CUL4B promote proliferation and migration of non-small-ce ll lung cells through epigenetically repression of miR-194

【摘要】：Objective CUL4 B, a scaffold protein that assembles CRL4 B ubiquitin ligase complexes, is overex pressed in many types of cancers and represses many tumor suppressors through epigenetic me chanisms. However, the roles of CUL4 B in lung cancer, particularly the non-small cell lung cancer s(NSCLC) are unknown. Method Cell proliferation was measured by MTT, Ed U incorporation and colony formation assa y. Wound-healing and transwell migration assays were employed to measure cell migration and i nvasion. Realtime PCR and western blot were used to detected m RNA and protein expression le vels. mi RNA pulldown and 3' UTR luciferase assays were used to verify the effect of mi R-194 on CUL4 B expression. Result Here, we show that CUL4 B was upregulated in NSCLC tissues and was critically required for cell proliferation and migration. Furthermore, we found that CRL4 B represses mi R-194 by cata lyzing monoubiquitination at H2 AK119 and by coordinating with PRC2 to promote trimethylation a t H3 K27 at the clusters encoding mi R-194. Inhibition of mi R-194 was further shown to be able to r escue the defects in proliferation and migration of lung cancer cells resulted from CUL4 B knockdo wn. Moreover, knockdown of CUL4 B decreased the expression of the mi R-194 downstream targe ts RBX1, a subunit of CRL4 B and overexpressed in a number of human tumors. Conclusion Together with the previous results we obtained that CUL4 B is a target of mi R-194, th ese data thus establish a double negative feedback loop between mi R-194 and CRL4 B whose dy sregulation contributes to tumorigenesis. Given the important roles of mi R-194 cluster genes in tu mor progression, these results provided new evidence to support the oncogenic roles of CUL4 B, and trongly support further development of anti-CUL4 B inhibitor against NSCLC.