CGRP Released by Corneal Sensory Nerve Maintains Tear Secretion of the Lacrimal Gland.

Purpose: This study aims to elucidate the calcitonin gene-related peptide (CGRP) mediation and primary mechanism of corneal sensory nerves on tear production of the lacrimal gland. Methods: Mouse corneal denervation models were constructed through surgical axotomy, pharmacologic treatment with capsaicin or resiniferatoxin, and Trpv1-Cre/DTR mice with diphtheria toxin injection. The capsaicin-treated mice received subconjunctival injection of CGRP or substance P, while the normal C57BL/6J mice were administered with CGRP receptor antagonist BIBN-4096. Furthermore, double immunostaining of c-FOS+ and choline acetyltransferase was used to evaluate the activation of the superior salivatory nucleus (SSN). Mouse lacrimal glands were collected for transcriptomic sequencing and subsequent RNA and protein expression analysis. Results: The corneal denervated mice exhibited a significant reduction in corneal sensitivity and tear secretion. In capsaicin-treated mice, tear secretion decreased to 2.5 ± 0.5 mm compared to 6.3 ± 0.9 mm in control mice (P < 0.0001). However, exogenous administration of CGRP in capsaicin-treated mice increased tear secretion from 2.6 ± 0.5 mm to 4.5 ± 0.5 mm (P = 0.0009), while BIBN-4096 treatment reduced tear secretion to 3.4 ± 0.5 mm when compared to 7.3 ± 0.7 mm in control mice (P = 0.0022). Furthermore, c-FOS+ cell number in the SSN increased by twofold (P = 0.0168) after CGRP administration compared with capsaicin-treated mice. In addition, the expressions of CCNA2, Ki67, PCNA, and CDK1 in acinar cells of the lacrimal gland were impaired by corneal denervation and alleviated by CGRP administration. Conclusions: CGRP released by corneal sensory nerves mediates tear secretion of the lacrimal gland, providing a new strategy for improving tear secretion in patients with neurotrophic keratitis.

Establishment of mouse model of neurotrophic keratopathy through TRPV1 neuronal ablation.

Neurotrophic keratopathy (NK) is a challenging disease with the reduced innervation to the cornea. To establish a genetic and stable mouse model of NK, we utilized the TRPV1-DTR mice with intraperitoneal injection of diphtheria toxin (DT) to selectively eliminate TRPV1 neurons. After DT administration, the mice exhibited robust ablation of TRPV1 neurons in the trigeminal ganglion, accompanied with reduced corneal sensation and nerve density, as well as the decreased calcitonin-gene-related peptide (CGRP) and substance P levels. According to disease progression of TRPV1 neuronal ablation, tear secretion was reduced from day 3, which followed by corneal epithelial punctate lesions from day 7. From day 11 to day 16, the mice exhibited persistent corneal epithelial defects and stromal edema. By day 21, corneal ulceration and stromal melting were observed with the abundant inflammatory cell infiltration, corneal neovascularization, and enhanced cell apoptosis. Moreover, subconjunctival injection of CGRP delayed the NK progression with the characteristics of reduced severe corneal epithelial lesions and corneal inflammation. In addition, the impairments of conjunctival goblet cells, lacrimal gland, and meibomian gland were identified by the diminished expression of MUC5AC, AQP5, and PPARγ, respectively. Therefore, these results suggest that the TRPV1-DTR mice may serve as a reliable animal model for the research of NK pathogenesis.

Protective effect of Salvia plebeia R. Br ethanol extract on UVB-induced skin photoaging in vitro and in vivo.

BACKGROUND: UV exposure is one of the primary factors responsible for photoaging, causing the increase in matrix metalloproteinases (MMPs) and the reduction in collagen. Salvia plebeia R. Br (SP), as an herbaceous plant, contains abundant flavonoids and possesses excellent anti-inflammatory and antioxidant activities. This study aimed to investigate the photoprotective effects of SP on UVB-induced photodamage in immortalized human keratinocytes (HaCaTs) and Kunming mice, as well as its main active components such as homoplantaginin (HP). METHODS: CCK-8 was applied to detect the cell viability in UVB-irradiated or non-irradiated HaCaTs. Commercial kits were used to evaluate the levels of ROS, MDA, SA-ß-Gal, MMP-1, and IL-6. The expression of MAPK and TGF-ß/Smad pathways was detected by western blot. HE and Masson's trichrome staining were performed to examine the epidermis thickness and collagen degradation of Kunming mice. RESULTS: Our results found that SP and HP notably decreased UVB-induced ROS, MDA, and SA-ß-Gal production, and inhibited MMP-1 and IL-6 secretion by inhibiting the MAPK signaling pathway. In addition, SP and HP significantly promoted type I procollagen synthesis by activation of TGF-ß/Smad pathway. Consistently, the in vivo experiments also indicated that SP and HP had a photoprotective effect, which significantly reversed UVB-induced epidermis thickness and collagen degradation. CONCLUSION: This study demonstrated that SP effectively could protect skin from UVB-induced photoaging, while HP acted as the active substance in SP. All these findings provided a new strategy for skin photoaging treatment.

Proline metabolism reprogramming of trained macrophages induced by early respiratory infection combined with allergen sensitization contributes to development of allergic asthma in childhood of mice.

Background: Infants with respiratory syncytial virus (RSV)-associated bronchiolitis are at increased risk of childhood asthma. Recent studies demonstrated that certain infections induce innate immune memory (also termed trained immunity), especially in macrophages, to respond more strongly to future stimuli with broad specificity, involving in human inflammatory diseases. Metabolic reprogramming increases the capacity of the innate immune cells to respond to a secondary stimulation, is a crucial step for the induction of trained immunity. We hypothesize that specific metabolic reprogramming of lung trained macrophages induced by neonatal respiratory infection is crucial for childhood allergic asthma. Objective: To address the role of metabolic reprogramming in lung trained macrophages induced by respiratory virus infection in allergic asthma. Methods: Neonatal mice were infected and sensitized by the natural rodent pathogen Pneumonia virus of mice (PVM), a mouse equivalent strain of human RSV, combined with ovalbumin (OVA). Lung CD11b+ macrophages in the memory phase were re-stimulated to investigate trained immunity and metabonomics. Adoptive transfer, metabolic inhibitor and restore experiments were used to explore the role of specific metabolic reprogramming in childhood allergic asthma. Results: PVM infection combined with OVA sensitization in neonatal mice resulted in non-Th2 (Th1/Th17) type allergic asthma following OVA challenge in childhood of mice. Lung CD11b+ macrophages in the memory phage increased, and showed enhanced inflammatory responses following re-stimulation, suggesting trained macrophages. Adoptive transfer of the trained macrophages mediated the allergic asthma in childhood. The trained macrophages showed metabolic reprogramming after re-stimulation. Notably, proline biosynthesis remarkably increased. Inhibition of proline biosynthesis suppressed the development of the trained macrophages as well as the Th1/Th17 type allergic asthma, while supplement of proline recovered the trained macrophages as well as the allergic asthma. Conclusion: Proline metabolism reprogramming of trained macrophages induced by early respiratory infection combined with allergen sensitization contributes to development of allergic asthma in childhood. Proline metabolism could be a well target for prevention of allergic asthma in childhood.

Ppm1b Negatively Regulates 3-Bromopyruvate Induced Necroptosis in Breast Cancer Cells.

Up to 30% of breast cancer mortality is caused by cancer relapse despite primary clinical treatments due to distant metastases. Further research focusing on breast cancer mechanisms are needed for deeper understanding of disease prognosis. 3-bromopyruvate (3-BP), a glycolysis inhibitor, has been studied as one of the antitumor agents in recent years. In this report, we want to investigate the form of cell death induced by 3-BP and demonstrate the inhibitory effect of 3-BP on breast cancer cell proliferation and its mechanism in vivo and in vitro. We found that 3-BP could inhibit MDA-MB-231 and MCF-7 breast cancer cell proliferation, through energy metabolism inhibition. Further, necroptosis characters in MDA-MB-231 cells after 3-BP treatment were observed, which could be negatively regulated through Ppm1b by dephosphorylation of RIP3. In addition, 3-BP treatment in an MDA-MB-231 cell-transplanted mouse model showed a significant antitumor effect, which correlated with necroptosis-related protein Ppm1b. The findings demonstrate the potential for 3-BP in the treatment of breast cancer, providing impetus for further clinical studies.

[2-deoxyglucose inhibits angiogenesis of rheumatoid arthritis via activating AMPK pathway].

OBJECTIVE: To observe the effects of 2-deoxyglucose inhibiting synovial pannus of adjuvant arthritis rats and to explore its potential mechanism of inhibiting angiogenesis by investigating proliferation, migration and matrigel tube formation assay in vitro. METHODS: The effect of 2-DG on synovial pannus was evaluated by histopathology of HE staining; HUVEC proliferation was determined by CCK-8 method; migration of FLS were determined by transwell; In vitro matrigel tube formation assay was made for assessing tube number of HUVEC; p-AMPK and Bcl-2 were detected by Western blot assay; AMPK signaling pathway in HUVEC was inhibited by compound C, which is an inhibitor of AMPK activation. RESULTS: 2-DG (200 mg/kg) obviously decreased appearance of synovial pannus (P < 0.01); in vitro, 2-DG (0.5 mmol/L and/or 5 mmol/L) obviously inhibited proliferation, migration and tube number of HUVEC (P < 0.01 or P < 0.001), and its effects on HUVEC were reversed by using AMPK antagonist (Compound C); Western blot showed that 2-DG (5 mmol/L) increased expression of p-AMPK and decreased expression of Bcl-2 (P < 0.05). CONCLUSIONS: Activating AMPK pathway and decreasing expression of Bcl-2 may the potential mechanism by which 2-DG contributes to anti-angiogenesis and effects of inhibiting proliferation, migration and tube number of HUVEC.

[Chloroquine induces apoptosis of human hepatocellular carcinoma cells in vitro by miR-26b-mediated regulation of Mcl-1].

OBJECTIVE: To investigate the effect of chloroquine in inducing apoptosis of human hepatocellular carcinoma cells and explore the possible mechanism. METHODS: MTT assay and flow cytometry were used to evaluate chloroquine-induced growth inhibition and apoptosis in human hepatocellular carcinoma HepG2 cells, respectively. The ATP levels in chloroquine-treated cells were detected using an ATP assay kit. PCR and Western blotting were used to detect the expression levels of miR-26b and Mcl-1 in the cells, respectively. RESULTS: Chloroquine inhibited the proliferation of HepG2 cells in a time- and concentration-dependent manner. Treatments with 80 µmol/L chloroquine for 24, 48, and 72 h induced survival rates of (71.59∓0.2)%, (45.40∓0.5)%, and (26.34∓1.4)% in the cells. Treatments with chloroquine at 40, 80, and 160 µmol/L for 5 h resulted in obviously lowered intracellular ATP levels in the cells to 87.80%, 71.29%, and 38.02% of the control level, respectively. At 80 µmol/L, chloroquine significantly increased the expression of miR-26b and down-regulated the expression of Mcl-1 in HepG2 cells, and the application of the miR-26b inhibitor increased the cellular expression of Mcl-1. CONCLUSION: s Chloroquine can inhibit the cell proliferation, reduce ATP level and induce apoptosis in HepG2 cells possibly through miR-26b-mediated regulation of Mcl-1.

Synergistic antitumor effect of 3-bromopyruvate and 5-fluorouracil against human colorectal cancer through cell cycle arrest and induction of apoptosis.

3-Bromopyruvic acid (3-BP) is a well-known inhibitor of energy metabolism. It has been proposed as an anticancer agent as well as a chemosensitizer for use in combination with anticancer drugs. 5-Fluorouracil (5-FU) is the first-line chemotherapeutic agent for colorectal cancer; however, most patients develop resistance to 5-FU through various mechanisms. The aim of this study was to investigate whether 3-BP has a synergistic antitumor effect with 5-FU on human colorectal cancer cells. In our study, combined 3-BP and 5-FU treatment upregulated p53 and p21, whereas cyclin-dependent kinase CDK4 and CDK2 were downregulated, which led to G0/G1 phase arrest. Furthermore, there was an increase in reactive oxygen species levels and a decrease in adenosine triphosphate levels. It was also observed that Bax expression increased, whereas Bcl-2 expression reduced, which were indicative of mitochondria-dependent apoptosis. In addition, the combination of 3-BP and 5-FU significantly suppressed tumor growth in the BALB/c mice in vivo. Therefore, 3-BP inhibits tumor proliferation and induces S and G2/M phase arrest. It also exerts a synergistic antitumor effect with 5-FU on SW480 cells.

[Small interfering RNA-mediated monocarboxylate transporter 1 silencing enhances sensitivity of nasopharyngeal carcinoma HNE1/DDP cells to cisplatin-induced apoptosis].

OBJECTIVE: To investigate the effect of small interfering RNA (siRNA)-mediated silencing of monocarboxylate transporter 1 (MCT1) on the sensitivity of drug-resistant nasopharyngeal carcinoma HNE1/DDP cells to cisplatin (DDP)-induced apoptosis and explore the possible mechanism. METHODS: The expression of MCT1 was analyzed in HNE1 and HNE1/DDP cells and in HNE1/DDP cells transfected with siRNA using Western blot. MTT assay was used to assess the inhibitory effect of different concentrations of DDP alone or in combination with MCT1 siRNA on the proliferation of HNE1/DDP cells. The apoptosis of cells treated with MCT1 siRNA or/and DDP (8 µmol/L) was assessed using flow cytometry with PI staining, and the mitochondrial membrane potential was detected using JC-1 staining assay; the expressions of Mcl-1, Bak, Bcl-2, and Bax were analyzed using Western blotting. RESULTS: HNE1/DDP cells showed a high expression of MCT1, and MCT1 silencing using siRNA significantly increased the sensitivity of HNE1/DDP cells to DDP (P<0.05) and partly reversed DDP resistance of the cells. MCT1 silencing enhanced the sensitivity of HNE1/DDP cells to DDP-induced apoptosis. Treatment of HNE1/DDP cells with MCT1 siRNA combined with 8 µmol/L DDP for 24 h resulted in an apoptotic rate of (51.23∓2.86)%, significantly higher than that in cells treated with MCT1 siRNA or DDP alone (P<0.05). The combined treatment also reduced the mitochondrial membrane potential, down-regulated the expression of Mcl-1 and Bcl-2, and up-regulated the expression of Bax in the DDP-resistant cells. CONCLUSION: MCT1 siRNA can enhance the sensitivity of HNE1/DDP cells to DDP-induced apoptosis, the mechanism of which may involve the down-regulation of Mcl-1 and Bcl-2 and up-regulation of Bax expression.

Non-benzoquinone geldanamycin analogs trigger various forms of death in human breast cancer cells.

BACKGROUND: Hsp90 proteins are important therapeutic targets for many anti-cancer drugs in clinical trials. Geldanamycin (GA) was identified as the first natural inhibitor of Hsp90, increasing evidence suggests that GA was not a good choice for clinical trials. In this study, we investigated two new non-benzoquinone geldanamycin analogs of Hsp90 inhibitors, DHQ3 and 17-demethoxy-reblastatin (17-DR), to explore the molecular mechanisms of their anti-cancer activity in vivo and vitro. METHODS: MTT and colony formation assays were used to measure cell viability. Flow cytometry, DAPI staining, ATP assay, electron microscopy, western blots, siRNAs transfection and immunofluorescence were used to determine the molecular mechanism of DHQ3- or 17-DR-induced different forms of death in human breast cancer MDA-MB-231 cells. Malachite green reagent was used to measure ATPase activity of the analogs. RESULTS: DHQ3 and 17-DR presented efficiently inhibitory effect in MDA-MB-231 cell lines, and DHQ3 induced necroptosis by activation of the RIP1-RIP3-MLKL necroptosis cascade. And DHQ3-induced cell death was inhibited by a necroptosis inhibitor, necrostatin-1 (Nec-1), but not by a caspase inhibitor z-VAD-fmk. On the other hand, 17-DR induced apoptosis in MDA-MB-231 cells, indicating a caspase-dependent killing mechanism. We further demonstrated that down-regulation of RIP1 and RIP3 by siRNA protected against DHQ3 but not 17-DR induced cell death. These results were confirmed by electron microscopy. DHQ3 and 17-DR induced the degradation of Hsp90 client proteins, and they showed strong antitumor effects in MDA-MB-231 cell-xenografted nude mice. CONCLUSIONS: These findings supported that DHQ3 and 17-DR induce different forms of death in some cancer cell line via activation of different pathways. All of the results provided evidence for its anti-tumorigentic action with low hepatotoxicity in vivo, making them promising anti-breast cancer agents.

[Effects of LCL161, a Smac mimetic on the proliferation and apoptosis in hepatocellular carcinoma cells].

OBJECTIVE: To investigate the effects of LCL161, a Smac mimetic, on the proliferation and apoptosis in hepatocellular carcinoma cells and the underlying mechanisms. 
 METHODS: The effect of LCL161 on the cell viability of HepG2 and SMMC7721 cells was measured by MTT assay. The effect of LCL161 at lower concentrations on the proliferation in hepatocellular carcinoma (HCC) cells was detected by colony formation assay. Apoptosis was assessed by flow cytometry with PI staining. The mitochondrial membrane potential was measured by JC-1 staining. The expression of PARP, p-Akt, cIAP1 and XIAP protein was analyzed by Western blot.
 RESULTS: LCL161 displayed notable antiproliferative activity on HCC cells at the concentrations of 1-16 µmol/L (P<0.01), with IC50 values of 4.3 and 4.9 µmol/L for HepG2 and SMMC7721 cells, respectively, after treatment for 48 h. LCL161 at lower concentrations obviously inhibited the colony formation of HCC cells. LCL161 induced significant apoptosis in HCC cells (P<0.01), and resulted in the apoptotic rate at (1.5±0.8)% or (1.8±0.6)% , (15.2±2.8)% or (12.2±2.4)%, (28.7±3.0)% or (22.4±2.7)%, (34.6±2.3)% or (30.2±2.4)% for HepG2 cells or SMMC7721 cells at the concentration of 0, 2, 4 or 8 µmol/L, respectively. The result of JC-1 staining indicated that the mitochondrial membrane potential of HCC cells was reduced by LCL161. In addition, LCL161 promoted the cleavage of PARP, down-regulated the protein expression of p-Akt, and degraded cIAP1.
 CONCLUSION: LCL161 possesses significant anti-proliferative activity and pro-apoptotic action in HepG2 and SMMC7721 cells, which might be correlated with reduction in mitochondrial membrane potential, down-regulation of p-Akt and degradation of cIAP1.

Knockdown of GRP78 enhances cell death by cisplatin and radiotherapy in nasopharyngeal cells.

Radiotherapy and adjuvant cisplatin chemotherapy are the mainstream approaches in the treatment of nasopharyngeal carcinoma (NPC). These have been shown to effectively improve the outcome and reduce tumor recurrence. However, radiotherapy and chemotherapy resistance during the course of treatment has become more common recently, resulting in the failure of NPC therapy. Therefore, new therapeutic strategies or adjuvant drugs are urgently needed. The current study was designed to look for new treatment strategies or auxiliary drugs in the treatment of NPC. Two human NPC cell lines, HNE1 and HNE1/DDP, were used to examine the relationship between endoplasmic reticulum stress and cell resistance to ionizing radiation (IR) and cisplatin (DDP). Cell proliferation was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Meanwhile, propidium iodide (PI) staining and PI/Annexin V staining were used to observe cell apoptosis. Finally, western blot was used to detect the endogenous expression of glucose-regulated protein 78 (GRP78) and other apoptosis-related proteins. GRP78 small interference RNA was transfected using Lipofectamine 2000. Compared with HNE1/DDP, IR and DDP increased the cell apoptosis and inhibited the cell proliferation of HNE1. Inhibition of GRP78 can reverse IR and DDP resistance in NPC cells by PI/Annexin V staining. Knockdown of GRP78 upregulates the expression of pro-apoptotic proteins and downregulates the expression of antiapoptotic proteins. These results indicate that HNE1 is more sensitive to DDP and IR than HNE1/DDP. Knockdown GRP78 can reverse IR and DDP resistance in NPC cells. Inhibition of GRP78 gives us a new target to overcome resistance to radiotherapy and chemotherapy of NPC cells. Thus, this study should be further explored in vivo and assessed for possible clinical applications.

[Autophagy inhibitor 3-methyladenine enhances the sensitivity of nasopharyngeal carcinoma cells to chemotherapy and radiotherapy].

OBJECTIVE: To explore the effects of 3-methyladenine (3-MA, an autophagy inhibitor) on sensitivities of nasopharyngeal carcinoma cells to radiotherapy and chemotherapy and the underlying mechanisms.
 METHODS: Cell proliferation was examined by MTT and colony formation assay, while cell apoptosis was evaluated by annexin V/PI double staining and 2-(4-Amidinophenyl)-6-indolecarbamidine dihydrochloride (DAPI) staining. Mitochondrial membrane potential was measured by commercial kit (JC-1). The expression of endoplasmic reticulum stress (ERS)-related protein, glucose-regulated protein 78 (GRP78) and autophagy-related protein beclin1, microtubule-associated protein 1 light chain 3 (LC3) were examined by Western blot.
 RESULTS: Cisplatin (DDP), ionizing radiation (IR) or tunicamycin (TM) treatment obviously inhibited the proliferation of HONE-1 cells in a concentration-dependent and time-dependent manner. Compared with control group, pretreatment with 1 mmol/L of 3-MA significantly reduced cell viability and enhanced the apoptosis in the DDP (6.00 µmol/L), 4.00 Gy IR or TM (1.00 µmol/L) groups. There was no significant difference in the apoptosis between the DDP (5.8%) and 4Gy IR (6.7%) groups. Compared with the control group, protein levels of GRP78, beclin1 and lipid-conjugated membrane-bound form (LC3-II) were significantly increased after the treatment of DDP, 4.00 Gy IR or TM, which were inhibited by pretreatment of 3-MA.
 CONCLUSION: 3-MA can sensitize HONE-1 cells to chemotherapy and radiotherapy, which is related to prevention of endoplasmic reticulum stress-induced autophagy in nasopharyngeal carcinoma cells.

[Effect of low-molecular-weight heparin combined with doxorubicin on hepatocellular cancer cell migration in vitro].

OBJECTIVE: To investigate the anti-cancer effect of low-molecular-weight heparin (LMWH) combined with doxorubicin and explore the mechanism. METHODS: Hepatocellular cancer HepG2 cells exposed to LMWH, doxorubicin, or both were evaluated for cell viability with MTT assay and for changes in their migration ability using wound healing assay and Transwell migration assay. The changes in cellular expressions of matrix metalloproteinase-9 (MMP-9) and MMP-2 mRNA and proteins were analyzed with quantitative real-time PCR (qRT-PCR) and Western blotting, and ELISA was used to determine heparanase (HPA) concentration in the cell culture medium. RESULTS: HepG2 cells exhibited suppressed proliferation in response to LMWH and doxorubicin treatments. The combined treatment caused a significantly higher inhibition rate of cell migration than LMWH and doxorubicin alone. LMWH enhanced doxorubicin-induced down-regulation of MMP-9, MMP-2 and HPA in the cells. CONCLUSIONS: LMWH can enhance the inhibitory effect of doxorubicin on the migration of HepG2 cells, the mechanism of which may involve the down-regulation of MMP-9, MMP-2 and HPA expressions.

Inhibition of autophagy by 3-MA enhances endoplasmic reticulum stress-induced apoptosis in human nasopharyngeal carcinoma cells.

Radiotherapy and adjuvant cisplatin chemotherapy are the mainstream treatments for nasopharyngeal carcinoma (NPC), which effectively improve the outcome and reduce tumor recurrence. However, the resistance mechanism(s) involved in radiotherapy and chemotherapy, which is the main barrier in NPC treatment, remains undefined. Therefore, there is an urgent requirement for the identification of new therapeutic strategies or adjuvant drugs. In the present study, the effects of autophagy inhibitors on endoplasmic reticulum (ER) stress-induced autophagy was investigated. Combining 3-methyladenine (3-MA) with cisplatin (DDP), ionizing radiation (IR), 2-deoxy-D-glucose (2-DG) or tunicamycin (TM) resulted in enhanced cell death, as revealed by MTT and colony formation assays. Flow cytometry results demonstrated that the sensitivity of NPC cells to DDP- and IR-induced apoptosis was not significant. DDP, IR, 2-DG and TM induced ER stress and autophagy. Using fluorescence microscopy, 3-MA was identified to increase the apoptotic cell death induced by DDP, IR, 2-DG or TM. In addition, 3-MA inhibited the increased autophagy induced by DDP, IR, 2-DG or TM, as demonstrated by western blot analysis and immunocytochemistry results. Results of the present study indicate that autophagy acts as a protective mechanism response to the apoptosis induced by DDP, IR, 2-DG or TM.

[Effect of tunicamycin combined with cisplatin on proliferation and apoptosis of human nasopharyngeal carcinoma cells in vitro].

OBJECTIVE: To study the effects of tunicamycin (a glycosylation inhibitor) combined with cisplatin on the proliferation and apoptosis of human nasopharyngeal carcinoma cells and explore the molecular mechanism. METHODS: Nasopharyngeal carcinoma CNE-1 and CNE-2 cells cultured in vitro were treated with different concentrations of tunicamycin with or without cisplatin. The inhibition of cell proliferation was examined using MTT assay and colony formation assay, and the cell apoptosis was analyzed using flow cytometry with propidium iodide staining. The expressions of Bax, Bcl-2, and GRP78 in cells treated with 3 µmol/L tunicamycin with or without 6.00 µmol/L cisplatin were measured with Western blotting. RESULTS: Treatment with tunicamycin or cisplatin obviously inhibited the proliferation of CNE-1 and CNE-2 cells. Treatment with 3 µmol/L tunicamycin for 24, 36 and 48 h resulted in a viability of 72.13%, 51.97%, and 37.56% in CNE-1 cells and 85.61%, 56.95%, and 43.66% in CNE-2 cells, respectively, and the combined treatment with 6 µmol/L cisplatin lowered the cell viability to 67.97%, 47.76%, and 34.68% in CNE-1 cells and 56.89%, 37.05%, and 29.30% in CNE-2 cells, respectively. Tunicamycin at 0.3 µmol/L combined with 0.6 µmol/L cisplatin showed an obviously enhanced inhibitory effect on colony formation of CNE-1 and CNE-2 cells. Tunicamycin treatment (3 µmol/L) of CNE-1 and CNE-2 cells for 48 h induced an apoptosis rate of only 8.89% and 8.67%, but when combined with 6 µmol/L cisplatin, the cell apoptosis rate increased to 37.02% and 32.25%, significantly higher than that in cells with cisplatin treatment alone (7.25% and 6.36%, respectively). Compared with tunicamycin and cisplatin alone, the combined treatment significantly increased Bax expression and decreased Bcl-2 expression in the cells; tunicamycin up-regulated the expression of GRP-78 and enhanced the activity of caspase-3. CONCLUSION: Tunicamycin can inhibit the proliferation of CNE-1 and CNE-2 cells and enhance cisplatin-induced cell death, the mechanism of which may involve excessive endoplasmic reticulum stress response and increased activity of caspase-3.