Knockdown of HOXC6 inhibits glioma cell proliferation and induces cell cycle arrest by targeting WIF-1 in vitro and vivo.

BACKGROUND

Homeobox C6 (HOXC6) is one of several HOXC genes and is frequently overexpressed in multiple cancers. However, the function and mechanism of HOXC6 in glioma remain unclear.

METHODS

The expression level of HOXC6 and its relationship with prognosis in glioma were determined through the TCGA database. The expressions of HOXC6 mRNA in glioblastoma tissues and normal brain tissues were detected by qRT-PCR and Western blot. To explore the role of HOXC6 in glioma, a lentiviral vector that expressed HOXC6-shRNA was constructed and transfected into glioma U87 cells. The expression levels of HOXC6 and WNT inhibitory factor 1 (WIF-1) in the glioma U87 cells after transfection with HOXC6-shRNA were measured by real-time PCR and Western blot． CCK-8, colony formation and EdU assays were used to measure the effects of HOXC6 on U87 cell proliferation, and flow cytometry was used to monitor the changes in the cell cycle and cell apoptosis after transfection with HOXC6-shRNA. Xenograft tumors were examined in vivo for the carcinogenic effects and prognostic value of HOXC6 in glioma tissues.

RESULTS

In this study, HOXC6 was highly expressed in human glioma tissues, and a high expression of HOXC6 was associated with poor prognosis in GBM patients. We demonstrated that HOXC6 was highly expressed in human GBM tissues and three glioma cell lines. The knockdown of HOXC6 expression significantly inhibited the proliferation and colony formation ability of U87 cells by blocking cell cycle progression in the G0/G1 phase and induced apoptosis. In addition, we found that the mRNA and protein levels of WIF-1 were substantially increased after transfection with HOXC6-shRNA compared with Ctrl-shRNA in vitro. Consistent with the results of the in vitro assays, the xenograft assay and immunohistochemistry also demonstrated that in response to HOXC6 inhibition, the tumor growth and Ki-67 expression level were inhibited and the WIF-1 expression was increased in vivo.

CONCLUSIONS

In conclusion, the results of the current study indicate that HOXC6 promotes glioma U87 cell growth through the WIF-1/Wnt signaling pathway and HOXC6 might be a novel target in clinical treatment for gliomas.