Sulindac Sulfide Is a Noncompetitive γ-Secretase Inhibitor That Preferentially Reduces Aβ42 Generation

Abstract

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been known to reduce risk for Alzheimer's disease. In addition to the anti-inflammatory effects of NSAIDs to block cylooxygenase, it has been shown recently that a subset of NSAIDs selectively inhibits the secretion of highly amyloidogenic A␤42 from cultured cells, although the molecular target(s) of NSAIDs in reducing the activity of ␥-secretase for A␤42 generation (␥ 42 -secretase) still remain unknown. Here we show that sulindac sulfide (SSide) directly acts on ␥-secretase and preferentially inhibits the ␥ 42 -secretase activity derived from the 3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxy-1-propanesulfonate-solubilized membrane fractions of HeLa cells, in an in vitro ␥-secretase assay using recombinant amyloid ␤ precursor protein C100 as a substrate. SSide also inhibits activities for the generation of A␤40 as well as for Notch intracellular domain at higher concentrations. Notably, SSide displayed linear noncompetitive inhibition profiles for ␥ 42 -secretase in vitro. Our data suggest that SSide is a direct inhibitor of ␥-secretase that preferentially affects the ␥ 42 -secretase activity. Alzheimer's disease (AD)1 is a dementing neurodegenerative disorder of the elderly characterized pathologically by neuronal loss in the cerebral cortex accompanied by massive deposition of amyloid ␤ peptides (A␤) as senile plaques (1). A␤ is produced by sequential proteolytic cleavages of the amyloid ␤ precursor protein (␤APP) by a set of membrane-bound proteases termed ␤-and ␥-secretases. The C-terminal length of A␤ generated by ␥-secretase is heterogeneous; A␤42 is a relatively minor molecular species of the A␤ secreted from cells, but it has a much higher propensity to aggregate and form amyloid compared with other A␤ species. These findings provide strong support for the hypothesis that the deposition of A␤42 is closely related to the pathogenesis of AD, implicating ␥-secretase as an important therapeutic target.Mutations in PS1 or PS2 genes account for the majority of early onset familial AD, and these mutations cause an increase in the ratio or levels of production of A␤42 (1). It is known that PS is essential for the ␥-secretase-mediated intramembranous cleavage not only for ␤APP but for other type I transmembrane proteins (e.g. Notch, ErbB4, E-cadherin, low density lipoprotein receptor-related protein, and CD44) (2). PS proteins undergo endoproteolysis to generate N-and C-terminal fragments and interact with other proteins (i.e. nicastrin, APH-1, and PEN-2) to form a high molecular weight (HMW) protein complex (3). The functional role of PS complex in ␥-secretase activity still remains unknown. However, aspartyl protease transition state analogue inhibitors of ␥-secretase, which harbors a hydroxyl ethylene isostere or a difluoro alcohol moiety, directly label PS fragments (4 -6). In addition, a systematic analysis using a variety of PS mutants revealed that HMW complex formation of PS as well as conserved aspartyl residues within the transmembrane domain are es...

Endoplasmic reticulum stress response is involved in nonsteroidal anti-inflammatory drug-induced apoptosis

“…2 Treatment of amyloid precursor protein transgenic mice with some NSAIDs suppressed the development of amyloid plaques pathology 32 and NSAIDs lowered the level of amyloid b-protein in cultured cells. 5 Although it was recently reported that some NSAIDs inhibit g-secretase that is involved in amyloid b-protein production, 33 the mechanism for decrease in amyloid b-protein production by NSAIDs is not fully understood. We showed that induction of GRP78 and CHOP by indomethacin was not specifically observed in gastric mucosal cells but observed in other cells, such as HEK293 (human embryonic kidney) cells (data not shown).…”

Ibuprofen Suppresses Interleukin-1β Induction of Pro-Amyloidogenic α1-Antichymotrypsin to Ameliorate β-Amyloid (Aβ) Pathology in Alzheimer's Models

“…Considering the first of these three mechanisms, high dose ibuprofen (100-500 mM) has been shown to reduce Ab42 production in vitro, an effect also shown by other NSAIDs to be independent of their antiinflammatory effects on regulating COX, PPAR, and NFkB (Weggen et al, 2001;Morihara et al, 2002;Sagi et al, 2003;Takahashi et al, 2003). Although the COX-dependency of ibuprofen's effects on Ab42 suppression has not been tested, another NSAID sulindac has been more extensively analyzed and clearly reduces Ab42 independent of COX (Weggen et al, 2001;Sagi et al, 2003;Takahashi et al, 2003). Ab42 production was reduced in 3-month-old Tg2576 mice with a brain ibuprofen level of B2 mM, which, surprisingly, was much lower than dosing required in vitro .…”

“…The major inflammatory target of NSAIDs, including ibuprofen, is cyclooxygenase (COX), and in our model ibuprofen-induced plaque reduction was associated with reductions in brain interleukin-1b, a downstream target of COX. Although this and other evidence suggests a possible role of inflammation in controlling plaque pathogenesis, this hypothesis has been challenged by discovery of an unexpected COX-independent function of a subset of NSAIDs (including ibuprofen) in reducing Ab42 production in vitro (Weggen et al, 2001(Weggen et al, , 2003aMorihara et al, 2002;Eriksen et al, 2003;Sagi et al, 2003;Takahashi et al, 2003;Zhou et al, 2003). Adding to the controversy whether the mechanism(s) of plaque reduction are inflammationdependent or -independent, it is unclear whether the high ibuprofen concentrations required in vitro to reduce Ab42 production can be attained in the human brain with doses shown epidemiologically to reduce AD risk.…”

Non-steroidal anti-inflammatory drugs have anti-amyloidogenic effects for Alzheimer's β-amyloid fibrils in vitro

“…Second, a subset of NSAIDs such as Ibu, sulindac sulfide (SSide), indomethacin (Ind) (Weggen et al, 2001) and flurbiprofen (Flu) selectively decreased the secretion of Aß(1-42) from cultured cells independently of cyclooxygenase (COX) activity and lowered the amount of soluble in the brains of Tg2576 mouse. Third, SSide and enantiomers of Flu have been reported to target γ-secretase and preferentially reduce Aß(1-42) generation (Takahashi et al, 2003;Eriksen et al, 2003).…”