Javamide-I-O-methyl ester increases p53 acetylation and induces cell death via activating caspase 3/7 in monocytic THP-1 cells

BACKGROUND

Javamide-I and-II are phenolic amide compounds found in Coffea sp. Previous study suggested that javamide-II may be a potent compound with Sirt1/2 inhibition activity.

PURPOSE

However, the effects of javamide-I and the its O-methyl ester on Sirt inhibition, p53 acetylation and cell death have not been investigated.

METHODS

The isolation and synthesis of javamide-I and its O-methyl ester analogue were confirmed by NMR. Their potential effects on Sirt1/2/3, p53 acetylation and cell death were examined using sirt assay, silico analysis, Western blot, caspase 3/7 and apoptotic assay methods.

RESULTS

Javamide-I and its O-methyl ester demonstrated a similar inhibition pattern; Sirt1 (IC₅₀ of 19µM) better than Sirt2 (IC₅₀ of 104µM) and Sirt3 (IC₅₀ of 160µM). However, javamide-I and its O-methyl ester were found to inhibit Sirt1 better than Sirt2, which is different from javamide-II able to inhibit Sirt2 stronger than Sirt1. In silico analysis, javamide-I and its O-methyl ester showed a competitive binding pattern against NAD^+, which was also supported by the kinetic analysis with K_i=20.1µM for javamide-I and 19.5µM for the O-methyl ester. However, the O-methyl ester increased p53 acetylation better than javamide-I in monocytic THP-1 cells. Since caspase 3/7 activation is often followed by the p53 activation, we investigated their effects on caspase 3/7, and found that O-methyl ester again activated caspase 3/7 greater than javamide-I in the cells, eventually leading to apoptotic cell death.

CONCLUSION

These data suggest that the O-methyl modification in javamide-I may play a critical role in increasing p53 acetylation, activating caspase, and eventually inducing the THP-1 cell death.

Modulation of human neutrophil apoptosis by gut hormones

BACKGROUND

Inhibition of neutrophil apoptosis seems to be a prominent feature in inflammation, parenchymal damage, and unresolved organ dysfunction. Agents that modulate neutrophil apoptosis could alter the course of the disease. A variety of endogenous peptides, including some GIT hormones, have been reported as modulators of apoptosis in several types of cells.

OBJECTIVES

We aimed to study the effect of the GIT hormones VIP, gastrin, secretin, GIP and CCK on the in vitro viability of human neutrophils and the associated caspase changes.

METHODS

Neutrophils were prepared from the venous blood of twenty healthy male volunteers using density gradient centrifugation. Neutrophils were cultured in RPMI and treated with two concentrations of each of the five hormones and incubated for 1, 2, 4 and 6 hours. Viability was assessed by a kit that measured ATP levels. Caspase 3/7, caspase 8 and caspase 9 were measured using specific kits.

RESULTS

VIP accelerated apoptosis causing a 15 - 32% decrease in neutrophil viability in 11 of the twenty volunteers. VIP increased the levels of caspase 8 and caspase 3/7. Gastrin suppressed apoptosis causing a 17-30% increase in neutrophil viability in 7 of the twenty volunteers. However, VIP inhibited apoptosis in one subject and gastrin accelerated apoptosis in two subjects. The effects of secretin, GIP and CCK were not marked.

CONCLUSIONS

The modulatory effects of VIP and gastrin on human neutrophil apoptosis are seen in a proportion, not all, of the population. VIP is more consistent in its effects than gastrin.