Anti-Cancer Agents in Medicinal Chemistry (Formerly Current Medicinal Chemistry - Anti-Cancer Agents) - Volume 14, Issue 6, 2014

After water, tea is the most widely consumed beverage. The major active constituents in green tea are catechins, of which epigallocatechin-3-gallate (EGCG) is the most abundant and active compound. Animal experimental studies using EGCG alone or green tea catechins with EGCG being a major component have generated a mounting body of evidence suggesting that EGCG as a naturally occurring compound and commonly consumed beverage ingredient is a promising cancer preventive agent. However, the relationship between green tea consumption and reduced cancer risk seen from epidemiologic studies is not as encouraging as that observed in animal studies and remains inconclusive. In the present article, the achievements using EGCG or green tea catechins for cancer prevention were reviewed, the latest identified anticancer mechanisms of EGCG and the emerging mechanism-based cancer therapies of EGCG were outlined, and the potential reasons for the discrepancy in animal studies and epidemiological studies were tentatively analysed. On the basis of these analyses, it could be anticipated that future intervention trials in humans would be able to achieve consistent cancer prevention effects provided that the timely intervention of EGCG or green tea catechins at appropriate high-dose levels presumably approaching their upper safety limits have had been fully considered.

Cancer stem cells are a subset of cells that are responsible for cancer initiation and relapse. They are generally resistant to the current anticancer agents. Successful anticancer therapy must consist of approaches that can target not only the differentiated cancer cells, but also cancer stem cells. Emerging evidence suggested that the dietary agent curcumin exerted its anti-cancer activities via targeting cancer stem cells of various origins such as those of colorectal cancer, pancreatic cancer, breast cancer, brain cancer, and head and neck cancer. In order to enhance the therapeutic potential of curcumin, this agent has been modified or used in combination with other agents in the experimental therapy for many cancers. In this mini-review, we discussed the effect of curcumin and its derivatives in eliminating cancer stem cells and the possible underlying mechanisms.

Garlic (Allium sativam L.) is widely used in traditional herbal remedies and alternative medicine. The potential health benefits of garlic are largely attributed to its metabolic byproducts. Extensive in vivo and in vitro studies has demonstrated that the garlic derivatives possess anti-cancer effects, but the underlying mechanisms are not completely understood. In this mini-review, we aim to summarize the reported biological effects of garlic products as anti-tumor agents, and present the possible molecular mechanisms responsible for the anti-carcinogenesis effects of garlic and its derivatives.

Prostate cancer is common in men with very high mortality which is one of leading causes of cancer-related deaths in men. The main treatment approaches for metastasized prostate cancer are androgen deprivation and chemotherapeutic agents. Although there are initial responses to castration, the resistance to the treatment will eventually occur, leading to castration-resistant prostate cancer. The common chemotherapeutic agents for the treatment of prostate cancer are docetaxel and taxane but outcomes of using these drugs have not been satisfactory. Therefore, it is necessary to find better treatment approaches for prostate cancer and to search for compounds that are effective in prostate cancer prevention. Lycopene extracted from tomato and other fruits or plants such as Gac, watermelon, pink grapefruit, pink guava, red carrot and papaya has been shown to be effective on prostate cancer prevention and treatment. The advantage of the application of lycopene for its anti-prostate cancer activity is that lycopene can reach much higher concentration in prostate tissue than other tissues. In this review, the effect of lycopene on PI3K/Akt pathway is summarised, which could be one of major mechanisms for anti-cancer activity of lycopene.

Resveratrol (3, 5, 4’-trihydroxy-trans-stilbene, RVT), a stilbenoid, polyphenol phytochemical present in berries, grape, peanuts and wine. It has been suggested as a major contributor to “French Paradox” that reduces the mortality from coronary heart disease (CHD) by consuming RVT in red wine even in some of French population with a high-fat intake. With extensive research, it has been found that RVT is a versatile and pleiotropic agent, it not only possesses cardiovascular-protective benefits by its powerful antioxidant capacity, anti-inflammatory, regulating metabolism and anti-aging effects, but also has strong anti-tumor activities through inhibiting tumor cell proliferation, inducing cell apoptosis, promoting tumor cell differentiation, preventing tumor invasion and metastasis, and further moderating the host immune system to kill tumor cells. This review will focus on RVT’s anti-tumor activity and tumor prevention potential including: the anti-tumor spectrum in vitro and in vivo; molecular targets and signal pathways involving RVT anti-tumor mechanisms; evidences from clinical trial for its bioavailability, dosage, toxicity and benefit in humans; and its prospective including its analog, deviations, and combinative chemotherapy.

Quercetin, a natural protective bioflavonoid, possesses diverse pharmacologic effects, such as antioxidant, anti-inflammatory, anti-proliferative, and anti-angiogenic activities. Recently, quercetin’s effect in cancer prevention and treatment was recognized. However, the poor water solubility and low-bioavailability of quercetin limit its clinical use in cancer therapy. Nanotechnology provides a method to create novel formulations for hydrophobic drug. Nanoparticles-delivered quercetin has attracted many attentions for its enhanced anticancer potential and promising clinical application. This review will discuss the application of nanotechnology in quercetin delivery for cancer therapy.

Paris polyphylla J.E. Smith is extensively used in traditional systems of Indian and Chinese medicines mainly for its anticancerous property. The national and international demand for P. polyphylla is constantly increasing and most of the supplies come from wild. Illegal and unscientific exploitation coupled with habitat destruction decreases the natural population of the herb, as a consequence this species comes under vulnerable category. Restoration and conservation of the natural population of this potential herb is prerequisites. This article aims to provide an overview on chemical and biological prospective of P. polyphylla. Secondary metabolites such as daucosterol, polyphyllin D, β -ecdysterone, Paris saponins I, II, V, VI, VII, H, dioscin, oligosaccharides, heptasaccharide, octasaccharide, trigofoenoside A, protogracillin, Paris yunnanosides G-J, padelaoside B, pinnatasterone, formosanin C and 20-hydroxyecdyson saponins have been isolated from P. polyphylla. Several biological activities such as anticancerous, antitumor, cytotoxic, anthelmintic, antimicrobial, antiangiogenic, immunostimulating, contractile and hemostatic have also been reported. Consequently, this review will be helpful to the researcher and scientist for further research.

Rho GTPases play a key role in the regulation of multiple essential cellular processes, including actin dynamics, gene transcription and cell cycle progression. Aberrant activation of Rac1, a member of Rho family of small GTPases, is associated with tumorigenesis, cancer progression, invasion and metastasis. Particularly, Rac1 is overexpressed and hyperactivated in highly aggressive breast cancer. Thus, Rac1 appears to be a promising and relevant target for the development of novel anticancer drugs. We identified the novel Rac1 inhibitor ZINC69391 through a docking-based virtual library screening targeting Rac1 activation by GEFs. This compound was able to block Rac1 interaction with its GEF Tiam1, prevented EGF-induced Rac1 activation and inhibited cell proliferation, cell migration and cell cycle progression in highly aggressive breast cancer cell lines. Moreover, ZINC69391 showed an in vivo antimetastatic effect in a syngeneic animal model. We further developed the novel analog 1A-116 by rational design and showed to be specific and more potent than the parental compound in vitro and interfered Rac1-P-Rex1 interaction. We also showed an enhanced in vivo potency of 1A-116 analog. These results show that we have developed novel Rac1 inhibitors that may be used as a novel anticancer therapy.

Objectives: To study the effect of co-injecting unlabelled hypericin (Hyp) on biodistribution, necrosis uptake and tumour retention of iodine-123 or iodine-131 labelled hypericin (123/131I-Hyp), a necrosis avid agent for an anticancer radiotherapy. Methods: 123/131I-Hyp was prepared with Iodogen as oxidant and formulated in 0.6 μg/kg no-carrier-added (NCA) or 0.25 mg/kg unlabelled Hyp carrier-added (CA) forms using dimethyl sulfoxide/polyethylene glycol-400/propylene glycol/water (25/25/25/25% v/v/v/v), as solvent mixture. Comparisons on biodistribution and necrosis uptake of NCA and CA123I-Hyp were conducted on rats (n=24) of reperfused liver infarction (RPLI) in 48h p.i. Tumour retention of CA131I-Hyp was assessed in severe combined immunodeficiency (SCID) mice with fibrosarcoma (RIF-1) tumours (n=25) over 40 days. To cause intratumour necrosis, mice were pre-treated with a vascular disrupting agent CA4P at 10mg/kg. Tissue-gamma counting (TGC), autoradiography and histology were performed. Results: TGC revealed no significant difference in organ biodistribution between RPLI-rats injected with NCA and CA123I-Hyp, except in intestines, liver, lungs and stomach (P<0.05). Both preparations showed hepatobiliary excretion since intestines and faeces retained the most radioactivity. NCA and CA123I-Hyp exhibited high avidity and selectivity for hepatic infarction. From the day after injection onward, CA123I-Hyp showed greater target accumulation (7-11%ID/g) than 123I-Hyp alone (∼4%ID/g; P<0.05). In RIF-1-SCID mice receiving CA131I-Hyp, prolonged high retention in tumour necrosis was detected over 40 days p. i. TGC findings were confirmed by histological and autoradiographic analysis. Conclusions: The study demonstrated the co-injection of unlabelled Hyp affected necrosis uptake but almost no biodistribution of radioiodinated Hyp. Long-term high retention into tumour necrosis characterizes the carrier-added 131I-Hyp.

The present work describes the anticancer activity of a new indolylcoumarin named COUFIN and more specifically, its efficiency against clear cell renal carcinoma (CCRC). COUFIN inhibited microtubule formation and bound on tubulin to or near the colchicine site. In vitro, COUFIN showed potent anticancer activity on renal carcinoma cells (RCC) both in monolayer (2D culture) (IC50 of 88±8 nM) and multicellular tumor spheroid (3D culture) (IC50 of 180±20 nM). The compound blocked cell cycle transition at G2/M phase, induced a subsequent apoptotic process but did not modulate clonal growth of CFU-GM. On the other hand, the coumarin derivative decreased the activity of P-gp and BCRP but was not substrate for these ABC pumps. In vivo, the indolylcoumarin increased the survival rate after 3 weeks of treatment. Based on the present study, COUFIN was identified as a bifunctional molecule able to inhibit renal carcinoma cells proliferation without being effluxed by ABC proteins. Thus COUFIN could be a promising chemotherapeutic agent for treating tumor cells over-expressing efflux pumps and tumor cells irrigated by vessels lined with endothelial cells responsible of poor distribution of conventional anticancer agents.

Recent era aims at developing safer partial Peroxisome proliferator-activated receptor-γ (PPAR- γ) agonists in order to dodge the toxicity issues related to full agonists. With a view to develop non-thiazolidinediones as partial PPAR-γ agonists, novel analogues of oxazol-5-ones (3a-3q) were designed and virtually analyzed for their molecular and drug like properties. The newly synthesized compounds were further evaluated for their preliminary cytotoxicity in a panel of eight cancer cell lines using four concentrations at 10- fold dilutions. Sulforhodamine B (SRB) protein assay was used to estimate cell stability or growth. All the compounds demonstrated distinct effect in the extent of cytotoxicity in the breast cancer cell line MCF-7 with 3g specifically exhibiting partial PPAR-γ agonist activity and adipogenesis stimulating ability.

Numerous studies showed that drug resistance of gastric cancer cells could be modulated by the abnormal expression of microRNAs (miRNAs) which target multiple cell signaling pathways. The possible function of miR-1271 in the formation of cisplatin resistance in gastric cancer cells has been investigated in this study. miR-1271 was significantly down-regulated in gastric cancer tissues and various gastric cancer cell lines. Moreover, it was down-regulated in the cisplatin-resistant gastric cancer cell line SGC7901/cisplatin (DDP) and the down-regulation of miR-1271 in SGC7901/DPP cells was accompanied by the up-regulation of insulin-like growth factor 1 receptor (IGF1R)/insulin receptor substrate 1 (IRS1) pathway-related proteins, i.e., IGF1R, IRS1, serine/threonine-protein kinase mTOR (mTOR), and the apoptosis regulator Bcl-2 (BCL2), compared with the parental SGC7901 cells. Over-expression of miR-1271 sensitized SGC7901/DDP cells to cisplatin. Changes in the luciferase activity of reporter constructs harboring the 3-untranslated region of the above proteins in SGC7901/DDP cells suggested that IGF1R, IRS1, mTOR, and BCL2 were target genes of miR-1271. Enforced miR-1271 expression repressed the protein levels of its targets, inhibited proliferation of SGC7901/DDP cells, and sensitized SGC7901/DDP cells to DDP-induced apoptosis. Overall, on the basis of the results of our study, we proposed that miR-1271 could regulate cisplatin resistance in human gastric cancer cells, at least partially, via targeting the IGF1R/IRS1 pathway.

We developed a drug-delivery system comprising a novel platinum drug (Pt(II) complex) entrapped within β-Casein (β-CN) nanoparticles referred to as nano-vehicles. Fluorescence spectroscopy, UV-Vis spectrometry, dynamic light scattering (DLS), and scanning electron microscopy (SEM) were used to characterize the β-CN-Pt(II) complex . What was apparent in this study was that the solubility of Pt (II) complex increased in the presence of β-CN. Furthermore, fluorescence spectroscopy results revealed the binding of the β -CN micelle to the platinum complex at pH 7.0. The tryptophan fluorescence intensity further revealed that the optimal loading molar ratio of β-CN: Pt (II) complex was 1:3 (with β-CN at 1 mg/mL). Under these conditions, the optimal nano-vehicle was formed based on the DLS results. Results from the DLS and SEM analyses are proof for the formation of the β-CN-Pt(II) complex nanoparticles with a very good colloidal stability and an average particle size of 250 nm. Finally, the cytotoxicity of free- and encapsulated-Pt (II) complex was evaluated using colorectal carcinoma HCT116 cells, as a cancer model cell line, because platinum drugs have been used mostly for treatment of Gastrointestinal cancers. Results indicated that the cytotoxicity and cellular uptake of the drug was enhanced when entrapped in β -CN nanoparticles. Polymeric micelles are internalized into the cells via fluid-state endocytosis. These findings suggest that β-CN is an excellent nano-vehicle for targeted delivery of platinum drugs, which are generally recognized as safe (GRAS) and potentially useful in pharmaceutical industries.

Objectives: Honey is reported to contain various compounds such as antioxidants. Chrysin is a natural and biologically active compound extracted from honey. It possesses antioxidant properties and promotes cell death by perturbing cell cycle progression. We focused on the possible role that chrysin may act as a potential anticancer agent, and tested its biological activity and possible mechanisms in the human lung adenocarcinoma epithelial cell line. Materials & Methods: Antiproliferative effect of honey and chrysin were determined by 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay; DNA fragmentation was determined by gel electrophoresis assay; apoptosis was detected by flow cytometer; apoptosis-related gene expression was detected by reverse transcription polymerase chain reaction assay; and activation of caspase-3 and caspase-9 were evaluated by a colorimetric assay; Bax and Bcl-2 protein expression were also analysed by western blotting. Results: The results revealed that the cell viability decreased in a concentration- and time- dependent manner in the malignant cells treated with honey and chrysin in comparison with the nonmalignant cells. The IC50 values of honey against A549 cells were determined 15 ± 0.05% and 8 ± 0.05 % after 48 and 72h, respectively. The IC50 dose of chrysin was determined to be 49.2 ± 0.6 and 38.7 ± 0.8μM at 48 and 72 h, respectively. Reactivity with Annexin V fluorescence antibody and propidium iodide showed that chrysin induced apoptosis in the lung cancer cells (p<0.001). Moreover, chrysin treatment resulted in the activation of caspase-3 and - 9 and an increase in the Bax/Bcl-2 ratio (p<0.01). Bax protein expression was increased but Bcl-2 protein expression decreased in chrysin-treated cells .Chrysin inhibits the growth of the lung cancer cells by inducing cancer cell apoptosis via the regulation of the Bcl-2 family and also activation of caspase-3 and -9, which may, in part, explain its anticancer activity. Conclusion: This study shows that chrysin could also be considered as a promising chemotherapeutic agent and anticancer activity in treatment of the lung cancer cells in future.

Synthesis of new chiral thiourea derivatives (27 examples) as anticancer agents has been described. Three compound 7d (NSC code 761448/1), 7e1 (NSC code 767161/1), and 7e3 (NSC code 767160/1) were found to exhibit higher anticancer activity than 5-fluorouracil against Colon cancer, Melanoma, Ovarian cancer, and Breast cancer subpanels. The effect of stereochemistry of amino acid residues on the tumor growth inhibitory activity has also been studied.