Group II phospholipase A2 in invasive gastric cancer cell line is induced by interleukin 6

To investigate the role of group II phospholipase A2(PLA2) in cancer, we examined the expression and secretion of group II PLA2 in response to the stimulation of interleukin 6(IL-6) in human gastric cancer cells in vitro. Group II PLA2 determined by a specific radioimmunoassay was constitutively produced in culture supernatant of KATO III (signet ring cell carcinoma) and MKN28 (well differentiated adenocarcinoma). This production in KATO III significantly increased with a treatment of IL-6, whereas that in MKN28 remained at a same level. Moreover, the quantitation by reverse transcription-polymerase chain reaction(RT-PCR) demonstrated the IL-6 inducible overexpression of group II PLA2 mRNA in KATO III. This transcription was mediated by NF-IL6, the same as in hepatocytes. These results suggest two possible mechanisms of group II PLA2 production by cancer cells in vivo, that is, cytokine-induced production and constitutive production.