Sulindac, a non-steroidal anti-inflammatory prodrug, is metabolized into pharmacologically active sulfide and sulfone derivatives. Sulindac sulfide, but not sulindac sulfone, inhibits cyclooxygenase (COX) enzyme activities, yet both derivatives have growth inhibitory effects on colon cancer cells. Microarray analysis was used to detect COX-independent effects of sulindac on gene expression in human colorectal cells. Spermidine/spermine N 1 -acetyltransferase (SSAT) gene, which encodes a polyamine catabolic enzyme, was induced by clinically relevant sulindac sulfone concentrations. Northern blots confirmed increased SSAT RNA levels in these colon cancer cells. Deletion analysis and mutational studies were done to map the sulindac sulfone-dependent response sequences in the SSAT 5-flanking sequences. This led us to the identification of two peroxisome proliferator-activated receptor (PPAR) response elements (PPREs) in the SSAT gene. PPRE-2, at ؉48 bases relative to the transcription start site, is required for the induction of SSAT by sulindac sulfone and is specifically bound by PPAR␥ in the Caco-2 cells as shown by transfection and gel shift experiments. PPRE-1, at ؊323 bases relative to the start site, is not required for the induction of SSAT by sulindac sulfone but can be bound by both PPAR␦ and PPAR␥. Sulindac sulfone reduced cellular polyamine contents in the absence but not in the presence of verapamil, an inhibitor of the export of monoacetyl diamines, inhibited cell proliferation and induced apoptosis. The induced apoptosis could be partially rescued by exogenous putrescine. These data suggest that apoptosis induced by sulindac sulfone is mediated, in part, by the COX-independent, PPAR-dependent transcriptional activation of SSAT, leading to reduced tissue polyamine contents in human colon cancer cells.Numerous epidemiological, animal, and in vitro studies indicate that non-steroidal anti-inflammatory drugs (NSAIDs) 1 have antitumorigenic activities against colorectal cancer (1-4).Sulindac, an NSAID, inhibits colorectal carcinogenesis in rodent models (5, 6) and causes regression of adenomas (7,8) in patients with familial adenomatous polyposis coli. NSAIDs work by inhibiting cyclooxygenases (COXs) of which there are at least two distinct forms, COX-1 and COX-2. Physiologically sulindac is metabolized into sulfide-or sulfonecontaining derivatives. The sulfide derivative inhibits colon carcinogenesis by inhibiting COX-1 and COX-2 enzyme activities (9). However, sulindac sulfone also inhibits chemical carcinogenesis in rodents but by a mechanism that cannot be explained solely by the inhibition of prostaglandin synthesis (10, 11), yet both derivatives inhibit growth and induce apoptosis in a variety of human tumor-derived cell lines (12, 13). Sulindac sulfone, at clinically relevant concentrations ranging from 35 M (in humans) to around 150 M (in mice), has been shown to have chemopreventive effects on colon cancer (12, 14 -16).One of the COX-independent mechanisms of action of sulindac and its metabolites...

The colorectal mucosa of pre-symptomatic individuals with familial adenomatous polyposis (FAP) contains elevated levels of the proliferation-associated polyamines. The Min mouse, like humans with FAP, expresses an abnormal genotype for the APC tumor suppressor gene. In order to determine how APC mutation influences intestinal tissue polyamine content, we measured steady-state RNA levels of ornithine decarboxylase (ODC), the first enzyme in polyamine synthesis, antizyme (AZ), a protein which negatively regulates ODC, and the spermidine/spermine N(1)-acetyltransferase (SSAT), the first enzyme in polyamine catabolism. RNA content was increased 6- to 8-fold in both the small intestine and colon for ODC, decreased significantly in the small intestine but not the colon for AZ and was not statistically different in either intestinal tissue for SSAT in Min mice compared with normal littermates. Consistent with the changes in ODC and AZ gene expression, small intestinal, but not colonic, polyamine content was elevated in Min mice compared with normal littermates. Treatment of Min mice with the specific ODC inhibitor difluoromethylornithine (DFMO) suppressed small intestinal, but not colonic, polyamine content and tumor number. These data indicate that small intestinal tissue polyamine content is elevated in Min mice by a mechanism involving APC-dependent changes in ODC and AZ RNA. Further, ODC enzyme activity, which is influenced by both ODC and AZ RNA levels and inhibited by DFMO, is consequential for small intestinal tumorigenesis in this model. In the FAP population, DFMO may be of value in the chemoprevention of small intestinal adenocarcinoma that remains a risk following colectomy.

The canine transmissible venereal tumor (CTVT) is a cancer lineage that arose several millennia ago and survives by “metastasizing” between hosts through cell transfer. The somatic mutations in this cancer record its phylogeography and evolutionary history. We constructed a time-resolved phylogeny from 546 CTVT exomes and describe the lineage’s worldwide expansion. Examining variation in mutational exposure, we identify a highly context-specific mutational process that operated early in the cancer’s evolution but subsequently vanished, correlate ultraviolet-light mutagenesis with tumor latitude, and describe tumors with heritable hyperactivity of an endogenous mutational process. CTVT displays little evidence of ongoing positive selection, and negative selection is detectable only in essential genes. We illustrate how long-lived clonal organisms capture changing mutagenic environments, and reveal that neutral genetic drift is the dominant feature of long-term cancer evolution.

Elevated polyamine and nitric oxide levels (both derived from arginine) promote tumorigenesis, whereas non-steroidal anti-inflammatory drugs (NSAIDs) inhibit colorectal cancer (CRC) incidence in experimental and epidemiologic studies. We investigated dietary arginine-induced intestinal tumorigenesis and NSAID-inhibitory effects in Apc Min/+ mice differentially expressing nitric oxide synthase-2 (Nos2). We also studied effects of estimated arginine exposures through meat consumption on tumor characteristics and survival in human CRC cases. Dietary arginine increased high-grade colon adenoma incidence in Apc Min/+ Nos2 +/+ mice, but not in Nos2 knockout mice. Additionally, celecoxib suppressed intestinal steady state ornithine decarboxylase RNA levels (p < 0.001), induced steady state spermidine/spermine N 1 -acetyltransferase RNA levels (p 5 0.002), decreased putrescine levels (p 5 0.04) and decreased tumor number in the small intestines of Apc Min/1 Nos2 1/1 mice (p 5 0.0003). Five hundred and eleven cases from our NCI-supported CRC gene-environment study were analyzed based on self-reported meat (as a surrogate for arginine) consumption. Familial CRC cases (n 5 144) in the highest meat consumption quartile (Q4) had no statistically significant differences in tumor grade compared to cases in Q1-Q3 (p 5 0.32); however, they were observed to have decreased overall survival (OS) (10-year OS 5 42% vs. 65%; p 5 0.017), and increased risk of death in an adjusted analysis (hazards ratio [HR] 5 2.24; p 5 0.007). No differences in tumor grade, OS or adjusted HR were observed for sporadic CRC cases (n 5 367) based on meat consumption. Our results suggest important roles for arginine and meat consumption in CRC pathogenesis, and have implications for CRC prevention. ' 2006 Wiley-Liss, Inc.Key words: arginine; polyamines; celecoxib; meat; familial colorectal cancer; colon cancer; rectal cancer; survival Extensive epidemiologic studies have investigated the relationship between meat consumption and colorectal cancer (CRC) risk. Meat consumption was shown not to be associated with CRC in a large meta-analysis of 34 case-control and 14 cohort studies published during 1973-1999, while red meat and processed meat intake were associated with moderate increases in CRC risk. 1 A large cohort study has recently confirmed an increased risk of developing CRC associated with consumption of red meat and processed meats, and demonstrated a protective effect for fish and poultry. 2 While many epidemiologic studies have assessed the risk of meat consumption on developing CRC, 1,3 there is a paucity of data addressing the risk of meat consumption on outcomes in CRC patients. Meat consumption is the major source of dietary arginine in humans, with high quantities of arginine found not only in red meat but also in pork, fish and chicken. 4 Meat and meat products accounted for 37-38% of total daily arginine in two European studies, where subjects were estimated to have similar daily arginine intake to U.S. men (i.e. 4.2-5.0 g/day). 5,6 In cell...