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BMC Cancer. 2014 Nov 28;14:889. doi: 10.1186/1471-2407-14-889.

Cholesterol-conjugated let-7a mimics: antitumor efficacy on hepatocellular carcinoma in vitro and in a preclinical orthotopic xenograft model of systemic therapy.

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Department of Pathology, Peking Union Medical College (PUMC) Hospital, PUMC & Chinese Academy of Medical Sciences (CAMS), Beijing, China.



A major challenge to the clinical utility of let-7 for hepatocellular carcinoma (HCC) therapy is the lack of an effective carrier to target tumours. We confirmed the high transfection efficiency of cholesterol-conjugated let-7a miRNA mimics (Chol-let-7a) in human HCC cells, as well as their high affinity for liver tissue in nude mice. However, their antitumor efficacy via systemic delivery remains unknown.


We explored the effects of Chol-let-7a on HCC in vitro and in vivo. Cell viability and mobility, let-7a abundance and the target ras genes was measured. Live-cell image and cell ultrastructure was observed. Antitumor efficacy in vivo was analyzed by ultrasonography, hispatholgogy and transmission electronic microscopy in a preclinical model of HCC orthotopic xenografts with systemic therapy.


Chol-let-7a inhibited the viability and mobility of HCC cells. Chol-let-7a was primarily observed in the cytoplasm and induced organelle changes, including autophagy. Mild changes were observed in the cells treated with negative control miRNA. Chol-let-7a reached HCC orthotopic tumours, significantly inhibited tumour growth, and prevented local invasion and metastasis. Compared to control tumours, Chol-let-7a-treated tumours showed more necrosis. Tumour cells showed no significant atypia, and mitoses were very rare after systemic Chol-let-7a therapy. Furthermore, let-7a abundance in orthotopic xenografts was coincident with a reduction in the expression of 3 human ras mRNAs and RAS proteins.


Chol-let-7a exerted significant antitumor effects by down-regulating all human ras genes at the transcriptional and translational levels. Chol-let-7a inhibited cell proliferation, growth, and metastasis, and mainly functioned in the cytoplasm. Chol-let-7a represents a potential useful modified molecule for systemic HCC therapy.

[Indexed for MEDLINE]
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