Abstract:

Objective To investigate the changes of protein kinase C (PKC) isoforms in rat vascular smooth muscle cells (VSMCs) treated with prolonged incubation of phorbol-12-myristate-13-acetate (PMA). Methods Primary rat vascular smooth muscle cells cultured in vitro were divided into blank group, 1, 5, and 10 μmol/L PMA-treated groups, and 0.25‰ DMSO-treated group, and all cells were treated for 4 h. The other cells were treated with 10 μmol/L PMA for 1, 4, and 24 h and with 0.25‰ DMSO for 24 h. The levels of PKCs were measured using Western blotting. Results In 1, 5, and 10 μmol/L PMA-treated groups for 4 h, the levels of PKC-α had no significant changes (P>0.05), while in 10 μmol/L PMA-treated group for 24 h, PKC-α was down-regulated significantly (P<0.05). PKC-δ expression was down-regulated obviously in VSMCs treated with PMA (>5 μmol/L for over 4 h)(P<0.01). PKC-ε expression had no changes in PMA-treated groups (<5 μmol/L shorter than 4 h) (P>0.05), while PKC-ε decreased remarkably in PMA group (10 μmol/L for 1 h)(P<0.01). PKC-θ expression was down-regulated obviously in VSMCs treated with PMA (>5 μmol/L for over 4 h)(P<0.01). Level of PKC-ζ had no changes in PMA group (10 μmol/L for 24 h)(P>0.05). Conclusion Prolonged treatment with PMA down-regulated classical PKC-α and novel PKC-δ, ε, and θ in VSMCs, while had no effect on atypical PKC-ζ.

Key words: phorbol-12-myristate-13-acetate, vascular smooth muscle cells, protein kinase C