DHX15 overexpression suppresses colorectal cancer cell line proliferation.

DEAH (Asp-Glu-Ala-His) box helicase 15 (DHX15) is a member of the DEAD box RNA helicase family that carries out a key role in innate immunity against viral infections. It is involved in tumorigenesis as a tumor-promoting factor in various types of cancer, but it has also been suggested to act as a tumor suppressor. However, the role of DHX15 in colorectal cancer (CRC) remains largely unknown. In the present study, we examined the role of DHX15 in CRC. Immunostaining of clinical samples from patients with CRC identified DHX15 proteins in the cell nuclei of both tumor and adjacent normal tissues. DHX15 overexpression was revealed to reduce the cell number of various CRC cell lines, as well as the number of Ki67-positive proliferating cells. However, the number of AC3-positive apoptotic cells was comparable between the control and DHX15-overexpressing cells. The possible downstream mechanisms of DHX15 were further examined which revealed that activation of the Wnt/β-catenin and NF-κB signaling pathways were not affected by DHX15 expression. However, DHX15 overexpression resulted in fewer LC3 puncta in HCT116 and DLD1 cells. Taken together, DHX15 may negatively affect CRC cell proliferation, and autophagy may potentially be involved in the downstream mechanism of DHX15.