No abstract

Cisplatin is one of the most widely used anticancer agents, but a major problem for successful chemotherapy is the development of drug resistance of tumor cells against cisplatin. Resistance to cisplatin is a multifactorial problem. A method to detect and identify intracellular cisplatin-protein adducts was developed using a fluorescent carboxyfluorescein-diacetate-labeled cisplatin analogue (CFDA-cisplatin), 2DE, and ESI-MS/MS. We identified several CFDA-cisplatin-protein adducts including members of the protein disulfide isomerase family (PDI). These are the first results of the detection of intracellular CFDA-cisplatin-protein adducts, which may help to understand the resistance mechanism of cisplatin.

platinum-based chemotherapeutics exhibit excellent antitumor properties. However, these drugs cause severe side effects including toxicity, drug resistance, and lack of tumor selectivity. Tumor-targeted drug delivery has demonstrated great potential to overcome these drawbacks. Herein, we aimed to design radioactive bisphosphonate-functionalized platinum (195m Pt-BP) complexes to confirm preferential accumulation of these pt-based drugs in metabolically active bone. In vitro nMR studies revealed that release of pt from pt Bp complexes increased with decreasing pH. Upon systemic administration to mice, Pt-BP exhibited a 4.5-fold higher affinity to bone compared to platinum complexes lacking the bone-seeking bisphosphonate moiety. these pt-Bp complexes formed less pt-DnA adducts compared to bisphosphonate-free platinum complexes, indicating that in vivo release of pt from pt-Bp complexes proceeded relatively slow. Subsequently, radioactive 195m pt-Bp complexes were synthesized using 195m pt(no 3) 2 (en) as precursor and injected intravenously into mice. Specific accumulation of 195m pt-Bp was observed at skeletal sites with high metabolic activity using micro-Spect/ct imaging. Furthermore, laser ablation-ICP-MS imaging of proximal tibia sections confirmed that 195m pt Bp colocalized with calcium in the trabeculae of mice tibia. Most types of tumors, i.e. breast, prostate, lung, kidney, and thyroid, metastasize to bone since its physiological environment facilitates the formation and growth of cancer cells 1,2. These metastases affect healthy bone, which then become the primary cause of mortality 3. Distant metastases are the leading cause of death for both breast and prostate cancer patients, with 65-75% and 90% of these patients developing bone metastases in advanced stages, respectively 4,5. Bone metastases are often associated with accelerated bone resorption leading to complications such as skeletal-related events (SREs), bone pain or hypercalcemia 6,7. Unfortunately, current treatments for bone metastases are limited. Bisphosphonates (BP) and denosumab are most commonly used for palliative treatment to prevent or limit SREs 8. Although such treatments inhibit osteoclast activity and prevent the progression of metastases, they do not kill cancer cells effectively and do not improve the quality of life of patients substantially 9. Consequently, the development of effective therapies to treat bone metastases remains a major clinical challenge.

This study focuses on interactions between nanoparticles and a pesticide. The aim was to investigate how nano-sized aluminum oxide (410 nm) can alter the toxic effects of thiacloprid, even if no sorption between particles and the insecticide takes place. Thus, our study investigated a rather unexplored interaction. We conducted our research with larvae of Chironomus riparius and used thiacloprid as test substance as its toxicity to C. riparius is well described. The used nano-Al2O3 particles where chosen due to their suitable properties. For testing the acute effects of the interaction, we exposed larvae to thiacloprid (0.5, 1.0, 2.0, and 5.0 μg/L) and nano-Al2O3 (300 and 1000 mg/L), either solely or in binary mixtures. While thiacloprid resulted in elevated mortality, nano-Al2O3 solely did not exert any effects. Moreover, we observed an aggregation of nano-Al2O3 within the lumen of the intestinal tract of the larvae. Further results showed a significantly reduced mortality of fourth instar larvae when they were exposed to mixtures of nanoparticles and the pesticide, compared to thiacloprid alone. With increasing nano-Al2O3 concentration, this effect became gradually stronger. Additionally, chemical analyses of internal thiacloprid concentrations implicate reduced uptake of thiacloprid in animals exposed to mixtures. However, as larvae exposed to thiacloprid concentrations > 0.5 μg/L showed severe convulsions, independent of the presence or concentration of nano-Al2O3, we assume that nano-Al2O3 leads to a delay of mortality and does not entirely prevent it. As sorption measurements on pristine or defecated nano-Al2O3 did not reveal any sorptive interaction with thiacloprid, we can exclude sorption-based reduction of thiacloprid bioavailability as a mechanism behind our results. Even though we used test substances which might not co-occur in the environment in the tested concentrations, our study gives evidence for an interaction besides adsorption, which is important to generally understand how nanoparticles might affect biota.

No abstract