Anti-Cancer Agents in Medicinal Chemistry (Formerly Current Medicinal Chemistry - Anti-Cancer Agents) - Volume 15, Issue 4, 2015

Tumor resistance and low drug efficacy prompt to investigate new therapeutic strategies that have high efficacy and low toxicity, especially for cancers with poor prognosis. This goal has been recently achieved using particular pharmaceutical combination or nanotechnologies to specifically deliver drugs at the tumor site. Novel combined treatments employ either naturally active ingredients or drugs already intended for other uses, with the aim to increase cell sensitivity to therapy and reduce drug toxicity. Combined treatments usually improve the overall therapeutic efficacy of the single drug. Drug–drug interactions allow synergistic effects. Several evidences indicate that synergy can be affected by drug–drug ratio and drug administration order. Therapeutic efficacy can be enhanced through drug entrapment in nanocarriers that allow a site-specific targeting, resulting in a build-up of the drug in the tumor with a significant toxicity reduction. Several studies investigated combined entrapment of two or more drugs each one characterized by different mechanisms of action. These nanosystems improve synergistic efficacy and could be a device to resolve toxicity and multi-drug resistance. Nano-encapsulation of anticancer agents by targeting specific tumor tissues significantly optimizes drug bioavailability, biocompatibility and therapeutic efficacy. The efficacy of these formulations results from receptor-mediated endocytosis and prolonged circulation time. Drug encapsulation also allows using limited final concentration while avoiding its activity within the blood circulation. In this review we report recent findings about novel combined treatment focusing on synergistic effects and mechanisms of action. We will also overview the latest drug delivery system and their therapeutic benefits in cancer treatment.

The ABC (ATP-binding cassette) transporter is one of the largest and most ancient protein families with members functioning from protozoa to human. The resistance of cancer and tumor cells to anticancer drugs is due to the over-expression of some ABC transporters, which may finally lead to chemotherapy failure. The mouse ABC transporters are classified into seven subfamilies by phylogenetic analysis. The mouse ABC transporter gene, alias, chromosomal location and function have been determined. Within the ABC super-family, the MDR transporters (Abcb1, Abcc1, Abcg2) in mouse models have been proved to be valuable to investigate the biochemistry and physiological functions. This review concentrates on the multidrug resistance of mouse ABC transporters in cancer and tumor cells.

Small-molecule cytotoxic agents are already in use for cancer immunotherapy in the form of antibody conjugates containing these molecules linked covalently to antibodies or their fragments with the goal of targeting specific surface components of tumor cells. However, there are also reports of small molecules that act as antagonists to surface enzyme-linked receptors and receptors that interact with the tumor microenvironment, or that even inhibit metabolic enzymes. Such molecules have been shown to directly inhibit the signaling initiated by the respective ligands binding to their receptors, to recruit antibodies and other immunomodulatory molecules, or to promote or inhibit the proliferation of different immune cells to target specific types of cancer cells. This review will discuss immune response modifiers such as imiquimod, antibody-recruiting molecules that target prostate cancer, integrin receptor antagonists, indoleamine-2,3-dioxygenase inhibitors, emodin, RORt antagonists, ephrin receptor antagonists, membrane-bound carbonic anhydrase IX (CAIX) inhibitors, and selected protein kinase inhibitors. These small molecules can open up new ways to treat many types of cancers and possibly even other diseases that arise from immune dysregulation. Finally, the review will briefly discuss some additional targets that are being pursued to modify immune system responses in the tumor microenvironment.

Hepatocellular carcinoma (HCC) is one of the most common and rapidly fatal malignancies worldwide with poor prognosis. Most of the HCC patients died quickly because of the rapid tumor progression with no effective therapy except for liver resection or transplantation. Recently, microRNAs (miRNAs) have emerged as key factors involved in a series of biological processes ranging from embryogenesis to programmed cell death with aberrant expression profiles, potentially attractive diagnosis, prognosis or therapeutic applications for related-diseases. Accumulating evidences have indicated the roles of miRNAs as tumor suppressor in hepatocyte malignant transformation including development, differentiation, proliferation and tumorigenesis. This article reviews that the recent progress underlies the development of novel miRNA-based HCC therapeutic strategies in the coming future.

Increasing knowledge on cellular biology has permitted rapid changes in the treatment of metastatic melanoma. Until 2011, dacarbazine was the gold standard treatment at our disposal. In 2011 the treatment landscape changed dramatically with the approval by the FDA of ipilimumab and vemurafenib. These drugs use two new therapeutic approaches: immunomodulation and the targeting of mutated cellular pathways in tumor cells. These two drugs, used as single agents have shown important increases in overall survival, unseen before in patients with advanced melanoma, but are limited by their toxicities and the appearance of acquired resistances. In this article, we review new therapeutic options in pathway-targeted –with the arrival of MEK inhibitors - and immune based melanoma therapies –with the arrival of anti-PD1 and anti-PDL1- as well as new therapeutic strategies developed to overcome acquired resistance and diminish drug toxicities.

Fulvenes represent a class of molecules very interesting under a chemical point of view because are easily accessible starting materials and are still poorly characterized for their biological activities, with the exception of acylfulvene and irofulvenes which have been reported to exert cytotoxic properties. Here, we describe the synthesis and characterization of several aryl-fulvenes together with their effects on cancer cell growth by MTT method. The cytotoxic potential was investigated on a panel of tumor cell lines such as breast MCF7 and SkBr3, endometrial Ishikawa, prostate LnCaP and lung A549, in comparison with the cis-diamminedichloroplatinum(II) (cisplatin) which is largely used for the treatment of different types of cancer. The evaluation of the cytotoxic activity of these compounds indicated that they are able to inhibit the proliferation of the aforementioned cancer cell types. In particular, the compound 4 exhibited the most powerful antiproliferative activity on all tumor cells evaluated with higher inhibitory effects respect to cisplatin and without altering the proliferation of human mammary MCF-10A epithelial cells.

The chemotherapeutic agent vincristine, used for treatment of acute lymphoblastic leukemia is metabolized preferentially by polymorphic cytochrome P450 3A5 (CYP3A5) with higher clearance rate than cytochrome P450 3A4 (CYP3A4). As a result, CYP3A5 expressers have a reduced amount of vincristine-induced peripheral neuropathy than non–expressers. We modeled the structure of CYP3A5 and its interaction with vincristine, compared with CYP3A4-vincristine complex using molecular docking and simulation studies. This relative study helped us to understand the molecular mechanisms behind the interaction at the atomic level through interaction energy, binding free energy, hydrogen bond and solvent accessible surface area analysis - giving an insight into the binding mode and the main residues involved in this particular interaction. Our results show that the interacting groups get closer in CYP3A5-vincristine complex due to different orientation of vincristine. This leads to higher binding affinity of vincristine towards CYP3A5 compared to CYP3A4 and explains the preferential metabolism of vincristine by CYP3A5. We believe that, the results of the current study will be helpful for future studies on structure-based drug design in this area.

Accumulating evidences have reported that caffeine has anticancer effects at high blood concentrations. However, whether caffeine has anticancer effects on human hepatocellular carcinoma (HCC) cells at low concentration, especially at physiologically applicable concentration (< 412 μM) is still not well understood. In this study, HCC cell lines HepG2 and Huh7 were used. The cells were incubated with varying concentrations of caffeine (0, 50, 100, 200, 400 or 600 μM). MTT assay was used to investigate the proliferation ability in vitro. Migration and invasion abilities were determined by wound healing assay and transwell assay. The molecular changes were detected by western blot. An ectopic nude mice model which the mice were gavaged with caffeine was used to reveal the anticancer effects of caffeine on HepG2 cells in vivo. Results showed that caffeine could inhibit the proliferation, migration and invasion significantly at physiologically applicable concentration in vitro. Also the associated molecular changes of cancer progression were observed. In animal experiment, the mice gavaged with caffeine also performanced reduced tumor burden in vivo. Moreover, the interrelated protein expression was also observed in vivo which was coincident with the results in vitro. All in all, this observation indicated that caffeine may suppress the progression of HCC through Akt signaling pathway. This makes caffeine a potential candidate for treating HCC which will be a safer and more effective treatment by giving for a long time at physiologically applicable concentration.

A number of N-alkylated 4-anilinofuro[2,3-b]quinoline derivatives were synthesized and evaluated in vitro against PC-3, A549, and MCF-7 cancer cells and M-10 normal human mammary epithelial cells. The known antimitotic CIL-102 was moderately active against the growth of PC-3 prostate cancer cells with an IC50 value of 2.69 μM while it was more potent against the growth of A549, MCF-7 and M-10 cells with IC50 values of 0.61, 0.31 and 0.95 μM, respectively. However, the cytotoxic profiles of its N-alkylated derivatives, 6a - 6c, were reversed and strongly inhibited PC-3 cell growth with IC50 values of less than 1.0 μM but only weakly against the growth of A549, MCF-7 and M-10 cells. These results indicated that N-alkylation of CIL-102 increased not only selectivity but also the antiproliferative potency against PC-3 cell growth. Among these derivatives synthesized, N-(4-acetylphenyl)-N-(furo[2,3-b]quinolin- 4-yl)methylamine (6a) and its N-ethyl counterpart 6b are the two most active CIL-102 derivatives against PC-3 cell growth with IC50 value of 0.22 and 0.20 μM, respectively. Compound 6a is less cytotoxic to normal human M-10 cells than 6b and therefore was selected for further mechanism studies. The flow cytometry studies clearly indicated that compound 6a induced cell accumulation in G2/M phase in a dose-dependent manner after 24 h-treatment. While the proliferation of LNCaP C-81 prostate cancer cells was also strongly suppressed by compound 6a; compound 11a exhibited better selective activity toward LNCaP C-81 prostate cancer cells over RWPE-1 non-cancerous prostate epithelia. Thus, this group of compounds has a potential of serving as therapeutic agents toward advanced castration-resistant prostate cancers.

Various preclinical, clinical and epidemiological studies have already well established the cancer chemopreventive and chemoprotective potential of selenium compounds. In addition to its protective efficacy, recent studies have also proved the abilities of selenium compounds to induce cell death specifically in malignant cells. Therefore, our intention is to improve the therapeutic efficacy of an alkylating agent, cisplatin, by the adjuvant use of an organoselenium compound, diphenylmethyl selenocyanate (DMSE). It was observed that combined treatment decreased the tumor burden significantly through reactive oxygen species generation and modulation of antioxidant and detoxifying enzyme system in tumor cells. These activities ultimately led to significant DNA damage and apoptosis in tumor cells. Study of the molecular pathway disclosed that the adjuvant treatment caused induction of p53, Bax and suppressed Bcl-2 followed by the activation of caspase cascade. Furthermore, a concomitant decrease in cisplatin-induced nephrotoxicity and hematopoietic toxicity by DMSE might also have enhanced the efficacy of cisplatin and provided survival advantage to the host. Results suggested that the combination treatment with DMSE and cisplatin may offer potential therapeutic benefit, and utilization of cisplatin in cancer chemotherapy exempt of its limitations.

Background: Berberine is an extract of a traditional Chinese herbal medicine and has been shown to inhibit the proliferation and induce apoptosis in a wide variety of tumour cells. However, the effects of Berberine in ovarian cancer cells are unknown. Aims: To investigate the potential anti-cancer effects of Berberine in human ovarian cancer cells. Methods: Cell proliferation was evaluated by a MTT assay. Apoptosis was determined by using Annexin V/PI staining and transmission electron microscopy. The methylation status of the hMLH1 promoter CpG islands was analysed by using methylation-specific polymerase chain reaction (MSP). mRNA expression of BCLM-2, BAX, survivin and HMLH1 was quantified by real-time fluorescence quantitative RT-PCR. Results: Berberine significantly inhibited the proliferation of SKOV3 cells in a dose- and time-dependent manner. It also dosedependently induced apoptosis, possibly through down-regulating the anti-apoptotic genes BCL-2; and survivin, and up-regulating the pro-apoptotic gene BAX. When combined with cisplatin, Berberine showed a strong synergistic anticancer effect against ovarian cancer cells. In addition, Berberine was found to restore the demethylation status of the hMLH1 promoter and up-regulate the mRNA expression of hMLH1. Conclusion: Berberine possesses antitumor effect via inhibition of cell proliferation and induction of apoptosis in ovarian cancer cells. Berberine could synergistically enhance the cell killing effect of other antitumor agents such as cisplatin. Further studies are essential to explore the therapeutic potential of Berberine either alone or in combination with other anticancer agents in patients with ovarian cancer.

A series of N-aryl derivatives of pyrrole and its related derivatives of fused form (namely; tetrahydroindole and dihydroindenopyrroles) were prepared in fair to good yields. The newly synthesized compounds were confirmed using IR, 1H NMR, Mass spectral and elemental analysis. Tetrahydrobenzo[b] pyrroles Ia-d, 1,4-dihydroindeno[1,2-b]pyrroles IIa,b and pyrroles IIIa-c,e were evaluated for anticancer activity, coinciding with the antioxidant activity; using Di-Phenyl Picryl Hydrazyl (DPPH) tests. The cytotoxicity of the tested compounds (at a concentration of 100 and 200 μg /mL) was performed against HepG-2 and EACC cell lines. Compounds Ib, d and IIa showed promising antioxidant activity beside their anticancer activity. Docking studies were employed to justify the promising anticancer activity of Ib,d and IIa. Protein kinase (PKase)-PDB entry 1FCQ was chosen as target enzyme for this purpose using the MOLSOFT ICM 3.4-8C program. The docking results of the tested compounds went aligned with the respective anticancer assay results.

Osteosarcoma (OS) is the second most common primary malign bone neoplasm after multiple myeloma. Despite systemic chemotherapy, OS may give rise to local recurrences and metastases. Resistance to chemotherapy is not rare and is likely to occur in a high number of patients. Novel therapeutic approaches are required in order to efficiently treat osteosarcoma. Tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL) and proteasome inhibitors (epoxomicin, MG132, bortezomib) represent new promising approaches in cancer treatment. The aim of our study is to elucidate the effects of epoxomicin alone or in combination with TRAIL in two TRAIL-resistant OS cell lines, Saos-2 and MG-63 namely. We determined the cytotoxic effects of epoxomicin and/or TRAIL on these two types of OS cells using dimethylthiazolyl 2,5 diphenyltetrazolium bromide (MTT) test and measured apoptosis markers such as pro-apoptotic Bax levels and caspase-3, -8, -9 activities. We used TUNEL assay to demonstrate apoptosis. We investigated dose and time dependent survival rates of OS cells and determined LD50 doses of epoxomicin and TRAIL on OS cell viability after 24, 48, and 72 hour incubations. Concurrent incubation with TRAIL and epoxomicin for 24 hour significantly increased caspase-3, caspase-8, caspase-9 activities and Bax protein levels. Our study demonstrated that the combination of TRAIL with epoxomicin enhances apoptosis, and overcomes TRAIL resistance, denoting promising results for OS therapy in the future.