NCAPG is transcriptionally regulated by CBX3 and activates the Wnt/β-catenin signaling pathway to promote proliferation and the cell cycle and inhibit apoptosis in colorectal cancer

Colorectal cancer (CRC) is highly heterogeneous at the genetic and molecular level and a major contributor to cancer-death worldwide. Non-structural maintenance of chromosomes (SMC) condensin I complex subunit G (NCAPG) is a subunit of condensin I and has been shown to be associated with the prognosis of cancers. This study investigated the functional role of NCAPG in CRC and its mechanism.

Collectively, the results of our study indicated that NCAPG was transcriptionally regulated by CBX3 and activated the Wnt/β-catenin signaling pathway to facilitate the progression of CRC.

Messenger RNA (mRNA) and protein expressions of NCAPG and chromobox protein homolog 3 (CBX3) were determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot. The proliferation, cycle, and apoptosis of HCT116 cells were analyzed by Cell Counting Kit-8 (CCK-8), flow cytometry, and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. RT-qPCR and western blot were used to determine the transfection efficacy of short hairpin (sh)-NCAPG and sh-CBX3. Western blot was used to explore cycle-, apoptosis-, and Wnt/β-catenin signaling-related proteins, and the activity of NCAPG promoter was evaluated using a luciferase report assay. The expressions of cleaved caspase9 and cleaved caspase3 were assessed by colorimetric caspase activity assay.

The results showed that NCAPG expression was elevated in CRC cells. After transfection with sh-NCAPG, NCAPG expression was reduced. It was also discovered that NCAPG knockdown suppressed proliferation and the cell cycle but induced apoptosis in HCT116 cells. The Human Transcription Factor Database (HumanTFDB; http://bioinfo.life.hust.edu.cn/HumanTFDB#!/) predicted the binding sites of CBX3 and NCAPG promoters. Meanwhile, the Encyclopedia of RNA Interactomes (ENCORI) database (https://starbase.sysu.edu.cn/) revealed that CBX3 was positively correlated with NCAPG. Our results showed that NCAPG was transcriptionally regulated by CBX3. Additionally, Wnt/β-catenin signaling was discovered to be activated by CBX3 overexpression. Further experiments showed that NCAPG transcriptionally regulated by CBX3 activated Wnt/β-catenin signaling to regulate the proliferation, cell cycle, and apoptosis of HCT116 cells. Conclusions: Collectively, the results of our study indicated that NCAPG was transcriptionally regulated by CBX3 and activated the Wnt/β-catenin signaling pathway to facilitate the progression of CRC.