Colorectal cancer (CRC) is one of the most lethal cancers worldwide, however it has limited chemotherapeutic agents available. Besides, CRC harboring KRAS and BRAF mutations are associated with resistance to EGFR inhibitors what constitutes a relevant clinical problem. Ruthenium (Ru) drugs had arisen as one of the most promising metallodrugs with features that increase their specificity and selectivity toward cancer cells. With this in mind, a new family of Ru-cyclopentadienyl conjugates was designed using macromolecules and/or biomolecules to increase selectivity and efficiency. In this work, we used two CRC-derived cell lines with KRAS and BRAF mutations and a normal colon cell line to study antiproliferative activity, cell death mechanism, cellular migration, intracellular distribution, MAPK-ERK and PI3K-AKT signaling pathways and actin cytoskeleton effects of the compounds. Our results revealed that Ru agents are more cytotoxic for cancer cells, inhibit in a high extent the clonogenic ability, induce apoptosis and decrease motility at high concentrations and preferentially localize in membrane and cytoskeleton of CRC cells. Ru agents also affected F-actin polymerization suggesting that actin might be a possible target for these compounds. Overall our results showed that Ru compounds present promising anticancer activity in CRC cells what could bring new avenues in CRC therapy.

Acknowledgements The authors thank the Portuguese Foundation for Science and Technology (Fundação para a Ciência e Tecnologia, FCT) within the scope of projects UIDB/00100/2020 (Centro de Química Estrutural) and PTDC/QUI-QIN/28662/2017. Ana Rita Brás thanks FCT for her Ph.D. Grant (SFRH/BD/139271/2018). A. Valente acknowledges the CEECIND 2017 Initiative (CEECCIND/01974/2017).