Stimulation of synthesis de novo of NAD+-dependent 15-hydroxyprostaglandin dehydrogenase in human promyelocytic leukaemia (HL-60) cells by phorbol ester

Abstract

Human promyelocytic leukaemia (HL-60) cells were employed to study the induction of NAD(+)-dependent 15-hydroxyprostaglandin dehydrogenase (15-PGDH), the key enzyme in controlling prostaglandin inactivation. Phorbol 12-myristate 13-acetate (PMA) stimulated 15-PGDH activity in a time- and concentration-dependent manner. Dimethyl sulphoxide (DMSO) also stimulated the enzyme activity, although a much delayed stimulation was observed. Western blot studies indicated that PMA increased significantly a 28 kDa immunoreactive protein characteristic of 15-PGDH. L-[35S]Methionine labelling of the PMA-treated cells showed a similar enhancement over the control cells. These studies indicate that PMA induced synthesis of 15-PGDH. Stimulation of 15-PGDH activity by PMA or DMSO appears to be mediated by protein kinase C activation, since an inactive analogue of PMA failed to induce the effect, and both staurosporine and H-7 blocked the stimulation. Stimulation by PMA was optimal at 10 nM and less effective at higher concentrations. Western blot studies indicated that a similar, if not greater, amount of enzyme protein was induced at high concentrations of PMA, suggesting that enzyme inactivation might be occurring. Possible enzyme inactivation by protein kinase C activation was further examined by incubating DMSO-treated cells with a high concentration of PMA (50 nM). Time-dependent inactivation of 15-PGDH within the first 1 h was observed and this inactivation was partially blocked by staurosporine and H-7. Pulse-chase experiments indicated that 15-PGDH had a rapid turnover rate (t 1/2 = 47 min), and PMA shortened the half-life of the enzyme (t 1/2 = 33 min), suggesting that PMA might have an additional effect on 15-PGDH degradation. The rapid turnover of 15-PGDH indicates that the enzyme activity depends on continued enzyme synthesis, and this could be susceptible to hormone and drug control mechanisms.

The effects of mifepristone (RU486) on prostaglandin dehydrogenase in decidual and chorionic tissue in early pregnancy

“…PGDH is high in secretory phase endometrium and probably never falls in a pregnant cycle and is certainly high in early pregnancy decidua (Keirse and Turnbull, 1975;Keirse, 1985). PGDH may be under progesterone control (Casey et al, 1980;Alam et al, 1975;Falkay and Sas, 1987;Bedwani and Marley, 1975) and it is not surprising that RU486 reduces the activity of this enzyme, which has a short half-life (Xun et al, 1991), and thus is well placed as a key controller of prostaglandin concentration. The result of a decrease in PGDH activity would be both an increase in sensitivity to exogenous prostaglandin (Swahn and Bygdeman, 1988), because of reduced catabolism, and an increased effectiveness of prostaglandin produced within the amnion or decidua (Mitchell et al, 1978).…”

“…Early studies showed that the 15-keto metabolites from such an action were inactive in several test systems (Anggard, 1966). The turnover of PGDH expressed as the interval in which half the enzyme disappears (U A ) has recently been estimated as 47 min (Xun et al, 1991). This short half-life shows that PGDH is ideally suited for a role controlling effective concentrations of prostaglandins in the tissues, and high local concentrations of PGDH suggest that although lung deactivation of prostaglandins may be critical in maintaining low circulating concentrations, local inactivation may be the critical factor in controlling tissue concentrations.…”

NAD+-Linked 15-Hydroxyprostaglandin Dehydrogenase: Structure and Biological Functions

“…Subsequently, the induction was found to achieve by 1, 25-dihydroxyvitamin D 3 in human neonatal monocytes [46], by indomethacin in human tumoral C cells [47], and by phorbol 12-myristate 13-acetate (PMA) in HL-60 and HEL cells [48,49]. In addition to PMA being able to induce 15-PGDH expression, progesterone, androgens, estrogens, dexamethasone and other anti-inflammatory steroids also induced 15-PGDH expression in HEL cells at the submicromolar concentrations [49].…”

Expression of genes controlling transport and catabolism of prostaglandin E2in lipopolysaccharide fever

“…Hence, the biological activity of PGE 2 is highly responsive to changes in its catabolism (24). It is also known that the half-life of the major dehydrogenase for PGE 2 , 15-PGDH, is on the order of tens of minutes (7,67). Moreover, it has been experimentally shown that changes at the mRNA level readily translate into corresponding changes at the protein level for PGE 2 -inactivating enzymes (23,67).…”

“…It is also known that the half-life of the major dehydrogenase for PGE 2 , 15-PGDH, is on the order of tens of minutes (7,67). Moreover, it has been experimentally shown that changes at the mRNA level readily translate into corresponding changes at the protein level for PGE 2 -inactivating enzymes (23,67). This information allows us to speculate about the physiological significance of the drastic transcriptional downregulation observed in the present study even though our own work focused only on the expression of the PGE 2 -inactivating enzymes at the mRNA level.…”