Hypoxia-induced EMAP-II transcription in colorectal cancer

Endothelial monocyte-activating polypeptide-II (p431EMAP-II) is a proinflammatory cytokine and a chemoattractant for mononuclear phagocytes and polymorphonuclear leucocytes, found in culture supernatants of many tumour cell lines. It was demonstrated that p43/EMAP-II induces apoptosis in mitogen-stimulated lymphocytes, and suggested that it may be a constituent of a novel immune evasion mechanism employed by tumour cells. Quantitative real-time reverse transcription- polymerase chain reaction (qRT-PCR) analysis for EMAP-II mRNA was performed for colorectal adenocarcinoma cell lines, DLD-1, HT 29; human umbilical vein endothelial cells (HUVEC); and normal colon under normal and hypoxic conditions. Under hypoxic conditions, EMAP-II transcript expression increased up to 22-fold over normoxia in tumour cells, while there was 1-fold increase due to hypoxia in HUVEC and no increase in normal colon. These results demonstrate that EMAP-II transcripts are upregulated in tumour cells in hypoxic conditions and support the notion that EMAP-II plays a complex and important role in human cancer.