罗格列酮抑制人胃腺癌SGC7901增殖机制的研究

目的：探讨在体外不同浓度的过氧化物酶体增殖物激活受体γ（PPARγ）激动剂罗格列酮（ROZ）对人胃癌细胞系SGC7901的生长及细胞周期的影响。方法：采用MTT法比色实验、集落形成实验、电子显微镜,透射电镜,流式细胞仪分别观察不同浓度罗格列酮0.08μmol/L,0.4μmol/L,2μmol/L,10μmol/L,50μmol/L,作用于SGC7901细胞,对细胞增殖,细胞形态和细胞周期的影响。结果：ROZ可抑制SGC7901细胞的生长以及SGC7901细胞集落的形成,并呈现剂量依赖性,其半数抑制浓度（IC50）约为50μmol/L。透射电镜低倍镜以及高倍下可见凋亡细胞。流式细胞仪结果显示,ROZ可抑制SGC7901细胞,引起G0/G1期细胞大量增加,S期细胞减少,且细胞周期停滞于G1期。结论：ROZ具有抗肿瘤作用,能够抑制SGC7901细胞的增殖并诱导凋亡,这种作用与其诱导细胞周期G0/G1期的停滞和诱导凋亡作用有关。因此,ROZ有望成为胃癌治疗的辅助用药亦或治疗药,PPARγ有潜力成为肿瘤治疗的新靶点。     

ARHGEF10L expression regulates cell proliferation and migration in gastric tumorigenesis

ABSTRACT

We recently reported that Rho guanine nucleotide exchange factor 10-like protein (ARHGEF10L) activated Rho GTPases as guanine nucleotide exchange factor to stimulate liver tumorigenesis. The present study continued to explore the effect of ARHGEF10L on the tumorigenic process of gastric cancer. This study detected increased expression of ARHGEF10L in GC tissues compared to peritumoral tissue samples. SGC7901 cells with ARHGEF10L overexpression showed increased cell proliferation, cell migration, and tube-like structure formation abilities, as well as increased expression of GTP-RhoA, ROCK1, and phospho-Ezrin/Radixin/Moesin. ARHGEF10L overexpression downregulated the expression of E-cadherin and upregulated the expression of N-cadherin and Slug, indicating an activation of EMT in the transfected cells. RNA-sequencing assay detected an increased expression of Heat shock 70 kDa protein 6 in the SGC7901 cells overexpressing ARHGEF10L. The above results suggest that ARHGEF10L expression can stimulate gastric tumorigenesis by prompting RhoA-ROCK1-phospho-ERM signaling, inducing EMT and increasing HSPA6 expression.     

The impact of C-MYC gene expression on gastric cancer cell

The upregulation or mutation of C-MYC has been observed in gastric, colon, breast, and lung tumors and in Burkitt’s lymphoma. However, little is known about the role C-MYC plays in gastric adenocarcinoma. In the present study, we intended to investigate the influence of C-MYC on the growth, proliferation, apoptosis, invasion, and cell cycle of the gastric cancer cell line SGC7901 and the gastric cell line HFE145. C-MYC cDNA was subcloned into a constitutive vector PCDNA3.1 followed by transfection in normal gastric cell line HFE145 by using liposome. Then stable transfectants were selected and appraised. Specific inhibition of C-MYC was achieved using a vector-based siRNA system which was transfected in gastric cancer cell line SGC7901. The apoptosis and cell cycles of these clones were analyzed by using flow cytometric assay. The growth and proliferation were analyzed by cell growth curves and colony-forming assay, respectively. The invasion of these clones was analyzed by using cell migration assay. The C-MYC stable expression clones (HFE-Myc) and C-MYC RNAi cells (SGC-MR) were detected and compared with their control groups, respectively. HFE-Myc grew faster than HFE145 and HFE-PC (HFE145 transfected with PCDNA3.1 vector). SGC-MR1, 2 grew slower than SGC7901 and SGC-MS1, 2 (SGC7901 transfected with scrambled control duplexes). The cell counts of HFE-Myc in the third, fourth, fifth, sixth, and seventh days were significantly more than those of control groups (P < 0.05). Those of SGC-MR1, 2 in the fourth, fifth, sixth, and seventh days were significantly fewer than those of control groups (P < 0.05). Cell cycle analysis showed that proportions of HFE-Myc and SGC-MR cells in G0–G1 and G2–M were different significantly with their control groups, respectively (P < 0.05). The apoptosis rate of HFE-Myc was significantly higher than those of control groups (P < 0.05). Results of colony-forming assay showed that the colony formation rate of HFE-Myc was higher than those of control groups; otherwise, the rate of SGC-MR was lower than those of their control groups (P < 0.05). The results of cell migration assay showed that there were no significant differences between experimental groups and control groups (P > 0.05). In conclusion, C-MYC can promote the growth and proliferation of normal gastric cells, and knockdown of C-MYC can restrain the growth and proliferation of gastric cancer cells. It can induce cell apoptosis and help tumor cell maintain malignant phenotype. But it can have not a detectable influence on the ability of invasion of gastric cancer cells.     

MiR-935通过其靶基因Notch1调控胃癌SGC7901细胞的发生发展

目的:探究Mi R-935调控胃癌SGC7901细胞的增殖和浸润与Notch1基因表达的关系。方法:分别检测40例正常人胃粘膜组织与40例胃印戒细胞癌的Notch1表达情况,并分析胃印戒细胞癌组织中Notch1表达与患者年龄、性别、组织进展程度、TNM分期、有无淋巴结转移的关系;采用Mi R-935转染体外培养的SGC7901细胞系,检测Notch1的表达情况,其后采用Mi R-935抑制剂处理,通过Transwell实验检测胃癌细胞的侵袭能力,细胞划痕实验检测胃癌细胞迁移能力。结果:正常人胃粘膜组织中Notch1表达呈阴性,而胃印戒细胞癌组织中Notch1表达呈阳性;Notch1的表达与胃印戒细胞癌的TNM分期、有无淋巴结转移存在着显著的相关性;转染Mi R-935的SGC7901细胞Notch1表达明显上调,采用Mi R-935抑制剂处理后,Notch1的表达显著下降。结论:Mi R-935可能通过调控Notch1的表达调控胃癌的扩增和浸润。     

Cycloxygenase-2 is Essential for the Survival and Proliferation of Gastric Cancer Cells

Cycloxygenase-2 catalyzes the synthesis of prostaglandins from arachidonic acid and this enzyme has been implicated in the metastasis of gastric cancer. In order to examine the significance of cycloxygenase-2 (Cox-2) in the survival and proliferation of gastric cancer cells, we have stably overexpressed an antisense Cox-2 in two gastric cancer cell lines, SGC7901 and AGS, in order to reduce the expression of this protein. The sense and antisense Cox-2 expression vectors were created by cloning COX-2 cDNA, in pIRES2-EGFP plasmid. Cox-2 gene expression was monitored by RT-PCR and Western blotting and the results indicated that cells with antisense Cox-2 construct had significantly reduced Cox-2 expression in comparison to the cells that received sense-Cox-2 plasmid. Reduction of Cox-2 expression in SGC7901 and AGS gastric cancer cells led to markedly decreased proliferation. The metastatic capability of the two cell lines, as assessed by in vitro colony formation assay, is also significantly compromised by lowered Cox-2 expression. Thus, this study demonstrates that Cox-2 activity is necessary for the proliferation and metastasis of gastric cancer cells.     

Impact of BTG2 expression on proliferation and invasion of gastric cancer cells in vitro

BTG2 (B cell translocation gene 2) is downregulated in several human tumors and has been known as a tumor suppressor in carcinogenesis of thymus, prostate, kidney, and liver. However, little is known about the role BTG2 plays in gastric adenocarcinoma. In the present study, we intended to investigate the influence of BTG2 on the growth, proliferation, apoptosis, invasion and cell cycle of the gastric cancer cell lines SGC7901 and MKN45. BTG2 cDNA was insected into a constitutive vector pcDNA3.1 followed by transfection in gastric cancer cell line MKN45 and SGC7901 by using liposome. Then stable transfectants were selected and appraised. The apoptosis and cell cycles of these transfectants were analyzed by using flow cytometric assay. The growth and proliferation were analyzed by cell growth curves and colony-forming assay, respectively. The invasion of these clones was analyzed by using cell migration assay. MKN-BTG2 (MKN45 with stable transfection of BTG2 gene) and SGC-BTG2 (SGC7901 with stable transfection of BTG2 gene) grew slower than their control groups, respectively. The cell counts of MKN-BTG2 in the fourth, fifth, sixth and seventh days were significantly fewer than those of control groups (P < 0.05). Those of SGC-BTG2 in the fourth fifth, sixth and seventh days were significantly fewer than those of control groups too (P < 0.05). Cell cycle analysis showed that proportions of MKN-BTG2 and SGC-BTG2 cells in G0–G1 and S were different significantly with those of their control groups, respectively (P < 0.05). The apoptosis rate of MKN-BTG2 was significantly higher than those of control groups (P < 0.05). Results of colony-forming assay showed that the colon formation rates of MKN-BTG2 and SGC-BTG2 were lower than those of their control groups (P < 0.05). The results of cell migration assay showed that the cell migration rates of MKN-BTG2 and SGC-BTG2 were not significantly different with those of their control groups (P > 0.05). BTG2 can restrain the growth and proliferation of gastric cancer cells powerfully. It can reduce some malignant phenotype of these tumor cells. But it could not impact the ability of invasion of gastric cancer cells, so could not restrain the metastasis of gastric cancer. In gastric cancer, BTG2 could be thought as a tumor-inhibiting gene in some distance, so the gene could be a potential target of gene therapy.     

FPR2介导内外源性配体HP(2-20)/ANXA1促进胃癌细胞侵袭和转移

目的:分析FPR2在内外源性配体对胃癌细胞侵袭和转移影响中的作用。方法:采用构建成功的XN0422/SGC7901-mock细胞和XN0422/SGC7901-sh FPR2低表达细胞,通过划痕实验、transwell实验观察和比较FPR2的内外源性配体-HP(2-20)/ANXA1对XN0422/SGC7901迁移和增殖的影响。结果:HP(2-20)/ANXA1处理的XN0422/SGC7901-mock和XN0422/SGC7901-sh FPR2细胞侵袭和转移能力均相较于DMSO处理的XN0422/SGC7901-mock和XN0422/SGC7901-sh FPR2细胞明显增强(P0.05),且XN0422/SGC7901-mock组细胞的侵袭转移能力明显优于XN0422/SGC7901-sh FPR2组细胞(P0.05)。结论:HP2-20和Ac2-26可以促进胃癌细胞的侵袭和迁移,而这一作用与FPR2有关。     

转录因子SOX2 对胃癌干细胞自我更新、增殖和迁移的影响

目的:检测SOX2在胃癌组织中的表达,探讨SOX2对胃癌干细胞自我更新、增殖和转移能力的影响。方法:采用免疫组化检测SOX2在胃癌及癌旁组织中的表达情况。通过肿瘤球形成实验富集、分离胃癌干细胞。构建SOX2过表达慢病毒并感染胃癌干细胞中,通过实时定量PCR和western bolt检测感染慢病毒后胃癌干细胞中SOX2表达情况。分别利用肿瘤球形成实验检测SOX2对胃癌肿瘤干细胞自我更新能力的影响,CCK-8实验检测SOX2对胃癌干细胞增殖能力的影响,流式细胞术分析SOX2对胃癌干细胞的细胞周期的影响,Transwell实验检测SOX2对胃癌干细胞转移能力的影响。结果:SOX2在胃癌组织中表达显著低于癌旁组织。肿瘤球形成实验能够有效富集胃癌细胞SGC-7901和BGC-823的干细胞。慢病毒载体感染能够显著增强SOX2在胃癌干细胞中的表达。过表达SOX2能够抑制胃癌干细胞的自我更新、增殖和侵袭能力。结论:SOX2在胃癌中发挥抑癌基因的功能,其机制可能通过抑制肿瘤干细胞的自我更新、增殖和侵袭转移能力而抑制胃癌的发生发展。     

siRNA targeting midkine inhibits gastric cancer cells growth and induces apoptosis involved caspase-3,8,9 activation and mitochondrial depolarization

Midkine (MK), a heparin-binding growth factor, is expressed highly in various malignant tumors, so it acts as attractive therapeutic target. In the present study, we used siRNA targeting MK to downregulate human MK expression in human gastric cancer cell line BGC823 and SGC7901 so as to determine the advantages of this anticancer therapeutic. The cell proliferation was evaluated by a WST-8 (4-[3-(2-methoxy-4-nitrophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1, 3-benzene disulfonate sodium salt) assay and colony formation assay. Apoptosis was determined by flow cytometer analysis and colorimetric assay. Our results showed that the BGC823 and SGC7901 cell growth were significantly inhibited by knockdown of MK gene. The loss of mitochondrial membrane potential, release of cytochrome c from the mitochondria into cytosol and increased activity of caspase-3, 8 and 9 occurred concomitantly with inhibition of MK gene. These results indicated that siRNA targeting MK gene can inhibit gastric cancer cells growth and induce apoptosis via mitochondrial depolarization and caspase-3 activation. MK siRNA may be a promising novel and potential therapeutic strategy for the treatment of gastric cancers.     

ERK1/2 inhibition enhances apoptosis induced by JAK2 silencing in human gastric cancer SGC7901 cells

Recent studies suggest JAK2 signaling may be a therapeutic target for treatment of gastric cancer (GC). However, the exact roles of JAK2 in gastric carcinogenesis are not very clear. Here, we have targeted JAK2 to be silenced by shRNA and investigated the biological functions and related mechanisms of JAK2 in GC cell SGC7901. In this study, JAK2 is commonly highly expressed in GC tissues as compared to their adjacent normal tissues (n = 75, p < 0.01). Specific down-regulation of JAK2 suppressed cell proliferation and colony-forming units, induced G2/M arrest in SGC7901 cells, but had no significant effect on cell apoptosis in vitro or tumor growth inhibition in vivo. Interestingly, JAK2 silencing-induced activation of ERK1/2, and inactivation of ERK1/2 using the specific ERK inhibitor PD98059 markedly enhanced JAK2 shRNA-induced cell proliferation inhibition, cell cycle arrest and apoptosis. Ultimately, combination of PD98059 and JAK2 shRNA significantly inhibited tumor growth in nude mice. Our results implicate JAK2 silencing-induced cell proliferation inhibition, cell cycle arrest, and ERK1/2 inhibition could enhance apoptosis induced by JAK2 silencing in SGC7901 cells.     

Reversal effects of pantoprazole on multidrug resistance in human gastric adenocarcinoma cells by down-regulating the V-ATPases/mTOR/HIF-1α/P-gp and MRP1 signaling pathway in vitro and in vivo

To investigate reversal effects of pantoprazole (PPZ) on multidrug resistance (MDR) in human gastric adenocarcinoma cells in vivo and in vitro. Human gastric adenocarcinoma cell SGC7901 was cultured in RPMI‐1640 medium supplemented with 10% fetal bovine serum and antibiotics in a humidified 5% CO₂ atmosphere at 37°C. Adriamycin (ADR)‐resistant cells were cultured with addition of 0.8 µg/ml of ADR maintaining MDR phenotype. ADR was used to calculate ADR releasing index; CCK‐8 Assay was performed to evaluate the cytotoxicity of anti‐tumor drugs; BCECF‐AM pH‐sensitive fluorescent probe was used to measure intracellular pH (pHi) value of cells, whereas pH value of medium was considered as extracellular pH (pHe) value; Western blotting and immunofluorescent staining analyses were employed to determine protein expressions and intracellular distributions of vacuolar H⁺‐ATPases (V‐ATPases), mTOR, HIF‐1α, P‐glycoprotein (P‐gp), and multidrug resistant protein 1 (MRP1); SGC7901 and SGC7901/ADR cells were inoculated in athymic nude mice. Thereafter, effects of ADR with or without PPZ pretreatment were compared by determining the tumor size and weight, apoptotic cells in tumor tissues were detected by TUNEL assay. At concentrations greater than 20 µg/ml, PPZ pretreatment reduced ADR releasing index and significantly enhanced intracellular ADR concentration of SGC7901 (P < 0.01). Similarly, PPZ pretreatment significantly decreased ADR releasing index of SGC7901/ADR dose‐dependently (P < 0.01). PPZ pretreatment also decreased cell viabilities of SGG7901 and SGC7901/ADR dose‐dependently. After 24‐h PPZ pretreatment, administration of chemotherapeutic agents demonstrated maximal cytotoxic effects on SGC7901 and SGC7901/ADR cells (P < 0.05). The resistance index in PPZ pretreatment group was significantly lower than that in non‐PPZ pretreatment group (3.71 vs. 14.80). PPZ at concentration >10 µg/ml significantly decreased pHi in SGC7901 and SGC7901/ADR cells and diminished or reversed transmembrane pH gradient (P < 0.05). PPZ pretreatment also significantly inhibited protein expressions of V‐ATPases, mTOR, HIF‐1α, P‐gp, and MRP1, and alter intracellular expressions in parent and ADR‐resistant cells (P < 0.05). In vivo experiments further confirmed that PPZ pretreatment could enhance anti‐tumor effects of ADR on xenografted tumor of nude mice and also improve the apoptotic index in xenografted tumor tissues. PPZ pretreatment enhances the cytotoxic effects of anti‐tumor drugs on SGC7901 and reverse MDR of SGC7901/ADR by downregulating the V‐ATPases/mTOR/HIF‐1α/P‐gp and MRP1 signaling pathway. J. Cell. Biochem. 113: 2474–2487, 2012. © 2012 Wiley Periodicals, Inc.     

慢病毒介导NCL基因沉默的胃癌细胞系的建立及对细胞增殖影响的研究

目的:本研究通过建立慢病毒介导的NCL基因沉默的胃癌细胞系,研究NCL沉默对胃癌细胞增殖能力的影响,为深入探究胃癌发生发展的分子机制提供理论基础。方法:利用小发卡RNA(shRNA)介导的慢病毒系统沉默胃癌细胞中的NCL,并利用RT-q PCR和免疫印迹检测基因沉默效果;并利用CCK-8实验和平板克隆形成实验检测胃癌细胞的增殖能力的改变。结果:琼脂糖凝胶电泳实验检测经酶切鉴定的pKLO.1-NCL载体,显示5000 bp和2000 bp两条带,测序峰图显示与设计序列一致;利用HEK293T包装病毒,感染胃癌细胞SGC-7901,免疫印迹结果显示sh NCL组NCL蛋白水平显著低于对照组,RT-qPCR结果显示,sh NCL组NCL表达量显著降低,为对照组的0.4209±0.087倍(P0.001);CCK-8实验结果显示,sh NCL组在第5天的吸光值较对照组显著降低(P0.001),平板克隆形成实验结果显示,sh NCL组克隆形成能力较对照组显著降低,克隆形成数量显著低于对照组(P0.01)。结论:建立了慢病毒介导的NCL基因沉默的胃癌细胞系SGC-7901,并利用此系统研究了NCL基因对胃癌细胞增殖能力的影响,证明了NCL基因能够促进胃癌细胞的增殖,为后续研究NCL基因在胃癌细胞中的作用提供基础。     

Induction of cell differentiation and promotion of endocan gene expression in stomach cancer by melatonin

The pineal hormone melatonin has been shown to have anticancer therapeutic properties in patients with gastric cancer, the mechanisms, however, remain largely unknown. The present study examined the effects of melatonin on cell differentiation related factors, namely, endocan, alkaline phosphatase, and lactate dehydrogenase, in gastric adenocarcinoma cell line SGC7901. Expression of endocan was significantly decreased in tissue of gastric cancer as compared to normal stomach tissue, as determined by immunohistochemical staining, and there is correlation between the degree of the decrease of endocan expression and the degree of differentiation of the cancer. Treatment of cultured gastric adenocarcinoma cells with 10⁻⁴ mol/l melatonin significantly increased the gene expression of endocan and down-regulated the activity of alkaline phosphatase and lactate dehydrogenase, two enzymes that promote de-differentiation in gastric tissue; and there was a negative correlation between the level of endocan expression and the activities of differentiation marker enzymes in the melatonin treated cancer cells. Gastric cancer cells treated with melatonin show more differentiated morphologic phenotype as compared the untreated cells. The findings indicate that melatonin may play its anticancer role in gastric adenocarcinoma by acting as a differentiation inducer.     

MicroRNA let-7f inhibits tumor invasion and metastasis by targeting MYH9 in human gastric cancer

Background

MicroRNAs (miRNAs) are important regulators that play key roles in tumorigenesis and tumor progression. A previous report has shown that let-7 family members can act as tumor suppressors in many cancers. Through miRNA array, we found that let-7f was downregulated in the highly metastatic potential gastric cancer cell lines GC9811-P and SGC7901-M, when compared with their parental cell lines, GC9811 and SGC7901-NM; however, the mechanism was not clear. In this study, we investigate whether let-7f acts as a tumor suppressor to inhibit invasion and metastasis in gastric cancers.

Methodology/Principal

Real-time PCR showed decreased levels of let-7f expression in metastatic gastric cancer tissues and cell lines that are potentially highly metastatic. Cell invasion and migration were significantly impaired in GC9811-P and SGC7901-M cell lines after transfection with let-7f-mimics. Nude mice with xenograft models of gastric cancer confirmed that let-7f could inhibit gastric cancer metastasis in vivo after transfection by the lentivirus pGCsil-GFP- let-7f. Luciferase reporter assays demonstrated that let-7f directly binds to the 3′UTR of MYH9, which codes for myosin IIA, and real-time PCR and Western blotting further indicated that let-7f downregulated the expression of myosin IIA at the mRNA and protein levels.

Conclusions/Significance

Our study demonstrated that overexpression of let-7f in gastric cancer could inhibit invasion and migration of gastric cancer cells through directly targeting the tumor metastasis-associated gene MYH9. These data suggest that let-7f may be a novel therapeutic candidate for gastric cancer, given its ability to reduce cell invasion and metastasis.     

Antiproliferative activity of rosamultic acid is associated with induction of apoptosis,cell cycle arrest,inhibition of cell migration and caspase activation in human gastric cancer (SGC-7901) cells

BackgroundGastric cancer is the second leading cause of cancer related deaths after lung cancer globally. Among natural products, natural triterpenes represent a structurally diverse group of organic compounds with potent antitumor activity.PurposeThe objective of the present research work demonstrated the antiproliferative and apoptotic activity of rosamultic acid, a natural triterpenoid, in human gastric cancer (SGC-7901) cells. Its effect on cellular morphology, cell cycle arrest, DNA fragmentation and expression levels of caspase-3, caspase-8 and caspase-9 were also determined.MethodsAntiproliferative activity of rosamultic acid was evaluated by MTT assay. Phase contrast, fluorescence microscopy as well as flow cytometry using Hoechst 33342, acridine orange/ethidium bromide and Annexin V-FITC as cellular probes were used to evaluate the induction of apoptosis by rosamultic acid. Protein level expressions were analyzed by western blot analysis.ResultsThe results revealed that rosamultic acid induced dose-dependent as well as time dependent cytotoxic effects in SGC-7901 gastric cancer cells. It also led to a reduction in clonogenic activity along with inhibiting the cell migration. Characteristic features of apoptosis induced by rosamultic acid were observed and quantified. Cell cycle arrest at sub-G1 phase was induced by rosamultic acid along with downregulation of expression levels of CDK4, CDK6 and cyclin D1. Rosamultic acid also significantly led to the activation of caspase-3, -8 and -9 during the 48 h treatment along with cleaving PARP in a dose-dependent manner. DNA fragmentation following rosamultic acid treatment was also observed in these cells.ConclusionThe current study strongly reveals that rosamultic acid inhibits gastric cancer proliferation by inducing apoptosis mediated through cell cycle arrest, downregulation of cell cycle related protein expressions, inhibition of cell migration, DNA damage, and activation of caspases.     

Downregulation of microRNA-92b-3p suppresses proliferation,migration, and invasion of gastric cancer SGC-7901 cells by targeting Homeobox D10

To investigate the effect and mechanism of microRNA-92b-3p (miR-92b-3p) targeting Homeobox D10 (HOXD10) on proliferation, migration, and invasion of gastric cancer, we detected t he expression of miR-92b-3p and HOXD10 in SGC-7901 cells. The effects of miR-92b-3p or HOXD10 on proliferation, migration, invasion, and matrix metalloproteinase (MMP)-2/9 expression in SGC-7901 cells were measured by the Cell Counting Kit-8 assay, Transwell assay, and Western blot, respectively. The results showed that miR-92b-3p expression was increased, and HOXD10 expression was decreased in SGC-7901 cells, compared with human normal gastric epithelial cells GES-1. Functional experiments demonstrated that cell proliferation, migration, invasion, and expression of MMP-2/9 in SGC-7901 cells were significantly inhibited by miR-92b-3p silencing and HOXD10 overexpression. Moreover, HOXD10 was a potential target gene of miR-92b-3p as evidenced by the TargetScan software and double luciferase reporter assay. In the rescue experiment, knockdown of HOXD10, accompanied by higher expression of MMP-2/9, could significantly eliminate the inhibitory effects of miR-92b-3p silencing on cell proliferation, migration, and invasion. In conclusion, miR-92b-3p is highly expressed in gastric cancer SGC-7901 cells, and interfering with its expression might inhibit SGC-7901 cell proliferation, migration, and invasion via downregulating MMP-2/9 expression and targeting HOXD10.     

Delivery of BR2‐SOX17 fusion protein can inhibit cell survival,proliferation, and invasion in gastric cancer cells through regulating Klotho gene expression

The prognosis of advanced gastric cancer is poor and understanding the biology and subsequent development of new targeting therapy is still an urgent need. This study was conducted to explore the effect of BR2 (a 17‐amino acid peptide)‐SOX17 (human sex determining region Y (SRY)‐related high‐mobility group (HMG) box protein family member 17) fusion protein on Klotho gene expression in gastric cancer cells. The regulatory effects of SOX17 on Klotho gene in gastric cancer cells were tested using dual‐luciferase reporter assay and chromatin immunoprecipitation (ChIP) assay. The therapeutic effects of BR2‐SOX17 were evaluated by proliferation, colony formation, invasion assay, and cell apoptosis analysis. Results showed that SOX17 enhanced Klotho gene expression in gastric adenocarcinoma cells through binding to the promoter of Klotho gene. BR2‐SOX17 fusion protein was effective in delivering SOX17 into gastric cancer cells and subsequently inhibited the cell proliferation, colony formation, and invasion, increased E‐cadherin protein expression, decreased vimentin protein expression, as well as induced apoptosis. Our findings suggested SOX17 can bind to the promoter of Klotho gene to enhance Klotho gene expression in gastric cancer cells. The fused BR2‐SOX17 protein is an effective agent for targeting therapy of gastric cancer.     

Downregulation of ornithine decarboxylase by pcDNA-ODCr inhibits gastric cancer cell growth in vitro

Ornithine decarboxylase (ODC), the first rate-limiting enzyme of polyamine biosynthesis, was found to be associated with cell growth, proliferation and transformation. ODC gene expression in gastric cancer was increased and its level was positively correlated with the degree of malignity of gastric mucosa and development of gastric lesions. In order to evaluate the therapeutic effects of antisense RNA of ODC on gastric cancer, an antisense RNA of ODC expressing plasmid pcDNA-ODCr which delivered a 120 bp fragment complementary to the initiation codon of ODC gene was constructed and transfected to gastric cancer cells SGC7901 and MGC803. Expression of ODC in gastric cancer cells was determined by western blot. Cell proliferation was assessed by MTS assay. Cell cycle was analyzed by flow cytometry and Matrigel assay was performed to assess the ability of gastric cancer cell invasiveness. The results showed that the ODC gene expression in gastric cancer cells transfected with the pcDNA-ODCr was downregulated efficiently. Tumor cell proliferation was suppressed significantly, and cell cycle was arrested at G1 phase. Gastric cancer cells had reduced invasiveness after gene transfer. Our study suggested that antisense RNA of ODC expressing plasmid pcDNA-ODCr had antitumor activity by inhibiting the expression of ODC, and downregulation of ODC expression using a gene therapy approach might be a novel therapeutic strategy for gastric cancer.