Estrogenic activity of zearalenone, α-zearalenol and β-zearalenol assessed using the E-screen assay in MCF-7 cells

Mycotoxins, including zearalenone (ZEA), can occur worldwide in cereals. They can enter the food chain and cause several health disorders. ZEA and its derivatives (α-zearalenol, α-ZOL and β-zearalenol, β-ZOL) have structural analogy to estrogen, thus they can bind to estrogen receptors (ERs). In order to characterize the estrogenic activity of ZEA, α-ZOL and β-ZOL, the proliferation of ER-positive human breast cancer cells (MCF-7) exposed to these mycotoxins was measured. After exposure at levels ranging from 6.25 to 25?µM, cell proliferation was evaluated by using the E-Screen bioassay. In accordance with previous studies, our results show the estrogenic activity of ZEA, α-ZOL and β-ZOL in MCF-7 cells. This effect is related to ZEA and its metabolites being flexible enough to bind to mammalian ERs. The relative proliferative effect (RPE) ranged from 10% to 91%. The α-ZOL induced the highest proliferative effect due to its higher affinity for the ERs compared to the other mycotoxins.     

Investigations on cellular proliferation induced by zearalenone and its derivatives in relation to the estrogenic parameters

Many man-made chemicals (pesticides) and naturally occurring compounds (mycotoxins and phytoestrogens) can enter the food chain and bind to estrogen receptors (ERs). Mycotoxins, including zearalenone (ZEA) and its derivatives, can occur worldwide in cereals and cause several health disorders. In order to characterize the estrogenic activity of zearalenone and its derivatives (alpha-zearalenol (alpha-ZEA), beta-zearalenol (beta-ZEA), alpha-zearalanol (alpha-ZAL) and beta-zearalanol (beta-ZAL)), the proliferation of ER-positive (MCF-7) and ER-negative (MDA-MB-231) human breast cancer cell lines was measured. After exposure at levels ranging from 0.1 pM to 0.1microM, cell proliferation (E-screen assay) was evaluated by MTT test through estrogenic parameters. On the MCF-7 cell line, estrogenic concentration that induced 50% cellular proliferation (EC(50)) of beta-zearalenol was statistically higher (5.2 x 10(-3)microM) than those of other zearalenone-related compounds, in agreement with other authors. All mycotoxins showed similar estrogenic parameters, with the exception of alpha-zearalenol that induced a higher proliferative effect (PE=2.6) and relative proliferative potency (RPP=7). Since MCF-7 contains both ERalpha and ERbeta-positive cells, at the mRNA and protein level, the estrogenic activity induced by mycotoxins may be ER-mediated, particularly through ERalpha that was the predominant ER subtype in these cells. A partial antagonism of mycotoxin-related estrogenic proliferation was seen when tamoxifen was used, confirming a receptor-dependent estrogenic response. MDA-MB-231 cells did not show ERs and after exposure to mycotoxins or 17beta-estradiol marginal PE values related to growth variability of MDA-MB-231 were found. Further studies are needed to understand in human tissues the mechanisms of action of ZEA and its derivatives that may be found as contaminants in the human diet.     

Synthesis and biological evaluation of novel prodrugs of anthracyclines for selective activation by the tumor-associated protease plasmin

New prodrugs of daunorubicin and doxorubicin designed for selective activation by the serine protease plasmin are described. The low toxic prodrugs 3, 4, and 5 are converted to the corresponding cytotoxic drugs upon proteolysis by the tumor-associated protease plasmin. Application of a self-eliminating spacer was essential for enzyme activation. A prodrug containing a chloro-substituted spacer was synthesized with the aim of enhancing the rate of conversion by plasmin. All prodrugs were highly stable in buffer solution and in serum and on the average 15-fold less cytotoxic than the parent drugs in seven human tumor cell lines. A marked in vitro selectivity was demonstrated by incubation of the doxorubicin prodrugs with a plasmin generating MCF-7 breast cancer cell line transfected with urokinase-type plasminogen activator (u-PA) in comparison with the nontransfected nonplasmin generating cell line. Prodrugs 4 and 5 showed the same cytotoxic effect as the free parent drug doxorubicin in the u-PA transfected cells, indicating complete conversion of the prodrug by plasmin. Addition of the plasmin inhibitor Trasylol drastically increased the ID(50) values in the u-PA transfected MCF-7 cells for both prodrugs 4 and 5.     

Stilbene-based inhibitors of estrone sulfatase with a dual mode of action in human breast cancer cells

Estrone sulfate (E1S) is an endogenous prodrug that delivers estrone and, subsequently, estradiol to target cells, after hydrolysis by the enzyme estrone sulfatase, which is active in various tissues including hormone-dependent breast cancer. Blockade of this enzyme should reduce the estrogen level in breast cancer cells and prevent hormonal growth stimulation. In this study, a number of sulfamoyloxy-substituted stilbenes with side chains that guarantee antiestrogenic activity were synthesized and evaluated as inhibitors of estrone sulfatase. They inhibited this enzyme in human MDA-MB 231 breast cancer cells, with IC(50) values in the submicromolar range. The effects of both the free hydroxy derivatives and the sulfamates on gene activation were determined in transfected MCF-7/2a breast cancer cells stimulated either with estradiol or with estrone sulfate. The analysis of data revealed a dual mode of action of the majority of compounds. They blocked gene expression by inhibition of estrone sulfatase and by antiestrogenic action. This pharmacological profile was also observed in assays on antiproliferative activity. The most potent derivative 8 g inhibited the growth of wild-type human MCF-7 cells with an IC(50) value of 13 nM.     

Synthesis and biological properties of a 1-(6-aziridinylhexyl)-2-phenylindole, a potential fluorescence label for estrogen receptors

2-Phenylindole derivative 8, linked to aziridine by a hexamethylene spacer group, was synthesized and tested. It binds to the estrogen receptor with an RBA-value of 4.0 (estradiol = 100). In vitro, it shows a selective cytostatic activity in hormone-dependent MCF-7 breast cancer cells (41% T/C at 10(-6) M). In vivo, it exerts a strong estrogenic effect. The binding to the estrogen receptor is largely reversible.     

Estrogen-anchored pH-sensitive liposomes as nanomodule designed for site-specific delivery of doxorubicin in breast cancer therapy

The present investigation reports the development of nanoengineered estrogen receptor (ER) targeted pH-sensitive liposome for the site-specific intracellular delivery of doxorubicin (DOX) for breast cancer therapy. Estrone, a bioligand, was anchored on the surface of pH-sensitive liposome for drug targeting to ERs. The estrone-anchored pH-sensitive liposomes (ES-pH-sensitive-SL) showed fusogenic potential at acidic pH (5.5). In vitro cytotoxicity studies carried out on ER-positive MCF-7 breast carcinoma cells revealed that ES-pH-sensitive-SL formulation was more cytotoxic than non-pH-sensitive targeted liposomes (ES-SL). The flow cytometry analysis confirmed significant enhanced uptake (p < 0.05) of ES-pH-sensitive-SL by MCF-7 cells. Intracellular delivery and nuclear localization of the DOX was confirmed by fluorescence microscopy. The mechanism for higher cytotoxicity shown by estrone-anchored pH-sensitive liposomal-DOX was elucidated using reactive oxygen species (ROS) determination. The in vivo biodistribution studies and antitumor activities of formulations were evaluated on tumor bearing female Balb/c mice followed by intravenous administration. The ES-pH-sensitive-SL efficiently suppressed the breast tumor growth in comparison to both ES-SL and free DOX. Serum enzyme activities such as LDH and CPK levels were assayed for the evaluation of DOX induced cardiotoxicity. The ES-pH-sensitive-SL accelerated the intracellular trafficking of encapsulated DOX, thus increasing the therapeutic efficacy. The findings support that estrone-anchored pH-sensitive liposomes could be one of the promising nanocarriers for the targeted intracellular delivery of anticancer agents to breast cancer with reduced systemic side effects.     

槲皮素、补骨脂素对乳腺癌细胞株MCF-7增殖的影响

目的探讨槲皮素(quercetin,Que)和补骨脂素(psor-alen,Pso)对人类乳腺癌细胞株增殖的影响。方法采用流式细胞术和蛋白印迹法检测槲皮素和补骨脂素对雌激素依赖性乳腺癌细胞MCF-7的影响,并以雌激素受体拮抗剂ICI182,780为工具药来评价槲皮素和补骨脂素发挥雌激素样作用与雌激素受体的关系。结果①槲皮素、补骨脂素在10μmol.L-1可使MCF-7细胞增殖指数明显升高,增加S期细胞的比例,与10-3μmon.L-1E2阳性对照组的变化趋势一致。当ICI182,780分别与E2、金雀异黄素、槲皮素、补骨脂素共孵育48 h后,E2、金雀异黄素、槲皮素、补骨脂素的增殖效应被抑制,细胞周期S期细胞数比例下降,G0/G1期细胞数比例上升。②10μmol.L-1槲皮素和10μmol.L-1补骨脂素均上调MCF-7细胞ERα蛋白水平,而对ERβ蛋白表达没有影响;当分别与ICI182,780共孵育MCF-7细胞ERα蛋白表达被拮抗。结论槲皮素和补骨脂素具有雌激素活性,此作用是通过雌激素受体(ER)介导的;产生的类似金雀异黄素促进MCF-7细胞增殖的作用是通过增加ERα表达实现的。     

Structure-activity relationships of nonisomerizable derivatives of tamoxifen: importance of hydroxyl group and side chain positioning for biological activity

The antiestrogen tamoxifen [(Z)-1(p-beta-dimethylaminoethoxy-phenyl)-1,2-diphenylbut-1-ene] is an effective anticancer agent against estrogen receptor (ER)-positive breast cancer. The alkylaminoethane side chain is essential for antiestrogenic activity, but the potency of the antiestrogen can be increased by para hydroxylation of the phenyl ring on carbon 1 of but-1-ene. This compound, 4-hydroxytamoxifen, is a metabolite of tamoxifen and has a very high binding affinity for ER [J. Endocrinol. 75:305-316 (1977)] because the hydroxyl is located in the equivalent position as the 3-phenolic hydroxyl of 17 beta-estradiol. In this study, we have examined the relationship between the relative positions of the hydroxyl and the alkyl-aminoethane side chain and the pharmacological activity of the ligand. A fixed seven-membered ring derivative of the triphenylethylene was used to prevent isomerization. All compounds were tested, with and without 17 beta-estradiol, for their effects on the growth of estrogen-responsive T47D and MCF-7 human breast cancer cells in vitro. The growth of MDA-MB-231 ER-negative breast cancer cells was not affected by any of the compounds tested, at a concentration (1 microM) that had a profound estrogenic or antiestrogenic action in ER-positive cell lines. The relative binding affinity of the compounds was determined using rat uterine ER and was found to be consistent with the observed potencies in vitro. The compounds found to be antiestrogens in vitro were antiestrogenic against estradiol (0.08 micrograms daily) in the 3-day immature rat uterine weight test. All compounds were partial agonists in vivo. In general, the estrogenic and antiestrogenic results obtained in vivo were consistent with the potency estimates obtained with the breast cancer cells in vitro. The results of this extensive structure-activity relationship study demonstrate that the substitution for 4-hydroxytamoxifen appears to be optimal to produce a potent antiestrogen; all other substitutions produced either estrogenic compounds or less potent antiestrogens. The hydroxyl group appears to be critical to locate the alkyl aminoethoxy side chain in the correct position in the steroid-binding site to block estrogen action. Novel antiestrogens were identified that could have been predicted based upon earlier drug-receptor models for the ER.     

Crucial Role of 3-Bromoethyl in Removing the Estrogenic Activity of 17β-HSD1 Inhibitor 16β-(m-Carbamoylbenzyl)estradiol

17β-Hydroxysteroid dehydrogenase type 1 (17β-HSD1) represents a promising therapeutic target for breast cancer treatment. To reduce the undesirable estrogenic activity of potent 17β-HSD1 inhibitor 16β-(m-carbamoylbenzyl)estradiol (1) (IC(50) = 27 nM), a series of analogues with a small functionalized side chain at position 3 were synthesized and tested. The 3-(2-bromoethyl)-16β-(m-carbamoylbenzyl)-estra-1,3,5(10)-trien-17β-ol (5) was found to be a potent inhibitor (IC(50) = 68 nM) for the transformation of estrone (E1) into estradiol (E2) and, most importantly, did not stimulate the proliferation of estrogen-sensitive MCF-7 cells, suggesting no estrogenic activity. From these results, the crucial role of a bromoalkyl side chain at carbon 3 was identified for the first time. Thus, this new inhibitor represents a good candidate with an interesting profile suitable for further studies including pharmacokinetic and in vivo studies.     

Growth factors and chemotherapeutic modulation of breast cancer cells

A variety of molecules including growth factors are involved in the metastasis of breast cancer cells to bone. We have investigated the effects of osteoblast derived growth factors, such as insulin-like growth factor-1 (IGF-1) and transforming growth factor beta-1 (TGF-beta1), on doxorubicin (adriamycin)-induced apoptosis and growth arrest of estrogen receptor positive (ER+) (MCF-7) and negative (ER-) (MDA-MB-435) breast cancer cell lines. Human breast normal epithelial (MCF-10A), breast cancer (MCF-7) and metastatic breast cancer (MDA-MB-435) cell lines were exposed to different doses of doxorubicin (0.1, 1 or 10 microM) at various exposure times (12, 24 or 48 h). The doxorubicin cytotoxicity was found to be higher in cancer cell lines (MDA-MB-435 and MCF-7) compared with normal breast epithelial cells (MCF-10A cells). Doxorubicin appeared to exert a blockade of MCF-7 and MDA-MB-435 cells at the G2/M phase, and induced apoptosis in MDA-MB-435 (29 +/- 4.2% vs 3.4 +/- 1.9% control) as assessed by flow cytometry, DNA fragmentation and terminal deoxynucleotidyl-transferase mediated deoxyuridine 5-triphosphate and biotin nick-end labelling (TUNEL) assays. Estradiol (E2) stimulated the growth of MCF-7 cells and increased the distribution of the cells at the G2/M and S phases. Exogenous IGF-1 partially neutralized the doxorubicin cytotoxicity in both cancer cell lines (MCF-7 and MDA-MB-435). Similarly, TGF-beta1 partially neutralized the doxorubicin cytotoxicity in MDA-MB-435 cells by reducing the number of cells at the 相似文献   

Synthesis and biological activity of the superestrogen (E)-17-oximino-3-O-sulfamoyl-1,3,5(10)-estratriene: x-ray crystal structure of (E)-17-oximino-3-hydroxy-1,3,5(10)-estratriene.

Steroid sulfatases regulate the formation of estrogenic steroids which can support the growth of endocrine-dependent breast tumors. Therefore, the development of potent steroid sulfatase inhibitors could have considerable therapeutic potential. Several such inhibitors have now been developed including estrone 3-O-sulfamate (EMATE, 1), which shows potent active site-directed inhibition. However, EMATE was subsequently shown to be also a potent estrogen. In an attempt to reduce the estrogenicity while retaining the potent sulfatase inhibitory properties associated with this type of molecule, (E)-17-oximino-3-O-sulfamoyl-1,3,5(10)-estratriene (5) (estrone oxime 3-O-sulfamate, OMATE) was synthesized. The X-ray crystal structure of (E)-17-oximino-3-hydroxy-1,3,5(10)-estratriene (4) (estrone oxime) demonstrated the presence of only one geometrical isomer [anti-isomer, (E)]. OMATE potently inhibited estrone sulfatase (E1-STS) activity and was similar to EMATE (>99% inhibition at 0.1 microM in MCF-7 breast cancer cells). It was also evaluated in vivo for its estrogenicity and ability to inhibit sulfatase activity. While it was equipotent with EMATE in vivo as a sulfatase inhibitor, it surprisingly had a stimulatory effect on uterine growth in ovariectomized rats about 1.5-fold greater than that of EMATE. Thus, OMATE possesses potential as a superestrogen and modification at C-17 is identified as a useful route for enhancement of estrogenicity in sulfamate-based estrogens.     

Review of estrone sulfatase and its inhibitors--an important new target against hormone dependent breast cancer

A high proportion (approximately 40%) of breast cancers are hormone dependent. The female hormones estradiol and androstenediol are believed to play a key role in the initiation and promotion of this disease. In the fight against hormone dependent breast cancers, extensive research has been undertaken to produce compounds which are potent inhibitors against the cytochrome P-450 enzyme aromatase (AR), which converts the C19 androgens to the C18 estrogens. However, the administration of AR inhibitors alone has failed to produce the expected decrease in plasma levels of estrone. The major impetus to the development of steroid sulfatase inhibitors has therefore been the realisation that in order to improve therapeutic response for women with hormone-dependent breast cancer, not only must the AR enzyme be inhibited, but also the synthesis of estrogens via alternative routes. The steroid sulfatase enzyme regulates the formation of estrone (which can subsequently be converted to the potent estrogen estradiol) from estrone sulfate, a steroid conjugate present in high concentrations in tissue and blood in women with breast cancer. The sulfatase enzyme system also controls the formation of dehydroepiandrosterone (DHEA) from the DHEA-sulfate. This is important since DHEA can be converted to 5-androstene-3 beta,17 beta-diol, which possesses estrogenic properties capable of stimulating the growth of breast cancer cells in vitro and in vivo. Considerable progress has been made in recent years in the development of a number of potent steroid/estrone sulfatase inhibitors, as such both steroidal and non-steroidal compounds have been considered and a number of highly potent inhibitors have been produced and evaluated against what is now considered a crucial enzyme in the fight against hormone dependent breast cancer. The review therefore considers the work that has been undertaken to date, as well as possible future development with respect to dual inhibitors of both estrone sulfatase and AR.     

Acetaminophen-induced proliferation of breast cancer cells involves estrogen receptors

Previous studies have shown that acetaminophen, a common analgesic/antipyretic, induces proliferation of cultured breast cancer cells containing both estrogen and progesterone receptors (ER+/PR+). The main objective of this study was to evaluate the involvement of ERs in this effect. First, the effects of therapeutic acetaminophen concentrations were compared in breast cancer cells with high ERs and in T47Dco cells with lower ERs, to determine if acetaminophen-induced proliferation depends on ER levels. Second, the effects of two antiestrogens (ICI 182,780 and 4'-hydroxytamoxifen) on acetaminophen-induced proliferation were determined in three human breast cancer cell lines: two ER+/PR+ (MCF7, T47D) and one ER-/PR- (MDA-MB-231). Third, ER binding assays were performed in MCF7 cells to determine if acetaminophen competed with estradiol for binding to ERs. Proliferation endpoints monitored included percent cells in the DNA synthesis phase of the cell cycle, 3H-thymidine incorporation into DNA, and cell number. Acetaminophen did not induce DNA synthesis in T47Dco cells, but did in cells with higher ER levels, suggesting high ER levels are necessary for acetaminophen to induce proliferation. Antiestrogens inhibited acetaminophen-induced proliferation in ER+/PR+ cells while no effects were observed in ER-/PR- cells, further supporting ER involvement. However, acetaminophen did not compete with estradiol for binding to ERs in ER+/PR+ cells. Collectively, these data suggest that acetaminophen induces breast cancer cell proliferation via ERs without binding to ERs like estradiol. The second purpose of this study was to determine if acetaminophen is estrogenic/antiestrogenic in vivo (uterotrophic assays). Acetaminophen has no antiestrogenic/estrogenic activity in mice or rats uteri.     

A dietary supplement for female sexual dysfunction, Avlimil, stimulates the growth of estrogen-dependent breast tumors (MCF-7) implanted in ovariectomized athymic nude mice.

Avlimil, a dietary supplement advertised to ameliorate female sexual dysfunction, is a mixture of eleven herbal components, and some herbal constituents of Avlimil (including black cohosh, licorice, red raspberry, red clover and kudzu) contain phenolic compounds, which are suggested to have estrogenic, anti-estrogenic, or androgenic potential for relieving menopausal symptoms. We hypothesize that Avlimil could modulate the growth of estrogen receptor positive human breast cancer (MCF-7) cells in vitro and in vivo. A dimethylsulfoxide (DMSO) extract of Avlimil (0.001-100 microg Avlimil powder equivalents/mL media) was tested for its estrogenic and anti-estrogenic effects on the growth of MCF-7 cells in vitro. We observed that the DMSO extract of Avlimil at low concentrations (0.1-50 microg/mL media) dose-dependently increased MCF-7 cell proliferation in vitro, and Avlimil DMSO extract at 100 microg/mL inhibited the growth of MCF-7 cells in vitro. Avlimil and some constituents (black cohosh and licorice roots) of Avlimil were fractionated by using sequential solvent extraction (hexane, ethyl acetate, and methanol) and the activities of the fractions were monitored by effects on the growth of MCF-7 cells. Depending on dosage (0.1-100 microg/mL media) both stimulatory and inhibitory effects of the extracts on the growth of MCF-7 cells were observed. The effect of dietary Avlimil at dosages approximating human intake was evaluated using ovariectomized mice implanted with MCF-7 cells. Animals were fed diets containing 500 ppm or 1000 ppm Avlimil for 16 weeks. Dietary Avlimil at 500 ppm stimulated MCF-7 tumors, but Avlimil at 1000 ppm had no apparent effect on the growth of MCF-7 tumors. The observation of stimulated tumor growth in the absence of uterine wet weight gains suggest that estrogenic/anti-estrogenic effects of Avlimil we observed may be dosage- and target tissue-specific and that Avlimil may not be safe for women with estrogen-dependent breast cancer. The different biological effects of fractionated Avlimil components and the different concentration dependencies warrant further compound identification and dose-response studies, especially at recommended intake levels that could have estrogenic effects in women.     

人参皂苷Rg_3对失巢凋亡耐受乳腺癌细胞MCF-7抑制作用

目的研究人参皂苷Rg3对失巢凋亡耐受的乳腺癌细胞MCF-7生长抑制作用。方法应用多聚2-羟乙基甲基丙烯酸酯(poly-hema)覆盖的细胞培养板,筛选出具有失巢凋亡耐受的乳腺癌细胞MCF-7,考察失巢凋亡耐受癌细胞的生长速率和侵袭力,并利用流式细胞仪检测人参皂苷Rg3对失巢凋亡耐受癌细胞MCF-7的周期分布和细胞凋亡。结果与阿霉素对照组相比,人参皂苷Rg3能显著抑制失巢凋亡耐受的乳腺癌细胞MCF-7的生长(P<0.01),并导致失巢凋亡耐受细胞MCF-7的G0/G1期细胞比例显著增加(P<0.05)。结论人参皂苷Rg3有效抑制失巢凋亡耐受的乳腺癌细胞MCF-7生长,其作用机制可能与人参皂苷Rg3使失巢凋亡耐受乳腺癌细胞MCF-7细胞周期停滞有关。     

塞来昔布联合多柔比星对乳腺癌细胞增殖及凋亡的影响

目的研究COX-2选择性抑制剂塞来昔布与多柔比星(doxorubicin,ADM)联合应用对乳腺癌MCF-7细胞和Sk-Br-3细胞的抗肿瘤作用,探讨塞来昔布是否对多柔比星具有减毒增效作用。方法实验分为对照组,塞来昔布组,多柔比星组和联合用药组。用MTT法检测药物对MCF-7细胞和Sk-Br-3细胞的生长抑制效应;Western blot测定MCF-7细胞和Sk-Br-3细胞bcl-2的表达;PI染色检测细胞凋亡;克隆形成法测定药物对MCF-7细胞和Sk-Br-3细胞系的细胞毒作用。结果 MTT结果显示,30μmol·L-1塞来昔布与0.625mg·L-1多柔比星联合作用于MCF-7细胞的72 h存活率为68.53%,作用于Sk-Br-3细胞的72 h存活率为32.66%,较多柔比星单用能明显降低乳腺癌细胞的存活率,且具有时间和剂量依赖性。流式细胞仪PI染色结果显示,联合用药诱导的细胞凋亡率分别为MCF-7细胞59.7%,Sk-Br-3细胞65.8%,较单用多柔比星诱导的凋亡率(MCF-7细胞25.9%,Sk-Br-3细胞28.7%)明显提高。Western blot结果显示单用多柔比星可以使蛋白bcl-2表达下调,合用后较单用下调更加明显。两者联合处理乳腺癌细胞后,caspases-3的活性明显增强。结论塞来昔布和多柔比星对乳腺癌MCF-7细胞和Sk-Br-3细胞有增殖抑制及促凋亡作用,两药联合表现为协同或相加作用。     

Probing the cysteine-34 position of endogenous serum albumin with thiol-binding doxorubicin derivatives. Improved efficacy of an acid-sensitive doxorubicin derivative with specific albumin-binding properties compared to that of the parent compound

We have recently proposed a macromolecular prodrug strategy for improved cancer chemotherapy based on two features (Kratz, F.; et al. J. Med. Chem 2000, 43, 1253-1256.): (a) rapid and selective binding of thiol-reactive prodrugs to the cysteine-34 position of endogenous albumin after intravenous administration and (b) release of the albumin-bound drug in the acidic environment at the tumor site due to the incorporation of an acid-sensitive bond between the drug and the carrier. To investigate this therapeutic strategy in greater depth, four (maleinimidoalkanoyl)hydrazone derivatives of doxorubicin were synthesized differing in the length of the aliphatic spacer (1, -(CH(2))(2)-; 2, -(CH(2))(3)-; 3, -(CH(2))(5)-; 4, -(CH(2))(7)-). The albumin-binding doxorubicin prodrugs, especially the (6-maleimidocaproyl)hydrazone derivative of doxorubicin (3), are rapidly and selectively bound to the cysteine-34 position of endogenous albumin. 3 was distinctly superior to the parent compound doxorubicin in three animal tumor models (RENCA, MDA-MB 435, and MCF-7) with respect to antitumor efficacy and toxicity.     

补骨脂素对人类乳腺癌细胞增殖作用的影响

目的研究补骨脂素(psoralen,Pso)对人类乳腺癌细胞株增殖的影响。方法采用噻唑蓝(MTT)比色法测定补骨脂素对雌激素依赖性乳腺癌细胞MCF-7和非雌激素依赖性乳腺癌细胞MDA-MB231的细胞增殖作用,并以雌激素受体拮抗剂ICI182,780为工具药来评价补骨脂素发挥雌激素样作用与雌激素受体的关系,流式细胞术对MCF-7细胞的增殖情况进行分析。结果与溶剂对照组相比较,Pso(10～40μmol.L-1)能明显促进MCF-7细胞的增殖,而对雌激素受体阴性MDA-MB231细胞未见影响,并将MCF-7细胞周期由G1期向S期推进,促进DNA合成,提高细胞分裂增殖指数,且Pso促进MCF-7细胞增殖作用被雌激素受体拮抗剂所拮抗。结论补骨脂素具有雌激素活性,此作用是通过雌激素受体(ER)介导的。