Pharmacologic evaluation of sulfasalazine, FTY720, and anti-IL-12/23p40 in a TNBS-induced Crohn's disease model.

BACKGROUND: 2,4,6-Trinitrobenzenesulfonic acid (TNBS)-induced colitis has been used as an inflammatory bowel disease (IBD), Crohn's disease (CD), preclinical model. However, published data on pharmacologic and therapeutic efficacy testing of this model are limited. FTY720 inhibits lymphoid cell trafficking in inflammatory conditions and is of interest to treat IBD. AIM: We investigated the pharmacologic therapeutic efficacy of sulfasalazine, FTY720, and anti-IL-12/23p40, in a TNBS CD model. METHODS: Female, 7-week-old, BALB/c mice were given sulfasalazine orally (PO) and intraperitoneally (IP) at 10 mg/kg, FTY720 at 3 mg/kg PO, and mouse anti-IL-12/23p40 at 25 mg/kg IP. Vehicle groups given PO either phosphate-buffered saline/water or 40% ethanol served as controls. Pharmacologic efficacy was assessed using body weight loss, clinical scores of diarrhea and intestinal gross pathology, and colon weight parameters. RESULTS: Sulfasalazine and FTY720 treatment did not prevent body weight loss or reduce clinical scores of diarrhea or intestinal gross pathology, when compared with vehicle treatment. However, anti-IL-12/23p40 treatment showed significant efficacy by preventing body weight loss, reducing clinical scores of diarrhea, and reducing intestinal gross pathologic lesions, when compared with vehicle-treated animals. Sulfasalazine, anti-IL-12/23p40, and FTY720 were not effective in reducing colon weight. CONCLUSION: With the exception of anti-IL-12/23p40, sulfasalazine, and FTY720 did not demonstrate full pharmacologic efficacy in our TNBS CD model.

Geldanamycin-induced PCNA degradation in isolated Hsp90 complex from cancer cells.

Hsp90 is a molecular chaperone involved in the folding and proteolytic turnover of many regulatory proteins associated with it. Some of the Hsp90 client proteins are known to be involved in tumorigenesis. An Hsp90-specific inhibitor, geldanamycin, is shown to bind to the ATP binding site of the chaperone to induce degradation of many client proteins, and results in antitumor activities. However, the mechanism of geldanamycin-induced client protein degradation is not fully understood. A large-scale immunoaffinity purification with anti-Hsp90 antibodies identified many Hsp90 client proteins from colon cancer cell line, HCT-116. One of the identified proteins, PCNA, was confirmed to be associated with Hsp90 in two additional cancer cell lines. After geldanamycin treatment, both PCNA and Hsp90 were shown to be degraded. More interestingly, this study demonstrated that in two different cancer cell lines, the degradation occurred in the isolated Hsp90 complex in vitro. This result indicated that the components responsible for the PCNA degradation are also associated with Hsp90. This finding provided a new mechanism for the Hsp90-mediated protein degradation induced by Hsp90-specific inhibitors.

Inhibition of cyclooxygenase-2 by celecoxib reverses tumor-induced wasting.

There have been a number of reports suggesting inhibition of prostaglandin production may impact tumor-mediated wasting and levels of associated humoral factors such as hypercalcemia. These reductions were achieved using traditional nonsteroidal anti-inflammatory drugs (NSAIDs), which are often contraindicated in cancer patients. This is especially true during chemotherapeutic regimens due to concerns of bleeding from gastrointestinal and hematopoietic toxicities associated with inhibition of the housekeeping cyclooxygenase enzyme COX-1. Here, we report that celecoxib, one of the new class of selective COX-2 inhibitors, has the potential to reverse tumor-mediated wasting and associated humoral factors such as interleukin (IL)-6 and hypercalcemia in preclinical models of cachexia. Tumor bearing mice in late stage cachexia regained weight within days of the start of celecoxib treatment. Two models were tested. The first was the Colon 26 (Col26) syngeneic murine model that induces high levels of circulating IL-6 and hypercalcemia. The second was the human head and neck 1483 HNSCC xenograft model, which is less inflammatory and produces less prostaglandin than Col26. Despite the observation that no significant impact on tumor growth was observed between vehicle and celecoxib-treated animals over the course of the studies, celecoxib rapidly reversed weight loss in both cachectic models. With the added safety of celecoxib over traditional NSAIDs, these results suggest a possible therapeutic use for celecoxib for treating tumor-mediated wasting.

Synergy between celecoxib and radiotherapy results from inhibition of cyclooxygenase-2-derived prostaglandin E2, a survival factor for tumor and associated vasculature.

Previous work has demonstrated that selective cyclooxygenase-2 (COX-2) inhibitors can act synergistically with radiotherapy to improve tumor debulking and control in preclinical models. The underlying mechanism of this remarkable activity has not yet been determined. Here, we report that radiation can elevate intratumoral levels of COX-2 protein and its products, particularly prostaglandin E(2) (PGE(2)). Furthermore, inhibition of COX-2 activity or neutralization of PGE(2) activity enhances radiotherapy even in tumors where COX-2 expression is restricted to the tumor neovasculature. Direct assessment of vascular function by direct contrast enhancement-magnetic resonance imaging showed that the combination of radiation and celecoxib lead to enhanced vascular permeability. These observations suggest that an important mechanism of celecoxib-induced radiosensitization involves inhibition of COX-2-derived PGE(2), thus removing a survival factor for the tumor and its vasculature.

Chiral N,N-disubstituted trifluoro-3-amino-2-propanols are potent inhibitors of cholesteryl ester transfer protein.

A novel series of substituted N-benzyl-N-phenyl-trifluoro-3-amino-2-propanols are described that reversibly inhibit cholesteryl ester transfer protein (CETP). Starting with screening lead 22, various structural features were explored with respect to inhibition of the CETP-mediated transfer of [(3)H]cholesterol from high-density cholesterol donor particles to low-density cholesterol acceptor particles. The free hydroxyl group of the propanol was required for high potency, since acylation or alkylation reduced activity. High inhibitory potency was also associated with 3-ether moieties in the aniline ring, and the highest potencies were exhibited by 3-phenoxyaniline analogues. Activity was substantially reduced by oxidation or substitution in the methylene of the benzylic group, implying that the benzyl ring orientation was important for activity. In the benzylic group, substitution at the 3-position was preferred over either the 2- or the 4-positions. Highest potencies were observed with inhibitors in which the 3-benzylic substituent had the potential to adopt an out of plane orientation with respect to the phenyl ring. The best 3-benzylic substituents were OCF(2)CF(2)H (42, IC(50) 0.14 microM in buffer, 5.6 microM in human serum), cyclopentyl (39), 3-iso-propoxy (27), SCF(3) (67), and C(CF(3))(2)OH (36). Separation of 42 into its enantiomers unexpectedly showed that the minor R(+) enantiomer 1a was 40-fold more potent (IC(50) 0.02 microM in buffer, 0.6 microM in human serum) than the major S(-) enantiomer 1b, demonstrating that the R-chirality at the propanol 2-position is key to high potency in this series. The R(+) enantiomer 1a represents the first reported acyclic CETP inhibitor with submicromolar potency in plasma. A chiral synthesis of 1a is reported.