Design, synthesis and SAR studies of novel 1,2-bis(aminomethyl)cyclohexane platinum(II) complexes with cytotoxic activity. Studies of interaction with DNA of iodinated seven-membered 1,4-diaminoplatinocycles

Glucosamine-Modified Reduction-Responsive Polymeric Micelles for Liver Cancer Therapy

In this work, glucose transporter-1 (GLUT-1) and glutathione (GSH) over-expression in liver cancer was utilized to design a reduction-responsive and active targeting drug delivery system AG-PEG-SS-PCL (APSP) for the delivery of sorafenib (SF). The SF-APSP micelles were prepared using the thin film hydration method and characterized by various techniques. In vitro release experiments showed that the cumulative release of SF-APSP micelles in the simulated tumor microenvironment (pH 7.4 with GSH) reached 94.76 ± 1.78% at 48 h, while it was only 20.32 ± 1.67% in the normal physiological environment (pH 7.4 without GSH). The in vitro study revealed that glucosamine (AG) enhanced the antitumor effects of SF, and SF-APSP micelles inhibited proliferation by targeting HepG2 cells and suppressing cyclin D1 expression. The in vivo antitumor efficacy study further confirmed that the SF-APSP micelles had excellent antitumor effects and better tolerance against nude mouse with HepG2 cells than other treatment groups. All in all, these results indicated that SF-APSP micelles could be a promising drug delivery system for anti-hepatoma treatment.

Unfolded Protein Response is Involved in Trans-Platinum (II) Complex-Induced Apoptosis in Prostate Cancer Cells via ROS Accumulation

BACKGROUND

Prostate cancer is one of the most common cancer types and it is the sixth leading cause of cancer-related death in men worldwide. Even though novel treatment modalities have been developed, it still a lifethreatening disease. Therefore novel compounds are needed to improve the overall survival.

METHODS

In our study, it was aimed to evaluate the anti-cancer activity of newly synthesized Platinum (II) [Pt(II)] complex on DU145, LNCaP and PC-3 prostate cancer cell lines. The cytotoxic activity of Pt(II) complex was tested by SRB and ATP cell viability assays. To detect the mode of cell death; fluorescent staining, flow cytometry and western blot analyses were performed.

RESULTS

The Pt(II) complex treatment resulted in a decrease in cell viability and increasing levels of apoptotic markers (pyknotic nuclei, annexin-V, caspase 3/7 activity) and a decrease in mitochondrial membrane potential in a dose dependent manner. Among cell types, tested PC-3 cells were found to be more sensitive to Pt(II) complex, demonstrating elevation of DNA damage in this cell line. In addition, Pt(II) complex induced Endoplasmic Reticulum (ER) stress by triggering ROS generation. More importantly, pre-treatment with NAC alleviated Pt(II) complex-mediated ER stress and cell death in PC-3.

CONCLUSION

These findings suggest an upstream role of ROS production in Pt(II) complex-induced ER stressmediated apoptotic cell death. Considering the ROS-mediated apoptosis inducing the effect of Pt(II) complex, it warrants further evaluation as a novel metal-containing anticancer drug candidate.

Design and synthesis of new antitumor agents with the 1,7-epoxycyclononane framework. Study of their anticancer action mechanism by a model compound

This article describes the design, synthesis and biological evaluation of a new family of antitumor agents having the 1,7-epoxycyclononane framework. We have developed a versatile synthetic methodology that allows the preparation of a chemical library with structural diversity and in good yield. The synthetic methodology has been scaled up to the multigram level and can be developed in an enantioselective fashion. The study in vitro of a model compound, in front of the cancer cell lines HL-60 and MCF-7, showed a growth inhibitory effect better than that of cisplatin. The observation of cancer cells by fluorescence microscopy showed the presence of apoptotic bodies and a degradation of microtubules. The study of cell cycle and mechanism of death of cancer cells by flow cytometry indicates that the cell cycle arrested at the G₀/G₁ phase and that the cells died by apoptosis preferably over necrosis. A high percentage of apoptotic cells at the subG₀/G₁ level was observed. This indicates that our model compound does not behave as an antimitotic agent like nocodazole, used as a reference, which arrests the cell cycle at G₂/M phase. The interaction of anticancer agents with DNA molecules was evaluated by atomic force microscopy, circular dichroism and electrophoresis on agarose gel. The results indicate that the model compound has not DNA as a target molecule. The in silico study of the model compound showed a potential good oral bioavailability.

Synthesis of the 10-oxabicyclo[5.2.1]decane framework present in bioactive natural products

The present work deals with the synthesis of the 10-oxabicyclo[5.2.1]decane framework present in bioactive natural products like physalins, with potential as antitumor agents. This synthetic methodology involves several key reactions: (a) synthesis of polyfunctionalized cycloheptenones by [4 + 3] cycloaddition reactions of furan precursors with oxyallyl cations; (b) Nicholas reaction with propargyl cations stabilized as dicobalt hexacarbonyl complexes; (c) demetallation and hydration of the resulting acetylenes; (d) stereoconvergent aldol cyclization to generate a key oxatricyclic intermediate and (e) a β-fragmentation process that affords, under hypoiodite photolysis, the desired product with moderate to good yield. The final compounds are the result of a radicalary β-fragmentation at the level of C2-C6 with respect to the tertiary hydroxyl group on C6, with an unexpected contraction from a ten- to a nine-membered ring system, via a radical addition to the carbonyl group on C4. The synthetic methodology has been scaled up to multigram level with good overall yield. Further biological, biochemical and biophysical studies are being carried out in our laboratory on these 1,7-epoxycyclononane derivatives to determine the potential of this kind of oxabicyclic compound as future hits and/or leads for the development of new anticancer drugs. The preliminary evaluation of the anticancer activity of the representative synthesized compounds, against the leukaemia cancer cell lines K-562 and SR, shows a promising activity with a GI₅₀ = 0.01 μM and a LC₅₀ = 7.4 μM for a conveniently functionalized 10-oxabicyclo[5.2.1]decane.

Research progress in modern structure of platinum complexes

Since the antitumor activity of cisplatin was discovered in 1967 by Rosenberg, platinum-based anticancer drugs have played an important role in chemotherapy in clinic. Nevertheless, platinum anticancer drugs also have caused severe side effects and cross drug resistance which limited their applications. Therefore, a significant amount of efforts have been devoted to developing new platinum-based anticancer agents with equal or higher antitumor activity but lower toxicity. Until now, a large number of platinum-based complexes have been prepared and extensively investigated in vitro and in vivo. Among them, some platinum-based complexes revealing excellent anticancer activity showed the potential to be developed as novel type of anticancer agents. In this account, we present such platinum-based anticancer complexes which owning various types of ligands, such as, amine carrier ligands, leaving groups, reactive molecule, steric hindrance groups, non-covalently binding platinum (II) complexes, Platinum(IV) complexes and polynuclear platinum complexes. Overall, platinum-based anticancer complexes reported recently years upon modern structure are emphasized.

In vitro and in vivo anti-tumor effects of selected platinum(IV) and dinuclear platinum(II) complexes against lung cancer cells

In the present study, cytotoxic effects of cisplatin, the most usually used chemotherapeutic agent, were compared with new designed platinum(IV) ([PtCl₄(en)] (en = ethylenediamine) and [PtCl₄(dach)]) (dach = (±)-trans-1,2-diaminocyclohexane) and platinum(II) complexes ([{trans-Pt(NH₃)₂Cl}₂(μ-pyrazine)](ClO₄)₂ (Pt1), [{trans-Pt(NH₃)₂Cl}₂(μ-4,4'-bipyridyl)](ClO₄)₂DMF(Pt2),[{trans-Pt(NH₃)₂Cl}₂(μ-1,2-bis(4pyridyl)ethane)](ClO₄)₂ (Pt3)), in vitro and in vivo against human and murine lung cancer cells, to determine anti-tumor potential of newly synthesized platinum-based drugs in the therapy of lung cancer. Results obtained by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide], Lactate dehydrogenase and Annexin V/Propidium Iodide assays showed that, among all tested complexes, [PtCl₄(en)] had the highest cytotoxicity against human and murine lung carcinoma cells in vitro. [PtCl₄(en)] showed significantly higher cytotoxicity then cisplatin in all tested concentrations, mainly by inducing apoptosis in lung cancer cells. [PtCl₄(en)] was well tolerated in vivo. Clinical signs of [PtCl₄(en)]-induced toxicity, such as changes in food, water consumption or body weight, nephrotoxicity or hepatotoxicity was not observed in [PtCl₄(en)]-treated mice. [PtCl₄(en)] managed to increase presence of CD45+ leukocytes, including F4/80+ macrophages, CD11c+ dendritic cells, CD4+ helper and CD8+ cytotoxic T cells (CTLs) in the lungs, cytotoxic NK, NKT and CTLs in the spleens of tumor bearing mice, resulting with reduction of metastatic lesions in the lungs, indicating its potential to stimulate anti-tumor immune response in vivo. Due to its anti-tumor cytotoxicity, biocompatibility, and potential for stimulation of anti-tumor immune response, [PtCl₄(en)] may be a good candidate for further testing in the field of medicinal chemistry.

Cytotoxicity and cellular response mechanisms of water-soluble platinum(II) complexes of lidocaine and phenylcyanamide derivatives

Three new platinum(II) complexes of lidocaine and phenylcyanamide derivative ligands of formula K[Pt(3,5-(NO₂)₂pcyd)₂(LC)], 1, K[Pt(3,5-(CF₃)₂pcyd)₂(LC)], 2, K[Pt(3,5-Cl₂pcyd)₂(LC)], 3 (LC: lidocaine, 3,5-(NO₂)₂pcyd: 3,5-dinitro phenylcyanamide, 3,5-(CF₃)₂pcyd: 3,5-bis(trifluoromethyl) phenylcyanamide, 3,5-Cl₂pcyd: 3,5-dichloro phenylcyanamide) have been synthesized and fully characterized. Cellular uptake, DNA platination and cytotoxicity against a panel of human tumor cell lines were evaluated. The complexes 1-3 revealed a significant in vitro antiproliferative activity against human ovarian carcinoma (A2780), colorectal adenocarcinoma (HT29), breast (MCF-7), liver hepatocellular carcinoma (HepG-2) and lung adenocarcinoma (A549) cancer cell lines. All the complexes are more active than cisplatin and follow the trend 1 > 2 > 3. Mechanistic studies showed that the trend in cytotoxicity of the Pt(II) complexes is mainly consistent with their ability to accumulate into cancer cells and to increase intracellular basal reactive oxygen species levels, which consequently results in the loss of mitochondrial membrane potential and apoptosis induction. The complex 1 caused to approximately 80-fold higher DNA platination level with respect to cisplatin. The complexes 1-3 can considerably stimulate the production of hydrogen peroxide in a time-dependent manner. Also, the complexes 1-3 induced an increase in reactive oxygen species (ROS) production that was superior to that induced by antimycin. The complex 1 had the most effect on ROS production in comparison with other complexes.