Ultrasound-targeted microbubble destruction-mediated downregulation of CD133 inhibits epithelial-mesenchymal transition, stemness and migratory ability of liver cancer stem cells

Hepatocellular carcinoma (HCC) is an aggressive disease with a poor outcome due to the high incidence of metastasis. Cancer stem cells (CSCs) have been identified to be responsible for tumor progression and may be generated by epithelial-mesenchymal transition (EMT) characteristics. CD133 is a specific surface marker for liver cancer stem cells (LCSCs), which is also considered as an important functional factor for tumorigenesis and overall survival in HCC. Ultrasound-targeted microbubble destruction (UTMD) has recently been used as a novel, safe and effective gene transfection technology. The aim of the present study was to elucidate the regulatory mechanism of CD133 and EMT in LCSCs and whether the UTMD-based shRNA delivery system facilitated gene delivery in LCSCs. In the present study, CD133+ cells were isolated from the SMMC-7721 HCC cell line and then transfected with shCD133 mediated by UTMD and liposomes, respectively. Compared to the liposomes group, the UTMD group resulted in significantly improved transfection efficiency. The downregulation of CD133 reversed the EMT program, attenuated self-renewal, proliferation and migration of CD133+ LCSCs and suppressed the growth of CSC tumor xenografts. Additionally, the downregulation of CD133 led to downregulation of the nuclear factor-κB (NF-κB) pathway. The present study demonstrated that CD133 plays a critical role in the regulation of the EMT process, tumor-initiating properties and migratory ability of LCSCs. The UTMD technique targeted for CD133 downregulation may be examined as a potential therapeutic strategy for HCC.