Inhibition of PTTG1 suppresses proliferation and promotes differentiation of neuroblastoma cells by inducing autophagy.

PURPOSE: PTTG1 is an oncogene that is highly expressed in various cancers and is involved in regulating the cell cycle in neuroblastoma (NB) cells. However, the specific role of PTTG1 in NB has not been extensively reported. We undertook this study to investigate the expression of PTTG1 in various NB cell lines to identify the gene expression patterns. METHODS: Small interfering RNA (siRNA) targeting PTTG1 was designed and used to transfect NB cells. Cell proliferation levels, wound healing and transwell experiments were undertaken to assess the invasion and migration abilities of transfected and control NB cells. Western blot, PCR, and immunofluorescence experiments were utilized to detect the expression of migration-related proteins, differentiation-related proteins, and autophagy-related proteins in NB cells. Different doses of the autophagy inhibitor 3-methyladenine (3-MA) were used for validating the mechanism. RESULTS: High expression of PTTG1 was seen in three types of NB cell lines, with the most significant levels observed in SK-N-SH cells. Interference of PTTG1 significantly inhibited the activity of SK-N-SH cells, reducing their proliferation, invasion, and migration abilities, and was accompanied by a decrease in MMP2 and MMP9 protein expression. In addition, there was enhancement of fluorescence intensity of the differentiation marker TUBB3 and the autophagy marker LC3II, and upregulated the protein expression and mRNA levels of GAP43, TH, MEG, TUBB3, LC3II/LC3I, and beclin1, while downregulated the expression levels of P62 and mTOR. After applying the autophagy inhibitor 3-MA, the regulation of SK-N-SH cell proliferation and differentiation by PTTG1 interference was significantly reduced. CONCLUSIONS: PTTG1 is highly expressed in various NB cells. Interfering with PTTG1 induces autophagy, thereby inhibiting SK-N-SH cell proliferation and promoting differentiation.