Biochemical Studies of the Thermal Effects on DNA Modifications by the Antitumor Cisplatin and Their Repair

A Nanoscale Trans-Platinum(II)-Based Supramolecular Coordination Self-Assembly with a Distinct Anticancer Mechanism

Drug resistance significantly hampers the clinical application of existing platinum-based anticancer drugs. New platinum medications that possess distinct mechanisms of action are highly desired for the treatment of Pt-resistant cancers. Herein, a nanoscale trans-platinum(II)-based supramolecular coordination self-assembly (Pt-TCPP-BA) is prepared via using trans-[PtCl2(pyridine)(NH3)] (transpyroplatin), tetracarboxylporphyrin (TCPP), and benzoic acid (BA) as building blocks to combat drug resistance in platinum-based chemotherapy. Mechanistic studies indicate that Pt-TCPP-BA shows a hydrogen-peroxide-responsive dissociation behavior along with the generation of bioactive trans-Pt(II) and TCPP-Pt species. Different from cisplatin, these degradation products interact with DNA via interstrand cross-links and small groove binding, and induce significant upregulation of cell-death-related proteins such as p53, cleaved caspase 3, p21, and phosphorylated H2A histone family member X in cisplatin-resistant cancer cells. As a result, Pt-TCPP-BA exhibits potent killing effects against Pt-resistant tumors both in vitro and in vivo. Overall, this work not only provides a new platinum drug for combating drug-resistant cancer but also offers a new paradigm for the development of platinum-based supramolecular anticancer drugs.

Personalized Identification of Optimal HIPEC Perfusion Protocol in Patient-Derived Tumor Organoid Platform

BACKGROUND

Chemotherapy dosing duration and perfusion temperature vary significantly in HIPEC protocols. This study investigates patient-derived tumor organoids as a platform to identify the most efficacious perfusion protocol in a personalized approach.

PATIENTS AND METHODS

Peritoneal tumor tissue from 15 appendiceal and 8 colon cancer patients who underwent CRS/HIPEC were used for personalized organoid development. Organoids were perfused in parallel at 37 and 42 °C with low- and high-dose oxaliplatin (200 mg/m² over 2 h vs. 460 mg/m² over 30 min) and MMC (40 mg/3L over 2 h). Viability assays were performed and pooled for statistical analysis.

RESULTS

An adequate organoid number was generated for 75% (6/8) of colon and 73% (11/15) of appendiceal patients. All 42 °C treatments displayed lower viability than 37 °C treatments. On pooled analysis, MMC and 200 mg/m² oxaliplatin displayed no treatment difference for either appendiceal or colon organoids (19% vs. 25%, p = 0.22 and 27% vs. 31%, p = 0.55, respectively), whereas heated MMC was superior to 460 mg/m² oxaliplatin in both primaries (19% vs. 54%, p < 0.001 and 27% vs. 53%, p = 0.002, respectively). In both appendiceal and colon tumor organoids, heated 200 mg/m² oxaliplatin displayed increased cytotoxicity as compared with 460 mg/m² oxaliplatin (25% vs. 54%, p < 0.001 and 31% vs. 53%, p = 0.008, respectively).

CONCLUSIONS

Organoids treated with MMC or 200 mg/m² heated oxaliplatin for 2 h displayed increased susceptibility in comparison with 30-min 460 mg/m² oxaliplatin. Optimal perfusion protocol varies among patients, and organoid technology may offer a platform for tailoring HIPEC conditions to the individual patient level.

HIPEC with oxaliplatin for colorectal peritoneal metastasis: The end of the road?

In patients with colorectal peritoneal metastases (PM), the use of cytoreductive surgery (CRS) and HIPEC with oxaliplatin (OX) is increasingly used. The results of the recently reported randomized Prodige 7 trial failed to show a difference in overall survival between patients undergoing CRS alone versus CRS combined with HIPEC using high dose OX. The trial was not designed or powered, however, to detect a potentially clinically meaningful benefit in locoregional disease control. Here, I address some potential explanations for the lack of benefit in the Prodige 7 trial, including OX efficacy issues, adverse effects of intraperitoneal high dose glucose, and potential drawbacks of the use of hyperthermia.

Magnetic nanoparticles and nanocomposites for remote controlled therapies

This review highlights the state-of-the-art in the application of magnetic nanoparticles (MNPs) and their composites for remote controlled therapies. Novel macro- to nano-scale systems that utilize remote controlled drug release due to actuation of MNPs by static or alternating magnetic fields and magnetic field guidance of MNPs for drug delivery applications are summarized. Recent advances in controlled energy release for thermal therapy and nanoscale energy therapy are addressed as well. Additionally, studies that utilize MNP-based thermal therapy in combination with other treatments such as chemotherapy or radiation to enhance the efficacy of the conventional treatment are discussed.

Comparative thermal and thermodynamic study of DNA chemically modified with antitumor drug cisplatin and its inactive analog transplatin

Antitumor activity of cisplatin is exerted by covalent binding to DNA. For comparison, studies of cisplatin-DNA complexes often employ the very similar but inactive transplatin. In this work, thermal and thermodynamic properties of DNA complexes with these compounds were studied using differential scanning calorimetry (DSC) and computer modeling. DSC demonstrates that cisplatin decreases thermal stability (melting temperature, Tm) of long DNA, and transplatin increases it. At the same time, both compounds decrease the enthalpy and entropy of the helix-coil transition, and the impact of transplatin is much higher. From Pt/nucleotide molar ratio rb=0.001, both compounds destroy the fine structure of DSC profile and increase the temperature melting range (ΔT). For cisplatin and transplatin, the dependences δTm vs rb differ in sign, while δΔT vs rb are positive for both compounds. The change in the parameter δΔT vs rb demonstrates the GC specificity in the location of DNA distortions. Our experimental results and calculations show that 1) in contrast to [Pt(dien)Cl]Cl, monofunctional adducts formed by transplatin decrease the thermal stability of long DNA at [Na(+)]>30mM; 2) interstrand crosslinks of cisplatin and transplatin only slightly increase Tm; 3) the difference in thermal stability of DNA complexes with cisplatin vs DNA complexes with transplatin mainly arises from the different thermodynamic properties of their intrastrand crosslinks. This type of crosslink appears to be responsible for the antitumor activity of cisplatin. At any [Na(+)] from interval 10-210mM, cisplatin and transplatin intrastrand crosslinks give rise to destabilization and stabilization, respectively.

Synergism between propolis and hyperthermal intraperitoneal chemotherapy with cisplatin on ehrlich ascites tumor in mice

We investigated antitumor, genotoxic, chemopreventive, and immunostimulative effects of local chemoimmunotherapy and hyperthermal intraperitoneal chemotherapy (HIPEC) in a mouse-bearing Ehrlich ascites tumor (EAT). Mice were treated with water-soluble derivative of propolis (WSDP) at a dose of 50 mg kg(-1) , 7 and 3 days before implantation of EAT cells, whereas cisplatin (5 or 10 mg kg(-1) ) was injected 3 days after implantation of EAT cells at 37°C and 43°C. The following variables were analyzed: the total number of cells, differential count of the cells present in the peritoneal cavity, functional activity of macrophages, comet assay, and micronucleus assay. The combination of WSDP + CIS 5 mg kg(-1) at 37°C resulted in tumor growth inhibition and increased the survival of mice by additional 115.25%. WSDP with HIPEC increased the survival of mice by additional 160.3% as compared with HIPEC. WSDP reduced cisplatin toxic and genotoxic effect to normal cells without affecting cisplatin cytotoxicity on EAT cells. In addition, WSDP with HIPEC increased the cytotoxic actions of macrophages to tumor cells. Water-soluble derivative of propolis increases macrophage activity and sensitivity of tumor cells to HIPEC and reduces cisplatin toxicity to normal cells.

DNA interactions of dinuclear RuII arene antitumor complexes in cell-free media

We recently synthesized and characterized water-soluble dinuclear Ru(II) arene complexes, in which two {(eta(6)-p-isopropyltoluene)RuCl[3-(oxo-kappaO)-2-methyl-4-pyridinonato-kappaO(4)]} units were linked by flexible chains of different length [(CH(2))(n) (n=4, 6, 8, 12)]. These new dinuclear ruthenium drugs were found to exert promising cytotoxic effects in human cancer cells. In the present work DNA modifications by these new dinuclear Ru(II) arene compounds, which differed in the length of the linker between the two Ru(II) centers, were examined by biochemical and biophysical methods. The complexes bind DNA forming intrastrand and interstrand cross-links in one DNA molecule in the absence of proteins. An intriguing aspect of the DNA-binding mode of these dinuclear Ru(II) compounds is that they can cross-link two DNA duplexes and also proteins to DNA--a feature not observed for other antitumor ruthenium complexes. Thus, the concept for the design of interhelical and DNA-protein cross-linking agents based on dinuclear Ru(II) arene complexes with sufficiently long linkers between two Ru centers may result in new compounds which exhibit a variety of biological effects and can be also useful in nucleic acids research.