Mebendazole (MBZ), a benzimidazole anthelmintic and cytoskeleton-disrupting compound, exhibits antitumor properties; however, its action on ovarian cancer (OC) is not clearly understood. This study evaluates the effect of MBZ on OC cell lines OVCAR3 and OAW42, focusing on cell proliferation, migration, invasion, and cancer stemness. The underlying mechanisms, including cytoskeletal disruption, epithelial–mesenchymal transition (EMT), and signaling pathways, were explored. MBZ inhibited OVCAR3 and OAW42 cell proliferation in a dose- and time-dependent manner. Additionally, MBZ significantly impedes migration, spheroid invasion, colony formation, and stemness. In addition, it reduced actin polymerization and down-regulated CSC markers (e.g., CD24, CD44, EpCAM). Moreover, MBZ suppressed MMP-9 activity and inhibited the EMT marker as judged by decreased N-Cadherin and Vimentin and increased E-Cadherin. Furthermore, MBZ induced G2/M cell cycle arrest by modulating Cyclin B1, CDC25C, and WEE1. Also, it triggered apoptosis by disrupting mitochondrial membrane potential. Mechanistic studies revealed a significant downregulation of Girdin, an Akt modulator, along with reduced p-Akt, p-IKKα/β, and p-NF-κB, indicating MBZ’s novel mechanism of action through the Girdin-mediated Akt/IKKα/β/NF-κB signaling axis. Thus, by targeting Girdin, MBZ presents a promising repurposed therapeutic strategy to inhibit cancer cell proliferation and metastasis in ovarian cancer.

The therapeutic application of CRISPR-Cas9 is limited due to its off-target activity. To have a better understanding of this off-target effect, we focused on its mismatch-prone PAM distal end. The off-target activity of SpCas9 depends directly on the nature of mismatches, which in turn results in deviation of the active site of SpCas9 due to structural instability in the RNADNA duplex strand. In order to test the hypothesis, we designed an array of mismatched target sites at the PAM distal end and performed in vitro and cell line-based experiments, which showed a strong correlation for Cas9 activity. We found that target sites having multiple mismatches in the 18th to 15th position upstream of the PAM showed no to little activity. For further mechanistic validation, Molecular Dynamics simulations were performed, which revealed that certain mismatches showed elevated root mean square deviation values that can be attributed to conformational instability within the RNA-DNA duplex. Therefore, for successful prediction of the off-target effect of SpCas9, along with complementation-derived energy, the RNA-DNA duplex stability should be taken into account.

The pharmaceutical industry has increasingly turned to natural product-based drug development as synthetic drug discovery declines. Marine ecosystems have become a key source of novel therapeutic agents, known as marine natural products (NPs), celebrated for their unique chemical structures and diverse biological activities. This chapter comprehensively explores marine NPs as a rich source of pharmacologically active compounds. We discuss the shift towards natural product-based drugs, the growing focus on marine ecosystems, and the diverse pharmacological actions of marine NPs. We also classify these natural products based on their sources. Furthermore, the chapter highlights marine NPs that are in various phases of clinical trials, those approved, and those already marketed as drugs. We emphasize the translational potential of marine NPs, showcasing their journey from promising leads to clinically relevant drugs, underscoring their importance as a reservoir of bioactive compounds.