Synthesis and biological evaluation of selective aromatase expression regulators in breast cancer cells

Design, Synthesis and Cytotoxicity of New Coumarin-1,2,3-triazole Derivatives: Evaluation of Anticancer Activity and Molecular Docking Studies

A library of new coumarin-1,2,3-triazole hybrids 7a-l were synthesized from 4-(diethylamino)-2-hydroxybenzaldehyde precursor through a series of reactions including Vilsmeier-Haack reaction and condensation reaction to achieve key intermediate oxime and further performed click reaction by using different aromatic azides. We screened all molecules in silico against crystal structure of Serine/threonine-protein kinase 24 (MST3), based on these results all molecules were screened for their cytotoxicity against human breast cancer MCF-7 and lung cancer A-549 cell lines. Compound 7 b (p-bromo) showed best activity against both cell lines MCF-7 and A-549 with IC50 value of 29.32 and 21.03 μM, respectively, in comparison to Doxorubicin corresponding IC50 value of 28.76 and 20.82 μM. Another compound 7 f (o-methoxy) also indicated good activity against both cell lines with IC50 value of 29.26 and 22.41 μM. The toxicity of all compounds tested against normal HEK-293 cell lines have not shown any adverse effects.

Synthesis of 2'-Deoxyuridine Modified with a 3,5-Difluoro-4-Methoxybenzylidene Imidazolinone Derivative for Incorporation into Oligonucleotide Probes for Detection of HER2 Breast Cancer Marker

Nucleoside intercalator conjugates (NICs) describe an innovative methodology developed in our research group for preparation of fluorescence turn-on DNA hybridization probes targeting specific mRNA sequences (e.g., breast cancer markers). In this methodology, we conjugate a non-fluorescent intercalator to the base of a nucleic acid (e.g., uracil) via a flexible spacer. This modified monomer can be incorporated into oligonucleotides by solid-phase synthesis and a large fluorescence enhancement is observed when the modified oligonucleotide is hybridized with its complementary strand due to intercalation of the fluorophore between the two strands. 5-(6-p-Methoxybenzylidene imidazolinone-1-hexene)-2'-deoxyuridine (dU^MBI ) is a synthetic monomer to which 4-methoxybenzylidene imidazolinone (MBI), the fluorescent chromophore of green fluorescent protein (GFP), has been conjugated via a flexible spacer. The detection of human epidermal growth factor receptor 2 (HER2) mRNA by this probe has already been established by our group. The fluorescent intensity of the single-strand DNA can be considered as negligible due to the free rotation of the fluorophore. Upon hybridization, however, the flexible spacer allows for the intercalation of the fluorophore between the hybridized strands, giving rise to enhanced fluorescence and indicating the presence of target mRNA. 3,5-Difluoro-4-methoxybenzylidene (DFMBI) has enhanced photophysical properties compared to MBI fluorophore. This protocol describes a simple, reliable, efficient, and general method for the synthesis of improved derivative dU^DFMBI as a monomer of fluorescent turn-on DNA hybridization probe with application for detection of HER2 mRNA. © 2020 by John Wiley & Sons, Inc. Basic Protocol: Synthesis of 5-[(6)-3,5-difluoro-4-methoxybenzylidene imidazolinone-1-hexene]-2'-deoxyuridine.

Nimesulide analogues: From anti-inflammatory to antitumor agents

Nimesulide is a nonsteroidal anti-inflammatory drug possessing analgesic and antipyretic properties. This drug is considered a selective cyclooxygenase-2 (COX-2) inhibitor and, more recently, has been associated to antitumor activity. Thus, numerous works have been developed to modify the nimesulide skeleton aiming to develop new and more potent and selective COX-2 inhibitors as well as potential anticancer agents. This review intends to provide an overview on analogues of nimesulide, including the general synthetic approaches used for their preparation and structural diversification and their main anti-inflammatory and/or antitumor properties.

Triarylethylene-indolin-2,3-dione molecular conjugates: design, synthesis, docking studies and anti-proliferation evaluation

A series of 1H-1,2,3-triazole-linked ospemifene-isatin and O-methylated ospemifene–isatin conjugates were synthesized and assayed for their anti-proliferative activities against estrogen-responsive as well as estrogen-non-responsive cells. The non-cytotoxic conjugate 14e, with an optimal combination of bromo substituents at the C-5/C-7 positions of isatin, proved to be a promising hit with an IC₅₀ value of 31.62 μM against MCF-7 and 19.23 μM against MDA-MB-231. The observed anti-proliferative activities of active conjugates were further corroborated via docking studies carried out on estrogen receptor subtypes α and β.

A series of 1H-1,2,3-triazole-linked ospemifene–isatin and O-methylated ospemifene–isatin conjugates were synthesized and assayed for their anti-proliferative activities against estrogen-responsive as well as estrogen-non-responsive cells.

Synthesis, computational studies and antiproliferative activities of coumarin-tagged 1,3,4-oxadiazole conjugates against MDA-MB-231 and MCF-7 human breast cancer cells

A novel library of coumarin tagged 1,3,4 oxadiazole conjugates was synthesized and evaluated for their antiproliferative activities against MDA-MB-231 and MCF-7 breast cancer cell lines. The evaluation studies revealed that compound 9d was the most potent molecule with an IC₅₀ value of <5 µM against the MCF-7 cell line. Interestingly, compounds 10b and 11a showed a similar trend with lower inhibitory concentration (IC₅₀ = 7.07 µM), in Estrogen Negative (ER-) cells than Estrogen Positive (ER+) cells. Structure-activity relationship (SAR) studies revealed that conjugates bearing benzyl moieties (9b, 9c and 9d) had superior activities compared to their alkyl analogues. The most potent compound 9d showed ∼1.4 times more potent activity than tamoxifen against MCF-7 cell line; while the introduction of sulfone unit in compounds 11a, 11b and 11c resulted in significant cytotoxicity against both MCF-7 and MDA-MB-231 cell lines. These results were further supported by docking studies, which revealed that the stronger binding affinity of the synthesized conjugates is due to the presence of sulfone unit attached to the substituted benzyl moiety in their pharmacophores.

Synthesis and biological evaluation of anti-cancer agents that selectively inhibit Her2 over-expressed breast cancer cell growth via down-regulation of Her2 protein

Compound JCC76 selectively inhibited the proliferation of human epidermal growth factor 2 (Her2) over-expressed breast cancer cells. In the current study, a ligand based structural optimization was performed to generate new analogs, and we identified derivatives 16 and 17 that showed improved activity and selectivity against Her2 positive breast cancer cells. A structure activity relationship (SAR) was summarized. Compounds 16 and 17 were also examined by western blot assay to check their effect on Her2 protein. The results reveal that the compounds could decrease the Her2 protein, which explains their selectivity to Her2 over-expressed breast cancer cells. Furthermore, the compounds inhibited the chaperone activity of small chaperone protein that could stabilize Her2 protein.

Design, synthesis, anti-proliferative evaluation and docking studies of 1H-1,2,3-triazole tethered ospemifene–isatin conjugates as selective estrogen receptor modulators

A library of 1H-1,2,3-triazole-tethered ospemifene–isatin and ospemifene–spiroisatin conjugates have been synthesized and evaluated for their anti-proliferative activities against MCF-7 and MDA-MB-231 cell lines.

Ibuprofen reduces zebrafish PGE(2) levels but steroid hormone levels and reproductive parameters are not affected

Prostaglandins are important regulators of reproductive function in fish. Analgesics like aspirin and ibuprofen are prostaglandin inhibitors and have been detected in freshwater systems at ng/L-μg/L levels. We investigated whether ibuprofen would affect prostaglandin and sex steroid hormone levels in adult zebrafish (Danio rerio) and if expression levels of genes involved in steroidogenesis and prostaglandin synthesis were affected. Zebrafish were exposed to moderate concentrations of ibuprofen (21, 201 or 506 μg/L) for 7 days in a semi-static test system. Ibuprofen concentrations were close to nominal levels and decreased by a maximum of 12-13% over 24 h. Prostaglandin E(2) (PGE(2)) levels in whole body homogenates of males and ovaries of females decreased in a monotonic dose-response relationship whereas male 11-ketotestosterone levels and ovarian 17β-estradiol levels remained unchanged. Ibuprofen did not have an influence on vitellogenin levels, female gonadosomatic index or cumulative egg production and no dose-response relationship in ovarian and testicular expression levels of the investigated genes was observed. This study shows that ibuprofen reduces PGE(2) levels in male and female zebrafish but has no consistent effects on other investigated reproductive parameters.

Design and synthesis of 2-aminothiazole based antimicrobials targeting MRSA

Privileged structure-based libraries have been shown to provide high affinity lead compounds for a variety of important biological targets. The present study describes the synthesis and screening of a 2-aminothiazole based compound library to determine their utility as antimicrobials, focusing on MRSA. Several of the compounds in this series demonstrated improved antimicrobial activity as compared to ceftriaxone (CTX), a β-lactam antibiotic. The most potent compound (21) had MICs in the range of 2-4 μg/ml across a panel of Staphylococcus aureus strains. In addition, trifluoromethoxy substituted aminothiazoles and aminobenzothiazoles were found to be potent antimicrobials with MICs of 2-16 μg/ml.

In vitro and in vivo effects of a cyclooxygenase-2 inhibitor nimesulide analog JCC76 in aromatase inhibitors-insensitive breast cancer cells

Third generation aromatase inhibitors (AIs) are more effective than tamoxifen in the treatment of estrogen receptor (ER) positive breast cancer. However, long-term use of AIs commonly results in resistance. We examined whether compound JCC76{Cyclohexanecarboxylic acid [3-(2,5-dimethyl-benzyloxy)-4-(methanesulfonyl-methyl-amino)-phenyl]-amide}, an analog of Cyclooxygenase-2 (COX-2) inhibitor nimesulide, can inhibit the growth of AI-insensitive breast cancer cells and the mechanisms by which the compound affects cell proliferation. LTEDaro (long term estrogen deprived MCF-7aro cell) cells, which are a model for AI resistance, were used in this study. JCC76 effectively inhibited LTEDaro cell proliferation with an IC(50) of 2.75 ± 0.31 μM. Further investigations reveal that the compound significantly induced apoptosis in LTEDaro cells by decreasing pAKT, BCL-2 and pBad protein levels, which were all up regulated in the cells after long term estrogen deprivation. LTEDaro tumor size and weight were decreased in ovariectomized nude mice treated with the compound, and cell apoptosis in the tumor tissue was increased compared to the control. The animal weight remained almost unchanged which indicated the low toxicity of the compound. These results suggest that JCC76 overcame AI resistance by inducing cell apoptosis as illustrated in the in vitro and in vivo models. Collectively, results from this study provide data to support that nimesulide analog JCC76 may be a new drug candidate to treat AI-resistant breast cancers. It could be also used as a lead to design and synthesize more potent derivatives.

Growth factor signaling enhances aromatase activity of breast cancer cells via post-transcriptional mechanisms

It has been demonstrated that growth factors produced by breast cancer cells stimulate aromatase expression in both breast cancer and adjacent adipose fibroblasts and stromal cells. However, whether these growth factors affect aromatase activity by other mechanisms still remain unclear. In the current study, MCF-7aro and T47Daro aromatase transfected breast carcinoma cells were used to explore the mechanisms of post-transcriptional regulation of aromatase activity by growth factor pathways. Our study reveals that PI3K/Akt and MAPK inhibitors suppressed aromatase activity in MCF-7aro cells. However, PI3K/Akt pathway inhibitors stimulated aromatase activity in T47Daro cells. This is due to enhanced MAPK phosphorylation as compensation after the PI3K/Akt pathway has been blocked. IGF-1 treatment increased aromatase activity in both breast cancer cell lines. In addition, LTEDaro cells (long-term estrogen deprived MCF-7aro cells) which have enhanced MAPK activity, show higher aromatase activity compared to parental MCF-7aro cells, but the aromatase protein level remains the same. These results suggest that aromatase activity could be enhanced by growth factor signaling pathways via post-transcriptional mechanisms.

COX-2 inhibitor nimesulide analogs are aromatase suppressors in breast cancer cells

Cyclooxygenase-2 (COX-2) inhibitor nimesulide derivatives compounds A and B decreased aromatase activity in breast cancer cells via a novel mechanism different to aromatase inhibitors (AIs), and were defined as "aromatase suppressors". Breast carcinoma cells (MCF-7aro and T47Daro) transfected with aromatase full gene were used to explore the mechanisms of the two compounds. They dose and time-dependently suppressed aromatase activity in MCF-7aro and T47Daro cells in the nanomole range. However, they neither directly inhibited aromatase, nor improved aromatase degradation even at much higher concentrations. They could also suppress androgen stimulated cell growth, but did not affect estrogen enhanced cell proliferation. These results suggest that compounds A and B selectively interfere with aromatase in breast cancer cells, but not estrogen receptor (ER) downstream to disrupt androgen mediated cell growth. Interestingly, compound B effectively inhibited LTED (long-term estrogen deprived MCF-7aro cell) cell growth, which is a model for AIs resistance, with an IC(50) of 4.68 ± 0.54 μM. The results indicate that compound B could potentially overcome AI resistance in breast cancer cell and could be used as a lead to design more potent derivatives.

Selective regulation of aromatase expression for drug discovery

Aromatase is a particularly attractive drug target in the treatment of hormone-responsive breast cancer, and aromatase activity in breast cancer patients is greater in or near the tumor tissue compared with the normal breast tissue. Complex regulation of aromatase expression in human tissues involves alternative promoter sites that provide tissue-specific control. Previous studies in our laboratories suggested a strong association between aromatase (CYP19) gene expression and the expression of cyclooxygenase (COX) genes. Additionally, COX selective inhibitors can suppress CYP19 gene expression and decrease aromatase activity. Our current hypothesis is that pharmacological regulation of aromatase can act locally to decrease the biosynthesis of estrogen and may provide additional therapy options for patients with hormone-dependent breast cancer. Two pharmacological approaches are being developed, one approach utilizing small molecule drug design and the second approach involving mRNA silencing technology. The small molecule drug design approach focuses on the synthesis and biological evaluation of a novel series of sulfonanilide analogs derived from COX-2 selective inhibitors. Combinatorial chemistry approaches were used to generate diversely substituted novel sulfonanilides. The compounds suppress aromatase enzyme activity in SK-BR-3 breast cancer cells in a dose and time dependent manner, and structure activity analysis does not find a correlation between aromatase suppression and COX inhibition. Real-time PCR analysis demonstrates that the sulfonanilide analogs decrease aromatase gene transcription in breast cells. Furthermore, the sulfonanilide compounds selectively decrease aromatase gene expression in several breast cancer cells, without exhibiting cytotoxic or apoptotic effects at low micromole concentrations. A ligand-based pharmacophore model for selective aromatase modulation (SAM) by the novel sulfonanilides identified an aromatic ring, two hydrogen bond acceptors, and a hydrophobic function as four key chemical features. In the second approach, short interfering RNAs (siRNA) were designed targeting human aromatase mRNA. Treatment of breast cancer cells with siRNAs targeting aromatase (siAROMs) completely masked the aromatase enzyme activity and resulted in suppression of CYP19 mRNA. Thus, these results suggest that the novel sulfonanilides and the siRNAs targeting aromatase expression may be valuable tools for selective regulation of aromatase in breast cancer.

Effects of celecoxib and ly117018 combination on human breast cancer cells in vitro

Activation and signalling of estrogen receptor (ER) and COX-2 represent two important pathways in breast cancer cell regulation. Activation of either pathway is associated with breast cancer cell proliferation and eventually malignant progression. Raloxifene analogue, Ly117018, a selective estrogen receptor modulator and celecoxib, a specific COX-2 inhibitor have been shown to inhibit breast cancer cell proliferation when used alone in vitro and in vivo. In this study, the combined drug effects on hormone-dependent MCF-7 and hormone-independent MDA-MB-435 cells in vitro were evaluated. Cell proliferation assays excluded drug antagonism and revealed a moderate synergistic growth inhibitory activity of Ly117018 and celecoxib on both cell lines when combined in specific concentrations. Growth inhibition of either compound was not associated with cell cycle arrest. In MCF-7 cells, western blot analysis revealed a decreased phosphorylation of the AKT protein by either agent alone or in combination. In MDA-MB-435 cells, celecoxib alone induced an increase in AKT phosphorylation relative to total AKT protein; this effect was decreased in the presence of Ly117018. These results indicate that these two drugs are non-antagonistic; and when combined in specific concentrations, moderate synergistic antiproliferative activity of celecoxib and Ly117018 were observed in hormone-dependent MCF-7 and hormone-independent MDA-MB-435 cells associated with changes in cell cycle distribution and regulation of AKT protein and phosphorylation. These findings further support a central role of the ER- and COX-2 pathways in human breast cancer cells.

CoMFA, LeapFrog and blind docking studies on sulfonanilide derivatives acting as selective aromatase expression regulators

Aromatase, the enzyme responsible for estrogen biosynthesis, is an attractive target in the treatment of hormone-dependent breast cancer. In this manuscript, the structure-based drug design approach of sulfonanilide analogues as potential selective aromatase expression regulators (SAERs) is described. Receptor-independent CoMFA (Comparative Molecular Field Analysis) maps were employed for generating a pseudocavity for LeapFrog calculation. A robust model, using 45 and 10 molecules in the training and test sets, respectively, was developed producing statistically significant results with cross-validated and conventional correlation coefficients of 0.656 and 0.956, respectively. This model was used to predict the activity of newly proposed molecules as SAERs candidates being two magnitude orders more potent than the previously reported compounds. Also in the present study, the computational blind docking method using eHiTS is tested on molecules study group and COX-2 enzyme. Future perspectives of the method in the screening of SAERs candidates with no COX-2 inhibitory activity are discussed.

Xanthones from the botanical dietary supplement mangosteen (Garcinia mangostana) with aromatase inhibitory activity

Twelve xanthone constituents of the botanical dietary supplement mangosteen (the pericarp of Garcinia mangostana) were screened using a noncellular, enzyme-based microsomal aromatase inhibition assay. Of these compounds, garcinone D (3), garcinone E (5), alpha-mangostin (8), and gamma-mangostin (9) exhibited dose-dependent inhibitory activity. In a follow-up cell-based assay using SK-BR-3 breast cancer cells that express high levels of aromatase, the most potent of these four xanthones was gamma-mangostin (9). Because xanthones may be consumed in substantial amounts from commercially available mangosteen products, the consequences of frequent intake of mangosteen botanical dietary supplements require further investigation to determine their possible role in breast cancer chemoprevention.

Synthesis and biological evaluation of novel sulfonanilide compounds as antiproliferative agents for breast cancer

Combinatorial chemistry approaches facilitate drug discovery processes and result in structural modifications of lead compounds that enhance pharmacological activity, improve pharmacokinetic properties, or reduce unwanted side effects. Epidemiological and animal model studies have suggested that nonsteroidal anti-inflammatory drugs (NSAIDs) can act as chemopreventive agents. The cyclooxygenase-2 (COX-2) inhibitor nimesulide shows anticancer effects in several cancer cell lines via COX-2-dependent and -independent mechanisms. The molecular structure of nimesulide was used as a starting scaffold to design novel sulfonanilide analogs and examine the structural features that contribute to this anticancer effect. A systematic combinatorial chemical approach was used to generate diversely substituted sulfonanilide derivatives that were tested for their effects on the proliferation of human breast cancer cells. Structure-function analysis indicated that the inhibition of cell growth by compounds derived from the novel sulfonanilides required a bulky terminal phenyl ring, a methanesulfonamide, and a hydrophobic carboxamide moiety.