摘要
In studying a relatively well-differentiated human hepatoma cell line (Hep G2),we found that the cells produced and secreted biologically active PTHrP.The present study was designed to determine whether PTHrP production by Hep G2 cells could be altered by agents that affect cell growth.PTHrP production was assessed by measuring immunoreactive peptide in culture medium using the Nichols immunoradiometric assay and by evaluating PTHrP mRNA levels in cells using Northern analysis. Treatment with 10μmol/L hydrocortisone or 10μg/L TGF-βfor 3 days inhibited Hep G2 cell growth by (28±6)%and(36)2) fi respectively and increased PTHrP in medium by (128 ±10)% and (525 ±27)% respectively.Related studies showed that the increase in PTHLP produced by both agents was dose-and time-dependent and that the increase in peptide in the medium was accompanied by an increase in PTHrP mRNA in the cells which also was dose- and timedependent. In contrast,culture of HeP G2 cells for 3 days in 10% fetal boxrine serum(FBS)or in high glucose(4 g/L)significantly increased cell growth by(38±6)%(vs no serum)and by(43±1)%(vs 1 g/L glucose) and suppressed PTHrP in the culture medium by (49±4)% and(55±0.4)%, respectively. The inhibition of PTHrP was found to be dose-and time-dependent,but FBS only marginally suppressed PTHrP mRNA levels and glucose did not detectably alter PTHrP mRNA. The results show that PTHrP production and secretion in HeP G2 cells can be regulated by factors that affect growth of the cells in culture. Agents which suppressed cell growth enhanced PTHrP production, while those that stimulated cell growth were associated with reduced PTHrP in medium. The findings imply that PTHrP may be involved in the altered cell growth produced by these factors; if so,the peptide appears to act as a suppressor of Hep G2 cell growth.
In studying a relatively well-differentiated human hepatoma cell line (Hep G2),we found that the cells produced and secreted biologically active PTHrP.The present study was designed to determine whether PTHrP production by Hep G2 cells could be altered by agents that affect cell growth.PTHrP production was assessed by measuring immunoreactive peptide in culture medium using the Nichols immunoradiometric assay and by evaluating PTHrP mRNA levels in cells using Northern analysis. Treatment with 10μmol/L hydrocortisone or 10μg/L TGF-βfor 3 days inhibited Hep G2 cell growth by (28±6)%and(36)2) fi respectively and increased PTHrP in medium by (128 ±10)% and (525 ±27)% respectively.Related studies showed that the increase in PTHLP produced by both agents was dose-and time-dependent and that the increase in peptide in the medium was accompanied by an increase in PTHrP mRNA in the cells which also was dose- and timedependent. In contrast,culture of HeP G2 cells for 3 days in 10% fetal boxrine serum(FBS)or in high glucose(4 g/L)significantly increased cell growth by(38±6)%(vs no serum)and by(43±1)%(vs 1 g/L glucose) and suppressed PTHrP in the culture medium by (49±4)% and(55±0.4)%, respectively. The inhibition of PTHrP was found to be dose-and time-dependent,but FBS only marginally suppressed PTHrP mRNA levels and glucose did not detectably alter PTHrP mRNA. The results show that PTHrP production and secretion in HeP G2 cells can be regulated by factors that affect growth of the cells in culture. Agents which suppressed cell growth enhanced PTHrP production, while those that stimulated cell growth were associated with reduced PTHrP in medium. The findings imply that PTHrP may be involved in the altered cell growth produced by these factors; if so,the peptide appears to act as a suppressor of Hep G2 cell growth.
