Crosstalk between autophagy and apoptosis induced by Rip2 and its mechanisms in human pancreatic cancer cells

AIM To investigate the crosstalk between autophagy and apoptosis caused by receptor-interacting protein 2 (Rip2) and its underling mechanisms in human pancreatic cancer cells. METHODS Plasmids (pEGFP-C2 and pEGFP-Rip2) were transfected into human pancreatic cancer Panc-1 cells by jetPRIME method. The Panc-1 cells transfected with pEGFP-Rip2 were treated with 3-methyladenine (3-MA), an autophagy inhibitor. The apoptotic rate was analyzed by flow cytometry. The levels of apoptosis-associated proteins were measured by Western blot. The activity of caspase-8, -9 and -3 was examined by colorimetric method. Moreover, the Panc-1 cells transfected with pEGFP-Rip2 were treated with Z-VAD-FMK, a broad inhibitor of caspases. Subsequently, the levels of autophagy- and PI3K/Akt/mTOR signaling pathway-related proteins were assessed by Western blot. The autophagosomes were observed under transmission electron microscope. RESULTS (1) The apoptotic rate in pEGFP-Rip2 group markedly increased as compared with control group and pEGFP-C2 group, while the apoptotic rate in pEGFP-Rip2+3-MA group was further elevated compared with pEGFP-Rip2 group (P<0.05). Meanwhile, the protein levels of Fas, Bax and cytoplasmic cytochrome c (Cyt-c) were significantly increased, and the protein expression of Bcl-2 was markedly reduced in pEGFP-Rip2+3-MA group as compared with pEGFP-Rip2 group (P<0.05). The activity of caspase-8, -9 and -3 in pEGFP-Rip2+3-MA group was higher than that in pEGFP-Rip2 group. (2) The protein expression of beclin-1 and LC3-Ⅱ was significantly increased and more accumulated autophagosomes were observed under transmission electron microscope in pEGFP-Rip2+Z-VAD-FMK group as compared with pEGFP-Rip2 group. Furthermore, the protein levels of p-mTOR and p-Akt in pEGFP-Rip2+Z-VAD-FMK group were markedly reduced compared with pEGFP-Rip2 group, while no significant difference of mTOR and Akt protein expression was found between the 2 groups. CONCLUSION Inhibition of autophagy promotes apoptosis induced by Rip2 in the pancreatic cancer cells. Its mechanism may be associated with the further activation of the intrinsic and extrinsic apoptotic pathways. Suppression of apoptosis accelerates autophagy induced by Rip2 in the pancreatic cancer cells, and the mechanism may be related to the further down-regulation of PI3K/Akt/mTOR signaling pathways. There is a mutual antagonistic effect between autophagy and apoptosis caused by Rip2 in pancreatic cancer cells.     

Photodynamic action of hematoporphyrin on human pancreatic cancer cell line Panc-1

AIM: To study the killing effect of photodynamic therapy (PDT) with hematoporphrin on human pancreatic cancer cell line Panc-1 in vitro.METHODS: The Panc-1 cells were divided into several groups according to the concentrations of photosensitizer and light doses to which the cells were exposed.The absorbance values of CCK-8 test were used as the detection index and were converted to cell survival.To study the main mechanism of PDT, the ROS production, the apoptotic rate and necrotic rate, and the expression of activated caspase-3 in the cells were measured by fluorescence microscopy, flow cytometry and Western blotting, respectively.RESULTS: With the concentration of photosensitizer and light dose increased, the survival rates of Panc-1 cells accordingly decreased, and the killing effect of PDT reached the maximum when the concentration of photosensitizer was 10 mg/L and the light dose was 20 J/cm².The synergistic effect between concentration of photosensitizer and light dose was observed.Using photosensitizer or light alone had no PDT effect.Exposure to photosensitizer and light induced ROS production and caused apoptosis and necrosis in Panc-1 cells in a concentration-dependent manner, and the rate of apoptosis was always higher than the rate of necrosis.PDT also increased the expression of activated caspase-3 in Panc-1 cells in a concentration-dependent manner.CONCLUSION: PDT with hematoporphyrin has killing effect on human pancreatic cancer cell line Panc-1 by producing ROS, activating caspase-3 and inducing apoptosis and necrosis in a concentration-dependent manner.The concentration of photosensitizer and light dose show synergistic effect on killing the cancer cells.     

Rip2 induces autophagy and its mechanism in human pancreatic cancer cells

AIM:To explore whether receptor-interacting protein 2 (Rip2) induces autophagy and its under-lying mechanisms in human pancreatic cancer cell line Panc-1. METHODS:The empty plasmid pEGFP-C2 or recombinant plasmid pEGFP-Rip2 was transfected into the Panc-1 cells by jetPRIME reagent. The untreated cells served as control group. The protein levels of Rip2, autophagy-related molecules (beclin-1 and LC3-Ⅱ), and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway-related proteins were determined by Western blot 48 h after transfection. The morphological changes of the autophagosomes were observed by transmission electron microscopy. RESULTS:The protein level of Rip2 was significantly increased in the Panc-1 cells transfected with pEGFP-Rip2 plasmid. The protein expression of beclin-1 and LC3-Ⅱ in pEGFP-Rip2 group was higher than that in control group and pEGFP-C2 group (all P<0.01). An increased number of autophagosomes was observed under transmission electron microscope in pEGFP-Rip2 group as compared with control group and pEGFP-C2 group. Furthermore, the protein levels of p-mTOR and p-AKT in pEGFP-Rip2 group were lower than those in control group and pEGFP-C2 group (all P<0.01), while no significant difference of the total mTOR and AKT protein levels was found among the 3 groups. CONCLUSION:Rip2 induces autophagy in the Panc-1 cells and its mechanism may be related to inhibiting the activation of PI3K/Akt/mTOR pathway.     

Manumycin inhibits activity of pancreatic duct cancer cell line Panc-1 via inducing apoptosis

AIM: In this study, we investigated the anticancer effect and mechanisms of manumycin on pancreatic cancer cell line-Panc-1 and the role of p38MAPK pathway in apoptosis. METHODS: The test of anticancer effect was performed by MTT assay. Apoptosis was induced in the cells by manumycin and then treated with SB203580, a specific p38MAPK inhibitor. A quantitative caspase-3 activity assay kit was used in this experiment. RESULTS: Manumycin (6 μmol/L, 18 μmol/L, 54 μmol/L) significantly inhibited cell growth of pancreatic cancer cell line Panc-1. The inhibition rates 24 h after treatment with 6 μmol/L, 18 μmol/L and 54 μmol/L manumycin were 8.9%, 21.9% and 67.0%, respectively. Compared with the control group, the survival levels of the last two groups were of significant statistical difference (P<0.01). The anticancer effects also showed dosage-effect relationship, the value of IC50 24 h after treatment was 34.7 μmol/L. In addition, this reagent simultaneously activated caspase-3 protein, which was partly blocked by p38MAPK specific inhibitor, SB203580. CONCLUSION: Manumycin exerted anticancer effect on Panc-1 cell line via inducing cell apoptosis, which was partly regulated by p38MAPK.     

Effect of Ginsenoside Rh2 on apoptosis of human osteosarcoma cell line MG-63

AIM: To investigate the effect of Ginsenoside Rh2(Rh2) on the apoptosis of human osteosarcoma cell line MG-63.METHODS: The cell viability was determined by MTT assay. MG-63 cell apoptotic rate was examined by flow cytometry with Annexin V-PI double staining. The expression of Bcl-2, Bax, cytochrome C(Cyt C) and cleaved caspase-3 were measured by Western blot.RESULTS: Rh2 enhanced the apoptosis of MG-63 cells in a dose-dependent manner. Furthermore, after treatment with Rh2, the release of mitochondrial Cyt C and Bax expression were increased, while Bcl-2 and the ratio of Bcl-2/Bax were decreased as compared with control group(P<0.05). The protein level of cleaved caspase-3 was also increased(P<0.05).CONCLUSION: Ginsenoside Rh2 accelerates the apoptosis of MG-63 cells through mitochondria-dependent pathway, suggesting that Rh2 is a novel approach for the treatment of osteosarcoma.     

Effect of IGFBP7 on proliferation of human breast cancer cell line MCF-7

AIM: To investigate the mechanism that insulin-like growth factor binding protein 7 (IGFBP7) inhibits proliferation of human breast cancer cell line MCF-7. METHODS: Plasmid pCMV6-IGFBP7 or empty plasmid was transfected into MCF-7 cells. The expression of IGFBP7 in MCF-7 cells after transfection was detected by Western blotting. The effects of IGFBP7 on the colony-forming efficiency and the cell cycle were studied by soft agar colony formation assay and flow cytometry,respectively. The effects of IGFBP7 on the expression of ERK1/2, p-ERK1/2, cyclin D1, CDK4, cyclin E, CDK2, p21^CIP1/WAF1, p27^KIP1, p53, Rb and p-Rb in MCF-7 cells were detected by Western blotting. RESULTS: Only the transfectant of pCMV6-IGFBP7 expressed IGFBP7. IGFBP7 remarkably reduced colony-forming efficiency (P<0.01) and G₀/G₁ arrest (P<0.01), inhibited phosphorylation of ERK1/2 (P<0.01), down-regulated cyclin D1 and cyclin E (P<0.01), up-regulated p27^KIP1, p21^CIP1/WAF1 and p53 (P<0.01), and inhibited phosphorylation of Rb (P<0.01) in MCF-7 cells. PD98059, an inhibitor of MEK1 and MEK2, imitated part of the tumor-suppressing activity of IGFBP7. CONCLUSION: IGFBP7 inhibits the proliferation of human breast cancer cell line MCF-7 by down-regulating cyclin D1 and cyclin E, up-regulating p27^KIP1, p21^CIP1/WAF1 and p53 and inhibiting phosphorylation of Rb. ERK1/2 signaling pathway might be involved in the regulation of cyclin D1 and p27^KIP1 by IGFBP7.     

Effect of Bmi-1 gene overexpression on proliferation of human gastric mucosal epithelial cell line GES-1

AIM: To investigate the effect of B lymphoma Moloney murine leukemia virus insertion region 1 ( Bmi-1 ) gene overexpression on the proliferation of a human normal gastric epithelial cell line GES-1. METHODS: The plasmid containing Bmi-1 gene or empty plasmid was transfected into GES-1 cells by retroviral mediation. The expression of Bmi-1 at mRNA and protein levels was detected by quantitative real-time PCR (qRT-PCR) analysis and Western blotting, respectively. The effect of Bmi-1 gene overexpression on the cell cycle of GES-1 cells was evaluated by flow cytometry. The proliferation of the stably transfected cells was measured by Cell Counting Kit-8. RESULTS: The results of qRT-PCR analysis and Western blotting demonstrated that stably transfected cell line was successfully established. The results of flow cytometry analysis showed that overexpression of Bmi-1 reduced the G₀/G₁ phase, arrested the cells in G₂/M phase and S phase. The growth curve showed that overexpression of Bmi-1 resulted in increased growth speed. CONCLUSION: Increase in Bmi-1 gene expression regulates the cell cycle and promotes the proliferation of GES-1 cells.     

Effects of the grub extract on apoptosis of MCF-7 human breast cancer cell line

AIM: To investigate the apoptotic pathway of MCF-7 breast cancer induced by the grub extract in vitro.METHODS: MTT assay was used to determine the effect of the grub extract on proliferation of MCF-7 human breast cancer cell line and cell toxicity. Morphological changes of the apoptosis in cancer cells were observed by HE staining through invert microscope, light microscope, AO/EB double fluorescent staining under fluorescent microscope. FCM was used to assay the change of apoptotic rate. The expression of Bcl-2, Fas, caspase-9, caspase-3 in apoptotic pathway was detected with immunocytochemical method before and after exposure to the grub extract, and the effect of that on apoptotic pathway was explored.RESULTS: (1) The MTT test showed that the growth of MCF-7 human breast cancer cell line was significantly inhibited by the grub extract in dose and time dependent manners. The inhibitory rate in exposure group was significantly different from that in control group (P<0.01). (2) Morphological changes of apoptosis including nuclear condensation, fragment and apoptosis body formation were observed by invert microscope. (3) The MCF-7 human breast cancer cells in experimental group by HE staining showed nuclear condensation and blue-black, cytoplasm slight red, nuclear chromatin condensation and fragment shape, apoptosis body formations. (4) Apoptosis in the experimental group was observed by AO/EB double fluorescent staining under fluorescent microscope. (5) FCM assay indicated that apoptotic rate increased significantly in time dependent manner in experimental group. (6) The expression of Bcl-2 was down-regulated, while that of Fas, caspase-3, caspase-9 was up-regulated, compared with control group (P<0.01).CONCLUSION: (1) The proliferation of MCF-7 human breast cancer cell line can be inhibited significantly by the grub extract in vitro. (2)The mechanism of effect of the grub extract on MCF-7 human breast cancer cell line might be mediated by down-regulation of Bcl-2 and up-regulation of Fas, caspase-3, caspase-9. This type of apoptosis starting and performing is through death receptor pathway and mitochondrial pathway.     

Effect of ARMCX1 on proliferation and apoptosis of cervical cancer SiHa cells

AIM: To observe the effect of Armadillo repeat-containing X-linked protein 1 (ARMCX1) on the proliferation and apoptosis of human cervical cancer SiHa cells by knock-down of ARMCX1 expression with small interfering RNA. METHODS: After knock-down of ARMCX1 expression, the cell cycle distribution and apoptosis of SiHa cells were detected by flow cytometry. The proliferation of SiHa cells was observed by plate colony formation assay after knock-down of ARMCX1 for 10 d. The protein levels of cell proliferation-and apoptosis-related molecules were determined by Western blot. RESULTS: After knock-down of ARMCX1 expression in the SiHa cells, the cell colony formation ability was significantly inhibited (P < 0.05), the cell cycle was arrested in S phase, and the protein levels of cyclin E and cell division cycle 25A (Cdc25A) in the SiHa cells were decreased. Meanwhile, knock-down of ARMCX1 expression promoted the apoptosis of SiHa cells, significantly reduced the protein expression of Bcl-2, and significantly increased the protein levels of Bax and active caspase-3 (P < 0.05). CONCLUSION: Knock-down of ARMCX1 expression inhibits the proliferation of SiHa cells and induces apoptosis.     

Over-expression of GSTP1 increases oxaliplatin-induced apoptosis in human hepatoma HepG2 cells

AIM: To investigate the effect of GSTP1 over-expression on the sensitivity of human hepatoma HepG2 cells to oxaliplatin (OXA). METHODS: Adenovirus carrying GSTP1 (Ad-GSTP1) was used to infect HepG2 cells for establishing the cell line over-expressing GSTP1. The cells were randomly divided into 6 groups:control, vehicle, Ad-GSTP1, OXA, OXA+vehicle and OXA+Ad-GSTP1. The cell survival rates were examined by CCK-8 assay, and the apoptotic rates were analyzed by flow cytometry. The protein levels of GSTP1, Akt, mTOR, p-Akt and p-mTOR were determined by Western blot. RESULTS: OXA decreased the cell survival rate in a dose-dependent manner (P<0.05). The protein expression of GSTP1 increased after transfection with adenovirus. At basal level, up-regulation of GSTP1 significantly decreased the cell survival rate, increased the cell apoptosis, and inhibited the phosphorylation levels of Akt and mTOR (P<0.05). Moreover, GSTP1 over-expression enhanced the effect of OXA on the cell viability, cell apoptosis, and further inhibited the phosphorylation levels of Akt and mTOR (P<0.05).CONCLUSION: Over-expression of GSTP1 augments the enhanced effect of OXA on HepG2 cell apoptosis, which may be related to the inactivation of Akt/mTOR signaling pathway.     

NAC-1 -specific siRNA enhances paelitaxel-induced apoptosis of ovarian cancer cell line HO8910

AIM: To observe the effect of NAC-1 -specific siRNA alone, or in combination with paelitaxel on proliferation and apoptosis of human ovarian cancer cell line HO8910. METHODS: Ovarian cancer cells were treated with NAC-1 siRNA alone or in combination with paelitaxel. The level of NAC-1 mRNA was assessed by real-time quantitative PCR. Western blotting analysis was used to detect NAC-1 protein and the activation of epidermal growth factor receptor(EGFR) downstream signals,Akt and ERK. The cell proliferation rate was measured by MTT assay, and the cell cycle and apoptosis were determined by flow cytometry. RESULTS: After treated with NAC-1 -specific siRNA for 48 h, the expression of NAC-1 at mRNA and protein levels in HO8910 cells decreased by 71.1% and 80.5%, respectively. The cells in G₁ phase increased. The protein levels of p-Akt and p-ERK were decreased by 43.7% and 49.8%, respectively. After treated with NAC-1 -specific siRNA for 72 h, the proliferation inhibitory rate of the cells was increased to 45.6% as compared with the cells treated with negative siRNA. Apoptotic rate of the cells treated with NAC-1 siRNA (0.5 μmol/L combined with 2 μmol/L of paelitaxel) for 72 h was (30.93±4.57)%,higher than that of the cells treated with paelitaxel alone[(23.85±3.65)%]. CONCLUSION: NAC-1 siRNA suppresses NAC-1 gene expression and EGFR downstream signaling activation, inhibits cell proliferation and enhances the responsiveness of ovarian cancer cells to paelitaxel. The combination treatment produces synergistic inhibition.     

Effect of arctigenin on apoptosis of human nasopharyngeal carcinoma cell line CNE-1

AIM: To investigate the effect of arctigenin on the apoptosis of human nasopharyngeal carcinoma cell line CNE-1 and its potential mechanism. METHODS: The inhibition of cell viability was analyzed by CCK-8 assay. The activity of caspase-3 and caspase-9 was analyzed by caspase-3 and caspase-9 activity kit. Apoptotic cell percentage was evaluated by Annexin V-PI staining. The expression of PI3K/AKT/XIAP signal pathway-related molecules at mRNA and protein levels was analyzed by real-time PCR and Western blot. RESULTS: Arctigenin inhibited the cell activity in a dose- and time-dependent manner after treatment with arctigenin at concentrations of 10, 20, 40 and 80 μmol/L for 24 h, 48 h and 72 h (P<0.01). Arctigenin also increased the activity of caspase-3 and caspase-9 and the apoptotic rate (P<0.05), and down-regulated the mRNA and protein expression of PI3K/AKT/XIAP signal pathway-related molecules (P<0.05).CONCLUSION: Arctigenin induces the apoptosis of CNE-1 cells through PI3K/AKT/XIAP signal pathway.     

Transition of WT1 isoforms inhibits proliferation and promotes apoptosis of human leukemia cell line HL-60

AIM: To study the potential effects of exogenous Wilms tumor 1 (WT1) isoforms on the proliferation and apoptosis of human leukemia cell line HL-60. METHODS: WT1 (17AA－/KTS－) gene obtained by RT-PCR was cloned into a PCDH1-MCS1-EF1-copGFP plasmid. The recombinant plasmid was confirmed by enzyme digestion and sequencing, and was transfected into HL-60 cells by LipofectamineTM 2000. The stable transformants were selected by G418 screening. WT1(17AA－/KTS－) expression was identified by real-time fluorescence quantitative RT-PCR and Western blotting. The proliferation of the cells was measured by MTT assay. The apoptosis of the cells was determined by morphological observation and flow cytometry analysis. RESULTS: The eukaryotic expression vector PCDH1-MCS1-EF1-copGFP-WT1 (17AA－/KTS－) was successfully constructed. The recombinant cells exhibited high mRNA and protein levels of WT1(17AA－/KTS－). The growth of recombinant cells was slower than that of HL-60 cells transfected with control vector and normal HL-60 cells. After exposed to As2O3 at 2 μmol/L for 48 h, both recombinant cells and control cells exhibited the morphological characteristics of apoptosis, but the former was more typical than the latter. The apoptosis was enhanced in the recombinant cells after the cells were exposed to As2O3 for 24 h. CONCLUSION: Exogenous WT1(17AA-/KTS-) isoform inhibits the proliferation and promotes the apoptosis of leukemic cells.     

Effects of shRNA targeting SIAH2 gene on proliferation and apoptosis of human hepatoma cell line HepG2

AIM：To investigate the effects of shRNA-mediated seven in absentia homolog 2 (SIAH2; one of ubiquitin ligases) gene silencing on cell cycle and apoptosis of human hepatoma cell line HepG2. METHODS：The specific recombinant vector pGenesil-SIAH2 was transiently transfected into HepG2 cells with Lipofectamine 2000. RT-PCR and Western blotting were performed to detect the mRNA and protein expression levels of SIAH2. MTS assay was employed to evaluate the cell proliferation. Flow cytometry was used to determine the cell cycle and apoptosis of the transfected cells. RESULTS：Compared with control groups, the mRNA and protein levels of SIAH2 were reduced by pGenesil-SIAH2 transfection in HepG2-SIAH2 group. The proliferation of HepG2-SIAH2 cells was significantly inhibited. The percentage of G1-phase cells and the early apoptotic rate were significantly higher in HepG2-SIAH2 cells. CONCLUSION: Tansfection of pGenesil-SIAH2 effectively inhibits the proliferation of HepG2 cells, arrests the cells in G1 phase and induces apoptosis, indicating an experimental basis of SIAH2-targeting gene therapy for hepatocellular carcinoma.     

Effects of silencing of COX-2 gene expression by siRNA on cell proliferation,cell cycles,apoptosis and tumorigenicity of human pancreatic cancer Capan-2 cells

AIM: To investigate the effects of silencing of cyclooxygenase-2 (COX-2) gene expression by siRNA on the proliferation, apoptosis, cell cycle and tumorigenicity of human pancreatic cancer Capan-2 cells.METHODS: The gene transfection was performed using Lipofectamine 2000 (Lipo). The proliferation, apoptosis and cell cycle of Capan-2 cells were tested by the methods of cell counting, microscopy and FCM. The mRNA expression of COX-2 was determined by RT-PCR and real-time PCR. The protein level of COX-2 was detected by Western blotting. The tumorigenicity of Capan-2 cells transfected with siRNA-COX-2 was determined using the model of nude mice. RESULTS: Transfection efficiency of 96.47% was obtained under the conditions that the transfection volume was 2 mL, concentration of Lipo was 5 μL and that of siRNA-COX-2 was 50 nmol/L. The best sequence of siRNA-COX-2 for silencing of COX-2 gene expression was siRNA006 with the silencing rate of up to 73% 24 h after tansfection. siRNA-COX-2 slowed down the growth of Capan-2 cells 48 h after transfection (P<0.05). At time points of 48 h and 72 h after transfection, the protein expression of COX-2 was down-regulated to 67% and 61% of the normal level, the proliferation inhibition rate was 35.48% and 56.32%, and the apoptotic rate was 2.03% and 3.27%, respectively. At time points of 24 h, 48 h and 72 h after transfection, the proportion of the cells in G₀/G₁ phrase was 58.03%, 63.31% and 65.66%, and that of the cells in S phase was 30.27%, 24.87% and 22.2%, respectively. The mean volume and weight of tumor tissues were remarkably decreased due to the transplantation of Capan-2 cells transfected with siRNA-COX-2.CONCLUSION: siRNA-COX-2 effectively silences the expression of COX-2 gene, inhibits the growth and decreases the tumorigenicity of Capan-2 cells.     

Effects of phycocyanin on apoptosis of human laryngeal cancer HEP-2 cells

AIM: To investigate the effect of phycocyanin on the apoptosis of human laryngeal cancer HEP-2 cells and to explore the inhibitory mechanism of phycocyanin to tumor. METHODS: Highly purified phycocyanin was extracted from spirulina. The effects of phycocyanin at different concentrations on the growth of human laryngeal cancer HEP-2 cells were detected by MTT assay. In addition, the cell structures were observed under electron microscope. The cell apoptosis was analyzed by flow cytometry. The production of reactive oxygen species (ROS) was measured by flow cytometry. Enzymatic activities of caspase-3, -8 and -9 were measured by chemical colorimatry. The expression of Bax, Bcl-2, Fas, P53, caspase-3 and caspase-9 at mRNA and protein levels was determined by RT-PCR and Western blot. RESULTS: MTT test confirmed that phycocyanin inhibited the cell activity of HEP-2 cells with time and dose dependent manners. The result of electron microscope observation and flow cytometry indicated that phycocyanin induced the apoptosis of HEP-2 cells. The intracellular content of ROS was increased. The activities of caspase-3, -8 and -9 were increased. RT-PCR showed that the mRNA expression of Bax, Fas, P53, caspase-3, caspase-9 was increased and Bcl-2 was decreased. The results of Western blot were consistent with the results of RT-PCR. CONCLUSION: Phycocyanin might induce apoptosis of HEP-2 cells by down-regulating Bcl-2, up-regulating Bax, Fas and P53, and the transduction of apoptotic signals in the human laryngeal cancer cells.     

Effect of gonadotropin-releasing hormone analogue on human breast cancer cell line in vitro

AIM: To investigate the effects of gonadotropin-releasing hormone (GnRH) analogue on the growth of breast cancer cell lines MCF-7 and MDA-MB-231 in vitro and to explore the related mechanisms with PI3K/Akt or ERK/MAPK pathways. METHODS: The proliferation of human breast cancer cell lines MCF-7 and MDA-MB-231 treatment with triptorelin was detected by MTT assay and the distribution of the cell cycle was determined by flow cytometry. The phosphorylation of the ERK1/2 and Akt was evaluated by Western blotting. RESULTS: Triptorelin inhibited the proliferation of MCF-7 cells at concentration of 10^-5 mol/L after treated for 192 h or at concentration of 10^-4 mol/L after treated for 168 h and 192 h. Triptorelin inhibited the proliferation of MDA-MB-231 cells at concentration of 10^-4 mol/L after treated for 192 h (P<0.05).Treatment with triptorelin for 192 h at concentration of 10^-4 mol/L had no statistical significance effect on phosphorylation of ERK1/2 and Akt(P>0.05).CONCLUSION: Inhibitory effect of GnRH analogue triptorelin on human breast cancer cells is not just the connection with the down-regulation of pituitary hormone, but also a direct inhibitory effect. The role may not be involved in the activation of ERK/MAPK and PI3K/Akt signaling pathways.     

Effects of WNT5B over-expression on viability and apoptosis of human breast cancer cell line MCF-7

AIM: To detect the expression of WNT5B in normal breast epithelial cells and different breast cancer cell lines, and to investigate the effects of WNT5B over-expression on the viability and apoptosis of human breast cell line MCF-7.METHODS: The mRNA expression of WNT5B was detected by RT-PCR in different breast cancer cells. MCF-7 cells were transfected with plasmid pcDNA3.1/WNT5B or pcDNA3.1, and the expression of WNT5B at mRNA and protein levels was examined in the 2 groups by real-time PCR and Western blotting, respectively. Subsequently, the changes of cell viability and cell apoptosis were analyzed by CCK-8 assay and flow cytometry, respectively. RESULTS: The expression of WNT5B in the breast cancer cell lines was lower than that in MCF10A cells. The WNT5B expression in the MCF-7 cells in experimental group was significantly higher than that in vector group (P<0.05). However, the cell viability in experimental group decreased significantly as compared with vector group (P<0.05). The number of the cells in S-phase obviously increased, while the percentage of the cells in G₁-phase and G₂/M-phase decreased compared with vector group. The number of apoptotic cells in WNT5B group was significantly higher than that in vector group.CONCLUSION: The expression of WNT5B is decreased in breast cancer cells. WNT5B over-expression significantly inhibits the cell growth and promotes the cell apoptosis in breast cancer MCF7 cells.     

Effects of JAG1 gene silencing on proliferation and apoptosis of human breast cancer MDA-MB-231 cells

AIM:To investigate the effects of Jagged 1 (JAG1) gene silencing on the proliferation and apoptosis of human breast cancer MDA-MB-231 cells. METHODS:The specific recombinant vector pRS-JAG1 was transfected into MDA-MB-231 cells with lipofectamine. The protein expression of JAG1 was observed by Western blotting after transfection. MTT assay was used to detect the effect of JAG1 gene silencing on the growth of the cells. The apoptosis and cell cycle were analyzed by flow cytometry. The protein levels of cyclin D1, p21CIP1/WAF1, p27KIP1, p-Rb, Bcl-2, Bax, Bcl-xL and cleaved caspase-3 were determined by Western blotting. RESULTS:Compared with control group, the expression level of JAG1 was reduced by pRS-JAG1 transfection for 72 h (P<0.05). The growth of MDA-MB-231 cells in shJAG1 group was significantly inhibited (P<0.05). The percentages of G 0/G 1-phase cells and early apoptotic rate were obviously higher in shJAG1 group than those in control group (P<0.05). The shRNA-mediated JAG1 silencing decreased the protein levels of cyclin D1, p-Rb, Bcl-2 and Bax, and increased the protein levels of p21CIP1/WAF1, p27KIP1, Bax and cleaved caspase-3 (P<0.05). CONCLUSION:JAG1 silencing effectively inhibits the proliferation and induces the apoptosis of human breast cancer cells, suggesting that JAG1 might serve as a therapeutic target for triple-negative breast cancer.     

Effects of shRNA targeting COL1A1 gene on proliferation and apoptosis of human breast cancer cell line MDA-MB-231

AIM: To investigate the effects of shRNA-mediated collagen type I alpha 1 (COL1A1) gene silencing on the proliferation and apoptosis of human breast cancer cell line MDA-MB-231. METHODS: The specific recombinant vector pSilencer2.1-U6-COL1A1 was transiently transfected into human breast cancer cell line MDA-MB-231 with lipofectamine. RT-PCR and Western blotting were performed to detect the expression levels of COL1A1. MTT assay was employed to evaluate the effect of COL1A1 gene silencing on the cell proliferation. Flow cytometry was used to determine the apoptosis and cell cycle of transfected cells. The morphological characteristics of apoptosis were observed by Hoechst 33258 staining. RESULTS: Compared with mock group and scrambled group, the mRNA and protein levels of COL1A1 were reduced by pshRNA-COL1A1 transfection (P<0.05). The proliferation of MDA-MB-231 cells treated in shRNA-COL1A1 was significantly inhibited in a time-dependent way. The percentages of G₀/G₁ phase cells and early apoptotic rate were significantly higher in pshRNA-COL1A1 group than those in mock and scrambled group (P<0.05). The changes of apoptotic morphology such as cell shrinkage and nuclear condensation were also observed by staining with Hoechst 33258 under fluorescence microscope. CONCLUSION: Transfection of eukaryotic expression vector pshRNA-COL1A1 effectively inhibits the proliferation, induces apoptosis and arrests MDA-MB-231 cells in G0/G1 phase.