Estrogen-producing steroidogenic pathways in parietal cells of the rat gastric mucosa

Recently we demonstrated the presence of aromatase (P450(arom)), estrogen synthetase, and the active production of estrogen in parietal cells of the rat stomach. We therefore investigated the steroidogenic pathways of estrogen and also other steroid metabolites in the gastric mucosa of male rats, by showing the mRNA expression of steroidogenic enzymes using RT-PCR and in situ hybridization histochemistry, and by measuring the blood concentration of steroids in the artery and the portal vein. RT-PCR analysis showed the strong mRNA expression of 17alpha-hydroxylase/17,20-lyase (P450(17alpha)), 17beta-hydroxysteroid dehydrogenase (HSD) type III and P450(arom), and the weak mRNA expression of 17beta-HSD type II, 5alpha-reductase type I and 3alpha-HSD. The other mRNAs of steroidogenic enzymes examined were not detected. In situ hybridization histochemistry demonstrated the localization of mRNAs for P450(17alpha), 17beta-HSD type III and P450(arom) in the parietal cells. Higher levels of progesterone and testosterone were found in the artery compared with the portal vein. Higher amounts of estrone and 17beta-estradiol, by contrast, were present in the portal vein compared with the artery. These results indicate that parietal cells of rat stomach convert circulating progesterone and/through androstenedione and testosterone to synthesize both estrone and 17beta-estradiol, which then enter the liver via the portal vein.     

幽门螺杆菌L型感染及血管生成素的表达与胃癌血管生成的关系

目的探讨幽门螺杆菌L型(Hp-L)感染和血管生成素(Ang)在胃癌中的表达及与肿瘤血管生成的关系。方法采用革兰染色和免疫组化方法检测84例胃癌和30例癌旁正常组织中Hp-L型感染,应用免疫组化方法检测Ang-1、Ang-2蛋白表达水平,计数微血管密度(MVD),结合临床病理因素进行分析。结果胃癌组织中Hp-L型感染率、Ang-2阳性表达率、MVD值明显高于正常组织(P0.05),胃癌中Hp-L型感染与肿瘤分化程度、侵袭深度、临床分期、淋巴结转移有关(P0.05),与Ang-2表达、MVD呈正相关。胃癌组织中Ang-2表达与肿瘤大小、侵袭深度、淋巴结转移有关(P0.05),与MVD呈正相关。Ang-1在胃癌中表达略低于对照组,但无统计学差异(P0.05),Ang-1表达与侵袭深度和MVD呈负相关。结果 胃癌Hp-L型感染在肿瘤血管生成中起重要作用,其机制与Ang-2表达上调,Ang-2/Ang-1比例失衡有关。     

褪黑素对胃癌小鼠Survivin表达的影响

目的探讨褪黑素对胃癌小鼠Survivin表达的影响。方法选用6-8周龄SPF级615近交系小鼠,接种胃癌MFC细胞,建立荷瘤小鼠模型并给予不同剂量的褪黑素处理,用Real-time PCR法和Western blot法检测肿瘤组织中Survivin mRNA和蛋白的表达。结果 Real-time PCR和Western-blot检测显示褪黑素各干预组小鼠胃癌组织中Survivin基因的表达水平下降且随褪黑素剂量增大而降低。结论褪黑素具有下调survivin的作用。褪黑素降低survivin的表达,可能是褪黑素抑制肿瘤的作用机制之一。     

Blood and urine iodine levels in patients with gastric cancer

In this study, we aimed to investigate whether there is any relationship between gastric cancer and iodine concentrations in blood and urine in the northeast Anatolia region, where iodine deficiency is common. A total of 56 patients, diagnosed as gastric cancer and 25 healthy volunteers were included in the study. The methods used were based on the Sandell-Kolthoff reaction. The urine iodine concentration (UIC) and serum protein-bound iodine (PBI) levels were higher in patients with gastric cancer compared with healthy control subjects. The UIC in stage IV was higher than all other stages and the control group. The UIC was higher in stages III and IV compared with stages I and II. However, serum PBI levels in stage III were higher compared with stages I, and II and also control group. The serum PBI level in stage IV was higher than stage II and the control group. In the patient and control groups, there were no significant differences in serum PBI and UIC with regard to age or sex. Our results suggested that urinary and blood iodine concentration might be a useful marker for following the disease.     

Expression cloning of cholesterol alpha-glucosyltransferase, a unique enzyme that can be inhibited by natural antibiotic gastric mucin O-glycans, from Helicobacter pylori

Helicobacter pylori infects over half the world's population, but only 3% of those infected develop peptic ulcer, gastric cancer, and mucosa-associated lymphoid tissue (MALT) lymphoma. In H. pylori, alpha-glucosyl cholesterol constitutes more than 25% of cell wall lipids, and it has been suggested that alpha-glucosyl cholesterol is essential for H. pylori viability. Here, we identified cholesterol alpha-glucosyltransferase (CHLalphaGcT) using an expression cloning strategy and showed that this enzyme is distinctively inhibited by mucin-type O-glycans similar to those present in deeper portions of the gastric mucosa. Moreover, inactivation of CHLalphaGcT by homologous recombination led to H. pylori lethality. These results indicate that H. pylori CHLalphaGcT is a unique enzyme targeted by a natural antibiotic mucin and constitutes an excellent therapeutic target to prevent H. pylori-induced peptic ulcer, gastric carcinoma, and MALT lymphoma.     

Isorhamnetin Inhibits Proliferation and Invasion and Induces Apoptosis through the Modulation of Peroxisome Proliferator-activated Receptor γ Activation Pathway in Gastric Cancer

Gastric cancer (GC) is a lethal malignancy and the second most common cause of cancer-related deaths. Although treatment options such as chemotherapy, radiotherapy, and surgery have led to a decline in the mortality rate due to GC, chemoresistance remains as one of the major causes for poor prognosis and high recurrence rate. In this study, we investigated the potential effects of isorhamnetin (IH), a 3′-O-methylated metabolite of quercetin on the peroxisome proliferator-activated receptor γ (PPAR-γ) signaling cascade using proteomics technology platform, GC cell lines, and xenograft mice model. We observed that IH exerted a strong antiproliferative effect and increased cytotoxicity in combination with chemotherapeutic drugs. IH also inhibited the migratory/invasive properties of GC cells, which could be reversed in the presence of PPAR-γ inhibitor. We found that IH increased PPAR-γ activity and modulated the expression of PPAR-γ regulated genes in GC cells. Also, the increase in PPAR-γ activity was reversed in the presence of PPAR-γ-specific inhibitor and a mutated PPAR-γ dominant negative plasmid, supporting our hypothesis that IH can act as a ligand of PPAR-γ. Using molecular docking analysis, we demonstrate that IH formed interactions with seven polar residues and six nonpolar residues within the ligand-binding pocket of PPAR-γ that are reported to be critical for its activity and could competitively bind to PPAR-γ. IH significantly increased the expression of PPAR-γ in tumor tissues obtained from xenograft model of GC. Overall, our findings clearly indicate that antitumor effects of IH may be mediated through modulation of the PPAR-γ activation pathway in GC.     

胃癌组织中幽门螺杆菌L型感染与淋巴管形成关系的研究

目的 研究胃癌组织中D2-40、LYVE-1标记的微淋巴管密度(LVD)、血管内皮生长因子受体(VEGFR-3)表达与幽门螺杆菌L型(helicobacter pylori L-form,Hp-L型)感染之间的关系.方法 应用革兰染色和免疫组化SP法检测80例胃癌组织和25例对照组的Hp-L型感染,同时用免疫组化SP法检测上述组织的LVD值和VEGFR-3的表达,分析Hp-L型与LVD以及VEGFR-3表达的关系结果 胃癌组织中革兰染色L型检出阳性率为67.5％;免疫组化Hp-L型抗原表达阳性率为65％,两种方法检测同时阳性的病例50例,占62.5％.胃癌组的Hp-L型阳性率、LVD及VEGFR-3表达阳性率均高于对照组(P＜0.01);胃癌组中Hp-L阳性组的LVD值和VEGFR-3表达阳性率高于Hp-L阴性组.LVD与胃癌淋巴结转移具有一定关系.结论 Hp-L型感染与胃癌的发生、发展密切相关,Hp-L型可能是肿瘤淋巴管生成的重要促进因子,影响胃癌的侵袭和转移.     

下丘脑室旁核注射GLP-1 对糖尿病大鼠中枢GLP-1 受体表达

目的:探讨下丘脑室旁核(hypothalamic paraventricular nucleus,PVN)注射GLP-1(胰高血糖素样肽-1)对糖尿病大鼠胃排空的影响及机制。方法:30只Wistar大鼠随机分为正常对照组(NC组)、糖尿病组(DM组)和GLP-1干预组(GLP-1组),每组各10只。DM组和GLP-1组腹腔注射链脲佐菌素,三组大鼠均PVN区埋置套管,恢复7d,GLP-1组微量注射0.5μg/0.5μl的GLP-1,NC组和DM组大鼠PVN区微量注射等体积生理盐水。甲基纤维素-酚红灌胃法检测胃排空;半定量RT-PCR检测大鼠下丘脑GLP-1RmRNA的表达。结果:DM组胃排空率较NC组明显升高(P<0.05),GLP-1组胃排空明显低于DM组(P<0.05),GLP-1组和NC组差异无统计学意义(P>0.05)。GLP-1组下丘脑GLP-1RmRNA的表达明显高于DM组和NC组(P<0.05),并与胃排空率成负相关(P<0.05)。DM组和NC组差异无统计学意义(P>0.05)。结论:PVN区注射GLP-1可以抑制糖尿病大鼠早期胃排空加速,作用机制可能和促进下丘脑GLP-1受体表达有关。     

胃癌SGC7901 表柔比星耐药细胞亚系的建立与耐药机制研究

目的:建立人胃癌SGC7901表柔比星耐药细胞系,探讨其对表柔比星的耐药机制。方法:采用逐步增加表柔比星浓度,间歇作用体外诱导法,建立人胃癌SGC7901表柔比星耐药细胞亚系SGC7901/EPI。用MTT法测定药物敏感性;流式细胞仪检测其药物排除能力和凋亡抵抗能力等生物学指标的改变,western blot检测相关蛋白的表达。结果:经过12个月建成人胃癌SGC7901表柔比星耐药细胞系SGC7901/EPI,其对表柔比星明显耐药,且对其他多种抗癌药具有不同程度的交叉耐药性,阿霉素蓄积潴留实验显示SGC7901/EPI的阿霉素含量明显低于亲本细胞,Western blot显示MRP1的表达上调;SGC7901/EPI凋亡抵抗能力明显上升,Bcl-2表达比亲本细胞增高,而Bax的表达下调。结论:SGC7901/EPI细胞具有多药耐药表型,其可能通过MRP1的上调增加药物排出和上调Bcl-2/Bax的比值促进凋亡抵抗等机制产生耐药。该胃癌多药耐药细胞亚系为进一步研究胃癌耐药机制及逆转方法奠定基础。     

miRNA 在胃癌中的作用及其在转化医学中的应用

转化医学是近年来提出的关于基础研究与临床密切结合的新概念,强调实现基础研究成果真正转化为临床实践,为疾病的诊断和治疗提供先进而有效的方法。胃癌是消化系统常见的恶性肿瘤,其早期诊断与治疗是转化医学研究的重点内容之一。microRNA(miRNA)是近年来发现的一类长约21-25个核苷酸的非编码单链小分子RNA,广泛存在于真核生物中。它的发现揭示了一种新的基因表达调控方式,为胃癌早期诊断与治疗的研究开辟了新路径。miRNA能够通过与靶基因特异性的结合使其降解或抑制其翻译,从而对靶基因进行转录后的表达调控。现有越来越多的研究发现,miRNA与了胃癌的发生、发展、治疗及预后都密切相关,此文从转化医学角度综述了miRNA在胃癌中对细胞周期、细胞凋亡、侵袭、转移、放化疗敏感性等的影响的研究进展。