Alteration of tumor growth by aspirin and indomethacin: studies with two transplantable tumors in mouse

Combination of Photothermal Therapy with Anti-Inflammation Therapy Attenuates the Inflammation Tumor Microenvironment and Weakens Immunosuppression for Enhancement Antitumor Treatment

Photothermal therapy has gained widespread attention in cancer treatment, although its efficacy is suppressed due to the inflammatory response and immunosuppression, resulting in a discounted therapeutic effect. In this contribution, a high-performance NIR absorption organic small chromophore is developed, which is encapsulated into Pluronic F-127 to fabricate NIR absorption organic nanoparticles (TTM NPs) with excellent photothermal conversion efficiency (51.49%) for photothermal therapy. TTM NPs based photothermal therapy are combined with Aspisol, a kind of nonsteroidal anti-inflammatory drug, to weaken the inflammation and immunosuppression tumor microenvironment and enhance the antitumor effect. The results prove that the combination therapy realizes effective thermal elimination of primary tumors, inhibition of distant tumors, and suppression of tumor metastasis. The data show that combination therapy can suppress the expression of inflammatory factors, enhance dendritic cell activation and maturation, reverse the immunosuppression, facilitate T cell infiltration, and restore antitumor cytotoxic T lymphocyte activity. This study provides a paradigm to extend the development of photothermal therapy.

Aggressive fibromatosis response to tamoxifen: lack of correlation between MRI and symptomatic response

Background

One of the commonly used systemic agents for the treatment of aggressive fibromatosis is the anti-oestrogen drug tamoxifen. However, data on efficacy and optimum methods of response assessment are limited, consisting mainly of small case series and reports.

Methods

A retrospective database was used to identify consecutive patients diagnosed with aggressive fibromatosis (AF) and treated with tamoxifen plus/minus non-steroidal anti-inflammatory drugs at our tertiary referral centre between 2007 and 2014. MRI and symptom changes were recorded.

Results

Thirty-two patients (13 male 19 female, median age 41 years) were included. Median duration of treatment with tamoxifen was 316 days. Of 9 patients with progressive disease by RECIST 1.1 (28%): 4 patients experienced worsening symptoms; 3 patients had improved symptoms and 2 had no change in symptoms. Of 22 patients with stable disease (69%): 11 had no change in symptoms; 6 had improved symptoms and 5 patients had worsening symptoms. One patient achieved a partial response with improved symptoms.

Conclusions

No relationship was identified between symptomatic benefit and response by RECIST 1.1 on MRI. Prospective studies in AF should incorporate endpoints focusing on patient symptoms.

Serendipity in Cancer Drug Discovery: Rational or Coincidence?

Novel drug development leading to final approval by the US FDA can cost as much as two billion dollars. Why the cost of novel drug discovery is so expensive is unclear, but high failure rates at the preclinical and clinical stages are major reasons. Although therapies targeting a given cell signaling pathway or a protein have become prominent in drug discovery, such treatments have done little in preventing or treating any disease alone because most chronic diseases have been found to be multigenic. A review of the discovery of numerous drugs currently being used for various diseases including cancer, diabetes, cardiovascular, pulmonary, and autoimmune diseases indicates that serendipity has played a major role in the discovery. In this review we provide evidence that rational drug discovery and targeted therapies have minimal roles in drug discovery, and that serendipity and coincidence have played and continue to play major roles. The primary focus in this review is on cancer-related drug discovery.

Personalizing Aspirin Use for Targeted Breast Cancer Chemoprevention in Postmenopausal Women

OBJECTIVE

To evaluate the association of aspirin and other nonsteroidal anti-inflammatory drugs with the incidence of postmenopausal breast cancer for risk subgroups defined by selected nonmodifiable or difficult to modify breast cancer risk factors in order to better understand the potential risk-benefit ratio for targeted chemoprevention.

PATIENTS AND METHODS

Postmenopausal women with no history of cancer on July 1, 1992 (N=26,580), were prospectively followed up through December 31, 2005, for breast cancer incidence (N=1581). Risk subgroups were defined on the basis of family history of breast cancer, age at menarche, age at menopause, parity/age at first live birth, personal history of benign breast disease, and body mass index. Hazard ratios (HRs) and 95% CIs adjusted for other breast cancer risk factors were estimated using Cox models.

RESULTS

Aspirin use was associated with a lower incidence of breast cancer for women with a family history of breast cancer (HR, 0.62 for 6 or more times per week vs never use; 95% CI, 0.41-0.93) and those with a personal history of benign breast disease (HR, 0.69; 95% CI, 0.50-0.95) but not for women in higher-risk subgroups for age at menarche, age at menopause, parity/age at first live birth, or body mass index. In contrast, inverse associations with aspirin use were observed in all lower-risk subgroups. Nonsteroidal anti-inflammatory drug use had no association with breast cancer incidence.

CONCLUSION

On the basis of their increased risk of breast cancer, postmenopausal women with a family history of breast cancer or a personal history of benign breast disease could potentially be targeted for aspirin chemoprevention studies. Future studies are needed to confirm these findings.

Comparative in vitro metabolism of phospho-tyrosol-indomethacin by mice, rats and humans

Phospho-tyrosol-indomethacin (PTI; MPI 621), a novel anti-cancer agent, is more potent and safer than conventional indomethacin. Here, we show that PTI was extensively metabolized in vitro and in vivo. PTI was rapidly hydrolyzed by carboxylesterases to generate indomethacin as its major metabolite in the liver microsomes and rats. PTI additionally undergoes cytochromes P450 (CYP)-mediated hydroxylation at its tyrosol moiety and O-demethylation at its indomethacin moiety. Of the five major human CYPs, CYP3A4 and CYP2D6 catalyze the hydroxylation and O-demethylation reactions of PTI, respectively; whereas CYP1A2, 2C9 and 2C19 are inactive towards PTI. In contrast to PTI, indomethacin is primarily O-demethylated by CYP2C9, which prefers acidic substrates. The hydrolyzed and O-demethylated metabolites of PTI are further glucuronidated and sulfated, facilitating drug elimination and detoxification. We observed substantial inter-species differences in the metabolic rates of PTI. Among the liver microsomes from various species, PTI was the most rapidly hydrolyzed, hydroxylated and O-demethylated in mouse, human and rat liver microsomes, respectively. These results reflect the differential expression patterns of carboxylesterase and CYP isoforms among these species. Of the human microsomes from various tissues, PTI underwent more rapid carboxylesterase- and CYP-catalyzed reactions in liver and intestine microsomes than in kidney and lung microsomes. Together, our results establish the metabolic pathways of PTI, reveal significant inter-species differences in its metabolism, and provide insights into the underlying biochemical mechanisms.

Association of Aspirin and Nonaspirin Nonsteroidal Anti-inflammatory Drugs With Cancer Incidence and Mortality

BACKGROUND

The cancer chemopreventive benefits of aspirin and nonaspirin nonsteroidal anti-inflammatory drugs (NSAIDs) are incompletely defined and may vary by smoking history. We evaluated associations between aspirin and nonaspirin NSAID use with cancer incidence and mortality stratified by smoking history in the Iowa Women's Health Study, a prospective cohort of postmenopausal women.

METHODS

Aspirin and nonaspirin NSAID use was self-reported by questionnaire in 1992. Cancer incidence and mortality were ascertained by annual linkage to the Iowa Surveillance, Epidemiology, and End Results Cancer Registry and death certificates. Cox proportional hazards models were used to estimate multivariable relative risks (RRs) and 95% confidence intervals (CIs). All statistical tests were two-sided.

RESULTS

During an average of 10 years of follow-up, 3487 incident cancer cases and 3581 deaths were observed in the cohort of 22,507 women. Compared with nonuse, aspirin use was inversely associated with total cancer incidence (multivariable-adjusted RR = 0.84, 95% CI = 0.77 to 0.90), with age-adjusted incidence rates of 147 and 170 per 10,000 person-years for ever and never users, respectively, and was inversely associated with cancer mortality (multivariable-adjusted RR = 0.87, 95% CI = 0.76 to 0.99), with age-adjusted rates of 47 and 52 per 10,000 person-years. The inverse relationship was stronger among former and never smokers than current smokers, although not statistically significantly (P = .28). Aspirin use was also inversely associated with coronary heart disease mortality (multivariable-adjusted RR = 0.75, 95% CI = 0.64 to 0.89), with age-adjusted rates of 23 and 30 per 10,000 person-years for ever and never users, respectively, and with all-cause mortality (multivariable-adjusted RR = 0.82, 95% CI = 0.76 to 0.89), with age-adjusted rates of 126 and 155 per 10,000 person-years. Nonaspirin NSAID use was not associated with cancer incidence or mortality, coronary heart disease mortality, or all-cause mortality.

CONCLUSIONS

Aspirin use, but not nonaspirin NSAID use, was associated with lower risks of cancer incidence and mortality, which was more pronounced among former and never smokers than current smokers.

Fibromatosis: benign by name but not necessarily by nature

Aggressive fibromatoses, also known as desmoid tumours, are rare fibrous tissue proliferations with a tendency for slow, local infiltrative growth. There is an association with Gardner's syndrome and familial adenomatous polyposis. Histologically they are fairly bland with no abnormal mitoses or necrosis. They do not metastasize, but can cause significant morbidity through their locally destructive effects. Magnetic resonance imaging is the method of choice for diagnosis, pre-treatment planning and post-treatment follow-up. Surgical excision with a wide margin is the treatment of choice. However, there is a tendency for local recurrence and repeated excision may result in a poor functional or cosmetic outcome. Radiotherapy is used to reduce local recurrence rates after excision and is also used to treat inoperable tumours. Long-lasting remissions can be obtained. Treatment is now planned using modern three-dimensional conformal techniques, similar to those used in soft tissue sarcoma management. There is no definite dose-response relationship, but doses of 50-60 Gy in 1.8-2 Gy fractions are recommended. Systemic therapy has been used for lesions not controlled by surgery or radiotherapy, or less commonly, as a primary treatment. Tamoxifen and non-steroidal anti-inflammatory agents are used most often as they are relatively non-toxic, but there is limited experience with cytotoxic chemotherapy and biological agents. There are no randomised trials to help guide the management of this locally aggressive 'benign' tumour and treatment decisions are best made by the local soft tissue sarcoma multidisciplinary team.

The role of COX-2 in intestinal cancer

Cyclooxygenase (COX), the key regulatory enzyme for prostaglandin synthesis, is transcribed from two distinct genes. COX-1 is expressed constitutively in most tissues whereas COX-2 is induced by a wide variety of stimuli and was initially identified as an immediate-early growth response gene. In addition, COX-2 expression is markedly increased in 85-90% of human colorectal adenocarcinomas while COX-1 levels remain unchanged. Several epidemiological studies have reported a 40-50% reduction in the risk of developing colorectal cancer in persons who chronically take non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin, which are classic inhibitors of COX. Genetic evidence also supports a role for COX-2, since mice null for COX-2 have an 86% reduction in tumour multiplicity in a background containing a mutated APC allele. These results strongly suggest that COX-2 contributes to the development of intestinal tumours and that inhibition of COX is chemopreventative. It is hoped that the chemopreventative effects of NSAIDs will be enhanced by the recent development of COX-2-specific inhibitors.

High-dose tamoxifen and sulindac as first-line treatment for desmoid tumors

BACKGROUND

Desmoid tumors are mesenchymal nonmetastasizing neoplasms. Although rare in the general population, they are a common extracolonic manifestation of familial adenomatous polyposis (FAP). Because of high tumor recurrence rates, surgery has been less than satisfactory in the treatment of desmoid tumors. In the current study, high doses of tamoxifen in combination with sulindac were used to treat severe desmoid tumors to avoid surgery.

METHODS

Since 1992, 25 patients at Heinrich Heine University (Dusseldorf, Germany) were treated with a combination of tamoxifen and sulindac. In the current study, 17 patients with FAP-associated and 8 patients with sporadic desmoid tumors received 120 mg of tamoxifen and 300 mg of sulindac daily. Every 6 months, the protracted course of desmoid growth was measured by computed tomography and/or magnetic resonance imaging scans. Tumor responses were characterized as progressive disease, stable disease (SD), partial regression (PR), and complete regression (CR).

RESULTS

Of the group of patients who received tamoxifen and sulindac as a primary treatment, all three patients with sporadic desmoid tumors demonstrated cessation of growth, and 10 of the 13 patients with FAP-associated tumors achieved either a PR or CR. In the sporadic desmoid tumor group, eight of nine patients developed tumor recurrences after undergoing surgery at other institutions. Of these, two patients had SD and two patients had a PR to CR.

CONCLUSIONS

The patients with desmoid tumors who were managed conservatively with high-dose tamoxifen and sulindac had the best outcome. Desmoid tumor recurrence after surgery was high and in the FAP-associated tumor group, therapy with tamoxifen and sulindac was found to be less successful. Based on this experience, the authors recommended high-dose tamoxifen and sulindac as the primary treatment for patients with FAP-associated desmoid tumors. However, to our knowledge, the best approach after surgical intervention for patients with sporadic desmoid tumors remains to be determined.

Activity of the non-steroidal anti-inflammatory drug indomethacin against colorectal cancer

A substantial body of evidence from rodent colon carcinogenesis models, in vitro experiments with human colorectal cancer cells and limited clinical observations in humans suggest that the non-steroidal anti-inflammatory drug indomethacin has anti-colorectal cancer activity. However, although many mechanisms of the anti-neoplastic activity of indomethacin have been suggested, e.g., cyclooxygenase inhibition and peroxisome proliferator-activated receptor gamma activation, the precise relevance of the majority of in vitro pharmacological observations to the in vivo anti-neoplastic activity of indomethacin remains unclear. Herein, we review the existing literature describing the chemopreventative and chemotherapeutic efficacy of indomethacin against colorectal cancer, and draw together the disparate literature describing potential mechanisms of action of indomethacin in human colorectal cancer cells in vitro. Although indomethacin itself has significant adverse effects, including serious upper gastrointestinal toxicity, the development of novel derivatives that may have an improved safety profile means that further investigation of the anti-colorectal cancer activity of indomethacin is warranted.

The pharmacological treatment of aggressive fibromatosis: a systematic review

BACKGROUND

Despite the use of surgery and radiotherapy, 20-35% of patients with aggressive fibromatosis (AF) will have local recurrence. The purpose of this review was to collect and analyze all available information regarding the role of non-cytotoxic and cytotoxic chemotherapy in AF that has been accumulated over the past few decades.

PATIENTS AND METHODS

A systematic review of published clinical trials, studies and case series was carried out using the Medline Express Databases and the Cochrane Collaboration Database from 1970 to October 2000.

RESULTS

Most studies published in the literature are in the form of successful case reports and single-arm series with small patient numbers. Most commonly used agents include hormonal agents, non-steroidal anti-inflammatory drugs (NSAIDs), interferons and cytotoxics. The literature data support the use of hormonal agents. Several questions, however, remain unresolved, such as which is the most suitable endocrine manipulation and what is the optimal dose and duration of treatment. NSAIDs and interferons have demonstrated activity against AF either alone or in combination with hormone therapy or chemotherapy but the precise mechanism of action is still unknown. Finally, there is growing evidence in the literature that chemotherapy is effective against AF with almost one in two patients being likely to respond.

CONCLUSIONS

The evidence in the literature supports the opinion that both non-cytotoxic and cytotoxic chemotherapies are effective against AF. However, the lack of sufficient patient numbers and randomized trials compromises the validity of the reported results and mandates further investigation with properly designed prospective studies including larger patient numbers, with main end points to include not only tumor response rate and survival but also quality-of-life issues.

The role of p38 in UVA-induced cyclooxygenase-2 expression in the human keratinocyte cell line, HaCaT

We examined the expression of cycloxygenase-2, the rate-limiting enzyme in the production of prostaglandins, in the UVA-irradiated human keratinocyte cell line, HaCaT. UVA induced a dose-dependent increase in COX-2 at the protein level at 2 and 4 h post-irradiation and at the mRNA level at 1 and 2 h post-irradiation. Experiments using semi-quantitative RT-PCR demonstrate that UVA increased the half-life of the COX-2 message by more than fourfold in the presence of Actinomycin D (with a half life between 4 and 8 h post-irradiation), suggesting that UVA induction of COX-2 is post-transcriptionally regulated. Through the use of the specific p38 inhibitor, SB202190, increases in COX-2 message and protein levels were abrogated in UVA-irradiated cells. In UVA-irradiated cells treated with SB202190, the half-life of the COX-2 message was decreased to basal levels (between 1 and 2 h post-irradiation), indicating that p38 was responsible for the stabilization of the message. Luciferase activity was increased in UVA-irradiated cells transfected with reporter constructs containing the 3' UTR of COX-2, a region containing AU-rich elements (AREs). These regulatory sequences of AUUUA have been proposed as one mechanism of post-transcriptional regulation. Increases observed in luciferase activity could be decreased using a p38 dominant-negative construct. We report for the first that UVA can induce COX-2 expression in the human keratinocyte cell line, HaCaT. Additionally, p38 appears to play a critical role in the UVA-induced expression of COX-2 in these keratinocytes and may serve as a potential drug target in the chemoprevention of skin cancer.

The future of colon cancer prevention

Chemoprevention science is in flux owing to rapid advances in postgenomic technology. We have witnessed enormous advances in the areas of early detection and molecular profiling of colorectal carcinogenesis; however, unique interpretive and technologic challenges persist. Neoplastic hallmarks must be iteratively tested and validated as markers of risk, targets for intervention, and/or markers of response in order to expedite the development of preventive interventions. In this review, we highlight several of the technologies that are revolutionizing our understanding of carcinogenesis and our approach to colorectal cancer prevention.

Synergistic effect of indomethacin with adriamycin and cisplatin on tumor growth

In this study, we have examined the antitumor effect of combined administrations of indomethacin (IND) with chemotherapeutic drugs on tumor growth. Colon 26 clone 20 (C20) cells and monocyte chemotactant protein-1 (MCP-1) transfected C20 cells (C20betaA-2-1) were used and these cells were inoculated into the footpad of BALB/c mice. At day 1 after tumor inoculation, treatment with 0.001% IND via the drinking water was commenced. At days 4, 6, and 8, adriamycin or cisplatin was administered intravenously at a dose of 5 mg/kg or intraperitoneally at a dose of 2 mg/kg, respectively. Although IND, adriamycin and cisplatin only partially reduced the growth of the C20 tumors after treatment with each drug on its own, a marked synergistic effect was observed when they were given in combination. A synergistic effect between IND and cisplatin on C20betaA-2-1 was also observed. However, IND itself showed no suppression of C20betaA-2-1 tumor growth. These results suggest that combination of indomethacin with chemotherapeutic drugs could be an effective form of cancer chemotherapy. The observed effects may be dependent on the expression of MCP-1.

Cyclooxygenase-2 as a target for prevention of colorectal cancer

COX-2 is an isoenzyme of cyclooxygenase that is increased in response to growth factors, cytokines, and other mitogenic stimuli. Upregulation of COX-2 gene expression and functional activity is an early event in colorectal tumor formation. The long-term use of cyclooxygenase inhibitors, such as aspirin and nonsteroidal anti-inflammatory drugs, is associated with a decreased rate of colorectal tumors. This observation holds across a range of experimental models, from animal genetic tumor models to large epidemiologic studies of human sporadic colorectal cancer. Selective inhibitors of COX-2 were primarily developed to treat COX-2-related inflammation with minimal side effects. These drugs, however, may also provide safe, effective chemoprevention of colorectal neoplasia.

Sulindac inhibits growth of rat colon carcinoma by inducing apoptosis

Sulindac possesses an inhibitory effect on colorectal cancer development. Rat colon cancer cells, ACL-15, inoculated subcutaneously in F344 rats were used. Sulindac was administered at 8 mg/kg twice daily for 7 consecutive days. Sulindac group and control group were compared regarding tumor volume and body weight. At sacrifice, the tumors were collected and examined for tumor-infiltrating lymphocytes, apoptotic index, and microvessel density. The tumor volume in the sulindac group was significantly smaller than that in the control group. Body weight, microvessel density, and tumor-infiltrating lymphocyte score were not significantly different between the two groups. The apoptotic index was significantly higher in the sulindac group than in the control group. Sulindac inhibited tumor growth by inducing apoptosis. These findings may be helpful in designing new treatment strategies in colorectal cancer patients.

Acetaminophen selectively reduces glioma cell growth and increases radiosensitivity in culture

Glioblastoma multiforme (GBM) is a highly lethal brain cancer. Using cultures of rodent and human malignant glioma cell lines, we demonstrated that millimolar concentrations of acetylsalicylate, acetaminophen, and ibuprofen all significantly reduce cell numbers after several days of culture. However, their mechanisms of action may vary, as demonstrated by (1) differences in the morphological changes produced by these compounds; (2) varied responses to these drugs with respect to toxicity kinetics; and (3) respective rates of cell proliferation, DNA synthesis, and mitotic index. We studied the effects of acetaminophen on relative cell number further. Evidence is presented that acetaminophen induced cell death by an apoptotic mechanism after a brief burst of mitosis in which cell numbers increased transiently, followed by a reduction in cell number and an increase in DNA fragmentation, as evidenced by terminal deoxytransferase-mediated dUTP-biotin nick end labeling (TUNEL) analysis. Using cultures of adult human brain and embryonic rat brain, we demonstrated that glioma cells were several-fold more sensitive to acetaminophen than normal brain cells in culture. Finally, subtoxic doses of acetaminophen increased the sensitivity of the human glioma cells in culture to ionizing radiation. Taken together, these results suggest that acetaminophen may prove to be a useful therapeutic agent in the treatment of human brain tumors.

Eicosanoids and the large intestine

During the past three decades, many studies have been conducted to determine the precise role of eicosanoids in colorectal physiology and pathophysiology. This research has increased our understanding of bioactive lipid signaling, and may contribute to the development of more effective therapeutic modalities for digestive diseases in the future. The purpose of this report is to provide a brief overview of the role of eicosanoids in the colon and rectum. This information has been organized according to both functional and disease-related categories. The role of eicosanoids in colonic secretion, motility, inflammatory bowel disease, and colorectal neoplasia will be discussed.

The role of COX-2 in intestinal cancer

Cyclooxygenase (COX), the key regulatory enzyme for prostaglandin synthesis is transcribed from two distinct genes. COX-1 is expressed constitutively in most tissues, and COX-2 is induced by a wide variety of stimuli and was initially identified as an immediate-early growth response gene. In addition, COX-2 expression is markedly increased in 85-90% of human colorectal adenocarcinomas, whereas COX-1 levels remain unchanged. Several epidemiological studies have reported a 40-50% reduction in the risk of developing colorectal cancer in persons who chronically take such nonsteroidal anti-inflammatory drugs (NSAIDs) as aspirin, which are classic inhibitors of cyclooxygenase. Genetic evidence also supports a role for COX-2, since mice null for COX-2 have an 86% reduction in tumor multiplicity in a background containing a mutated APC allele. These results strongly suggest that COX-2 contributes to the development of intestinal tumors and that inhibition of COX is chemo-preventative.

[Aspirin against cancer]

PURPOSE

That aspirin as an anti-aggregative and anti-inflammatory compound might prevent tumor spread is an old concept that is still not of clinical relevance. To date, aspirin has been shown in several epidemiologic studies to be linked with a reduction of colorectal cancer incidence, as well as the incidence of lung and breast cancer. In this issue, we have summarized the mechanisms that support this hypothesis, and we have analysed the main clinical studies.

RESULTS

Only case-control studies and most of the prospective cohort studies showed a reduction of colorectal cancer incidence in regular aspirin users. Nevertheless, the minimum effective doses of aspirin and the duration of therapy remain unclear. To date, only one prospective randomized trial has evaluated the influence of aspirin in the prevention of colorectal cancer. Despite the inclusion of 22,000 subjects and a five-year follow-up, aspirin failed to show any protection. The mechanism of the potential role of aspirin in preventing cancer, primarily supposed to rely on the antiprostaglandin effect, is now under debate. Few studies have evaluated the prevention of other cancers, such as breast or lung cancers, by aspirin. Data remain too sparse to allow any conclusion.

CONCLUSION

The role of aspirin in the prevention of colorectal cancer still needs further studies, such as a prospective randomized study, which should be conducted in a high-risk population.

The role of cyclooxygenases in inflammation, cancer, and development

The cyclooxygenase (COX) enzymes catalyze a key step in the conversion of arachidonate to PGH2, the immediate substrate for a series of cell specific prostaglandin and thromboxane synthases. Prostaglandins play critical roles in numerous biologic processes, including the regulation of immune function, kidney development, reproductive biology, and gastrointestinal integrity. There are two COX isoforms, which differ mainly in their pattern of expression. COX-1 is expressed in most tissues, whereas COX-2 usually is absent, but is induced by numerous physiologic stimuli. Surprisingly, disruption of Cox1 (Ptgs1) in the mouse did not result in gastrointestinal abnormalities. cox-2 (Ptgs2) null mice show reproductive anomalies and defects in kidney development. Epidemiologic, animal, and human data indicate that NSAIDs, inhibitors of cyclooxygenase, are chemopreventive for colon cancer. COX-2 is overexpressed in 50% of benign polyps and 80-85% of adenocarcinomas. Offspring from cox-2 null by Apcdelta716 matings exhibit an 86% reduction in polyp number when compared to offspring from control animals, thus providing genetic evidence that COX-2 contributes to tumor formation or growth. The in vivo mechanism by which COX-2 affects tumor growth has not been determined. It is possible that both tumor and stromally derived COX-2 could influence tumor angiogenesis and/ or immune function.

Inhibitors of prostaglandin synthesis do not improve food intake or body weight of tumor-bearing rats

Interleukin-1 (IL-1) and tumor necrosis factor (TNF) are immunoregulatory cytokines that mediate many aspects of the acute phase response to infection and injury. It has been hypothesized that these cytokines mediate the onset of the cachexia-anorexia syndrome with tumor growth. The anorexigenic effects of IL-1 are mediated in part by prostaglandins (PG). Therefore, the purpose of the present study was to determine if administration of ibuprofen (ibu) or indomethacin (indo), which inhibit PG synthesis, would affect the food intake and body weight of tumor-bearing rats. Rats were implanted with the Morris 7777 hepatoma, a tumor known to induce anorexia and weight loss in rats, and weight loss and leukocyte synthesis of IL-1 and TNF in mice. Treatment with indo or ibu did not improve food intake or body weight in the tumor-bearing rats. However, administration of ibu coincident with tumor implantation did result in smaller tumor mass compared to placebo-treated controls. The results of the present study suggest that PG synthesis is not a major factor in the onset of anorexia in this animal model of tumor-induced anorexia. However, further studies of the effects of inhibitors of PG synthesis on the kinetics of tumor growth are clearly indicated.

Intracellular measurement of prostaglandin E2: effect of anti-inflammatory drugs on cyclooxygenase activity and prostanoid expression

Cyclooxygenase (COX) converts arachidonic acid to prostaglandin (PG) H2, which is further metabolized to various prostaglandins, prostacyclin and thromboxane A2. COX exists in at least two different isoforms. COX-1 is constitutively expressed, whereas COX-2 is induced by proinflammatory stimuli. Prostaglandin E2 is a major metabolite of COX activation. In order to compare the activity of target ligands and COX inhibitors on PGE2 synthesis and release, the responsiveness of several cell lines to the calcium ionophore A23187, bacterial lipopolysaccharide (LPS), nonsteroidal anti-inflammatory drugs (NSAIDs), and the glucocorticoid, dexamethasone, were investigated. For intracellular measurements, the culture supernatant was aspirated, and the cells were thoroughly washed and lysed with dodecyltrimethylammonium bromide. Intracellular and secreted PGE2 were measured with an enzyme immunoassay. A23187 and LPS increased intracellular PGE2 in a dose-dependent manner. Kinetic experiments with A23187-stimulated mouse 3T3 fibroblast cells revealed a distinct biphasic response in COX activity. In the presence of NSAIDs or dexamethasone, there was a dose-dependent inhibition in intracellular PGE2 with A23187-stimulated 3T3 cells. Inhibitory studies demonstrated an apparent increased sensitivity of COX activity to the action of inhibitors when measuring intracellular PGE2 compared with using cell culture supernatants. Indeed, intracellular PGE2 levels were comprehensively reduced in the presence of low concentrations of inhibitor. The utilization of cell culture lysates and, in particular, measurement of intracellular PGE2 should prove useful for identifying new COX inhibitors.

Cyclooxygenase-2 inhibitors in tumorigenesis (Part II)

The rate-limiting step in arachidonate metabolism is mediated by enzymes known as cyclooxygenases (COXs). These enzymes catalyze the biosynthesis of prostaglandin H2, the precursor of molecules such as prostaglandins, prostacyclin, and thromboxanes. The COX enzyme family consists of the classical COX-1 enzyme, which is constitutively expressed in many tissues, and a second isozyme, i.e., COX-2, which is induced by various stimuli, such as mitogens and cytokines, and is involved in many inflammatory reactions. Because nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit both COX-1 and COX-2, these drugs also cause unwanted side effects, exemplified by gastrointestinal bleeding. Accumulating evidence indicates that NSAIDs can reduce the incidence of colorectal cancers in human and experimental animals and can reduce the number and size of polyps in patients with familial adenomatous polyposis. This Part II (of a two-part review) focuses on the growing clinical and experimental evidence that NSAIDS and COX-2 inhibitors can influence the risk of colon (and possibly of other) cancers.

Management of desmoid tumors in patients after ileal pouch-anal anastomosis for familial adenomatous polyposis

PURPOSE

The aim of this study was to review the management of desmoid tumors in patients who have undergone ileal pouch-anal anastomosis for familial adenomatous polyposis and their outcome.

METHODS

A retrospective review of case notes was undertaken in a series of 196 patients with familial adenomatous polyposis who had had an ileal pouch-anal anastomosis. Eleven patients were identified in whom desmoid tumor had developed (4 male; median age, 30 (range, 16-43) years).

RESULTS

Desmoid tumors developed in the abdominal wall alone in 4 of 11 patients. Three enlarging tumors were resected with no subsequent recurrence. No patient received adjuvant treatment and pouch function remained stable at a median follow-up of eight years. Mesenteric desmoid tumors developed in seven patients; the pouch has been excised in two because of ischemia; two other patients have had defunctioning stomas created because of slow progression of their desmoid tumors. One patient had a single-lumen pouch excised and a new S-pouch inserted, with no subsequent recurrence of the desmoid tumor, and in two patients the mesenteric desmoid tumor has remained unchanged. All of these patients received long-term Clinoril (sulindac, Merck & Co., Inc., West Point, PA). Although there has been no significant deterioration in pouch function in patients in whom the pouch remains in situ, the pouch function was significantly worse compared with a control group of patients after ileal pouch-anal anastomosis for familial adenomatous polyposis in whom desmoid tumors did not develop.

CONCLUSION

Desmoid tumors developed in 5.6 percent of 196 patients after ileal pouch-anal anastomosis for familial adenomatous polyposis. No patient with abdominal-wall desmoid tumor had a recurrence after local excision. By contrast, mesenteric desmoid tumors eventually resulted in pouch failure in four of seven affected patients.

Tumor cell-endothelial cell interactions: evidence for roles for lipoxygenase products of arachidonic acid in metastasis

Adhesion of tumor cells (TC) to endothelial cells (EC) is necessary for movement of TC out of the interstitium to form metastatic deposits. This interaction may be influenced by proadhesive molecules such as lipoxygenase products of arachidonic acid metabolism. We studied the effect of inflammatory stimuli, A23187 calcium ionophore, n-formyl-methionyl-leucine-phenylalanine (FMLP) and phorbol myristate acetate (PMA) on TC-EC interaction. Adherence of metastatic breast tumor cell line (MCF-7), choriocarcinoma cell line (JEG-3), and non metastatic pituitary cell (GH-3) were assayed as the number of radiolabeled TC attached to EC (cpm/well). TC and EC were incubated with A23187, FMLP, and PMA for varying time periods. Lipoxygenase products (LTB4, 5-HETE) were measured under basal and stimulated conditions using RP-HPLC and RIA. There were no differences in basal adherence of TC lines to EC. When EC were incubated with stimuli, there were significant increases in the numbers of MCF-7 and JEG-3 cells adherent to EC compared to GH-3. Light and phase contrast microscopy confirmed that TC were attached to EC. Upon stimulation, GH-3 preferentially produced prostaglandins (PGI1(2)) while MCF-7 and JEG-3 produced lipoxygenase products (LTB4 and 5-HETE). Pre-incubation of MCF-7 and JEG-3 with the lipoxygenase inhibitor nordihydroguiaretic acid resulted in partial inhibition of adhesion to EC. Our data strongly indicate a role for lipoxygenase products of arachidonic acid in adherence of TC to EC.

Desmoids in familial adenomatous polyposis

Clinical desmoid disease affect approximately 10 per cent of patients with familial adenomatous polyposis (FAP); the subclinical rate is unknown. Desmoids are probably neoplastic rather than regenerative in origin and may arise in association with germline or somatic mutations at or beyond codon 1444 of the APC gene. Intra-abdominal desmoids behave unpredictably but are an important cause of death in those with FAP. Signal intensity on magnetic resonance imaging reflects tumour cellularity, which in part determines progression, and this may help management. Surgical treatment of advanced desmoids is hazardous, but medical treatments have limited success. Chemotherapy with doxorubicin and dacarbazine is currently under evaluation.

Sulindac and indomethacin inhibit formation of aberrant crypt foci in the colons of dimethyl hydrazine treated rats

Aberrant crypt foci are microscopic lesions found in the colons of rodents treated with carcinogens, and in patients with premalignant colorectal conditions. They consist of single or multiple abnormal crypts and show cellular changes ranging from dysplasia to microscopic adenomacarcinoma. It is thought that these lesions represent the initial stages of the adenomacarcinoma path that results in the development of colorectal neoplasia. We have examined the effect of sulindac and indomethacin on the formation of aberrant crypt foci in rats treated with dimethylhydrazine (DMH). Aberrant crypt foci were induced in male Sprague-Dawley rats with two oral doses of dimethyl hydrazine at 25 mg/kg per dose. Rats were randomized to receive sulindac at 3 mg/kg (n = 20) or 10 mg/kg (n = 18) b.d., indomethacin at 1 mg/kg per day (n = 18) or 2 mg/kg per day (n = 19) or control (n = 37). Drug treatment was started on the day following the first dose of carcinogen and continued for 3 weeks. Colons were fixed flat overnight in 10% formalin and stained with 0.2%. Methylene Blue solution before being studied. There was a significant reduction in the number of aberrant crypt foci in rats treated with 10 mg/kg b.d., sulindac (P = 0.001) and indomethacin at 2 mg/kg per day (P = 0.0002). Sulindac, at 3 mg/kg b.d., and indomethacin, at 1 mg/kg per day, did not have a statistically significant effect (P = 0.089 and P = 0.052, respectively). None of the drug treatments affected the relative frequency of single crypt vs multiple crypt foci. Previous studies have shown that sulindac and indomethacin will significantly inhibit the growth and development of tumours in DMH treated rats. The current data suggest that one of the pathways of action of NSAID is to inhibit the formation of early preneoplastic lesions.

Binding of estradiol to whole prostatic DU-145 cells in the presence and absence of tamoxifen and acetylsalicylic acid

Conflicting results have been obtained with regard to the estradiol receptor (ER) capacity of human prostatic tissue. Human prostatic DU-145 cells have been found to be ER-negative with immunohistochemical assays. The object of this investigation was to determine if whole DU-145 cells, which had been grown in monolayer culture, have ER and, if so, to confirm the finding with antiestrogens. After cells had been lysed, a Bmax of 44.7 +/- 4.0 fmol/mg (Kd = 0.6 +/- 0.6 nM) was obtained. Subcellular localization studies showed that the estrogen receptor level in the cytoplasmic fraction was approximately 10 times higher than in the nuclear fraction. Competitive binding studies showed that tamoxifen, DES, and acetylsalicylic acid decreased estradiol binding. The dissociation constants and relative affinities for tamoxifen, DES, and acetylsalicylic acid were 0.2 nM (281.7%), 0.2 nM (224.0%), and 0.8 nM (78.43%), respectively. However, 5 alpha-dihydrotestosterone and metabolites of acetylsalicylic acid had no effect in competitive binding studies. These results may contribute to a better understanding of prostatic carcinogenesis, which may in turn lead to more effective treatment.

Influence of zymosan (a non-specific macrophage stimulator) and of indomethacin on liver tumours--an experimental study in rats

Zymosan--a non-specific macrophage-stimulating agent--reduces tumour take in the liver. The mechanism for this effect is not clear, but it may be mediated via the Kupffer cells and prostaglandins. On the other hand, the Prostaglandin-synthesis inhibitor, indomethacin, inhibits tumour growth. Pretreatment with zymosan (3 mg 100 g-1) for 3 days of two different strains of rats, inoculated in the liver with a hepatoma or an adenocarcinoma cell suspension respectively, reduced tumour take and also initial tumour growth. The effect on tumour take and initial growth was inhibited by concomitant administration of indomethacin (0.2 mg 100 g-1). When zymosan was administered after tumour cell inoculation the growth rate of the hepatoma was retarded, but this effect was not abrogated by indomethacin. Pretreatment with indomethacin had no significant effect on tumour take or initial growth. When given after the tumour was established in the liver, indomethacin reduced the growth rate of the hepatoma, but not of the adenocarcinoma. These results suggest that there are different mechanisms for the effects of zymosan on tumour take and on growth of an established tumour. In immunoincompetent nude mice the effect on the hepatoma was similar to the effect in the rat. In vitro both tumours were insensitive to zymosan and indomethacin. This study confirms that pretreatment with a non-specific macrophage stimulator (zymosan) diminishes tumour take and growth in the liver, that the effect of zymosan on tumour take in the liver is abrogated by indomethacin and that the zymosan effect on tumour take in the liver is at least partly mediated by the Kupffer cells and prostaglandins.

In vitro effects of prostaglandin E1 and indomethacin on mitomycin C-induced sister-chromatid exchanges in mitogen-stimulated human lymphocytes

In this study, the individual and combined effects of prostaglandin E1 (PGE1) and Indomethacin on mitomycin C (MMC)-induced SCEs in human lymphocytes was investigated in vitro. All MMC-treated cultures showed a great increase of SCEs (approximately two-fold), indicating its ability to induce mutations. SCE data showed that MMC-induced SCEs were reduced significantly in the presence of PGE1 in pooled analysis of six experiments (60.55% reduction of SCEs at 10(-6) M, 34.13% reduction of SCEs at 10(-9) M). In contrast the presence of indomethacin in the medium during MMC treatment of cells failed to show a significant reduction of SCEs in pooled analysis (21.17%). However, individual analyses revealed only two of six donors with a significant SCE response. Thus, the findings suggest that PGE1 can modify the DNA damaging effect of carcinogens and thereby may prevent the initiation of the carcinogenic process.

Growth inhibition of rat glioma cells in vitro and in vivo by aspirin

The effect of non-steroidal anti-inflammatory drugs (NSAIDs), acetylsalicylic acid (commonly known as aspirin), salicylic acid, piroxicam and indomethacin on the growth of rat glioma cells (RG 2) in vitro and aspirin in vivo was studied. The in vitro studies reveal that aspirin and salicylic acid strongly inhibit growth of rat glioma (RG 2) cells in concentrations used in medicine for treatment of rheumatic diseases. On the other hand, indomethacin and piroxicam had no effect, indicating that the inhibitory effect on tumor growth is not due to the inhibition of prostaglandin synthesis. The synthesis of ATP was markedly reduced (34% of control) in the presence of drugs, whereas protein synthesis measured as 3H-leucine incorporation was slightly more inhibited (73% of control) than cell growth. Aspirin administered to Fischer 344 rats inhibited growth of RG 2 cells inoculated into the caudate nucleus in vivo, both when administered the day before inoculation of tumor cells and when tumors had formed, i.e. 5 days post inoculation.

Do NSAIDs exert their colon cancer chemoprevention activities through the inhibition of mucosal prostaglandin synthetase?

Nonsteroidal antiinflammatory drugs (NSAIDs) have considerable potential as chemopreventive agents for colorectal cancer. Recent case-control drug surveillance and large cohort studies found that patients with regular aspirin use had a reduced incidence of colorectal cancer and/or decreased death rate from this disease. Several different NSAIDs reduce formation of both colon adenomatous polyps (the precursor lesion of colon cancer) and cancers in experimental animals given known carcinogens. Perhaps most convincing are reports that the NSAID sulindac promotes regression and inhibits recurrence of adenomatous colon polyps in patients with adenomatous polyposis coli. The best characterized pharmacologic effect of the NSAIDs is their reduction of prostaglandin synthesis by inhibiting prostaglandin synthetase PGE2, which catalyzes the formation of prostaglandin precursors from arachidonic acid. Several lines of evidence are contrary to the concept that inhibition of prostaglandin synthesis is central to the NSAIDs' chemopreventive effects. Relatively high levels of prostaglandins have been reported to inhibit tumor cell growth both in vivo and in vitro, and to inhibit differentiation in some tumor cell lines. We evaluated comparative chemopreventive effects on colon tumor formation in an azoxymethane (AOM)-induced colon carcinogenesis rat model using the NSAIDs piroxicam, sulindac, and sulindac sulfone, a metabolite of sulindac which lacks the anti-prostaglandin synthetase activity typically associated with NSAID-induced gastrointestinal toxicities. The results demonstrate that sulindac sulfone, a compound lacking anti-prostaglandin synthetase activity, inhibits AOM-induced colon cancer in rats. Substantial dose-dependent reductions in both tumor burden and tumor multiplicity were observed in the sulindac sulfone-treated animals.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of misoprostol on colon cancer

A synthetic prostaglandin E1 (PGE1) analogue, misoprostol, was investigated for its effects on the growth of colon cancer in two in vivo models. Human colon cancer cell lines C170, LIM2412 and LIM2405 were grown as subcutaneous xenografts on T-lymphocyte deficient ARC(s) nu/nu mice. Tumour volumes were found to be significantly inhibited compared with control in misoprostol-treated animals with two cell lines. C170 was inhibited by 70.5% (P = 0.0001) and LIM2412 by 68.2% (P = 0.01). LIM2405 was inhibited by 33% (P = 0.14) which was not significantly different from the control. In a second experiment, colon cancers were induced in Sprague-Dawley rats using 1,2 dimethyl-hydrazine (DMH). After 10 weeks of treatment, rats were randomized to receive a 5 week course of 20 micrograms/kg per day of oral misoprostol. Misoprostol-treated rats were found to have a similar tumour incidence and staging compared with control animals. Oral administration of misoprostol has an inhibitory effect on early tumour growth of some colonic cancers, but not on established tumours.

Ingestion of aspirin prevents platelet-induced human fibroblast growth. Implications for peptic ulcer healing

Because aspirin (ASA) may affect peptic ulcer healing through actions on platelets (for example, by inhibiting release of growth factors), human foreskin fibroblast mitogenesis was used for two bioassays (24-h growth with 3H-thymidine incorporation and 5- to 6-day cell proliferation) for serum derived from collagen-aggregated platelet-rich plasma (PRP) or platelet-poor plasma (PPP) or from clotted whole blood (WBS). Blood was taken from five normal subjects before and 6 h after ingestion of ASA. After ASA ingestion serum (WBS or PRP) was less mitogenic (p < 0.01) by both bioassays, whereas PPP serum was not mitogenic either before or after ASA. In vitro, neither ASA nor salicylic acid alone at levels normally found in plasma with ASA use inhibited fibroblast growth. We conclude that ASA ingestion inhibits the mitogenic action of platelets on fibroblast culture by inhibiting the release of putative growth factors. Such an effect might explain the adverse effects of ASA on ulcer healing.

Role of Acetylsalicylic Acid in Cytokine Stimulation of Macrophages in Antibody-Dependent Cellular Cytotoxicity (ADCC)

In addition to the spectrum of biological action already known to be exhibited by acetylsalicylic acid (ASA) as an analgesic, anti-inflammatory and platelet aggregation inhibitor, there is growing evidence of a stimulatory effect on the immune system. ASA has been found to increase the production ofcytokines and to increase the activity of various leukocytes. The action of ASA on the activity of mouse peritoneal macrophages was therefore investigated in the present study. Therapeutically effective concentrations of ASA, which are known to decrease levels of prostaglandins, had neither a stimulating nor an inhibiting influence on antibody-dependent cellular cytotoxicity (ADCC) or on the binding capacity of macrophages with regard to SW 948 tumour cells. Likewise ASA had little or no adverse effect on the capacity of the macrophages for stimulation by interferon-gamma (IFN-gamma) and interleukin-4 (IL-4). Taken together, the immunostimulant effect of ASA shown in the literature as an increased production of interleukin-2 (IL-2) and IFN, could not be confirmed on the basis of the macrophage cytotoxiclty.

Mechanistic considerations in chemopreventive drug development

This overview of the potential mechanisms of chemopreventive activity will provide the conceptual groundwork for chemopreventive drug discovery, leading to structure-activity and mechanistic studies that identify and evaluate new agents. Possible mechanisms of chemopreventive activity with examples of promising agents include carcinogen blocking activities such as inhibition of carcinogen uptake (calcium), inhibition of formation or activation of carcinogen (arylalkyl isothiocyanates, DHEA, NSAIDs, polyphenols), deactivation or detoxification of carcinogen (oltipraz, other GSH-enhancing agents), preventing carcinogen binding to DNA (oltipraz, polyphenols), and enhancing the level or fidelity of DNA repair (NAC, protease inhibitors). Chemopreventive antioxidant activities include scavenging reactive electrophiles (GSH-enhancing agents), scavenging oxygen radicals (polyphenols, vitamin E), and inhibiting arachidonic acid metabolism (glycyrrhetinic acid, NAC, NSAIDs, polyphenols, tamoxifen). Antiproliferation/antiprogression activities include modulation of signal transduction (glycyrrhetinic acid, NSAIDs, polyphenols, retinoids, tamoxifen), modulation of hormonal and growth factor activity (NSAIDs, retinoids, tamoxifen), inhibition of aberrant oncogene activity (genistein, NSAIDs, monoterpenes), inhibition of polyamine metabolism (DFMO, retinoids, tamoxifen), induction of terminal differentiation (calcium, retinoids, vitamin D3), restoration of immune response (NSAIDs, selenium, vitamin E), enhancing intercellular communication (carotenoids, retinoids), restoration of tumor suppressor function, induction of programmed cell death (apoptosis) (butyric acid, genistein, retinoids, tamoxifen), correction of DNA methylation imbalances (folic acid), inhibition of angiogenesis (genistein, retinoids, tamoxifen), inhibition of basement membrane degradation (protease inhibitors), and activation of antimetastasis genes. A systematic drug development program for chemopreventive agents is only possible with continuing research into mechanisms of action and thoughtful application of the mechanisms to new drug design and discovery. One approach is to construct pharmacological activity profiles for promising agents. These profiles are compared among the promising agents and with untested compounds to identify similarities. Classical structure-activity studies are used to find optimal agents (high efficacy with low toxicity) based on good lead agents. Studies evaluating tissue-specific and pharmacokinetic parameters are very important. A final approach is design of mechanism-based assays and identification of mechanism-based intermediate biomarkers for evaluation of chemopreventive efficacy.

Application of chemical immunomodulators to the treatment of cancer and AIDS

A number of potential advantages, development of promising new agents, and the discovery of synergy with cytokines or cell products continue to spur research into the application of chemical immunomodulators for the treatment of cancer and AIDS. In preclinical in vitro and in vivo systems, chemical immunomodulators definitely modulate the immune system and have therapeutic efficacy. Although clinical trials have shown the ability of these agents to modulate the human immune system, thus far chemical immunomodulators have generally not fulfilled the therapeutic promise generated in animal models for the treatment of human diseases. While the discrepancy in results between animal models and human trials is obvious, the basis is not apparent. Species differences in elimination kinetics, presentation of active drug at the site of action, and the development of tachyphylaxis have been postulated as reasons for the minimal activity of these agents in humans. In addition, the use of investigational techniques established for cytotoxic agents may not be appropriate for immunomodulators. As with any immunomodulator, determining an optimal immunostimulatory dose and schedule and applying the therapy to patients with minimal tumor burden would perhaps be more appropriate than use of a maximally tolerated dose in patients with advanced disease. A dose-immunological effect relationship has recently been demonstrated for levamisole at doses higher than those used for many years in levamisole trials (99). While research and clinical investigation have identified several potentially useful chemical immunomodulators, the elementary understanding of the biochemical mechanisms involved in immunoregulation remains basic. Future research must elucidate these mechanisms, particularly in humans, to maximize the benefits of chemical immunomodulators as single agents or combined with cytotoxic chemotherapeutic agents, surgery, radiation therapy, other immunomodulators, and antiviral agents.

The effect of sulindac on colon polyps: circumvention of a transformed phenotype--a hypothesis

Sulindac suppresses the growth of colon polyps in Gardner syndrome and familial adenomatous polyposis. The mechanism of action is not known. The problems are to ascertain the significance of high prostaglandin concentrations in transformed cells, colon polyps and cancers and to explain how sulindac restores normal growth patterns. A few clinical observations and an abundance of experimental data can be integrated to produce a reasonable model based on current biochemical and physiologic concepts. A fundamental defect in the formation of colon polyps is mutation of the APC (adenomatous polyposis coli) gene that leads to inadequate suppression of proliferation. There is high PGE2 content in colon polyps and cancers, presumably the result of stimulation by protein kinase C (PKC). In small quantities it stimulates cyclic AMP production but with persistent high concentrations it desensitizes and down-regulates specific PG receptors and inactivates adenylate cyclase, cAMP synthesis, and the cAMP-dependent mechanism for control of proliferation. The PKC pathway is thereby unopposed. It is hypothesized that restriction of PG synthesis by sulindac is accompanied by resensitization of PG receptors, and reactivation of the cAMP-dependent pathway for control of cell growth. It is further postulated that restoration of cAMP synthesis and protein kinase A activity converts a functionally inadequate mutant APC suppressor gene to one sufficient to inhibit colon polyp formation.

Treatment of colonic and rectal adenomas with sulindac in familial adenomatous polyposis

BACKGROUND

Familial adenomatous polyposis is an autosomal dominant disorder characterized by the formation of hundreds of colorectal adenomas and eventual colorectal cancer. Administration of the nonsteroidal antiinflammatory drug sulindac has been followed by regression of polyps in patients with this disorder, but no controlled trial of this drug in patients who have not had surgery has been reported.

METHODS

We conducted a randomized, double-blind, placebo-controlled study of 22 patients with familial adenomatous polyposis, including 18 who had not undergone colectomy. The patients received sulindac at a dose of 150 mg orally twice a day for nine months or identical-appearing placebo tablets. The number and size of the polyps were evaluated every three months for one year.

RESULTS

A statistically significant decrease in the mean number of polyps and their mean diameter occurred in patients treated with sulindac, as compared with those given placebo. When treatment was stopped at nine months, the number of polyps had decreased to 44 percent of base-line values and the diameter of the polyps to 35 percent of base-line values (P = 0.014 and P < 0.001, respectively, for the comparison with the changes in the group given placebo). No patient had complete resolution of polyps. Three months after treatment with sulindac was stopped, both the number and the size of the polyps increased in sulindac-treated patients but remained significantly lower than the values at base line. No side effects from sulindac were noted.

CONCLUSIONS

Sulindac reduces the number and size of colorectal adenomas in patients with familial adenomatous polyposis, but its effect is incomplete, and it is unlikely to replace colectomy as primary therapy.

Acetylsalicylic acid has no effects on various isolated immune cells in vitro

In addition to the well known biological effects of acetylsalicylic acid (ASA), its stimulating effect on the immune system has recently been described. In the present study, therefore, the influence of ASA on isolated leucocytes was investigated in vitro. Various concentrations of ASA, representing therapeutic concentrations, had neither an inhibitory nor a stimulating influence on the cytotoxicity of CD16-positive cells. The phytohaemagglutinin-induced proliferation of lymphocytes and the phagocytosis activity of monocytes and neutrophilic granulocytes was similarly unaffected. These results would indicate that the immunostimulating effects already described for ASA cannot be examined in isolated leucocytes in vitro and should be attributed to an interaction of various effector cells in vivo.

A model system for studying nutritional interventions on colon tumor growth: effects of marine oil

Lipid nutrition effects were evaluated on the growth of a transplantable colon tumor (CT-26) at various sites in the BALB/c mouse. CT-26 implanted into the back or flank of these mice grew well independent of the quality or quantity of fat in the diet. However, when implanted in the mid-portion of the descending colon, tumor growth was related to the level of dietary saturated (coconut oil) or n-6 unsaturated (safflower oil) fat in the diet. Similar findings were obtained when the tumor was utilized in a pulmonary colonization assay. Dietary marine oil (mainly EPA, and DHA n-3 polyunsaturated oils) was found to markedly impair the growth of CT-26 implanted in the bowel and lung, but not in the back. Thus, CT-26 exhibits nutrition responsiveness at certain sites, but not at others. This may help to explain contradictory findings concerning dietary lipids in certain studies. Inhibition of tumor growth by marine oils may afford preventive or chemotherapeutic implications as its mode of action unfolds. Histologic findings in bowel tumors from mice fed marine oil but not other oils revealed focal areas of necrosis. It is appreciated that arachidonate metabolism is competitively interfered with by EPA in both cyclooxygenase and lipoxygenase pathways. The possibility is raised that the metabolism of marine oils in this model system may generate lipid peroxidation products to a greater extent than n-6 lipids and in turn is associated with focal areas of necrosis. A model system of nutritionally non-responsive and nutritionally responsive sites for the post-promotional growth of a bowel tumor affords the opportunity to explore lipid effects with control and test tumors in hosts fed identical lipid nutriture.