Downregulation of Frizzled-7 induces the apoptosis of hepatocellular carcinoma cells through inhibition of NF-κB

Abstract

The aim of the present study was to investigate the functional role of Frizzled-7 (FZD7) in the apoptosis of hepatoma cells. HepG2 and Huh-7 hepatocellular carcinoma (HCC) cell lines with FZD7 expression were selected for use in the present study. The small hairpin RNA (shRNA) eukaryotic expression vector specific to FZD7 was constructed using gene recombination, and was then transfected into HepG2 and Huh-7 hepatoma cell lines using Lipofectamine 2000 to assess whether the downregulation of FZD7 could affect the proliferative ability of these cells. The results demonstrated that the downregulation of FZD7 expression significantly inhibited the proliferative ability of both cell types through the induction of cell apoptosis, as evidenced using Cell Counting kit-8 assays and flow cytometry. Furthermore, the western blotting results demonstrated that silencing of FZD7 increased the activities of caspase-3 and caspase-9. These increases were also associated with the downregulation of the inhibitor of the apoptosis protein family. Additionally, it was revealed that silencing of FZD7 expression caused the downregulation of apoptosis regulator Bcl-2 and Bcl-XL in HepG2, and Huh-7 cells, as determined through western blot analysis and reverse transcription-quantitative polymerase chain reaction. In the following work, ELISA and western blot analysis revealed that the knockdown of FZD7 inhibited the expression and activities of nuclear factor-κB (NF-κB) p65. Furthermore, it was demonstrated that the expression levels of phosphylated-Smad2/3 were markedly upregulated in sh-FZD7-transfected HepG2 and Huh-7 cells. Then, shRNA eukaryotic expression vector specific to transforming growth factor (TGF)-β receptor II was transfected into both cell lines to investigate the association between the TGF-β/Smad signaling pathway and NF-κB p65. Notably, when the TGF-β/Smad signaling pathway was inhibited, no significant differences in the cell apoptosis rate and NF-κB expression levels were identified in HCC cells. Overall, the results of the present study suggest that the shRNA-mediated knockdown of FZD7 induces apoptosis of hepatoma cell lines through the inhibition of NF-κB. In addition, the TGF-β/Smad signaling pathway appeared to partially participate in the underlying molecular mechanism of FZD7 in HCC.

Regulation of Wnt Signaling Pathways at the Plasma Membrane and Their Misregulation in Cancer

“…In search of novel potential therapeutic targets for HCC, the tumor-promoting function of Fz7 could be effectively reverted by small interfering RNAs that suppressed proliferation and metastasis of HCC cells and enhanced their apoptosis and sensitivity to chemotherapeutic drugs ( Chen et al, 2016 , 2018 ; Xue et al, 2018 ). Similarly, miR-542-3p, a common tumor-suppresser that is also downregulated in HCC tissues and cell lines, has been shown to inhibit HCC cell growth by targeting Fz7 and may thus represent a novel therapeutic target for HCC ( Wu et al, 2017 ).…”

Wnt signaling related transcripts and their relationship to energy metabolism in C2C12 myoblasts under temperature stress

“…Wnt/PCP pathway involves several proteins. FZD7 favors non-canonical signaling, and its downregulation restrains cell proliferation (Xue et al, 2018). DAAM1 is required for organizing the cytoskeleton (Habas & He, 2001).…”

ZnO nanomaterials target mitochondrial apoptosis and mitochondrial autophagy pathways in cancer cells

“…In a normal adult, approximately 10 billion cells undergo apoptosis as part of maintaining cell balance in the body. Therefore, regular homeostasis is not solely a passive process, but rather highly regulated by PCD 20 . Apoptosis plays a crucial role in fighting infection by clearing the pathogenic niche inside cells, as well as managing cancer prevention by eliminating nascent tumor cells in developing organisms 12 .…”

“…Additionally, the outer membrane of cancer cells often contains high concentrations of anionic phospholipids and a large membrane potential. The interaction between cancer cells and positively charged ZnO NPs is expected to be driven by electrostatic interactions, promoting cellular uptake, phagocytosis, and ultimately cytotoxicity 20,21,41,42 …”