Cooperation between retinoic acid and phorbol esters enhances human teratocarcinoma differentiation.
This study explored cooperation between the retinoic acid (RA) and protein kinase C (PKC) pathways during differentiation of the multipotential human teratocarcinoma (TC) cell line NTERA-2 clone D1 (abbreviated NT2/D1). We report here that, compared to RA treatment alone, RA combined with the PKC stimulator 12-O-tetradecanoylphorbol-13-acetate (TPA) enhanced the regulated expression of the immunophenotypic differentiation markers SSEA-3, a globo-series carbohydrate, and the ganglio-series carbohydrate antigens GD2 and GD3. Northern analysis and transient transfection assays revealed that TPA co-treatment augmented the RA-induced expression and activation of the RA nuclear receptor-beta (RAR-beta), one early marker of RA response in NT2/D1 cells. This finding was extended with transient co-transfection experiments using a PKC-alpha expression vector which revealed that the PKC pathway can augment the activation of RAR-beta by RA. These experiments establish PKC as a modulator of RAR-beta expression in NT2/D1 cells. Similarly, experiments showed that RA can modulate activation of the PKC-responsive AP-1 complex, a transcription factor rapidly activated by TPA. Northern analysis and transient transfection assays revealed that, compared to TPA treatment alone, RA and TPA augmented the expression and transcriptional activity of AP-1 in NT2/D1 cells. In contrast, transient transfection assays revealed no cooperative effect between RA and TPA in HeLa cells, indicating that this effect in NT2/D1 cells is cell type-specific. In summary, these studies show that stimulation of the PKC second messenger pathway can modulate tumor differentiation and transcriptional activation of a retinoid receptor associated with RA response.
Kurie
J M
JM
Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY 10021.
Brown
P
P
Salk
E
E
Scheinberg
D
D
Birrer
M
M
Deutsch
P
P
Dmitrovsky
E
E
D015415:Biomarkers / Q000737:chemistry; D002454:Cell Differentiation / Q000187:drug effects; D002999:Clone Cells / Q000187:drug effects; D004357:Drug Synergism; D006801:Humans; D016130:Immunophenotyping; D011493:Protein Kinase C / Q000187:drug effects*; D016755:Proto-Oncogene Proteins c-jun / Q000096:biosynthesis; D018168:Receptors, Retinoic Acid / Q000096:biosynthesis; D018243:Teratocarcinoma / Q000235:genetics / Q000473:pathology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects; D015533:Transcriptional Activation / Q000187:drug effects; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D015415:Biomarkers; D016755:Proto-Oncogene Proteins c-jun; D018168:Receptors, Retinoic Acid; C082925:retinoic acid receptor beta; D014212:Tretinoin; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate