Growth inhibition by adenosine 3',5-monophosphate derivatives does not require 3',5' phosphodiester linkage

Analogs of adenosine 3',5'-monophosphate (cyclic AMP) inhibit the growth of cultured cell lines. The effects of 8-bromo- and N6-butyryl-substituted analogs of cyclic and noncyclic AMP on six cell lines were examined and were equally inhibitory. Variant cell lines with altered cyclic AMP-dependent protein kinase were more resistant to both cyclic and noncyclic nucleotides. We conclude that growth inhibition by analogs of cyclic AMP (i) does not require a 3',5' phosphodiester bond and (ii) may be mediated by a pathway involving endogenous cyclic AMP.     

人乳腺癌细胞、结肠癌细胞和宫颈癌细胞生长曲线测定

为检测比较人乳腺细胞(MDA-MB-231、MCF-7、HBL-100)、人结肠癌细胞(HCT-8)和人宫颈癌细胞(HeLa)生长曲线的差异性.本实验首先常规培养MDA-MB-231、MCF-7、HBL-100、HCT-8和HeLa细胞,然后应用MTT方法测定这几种细胞的生长曲线.在本实验条件下,这几种细胞生长速度从高...     

Adenosine 3',5'-monophosphate waves in Dictyostelium discoideum: a demonstration by isotope dilution--fluorography

The distribution of adenosine 3',5'-monophosphate (cyclic AMP) in fields of aggregating amoebae of Dictyostelium discoideum was examined by a novel isotope dilution-fluorographic technique. Cellular cyclic AMP was visualized by its competition with exogenous 3H-labeled cyclic AMP for high-affinity binding sites on protein kinase immobilized on a Millipore filter used to blot the monolayer. The cyclic AMP was distributed in spiral or concentric circular wave patterns which centered on the foci of the aggregations. These patterns were correlated with those of cell shape change that propagate through the monolayers: cells in regions of high concentrations of cyclic AMP were elongated (presumably moving up a cyclic AMP gradient), whereas those in regions of low cyclic AMP concentrations were randomly directed. The highest cyclic AMP concentrations were about 10(-6)M. The widths of the regions of elevated cyclic AMP were about 0.3 to 1 millimeter which, assuming a wave velocity of 300 micrometers per minute, suggests that a cell signals for about 1 to 3 minutes. These observations support the hypothesis that the aggregation process in Dictyostelium is mediated by the periodic relay of cyclic AMP signals and suggest a simple scheme for the dynamics of the aggregation process.     

Direct interaction of a ligand for the erbB2 oncogene product with the EGF receptor and p185erbB2

The erbB2 oncogene encodes a 185-kilodalton transmembrane protein whose sequence is similar to the epidermal growth factor receptor (EGFR). A 30-kilodalton factor (gp30) secreted from MDA-MB-231 human breast cancer cells was shown to be a ligand for p185erbB2. An antibody to EGFR abolished the tyrosine phosphorylation induced by EGF and transforming growth factor-alpha (TGF-alpha) but only partially blocked that produced by gp30 in SK-BR-3 breast cancer cells. In two cell lines that overexpress erbB2 but do not expresss EGFR (MDA-MB-453 breast cancer cells and a Chinese hamster ovary cell line that had been transfected with erbB2), phosphorylation of p185erbB2 was induced only by gp30. The gp30 specifically inhibited the growth of cells that overexpressed p185erbB2. An antibody to EGFR had no effect on the inhibition of SK-BR-3 cell colony formation obtained with gp30. Thus, it appeared that gp30 interacted directly with the EGFR and erbB2. Direct binding of gp30 to p185erbB2 was confirmed by binding competition experiments, where gp30 was found to displace the p185erbB2 binding of a specific antibody to p185erbB2. The evidence described here suggests that gp30 is a ligand for p185erbB2.     

Transfection of v-rasH DNA into MCF-7 human breast cancer cells bypasses dependence on estrogen for tumorigenicity

The natural history of estrogen-responsive breast cancers often involves a phenotypic change to an estrogen-unresponsive, more aggressive tumor. The human breast cancer cell line, MCF-7, which requires estradiol for tumor formation in vivo and shows growth stimulation in response to estradiol in vitro, is a model for hormone-responsive tumors. The v-rasH onc gene was transfected into MCF-7 cells. The cloned MCF-7ras transfectants, which expressed the v-rasH messenger RNA and v-rasH p21 protein (21,000 daltons), were characterized. In contrast to the parental cell line, MCF-7ras cells no longer responded to exogenous estrogen in culture and their growth was minimally inhibited by exogenous antiestrogens. When tested in the nude mouse, the MCF-7ras cells were fully tumorigenic in the absence of estrogen supplementation. Thus, cells acquiring an activated onc gene can bypass the hormonal regulatory signals that trigger the neoplastic growth of a human breast cancer cell line.     

茶多酚与银杏叶提取物联用对人乳腺癌细胞增殖的影响

[目的]研究茶多酚与银杏叶提取物联合作用对人乳腺癌细胞MDA-MB-231增殖的影响。[方法]采用MTT法测定茶多酚、银杏叶提取物单独及联合应用对人乳腺癌细胞系MDA-MB-231的抑制作用;利用光镜观察茶多酚、银杏叶提取物对人乳腺癌系MDA-MB-231形态的影响。[结果]MTT法显示银杏叶提取物与低浓度（10、20μg/ml）的茶多酚联合使用,对乳腺癌细胞抑制率明显高于单独用药组,但是联合用药组只有在一定的浓度范围内才会产生协同作用抑制乳腺癌细胞增殖;在细胞形态方面,与单独用药组、对照组相比,联合用药组乳腺癌细胞生长状况差,折光性弱,贴壁细胞皱缩,变圆。[结论]银杏叶提取物在低浓度下对人乳腺癌细胞系MDA-MB-231生长无明显抑制作用,茶多酚和茶多酚联合银杏叶提取物均可抑制MDA-MB-231细胞生长,联合用药组强于单独用药,在一定浓度范围内起协同作用。     

转染抑癌基因PTEN对人乳腺癌ZR-75-1细胞的细胞周期和增殖能力的影响

目的：观察PTEN（phosphatase and tensin homology deleted on chromosome ten，第10号染色体上磷酸酶和张力蛋白同源缺失的基因）对人乳腺癌细胞ZR-75-1细胞增殖和细胞周期的影响。方法；利用脂质体介导法将携带有野生型和突变型PTEN cDNA的真核表达载体pBP—wt—PTEN和pBP—G129R—PTEN导八人乳腺癌ZR-75-1细胞（质粒转染成功后实验分为C—WT—PTEN组、CG129R—PTEN组和未转染质粒组即对照组）后，以RT—PCR、Western blot分析目的基因的表达，并采用MTT法和流式细胞术检测细胞增殖和细胞周期。结果：C—WT—PTEN组、C—G129R—PTEN组细胞PTEN mRNA及PTEN蛋白出现明显的高表达。C—WT—PTEN组细胞生长的抑制率可高达42．7％，与对照组比较．差异有显著性（P〈0．05）。但C—G129R—PTEN组细胞生长的抑制率与对照组比较，差异无显著性（P〉0．05）。流式细胞术显示C—WT—PTEN组细胞周期从G1期到S期已发生抑制。结论：野生型PTEN可依赖其磷酸酶活性抑制肿瘤细胞的增殖,并最终诱导细胞凋亡。     

茶氨酸衍生物TClC脂质体对雌激素受体阳性的 乳腺癌细胞生长和迁移的抑制作用

为研发抗癌新药,使用茶氨酸衍生物茶氯香酰胺TClC制备纳米脂质体(TClC-L),研究TClC-L对雌激素受体阳性的人乳腺癌MCF-7细胞生长和迁移的抑制作用,并深入探究可能的作用机制。分别采用MTT和Transwell chamber实验方法探究各浓度TClC-L对MCF-7细胞的生长和迁移的抑制作用;使用流式细胞术(FCM)检测TClC-L对MCF-7细胞凋亡的影响;应用Western blotting检测MCF-7细胞生长和迁移有关蛋白和酶的表达。实验结果显示,TClC-L对MCF-7细胞生长和迁移有显著的抑制、对癌细胞的凋亡表现促进作用;TClC-L明显下调受体蛋白p-VEGFR~2、Met和ER-α、抗凋亡蛋白Bcl-2、Cyclin D1、Akt和NF-?B的表达,上调促凋亡蛋白Bax、Caspase-3、p53和p21的表达。TClC-L作用的分子机制可能与抑制VEGFR/Met/ER-α-Akt/NF-?B信号传导通路有关。本研究显示了TClC-L有潜在的治疗雌激素受体阳性乳腺癌的作用。     

Receptor-associated resistance to growth hormone-releasing factor in dwarf "little" mice

Anterior pituitaries from the dwarf mouse strain "little" did not release growth hormone or accumulate adenosine 3',5'-monophosphate (cyclic AMP) in response to human and rat growth hormone-releasing factor (GRF). Dibutyryl cyclic AMP, as well as the adenylate cyclase stimulators forskolin and cholera toxin, markedly stimulated growth hormone (GH) release. The basis of the GH deficiency in the little mouse may therefore be a defect in an early stage of GRF-stimulated GH release related either to receptor binding or to the function of the hormone-receptor complex.     

黄芩苷通过上调miR-126诱导乳腺癌细胞凋亡的机制研究

目的 用黄芩苷干预人乳腺癌细胞株MDA-MB-231,观察黄芩苷对乳腺癌细胞增殖、凋亡的影响及作用机制。方法 用qRT-PCR检测miR-126的表达变化,Western-blot检测Bcl-2、Caspase-9、Caspase-3、p-p38和p53的表达,MTT法检测细胞增殖,流式细胞术检测细胞凋亡。结果 miR-126在乳腺癌MDA-MB-231细胞中的表达比正常乳腺细胞低,黄芩苷干预乳腺癌细胞后miR-126上调最为明显（P<0.05）。用miR-126 mimics、miR-126 inhibitors转染乳腺癌细胞,Western-blot显示黄芩苷及miR-126 mimics作用于人乳腺癌细胞后Bcl-2表达水平下降,Caspase-9和Caspase-3的裂解产物、p-p38、p53表达增加,差异有统计学意义（P<0.05）。MTT法显示黄芩苷和miR-126 均可抑制乳腺癌细胞的增殖,流式细胞术显示黄芩苷与miR-126 mimics促进癌细胞凋亡。结论 黄芩苷可以抑制乳腺癌细胞的增殖,促进其凋亡,其机制可能与通过上调miR-126调节凋亡相关基因有关。     

A chemoattractant receptor controls development in Dictyostelium discoideum

During the early stages of its developmental program, Dictyostelium discoideum expresses cell surface cyclic adenosine monophosphate (cyclic AMP) receptors. It has been suggested that these receptors coordinate the aggregation of individual cells into a multicellular organism and regulate the expression of a large number of developmentally regulated genes. The complementary DNA (cDNA) for the cyclic AMP receptor has now been cloned from lambda gt-11 libraries by screening with specific antiserum. The 2-kilobase messenger RNA (mRNA) that encodes the receptor is undetectable in growing cells, rises to a maximum at 3 to 4 hours of development, and then declines. In vitro transcribed complementary RNA, when hybridized to cellular mRNA, specifically arrests in vitro translation of the receptor polypeptide. When the cDNA is expressed in Dictyostelium cells, the undifferentiated cells specifically bind cyclic AMP. Cell lines transformed with a vector that expresses complementary mRNA (antisense) do not express the cyclic AMP receptor protein. These cells fail to enter the aggregation stage of development during starvation, whereas control and wild-type cells aggregate and complete the developmental program within 24 hours. The phenotype of the antisense transformants suggests that the cyclic AMP receptor is essential for development. The deduced amino acid sequence of the receptor reveals a high percentage of hydrophobic residues grouped in seven domains, similar to the rhodopsins and other receptors believed to interact with G proteins. It shares amino acid sequence identity and is immunologically cross-reactive with bovine rhodopsin. A model is proposed in which the cyclic AMP receptor crosses the bilayer seven times with a serine-rich cytoplasmic carboxyl terminus, the proposed site of ligand-induced receptor phosphorylation.     

Independent molecular pathways in initiation and loss of hormone responsiveness of breast carcinomas

These studies were set up to determine whether those oncogenes participating in the initiation of mammary carcinogenesis (for example, ras oncogenes) play a direct role in the outcome of events associated with the late stages of tumor development such as loss of hormone dependency. Mammary carcinomas induced by a single carcinogenic insult in pubescent rats was selected as an in vivo model system with direct relevance to human breast cancer. Acquisition of hormone-independent growth in these carcinogen-induced tumors was found to be independent of the activation of ras oncogenes during the early stages of carcinogenesis. In agreement with these observations, introduction of a human ras oncogene into human MCF-7 breast carcinoma cells did not abrogate their hormonal dependency for growth in vivo. These findings suggest that those events responsible for the critical stages of breast cancer development occur independently and in an uncoordinated manner.     

漆姑草石油醚提取物化学成分分析及抗肿瘤活性筛选

[目的]对漆姑草[Sagina japonica（Sw.）Ohwi]石油醚提取物的化学成分进行分析鉴定,并对其抗肿瘤活性进行研究。[方法]采用GC-MS联用技术分析漆姑草石油醚提取物的化学成分;选用3种人癌细胞株（人白血病K562细胞株、人宫颈癌Hela细胞株和人乳腺癌MCF-7细胞株）,采用MTT法和SRB法,对其抗肿瘤活性进行研究。[结果]从漆姑草石油醚提取物中分离鉴定出25种成分,其中脂肪酸含量最多,亚油酸含量达49.318%;漆姑草石油醚提取物对人白血病K562细胞株的生长具有微弱的抑制作用,对人宫颈癌Hela细胞株和人乳腺癌MCF-7细胞株均无抑制作用。[结论]该研究可为漆姑草资源在临床上的广泛应用奠定基础。     

Adenosine 3',5'-monophosphate modulates thyrotropin receptor clustering and thyrotropin activity in culture

A biologically active rhodamine conjugate of thyrotropin binds at 4 degrees C to diffusely distributed membrane thyrotropin receptors which patch and become endocytosed into thyroid cells in a temperature-sensitive process. When the cells are first incubated with 8-bromo-cyclic adenosine monophosphate at 37 degrees C, the conjugate also binds to clustered receptors at 4 degrees C. Furthermore, 8-bromo-cyclic adenosine monophosphate reduces the amount of adenosine 3',5'-monophosphate (cyclic AMP) induced by thyrotropin. Hence, increased intracellular cyclic AMP induces receptor patching and reduces the concentration of cyclic AMP normally induced by thyrotropin. This suggests that cyclic AMP acts both as the second messenger of thyrotropin and also as the regulator of the level of thyrotropin receptors.     

Adenosine 3'5'-monophosphate: inhibition of complement-mediated cell lysis

An increase in adenosine 3',5'-monophosphate (cyclic AMP) in rat mast cells, achieved by stimulating the cells with prostaglandin E(1), by preventing cyclic AMP breakdown with aminophylline, or by adding exogenous dibutyryl cyclic AMP, prevented complement-mediated cytolysis as assessed by both histamine release and vital dye exclusion. Dibutyryl cyclic AMP also suppressed water-induced osmotic lysis.     

番木瓜种子中异硫氰酸苄酯（BITC）的抑癌试验

利用MTT法检测番木瓜种子中的异硫氰酸苄酯(BITC)在体外对肝癌细胞等6种常见癌细胞的生长抑制率。结果表明,番木瓜种子提取物中BITC的浓度达到5μmol.L-1(相当于0.745mg.L-1)时,对人肝癌HepG2细胞、人肺癌A549细胞、人乳腺癌MCF-7细胞、人大肠癌HCT-8细胞、人宫颈癌HeLa细胞、人前列腺癌DU-145细胞的生长抑制率均达到70%以上,其中,人肝癌细胞HepG2最敏感,cBITC=2.5μmol.L-1时抑制率可达87%,在cBITC=10μmol.L-1和5.0μmol.L-1时,人大肠癌HCT-8细胞的生长抑制率几乎相同。因此,BITC具有良好的抑癌效果。     

茶氨酸衍生物茶溴香酰胺脂质体对人肺癌细胞 生长和迁移的抑制作用

为了探索研究茶氨酸衍生物茶溴香酰胺制备的脂质体(TBrC-L)对人非小细胞肺癌A549细胞生长和迁移的抑制作用与其分子机制,采用薄膜分散法制备了TBrC-L,通过MTT法检测不同浓度的TBrC-L对人肺癌A549细胞生长的抑制作用;使用流式细胞术检测TBrC-L对人肺癌A549细胞凋亡的诱导作用;利用Transwell chamber法观察TBrC-L对人肺癌A549细胞迁移作用的影响;应用蛋白质印迹法检测人肺癌A549细胞中与凋亡和生长密切相关蛋白的表达和药物可能的作用靶点。实验结果显示,TBrC-L对人肺癌A549细胞生长和迁移有显著的抑制作用,促进肿瘤细胞凋亡、抑制肿瘤细胞生长和迁移可能是其抗人肺癌作用的重要机制,其作用的分子机制涉及到抑制EGFR、VEGFR1、VEGFR~2和Met受体介导的Akt和NF-κB信号传导通路,本研究结果提示,TBrC-L具有应用于临床治疗和(或)辅助治疗人肺癌的潜力。     

Estrogen-induced factors of breast cancer cells partially replace estrogen to promote tumor growth

The hormone 17 beta-estradiol acts through its receptor system to induce MCF-7 human breast cancer cells to form tumors in athymic mice. In vitro studies have identified the production of estrogen-induced growth factors from MCF-7 cells that may have a role in growth control. These induced growth factors were sufficient to stimulate MCF-7 tumor growth in ovariectomized athymic mice, thus partially replacing estradiol. Growth factors may act as estrogen-induced "second messengers" in estrogen-responsive growth of human breast cancer.     

Selective reduction of forskolin-stimulated cyclic AMP accumulation by inhibitors of protein synthesis

Inhibiting protein synthesis by incubating C6-2B rat astrocytoma cells with cycloheximide or emetine for periods up to 24 hours caused a progressive decrease in the accumulation of adenosine 3',5'-monophosphate (cyclic AMP) when the cells were challenged for 30 minutes with 100 microM forskolin. In contrast, cholera toxin-stimulated (6 nM, 3 hours) cyclic AMP accumulation was not diminished in cycloheximide-treated cells, and cyclic AMP was only minimally diminished in response to a 30-minute challenge with 10 microM (-)-isoproterenol. These experiments suggest the presence of a previously unrecognized cyclase component, which is essential for forskolin-stimulated cyclic AMP accumulation and has a shorter half-life than the beta-adrenergic receptor, the guanine nucleotide regulatory proteins, or the cyclase catalytic component.