Rifat Pamukcu

Sulindac Derivatives Inhibit Growth and Induce Apoptosis in Human Prostate Cancer Cell Lines

We examined the activity of two metabolites of sulindac (a nonsteroidal anti-inflammatory drug), sulindac sulfide and sulindac sulfone (exisulind, Prevatec), and a novel highly potent analog of exisulind (CP248) on a series of human prostate epithelial cell lines. Marked growth inhibition was seen with the BPH-1, LNCaP, and PC3 cell lines with IC50 values of about 66 microM, 137 microM, and 64 nM for sulindac sulfide, exisulind, and CP248, respectively. DNA flow cytometry and 4,6-diamido-2-phenylindole (DAPI) staining indicated that these three compounds also induced apoptosis in all of these cell lines. Similar growth inhibition also was seen with the PrEC normal human prostate epithelial cell line, but these cells were resistant to induction of apoptosis at concentrations up to 300 microM, 1 mM, and 750 nM of sulindac sulfide, exisulind, and CP248, respectively. Derivatives of LNCaP cells that stably overexpress bcl-2 remained sensitive to growth inhibition and induction of apoptosis by these compounds. In vitro enzyme assays indicated that despite its high potency in inhibiting growth and inducing apoptosis, CP248, like exisulind, lacked cyclooxygenase (COX-1 and COX-2) inhibitory activity even at concentrations up to 10 mM. Moreover, despite variations of COX-1 and COX-2 expression, the three benign and malignant prostate cell lines showed similar sensitivity to growth inhibition and induction of apoptosis by these three compounds. Therefore, sulindac derivatives can cause growth inhibition and induce apoptosis in human prostate cancer cells by a COX-1 and -2 independent mechanism, and this occurs irrespective of androgen sensitivity or increased expression of bcl-2. These compounds may be useful in the prevention and treatment of human prostate cancer.

Exisulind (sulindac sulfone) suppresses growth of human prostate cancer in a nude mouse xenograft model by increasing apoptosis

OBJECTIVESnRecent studies have shown that Exisulind, a sulfone metabolite of the nonsteroidal anti-inflammatory drug (NSAID) sulindac, has inhibitory activity in vitro with cultured human prostate cancer cells. To determine whether this effect might be pharmacologically relevant in vivo, we tested whether Exisulind therapy could suppress the growth of human prostate cancer cells in a nude mouse xenograft model.nnnMETHODSnThirty athymic nude mice were injected subcutaneously in the flank with 1 x 10(7) LNCaP human prostate tumor cells. All mice received a control diet for 21 days. One group of mice was continued on this control diet for an additional 4 weeks, a second group was switched to a diet supplemented with 0.05% Exisulind (40% of maximal tolerated dose [MTD]), and a third group was switched to a diet supplemented with 0.1% Exisulind (80% MTD) for the additional 4 weeks. Tumor growth was measured through the 4-week test period, and subsequently tissue sections from the various groups were tested for apoptotic and dividing cells by quantified use of the TUNEL assay and a bromodeoxyuridine (BrdU) incorporation immunoassay.nnnRESULTSnTumors grew by 158%, 24%, and 18% for the control and 0.05% and 0.1% Exisulind groups, respectively (P = 0.02) during the 4-week test period. Immunohistochemical studies on excised tumors showed an increased number of apoptotic bodies in the treated groups versus the control group (P<0.0001) but no change in the number of BrdU positive cells.nnnCONCLUSIONSnThis is the first study to show a direct in vivo effect of an NSAID-derived drug, lacking cyclooxygenase inhibitory activity, in a xenograft model of prostate cancer. Clinical studies to evaluate the effects of Exisulind against prostate cancer in humans are warranted.

Pro-apoptotic actions of exisulind and CP461 in SW480 colon tumor cells involve β-catenin and cyclin D1 down-regulation

Exisulind and its analogues are inhibitors of cyclic GMP phosphodiesterases (PDEs) that have been shown to activate and induce protein kinase G, resulting in the induction of apoptosis in colon cancer cells. These drugs also reduce beta-catenin protein levels and decrease cyclin D1 mRNA levels in SW480 cells. Herein we report on studies pertaining to exisulind regulation of beta-catenin levels and activity in colon tumor cells. Exisulind and its higher-affinity PDE analogues, (Z)-5-fluoro-2-methyl-(4-pyridylidene)-3-(N-benzyl)-indenylacetamide hydrochloride (CP461) and (Z)-1H-indene-3-acetamide, 5-fluoro-2-methyl-N-(phenylmethyl)-1-[(3,4,5-trimethoxyphenyl)methylene] (CP248), reduced beta-catenin, including the nuclear beta-catenin in SW480 cells (EC(50) approximately 200 microM, 1 microM, and <1 microM, respectively). The 50% reduction of beta-catenin was seen in 8-14 hr. There was no change in beta-catenin mRNA. Exisulind-induced beta-catenin reduction was blocked by the proteasomal inhibitor MG132 (Z-leu-Leu-Leu-CHO), indicating that the effect of exisulind involved ubiquitin-proteasomal degradation. A consequence of reduced beta-catenin in SW480 cells was that exisulind, CP461, and CP248 caused a concentration- and time-dependent decrease in cyclin D1 levels (EC(50) approximately 300 microM, 1 microM, and <1 microM, respectively) in 4 hr. The effect was via decreased cyclin D1 mRNA levels. Exisulind-induced degradation of beta-catenin was not blocked by the inhibition of caspase-3 activity and/or apoptosis, and some SW480 cells showed a reduction in beta-catenin levels before the appearance of early apoptosis indicators. Expression of the N-terminal 170 amino acid fragment of beta-catenin reduced the effects of beta-catenin degradation, cyclin D1 reduction, and the apoptosis response to exisulind. These results indicate that exisulind-induced beta-catenin degradation precedes the induction of apoptosis and that the down-regulation of inappropriate beta-catenin-activated genes accounts in part for the pro-apoptotic effects of exisulind and CP461 in colon tumor cells.

Specific cGMP binding by the cGMP binding domains of cGMP-binding cGMP specific phosphodiesterase.

The structure of cyclic GMP (cGMP)-binding (cGB), cGMP specific phosphodiesterase (PDE5) comprises several domains. We have used RT-PCR methods to clone the noncatalytic cGB domains of PDE5 from human colon cancer cell RNA and constructed glutathione-S-transferase (GST) fusion proteins to express and study the domains. One fragment showed 94% identity to bovine PDE5 and coded for the high affinity cGB domain of PDE5 (Val(156)-Asp(394), cGB-I). Another cloned fragment showed 92% identity to bovine PDE5 and coded for the phosphorylation site plus both high and low affinity cGB domains of PDE5 (Val(36)-Glu(529), cGB-II). Both fragments expressed as GST-cGB fusion proteins bound cGMP specifically, as determined by competitive [3H]-cGMP ligand binding. We found that cGB-I showed high affinity cGMP binding with K(d)=0.33 microM. cGB-II showed two cGMP binding sites with similar affinities and specificity to the native enzyme. cGB-II was phosphorylated by cGMP-dependent protein kinase (PKG) as reported for bovine PDE5. These data show that recombinant regulatory regions of PDE5 form cGB sites similar to native enzyme sites and confirm proposed domain functions. These results establish that recombinant fusion proteins of PDE5 domains may be used to further characterize the structure of PDE5.

Effect of disodium azodisalicylate on electrolyte transport in rabbit ileum and colon in vitro. Comparison with sulfasalazine and 5-aminosalicylic acid

Abstract Azodisalicylate, used to treat ulcerative colitis, causes diarrhea in up to 12.5% of patients. We compared the in vitro effects of azodisalicylate, sulfasalazine, and 5-aminosalicylic acid on rabbit intestinal electrolyte transport. Distal ileal mucosae mounted in Ussing chambers were exposed to varying concentrations of the drugs. Mucosal addition of azodisalicylate (>5 mM) caused the greatest aniondependent increase in short-circuit current of 83 μA/cm 2 (ED 50 = 0.3 mM). Isotope flux measurements suggest that azodisalicylate may stimulate predominantly electrogenic HCO 3 secretion and induces net NaCl secretion. In contrast, serosal addition of azodisalicylate and sulfasalazine (>5 mM) decreased short-circuit current, and 5-aminosalicylic acid had no effect. Azodisalicylate had no effect on ion transport in distal colon. The effects of azodisalicylate in ileum were not inhibited with piroxicam (an inhibitor of cyclooxygenase). Mucosal cyclic adenosine monophosphate and cyclic guanosine monophosphate levels were unchanged after ileal exposure to azodisalicylate. Azodisalicylate appears to be a mechanistically unusual secretagogue, possibly explaining the increased incidence of diarrhea seen in patients taking the drug.

Proapoptotic anti-inflammatory drugs

The very fact that apoptosis and nonsteroidal anti-inflammatory drugs (NSAIDs) can be linked in the same title should tell you that something unusual is happening. The image of NSAIDs among physicians is certainly discordant with that associated with cancer treatment, which usually involves administration of drugs with serious or even life-threatening toxicity. In contrast, the drugs discussed in this review, including selective cyclooxygenase-2 inhibitors, lipoxygenase inhibitors, and novel NSAID derivatives (eg, sulindac sulfone and R-flurbiprofen), offer the promise of oral, nontoxic agents able to control the progression of established prostate cancer and possibly to prevent the development of prostate cancer de novo. NSAIDs were initially developed to suppress inflammation and pain by inhibiting the production of prostaglandin E2 and its metabolites. At first glance, the fact that NSAIDs are active against prostate cancer in laboratory and clinical studies might suggest that prostaglandins play a pivotal role in prostate cancer biology. However, the story is much more complex than that. Although cyclooxygenase-mediated production of prostaglandins appears to play an important role in the biology of prostate cancer, the NSAIDs and derivatives with promising activity against prostate cancer manifest several mechanisms of action that can include direct inhibition of eicosanoid formation, indirect inhibition of eicosanoid formation by inhibiting expression of enzymes involved in eicosanoid synthesis, or by interfering with the function of cyclic guanosine monophosphate.

Olsalazine Induced Secretion in Rabbit IIeal Mucosa

Olsalazine has been observed to induce diarrhoea in 4.9% of patients. In vivo trials in rat ileum and colon suggest stimulation of secretion by olsalazine. The in vitro effect of olsalazine was examined on active anion secretion by rabbit distal ileum compared to sulphasalazine and 5-aminosalicylic acid (5-ASA). Rabbit terminal ileal strips were mounted in Ussing chambers, and the mucosal and serosal surfaces were selectively exposed to 3.0, 5.0, 1.0, 0.1 and 0.001 mM of olsalazine, sulphasalazine and 5-ASA. The maximal short circuit current (Isc, a measure of active anion secretion) was determined for each concentration. Olsalazine significantly stimulated anion secretion at concentrations above 0.001 mM with a more pronounced effect (approximate ED50 of 0.5 mM) when added to the mucosal surface. In contrast, sulphasalazine and 5-ASA demonstrated no secretory effect. Additional studies of transmucosal fluxes and chemical mediation of these effects are in progress and will be reported. Olsalazine stimulat...

Synthesis of radioactive sulindac‐sulfone‐lactone via sulfonium salt and 14C alkylhalide

A new method of radioactive labeling via sulfonium salts and 14C alkylhalides is reported, along with a novel synthesis of (E)-rac-(2′-buten-1′,4′-olido)-[3′,4′:1,2]-6-fluoro-2-methyl-3-(4-[14C-methyl]-sulfonylbenzylidene)-indan (scheme 1, compound 14CH3-SO2-L]), a drug that showed very high activity, when tested in various tumor cell lines (1). Copyright