Anti-Cancer Agents in Medicinal Chemistry (Formerly Current Medicinal Chemistry - Anti-Cancer Agents) - Volume 17, Issue 6, 2017

Breast cancer has continued to cause high cancer death rates among women worldwide. The use of plants’ natural products in breast cancer treatment has received more attention in recent years due to their potentially wider safety margin and the potential to complement conventional chemotherapeutic drugs. Plantbased products have demonstrated anticancer potential through different biological pathways including modulation of the immune system. Immunomodulatory properties of medicinal plants have been shown to mitigate breast cancer cell growth. Different immune cell types participate in this process especially cytotoxic T cells and natural killer cells, and cytokines including chemokines and tumor necrosis factor-α. Medicinal plants such as Glycyrrhiza glabra, Uncaria tomentosa, Camellia sinensis, Panax ginseng, Prunus armenaica (apricot), Allium sativum, Arctium lappa and Curcuma longa were reported to hold strong potential in breast cancer treatment in various parts of the world. Interestingly, research findings have shown that these plants possess bioactive immunomodulators as their main constituents producing the anticancer effects. These immunomodulatory compounds include ajoene, arctigenin, β-carotene, curcumin, epigallocatechin-3-gallate, ginsan, glabridin and quinic acid. In this review, we discussed the ability of these eight immunomodulators in regulating the immune system potentially applicable in breast cancer treatment via anti-inflammatory (curcumin, arctigenin, glabridin and ajoene) and lymphocytes activation (β-carotene, epigallocatechin-3-gallate, quinic acid and ginsan) properties, as well as future research direction in their use for breast cancer treatment.

Background: Polymeric micelles can provide a valid way for cancer treatment with several benefits including high water-solubility of lipophilic drugs, low unwanted effects of cytotoxic drugs by way of reduced systemic exposure and prolonged retention time in the circulatory system. Objective: Recently, there is an increasing interest in preparing poly (ethylene glycol)-poly (amino acid) copolymeric micelles as drug delivery carriers due to their multifunctional property, easy decoration and biosafety. The copolymer contains several functional groups, which show stronger interactions with drugs or can be transferred to develop different types of the copolymers showing pH-, reduction-, thermo-sensitive, targeted or double-function properties. In addition, conjugation of drugs with these copolymers also becomes a novel modification method with the aim of higher drug loading capacity and stability. Copolymeric micelles show exciting advantages on improving a drug’s water-solubility, release behavior, in vitro activity, targeted delivery pharmacokinetic property and biodistribution. In this review, we will introduce the recent development of poly(ethylene glycol)-modified poly (amino acid) copolymeric micelles as anticancer drug delivery systems containing different stimuli (such as thermo-, pH-, reduction- or special enzyme- condition) functional groups and targeting ligands to improve cellular uptake or biostablility of drug-loaded micelles. Conclusion: Poly (ethylene glycol)-poly (amino acid) copolymeric micelles provide an opportunity to realize anticancer drug delivery with environment-responsive and/or targeting property.

Epigenetic modifications play central roles in cellular differentiation and their deregulations really contribute to tumor development. Histone deacetylase (HDAC) enzymes can exert their functions in the epigenetic regulation of gene expression related to oncogenesis via deacetylating the lysine residues of histones in the chromatin and various non-histone proteins. A majority of HDAC inhibitors (HDACIs) have been in different stages of preclinical and clinical trials with potent anticancer activity recently. Among these agents, chidamide tested as either monotherapeutic agent or in combination regimens for numerous hematological and solid malignancies has shown promising potential as an orally active subtype-selective HDACI. Herein we will highlight the progress of clinical trials of chidamide and rationally analyze those results from both preclinical and clinical studies about chidamide as an epigenetic modulator in cancer therapy.

Background: Angiogenesis is a fundamental process in the progression, invasion, and metastasis of tumors. Therapeutic drugs such as bevacizumab and ranibuzumab have thus been developed to inhibit vascular endothelial growth factor (VEFG)-promoted angiogenesis. While these anti-angiogenic drugs have been commonly used in the treatment of cancer, patients often develop significant resistance that limits the efficacy of anti-VEGF therapies to a short period of time. This is in part due to the fact that an independent pathway of angiogenesis exists, which is mediated by 2-(ω-carboxyethyl)pyrrole (CEP) in a TLR2 receptor-dependent manner that can compensate for inhibition of the VEGF-mediated pathway. Aims: In this work, we evaluated a CEP antibody as a new tumor growth inhibitor that blocks CEP-induced angiogenesis. Method: We first evaluated the effectiveness of a CEP antibody as a monotherapy to impede tumor growth in two human tumor xenograft models. We then determined the synergistic effects of bevacizumab and CEP antibody in a combination therapy, which demonstrated that blocking of the CEP-mediated pathway significantly enhanced the anti-angiogenic efficacy of bevacizumab in tumor growth inhibition indicating that CEP antibody is a promising chemotherapeutic drug. To facilitate potential translational studies of CEP-antibody, we also conducted longitudinal imaging studies and identified that FMISO-PET is a non-invasive imaging tool that can be used to quantitatively monitor the anti-angiogenic effects of CEP-antibody in the clinical setting. Results: That treatment with CEP antibody induces hypoxia in tumor tissue WHICH was indicated by 43% higher uptake of [18F]FMISO in CEP antibody-treated tumor xenografs than in the control PBS-treated littermates.

Background: Cancer is considered a major public health problem worldwide. Objective: The aim of this paper is to design and synthesis of novel anticancer agents with potent anticancer activity and minimum side effects. Method: A series of pyrrole derivatives were synthesized, their anti-cancer activity against nine cancer cell lines and two non-cancer cell lines were evaluated by MTT assay, and their cell cycle progression were determined by flow cytometry analysis. Results: The study of the structure-activity relationships revealed that the introduction of the electron-donation groups at the 4th position of the pyrrole ring increased the anti-cancer activity. Among the synthesized compounds, specially the compounds bearing 3,4-dimethoxy phenyl at the 4th position of the pyrrole ring showed potent anti-cancer activity, cpd 19 was the most potent against MGC 80-3, HCT-116 and CHO cell lines (IC50s = 1.0#141;1.7 μM), cpd 21 was the most potent against HepG2, DU145 and CT-26 cell lines (IC50s = 0.5#141;0.9 μM), and cpd 15 was the most potent against A549 (IC50 = 3.6 μM). Moreover, these potent compounds showed weak cytotoxicity against HUVEC and NIH/3T3. Thus, the cpds 15, 19 and 21 show potential anti-cancer for further investigation. Furthermore, the flow cytometry analysis revealed that cpd 21 arrested the CT-26 cells at S phase, and induced the cell apoptosis. Conclusion: Thus, these compounds with the potent anticancer activity and low toxicity have potential for the development of new anticancer chemotherapy agents.

Background: Cancer is a major health problem to human beings around the world. Many quinazoline derivatives were reported to have potent cytotoxic activity. Aims: Our aim in this work is the discovery of potent epidermal growth factor receptor (EGFR) inhibitors with anti-breast cancer activity containing 4-substituted quinazoline pharmacophore. Method: Novel series of 4-substituted 6,8-dibromo-2-(4-chlorophenyl)-quinazoline derivatives have been designed and synthesized. New derivatives were tested against MCF-7 (human breast carcinoma cell line) and screened for their inhibition activity against epidermal growth factor receptor tyrosine kinase (EGFR-TK). Result: Most of the tested compounds show potent antiproliferative activity and EGFR-TK inhibitory activity. Compounds VIIIc and VIIIb exerted powerful cytotoxic activity (IC50 3.1 and 6.3 μM) with potent inhibitory percent (91.1 and 88.4%) against EGFR-TK. Compounds IX, VIIa, X, VIIb, VIc, V, IV, VIa and VIb showed promising cytotoxic effects with IC50 range (12-79 μM) with good activity against EGFR-TK with the inhibitory percent (85.4-60.8%). On the other hand, compounds VIIc, VIIIa exerted low cytotoxic effects as revealed from their IC50 value (124 and 144 μM) with low activity against EGFR-TK with inhibitory percent 30.6 and 29.1% respectively.

Background: Dehydroleucodine, a natural sesquiterpene lactone from Artemisia douglassiana Besser (Argentine) and Gynoxys verrucosa (Ecuador). Objective: To define the molecular mechanisms underlying the effect of dehydroleucodine on the human glioblastoma cells. Method: Various techniques (cDNA expression array, real-time quantitative PCR, chromatin immunprecipitation, luciferase reporter assay, use of phosphospecific antibodies, immunoprecipitation, immunoblotting, apoptosis and autophagy assays) were employed to define and validate multiple molecular gene targets affected in human glioblastoma cells upon dehydroleucodine exposure. Results: Dehydroleucodine exposure upregulated the total and phosphorylated (p-Y99) levels of TP73 in U87- MG glioblastoma cells. We found that TP73 silencing led to a partial rescue of U87-MG cells from the cell death induced by dehydroleucodine. Upon the dehydroleucodine exposure numerous gene targets were upregulated and downregulated through a TP73-dependent transcriptional mechanism. Some of these gene targets are known to be involved in cell cycle arrest, apoptosis, autophagy and necroptosis. Dehydroleucodine induced the TP73 binding to the specific genes promoters (CDKN1A, BAX, TP53AIP1, CYLD, RIPK1, and APG5L). Moreover, the exposure of U87-MG cells to dehydroleucodine upregulated the protein levels of CDKN1A, BAX, TP53AIP1, CYLD, RIPK1, APG5L, and downregulated the CASP8 level. The formation of RIPK1 protein complexes and phosphorylation of MLKL were induced by dehydroleucodine supporting the notion of multiple cell death mechanisms implicated in the tumor cell response to dehydroleucodine. Conclusion: This multifaceted study led to a conclusion that dehydroleucodine induces the phosphorylation of tumor protein TP73 and in turn activates numerous TP73-target genes regulating apoptosis, autophagy and necroptosis in human glioblastoma cells.

Background: An efficient strategy to improve the immunogenicity of peptide vaccines is the use of a synthetic peptide containing cytotoxic T-lymphocyte (CTL) epitopes with T-helper (Th) inducing-epitopes. Objective: Our purpose was to determine the use of human epidermal growth factor receptor-2 (Her2/neu)- specific CTL epitopes plus the pan HLA DR-binding epitope (PADRE) and CpG oligodeoxynucleotides (ODNs) to induce antitumor effects in vaccinated mice. Method: Female BALB/c mice were immunized subcutaneously with different vaccines. Three mice per group were euthanized to assess immune responses and the others were transplanted with TUBO cells. Enzyme-linked Immuno Spot assay (ELISpot) and flow cytometry studies were followed by tumor size and survival rate measurements in a TUBO tumor mice model. Results: The results showed that mice vaccinated with the P5 peptide plus PADRE plus CpG produced higher antigen-specific CTL responses than mice vaccinated with the P5 peptide alone. Also, tumors in those mice grew more slowly and the survival rates were greater than mice in the other groups. Conclusion: We conclude that peptide vaccines containing epitopes that stimulate both CD4+ and CD8+ T-cells are effective at inducing anti-tumor immunity.

Background: The ultimate goal of the study was to find a role of curcumin in targeting lung cancer stem cells by reducing their self-renewal efficiency causing DNA damage. Materials and Methods: Circulating lung cancer stem cells were isolated by sphere formation assay and further analysed by flow-cytometry and qRT-PCR for the presence of stem cell and stem cell transcription markers. The IC50 values of gemcitabine and curcumin were analysed by MTT assay, while curcumin induced DNA damage was scrutinized by single cell gel electrophoresis assay. Results and Conclusion: Our results demonstrated that curcumin significantly affect the self-renewal ability of circulating lung cancer stem cells. The no. of spheres formed in the presence of curcumin was shown to be significantly decreased. Additionally, our results depicted that 4.52±0.72 % and 95.47±0.72 % (p < 0.0001) of DNA material was found to be present in head and tail, respectively, suggesting curcumin’s functional potential to cause DNA damage. Thus, we can conclude that curcumin can be used to target lung cancer stem cells which is responsible for the disease progression and metastasis by causing DNA damage or inhibiting their DNA repair mechanisms.

Background: In cancer, apoptosis relevant proteins—such as CaM kinase, Bcl-2 or P53, topoisomerase I, cell migration feature and DNA/BSA—macromolecules represent significant targets for current chemotherapeutics. Objective: We recently reported two coordination compounds—[Cu(C6H16N2O2)2][Ni(CN)4] (1) and [Cu(C6H16 N2O2)Pd(CN)4] (2)—together with their IR spectra, magnetic properties, thermal analyses and crystal structures. Herein, we describe the ability of these complexes to induce apoptosis in relevant proteins and stimulate topoisomerase I activity, cell migration velocity and DNA/BSA binding properties. Method: The in vitro antiproliferative effects and cell toxicity of both compounds were investigated through pharmacological measurement techniques, and interactions between both compounds and CT-DNA/BSA were studied with UV-Vis spectroscopy and fluorescence spectroscopy. Results & Conclusion: Studies on cells revealed that 2 (i) demonstrated a high antiproliferative effect, which was higher toward HeLa and C6 cancer cells than toward healthy Vero cells; (ii) impaired the migration of HeLa cells; (iii) altered the P53-Bcl-2 ratio in favor of apoptosis; (iv) strongly bound to DNA/BSA macromolecules; and (v) inhibited human topoisomerase I and KpnI or BamHI restriction endonucleases. In conclusion, this preliminary information demonstrates that 2 may represent a promising antiproliferative agent and a potential candidate for a therapeutic approach against HeLa.

Background: The high mortality rate of lung cancer is highly associated with faster metastasis spread. All Trans Retinoic Acid (ATRA), being the first choice drug for leukemia therapy is now under intense study for its therapeutic efficiency in other solid cancers. Objectives: This study was aimed to investigate the anti-metastasis activity of free ATRA and liposome entrapped ATRA (5:4:1) in the experimental C57BL/6 mice model developed by the injection of B16F10 cell line into the tail vein. Method: The ATRA drug was given via i.p for 21 days. The visual lung and liver metastatic tumor nodules were noted. Various biochemical markers of cancer metastasis in the serum as well as tissues were also analyzed after sacrifice. Results: Tumor nodules have significantly decreased in ATRA treatment groups (32.83 ± 1.83 for free ATRA, 23 ± 2.36 for DSPC Lipo-ATRA) when compared with metastasis control (63.16 ± 2.9) in the lungs. Among the treatment groups, the DSPC lipo-ATRA treated group showed a significant tumor growth inhibition (63.6%) than that of in the free ATRA treated groups (48%). Similar anti-metastatic effect was observed in liver also. Furthermore lipo-ATRA has shown a significant change in the levels of biochemical cancer markers analyzed in this study. Conclusion: Our results concluded that the liposome encapsulated ATRA has an enhanced anti-metastasis potency than the free ATRA during B16F10 metastatic cell line implantation.