Cytotoxic evaluation of YSL-109 in a triple negative breast cancer cell line and toxicological evaluations

Discovery of potential RSK1 inhibitors for cancer therapy using virtual screening, molecular docking, molecular dynamics simulation, and MM/GBSA calculations

The p90 ribosomal protein S6 Kinase (RSK) family belongs to Ser/Thr protein kinases that includes four isoform RSK1-4 in mammals. The ribosomal protein S6 Kinase 1 (RSK1) is also known as ribosomal protein S6 kinase alpha-1 (RPS6KA1) is a special protein due to their two catalytic regions that is associated with abundantly various cancers and it is proposed as a drug target. Several RSK1 isoform inhibitors have been reported but none of them are used in clinical studies. Thus, we aimed to perform ligand pharmacophore mapping with the known inhibitor and structure-based virtual screening studies to determine potential candidates against RSK1-terminal kinase domains CTKD and NTKD. The studied compounds from the databases (ApexBio, ChEMBL, ChemDiv). The molecular docking study was performed with the resulted candidates by using CDOCKER and Glide/SP methods. The four candidates with the highest docking scores were used for further 100-ns molecular dynamics (MD) simulations and Molecular Mechanics Generalised Born and Surface Area (MM/GBSA) calculations. The root mean square deviation (RMSD) for protein complexes were found between 2 Å and 4 Å. Solvent accessible surface area (SASA), radius of gyration (Rg), and polar surface area (PSA) values were calculated for compounds. The binding free energies were calculated between -72.22 kcal/mol and -82.44 kcal/mol. The interaction diagrams showed that hydrogen bond, alkyl, and π-alkyl interactions were observed with specific residues such as Leu144, Lys94, Asp142 for RSK1-NTKD, and Cys532, Cys556, Lys447, Asn540 for RSK1-CTKD. The identified compounds may be potential inhibitor candidates of RSK1 following the preclinical studies.Communicated by Ramaswamy H. Sarma.

Small molecule agents for triple negative breast cancer: Current status and future prospects

Triple-negative breast cancer (TNBC) is a subtype of breast cancer with poor prognosis. The number of cases increased by 2.26 million in 2020, making it the most commonly diagnosed cancer type in the world. TNBCs lack hormone receptor (HR) and human epidermal growth factor 2 (HER2), which limits treatment options. Currently, paclitaxel-based drugs combined with other chemotherapeutics remain the main treatment for TNBC. There is currently no consensus on the best therapeutic regimen for TNBC. However, there have been successful clinical trials exploring large-molecule monoclonal antibodies, small-molecule targeted drugs, and novel antibody-drug conjugate (ADC). Although monoclonal antibodies have produced clinical success, their large molecular weight can limit therapeutic benefits. It is worth noting that in the past 30 years, the FDA has approved small molecule drugs for HER2-positive breast cancers. The lack of effective targets and the occurrence of drug resistance pose significant challenges in the treatment of TNBC. To improve the prognosis of TNBC, it is crucial to search for effective targets and to overcome drug resistance. This review examines the clinical efficacy, adverse effects, resistance mechanisms, and potential solutions of targeted small molecule drugs in both monotherapies and combination therapies. New therapeutic targets, including nuclear export protein 1 (XPO1) and hedgehog (Hh), are emerging as potential options for researchers and become integrated into clinical trials for TNBC. Additionally, there is growing interest in the potential of targeted protein degradation chimeras (PROTACs), degraders of rogue proteins, as a future therapy direction. This review provides potentially valuable insights with clinical implications.