Let-7 inhibits self-renewal of hepatocellular cancer stem-like cells through regulating the epithelial-mesenchymal transition and the Wnt signaling pathway.
Tumor suppressive let-7 miRNAs are universally down-regulated in human hepatocellular carcinoma (HCC) versus normal tissues; however, the roles and related molecular mechanisms of let-7 in HCC stem cells are poorly understood.



We examined the inhibitory effect of let-7 miRNAs on the proliferation of MHCC97-H and HCCLM3 hepatic cancer cells by using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, which was further confirmed by apoptosis and cell cycle studies. The sphere-forming assay was used to study the effects of let-7a on stem like cells. Through western blot, immunofluorescence and the luciferase-reporter assay, we explored the activity of epithelial-mesenchymal transition (EMT) signaling factors in HCC cells. qRT-PCR was applied to detect miRNA expression levels in clinical tissues.



Let-7a effectively repressed cell proliferation and viability, and in stem-like cells, also let-7a decreased the efficiency of sphere formation.in stem-like cells. The suppression of EMT signaling factors in HCC cells contributed to let-7's induced tumor viability repression and Wnt activation repression. Besides, Wnt1 is critical and essential for let-7a functions, and the rescue with recombinant Wnt1 agent abolished the suppressive roles of let-7a on hepatospheres. In clinical HCC and normal tissues, let-7a expression was inversely correlated with Wnt1 expression.



Let-7 miRNAs, especially let-7a, will be a promising therapeutic strategy in the treatment of HCC through eliminating HCC stem cells, which could be achieved by their inhibitory effect on the Wnt signaling pathway.
Department of General Surgery, Qilu Hospital of Shandong University, 107 Wenhua West Road, Lixia District, Jinan, Shandong Province, 250012, China. prof_binjin@163.com.
Bin
B
Jin
Department of Biochemistry and Molecular Biology, School of Medicine, Shandong University, Jinan, Shandong Province, 250012, China.
Wei
W
Wang
Department of General Surgery, The People's Hospital of LingCheng, Dezhou, 253500, China.
Xiang-Xin
XX
Meng
Department of General Surgery, Qilu Hospital of Shandong University, 107 Wenhua West Road, Lixia District, Jinan, Shandong Province, 250012, China.
Gang
G
Du
Department of General Surgery, Qilu Hospital of Shandong University, 107 Wenhua West Road, Lixia District, Jinan, Shandong Province, 250012, China.
Jia
J
Li
Department of General Surgery, Qilu Hospital of Shandong University, 107 Wenhua West Road, Lixia District, Jinan, Shandong Province, 250012, China.
Shi-Zhe
SZ
Zhang
Department of General Surgery, Qilu Hospital of Shandong University, 107 Wenhua West Road, Lixia District, Jinan, Shandong Province, 250012, China.
Bing-Hai
BH
Zhou
Department of General Surgery, Qilu Hospital of Shandong University, 107 Wenhua West Road, Lixia District, Jinan, Shandong Province, 250012, China.
Zhi-Hao
ZH
Fu
D017209:Apoptosis / Q000235:genetics; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D002453:Cell Cycle / Q000235:genetics; D045744:Cell Line, Tumor; D000066673:Cell Self Renewal / Q000235:genetics; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D018450:Disease Progression; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D035683:MicroRNAs / Q000235:genetics*; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000378:metabolism*; D010984:Platinum / Q000494:pharmacology; D034622:RNA Interference; D060449:Wnt Signaling Pathway; D051155:Wnt1 Protein / Q000235:genetics
D035683:MicroRNAs; C495247:WNT1 protein, human; D051155:Wnt1 Protein; C487931:mirnlet7 microRNA, human; D010984:Platinum
Cancer stem-like cells; EMT; Hepatocellular carcinoma; Let-7 miRNAs; Wnt signaling