Characterization of in vitro and in vivo metabolic pathways of the investigational anticancer agent, 2-methoxyestradiol

Metabolite Profiling in Anticancer Drug Development: A Systematic Review

Drug metabolism is one of the most important pharmacokinetic processes and plays an important role during the stage of drug development. The metabolite profile investigation is important as the metabolites generated could be beneficial for therapy or leading to serious toxicity. This systematic review aims to summarize the research articles relating to the metabolite profile investigation of conventional drugs and herb-derived compounds for cancer chemotherapy, to examine factors influencing metabolite profiling of these drugs/compounds, and to determine the relationship between therapeutic efficacy and toxicity of their metabolites. The literature search was performed through PubMed and ScienceDirect databases up to January 2019. Out of 830 published articles, 78 articles were included in the analysis based on pre-defined inclusion and exclusion criteria. Both phase I and II enzymes metabolize the anticancer agents/herb-derived compounds . The major phase I reactions include oxidation/hydroxylation and hydrolysis, while the major phase II reactions are glucuronidation, methylation, and sulfation. Four main factors were found to influence metabolite formation, including species, gender, and route and dose of drug administration. Some metabolites were identified as active or toxic metabolites. This information is critical for cancer chemotherapy and anticancer drug development.

2-Methoxyestradiol and Its Combination with a Natural Compound, Ferulic Acid, Induces Melanoma Cell Death via Downregulation of Hsp60 and Hsp90

Melanoma is an aggressive type of skin cancer with one of the highest mortality rates. Notably, its incidence in the last few decades has increased faster than any other cancer. Therefore, searching for novel anticancer therapies is of great clinical importance. In the present study, we investigated the anticancer potential of 2-methoxyestradiol, potent chemotherapeutic, in the A375 melanoma cellular model. In order to furthermore evaluate the anticancer efficacy of 2-methoxyestradiol, we have additionally combined the treatment with a naturally occurring polyphenol, ferulic acid. The results were obtained using the melanoma A375 cellular model. In the study, we used MTT assay, flow cytometry, and western blot techniques. Herein, we have evidenced that the molecular mechanism of action of 2-methoxyestradiol and ferulic acid is partly related to the reduction of Hsp60 and Hsp90 levels and the induction of nitric oxide in the A375 melanoma cell model, while no changes were observed in Hsp70 expression after 2-methoxyestradiol and ferulic acid treatment separately or in combination. This is especially important in case of chemoresistance mechanisms because the accumulation of Hsp70 reduces induction of cancer cell death, thus decreasing antitumour efficacy.

2-Methoxyoestradiol impairs mouse embryo implantation via F-spondin

The anti-implantation effects of high oestradiol (E2) concentrations could be mediated by E2 metabolites. Herein, we examined whether 2-methoxyoestradiol (2ME) impairs embryo implantation via its target protein F-spondin. Mice on Day 3 of pregnancy were treated with E2 concomitantly with the cathecol-O-methyl transferase inhibitor OR486 and the number of implanted embryos was recorded 5 days later. The effect of 2ME or 4-methoxyoestradiol (4ME) on embryo implantation was also investigated. Plasma and uterine levels of 2ME were measured 0.5, 1 or 3h after E2 treatment while the mRNA for spondin 1 (Spon1) and F-spondin were determined in the uterus 3, 6, 12 or 24h after 2ME treatment. Finally, the effect of a neutralising F-spondin antibody on the anti-implantation effect of 2ME was explored. OR486 blocked the anti-implantation effect of E2; 2ME, but not 4ME, affected embryo implantation. The 2ME concentration was increased after 0.5 and 1h in plasma and 3h in uterine fluid following E2 treatment. 2ME increased levels of Spon1 at 12 and 24h although F-spondin was increased at 12h. F-spondin antibody blocked the effect of 2ME on embryo implantation. We conclude that 2ME impairs mouse embryo implantation via activation of F-spondin in the uterus.

Synthesis, molecular modeling and biological evaluation of potent analogs of 2-methoxyestradiol

The endogenous steroid 2-methoxyestradiol (1) has attracted a great interest as a lead compound towards the development of new anti-cancer drugs. Herein, the synthesis, molecular modeling, anti-proliferative and anti-angiogenic effects of ten 2-ethyl and four 2-methoxy analogs of estradiol are reported. The ethyl group was introduced to the steroid A-ring using a novel Friedel-Crafts alkylation protocol. Several analogs displayed potent anti-proliferative activity with IC₅₀-values in the submicromolar range towards the CEM human leukemia cancer cell line. As such, all of these compounds proved to be more active than the lead compound 2-methoxyestradiol (1) in these cells. The six most cytostatic analogs were also tested as anti-angiogenic agents using an in vitro tube formation assay. The IC₅₀-values were determined to be in the range of 0.1 μM ± 0.03 and 1.1 μM ± 0.2. These six compounds were also modest inhibitors against tubulin polymerization with the most potent inhibitor was 14b (IC₅₀ = 2.1 ± 0.1 μM). Binding studies using N,N'-ethylene-bis(iodoacetamide) revealed that neither14a or 14b binds to the colchicine binding site in the tubulin protein, in contrast to 2-methoxyestradiol (1). These observations were supported by molecular modeling studies. Results from a MDA-MB-231 cell cycle assay showed that both 10e and 14b gave accumulation in the G2/M phase resulting in induction of apoptosis. The results presented herein shows that the novel analogs reported exhibit their anticancer effects via several modes of action.

Identification and Growth Inhibitory Activity of the Chemical Constituents from Imperata Cylindrica Aerial Part Ethyl Acetate Extract

Imperata cylindrica (L.) Raeusch. (IMP) aerial part ethyl acetate extract has anti-proliferative, pro-apoptotic, and pro-oxidative effects towards colorectal cancer in vitro. The chemical constituents of IMP aerial part ethyl acetate extract were isolated using high-performance liquid chromatography (HPLC) and identified with tandem mass spectrometry (ESI-MS/MS) in combination with ultraviolet-visible spectrophotometry and 400 MHz NMR. The growth inhibitory effects of each identified component on BT-549 (breast) and HT-29 (colon) cancer cell lines were evaluated after 48/72 h treatment by MTT assay. Four isolated compounds were identified as trans-p-Coumaric acid (1); 2-Methoxyestrone (2); 11, 16-Dihydroxypregn-4-ene-3, 20-dione (3); and Tricin (4). Compounds (2), (3), and (4) exhibited considerable growth inhibitory activities against BT-549 and HT-29 cancer cell lines. Compounds (2), (3), and (4) are potential candidates for novel anti-cancer agents against breast and colorectal cancers.

The in vitro effects of a novel estradiol analog on cell proliferation and morphology in human epithelial cervical carcinoma

Background

The majority of novel chemotherapeutics target the cell cycle, aiming to effect arrest and cause apoptosis. One such agent, 2-methoxyestradiol (2ME), has been shown to possess anticancer properties against numerous cancer types, both in vitro and in vivo. Despite its promise, 2ME has exhibited limitations, including low oral bioavailability and rapid hepatic enzymatic inactivation in vivo. A novel sulphamoylated estrogen analog, 2-ethyl-3-O-sulphamoyl-estra-1,3,5(10)16-tetraene (ESE-16), was in silico-designed in our laboratory to overcome these issues. It was then synthesized by a pharmaceutical company and used in an in vitro antiproliferative effect study on a human cervical carcinoma (HeLa) cell line.

Results

Cell proliferation data obtained from the crystal violet assay and real-time cell analysis demonstrated that 0.2 μM of ESE-16 had a significant inhibitory effect on the HeLa cells 24 h post-exposure. Immunofluorescence showed that ESE-16 is a microtubule disruptor that causes cells to undergo a mitotic block. Qualitative morphological studies using polarization-optical transmitted light differential interference contrast (PlasDIC) and light microscopy revealed a decrease in cell density and an increase in the number of cells arrested in metaphase. After ESE-16 exposure, hallmarks of apoptosis were also observed, including membrane blebbing, chromatin condensation and the presence of apoptotic bodies. Flow cytometry provided quantitative results from cell cycle progression analysis, indicating cells undergoing apoptosis and cells in the G₂/M phase of the cell cycle, confirming cell cycle arrest in metaphase after ESE-16 treatment. Quantification of the ESE-16-mediated upregulation of cyclin B in HeLa cells and spectrophotometric and flow cytometric confirmation of cell death via apoptosis further confirmed the substance's impact.

Conclusion

ESE-16 exerts its antiproliferative effects through microtubule disruption, which induces a mitotic block culminating in apoptosis. This research provided information on ESE-16 as a potential antitumor agent and on cellular targets that could aid in the design of prospective microtubule-disrupting compounds. Further in vitro and in vivo investigations of this novel compound are needed.

Efficacy of Intravitreal injection of 2-Methoxyestradiol in regression of neovascularization of a retinopathy of prematurity rat model

Background

Retinopathy of prematurity (ROP) is one of the targets for early detection and treatment to prevent childhood blindness in world health organization programs. The purpose of study was to evaluate the efficacy of intravitreal injection of 2-Methoxyestradiol (2-ME) nanoemulsion in regressing neovascularization of a ROP rat model.

Methods

A prospective comparative case - control animal study conducted on 56 eyes of 28 healthy new born Sprague Dawley male albino rat. ROP was induced in 21 rats then two concentrations of 2-ME nanoparticles were injected in right eyes of 14 rats (low dose; study group I, high dose; study group II). A blank nanoemulsion was injected in the right eyes of seven rats (control positive group I). No injections performed in contralateral left eyes (control positive group II). Seven rats (14 eyes) were kept in room air (control negative group). On postnatal day 17, eyeballs were enucleated. Histological structure of the retina was examined using Hematoxylin and eosin staining. Vascular endothelial growth factor (VEGF) and glial fibrillary acidic protein (GFAP) expressions were detected by immunohistochemical studies.

Results

Intravitreal injection of 2-ME (in the two concentrations) caused marked regression of the new vascular tufts on the vitreal side with normal organization and thickness of the retina especially in study group II, which also show negative VEGF immunoreaction. Positive GFAP expression was detected in the control positive groups and study group (I).

Conclusion

Intravitreal injection of 2-Methoxyestradiol nanoemulsion is a promising effective method in reduction of neovascularization of a ROP rat model.

Electronic supplementary material

The online version of this article (doi:10.1186/s12886-017-0433-3) contains supplementary material, which is available to authorized users.

The Bone Sparing Effects of 2-Methoxyestradiol Are Mediated via Estrogen Receptor-α in Male Mice

2-Methoxyestradiol (2ME2), a metabolite of 17β-estradiol (E2), exerts bone sparing effects in animal models. We hypothesized that the underlying mechanism is back conversion of 2ME2 to E2, which subsequently acts via estrogen receptor (ER)α. We measured serum E2 levels in orchidectomized wild-type (WT) mice treated with 2ME2 66.6 μg/d or placebo. In placebo-treated animals, E2 was below the detection limit. In 2ME2-treated mice, the serum E2 level was 4.97 ± 0.68 pg/mL. This corresponds to the level found in diesterus in cycling female mice. Next, we investigated bone parameters in orchidectomized WT and ERα knockout mice treated with 2ME2 or placebo for 35 days. 2ME2 (6.66 μg/d) preserved trabecular and cortical bone in WT mice. Trabecular volumetric-bone mineral density was 64 ± 20%, and trabecular bone volume/total volume was 60 ± 20% higher in the metaphyseal region of the femur in the 2ME2 group, compared with placebo (P < .01). Both trabecular number and trabecular thickness were increased (P < .01). Cortical bone mineral content in the diaphyseal region of the femur was 31 ± 3% higher in the 2ME2 group, compared with placebo (P < .001). This was due to larger cortical area (P < .001). Three-point bending showed an increased bone strength in WT 2ME2-treated animals compared with placebo (maximum load [Fmax] +19±5% in the 2ME2 group, P < .05). Importantly, no bone parameter was affected by 2ME2 treatment in ERα knockout mice. In conclusion, 2ME2 treatment of orchidectomized mice results in increased serum E2. ERα mediates the bone sparing effects of 2ME2. The likely mediator of this effect is E2 resulting from back conversion of 2ME2.

Recent Advances in chemistry and pharmacology of 2-methoxyestradiol: An anticancer investigational drug

2-Methoxyestradiol (2ME2), an estrogen hormone metabolite is a potential cancer chemotherapeutic agent. Presently, it is an investigational drug under various phases of clinical trials alone or in combination therapy. Its anticancer activity has been attributed to its antitubulin, antiangiogenic, pro-apoptotic and ROS induction properties. This anticancer drug candidate has been explored extensively in last twenty years for its detailed chemistry and pharmacology. Present review is an update of its chemistry and biological activity. It also extends an assessment of potential of 2ME2 and its analogues as possible anticancer drug in future.

Inhibition of 2-methoxyestradiol glucuronidation by probenecid

Objectives

2-Methoxyestradiol (2ME2), a metabolite of estradiol, has antitumour activity in vitro. However, potential clinical applicability has been limited by low oral bioavailability. Probenecid was evaluated in vitro as an inhibitor of 2ME2 glucuronidation for purposes of enhancing 2ME2 oral bioavailability.

Methods

Human liver microsomes were used to determine kinetic parameters for transformation of 2ME2 to its glucuronide metabolites (M1, M2) and inhibition of the reactions by probenecid.

Key findings

M1 and M2 formation from 2ME2 proceeded with features of substrate inhibition. Probenecid inhibited metabolite formation, with mean inhibition constant (Ki) values of 0.9 and 2.6 mM, respectively. Inhibition was reversible, with mixed competitive–non-competitive characteristics.

Conclusion

The Ki values for probenecid inhibition of 2ME2 glucuronide formation, when compared to maximum probenecid plasma concentrations anticipated clinically, indicate that probenecid co-administration has the potential to augment systemic plasma levels of 2ME2 after oral dosage in humans.

Synthesis, cytotoxic effects and tubulin polymerization inhibition of 1,4-disubstituted 1,2,3-triazole analogs of 2-methoxyestradiol

Thirteen 1,4-disubstituted 1,2,3-triazole analogs of 2-methoxyestradiol were prepared and tested for their cytotoxic and tubulin polymerization inhibition effects. Two compounds, 11j and 11k, exhibited anti-proliferative effects at low micromolar concentrations. The two analogs 11j and 11k also inhibited tubulin assembly with IC50 values of 8.1 and 5.9μM, respectively.

2-methoxyestradiol and disorders of female reproductive tissues

2-Methoxyestradiol (2ME) is an endogenous metabolite of 17β-estradiol. Once thought of as a mere degradation product, 2ME has gained attention as an important component of reproductive physiology and as a therapeutic agent in reproductive pathologies such as preeclampsia, endometriosis, infertility, and cancer. In this review, we discuss the involvement of 2ME in reproductive pathophysiology and summarize its known mechanisms of action: microtubule disruption, inhibition of angiogenesis and stimulation of apoptosis. Currently, the clinical uses of 2ME as a single agent are limited due to its poor water solubility and thus low bioavailability; however, 2ME analogs and derivatives have been recently developed and tested as cancer treatments. Despite some isolated success stories and ongoing research, 2ME derivatives have not yet provided the expected results. The adjuvant use of 2ME derivatives with chemotherapeutic agents is hindered by their intrinsic toxicity confounding the unwanted secondary effects of chemotherapy. However, due to the well-tested tolerance of the body to high doses of native 2ME, it may the combination of native 2ME with conventional treatments that will offer novel clinically relevant regimens for cancer and other reproductive disorders.

Antitumor activity of CDA-Ⅱ, a urinary preparation, on human multiple myeloma cell lines via the mitochondrial pathway

Cell differentiation agent II (CDA‑II) is a DNA methyltransferase inhibitor isolated from healthy human urine. In the present study, the antitumor activity of CDA‑II on human multiple myeloma (MM) cell lines via the mitochondrial pathway was first revealed. The human MM cell lines were exposed to CDA‑II. Cytotoxicity, caspase activation, apoptosis and the effects on the mitochondrial pathway were assessed. CDA‑Ⅱ was capable of decreasing the depolarized mitochondrial membranes and activating caspase‑3 and ‑9 and poly (ADP‑ribose) polymerase in MM cells treated with CDA‑II. CDA‑II induced caspase‑dependent cell death accompanied by a significant decrease in X-linked inhibitor of apoptosis protein (XIAP), survivin and Mcl‑1 levels. The caspase‑3 inhibitor, Z‑DEVD‑FMK, inhibited CDA‑II‑induced apoptosis. CDA‑II potently increased the Bax levels, decreased the Bcl‑2/Bax ratio and decreased the expression of the downstream targets of NF‑κB. In conclusion, the results of the present study demonstrated that CDA‑II treatment leads to the inhibition of p65 nuclear localization and potently induces caspase‑dependent apoptosis in MM cells mediated through the mitochondrial pathway at low nanomolar concentrations. These results indicate that CDA‑II is a novel inhibitor of NF‑κB activity, with notable antimyeloma efficacy. This study provides a rationale for the clinical investigation of CDA‑Ⅱ in human MM.

Synthesis of sex hormone-derived modified steroids possessing antiproliferative activity

During recent years intensive research has been focused on the synthesis of structurally modified steroid hormones in order to obtain compounds with beneficial biological activity such as cell-growth inhibition. Experimental results have revealed that some steroidal derivatives possess direct cytostatic effect on cancer cells in a hormone receptor-independent manner. After a brief account on the most important biological function and characteristics of the naturally occurring sex hormones in physiological and pathological conditions, structural modifications of estrane and androstane scaffolds are discussed in detail. The review covers literature publications (from 2002 to 2012) relating to the synthesis and antiproliferative activity of semisynthetic sex hormone-derived molecules containing simple or heterocyclic substituents. The compounds reviewed are divided into three main categories according to their sterane framework and the nature of substitution. This article is part of a Special Issue entitled "Synthesis and biological testing of steroid derivatives as inhibitors".

Assessing the regioselectivity of OleD-catalyzed glycosylation with a diverse set of acceptors

To explore the acceptor regioselectivity of OleD-catalyzed glucosylation, the products of OleD-catalyzed reactions with six structurally diverse acceptors flavones- (daidzein), isoflavones (flavopiridol), stilbenes (resveratrol), indole alkaloids (10-hydroxycamptothecin), and steroids (2-methoxyestradiol)-were determined. This study highlights the first synthesis of flavopiridol and 2-methoxyestradiol glucosides and confirms the ability of OleD to glucosylate both aromatic and aliphatic nucleophiles. In all cases, molecular dynamics simulations were consistent with the determined product distribution and suggest the potential to develop a virtual screening model to identify additional OleD substrates.

Therapeutic promises of 2-methoxyestradiol and its drug disposition challenges

2-Methoxyestradiol (2MeO-E2) is an endogenous metabolite of estrogen which was initially considered to be inactive. During the last few decades it has been shown that 2MeO-E2 is a promising anticancer drug. In vitro experiments have demonstrated that it has several anticancer activities, and potential to alleviate hypertension, glomerulosclerosis, hypercholesterolemia, and other disorders. However, due to its low solubility and extensive glucuronidation, to achieve effective concentrations large doses of 2MeO-E2 would be required. Clinical studies reflected very high inter- and intrapatient variability and oral bioavailability of 1 to 2%. Thus, this review paper highlights the origin of this compound, its therapeutic promises, and possible mechanisms of action. It also discusses the pharmacokinetic properties of 2MeO-E2 as well as current developments to overcome low drug solubility and its extensive first pass metabolism.

Uridine 5'-diphospho-glucuronosyltransferase genetic polymorphisms and response to cancer chemotherapy

Pharmacogenetics aims to elucidate how genetic variation affects the efficacy and side effects of drugs, with the ultimate goal of personalizing medicine. Clinical studies of the genetic variation in the uridine 5'-diphosphoglucuronosyltransferase gene have demonstrated how reduced-function allele variants can predict the risk of severe toxicity and help identify cancer patients who could benefit from reduced-dose schedules or alternative chemotherapy. Candidate polymorphisms have also been identified in vitro, although the functional consequences of these variants still need to be tested in the clinical setting. Future approaches in uridine 5'-diphosphoglucuronosyltransferase pharmacogenetics include genetic testing prior to drug treatment, genotype-directed dose-escalation studies, study of genetic variation at the haplotype level and genome-wide studies.

Potential vascular actions of 2-methoxyestradiol

2-Methoxyestradiol (2-ME) is a biologically active metabolite of 17beta-estradiol that appears to inhibit key processes associated with cell replication in vitro. The molecule has been suggested to have potent growth-inhibitory effects on proliferating cells, including smooth muscle cells and endothelial cells, and may be antiangiogenic. Because of these potential roles for 2-ME, its lack of cytotoxicity and low estrogenic activity, we hypothesize that 2-ME could be a valuable therapeutic molecule for prevention and treatment of cardiovascular diseases. Whether 2-ME is as effective in vivo as it is in vitro at modulating vascular processes remains controversial. Here we discuss recent developments regarding mechanisms by which 2-ME might regulate vascular activity and angiogenesis and speculate on the therapeutic implications of these developments.

Synthesis and antitumor activities of 3-modified 2-methoxyestradiol analogs

The syntheses of 2-methoxyestradiol analogs with modifications at the 3-position are described. The analogs were assessed for their antiproliferative, antiangiogenic, and estrogenic activities. Several lead substituents were identified with similar or improved antitumor activities and reduced metabolic liability compared to 2-methoxyestradiol.

Synthesis of 2- and 17-substituted estrone analogs and their antiproliferative structure-activity relationships compared to 2-methoxyestradiol

A novel series of 17-modified and 2,17-modified analogs of 2-methoxyestradiol (2ME2) were synthesized and characterized. These analogs were designed to retain or potentiate the biological activities of 2ME2 and have diminished metabolic liability. The analogs were evaluated for antiproliferative activity against MDA-MB-231 breast tumor cells, antiangiogenic activity in HUVEC, and estrogenic activity on MCF-7 cell proliferation. Several analogs were evaluated for metabolic stability in human liver microsomes and in vivo in a rat cassette dosing model. This study lead to several 17-modified analogs of 2ME2 that have similar or improved antiproliferative and antiangiogenic activity, lack estrogenic properties and have improved metabolic stability compared to 2ME2.

Phase I trial of 2-methoxyestradiol NanoCrystal dispersion in advanced solid malignancies

PURPOSE

2-methoxyestradiol (2ME2; Panzem) is an endogenous, estradiol-17beta metabolite that at pharmacologic doses exerts antimitotic and antiangiogenic activities. Studies with a 2ME2 capsule formulation showed limited oral bioavailability. We report the results of a phase I study using a NanoCrystal Dispersion formulation of 2ME2 (2ME2 NCD).

EXPERIMENTAL DESIGN

Patients with refractory solid tumors received 2ME2 NCD orally. Patients received drug either every 6 hours (part A) or every 8 hours (part B). Doses were escalated in successive cohorts until the maximum tolerated dose (MTD) was identified. The primary objective was identifying the MTD. Secondary objectives were to evaluate the plasma pharmacokinetics of 2ME2 and efficacy.

RESULTS

In part A, 16 patients received a median of 4 cycles of 2ME2 NCD. Dose-limiting toxicities (DLT) included fatigue (2), hypophosphatemia (2), increased alanine aminotransferase (1), and muscle weakness (1). Trough levels at steady-state reached the minimum effective concentration in all cohorts. The MTD was determined to be 1,000 mg orally every 6 hours. In part B, 10 patients received a median of 1 cycle. DLTs included elevated gamma-glutamyltransferase (1), hyponatremia (1), fatigue (1), and anorexia (1). An MTD could not be defined for part B because 4 of 10 patients had DLTs at the initial dose level and dose reduction was not pursued. Thirteen patients had stable disease (A, 11; B, 2); there were no confirmed responses.

CONCLUSION

For 2ME2 NCD, the MTD and recommended phase II regimen is 1,000 mg orally every 6 hours. Treatment was generally well-tolerated.

Significant antitumor activity in vivo following treatment with the microtubule agent ENMD-1198

Clinical studies using the microtubule-targeting agent 2-methoxyestradiol (2ME2; Panzem) in cancer patients show that treatment is associated with clinical benefit, including prolonged stable disease, complete and partial responses, and an excellent safety profile. Studies have shown that 2ME2 is metabolized by conjugation at positions 3 and 17 and oxidation at position 17. To define structure-activity relationships for these positions of 2ME2 and to generate metabolically stable analogues with improved anti-tubulin properties, a series of analogues was generated and three lead analogues were selected, ENMD-1198, ENMD-1200, and ENMD-1237. These molecules showed improved metabolic stability with >65% remaining after 2-h incubation with hepatocytes. Pharmacokinetic studies showed that oral administration of the compounds resulted in increased plasma levels compared with 2ME2. All three analogues bind the colchicine binding site of tubulin, induce G(2)-M cell cycle arrest and apoptosis, and reduce hypoxia-inducible factor-1alpha levels. ENMD-1198 and ENMD-1200 showed improved in vitro antiproliferative activities. Significant reductions in tumor volumes compared with vehicle-treated mice were observed in an orthotopic breast carcinoma (MDA-MB-231) xenograft model following daily oral treatment with all compounds (ANOVA, P < 0.05). Significantly improved median survival time was observed with ENMD-1198 and ENMD-1237 (200 mg/kg/d) in a Lewis lung carcinoma metastatic model (P < 0.05). In both tumor models, the high-dose group of ENMD-1198 showed antitumor activity equivalent to that of cyclophosphamide. ENMD-1198 was selected as the lead molecule in this analogue series and is currently in a phase I clinical trial in patients with refractory solid tumors.

CDA-II, a urinary preparation, induces growth arrest and apoptosis of human leukemia cells through inactivation of nuclear factor-kappaB in a caspase-dependent manner

CDA-II (cell differentiation agent II) was a urinary preparation, isolated from healthy human urine. We determined the anticancer activity of CDA-II using human acute myeloid leukemia (AML) cell lines, K562, Kasumi-1 and KG-1. An in vitro cytotoxicity assay showed that CDA-II exhibited growth arrest in leukemic cells, while it did not induce cytotoxicity in normal peripheral blood mononuclear cells (PBMCs). In vivo studies using the Kasumi-1 xenografted SCID mouse model showed tumor inhibition rate were increased and the survival time were prolonged in a dose-dependent manner, without any significant toxicity on mice body. Depolarized mitochondrial membranes and the activation of caspase-3, 9 as well as PARP were found in leukemic cells treated with CDA-II for 6-24h. We further found NF-kappaB nuclear translocation were prevented by CDA-II treatment, which therefore inactivated NF-kappaB and down-regulated its target genes expression, including Bcl-2/Bax ratio, Mcl-1 and XIAP. The caspase-3 inhibitor Z-DEVD-FMK inhibited CDA-II-induced apoptosis and CDA-II combined with NF-kappaB inhibitor PDTC significantly increased the apoptotic rate of leukemic cells. We concluded that CDA-II potently induced caspase-dependent leukemia-specific apoptosis in leukemic cells mediated through inactivation of NF-kappaB, involving in Bcl-2 family and XIAP, which has no cytotoxicity on normal cells.

Synthesis and structure-activity relationships of 16-modified analogs of 2-methoxyestradiol

A series of 16-modified 2-methoxyestradiol analogs were synthesized and evaluated for antiproliferative activity toward HUVEC and MDA-MB-231 cells, and for susceptibility to conjugation. In addition, the estrogenicity of these analogs was accessed by measuring cell proliferation of the estrogen-dependent cell line MCF7 in response to compound treatment. It was observed that antiproliferative activity dropped as the size of the 16 substituent increased. Selected analogs tested in glucuronidation assays had similar rates of clearance to 2-methoxyestradiol, but had enhanced clearance in sulfonate conjugation assays.