The novel phospho-non-steroidal anti-inflammatory drugs, OXT-328, MDC-22 and MDC-917, inhibit adjuvant-induced arthritis in rats

BACKGROUND AND PURPOSE

The use of non-steroidal anti-inflammatory drugs (NSAIDs) in the treatment of rheumatoid arthritis (RA) is limited by their toxicity. We evaluated the anti-inflammatory efficacy and safety of three novel modified NSAIDs, phospho-aspirin, phospho-ibuprofen and phospho-sulindac.

EXPERIMENTAL APPROACH

We determined the anti-inflammatory effects and gastrointestinal safety of the phospho-NSAIDs in the rat adjuvant arthritis model and studied their mechanism of action in cultured cells, Cytokines were measured with elisa and activation of nuclear factor-κB (NF-κB) by immunohistochemistry.

KEY RESULTS

All three phospho-NSAIDs showed less gastrointestinal toxicity than their parent compounds and demonstrated strong anti-inflammatory effects, essentially reversing joint inflammation and oedema. They have a broad but not uniform effect on the expression of relevant cytokines, in general decreasing IL-6 and IL-1β and increasing IL-10 levels in rat plasma and cultured cells. Phospho-sulindac and phospho-ibuprofen but not phospho-aspirin suppressed PGE(2) production in vitro, whereas phospho-aspirin (in contrast to aspirin) showed the same effect in vivo. In joint tissues, phospho-aspirin inhibited NF-κB activation, and suppressed inflammation and bone resorption. Phospho-aspirin also inhibited Jurkat T cell proliferation. In general, phospho-aspirin had greater efficacy but different effects upon inflammatory mediators compared with aspirin. The chemical modification of the parent NSAIDs seems crucial for their safety and efficacy.

CONCLUSIONS AND IMPLICATIONS

Phospho-aspirin, phospho-ibuprofen and phospho-sulindac were safer than their parent NSAIDs, were highly effective in rat adjuvant arthritis and inhibited many key mediators in the pathophysiology of RA. These novel compounds are promising candidate drugs for the treatment of RA and merit further evaluation.

Exisulind and guanylyl cyclase C induce distinct antineoplastic signaling mechanisms in human colon cancer cells

The nonsteroidal anti-inflammatory drug sulindac is metabolized to sulindac sulfone (exisulind), an antineoplastic agent that inhibits growth and induces apoptosis in solid tumors. In colon cancer cells, the antineoplastic effects of exisulind have been attributed, in part, to induction of cyclic guanosine 3',5'-monophosphate (cGMP) signaling through inhibition of cGMP-specific phosphodiesterases, which elevates intracellular cGMP, and novel expression of cGMP-dependent protein kinase (PKG) Ibeta, the presumed downstream effector mediating apoptosis. Here, inhibition of proliferation and induction of cell death by exisulind was dissociated from cGMP signaling in human colon cancer cells. Accumulation of intracellular cGMP produced by an exogenous cell-permeant analogue of cGMP or a potent agonist of guanylyl cyclase C yielded cytostasis without cell death. Surprisingly, the antiproliferative effects of induced cGMP accumulation were paradoxically less than additive, rather than synergistic, when combined with exisulind. Further, although exisulind induced expression of PKG Ibeta, it did not elevate intracellular cGMP and its efficacy was not altered by inhibition or activation of PKG I. Rather, PKG I induced by exisulind may mediate desensitization of cytostasis induced by cGMP. Thus, cytotoxic effects of exisulind are independent of cGMP signaling in human colon cancer cells. Moreover, combination therapies, including exisulind and agents that induce cGMP signaling, may require careful evaluation in patients with colon cancer.

Non-steroidal anti-inflammatory agents, tolmetin and sulindac, inhibit liver tryptophan 2,3-dioxygenase activity and alter brain neurotransmitter levels

Hepatic tryptophan 2,3-dioxygenase (TDO) is one of the rate-limiting enzymes in tryptophan catabolism and plays an important role in regulating the physiological flux of tryptophan into relevant metabolic pathways. In this study, we determined the effect of the non-steroidal anti-inflammatory agents, tolmetin and sulindac, on rat liver TDO activity and the subsequent changes in the hippocampal and striatal neurotransmitter levels. The amount of melatonin produced by the pineal gland was also measured using high performance liquid chromatography (HPLC). Treatment of rats with tolmetin or sulindac (5 mg/kg/bd for 5 days) significantly inhibited liver TDO activity. The results show that whilst tolmetin and sulindac increase serotonin levels in the hippocampus, these agents also significantly reduce dopamine levels in the striatum. Tolmetin, but not sulindac, increased the amount of melatonin produced by the pineal gland. The results of this study suggest that whilst tolmetin and sulindac may be beneficial for patients suffering from depression, these agents also have the potential to induce adverse effects in patients suffering with neurological disorders such as Parkinson's disease.

Combination of Tumor Necrosis Factor-α with Sulindac in Human Carcinoma Cellsin Vivo

Transcription factor NF-kappaB plays a pivotal role in cancer cells in the resistance to apoptosis, since NF-kappaB is frequently activated in many primary carcinoma cells. Indeed, several NF-kappaB inhibitors are found to be promising anti-cancer agents. However, some anti-cancer agents activate NF-kappaB signals and may reduce their potential, including tumor necrosis factor (TNF)-alpha. Recently, the nonsteroidal anti-inflammatory drug (NSAID) sulindac and its metabolites have been shown to inhibit the NF-kappaB-mediated survival signals through inhibition of IKK-beta by their direct interaction. We thus investigate whether sulindac and its metabolite can augment TNF-alpha-mediated apoptosis in human carcinoma cells and be applicable for in vivo clinical usage. We here demonstrate that sulindac inhibited TNF-alpha-mediated NF-kappaB activation and greatly enhanced TNF-alpha-induced apoptosis in human gastric MKN45 and cervical HeLa carcinoma cell lines. The in vivo tumor growth of MKN45 cells was most strongly inhibited by a combination of TNF-alpha with sulindac compared with TNF-alpha or sulindac alone. Moreover, we demonstrate that sulindac sulfide further augmented TNF-alpha-mediated apoptosis. Our data strongly suggest that combination therapy of TNF-alpha with sulindac and its metabolites may sensitize cancer cells to TNF-alpha and augment its pro-apoptotic potential. Therefore, in combination with sulindac or its metabolites, TNF-alpha may become a potentially useful anti-cancer agent to suppress tumor.

Delayed mechanism for induction of gamma-glutamylcysteine synthetase heavy subunit mRNA stability by oxidative stress involving p38 mitogen-activated protein kinase signaling

Expression of the gamma-glutamylcysteine synthetase heavy subunit (gamma-GCSh), which encodes the rate-limiting enzymes for glutathione biosynthesis, is regulated by many cytotoxic agents. Moreover, gamma-GCSh mRNA expression is elevated in colorectal cancer, but how gamma-GCSh expression is regulated is not completely understood. By using actinomycin D, which inhibits new RNA synthesis, we showed that treatment of human colorectal cancer cells with the prooxidant sulindac increased the half-life of gamma-GCSh mRNA. By using a tetracycline-regulated gamma-GCSh mRNA assay system, we systematically dissected the cis-acting sequence and trans-acting factors that regulate the stability of gamma-GCSh by cytotoxic prooxidants. We demonstrated that a HuR recognition sequence, AUUUA, in the 3'-untranslated region is responsible for the decay of gamma-GCSh mRNA. Oxidative stress enhanced cytoplasmic content of HuR. Overexpression of HuR by transfection stabilized gamma-GCSh mRNA, whereas overexpression of a dominant-negative HuR mutant suppressed the induced stability. Furthermore, prooxidant-induced gamma-GCSh mRNA stabilization and HuR binding were blocked by p38 mitogen-activated protein kinase inhibitors. We provide the first evidence that reduction-oxidation regulation of gamma-GCSh expression, itself a reduction-oxidation sensor and regulator, is mediated at least in part by the p38 mitogen-activated protein kinase signaling through the HuR RNA-binding protein.

Methylation in the p21WAF1/cip1 promoter of Apc+/-, p21+/- mice and lack of response to sulindac

P21WAF1/cip1 plays a critical role in regulating intestinal cell proliferation, maturation and tumorigenesis. Our previous work demonstrated that inactivation of a single p21 allele in Apc1638+/- mice was sufficient to accelerate Apc-initiated tumor formation, and that inactivation of only one p21 allele was also sufficient to abrogate duodenal tumor inhibition by sulindac, a nonsteroidal anti-inflammatory drug. To dissect the role of p21 in sulindac inhibition of intestinal tumor development in Apc1638+/- mice, we quantified p21 expression from Apc+/-, p21+/+, +/- or -/- mice fed sulindac. In Apc+/-, p21 wild-type mice fed the sulindac supplemental diet, both p21 mRNA and protein were significantly increased in the flat mucosa and tumors of the duodenum. However, p21 was not induced by sulindac in the duodenal flat mucosa and tumors of Apc+/- mice in which one or both p21 alleles had been inactivated. Further investigation revealed that the cytosine residues in a CpG cluster in the promoter region of the mouse p21 gene displayed hypermethylation in the Apc+/-, p21+/- mice. This suggested that although the p21+/- mice retained a wild-type allele, this allele was functionally modulated by hypermethylation, and that the inability of sulindac to inhibit tumor formation in Apc+/-, p21+/- mice is likely due to the inability to induce expression of the wild-type, but differentially methylated, p21 allele.

Selective inhibitors of MEK1/ERK44/42 and p38 mitogen-activated protein kinases potentiate apoptosis induction by sulindac sulfide in human colon carcinoma cells

The nonsteroidal anti-inflammatory drug (NSAID) sulindac prevents experimental colon cancer and can regress precancerous polyps in humans. Sulindac sulfide inhibits cyclooxygenase (COX)-mediated prostaglandin synthesis and retards the growth of cultured colon cell lines primarily by inducing apoptosis. Given the known role of mitogen-activated protein kinase (MAPK) in signal transduction and the regulation of cell survival and death, we determined the effect of sulindac sulfide on MAPK activation, COX-2 expression, and apoptosis induction in HCA-7 human colon cancer cells. Sulindac sulfide treatment was associated with activation of ERKp44/42 and p38 MAPK in a dosage- and time-dependent manner, and also activated upstream MEK. Similar results were seen in HCT-15 cells and also with the selective COX-2 inhibitor NS398. ERKp44/42 and p38 activation were accompanied by an induction of COX-2 protein expression. Selective inhibitors of sulindac sulfide-induced ERKp44/42 (PD98059) and p38 MAPK (SB203580) activation also suppressed the induction of COX-2 by this NSAID. Furthermore, both MAPK inhibitors significantly augmented sulindac sulfide-induced apoptosis, as did suppression of constitutive COX-2 using antisense oligonucleotides. In conclusion, MEK/ERK and p38 MAPK activation mediate COX-2 induction by sulindac sulfide. Selective inhibitors of these MAPKs potentiate apoptosis induction by this NSAID, suggesting a novel strategy for the prevention or treatment of colorectal cancer.

Polyamines reverse non-steroidal anti-inflammatory drug-induced toxicity in human colorectal cancer cells

Naproxen, sulindac and salicylate, three NSAIDs (non-steroidal anti-inflammatory drugs), were cytotoxic to human colorectal cancer cells in culture. Toxicity was accompanied by significant depletion of intracellular polyamine content. Inhibition of ornithine decarboxylase (the first enzyme of the polyamine biosynthetic pathway), induction of polyamine oxidase and spermidine/spermine N(1)-acetyltransferase (the enzymes responsible for polyamine catabolism) and induction of polyamine export all contributed to the decreased intracellular polyamine content. Morphological examination of the cells showed typical signs of apoptosis, and this was confirmed by DNA fragmentation and measurement of caspase-3-like activity. Re-addition of spermidine to the cells partially prevented apoptosis and recovered the cell number. Thus polyamines appear to be an integral part of the signalling pathway mediating NSAID toxicity in human colorectal cancer cells, and may therefore also be important in cancer chemoprevention in humans.

Exisulind Cell Pathways

Cell Pathways has developed exisulind (Aptosyn), an oral apoptosis modulator and cGMP phosphodiesterase inhibitor, for the potential treatment of several oncologic indications including precancerous adenomatous polyposis coli (APC), also known as familial adenomatous polyposis (FAP), precancerous sporadic colonic polyps, cervical dysplasia and the prevention of tumor recurrence in prostate and breast cancer. An NDA filing for the treatment of precancerous APC, for which the US FDA designated exisulind a Fast Track product in July 1998, was initially expected in March 1999 [291313]. However, in January of the same year the company stated that it anticipated a delay in the NDA filing. The decision was based on unsatisfactory phase III data [308912], [313124]. In June 1999, the company completed analysis of the phase III trial data [328000] and the NDA was submitted in August 1999. An NDA was accepted for review by the FDA in October 1999 for the treatment of APC [328000], [338007], [344721], after data from three additional trials were submitted to the FDA in support of the NDA. At this time phase II/III trials were also ongoing for prostate and breast cancer recurrence [287250], [326795]. Approval for the indication of FAP had been expected by the end of 2000 [365737] but in September 2000 the FDA completed its initial review and advised Cell Pathways that exisulind will not be approved at this time. Cell Pathways has received a 'non-approvable' letter and intends to advise the FDA of its intent to amend the NDA and to request a meeting to address the deficiencies in the NDA [383249], [383560]. The first of the three additional trials submitted to the FDA in October 1999 was a 6-month, open-label trial involving 48 of the patients who completed a phase II/III study of exisulind in early 1999. After 6 months of treatment with exisulind, 25 patients who had previously been taking placebo experienced a 50% reduction in polyp formation. The patients continuing treatment with exisulind exhibited a further 50% reduction from their already reduced rate of polyp formation [344991]. The second study was an extension study of 11 patients who participated in a 6-month, open-label, phase I/II, dose-ranging, safety and efficacy trial. As of October 1999, these patients were still on therapy and had been receiving exisulind for between 36 and 50 months. They had all experienced statistically significant reductions in polyp formation rates [344991]. The third study was a double-blind, placebo-controlled safety study of 26 patients. All patients exhibited a trend of reduced new polyp formation when compared to placebo. Exisulind was generally well-tolerated by all patients during the course of the studies [344991]. In July 2000, Cell Pathways signed a marketing and distribution agreement for Canada with Paladin Labs, allowing Paladin exclusive rights to commercialize exisulind within Canada [376072]. Also in July 2000, Cell Pathways announced that patents covering methods of identifying compounds that selectively stimulate apoptosis have been allowed in Europe and Japan. The patents describe the mechanism of action of Cell Pathways' SAANDs, including exisulind, and use of that knowledge in screening for new drugs [374888]. In January 1999, the company received US-05858694 covering the mechanism of action of exisulind [311504].

Immunochemical identification of mouse hepatic protein adducts derived from the nonsteroidal anti-inflammatory drugs diclofenac, sulindac, and ibuprofen

Reactive metabolite-modified hepatic protein adducts have been proposed to play important roles in the mechanism(s) of hepatotoxicity of nonsteroidal anti-inflammatory drugs (NSAIDs). In the present study, immunochemical techniques have been used to compare the patterns of drug-protein adducts expressed in livers of mice given single doses of one or other of three different NSAIDs. These were diclofenac and sulindac, which are widely used but potentially hepatotoxic drugs, and ibuprofen, which is considered to be nonhepatotoxic. Specific polyclonal antisera were produced by immunization of rabbits with conjugates prepared by coupling each of the NSAIDs to the carrier protein keyhole limpet hemocyanin. Immunoblotting studies revealed dose-dependent formation of major 110 kDa polypeptide adducts in livers from mice sacrificed 6 h after administration of single doses of either diclofenac (0-300 mg/kg) or sulindac (0-100 mg/kg). Lower levels of several other adducts, of 140 and 200 kDa, were also expressed in livers from these animals. In contrast, livers from mice treated with ibuprofen (0-200 mg/kg) predominantly expressed a 60 kDa adduct and only relatively low levels of a 110 kDa adduct. The various adducts were shown by differential centrifugation to be concentrated in the nuclear fraction of liver homogenates. Those derived from diclofenac and sulindac were further localized, by Percoll density gradient centrifugation, to a subfraction which contained a high activity of the bile canalicular marker enzyme alkaline phosphatase. This suggests that they are concentrated in the bile canalicular domain of hepatocytes. The different patterns of adduct formation raise the possibility that formation of certain NSAID protein adducts, particularly 110 kDa adducts, has toxicological significance.

The anti-proliferative effect of sulindac and sulindac sulfide on HT-29 colon cancer cells: alterations in tumor suppressor and cell cycle-regulatory proteins

Nonsteroidal anti-inflammatory drugs lower the incidence of and mortality from colon cancer. Sulindac reduces the number and size of polyps in patients with familial adenomatous polyposis. We have shown that sulindac and sulindac sulfide reversibly reduce the proliferation rate of HT-29 colon cancer cells, alter their morphology, induce them to accumulate in the G0/G1 phase of the cell cycle, and sulindac sulfide induces cell death by apoptosis. In this study we confirmed that sulindac and sulindac sulfide prevent HT-29 cells from progressing from the G0/G1 into the S phase. This block in cell cycle progression is associated with an initial rise, then an abrupt decrease in the levels of p34cdc2 protein. Sulindac and sulindac sulfide decrease the levels of mitotic cyclins, induce the levels of p21WAF-1/cip1, and reduce the total levels of pRB, with a relative increase in the amount of the underphosphorylated form of pRB in a time- and concentration-dependent manner. In addition, these compounds reduce the levels of mutant p53. These responses are not associated with intestinal cell differentiation and occur independent of the ability of these compounds to induce apoptosis. We conclude that sulindac and sulindac sulfide reduce the levels of major components of the molecular cell cycle machinery and alter the levels of several tumor suppressor proteins in a manner consistent with cell cycle quiescence. These mechanisms may be operative in vivo to account, in part, for the anti-neoplastic effects of these compounds.

Effects of NSAIDs on NNK-induced pulmonary and gastric tumorigenesis in A/J mice

Non-steroidal anti-inflammatory drugs (NS-AIDs) are among the most widely prescribed drugs. In this study, we compared the efficacies of four NSAIDs to inhibit lung tumorigenesis in A/J mice. The tobacco-specific carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), was given in drinking water between week 0 and week +7. Groups of 25 mice were fed sulindac (123 mg/kg diet), ibuprofen (263 mg/kg), piroxicam (25 mg/kg) or naproxen (230 mg/kg) in AIN-76A diet from week -2 to the end of the bioassay (week +23). Sulindac was the most effective inhibitor and reduced lung tumor multiplicity by 51%. Ibuprofen and piroxicam reduced lung multiplicity by 38% and 30%, respectively. Naproxen demonstrated no inhibitory capacity. Forestomach tumor multiplicity and incidence were both reduced by sulindac and ibuprofen. Sulindac administered from week -2 to week +7 was less effective (28% inhibition) than when given throughout the bioassay. Sulindac induced more intestinal adhesions than any other NSAID and was directly related to the cumulative dose of sulindac. These results show that chemoprevention of lung tumorigenesis by NSAIDs is not limited to sulindac although it is the most effective.

Efficacy and safety of nonsteroidal anti-inflammatory drugs in the therapy of diabetic neuropathy

A study comparing ibuprofen (600 mg four times a day) vs sulindac (200 mg twice a day), and a placebo in the treatment of painful diabetic peripheral neuropathy was conducted in 18 male outpatients. Discomfort was characterized and rated with a subjective neuropathy score. The response to both ibuprofen and sulindac was better than it was to placebo in the entire group. There were no changes in glucose control or renal function. Further studies are necessary to evaluate the significance of aldose reductase-inhibitor properties of nonsteroidal anti-inflammatory drugs and to select the "best" one of these drugs for the treatment of diabetic neuropathy.

The effects of sulindac and its metabolites on acute stress-induced gastric ulcers in rats

Rats were given a single intragastric administration of the prodrug sulindac (4.0 mg/kg) or its sulfide (1.0, 2.0, 4.0, or 8.0 mg/kg) or sulfone (1.0, 2.0, 4.0, or 8.0 mg/kg) metabolites and were then subjected to acute stress in the form of immobilization for 3 hr in a cold environment. Control rats received an equal volume of propylene glycol vehicle or nothing po. Other rats received 200 mg/kg acetylsalicylic acid (ASA) with or without stress, to compare the gastrointestinal effects of sulindac metabolites with those of a known non-steroidal anti-inflammatory agent. The sulfide metabolite exacerbated stress-induced gastric glandular ulcer incidence and severity in a dose-related manner relative to all groups except the ASA-stress group, which exhibited the greatest amount of gastric damage. The sulfone metabolite did not potentiate ulcer incidence or severity beyond control (stress only) levels at lower doses. However, at 4.0 and 8.0 mg/kg, the observed ulceration was greater than that seen in stressed but otherwise untreated animals. Sulindac, vehicle, and otherwise untreated rats exhibited a similar degree of stress-induced gastric damage. It appears that the prodrug does not significantly enhance stress-related gut disease, but that the active sulfide metabolite does. Although the clinical literature suggests that the sulfone metabolite is inactive, the present results suggest otherwise. While this metabolite did not, by itself, induce gastric damage at higher doses, sulfone did exacerbate stress ulcer formation. This is the only report of which we are aware, indicating a possible toxic effect of the sulfone metabolite.

Effects of sulindac and ibuprofen in patients with cirrhosis and ascites. An explanation for the renal-sparing effect of sulindac

Nonsteroidal antiinflammatory drugs impair renal function in susceptible patients with cirrhosis and ascites. A new antiinflammatory drug, sulindac, is reported not to affect renal function. To evaluate its renal-sparing mechanism, sulindac was administered for 5 days and ibuprofen for 1 day to 10 patients and paraaminohippurate and inulin clearances, serum and urine eicosanoids, and serum and urine sulindac metabolites were monitored. Ibuprofen reduced renal clearances in the 5 subjects with greatest sodium retention, whereas sulindac had no effect. Plasma concentration of the active sulfide metabolite was markedly increased in liver patients, and this concentration correlated with the inhibition of serum thromboxane (r = 0.75, p = 0.01). The percent inhibition of serum thromboxane with sulindac administration correlated with the inhibition of urinary eicosanoids (r = 0.68-0.81, all p less than 0.02). Ibuprofen was generally a more potent inhibitor of serum and urine eicosanoids. Thus, a major factor in the renal-sparing effect of sulindac appears to be its less potent inhibition of renal and extrarenal cyclooxygenase systems.

Sulindac hepatotoxicity: a case report and review

A 44 year old female, previously on propranolol, phenytoin and phenobarbital, developed hepatotoxicity while on sulindac and acetaminophen containing analgesic. A limited review of hepatotoxicity and drug interactions of sulindac is presented. The possible mechanism of hepatotoxicity and its treatment is suggested.

A multi-centre, double-blind randomized study to assess the efficacy and tolerance of sulindac versus placebo in the symptomatic treatment of patients with upper respiratory tract infection

A multi-centre, double-blind, randomized, placebo-controlled study was carried out to compare the efficacy and tolerance of sulindac (200 mg twice daily) with placebo in the symptomatic treatment for 7 days of 312 adult patients with upper respiratory tract infection. Investigators and patients rated sulindac superior to placebo in the overall evaluations of response to treatment, but the differences were not significant. In general, patients treated with sulindac had greater mean decreases from baseline scores for individual signs and symptoms than did placebo patients. Fever was relieved better by sulindac than by placebo. The mean decrease from baseline pain scores was also greater in the sulindac group. More patients receiving sulindac reported clinical adverse experiences compared with those on placebo, the most common adverse experiences reported being in the digestive system.