β-elemene reverses hepatocyte growth factor-induced resistance to gefitinib in PC-9 lung cancer cells via c-Met pathway

AIM: To investigate the effect of β-elemene on reversing hepatocyte growth factor (HGF)-induced resistance to gefitinib in PC-9 cells, and to explore its possible mechanisms. METHODS: The gefitinib-resistant PC-9 cells induced by HGF were treated with β-elemene or/and gefitinib. The cell activity was measured by MTT assay. The effect of β-elemene on the invasion ability in HGF-induced resistance to gefitinib in PC-9 cells was detected by Transwell migration assay. The protein levels of p-Met, c-Met, p-AKT and AKT in PC-9 cells of each group were determined by Western blot. RESULTS: The results of MTT assay showed that the cell activity of PC-9 cells was significantly inhibited by β-elemene (P<0.05). IC₅₀ of β-elemene for PC-9 cells was 169.31 mg/L. IC₅₀ of gefitinib for PC-9 cells was 0.30 μmol/L. Exogenously adding recombinant HGF induced significantly resistance to gefitinib in PC-9 cells. Moreover, SU11274 (an inhibitor of c-Met) significantly decreased the viability of the cells exposed to HGF and gefitinib (P<0.05). Combined treatment with β-elemene and gefitinib in the presence of HGF (50 μg/L) significantly decreased the viability of PC-9 cells as compared with the PC-9 cells treated with gefitinib alone in the presence of HGF (P<0.05), so did the result of the cell migration. The protein levels of p-Met and p-AKT were significantly up-regulated by HGF, while the protein levels of p-Met and p-AKT were markedly down-regulated in the cells treated with β-elemene and gefitinib compared with gefitinib alone in the presence of HGF. CONCLUSION: β-elemene reverses HGF-induced resistance to gefitinib in lung cancer PC-9 cells, likely due to the inhibition of HGF-induced activation of c-Met and its down streams signaling pathways (P<0.01).     

Chutan-Jiedu decoction reverses resistance of lung cancer to gefitinib by processing EMT

AIM: To investigate the mechanism of Chutan-Jiedu decoction (CJD) reversing the resistance of lung cancer to gefitinib via epithelial-mesenchymal transition (EMT) pathway.METHODS: BALB/c nude mice (n=60) were selected to establish lung cancer xenograft model with human lung adenocarcinoma drug-resistant cell line H1975, which were randomly divided into 6 groups (10 mice per group):model group, gefitinib (0.04 g/kg) group, low-dose (13.52 g/kg) CJD group, middle-dose (27.04 g/kg) CJD group, high-dose (54.08 g/kg) CJD group, and combined medication group (27.04 g/kg CJD+0.04 g/kg gefitinib). The mice in each group were treated for 2 weeks before the tumor size and tumor weight were detected for the calculation of the tumor inhibitory rate. The mRNA and protein expression levels of E-cadherin, Snail and vimentin were determined by immunohistochemistry, Western blot and real-time PCR.RESULTS: Compared with model group and gefitinib group, the tumor size and the tumor weight in middle-dose CJD group, high-dose CJD group and combined medication group were decreased significantly (P<0.05). The results of immunohistochemistry, Western blot and real-time PCR showed that the expression of E-cadherin at mRNA and protein levels was increased significantly, while the expression of Snail and vimentin at mRNA and protein levels was decreased significantly (P<0.05).CONCLUSION: The growth of lung adenocarcinoma H1975 xenografts in nude mice is inhibited by CJD. In addition, the resistance of lung cancer to gefitinib is reversed. The mechanism may be related to the regulation of EMT-related protein expression.     

miR-221 changes resistance of lung cancer cells to gefitinib by regulating PTEN

AIM: To explore the effect of microRNA-221 (miR-221) on resistance of lung cancer cells to gefitinib, and to investigate its related mechanism. METHODS: RT-qPCR was used to detect the levels of miR-221 expression between gefitinib-sensitive cell line PC9 and gefitinib-resistant cell line PC9/GR. The PC9/GR cells were transfected with miR-221 inhibitor by Lipofectamine 2000. The drug sensitivity of these cells to gefitinib was determined by CCK-8 assay. The protein expression level of phosphatase and tensin homologue deleted on chromosome ten (PTEN) was determined by Western blot. The 3'-UTR of PTEN was cloned into luciferase reporter vector and its luciferase activity was detected to verify whether miR-221 targets PTEN. RESULTS: The expression level of miR-221 in the PC9/GR cells was significantly higher than that in the PC9 cells (P<0.05). The protein expression level of PTEN in the PC9/GR cells was lower than that in the PC9 cells (P<0.05). The IC₅₀ of gefitinib was significantly reduced in the PC9/GR cells after transfection with miR-221 inhibitor (P<0.05). The protein expression level of PTEN in the cells transfected with miR-221 inhibitor was increased as compared with control group and blank group (P<0.05). Inhibition of miR-221 expression enhanced the enzymatic activity of luciferase reporter vector of PTEN. CONCLUSION: miR-221 enhances the resistance of lung cancer cells to gefitinib by down-regulating the protein expression of PTEN.     

Reverse effect of shikonin on epithelial-mesenchymal transition induced by HGF in lung cancer cells

AIM:To investigate the effects of shikonin on the migration, invasion and epithelial-mesenchymal transition (EMT) in human non-small-cell lung cancer PC9 cells induced by hepatocyte growth factor (HGF). METHODS:The effect of shikonin on the viability of PC9 cells was measured by MTT assay. The cell migration and invasion abilities were analyzed by wound healing assay and Transwell method, respectively. The protein expression levels of E-cadherin, N-cadherin and vimentin in the PC9 cells were determined by Western blot. RESULTS:The viability of PC9 cells was significantly inhibited by shikonin in a dose-dependent manner (P<0.01), with IC₅₀ at 9.364 μmol/L. HGF significantly promoted the abilities of migration and invasion, and induced EMT in the PC9 cells. Shikonin significantly inhibited HGF-induced migration and invasion in the PC9 cells. The expression of E-cadherin was significantly down-regulated and the expression of N-cadherin and vimentin was significantly up-regulated in the presence of HGF (50 μg/L). However, shikonin reversed HGF-induced EMT, as indicated by up-regulation of E-cadherin and down-regulation of N-cadherin and vimentin (P<0.01). CONCLUSION:Shikonin reverses HGF-induced EMT in lung cancer PC9 cells.     

Let-7a-3p inhibits activity of cancer stem cells in human lung cancer A549 cells by targeting IGF1R

AIM:To study the effect of let-7a-3p on the activity of cancer stem cells in human lung cancer A549 cells and its molecular biological mechanism. METHODS:The exepression levels of let-7a-3p in lung cancer cell lines A549, NCI-H1299, SPC-A1, H1650 and HCC-827, and human normal bronchial epithilial cell line BEAS-2B were compared by RT-qPCR. The lung cancer A549 cells were transfected with let-7a-3p mimic and negative control mimic, as let-7a-3p group and negative control group, respectively, and non-transfected control group was also set up. The content of let-7a-3p in each group was detected by RT-qPCR. Tumor sphere formation assay was used to detect the tumor sphere formation ability in 3 groups of the cancer stem cells. The proportion of cancer stem cells was detected by flow cytometry. The protein levels of NANOG, OCT4 and insulin-like growth factor 1 receptor (IGF1R) were determined by Western blot. The target gene of let-7a-3p was predicted by the bioinformatic method. The relationship between let-7a-3p and IGF1R was analyzed by double luciferase assay. Western blot was used to detect whether IGF1R over-expression antagonized the inhibitory effect of let-7a-3p on the activity of cancer stem cells. A subcutaneous transplantation tumor model was also established and the effect of let-7a-3p in vivo was observed. RESULTS:The expression level of let-7a-3p in the lung cancer cell lines was significantly lower than that in the normal bronchial epithelial cell line (P<0.01). The expression level of let-7a-3p in the A549 cells of let-7a-3p group was significantly up-regulated compared with non-transfected group (P<0.01). The number of tumor spheres in let-7a-3p group was significantly lower than that in non-transfected group. The percentage of CD133⁺ cells in let-7a-3p group was significantly lower than that in non-transfected group (P<0.01). The protein expression of NANOG and OCT4 in let-7a-3p group was significantly lower than that in non-transfected group (P<0.01). Bioinformatic prediction showed that let-7a-3p complementarily matched the 3'-UTR of IGF1R, and IGF1R might be the target gene of let-7a-3p. Luciferase assay confirmed that IGF1R was the direct downstream target gene of let-7a-3p. The protein expression of IGF1R in let-7a-3p group was significantly decreased (P<0.01). Subcutaneously transplantated tumor in let-7a-3p group was significantly smaller than that in non-transfected group. CONCLUSION:Let-7a-3p may affect the expression of lung cancer stem cell-related proteins and inhibit the potential of lung cancer stem cells by down-regulating its downstream target gene IGF1R.     

Pantoprazole sodium inhibits epithelial-mesenchymal transition and cisplatin resistance in lung cancer cells and underlying mechanism

AIM: To explore the inhibitory effects of pantoprazole sodium on epithelial-mesenchymal transition and cisplatin resistance in lung cancer cells and the underlying mechanism.METHODS: Using MTT method, wound healing assay, Transwell experiment, Western blot, the differences of morphology, invasion ability, migration ability, drug sensitivity and protein expression between A549/DDP cells and A549 cells were determined. The effect of pantoprazole sodium on morphology, invasion ability, migration ability, drug sensitivity and protein expression in A549/DDP cells were also observed.RESULTS: Compared with A549 cells, A549/DDP cells had higher invasion and migration abilities, and lower drug sensitivity, exhibited mesenchymal phenotype and activated c-Met/AKT/mTOR pathway. Pantoprazole sodium inhibited the abilities of invasion and migration, and reversed the mesenchymal phenotype, drug resistance and the c-Met/AKT/mTOR pathway activation in A549/DDP cells. Treatment with c-Met inhibitor SU11274, PI3K inhibitor LY294002 and mTOR inhibitor rapamycin had the same effects on A549/DDP cells as that of pantoprazole sodium.CONCLUSION: Pantoprazole sodium inhibits invasion, migration, epithelial-mesenchymal transition and cisplatin resistance in lung cancer cells by down-regulating c-Met/AKT/mTOR pathways.     

Reversing effect of naringin on cisplatin resistance in human lung cancer A549/DDP cells

AIM: To investigate the effect of naringin (NRG) on cisplatin (DDP) resistance in human lung cancer A549/DDP cells and its possible mechanism. METHODS: A549/DDP cells were cultured in vitro and treated with NRG and/or DDP at different concentrations for 24 h, and then the cell viability were measured by CCK-8 assay. The combination index (CI) of NRG and DDP were analyzed by Chou-Talalay method. The apoptosis rate was analyzed by flow cytometry. Western blot was performed to detect the protein levels of P-glycoprotein (P-gp), multidrug resistance-associated protein 1 (MRP1), p-Akt, CXC chemokine receptor 4 (CXCR4), cleaved caspase-3, Bcl-2 and Bax.RESULTS: The protein levels of P-gp, MRP1, p-Akt and CXCR4 in the A549/DDP cells were higher than those in the A549 cells (P<0.05). The cell viability was remarkably reduced in a dose-dependent manner when A549/DDP cells were exposed to NRG and/or DDP (P<0.05), and the IC₅₀ values of NRG and DDP were 36.92 μmol/L and 129.77 μmol/L, respectively. When the inhibition rate exceeded 15%, NRG in combination with DDP produced a synergistic effect (CI<1). Combination treatment with NRG and DDP significantly induced apoptosis (P<0.05), up-regulated the protein levels of cleaved caspase-3 and Bax, and down-regulated the protein level of Bcl-2 (P<0.05). Meanwhile, NRG remarkably down-regulated the protein levels of P-gp, MRP1, p-Akt and CXCR4 in a dose-dependent manner (P<0.05). CONCLUSION: NRG may enhance the sensibility of A549/DDP cells to DDP most likely via up-regulating the protein level of Bax and down-regulating the protein levels of Bcl-2, P-gp, MRP1, p-Akt and CXCR4.     

Reversal effect of shikonin on cisplatin resistance of ovarian cancer SKOV3/DDP cells

AIM:To explore the reversal effect of shikonin on cisplatin resistance of ovarian cancer SKOV3/DDP cells and its potential mechanism. METHODS:The proper conditions of treatment with shikonin and cisplatin were determined by CCK-8 assay. The cell cycle and apoptotic rate were analyzed by flow cytometry. The protein levels of cell cycle-and apoptotic-related molecules, such as cyclin D1, cyclin-dependent kinases 2 (CDK2), P18, p-Rb, Bcl-2, Bax and cleaved caspase-3, were determined by Western blot. RESULTS:The results of CCK-8 assay showed that compared with cisplatin group, combined treatment with shikonin and cisplatin had a better inhibitory effect on the growth of cisplatin-resistant SKOV3/DDP cells. The cell cycle G₁/S transition was inhibited, while early apoptotic rate was increased after combined use of shikonin and cisplatin. The results of Western blot showed that compared with cisplatin group, the cells in combination group had lower protein levels of cyclin D1, CDK2, p-Rb and Bcl-2, accompanied with higher protein levels of P18, Bax and cleaved caspase-3. CONCLUSION:Shikonin reverses the cisplatin resistance of ovarian cancer SKOV3/DDP cells. The mechanism may be related to the regulation of cell cycle-and apoptotic-related molecules, and further inhibition of cell viability and promotion of cell apoptosis.     

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.     

Effect of luteolin on TGF-β1-induced epithelial-mesenchymal transition in lung cancer A549 cells

AIM:To investigate the effects of luteolin on the invasion and epithelial-mesenchymal transition (EMT) induced by transforming growth factor-β1 (TGF-β1) in lung cancer A549 cells. METHODS:The effect of luteolin at 5, 10, 20, 40, 80 and 160 μmol/L on the viability of A549 cells was measured by MTT assay. The invasion ability was analyzed by Transwell method. The morphological changes of the A549 cells were observed under microscope.The protein expression of E-cadherin and vimentin in the A549 cells were determined by Western blot. RESULTS:The viability of the A549 cells was significantly inhibited by luteolin in a dose-time dependent manner (P<0.05). The IC₅₀ of luteolin for the A549 cells (24 h) was 68.79 μmol/L, while that (48 h) was 47.86 μmol/L. TGF-β1 induced morphological alteration of the A549 cells from epithelial to mesenchymal forms. Luteolin significantly inhibited TGF-β1-induced invasion of the A549 cells (P<0.01). The protein expression of E-cadherin was significantly down-regulated and the protein expression of vimentin was significantly up-regulated in the presence of TGF-β1 at 5 μg/L (P<0.01). However, luteolin reversed TGF-β1-induced EMT, up-regulation of E-cadherin and down-regulation of vimentin (P<0.01). CONCLUSION:Lu-teolin reverses TGF-β1-induced EMT in the lung cancer A549 cells.     

Tripchlorolide activates p-ERK and induces autophagy in lung cancer A549 cells

AIM: To investigate the effects of tripchlorolide (TP) on proliferation and autophagy of human lung cancer A549 cells, and explore its mechanism. METHODS: MTT assay was performed to analyze the effect of TP on the viability of human lung cancer A549 cells. The A549 cells were treated with TP, and their autophagy was observed under the fluorescence microscope through acridine orange staining. Green fluorescence spots were observed by fluorescence microscopy through GFP-LC3 plasmid transfection experiment. The levels of LC3 and p-ERK in the A549 cells after TP treatment were determined by Western blot. RESULTS: The viability of human lung cancer A549 cells was significantly inhibited by TP in a dose-time dependent manner (P<0.05). The number of the intracellular acidic follicles dyed with bright red fluorescence was significantly increased after TP treatment in A549 cells. The number of green dot-like congregate autophagosomes in cell cytoplasm was significantly increased after TP treatment in the A549 cells transfected with GFP-LC3 plasmid, while the normal treatment only induced a few cells with autophagosome formation. At the same time, we did not observe the dot-like congregate autophagosomes after TP treatment in the A549 cells transfected with GFP-control plasmid. Compared with control group, the expression of LC3-Ⅱ protein was up-regulated in A549 cells after TP treatment (P<0.01). Furthermore, treatment with TP in A549 cells for 48 h also led to a significant upregulation of phosphorylated form of ERK (P<0.01). In contrast, no significant change in the levels of total ERK protein was observed. Compared with 100 nmol/L TP group, TP+3-MA group down-regulated the protein levels of LC3-Ⅱ (P<0.01) and p-ERK (P<0.01) in the A549 cells. CONCLUSION: TP significantly inhibits the growth of A549 lung cancer cells and induces the autophagy, which may be correlated with upregulation of p-ERK protein.     

Relationship of expression of extracellular matrix metalloproteinase inducer and hepatocyte growth factor with lymphoid metastasis and prognosis in non-small-cell lung carcinoma

AIM: To investigate the expression of extracellular matrix metalloproteinase inducer (EMMPRIN) and hepatocyte growth factor (HGF) in non-small-cell lung carcinoma (NSCLC) and their relationship with lymphoid metastasis and prognosis.METHODS: Expression of EMMPRIN and HGF in 77 cases of patients with NSCLC was detected immunohistochemically.The relationship of expression of EMMPRIN and HGF with tumor size,smoking,histological type,differentiation,lymphoid metastasis,clinical stage,and prognosis was analyzed.RESULTS: The expressive rates of EMMPRIN and HGF were 68% and 44%,respectively.The expressions of EMMPRIN and HGF were associated positively with lymphoid metastasis (r=0.371 and 0.339，P＜0.01),and inversely with survival time (P＜0.01).No relationship was found between the expression of EMMPRIN,HGF and smoking,tumor size,histological type and differentiation (P＞0.05).The expression of EMMPRIN was associated with the expression of HGF in NSCLC.CONCLUSION: The expression of EMMPRIN and HGF is associated with lymphoid metastasis and prognosis in NSCLC.Overexpression of EMMPRIN and HGF implies infavourable prognosis in NSCLC.     

miR-125a-5p reverses cisplatin resistance of non-small-cell lung cancer A549/DDP cells by targeting LIMK1

AIM:To explore the effect of microRNA-125a-5p (miR-125a-5p) on cisplatin (DDP) resistance of non-small-cell lung cancer A549/DDP cells and its related mechanisms. METHODS:The expression levels of miR-125a-5p and LIM kinase 1 (LIMK1) in non-small-cell lung cancer tissues, A549 cells and A549/DDP cells were detected by RT-qPCR. The A549/DDP cell viability, apoptotic rate and expression of drug resistance-related proteins after over-expression or knockdown of miR-125a-5p and/or LIMK1 expression were detected by MTT assay, flow cytometry and Western blot, respectively. The targeting relationship between miR-125a-5p and LIMK1 was verified by TargetScan online prediction and dual-luciferase reporter system. The cell viability, apoptotic rate and expression of drug resistance-related proteins after co-expression of miR-125a-5p and LIMK1 were also determined. RESULTS:The expression level of miR-125a-5p was down-regulated and LIMK1 expression was up-regulated in non-small-cell lung cancer tissues and cell lines (P<0.05). The results of dual-luciferase assay indicated that miR-125a-5p negatively regulated the expression of LIMK1. The expression of drug resistance-related proteins and the viability of A549/DDP cells were inhibited after over-expression of miR-125a-5p or knockdown of LIMK1, while the apoptosis was enhanced. Over-expression of LIMK1 attenuated the inhibitory effect of miR-125a-5p on A549/DDP cell viability and drug resistance-related protein expression (P<0.05). CONCLUSION:miR-125a-5p reverses the resistance of A549/DDP cells to DDP by inhibiting the expression of LIMK1 and drug resistance-related proteins.     

Imperatorin increased sensitivity of lung cancer CD133+ cell subsets to gefitinib by down-regulating c-met expression

AIM: To investigate the role of imperatorin in reversing the resistance of the PC9 CD133⁺ cell subsets to gefitinib. METHODS: MTT assay was performed to evaluate the viability of PC9 cells treated with imperatorin and gefitinib. The expression of c-met, activation of caspases and phosphorylation of epidermal growth factor receptor (EGFR), PI3K and AKT in the PC9 cells treated with imperatorin and gefitinib were determined by Western blot. The percentage of CD133⁺ cell subsets population and the apoptotic rate of the PC9 cells treated with imperatorin and gefitinib were analyzed by flow cytometry. RESULTS: The sensitivity of the PC9 CD133⁺ cell subsets to gefitinib was significantly lower than that of the PC9 CD133^- cell subsets. Treatment with gefitinib alone significantly inhibited the protein levels of EGFR/PI3K/AKT in the PC9 CD133^- cell subsets but not the PC9 CD133⁺ cell subsets. Treatment with gefitinib alone increased the percentage of CD133⁺ cell subsets population in the PC9 cells. However, combination of gefitinib with imperatorin significantly inhibited the enrichment of CD133⁺ cell subsets population. Imperatorin down-regulated c-met expression, suggesting the c-met was the target of imperatorin in the PC9 CD133⁺ cell subsets. The results of MTT assay, Western blot analysis and flow cytometry indicated that imperatorin increased the gefitinib induced inhibition of PI3K/AKT protein levels by down-regulating the expression of c-met, which subsequently induced the cleavage of caspases and apoptosis in the PC9 CD133⁺ cell subsets.CONCLUSION: Imperatorin increases the sensitivity of lung cancer CD133⁺ cell subsets to gefitinib by down-regulating the expression of c-met, and the synergistic anti-tumor effect exists between imperatorin and gefitinib.     

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.     

A 3D cell culture system to study epithelial-mesenchymal transition and drug resistance of lung cancer

AIM To explore the molecular mechanism of transforming growth factor-β1 （TGF-β1）-induced epithelial-mesenchymal transition （EMT） and cisplatin resistance in three-dimensionally cultured lung cancer cells. METHODS Under three-dimensional culture condition, the morphological changes and protein expression changes of human non-small-cell lung cancer 95D cells were observed by inversed fluorescence microscopy, scanning electron microscopy, laser scanning confocal microscopy and Western blot before or after TGF-β1 stimulation. The cisplatin sensitivity was determined by MTT assay. RESULTS Under the three-dimensional culture condition, the structure of 95D cell spheroids after TGF-β1 stimulation collapsed, the cells were dispersed and migrating, and the spheroids merged with each other. The results of laser confocal microscopy showed that E-cadherin protein expression in the 95D cells did not changed after TGF-β1 stimulation, and the protein expression of N-cadherin and vimentin was significantly up-regulated. The results of Western blot showed that the expression of E-cadherin was down-regulated after TGF-β1 stimulation, and the protein levels of N-cadherin, vimentin, phosphorylated AKT and phosphorylated mTOR were up-regulated. LY294002 and rapamycin reversed TGF-β1-induced expression of the above proteins. The results of MTT assay showed that TGF-β1 reduced the sensitivity of three-dimensionally cultured 95D cells to cisplatin, while LY294002 and rapamycin reversed the cisplatin resistance of the 95D cells stimulated by TGF-β1. CONCLUSION TGF-β1 induces the EMT and cisplatin resistance of three-dimensionally cultured lung cancer cells through the activation of PI3K/AKT/mTOR signaling pathway.     

Bone marrow mesenchymal stem cells are induced to differentiate into cardiomyocytes by hepatocyte growth factor in vitro

AIM: To explore a new method of hepatocyte growth factor (HGF) inducing bone marrow mesenchymal stem cells (MSC) to differentiate into cardiomyocytes. METHODS: Bone marrow MSC was cultured with DMEM media (10% fetal calf serum) 4-6 passages, and induced by HGF (10 μg/L) for 30 d. Automatical beating of the differentiated cells was observed daily with transverse microscopy, or under condition of 0.1% isoproterenol or cal-cium-deprived incubation. Specific cardiac myosin in the cells was indentified by immunochemistry. RESULTS: At 14-20 d of differentiation, bone marrow mesenchymal stem cells formed clones, in 10%-50% of which spontaneous beating cell-mass had come to continuously exist. Isoproterenol increased the beating rate and calcium-deprived media inhibited the beating. The cells were identified to be cardiomyocytes by expression of cardiac myosin heavy chain. CONCLUSION: HGF may induce bone marrow mesenchymal stem cells into cardiomyocytes with high efficiency, but the differentiating pathway of stem cells remains to be further studied.     

Effect of PDK1 on biological characteristics of lung cancer A549 cells

AIM: To investigate the effects of 3-phosphoinositide-dependent protein-1 (PDK1) on the biological characteristics of non-small-cell lung cancer cell line A549 and the underlying mechanisms.METHODS: The expression levels of PDK1 in lung normal epithelial cell line BEAS-2B and different lung cancer cell lines H460, SPCA1 and A549 were determined by Western blot and real-time PCR. Small interfering RNA was used to down-regulated PDK1 expression in the A549 cells, and then cell viability and apoptosis were measured by CCK-8 assay and flow cytometry, respectively. The expression of cell cycle-and apoptosis-related molecules at protein level and the activation of Akt/FoxO1 pathway were measured by Western blot. Insulin-like growth factor-1 (IGF-1, one of the most potent Akt activators) was used to evaluate the interaction between PDK1 and Akt/FoxO1 pathway.RESULTS: Compared with lung normal epithelial cell line BEAS-2B, PDK1 expression in the lung cancer cell lines was obviously increased (P<0.05). Knockdown of PDK1 suppressed cell viability and cell cycle, but promoted the apoptosis of the A549 cells. The results of Western blot showed that the protein levels of cyclin D1, CDK4, p-Rb, Bcl-2, p-Akt and cytoplasmic p-FoxO1 were significantly decreased after knockdown of PDK1, with increases in the protein levels of P27, cleaved caspase-3 and nuclear FoxO1. Pre-incubation with IGF-1 partly reversed the effect of PDK1 knockdown on Akt/FoxO1 pathway and increased the viability of A549 cells.CONCLUSION: In human non-small-cell lung cancer A549 cells, knockdown of PDK1 suppresses cell viability and promotes cell apoptosis by regulating the expression of cell cycle-and apoptosis-related molecules via Akt/FoxO1 pathway, suggesting that PDK1 may be a potential target for diagnosis and theatment of lung cancer.     

miR-221 promotes proliferation of lung cancer A549 cells by down-regulating PTEN

AIM: To explore the effect of microRNA-221 (miR-221) on the proliferation of lung cancer A549 cells, and to investigate its mechanism. METHODS: The A549 cells were transfected with miR-221 mimics by Lipofectamine 2000. The expression of miR-221 was detected by RT-qPCR. The expression of PTEN at mRNA and protein le-vels was detected by RT-qPCR and Western blot, respectively. The cell proliferation was examined by CCK-8 assay and colony formation assay. The 3'-UTR of PTEN was cloned into luciferase reporter vector and its enzymatic activity was detected to verify whether miR-221 targeted to PTEN. RESULTS: The expression level of miR-221 in the A549 cells was significantly increased after transfection with miR-221 mimics as compared with negative control group and blank group (P<0.01). The mRNA and protein levels of PTEN were significantly down-regulated compared with control group and blank group (P<0.05). In addition, miR-221 over-expression significantly promoted the proliferation of A549 cells (P<0.05). Moreover, miR-221 inhibited the enzymatic activity of luciferase reporter vector of PTEN. CONCLUSION: Over-expression of miR-221 significantly promotes the proliferation ability of human lung cancer A549 cells by down-regulation of PTEN.