Confirmation of HIF-1α Independent Pathway in the Progression of HepG2 Cells by Hypoxic Condition

BACKGROUND/AIMS: When hepatocellular carcinoma (HCC) is exposed to hypoxic condition, HIF-1α is activated and results in angiogenesis and increased tumor burden. Although inhibition of HIF-1α may reduce tumor growth, there are some limitations to control tumor growth completely. For a more effective therapy for HCC, we investigated HIF-1α independent pathway related tumor growth with angiogenesis. METHODS: We cultured HepG2 cells (HCC cell line) in both normoxia and hypoxia conditions. These cells were divided into three groups: a echinomycin treated group, a echinomycin and quinazoline treated group and a control group without any treatments. Growth morphologies of cells were observed with a microscope after 24 hours. Immunocytochemistry assay was done to detect the angiogenesis during inhibition of HIF-1α and/or NF-κB in hypoxia condition, and compared with results in normoxia condition. RESULTS: In normoxia, the expression of HIF-1α on tumor growth was not found. In hypoxia, inhibition of HIF-1α reduced the tumor growth compared to the control group. But, inhibition of both HIF-1α and NF-κB did not show apparent reduction of tumor growth as shown in HIF-1α only group. CONCLUSIONS: Signaling pathways related to cancer cell growth exist through a vast network. Inhibition of one target molecule may result in over-expression of other molecules related to the tumor growth. For an effective therapy in blocking of the tumor growth, more comprehensive understanding of the network related to signaling pathways on tumor growth is necessary.

Multi-facets of Corticotropin-releasing Factor in Modulating Inflammation and Angiogenesis

The family of corticotropin-releasing factor (CRF) composed of 4 ligands including CRF, urocortin (Ucn) 1, Ucn2, and Ucn3 is expressed both in the central nervous system and the periphery including the gastrointestinal tract. Two different forms of G protein coupled receptors, CRF1 and CRF2, differentially recognize CRF family members, mediating various biological functions. A large body of evidence suggests that the CRF family plays an important role in regulating inflammation and angiogenesis. Of particular interest is a contrasting role of the CRF family during inflammatory processes. The CRF family can exert both pro- and anti-inflammatory functions depending on the type of receptors, the tissues, and the disease phases. In addition, there has been a growing interest in a possible role of the CRF family in angiogenesis. Regulation of angiogenesis by the CRF family has been shown to modulate endogenous blood vessel formation, inflammatory neovascularization and cardiovascular function. This review outlines the effect of the CRF family and its receptors on 2 major biological events: inflammation and angiogenesis, and provides a possibility of their application for the treatment of inflammatory vascular diseases.