BACKGROUNDClinical combination of some traditional Chinese medical herbs, including berberine, with irradiation is demonstrated to improve efficacy of tumor radiotherapy, yet the mechanisms for such effect remain largely unknown. The present study investigated the effect of berberine on apoptosis induced by X-rays irradiation and the relation between this effect and gap junction intercellular communication (GJIC).

METHODSThe role of gap junctions in the modulation of X-rays irradiation-induced apoptosis was explored by manipulation of connexin (Cx) expression, and gap junction function, using oleamide, a GJIC inhibitor, and berberine.

RESULTSIn transfected HeLa cells, Cx32 expression increased apoptosis induced by X-rays irradiation, while inhibition of gap junction by oleamide reduced the irradiation responses, indicating the dependence of X-rays irradiation-induced apoptosis on GJIC. Berberine, at the concentrations without cytotoxicity, enhanced apoptosis induced by irradiation only in the presence of functional gap junctions.

CONCLUSIONSThese results suggest that berberine potentizes cell apoptosis induced by X-rays irradiation, probably through enhancement of gap junction activity.

Apoptosis ; drug effects ; Berberine ; pharmacology ; Gap Junctions ; drug effects ; metabolism ; radiation effects ; HeLa Cells ; Humans ; Oleic Acids ; pharmacology ; X-Rays

OBJECTIVETo explore the effect of silica dioxide(SiO2) on proliferation and downregulation of gap junctional intercellular communication (GJIC) in pulmonary alveolar epithelial cells (CCL-64 cells).

METHODSThe pulmonary alveolar macrophages(PAMs) were incubated in the serum-free RPMI 1640 containing the various concentration of SiO2 for 24 hours. The supernatants were prepared and added 5% (V/V) into 2% (V/V) NBS RPMI 1640 to stimulate the proliferation of CCL-64 cells for 24 hours. A set of "blank control", run in parallel, contained RPMI 1640 + 2% (V/V) NBS alone. The proliferation of CCL-64 cells was detected using MTT assay(to show as the absorbency, A570nm). GJIC function was measured using the fluorescence redistribution after photobleaching(FRAP) assay [to express as the transfer rate of the fluorescence, K (x 10(-3)/s)], with a laser scanning confocal microscope(LSCM, Leica TCS SP).

RESULTSThe silica-exposed PAM supernatants could induce both the proliferation(F = 9.679, P < 0.01) and downregulation of GJIC(F = 20.587, P < 0.01) of CCL-64 cells. In the range of 50-500 micrograms/ml SiO2 concentrations, the proliferation (A570nm values) and GJIC(the transfer rate, K) were fitted well in a dose-dependent manner(proliferation: r = 0.891, P < 0.05; GJIC: r = -0.943, P < 0.05).

CONCLUSIONBy way of stimulating the PAM, SiO2 could inhibit GJIC function in lung alveolar epithelial cells, and induce epithelial cell proliferation. In the pathogenesis of silicosis, the downregulation of GJIC of the pulmonary epithelial cells may play an important role in silica-mediated alveolar epithelial cell injury.

Cell Communication ; drug effects ; Cell Proliferation ; drug effects ; Epithelial Cells ; drug effects ; Gap Junctions ; drug effects ; Pulmonary Alveoli ; drug effects ; Silicon Dioxide ; toxicity ; Silicosis ; etiology

OBJECTIVETo investigate the effect of Src kinase inhibitor PP2 on intercellular communication of gap junction in breast cancer cells.

METHODSCultured breast cancer Hs578T cells were treated with various concentrations of pp2 (0,1,2,4,8,16,32 μmol/L) for 24h. Cell growth was determined by MTT assay; dye spread in Hs578T cells was measured by Parachute assay; and the expression of Src kinase in Hs578T cells was detected by Western blot.

RESULTSMTT assay showed that the survive rate of Hs578T cells treated with PP2 (1 ≊ 8 μmol/L) was 98% ± 3% ≊ 94 % ± 4%. Parachute assay showed that compared to control group the standard normalized dye spread rates of Hs578T cells treated with 1,2,4 and 8 μmol/L PP2 were 1.60 ± 0.08,2.00 ± 0.05,2.20 ± 0.05 and 2.70 ± 0.09,respectively (all P<0.01). Moreover,compared to control group at the same time points,the standard normalized dye spread of Hs578T cells treated with 8 μmol/L PP2 for 6,12 and 24 h were 1.4 ± 0.05,1.7 ± 0.06,and 2.2 ± 0.07,respectively (all P<0.01). Western blot showed that the expression ratios of Src kinase/β-actin of Hs578T cells treated with 1,2,4 and 8 μmol/L PP2 for 24 h were 0.93 ± 0.02,0.70 ± 0.09,0.66 ± 0.09 and 0.36 ± 0.10,which were significantly inhibited compared with control group (P<0.05 or 0.01). And the expression ratio of Src kinase/β-actin of Hs578T cells treated with 8 μmol/L PP2 for 6,12 and 24h was 0.82 ± 0.03,0.66 ± 0.08 and 0.59 ±0.09, which were all inhibited significantly compared to control group (P<0.01).

CONCLUSIONPP2 enhances the gap junction function in breast cancer Hs578T cells, which is probably related to the inhibition of Src kinase.

Breast Neoplasms ; pathology ; Cell Line, Tumor ; Female ; Gap Junctions ; drug effects ; Humans ; Pyrimidines ; administration & dosage ; pharmacology ; src-Family Kinases ; metabolism

OBJECTIVETo investigate the cytotoxicity of the nickel-refining dusts for Chinese hamster lung (CHL) cells and the effects of nickel-refining dusts on the gap junctional intercellular communication (GJIC) of CHL cells.

METHODSThe cytotoxicity of the nickel-refining dusts for the CHL cells was determined in two nickel-refining dusts samples with the CHL cells as the target cells by MTT method while the effects of nickel-refining dusts on the CJIC of the CHL cells were investigated using the scrape-loading and dye transfer (SLDT) technique.

RESULTSThere were no significant difference in the CHL proliferation between all dosage groups in the two samples and the control group at 6 and 12 hours (P > 0.05). The survival rate of cells in all dosage groups were all decreased at 36 hours (P < 0.05), presenting the dosage-reaction relationship and the time-reaction relationship. IC(50) was 21.36 and 23.07 micro/ml for the two samples respectively at 36 hours. Compared with the control group, the transport of Lucifer Yellow (LY) from the injury line to the adjacent cells was decreased when the CHL cells were treated with nickel-refining dusts of 25.00, 50.00 and 100.00 microg/ml (P < 0.01).

CONCLUSIONThe nickel-refining dusts have cytotoxicity for the CHL cells cultivated in vitro, can inhibit the growth of the cells and at a certain concentration can inhibit the GJIC function of CHL cells.

Animals ; Cell Communication ; drug effects ; Cell Survival ; drug effects ; Cells, Cultured ; Cricetinae ; Cricetulus ; Dose-Response Relationship, Drug ; Dust ; Gap Junctions ; drug effects ; Lung ; cytology ; Nickel ; toxicity

OBJECTIVETo investigate whether the cellular gap junctional communication(GJIC) down-regulation in alveolar epithelial cells (CCL-64 cells) induced by silica-stimulated pulmonary alveolar macrophages (PAM) supernatant is related with the phosphorylation states of connexin 43(Cx43) protein.

METHODWestern-blot analysis was used to identify phosphorylated Cx43 species.

RESULTSWestern-blot analyses of SiO2- and phorbol 12-myristate 13-acetate(TPA)-treated CCL-64 cells showed the same phosphorylation states of Cx43 as the control group. There were no Cx43 protein in nucleus of CCL-64 cells.

CONCLUSIONThe inhibition on GJIC induced by SiO2 and TPA in CCL-64 cells may not be brought about by altering the phosphorylation states of Cx43.

Animals ; Cell Communication ; drug effects ; Cell Line ; Connexin 43 ; metabolism ; Gap Junctions ; drug effects ; Lung ; drug effects ; metabolism ; Mink ; Phosphorylation ; Silicon Dioxide ; toxicity ; Tetradecanoylphorbol Acetate ; pharmacology

OBJECTIVETo investigate whether cellular gap-junctional communication(GJIC) down-regulation and the internalization of connexin 43(Cx43) in Chinese hamster lung fibroblasts (CHL) induced by silica-stimulated pulmonary alveolar macrophages (PAM) supermatant is related with the phosphorylation states of Cx43 protein.

METHODSWestern-blot analysis was used to identify phosphorylated Cx43 species.

RESULTSSamples from membrane protein, total protein and nucleoprotein in CHL cells with 50-500 micrograms/ml doses of silica-stimulated PAM supernatants showed NP, P1, P2, P3 four immunoreactive bands of Cx43 protein by contrast with the control group and 0 microgram/ml SiO2 group. And with the dose of SiO2 increased, the increment of the levels of P2 and P3 was observed. Moreover, the groups treated with SiO2 and protein kinase C inhibitor, Palmitoyl-DL-Camitine chloride (PMC), simutaneously showed reduced level of P2 and P3, as compared with the groups treated with SiO2 only.

CONCLUSIONThe inhibition of GJIC and the internalization of Cx43 by SiO2 in CHL cells may relate to the changes of phosphorylation states of Cx43, and its mechanism may be similar to that of phorbol 12-myristate 13-acetate (TPA), i.e. via PKC activation pathway.

Animals ; Cell Communication ; drug effects ; Cell Line ; Connexin 43 ; metabolism ; Cricetinae ; Gap Junctions ; drug effects ; Lung ; drug effects ; metabolism ; Phosphorylation ; Silicon Dioxide ; toxicity

OBJECTIVETo observe the effects of TGF-beta on the expression of connexin43 (Cx43) and Cx43-mediated gap junctional intercellular communication (GJIC) in rat Leydig cells, and investigate the association of its effects on Leydig cells with its ability of changing GJIC.

METHODSPrimarily cultured purified Leydig cells were divided into a blank control group, a positive control group (treated with the GJIC inhibitor Carbenoxolone), and four TGF-beta1 groups (treated with TGF-beta1 at the concentration of 1, 2, 5 and 10 ng/ml, respectively, for 20 hours). The localization and expression of Cx43 were detected by immunofluorescence and Western blot, and the changes in GJIC analyzed by FRAP assay.

RESULTSCx43 was expressed as scattered bright spots in the cytoplasm and membrane of Leydig cells. TGF-beta1 significantly elevated the expression of Cx43 in the cytoplasm, but caused no evident change in the membrane. Western blot showed an evident increase in the phosphorylation of Cx43 with the increased concentration of TGF-beta1 as compared with that of the blank control group (P < 0.05). After 20 hours of treatment with TGF-beta1 at 5 ng/ml, the fluorescence intensity of Leydig cells was markedly reduced (P < 0.01), with a mean fluorescence recovery rate of merely (43.58 +/- 1.87)%.

CONCLUSIONTGF-beta1 could significantly down-regulate GJIC between adjacent Leydig cells, and this inhibitory effect may be achieved by promoting the expression of Cx43 in the cytoplasm and elevating the phosphorylation of Cx43.

Animals ; Cell Communication ; drug effects ; Cells, Cultured ; Connexin 43 ; metabolism ; Gap Junctions ; drug effects ; metabolism ; Leydig Cells ; drug effects ; metabolism ; Male ; Phosphorylation ; Rats ; Transforming Growth Factor beta1 ; pharmacology

OBJECTIVETo investigate the effect of baicalein on the gap junction intercellular communication (GJIC) in the TM4 Sertoli cells of the mouse testis and its related mechanism.

METHODSWe measured the cytotoxicity of different concentrations of baicalein on the TM4 Sertoli cells in the mouse testis by MTT, detected the fluorescence transfer of the TM4 Sertoli cells by parachute assay, and determined the expression of the protein connexin 43 ( Cx43) in the baicalein-treated cells by Western blot and immunofluorescence assay.

RESULTSBaicalein produced no obvious cytotoxicity on the TM4 Sertoli cells at the concentration below 60 µmol/L but significantly increased their GJIC at 0-20 µmol/L (P < 0.01). Western blot and immunofluorescence assay showed that 0-20 µmol/L baicalein remarkably elevated the expression of Cx43 in the TM4 cells (P < 0.01) and on the membrane of the TM4 cells.

CONCLUSIONBaicalein at the concentration of 0-20 µmol/L can significantly enhance GJIC in mouse TM4 Sertoli cells by increasing the expression of the Cx43 protein.

Animals ; Cell Communication ; drug effects ; Connexin 43 ; metabolism ; Flavanones ; administration & dosage ; pharmacology ; Gap Junctions ; drug effects ; Male ; Mice ; Sertoli Cells ; drug effects ; metabolism ; ultrastructure

OBJECTIVE: To determine the effect of human corticotrophin-releasing hormone (CRH) on the expression of connexin-43 phosphate (P-Cx43) in human myometrial smooth muscle cells (SMCs) and the function of cell gap junction intercellular communication in SMCs. METHODS: Human non-conceive myometial SMCs were cultured with different concentrations of CRH (0, 5.85, 58.5, 585 and 5850 pmol/L). Western blot was used to test P-Cx43 and Cx43 non-phosphate (NP-Cx43) of protein expression. Cell scratch was used to test cell gap junction intercellular communication opening status in human myometrial SMCs. RESULTS: Compared with the control group, the expression of P-Cx43 was higher in the CRH groups (P<0.01), and was concentration-dependent. There was no significant difference in NPCx43 between the control group and the CRH groups (P>0.05). The transmission of cell layers in the CRH groups was higher than that in the control group (P<0.01), and as the concentration of CRH increased, the time was concentration-dependent (P<0.01). CONCLUSION CRH can enhance the expression of P-Cx43 and the function of gap junction intercellular communication in the primary cultured myometrial SMCs.
Cell Communication ; drug effects ; Cells, Cultured ; Connexin 43 ; metabolism ; Corticotropin-Releasing Hormone ; pharmacology ; Female ; Gap Junctions ; drug effects ; Humans ; Myocytes, Smooth Muscle ; metabolism ; Myometrium ; cytology ; Phosphorylation ; drug effects

OBJECTIVETo observe effects of phytoestrogens quercetin (QC), Genistein (GEN), coumestrol (COM), and enterolactone (ENL) on gap junctional intercellular communication (GJIC) in HaCaT cells.

METHODSHaCaT cells were exposed to QC, GEN, COM, and ENL at 0.1, 1.0, 10.0 and 100.0 micromol/L for 24 hours. The effects of phytoestrogens on GJIC were determined by fluorescence redistribution after photobleaching (FRAP) technique of using a laser scanning confocal microscope (LSCM).

RESULTSQC did not affect the GJIC at 0.1-10.0 micromol/L, whereas, GEN, COM, and ENL exhibited inhibition on the GJIC in some extent at 0.1-10.0 micromol/L without showing significant cytotoxicity. The ratio of fluorescence recovery were between 31.77% to 37.06%, which were significantly decreased compared the vehicle control (44.74%).

CONCLUSIONThe phytoestrogens GEN, COM, and ENL, but not QC, could inhibit the GJIC function in HaCaT cells at concentrations could be reached in human serum in some instance, indicating they could, under certain conditions, be cancer promoters. Therefore, it should be prudent to use these chemicals as pharmaceuticals or dietary supplements.

Cell Communication ; drug effects ; physiology ; Cell Line ; Coumestrol ; pharmacology ; Dose-Response Relationship, Drug ; Gap Junctions ; drug effects ; physiology ; Genistein ; pharmacology ; Humans ; Microscopy, Confocal ; Phytoestrogens ; pharmacology ; Quercetin ; pharmacology