ABSTRACT
The effects of pituitary adenylate cyclase activating polypeptide (PACAP) on human lung cancer cell line NCI-1299 mitogen activated protein kinase (MAPK) tyrosine phosphorylation and vascular endothelial cell growth factor (VEGF) expression were investigated. PACAP-27 (100 nM) increased MAPK tyrosine phosphorylation 3-fold, 5 min after addition to NCI-H1299 cells. PACAP caused tyrosine phosphorylation in a concentration-dependent manner being half-maximal at 10 nM PACAP-27. PACAP-27 or PACAP-38 (100 nM) but not PACAP28-38 or VIP caused increased MAPK tyrosine phosphorylation using NCI-H1299 cells. Also, the increase in MAPK tyrosine phosphorylation caused by PACAP-27 was totally inhibited by 10 microM PACAP(6-38), a PAC(1) receptor antagonist or 10 microM PD98059, a MAPKK inhibitor. These results suggest that PAC(1) receptors regulate tyrosine phosphorylation of MAPK in a MAPKK-dependent manner. PACAP-27 (100 nM) caused increased VEGF mRNA in NCI-H1299 cells after 8 h. The increase in VEGF mRNA caused by PACAP-27 was partially inhibited by PACAP(6-38), PD98059 and H-89. Addition of VIP to NCI-H1299 cells caused increased VEGF mRNA, which was totally inhibited by H89, a PKA inhibitor. These results suggest that PAC(1) and VPAC(1) receptors regulate VEGF expression in lung cancer cells.
Subject(s)
Endothelial Growth Factors/genetics , Endothelial Growth Factors/metabolism , Intercellular Signaling Peptides and Proteins/genetics , Intercellular Signaling Peptides and Proteins/metabolism , Lung Neoplasms/genetics , Lung Neoplasms/metabolism , Lymphokines/genetics , Lymphokines/metabolism , Mitogen-Activated Protein Kinases/metabolism , Neuropeptides/pharmacology , 3T3 Cells , Animals , Humans , Lung Neoplasms/enzymology , Mice , Phosphorylation/drug effects , Phosphotyrosine/metabolism , Pituitary Adenylate Cyclase-Activating Polypeptide , RNA, Messenger/genetics , RNA, Messenger/metabolism , Transfection , Tumor Cells, Cultured , Vascular Endothelial Growth Factor A , Vascular Endothelial Growth FactorsABSTRACT
The effects of prostaglandin (PG)E2 on lung cancer cells were investigated. 3H-PGE2 bound with high affinity to membranes derived from small cell lung cancer (SCLC) and non-SCLC (NSCLC) cell lines. Using NSCLC NCI-H1299 membranes, specific 3H-PGE2 binding to NCI-H1299 membranes was inhibited with moderate affinity by PGE2, PGE1, PGF2alpha and 6-isopropoxy-9-xanthone-2-carboxylic acid (AH6809) but not PGD2, LTB4 or 5-HETE. By RT-PCR, EP2 receptor PCR products were detected in extracts derived from lung cancer cells. PGE2 caused cAMP elevation in a concentration-dependent manner using NCI-H1299 cells and the increase in cAMP caused by PGE2 was antagonized by AH6809. PGE2 had no effect on cytosolic Ca2+ but PGE2 caused increased c-fos mRNA in NCI-H1299 cells. AH6809 inhibited the proliferation of NCI-H1299 cells using MTT and clonogenic assays. These results indicate that functional PG receptors are present on NSCLC cells which are antagonized by AH6809.
