Decrease of cyclin D1 and CDK4 protein and their related factors induced by quartz in human embryonic lung fibroblasts

Objective To study the expression level of cyclin D1-CDK4 protein in human embryonic lung fthroblasts (HELF) induced by quartz, and to study whether the expression level of eyclin D1-CDK4 protein mediated by mitogen activated protein kinase (MAPK)/(AP-1 )signaling pathways. Methods Cells were harvested after stimulation 2h for the detection of cytokines. Cyclin D1 and CDK4 (cyclin dependent kinase 4)proteins was measured by immunocytochemistry(IC) and Western blot(WB). Results The exposure of HELF to crystalline quartz for 2 hours could cause the decrease of cyclin D1 and cyclin dependent kinase 4 (CDK4)protein expression level, (7.91±0.29)x 103 and (5.17±0.28 )×104 respectively, which was lower than that of the HELF group (P＜0.05). AG126 (chemical inhibitor of the extracel-lular signalregulated protein kinase (ERK) signaling pathway) and the dominant negative mutant of ERK2 (molecular inhibitor of ERK2), prevented the decrease of cyclin D1 and CDK4 protein expression level. The chemical inhibitor of c-Jun NH2-terminal amino kinase (JNK),SP600125,could prevent both eyclin D1 and CDK4 protein expression level decrease. ButSB203580, the chemical inhibitor of p38, prevented neither cyclin D1 nor CDK4 protein expression level decrease. Curcumin could prevent CDK4 protein expression level decrease but not cyclin D1 protein. ConclusionERKs and JNKs, but not p38, are responsible for the decrease of eyclin D1 and CDK4 protein expression level in HELF induced by quartz. AP-1 is responsible for the decrease of CDK4 expression level but not that of cyclin D1. Key words: Quartz; Cyclin-dependent kinases; Cyelin D1; Tmnscdptionfactor AP-1