TELO2 induced progression of colorectal cancer by binding with RICTOR through mTORC2

Colorectal cancer (CRC) is a common cancer worldwide, and its treatment strategies are limited. The underlying mechanism of CRC progression remains to be determined. Telomere maintenance 2 (TELO2) is a mTOR-interacting protein. Both the role and molecular mechanism of TELO2 in cancer progression remain unknown. In this study, the gene expression database of normal and tumor tissue, in addition to western blot analysis, and immunohistochemistry (IHC) were used to determine the expression and location of TELO2 in CRC and normal tissues. Clinical features of a tissue array were collected and analyzed. WST-1, soft agar, flow cytometry, wound healing, and invasion assays were employed to verify the role of TELO2 in the growth, cell cycle, migration, and invasion of CRC cells. The correlation between TELO2 and RICTOR (rapamycin-insensitive companion of mTOR) was analyzed by bioinformatics, IHC, and immunoprecipitation. Normal and serum-deprived cells were collected to detect the protein level of TELO2 and its downstream effectors. The results revealed that TELO2 was significantly upregulated in CRC, and TELO2 inhibition significantly restrained the growth, cell cycle, and metastasis of CRC cells. TELO2 overexpression correlated with age, lymph node metastasis, and TNM stage of CRC patients. In addition, TELO2 was positively correlated with RICTOR in CRC and induced tumor progression mainly via RICTOR with serum in culture. RICTOR induced the degradation of TELO2 upon serum deprivation in an mTOR-independent manner. These findings indicate that TELO2 promotes tumor progression via RICTOR in a serum-dependent manner, which may be a potential therapeutic target for CRC.