MiR-20a and miR-20b negatively regulate autophagy by targeting RB1CC1/FIP200 in breast cancer cells

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• 作者：Shufeng Li^a ; ¹ ; ^{shufengli@seu.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Qian Qiang^a ; ¹ ; Haitao Shan^a ; ¹ ; Minke Shi^b ; ¹ ; Guangming Gan^a ; Fang Ma^a ; Baojun Chen^b ; ^{cbaoj_608@126.com" class="auth_mail" title="E-mail the corresponding author}
• 关键词：RB1CC1/FIP200 ; miR-20a ; miR-20b ; Autophagy ; Breast cancer
• 刊名：Life Sciences
• 出版年：2016
• 出版时间：15 February 2016
• 年：2016
• 卷：147
• 期：Complete
• 页码：143-152
• 全文大小：2123 K

文摘

RB1CC1/FIP200 was essential for autophagosome formation. Therefore, RB1CC1/FIP200 cellular levels are critical for the activation of the autophagy pathways. Following the screen of miRNAs affecting RB1CC1/FIP200 level and rapamycin-induced autophagy, we discovered miR-20a and miR-20b could regulate autophagy by targeting RB1CC1/FIP200.

Main methods

Inhibitory effect of miR-20a and 20b on basal and rapamycin-stimulated autophagy was demonstrated using various autophagic tests including GFP-LC3 puncta analysis, LC3II/LC3I gel shift and TEM observation.

Key findings

We discovered RB1CC1/FIP200 as cellular targets of miR-20a and miR-20b. Upon miR-20a and miR-20b overexpression, both mRNA and protein levels of RB1CC1/FIP200 decreased. miR-20a and miR-20b target sequences present in the 3′ UTR of RB1CC1/FIP200 mRNAs and introduction of mutations abolished the miR-20a and miR-20b responsiveness. In MCF7 and MDA-MB-231 breast cancer cells, miR-20a and miR-20b over-expression attenuated basal and rapamycin-induced autophagy; while suppression of miR-20a or miR-20b by specific antagomir showed normal rapamycin-induced autophagic activity.

Significance

To our knowledge, this is the first study showing the significance of miR-20a and miR-20b regulating autophagy by targeting RB1CC1/FIP200.