Rectal epithelial apoptosis in familial adenomatous polyposis patients treated with sulindac

Combination Chemotherapy of Multidrug-resistant Early-stage Colon Cancer: Determining Optimal Dose Schedules by High-performance Computer Simulation

The goal of this project was to utilize mechanistic simulation to demonstrate a methodology that could determine drug combination dose schedules and dose intensities that would be most effective in eliminating multidrug resistant cancer cells in early-stage colon cancer. An agent-based model of cell dynamics in human colon crypts was calibrated using measurements of human biopsy specimens. Mutant cancer cells were simulated as cells that were resistant to each of two drugs when the drugs were used separately. The drugs, 5-flurouracil and sulindac, have different mechanisms of action. An artificial neural network was used to generate nearly two hundred thousand two-drug dose schedules. A high-performance computer simulated each dose schedule as a in silico clinical trial and evaluated each dose schedule for its efficiency to cure (eliminate) multidrug resistant cancer cells and its toxicity to the host, as indicated by continued crypt function. Among the dose schedules that were generated, 2430 dose schedules were found to cure all multidrug resistant mutants in each of the 50 simulated trials and retained colon crypt function. One dose schedule was optimal; it eliminated multidrug resistant cancer cells with the minimum toxicity and had a time schedule that would be practical for implementation in the clinic. These results demonstrate a procedure to identify which combination drug dose schedules could be most effective in eliminating drug resistant cancer cells. This was accomplished using a calibrated agent-based model of a human tissue, and a high-performance computer simulation of clinical trials.

Aldehyde Dehydrogenase 2 Family Member (ALDH2) Is a Therapeutic Index for Oxaliplatin Response on Colorectal Cancer Therapy with Dysfunction p53

Oxaliplatin resistance is a major issue in the treatment of p53 mutant colorectal cancer (CRC). Finding the specific biomarkers would improve therapeutic efficacy of patients with CRC. In order to figure out the biomarker for CRC patients with mutant p53 access oxaliplatin, a Gene Expression Omnibus dataset (GSE42387) was used to determine differentially expressed genes (DEGs). The Search Tool for the Retrieval of Interacting Genes (STRING) and Cytoscape software were used to predict protein-protein interactions. The Database for Annotation, Visualization, and Integrated Discovery online tool was used to group the DEGs into their common pathways. 138 DEGs were identified with 46 upregulated and 92 downregulated. In the PPI networks, 7 of the upregulated genes and 13 of the downregulated genes were identified as hub genes (high degrees). Four hub genes, aldehyde dehydrogenase 2 family member (ALDH2), aldo-keto reductase family 1 member B1 (AKR1B1), aldo-keto reductase family 1 member B10 (AKR1B10), and monoglyceride lipase (MGLL) were enriched in the most significant pathway, glycerolipid metabolism. Further, we found that low expression of ALDH2 is correlated with poor overall survival and oxaliplatin resistance. Finally, we found that combined treatment with ALDH2 inhibitor and oxaliplatin will reduce the sensitivity to oxaliplatin in p53 mutant HT29 cells. In conclusion, we demonstrate that ALDH2 may be a biomarker for oxaliplatin resistance status in CRC patients and bring new insight into treatment strategy for p53 mutant CRC patients.

Field carcinogenesis for risk stratification of colorectal cancer

Colorectal cancer (CRC) is characterized by genetic-environmental interplay leading to diffuse changes in the entire colonic mucosa (field carcinogenesis or field of injury) and to a pro-neoplastic genetic/epigenetic/physiological milieu. The clinical consequences are increased risk of synchronous and metachronous neoplasia. Factors such as genetics, race, ethnicity, age, and socioeconomic status are thought to influence neoplasia development. Here, we explore the potential improvement to CRC screening through exploiting field carcinogenesis, with particular focus on racial disparities and chemoprevention strategies. Also, we discuss future directions for field carcinogenesis/risk stratification using molecular and novel biophotonic techniques for personalized CRC screening.

Prevention of Colon Cancer Recurrence From Minimal Residual Disease: Computer Optimized Dose Schedules of Intermittent Apoptotic Adjuvant Therapy

PURPOSE

Adjuvant chemotherapy is used after surgery for stages II and III colorectal cancer to reduce recurrence. Nevertheless, recurrence may occur years later with the emergence of initially undetected minimal residual disease (MRD). Attempts to reduce recurrence by increasing the dose intensity and increasing the time of adjuvant therapy have been limited by the adverse effects of the recommended cytotoxic agents. The goals of this study were to suggest an alternative to the recommended cytotoxic agents and to determine optimal adjuvant therapy dose schedules that would reduce the percentage of recurrence at 5 years while retaining colon crypt function.

METHODS

A total of 84,400 dose schedules with different duration, interval between doses, and intensity of treatment were simulated with a high-performance computer. Simulated treatments used the drug sulindac, which had previously been used in primary prevention. With appropriate dose schedules, it can induce apoptosis at the crypt lumen surface while retaining crypt function. We used a computer model of cell dynamics in colon crypts that had been calibrated with measurements of human biopsy specimens. Proliferating mutant cells were assumed to emerge from MRD within crypts. Simulated outcomes included the recurrence percentage at 5 years and the retention of crypt function.

RESULTS

Optimal dose schedules were determined for adjuvant treatment of MRD that reduced the percentage of recurrence at 5 years of stages I, II, and III colon cancer to zero.

CONCLUSION

A new adjuvant therapy for colon cancer based upon optimum dose schedules of intermittent apoptotic treatment may prevent the recurrence of colon cancer from MRD and avoid the adverse effects of cytotoxic treatments.

A small diversity library of α-methyl amide analogs of sulindac for probing anticancer structure-activity relationships

Non-steroidal anti-inflammatory drugs (NSAIDs) have a variety of potential indications that include management of pain and inflammation as well as chemoprevention and/or treatment of cancer. Furthermore, a specific form of ibuprofen, dexibuprofen or the S-(+) form, shows interesting neurological activities and has been proposed for the treatment of Alzheimer's disease. In a continuation of our work probing the anticancer activity of small sulindac libraries, we have prepared and screened a small diversity library of α-methyl substituted sulindac amides in the profen class. Several compounds of this series displayed promising activity compared with a lead sulindac analog.

Oxazole and thiazole analogs of sulindac for cancer prevention

Aim:

Experimental and epidemiological studies and clinical trials suggest that nonsteroidal anti-inflammatory drugs possess antitumor potential. Sulindac, a widely used nonsteroidal anti-inflammatory drug, can prevent adenomatous colorectal polyps and colon cancer, especially in patients with familial adenomatous polyposis. Sulindac sulfide amide (SSA) is an amide-linked sulindac sulfide analog that showed in vivo antitumor activity in a human colon tumor xenograft model.

Results/methodology:

A new analog series with heterocyclic rings such as oxazole or thiazole at the C-2 position of sulindac was prepared and screened against prostate, colon and breast cancer cell lines to probe the effect of these novel substitutions on the activity of sulindac analogs.

Conclusion:

In general, replacement of the amide function of SSA analogs had a negative impact on the cell lines tested. A small number of hits incorporating rigid oxazole or thiazole groups in the sulindac scaffold in place of the amide linkage show comparable activity to our lead agent SSA.

Amine Containing Analogs of Sulindac for Cancer Prevention

Background:

Sulindac belongs to the chemically diverse family of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) that effectively prevent adenomatous colorectal polyps and colon cancer, especially in patients with familial adenomatous polyposis. Sulindac sulfide amide (SSA), an amide analog of sulindac sulfide, shows insignificant COX-related activity and toxicity while enhancing anticancer activity in vitro and demonstrating in vivo xenograft activity.

Objective:

Develop structure-activity relationships in the sulindac amine series and identify analogs with promising anticancer activities.

Method:

A series of sulindac amine analogs were designed and synthesized and then further modified in a “libraries from libraries” approach to produce amide, sulfonamide and N,N-disubstituted sulindac amine sub-libraries. All analogs were screened against three cancer cell lines (prostate, colon and breast).

Results:

Several active compounds were identified viain vitro cancer cell line screening with the most potent compound (26) in the nanomolar range.

Conclusion:

Compound 26 and analogs showing the most potent inhibitory activity may be considered for further design and optimization efforts as anticancer hit scaffolds.

Screening and Development of New Inhibitors of FtsZ from M. Tuberculosis

A variety of commercial analogs and a newer series of Sulindac derivatives were screened for inhibition of M. tuberculosis (Mtb) in vitro and specifically as inhibitors of the essential mycobacterial tubulin homolog, FtsZ. Due to the ease of preparing diverse analogs and a favorable in vivo pharmacokinetic and toxicity profile of a representative analog, the Sulindac scaffold may be useful for further development against Mtb with respect to in vitro bacterial growth inhibition and selective activity for Mtb FtsZ versus mammalian tubulin. Further discovery efforts will require separating reported mammalian cell activity from both antibacterial activity and inhibition of Mtb FtsZ. Modeling studies suggest that these analogs bind in a specific region of the Mtb FtsZ polymer that differs from human tubulin and, in combination with a pharmacophore model presented herein, future hybrid analogs of the reported active molecules that more efficiently bind in this pocket may improve antibacterial activity while improving other drug characteristics.

NSAIDs inhibit tumorigenesis, but how?

Numerous epidemiologic studies have reported that the long-term use of nonsteroidal anti-inflammatory drugs (NSAID) is associated with a significant decrease in cancer incidence and delayed progression of malignant disease. The use of NSAIDs has also been linked with reduced risk from cancer-related mortality and distant metastasis. Certain prescription-strength NSAIDs, such as sulindac, have been shown to cause regression of precancerous lesions. Unfortunately, the extended use of NSAIDs for chemoprevention results in potentially fatal side effects related to their COX-inhibitory activity and suppression of prostaglandin synthesis. Although the basis for the tumor growth-inhibitory activity of NSAIDs likely involves multiple effects on tumor cells and their microenvironment, numerous investigators have concluded that the underlying mechanism is not completely explained by COX inhibition. It may therefore be possible to develop safer and more efficacious drugs by targeting such COX-independent mechanisms. NSAID derivatives or metabolites that lack COX-inhibitory activity, but retain or have improved anticancer activity, support this possibility. Experimental studies suggest that apoptosis induction and suppression of β-catenin-dependent transcription are important aspects of their antineoplastic activity. Studies show that the latter involves phosphodiesterase inhibition and the elevation of intracellular cyclic GMP levels. Here, we review the evidence for COX-independent mechanisms and discuss progress toward identifying alternative targets and developing NSAID derivatives that lack COX-inhibitory activity but have improved antineoplastic properties.

COX-Independent Mechanisms of Cancer Chemoprevention by Anti-Inflammatory Drugs

Epidemiological and clinical studies suggest that non-steroidal anti-inflammatory drugs (NSAIDs), including cyclooxygenase (COX)-2 selective inhibitors, reduce the risk of developing cancer. Experimental studies in human cancer cell lines and rodent models of carcinogenesis support these observations by providing strong evidence for the antineoplastic properties of NSAIDs. The involvement of COX-2 in tumorigenesis and its overexpression in various cancer tissues suggest that inhibition of COX-2 is responsible for the chemopreventive efficacy of these agents. However, the precise mechanisms by which NSAIDs exert their antiproliferative effects are still a matter of debate. Numerous other studies have shown that NSAIDs can act through COX-independent mechanisms. This review provides a detailed description of the major COX-independent molecular targets of NSAIDs and discusses how these targets may be involved in their anticancer effects. Toxicities resulting from COX inhibition and the suppression of prostaglandin synthesis preclude the long-term use of NSAIDs for cancer chemoprevention. Furthermore, chemopreventive efficacy is incomplete and treatment often leads to the development of resistance. Identification of alternative NSAID targets and elucidation of the biochemical processes by which they inhibit tumor growth could lead to the development of safer and more efficacious drugs for cancer chemoprevention.

The role of anti-inflammatory drugs in colorectal cancer

A large body of evidence indicates that genetic mutations, epigenetic changes, chronic inflammation, diet, and lifestyle are key risk factors for colorectal cancer (CRC). Prevention of CRC has long been considered a plausible approach for the population and individuals at high risk for developing this disease. A significant effort has been made in the development of novel drugs for both prevention and treatment over the past two decades. This review highlights recent advances in our understanding of the role of nonsteroidal anti-inflammatory drugs in CRC prevention and adjuvant treatment. Moreover, we focus on the molecular mechanisms underlying the antitumor effects of these drugs in CRC. The knowledge of how anti-inflammatory agents inhibit cancer formation and progression may provide a rationale for the development of more effective chemopreventive and chemotherapeutic agents with less toxicity.

Sulindac effects on inflammation and tumorigenesis in the intestine of mice with Apc and Mlh1 mutations

We have previously reported that sulindac, a non-steroidal anti-inflammatory drug, inhibited tumor formation in the small intestine but increased tumors in the colon of Apc(Min/+) mice, a model of human familial adenomatous polyposis. To further explore intestinal regional responses, we studied effects of sulindac on additional gene-targeted mouse models of human intestinal tumorigenesis; these were (i) Apc(1638N/+) mouse (chain termination mutation in exon 15 of the Apc gene); (ii) Mlh1(+/-) mouse (DNA mismatch repair deficiency, a mouse model of human hereditary non-polyposis colorectal cancer) and (iii) double-heterozygous Mlh1(+/-)Apc(1638N/+) mutant mouse. Mice were fed AIN-76A control diet with or without 0.02% sulindac for 6 months. Intestinal regional tumor incidence, multiplicity, volume and degree of inflammation were used as end points. The results showed the following: (i) sulindac inhibited tumor development in the small intestine of Apc(1638N/+) mice; (ii) in contrast, sulindac increased tumors in the small intestine of Mlh1 mutant mice, a neoplastic effect which persisted in heterozygous compound Mlh1(+/-)Apc(1638N/+) mutant mice; (iii) sulindac increased tumors in the cecum of all mice regardless of genetic background; (iv) sulindac decreased inflammation in the small intestine of Apc(1638N/+) mice, but it increased inflammation in the small intestine of Mlh1(+/-) mice and Mlh1(+/-)Apc(1638N/+) mice and (v) sulindac enhanced inflammation in the cecum of all mutant mice. Findings indicate that the effects of sulindac in the intestine of these mutant mouse models are probably related to genetic background and appear to be associated with its inflammatory-inducing response.

Apoptosis in the colonic crypt, colorectal adenomata, and manipulation by chemoprevention

This review discusses the biology and the methods of assessment of apoptosis, of which, the monoclonal antibody M30 would seem to be the most useful; the role of apoptosis in the etiology of colorectal cancer; and its use as a marker to monitor the beneficial effects of chemopreventative interventions to reduce the development of colorectal cancer within the context of clinical trials.

NSAIDs downregulate Bcl-X(L) and dissociate BAX and Bcl-X(L) to induce apoptosis in colon cancer cells

Nonsteroidal anti-inflammatory drugs (NSAIDs) are effective in preventing colorectal cancer. Apoptosis induction by NSAIDs plays a critical role in NSAID-mediated chemoprevention. Our previous study demonstrated that NSAIDs require the proapoptotic B-cell non-Hodgkin lymphoma-2 (Bcl-2) family member Bcl-2-associated x protein (BAX) to induce apoptosis and inhibit the expression of antiapoptotic basal cell lymphoma-extra large (Bcl-X(L)) in colon cancer cells. In this study, we further investigated how BAX and Bcl-X(L) mediate NSAID-induced apoptosis. We found that Bcl-X(L) is downregulated by NSAIDs in part through proteasome-mediated protein degradation. NSAIDs promote the dissociation of BAX and Bcl-X(L) and translocation of BAX to the mitochondria. Furthermore, we found that only wild-type BAX, but not a mutant BAX deficient in either protein-protein interaction or mitochondrial localization, was able to restore NSAID-induced apoptosis in the BAX-knockout colon cancer cells. These results suggest that NSAIDs induce apoptosis in colon cancer cells by dissociating BAX and Bcl-X(L), thereby promoting BAX mitochondrial translocation and multimerization.

Apoptosis in normal rectal mucosa, baseline adenoma characteristics, and risk of future adenomas

Low apoptosis in the normal rectal mucosa has been associated with colorectal adenomas in cross-sectional studies. It is unknown whether apoptosis can predict the occurrence of new adenomas. We evaluated whether apoptosis at baseline colonoscopy, as well as patient and adenoma characteristics, could predict future occurrence of adenomas. Study subjects were participants in the Diet and Health Study III, a cross-sectional study of adenoma risk factors between August 1998 and March 2000. At baseline, subjects underwent colonoscopy and provided normal rectal mucosal biopsies to evaluate apoptosis as well as information about diet and lifestyle. The present study includes 257 subjects who returned for follow-up colonoscopy between 2000 and 2005. Apoptosis, number of adenomas, size, and atypia at baseline colonoscopy were evaluated as predictors of new adenomas. Logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (95% CI). At baseline, low apoptosis was significantly associated with increased risk of adenomas (P = 0.0001). Compared with those in the lowest tertile, subjects with high apoptosis were less likely to have an adenoma at follow-up (crude OR, 0.25; 95% CI, 0.09-0.65; adjusted OR, 0.29; 95% CI, 0.08-1.06). Having three or more adenomas at baseline was associated with increased risk of new adenomas (crude OR, 2.46; 95% CI, 1.14-5.31; adjusted OR, 3.74; 95% CI, 1.01-13.83). This study suggests that lower apoptosis is associated with increased risk of future adenoma development. If confirmed in larger studies, apoptosis could potentially be used to identify patients at highest risk for developing new adenomas.

SMAC mimetics sensitize nonsteroidal anti-inflammatory drug-induced apoptosis by promoting caspase-3-mediated cytochrome c release

Nonsteroidal anti-inflammatory drugs (NSAID) are effective in suppressing the formation of colorectal tumors. However, the mechanisms underlying the antineoplastic effects of NSAIDs remain unclear. The effects of NSAIDs are incomplete, and resistance to NSAIDs is often developed. Growing evidence has indicated that the chemopreventive activity of NSAIDs is mediated by induction of apoptosis. Our previous studies showed that second mitochondria-derived activator of caspase (SMAC)/Diablo, a mitochondrial apoptogenic protein, plays an essential role in NSAID-induced apoptosis in colon cancer cells. In this study, we found that SMAC mediates NSAID-induced apoptosis through a feedback amplification mechanism involving interactions with inhibitor of apoptosis proteins, activation of caspase-3, and induction of cytosolic release of cytochrome c. Small-molecule SMAC mimetics at nanomolar concentrations significantly sensitize colon cancer cells to NSAID-induced apoptosis by promoting caspase-3 activation and cytochrome c release. Furthermore, SMAC mimetics overcome NSAID resistance in Bax-deficient or SMAC-deficient colon cancer cells by restoring caspase-3 activation and cytochrome c release. Together, these results suggest that SMAC is useful as a target for the development of more effective chemopreventive strategies and agents.

Increased epithelial cell proliferation in the ileal pouch mucosa of patients with familial adenomatous polyposis

To eliminate the risk of colorectal cancer in patients with familial adenomatous polyposis (FAP), reconstructive proctocolectomy is performed. Although most colonic mucosa is resected during the ileal pouch anal anastomosis, adenomas and carcinomas may develop in the pouch. This may be caused by altered cell kinetics due to intraluminal changes in the pouch. In 32 patients with FAP, biopsy specimens from the mucosa of the pouch and also of the afferent ileal loop were taken. Tissue sections were immunohistochemically processed with the monoclonal antibodies M30 and MIB-1 to assess apoptotic and proliferative indices, respectively. Cell proliferation was also assessed by a modified sign test. There were no significant differences in apoptotic rates between the mucosa of the pouch and the mucosa of the afferent ileal loop. However, cell proliferation was significantly higher in the mucosa of the pouch vs afferent ileal loop, both by using the quantitative (68.3% vs 61.6%, p = 0.001) and semiquantitative methods (p < 0.05). Our newly developed semiquantitative approach outperformed previously described methods. The higher cell proliferation in the pouch as compared to the afferent ileal loop may contribute to the increased risk for adenomas and carcinomas in the pouch of patients with FAP and emphasizes the need for regular endoscopic surveillance.

Sulindac treatment in hereditary non-polyposis colorectal cancer

Non-steroidal anti-inflammatory drugs, e.g. sulindac have been extensively studied for chemoprevention in familial adenomatous polyposis, but not in hereditary non-polyposis colorectal cancer (HNPCC). We evaluated these effects in HNPCC using surrogate end-points for cancer risk. In a randomised double-blind cross-over study, 22 subjects (9 female; age 30-66 years, mean 44), all ascertained or probable mutation carriers for HNPCC, were included. Sulindac 150 mg b.i.d. and placebo were given for 4 weeks each, with 4 weeks in between, with biopsies taken from ascending, transverse and sigmoid colon and rectum by colonoscopy after both periods. Proliferation was determined by Ki-67 staining and apoptosis by staining of cytokeratin 18 cleavage products. Expression of cyclins B1, D3 and E and p21, p27, bax, bcl2 and cox-2 was studied immunohistochemically. Proliferation was higher during sulindac treatment than drug placebo treatment in ascending and transverse colon, but not in sigmoid and rectum. Apoptosis was not affected. Besides an increase in cyclin D3, no differences were found in expression of regulating proteins in the proximal colon.

CONCLUSION

Sulindac induces an increase in epithelial cell proliferation in the proximal colon of subjects with HNPCC. Since colorectal cancer predominantly arises in the proximal colon in HNPCC, these results cast doubts on the potential chemopreventive effects of sulindac in HNPCC.

Sulindac induces specific degradation of the HPV oncoprotein E7 and causes growth arrest and apoptosis in cervical carcinoma cells

Sulindac, a nonsteroidal anti-inflammatory drug (NSAID), induces growth arrest in HeLa cells and causes strong inhibition of the G1 to S transition of the cell cycle in a concentration-dependent manner. The G1 arrest is preceded by suppression of cyclin E and A, inactivation of cdk2, and the complete loss of the viral oncoprotein E7, despite ongoing HPV transcription. As shown by inhibitors specific for cyclooxygenase (COX) 1 and 2 loss of E7 is COX-independent. Moreover, inhibition of the proteasome activity with MG132 partially blocked the ability of sulindac to suppress E7 suggesting that sulindac induces degradation of E7 by the proteasomal pathway. In addition to inhibiting growth, sulindac strongly induces apoptosis, which can be abrogated by using the general caspase inhibitor zVAD-fmk. Unchanged expression of the pro-apoptotic protein Bax and suppression of the anti-apoptotic molecules Bcl-2 and Bcl-x(L) argues for the engagement of the mitochondrial apoptotic pathway. These results support the notion that sulindac is a potent growth inhibitor and inducer of apoptosis on cervical cancer cells in vitro and may offer new perspectives as a chemopreventive or supplementary anti-cervical cancer drug.

Targeting cyclooxygenase-2 for prevention and therapy of colorectal cancer

Cyclooxygenase-2 (COX-2) is an inducible enzyme that regulates prostaglandin synthesis and is overexpressed at sites of inflammation and in several epithelial cancers. A causal link for COX-2 in epithelial tumorigenesis was shown in genetically manipulated animal models of colon and breast carcinoma. Studies have elucidated the regulation of COX-2 expression and have identified EP receptors through which prostanoids exert their biological effects. Mechanistic studies indicated that COX-2 is involved in apoptosis resistance, angiogenesis, and tumor cell invasiveness, which appear to contribute to its effects in tumorigenesis. Furthermore, forced COX-2 expression has been shown to suppress apoptosis by modulating the level of death receptor 5 (DR5) and this effect was reversed by a COX inhibitor. COX enzymes are targets for cancer prevention as shown by the observation that nonselective COX and selective COX-2 inhibitors have been reported to effectively prevent experimental colon cancer and can regress colorectal polyps in patients with familial adenomatous polyposis. This review will focus on the role of COX-2 as a target for the prevention and treatment of human colorectal cancer.

Neoadjuvant selective COX-2 inhibition down-regulates important oncogenic pathways in patients with esophageal adenocarcinoma

OBJECTIVES

To evaluate the effects of neoadjuvant therapy with the selective cyclooxygenase-2 (COX-2) inhibitor celecoxib in vitro and in patients with esophageal adenocarcinoma on COX-2 and MET expression.

SUMMARY BACKGROUND DATA

High COX-2 and/or MET expression levels are negative prognostic factors for adenocarcinoma of the esophagus. Nonsteroidal anti-inflammatory drugs (NSAIDs) and selective COX-2 inhibitors exert anticancer mechanisms as is evident from epidemiologic studies and from experimental models for esophageal cancer. The mechanisms and the significance of these findings in patients with adenocarcinoma of the esophagus are unknown.

METHODS

Esophageal adenocarcinoma cell lines were used to asses the effects in vitro. To study the clinical effects 12 patients with esophageal adenocarcinoma were included for neoadjuvant treatment (4 weeks) with celecoxib at 400 mg twice daily. Fifteen patients not receiving NSAIDs or celecoxib were included as a control. Effects were evaluated using the MTT-cell viability test, Western blot analysis, immunohistochemistry, and RT-PCR.

RESULTS

In vitro celecoxib administration resulted in decreased cell viability, increased apoptosis, and decreased COX-2 and MET expression levels. In patients, neoadjuvant treatment with celecoxib significantly down-regulated COX-2 and MET expression in the tumor when compared with the nontreated control group and when compared with pretreatment measurements.

CONCLUSIONS

This is the first study to show in vitro and in patients with esophageal adenocarcinoma that selective COX-2 inhibition down-regulates COX-2 and MET expression, both important proteins involved in cancer progression and dissemination. Therefore, (neo)adjuvant therapy with celecoxib might have clinical potential for patients with esophageal adenocarcinoma.

Sulindac sulfide–induced apoptosis is enhanced by a small-molecule Bcl-2 inhibitor and by TRAIL in human colon cancer cells overexpressing Bcl-2

Sulindac is a nonsteroidal anti-inflammatory drug (NSAID) that induces apoptosis in cultured colon cancer cells and in intestinal epithelia in association with its chemopreventive efficacy. Resistance to sulindac is well documented in patients with familial adenomatous polyposis; however, the molecular mechanisms underlying such resistance remain unknown. We determined the effect of ectopic Bcl-2 expression upon sulindac-induced apoptotic signaling in SW480 human colon cancer cells. Sulindac sulfide activated both the caspase-8-dependent and mitochondrial apoptotic pathways. Ectopic Bcl-2 attenuated cytochrome c release and apoptosis induction compared with SW480/neo cells. Coadministration of sulindac sulfide and the small-molecule Bcl-2 inhibitor HA14-1 increased apoptosis induction and enhanced caspase-8 and caspase-9 cleavage, Bax redistribution, and cytochrome c and second mitochondria-derived activator of caspase release. Given that sulindac sulfide activated caspase-8 and increased membrane death receptor (DR4 and DR5) protein levels, we evaluated its combination with the endogenous death receptor ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Coadministration of sulindac sulfide and TRAIL cooperatively enhanced apoptotic signaling as effectively as did HA14-1. Together, these data indicate that HA14-1 or TRAIL can enhance sulindac sulfide-induced apoptosis and represent novel strategies for circumventing Bcl-2-mediated apoptosis resistance in human colon cancer cells.

Sulindac inhibits beta-catenin expression in normal-appearing colon of hereditary nonpolyposis colorectal cancer and familial adenomatous polyposis patients

Sulindac reduces colorectal cancer risk in genetically susceptible humans and animals. The molecular mechanisms underlying these effects are incompletely understood. Many studies suggest an important role for induction of apoptosis involving the mitochondrial pathway and the death receptor pathway. Alternatively, mechanisms involving the APC-beta-catenin-Wnt pathway have been suggested, possibly mediated by p21. We determined the effects of sulindac on apoptosis and expression of death receptor (DR)-4 and DR5, beta-catenin, and p21 in normal-appearing colorectal epithelium. Biopsies were obtained before and after sulindac treatment during two chemoprevention studies. Patients (n = 18) with hereditary nonpolyposis colorectal cancer (HNPCC) received 150 mg sulindac bd for 4 weeks in a placebo-controlled crossover design. Patients (n = 6) with familial adenomatous polyposis (FAP) received 150 mg sulindac bd for 6 months. Apoptosis was assessed by M30 staining and expression patterns of DR4, DR5, beta-catenin, and p21 were studied immunohistochemically. In HNPCC patients, apoptotic indices were similar following placebo and sulindac. Also in FAP patients, apoptotic indices were not different after sulindac compared with pretreatment values. Expression of DR4 and DR5 was observed in all samples with no consistent differences between placebo/baseline and sulindac. Intensity of membranous beta-catenin staining was lower in HNPCC samples following sulindac compared with placebo (P < 0.001). Similar results were obtained in FAP samples (P < 0.01). p21 expressions before and after sulindac treatment were similar in both patient groups. In conclusion, sulindac inhibits beta-catenin expression in normal colorectal epithelium from HNPCC and FAP patients without affecting apoptotic indices and DR4, DR5, and p21 expression.

Colorectal cancer prevention: is an ounce of prevention worth a pound of cure?

Colorectal cancer (CRC) is among the most common human malignancies and remains a leading cause of cancer-related morbidity and mortality. Colorectal carcinogenesis is a multistep process characterized by molecular and cellular alterations that result in an identifiable precursor lesion, ie, the adenomatous polyp. The transition from normal mucosa to adenoma and its subsequent progression to carcinoma are protracted events that offer opportunities for preventive interventions. Suppression or reversal of the carcinogenic process in the colorectum with nonpharmacologic or pharmacologic agents, ie, chemoprevention, is an area of considerable research interest and activity. Interest in this field derives from multiple epidemiologic studies showing that regular and continued use of nonsteroidal anti-inflammatory drugs (NSAIDs), predominantly aspirin, is associated with significant reductions in both colorectal adenoma and carcinoma incidence. NSAIDs were first shown to be effective in patients with familial adenomatous polyposis (FAP). Subsequent randomized trials in FAP demonstrated that sulindac and the selective cyclooxygenase-2 (COX-2) inhibitor, celecoxib, can significantly regress existing adenomas, and resulted in Food and Drug Administration (FDA) approval of celecoxib for adjunctive management of these patients. Based on the aforementioned data, aspirin and coxibs have been or are currently being evaluated for the prevention of sporadic adenoma recurrence in high-risk patient populations. Evidence indicates that aspirin can reduce adenoma recurrence rates in patients with prior colorectal neoplasia; however, questions remain, including the optimal dosage, timing of initiation and duration of treatment, and clinical benefit versus potential harm to patients. These same issues apply to the nonpharmacologic agents such as calcium, folic acid, and selenium given as dietary supplements. Apart from aspirin, calcium carbonate is the only other agent that has been shown to modestly reduce sporadic adenoma recurrence rates in a randomized trial. Folate and selenium are being actively studied based on provocative preclinical data. In addition to demonstrating efficacy, chemopreventive agents must also be safe for long-term use, be well accepted by patients, and be cost-effective. In this review, the current status of CRC chemoprevention will be discussed, including the available evidence for selected pharmacologic and nonpharmacologic agents, particularly among high-risk populations.

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.

Immunohistochemical characteristics of duodenal adenomas in familial adenomatous polyposis with special reference to cell kinetics

The duodenum is the second most frequent site of cancer in patients with familial adenomatous polyposis (FAP). The main objective of this study was to evaluate the cell kinetics in duodenal and ampullary adenomas in FAP. The endoscopic and biopsy findings of duodenal adenomas in 22 FAP subjects and 18 non-FAP subjects were compared. Adenomas in FAP included 15 ampullary adenomas and 17 nonampullary adenomas. The cell kinetics was evaluated by immunohistochemistry for Ki-67, p53, bcl-2, and cyclooxygenase 2 (COX2), and the apoptotic index (AI) as determined by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) method. Any correlations between the indices for cell kinetics and the endoscopic findings were identified. All 50 adenomas were histologically verified to be tubular adenoma with low-grade dysplasia. Neither the expression of Ki-67, p53, bcl-2, and COX2 nor the AI differed substantially between FAP and non-FAP subjects. In patients with FAP, duodenal adenoma tended to have a higher Ki-67-labeling index than the ampullary adenoma (54.3 +/- 11.3 versus 46.8 +/- 12.7; .05 < P < .1). In addition, the Ki-67-labeling index in endoscopically normal or slightly enlarged ampullary adenoma was significantly higher than that in markedly enlarged ampullary adenoma (51.8 +/- 11.4 versus 39.4 +/- 11.3; P < .05). Duodenal adenoma in FAP subjects was not found to have a higher proliferative activity or a smaller degree of apoptosis compared with those in non-FAP subjects. The smaller proliferative activity in larger ampullary adenoma may thus be related to the static nature of ampullary adenoma in FAP.

Cell Proliferation and Apoptotic Indices Predict Adenoma Regression in a Placebo-Controlled Trial of Celecoxib in Familial Adenomatous Polyposis Patients

Background: Celecoxib was shown to regress colorectal adenomas in familial adenomatous polyposis (FAP) patients relative to placebo. To address the mechanism of polyp regression, we determined whether celecoxib can modulate cell proliferation, apoptosis, and prostaglandin E2 (PGE2) levels in colorectal epithelia from FAP trial participants and whether such alterations correlate with observed reductions in polyp number. Materials and Methods: Colorectal mucosal biopsies were obtained at baseline and on last day of celecoxib (100 or 400 mg twice daily) or placebo administration (6 months). Residual paraffin-embedded adenomas and normal mucosa from the same patients (n = 17) or normal tissue alone (n = 15) were analyzed. Immunoperoxidase staining for Ki-67 was performed and apoptotic cells were identified by their morphology. Ki-67 and apoptotic labeling indices and their ratios were calculated in superficials (s) and nonsuperficial (ns) regions of adenomas and normal mucosa, and baseline to 6-month differences were calculated. PGE2 levels were analyzed by mass spectroscopy (normal, n = 64; adenoma, n = 56). Biomarkers were analyzed by treatment arm and correlated with previously determined mean percentage reductions in colorectal polyp number. Results: In adenomas, a reduction in the superficial proliferative activity i.e., Ki-67s labeling index, accompanied polyp regression (r = −0.76, P = 0.006). An increase in the apoptotic ratio [i.e., superficial apoptotic index (AIs)/nonsuperficial apoptotic index (AIns)] was found to correlate with reduced polyp counts in that higher apoptotic ratios correlated with better response to celecoxib (r = 0.71, P = 0.004). Furthermore, the AIs/Ki-67s ratio (r = 0.58, P = 0.026) accompanied polyp regression. In normal mucosa, a trend toward increased AIs (r = 0.33, P = 0.053) and polyp regression was found. PGE2 levels did not significantly correlate with polyp regression. Changes in biomarker levels (baseline to 6 months) were correlated in adenomas and normal mucosa (AIs, r = 0.29, P = 0.024; AIns, r = 0.34, P = 0.009; PGE2, r = 0.50, P = 0.059) within individual patients. Conclusion: Suppression of cell proliferation and an increased apoptotic ratio, as well as the ratio of apoptosis to cell proliferation, accompany polyp regression in a chemoprevention trial in FAP patients. These findings suggest potential mechanisms for the efficacy of celecoxib and warrant further study of these biomarkers as intermediate endpoints in FAP patients.

Sulindac targets nuclear beta-catenin accumulation and Wnt signalling in adenomas of patients with familial adenomatous polyposis and in human colorectal cancer cell lines

Nonsteroidal anti-inflammatory drugs (NSAIDs) have chemopreventive potential against colorectal carcinomas (CRCs). Inhibition of cyclooxygenase (COX)-2 underlies part of this effect, although COX-2-independent mechanisms may also exist. Nonsteroidal anti-inflammatory drugs appear to inhibit the initial stages of the adenoma-carcinoma sequence, suggesting a link to the APC/beta-catenin/TCF pathway (Wnt-signalling pathway). Therefore, the effect of the NSAID sulindac on nuclear (nonphosphorylated) beta-catenin and beta-catenin/TCF-mediated transcription was investigated. Nuclear beta-catenin expression was assessed in pretreatment colorectal adenomas and in adenomas after treatment with sulindac from five patients with familial adenomatous polyposis (FAP). Also, the effect of sulindac sulphide on beta-catenin/TCF-mediated transcription was studied. Adenomas of FAP patients collected after treatment with sulindac for up to 6 months showed less nuclear beta-catenin expression compared to pretreatment adenomas of the same patients. Sulindac sulphide abrogated beta-catenin/TCF-mediated transcription in the CRC cell lines DLD1 and SW480, and decreased the levels of nonphosphorylated beta-catenin. As a result, the protein levels of the positively regulated TCF targets Met and cyclin D1 were downregulated after sulindac treatment. This study provides in vivo and in vitro evidence that nuclear beta-catenin localisation and beta-catenin/TCF-regulated transcription of target genes can be inhibited by sulindac. The inhibition of Wnt-signalling provides an explanation for the COX-2-independent mechanism of chemoprevention by NSAIDs.

Cyclo-oxygenase inhibition in colorectal adenomas and cancer

Increasing evidence indicates that Non-steroidal anti-inflammatory drugs (NSAIDs), compounds that inhibit the enzymatic activity of cyclooxygenase (COX), can reduce the number and size of adenomas in patients with familial adenomatous polyposis as well as the incidence of colorectal cancer. The COX enzyme family consists of the classic COX-1 and a second enzyme, COX-2, which is induced by various stimuli, such as mitogens and cytokines. While it is well proven that COX-2 overexpression is a central event in colorectal carcinogenesis, that prostaglandins (PGs) can contribute to tumorigenesis, and that COX-2 selective inhibitors are active chemopreventive agents, the molecular mechanisms by which NSAIDs exert their chemopreventive effect is not fully understood. However, significant advances have been made in understanding the interference of NSAIDs with the pathways that control cell growth and survival even independently from their COX-inhibiting properties, making their use attractive both alone and in combination with standard therapies in the treatment of advanced colorectal cancer. In addition, the recently recognized anti-angiogenic and radiosensitizer properties of COX-2 inhibitors support, further suggest their use in the adjuvant setting.

Genetic testing for hereditary colorectal cancer in children: long-term psychological effects

Children who carry a gene mutation for familial adenomatous polyposis are virtually certain to develop colorectal cancer without annual endoscopic screening and a colectomy when polyps appear. Predictive genetic testing can identify children who need regular surveillance. While the medical benefits of genetic testing are clear, the psychological effects have not been well studied. We evaluated the long-term psychological effects of genetic testing in 48 children and their parents. In each family, one parent was a known APC gene mutation carrier. Before genetic testing, and three times afterward, participants completed measures of psychological functioning, which, for children, included depression and anxiety symptoms, and behavior problems and competencies. Parents completed a measure of depression symptoms. Data were collected at 3-, 12-, and 23-55 months after disclosure. Twenty-two children tested positive; 26 children tested negative. Mean length of follow-up was 38 months. There were no clinically significant changes in mean psychological test scores in children or parents, regardless of the children's test results or the sex of the affected parent. However, the group of children who tested positive and had a mutation-positive sibling showed significant, but subclinical, increases in depression symptoms. Furthermore, several individual mutation-negative children with a positive sibling had clinical elevations in anxiety symptoms at one or more follow-up. Behavior problems declined for all groups, and behavior competence scores remained unchanged. We conclude that most children do not suffer clinically significant psychological distress after testing. However, because some children showed clinically significant anxiety symptoms, long-term psychological support should be available to those families with both mutation-positive and mutation-negative children, and with multiple mutation-positive children. Our findings should call for a multidisciplinary approach to genetic testing for children.

Changes in apoptosis during the development of colorectal cancer: a systematic review of the literature

The development of colorectal cancer is characterised by an accumulation of molecular genetic alterations causing disorders in cell growth, differentiation and apoptosis. Although changes in apoptosis with colorectal cancer development have been studied extensively, a clear consensus of opinion has not yet emerged. In this review, the literature about changes in the frequency and distribution of apoptosis in tissue sections of normal and neoplastic colorectal tissues was reviewed systematically. Using a PUBMED search, 53 relevant articles were identified. Data from these studies are discussed with respect to the following aspects: methods used to detect apoptotic cell death; frequency and locoregional distribution of apoptosis in normal mucosa, adenomas and carcinomas; the correlation between levels of apoptosis and proliferation and the prognostic significance of the degree of apoptosis in colorectal cancer. Possible underlying mechanisms of dysregulation of apoptosis are discussed briefly. Finally, possible therapeutic implications of knowledge of the molecular regulation of apoptosis are discussed and potential options for further research are suggested.

Effect of Helicobacter pylori-induced cyclooxygenase-2 on gastric epithelial cell kinetics: implication for gastric carcinogenesis

BACKGROUND

Cyclooxygenase (COX)-2 induced by Helicobacter pylori is thought to enhance gastric carcinogenesis by affecting the maintenance of epithelial homeostasis.

MATERIALS AND METHODS

Gastric biopsies from 160 subjects, 97 with nonulcer dyspepsia (47 H. pylori negative, 50 H. pylori positive) and 63 with gastric cancer were examined immunohistochemically for COX-2 expression, cell proliferation and apoptotic indices.

RESULTS

COX-2 expression in corpus was significantly higher in H. pylori positive than in negative non-ulcer dyspepsia (NUD) (p <.05). Regardless of site, gastric cancer subjects had higher COX-2 expression in both antrum and corpus compared with H. pylori negative and positive NUD (p <.005). Proliferation was higher in cancer and H. pylori positive than in negative NUD (p <.0001). Moreover, cancer had enhanced proliferation than H. pylori positive NUD in corpus greater (p =.0454) and antrum lesser (p =.0215) curvatures. Apoptosis was higher in H. pylori positive than in negative NUD (p <.05). However, both had a higher index than the cancer subjects (p <.0001). Apoptosis : proliferation ratio was higher in corpus of H. pylori negative than in positive NUD in greater (p =.0122) and lesser (p =.0009) curvatures. However, both had a higher A:P ratio than cancer cases (p =.0001). A negative correlation between COX-2 expression and A:P ratio was found in corpus greater (r = -.176, p =.0437) and lesser (r = -.188, p =.0312) curvatures.

CONCLUSION

The expression of COX-2 is associated with disruption in gastric epithelial kinetics and hence may play a role in gastric carcinogenesis.

Diallyl disulfide (DADS) induces the antitumorigenic NSAID-activated gene (NAG-1) by a p53-dependent mechanism in human colorectal HCT 116 cells

Garlic is appealing as an anti-carcinogenic agent due to its ability to induce apoptosis in vitro and inhibit the formation and growth of tumors in animals in vivo. Diallyl disulfide (DADS) is a constituent of garlic that suppresses neoplastic cell growth and induces apoptosis. We examined the effects of DADS on various cancer cell lines to better understand its effect on apoptosis and apoptosis-related genes. The nonsteroidal anti-inflammatory drug (NSAID)-activated gene (NAG-1) has proapoptotic and antitumorigenic activities and is upregulated by anticancer agents such as NSAIDs. In this study, human colorectal HCT-116 (wild-type p53), HCT-15 (p53 mutant) and human prostate PC-3 (p53 mutant) cells were exposed to DADS. DADS inhibited cell proliferation in all cell lines albeit to a lesser extent in HCT-15 and PC-3 cells at 11.5 and 23 micromol/L. In HCT-116 cells, DADS induced p53 and NAG-1 in a dose-dependent manner and the induction of p53 preceded that of NAG-1. In HCT-116 cells, NAG-1 protein expression was increased 2.4-fold +/- 0.6 at 4.6 micromol/L and 6.1-fold +/- 1.7 at 23 micromol/L DADS, whereas p53 was induced 1.5-fold +/- 0.1 and 2.3-fold +/- 0.4. DADS did not induce NAG-1 or p53 in p53 mutant cell lines; however, NAG-1 expression was induced by sulindac sulfide. HCT-116 cells treated with 4.6 and 23 micromol/L DADS resulted in a 1.9- and 2.9-fold increase in apoptosis, respectively. In contrast, 23 micromol/L DADS induced apoptosis only 1.8-fold in HCT-15 cells and not at all in PC-3 cells. Thus, DADS-induced apoptosis and NAG-1 protein expression appear to occur via p53.

NSAID inhibition of GI cancer growth: clinical implications and molecular mechanisms of action

Epidemiological studies suggest that aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) reduce the incidence of and mortality from colorectal, gastric, and esophageal cancers. The precise mechanisms by which NSAIDs exert their chemopreventive effects are not fully explained, but likely involve inhibition of cyclo-oxygenase, the enzyme that converts arachidonic acid to prostaglandins. Two isoforms of this enzyme, cyclo-oxygenase 1 (COX-1) and COX-2, have been identified. COX-2 is absent in normal mucosa but is overexpressed in colonic, gastric, and esophageal cancers, as well as their precursor lesions. The inhibition of COX-2 through either pharmacological agents or gene deletion results in suppression of colonic polyp formation. NSAIDs reduce colonic, gastric, and esophageal cancer cell growth, in part, by inducing apoptosis. However, the antineoplastic effects of NSAIDs may be partly independent of their ability to inhibit COX-2. The mechanisms involved in the antineoplastic actions of NSAIDs include inhibition of angiogenesis (essential for delivery of oxygen and nutrients to a growing tumor), induction of apoptosis (which is usually reduced in cancer cells) by stimulation of proapoptotic genes, and direct inhibition of cancer cell growth by blocking signal transduction pathways responsible for cell proliferation.

Growth inhibition and apoptosis induction of Sulindac on Human gastric cancer cells

AIM: To evaluate the effects of sulindac in inducing growth inhibition and apoptosis of human gastric cancer cells in comparison with human hepatocellular carcinoma (HCC) cells.

METHODS: The human gastric cancer cell lines MKN45 and MKN28 and human hepatocellular carcinoma cell lines HepG₂ and SMMC7721 were used for the study. Anti-proliferative effect was measured by MTT assay, and apoptosis was determined by Hoechst-33258 staining, electronography and DNA fragmentation. The protein of cyclooxygenase-2 (COX-2) and Bcl-2 were detected by Western dot blotting.

RESULTS: Sulindac could initiate growth inhibition and apoptosis of MKN45, MKN28, HepG₂ and SMMC7721 cells in a dose-and time-dependent manner. Growth inhibitory activity and apoptosis were more sensitive in HepG₂ cells than in SMMC7721 cells, MKN45 and MKN28 cells. After 24 h incubation with sulindac at 2 mmol•L¯¹ and 4 mmol•L¯¹, the level of COX-2 and Bcl-2 protein were lowered in MKN45, SMMC7721 and HepG₂ cells but not in MKN28 cells.

CONCLUSION: Sulindac could inhibit the growth of gastric cancer cells and HCC cells effectively in vitro by apoptosis induction, which was associated with regression of COX- 2 and Bcl-2 expression. The growth inhibition and apoptosis of HCC cells were greater than that of human gastric cancer cells. The different effects of apoptosis in gastric cancer cells may be related to the differentiation of the cells.

Increased apoptosis associated with depressed type of early intestinal gastric cancer

Early gastric cancer can be macroscopically classified into elevated and depressed types. To clarify the relationship between macroscopic appearance of early gastric cancer and apoptosis or cell proliferation, formalin-fixed paraffin-embedded tissue specimens of 44 intestinal-type early gastric cancers were investigated by the TUNEL method and immunohistochemical techniques. Diffuse type was excluded in this study. When tissue sections of gastric cancer were vertically classified into the 3 compartments of luminar, intermediate and basal, the apoptosis index (%) was significantly higher in the basal compartment of depressed type (1.76 +/- 2.04, mean +/- SD) than in the basal compartment of elevated type (0.63 +/- 0.81, P = 0.01). In depressed type, the apoptosis index (%) was significantly higher in the basal compartment than in the luminar compartment (0.76 +/- 0.85, P = 0.03). Apoptosis-inducing protein, Bax, was expressed more in each of the compartments of depressed type than in those of elevated type, while there were no significant differences in expression of anti-apoptotic protein, Bcl-2, between the two types. Moreover, the apoptosis index (%) of Bax-positive gastric cancer was significantly higher in the basal compartment (P = 0.03), compared to that of Bax-negative gastric cancer, while there were no significant differences in apoptosis index (%) in any compartment between Bcl-2-positive and Bcl-2-negative gastric cancers. There were no significant differences in Ki-67 expression, either between the two types, or among the compartments of depressed type. These results indicate that increased apoptosis with excessive expression of Bax in the basal compartment is involved in the morphogenesis of the depressed type in intestinal-type early gastric cancer.

Inhibition of human brain tumor cell growth by the anti-inflammatory drug, flurbiprofen

Despite many efforts to alter the relentlessly aggressive progression of tumors of neural origin, individuals bearing these tumors exhibit poor prognosis for long-term survival. In an attempt to find an effective treatment, we examined the efficacy of the non-steroidal anti-inflammatory drug, flurbiprofen, to suppress the growth of tumor cell lines derived from medulloblastoma and glioblastoma multiforme. Results from cell proliferation assays have revealed that flurbiprofen effectively inhibits the growth of various tumor cells in a dose-dependent manner and causes a noticeable change in the progression of cells through cell cycle stages. Treatment of tumor cells with flurbiprofen reduced the number of cells in G1 and G2, and significantly increased their numbers in S phase, suggesting that, flurbiprofen accelerates G1/S entry, and/or delays cell exit from S to G2/M stages. Results from RNase protection assay and Western blot analysis showed that while treatment of cells with flurbiprofen causes a minor change in the RNA level of different cyclins, there is a significant decrease in the level of cyclin B protein upon flurbiprofen treatment. Examination of tumor suppressors by RNase protection technique showed a subtle increase in the levels of several tumor suppressors upon flurbiprofen treatment. Interestingly, at the protein level, p53 tumor suppressor was substantially increased upon flurbiprofen treatment, yet the level of p21, a downstream target for p53 remained unchanged. Curiously, treatment of the cells with flurbiprofen enhanced the level of COX-2 expression. Results from co-immunoprecipitation showed association of COX-2 with p53 in tumor cells. These observations suggest that the interaction of COX-2 with p53 may cause p21-independent suppression of tumor cell growth upon flurbiprofen treatment.

Effects of cellular redox balance on induction of apoptosis by eicosapentaenoic acid in HT29 colorectal adenocarcinoma cells and rat colon in vivo

BACKGROUND AND AIMS

Epidemiological evidence suggests n-3 polyunsaturated lipids may protect against colorectal neoplasia. Consumption of fish oil modulates crypt cytokinetics in humans, and crypt apoptosis in animal models. To explore these effects, we investigated involvement of caspase enzymes and cellular redox balance in the induction of apoptosis by eicosapentaenoic acid (EPA) in HT29 cells, and in rat colon in vivo.

METHODS

Survival of HT29 cells grown with EPA in the presence of caspase inhibitors, antioxidants, or buthionine sulphoximine, an inhibitor of glutathione neosynthesis, was determined. The effects of EPA enriched fish oil and glutathione depletion on apoptosis in rat colon were assessed using microdissected crypts.

RESULTS

Treatment of HT29 cells with EPA reduced viable cell number and activated caspase 3, prior to cell detachment. Antioxidants and caspase inhibitors blocked HT29 cell death whereas glutathione depletion increased it. Rats fed fish oil had higher crypt cell apoptosis than those fed corn oil, and glutathione depletion enhanced this effect.

CONCLUSIONS

Incorporation of EPA into colonic epithelial cell lipids increases apoptosis. The results of this study, using both an animal and cell line model, support the hypothesis that this effect is mediated via cellular redox tone, and is sensitive to glutathione metabolism. The data suggest a mechanism whereby polyunsaturated fatty acids may influence the susceptibility of colorectal crypt cells to induction or progression of neoplasia.

A molecular rationale for the how, when and why of colorectal cancer screening

Colorectal cancer remains a leading cause of cancer-related mortality in the United States. Recently, colorectal cancer screening and colorectal cancer prevention have gained national attention. In response, the American Gastroenterological Association, the American College of Gastroenterology and the Agency for Healthcare Policy and Research have published recommendations for colorectal cancer screening and surveillance in patients with sporadic as well as hereditary forms of colorectal cancer. This review will focus on the basic molecular differences underlying the formation of carcinoma in patients with sporadic colorectal cancer, and the heritable syndromes of familial adenomatous polyposis (FAP), hereditary non-polyposis colorectal cancer (HNPCC), and juvenile polyposis (JPS). By appreciating the molecular mechanisms underlying these four types of polyp cancer syndromes, the differences in clinical time course for progression from polyp to carcinoma and in current screening recommendations for patients with sporadic adenomas, FAP, HNPCC and JPS can be better understood.

Lewis antigens and argyrophilic nucleolar organizer regions staining for assessment of potential malignancy of adenomatous polyps of the gastrointestinal tract in children

Adenomatous polyps (AP) of the gastrointestinal tract in children are very rare. Because of their potential malignancy, they are of great clinical importance. There is little experience in the management of children with AP. The immunohistochemical expression of the Lewis blood group antigens (BGA) (sialosyl-Le(a), Le(a), Leb, Le(x), and Le(y)) and the number of activated nucleoli with the silver staining method for nucleolar organizer regions (AgNORs) were studied in two children with AP. In a girl with isolated AP of the stomach and colon, it was found that antigens Le(b) and s-Le(a) were expressed extensively in the gastric adenoma, and sialosyl-Le(a) throughout the entire length of the rectal adenoma crypts, but in the AgNORs stain the number of nucleoli ranged from two to four, evidencing changes of a benign character. In the case of familial adenomatous polyposis diagnosed in a 9-year-old boy, in some colonic adenomas the number of activated nucleoli was greater than five, and the Le(b) antigen was expressed in superficial epithelial cells in one of the adenomas. Also, extensive expression of antigens Le(y) and s-Le(a) throughout the entire length of the crypt in another polyp removed was observed. We believe that immunohistochemical study of the intensity and extent of the expression of Lewis BGA in the polyp tissue simultaneously with the determination of the number of activated nucleoli by the AgNORs staining method can be helpful in better analysis of cytological risk factors of a malignant transformation.