nutrients Review Beneficial Actions of Orostachys japonica and Its Compounds against Tumors via MAPK Signaling Pathways Soyoung Hur 1,† , Eungyeong Jang 2,3,† and Jang-Hoon Lee 2,* 1 Department of Clinical Korean Medicine, Graduate School, Kyung Hee University, Seoul 02447, Korea;
[email protected] 2 Department of Internal Medicine, College of Korean Medicine, Kyung Hee University, Seoul 02447, Korea;
[email protected] 3 Department of Internal Medicine, Kyung Hee University Korean Medicine Hospital, Seoul 02447, Korea * Correspondence:
[email protected]; Tel.: +82-2-958-9118; Fax: +82-2-958-9258 † These authors contributed equally to this work. Abstract: Tumors are one of the most life-threatening diseases, and a variety of cancer treatment options have been continuously introduced in order to overcome cancer and improve conventional therapy. Orostachys japonica (O. japonica), which is a perennial plant belonging to the genus Orostachys of the Crassulaceae family, has been revealed to exhibit pharmacological properties against vari- ous tumors in numerous studies. The present review aimed to discuss the biological actions and underlying molecular mechanisms of O. japonica and its representative compounds—kaempferol and quercetin—against tumors. O. japonica reportedly has antiproliferative, anti-angiogenic, and antimetastatic activities against various types of malignant tumors through the induction of apoptosis and cell cycle arrest, a blockade of downstream vascular endothelial growth factor (VEGF)-VEGFR2 pathways, and the regulation of epithelial-to-mesenchymal transition. In addition, emerging studies have highlighted the antitumor efficacy of kaempferol and quercetin. Interestingly, it was found that alterations of the mitogen-activated protein kinase (MAPK) signaling cascades are involved in the Citation: Hur, S.; Jang, E.; Lee, J.-H.