THE SIGNAL EFFECTS OF PROTEIN KINASE C,PROTEIN KINASE A AND PROTEIN TYROSINE KINASE ON PROLIFERATION AND COLLAGEN SYNTHESIS OF FIBROBLASTS DERIVED FROM HYPERTROPHIC SCAR AND NORMAL SKIN UNDER TGF-β₁ OR IFN-γSTIMULATION

It is generally agreed that hypertrophic scar (HS) is characterized by excessive deposition of collagen and over-proliferated fibroblast. Growth factors play an important role in HS development. The mechanism of the effect is unknown. The activities of protein kinase C (PKC), protein kinase A(PKA),protein tyrosine kinase (PTK) ,as well as the proliferation and the collagen synthesis of the fibroblasts derived from the HS (HS-FB) and normal skin(NS-FB) were assayed to investigate the mechanisms of signal transduction.First of all, the activities of PKC, PKA, PTK in the tissues of HS, keloid (K), mature scar (MS), normal skin (NS) and HS with low level of proliferation (LHS) were assayed by transferring phosphorus (32P) into substrate. The results showed that the activities of PKC and PTK were decreased in the order of K, HS, LHS, MS and NS (p<0.001). And the difference between MS and NS was insignificant (p>0.05). However, the activity of PKA in all tissues was changed insignificantly (p>0.05). It indicated that PKC and PTK might mediate the signal of the proliferation and the collagen synthesis. And the activity of PKA had no significant change, which suggested that scar proliferation be related to the loss of PKA inhibition.The activity of PKC, PKA, PTK in the HS-FB and NS-FB before and after TGF- P i or IFN- Y stimulating were assayed by transferring phosphorus (32P) into substrate. Cell proliferation was measured by MTT stain. The collagen synthesis was determined by 3H-proline incorporation assay and by radioimmunoassay.The action of PKC on proliferation and collagen synthesis of HS-FB and NS-FB.TGF- P i or IFN- y stimulation were investigated. The results showed that PKC activator (PS,DG,Ca2*) and TGF- P i could stimulate proliferation and collagen synthesis of HS-FB and NS-FB (PO.05 or 0.01 at 30min-60min).GF 109 could inhibit it(p<0.05 at 60min) and abrogate the functions of TGF- P , partly (p<0.05,to compare with TGF- P i group). At the same time, the PKC activity of NS-FB and HS-FB was enhanced by TGF- 3 , (p<0.05 after SOmin). The effect of TGF- B , can be canceled by GF109. All results might indicate that the influence of TGF- 3 , on HS-FB and NS-FB might be partly mediated by PKC signal passage. IFN- Y could increase proliferation and collagen synthesis of HS-FB and NS-FB transiently (PO.05 or 0.01 at 30min-60min) and then decrease it. But the collagen syntheses of the signal cell don't decrease (p<0.05, compared with the control). Change of PKC activity after IFN- Y stimulation was similar to varies of proliferation(p<0.05 or 0.01 at 30-60min and to back in control level at 120min).GF109 could reverse transient roles of IFN- Y (p<0.05) and couldn't affect the inhibitory function. All these might suggest that the transient enhancement of IFN- Y might be mediated by PKC signal passage and its inhibition seem not to be related to PKC signal passage and that it could enhance or inhibit proliferation and collagen synthesis of FB to activate or inhibit of PKC.The action of the signal PKA on proliferation and collagen synthesis of HS-FB and NS-FB, TGF- P i or IFN- Y stimulation were investigated. The results showed that cAMP could inhibit the FB proliferation(p<0.05 after 60min).The influence of H? and TGF- P i on proliferation were alike(p<0.05 after 30min).Furthermore,H7 could strengthen the functions of TGF- P i(p<0.05 at 30-60min).The PKA activity of NS-FB was transiently raised and return to normal immediately by TGF- P i(p>0.05). One of HS-FB was reduced (p<0.05 at 30-60min) and recovered after 60min. The results suggested that there might be some differences with cAMP/PKA between HS-FB and NS-FB and activation of PKA might cancel the roles of TGF- P ]. Again, H? could reinforce the transient roles of IFN- Y (p>0.05) and reverse partly its inhibitory functions(p<0.05). IFN-Y may simultaneously activate PKA (p<0.05 after 60min). These results might indicate that the inhibitory roles of IFN- Y might be partly mediate by PKA signaling and that activating PKA could inhibit proliferation...