Lenalidomide affect expression level of cereblon protein in multiple myeloma cell line RPMI8226

Baicalein Inhibits Proliferation of Myeloma U266 Cells by Downregulating IKZF1 and IKZF3

BACKGROUND Baicalein can suppress the growth of multiple tumors, including multiple myeloma (MM), but the exact mechanisms remains elusive. Here, we investigated the exact mechanisms of the anti-myeloma activity of baicalein. MATERIAL AND METHODS Proliferation and rates of apoptosis of myeloma U266 cells exposed to baicalein were detected. Microarray, polymerase chain reaction (PCR) assay, and Western blot analysis were applied to evaluate the mRNA and protein levels of associated molecules. Survival analysis of IKZF1 and IKZF3 was conducted as well. RESULTS Baicalein suppressed the growth and stimulated apoptosis of myeloma U266 cells in a dose- and time-dependent way. Baicalein increased mRNA level of CRBN, and further studies suggested that baicalein downregulated IKZF1 and IKZF3 on a post-transcriptional level. Although the differences did not reach statistical significance, IKZF1 and IKZF3 were associated with poor overall survival. CONCLUSIONS Our results suggest that baicalein suppresses the growth and promotes apoptosis of myeloma U266 cells through downregulating IKZF1 and IKZF3. Baicalein increased the expression of CRBN, which might exert a reversion effect on resistance of IMiDs. MM patients in IKZF1 and IKZF3 low-expression groups had better overall survival than those in IKZF1 and IKZF3 high-expression groups. Thus, the present results indicate that baicalein might be a therapeutic choice for targeting IKZF1 and IKZF3.

Cereblon in health and disease

Cereblon (CRBN) is a substrate receptor of the E3 ubiquitin ligase complex that has been linked to autosomal recessive non-syndromic mental retardation. Several key findings suggest diverse roles of CRBN, including its regulation of the large-conductance calcium- and voltage-activated potassium (BKCa) channels, regulation of thalidomide-binding proteins, and mediation of lenalidomide treatment in multiple myeloma. Recent studies also indicate that CRBN is involved in energy metabolism and negatively regulates AMP-activated protein kinase signaling. Mice with genetic depletion of CRBN are resistant to various stress conditions including a high-fat diet, endoplasmic reticulum stress, ischemia/reperfusion injury, and alcohol-related liver damage. In this review, we discuss the various roles of CRBN in human health and disease and suggest avenues for further research to enhance our basic knowledge and clinical application of CRBN.