[A study of protein kinase C signal pathway in regulating airway smooth muscle cell proliferation in asthmatic rats].

OBJECTIVE: To investigate the role of protein kinase C (PKC) signal pathway in airway smooth muscle cell (ASMCs) proliferation in asthmatic rats. METHODS: (1) Forty-eight Wistar rats were divided into an asthmatic group (group A) and a control group (group B), and then subdivided into group A(1), A(2), A(3) and group B(1), B(2), B(3) based on the time of challenge (2, 4, 8 weeks). The proliferation of ASMCs isolated from group A and B was examined with cell cycle analysis, MTT colorimetric assay and proliferating cell nuclear antigen (PCNA) immunocytochemical staining. (2) ASMCs from group A(1) and B(1) were treated with PKC agonist PMA and inhibitor Ro-31-8220, and their proliferations were examined. (3) The expression of PKC-alpha in group A(1), A(2), A(3) and B(1) was observed by immunocytochemical staining and RT-PCR, respectively. RESULTS: (1) The percentage of S phase, absorbance (A) value and the expression rate of PCNA protein in ASMCs from group A were significantly increased compared to those of group B (P < 0.01). (2) Before ASMCs from A(1) group were treated, the percentage of S phase, A value and the expression rate of PCNA were (19 +/- 3)%, 0.459 +/- 0.036, and (80 +/- 10)% respectively; After treated with 10 nmol/L PMA, these values reached (27 +/- 4)%, 0.599 +/- 0.078, and (95 +/- 9)% respectively; After treated with 50 nmol/L PMA, these values were (14 +/- 3)%, 0.346 +/- 0.038, and (53 +/- 8)% respectively; After treatment with Ro-31-8220, these values were (14 +/- 3)%, 0.343 +/- 0.048, and (49 +/- 8)% respectively. Statistical analysis revealed that there were significant differences in the percentage of S phase, A value and the expression of PCNA before and after treatment (P < 0.01). After treatment with 50 nmol/L PMA, there was a significant difference as compared to 10 nmol/L PMA treatment (P < 0.01), whereas there was no statistical significance as compared to Ro-31-8220 treatment (P > 0.05). (3) Compared with that of group B(1) (0.84 +/- 0.07), the ratios of A value of PKC-alpha mRNA in group A(1) (1.08 +/- 0.06), group A(2) (1.12 +/- 0.05), and group A(3) (1.10 +/- 0.08) were significantly increased (P < 0.01). Compared with that of group B(1) (28 +/- 4)%, the expression rates of PKC-alpha protein in group A(1) (54 +/- 5)%, group A(2) (56 +/- 5)%, and group A(3) (53 +/- 6)% were significantly increased (P < 0.01). CONCLUSIONS: Airway smooth muscle cell proliferation increases in asthmatic rats. PKC and it's alpha subtype may contribute to this process.