Oct4-related cytokine effects regulate tumorigenic properties of colorectal cancer cells

Oct4, a member of the POU-domain transcription factor family, has been implicated in the cancer stem cell (CSC)-like properties of various cancers. However, the precise role of Oct4 in colorectal CSC initiation remains uncertain. Numerous studies have demonstrated a strong link between inflammation and tumorigenesis in colorectal cancers. In this study, we demonstrated that Oct4 overexpression enhances CSC-like properties of colorectal cancer cells (CRCs), including sphere formation, cell colony formation, cell migration, invasiveness, and drug resistance. In addition, putative CSC markers, stemness genes, drug-resistant genes, as well as interleukin (IL)-8 and IL-32 were upregulated. Microarray-based bioinformatics of CRCs showed higher expression levels of embryonic stem cell-specific genes in cells that overexpressed Oct4. Neutralization of either IL-8 or IL-32 with specific antibodies partially blocked the tumorigenic effects induced by either Oct4 overexpression or by the addition of conditioned media from Oct4-overexpressing CRCs. In addition, the presence of Oct4-overexpressing CRCs enhanced the tumorigenic potential of parental CRCs in vivo. In summary, these data suggest that IL-8 and IL-32 play a role in regulating the CSC-like properties that promote tumorigenesis of CRCs in both autocrine and paracrine manners.