OBJECTIVETo investigate the significance of Rac subfamily members in the gastrointestinal carcinogenesis and progression.

METHODSThe mRNA expression of Rac1, Rac2 and Rac3 in 12 kinds of gastrointestinal cancer cell lines was examined by semi-quantitative RT-PCR. The activities of Rac1 protein in 5 kinds of gastric cancer cell lines were tested by pull-down assay.

RESULTSCompared with the normal gastric mucosa and intestinal epithelial cell line, the mRNA expression of Rac1 and Rac3 was up-regulated in most of gastrointestinal cancer cell lines. The activities of Rac1 protein increased markedly in gastric cancer cell lines.

CONCLUSIONThe increased mRNA expression of Rac1 and Rac3 in gastrointestinal cancer cell lines and the abnormal activation of Rac1 protein in gastric cancer cell lines might be correlated with the carcinogenesis of gastrointestinal cancer.

Cell Line, Tumor ; Gastrointestinal Neoplasms ; metabolism ; Humans ; RNA, Messenger ; analysis ; Reverse Transcriptase Polymerase Chain Reaction ; rac GTP-Binding Proteins ; genetics ; rac1 GTP-Binding Protein ; analysis ; genetics

This study sought to elucidate whether Rac1 mediates the migration of endothelial cell induced by IL-8. The Transwell chamber motility assay was conducted to disclose the effect of different matrigel dilution and different time of IL-8 treatment on the migration of endothelial cells. The mRNA of Rac1 was detected by RT-PCR. The results demonstrated that when the concentration of Matrigel was 1:2, there is significant difference on the amounts of migration cells than that of the concentration of 1:3 or 1:8; When the dilution of Matrigel was 1:4, 1:5 or 1:6, there is no significant difference on the amounts of migration cells than that of other dilution groups. So we choose the Matrigel concentration as 1:4. With the increase of IL-8 stimulation time, the cells which migrated from upper reservoirs to lower reservoirs progressively increased. After six hours stimulation by IL-8, the expression of Rac1 mRNA in migrated cells was increased, compared with that of other groups. The results suggest that Rac1 may mediate the migration of endothelial cells induced by IL-8. It can also be the foundation for further investigation on the role of Rac1 in the migration of endothelial cells induced by IL-8.
Cell Movement ; drug effects ; Cells, Cultured ; Endothelial Cells ; cytology ; metabolism ; Humans ; Interleukin-8 ; pharmacology ; RNA, Messenger ; biosynthesis ; genetics ; Umbilical Veins ; cytology ; metabolism ; rac1 GTP-Binding Protein ; biosynthesis ; genetics

OBJECTIVETo investigate modulatory role of Rac1 protein in epidermal stem cell (ESC) migration during wound healing, in order to provide a reference for enriching basic theory of wound healing and guiding clinical application.

METHODSConstitutively active mutant of Rac1 protein (Rac1Q61L) or dominant negative isoform of Rac1 protein (Rac1T17N) was transfected into ESC using a retroviral vector FUGW, and retroviral vector FUGW transfected into ESC in singles was used as blank control. The cells were divided into 3 parts according to the random number table and treated as follows. First, equal numbers of cells were inoculated into 24-well plates coated with collagen I (20 µg/mL), collagen IV (20 µg/mL) or fibronectin (10 µg/mL). Cells adhered to above matrices were quantitated using CytoTox 96 colorimetric kit. Second, 1000 cells adhered to collagen IV, after being stained with tetramethyl rhodamine isothiocyanate-phalloidin, were collected for observation of cell morphology and comparison of spreading area under confocal laser scanning microscope. Third, ESC with density of 2 × 10(5) cells per well were placed in upper compartment of Transwell chamber, DK-SFM culture medium alone or that containing stromal cell derived factor 1 (SDF-1) was added into lower compartment of Transwell chamber. Migration of ESC was observed using inverted phase contrast microscope, and the result was denoted as migration rate. Lastly, ESC with density of 7.5 × 10(5) cells per well was inoculated into 6-well plates for 12 hours, and treated with 4 µg/mL mitomycin C for 2 hours. The remaining scratch width of monolayer was respectively measured 6 hours or 12 hours after scratching to calculate the percentage of remaining scratch width. Data were processed with t test.

RESULTSCompared with that of blank control, the number of Rac1Q61L-transfected cells adhered to collagen I was significantly increased (t = 5.302,P < 0.05), while the number of Rac1T17N-transfected cells adhered to collagen I, IV, and fibronectin were all obviously decreased (with t value respectively 13.741, 15.676, 8.256, P values all below 0.05). Confocal laser scanning microscope showed that spreading area of Rac1Q61L-transfected ESC (with laminate pseudopodia on edge) and Rac1T17N-transfected ESC was respectively larger and smaller as compared with that of blank control. With SDF-1 effect, the migration rate of Rac1T17N-transfected ESC was decreased by 78.0% and Rac1Q61L-transfected ESC was increased by 43.4% as compared with that of blank control. Without SDF-1 effect, the migration rate of Rac1T17N-transfected ESC was decreased by 55.2%, while the migration rate of Rac1Q61L-transfected ESC was close to that of blank control. Six or 12 hours after scratching, the percentage of remaining scratch width in Rac1Q61L-transfected ESC was lower as compared with that in blank control [(39 ± 9)% vs. (43 ± 5)%, (6 ± 5)% vs. (18 ± 7)%, with t value respectively 1.027, 4.389, with P value respectively above and below 0.05], while that in Rac1T17N-transfected ESC [(81 ± 9)%, (71 ± 11)%, respectively] was obviously higher as compared with that in blank control (with t value respectively 11.386, 11.726, P values all below 0.05).

CONCLUSIONSRac1 protein may control the migration of ESC by regulating its adhesion, spreading, and chemotaxis, and it plays an active role in wound healing accelerated by ESC.

Cell Movement ; Cell Proliferation ; Epidermis ; cytology ; Epithelial Cells ; Humans ; Mutation ; Stem Cells ; cytology ; Transfection ; Wound Healing ; rac1 GTP-Binding Protein ; genetics ; metabolism

OBJECTIVETo study the role of activation of Rac1 in colorectal cancer cell migration and invasion.

METHODSRac1 L61 plasmid and control plasmid were transfected into colorectal cancer cell line SW480 cells. Pull down assay by Western blotting was carried out to measure the amount of activited Rac1, and transwell permeable supports were used to assess the migration and invasion of SW480 cells with different activitivity of Rac1.

RESULTSThe transfection ratio of SW480 cells was more than 80%. Pull down assay showed that the activited Rac1 was significantly higher in the SW480 cells transfected with Rac1 L61 plasmid than that in the control, and the amount of migrating and invasing SW480 cells transfected with Rac1 L61 plasmid in the Transwell permeable supports were significantly more than those in controls (migrating cell numbers: 43 +/- 9 vs. 22 +/- 5, P < 0.01; invasing cell numbers: 73 +/- 13 vs. 38 +/- 1, P < 0.01).

CONCLUSIONThe activation of Rac1 plays an important role in the migration and invasion of colorectal cancer cells.

Cell Line, Tumor ; Cell Movement ; Colonic Neoplasms ; metabolism ; pathology ; Enzyme Activation ; Genetic Vectors ; Green Fluorescent Proteins ; genetics ; metabolism ; Humans ; Neoplasm Invasiveness ; Plasmids ; Recombinant Fusion Proteins ; genetics ; metabolism ; Transfection ; rac1 GTP-Binding Protein ; genetics ; metabolism

To study the effects of tyrosine-kinase inhibitor STI571 on the adhesion of RPMI8226 cells to fibronectin (FN), cell adhesion mediated adriamycin-resistance and the Rac1 mRNA expression, the adhesion of RPMI8226 cells to fibronectin and drug resistance mediated by cell adhesion were determined by means of crystal violet staining and MTT assays respectively, Rac1 mRNA levels in RPMI8226 cells were examined by semi-quantitative RT-PCR. The results showed that STI571 could inhibit the adhesion of RPMI8226 cells to fibronectin. When RPMI8226 cells had been adhered to FN or BSA-coated wells for 1, 6 and 12 hours, the adhesion rates were (43.71 +/- 2.18)%, (55.63 +/- 1.56)%, and (63.42 +/- 2.46)% respectively. After treatment with STI571 20 micromol/L, the adhesion rates decreased to (15.12 +/- 1.04)%, (17.58 +/- 1.32)% and (17.24 +/- 1.59)% respectively (P < 0.05). The experiment revealed that growth of RPMI8226 cells adhered to FN-coated plates had a significant advantage over growth on BSA-coated plates when exposed to adriamycin (Adr) for 1 hour followed by a 24-hour culture period, and the mean IC(50) value for FN-adhered cells was (1.46 +/- 0.04) micromol/L while mean IC(50) value for BSA control was (0.78 +/- 0.03) micromol/L (P < 0.05). Following treatment with 20 micromol/L STI571, the mean IC50 values for FN and BSA adhered cells were (0.81 +/- 0.05) micromol/L, (0.74 +/- 0.02) micromol/L respectively, there was no significant difference between them (P > 0.05). RT-PCR demonstrated that the relative Rac1 mRNA level (Rac1/GAPDH) in RPMI8226 cells was downregulated following being treated with 20 micromol/L STI571. It is concluded that STI571 can inhibit the adhesion of RPMI8226 cells to fibronectin, reverse cell adhesion mediated adriamycin-resistance, and downregulate Rac1 mRNA level.
Benzamides ; Cell Adhesion ; Doxorubicin ; pharmacology ; Drug Resistance, Neoplasm ; Fibronectins ; metabolism ; Humans ; Imatinib Mesylate ; Multiple Myeloma ; metabolism ; pathology ; Piperazines ; Protein-Tyrosine Kinases ; antagonists & inhibitors ; Pyrimidines ; pharmacology ; RNA, Messenger ; biosynthesis ; genetics ; Tumor Cells, Cultured ; rac1 GTP-Binding Protein ; biosynthesis ; genetics

To investigate the role and mechanism of Rac1 protein in the process of the human umbilical vein endothelial cell (HUVEC) senescence, we used hypoxia as a model for modulating HUVECs entering replicative senescence in vitro. Premature senescence of HUVECs was evidenced by detecting the SA-beta-Gal activity and PAI-1 expression. Meanwhile, cell cycle distribution and cell proliferation rate were investigated by flow cytometry assay and BrdU staining. The results indicated that the HUVECs became enlarged and flattened, both SA-beta-Gal activity and PAI-1 expression increased obviously, while cell proliferation was inhibited and G(1) phase cell cycle arresting occurred when HUVECs were treated with continued hypoxia for 96 h. Accompanied with these changes, the expression of activated Rac1 increased obviously in cells after hypoxia. All these observations suggested that endothelial senescence could be induced by continued hypoxia and it might correlate with the activity of Rac1. To further define the relationship between Rac1 and HUVEC senescence, HUVECs were transiently infected with the constitutively active form of Rac1 (V12Rac1) or dominant negative form of Rac1 (N17Rac1) using retrovirus vector pLNCX-V12Rac1 or pLNCX-N17Rac1. We observed the changes of these three kinds of HUVECs (HUVECs, N17Rac1-HUVECs, V12Rac1-HUVECs) after hypoxia for 48 h and 96 h, the expression and localization of serum response factor (SRF), which is one of the downstream signal molecules of Rac1, were also investigated. The results obtained indicated that after continued hypoxia for 48 h, HUVECs infected by V12Rac1 showed obvious senescence accompanied with SA-beta-Gal activation, PAI-1 expression increase, G(1) phase arrest and cell proliferation inhibition which were similar to HUVECs after continued 96-hour hypoxia treatment, while the senescence of HUVECs infected by N17Rac1 was significantly inhibited even if the cells were exposed to hypoxia for more than 96 h. All the results identified that the activation of Rac1 might accelerate HUVEC senescence induced by hypoxia and that inactivation of Rac1 could partly block the cell senescence. To further investigate the mechanism of HUVEC senescence induced by Rac1, we detected the expression of total SRF (tSRF) and nuclear SRF (nSRF) in these three kinds of HUVECs by immunofluorescent analysis and Western blot assay after hypoxia. The results showed that the expression of nSRF decreased obviously and the nuclear translocation of SRF was inhibited in HUVECs infected by V12Rac1 compared with those in the normal HUVECs. In contrast, the expression of nSRF increased obviously in the HUVECs infected by N17Rac1. These results suggest that activation of Rac1 accelerates endothelial cell senescence and inhibition of Rac1 activity prevents HUVECs from entering senescence induced by hypoxia, while the nuclear translocation of SRF regulated by Rac1 might play an important role in the process of senescence.
Cell Hypoxia ; Cells, Cultured ; Cellular Senescence ; physiology ; Human Umbilical Vein Endothelial Cells ; cytology ; Humans ; Plasminogen Activator Inhibitor 1 ; genetics ; metabolism ; Serum Response Factor ; genetics ; metabolism ; beta-Galactosidase ; metabolism ; rac1 GTP-Binding Protein ; metabolism

OBJECTIVETo analyze the drug-sensitivity-related genes to anti-tumor drugs navalbine (NVB) and docetaxel (Doc) in four SCLC and six NSCLC cell lines.

METHODSThe sensitivity of 4 SCLC lines and 6 NSCLC lines to NVB and to Doc was determined with MTT test. The expression of 1291 anti-tumor drug sensitivity-related genes in the 10 cell lines was assayed by cDNA macroarray technique, and cluster analysis was performed to find the relationship between the results obtained by the above mentioned two measurements.

RESULTS(1) The anti-tumor effect of NVB on the 10 cell lines was apparently better than that of Doc. (2) The drug sensitivity-related genes in these 10 cell lines showed a more close positive correlation with Doc than that with NVB, whereas more genes showed negative correlation with NVB than that with Doc. But in 6 NSCLC cell lines, more genes showed the same positive or negative correlation with the two drugs. (3) 51 genes in the 10 cell lines showed correlation with Doc or NVB. 13 of them had negative correlation with Doc, 11 of them showed positive correlation. 24 of them showed negative correlation with NVB, 3 of them showed positive correlation. 67 genes in 6 NSCLC cell lines showed a correlation with sensitivity to Doc or NVB, among them 34 had negative correlation with Doc, 4 had positive correlation. 25 genes had negative correlation with NVB, 4 had positive correlation. (4) Rab 1, Rab 3, Rho B, Rho C, Rac 1, Rac 2, Gho GDI beta, CD44, integrin alpha5, integrin alpha6, integrin beta5, vinculin showed to be cytoskeleton-related genes differently expressing in SCLC or NSCLC cell lines.

CONCLUSIONThere is obvious difference in the drug sensitivity-related genes to NVB or Doc between SCLC and NSCLC cell lines.

Antineoplastic Agents ; pharmacology ; Cell Line, Tumor ; Cluster Analysis ; Cytoskeletal Proteins ; metabolism ; Cytoskeleton ; genetics ; Gene Expression Profiling ; Gene Expression Regulation, Neoplastic ; Humans ; Integrin alpha5 ; metabolism ; Lung Neoplasms ; genetics ; metabolism ; pathology ; Oligonucleotide Array Sequence Analysis ; Taxoids ; pharmacology ; Vinblastine ; analogs & derivatives ; pharmacology ; rab1 GTP-Binding Proteins ; metabolism ; rac1 GTP-Binding Protein ; metabolism

OBJECTIVETo construct lentiviruses carrying dominant negative mutant of Rac1-GTPase (Rac1N17) or the constitutive active mutant of Rac1-GTPase (Rac1L61) and expressing enhanced green fluorescent protein (EGFP) bicistronically.

METHODSThe lentiviral expression plasmid Plenti6/v5-Rac1N17 and Plenti6/v5-Rac1L61 were constructed and identified by restriction enzyme digestion and DNA sequence analysis. The two plasmids were packaged using the ViraPowerTM lentiviral expression system to produce replication-incompetent lentiviruses Rac1L61 and Rac1N17, which were used to infect the prefrontal cortex neurons (PFCs) from neonatal SD rats. The transfection efficiency and biological activity of different Rac1 mutants were evaluated and the morphology of the transfected PFCs was observed.

RESULTSThe results of DNA sequencing and restriction enzyme analysis demonstrated correct plasmid construction. The packaged lentiviral titer was 1x10(6) TU/ml. Analysis of Rac1 biological activity showed that Rac1N17 lentivirus particles infection significantly inhibited epidermal growth factor-stimulated Rac1 activity in the PFCs, while Rac1L61 lentivirus particles enhanced the Rac1 activity. The transfection efficiency of these Rac1 mutant lentivirus particles exceeded 80% in the PFCs. Morphologically, the PFCs exhibited distinct dendritic branches after infection by these lentiviruses.

CONCLUSIONThe lentiviruses carrying Rac1 dominant negative mutant and constitutive active mutant have been successfully constructed. The lentiviral particles can efficiently infect neonatal rat PFCs and lend important support for the study of Rac1-GTPase.

3T3 Cells ; Animals ; Animals, Newborn ; Cerebral Cortex ; cytology ; GTP Phosphohydrolases ; biosynthesis ; genetics ; Genetic Vectors ; genetics ; Green Fluorescent Proteins ; genetics ; metabolism ; Lentivirus ; genetics ; metabolism ; Mice ; Neurons ; metabolism ; physiology ; Rats ; Rats, Sprague-Dawley ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; Signal Transduction ; Transfection ; rac1 GTP-Binding Protein ; biosynthesis ; genetics

Diabetic nephropathy (DN) is a progressive kidney disease that is caused by injury to kidney glomeruli. Podocytes are glomerular epithelial cells and play critical roles in the glomerular filtration barrier. Recent studies have shown the importance of regulating the podocyte actin cytoskeleton in early DN. The phosphoinositide 3-kinase (PI3K) inhibitor, wortmannin, simultaneously regulates Rac1 and Cdc42, which destabilize the podocyte actin cytoskeleton during early DN. In this study, in order to evaluate the reno-protective effects of wortmannin in early DN by regulating Rac1 and Cdc42, streptozotocin (STZ)-induced proteinuric renal disease (SPRD) rats were treated with wortmannin. The albuminuria value of the SPRD group was 3.55 +/- 0.56 mg/day, whereas wortmannin group was 1.77 +/- 0.48 mg/day. Also, the albumin to creatinine ratio (ACR) value of the SPRD group was 53.08 +/- 10.82 mg/g, whereas wortmannin group was 20.27 +/- 6.41 mg/g. Changes in the expression level of nephrin, podocin and Rac1/Cdc42, which is related to actin cytoskeleton in podocytes, by wortmannin administration were confirmed by Western blotting. The expression levels of nephrin (79.66 +/- 0.02), podocin (87.81 +/- 0.03) and Rac1/Cdc42 (86.12 +/- 0.02) in the wortmannin group were higher than the expression levels of nephrin (55.32 +/- 0.03), podocin (53.40 +/- 0.06) and Rac1/Cdc42 (54.05 +/- 0.04) in the SPRD group. In addition, expression and localization of nephrin, podocin and desmin were confirmed by immunofluorescence. In summary, we found for the first time that wortmannin has a reno-protective effect on SPRD rats during the early DN. The beneficial effects of wortmannin in SPRD rats indicate that this compound could be used to delay the progression of the disease during the early DN stage.
Albumins/metabolism ; Androstadienes/*administration & dosage/pharmacology ; Animals ; Creatinine/blood ; Desmin/genetics/metabolism ; Diabetes Mellitus, Experimental/*drug therapy/metabolism/pathology ; Diabetic Nephropathies/*drug therapy/metabolism/pathology ; Disease Models, Animal ; Humans ; Intracellular Signaling Peptides and Proteins/genetics/metabolism ; Kidney/*pathology ; Membrane Proteins/genetics/metabolism ; Phosphatidylinositol 3-Kinases/*antagonists & inhibitors ; Podocytes/*drug effects/metabolism/pathology ; Rats ; Rats, Inbred Strains ; cdc42 GTP-Binding Protein/genetics/metabolism ; rac1 GTP-Binding Protein/genetics/metabolism

OBJECTIVETo investigate the effects of silencing ADP-ribosylation factor 6 (Arf6) on the proliferation, migration, and invasion of prostate cancer cell line PC-3 and the possible molecular mechanisms.

METHODSThree Arf6-specific small interfering RNA (siRNA) were transfected into cultured prostate cancer cell line PC-3. Arf6 expression was examined by real-time PCR and Western blotting. MTT assay, wound healing assay, and Transwell migration and invasion assay were used to observe the effect of Arf6 silencing on the proliferation, migration, and invasion ability of PC-3 cells. The levels of phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2), ERK1/2, p-AKT, AKT and Rac1 were detected by Western blotting.

RESULTSTransfection of siRNA-3 resulted in significantly decreased Arf6 mRNA and protein expression with inhibition rates of (91.88±3.13)% and (86.37±0.57)%, respectively. Arf6 silencing by siRNA-3 markedly suppressed the proliferation, migration and invasion of PC-3 cells and reduced the expression levels of p-ERK1/2 and Rac1.

CONCLUSIONSilencing of Arf6 efficiently inhibits the proliferation, migration, and invasion of PC-3 cells in vitro, and the underlying mechanisms may involve the down-regulation of p-ERK1/2 and Rac1.

ADP-Ribosylation Factors ; genetics ; metabolism ; Cell Line, Tumor ; Cell Movement ; Down-Regulation ; Humans ; Male ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Neoplasm Invasiveness ; Prostatic Neoplasms ; pathology ; RNA Interference ; RNA, Messenger ; genetics ; metabolism ; RNA, Small Interfering ; genetics ; Real-Time Polymerase Chain Reaction ; Transfection ; Wound Healing ; rac1 GTP-Binding Protein ; metabolism