Anti-Cancer Agents in Medicinal Chemistry (Formerly Current Medicinal Chemistry - Anti-Cancer Agents) - Volume 17, Issue 11, 2017

Malignant transformation of cells requires specific adaptations of cellular metabolism to support growth and survival. Alterations in cancer central carbon metabolism including aerobic glycolysis, elevated glutaminolysis, dysregulated tricarboxylic acid cycle and pentose phosphate pathway, facilitate cancer development by maintaining viability and building new biomass. Although a variety of oncogenes or tumor suppressors contribute to these rewiring, accumulating evidence suggests that both post-transcriptional and post-translational modifications (PTMs) also orchestrate the tightly controlled regulation of cancer metabolic adaptations, broadening the biological mechanisms of cancer metabolic reprogramming. Micro RNA, one kind of posttranscriptional modification, mediates transcriptional silencing of various metabolic enzymes. Additional, different kinds of PTMs play important roles in cancer metabolic rewiring by affecting the function, interaction or stability of target proteins. We survey recent studies demonstrating PTMs at lysine residues and microRNAs that are involved in reprogramming of cancer central carbon metabolism, and summarize the effect of these modifications according to different parts of central carbon metabolic pathway. Moreover, we provide an updated overview of the compounds or agents targeting central carbon metabolism in cancer. Given that the heterogeneity of cancer biology, a combination of these novel therapeutics and standard chemotherapeutic agents may obtain better benefit and overcome drug resistance. Finally, this review discusses the challenges and some new steps that may further advance this field.

Multidrug resistance occurs when a tumor develops resistance to multiple chemotherapeutic drugs, which may include antitumor drugs with different chemical structures and mechanisms. Multidrug resistance limits the treatment effects of antitumor drugs, and is the main cause of chemotherapy failure. Multidrug resistance is caused by numerous factors including changes in ATP-binding cassette transporters, target proteins, detoxification, deoxyribonucleic acid repair, drug metabolic enzymes, and signal pathways of apoptosis. Clinical research indicates that natural products have great potential to treat tumors and reverse multidrug resistance. Natural products, which often have multiple targets, could play an important role in tumor treatment, have beneficial effects on tumor inhibition, improve symptoms, reduce radiotherapy and chemotherapy side effects, enhance immunity, and prolong survival. Because natural products often have few adverse reactions and less drug resistance, the antitumor activities of natural products have attracted extensive research. We aimed to review the basic research and clinical application of natural products in the reversal of multidrug resistance.

Cytokines are small secreted proteins serving as vital mediators that mediate the host immune responses. Transcription and post-transcription play a critical role in cytokine expression through the regulation of message RNA (mRNA) cytoplasmic localization, translation initiation and decay. Researches have been conducted to reveal regulatory mechanisms of cytokines production in cells involved in cancer. AU-rich element (ARE) can regulate the degradation and translation of mRNA by connecting with specific ARE binding proteins. It is now clear that tristetraprolin (TTP), as the most common ARE binding protein, negatively regulates many aspects of the cytokines through binding to the AREs in the 3'-untranslated region (3'UTR) of mRNA. Furthermore, some certain cytokines have an impact on TTP expression and function. Therefore, the cross-regulation between cytokines and TTP has come into sight. The complicated regulatory networks between cytokines and TTP are closely related to tumorigenesis. In this review, we summarize specific regulatory mechanisms of cytokine mRNAs. We focus on how TTP negatively regulates inflammatory and oncogenic cytokines expression after combining with AREs, we also pay attention to some cytokines mediating the expression of TTP and their cross-talk in various cancers in detail.

Aromatase inhibitors have often been likened to that of 'medical scalpels' for the treatment of breast carcinoma. By inhibiting the singular step of aromatisation, they have proven to be extremely effective allies in the treatment of breast cancer among postmenopausal women. However, their relevance soon may not be limited to the post-menopausal age group alone. Recent studies have hinted at their utility amongst the premenopausal women; combined with ovarian ablation techniques, aromatase inhibitors may prove to be equally effective and more, as compared to tamoxifen in this age-group. Additionally, explorations aimed at ascertaining their potential utility as an effective preventive strategy against breast carcinoma have yielded encouraging results. However, for aromatase inhibitors to be able to attain their full potential, further strategic fine-tuning aimed at maximising their efficacy and minimising their potentially far-reaching adverse effects, is the need of the hour. Despite the recent diversification, the issue of resistance to aromatase inhibitors in breast cancer threatens to derail the advances so gained till date. Fortunately, a few novel ploys have come to the fore, for instance combining aromatase inhibitors with HER-2 antibodies that could potentially help circumvent the menace of resistance in the near future. Till date, the utility of aromatase inhibitors can at best be described as onedimensional. However, with the unearthing of potential new avenues for its application, this assortment of molecules today stands on the precipice of ushering in a new revolution in the treatment of breast carcinoma.

Background: The epidermal growth factor receptor (EGFR) is a driver oncogene and specific blockade of EGFR has been shown to be an effective therapeutic approach against multiple human cancers. Aims: Here we employed the homogeneous time-resolved fluorescence (HTRF) technology to screen new EGFR mediators. Method: 4 hits (NDS-41107, NDS-41119, NDS-41111 and NDS-41126) were confirmed in a compound library of 8000 compounds, and the IC50 values were determined to be 15.45±2.25μM (NDS-41107), 6.16±0.88 μM (NDS-41119), 11.33±3.31 μM (NDS-41111) and 11.19±1.67μM (NDS-41126), respectively. We then showed that NDS-41119 (N-cyclohexyl-2-(1-(phenylsulfonyl) piperidin-4-yl) acetamide) significantly inhibited EGFR signaling in human lung cancer cells, as evidenced by decreased phosphorylation of EGFR128;ERK and Akt. NDS-41119 also attenuated EGF-induced cell proliferation and migration in a dose-dependent manner. We finally demonstrated that NDS-41119 inhibited the T790M mutation in NCI-H1975 cells and potentiated the effect of gefitinib against resistant cells. Result: Our results will contribute to the development of novel EGFR-targeted anti-cancer drugs.

Background: Saponins from Medicago species display several biological activities, among them apoptotic effects against plant cells have been evidenced. In contrast, their cytotoxic and antitumor activity against animal cells have not been studied in great details. Objective: To explore the cytotoxic properties of saponin from Medicago species against animal cells and their effect in combination with the antitumoral drug cisplatin. Method: Cytotoxic activity of saponin mixtures from M. arabica (tops and roots), M. arborea (tops) and M. sativa (tops, roots and seeds) and related prosapogenins from M. arborea and M. sativa (tops) against HeLa and MCF-7 cell lines is described. In addition, cytotoxicity of soyasaponin I and purified saponins (1-8) of hederagenin, medicagenic and zanhic acid is also presented. Combination experiments with cisplatin have been also conducted. Results: Saponins from M. arabica tops and roots (mainly monodesmosides of hederagenin and bayogenin) were the most effective to reduce proliferation of HeLa and MCF-7 cell lines. Among the purified saponins, the most cytotoxic was saponin 1, 3-O-D-glucopyranosyl(1→2)-α-L-arabinopyranosyl hederagenin. When saponins, derived prosapogenins and pure saponins were used in combination with cisplatin, they all, to different extent, were able to potentiate cisplatin activity against HeLa cells but not against MCF-7 cell lines. Moreover uptake of cisplatin in these cell lines was significantly reduced. Conclusion: Overall results showed that specific molecular types of saponins (hederagenin glycosides) have potential as anti-cancer agents or as leads for anti-cancer agents. Moreover saponins from Medicago species have evidenced interesting properties to mediate cisplatin effects in tumor cell lines.

Background: Fruits of Morus alba L. (mulberry) have various bioactive compounds such as polyphenols and anthocyanins and used as a herbal medicine. However, the anti-cancer effects and molecular basis have not been elucidated. Methods: We isolated the cyanidin-3-glucoside in various cultivar of mulberry by acidified-methanol extraction methods. This molecule were compared mass spectroscopic properties by LC-MS/MS and analyzed by 1H and 13C NMR. We examined the anti-cancer effect with molecular mechanisms of the cyanidin-3-glucoside on MDA-MB-453 human breast cancer cells and xenograft animal model. Results: The treatment with the mulberry cyanidin-3-glucoside decreased cell viability in a dose-dependent manner with alteration of apoptotic protein contents, and DNA fragmentation, suggesting that cells undergo apoptosis. Supporting the observations, Treatment with the cyanidin-3-glucoside showed active apoptosis by caspase-3 cleavage and DNA fragmentation through Bcl-2 and Bax pathway. Indeed, cyanidin-3-glucoside inhibits tumor growth in MDA-MB-453 cells-inoculated nude mice. Tumor growth of xenograft nude mouse was significantly reduced compared to the control group by the cyanidin-3-glucoside. Conclusion: The data demonstrate that cyanidin-3-glucoside isolated from mulberry induced apoptosis in breast cancer (MDA-MB-453) cells, and therefore, has a potential as an anti-cancer agent. These results show that mulberry cyanidin-3-glucoside inhibit the proliferation and growth in vitro and in vivo model and, indicating the inhibition of tumor progression.

Background: Squamous cell cancer is a heterogeneous aggressive disease, therefore, its treatment is challenging. Increased attention has been paid to metal complexes as anticancer drugs. However, new insights towards autophagy have been recognized due to its role in tumor cell death or survival. Objective: To clarify the antitumor activity of copper (I) nicotinate complex (CNC) as new therapeutic agent and understand the role of autophagy modulation as a prospective target for the advancement of efficient therapeutic agent for treatment. Method: Viability of MDA-MB-231 and HCC1806 cells and IC50 values of CNC for both cell lines were assessed by MTT assay. Also, the viability and IC50 values of Torin1 and Chloroquine (CQ) were assessed only in HCC1806 cells by MTT assay. The level of microtubule-associated protein 1 light chain 3 (LC3) was assessed by ELISA. Real time PCR was used to detect the changes in NBR1 gene expression. Cell cycle distribution and quantitative detection of acid vesicular organelles (AVOs) were determined by flow cytometry. Fluorescence microscope was used for qualitative detection of AVOs. Modulation of autophagy was carried out by Torin1 as inducer and CQ as inhibitor. Results: CNC restrained the growth, in a dose-dependent manner, and induced cell death in human HCC1806 cell line. In addition, the CNC treated cells displayed inhibition of autophagy, as indicated by reduction of AVOs, decrease in LC3 protein level and up regulation of NBR1 gene expression. Conclusion: CNC, as an autophagy inhibitor and pro-apoptotic agent, could be a promising anti-cancer agent either alone or in combination with other therapeutic drugs.

Background: Resveratrol (RV) and its analogues Aza-stilbenes were found effective in exhibiting anticancer activity. Objective: The present study mainly focused on the green synthesis of novel imine stilbene analogues and evaluation of their anticancer activity besides their influence on hypoxia-induced gene expression in cancer cells. Method: Novel imine stilbenes, differing in number and/or position of hydroxyl and methoxy functional groups, have been synthesized using green chemistry mediated condensation reaction between aldehydes and amines in the ethanolic extract of Psoralea corylifolia hairy roots and tested for their anticancer potential. Results: Ethanol containing 1% hairy root extract facilitated instant reaction and yielded more than 99% product( s). MTT assay on HeLa cells treated with imine stilbene analogues revealed an increase in the inhibition of cell proliferation as compared to RV. Treatment of nontumor HEK293 cells with these compounds disclosed minimal toxicity implying the selective advantage of these compounds for cervical cancer therapy. Scratch assay on HeLa cells displayed inhibition of directional cell motility by these analogues and compound 3e [4-((E)-(4- hydroxyphenylimino)methyl)-2-methoxyphenol] recorded maximum inhibition. In reporter assay, as compared to untreated N-(2-Methoxy-2-oxoacetyl) glycine methyl ester (DMOG) induced cells, hypoxia response element- directed transcriptional activity has been significantly reduced in DMOG induced cells treated with imine stilbene analogues. Conclusion: Overall results indicated that four of the five imine stilbene analogues exhibited enhanced anticancer activity than that of the RV. As such, the novel synthetic compounds 3d, 3e and 3b endowed with potent anticancer activity than RV can serve as drug lead molecules.

Background: Renal cell carcinoma (RCC) is one of the most common neoplasms that occurs in the kidney and is marked by a unique biology, with a long history of poor response to conventional cancer treatments. In recent years, there have been significant advancements implemented to understanding the biology of RCC, which has led to the introduction of novel targeted therapies in the management of patients with metastatic disease. Objective: The present study was designed to evaluate the effects of p38 MAPK inhibitor (SB203580), alone and in combination with mTOR inhibitor (CCI779) on apoptosis and cell proliferation. Method: Subtoxic concentrations of inhibitors were selected by MTT assay using A-498, ACHN and primary culture of RCC. Results: All the three types of RCC cells had almost similar response towards these inhibitors. The results revealed that 25μM of SB203580 and 20μM of CCI779 at 48 hrs decreased cell viability by 20% and 30%, respectively, whereas the combination of both inhibitors showed a maximum of 40% reduction in cell viability. Conclusion: The study concludes that the combination of SB203580 and CCI779 inhibitors may induce cellular senescence in A-498 cells with higher potency than that of individual inhibitors.

Background: Cabazitaxel (CTX) is a second- generation taxane derivative, a class of potent anticancer drugs with very low water solubility. CTX is used in patients with resistant prostate cancer unresponsive to the first generation taxane, docetaxel. Currently marketed formulations of CTX contain high concentrations of surfactant and ethanol, which cause severe hypersensitivity reactions in patients. Methods: In order to increase its solubility, two hemiester analogs; CTX-succinate and CTX-glutarate were synthesized and characterized. To improve the solubility of hemiesters even more, dextran as a biocompatible polymer was also conjugated to hemiester analogs. MTT assay was performed on MCF-7 cell line to evaluate the cytotoxicity effect of hemiesters and conjugates. Results: Based on the results, hemiester analogs increased water solubility of the drug up to about 3 and 8 fold. Conjugation to dextran enhanced the CTX solubility to more than 1500 fold. These conjugates released the conjugated CTX in less than 24 hours in a pH dependent manner and showed proper hemocompatibility characteristics. The hemiesters had approximately similar cytotoxicity in comparison with CTX and the dextran conjugates showed higher cytotoxicity effect on MCF-7 cell line.

Background: Cancer is one of the most dangerous diseases with quite a high mortality rate. Many quinazoline derivatives show potent anticancer activity. Objective: In this work our aim is to develop novel, safe and effective anticancer agents. Method: New 6,8-dibromo-2-(4-chlorophenyl)-quinazoline-sulphonamide hybrids and some Schiff´s base analogs were synthesized, and their structures were confirmed by spectral and elemental analysis. Cytotoxicity of all synthesized compounds was evaluated on three cancer cell lines MCF7, HCT116 and HEPG2 using sulpharodamine- B assay method and doxorubicin as a reference drug. All tested compounds show promising cytotoxic activities on the three cell lines. Results: Compound IXd was 2 times more active than doxorubicin on MCF7 cancer cells, while it was 3 times more potent than doxorubicin on HCT116 cancer cells. Compound IV was 2 times more active than doxorubicin while compound VI exhibited similar activity to doxorubicin on HEPG2 cell line. The most active compounds were tested against epidermal growth factor receptor tyrosine kinase (EGFR TK). Compounds IV, IXd, IXf show the most potent inhibitory percent 62.3, 91.1, 91.6 respectively. Compounds IV, V, VII, IXd, IXf caused a significant increase of CASP3 activity with range 86.5-37.6 %. Conclusion: The present work led to the discovery of new cytotoxic compounds having quinazoline pharmacophore.

Background: Evidence has been provided of the anti-proliferative activity of citalopram against some cancer cells. Objective: The apoptotic impact of citalopram, an antidepressant, against liver hepatocellular carcinoma cell line HepG2 was investigated in relation to the oxidative pathway and nuclear factor (NF)ΚB activation. Method: The cytotoxic effects of citalopram on HepG2 cells were determined by MTT assay. Reactive oxygen species (ROS) formation and cytochrome c release were measured following treatment with citalopram. Apoptosis analysis and Bax and Bcl-­2 mRNA and protein levels were also determined. Results: The cytotoxic effects of different concentrations of citalopram on HepG2 cells were observed as a reduction in cell viability and an increase in ROS formation. Citalopram caused an increase in mitochondrial Bax levels and a decrease in Bcl2 levels and also caused cytochrome c release. Moreover, DAPI staining and flow cytometry assays revealed citalopram-induced apoptosis in HepG2 cells. Oxidant scavengers and Bay 11-7082 (an irreversible inhibitor of NFΚB activation) prevented the citalopram-associated cell death, increased BAX and decreased Bcl2. Conclusion: Outcomes from current study suggest that citalopram might exhibit apoptotic effect against hepatocellular carcinoma cell line by induction of cell death through cytochrome c release and ROS-dependent activation of NFΚB.

Background: A new tool for the drug delivery is based on the use of Mesenchymal Stromal Cells (MSCs) loaded in vitro with anti-cancer drugs. Unfortunately, the restricted lifespan of MSCs represents a significant limitation to produce them in high amounts and for long time studies. Immortalized MSCs from adipose tissue (hASCs) have been generated as good source of cells with stable features. These cells could improve the development of standardized procedures for both in vitro and preclinical studies. Furthermore they facilitate procedures for preparing large amounts of secretome containing microvesicles (MVs). Method: We used human adipose tissue derived MSCs immortalized with hTERT+SV40 (TS) genes and transfected with GFP (hASCs-TS/GFP+). This line was investigated for its ability to uptake and release anticancer drugs. Microvesicles associated to paclitaxel (MVs/PTX) were isolated, quantified, and tested on pancreatic cancer cells. Results: The line hASCs-TS/GFP+ maintained the main mesenchymal characters and was able to uptake and release, in active form, both paclitaxel and gemcitabine. From paclitaxel loaded hASCs-TS/GFP+ cells were isolated microvesicles in sufficient amount to inhibit “in vitro” the proliferation of pancreatic tumor cells. Conclusion: Our study suggests that human immortalized MSCs could be used for a large scale production of cells for mediated drug delivery. Moreover, the secretion of drug-associated MVs could represent a new way for producing new drug formulation by “biogenesis”. In the context of the “advanced cell therapy procedure”, the MVs/PTX production would use less resource and time and it could possibly contribute to simplification of GMP procedures.

Background: Breast cancer is associated with a high mortality rate around the world due to its aggressiveness and high resistance to conventional therapies. Sanguinarine (SAN) and Chelerythrine (CHE) are plant alkaloids extracted from Sanguinaria canadensis and Macleaya cordata, which have been studied for their bioactivities. Objective: To determine the anticancer activities of Sanguinarine (SAN) and Chelerythrine (CHE) plant alkaloids. Method: The MTT assay, the alkaline comet assay and cell cycle analyses by flow cytometry were performed. Results: It was observed that SAN was cytotoxic to human breast adenocarcinoma cells (MCF-7) at concentrations of 7.5 μM (24 and 48 hours), effectively reducing cell viability from the concentration of 10 μM for 24 hours and 7.5 μM for 48 hours, by the MTT test. CHE, in turn, was cytotoxic at concentrations of 10 and 20 μM (48 hours), but did not compromise the cellular viability. The comet assay indicated that SAN was genotoxic to the MCF-7 cells, with a significant increment of damage at 10 μM, while none of the tested concentrations of CHE showed a genotoxic effect. The flow cytometry analysis indicated that no cell cycle arrest was caused by both alkaloids, but SAN 10 μM induced a sub-G1 cell population. Conclusion: The results of cytotoxicity, genotoxicity and cell cycle monitoring that are presented in this paper have suggested that SAN has more of a chemotherapeutic activity, as well as having the potential for the development of new therapies for breast cancer, when compared to CHE.

Background: Human Hsp90 chaperone inhibitors are known to be potential anticancer drugs. Previously we have shown a couple of 5-aryl-4-(2,4-dihydroxyphenyl)-1,2,3-thiadiazoles to be promising anticancer agents. Objective: To improve the compounds containing 4-(2,4-dihydroxyphenyl)-1,2,3-thiadiazole scaffold as human Hsp90 inhibitors. Method: We employed chemical synthesis to obtain new compounds and assayed their binding to Hsp90 using the fluorescence thermal shift assay and used MTT assays to determine their effect on cancer cells. Results: A series of compounds containing the 4-(2,4-dihydroxyphenyl)-1,2,3-thiadiazole scaffold were synthesized as Hsp90 inhibitors. Analysis of their binding to the recombinant N-terminal domain of Hsp90 revealed that four of these compounds bound to Hsp90 with Kd of 0.6 to 0.8 nM. The compounds fully inhibited the growth of all tested cancer cell lines: A549 (lung adenocarcinoma), IGR39 (melanoma), and U87 (glioblastoma), with the effective antiproliferative concentration (EC50) of the compounds reaching 0.35 μM. Conclusion: This series of 14 novel and efficient Hsp90 inhibitors provided additional information on the structure-activity relationship of Hsp90 inhibitors and may be further developed into drugs targeting Hsp90.

Background: Natural products inhibiting fatty acid synthase are potential therapeutic agents to treat cancer. Objective: To investigate the chemical constituents of the root tubers of Lindera aggregate and the stems of Linderanacusua, and to find natural inhibitors on the expression level on fatty acid synthase in human breast cancer MDA-MB-231 cells. Methods: The isolation and purification of the extracts were conducted by the methods of percolation and partition extraction, silica and gel column chromatography, recrystallization and by NMR and spectroscopic analysis method. The cell viability was assessed by Cell Counting Kit assay. Results: Seven compounds were elucidated, mainly including five sesquiterpenes, one anthraquinoe and one γ -butanolide, in which compounds 6 was firstly reported from genus Lindera, and compound 7 was isolated from Linderanacusuafor the first time. Among them, 1,3,6-Trihydroxy-7-methyl-9,10-anthracenedione (TMA, compound 6) showed strong inhibitory effect on the expression level on fatty acid synthase in human breast cancer MDA-MB-231 cells. In addition, TMA was found to reduce breast cancer cells viability dosedependently. Conclusion: The fatty acid synthase was a potent therapeutic target for cancers, these findings suggest that TMA has the application potential for treating human cancers.