A novel role of sympathetic activity in regulating mitral valve prolapse.

BACKGROUND: Increased sympathetic activity, commonly reported in mitral valve prolapse, indicates that the sympathetic nervous system might play an important role in regulating mitral interstitial cells. Hence, the aim of this study is to determine the level and pattern of adrenergic receptors expressed in human mitral valve leaflets and to investigate the effect of norepinephrine on physiologic behaviors of mitral interstitial cells. METHODS AND RESULTS: Immunohistochemistry displayed significantly increased expressions of ß1, ß2, and α1 adrenergic receptors in mitral valve prolapse. Norepinephrine was found to activate the phenotype of interstitial cells with increased α-SMA expression (2.26 fold). In synthesis, norepinephrine downregulated levels of mRNA for type I to type III collagen in ratio, but increased the elastin gene transcription and glycosaminoglycan levels in valve interstitial cells greatly. In view of the extracellular matrix remodel, sympathetic effects presented catabolic metabolism displaying significantly increased expressions of total, secretory and active MMP-2 protein (matrix metalloproteinase-2), as well as MMP-9 protein. Diminished MMP inhibitor expression, TIMP2, also could reflect this effect in the norepinephrine medium. CONCLUSIONS: A novel role for the sympathetic effect in influencing physiologic behaviors in mitral interstitial cells was identified. It is indicated that sympathetic activity could promote myxomatous degeneration in mitral valve prolapse, propagating the disease severity, which might identify potential therapeutic targets.

Optical coherence tomography enhanced depth imaging of chorioretinal folds in patients with orbital tumors.

AIM: To characterize spectral-domain optical coherence tomography (SD-OCT) features of chorioretinal folds in orbital mass imaged using enhanced depth imaging (EDI). METHODS: Prospective observational case-control study was conducted in 20 eyes of 20 patients, the uninvolved eye served as a control. All the patients underwent clinical fundus photography, computed tomography, EDI SD-OCT imaging before and after surgery. Two patients with cavernous hemangiomas underwent intratumoral injection of bleomycin A5; the remaining patients underwent tumor excision. Patients were followed 1 to 14mo following surgery (average follow up, 5.8mo). RESULTS: Visual acuity prior to surgery ranged from 20/20 to 20/200. Following surgery, 5 patients' visual acuity remained unchanged while the remaining 15 patients had a mean letter improvement of 10 (range 4 to 26 letters). Photoreceptor inner/outer segment defects were found in 10 of 15 patients prior to surgery. Following surgical excision, photoreceptor inner/outer segment defects fully resolved in 8 of these 10 patients. CONCLUSION: Persistence of photoreceptor inner/outer segment defects caused by compression of the globe by an orbital mass can be associated with reduced visual prognosis. Our findings suggest that photoreceptor inner/outer segment defects on EDI SD-OCT could be an indicator for immediate surgical excision of an orbital mass causing choroidal compression.

Mechanism of Acupuncture and Moxibustion on Promoting Mucosal Healing in Ulcerative Colitis.

The latest guideline about ulcerative colitis (UC) clinical practice stresses that mucosal healing, rather than anti-inflammation, is the main target in UC clinical management. Current mucosal dysfunction mainly closely relates to the endoscopic intestinal wall (mechanical barrier) injury with the imbalance between intestinal epithelial cells (IECs) regeneration and death, as well as tight junction (TJ) dysfunction. It is suggested that biological barrier (gut microbiota), chemical barrier (mucus protein layer, MUC) and immune barrier (immune cells) all take part in the imbalance, leading to mechanical barrier injury. Lots of experimental studies reported that acupuncture and moxibustion on UC recovery by adjusting the gut microbiota, MUC and immune cells on multiple targets and pathways, which contributes to the balance of IEC regeneration and death, as well as TJ structure recovery in animals. Moreover, the validity and superiority of acupuncture and moxibustion were also demonstrated in clinic. This study aims to review the achievements of acupuncture and moxibustion on mucosal healing and analyse the underlying mechanisms.

[Fundus fluorescein angiography in metastatic choroidal carcinomas and differentiating metastatic choroidal carcinomas from primary choroidal melanomas].

OBJECTIVE: To investigate the characteristics of fundus fluorescein angiography (FFA) in metastatic choroidal carcinomas and determine the value of FFA in differentiating metastatic choroidal carcinomas from primary choroidal melanomas. METHODS: It was a retrospective case series. The retrospective analysis of clinical data and FFA findings was performed in 23 eyes of 22 patients with metastatic choroidal carcinomas and 31 eyes of 31 patients with primary choroidal melanomas as the control. RESULTS: Ocular fundus findings of metastatic choroidal carcinomas were divided into three types: solitary flat (tumor thickness less than 3 mm), solitary elevated (tumor thickness more than 3 mm) or diffuse type. FFA of the three types showed hypofluorescence during the arterial phase and progressive hyperfluorescence during the subsequent phases. The border of the lesions revealed retinal capillary dilation during the arteriovenous phase and persistent pinpoint leakage throughout the angiogram. Retinal capillary dilation and pinpoint leakage were more frequently presented in the solitary flat type. Simultaneous visualization of retinal and tumor circulation (the so called double circulation) was more frequently presented in the solitary elevated type. Pinpoint leakage could be detected in 17 (73.91%) eyes of metastatic choroidal carcinomas and in 5 (16.13%) eyes of primary choroidal melanomas. The difference between the visibility of pinpoint leakage in metastatic choroidal carcinomas and primary choroidal melanomas was statistically significant (P = 0.0000). When pinpoint leakage of FFA was used to differentiate metastatic choroidal carcinomas from primary choroidal melanomas, the sensitivity, specificity, accuracy, positive and negative predictive values were 73.91%, 83.87%, 79.63%, 77.27%, 81.25% respectively. CONCLUSIONS: FFA is helpful for the diagnosis of metastatic choroidal carcinomas. Pinpoint leakage on the border of lesions has some value in differentiating metastatic choroidal carcinomas from primary choroidal melanomas.

[Transplantation of bone marrow-derived endothelial progenitor cells preconditioned with ex vivo 17ß-estradiol enhances healing efficacy after acute myocardial infarction].

OBJECTIVE: To investigate the therapeutic efficacy of intravenous implanted bone marrow-derived endothelial progenitor cells (BM-EPC) preconditioned with 17ß-estradiol in ovariectomized mice model of acute myocardial infarction (AMI). METHODS: BM-EPC were cultured and identified from ovariectomized BALB/C mice tibia and femur. The ovariectomized BALB/C mice models of acute myocardial infarction (AMI) were established, and randomly divided into 17ß-estradiol + BM-EPC group (n = 6), BM-EPC group (n = 6) and control group (n = 6). Three days after AMI, BM-EPC pretreated with or without 17ß-estradiol was infused via tail vein. The equal volume of saline was infused in control group. Twenty-five days after infusion, left ventricular (LV) function and dimensions, capillary density and ratio of fibrosis area to LV area were measured. RESULTS: LV function and dimensions, capillary density and LV fibrosis were significantly improved in 17ß-estradiol + BM-EPC group than in control group [(LVDs: (3.09 ± 0.05) mm vs. (3.27 ± 0.10)mm, P < 0.05; LVDd: (4.18 ± 0.07) mm vs. (4.31 ± 0.05) mm, P < 0.05; FS: (33.0 ± 3.8)% vs. (26.0 ± 3.2)%, P < 0.05; capillary density: (1428 ± 214)/mm² vs. (1070 ± 168)/mm², P < 0.05; ratio of fibrosis: (38.8 ± 4.9)% vs. (49.0 ± 4.6)%, P < 0.05]. However, Above mentioned parameters were similar between BM-EPC group and control group (P > 0.05). CONCLUSIONS: BM-EPC preconditioned with 17ß-estradiol can enhance capillary density, decrease LV fibrosis and improve cardiac function in this mice model of AMI.

Learning curve associated with thoraco-laparoscopic esophagectomy for esophageal cancer patients in the prone position.

OBJECTIVE: To observe the surgical index at the different learning stages of thoraco-laparoscopic esophagectomy in the prone position for esophageal cancer and to investigate the learning curve of this surgical procedure. METHODS: Sixty thoraco-laparoscopic esophagectomies in the prone position for esophageal cancer conducted by the same group of surgeons between January 2014 and December 2015 were retrospectively analyzed. The surgeries were divided into 5 groups, A, B, C, D, and E, in chronological order. The duration of surgery, intraoperative blood loss, total number of lymph nodes removed, rate of the intraoperative conversion to open surgery, complication rate, and length of postoperative hospitalization were recorded and analyzed. RESULTS: The general information of the patients did not significantly differ among the 5 groups (P > 0.05). The duration of surgery, intraoperative blood loss, number of lymph node removed, rate of intraoperative conversion to open surgery, and number of injuries to the recurrent laryngeal nerve all significantly differed (P < 0.05). The rates of postoperative pulmonary infection, anastomotic fistula, pneumothorax, and hospitalization did not significantly differ (P > 0.05). CONCLUSION: Thoracic physicians with some endoscopic experience can meet the requirements of the thoraco-laparoscopic esophagectomy in the prone position for esophageal cancer after completing 24-30 surgeries.

A Novel Strategy for Decoding and Validating the Combination Principles of Huanglian Jiedu Decoction From Multi-Scale Perspective.

Traditional Chinese medicine (TCM) formulas treat complex diseases through combined botanical drugs which follow specific compatibility rules to reduce toxicity and increase efficiency. "Jun, Chen, Zuo and Shi" is one of most used compatibility rules in the combination of botanical drugs. However, due to the deficiency of traditional research methods, the quantified theoretical basis of herbal compatibility including principles of "Jun, Chen, Zuo and Shi" are still unclear. Network pharmacology is a new strategy based on system biology and multi-disciplines, which can systematically and comprehensively observe the intervention of drugs on disease networks, and is especially suitable for the research of TCM in the treatment of complex diseases. In this study, we systematically decoded the "Jun, Chen, Zuo and Shi" rules of Huanglian Jiedu Decoction (HJD) in the treatment of diseases for the first time. This interpretation method considered three levels of data. The data in the first level mainly depicts the characteristics of each component in single botanical drug of HJD, include the physical and chemical properties of component, ADME properties and functional enrichment analysis of component targets. The second level data is the characterization of component-target-protein (C-T-P) network in the whole protein-protein interaction (PPI) network, mainly include the characterization of degree and key communities in C-T-P network. The third level data is the characterization of intervention propagation properties of HJD in the treatment of different complex diseases, mainly include target coverage of pathogenic genes and propagation coefficient of intervention effect between target proteins and pathogenic genes. Finally, our method was validated by metabolic data, which could be used to detect the components absorbed into blood. This research shows the scientific basis of "Jun-Chen-Zuo-Shi" from a multi-dimensional perspective, and provides a good methodological reference for the subsequent interpretation of key components and speculation mechanism of the formula.

[Experimental study on mechanical properties of decellularized porcine aortic valve and effects of precoating methods of biological scaffold on histocompatibility].

OBJECTIVE: To observe the mechanical properties of decellularized porcine aortic valve, and to explore the effects of precoating methods of biological scaffold on histocompatibility. METHODS: Fresh porcine aortic valves were decellularized using trypsin, TritonX-100 and nuclease. Treated valves were evaluated by light microscopy, scanning electron microscopy (SEM) and mechanical test. Three groups of scaffold were precoated with phosphate buffered saline (PBS), poly-L-lysine (PLL) and fetal bovine serum (FBS) respectively. Myofibroblasts were seeded onto each scaffold. Light and electron microscopic observation was performed and MTT test was used to examine efficiency of cell attachment. RESULTS: HE stain and SEM showed that cells were almost absent in the treated leaflet. The wave-like collagen together with the whole three-dimensional structure was maintained. Compared with normal valves, the Max-load, Max-stress and elastic modulus decreased while the Max-strain increased (P<0.05). The result of MTT test showed more cells were attached on the valves treated with FBS compared to the other two groups. Histological investigations also confirm that the high degree of cell attachment on the valves precoated with FBS (F=129.26, P=0.000). CONCLUSIONS: Enzyme combined with detergent and nucleases can remove cells from porcine aortic valves. Meanwhile the mechanical properties of these valves may be altered. Precoating porcine aortic valve with FBS is an effective method to improve cell attachment, growth and increasing.

[Protective effect of the cholinergic anti-inflammatory pathway against hemorrhagic shock in rats].

OBJECTIVE: To investigate the effect of the cholinergic anti-inflammatory pathway on hemodynamics in hemorrhaged rats. METHODS: Hemorrhagic shock was induced by modified Wiggers method until mean arterial pressure (MAP) was stabilized within the range of 35 to 40 mm Hg (1 mmHg=0.133 kPa). Thirty male Sprague-Dawley rats were randomly divided into six groups: sham group, hemorrhagic shock (Hem) group, vagotomy (VGX) group, vagus stimulation (STM) group, cholinergic inhibitor (THA) group and N receptor inhibitor (alpha-BGT) group. The distal end of the left vagus nerve trunk was placed on bipolar platinum electrode connected to a stimulation module and controlled by an acquisition system. Stimuli with constant voltage (5 V, 2 ms, 1 Hz) were applied to nerve for 12 minutes, starting 5 minutes after MAP stabilized at a level of 35 to 40 mmHg. Before stimulation a blood pressure transducer was implanted in the common carotid artery for continuous registration of MAP. Blood samples and liver samples were collected from animals of all groups after stimulation. Serum levels of tumor necrosis factor-alpha (TNF-alpha) and liver nuclear factor kappa-B (NF-KappaB) were determined. RESULTS: MAP was markedly lowered at the end of bleeding, and the levels of serum TNF-alpha and liver NF-KappaB markedly increased 45 minutes after the bleeding was discontinued. Bilateral cervical vagotomy did not significantly modify the changes in serum TNF-alpha, but slightly increased liver NF-KappaB activation. Application of constant electric current to the distal end of the vagus trunk significantly reduced serum TNF-alpha and blunted liver NF-KappaB activation. Tetrahydroamino-acridine (THA,1.5 mg/kg, intravenous drip administration after bilateral cervical vagotomy reversed hypotension and attenuated serum TNF-alpha and liver NF-KappaB amounts, but alpha-bungarotoxin (1.0 microg/kg intravenous drip) pretreatment reverted the inhibitory effects of vagal stimulation. CONCLUSION: The result suggest that direct electrical stimulation of the vagus nerve and its transmitter can significantly attenuate peak serum TNF-alpha amounts, inhibit the expression of liver NF-KappaB, and prevent the development of hypotension, thus it might produce a potential protective effect on hemorrhaged rats through acetylcholine (Ach) binds NAch receptor alpha 7 subunit which exists in the macrophage.

Distinct role and functional mode of TR3 and RARalpha in mediating ATRA-induced signalling pathway in breast and gastric cancer cells.

All-trans retinoic acid (ATRA) affects cell proliferation, differentiation and apoptosis through its receptors, RARs and RXRs. Besides these, other receptors such as orphan receptor TR3, are also involved in the regulatory process of ATRA. However, how different receptors function in response to ATRA is still largely unknown. In the present study, we found that formation of TR3/RXRalpha heterodimers in the nucleus and their subsequent translocation into the cytoplasm, in association with regulation of apoptosis-related proteins Bcl-2, Bcl-xl and Bax, was critical for apoptosis induction by ATRA in breast cancer cells MCF-7. When such translocation was blocked by Leptomycin B (LMB), ATRA-induced apoptosis was consequently abolished. However, in ATRA-induced gastric cancer cells MGC80-3, RXRalpha heterodimerised with RARalpha but not with TR3, and remained in the nucleus exerting its effect on cell cycle regulation. When transfected with antisense-RARalpha, MGC80-3 cells changed from ATRA-sensitive to ATRA-resistant and most cells were arrested in the S phase, implying the importance of RARalpha in cell cycle regulation. Furthermore, we demonstrated that the effects of ATRA depend on the relative levels of TR3, RARalpha and RXRalpha expression in cancer cells. In ATRA-induced MCF-7 cells, highly expressed TR3 favours the formation of TR3/RXRalpha and promotes the TR3/RXRalpha signalling pathway causing apoptosis; while in ATRA-induced MGC80-3 cells, high expression of RARalpha favours the formation of RARalpha/RXRalpha and promotes the RXRalpha/RARalpha signalling pathway in mediating cell cycle regulation. In conclusion, these results reveal the novel mechanism that cellular expression and location of protein is associated with diverse signalling transduction pathways and the resultant physiological process.

Ubiquitinated or sumoylated retinoic acid receptor alpha determines its characteristic and interacting model with retinoid X receptor alpha in gastric and breast cancer cells.

Retinoic acid receptor alpha (RARalpha) plays an important role in mediating all-trans retinoic acid (ATRA) signals. In this study, we found that ATRA up-regulated RARalpha mRNA and protein expression in gastric cancer BGC-823 cells. However, in breast cancer MCF-7 cells it down-regulated RARalpha protein expression with no effect on its RARalpha mRNA. Immunoprecipitation/Western blot analysis showed that, although sumoylated and ubiquitinated RARalpha existed simultaneously in both cancer cell lines, ATRA exerted different regulatory effects on sumoylation and ubiquitination of RARalpha. In MCF-7 cells, ATRA treatment enhanced the ubiquitination of RARalpha and the subsequent degradation of RARalpha through the ubiquitin/proteasome pathway. This resulted in a reduction in the DNA binding activity of RARalpha/retinoid X receptor alpha (RXRalpha) heterodimer, the separation of RXRalpha from RARalpha and the translocation of RXRalpha from the nucleus to the cytoplasm. By contrast, in BGC-823 cells, ATRA augmented sumoylation, not ubiquitination, of RARalpha. The stability of sumoylated RARalpha was significantly stronger than in non-sumoylated RARalpha. These results also showed an increase in the DNA binding activity of the RARalpha/RXRalpha heterodimer and the stability of nuclear localization of this heterodimer, which normally facilitates the ATRA signal transduction. In conclusion, our results reveal a novel mechanism for the regulation of RARalpha-dependent signal transduction through the ubiquitin/proteasome pathway in breast cancer cells and the sumoylation pathway in gastric cancer cells.

Induction of apoptosis by TPA and VP-16 is through translocation of TR3.

AIM: To investigate the role of TR3 in induction of apoptosis in gastric cancer cells. METHODS: Human gastric cancer cell line, MGC80-3, was used. Expression of TR3 mRNA and its protein was detected by Northern blot and Western blot. Localization of TR3 protein was showed by immunofluorescence analysis under laser-scanning confocal microscope. Apoptotic morphology was observed by DAPI fluorescence staining, and apoptotic index was counted among 1000 cells randomly. Stable transfection assay was carried out by Lipofectamine. RESULTS: Treatment of MGC80-3 cells with TPA and VP-16 resulted in apoptosis, accompanied by the repression of Bcl-2 protein in a time-dependent manner. At the same time, TPA and VP-16 also up-regulated expression level of TR3 mRNA in MGC80-3 cells that expressed TR3 mRNA. When antisense-TR3 expression vector was transfected into the cells, expression of TR3 protein was repressed. In this case, TPA and VP-16 did not induce apoptosis. In addition, TPA and VP-16-induced apoptosis involved in translocation of TR3. In MGC80-3 cells, TR3 localized concentrative in nucleus, after treatment of cells with TPA and VP-16, TR3 translocated from nucleus to cytosol obviously. However, when this nuclear translocation was blocked by LMB, apoptosis was not occurred in MGC80-3 cells even in the presence of TPA and VP-16. CONCLUSION: Induction of apoptosis by TPA and VP-16 is through induction of TR3 expression and translocation of TR3 from nucleus to cytosol, which may be a novel signal pathway for TR3, and represent the new biological function of TR3 to exert its effect on apoptosis in gastric cancer cells.

Roles of PLC-gamma2 and PKCalpha in TPA-induced apoptosis of gastric cancer cells.

AIM: To investigate the roles of PLCgamma2 and PKCalpha in TPA-induced apoptosis of gastric cancer cells. METHODS: Human gastric cancer cell line MGC80-3 was used. Protein expression levels of PLCgamma2 and PKCalpha were detected by Western blot. Protein localization of PLCgamma2 and PKCalpha was shown by immunofluorescence analysis under laser-scanning confocal microscope. Apoptotic morphology was observed by DAPI fluorescence staining, and apoptotic index was counted among 1,000 cells randomly. RESULTS: Treatment of gastric cancer cells MGC80-3 with TPA not only up-regulated expression of PLC-gamma2 protein, but also induced PLC-gamma2 translocation from the cytoplasm to the nucleus. However, this process was not directly associated with apoptosis induction. Further investigation showed that PKCalpha translocation from the cytoplasm to the nucleus was correlated with initiation of apoptosis. To explore the inevitable linkage between PLC-gamma2 and PKCalpha during apoptosis induction, PLC inhibitor U73122 was used to block PLC-gamma2 translocation, in which neither stimulating PKCalpha translocation nor inducing apoptosis occurred in MGC80-3 cells. However, when U73122-treated cells were exposed to TPA, not only PLC-gamma2, but also PKCalpha was redistributed. On the other hand, when cells were treated with PKC inhibitor alone, PLC-gamma2 protein was still located in the cytoplasm. However, redistribution of PLC-gamma2 protein occurred in the presence of TPA, no matter whether PKC inhibitor existed or not. CONCLUSION: PLC-gamma2 translocation is critical in transmitting TPA signal to its downstream molecule PKCalpha. As an effector, PKCalpha directly promotes apoptosis of MGC80-3 cells. Therefore, protein translocation of PLCgamma2 and PKCalpha is critical event in the process of apoptosis induction.

Degradation of retinoid X receptor alpha by TPA through proteasome pathway in gastric cancer cells.

AIM: To investigate and determine the mechanism and signal pathway of tetradecanoylphorbol-1, 3-acetate (TPA) in degradation of RXRalpha. METHODS: Gastric cancer cell line, BGC-823 was used in the experiments. The expression level of RXRalpha protein was detected by Western blot. Nuclear and cytoplasmic protein fractions were prepared through lysis of cell and centrifugation. Localization and translocation of RXRalpha were observed under laser-scanning confocal microscope through labeling specific anti-RXRalpha antibody and corresponding immunofluorescent antibody as secondary antibody. Different inhibitors were used as required. RESULTS: In BGC-823 cells, RXRalpha was expressed in the nucleus. When cells were treated with TPA, expression of RXRalpha was repressed in a time-dependent and TPA-concentration-dependent manner. Meanwhile, translocation of RXRalpha from the nucleus to the cytoplasm occurred, also in a time-dependent manner. When cells were pre-incubated with proteasome inhibitor MG132 for 3 hrs, followed by TPA for another 12 hrs, TPA-induced RXRalpha degradation was inhibited. Further observation of RXRalpha translocation in the presence of MG132 showed that MG-132 could block TPA-induced RXRalpha redistribution. Conversely, when RXRalpha translocation was inhibited by LMB, an inhibitor for blocking protein export from the nucleus, TPA could not repress expression of RXRalpha. CONCLUSION: TPA could induce the degradation of RXRalpha protein in BGC-823 cells, and this degradation is time- and TPA-concentration-dependent. Furthermore, the degradation of RXRalpha by TPA is via a proteasome pathway and associated with RXRalphatranslocation from the nucleus to the cytoplasm.

Knockout of the tumor suppressor gene Gprc5a in mice leads to NF-kappaB activation in airway epithelium and promotes lung inflammation and tumorigenesis.

Mouse models can be useful for increasing the understanding of lung tumorigenesis and assessing the potential of chemopreventive agents. We explored the role of inflammation in lung tumor development in mice with knockout of the tumor suppressor Gprc5a. Examination of normal lung tissue and tumors from 51 Gprc5a(+/+) (adenoma incidence, 9.8%; adenocarcinoma, 0%) and 38 Gprc5a(-/-) mice (adenoma, 63%; adenocarcinoma, 21%) revealed macrophage infiltration into lungs of 45% of the Gprc5a(-/-) mice and 8% of Gprc5a(+/+) mice and the direct association of macrophages with 42% of adenomas and 88% of adenocarcinomas in the knockout mice. Gprc5a(-/-) mouse lungs contained higher constitutive levels of proinflammatory cytokines and chemokines and were more sensitive than lungs of Gprc5a(+/+) mice to stimulation of NF-kappaB activation by lipopolysaccharide in vivo. Studies with epithelial cells cultured from tracheas of Gprc5a(-/-) and Gprc5a(+/+) mice revealed that Gprc5a loss is associated with increased cell proliferation, resistance to cell death in suspension, and increased basal, tumor necrosis factor alpha-induced, and lipopolysaccharide-induced NF-kappaB activation, which were reversed partially in Gprc5a(-/-) adenocarcinoma cells by reexpression of Gprc5a. Compared with Gprc5a(+/+) cells, the Gprc5a(-/-) cells produced higher levels of chemokines and cytokines and their conditioned medium induced more extensive macrophage migration. Silencing Gprc5a and the p65 subunit of NF-kappaB in Gprc5a(+/+) and Gprc5a(-/-) cells, respectively, reversed these effects. Thus, Gprc5a loss enhances NF-kappaB activation in lung epithelial cells, leading to increased autocrine and paracrine interactions, cell autonomy, and enhanced inflammation, which may synergize in the creation of a tumor-promoting microenvironment.

Dual roles of Nur77 in selective regulation of apoptosis and cell cycle by TPA and ATRA in gastric cancer cells.

Nur77 is an orphan receptor. Although Nur77 affects cell proliferation and apoptosis through its capability of binding to a variety of response elements and regulating their transactivation activities, the intrinsic function of Nur77 is not yet fully understood; in particular, its regulation of apoptosis and proliferation has been characterized as cell type-dependent and agent context-dependent. In this study, Nur77 can be seen to regulate apoptosis via its expression and translocation, rather than its transactivation activity in gastric cancer cells. Nur77 was constitutively expressed in BGC-823 cells. The tetradecanoylphorbol-1,3-acetate (TPA) treatment not only resulted in up-regulation of the Nur77 mRNA level, but also led to translocation of Nur77 protein from the nucleus to the mitochondria, and caused the release of cytochrome c. This TPA-induced translocation of Nur77 was in association with the initiation of apoptosis in gastric cancer cells. Although all-trans retinoic acid (ATRA) could not induce apoptosis in BGC-823 cells due to failure of stimulating Nur77 translocation, expression of Nur77 in the nucleus was required for cell growth inhibition by ATRA. Transfection of antisense Nur77 receptor into BGC-823 cells resulted in resistance of cell growth against ATRA inhibition, and the cells were still arrested in the S phase. Furthermore, the action of Nur77 in TPA-induced apoptosis was mediated through a protein kinase C signaling pathway, while mitogen-activated protein kinase and phosphatidylinositol 3-kinase signaling pathways were responsible for the regulation of Nur77 mRNA expression. Taken together, the data revealed the dual functioning mechanisms of Nur77 in gastric cancer cells in response to TPA and ATRA.

RXRalpha acts as a carrier for TR3 nuclear export in a 9-cis retinoic acid-dependent manner in gastric cancer cells.

Retinoid X receptor (RXR) plays a crucial role in the cross talk between retinoid receptors and other hormone receptors including the orphan receptor TR3, forming different heterodimers that transduce diverse steroid/thyroid hormone signaling. Here we show that RXRalpha exhibits nucleocytoplasmic shuttling in MGC80-3 gastric cancer cells and that RXRalpha shuttling is energy-dependent through a nuclear pore complex (NPC)-mediated pathway for its import and an intact DNA binding domain-mediated pathway for its export. In the presence of its ligand 9-cis retinoic acid, RXRalpha was almost exclusively located in the cytoplasm. More importantly, we also show that RXRalpha acts as a carrier to assist translocation of TR3, which plays an important role in apoptosis. Both RXRalpha and TR3 colocalized in the nucleus; however, upon stimulation by 9-cis retinoic acid they cotranslocated to the cytoplasm and then localized in the mitochondria. TR3 export depends on RXRalpha, as in living cells GFP-TR3 alone did not result in export from the nucleus even in the presence of 9-cis retinoic acid, whereas GFP-TR3 cotransfected with RXRalpha was exported out of the nucleus in response to 9-cis retinoic acid. Moreover, specific reduction of RXRalpha levels caused by anti-sense RXRalpha abolished TR3 nuclear export. In contrast, specific knockdown of TR3 by antisense-TR3 or TR3-siRNA did not affect RXRalpha shuttling. These results indicate that RXRalpha is responsible for TR3 nucleocytoplasmic translocation, which is facilitated by the RXRalpha ligand 9-cis retinoic acid. In addition, mitochondrial TR3, but not RXRalpha, was critical for apoptosis, as TR3 mutants that were distributed in the mitochondria induced apoptosis in the presence or absence of 9-cis retinoic acid. These data reveal a novel aspect of RXRalpha function, in which it acts as a carrier for nucleocytoplasmic translocation of orphan receptors.