TROAP regulates cell cycle and promotes tumor progression through Wnt/β‐Catenin signaling pathway in glioma cells

Aims Experimental evidence demonstrated a crucial role of TROAP (Trophinin‐associated protein) in regulating the cell proliferation of multiple tumors, while TROAP expression and function were largely unknown in glioma. We aimed to investigate the oncogenic role of TROAP and its potential mechanisms in gliomagenesis. Methods Four gene expression databases (GEO, TCGA, GTEx and CCLE) were enrolled in our study and used for TROAP expression and survival analysis. TROAP expression was quantified by qRT‐PCR, western blot and immunohistochemistry assays in glioma tissues and cell lines. TROAP knockdown and overexpression vector were constructed and transfected into glioma cells. CCK‐8, colony formation, transwell, and wound healing assays were used to evaluate cell viability, migration and invasion, flow cytometry to determine cell cycle arrest. Gene set enrichment analysis (GSEA) was conducted to screen the pathway involved in TROAP‐high phenotype. The expression of cell cycle and Wnt/β‐Catenin signaling proteins were analyzed by immunofluorescence and western blot. Results Based on the bioinformatic analysis and a series of functional assays, we found the TROAP was enriched in glioma tissues and cell lines, its overexpression was correlated with the clinicopathologic characteristics and poor prognosis. TROAP knockdown inhibited cell proliferation, migration, invasion, and G1/S cell cycle arrest compared with control group in glioma. Mechanism analysis revealed that TROAP activated Wnt/β‐Catenin pathway and upregulated its downstream targets expression, while silencing β‐Catenin or Axin2 could reverse the tumor‐promoting effects caused by TROAP, confirming that TROAP‐induced malignant phenotype and tumorigenesis via Wnt/β‐Catenin signaling pathway. Conclusion The present study found that TROAP accelerated the progression of gliomagenesis through Wnt/β‐Catenin pathway, and TROAP might be considered as a novel target for glioma therapy.
Trophinin‐associated protein (TROAP), a soluble cytoplasmic protein characterized by 778 amino acids, showed a cell cycle‐dependent manner, glioma cells with TROAP overexpression represented the accelerated entry into S phase and cell proliferation. TROAP, as a microtubule (MT)‐associated protein, upregulated the expression of Axin2 which disassemble the destruction complex and activated the Wnt signaling, then, β‐catenin accumulated in cytoplasm and subsequently was transported into the nucleus, which was binded with TCF to promote the transcription of downstream cell motility‐related genes, such as CyclinD1, C‐Myc, MMP7 and TCF4, inducing the process of gliomagenesis.