Targeting RSK2 in Cancer Therapy: A Review of Natural Products.

P90 ribosomal S6 kinase 2 (RSK2) is an important member of the RSK family, functioning as a kinase enzyme that targets serine and threonine residues and contributes to regulating cell growth. RSK2 comprises two major functional domains: the N-terminal kinase domain (NTKD) and the C-terminal kinase domain (CTKD). RSK2 is situated at the lower end of the Mitogen-activated protein kinases (MAPK) signaling pathway and is phosphorylated by the direct regulation of Extracellular signal-regulating kinase (ERK). RSK2 has been found to play a pivotal role in regulating cell proliferation, apoptosis, metastasis, and invasion in various cancer cells, including breast cancer and melanoma. Consequently, RSK2 has emerged as a potential target for the development of anti-cancer drugs. Presently, several inhibitors are undergoing clinical trials, such as SL0101. Current inhibitors of RSK2 mainly bind to its NTK or CTK domains and inhibit their activity. Natural products serve as an important resource for drug development and screening and with the potential to identify RSK2 inhibitors. This article discusses how RSK2 influences tumor cell proliferation, prevents apoptosis, arrests the cell cycle process, and promotes cancer metastasis through its regulation of downstream pathways or interaction with other biological molecules. Additionally, the paper also covers recent research progress on RSK2 inhibitors and the mechanisms of action of natural RSK2 inhibitors on tumors. This review emphasizes the significance of RSK2 as a potential therapeutic target in cancer and offers a theoretical basis for the clinical application of RSK2 inhibitors.