中药对恶性肿瘤细胞信号转导通路的影响及其作用机理研究的进展

细胞信号转导通路(cellular signal transduction pathway)是指细胞接受外界信号,通过一整套特定的机制,将胞外信号转导为胞内信号,终调节特定基因表达,并引起细胞的应答反应.

Stat3反义寡核苷酸对人胃腺癌MKN45细胞相关信号传导影响的研究

目的:通过研究Stat3反义寡核苷酸对人胃腺癌MKN45细胞增生活性的影响,寻求胃癌治疗中相关信号传导途径的新靶点.方法:Stat3反义寡核苷酸是一种混合骨架寡核苷酸(MBO),采用脂质体介导的方式将其转染人胃腺癌细胞株MKN45;通过MTT法观察转染前后对细胞增生状态的影响;凝胶阻滞电泳(EMSA)和Western blot方法观察转染前后Stat3DNA的结合活性和磷酸化Stat3蛋白表达的变化.结果:Stat3反义寡核苷酸对MKN45细胞的增生有明显抑制作用;转染反义寡核苷酸后MKN45细胞中Stat3信号的组成性激活水平和磷酸化Stat3蛋白的表达分别下降了50.65%及78.86%.结论:Stat3反义寡核苷酸能显著抑制MKN45细胞中Stat3信号的传导,胃癌细胞株中活化的Stat3信号可作为胃癌治疗新的分子靶点.

一氧化氮及其信号转导通路在糖尿病性勃起功能障碍的作用

勃起功能障碍(erectile dysfunction,ED)是糖尿病的常见并发症,影响人们的生活质量,其病变机理还不甚清楚.一氧化氮(NO)由一氧化氮合酶(NOS)合成,是调节海绵体肌肉松弛和阴茎勃起的重要的神经递质.PI3-kinase/Akt (PKB)通路使eNOS磷酸化,NO的产量增加;NO/cGMPPKG通路参与平滑肌的舒张;RhoA和Rho-kinase参与平滑肌的收缩,抑制eNOS基因表达和酶的活性.周围血管病变和自主神经变性是引起糖尿病性ED的主要原因之一.基因和干细胞(eNOS、 RhoA/Rho-kinase与Mesenchymal stem cell-based cell)治疗糖尿病性ED取得一些进展.

胃泌素的生物活性及其信号传导通路

胃泌素(Gastrin)是一种由消化道G细胞分泌的胃肠激素,对调节消化道功能和维持其结构完整具有重要作用.通过对其信号传导机制的研究,将有助于我们了解其生物学活性的本质.胃泌素是一类主要由胃肠道G细胞合成、释放的肽类激素.胃泌素的合成经历了前胃泌素(progastrin)、甘氨酸延伸型胃泌素(glycine-extended gastrin,G-Gly)和成熟胃泌素(gastrin amide)三个阶段.前两种胃泌素是胃泌素合成、加工过程中的中间产物,是未酰氨化的胃泌素(non-amidated gastrin,NAG),而成熟胃泌素是酰氨化胃泌素(amidatedgastrin).胃泌素家族成员既有各自的生物学活性,彼此之间也相互协调促进,共同发挥功能.众多学者对胃泌素发挥生物作用的细胞内信号传导通路进行了广泛而深入的研究.本文就胃泌素的合成释放、生物活性及信号传导通路作一综述.

供血白细胞活性不可逆丧失可以作为TA-GVHD的原因之一

Transfusion-asseciated gruft-versus-host disease(TA-GVHD) is usually a fatal outcome of blood transfusion therapy caused by viable leucocytes contained in the donor blood. Most cases of TA-GVHD occur when less than 4-d-old blood is transfused. We therefore examined the molecular changes that occur during storage that may account for the paucity of TA-GVHD following infusion of older blood. Leucocyte number and viability were essentially unchanged from freshly obtained blood, but the expression of cell-surface lymphocyte activation antigens(CD3,CD4,CD28,CD2,CD45) decreased rapidly within the first 24 h and continued to fall to less than 20% of original levels by d 9 of storage at 4℃. The decrease in CD antigen expression directly correlated with a decreasing ability to induce activation of the T-tymphocyte cellular signal transduction pathway. As a result, sells became less responsive in a mixed lymphocyte culture(MLC) by d 3, with abrogation of the MLC responsiveness by d 5. Donor leucocytes stored for 4 d or less at 4℃ were able to partially re-express. CD antiger and reconstitute, their signalling pathway when plaued at 37℃, where as those stored for more than 4 d were not. These irreversible changes result from a permanent down regulation of donor cell protein synthesis. These findings provide a mechanism to explain the paucity of TA-GVHD following transfusion of blood that is more than 4 d-old. Further study may show that aged blood provides additional assurances for the prevention of TA-GVHD; hoever, use of aged blood should not replace current protocols using irradiation.

The present study was undertaken to investigate the effect of human PMNs on the production of TNF-α by the human peripheral blood mononuclear cells (PBMCs) and to elucidate its tentative mechanism. Human PMNs and PBMCs were isolated from the venous blood of healthy donors by dextran sedimentation and density gradient centrifugation. In the presence of lipopolysaccharide (LPS), PMNs and PBMCs were cocultured at the ratio of 2:1 for 20 h and the concentration of TNF-α in the supernatant was measured by enzyme-linked immunosorbent assay. The binding rate of monocytes with the fluorescein isothiocyanate-labeled LPS (FITC-LPS) and the mean surface fluorescence intensity of monocytes were analyzed by flow cytometry. Results showed that PMNs were capable of inhibiting the TNF-α release from PBMCs (P＜0.05). PMNs suppressed the TNF-α release from PBMCs by 45% on average when PMNs and PBMCs cocultured at the ratio of 2:1. Paraformaldehyde-fixed PMNs still demonstrated the same inhibition (P＜0.05)，which proved that the inhibition was dependent on cell-to-cell contact and suggested that effector molecules responsible for this effect existed on the cell surface of PMNs. In the presence of PMNs, the binding rate of monocytes with the FITC-LPS and the mean surface fluorescence intensity of monocytes were not affected compared with PBMCs alone (P＞0.05). As incubation time was prolonged, the binding of FITC-LPS to monocytes increased (P＜0.05). Thus PMNs did not block the binding of LPS with monocytes. It was concluded that PMNs suppressed the TNF-α release from PBMCs via cell-to-cell interaction. In a cell-contact dependent manner, PMNs might interfere with the signal transduction pathway through which LPS activated PBMCs, thus attenuating the response of PBMCs to LPS and downregulating the TNF-α release.

The primary action of corticotropin releasing hormone (CRH) is stimulation of the synthesis and release of adrenocorticotropic hormone and β-endorphin from the pituitary in response to stress. In addition, a number of studies indicate that CRH exerts other physiological actions within the central nervous system which are independent of the pituitary. These include increased body temperature and thermogenesis. However, the intracellular mechanism responsible for pyrogenic action of CRH is still unclear. The purpose of these studies was to determine whether or not cAMP was involved in the pyrogenic action of CRH in the rat. Intracerebroventricular (icv) microinjection of CRH (2.5 μg, 5.0 μg, 10 μg) caused increases in colonic temperature and hypothalamus cAMP level in conscious rats. The pyrogenic effects of CRH were abolished or markedly inhibited by prior injection (icv) of an adenylate cyclase inhibitor, 2，，3，-dideoxyadenosine (DDA, 30 μg) or an inhibitor of cAMP-dependent protein kinase, adenosine-3，，5，-(cyclic) monophosphorothionate (Rp-cAMPs, 15 μg). This is the first report demonstrating the pyrogenic effcet of centrally administration of CRH on the rat via the cAMP-mediated protein kinase signal transduction pathway.