3 decreased after irradiation. APC/CCdh1 is involved in regulation of radiosensitivity in human NPC CNE-1 cells. Our study may provide a promising therapeutic strategy for NPC by targeting Cdh1. J. Cell. Biochem. 118: 3150-3157, 2017. © 2016 Wiley Periodicals, Inc.

The Enhancement of Radiation Sensitivity in Nasopharyngeal Carcinoma Cells via Activation of the Rac1/NADPH Signaling Pathway.

We reported in an earlier study that using mass spectrometry and bioinformatic analysis demonstrated Rac1 protein might be mostly mitochondrial target in the radiosensitization process of nasopharyngeal carcinoma CNE-1 cells. The goal of our current study was to reveal the relationship between Rac1/NADPH pathway and radiosensitization in CNE-1 cells using Rac1 activator, phorbol 12-myristate 13-acetate (PMA) and Rac1 inhibitor NSC23766. The Rac1-GTP expression was determined using a pulldown assay, the Rac1 location using a immunofluorescence with a laser scanning confocal microscope, the NADPH oxidase activity with NBT assay and the reactive oxygen species with DCFH-DA probe. The apoptosis rate was analyzed by flow cytometry, and the expressions of p67(phox) and NFκB-p105/p50 were analyzed by Western blot. After treatment with PMA and 2 Gy radiation (compared to the control), Rac1-GTP was activated and translocated to the cell membrane. NADPH oxidase activity, reactive oxygen species of intracellular concentration and the apoptosis rate increased significantly. The expression of p67(phox) and NFκB-p50 protein also increased. However, in the cells treated with NSC23766 alone or NSC23766 combined with 2 Gy irradiation, the results were just the opposite. Overall, these results indicate that the Rac1 protein may be the key target involved in the radiosensitization of nasopharyngeal carcinoma cells. The activated Rac1/NADPH pathway combined with radiation can increase the radiosensitivity of nasopharyngeal carcinoma cells, and the Rac1/NADPH pathway may be the signaling pathway involved in the radiosensitization process.

Protein expression of nucleophosmin, annexin A3 and nm23-H1 correlates with human nasopharyngeal carcinoma radioresistance in vivo.

Radioresistance is a significant obstacle in the treatment of endemic nasopharyngeal carcinoma (NPC). The present study aimed to identify proteins associated with radioresistance in NPC in vitro and in vivo. Proteomics analyses were conducted to screen for differentially-expressed proteins (DEPs) in parental CNE-2 cells and CNE-2R cells. Using proteomics approaches, 16 DEPs were identified. Of these DEPs, nucleophosmin (NPM1), annexin A3 and nm23-H1, were verified using western blot analyses. The tumorigenicity was investigated using mouse xenograft tumorigenicity assays, and tumor growth curves were generated. The protein expression of NPM1, annexin A3 and nm23-H1 was examined by immunohistochemically staining tumor tissues. NPM1 and annexin A3 protein levels were downregulated in the CNE-2R cells, whereas nm23-H1 expression was upregulated. In vivo tests showed that compared with the CNE-2 tumors, CNE-2R tumor growth was significantly retarded (P<0.05). CNE-2 tumor progression was inhibited by irradiation, but CNE-2R tumor progression was not, indicating that the CNE-2R cells were also radioresistant in vivo. NPM1 and annexin A3 expression was significantly lower in non-irradiated (NIR)-CNE-2R tumors compared with NIR-CNE-2 tumors (P<0.01). However, Nm23-H1 protein levels were significantly higher (P<0.05). Overall, the present study established comparable radioresistant and radiosensitive tumor models of human NPC, and identified candidate biomarkers that may correlate with radioresistance. The data showed that dysregulation of NPM1, annexin A3 and nm23-H1 expression correlated with the cellular and tumor radioresponse. These proteins are involved in the regulation of intracellular functions, including stress responses, cell proliferation and DNA repair. However, further clinical evaluations are required.