Inhibitory effect of liposomes survivin antisense oligonucleotide on human hepatic carcinoma transplanted subcutaneously in nude mice

AIM: To explore the effects of liposomes survivin antisense oligonucleotides (ASODN) on growth of human hepatic carcinoma transplanted subcutaneously in nude mice. METHODS: Nude mouse model of human hepatic cancer was established by transplantation of hepatic cancer cell line SMMC-7721/ADM subcutaneously. Models were divided randomly into six groups: control group, liposome group, sense oligonucleotide (SODN) group, 200 μg/L, 400 μg/L and 600 μg/L ASODN groups. Different treatments were given respectively. Weight and volume of subcutaneous tumors were measured, and tumor growth inhibitory rate was calculated. Morphological changes of transplanted tumor cells were observed under light microscope. The expression of Survivin was detected by immunohistochemistry. RESULTS: The growth of tumors was significantly inhibits in all ASODN groups compared with control, liposome and SODN groups (P<0.05). Volume of subcutaneous tumors decreased in a time-dependent and dosage-dependent manner (P<0.5). CONCLUSION: Survivin ASODN inhibits the growth of human hepatic carcinoma in nude mice.     

Apoptosis of implanted tumor of human primary gastric cancer cells in nude mice induced by resveratrol

AIM: To investigate the molecular mechanism of the apoptosis of implanted tumor of human primary gastric cancer cells in nude mice induced by resveratrol. METHODS: Human primary gastric cancer cells were planted into nude mice to establish the cancer model. Resveratrol at different doses were injected near the carcinoma on the nude mice. After treatment, transmission electron microscope and TUNEL staining method were used to detect the apoptosis of implanted tumor cells. Immunohistochemical staining and RT-PCR were used to detect the expression of apoptosis-related genes bcl-2 and bax in implanted tumor. RESULTS: Resveratrol significantly inhibited carcinoma growth when it was injected near the carcinoma. The apoptotic cells in implanted tumor induced by resveratrol were detected by transmission electron microscope and TUNEL staining, immunohistochemical staining and RT-PCR showed resveratrol inhibited bcl-2 expression and increased bax expression in human primary gastric cancer cells. CONCLUSION: Resveratrol inhibits implanted tumor of human primary gastric cancer cells in nude mice through inducing apoptosis. This apoptosis may be mediated by down-regulation of bcl-2 expression and up-regulation of bax expression.     

The anticancer activity of genistein on implanted tumor of human primary gastric carcinoma cells in nude mice

AIM: To investigate the apoptosis of implanted tumor of primary human gastric cancer cells in nude mice induced by genistein and the relation between this apoptosis and expression of bcl-2 and bax.METHODS: Establishing a transplanted tumor model by injecting human primary gastric cancer cells into subcutaneous tissue of nude mice.The different doses of genistein (0.5mg/kg,1mg/kg and 1.5 mg/kg ) were directly injected beside tumor body respectively,for six times at an interval of two days.Then changes of tumor volume were measured continuously and tumor inhibition rate of each group was calculated.We observed the morphologic alteration by electron microscope,measured the apoptotic rate by TUNEL staining method,detected the expression of apoptosis-regulated gene bcl-2 and bax by immunohistochemical staining and RT-PCR.RESULTS: Genistein could significantly inhibit carcinoma growth when it was injected near the carcinoma.Genistein induced implanted tumors cells to undergo apoptosis with apoptotic characteristics by transmission electron microscope.The apoptosis index of above three groups was increased progressively.Positive rate of Bcl-2 protein of above three groups was decreased progressively and positive rate of Bax protein of above three groups was increased progressively by immunohistochemical staining.The density of bcl-2 mRNA decreased progressively and the density of bax mRNA increased progressively with elongation of time by RT-PCR.CONCLUSION: Genistein is able to induce the apoptosis of transplanted tumor cells.This apoptosis may be mediated by down-regulating bcl-2 and up-regulating bax mRNA and its protein.     

Inhibitory effect of ampelopsin combined with mitomycin on proliferation of gastric carcinoma cells

AIM: To investigate the synergistic effects of ampelopsin (AMP) and a chemotherapeutic drug mitomycin (MMC) on the proliferation of gastric cancer cell line SGC-7901.METHODS: SGC-7901 cells were cultured in vitro and divided into 4 groups: control group, AMP group, MMC group and AMP+MMC group. Cell proliferation was measured by MTT method. The apoptotic index was examined by flow cytometry. The expression of apoptotic proteins, Bcl-2 and survivin, was detected by Western blotting.RESULTS: AMP at the concentrations ranging from 2.2 mg/L to 14.84 mg/L exerted inhibitory effect on the growth of SGC-7901 cells. Cell proliferation in AMP (14.84 mg/L) group was inhibitory by (60.85±1.13) %, significantly higher than that in control group (P<0.05). The inhibitory rates of cell proliferation varied from (17.40±0.30) % to (72.23±1.36) % when the concentrations of MMC increased from 1×10^-3 g/L to 1×10^-2 g/L. AMP combined with MMC showed a synergistic effect on the growth of SGC-7901 cells. The inhibitory rates of cell proliferation varied from (21.83±2.50) % to (46.70±1.45) % when the concentrations of MMC increased from 1×10^-3g/L to 5×10^-3g/L. The inhibitory effect of AMP plus MMC was higher than that of MMC or AMP alone. The protein levels of Bcl-2 and survivin were inhibited in AMP group, MMC group and AMP+MMC group, and were significantly lower in AMP+MMC group than those in AMP group or MMC group.CONCLUSION: AMP enhances the inhibitory effect of MMC on the growth of SGC-7901 cells. The mechanism is related to the inhibition of apoptotic protein expression.     

Dickkopf-1 silencing inhibits invasion and epithelial-mesenchymal transition in gastric carcinoma cells by down-regulating β-catenin

AIM: To explore the expression of Dickkopf-1 (DKK1) in human gastric carcinoma cells, and the influences of DKK1 gene silencing on cell invasion. METHODS: The levels of DKK1 in the human gastric mucosa cell line GES-1 and gastric carcinoma cell lines MKN-45 and SGC-7901 were detected by real-time PCR and Western blot. DKK1 gene was silenced by RNA interference, which was verified by real-time PCR, Western blot and ELISA. The cell invasion ability was determined by Transwell assay, and the cell proliferation was inhibited by mitomycin C. The levels of E-cadherin, N-cadherin, vimentin and β-catenin were determined by real-time PCR and Western blot. RESULTS: The expression of DKK1 was significantly higher in MKN-45 cells and SGC-7901 cells than that in GES-1 cells, indicating that DKK1 expression was obviously increased in gastric carcinoma cells. After successful silencing of DKK1 gene in the MKN-45 cells and SGC-7901 cells, the cell invasion ability was markedly decreased in a time-dependent pattern with increased expression of E-cadherin and decreased expression of N-cadherin and vimentin, indicating that DKK1 silencing dramatically inhibited gastric carcinoma cell invasion and epithelial-mesenchymal transition (EMT). The introduction of exogenous recombinant DKK1 (rDKK1) demonstrated the promoting effect of DKK1 on gastric carcinoma cell invasion and EMT. In addition, the inhibitory effects of DKK1 silencing on gastric carcinoma cell invasion and EMT were fulfilled by down-regulating β-catenin. CONCLUSION: The expression of DKK1 is significantly increased in human gastric carcinoma cells. Silencing of DKK1 markedly inhibits gastric carcinoma cell invasion and EMT by down-regulating β-catenin.     

Effect of ruthenium-polypyridine complex on apoptosis of gastric cancer SGC-7901 cells

AIM:To study the effect of ruthenium-pyridine complex Ru1 on apoptosis of gastric cancer SGC-7901 cells. METHODS:MTT assay and crystal violet staining method were used to detect the viability and cell number of SGC-7901 cells treatment with Ru1. Annexin V-FITC and PI staining was performed to test the apoptosis rate of SGC-7901 cells. The protein expression of Bax and Bcl-2 was detected by Western blot. RESULTS:The results of MTT assay and crystal violet staining showed that the ruthenium-pyridine complexes significantly reduced the viability and cell number of SGC-7901 cells. Treatment with Ru1 for 24 h significantly increased the apoptotic rate of SGC-7901 cells (P<0.05). Ru1 up-regulated the expression of Bax protein and down-regulated the expression of Bcl-2 protein in the SGC-7901 cells (P<0.05). CONCLUSION:Ru1 induces apoptosis of SGC-7901 cells by affecting the expression of Bax and Bcl-2 proteins.     

Inhibition of 17-DMAG on VEGF expression in transplanted human gastric cancer in nude mice

AIM: To observe the anti-tumor effects of heat shock protein 90(HSP90) inhibitor 17-dimethylaminoethylamino-17 demethoxygeldanamycin (17-DMAG) on the tumor growth and angiogenesis in implanted gastric cancer nude mouse model. METHODS: Human gastric cancer cell HGC-27 was subcutaneous inoculation into the nude mice to develop a tumor model. Ten days later, 24 mice with implanted tumor were randomly divided into 3 groups: 17-DMAG group (receiving 17-DMAG at dose of 25 mg/kg), control group (treated with NS at dose of 10 mL/kg) and 5-fluorouracil(5-FU) group (treated with 5-FU at dose of 20 mg/kg). Four weeks after treatment, the tumor volume and weight, and the inhibitory rates of tumor growth were evaluated. In the meantime, the expression of CD31 was detected by immunohistochemical staining. The expression of vascular endothelial growth factor (VEGF) was determined by Western blotting. RESULTS: The size of xenografts in 17-DMAG treatment group was (288.10±23.32)mm³, and that in 5-FU treatment group was (366.37±26.42)mm³, both were significantly smaller than that in control group (957.66±117.51)mm³. The tumor weight in 17-DMAG treatment group was (0.41±0.02)g, significantly less than that in control group (1.12±0.08)g. The inhibitory rate of 17-DMAG was 63%. A significant decease of MVD in 17-DMAG group (21.72±1.24) was observed as compared to 5-FU group (36.70±1.51) and control group (37.78±1.68). The expression of VEGF in 17-DMAG group (15.39±4.37) was significantly lower than that in 5-FU group (26.11±6.26) and control group (36.45±7.45). CONCLUSION: HSP90 inhibitor 17-DMAG suppresses the expression of VEGF and the angiogenesis of the gastric cancer to inhibit the tumor growth.     

Effects of propofol on invasion and migration of human gastric cancer SGC-7901 cells

AIM: To investigate the effects of propofol on invasion and migration of gastric cancer cell line SGC-7901. METHODS: Cultured gastric cancer cell line SGC-7901 was randomly divided into 4 groups, and then diffe-rent concentrations (1, 3, 5 and 7 mg/L) of propofol were added and incubated for 24 h. The cell viability was measured by MTT assay. The invasion and migration abilities of the SGC-7901 cells were detected by Transwell assay and wound-healing assay. The expression of cysteine-rich angiogenic inducer 61 (CYR61), CD44v6 and matrix metalloproteinase-7 (MMP-7) in the SGC-7901 cells were examined by immunocytochemistry and Western blot.RESULTS: Propofol at 5 mg/L does not affect the viability of SGC-7901 cells, whereas significantly suppresses the invasion and migration abilities, and down-regulates the expression of CD44v6 and MMP-7 (P<0.05). CONCLUSION: The decreased invasion and migration abilities of SGC-7901 cells were partly due to the inhibition of CD44v6 and MMP-7 expression.     

Inhibitory effect of survivin-siRNA on prostatic subcutaneous xenografts in nude mice

AIM: To investigate the inhibitory effect of survivin-siRNA recombinant plasmid on prostate cancer xenografts. METHODS: Prostatic cancer DU145 cells were cultured and subcutaneously injected into nude mice. When the tumor grew to 8 mm in diameter, it was aseptically removed and divided into about 2 mm blocks through surgery and subcutaneously implanted into another nude mice. After the prostatic cancer xenograft model was reconstructed, the mice were treated with survivin-siRNA plasmid and control scrambled siRNA plasmid using electric transfection method. The tumor growth curve was plotted and the inhibitory rate was calculated. HE staining, immunohistochemical staining and TUNEL assay were applied to observe the effect of survivin-siRNA on the xenografts. RESULTS: The prostatic cancer xenograft model was successfully constructed in vivo. Compared with mock and scrambled siRNA groups, transfection of survivin-siRNA recombinant plasmid obviously inhibited the tumor growth with the inhibitory rates of 61.81% and 62.87%, respectively. Compared with both controls, survivin-siRNA depressed the protein expression of survivin and promoted the cell apoptosis. CONCLUSION: Survivin-siRNA recombinant plasmid significantly inhibits the growth of prostatic tumor xenografts by inhibiting the protein expression of endogenous survivin and promoting cell apoptosis.     

MicroRNA-146a promotes apoptosis of gastric cancer SGC-7901 cells by targeting TAK1

AIM: To explore the effect of microRNA-146a (miR-146a) on apoptosis of human gastric cancer SGC-7901 cells and the underluing mechanism. METHODS: miR-146a mimic (up-regulated miR-146a expression) and miR-146a inhibitor (down-regulated miR-146a expression) were transfected into the SGC-7901 cells by liposome method. At the same time, miRNA nonsense sequence transfection group as the negative control group (NC group) was set up. RT-qPCR was used to evaluate the levels of miR-146a in the SGC-7901 cells after transfection. The effects of miR-146a on the cell apoptosis and growth were assessed by flow cytometry analysis and CCK-8 assay, respectively. The effect of over-expression or knockdown of miR-146a on transforming growth factor-β-activated kinase 1 (TAK1)/nuclear factor-kappa B (NF-κB) signaling was evaluated by RT-qPCR and Western blot. RESULTS: miR-146a modulated apoptosis of SGC-7901 cells. Over-expression of miR-146a significantly increased apoptosis, whereas knockdown of miR-146a inhibited the apoptosis of SGC-7901 cells. The expression of TAK1 at mRNA and protein levels was significantly decreased when miR-146a mimic was transfected into the SGC-7901 cells (P<0.05). On the contrast, the expression of TAK1 at mRNA and protein were significantly higher in miR-146a inhibitor transfection group than that in NC group (P<0.05), suggesting that miR-146a negatively regulated TAK1 expression. Moreover, knockdown of TAK1 enhanced the apoptosis of SGC-7901 cells (P<0.01), while over-expression of TAK1 inhibited the apoptosis of SGC-7901 cells(P<0.01). Additionally, both over-expression of miR-146a and knockdown of TAK1 led to a prominent increase in the expression of NF-κB inhibitor protein alpha (IκBα) and a significat decrease in B cell lymphoma-2 (Bcl-2) level in the SGC-7901 cells. CONCLUSION: miR-146a significantly promotes apoptosis of SGC-7901 cells by inhibition of NF-κB pathway via targeting TAK1.     

Effects of interferon-β on recurrence and growth of intrahepatic HCC after radical resection in nude mice

AIM:To study the effect of interferon-β (INF-β) on recurrence and growth of intrahepatic HCC after radical resection in nude mice. METHODS:Human HCC cells were implanted into the livers of 25 BALB/c nu/nu nude mice. All the mice were received radical resection of HCC at day 10, and divided into three groups randomly. In group B and C, INF-β was injected subcutaneously at different dosage for each mouse respectively. In group A, nude mice were given saline at the same volume instead of INF-β. At 35 days after treatment, all mice were sacrificed, liver specimens were harvested, the size and volume of recurrent tumor were also measured to calculate the tumor inhibition rate of INF-β. Expression of iNOS, Ki-67 and caspase-3 in recurrent tumor were detected by immunohistochemistry. RESULTS:No difference in HCC recurrent rate among group A, B and C was observed (P>0.05). Tumor volumes was diminished in group B and C as compared with that in group A (P<0.05). Expression of iNOS and Ki-67 in group B and C was decreased as compared with that in group A (P<0.05). Expression of caspase-3 in IFN-β treated group was increased as compared with that in control group (P<0.05). CONCLUSION:IFN-β has an inhibitory effect on growth of intrahepatic HCC after radical resection in nude mice. The inhibitory effect of IFN-β is associated with the dose used, probably related to the changes of iNOS, Ki-67 and caspase-3 expression in tumor tissue.     

Blocking autophagy magnifies MK-2206-induced DNA damage in SGC-7901 cells

AIM: To investigate the effect of MK-2206, an inhibitor of protein kinase B(Akt), on the DNA damage of SGC-7901 cells.METHODS: SGC-7901 cells were treated with different concentrations of MK-2206, and phosphorylated histone H2AX(γ-H2AX) foci formation was detected by immunofluorescence staining. Western blot analysis was used to exam the levels of DNA damage-related protein. The expression of LC3-Ⅱ was determined to evaluate the change of autophagy.RESULTS: MK-2206 treatment increased the formation of γ-H2AX foci and histone H2AX phosphorylation in the SGC-7901 cells. The levels of DNA damage response protein were also increased. In addition, MK-2206-treated SGC-7901 cells increased the expression of LC3-II, a hallmark of autophagy. Inhibition of autophagy significantly enhanced MK-2206-mediated histone H2AX phosphorylation.CONCLUSION: MK-2206 induces DNA damage and autophagy in SGC-7901 cells. Blocking autophagy potentiates the response of MK-2206-induced DNA damage.     

Establishment of human pancreatic tumor xenograft mouse model for evaluating tumor-homing and gene-silencing effects of siRNA-loading nanoparticles

AIM：To establish an effective and rapid method to develop transplanted subcutaneous pancreatic carcinoma by inducing PANC-1 cells into nude mice, and then use this mouse model to evaluate the tumor-homing and gene-silencing effects of siRNA-loading nanoparticles in vivo. METHODS：Different numbers of PANC-1 cells in 100 μL or 300 μL PBS were inoculated subcutaneously into the right flank of BALB/c (nu/nu) mice. When the tumor volume reached 100 mm3, siRNACY5.5 nanoparticles were injected through the mouse tail vein to perform in vivo imaging assay. Besides, the mice were randomly divided into 3 treatment groups treated with PBS, scrambled control RNA nanoparticles and siKras nanoparticles, respectively. The protein expression of Kras was detected by Western blotting and immunohistochemical staining. RESULTS：After inoculated with 1×107 PANC-1 cells in 300 μL PBS, all mice developed tumors within 2 weeks. The in vivo results showed that siRNA-loading nanoparticles accumulated in the tumor tissues and exerted gene silencing effect. CONCLUSION:In the present study, an effective and rapid method was established for PANC-1 cells to induce transplanted subcutaneous pancreatic carcinoma in nude mice within 2 weeks, which is suitable for in vivo imaging and treatment evaluations as a reproducible and reliable way for the further experiments.     

MicroRNA-9 inhibits epithelial-mesenchymal transition in gastric cancer SGC-7901 cells by NRP1

AIM:To investigate the inhibitory effect of microRNA-9(miR-9) on epithelial-mesenchymal transition (EMT) in the gastric cancer SGC-7901 cells and its mechanism.METHODS:The gastric cancer cell line SGC-7901 was transfected with miR-9 mimics or negative control mimic (NCM),as miR-9 or NCM group,respectively.The SGC-7901 cells without transfection were used as control group.The expression level of miR-9 in each group was detected by RT-qPCR.The migration and invasion abilities of the SGC-7901 cells in the 3 groups were detected by Transwell assay.The protein expression of N-cadherin,E-cadherin,α-catenin and neuropilin-1(NRP1) was determined by Western blot.Antagonistic effect of NRP1 over-expression on miR-9 inhibition of EMT was detected by Western blot.The relationship between miR-9 and NRP1 was analyzed by dual luciferase assay.RESULTS:The expression level of miR-9 in miR-9 group was significantly up-regulated,which was 538 times higher than that in control group (P<0.05).The number of migratory cells in miR-9 group was significantly lower than that in control group (P<0.05).Compared with control group,the protein expression of N-cadherin and NRP1 in miR-9 group was significantly decreased,while the protein expression of E-cadherin and α-catenin protein was significantly increased.Over-expression of NRP1 resulted in the increase in the protein expression of N-cadherin in the gastric cancer cells of miR-9 group,and the decrease in the protein expression of E-cadherin and α-catenin significantly.The result of dual luciferase assay showed that NRP1 was a downstream target gene of miR-9(P<0.05).CONCLUSION:miR-9 may inhibit the expression of EMT-related proteins through the downstream target gene NRP1,thus inhibiting the EMT of gastric cancer SGC-7901 cells.     

Role of Fas overexperssion in reversing cisplatin resistance in stomach cancer cells

AIM: To study the effect of Fas on cisplatin resistance in stomach cancer cells and its possible mechanisms.METHODS: The expression of Fas at mRMA and protein levels in SGC-7901 cells and SGC-7901/DDP cells was determined by RT-qPCR and Western blot. Fas-containing adenovirus vector was transfected into the SGC-7901/DDP cells to upregulate Fas expression. The cell viability was detected by CCK-8 assay. The cell cycle and cell apoptosis were analyzed by flow cytometry. The protein levels of Fas, P38/p-P38, JNK/p-JNK, cleaved caspase-8/caspase-8 and cleaved caspase-3/caspase-3 were detected by Western blot.RESULTS: The expression of Fas at both mRNA and protein levels was significantly downregulated in the SGC-7901/DDP cells. Fas expression was decreased by cisplatin in a dose-dependent manner in the SGC-7901 cells. Overexpression of Fas suppressed the viability and induced apoptosis in the SGC-7901/DDP cells, and upregulated the protein levels of p-P38, p-JNK, cleaved caspase-8 and cleaved caspase-3.CONCLUSION: Overexpression of Fas increases the sensitivity of the SGC-7901/DDP cells to cisplatin, and inhibits the cell growth and promotes cell apoptosis. The mechanism may be related to the activation of JNK and P38 pathway.     

Effect of beclin-1 gene silencing on TuAKe-injured gastric cancer SGC-7901 cells

AIM: To observe the effect of beclin-1 silencing by the technique of RNA interference on the injury of human gastric cancer SGC-7901 cell by Sheliugu extract (the extract from tuber of Amorphophallus konjac, TuAKe). METHODS: To knock down the expression of beclin-1 gene, SGC-7901 cells were transfected with lentiviral vector carrying beclin-1-shRNA. The beclin-1 gene knock-down and non-knock-down SGC-7901 cells were treated with TuAKe. The cell viability was analyzed by CKK-8 assay. The percentages of apoptotic cells were detected by flow cytometry. The expression of beclin-1 and LC3 was detected by Western blot. RESULTS: The beclin-1 gene silencing decreased the protein expression of beclin-1 and increased the protein expression of LC3 in the SGC-7901 cells, leading to the decrease in cell viability and the increase in apoptotic rate (P<0.05). TuAKe increased the protein expression of beclin-1 and LC3 in the SGC-7901 cells, and decreased the protein expression of LC3 in the SGC-7901 cells with beclin-1 gene silencing, thus inhibiting the cell viability and increasing the apoptotic rate (P<0.05). CONCLUSION: Beclin-1 gene silencing inhibits the activation of beclin-1-related signaling pathway in gastric cancer SGC-7901 cells, and aggravates the injury of cell viability induced by TuAKe.     

Expression of DNMT in gastric cancer and effects of DNMT inhibitor 5-aza-2’-deoxycytidine on gastric cancer

AIM: To investigate the protein expression of DNA methyltransferases (DNMT1, DNMT2, DNMT3A, DNMT3B and DNMT3L) in gastric cancer and the effects of DNMT inhibitor (5-aza-2’-deoxycytidine) on gastric cancer. METHODS: The method of immunohistochemistry was used to detect DNMT expression in 60 pairs of gastric cancer and corresponding non-cancerous tissues. The expression of DNMT in gastric cancer cells (SGC-7901 and MKN-45) and gastric mucosa cells (GES-1) was detected by immunofluorescence and Western blotting. The proliferation, cell cycle and apoptosis in the cell lines of SGC-7901, MKN-45 and GES-1 were determined by MTT assay and flow cytometry with 5-aza-2’-deoxycytidine treatment. RESULTS: Both gastric cancer and corresponding non-cancerous tissues expressed 5 kinds of DNMT proteins, but the expression levels of DNMT1 and DNMT3A were significantly lower in gastric cancer than those in non-cancerous tissues (P<0.01). The expression levels of DNMT2 and DNMT3L were also lower in the cancer than those in non-cancerous tissues (P<0.05). No difference of DNMT3B expression level between cancer and non-cancerous tissues was observed (P>0.05). On the other hand, the cells lines of SGC-7901, MKN-45 and GES-1 also expressed DNMT proteins. Except DNMT3B, no difference of the other kinds of DNMT between gastric cancer cells and gastric mucosa cells was observed. DNMT inhibitor 5-aza-2’-deoxycytidine did not have any effect on the growth rate, cell cycle distribution or apoptotic rate in gastric cancer cells and gastric mucosa cells. CONCLUSION: Gastric cancer expresses low levels of DNMT proteins than normal gastric mucosa. 5-Aza-2’-deoxycytidine is not useful for treating gastric cancer.     

Effect of integrin β1 on multidrug resistance in gastric cancer SGC-7901 cells

AIM: To study the effect of integrin β1 on multidrug resistance in gastric cancer and its possible mechanisms. METHODS: The expression of integrin β1 at mRNA and protein levels in the SGC-7901 cells and SGC-7901/DDP cells was determined by qPCR and Western blot. The expression of integrin β1 in the SGC-7901/DDP cells was silenced by antisense oligodeoxynucleotide. The cell viability was detected by the CCK-8 assay, the cell apoptosis were analyzed by flow cytometry, and the protein levels of integrin β1, Bcl-2/Bax, cleaved caspase-3/caspase-3, cytochrome C (Cyt-C) and p-AKT/AKT were determined by Western blot.RESULTS: The expression of integrin β1 at both mRNA and protein levels was significantly upregulated in SGC-7901/DDP cells. The expression of integrin β1 was increased in SGC-7901 cells treated with chemotherapeutic agents such as cisplatin, paclitaxel and 5-fluorouracil. Knockdown of integrin β1 induced apoptosis of SGC-7901/DDP cells with an increased sensitivity to the chemotherapeutic agents. Meanwhile, knockdown of integrin β1 downregulated the protein levels of Bcl-2/Bax, p-AKT^Ser473 and p-AKT^Thr308, while promoted the release of Cyt-C and upregulated the protein level of cleaved caspase-3. CONCLUSION: Knockdown of integrin β1 increases the sensitivity of SGC-7901/DDP cells to the chemotherapeutic agents, and promotes the cell apoptosis via mitochondrial apoptosis pathway. The mechanism may be related to the attenuation of AKT pathway by inhibiting phosphorylations of AKT at Ser473 and Thr308.