Human DHX9 Stable Cell Line - HCT 116

Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide; consequently, there is an urgent need to identify novel therapeutic targets for its treatment. Here, DHX9 was identified as a key factor promoting the proliferation of CRC cells. Furthermore, DHX9 was found to be highly expressed in CRC cell lines, clinical CRC tissue samples, and a mouse model of colitis-associated colorectal cancer (CAC). Elevated levels of DHX9 expression were positively correlated with poor prognosis in CRC patients. Through gain-of-function and loss-of-function experiments, researchers demonstrated that DHX9 promotes CRC cell proliferation, colony formation, resistance to apoptosis, migration, and invasion in vitro. Moreover, validation studies utilizing xenograft and liver metastasis mouse models confirmed that forced overexpression of DHX9 promotes CRC growth and metastasis in vivo, whereas the knockdown of DHX9 exerts the opposite inhibitory effect. These findings suggest that DHX9 holds promise as a potential therapeutic target for the prevention and treatment of CRC.

Annexin V-FITC/PI double staining results revealed that, compared to control cells, DHX9-overexpressing HCT116 cells exhibited a lower apoptotic index, whereas cells with silenced DHX9 expression demonstrated a higher apoptotic rate. Consistent with this, similar results were also observed in HCT8 and COLO205 cells (Figure 1A). Furthermore, the researchers investigated the impact of modulating DHX9 expression on the enzymatic activities of Caspase-3, Caspase-8, and Caspase-9 in HCT116 cells. The results indicated that DHX9 overexpression significantly reduced the enzymatic activities of Caspase-3 and Caspase-9; conversely, DHX9 knockdown significantly enhanced the enzymatic activities of Caspase-3 and Caspase-9. However, no significant changes in Caspase-8 enzymatic activity were observed in DHX9-overexpressed and -silenced HCT116 cells (Figure 1B). To further evaluate the role of DHX9 in sustaining the growth of colorectal cancer (CRC), the researchers established a tumor xenograft model in nude mice inoculated with HCT116 cells. The results demonstrated that, compared to HCT116 cells transfected with an empty vector, the inoculation of DHX9-overexpressing HCT116 cells led to a significant increase in tumor volume (Figure 1C), size (Figure 1D), and weight (Figure 1E); conversely, DHX9 knockdown significantly inhibited tumor growth (Figure 1C-E). Immunohistochemical (IHC) analysis of tumor sections from these three groups further confirmed that DHX9 overexpression significantly promoted cell proliferation and inhibited apoptosis, whereas DHX9 knockdown effectively suppressed CRC growth and induced apoptosis (Figure 1F-G).

Figure 1. DHX9 depletion induces apoptosis and inhibits outgrowth of xenografted colorectal cancer cells in nude mice. (Liu S, et al., 2021)