Synthesis and antiproliferative activity of two diastereomeric lignan amides serving as dimeric caffeic acid-l-DOPA hybrids

Two new diastereomeric lignan amides (4 and 5) serving as dimeric caffeic acid-l-DOPA hybrids were synthesized. The synthesis involved the FeCl₃-mediated phenol oxidative coupling of methyl caffeate to afford trans-diester 1a as a mixture of enantiomers, protection of the catechol units, regioselective saponification, coupling with a suitably protected l-DOPA derivative, separation of the two diastereomers thus obtained by flash column chromatography and finally global chemoselective deprotection of the catechol units. The effect of hybrids 4 and 5 and related compounds on the proliferation of two breast cancer cell lines with different metastatic potential and estrogen receptor status (MDA-MB-231 and MCF-7) and of one epithelial lung cancer cell line, namely A-549, was evaluated for concentrations ranging from 1 to 256 μM and periods of treatment of 24, 48 and 72 h. Both hybrids showed interesting and almost equipotent antiproliferative activities (IC₅₀ 64–70 μM) for the MDA-MB-231 cell line after 24–48 h of treatment, but they were more selective and much more potent (IC₅₀ 4–16 μM) for the MCF-7 cells after 48 h of treatment. The highest activity for both hybrids and both breast cancer lines was observed after 72 h of treatment (IC₅₀ 1–2 μM), probably as the result of slow hydrolysis of their methyl ester functions.     

Anticancer activity and SAR studies of substituted 1,4-naphthoquinones

In this paper, we report the structure–activity relationship studies of substituted 1,4-naphthoquinones for its anticancer properties. 1,4-Naphthoquinone, Juglone, Menadione, Plumbagin and LLL12.1 were used as lead molecules to design PD compounds. Most of the PD compounds showed improved antiproliferative activity in comparison to the lead molecule in prostate (DU-145), breast (MDA-MB-231) and colon (HT-29) cancer cell lines. PD9, PD10, PD11, PD13, PD14 and PD15 were found to be the most potent compound with an IC₅₀ value of 1–3 μM in all cancer cell lines. Fluorescent polarization assay was employed to study the inhibition of STAT3 dimerization by PD compounds. PD9 and PD18 were found to be potent STAT3 dimerization inhibitors.     

Anti-tumor activity of a new series of benzoxazepine derivatives in breast cancer

A series of new benzoxazepine derivatives substituted with different alkoxy and aryloxy group were synthesized comprising synthetic steps of Mitsunobu reaction, lithium aluminum hydride (LAH) reduction, followed by debenzylation and finally intramolecular Mitsunobu cyclization. The new benzoxazepines specifically inhibited growth of breast cancer cell lines, MCF-7 and MDA-MB-231, but lack cytotoxicity to normal HEK-293 cells. The cell growth inhibition induced by the active compounds was due to cell cycle arrest at G₀/G₁ phase. The active compound could cause significant reduction in tumor volume of MCF-7 xenograft tumor in nude mice model and their activity was comparable to that of tamoxifen citrate at 16 mg kg^?1 dose at 30 days of treatment. The identified most active compounds of the series have specific advantages as anti-cancer agent in breast cancer than tamoxifen.     

Anti-tumor activity of novel biisoquinoline derivatives against breast cancers

Breast cancer is classified into three groups according to its expression of hormone/growth factor receptors: (i) estrogen receptor (ER) and progesterone receptor (PR)-positive; (ii) human epidermal growth factor receptor 2 (HER2)-positive; and (iii) ER, PR, and HER2-negative (triple-negative). A series of methoxy-substituted biisoquinoline compounds have been synthesized as a potential chemotherapeutic agent for the triple-negative breast cancers which are especially challenging to manage. Structure activity relationship study revealed that rigid 6,6′-dimethoxy biisoquinoline imidazolium compound (1c, DH20931) exhibited the significant growth inhibitory effects on both triple-positive and triple-negative human breast cancer cell lines with IC₅₀ in the range of 0.3–3.9 μM. The 1c (DH20931) is more potent than structurally related noscapine for growth inhibition of MCF7 cell line (IC₅₀ = 1.3 vs 57 μM) and MDA-MB231 cell line (IC₅₀ = 3.9 vs 64 μM).     

Effects of iodonium-class flavin dehydrogenase inhibitors on growth,reactive oxygen production,cell cycle progression,NADPH oxidase 1 levels,and gene expression in human colon cancer cells and xenografts

Iodonium-class flavoprotein dehydrogenase inhibitors have been demonstrated to possess antiproliferative potential and to inhibit reactive oxygen production in human tumor cells, although the mechanism(s) that explains the relationship between altered cell growth and the generation of reactive oxygen species (ROS) remains an area of active investigation. Because of the ability of these compounds to inhibit the activity of flavoprotein-containing epithelial NADPH oxidases, we chose to examine the effects of several iodonium-class flavoprotein inhibitors on human colon cancer cell lines that express high, functional levels of a single such oxidase (NADPH oxidase 1, or Nox1). We found that diphenyleneiodonium (DPI), di-2-thienyliodonium (DTI), and iodonium diphenyl inhibited the growth of Caco2, HT-29, and LS-174 T colon cancer cells at concentrations (10–250 nM for DPI, 0.5–2.5 μM for DTI, and 155 nM to 10 μM for iodonium diphenyl) substantially lower than needed for DU145 human prostate cancer cells, which do not possess functional NADPH oxidase activity. Drug treatment was associated with decreased H₂O₂ production and diminished intracellular ROS levels, lasting up to 24 h, after short-term (1-h) exposure to the iodonium analogs. Decreased tumor cell proliferation was caused, in part, by a profound block in cell cycle progression at the G₁/S interface in both LS-174 T and HT-29 cells exposed to either DPI or DTI; and the G₁ block was produced, for LS-174 T cells, by upregulation of p27 and a drug concentration-related decrease in the expression of cyclins D1, A, and E that was partially prevented by exogenous H₂O₂. Not only did DPI and DTI decrease intracellular ROS, they both also significantly decreased the mRNA expression levels of Nox1, potentially contributing to the prolonged reduction in tumor cell reactive oxygen levels. We also found that DPI and DTI significantly decreased the growth of both HT-29 and LS-174 T human tumor xenografts, at dose levels that produced peak plasma concentrations similar to those utilized for our in vitro experiments. These findings suggest that iodonium analogs have therapeutic potential for NADPH oxidase-containing human colon cancers in vivo and that at least part of their antineoplastic mechanism of action may be related to targeting Nox1.     

Design,synthesis and biological evaluation of novel hydroxamic acids bearing artemisinin skeleton

A series of novel hydroxamic acids bearing artemisinin skeleton was designed and synthesized. Some compounds in this series exhibited moderate inhibition against the whole cell HDAC enzymes. Especially, compound 6g displayed potent cytotoxicity against three human cancer cell lines, including HepG2 (liver cancer), MCF-7 (breast cancer) and HL-60 (leukemia cancer), with IC₅₀ values of 2.50, 2.62 and 1.28 μg/mL, respectively. Docking studies performed with two potent compounds 6a and 6g using Autodock Vina showed that both compounds bound to HDAC2 with relatively high binding affinities from −7.1 to 7.0 kcal/mol compared to SAHA (−7.4 kcal/mol). It was found in this research that most of the target compounds seemed to be more cytotoxic toward blood cancer cells (HL-60) than liver (HepG2), and breast (MCF-7) cancer cells.     

Synthesis of novel forskolin isoxazole derivatives with potent anti-cancer activity against breast cancer cell lines

Forskolin C₁-isoxazole derivatives (3,5-regioisomers) (11a–e, 14, 15a–h and 15, 16a–g) were synthesized regioselectively by adopting 1,3-dipolar cycloadditions. These derivatives were tested using estrogen receptor positive breast cancer cell lines MCF-7 and BT-474. Majority of the compounds exhibited activity against the p53-positive MCF-7 breast cancer cells but not against the p53-negative BT-474 breast cancer cells. Among forskolin derivatives, compounds 11a, 11c, 14a, 14f, 14g, 14h, 15b, 16g and 17b exhibited higher anti-cancer activity against MCF-7 cell line with an IC₅₀ ≤ 1 µM. The derivative 14f exhibited highest activity in both p53-positive (MCF-7) and p53-negative (BT-474) breast cancer cell lines with an IC₅₀ of 0.5 µM.     

In vitro growth inhibitory effects of 13,28-epoxyoleanane triterpene saponins in cancer cells

Two new 13,28-epoxyoleanane triterpene saponins, magnosides A (1) and B (2), were isolated from the 95% ethanolic extract of Cybianthus magnus (Mez) Pipoly roots. Their structures were deduced by a combination of spectral analyses and chemical evidences as compared to data reported in the literature. The hemolytic activity of both compounds was measured. Compound 1 was shown to exhibit the strongest hemolytic activity with a HD₅₀ of 3.8 μM followed by 2 with a HD₅₀ of 33.5 μM. The bioactivity of compounds 1 and 2 was also evaluated in vitro against different cellular models including Mycobacterium tuberculosis, Leishmania amazonensis axenic amastigotes, mouse peritoneal macrophages and eight cancer cell lines. While neither of the tested compounds displayed any activity against M. tuberculosis, both exhibited anti-leishmanial activity against axenic amastigotes as well as in vitro growth inhibitory activity against all tested cancer cell lines with IC₅₀ growth inhibitory concentrations ranging between 4 μM and 33 μM. The compounds displayed similar growth inhibitory activity in cancer cell lines sensitive to pro-apoptotic stimuli versus those displaying various levels of resistance to such stimuli. Quantitative videomicroscopy analyses revealed that compounds 1 and 2 are cytotoxic.     

Anti-tumoral activity of imidazoquines,a new class of antimalarials derived from primaquine

The growth inhibitory activity of imidazoquines, antimalarial imidazolidin-4-ones derived from primaquine, on human cancer cell lines HT-29, Caco-2, and MCF-7 has been evaluated. Primaquine, N-dipeptidyl-primaquine derivatives, and other quinolines have been included in the study for comparison purposes. Primaquine and some of its derivatives were significantly active against the MCF-7 human breast cancer cell line, so these compounds might represent useful leads targeted at the development of novel specific agents against breast cancer. Conversely, all compounds were generally inactive against HT-29, with only one of the imidazoquines having IC₅₀ below 50 μM. Activities against the Caco-2 cell line were modest and did not follow any defined trend.     

Brassinosteroids cause cell cycle arrest and apoptosis of human breast cancer cells

Brassinosteroids (BRs) are plant hormones that appear to be ubiquitous in both lower and higher plants. Recently, we published the first evidence that some natural BRs induce cell growth inhibitory responses in several human cancer cell lines without affecting normal non-tumor cell growth (BJ fibroblasts). The aim of the study presented here was to examine the mechanism of the antiproliferative activity of the natural BRs 28-homocastasterone (28-homoCS) and 24-epibrassinolide (24-epiBL) in human hormone-sensitive and -insensitive (MCF-7 and MDA-MB-468, respectively) breast cancer cell lines. The effects of 6, 12 and 24 h treatments with 28-homoCS and 24-epiBL on cancer cells were surveyed using flow cytometry, Western blotting, TUNEL assays and immunofluorescence analyses. The studied BRs inhibited cell growth and induced blocks in the G₁ cell cycle phase. ER-α immunoreactivity was uniformly present in the nuclei of control MCF-7 cells, while cytoplasmic speckles of ER-α immunofluorescence appeared in BR-treated cells (IC₅₀, 24 h). ER-β was relocated to the nuclei following 28-homoCS treatment and found predominantly at the periphery of the nuclei in 24-epiBL-treated cells after 24 h of treatment. These changes were also accompanied by down-regulation of the ERs following BR treatment. In addition, BR application to breast cancer cells resulted in G₁ phase arrest. Furthermore, TUNEL staining and double staining with propidium iodide and acridine orange demonstrated the BR-mediated induction of apoptosis in both cell lines, although changes in the expression of apoptosis-related proteins were modulated differently by the BRs in each cell line. The studied BRs seem to exert potent growth inhibitory effects via interactions with the cell cycle machinery, and they could be highly valuable leads for agents for managing breast cancer.     

Lead optimization of COX-2 inhibitor nimesulide analogs to overcome aromatase inhibitor resistance in breast cancer cells

A series of COX-2 selective inhibitor nimesulide derivatives were synthesized. Their anti-cell proliferation activities were evaluated with a long-term estrogen deprived MCF-7aro (LTEDaro) breast cancer cell line, which is the biological model of aromatase inhibitor resistance for hormone-dependent breast cancer. Compared to nimesulide which inhibited LTEDaro cell proliferation with an IC₅₀ at 170.30 μM, several new compounds showed IC₅₀ close to 1.0 μM.     

Design,synthesis and antitumor activity of novel pyrazolo[3,4-d]pyrimidine derivatives as EGFR-TK inhibitors

A novel series of 2-(3,6-dimethyl-1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-4-yloxy)-N-(4-substitutedbenzylidene)acetohydrazide (12a–g) was prepared and their structures were confirmed by spectral and elemental analyses. The cytotoxic activity of the newly synthesized compounds was evaluated against breast carcinoma (MCF-7), non-small cell lung cancer (A549) and human colorectal adenocarcinoma (HT-29) cell lines using MTT and colony formation assays. The tested compounds showed a marked anticancer activity against all the tested cell lines, especially compound 12g, which was the most potent anticancer agent with half maximal inhibitory concentrations (IC₅₀) between 5.36 and 9.09 μM. Docking studies into ATP binding site of EGFR protein tyrosine kinase were performed to predict their scores and mode of binding to amino acids, In addition, the inhibitory activity of the target compounds against epidermal growth factor receptor tyrosine kinase (EGFR-TK) was evaluated. Results indicated the ability of the target compounds to inhibit EGFR-TK with half maximal inhibitory concentrations (IC₅₀) in the range of 4.18–35.88 μM. Furthermore, The most active compounds 12g, 12c and 12d were assayed against Fibroblast Growth Factor Receptor (FGFR), Insulin Receptor (IR) and Vascular Endothelial Growth Factor Receptor (VEGFR). The activity of the reported compounds warrants further optimization as novel members in cancer treatment protocols.     

Synthesis and cytotoxic potential of heterocyclic cyclohexanone analogues of curcumin

A series of 18 heterocyclic cyclohexanone analogues of curcumin have been synthesised and screened for their activity in both adherent and non-adherent cancer cell models. Cytotoxicity towards MBA-MB-231 breast cancer cells, as well as ability to inhibit NF-κB transactivation in non-adherent K562 leukemia cells were investigated. Three of these analogues 3,5-bis(pyridine-4-yl)-1-methylpiperidin-4-one B1, 3,5-bis(3,4,5-trimethoxybenzylidene)-1-methylpiperidin-4-one B10, and 8-methyl-2,4-bis((pyridine-4-yl)methylene)-8-aza-bicyclo[3.2.1]octan-3-one C1 showed potent cytotoxicity towards MBA-MB-231, MDA-MB-468, and SkBr3 cell lines with EC₅₀ values below 1 μM and inhibition of NF-κB activation below 7.5 μM. The lead drug candidate, B10, was also able to cause 43% of MDA-MB-231 cells to undergo apoptosis after 18 h. This level of activity warrants further investigation for the treatment of ER-negative breast cancer and/or chronic myelogenous leukemia as prototypical cellular models for solid and liquid tumors.     

3,3′-Diindolylmethane rapidly and selectively inhibits hepatocyte growth factor/c-Met signaling in breast cancer cells

3,3′-Diindolylmethane (DIM), an indole derivative from vegetables of the Brassica genus, has antiproliferative activity in breast cancer cells. Part of this activity is thought to be due to DIM inhibition of Akt signaling, but an upstream mechanism of DIM-induced Akt inhibition has not been described. The goals of this study were to investigate the kinetics of inhibition of Akt by physiologically relevant concentrations of DIM and to identify an upstream factor that mediates this effect. Here we report that DIM (5–25 μM) inhibited Akt activation from 30 min to 24 h in tumorigenic MDA-MB-231 cells but did not inhibit Akt activation in non-tumorigenic preneoplastic MCF10AT cells. DIM inhibited hepatocyte growth factor (HGF)-induced Akt activation by up to 46%, cell migration by 66% and cell proliferation by up to 54%, but did not inhibit induction of Akt by epidermal growth factor or insulin-like growth factor-1. DIM decreased phosphorylation of the HGF receptor, c-Met, at tyrosines 1234 and 1235, indicating decreased activation of the receptor. This decrease was reversed by pretreatment with inhibitors of p38 or calcineurin. Our results demonstrate the important role of HGF and c-Met in DIM's anti-proliferative effect on breast cancer cells and suggest that DIM could have preventive or clinical value as an inhibitor of c-Met signaling.     

Design and biological testing of peptidic dimerization inhibitors of human Hsp90 that target the C-terminal domain

BackgroundSmall molecules targeting the dimerization interface of the C-terminal domain of Hsp90, a validated target for cancer treatment, have yet to be identified.MethodsThree peptides were designed with the aim to inhibit the dimerization of Hsp90. Computational and biophysical methods examined the α-helical structure for the three peptides. Based on the Autodisplay technology, a novel flow cytometer dimerization assay was developed to test inhibition of Hsp90 dimerization. Microscale thermophoresis was used to determine the K_D of the peptides towards the C-terminal domain of Hsp90.ResultsMD simulations and CD spectroscopy indicated an α-helical structure for two of the three peptides. By flow cytometer analysis, IC₅₀ values of 2.08 μM for peptide H2 and 8.96 μM for peptide H3 were determined. Dimer formation of the C-terminal dimerization domain was analyzed by microscale thermophoresis, and a K_D of 1.29 nM was determined. Furthermore, microscale thermophoresis studies demonstrated a high affinity binding of H2 and H3 to the C-terminal domain, with a K_D of 1.02 μM and 1.46 μM, respectively.ConclusionsThese results revealed the first peptidic inhibitors of Hsp90 dimerization targeting the C-terminal domain. Furthermore, it has been shown that these peptides bind to the C-terminal domain with a low micromolar affinity.General significanceThese results can be used to design and screen for small molecules that inhibit the dimerization of the C-terminal domain of Hsp90, which could open a new route for cancer therapy.     

Discovery of N-(3-((7H-purin-6-yl)thio)-4-hydroxynaphthalen-1-yl)-sulfonamide derivatives as novel protein kinase and angiogenesis inhibitors for the treatment of cancer: Synthesis and biological evaluation. Part III

A novel series of N-(3-((7H-purin-6-yl)thio)-4-hydroxynaphthalen-1-yl)-sulfonamides were designed and synthesized. Biological characterization revealed that several compounds exerted enhanced anti-proliferative activity against human umbilical vein endothelial cells (HUVECs) and several cancer cell lines and high specific protein kinase and angiogenesis inhibitory activities. Compared with our previously synthesized compounds, the substitution of sulfonamide structure for amide fragment played an essential role for the advance of inhibitory activities. In addition, the replacement of 1H-1,2,4-triazole ring by 7H-purine did not result in obvious decrease of inhibition efficacy, indicating that the sulfonamide structure contributes even more to the inhibition efficacy than the 1H-1,2,4-triazole ring. Among these compounds, compound 9n demonstrated comparable in vitro antiangiogenic activities to pazopanib in both HUVEC tube formation assay and the rat thoracic aorta rings (TARs) test. Meanwhile, compound 9n was identified to inhibit Akt1 (IC₅₀ = 1.73 μM) and Abl tyrosine kinase (IC₅₀ = 1.53 μM) effectively.     

Benzo[b]furan derivatives induces apoptosis by targeting the PI3K/Akt/mTOR signaling pathway in human breast cancer cells

The PI3K/Akt/mTOR signaling pathway plays a key regulatory function in cell survival, proliferation, migration, metabolism and apoptosis. Aberrant activation of the PI3K/Akt/mTOR pathway is found in many types of cancer and thus plays a major role in breast cancer cell proliferation. In our previous studies, benzo[b]furan derivatives were evaluated for their anticancer activity and the lead compounds identified were 26 and 36. These observations prompted us to investigate the molecular mechanism and apoptotic pathway of these lead molecules against breast cancer cells. Benzo[b]furan derivatives (26 and 36) were evaluated for their antiproliferative activity against human breast cancer cell lines MCF-7 and MDA MB-231. These compounds (26 and 36) have shown potent efficiency against breast cancer cells (MCF-7) with IC₅₀ values 0.057 and 0.051 μM respectively. Cell cycle analysis revealed that these compounds induced cell cycle arrest at G2/M phase in MCF-7 cells. Western blot analysis revealed that these compounds inhibit the PI3K/Akt/mTOR signaling pathway and induced mitochondrial mediated apoptosis in human breast cancer cells (MCF-7).     

Flavonoid and cardenolide glycosides and a pentacyclic triterpene from the leaves of Nerium oleander and evaluation of cytotoxicity

A pentacyclic triterpene, oleanderocioic acid, two flavonoidal glycosides, quercetin-5-O-[α-l-rhamnopyranosyl-(1 → 6)]-β-d-glucopyranoside and kaempferol-5-O-[α-l-rhamnopyranosyl-(1 → 6)-β-d-glucopyranoside, and a cardenolide, oleandigoside, together with 11 known compounds, were isolated from the leaves of Nerium oleander. Their structures were elucidated on the basis of spectroscopic analysis. The growth inhibitory and cytotoxic activities of eight compounds were evaluated against the MCF-7 human breast cancer cell line using a sulforhodamine B assay. Three compounds, oleandrin, odoroside A and B were further assayed using a panel of 57 human cancer cell lines.     

Synthesis of novel substituted pyrimidine derivatives bearing a sulfamide group and their in vitro cancer growth inhibition activity

The synthesis of two series of novel substituted pyrimidine derivatives bearing a sulfamide group have been described and their in vitro cancer growth inhibition activities have been evaluated against three human tumour cell lines (HT-29, M21, and MCF7). In general, growth inhibition activity has been enhanced by the introduction of a bulky substituent on the aromatic ring with the best compound having GI₅₀ < 6 μM for all the human tumour cell lines. The MCF7 selective compounds were evaluated on four additional human invasive breast ductal carcinoma cell lines (MDA-MB-231, MDA-MB-468, SKBR3, and T47D) and were selective against T47D cell line in all cases except one, suggesting a potential antiestrogen activity.