Expression of cytokines, TNF-alpha and IL-1 alpha, in MAM acetate and 1-hydroxyanthraquinone-induced colon carcinogenesis of rats

Evaluation of immunologic and intestinal effects in rats administered an E 171-containing diet, a food grade titanium dioxide (TiO2)

The toxicity of dietary E 171, a food grade titanium dioxide was evaluated. A recent study reported rats receiving E 171 in water developed inflammation and aberrant crypt foci (ACF) in the gastrointestinal tract. Here, rats received food containing E 171 (7 or 100 days). The 100-day study included feeding E 171 after dimethylhydrazine (DMH) or vehicle only pretreatment. Food consumption was similar between treatment groups with maximum total cumulative E 171 exposure being 2617 mg/kg in 7 days and 29,400 mg/kg in 100 days. No differences were observed due to E 171 in the percentage of dendritic, CD4+ T or Treg cells within Peyer's patches or the periphery, or in cytokine production in plasma, sections of jejunum, and colon in 7- or 100-day E 171 alone fed rats. Differences were observed for IL-17A in colon (400 ppm E 171 + DMH) and IL-12p70 in plasma (40 ppm E 171 + DMH). E 171 had no effect on histopathologic evaluations of small and large intestines, liver, spleen, lungs, or testes, and no effects on ACF, goblet cell numbers, or colonic gland length. Dietary E 171 administration (7- or 100-day), even at high doses, produced no effect on the immune parameters or tissue morphology.

Improving the therapeutic efficiency of ginger extract for treatment of colon cancer using a suitably designed multiparticulate system

Ginger extract (GE), a potential natural anticancer agent, has compromised therapeutic utilization due to poor bioavailability and physicochemical properties. Present study aimed at assigning GE with a pharmaceutical couture so as to improve its biopharmaceutical performance by monitoring its localized (though prolonged) delivery in the distal parts of gastrointestinal tract for the treatment of colon cancer. Alginate beads entrapping 85.9 ± 1.78% GE were subjected to Eudragit S100 coating. Latter is insoluble at acidic and near neutral (6.8) pH of stomach and upper part of small intestine and it led to 50% retardation (upto 12 h) in release of GE. However, it was solubilised at pH > 7.0 resulting in colon targeted system. Developed beads were free flowing, showed a particle size of 0.9 ± 0.006 mm and super class-II release controlled by swelling and polymer relaxation. Preclinical evaluation using 1,2-dimethylhydrazine-induced colon cancer, in male Wistar rats, in terms of histopathology, oxidative stress, mitochondrial complex activity, β-glucuronidase and ammonia concentration determinations indicated GE loaded beads (50 mg/kg) to be significantly better (p < 0.05) than free GE. Highlight of the study was that GE loaded coated alginate beads were administered after the induction of colon cancer and significant recession of the cancers was observed after 4 weeks of treatment.

Aloe vera non-decolorized whole leaf extract-induced large intestinal tumors in F344 rats share similar molecular pathways with human sporadic colorectal tumors

Aloe vera is one of the most commonly used botanicals for various prophylactic and therapeutic purposes. Recently, NTP/NCTR has demonstrated a dose-dependent increase in large intestinal tumors in F344 rats chronically exposed to Aloe barbadensis Miller (Aloe vera) non-decolorized whole leaf extract (AVNWLE) in drinking water. The morphological and molecular pathways of AVNWLE-induced large intestinal tumors in the F344 rats were compared to human colorectal cancer (hCRC) literature. Defined histological criteria were used to compare AVNWLE-induced large intestinal tumors with hCRC. The commonly mutated genes (Kras, Ctnnb1, and Tp53) and altered signaling pathways (MAPK, WNT, and TGF-β) important in hCRC were evaluated within AVNWLE-induced large intestinal tumors. Histological evaluation of the large intestinal tumors indicated eight of twelve adenomas (Ads) and four of twelve carcinomas (Cas). Mutation analysis of eight Ads and four Cas identified point mutations in exons 1 and 2 of the Kras gene (two of eight Ads, two of four Cas), and in exon 2 of the Ctnnb1 gene (three of eight Ads, one of four Cas). No Tp53 (exons 5-8) mutations were found in Ads or Cas. Molecular pathways important in hCRC such as MAPK, WNT, and TGF-β signaling were also altered in AVNWLE-induced Ads and Cas. In conclusion, the AVNWLE-induced large intestinal tumors in F344 rats share several similarities with hCRC at the morphological and molecular levels.

Mouse models for the study of colon carcinogenesis

The study of experimental colon carcinogenesis in rodents has a long history, dating back almost 80 years. There are many advantages to studying the pathogenesis of carcinogen-induced colon cancer in mouse models, including rapid and reproducible tumor induction and the recapitulation of the adenoma-carcinoma sequence that occurs in humans. The availability of recombinant inbred mouse panels and the existence of transgenic, knock-out and knock-in genetic models further increase the value of these studies. In this review, we discuss the general mechanisms of tumor initiation elicited by commonly used chemical carcinogens and how genetic background influences the extent of disease. We will also describe the general features of lesions formed in response to carcinogen treatment, including the underlying molecular aberrations and how these changes may relate to the pathogenesis of human colorectal cancer.

Lack of interleukin-4 receptor alpha chain-dependent signalling promotes azoxymethane-induced colorectal aberrant crypt focus formation in Balb/c mice

Interleukin (IL)-4 receptor (IL-4R) alpha chain-dependent signalling by IL-4 and IL-13 promotes tumour growth and metastasis in mouse models of colorectal cancer. However, the role of IL-4R alpha-dependent signalling during the early, pre-malignant stages of colorectal carcinogenesis has not been investigated. Therefore, we investigated the effect of deletion of the IL-4R alpha gene on azoxymethane-induced colorectal aberrant crypt focus (ACF) multiplicity and size in Balb/c mice. IL-4R alpha(-/-) mice developed significantly more ACFs [median 8, inter-quartile range (IQR) 4-11.5; n = 9] than wild-type (WT) animals (median 4, IQR 1-6; n = 9; p = 0.04, Mann-Whitney U-test). There were significantly higher levels of IL-4 in serum from azoxymethane- and sham-treated IL-4R alpha(-/-) mice than WT animals, but no difference in serum IL-13 levels. In the absence of functional IL-4Rs, IL-13 can also signal via the IL-13R alpha2 receptor, leading to induction of transforming growth factor (TGF) beta, which has pro-tumourigenic activity at early stages of intestinal tumourigenesis. We found that mucosal TGFbeta mRNA levels and intestinal epithelial cell TGFbeta immunoreactivity were significantly higher in IL-4R alpha(-/-) mice than in WT animals. In summary, IL-4R alpha-dependent signalling has a protective, anti-neoplastic role during the post-initiation phase of azoxymethane-induced colorectal carcinogenesis in Balb/c mice. Our data should prompt thorough investigation of the role of IL-4R alpha-dependent signalling during human colorectal carcinogenesis, particularly as antagonism of IL-4R signalling represents a therapeutic strategy for asthma and other allergic diseases.

Lactoferrin modifies apoptosis-related gene expression in the colon of the azoxymethane-treated rat

Lactoferrin, an iron-binding glycoprotein, exhibits suppressive effects on development of azoxymethane (AOM)-induced tumors in the rat colon, but the mechanisms are largely unknown. In this study, we investigated the effect of lactoferrin on the gene expression of 10 apoptosis-related molecules in colon mucosa of AOM-treated rats during early and late stages of colon carcinogenesis by reverse transcription PCR. Here we document that a death-inducing receptor, Fas, and a pro-apoptotic Bcl-2 family member, Bid, are increased in the colon mucosa in proportion to decreases in AOM-induced aberrant crypt foci by lactoferrin. Similarly, increased expression of the pro-apoptotic Bcl-2 family member, Bax, was also observed in AOM-induced tumors in rats fed by lactoferrin. These results indicate that Fas and pro-apoptotic Bcl-2 members participate in the lactoferrin action and may contribute to suppressive effects on tumor development in the rat colon.

Nitric oxide differentially regulates pro- and anti-angiogenic markers in DLD-1 colon carcinoma cells

Inducible nitric oxide (NO) synthase (iNOS) appears to be a marker of tumor progression in colon carcinogenesis. Here we investigated effects of NO on selected chemokines that differentially regulate angiogenesis, namely pro-angiogenic interleukin (IL)-8 as well as tumor-suppressive interferon-inducible protein-10 (IP-10) and monokine induced by interferon-gamma (MIG). These chemokines are expressed by DLD-1 colon carcinoma cells after stimulation with IL-1beta/interferon-gamma. Expression of IL-8 was markedly upregulated by NO. Moreover, NO enhanced expression of vascular endothelial growth factor (VEGF). In contrast, expression of IP-10 and MIG was suppressed by NO. The present data are consistent with previous observations that link NO to enhanced tumor angiogenesis and imply that NO-mediated upregulation of IL-8 and VEGF as well as downregulation of IP-10 and MIG may contribute to this phenomenon.

Preventive Effect of Juzen-taiho-to on Endometrial Carcinogenesis in Mice Is Based on Shimotsu-to Constituent

Juzen-taiho-to, a Kampo formula, originally consists of a mixture of Shimotsu-to and Shikunshi-to formulas together with two other crude ingredients. Juzen-taiho-to is reported to have a preventive effect on endometrial carcinogenesis in mice. Shimotsu-to exerts an inhibitory effect on estrogen-induced expression of c-fos, interleukin (IL)-1alpha and tumor necrosis factor (TNF)-alpha in uteri of ovarectomized mice. In the present study, short- and long-term experiments were designed to determine the effects of Juzen-taiho-to and Shimotsu-to on the estrogen-related endometrial carcinogenesis in mouse uteri, associated with the expression of cyclooxygenase (COX)-1 and -2. In the short-term experiment, exposure to Juzen-taiho-to or Shimotsu-to significantly reduced estradiol-17beta (E(2))-stimulated expressions of COX-2 mRNA (p<0.05) as well as the protein. However, no effects on the expression of COX-1 were observed. Shikunshi-to did not affect COX expression. In the long-term experiment, 90 female ICR mice were given N-methyl-N-nitrosourea (MNU) into their uterine corpora. The animals were divided into four groups as follows: group 1, a diet containing 0.07% Shimotsu-to and 5 ppm E(2); group 2, a diet containing 5 ppm E(2); group 3, a diet containing 0.07% Shimotsu-to; group 4 served as a control. Exposure of Shimotsu-to reduced the incidence of MNU- and E(2)-induced endometrial adenocarcinoma and atypical hyperplasia at the termination of the experiment (30 weeks). The above findings and our previous reports suggest that Shimotsu-to is responsible for the preventive effects of Juzen-taiho-to on estrogen-related endometrial carcinogenesis in mice, through the inhibition of estrogen-related COX-2 as well as c-fos, IL-1alpha and TNF-alpha expressions.

Shikonin modulates cell proliferation by inhibiting epidermal growth factor receptor signaling in human epidermoid carcinoma cells

Shikonin isolated from the roots of the Chinese herb Lithospermum erythrorhizon has been associated with anti-inflammatory properties. We evaluated shikonin's chemotherapeutic potential and investigated its possible mechanism of action in a human cutaneous neoplasm in tissue culture. Shikonin preferentially inhibits the growth of human epidermoid carcinoma cells concentration- and time-dependently compared to SV-40 transfected keratinocytes, demonstrating its anti-proliferative effects against this cancer cell line. Additionally, shikonin decreased phosphorylated levels of EGFR, ERK1/2 and protein tyrosine kinases, while increasing phosphorylated JNK1/2 levels. Overall, shikonin treatment was associated with increased intracellular levels of phosphorylated apoptosis-related proteins, and decreased levels of proteins associated with proliferation in human epidermoid carcinoma cells.

A novel inflammation-related mouse colon carcinogenesis model induced by azoxymethane and dextran sodium sulfate

To develop an efficient animal model for colitis-related carcinogenesis, male Crj: CD-1 (ICR) mice were given a single intraperitoneal administration (10 mg/kg body weight) of a genotoxic colonic carcinogen, azoxymethane (AOM), and a 1-week oral exposure (2% in drinking water) to a non-genotoxic carcinogen, dextran sodium sulfate (DSS), under various protocols. At week 20, colonic neoplasms (adenocarcinomas, 100% incidence with 5.60 +/- 2.42 multiplicity; and adenomas, 38% incidence with 0.20 +/- 0.40 multiplicity) with dysplastic lesions developed in mice treated with AOM followed by DSS. Protocols in which AOM was given during or after DSS administration induced a few tubular adenomas or no tumors in the colon. Immunohistochemical investigation of such dysplasias and neoplasms revealed that all lesions were positive for beta-catenin, cyclooxygenase-2 and inducible nitric oxide synthase, but did not show p53 immunoreactivity. The results indicate that 1-week administration of 2% DSS after initiation with a low dose of AOM exerts a powerful tumor-promoting activity in colon carcinogenesis in male ICR mice, and may provide a novel mouse model for investigating colitis-related colon carcinogenesis and for identifying xenobiotics with modifying effects.

Shimotsu-to is the agent in Juzen-taiho-to responsible for the prevention of endometrial carcinogenesis in mice

We have found that Juzen-taiho-to has a preventive effect on endometrial carcinogenesis in mice (Carcinogenesis 22 (2001) 587). In the present study, the constituents of Juzen-taiho-to responsible for this effect were explored using a short-term experiment. Thirty female ICR mice were divided into five groups: Group 1 was given a diet containing 0.2% of Juzen-taiho-to and 5ppm estradiol-17beta (E(2)); Group 2 was given a diet containing Shimotsu-to (0.07%) and E(2) (5ppm); Group 3 received Shikunshi-to (0.08%) and E(2) (5ppm) in the diet; Group 4 was given 5ppm E(2) in the diet; and Group 5 served as a control. Exposure of Juzen-taiho-to or Shimotsu-to decreased E(2)-stimulated expression of estrogen-related gene c-fos mRNA (P<0.05), and the cytokines interleukin-1alpha mRNA and tumor necrosis factor alpha mRNA P<0.01). A similar trend was not found upon treatment with Shikunshi-to. These findings suggest that Shimotsu-to is responsible for the inhibitory effects of Juzen-taiho-to on the estrogen-related endometrial carcinogenesis in mice.

Inhibitory effects of toremifene on N-methyl-N-nitrosourea and estradiol-17beta-induced endometrial carcinogenesis in mice

Short- and long-term experiments were designed to determine the effects of toremifene (TOR) on estrogen-related endometrial carcinogenesis in mice. In the short-term experiment, a single low dose of TOR (0.2 mg / 30 g body weight) decreased expression of c-fos, interleukin (IL)-1alpha, estrogen receptor (ER)-alpha mRNAs and corresponding proteins induced by estradiol-17beta (E(2)), in the uteri of the ovariectomized mice. Expression of ER-beta mRNA was increased by the TOR treatment, compared with the control. In the long-term experiment, 106 female ICR mice were given N-methyl-N-nitrosourea (MNU) into their uterine corpora. The animals were divided into four groups as follows: group 1, E(2) diet (5 ppm) plus TOR (0.2 mg / 30 g body weight, subcutaneously, every four weeks); group 2, E(2) diet alone; group 3, basal diet plus TOR. Group 4 served as the control. TOR treatment decreased the incidence of MNU and E(2)-induced endometrial adenocarcinoma and atypical hyperplasia at the termination of the experiment (30 weeks after the start). These results suggest that TOR exerts preventive effects against estrogen-related endometrial carcinogenesis in mice, through the suppression of c-fos as well as IL-1alpha expression induced by E(2). Such suppressive effects of TOR may be related to the decreased ER-alpha and increased ER-beta expressions.

Preventive effects of isoflavones, genistein and daidzein, on estradiol-17beta-related endometrial carcinogenesis in mice

The effects of isoflavones (genistein and daidzein) on endometrial carcinogenesis in mice were investigated in two experiments. In the short-term experiment (2 weeks), single subcutaneous (s.c.) administration of genistein [1 mg / 30 g body weight (b.w.)] significantly decreased the levels of estradiol-17beta (E(2)) (5 ppm in diet)-induced expression of c-jun, interleukin-1alpha (IL-1alpha) and tumor necrosis factor-alpha (TNF-alpha) mRNAs in the uteri of ovariectomized mice (P < 0.005, P < 0.05 and P < 0.01, respectively). Daidzein significantly inhibited E(2)-induced expression of c-fos and IL-1alpha (P < 0.01, P < 0.01 respectively). In the long-term experiment (30 weeks), 140 female ICR mice were given N-methyl-N-nitrosourea-containing solution (1 mg / 100 g b.w.) and normal saline (as controls) into their left and right uterine corpora, respectively. They were divided into six groups; group 1 was given E(2) (in diet) alone. Group 2 was given E(2) and genistein (1 mg / 30 g b.w., s.c., every four weeks). Group 3 was exposed to E(2) and daidzein (1 mg / 30 g b.w., s.c., every four weeks). Groups 4 and 5 respectively received genistein and daidzein, and were kept on the basal diet. Group 6 was kept on the basal diet and served as a control. At the termination of the experiment, incidences of endometrial adenocarcinoma and atypical endometrial hyperplasia of the group given E(2) and genistein or daidzein were significantly lower than of the group with E(2) alone (P < 0.01 and P < 0.05, respectively). It is suggested that both genistein and daidzein have an inhibitory effect on estrogen-related endometrial carcinogenesis in mice, possibly by suppressing expression of estrogen-induced estrogen-related genes c-fos and c-jun, and internal cytokines IL-1alpha and TNF-alpha through a cytokine and estrogen receptor-mediated pathway.

Tenascin immunoreactivity in the large bowel and the liver in patients with colorectal cancer

The expression of tenascin in colorectal tumours and liver was investigated in 30 patients with colorectal adenocarcinomas. Tissue samples were immersion-fixed in 4% paraformaldehyde solution. Free-floating cryostat sections were incubated with monoclonal antibody against tenascin, and examined by light and electron microscopy. Tenascin immunostaining was positive in sub-basement membrane zones and in newly-formed connective tissue of the primary tumour and perisinusoidally in the liver. The immunoreactivity in the sub-basement membrane zones of tumour glands in well- and moderately-differentiated tumours was more intensely expressed compared to that in poorly-differentiated tumours (p = 0.007 and p = 0.001 respectively, chi2-test). Perisinusoidal tenascin deposition was more often detected in the liver of patients with well-differentiated tumours (p = 0.006, chi2-test). The presence of metastases was accompanied by low tenascin deposition (p < 0.005, Fisher's exact test). Ultrastructurally tenascin deposits were observed around single tumour cells and glands in the primary tumours, and close to hepatic stellate cells in the liver. Finally, the role of tenascin deposition in the stimulation of tumour cell proliferation and mobility is discussed.

Interleukin-1 family expression in human breast cancer: interleukin-1 receptor antagonist

We hypothesize that interleukin-1 alpha, beta, and receptor antagonist (IL-1 alpha, IL-1 beta, and IL-1 ra, respectively) are present and tumor cell associated in human breast cancer (HBC). We believe the levels of these cytokines in breast tumor homogenates relate to other known prognosticators of patient survival (i.e., estrogen receptor [ER] status). Our results demonstrated that, immunohistochemically, tumor cells express IL-1 alpha, IL-1 beta, and IL-1 ra in most specimens tested. In breast tissue homogenates, IL-1 alpha levels correlated inversely with ER levels (p < 0.06), whereas IL-1 ra levels correlated directly with both ER levels (p < 0.009) and IL-1 beta levels (p < 0.06). When analyzing cytokine levels for the ER (-) versus ER (+) patient groups, we found that in many instances these groups showed a different cytokine profile. These studies suggest that the IL-1 family of cytokines may be important in regulating protumorigenic activities within the HBC tumor microenvironment.

The significance of the expression of tumor suppressor gene DCC in human gliomas

Deleted in colorectal carcinoma (DCC) gene has been as a candidate of tumor suppressor genes, has been identified recently and is thought to relate to the metastatic potential in some cancers. We examined the gene in 60 human gliomas (26 glioblastomas multiforme (GBMs), 16 anaplastic astrocytomas (AAs), 6 low grade astrocytomas (LGAs) of WHO Grade II, and 11 recurrent gliomas) and A172 human GBM cell line by reverse transcription polymerase chain reaction (RT-PCR). Twenty (77%) GBMs, 11 (69%) AAs, and 1 (17%) LGA revealed the reduced or absent DCC expression. Reduced DCC expression was also shown in 10 (91%) recurrent gliomas. Furthermore, in 5 cases with both primary and recurrent GBM, the DCC expressions of all recurrent tumors were lower than those of primary tumors. No significant correlation between DCC expression and Mib-1 labeling index was confirmed. The survival rate of patients without reduced DCC expression was significantly superior to that of patients with reduced DCC expression in overall malignant astrocytic tumors. In GBM and AA separately, DCC expression also tended to correlate with patient's prognosis. These results suggest that reduced DCC expression is an important marker in tumor malignancy and recurrence in astrocytic tumors and that may be a useful prognostic factor in patients with malignant astrocytic tumors.

Superoxide dismutases in relation to the overall survival of colorectal cancer patients

Reactive oxygen metabolites are implicated in the initiation and promotion of cancer. In addition, oxidant scavengers, such as manganese--(Mn-SOD) and copper/zinc--superoxide dismutase (Cu/Zn-SOD), are thought to contribute to colorectal cancer treatment response. In the present study, the prognostic significance of the Mn- and Cu/Zn-SOD antigen content of normal mucosa and carcinomas of 163 patients with colorectal cancer was evaluated in comparison with major clinicopathological parameters, with respect to the 5-year overall survival. The Mn-SOD content of carcinomas was found to be significantly higher than that of normal mucosa, whereas there was no difference in the Cu/Zn-SOD content between the normal mucosa and carcinomas. No association was demonstrable between the Mn-SOD and Cu/Zn-SOD content of the tissues and the assessed clinicopathological parameters (gender, age, localization, differentiation grade, diameter and Dukes' stage), with the exception of the Cu/Zn-SOD and the differentiation grade of the carcinomas. Univariate analysis showed that a high Mn-SOD content of carcinomas was associated with a poor 5-year overall survival of the patients with colorectal cancer. Multivariate analysis including all clinicopathological parameters revealed that this Mn-SOD parameter was prognostically independent. The Mn- and Cu/Zn-SOD content of normal mucosa and the Cu/Zn-SOD content of carcinomas were not associated with the overall survival of the patients. In conclusion, this study demonstrates that for patients with colorectal cancer the Mn-SOD content of colorectal carcinomas has a significant prognostic value that is independent from major clinicopathological parameters, including Dukes' stage.

Inhibitory effects of nabumetone, a cyclooxygenase-2 inhibitor, and esculetin, a lipoxygenase inhibitor, on N-methyl-N-nitrosourea-induced mammary carcinogenesis in rats

We investigated the modifying effects of nabumetone, a relatively selective cyclooxygenase-2 inhibitor, and esculetin, a lipoxygenase inhibitor, on N-methyl-N-nitrosourea(MNU)-induced mammary carcinogenesis in female Sprague-Dawley rats. A total of 124 rats, 6 weeks old, were divided into 6 groups. At 50 days of age, groups 1, 2, and 3 were treated with MNU (50 mg/kg body weight) by subcutaneous injection. From the age of 8 weeks, groups 2 and 4 were given 0.03% nabumetone in the diet and groups 3 and 5 were given 0.03% esculetin in the diet. All rats were necropsied at the termination (25 weeks after the start of experiment). The incidence and multiplicity of neoplasms in group 2 were significantly smaller than those in group 1 (P < 0.005 and P < 0.001, respectively). The incidence of neoplasms in group 3 was also significantly smaller than that in group 1 (P < 0.05). These results indicate that the intake of nabumetone or esculetin during the time corresponding to the post initiation phase has a chemopreventive effect on MNU-induced mammary carcinogenesis in rats.

Inhibitory effect of NS-398, a selective cyclooxygenase-2 inhibitor, on azoxymethane-induced aberrant crypt foci in colon carcinogenesis of F344 rats

Prostaglandin E2, which is produced by cyclooxygenase (COX) during arachidonic acid metabolism, is considered to be related to colon carcinogenesis. Therefore, the effect of NS-398 (N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide), a COX-2 inhibitor, was examined in azoxymethane (AOM)-induced colon carcinogenesis in rats in this study. In the first experiment, groups 1-3 were treated with AOM (15 mg/kg, s.c.) 3 times at intervals of a week from 5 weeks of age. Groups 2 and 3 were respectively given 1 mg/kg and 10 mg/kg of NS-398 in 5% gum arabic aqueous solution 3 times per week by oral gavage during the experiment. Six weeks after the first exposure to AOM, aberrant crypt foci (ACF) were counted in the colonic mucosa of all rats. The mean occurrence of ACF per length in rats given 1 mg/kg b.w. or 10 mg/kg b.w. of NS-398 was reduced to 65.7% or 52.8%, respectively, of that in rats treated with only AOM. Levels of COX-2 mRNA expression in groups treated with AOM, regardless of NS-398, were slightly higher than that in the group treated with NS-398 alone as judged from reverse transcription-polymerase chain reaction analysis. In the second experiment, the effect of NS-398 at different times, i.e., during initiation and post-initiation, was examined. Treatment with NS-398 in both phases significantly inhibited the appearance of ACF. The results imply that NS-398 might have a chemopreventive potential.

Overexpression of matrix metalloproteinase-2 and tissue inhibitor of matrix metalloproteinase-2 in liver from patients with gastrointestinal adenocarcinoma and no detectable metastasis

Degradation of basement membranes is a key step in tumoral invasion, mainly mediated by matrix metalloproteinases (MMPs) and their inhibitors (TIMPs). Since the liver is a main target for metastases from gastrointestinal adenocarcinoma, we have investigated MMP2 and TIMP2 expression by RT-PCR, in situ hybridization and zymography in the liver of patients with gastrointestinal adenocarcinomas and no detectable hepatic metastasis (n = 12), in tumoral and nontumoral liver from patients with hepatic metastasis (n = 9) and in control liver (n = 4). MMP2 and TIMP2 mRNA levels were increased in liver from patients with gastrointestinal adenocarcinomas and no detectable metastasis, compared with those of either control liver (5-fold and 3.2-fold, respectively) or nontumoral areas of liver from patients with metastasis (7.8-fold and 3-fold, respectively). MMP2 and TIMP2 transcripts were located in mesenchymal cells of portal tracts and sinusoids. MMP2 was mainly in its latent form. In liver from patients with hepatic metastasis, the tumoral/nontumoral ratios for MMP2 and TIMP2 mRNA were 6.2 +/- 4 and 1.5 +/- 0.4, respectively. Both transcripts were localized in the stromal cells of liver metastases, and the active form of MMP2 was found only in the tumoral areas. In the matching nontumoral areas the signals for MMP2 and TIMP2 mRNA were restricted to mesenchymal cells in portal tracts and sinusoidal cells. Our data show that liver stromal cells express high levels of MMP2 and TIMP2 in patients with colonic carcinoma without liver metastasis, suggesting the distant induction of these transcripts by the primary tumor.

Carcinoma-associated collagen type III and type IV immune localization and Ito cell transformation indicate tumor-related changes in sinusoids of the human liver

The deterioration of extracellular matrix turnover is a key event in tumor progression. It has been assumed that Ito cell transformation is stimulated by tumor-derived factors. In the present study changes in the occurrence of collagen type III and IV and Ito cell transformation are described in the sinusoids of patients with malignant gastrointestinal tumors without liver metastases, and around metastatic liver tumors using routine histology, electron microscopy as well as light microscopical and ultrastructural immunohistochemistry. Dilated sinusoids filled with lymphoid cells and variable perisinusoidal fibrosis were detected light microscopically. Collagen type III and IV immune deposits were increased perisinusoidally. Ultrastructural immunohistochemistry showed increased staining in the space of Disse and around Ito and transitional cells for both types of collagen. Ito cells were transformed into transitional cells. Pit cells appeared in the inflammatory infiltrate in sinusoids. Ito cells were significantly increased in number pericentrally and periportally. It is suggested that stimuli, which can influence Ito cellular behaviour are produced by inflammatory cells in sinusoids, resident sinusoidal cells, tumor cells or by tumor stroma. It is concluded that transformed Ito cells and increased amounts of collagen type III and IV in sinusoids of patients with malignant tumors without liver metastases or around metastatic tumors may predict tumor-related alterations of liver parenchyma, which may serve as a barrier for further outgrowths of the cancer cells.

The mRNA overexpression of inflammatory enzymes, phospholipase A2 and cyclooxygenase, in the large bowel mucosa and neoplasms of F344 rats treated with naturally occurring carcinogen, 1-hydroxyanthraquinone

Inflammation has been considered to be related to carcinogenesis. Previously, we demonstrated that 1-hydroxyanthraquinone (1-HA), a naturally occurring carcinogen, induced severe inflammation such as ulcerative colitis in colonic mucosa. We also showed that indomethacin inhibited the tumorigenicity of 1-HA. In this study, we examined the expressions of major enzymes in arachidonic acid cascade related to inflammation in the colon mucosa of rats treated with 1-HA. After the treatment of 1% 1-HA diet, colon lesions were observed and RNA was extracted from mucosa and neoplasms. The mRNA expressions of group II phospholipase A2, cyclooxygenase-2 and 5-lipoxygenase, were examined by using a reverse transcriptase polymerase chain reaction. The expressions of phospholipase A2 and cyclooxygenase were significantly increased in non-neoplastic mucosa in rats treated with 1-HA compared with those in control rats. The expressions in the neoplasms induced by 1-HA were also increased. Phospholipase A2, especially, was much higher in the neoplasms than in non-neoplastic mucosa. However, the expression of 5-lipoxygenase showed no change in the non-neoplastic mucosa and neoplasms of rats treated with 1-HA, compared with that in control rats. These findings suggest that the inflammation induced by 1-HA may be related to the metabolites through a cyclooxygenase pathway, which indicates a prostaglandin synthesis, but not through a lipoxygenase pathway, which indicates a leukotriene synthesis in arachidonic acid cascade.

No involvement of Ki-ras or p53 gene mutations in colitis-associated rat colon tumors induced by 1-hydroxyanthraquinone and methylazoxymethanol acetate

1-Hydroxyanthraquinone (1-HA), which is present in some herbs, and methylazoxymethanol (MAM) acetate, a metabolite of azoxymethane, show synergistic carcinogenicity in rat colon, and 1-HA induces ulcerative changes with simultaneous severe inflammation of the entire colon. In this study, mutations in Ki-ras (exons 1 and 2) and p53 (exons 4-7) were studied by polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) analysis. Of 18 adenomas and 38 adenocarcinomas induced in male F344 rats (52 tumors induced by 1-HA plus MAM acetate, three by 1-HA alone, and one by MAM acetate alone), no mutations in Ki-ras or p53 were detected under two conditions of PCR-SSCP analysis. Because human colon carcinomas from patients with ulcerative colitis have a very low incidence of Ki-ras mutation, this experimental system would be a good animal model of human colon carcinomas with ulcerative colitis and of human colon carcinomas without Ki-ras or p53 mutations.

Reduced expression of phospholipase C-delta, a signal-transducing enzyme, in rat colon neoplasms induced by methylazoxymethanol acetate

Phospholipase C (PLC), which hydrolyzes phosphoinositides, has been implicated as a key enzyme in signal transduction. We examined the expression of an isozyme of PLC, PLC-delta, in rat colon neoplasms induced by methylazoxymethanol (MAM) acetate. Large-bowel neoplasms were observed in five of 10 rats given MAM acetate (25 mg/kg body weight, by interperitoneal injection at 6 and 7 wk of age) 40 wk after treatment. Expression of PLC-delta in the neoplasms was not detected by northern blot analysis, and a low level of expression was detected by immunoblot analysis, although PLC-delta expression was apparent in the non-neoplastic colon mucosae of MAM acetate-treated rats as well as in the colon mucosae of control rats. Furthermore, analysis by reverse transcriptase-polymerase chain reaction revealed that the ratio of the expression of PLC-delta to that of beta-actin in the neoplasms was significantly lower than the ratios in the non-neoplastic colon mucosae of carcinogen-treated and control rats (P < 0.01). However, the ornithine decarboxylase (ODC) activity in the neoplasms was significantly greater than that of the non-neoplastic and control mucosae (P < 0.001). The differences in the levels of PLC-delta expression in neoplastic and non-neoplastic tissues and the inverse correlation of PLC-delta expression with ODC activity may suggest that PLC-delta has little effect on the PLC-mediated mitogenic signaling system, at least in MAM acetate-induced colon neoplasms in rats.