• mesotelioma pleurico maligno
• zebrafish
• drug repositioning
• mpm

Malignant pleural mesothelioma (MPM) is a rare and aggressive tumor arising mainly from the pleura (65%-70%) and peritoneum (30%). It is an occupational disease commonly caused by asbestos exposure, with several years of latency between the contact and the development of the condition. Currently, the treatment options are surgery in combination of chemotherapy with pemetrexed and cisplatin, or immunotherapy or target therapy. However, an effective cure is still lacking, and, to date, the 5-year overall survival is less than 5-8%.
In this scenario, the challenge is to develop novel, safe, and more effective therapies, but given the extremely high costs for drug discovery and development, the drug repurposing approach in oncology is increasingly becoming attractive to identify anticancer properties of drugs already approved by the FDA.
My thesis project is a part of a drug repurposing study in malignant pleural mesothelioma. Specifically, the aim of my work is to test in vivo three approved drugs (Mebendazole, Idarubicin, and Podophyllotoxin) that have already shown promising results in vitro against pleural mesothelioma cell lines by studies performed in Prof Landi Lab.
Mebendazole is active against intestinal helminthiasis and has shown cytotoxic activity. Idarubicin is an anthracycline already used for some malignant diseases, such as breast cancer and non- Hodgkin lymphoma. Podophyllotoxin is known to inhibit tubulin polymerization and has an antimitotic effect.
To do the in vivo studies, I took advantage of the zebrafish model (Danio rerio) since has several advantages compared to the mouse model: it has an extra-uterine development, is small, and requires a lower cost for husbandry. Zebrafish embryos are transparent, and, most importantly, they are not sentient up to five days post fertilization implying a low ethical impact.
In recent decades, zebrafish has emerged as a good model organism to screen and validate drug candidates through safety and efficacy studies. The zebrafish model is also used for xenograft experiments with human cancer cell lines to evaluate the potential drug effects with a non-invasive method.
First, it was generated a MPM zebrafish xenograft model, xenografting REN cell line into the perivitelline space of 2 days post fertilization (2 dpf) zebrafish embryos. REN cells express the luciferase gene which was used to quantify the cell viability.
Cell proliferation was evaluated by an immuno-staining whole mount using a mitosis marker. Subsequently, to determine the number of cells to be injected into the model, a characterization assay was performed by injecting an increasing number of cells and detecting the signal after one day, to allow their engraftment.
Using, as a reference, the maximum patient’s plasma concentration of each drug of interest, a toxicity study was performed on 2 dpf embryos exposed for three days to increasing concentration of each compound in order to determine the IC50 and LD25.
Then, the MPM zebrafish xenograft model was used to perform a drug efficacy study using a high- throughput luminescence assay. The model was also used to investigate the efficacy of the drugs to inhibit cell migration.
The results obtained in my project thesis confirm the efficacy of the selected drugs and open the way to test them on mouse models.