A novel screening method for transition metal‐based anticancer compounds using zebrafish embryo‐larval assay and inductively coupled plasma‐mass spectrometry analysis

Abstract

As novel metallodrugs continue to emerge, they are evaluated using models, including zebrafish, that offer unique sublethal endpoints. Testing metal-based anticancer compounds with high-throughput zebrafish toxicological assays requires analytical methods with the sensitivity to detect these sublethal tissue doses in very small sample masses (e.g., egg mass 100 μg). A robust bioanalytical model, zebrafish embryos coupled with inductively coupled plasma-mass spectrometry (ICPMS) for measurement of delivered dose, creates a very effective means for screening metal-based chemotherapeutic agents. In this study, we used ICPMS quantitation with the zebrafish embryo assays to detect metal equivalents at multiple response endpoints for two compounds, the chemotherapeutic agent cisplatin and ruthenium (Ru)-based prospective metallodrug, PMC79. We hypothesized that cisplatin and PMC79 have different mechanisms for inducing apoptosis and result in similar lesions but different potencies following water-borne exposure. An ICPMS method was developed to detect the metal in waterborne solution and tissue (detection limit: 5 parts per trillion for Ru or platinum [Pt]). The Ru-based compound was more potent (LC 50 : 7.8 μM) than cisplatin (LC 50 : 158 μM) and induced disparate lesions. Lethality from cisplatin exposure exhibited a threshold (values >15 mg/L) while no threshold was observed for delayed hatching (lowest observed adverse effect level 3.75 mg/L cisplatin; 8.7Pt (ng)/organism). The Ru organometallic did not have a threshold for lethality.Cisplatin-induced delayed hatching was investigated further by larval-Pt distribution and preferentially distributed to the chorion. We propose that zebrafish embryolarval assays coupled with ICPMS serve as a powerful platform to evaluate relative potency and toxic effects of metallodrug candidates.

Supercritical CO2 Processing Generates Aqueous Cisplatin Solutions with Enhanced Cancer Specificity

“…46−49 Cisplatin has been shown to effectively kill the hair cells of zebrafish lateral line, 50−53 zebrafish have been used to examine cisplatin, and other metal-based chemotherapies cause cell death. 54 Our studies using this model showed that NC-4 and NC-5 were better tolerated than standard cisplatin. A similar effect was observed in vitro.…”

“…Zebrafish are a well-established vertebrate system for toxicological studies and preclinical drug assessment. , The rapid cell division of early embryos is an effective experimental model to evaluate chemotherapies and other compounds in the context of nontransformed cells in vivo. − Cisplatin has been shown to effectively kill the hair cells of zebrafish lateral line, − zebrafish have been used to examine cisplatin, and other metal-based chemotherapies cause cell death …”

Synthesis and biological assessment of a ruthenium(II) cyclopentadienyl complex in breast cancer cells and on the development of zebrafish embryos

“…It is noteworthy that we have previously reported significant inhibition of hatching rate for zebrafish embryos exposed to cisplatin at concentrations far less than its IC 50 value in human cancer cells [26,27]. There are also a few studies reported for which Ru(II)Cp complexes have been investigated for their overall toxicity in a zebrafish model [78,92,93]. Although different conditions have been used for these studies making us unable to draw a certain conclusion, signs of toxicity such as delayed hatching, mortality and abnormalities such as pericardial edema, yolk sac edema, curved tail and head malfunction have been observed for some of the reported Ru(II)Cp complexes at the tested concentrations.…”

Ruthenium–Cyclopentadienyl Bipyridine–Biotin Based Compounds: Synthesis and Biological Effect

“…For the analytical data, the solutions in each vial were collected for ICPMS analysis, and the larvae were euthanized and fixed with 10% buffered formalin phosphate. 58 Three replicates containing larvae from each concentration were also collected for ICPMS analysis (see below). The concentrations of each individual compounds and corresponding control groups were set up as individual experiments, and the sample size was between 30 and 40 embryos, and repeated two times.…”

“…For the analytical data, the solutions in each vial were collected for ICPMS analysis, and the larvae were euthanized and fixed with 10% buffered formalin phosphate. 58 Three replicates containing larvae from each concentration were also collected for ICPMS analysis (see below).…”