基于PI3K/AKT信号通路研究丹酚酸B对成骨细胞骨形成的调控作用

目的探讨磷脂酰肌醇3激酶/蛋白激酶B(PI3K/AKT)信号通路在丹酚酸B对成骨细胞骨形成的调控作用。方法 0.00、0.01、0.03、0.10、0.30、1.00 nmol/L的丹酚酸B作用MC3T3-E1细胞12、24、36 h,MTT法检测细胞活力,RT-PCR法检测碱性磷酸酶(ALP)、骨桥蛋白(OPN)、Ⅰ型胶原蛋白(COLⅠ)、骨钙素(OCN)mRNA表达,Western印迹检测细胞中ALP、OPN、COLⅠ、OCN及PI3K/AKT信号通路相关蛋白的表达。结果与0.00 nmol/L比较,0.03、0.10、0.30 nmol/L丹酚酸B组细胞活力显著提高(P0.01),ALP、OPN、COLⅠ、OCN蛋白及mRNA表达量上调(P0.01),PI3K及p-AKT表达量上调(P0.01);而LY294002组ALP、OPN、COLⅠ及OCN蛋白及mRNA表达量下调(P0.01),PI3K及p-AKT表达量下调(P0.01)。与LY294002组比较,丹酚酸B+LY294002组ALP、OPN、COLⅠ、OCN蛋白及mRNA表达量上调(P0.01),PI3K及p-AKT表达量上调(P0.01)。结论丹酚酸B通过激活PI3K/AKT信号通路促进MC3T3-E1细胞骨形成。     

缺氧对人肝癌细胞株SMMC7721中HCCR表达的影响及其调控机制

背景：缺氧是实体瘤微环境的基本特征之一。人宫颈癌基因（HCCR）是新近发现的一种癌基因．在多种人类肿瘤中过表达。然而，尚缺乏HCCR在肿瘤缺氧环境中的表达及其调控机制的研究。目的：探讨缺氧对人肝癌细胞株SMMC7721中HCCR表达的影响及其调控机制。方法：SMMC7721细胞分别接受缺氧培养以及LY294002（P13K特异性抑制剂）和PD98059（MEK1特异性抑制剂）预处理＋缺氧培养，以蛋白质印迹法检测HCCR表达：将含HCCR启动子片段的荧光素酶报告基因质粒转染SMMC7721细胞，检测缺氧对HCCR启动子转录活性的影响。结果：缺氧环境下SMMC7721细胞中HCCR蛋白表达和转录活性均较常氧环境中升高，LY294002和PD98059可抑制缺氧环境下HCCR蛋白表达。结论：缺氧状态下人肝癌细胞株SMMC7721中HCCR蛋白表达和启动子转录活性增高。可能是肿瘤细胞在缺氧实体瘤组织中存活和快速增殖的重要机制之一。缺氧状态下HCCR蛋白表达受P13K／Akt和MAPK这两条信号通路的调节。     

非小细胞肺癌中PI3K/Akt信号通路通过Cdh1调控Skp2表达的机制研究

目的探讨非小细胞肺癌（NSCLC）中Cdc20同源蛋白1（Cdh1）参与磷脂酰肌醇三羟基激酶（PI3K）/Akt信号通路对S期激酶相关蛋白2（Skp2）表达调控的机制。方法体外培养NSCLC细胞系A549、LK2和H460,LY294002特异性阻断PI3K/Akt信号通路后,Western blot检测Skp2、Cdh1及p-Akt蛋白表达的变化,免疫荧光（IF）检测Cdh1在NSCLC中的定位变化。结果 LY294002处理后,与对照组相比3种细胞中Skp2蛋白表达和Akt磷酸化水平均降低（P〈0.01）,Cdh1在3种细胞的核内表达均增多。结论 NSCLC中PI3K/Akt信号通路抑制剂LY294002使Skp2蛋白表达下调与Cdh1由细胞质向细胞核转位有关。     

LY294002对人肺腺癌A549细胞p-Akt、VEGF表达的影响

目的 探讨PI3K抑制剂LY294002对肺腺癌A549细胞p-Akt及血管内皮生长因子(VEGF)表达的影响.方法 不同浓度LY294002(5μmol/L、10 μmol/L、20μmol/L、40 μnol/L)处理肺腺癌A549细胞24h后,分别用免疫细胞化学法和Western印迹法检测p-Akt、VEGF蛋白表达.结果 P13K抑制剂LY294002可抑制肺腺癌A549细胞株细胞中p-Akt蛋白的表达,而且其表达呈浓度依赖型降低(r=-0.913,P＜0.05).LY294002也可抑制该细胞株中VEGF蛋白的表达,其表达也呈浓度依赖型降低(r=-0.969,P＜0.01).结论 LY294002可抑制p-Akt活性及下调VEGF蛋白的表达,该作用可能是PI3K抑制剂LY294002发挥抗癌作用及抗血管生成的机制之一.     

LY294002联合AD-PTEN对脑胶质瘤细胞增殖和侵袭的影响及机制探讨

目的观察P13K抑制剂LY294002联合含VIEN基因的重组腺病毒（Ad—PTEN）对人脑胶质瘤TJ899细胞增殖和侵袭的影响,并探讨其机制。方法向TJ889分别加入LY294002（LY294002组）、Ad-PTEN＋LY294002（联合组）、Ad—vector病毒（空载组）、DMSO（DMSO组）培养48h。分别采用MTY法、流式细胞术、划痕实验和Tran．swell小室观察TJ899增殖活性和侵袭能力的变化;Western Blot检测TJ899的PTEN／P13K／AKT信号转导通路中相关蛋白。结果与DMSO组、空载组和LY294002组相比,联合组细胞存活速率下降,细胞周期阻滞在G0／G1期,S期减少,细胞凋亡率增加,侵袭和迁移的细胞数减少,PTEN蛋白表达增加,而磷酸化蛋白激酶B、细胞增殖抗原、细胞周期素D1、Bcl-2、基质金属蛋白酶-2、黏着斑激酶蛋白表达显著下降,P均〈0．05。结论LY294002联合Ad-PTEN可明显抑制TJ899的增殖活性和侵袭能力,该作用与抑制P13K／AKT信号通路有关。     

巨噬细胞游走抑制因子通过PI3K／Akt信号通路调控人结肠癌细胞株HT-29增殖和血管生成因子表达

背景：巨噬细胞游走抑制因子（MIF）是-种多功能细胞因子,其在结直肠癌发生、发展中的作用机制尚不明确。目的：探讨MIF是否通过P13K／Akt信号通路调控人结肠癌细胞增殖和血管生成因子表达。方法：人结肠癌细胞株HT-29分为对照组（RPMI-1640）、重组人MIF（rhMIF）组、PI3K抑制剂LY294002组和LY294002预处理联合rhMIF组,并予相应干预。以甲基噻唑基四唑（MTT）法检测HT-29细胞增殖状态,分别以逆转录聚合酶链反应（RT-PCR）和酶联免疫吸附测定（ELISA）检测血管内皮生长因子（VEGF）、白细胞介素-8（IL-8）mRNA表达和蛋白分泌,蛋白质印迹法检测Akt和磷酸化Akt（p—Akt）蛋白表达。结果：rhMIF对HT-29细胞具有促增殖作用,能增加细胞VEGF、IL-8 mRNA表达和蛋白分泌,并促进Akt蛋白磷酸化（P＜0．05）;而先予LY294002预处理可显著抑制rhMIF的上述作用．HT-29细胞增殖显著受抑（P＜0．05）,VEGF、IL-8mRNA表达、蛋白分泌以及p-Akt蛋白水平与对照组相比无明显差异。各组总Akt蛋白水平均无明显差异。结论：MIF诱导人结肠癌细胞增殖和血管生成因子表达可能是通过活化PI3K／Akt信号通路实现的。     

mTOR信号通路抑制剂和DNA甲基转移酶抑制剂对人胃癌细胞株Syk表达的影响

背景：哺乳动物雷帕霉素靶蛋白（roTOR）信号途径和DNA甲基化均参与肿瘤的发生、发展。脾酪氨酸激酶（Syk）是一种候选抑癌基因,与肿瘤发生有关。目的：研究mTOR信号通路抑制剂和DNA甲基转移酶抑制剂对人胃癌细胞株Syk表达的调控作用。方法：分别单独或联合应用mTOR抑制剂雷帕霉素（RAPA）、DNA甲基转移酶抑制剂5-氮杂-2’-脱氧胞苷（5-Aza—dC）、磷脂酰肌醇-3-激酶／丝苏氨酸蛋白激酶（P13K／Akt）抑制剂LY294002干预人胃癌细胞株MKN45和SGC7901,以细胞计数法检测细胞增殖能力,实时定量PCR法检测Syk表达情况,亚硫酸氢盐修饰后测序法检测DNA甲基化改变。结果：单独应用5-Aza—dC对细胞增殖抑制不明显,与RAPA、LY294002联合则显著抑制细胞增殖。单独应用5-Aza-dC可通过抑制DNA甲基化上调胃癌细胞的Syk表达,联合应用5-Aza—dc、RAPA和LY294002则显著上调Syk表达,但未进一步抑制DNA甲基化。结论：抑制mTOR信号通路可间接增强DNA甲基转移酶抑制剂上调Syk表达,从而抑制胃癌细胞生长。     

磷脂酰肌醇3-激酶/蛋白激酶B信号通路对CD40介导胃癌细胞侵袭与转移的研究

目的 探讨可溶性CD40配体(sCD40L)联合磷脂酰肌醇3-激酶/蛋白激酶B(P13K/Akt)信号通路特异性阻断剂LY294002对胃癌AGS细胞体外增殖及侵袭、转移的影响;初步探讨其可能的作用机制.方法 将细胞分成对照组(仅加入含10%胎牛血清的RPMI 1640培养液)、LY294002组(20μmol/L)、sCD40L组(2μg/ml)和LY294002+sCD40L组.四甲基偶氮唑盐法检测不同浓度sCD401,及联合LY294002对细胞增殖的影响;Transwell实验和划痕实验分析细胞侵袭、转移能力的改变;Western印迹检测细胞P13K、p-Akt、血管内皮生长因子(VEGF)蛋白表达的变化.结果 LY294002作用后细胞生存率为65.7%,sCD40L作用后为70.1%,LY294002+sCD40L组生存率为41.3 0A,差异有统计学意义(P<0.05).LY294002+sCD40L组细胞的划痕愈合速度较sCD40L和LY294002组明显减慢.LY294002+sCD40L组平均每个视野的细胞数较sCD40L和LY294002组明显减少.与对照组相比,sCD40L使P13K、p-Akt、VEGF蛋白表达升高,与LY294002联合作用后,P13K,p-Akt、VEGF蛋白表达明显降低.结论 阻断P13K/Akt信号途径可显著增强sCD40L对人胃癌AGS细胞增殖及侵袭、转移的抑制作用,为胃癌的生物治疗提供一种新的方法.     

Ad—PTEN对乳腺癌细胞系MCF-7生长抑制作用的影响及机制

目的探讨携带野生型PTEN基因的重组腺病毒（Ad—PTEN）和LY294002对乳腺癌细胞系MCF-7生长抑制作用的影响及机制。方法在MCF-7中导人Ad—PTEN和P13K抑制剂LY294002。Westem blotting法检测P11EN／P13K／AKT及其下游相关蛋白表达,M1Tr法检测MCF-7细胞存活率,流式细胞仪检测细胞周期,AnnexinV法检测细胞凋亡率。结果与DMSO组、空载病毒和LY294002组相比,联合组（LY294002＋Ad—PTEN）PTEN蛋白明显上调,而P13K／AKT及下游蛋白水平显著下降;联合组细胞阻滞于G0／C1期;细胞凋亡率增加明显;自培养第2天起,联合组细胞生存率呈下降趋势。结论Ad—PTEN联合LY294002通过阻滞细胞周期、促进细胞凋亡抑制MCF-7的增殖能力,两者具有正向协同作用;其机制可能与下调P13K／AKT信号通路下游蛋白有关。     

肺癌中PI3K／AKT信号通路对Skp2调控机制的研究

目的探讨肺癌中磷脂酰肌醇-3-激酶（P13K）／AKT信号通路对S期激酶相关蛋白2（Skp2）的调控机制。方法体外培养4种类型肺癌细胞系H460、LK2、H446和A549,经LY294002处理细胞24h后实时RT—PCR法检测Skp2基因表达变化;Westernblot检测E2F1蛋白表达变化。结果实时RT—PCR显示LY294002作用后4种肺肿瘤细胞系中skp2基因表达均下降;Westernblot结果表明在小细胞肺癌、肺鳞癌、大细胞肺癌中E2F1蛋白表达降低,肺腺癌中E2F1蛋白未表达。结论肺癌中P13K／AKT通路可在转录水平调节Skp2表达,在小细胞肺癌、肺鳞癌、大细胞肺癌中此种调节可能通过转录因子E2F1发挥作用,而肺腺癌中E2F1不参与此种调节。     

Three layer functional model and energy exchange concept of aging process

Relying on a certain degree of abstraction, we can propose that no particular distinction exists between animate or living matter and inanimate matter. While focusing attention on some specifics, the dividing line between the two can be drawn. The most apparent distinction is in the level of structural and functional organization with the dissimilar streams of ‘energy flow’ between the observed entity and the surrounding environment. In essence, living matter is created from inanimate matter which is organized to contain internal intense energy processes and maintain lower intensity energy exchange processes with the environment. Taking internal and external energy processes into account, we contend in this paper that living matter can be referred to as matter of dissipative structure, with this structure assumed to be a common quality of all living creatures and living matter in general. Interruption of internal energy conversion processes and terminating the controlled energy exchange with the environment leads to degeneration of dissipative structure and reduction of the same to inanimate matter, (gas, liquid and/or solid inanimate substances), and ultimately what can be called ‘death.’ This concept of what we call dissipative nature can be extended from living organisms to social groups of animals, to mankind. An analogy based on the organization of matter provides a basis for a functional model of living entities. The models relies on the parallels among the three central structures of any cell (nucleus, cytoplasm and outer membrane) and the human body (central organs, body fluids along with the connective tissues, and external skin integument). This three-part structural organization may be observed almost universally in nature. It can be observed from the atomic structure to the planetary and intergalactic organizations. This similarity is corroborated by the membrane theory applied to living organisms. According to the energy nature of living matter and the proposed functional model, the decreased integrity of a human body's external envelope membrane is a first cause of the structural degradation and aging of the entire organism. The aging process than progresses externally to internally, as in single cell organisms, suggesting that much of the efforts towards the restoration and maintenance of the mechanisms responsible for structural development should be focused accordingly, on the membrane, i.e., the skin. Numerous reports indicate that all parts of the human body, like: bones, blood with blood vessels, muscles, skin, and so on, have some ability for restoration. Therefore, actual revival of not only aging tissue of the human body's membrane, but the entire human body enclosed within, with all internal organs, might be expected. We assess several aging theories within the context of our model and provide suggestions on how to activate the body's own anti-aging mechanisms and increase longevity. This paper presents some analogies and some distinctions that exist between the living dissipative structure matter and inanimate matter, discusses the aging process and proposes certain aging reversal solutions.     

Unusual responses of nocturnal pineal melatonin synthesis and secretion to swimming: Attempts to define mechanisms

Abstract: The effect of swimming at night on rat pineal melatonin synthesis was compared with that of light exposure at night. Rats were forced to swim at 0030 hr (lights out at 2000 hr) and sacrificed by decapitation 15 and 30 min later, immediately after swimming. Other groups of animals were exposed to white light (650μW/cm²) for 15 and 30 min at same time. Swimming caused a rapid and highly significant drop in the melatonin content in the pineal gland; however, the activity of N-acetyltransferase (NAT), the supposed rate limiting enzyme in the melatonin production, was not changed. Despite the drop in pineal melatonin levels, serum concentrations of the indole remained elevated in the rats that swam. In contrast, melatonin levels in the pineal and serum of light exposed rats fell precipitously, accompanied by a significant suppression of NAT activity. Since we anticipated that the strenuous exercise associated with swimming may induce release of artrial natriuretic peptide (ANP) from the heart, which in turn could cause the release of pineal melatonin, in a second study we injected physiological saline intravenously to stretch the cardiac muscle and release ANP. Three milliliters of normal saline was injected during the day into the jugular vein of anesthetized rats that were pretreated with isoproterenol to stimulate pineal melatonin production. Animals were killed 15 min after the saline injection, and pineal NAT activity and pineal melatonin levels were measured. The saline injections caused no alteration in the elevated levels of either NAT or melatonin. These data suggest that the disparity in pineal NAT activity (which was high) and pineal melatonin (which was low), in animals swum at night, may not be caused by ANP which is released during strenuous exercise such as swimming.     

The immunoneuroendocrine role of melatonin

Abstract: A tight, physiological link between the pineal gland and the immune system is emerging from a series of experimental studies. This link might reflect the evolutionary connection between self-recognition and reproduction. Pinealectomy or other experimental methods which inhibit melatonin synthesis and secretion induce a state of immunodepression which is counteracted by melatonin. In general, melatonin seems to have an immunoenhancing effect that is particularly apparent in immunodepressive states. The negative effect of acute stress or immunosuppressive pharmacological treatments on various immune parameters are counteracted by melatonin. It seems important to note that one of the main targets of melatonin is the thymus, i.e., the central organ of the immune system. The clinical use of melatonin as an immunotherapeutic agent seems promising in primary and secondary immunodeficiencies as well as in cancer immunotherapy. The immunoenhancing action of melatonin seems to be mediated by T-helper cell-derived opioid peptides as well as by lymphokines and, perhaps, by pituitary hormones. Melatonin-induced-immuno-opioids (MHO) and lymphokines imply the presence of specific binding sites or melatonin receptors on cells of the immune system. On the other hand, lymphokines such as -γ-interferon and interleukin-2 as well as thymic hormones can modulate the synthesis of melatonin in the pineal gland. The pineal gland might thus be viewed as the crux of a sophisticated immunoneuroendocrine network which functions as an unconscious, diffuse sensory organ.     

Melatonin and photoperiodic time measurement: Seasonal breeding in the sheep

Abstract: Well-established circadian physiology supports the view that photoperiodic time measurement utilizes the coincidence between the presence of light and a photosensitive phase of a 'biological clock' to alter reproductive status—the so-called external coincidence model of seasonal breeding. In this review, we examine the mechanism whereby photoperiod interacts with presumed suprachiasmatic nuclei activity to allow endogenous melatonin to normally synchronize reproductive activity to the optimal time of year. The Romney Marsh sheep is particularly explored as an experimental model. It is suggested that the on/off activity of seasonal reproduction may be a robust mechanism able to be predictably manipulated by the judicious use of the light/dark cycle and exogenous melatonin, but firmly based on circadian principles.     

Response of rat pineal melatonin to calcium, magnesium, and lithium is circadian stage dependent

Abstract: Herein we documented the response of pineal melatonin production to electrolytes known to be effective on pineal function in view of a possible circadian stage dependence. We studied the release of melatonin by perifused rat pineal glands at 2 different circadian stages corresponding to the middle of the light and dark periods, i.e., respectively, 7 and 19 HALO (Hours After Light Onset, L:D = 12:12). The initial efflux rates were, as expected, much higher in the perifusates of glands removed from rats sacrificed during the dark phase than of those removed during the light phase. After 3 hr of perifusion, melatonin release reached similar levels which were found constant up to the 8th hr of perifusion, whatever the circadian stage. Perifusion of the glands with physiological concentrations for the rat of calcium (5.2 mmol/1) and magnesium (1.34 mmol/1) resulted in a stimulatory effect on the pineal glands removed from rats sacrificed in the middle of the dark period (19 HALO), whereas no effects were observed on the pineal glands removed from rats sacrificed during the light (7 HALO). Lithium (0.28 and 0.55 mmol/1) was ineffective on melatonin release in pineal glands removed 7 and 19 HALO. Our results show differences in the initial efflux rates of melatonin and in the response of perifused pineal glands to calcium and magnesium according to the circadian stage.     

Conservative management of perforated duodenal diverticulum： A case report and review of the literature

Duodenal diverticula are a relatively common condition. They are asymptomatic, unless they become complicated, with perforation being the rarest but most severe complication. Surgical treatment is the most frequently performed approach. We report the case of a patient with a perforated duodenal diverticulum, which was diagnosed early and treated conservatively with antibiotics and percutaneous drainage of secondary retroperitoneal abscesses. We suggest this method could be an acceptable option for the management of similar cases, provided that the patient is in good general condition and without septic signs.     

Changes in connexin43, the gap junction protein of astrocytes, during development of the rat pineal gland

Abstract: The abundance of gap junctions between rat pineal astrocytes formed by connexin43 (Cx43) was studied during development. Levels and distribution of Cx43 were measured by immunoblotting and indirect immunofluorescence, respectively. The amount of Cx43 in cells located within the gland was low until about the 7th postnatal day and increased to adult values between the 14th and 21st days postpartum. Although astrocytes, recognized by their vimentin immunoreactivity, were scarce before birth, they were abundant by the 7th postnatal day suggesting that the low levels of Cx43 found at this age corresponded to a low expression of this protein. Localization of the immunoreactivity to Cx43 and vimentin showed a close correlation, indicating that mature or immature pineal astrocytes form gap junctions made of Cx43. Since Cx43 levels attained their adult values at about the time the innervation and the functional state of the gland reached maturity (2–3 weeks after birth), it is proposed that astrocyte gap junctions are involved in the function of the adult rat pineal gland.