MELK/MPK38 in cancer: from mechanistic aspects to therapeutic strategies

Maternal embryonic leucine zipper kinase (MELK)/Murine protein serine-threonine kinase 38 (MPK38) is a member of the AMP-related serine-threonine kinase family, which has been reported to be involved in the regulation of many cellular events, including cell proliferation, apoptosis, and metabolism, partly by phosphorylation and regulation of several signaling molecules. The abnormal expression of MELK has been associated with tumorigenesis and malignant progression in various types of cancer. Currently, several small-molecule inhibitors of MELK are under investigation although only OTS167 has entered clinical trials. In this review, we elaborate on the relative contributions of MELK pathways in the physiological process, their oncogenic role in carcinogenesis, and targeted agents under development for the treatment of cancer.