miR-24-3p targeting KLF6 gene affects viability and apoptosis of esophageal cancer cells via IL-6/STAT3 signaling pathway

AIM: To investigate the effect of microRNA-24-3p (miR-24-3p) on the viability and apoptosis of esophageal cancer cells. METHODS: The expression of miR-24-3p and KLF6 mRNA in the esophageal cancer cells TE11, Eca109 and EC9706 were detected by RT-qPCR. The protein expression of KLF6 was determined by Western blot. EC9706 cells were transfected with anti-miR-24-3p and KLF6 siRNA. The cell viability was measured by MTT assay, the apoptotic rate was analyzed by flow cytometry, and the proliferation, apoptosis and IL-6/STAT3 signaling pathways related proteins were determined by Western blot. The level of IL-6 was measured by ELISA. The dual luciferase reporter gene assay was used to verify the relationship between miR-24-3p and KLF6. RESULTS: The levels of miR-24-3p were up-regulated in the esophageal cancer cells TE11, Eca109 and EC9706 (P < 0.05), and the expression of KLF6 at mRNA and protein levels was down-regulated (P < 0.05). Knock-down of miR-24-3p expression inhibited the cell viability, induced apoptosis, and inhibited the protein levels of CDK4, cyclin D1, CDC25A, p-STAT3, Bcl-2 and IL-6, and promoted the protein expression of caspase-3 and Bax in EC9706 cells. CONCLUSION: miR-24-3p targets KLF6 gene to affect the viability and apoptosis of esophageal cancer cells by regulating IL-6/STAT3 signaling pathway.     

Tetrandrine induces autophagy of ovarian cancer cells by inhibiting PI3K/Akt/mTOR signaling pathway

AIM To investigate the effect of tetrandrine on the autophagy of human ovarian serous cystadenocarcinoma SKOV3 cells, and to explore its molecular mechanism. METHODS The SKOV3 cells were treated with various concentrations of tetrandrine, and the cell viability was measured by MTT assay. The formation of autophagolysosomes was observed by acridine orange staining under fluorescence microscope. The protein levels of LC3, mTOR, p-mTOR, Akt and p-Akt in the SKOV3 cells were determined by Western blot. The viability of the SKOV3 cells treated with tetrandrine alone or combined with autophagy inhibitor 3-methyladenine (3-MA) were measured by MTT assay. RESULTS Tetrandrine significantly inhibited the viability of SKOV3 cells in a dose-dependent manner (P<0.01). The results of acridine orange fluorescence staining showed that the number of intracellular autophagolysosomes with bright red fluorescence in the SKOV3 cells was significantly increased after tetrandrine treatment, while the autophagolysosomes were rarely observed in control group. The protein levels of LC3-II and P62 in the SKOV3 cells were significantly increased after tetrandrine treatment (P<0.01). Furthermore, treatment with tetrandrine resulted in significant down-regulation of phosphorylated form of mTOR and AKT in the SKOV3 cells (P<0.01), while total mTOR and AKT protein levels were not changed. Finally, combination of tetrandrine and 3-MA significantly decreased the cell viability compared with using tetrandrine alone (P<0.01). CONCLUSION The autophagy of human ovarian cancer SKOV3 cells were induced by tetrandrine and the molecular mechanism may be related to inhibition of PI3K/Akt/mTOR signaling pathway．     

Cepharanthine induces autophagy via PI3K/AKT/mTOR signaling pathway in ovarian cancer SKOV3 cells

AIM: To investigate the autophagy of human ovarian cancer SKOV3 cells induced by cepharanthine and to explore its mechanism. METHODS: The effect of cepharanthine on the viability of ovarian cancer SKOV3 cells was measured by CCK-8 assay. The SKOV3 cells were treated with cepharanthine, and then the formation of autophagosome was observed with acridine orange staining under fluorescence microscope. The protein levels of LC3, AKT, p-AKT, mTOR, p-mTOR and GAPDH in the SKOV3 cells treated with cepharanthine were determined by Western blot.RESULTS: Cepharanthine significantly inhibited the viability of ovarian cancer SKOV3 cells in a dose-dependent manner (P<0.05). The number of the intracellular acidic autophagosomes with bright red fluorescence was significantly increased after cepharanthine treatment in the SKOV3 cells. The expression of LC3-Ⅱ in SKOV3 cells was significantly enhanced after cepharanthine treatment. Furthermore, treatment with cepharanthine in the SKOV3 cells also resulted in a significant down-regulation of phosphorylated form of AKT and mTOR (P<0.01), while the total protein level was not changed. Combination of cepharanthine and 3-methyladenine resulted in a substantial decrease in the cell viability compared with using cepharanthine alone.CONCLUSION: Cepharanthine significantly inhibits the growth of human ovarian cancer SKOV3 cells and induces the autophagy, which may be correlated with down-regulation of PI3K/AKT/mTOR signaling pathway.     

Growth inhibition of colorectal cancer HCT116 cells by lincRNA-p21 through STAT3 signaling pathway

AIM: To study the effect of long intergenic non-coding RNA-p21 (lincRNA-p21) on the growth inhibition of colorectal cancer HCT116 cells via STAT3 signaling pathway. METHODS: The human colorectal cancer cell line HCT116 was used to construct the cells with over-expression of lincRNA-p21 by transfection of pcDNA-lincRNA-p21, and negative control cells were also set up. After transfection, the expression level of lincRNA-p21 was detected by RT-qPCR. The cell viability and proliferation were examined by MTT assay and plate colony formation assay, respectively. The protein levels of STAT3 and phosphorylated STAT3 (p-STAT3) were determined by Western blot. After STAT3 signaling pathway activator SD19 was used to treat the colorectal cancer HCT116 cells with over-expression of lincRNA-p21, Western blot was used to detect the protein levels of STAT3 and p-STAT3, MTT assay was used to measure the viability of the cells, and flow cytometry analysis was used to determine the cell apoptosis. RESULTS: Compared with control group and pcDNA group, the expression of lincRNA-p21 in pcDNA-lincRNA-p21 group was significantly up-regulated, the cell proliferation was inhibited, and the protein levels of STAT3 and p-STAT3 were significantly decreased (P<0.05). After treatment with STAT3 activator SD19, the protein levels of STAT3 and p-STAT3 in pcDNA-lincRNA-p21+SD19 group were higher than those in pcDNA-lincRNA-p21 group, the cell viability was increased, and the apoptotic rate was decreased significantly (P<0.05). CONCLUSION: Over-expression of lincRNA-p21 inhibits the growth of colorectal cancer HCT116 cells. STAT3 signaling pathway activator abolishes the growth inhibitory effect of lincRNA-p21 over-expression. lincRNA-p21 inhibits the growth of colorectal cancer cells by inhibiting the activation of STAT3 signaling.     

Jagged1 regulates STAT3 signaling pathway and affects growth and apoptosis of multiple myeloma cells

AIM:To investigate the effect of Jagged1 on the growth and apoptosis of multiple myeloma cells. METHODS:Transfection with small interfering RNA targeting Jagged1 and negative control was carried out in multiple myeloma cell line U266, and the mRNA and protein levels of Jagged1 in the cells were determined by RT-qPCR and Wes-tern blot. The cells without transfection were used as blank control. Trypan blue staining was used to draw the cell growth curve. The cell viability was measured by MTT assay. The apoptosis was analyzed by flow cytometry. The protein levels of STAT3, p-STAT3 and Bax in the cells were determined by Western blot. STAT3 signaling pathway inhibitor AG490 was used to detect the activation level of STAT3 signaling in the cells. RESULTS:Compared with the U266 cells without transfection, the expression of Jagged1 at mRNA and protein levels decreased in the U266 cells transfeced with small interfering RNA targeting Jagged1 (P<0.05). However, the expression of Jagged1 at mRNA and protein levels did not change in the U266 cells transfected with small interfering RNA negative control. Knockdown of Jagged1 expression decreased the cell viability, increased the apoptotic rate, increased Bax levels, and decreased the protein level of p-STAT3 in the U266 cells (P<0.05). AG490 treatment decreased the protein level of p-STAT3, blocked the activation of STAT3 signaling pathway, promoted the cell apoptosis induced by Jagged1 knockdown, and inhibited the viability of the U266 cells. CONCLUSION:Knock-down of Jagged1 expression promotes the apoptosis of multiple myeloma cells by inhibiting STAT3 signaling pathway, thus suppressing cell growth.     

Effects of sodium valproate on RPMI8226 and U266 cell proliferation and IL-6/JAK/STAT signaling pathway

AIM: To investigate the effects of sodium valproate (VPA) on the proliferation of multiple myeloma cell lines RPMI8226 and U266 and the regulation of IL-6/JAK/STAT signaling pathway. METHODS: The cells were treated with different concentrations of VPA for 12 h and 24 h. The growth of RPMI8226 cells and U266 cells was detected by MTT assay. Apoptotic rates and cell cycle were analyzed by flow cytometry. The mRNA expression of STAT3, STAT5 and STAT target genes Bcl-xL, Mcl-1, c-Myc, CCND1 and VEGF was measured by RT-PCR. Western blotting analysis was used to determine the total proteins and protein phosphorylation levels of JAK2 and STAT5. RESULTS: VPA inhibited the growth and induced the apoptosis of RPMI8226 cells and U266 cells in a concentration- and time-dependent manner. The levels of IL-6 in the culture supernatants of RPMI8226 cells and U266 cells treated with VPA were significantly higher than that in negative control group. VPA down-regulated the mRNA expression of STAT3, STAT5, Bcl-xL, Mcl-1, c-Myc, CCND1 and VEGF. After treated with VPA, the protein levels of p-JAK2, JAK2, p-STAT5 and STAT5 in RPMI8226 cells and U266 cells were significantly lower than those in control group. CONCLUSION: VPA inhibits the proliferation of PRMI8226 cells and U266 cells in vitro. The modulation of IL-6/JAK/STAT signaling pathway may be involved in its potential mechanisms.     

Marsdenia tenacissima extract inhibits viability and induces apoptosis of melanoma cells via regulating PI3K/AKT/mTOR signaling pathway

AIM:To evaluate the effects of Marsdenia tenacissima extract (MTE) on the viability and apoptosis of mouse skin melanoma cell line B16-F10. METHODS:B16-F10 cells were treated with MTE at different doses for 24 h or at different doses for different time, and the cell viability was measured by MTT assay. The apoptosis was analyzed by flow cytometry. The protein levels were determined by Western blot. Meanwhile, the cells were treated with insulin-like growth factor-1 (IGF-1) and the protein levels were measured again. RESULTS:The cells were treated with MTE for 72 h for further study according to the results of pre-experiments. MTE at 100 and 200 mg/L inhibited the viability of B16-F10 cells and decreased the protein expression of Ki67 and PCNA significantly. MTE induced the apoptosis of B16-F10 cells as demonstrated by increasing cleaved caspase-3 and cleaved caspase-9. Meanwhile, MTE down-regulated the protein levels of p-PI3K, p-AKT and mTOR. In addition, IGF-1, the activator of PI3K/AKT/mTOR pathway, alleviated the effects of MTE on the viability and apoptosis markedly. CONCLUSION:MTE inhibits the viability and induces the apoptosis of melanoma cells by down-regulating PI3K/AKT/mTOR signaling pathway.     

Procaine regulates CXCR7 and affects AKT/STAT3 signaling pathway to inhibit viability,migration and invasion of bladder cancer cells

AIM To investigate the effects of procaine (PCA) and CXC chemokine receptor 7 (CXCR7) on the viability, migration and invasion of bladder cancer cells and its potential mechanism. METHODS Human bladder cancer RT4 cells were treated with PCA at different concentrations, and were divided into PBS group (without PCA treatment), PCA group (treated with 4 mmol/L PCA), siRNA negative control (si-Con) group (transfected with si-Con), CX?CR7 siRNA (si-CXCR7) group (transfected with si-CXCR7), PCA+pcDNA group (treated with 4 mmol/L PCA and transfected with pcDNA) and PCA+pcDNA-CXCR7 group (treated with 4 mmol/L PCA and transfected with pcDNA-CX?CR7). The siRNA and pcDNA were transfected into the RT4 cells by liposome method. The mRNA expression of CX?CR7 in the RT4 cells was detected by RT-qPCR. The cell viability was measured by CCK-8 assay. The invasion and migration abilities of the cells were detected by Transwell assays. The protein levels of CXCR7, AKT, STAT3, p-AKT and p-STAT3 were determined by Western blot . RESULTS Compared with PBS group, the viability, migration ability and invasion ability of the RT4 cells treated with PCA at different concentrations were significantly decreased (P<0.05), and the expression of CXCR7 at mRNA and protein levels in PCA group was also significantly decreased (P<0.05). Compared with si-Con group, the expression of CXCR7 at mRNA and protein levels in si-CXCR7 group was significantly decreased, and the viability, migration ability and invasion ability of the cells were also significantly decreased (P<0.05). Compared with PCA+pcDNA group, the expression of CXCR7 at mRNA and protein levels in PCA+pcDNA-CXCR7 group was significantly increased, and the viability, migration ability and invasion ability of the cells were also significantly increased (P<0.05). Compared with PBS group, the protein levels of p-AKT and p-STAT3 in PCA group were significantly decreased(P<0.05). Compared with PCA+pcDNA group, the protein levels of p-AKT and p-STAT3 in PCA+pcDNA-CX?CR7 group were significantly increased (P<0.05). No significant difference in the protein levels of AKT and STAT3 among the groups was observed. CONCLUSION Treatment with PCA inhibits the viability, migration and invasion of bladder cancer cells by inhibiting the expression of CXCR7. Over-expression of CXCR7 reverses this effect of PCA. Its mechanism may be related to AKT/STAT3 signaling pathway.     

Shikonin induces apoptosis and autophagy of human cervical cancer HeLa cells by PI3K/Akt/mTOR signaling pathway

AIM:To observe the effects of shikonin on the apoptosis and autophagy of human cervical cancer HeLa cells, and to explore the possible role of PI3K/Akt/mTOR signaling pathway in these processes. METHODS:The HeLa cells were treated with shikonin, and the cell viability was detected by CCK-8 assay. The apoptosis was detected by Annexin V/PI double staining. The autophagosome was observed by transfection with GFP-LC3 into the HeLa cells. After the treatment with shikonin combined with autophagy inhibitor 3-methyladenine (3-MA) or apoptosis inhibitor Z-DEVD-FMK, the protein levels of autophagy-and apoptosis-related molecules microtuble-associated protein 1 light chain 3 (LC3) and cleaved caspase-3 in the HeLa cells were determined by Western blot. The protein levels of phosphorylated PI3K (p-PI3K), phosphorylated Akt (p-Akt) and phosphorylated mTOR (p-mTOR) were also determined by Western blot. RESULTS:Shikonin significantly inhibited the viability of HeLa cells (P<0.05). Compared with control group, shikonin significantly induced apoptosis of HeLa cells (P<0.05). The results of GFP-LC3 plasmid transfection analysis showed that green dot-like congregate autophagosomes appeared in the cytoplasm of the HeLa cells after shikonin treatment, while the autophagosomes were rarely observed in control group. Compared with shikonin group, LC3-Ⅱ/LC3-I was significantly decreased and cleaved caspase-3 was significantly increased in shikonin+3-MA group (P<0.05). Compared with shikonin group, LC3-Ⅱ/LC3-I was significantly increased and cleaved caspase-3 was significantly decreased in shikonin+Z-DEVD-FMK group (P<0.05). Compared with control group, shikonin significantly decreased the protein levels of p-PI3K, p-Akt and p-mTOR (P<0.05). CONCLUSION:The apoptosis and autophagy of the HeLa cells are induced by shikonin, these two processes are complementary. The mechanism may be related to inhibition of PI3K/Akt/mTOR signaling pathway.     

HBx modulates apoptosis by activating JAK2/STAT3 signaling pathway in human renal proximal tubular epithelial cells

AIM: To investigate the correlation of hepatitis B virus X protein (HBx) with renal tubular epithelial cell apoptosis in hepatitis B virus-associated glomerulonephritis (HBVGN) and the possible signaling mechanism. METHODS: The activation of JAK2/STAT3 signal pathway and the expression of apoptosis-related proteins in human kindey proximal tubular epithelial cells (HK-2 cells) were determined by Western blotting after transfection with HBx eukaryotic expression vector. The cell proliferation was observed by CCK-8 assay. The cell apoptosis was analyzed by the imaging of HO33342 staining, transmission electron microscopy and flow cytometry with Annexin V/PI double staining. RESULTS: After transfection of the target gene HBx, the expression levels of both p-JAK2 and p-STAT3 were significantly increased. At the same time, the cell proliferation was obviously inhibited, and the apoptotic rate was increased. After incubation with AG490, the JAK2/STAT3 signal pathway was partially blocked, and the cell apoptosis induced by HBx was reduced. CONCLUSION：HBx up-regulates the activation of JAK2/STAT3 signal pathway to induce renal tubular epithelial cell apoptosis, which is possibly involved in the pathogenic mechanism that HBV directly damages nephridial tissue.     

Quercitrin promotes apoptosis of gastric cancer cell line SGC7901 by inhibiting PI3K/AKT signaling pathway

AIM: To investigate whether quercitrin induces apoptosis of gastric cancer cell line SGC7901 by inhibition of PI3K/AKT signaling pathway. METHODS: The human gastric cancer SGC7901 cells were selected as the research object. The cytotoxicity of quercitrin was detected by MTT assay, and IC₅₀ value of quercitrin was calculated. The SGC7901 cells were divided into control group, quercitrin group (incubated with 200 μmol/L quercitrin), insulin-like growth factor-1 (IGF-1) group (incubated with 100 μg/L IGF-1) and quercitrin+IGF-1 group (incubated with 200 μmol/L quercitrin and 100 μg/L IGF-1). After 48 h, the apoptosis of SGC7901 cells was analyzed by flow cytometry, and the protein levels of cleaved caspase-3, p-AKT (Ser473), AKT, p-PI3K (Tyr508) and PI3K were determined by Western blot. RESULTS: The viability of SGC7901 cells was significantly decreased as the concentration of quercitrin increased, starting at 100 μmol/L (P<0.05). The IC₅₀ value of quercitrin for 48 h was 275.40 μmol/L. After treatment with 200 μmol/L quercitrin for 48 h, the apoptosis rate and the protein level of cleaved caspase-3 in quercitrin group were significantly increased (P<0.05), and the phosphorylated levels of AKT and PI3K were significantly decreased compared with control group (P<0.05). Treatment with quercitrin and IGF-1 inhibited the effect of quercitrin on SGC7901 cells compared with quercitrin group. CONCLUSION: Quercitrin may induce apoptosis of gastric cancer cell line SGC7901 by inhibiting the activation of PI3K/AKT signaling pathway.     

Resveratrol induces apoptosis in human ovarian cancer SKOV3 cells via Sirt3-SOD2-ROS pathway

AIM: To investigate whetier resveratrol induces apoptosis of human ovarian cancer SKOV3 cells through Sirt3-SOD2-ROS pathway. METHODS: SKOV3 cells were cultured in vitro and treated with resveratrol at 0, 2.5, 5, 10, 20, 40 and 80 mg/L for 24 h. The inhibitory effect of resveratrol on the viability of SKOV3 cells was measured by MTT assay. SKOV3 cells were randomly divided into blank control group, 10 mg/L resveratrol group, 20 mg/L resveratrol group and 40 mg/L resveratrol group. After 24 h of treatment, Hoechst 33342 staining and confocal microscopy were used to observe the nuclear changes. The protein levels of silent mating type information regulation 2 homolog 3 (Sirt3), superoxide dismutase 2 (SOD2), Bcl-2, Bax and cleaved caspase-3 were determined by Western blot. RESULTS: Treatment with resveratrol at 2.5, 5, 10, 20, 40 and 80 mg/L for 24 h significantly reduced the viability of SKOV3 cells. The observation by confocal microscopy showed that the nucleus of SKOV3 cells was markedly condensed and heavily stained with the increase in the concentration of resveratrol. Compared with blank control group, the red fluorescence intensity of ROS in different concentrations of resveratrol groups was significantly reduced. The results of Western blot showed that the protein levels of Sirt3, SOD2, Bax and cleaved caspase-3 in resveratrol groups were significantly higher than those in control group, while the protein expression of Bcl-2 was significantly lower than that in control group (P<0.05). CONCLUSION: Resveratrol induces apoptosis of SKOV3 cells by regulating Sirt3-SOD2-ROS pathway.     

Effect of IQGAP1 siRNA on biological characteristics of glioma cells by regulating STAT3 signaling pathway

AIM: To investigate the effect of IQGAP1 gene expression knock-down on invasion, migration and immunosuppression of glioma cells and its mechanism. METHODS: Human glioma U251 cells were randomly divided into blank group, negative control group and si-IQGAP1 group. AG490, an inhibitor of STAT3 signaling pathway, was used to treat the cells for 48 h. The cell viability was measured by MTT assay. The protein levels of IQGAP1, vascular endothelial growth factor (VEGF), transforming growth factor-β1 (TGF-β1), STAT3 and p-STAT3 were determined by Western blot. The cell invasion and migration abilities were detected by Transwell assays. RESULTS: The protein expression of IQGAP1 in si-IQGAP1-1 group and si-IQGAP1-2 group was significantly lower than that in blank group (P<0.05). Compared with blank group, the viability, the invasion ability and the migration ability of the cells in si-IQGAP1 group and AG490 group were significantly decreased, while the protein levels of VEGF, TGF-β1 and p-STAT3 were significantly decreased (P<0.05). Compared with AG490 group, the cell viability, invasion ability and migration ability in AG490+si-IQGAP1 group were significantly decreased, and the protein levels of VEGF and TGF-β1 were significantly decreased (P<0.05). CONCLUSION: Silencing of IQGAP1 gene expression reduces the invasion and migration abilities of glioma cells and decreases the protein expression of cellular immunosuppression molecules VEGF and TGF-β1, which is related to down-regulation of STAT3 signaling pathway.     

siRNA targeting TRIM29 gene induces apoptosis of nasopharyngeal carcinoma cells by inhibiting PI3K/AKT signaling pathway

AIM:To investigate the effect of TRIM29 gene expression silencing on the apoptosis and PI3K/AKT signaling pathway in human nasopharyngeal carcinoma 5-8F cells. METHODS:The 5-8F cells were divided into blank group, negative control (NC) group (transfected negative control siRNA) and si-TRIM29 group (transfected TRIM29 specific siRNA). The viability of the 5-8F cells transfected with si-TRIM29 for 0~96 h was measured by CCK-8 assay. The apoptotic rate and the protein levels of TRIM29, cleaved caspase-3, cleaved caspase-9, Bcl-2, Bax, t-AKT and p-AKT in the 5-8F cells transfected with si-TRIM29 for 48 h were determined by flow cytometry and Western blot, respectively. PI3K/AKT signal specific inhibitor LY294002 at 10 μmol/L and si-TRIM29 alone or in combination were treated with the 5-8F cells, and the cells were divided into blank group, LY294002 group and LY294002+si-TRIM29 group. The apoptotic rates in the 3 groups were detected by flow cytometry. RESULTS:The protein expression of TRIM29 in the 5-8F cells transfected with TRIM29 siRNA was significantly lower than that in blank group (P<0.05). Compared with blank group, the cell viability was significantly decreased, the apoptotic rate was significantly increased, the protein levels of cleaved caspase-3, cleaved caspase-9 and Bax were significantly increased, and the protein levels of Bcl-2 and p-AKT were significantly decreased in si-TRIM29 group (P<0.05). The apoptotic rate in LY294002 group was higher than that in blank group, while that in LY294002+si-TRIM29 group was even higher than that in LY294002 group (P<0.05). CONCLUSION:Silencing of TRIM29 gene expression induces apoptosis of nasopharyngeal carcinoma 5-8F cells by inhibiting PI3K/AKT signaling pathway.     

Inhibitory effects of paeonol on keratinocyte viability,cytokines secretion stimulated by IL-17A via STAT3 signaling pathway

AIM To observe the effect of paeonol on interleukin-17A （IL-17A）-induced human keratinocyte viability, cytokine secretion, and related signal transduction pathways. METHODS In vitro HaCaT cells stimulated by IL-17A （200 μg/L） were co-cultured with paeonol （200 mg/L and 100 mg/L） for 24 h. The cell viability was measured by CCK-8 assay. The Th1/Th2/Th17 cytokine （including IL-6, etc.） levels were measured by cytometric bead array assay. The IL-23 level was measured by ELISA. The mRNA expression of IL-23, IL-6, CXCL2, CXCL8, CCL20 and STAT3 was detected by real-time PCR, and Western blot was used to determine the protein levels of STAT3 and ERK1/2. RESULTS Paeonol significantly inhibited IL-17A-induced HaCaT cell viability （P<0.05）, as well as reduced IL-6 level. Meanwhile, paeonol decreased mRNA levels of IL-23, CXCL2, CXCL8, and CCL20. Paeonol also inhibited the expression of STAT3 at mRNA and protein levels. However, no significant effect of paeonol on ERK1/2 protein expression was observed. CONCLUSION Paeonol inhibits HaCaT cell viability and cytokine secretion induced by IL-17A, and its mechanism might be related to STAT3 singaling pathway.     

Effect of HDAC1 silencing on apoptosis of squamous cell carcinoma of skin via regulating STAT3 signaling pathway

AIM: To investigate the effect of histone deacetylase 1 (HDAC1) silencing on apoptosis of squamous cell carcinoma of skin. METHODS: Skin squamous cell carcinoma A431 cells were transfected with HDAC1 small interfering RNA (HDAC1 siRNA) or small interfering RNA negative control (siRNA NC). The expression levels of HDAC1 in transfected cells were detected by RT-PCR and Western blot. The cell viability was measured by MTT assay, and the apoptosis was analyzed by flow cytometry. The protein levels of STAT3, p-STAT3 and cleaved caspase-3 were determined by Western blot. The inhibitor of STAT3 signaling pathway was used to treat the A431 cells transfected with HDAC1 siRNA. The cell viability was detected by MTT assay, the apoptosis was analyzed by flow cytometry, and the protein levels of STAT3, p-STAT3 and cleaved caspase-3 were determined by Western blot. RESULTS: HDAC1 siRNA inhibited the expression of HDAC1 at mRNA and protein levels in the A431 cells. After interfering with the expression of HDAC1, the cell viability and the protein level of p-STAT3 in the cells decreased, while the apoptotic rate and the protein level of cleaved caspase-3 in the cells were increased. After treatment with the inhibitor of STAT3 pathway, the viability of A431 cells transfected with siRNA and the protein level of p-STAT3 decreased, while the apoptotic rate and the protein le-vel of cleaved caspase-3 in the cells were increased. CONCLUSION: Interference with HDAC1 expression may regulate the STAT3 signaling pathway to inhibit the viability of skin squamous cell carcinoma cells, thus promoting the apoptosis of squamous cell carcinoma of skin.     

Honokiol induces autophagy by inhibiting mTOR signaling pathway in lung cancer A549 cells

AIM:To investigate whether honokiol induces the autophagy of human lung cancer A549 cells and to explore its mechanism. METHODS:The A549 cells were cultured in vitro, and treated with honokiol at different concentrations (0, 10, 20, 40, 60 and 80 μmol/L) for 48 h. MTT assay was performed to analyze the effect of honokiol on the viability of the A549 cells. The formation of autophagosome was observed by staining with acridine orange under fluorescence microscope. The protein levels of autophagy-associated protein LC3, mTOR and p-mTOR in the A549 cells treated with honokiol, or combined with autophagy inhibitor 3-methyladenine (3-MA) were determined by Western blot. RESULTS:Honokiol significantly inhibited the viability of A549 cells in a dose-dependent manner (P<0.05). The number of the intracellular acidic autophageic vacuoles with bright red fluorescence was significantly increased after honokiol treatment. The protein level of LC3-Ⅱ/LC3-I in the A549 cells was significantly enhanced after honokiol (40 μmol/L) treatment, and the ratio of LC3-Ⅱ/LC3-I was significantly decreased by treatment with 3-MA (P<0.05). Furthermore, treatment with honokiol (40 μmol/L) in the A549 cells for 48 h also resulted in significant down-regulation of phosphorylated form of mTOR (P<0.01), while the total protein level was not changed. CONCLUSION:Honokiol significantly inhibits the growth of lung cancer A549 cells and induces the autophagy, which may be correlated with inhibition of mTOR signaling pathway.