Growth inhibition of transplantable murine colon adenocarcinoma 38 by indomethacin

Mechanistic contribution of ubiquitous 15-lipoxygenase-1 expression loss in cancer cells to terminal cell differentiation evasion

Loss of terminal cell differentiation promotes tumorigenesis. 15-Lipoxygenase-1 (15-LOX-1) contributes to terminal cell differentiation in normal cells. The mechanistic significance of 15-LOX-1 expression loss in human cancers to terminal cell differentiation suppression is unknown. In a screen of 128 cancer cell lines representing more than 20 types of human cancer, we found that 15-LOX-1 mRNA expression levels were markedly lower than levels in terminally differentiated cells. Relative expression levels of 15-LOX-1 (relative to the level in terminally differentiated primary normal human-derived bronchial epithelial cells) were lower in 79% of the screened cancer cell lines than relative expression levels of p16 (INK4A), which promotes terminal cell differentiation and is considered one of the most commonly lost tumor suppressor genes in cancer cells. 15-LOX-1 was expressed during terminal differentiation in three-dimensional air-liquid interface cultures, and 15-LOX-1 expression and terminal differentiation occurred in immortalized nontransformed bronchial epithelial but not in lung cancer cell lines. 15-LOX-1 expression levels were lower in human tumors than in paired normal lung epithelia. Short hairpin RNA-mediated downregulation of 15-LOX-1 in Caco-2 cells blocked enterocyte-like differentiation, disrupted tight junction formation, and blocked E-cadherin and ZO-1 localization to the cell wall membrane. 15-LOX-1 episomal expression in Caco-2 and HT-29 colon cancer cells induced differentiation. Our findings indicate that 15-LOX-1 downregulation in cancer cells is an important mechanism for terminal cell differentiation dysregulation and support the potential therapeutic utility of 15-LOX-1 reexpression to inhibit tumorigenesis.

Increased toxicity and lack of efficacy of Rofecoxib in combination with chemotherapy for treatment of metastatic colorectal cancer: A phase II study

Preclinical and clinical models have demonstrated that cyclooxygenase-2 (COX-2) is overexpressed in primary and metastatic colorectal tumors. In preclinical models, there appears to be additive or synergistic effects when combining 5-Fluorouracil (5-FU) with nonsteroidal anti-inflammatory agents (NSAIDs) for the treatment of colorectal neoplasms. This data raised the question as to whether adding a COX-2 inhibitor to 5-FU-based regimens would increase the response rates with an acceptable toxicity profile in patients with metastatic colon cancer. In the current study, patients with metastatic colorectal cancer, who were either untreated or previously treated (more than 1 year ago) with adjuvant 5-FU and Leucovorin (LV) received 5-FU and LV (Mayo regimen) in addition to Rofecoxib. Tumor samples from all patients exhibited evidence of moderate COX-2 over-expression. 4 patients entered on the study developed upper gastrointestinal bleeding (grade III). Other toxicities included grade II stomatitis (3 patients), grade II thrombocytopenia (1 patient), grade II diarrhea (2 patients) and grade I nausea (1 patient). There were no partial or complete responses in the first 10 patients entered on the study so the study was terminated (probability of success < 0.3 with type 1 error of 0.05 and power of 0.8). Thus, Rofecoxib did not appear to increase antitumor activity and resulted in increased gastrointestinal toxicity when combined with 5-FU/LV. Future studies will need to consider the added gastrointestinal toxicity of Rofecoxib when combined with chemotherapy for the treatment of patients with colorectal cancer.

Treatment and survival study in the C57BL/6J-APC(Min)/+(Min) mouse with R-flurbiprofen

Our previous studies with the mouse model of familial adenomatous polyposis (FAP), C57BL/6J-APC(Min)/+ or Min mouse, demonstrated the optimal dose for adenoma reduction with R-flurbiprofen was 10 mg/kg/day as an undivided dose. Divided doses exhibited no increased efficaciousness. This study examines 10 mg/kg R-flurbiprofen daily (qd) on survival as well as a second daily (q.o.d.) schedule and compares it with sulindac sulfone. The q.o.d. schedule at 10 mg/kg was equally efficacious as qd treatment at the same dose. For the q.o.d. group, tumor number decreased similarly (p<0.01); while body weight gain (p<0.01), hematocrit and average tumor area (both, p<0.05) were improved compared with qd treatment. Treatment with R-flurbiprofen (10 mg/kg/day) increased survival significantly (p=0.0004, log-rank) compared to vehicle treated animals. Major biological endpoints (hematocrit, weight gain, tumor number, average and total area [99% reduction]) were significantly improved in treated animals (p<0.01). Sulindac sulfone treatment (50 mg/kg/day) of the Min mouse produced no significant biological benefit. The dose schedule study suggests that for tumor reduction it is necessary to attain a threshold drug-level but not necessarily sustain it over 24 hrs (pharmacodynamic t1/2 >> pharmacokinetic t1/2). During the period of administration R-flurbiprofen dramatically prolongs survival for the mouse model of the human disease, FAP.

The marked anticancer effect of combined VCR, MTX, and indomethacin against drug-resistant recurrent small cell lung carcinoma after conventional chemotherapy: report of a case

In a previous study, we discovered that indomethacin was an effective modulator of the sensitivity of pulmonary carcinoma cells to vincristine (VCR), methotrexate (MTX), adriamycin (ADR), and etoposide (VP-16). We describe herein the case of a 61-year-old-man with multiple brain, lung, liver, and bone metastases from small cell lung carcinoma (SCLC) that recurred after intensive chemotherapy, who showed no signs of remission following conventional chemotherapy. The general condition of the patient deteriorated until he required morphine sulfate to control his severe diffuse pain. In an attempt to improve this patient's quality of life (QOL), he was discharged from hospital and treated at the outpatient clinic with modulation therapy using indomethacin as an anodyne instead of morphine sulfate. Signs of almost complete remission to only one cycle of combination therapy with VCR, MTX, and indomethacin were observed without any obvious adverse effects. This case report serves to demonstrate that modulation therapy combined with VCR, MTX, and indomethacin may be useful in the treatment of patients with drug-resistant recurrent SCLC.

Indomethacin suppresses the growth of colon 26, Meth-A and FM3A tumors in mice by reducing the prostaglandin E2 content and telomerase activity in tumor tissues

The antitumor effect of indomethacin on Colon 26, Meth-A and FM3A tumors was investigated in mice. The prostaglandin E2 content in tumor tissues was assayed to find out if indomethacin acts on tumors, and the telomerase activity in tumors and somatic tissues (testis, liver, spleen and colon) was also monitored during indomethacin treatment. Growth of Colon 26, Meth-A and FM3A tumors was significantly (P < 0.001-0.05) suppressed by indomethacin compared to the untreated controls. The prostaglandin E2 content in the three tumors was markedly (P < 0.001) reduced by indomethacin. Telomerase activity in Colon 26 and FM3A tumors was significantly (P < 0.001) lower than that of untreated tumors (80% and 45% decrease versus the controls, respectively), and the activity in Meth-A tumor was slightly decreased (10% decrease versus the control) by indomethacin. Telomerase activity in the somatic tissues was not significantly affected by indomethacin. In summary, this study shows the effectiveness of indomethacin as an antitumor agent against three types of tumors, and suggests that indomethacin affects telomerase activity in tumors in vivo.

NSAID-induced polyp regression in familial adenomatous polyposis patients

NSAIDs inhibit prostaglandin synthesis. In 1983, Waddell et al first reported that sulindac, a NSAID (Clinoril), caused regression of rectal adenomatous polyps in several patients with familial adenomatous polyposis, an inherited form of colorectal cancer. Subsequently, NSAIDs have been used as chemopreventive agents in animal carcinogenesis models and adenoma regression had been confirmed in human trials with sulindac. This article summarizes these developments and describes possible mechanisms of colorectal neoplasia chemoprevention.

Antiproliferative effects of the enantiomers of flurbiprofen

Nonsteroidal antiinflammatory drugs (NSAIDs) are recognized for inhibiting growth of colon tumors in animal models, and for reducing the risk of colon cancer in humans. The mechanisms involved have not been established, but are thought to be related to reduced prostaglandin biosynthesis. The present study investigates the effect of COX-inhibiting and non-COX-inhibiting enantiomers of flurbiprofen on rat colonocyte proliferation. Intestinal ulceration was used as a surrogate indicator of COX inhibition. Sprague Dawley rats were treated orally with 6.3 mg/kg of R- or s-flurbiprofen or vehicle. Colonocyte labeling index and small bowel ulcer index were measured. R-flurbiprofen and S-flurbiprofen significantly reduced colonocyte labeling index, by 34% and 23% respectively, compared with vehicle. R-flurbiprofen caused minimal ulcer formation (4.48 mm2) compared with S-flurbiprofen (94.4 mm2). These findings suggest that R-flurbiprofen-mediated control of colonocyte proliferation is independent of prostaglandin biosynthesis.

Dietary fat and colon cancer

Dietary fat in general, and perhaps animal and polyunsaturated fats in particular, appear to increase colon carcinogenesis in animal models and epidemiologic studies. This observation holds the potential to shed light on the underlying mechanisms of colorectal carcinogenesis and reduce morbidity and mortality from the disease by dietary and chemoprevention. While research continues into the relationship between prostglandins and other putative mediators of the effects of fats on the colon, we can suggest that a diet which protects against colorectal cancer would be low in fat with most of that fat coming from vegetable sources. Prospective dietary trials are ongoing which may strengthen or modify these preliminary recommendations.

Effect of splenectomy on hepatic metastasis of colon carcinoma and natural killer activity in the liver

We have previously demonstrated that administration of killed streptococcal preparation (OK432), a biological modifier, increased the number of asialo GM1-positive cells in the liver, enhanced NK activity of hepatic mononuclear cells, and reduced the number of hepatic metastases of colon 38 adenocarcinoma that were inoculated into the superior mesenteric vein of C57BL/6 strain mice. In the present study, to clarify the role of the spleen in immune surveillance of the liver, the effect of splenectomy on hepatic metastasis of colon carcinoma and on hepatic NK activity has been examined. The number of hepatic metastasis increased in the splenectomized mice, compared with that in sham-operated mice. Administration of OK432 increased the number of asialo GM1-positive cells in the liver and enhanced NK activity of hepatic mononuclear cells in both groups, but NK activity of hepatic mononuclear cells in the splenectomized mice was less than that of the sham-operated mice. An enhanced NK activity of these cells was abolished by treatment with anti-asialo-GM1 antibody plus complement in vitro. Interleukin-2 mRNA expression was increased in the spleen 2 hr after OK432 administration and persisted until 8 hr, but was scarcely noted in the liver. On the other hand, NK activity of hepatic mononuclear cells in the asialo GM1-positive cell-depleted (previous administration of antiserum against asialo GM1) mice was enhanced after OK432 administration in the sham operated and splenectomized mice, but an enhanced NK activity in these mice was only partially or not at all abolished by treatment with anti-asialo GM1 antibody plus complement in vitro, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of nonsteroidal anti-inflammatory drugs in colorectal cancer prevention

Colorectal cancer is the second leading cause of cancer death in the U.S.A. Recent research suggests that nonsteroidal anti-inflammatory drugs (NSAIDs) are effective in the prevention of colorectal neoplasia. This review summarises the results of research in animals and humans of these compounds in preventing tumours of the colorectum.

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.

Piroxicam and other cyclooxygenase inhibitors: potential for cancer chemoprevention

Piroxicam is a nonsteroidal anti-inflammatory drug (NSAID) widely used for treatment of inflammatory arthritis. Recent experimental and clinical studies suggest that piroxicam, as well as other NSAIDs, may be useful for chemoprevention of colon cancer. While there is less information regarding NSAIDs for chemoprevention of urinary bladder malignancy, there are compelling data which suggest that this should be evaluated. A major effect of NSAIDs is inhibition of cyclooxygenase, the rate-limiting enzyme for conversion of arachidonic acid to important signal molecules, including prostaglandins, which profoundly affect cellular functions in many tissues. The initial enzyme reaction leading to formation of prostaglandin H can be accompanied by cooxidation of xenobiotics resulting in extrahepatic and local tissue production of reactive products which are carcinogenic. The end product prostaglandins, especially prostaglandin E2 (PGE2), are biological modifiers which can significantly affect cell proliferation and tumor growth. High levels of PGE2 stimulate growth of certain tumor cell lines while inhibition of prostaglandin synthesis with indomethacin or piroxicam can cause suppression. The mechanisms for this effect are unclear. Studies in cultured cells exposed to indomethacin show inhibition of G1-to-S phase progression of the cell cycle and a reduction in overall DNA synthesis. It is unclear whether this effect on cell growth results from some direct action of the NSAID or a reduction in prostaglandins or indirectly from modulation of important control signals, such as calcium flux. In addition to cyclooxygenase, NSAIDs can inhibit activity of other enzymes, including phosphodiesterases and cyclic GMP-AMP protein kinases, which may be central to cancer initiation and promotion. NSAIDs can also interfere with transmembrane ion fluxes and with cell-to-cell binding. Prostaglandins can modulate a variety of immunological responses and thereby play an important role in host antitumor immunity. For example, high levels of tissue PGE2 are frequently associated with suppression of immune surveillance and killing of malignant cells. Conversely, immune responses are generally enhanced by drugs that inhibit prostaglandin synthesis. PGE2 can act as a feedback inhibitor for cellular immune processes, such as T-cell proliferation, lymphokine production, and cytotoxicity. This effect is also seen for macrophage activity and natural killer cell toxicity. In general, either increased production of PGE2 or increased sensitivity to normal amounts of PGE2 results in depressed cellular immunity. Cyclooxygenase inhibitors (NSAIDs) such as piroxicam which decrease PGE2 production can stimulate cellular immune function both in vitro and in vivo. A variety of tumor cell lines and human malignancies produce large quantities of prostaglandins.(ABSTRACT TRUNCATED AT 400 WORDS)

Relationship between blood plasma prostaglandin E2 and liver and lung metastases in colorectal cancer

The relationship of prostaglandin E2, of which a large amount is produced in various neoplasms, and hematogenous distant metastases was investigated in a total of 44 colorectal cancer patients because of its varied pathophysiologic potentials. The authors found significantly high levels of PGE2 in local venous blood draining the carcinoma and in peripheral blood in cases with liver or lung metastasis, as well as a significantly large amount of PGE2 production in the carcinoma tissue. The results suggest that increased local blood PGE2 could enhance the metastasis formation, and increased peripheral blood PGE2 may be useful in the detection of such metastasis in colorectal cancer.

Modulation of methylcholanthrene-induced carcinogenesis in the uterine cervix of mouse by indomethacin

The present paper reports the chemopreventive action of indomethacin on methylcholanthrene (MCA)-induced carcinogenesis in the uterine cervix of virgin young adult Swiss albino mice. Placement of a sterile cotton thread impregnated with beeswax containing approx. 600 micrograms of MCA produces cervical tumors in 91% mice in 16 weeks. When such carcinogen-containing threads are inserted into the uterine cervix of mice fed diets containing indomethacin at the dose levels of 10 mg/kg, 20 mg/kg and 40 mg/kg diet for two pre-insertion weeks plus 16 post-insertion weeks, the cervical tumor incidences were 83%, 65% and 26% (P less than 0.01), respectively. It is concluded that indomethacin, when given in the diet at sufficiently high concentration, significantly inhibits MCA-induced cervical carcinogenesis.

Antimetastatic effect of bromelain with or without its proteolytic and anticoagulant activity

Bromelain, a pineapple-derived plant product, added to C57Bl/6 mice laboratory chow decreased lung metastasis of Lewis lung cancer cells implanted s.c. This antimetastatic potential was demonstrated by both the active and inactive bromelain with or without proteolytic, anticoagulant properties.

Antitumor effects of inhibitors of arachidonic acid cascade on experimentally induced intestinal tumors

The antitumor action of inhibitors of cyclooxygenase (indomethacin) and lipoxygenase activity (nordihydroguaiaretic acid) of arachidonic acid cascade was investigated in the chemically induced large bowel tumors in Sprague-Dawley rats. Indomethacin treatment completely prevented the carcinogenic effect of methylazoxymethanol. Thus, no tumors were found in the 14 rat test group, compared with 13 of 14 tumor-bearing rats in the untreated control group. Although nordihydroguaiaretic acid treatment does not abolish prostaglandin synthesis, it does reduce the effect of the carcinogen and tumors were found in only five of 14 treated rats. From this study it can be postulated that not only is reduction in prostaglandin formation responsible for the inhibition of tumor growth, but also leukotrienes may play some role.

Role of macrophage in the defense against intestinal cancers

The capability of activated macrophages to kill tumor cells in vitro is now well documented. The tumoricidal activation of macrophages against intestinal tumor cells by different agents is described and the main hypothesis on the mechanisms of tumor cell killing in vitro are discussed. These in vitro results suggest that the macrophage can constitute an efficient effector cell in the defense against intestinal tumors. The distribution and ratio of macrophages in normal intestine and intestinal tumors is described. At the moment, potent activators of macrophages studied in vivo on experimental and human intestinal tumors give poor results or even enhance the growth of tumors. Macrophages may also interfere with the specific immune response in two directions by enhancing the immune response or decreasing it by elaboration of mediators such as prostaglandins.