Shikonin­mediated inhibition of nestin affects hypoxia­induced proliferation of pulmonary artery smooth muscle cells.

The imbalance between the proliferation and apoptosis of pulmonary artery smooth muscle cells (PASMCs) is of importance in pulmonary vascular remodeling. Shikonin, a naphthoquinone compound extracted from the Chinese medicinal herb Lithospermum erythrorhizon, inhibits the proliferation of rat smooth muscle cells (SMCs). The present study was designed to investigate the effects of shikonin on the proliferation of rat PASMCs and the possible mechanisms involved. Rat PASMCs were cultured under the following five treatment conditions: Normal control; hypoxia for 24 h; hypoxia + 1 µM shikonin for 24 h; hypoxia + 2 µM shikonin for 24 h; and hypoxia + 4 µM shikonin for 24 h. The viability of PASMCs was measured using the Cell Counting Kit­8 assay, the mRNA expression of nestin (NES) in each group was measured by reverse transcription­polymerase chain reaction and the protein expression of NES was measured by western blotting. The proliferation of hypoxic PASMCs transfected with NES­specific small interfering (si)RNA decreased compared with the non­transfected group. These results indicated that hypoxia induced the proliferation of PASMCs through the enhancement of NES expression. The treatment of hypoxic PASMCs with shikonin resulted in a significant downregulation of NES expression and the inhibition of PASMC proliferation.