BACKGROUNDTo explore the effects of nm23-H1 gene transfection and forskolin on PKA activity in human high-metastasis large cell lung cancer cell line L9981.

METHODSThree cell lines, primary human large cell lung cancer cell line (L9981), vector transfection cell line (L9981-pLXSN) and nm23-H1 gene transfection cell line (L9981-nm23-H1-pLXSN), were treated with PKA activator forskolin. The PKA activity at different time points after treatment with forskolin was detected in the three lung cancer cell lines by radioimmunological method with SignaTECT cAMP-dependent PKA assay system.

RESULTS(1) Before forskolin treatment, the activity of PKA of L9981-nm23-H1-pLXSN was remarkably higher than those of L9981 and L9981-pLXSN (P < 0.01), but no significant difference in the PKA activity was observed between L9981 and L9981-pLXSN (P > 0.05). (2)The PKA activity was remarkably increased in all the three lung cancer cell lines after treatment with different concentration of forskolin (P < 0.01), and up to the highest level at the concentration of 100 μmol/L. It showed a dose-dependent relationship between the PKA activity and forskolin concentration; (3) The PKA activity in all the three cell lines was elevated to the highest level at 30 minutes after treatment with forskolin of 100 μmol/L, and it showed a time-dependent relationship between the PKA activity and action time of forskolin.

CONCLUSIONS(1)Transfection of nm23-H1 gene can up-regulate the PKA activity of human high-metastasis large cell lung cancer cell line L9981, and its function as a tumor metastasis suppressor gene may be related to its effects on regulation of PKA signal transduction pathways; (2)Forskolin can remarkably up-regulate the PKA activity of L9981 cell line, and the elevation of PKA activity has a time-dependent and dose-dependent relation to forskolin.