Anti-Cancer Agents in Medicinal Chemistry (Formerly Current Medicinal Chemistry - Anti-Cancer Agents) - Volume 19, Issue 12, 2019

Background: Dimedone and thiazole moieties are privileged scaffolds (acting as primary pharmacophores) in many compounds that are useful to treat several diseases, mainly tropical infectious diseases. Thiazole derivatives are a very important class of compounds due to their wide range of pharmaceutical and therapeutic activities. On the other hand, dimedone is used to synthesize many therapeutically active compounds. Therefore, the combination of both moieties through a single molecule to produce heterocyclic compounds will produce excellent anticancer agents. Objective: The present work reports the synthesis of 47 new substances belonging to two classes of compounds: Dimedone and thiazoles, with the purpose of developing new drugs that present high specificity for tumor cells and low toxicity to the organism. To achieve this goal, our strategy was to synthesize a series of 4,5,6,7-tetrahydrobenzo[d]-thiazol-2-yl derivatives using the reaction of the 2-bromodimedone with cyanothioacetamide. Methods: The reaction of 2-bromodimedone with cyanothioacetamide gave the 4,5,6,7-tetrahydrobenzo[d]- thiazol-2-yl derivative 4. The reactivity of compound 4 towards some chemical reagents was observed to produce different heterocyclic derivatives. Results: A cytotoxic screening was performed to evaluate the performance of the new derivatives in six tumor cell lines. Thirteen compounds were shown to be promising toward the tumor cell lines which were further evaluated toward five tyrosine kinases. Conclusion: The results of antitumor screening showed that many of the tested compounds were of high inhibition towards the tested cell lines. Compounds 6c, 8c, 11b, 11d, 13b, 14b, 15c, 15g, 21b, 21c, 20d and 21d were the most potent compounds toward c-Met kinase and PC-3 cell line. The most promising compounds 6c, 8c, 11b, 11d, 13b, 14b, 15c, 15g, 20c, 20d, 21b, 21c and 21d were further investigated against tyrosine kinase (c-Kit, Flt-3, VEGFR-2, EGFR, and PDGFR). Compounds 6c, 11b, 11d, 14b, 15c, and 20d were selected to examine their Pim-1 kinase inhibition activity the results revealed that compounds 11b, 11d and 15c had high activities.

Background: Lung cancer is one of the most prevalent malignancies and thus the development of novel therapeutic agents for managing lung cancer is imperative. Tetrandrine, a bis-benzyltetrahydroisoquinoline alkaloid isolated from Stephania tetrandra S. Moore, has been found to exert cytotoxic effects on cancerous cells. Methods: A series of 5-alkynyltetrandrine derivatives was synthesized via the Sonogashira cross-coupling reactions and evaluated as potential anti-tumor agents. The anti-tumor activities of 12 compounds on lung cancer cells (A549) were evaluated using the MTT method. The population of apoptotic cells was measured using a TUNEL assay. Real-time PCR quantified the gene expression levels of Bcl-2, Bax, survivin and caspase-3. The content of Cyt-C was detected using a Human Cyt-C ELISA kit. Results: Most of these compounds exhibited better activities than tetrandrine itself on A549 cells. Among them, compound 7 showed the highest cytotoxicity among the tested compounds against human lung adenocarcinoma A549 cells with an IC50 of 2.94 μM. Preliminary mechanistic studies indicated that compound 7 induced apoptosis of human lung cancer A549 cells and increased the level of the proapoptotic gene Bax, release of Cyt-C from mitochondria and activation of caspase-3 genes. Conclusion: The results suggest that compound 7 exerts its antitumor activity against A549 cells through the induction of the intrinsic (mitochondrial) apoptotic pathway. These findings will contribute to the future design of more effective anti-tumor agents in lung cancer therapy.

Objective: Breast Cancer (BC) is the most common type of cancer diagnosed in women. A common treatment strategy for BC is still not available because of its molecular heterogeneity and resistance is developed in most of the patients through the course of treatment. Therefore, alternative medicine resources as being novel treatment options are needed to be used for the treatment of BC. Usnic Acid (UA) that is one of the secondary metabolites of lichens used for different purposes in the field of medicine and its anti-proliferative effect has been shown in certain cancer types, suggesting its potential use for the treatment. Methods: Anti-proliferative effect of UA in BC cells (MDA-MB-231, MCF-7, BT-474) was identified through MTT analysis. Microarray analysis was performed in cells treated with the effective concentration of UA and UA-responsive miRNAs were detected. Their targets and the pathways that they involve were determined using a miRNA target prediction tool. Results: Microarray experiments showed that 67 miRNAs were specifically responsive to UA in MDA-MB-231 cells while 15 and 8 were specific to BT-474 and MCF-7 cells, respectively. The miRNA targets were mostly found to play role in Hedgehog signaling pathway. TGF-Beta, MAPK and apoptosis pathways were also the prominent ones according to the miRNA enrichment analysis. Conclusion: The current study is important as being the first study in the literature which aimed to explore the UA related miRNAs, their targets and molecular pathways that may have roles in the BC. The results of pathway enrichment analysis and anti-proliferative effects of UA support the idea that UA might be used as a potential alternative therapeutic agent for BC treatment.

Background: Various phenolic phytochemical extracts have been claimed to exhibit different types of biological activity, including anti-inflammatory, anti-oxidative and anti-carcinogenic activity. Carnosol and carnosic acid, extracts of rosemary, are among these phenolic compounds. Materials and Methods: CHARMm-based molecular docking was performed to estimate the possible molecular interactions of both carnosic acid and carnosol with the COX-2 active binding site. An MTT assay was used to evaluate HEp-2 cell viability after incubation for 48 hours with low or high concentrations of carnosol, carnosic acid or their combination. The levels of COX-2 were measured in cell lysate by the quantitative indirect ELISA technique. Results: Docking revealed favourable negative binding energies as well as binding interactions of both carnosic acid and carnosol within the binding site of the COX-2 receptor. Carnosic acid showed more favourable binding potential than carnosol. One-way ANOVA and Bonferroni’s post hoc tests revealed significant differences in cytotoxicity among cells treated with different concentrations of the rosemary extracts (P< 0.001). ELISA revealed significant reductions in COX-2 protein levels in HEp-2 cells treated with either carnosic acid (-1.42- fold) or carnosol (-3.16-fold) compared to control cells. Conclusion: Both rosemary extracts, carnosol and carnosic acid, exert potential cytotoxic effects on the HEp-2 cell line via inhibition of the COX-2 pathway. The combination of carnosol and carnosic acid exerts a stronger cytotoxic effect than either compound alone.

Background: Chemotherapeutic drugs have high toxicity associated with undesirable side-effects. Now, natural products are the most important anti-cancer agents because of their low toxicity and potential effectiveness. Methods: The half maximal inhibitory concentration (IC50) of amygdalin, naringenin and ellagic acid against breast, colon, and liver cell lines was estimated. The antimutagenic, free radical-, superoxide radical-, and hydroxyl radical- scavenging activities of these phytochemicals were measured. The expression of p53, bid, bax, bcl2, and caspases 9, 3, and 7 was measured by quantitative real-time polymerase chain reaction (qRT-PCR) in breast and liver cells. In addition, the active Caspase 3 protein was estimated in liver cells. Results: Ellagic acid showed the highest antioxidant and antiproliferative activities. Amygdalin and naringenin with low and moderate antioxidant profiles showed a corresponding low and moderate cytotoxicity against cancer cell lines, respectively. Naringenin and ellagic acid had a significant antimutagenic activity which was detected by the Salmonella test. Ellagic acid offered a much better antimutagenic activity than naringenin. The apoptotic pathway evoked by ellagic acid in HepG2 and MCF-7 cells was investigated. The results showed that a caspase-dependent and a caspase-independent apoptosis occurred in MCF-7 and HepG2, respectively. Conclusion: The antimutagenic/antioxidant properties are well correlated with the antiproliferative activity of the phytochemicals investigated. This study proved that some easy, quick and cheap assays could predict the antiproliferative activity of many nutraceuticals. Finally, this platform could help in the discovery of new anticancer agents where hundreds of compounds are investigated in the pipeline of drug discovery.

Background: Hydantoin and its newly synthesized derivatives have recently become a focus of interest due to their numerous biological activities and newly emerging beneficial effects in different pathological conditions, including cancer. Objective: The aim of this study was to evaluate the possible anti-tumor mechanisms of a series of newly synthesized 3-(4-substituted benzyl)-5-isopropyl-5-phenylhydantoin derivatives in different aspects of cell physiology of human colon cancer cell line, HCT-116. Methods: The increasing concentrations of derivatives (0.01μM up to 100μM) were applied to cells during 24h, 48h, and 72h after which the evaluation of proliferation, apoptosis, oxidative/anti-oxidative status, nitrite production, and migration/invasion potential of treated cells was performed. Results: All tested compounds expressed the dose- and time-dependent anti-proliferative and pro-apoptotic activities against HCT-116 cells. The investigated derivatives induced a decrease in levels of oxidative stress parameters and an increase in levels of nitrite production by treated cells suggesting their significant antioxidative effects. The cell migration index and expression level of tumor invasion-promoting metalloproteinase- 9 (MMP-9) gene were significantly decreased after treatment with the tested hydantoin derivatives implicating their inhibitory role in colon cancer cell motility and invasion processes. The mRNA level of cyclooxygenase-2 (COX-2) gene as a pro-inflammatory gene related to colorectal carcinogenesis was reduced compared to values in the non-treated control cells indicating the significant anti-inflammatory/anti-tumor effects of these compounds. Conclusion: The obtained results show the significant anti-tumor potential of tested derivatives, especially 3- benzyl-5-isopropyl-5-phenylhydantoin and 3-(4-chlorobenzyl)-5-isopropyl-5-phenylhydantoin, suggesting their potential usage in the development of more effective chemotherapies.

Background: Recent studies have suggested that 85% of pancreatic cancer patients accompanied with impaired glucose tolerance or even Diabetes Mellitus (DM) and the invasive and migratory abilities of pancreatic cancer could be enhanced by high glucose. This study aimed to investigate whether Hypoxia- Inducible Factor-1α (HIF-1α) mediates hyperglycemia-induced pancreatic cancer glycolysis. Methods: The cellular glycolytic activity was assessed by determining lactate production, glucose uptake and lactate dehydrogenase enzymatic activity. Pancreatic cancer cells (BxPC-3 cells) were transfected with short hairpin RNA targeting the HIF-1α. Results: Hyperglycemia promotes pancreatic cancer glycolysis. Lactate dehydrogenase A (LDHA) activity and hexokinase 2 (HK2), platelet-type of phosphofructokinase (PFKP) expression were significantly upregulated under hyperglycemic conditions. HIF-1α knockdown prominently down-regulated the activity of LDHA and the expression of HK2, PFKP and decreased lactate production in BxPC-3 cells. Under hypoxia condition, hyperglycemia induced pancreatic glycolysis by mechanisms that are both dependent on HIF-1α and independent of it. Conclusion: The accumulation of HIF-1α induced by hyperglycemia increases LDHA activity and HK2, PFKP expression, thereby promoting pancreatic glycolysis to facilitate cancer progression.

Background: Glutathione (GSH), which is the predominant low molecular weight intracellular thiol in mammals, has multiple functions, such as those of protecting against oxidative stress and detoxifying endogenous and exogenous electrophiles. High GSH levels, which have been observed in various types of tumors, have been thought to contribute to the resistance of neoplastic cells to apoptotic stimuli triggered by pro-oxidant therapy. Although L-(S,R)-Buthionine Sulfoximine (BSO), a selective irreversible inhibitor of glutamate cysteine ligase, depletes GSH in vitro and in in vivo and sensitizes tumor cells to radiation and some cancer chemotherapeutics, its toxicity and short in vivo half-life have limited its application to combination anticancer therapies. Objective: To demonstrate that a folate-targeted PEGylated BSO conjugate can sensitize cancer cells to a Reactive Oxygen Species (ROS)-generating anticancer agent by depleting GSH. Methods: A novel folate-targeted PEGylated-BSO conjugate was synthesized and tested in combination with gemcitabine in human cell lines that over-express (HeLa) or do not express (A549) the folate receptor. Results: The prepared folate-PEG-GFLG-BSO conjugate proved to be efficacious in reducing GSH levels and, when used in combination with the pro-oxidant drug gemcitabine, it enhanced drug activity in the cell line overexpressing the folate receptor. Conclusion: The folate-PEG-GFLG-BSO conjugate studied was found to be effective in sensitizing folatereceptor positive cancer cells to the ROS-generating drug gemcitabine.

Background: Chronic Myeloid Leukaemia (CML) starts in certain blood-forming cells of the bone marrow when cells acquire Philadelphia chromosome. Nowadays, scientists attempt to find novel and safe therapeutic agents and approaches for CML therapy using Tyrosine Kinase Inhibitors (TKIs), CML conventional treatment agents, has some restrictions and also adverse effects. Recently, it has been proposed that phytochemicals, such as flavonoids due to their low side effects and notable safety have the potential to be used for CML therapy. Materials and Methods: K-562 cells were exposed with three concentrations of the querectin (10, 40 and 80μM) for 12, 24 and 48 hours. After that, these cells apoptosis rate was estimated using Annexin-V/PI staining and flowcytometry analysis, and their proliferation rate was evaluated using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT). Finally, the expression of the 70 and 90 kilodalton heat shock proteins (HSP70 and 90), methionine adenosyltransferase 2A (MAT2A), Forkhead box protein M1 (FOXM1), caspase-3 and -8, Bcl-X(L) and Bax involved in leukemic cells survival and proliferation was assessed using Real-Time PCR within 12, 24 and 48 hours after exposure with quercetin 40 and 80μM. Results: Considering consequences, querecetin induced apoptosis in K-562 cells, and also abrogated these cells proliferation. On the other hand, RT-PCR results showed a reduction in some of the candidate genes expression, especially HSP70, Bcl-X(L) and FOXM1, when cells were treated with quercetin 40 and 80μM. Also, Bax, caspase-3 and caspase-8 expression was significantly improved in K-562 cells upon quercetin exposure. Conclusion: We concluded that CML therapy by querecetin due to its anti-proliferative and anti-survival potentials could lead to the promising therapeutic outcome through targeting major survival and proliferation involved genes expression.

Introduction: Deregulation of Thyroid Hormones (THs) system in Colorectal Cancer (CRC) suggests that these hormones may play roles in CRC pathogenesis. Flavonoids are polyphenolic compounds, which possess potent antitumor activities and interfere, albeit some of them, with all aspects of THs physiology. Whether the antitumor actions of flavonoids are affected by THs is unknown. Therefore, we investigated the effects of apigenin (Api), a well-known flavone, on some tumorigenic properties of SW480 CRC cells in the presence and absence of L-thyroxine (T4). Methods: Cell viability was assessed by MTT assay. Flow cytometry and DNA electrophoresis were used to evaluate cell death. Cell senescence was examined by in situ detection of β-galactosidase activity. Protein expression was assessed by antibody array technique. Results: While T4 had minimal effects, Api reduced cell growth and senescence by induction of apoptosis. Expression of anti-apoptotic and pro-apoptotic proteins were differentially affected by Api and T4. Survivin, HSP60 and HTRA were the most expressed proteins by the cells. Almost all Api-induced effects persisted in the presence of T4. Conclusion: These data suggest that Api may inhibit CRC cell growth and progression through induction of apoptosis rather than cell necrosis or senescence. In addition, they suggest that T4 has minimal effects on CRC cell growth, and is not able to antagonize the anti-growth effects of Api. Regardless of the treatments, cells expressed high levels of survivin, HSP60 and HTRA, indicating that these proteins may play central roles in SW480 CRC cell immortality.

Background: Target-based approach to drug discovery currently attracts a great deal of interest from medicinal chemists in anticancer drug discovery and development worldwide, and Histone Deacetylase (HDAC) inhibitors represent an extensive class of targeted anti-cancer agents. Among the most explored structure moieties, hydroxybenzamides and hydroxypropenamides have been demonstrated to have potential HDAC inhibitory effects. Several compounds of these structural classes have been approved for clinical uses to treat different types of cancer, such as vorinostat and belinostat. Aims: This study aims at developing novel HDAC inhibitors bearing quinazolinone scaffolds with potential cytotoxicity against different cancer cell lines. Methods: A series of novel N-hydroxyheptanamides incorporating 6-hydroxy-2 methylquinazolin-4(3H)-ones (14a-m) was designed, synthesized and evaluated for HDAC inhibitory potency as well as cytotoxicity against three human cancer cell lines, including HepG-2 (liver cancer), MCF-7 (breast cancer) and SKLu-1 (lung cancer). Molecular simulations were finally carried out to gain more insight into the structure-activity relationships. ADME-T predictions for selected compounds were also performed to predict some important features contributing to the absorption profile of the present hydroxamic derivatives. Results: It was found that the N-hydroxyheptanamide 14i and 14j were the most potent, both in terms of HDAC inhibition and cytotoxicity. These compounds displayed up to 21-71-fold more potent than SAHA (suberoylanilide hydroxamic acid, vorinostat) in terms of cytotoxicity, and strong inhibition against the whole cell HDAC enzymes with IC50 values of 7.07-9.24μM. Docking experiments on HDAC2 isozyme using Autodock Vina showed all compounds bound to HDAC2 with relatively higher affinities (from -7.02 to -11.23 kcal/mol) compared to SAHA (-7.4 kcal/mol). It was also found in this research that most of the target compounds seemed to be more cytotoxic toward breast cancer cells (MCF-7) than liver (HepG2), and lung (SKLu-1) cancer cells.