This study examined the radiation-induced ERBB2 nuclear transport in the BT474 breast cancer cell line and the relationship between caveolin-1 and radiation-induced ERBB2 nuclear transport. The BT474 cells were treated with herceptin (200 nmol/L), PP2 (a caveolin-1 inhibitor, 100 nmol/L) and irradiation combined or alone. Confocal microscopy was used to observe the nuclear import of ERBB2 and caveolin-1 after irradiation. Western blotting was employed to detect the expression of ERBB2, caveolin-1 and DNA-PKcs after irradiation, and immunoprecipitation to identify the ERBB2 and caveolin-1 complex before perinuclear ERBB2 localization. Confocal microscopy showed the transport of ERBB2 and caveolin-1 from the cell membrane to the nucleus 15 min after irradiation and the proteins accumulated at the perinuclear region within 45 min. Western blotting revealed that the expression levels of ERBB2, caveolin-1 and DNA-PKcs were increased after irradiation and reached a peak 45 min later. Both herceptin and PP2 treatments were found to decrease ERBB2 expression. An immune complex composed of ERBB2 and caveolin-1 was found in the herceptin group after irradiation. It was concluded that after irradiation, ERBB2 may be transported from the cell membrane to the nucleus and activate DNA-PKcs to trigger DNA double-strand break (DSB) repair; caveolin-1 may participate in this process. Treatments involving the downregulation of caveolin-1 may increase the radiosensitization of breast cancer cells.
Active Transport, Cell Nucleus ; physiology ; Breast Neoplasms ; metabolism ; physiopathology ; Caveolin 1 ; metabolism ; Cell Line, Tumor ; Female ; Humans ; Protein Transport ; physiology ; Radiation ; Receptor, ErbB-2 ; metabolism

It has been proposed that the pro-inflammatory catalytic activity of cyclooxygenase-2 (COX-2) plays a key role in the aging process. However, it remains unclear whether the COX-2 activity is a causal factor for aging and whether COX-2 inhibitors could prevent aging. We here examined the effect of COX-2 inhibitors on aging in the intrinsic skin aging model of hairless mice. We observed that among two selective COX-2 inhibitors and one non-selective COX inhibitor studied, only NS-398 inhibited skin aging, while celecoxib and aspirin accelerated skin aging. In addition, NS-398 reduced the expression of p53 and p16, whereas celecoxib and aspirin enhanced their expression. We also found that the aging-modulating effect of the inhibitors is closely associated with the expression of type I procollagen and caveolin-1. These results suggest that pro-inflammatory catalytic activity of COX-2 is not a causal factor for aging at least in skin and that COX-2 inhibitors might modulate skin aging by regulating the expression of type I procollagen and caveolin-1.
Animals ; Aspirin/administration & dosage ; Catalysis ; Caveolin 1/genetics/metabolism ; Collagen Type I/genetics/metabolism ; *Cyclooxygenase 2/metabolism/physiology ; Cyclooxygenase 2 Inhibitors/*administration & dosage ; Gene Expression Regulation ; Mice ; Nitrobenzenes/*administration & dosage ; Pyrazoles/administration & dosage ; Skin Aging/*drug effects/physiology ; Sulfonamides/*administration & dosage ; Tumor Suppressor Protein p53/genetics/metabolism

Recent evidence supports a neuroprotective role of Src homology 2-containing protein tyrosine phosphatase 2 (SHP-2) against ischemic brain injury. However, the molecular mechanisms of SHP-2 activation and those governing how SHP-2 exerts its function under oxidative stress conditions are not well understood. Recently we have reported that reactive oxygen species (ROS)-mediated oxidative stress promotes the phosphorylation of endogenous SHP-2 through lipid rafts, and that this phosphorylation strongly occurs in astrocytes, but not in microglia. To investigate the molecules involved in events leading to phosphorylation of SHP-2, raft proteins were analyzed using astrocytes and microglia. Interestingly, caveolin-1 and -2 were detected only in astrocytes but not in microglia, whereas flotillin-1 was expressed in both cell types. To examine whether the H2O2-dependent phosphorylation of SHP-2 is mediated by caveolin-1, we used specific small interfering RNA (siRNA) to downregulate caveolin-1 expression. In the presence of caveolin-1 siRNA, the level of SHP-2 phosphorylation induced by H2O2 was significantly decreased, compared with in the presence of control siRNA. Overexpression of caveolin-1 effectively increased H2O2-induced SHP-2 phosphorylation in microglia. Lastly, H2O2 induced extracellular signal-regulated kinase (ERK) activation in astrocytes through caveolin-1. Our results suggest that caveolin-1 is involved in astrocyte-specific intracellular responses linked to the SHP-2-mediated signaling cascade following ROS-induced oxidative stress.
Animals ; Astrocytes/*metabolism ; Caveolin 1/*genetics/metabolism ; Caveolin 2/genetics ; Cell Line ; Cells, Cultured ; Extracellular Signal-Regulated MAP Kinases/metabolism ; Gene Expression ; Humans ; Microglia/metabolism ; Phosphoric Monoester Hydrolases/*metabolism ; Phosphorylation ; Protein Tyrosine Phosphatase, Non-Receptor Type 11/*metabolism ; Rats ; Reactive Oxygen Species/*metabolism

OBJECTIVETo observe the therapeutic effect and mechanism of penehyclidine hydrochloride on paraquat-induced acute lung injury.

METHODS80 healthy adult male Wistar rats were randomly assigned into control groups (10 rats), 100 mg/kg PQ group (10 rats), 100 mg/kg PQ plus 33 µg/kg penehyclidine hydrochloride treatment group (30 rats), 100 mg/kg PQ plus 66 µg/kg penehyclidine hydrochloride treatment group (30 rats). The two treatment groups were executed respectively at 36 h, 72 h and 7 d. Lung tissues were used to assess histopathological change by HE staining. The level of MMP-2, caveolin-1 and HYP were detected in the lung homogenate. The serum and BALF contents of ET were measured.

RESULTSPathology inspection confirmed that the model of acute rat pulmonary injury were duplicated successfully. The level of MMP-2, HYP in lung tissues and the serum and BALF ET contents in PQ group were (1.77 ± 0.40) µg/g, (2.91 ± 0.79) µg/g, (505.23 ± 124.69) µg/ml, (640.38 ± 136.60) µg/ml. The level of those was higher than that in control group [(0.95 ± 0.66) µg/g, (1.48 ± 0.69) µg/g, (95.48 ± 46.01) µg/ml, (200.40 ± 88.39) µg/ml, P < 0.05]; The above-mentioned index in two treatment groups was lower than that in PQ group (P < 0.05). The caveolin-1 content [(1.77 ± 0.82) µg/g] in PQ group was lower than that in control group [(5.39 ± 1.68) µg/g, P < 0.05]. The level of caveolin-1 in two treatment groups was higher than that in PQ group (P < 0.05).

CONCLUSIONPenehyclidine hydrochloride can decrease the level of MMP-2, HYP in lung tissues and the ET in serum and BALF, increase that of caveolin-1 and lessen the damage induced by paraquat.

Acute Lung Injury ; chemically induced ; drug therapy ; Animals ; Caveolin 1 ; metabolism ; Endothelins ; metabolism ; Hydroxyproline ; metabolism ; Male ; Matrix Metalloproteinase 2 ; metabolism ; Paraquat ; toxicity ; Quinuclidines ; therapeutic use ; Rats ; Rats, Wistar

Caveolin-2, a protein about 20 kD, is a major component of the inner surface of caveolae, small invaginations of the plasma membrane. Similar with caveolin-1 and caveolin-3, it serves as a protein marker of caveolae. Caveolin-1 and -2 are located next to each other at 7q31.1 on human chromosome, the proteins encoded are co-localized and form a stable hetero-oligomeric complex, distributing similarly in tissue and cultured cells. Caveolin-3 is located on different chromosomes but confirmed to interact with caveolin-2. Caveolin-2 is similar to caveolin-1 in many respects but differs from the latter in functional domains, especially in G-protein binding domain and caveolin scaffolding domain. The mRNAs of both caveolin-1 and caveolin-2 are most abundantly expressed in white adipose tissue and are induced during differentiation of 3T3-L1 cells to adipocytes. Caveolin-2-deficient mice demonstrate clear pulmonary defects, with little or no change in caveolin-1 expression and caveolae formation, suggesting that caveolin-2 plays a selective role in lung functions. Caveolin-2 is also involved in lipid metabolism and human cancers.
Biomarkers ; metabolism ; Caveolae ; metabolism ; Caveolin 2 ; genetics ; metabolism ; Chromosomes, Human, Pair 7 ; Humans

BACKGROUND/AIMS: Hepatocellular carcinoma (HCC) is becoming one of the common malignant tumors worldwide, and it is characterized by its high vascularity. Caveolin is the major structural protein in caveolae, which are small omega-shaped invaginations within the plasma membrane. Caveolin has been implicated in mitogenic signaling, oncogenesis and angiogenesis. The expression of caveolin-1 and -2 in HCC and its potential relationship with angiogenesis has not been examined. METHODS: Paraffin sections of 35 HCC specimens were immunostained with caveolin-1, caveolin-2, alpha-smooth muscle actin, and CD34 antibodies. In addition, the expression of caveolin-1 and -2 mRNA in HCC was examined. The relationship between the radiological findings and the number of unpaired arteries and microvessel density (MVD) was also investigated. RESULTS: Caveolin-1 and -2 were expressed in the sinusoidal endothelial cells in 20 out of 35, and 18 out of 35 HCC specimens, respectively. Caveolin-1 and -2 were also expressed in the smooth muscle cells of the unpaired arteries in 26 out of 35, and 18 out of 35 HCC specimens, respectively. Increased expression of caveolin-1 and -2 mRNA was detected in 26.7% and 33.3% of the tumor specimens, respectively, compared with the corresponding non-tumorous adjacent liver tissues. There was a significant correlation between expression of caveolin-1, -2 in the smooth muscle cells of unpaired arteries and the number of unpaired arteries. The number of unpaired arteries in HCCs was found to be associated with the degree of contrast enhancement in the arterial phase imaging. However, it did not correlate with the degree of MVD. CONCLUSIONS: These findings suggest that the expression of caveolin-1, -2 is associated with the formation of unpaired arteries in HCC. In addition, there is a correlation between the degree of contrast enhancement of the HCC in the arterial phase image and the number of unpaired arteries.
Adult ; Aged ; Carcinoma, Hepatocellular/*blood supply/metabolism/radiography ; Caveolin 1/genetics/*metabolism ; Caveolin 2/genetics/*metabolism ; Female ; Hepatic Artery/pathology/radiography ; Humans ; Liver Neoplasms/*blood supply/metabolism/radiography ; Male ; Middle Aged ; Neoplasm Staging ; Neovascularization, Pathologic/etiology/*metabolism/radiography ; Retrospective Studies

BACKGROUND: Nitric oxide (NO) in articular chondrocytes regulates dedifferentiation and inflammatory responses by modulating MAP kinases. In this study, we investigated whether the Src kinase in chondrocytes regulates NO-induced dedifferentiation and cyclooxygenase-2 (COX-2) expression. METHODS: Primary chondrocytes were treated with various concentrations of SNP for 24 h. The COX-2 and type II collagen expression levels were determined by immunoblot analysis, and prostaglandin E(2) (PGE(2)) was determined by using a PGE(2) assay kit. Expression and distribution of p-Caveolin and COX-2 in rabbit articular chondrocytes and cartilage explants were determined by immunohistochemical staining and immunocytochemical staining, respectively. RESULTS: SNP treatment stimulated Src kinase activation in a dose-dependent manner in articular chondrocytes. The Src kinase inhibitors PP2 [4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo(3,4-d)pyrimidine], a significantly blocked SNP-induced p38 kinase and caveolin-1 activation in a dose-dependent manner. Therefore, to determine whether Src kinase activation is associated with dedifferentiation and/or COX-2 expression and PGE(2) production. As expected, PP2 potentiated SNP-stimulated dedifferentiation, but completely blocked both COX-2 expression and PGE2 production. And also, levels of p-Caveolin and COX-2 protein expression were increased in SNP-treated primary chondrocytes and osteoarthritic and rheumatoid arthritic cartilage, suggesting that p-Caveolin may play a role in the inflammatory responses of arthritic cartilage. CONCLUSION: Our previously studies indicated that NO caused dedifferentiation and COX-2 expression is regulated by p38 kinase through caveolin-1 (1). Therefore, our results collectively suggest that Src kinase regulates NO-induced dedifferentiation and COX-2 expression in chondrocytes via p38 kinase in association with caveolin-1.
Cartilage ; Caveolin 1 ; Chondrocytes* ; Collagen Type II ; Cyclooxygenase 2* ; Dinoprostone ; Nitric Oxide ; Phosphotransferases*

The purpose of this study was to demonstrate the cellular localization of cyclooxygenase-2 (COX-2) and caveolin-3 (Cav-3) in primarily cultured rat chondrocytes. In normal rat chondrocytes, we observed relatively high levels of Cav-3 and a very low level of COX-2 mRNA and protein. Upon treating the chondrocytes with 5 microM of CdCl2 (Cd) for 6 hr, the expressions of COX-2 mRNA and protein were increased with the decreased Cav-3 mRNA and protein expressions. The detergent insoluble caveolae-rich membranous fractions that were isolated from the rat chondrocytes and treated with Cd contained the both proteins of both COX-2 and Cav-3 in a same fraction. The immuno-precipitation experiments showed complex formation between the COX-2 and Cav-3 in the rat chondrocytes. Purified COX-2 with glutathione S-transferase-fused COX-2 also showed complex formation with Cav-3. Confocal and electron microscopy also demonstrated the co-localization of COX-2 and Cav-3 in the plasma membrane. The results from our current study show that COX-2 and Cav-3 are co-localized in the caveolae of the plasma membrane, and they form a protein-protein complex. The co-localization of COX-2 with Cav-3 in the caveolae suggests that the caveolins might play an important role for regulating the function of COX-2.
Animals ; Animals, Newborn ; Blotting, Western ; Cadmium Chloride/pharmacology ; Caveolae/drug effects/metabolism/ultrastructure ; Caveolin 3/*genetics/metabolism ; Cell Membrane/drug effects/metabolism ; Cells, Cultured ; Chondrocytes/cytology/drug effects/*metabolism ; Cyclooxygenase 2/*genetics/metabolism ; Gene Expression ; Immunoprecipitation ; Microscopy, Confocal ; Microscopy, Electron ; RNA, Messenger/genetics/metabolism ; Rats ; Reverse Transcriptase Polymerase Chain Reaction

The expression of caveolin-1 and -2 in the retina was examined; Western blot analysis showed that both were present. Immunohistochemistry indicated that caveolin-1 was expressed in the majority of retinal layers, including the ganglion cell layer, inner plexiform layer, outer plexiform layer, and in the vascular endothelial cells of the retina. Caveolin-2 was primarily immunostained in the vessels, but in a few other elements as well. This is the first demonstration of caveolin differential expression in the retina of rats, and suggests that caveolin plays an important role in signal transduction in glial cells and neuronal cells.
Animals ; Caveolin 1/*analysis/immunology ; Caveolin 2/*analysis/immunology ; Gene Expression Regulation ; Immunohistochemistry ; Male ; Rats ; Rats, Sprague-Dawley ; Retina/*chemistry

BACKGROUND: Caveolin-1 is a principal component of caveolae membranes in vivo. Although expression of caveolae structure and expression of caveolin family, caveolin-1, -2 and -3, was known in chondrocytes, the functional role of caveolae and caveolins in chondrocytes remains unknown. In this study, we investigated the role of caveolin-1 in articular chondrocytes. METHODS: Rabbit articular chondrocytes were prepared from cartilage slices of 2-week-old New Zealand white rabbits by enzymatic digestion. Caveolin-1 cDNA was transfected to articular chondrocytes using LipofectaminePLUS. The cyclooxygenase-2 (COX-2) expression levels were determined by immunoblot analysis, immunostaining, immunohistochemistry, and prostaglandin E2 (PGE2) assay was used to measure the COX-2 activity. RESULTS: Ectopic expression of caveolin-1 induced COX-2 expression and activity, as indicated by immunoblot analysis and PGE2 assay. And also, overexpression of caveolin-1 stimulated activation of p38 kinase and ERK-1/ -2. Inhibition of p38 kinase and ERK-1/-2 with SB203580 and PD98059, respectively, led to a dose-dependent decrease COX-2 expression and PGE2 production in caveolin-1-transfected cells. CONCLUSION: Taken together, our data suggest that ectopic expression of caveolin-1 contributes to the expression and activity of COX-2 in articular chondrocytes through MAP kinase pathway.
Cartilage ; Caveolae ; Caveolin 1* ; Caveolins ; Chondrocytes* ; Cyclooxygenase 2 ; Digestion ; Dinoprostone ; DNA, Complementary ; Humans ; Immunohistochemistry ; Membranes ; Phosphotransferases* ; Rabbits