Abstract 5876: Exploratory testing of PM060184 compound in high-grade serous ovarian carcinoma cell lines
Authors: Heredia-Soto Victoria , Redondo Andrés , Gallego Alejandro , Miguel-Martín María , Crespo Roberto , Hernández Alicia , Hardisson David , Feliu Jaime , Galmarini Carlos , Mendiola Marta 
Published: August 2018

Purpose of the Study: Marine sponges have developed mechanisms to protect themselves from a hostile marine microenvironment. One of these mechanisms is the use of biologically active metabolites, explored nowadays for their anticancer properties. PM060184 is one of these compounds, isolated from the Madagascan sponge Lithoplocamia lithistoides. This polyketide is currently under evaluation on clinical trials, and its antitumor activity was previously reported in the preclinical setting in a panel of cell lines and subcutaneous tumor xenografts of different origin. The purpose of the study is to explore the effect of PM060184 in a panel of ovarian high-grade serous (HGS) carcinoma cell lines with different sensitivity to cisplatin and paclitaxel.

Experimental Procedures: Cell growth inhibition was analyzed by exposure of increasing concentrations of PM060184 in 96 multiwell plates for 72h, by subsequent confluence evaluation and sulphorhodamine (SRB) staining. Cell cycle experiments were done by propidium iodide (PI) staining after treatment of cell lines at their IC50 value for 72h. Three independent experiments with 6 replicates per condition were performed for both approaches. Celigo Image Cytometer platform was employed for phase contrast and viable cells discrimination with a triple staining (Hoechst, PI and calcein AM), as well as for cell cycle analyses.

Results: We have focused on the effect of this drug on a panel of HGS ovarian carcinoma cell lines, previously characterized by their response to cisplatin and paclitaxel. We have observed antiproliferative activity in a concentration-dependent manner, with IC50 values at subnanomolar concentrations in all the cell lines tested. This effect was observed in platinum-sensitive and -resistant cell lines and all of them were also more sensitive to PM060184 than paclitaxel, another tubulin-binding agent usually used for the treatment of ovarian cancer. We have evaluated cell cycle and apoptosis at the IC50 values for each cell line. We have seen that this agent disrupts the cell cycle at different phases, as DNA synthesis and mitosis, depending on the cell line. Additionally, an increase in apoptotic cell death is detected as a sub G1 peak by flow cytometry in most of the cell lines tested.

Conclusions: PM060184 is a new tubulin-binding agent with a potent antitumor activity in a panel of HGS ovarian cancer cell lines, with different ranges of sensitivity to cisplatin and paclitaxel. Additionally, this effect is more potent than that exerted by other tubulin-binding compounds, such as paclitaxel. However, the underlying mechanism of PM060184 action on ovarian HGS cell lines will need to be further elucidated.

Citation Format: Victoria Heredia-Soto, Andrés Redondo, Alejandro Gallego, María Miguel-Martín, Roberto Crespo, Alicia Hernández, David Hardisson, Jaime Feliu, Carlos Galmarini, Marta Mendiola. Exploratory testing of PM060184 compound in high-grade serous ovarian carcinoma cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5876.