Cytokines are known to function as regulatory molecules that can be produced by virtually every nucleated cell type in the body, including lymphocytes, monocytes/macrophages, epithelial cells, fibroblasts, and many others. Cytokines include lymphocyte-derived factors (lymphokines), monocyte-derived factors (monokines), hematopoietic factors (colony-stimulating factors), connective tissue/ growth factors, and chemotactic chemokines. Cytokines released in response to infection can affect tumor development in different ways. When exposed to infectious agents, cytokines are secreted by sentinel cells, such as macrophages and dendritic cells. These cytokines include interleukin 1 (IL-1) and tumor necrosis factor-α, as well as others, such as IL-6, IL-12, and IL-18. When released in sufficient quantities, these molecules can cause inflammation. Chronic inflammation is highly associated with tumor initiation, promotion, and progression. In this article, we review the roles and mechanisms of cytokines in tumor development.

• Jin Tae Hong(College of Pharmacy and Medical Research Center, Chungbuk National University) Corresponding author
• Ju Kyung Song(College of Pharmacy and Medical Research Center, Chungbuk National University)
• Sun Mi Kwon(College of Pharmacy and Medical Research Center, Chungbuk National University)
• Byung Woo Ahn(College of Veterinary Medicine, Chungbuk National University)
• Youngsoo Kim(College of Pharmacy and Medical Research Center, Chungbuk National University)
• Sang Bae Han(College of Pharmacy and Medical Research Center, Chungbuk National University)
• Dea Joong Kim(College of Veterinary Medicine, Chungbuk National University)