Comparative pulmonary toxicity of a DWCNT and MWCNT-7 in rats.

Very little is known about the in vivo toxicity of inhaled double-walled carbon nanotubes (DWCNTs). In the present study, we compared the pulmonary toxicity of DWCNT to MWCNT-7, a well-known multi-walled carbon nanotube. Rats were divided into six groups: untreated, vehicle, low-dose DWCNT, high-dose DWCNT, low-dose MWCNT-7, and high-dose MWCNT-7. The test materials were administered by intra-tracheal intra-pulmonary spraying (TIPS) every other day for 15 days: the low-dose and high-dose groups were administered final total doses of 0.25 and 0.50 mg/rat of the test material. The animals were sacrificed 1 and 6 weeks after the final TIPS administration. Six weeks after the final TIPS administration, rats administered MWCNT-7 had high levels of macrophage infiltration into the lung with dense alveolar wall fibrous thickening throughout the lung; significant elevation of lactate dehydrogenase activity, alkaline phosphatase activity, and total protein concentration in the bronchioalveolar lavage fluid; an increase in the pulmonary cell PCNA index; slightly elevated levels of 8-OHdG DNA adducts in lung tissue DNA; a small but significant increase in protein concentration in the pleural cavity lavage fluid and an increase in the visceral mesothelial cell PCNA index. None of these parameters was increased in rats administered DWCNT. The primary lesion in rats administered DWCNT was scattered formation of granulation tissue containing internalized DWCNT fibers. Our data indicate that DWCNT has lower pulmonary and pleural toxicity than MWCNT-7.

Bovine lactoferrin and Crohn's disease: a case study.

A 22-year-old male suffering from abdominal pain, repeated diarrhea, and weight loss visited the Digestive Disease Department of Nagoya City University Hospital on 19 December 2011. He was hospitalized and diagnosed with Crohn's colitis. His Crohn's Disease Activity Index (CDAI) was 415. Treatment by granulocyte apheresis, mesalazine, and adalimumab was started. His CDAI was 314 on 30 December and 215 on 5 January. A colonoscopic examination on 19 January showed almost complete remission in the transverse colon and marked remission in the rectum. Mesalazine therapy was stopped on 28 February, and the patient was instructed to self-inject 40 mg of adalimumab every other week. His CDAI was 50 on 10 April, indicating clinical remission. His last self-injection of adalimumab was on 24 April 2012, and he started taking 1 g of bovine lactoferrin (bLF) daily. His CDAI was 35 on 8 January 2013. He continued taking 1 g of bLF daily without any other treatment for Crohn's disease. Laboratory blood tests on 7 September 2015 showed no sign of disease recurrence, and a colonoscopic examination on 23 October 2015 showed almost complete mucosal healing. This case indicates that ingestion of bLF to maintain Crohn's disease in a remissive state should be further explored.

Chemokine (C-C motif) ligand 3 detection in the serum of persons exposed to asbestos: A patient-based study.

Exposure to asbestos results in serious risk of developing lung and mesothelial diseases. Currently, there are no biomarkers that can be used to diagnose asbestos exposure. The purpose of the present study was to determine whether the levels or detection rate of chemokine (C-C motif) ligand 3 (CCL3) in the serum are elevated in persons exposed to asbestos. The primary study group consisted of 76 healthy subjects not exposed to asbestos and 172 healthy subjects possibly exposed to asbestos. The secondary study group consisted of 535 subjects possibly exposed to asbestos and diagnosed with pleural plaque (412), benign hydrothorax (10), asbestosis (86), lung cancer (17), and malignant mesothelioma (10). All study subjects who were possibly exposed to asbestos had a certificate of asbestos exposure issued by the Japanese Ministry of Health, Labour and Welfare. For the primary study group, levels of serum CCL3 did not differ between the two groups. However, the detection rate of CCL3 in the serum of healthy subjects possibly exposed to asbestos (30.2%) was significantly higher (P < 0.001) than for the control group (6.6%). The pleural plaque, benign hydrothorax, asbestosis, and lung cancer groups had serum CCL3 levels and detection rates similar to that of healthy subjects possibly exposed to asbestos. The CCL3 chemokine was detected in the serum of 9 of the 10 patients diagnosed with malignant mesothelioma. Three of the patients with malignant mesothelioma had exceptionally high CCL3 levels. Malignant mesothelioma cells from four biopsy cases and an autopsy case were positive for CCL3, possibly identifying the source of the CCL3 in the three malignant mesothelioma patients with exceptionally high serum CCL3 levels. In conclusion, a significantly higher percentage of healthy persons possibly exposed to asbestos had detectable levels of serum CCL3 compared to healthy unexposed control subjects.

Rat N-ERC/mesothelin as a marker for in vivo screening of drugs against pancreas cancer.

Pancreatic ductal adenocarcinoma (PDA) is a highly lethal disease, which is usually diagnosed in an advanced stage. We have established transgenic rats carrying a mutated K-ras gene controlled by Cre/loxP activation. The animals develop PDA which is histopathologically similar to that in humans. Previously, we reported that serum levels of N-ERC/mesothelin were significantly higher in rats bearing PDA than in controls. In the present study, to determine whether serum levels of N-ERC/mesothelin correlated with tumor size, we measured N-ERC/mesothelin levels in rats bearing PDA. Increased serum levels of N-ERC/mesothelin correlated with increased tumor size. This result indicates an interrelationship between the serum level of N-ERC/mesothelin and tumor size. We next investigated the effect of chemotherapy on serum N-ERC/mesothelin levels. Rat pancreatic cancer cells were implanted subcutaneously into the flank of NOD-SCID mice. In the mice treated with 200 mg/kg gemcitabine, tumor weight and the serum level of N-ERC/mesothelin were significantly decreased compared to controls. These results suggest that serum N-ERC/mesothelin measurements might be useful for monitoring response to therapy.

Inhibition of intestinal polyp growth by oral ingestion of bovine lactoferrin and immune cells in the large intestine.

Studies using animal models have demonstrated that ingestion of bovine lactoferrin (bLF) inhibits carcinogenesis in the colon and other organs of experimental animals. As a result of these studies, a blinded, randomized, controlled clinical trial was conducted in the National Cancer Center Hospital, Tokyo, Japan to determine whether ingestion of bLF had an effect on the growth of colorectal polyps in humans. Patients with colorectal polyps ≤5 mm diameter and likely to be adenomas ingested 0, 1.5, or 3.0 g bLF daily for 1 year. Ingestion of 3.0 g bLF suppressed the growth of colorectal polyps and increased the level of serum human lactoferrin in trial participants 63 years old or younger. The purpose of the present study was to investigate correlations between immune parameters and changes in polyp size. Trial participants with regressing polyps had increased NK cell activity, increased serum hLF levels (indicating increased neutrophil activity), and increased numbers of CD4+ cells in the polyps. These findings are consistent with a correlation between higher immune activity and suppression of colorectal polyps. In addition, participants with regressing polyps had lower numbers of PMNs and increased numbers of S100A8+ cells in the polyps, consistent with a correlation between lower inflammatory potential in the colon and suppression of colorectal polyps. Trial participants ingesting bLF had increased serum hLF levels, a possible increase in systemic NK cell activity, and increased numbers of CD4+ and CD161+ cells in the polyps. Taken together, our findings suggest that bLF suppressed colorectal polyps by enhancing immune responsiveness.

Prevention and intervention trials for colorectal cancer.

There have been a number of candidates for chemopreventive agents from synthetic drugs and natural compounds suggested to prevent colorectal cancer. However, they have shown modest efficacy in humans. The reason for this could be partly explained by the use of inappropriate models in vitro and in vivo, and the limitation of chemoprevention trials. In Japan, there are no cancer chemopreventive medicines, and few cancer chemoprevention trials to date. In contrast, an increase in the prevalence of colorectal cancer in Japan has forced us to develop more efficient chemopreventive strategies. It is now a good time to review in detail the current status and future prospects for chemoprevention of colorectal cancer with respect to the future development of chemopreventive medicines, particularly using synthetic drugs and natural compounds in Asian populations. The role and mode of action of available synthetic drugs, mainly aspirin and metformin, are reviewed. In addition, the possible impact of natural compounds with anti-inflammatory/immunosuppressive properties, such as ω3 polyunsaturated fatty acid and lactoferrin, are also reviewed.

Lactoferrin: an alternative view of its role in human biological fluids.

Lactoferrin is a major component of biologically important mucosal fluids and of the specific granules of neutrophils. Understanding its biological function is essential for understanding neutrophil- and mucosal-mediated immunity. In this review, we reevaluate the in vivo functions of human lactoferrin (hLF) emphasizing in vivo studies and in vitro studies performed in biologically relevant fluids. We discuss the evidence in the literature that supports (or does not support) proposed roles for hLF in mucosal immunity and in neutrophil function. We argue that the current literature supports a microbiostatic role, but not a microbicidal role, for hLF in vivo. The literature also supports a role for hLF in inhibiting colonization and infection of epithelial surfaces by microorganisms and in protecting tissues from neutrophil-mediated damage. Using this information, we briefly discuss hLF in the context of the complex biological fluids in which it is found.

Effects of pepsin and trypsin on the anti-adipogenic action of lactoferrin against pre-adipocytes derived from rat mesenteric fat.

Lactoferrin (LF) is a multifunctional glycoprotein in mammalian milk. In a previous report, we showed that enteric-coated bovine LF tablets can decrease visceral fat accumulation, hypothesising that the enteric coating is critical to the functional peptides reaching the visceral fat tissue and exerting their anti-adipogenic activity. The aim of the present study was to assess whether ingested LF can retain its anti-adipogenic activity. We therefore investigated the effects of LF and LF treated with digestive enzymes (the stomach enzyme pepsin and the small intestine enzyme trypsin) on lipid accumulation in pre-adipocytes derived from the mesenteric fat tissue of male Sprague-Dawley rats. Lipid accumulation in pre-adipocytes was significantly reduced by LF in a dose-dependent manner and was associated with reduction in gene expression of CCAAT/enhancer binding protein delta, CCAAT/enhancer binding protein alpha and PPARγ as revealed by DNA microarray analysis. Trypsin-treated LF continued to show anti-adipogenic action, whereas pepsin-treated LF abrogated the activity. When an LF solution (1000 mg bovine LF) was administered by gastric intubation to Sprague-Dawley rats, immunoreactive LF determined by ELISA could be detected in mesenteric fat tissue at a concentration of 14·4 µg/g fat after 15 min. The overall results point to the importance of enteric coating for action of LF as a visceral fat-reducing agent when administered in oral form.

Potent anti-obesity effect of enteric-coated lactoferrin: decrease in visceral fat accumulation in Japanese men and women with abdominal obesity after 8-week administration of enteric-coated lactoferrin tablets.

Lactoferrin (LF), a multifunctional glycoprotein in mammalian milk, is reported to exert a modulatory effect on lipid metabolism. The aim of the present study was to elucidate whether enteric-coated LF (eLF) might improve visceral fat-type obesity, an underlying cause of the metabolic syndrome. Using a double-blind, placebo-controlled design, Japanese men and women (n 26; aged 22-60 years) with abdominal obesity (BMI>25 kg/m2, and visceral fat area (VFA)>100 cm2) consumed eLF (300 mg/d as bovine LF) or placebo tablets for 8 weeks. Measurement of the total fat area, VFA and subcutaneous fat area from computed tomography images revealed a significant reduction in VFA ( - 14.6 cm2) in the eLF group, as compared with the placebo controls ( - 1.8 cm2; P = 0.009 by ANCOVA). Decreases in body weight, BMI and hip circumference in the eLF group ( - 1.5 kg, - 0.6 kg/m2, - 2.6 cm) were also found to be significantly greater than with the placebo (+1.0 kg, +0.3 kg/m2, - 0.2 cm; P = 0.032, 0.013, 0.041, respectively). There was also a tendency for a reduction in waist circumference in the eLF group ( - 4.4 cm) as compared with the placebo group ( - 0.9 cm; P = 0.073). No adverse effects of the eLF treatment were found with regard to blood lipid or biochemical parameters. From these results, eLF appears to be a promising agent for the control of visceral fat accumulation.

Cancer prevention by bovine lactoferrin: from animal studies to human trial.

Colorectal cancer (CRC) is one of the most frequently diagnosed cancers and, despite improved colonoscopic screening, CRC is a leading cause of death from cancer. Administration of bovine lactoferrin (bLF) suppresses carcinogenesis in the colon and other organs of test animals, and recently it was shown that ingestion of bLF inhibits the growth of adenomatous polyps in human patients. Here we review work which established bLF as an anti-carcinogenic agent in laboratory animals and the results of a clinical trial which demonstrated that bLF can reduce the risk of colon carcinogenesis in humans.

Involvement of macrophage inflammatory protein 1alpha (MIP1alpha) in promotion of rat lung and mammary carcinogenic activity of nanoscale titanium dioxide particles administered by intra-pulmonary spraying.

Titanium dioxide (TiO(2)) is evaluated by World Health Organization/International Agency for Research on Cancer as a Group 2B carcinogen. The present study was conducted to detect carcinogenic activity of nanoscale TiO(2) administered by a novel intrapulmonary spraying (IPS)-initiation-promotion protocol in the rat lung. Female human c-Ha-ras proto-oncogene transgenic rat (Hras128) transgenic rats were treated first with N-nitrosobis(2-hydroxypropyl)amine (DHPN) in the drinking water and then with TiO(2) (rutile type, mean diameter 20 nm, without coating) by IPS. TiO(2) treatment significantly increased the multiplicity of DHPN-induced alveolar cell hyperplasias and adenomas in the lung, and the multiplicity of mammary adenocarcinomas, confirming the effectiveness of the IPS-initiation-promotion protocol. TiO(2) aggregates were localized exclusively in alveolar macrophages and had a mean diameter of 107.4 nm. To investigate the underlying mechanism of its carcinogenic effects, TiO(2) was administered to wild-type rats by IPS five times over 9 days. TiO(2) treatment significantly increased 8-hydroxydeoxy guanosine level, superoxide dismutase activity and macrophage inflammatory protein 1alpha (MIP1alpha) expression in the lung. MIP1alpha, detected in the cytoplasm of TiO(2)-laden alveolar macrophages in vivo and in the media of rat primary alveolar macrophages treated with TiO(2) in vitro, enhanced proliferation of human lung cancer cells. Furthermore, MIP1alpha, also detected in the sera and mammary adenocarcinomas of TiO(2)-treated Hras128 rats, enhanced proliferation of rat mammary carcinoma cells. These data indicate that secreted MIP1alpha from TiO(2)-laden alveolar macrophages can cause cell proliferation in the alveoli and mammary gland and suggest that TiO(2) tumor promotion is mediated by MIP1alpha acting locally in the alveoli and distantly in the mammary gland after transport via the circulation.

Nano-scaled particles of titanium dioxide convert benign mouse fibrosarcoma cells into aggressive tumor cells.

Nanoparticles are prevalent in both commercial and medicinal products; however, the contribution of nanomaterials to carcinogenesis remains unclear. We therefore examined the effects of nano-sized titanium dioxide (TiO(2)) on poorly tumorigenic and nonmetastatic QR-32 fibrosarcoma cells. We found that mice that were cotransplanted subcutaneously with QR-32 cells and nano-sized TiO(2), either uncoated (TiO(2)-1, hydrophilic) or coated with stearic acid (TiO(2)-2, hydrophobic), did not form tumors. However, QR-32 cells became tumorigenic after injection into sites previously implanted with TiO(2)-1, but not TiO(2)-2, and these developing tumors acquired metastatic phenotypes. No differences were observed either histologically or in inflammatory cytokine mRNA expression between TiO(2)-1 and TiO(2)-2 treatments. However, TiO(2)-2, but not TiO(2)-1, generated high levels of reactive oxygen species (ROS) in cell-free conditions. Although both TiO(2)-1 and TiO(2)-2 resulted in intracellular ROS formation, TiO(2)-2 elicited a stronger response, resulting in cytotoxicity to the QR-32 cells. Moreover, TiO(2)-2, but not TiO(2)-1, led to the development of nuclear interstices and multinucleate cells. Cells that survived the TiO(2) toxicity acquired a tumorigenic phenotype. TiO(2)-induced ROS formation and its related cell injury were inhibited by the addition of antioxidant N-acetyl-l-cysteine. These results indicate that nano-sized TiO(2) has the potential to convert benign tumor cells into malignant ones through the generation of ROS in the target cells.

Effect of orally administered bovine lactoferrin on the growth of adenomatous colorectal polyps in a randomized, placebo-controlled clinical trial.

Lactoferrin (LF), a secreted, iron binding glycoprotein originally discovered as a component of milk, is found in a variety of exocrine secretions and in the secondary granules of polymorphonuclear leukocytes. Animal experiments have shown that oral administration of bovine lactoferrin (bLF) exerts anticarcinogenesis effects in the colon and other organs of the rat. The aim of this study was to determine whether oral bLF could inhibit the growth of adenomatous colorectal polyps in human patients. A randomized, double-blind, controlled trial was conducted in 104 participants, ages 40 to 75 years, with polyps

An animal model of preclinical diagnosis of pancreatic ductal adenocarcinomas.

Pancreatic ductal adenocarcinoma (PDA) is a highly lethal disease, which is usually diagnosed in an advanced stage. Animal PDA models which reflect the human condition are clearly necessary to develop early diagnostic tools and explore new therapeutic approaches. We have established transgenic rats carrying a mutated H- or K-ras gene (Hras250 and Kras327) controlled by Cre/loxP activation. These animals develop PDA which are histopathologically similar to that in humans. We utilized this model to identify biomarkers to detect early PDA. We report here that serum levels of Erc/Mesothelin are significantly higher in rats bearing PDA than in controls. Importantly, the levels are significantly elevated in rats before grossly visible carcinomas develop. Even in rats with very small microscopic ductal carcinoma lesions, elevated serum Erc/Mesothelin can be detected. We believe this is the first report of a pancreas tumor animal model in which pre-symptomatic lesions can be diagnosed.

Promotion of mouse two-stage skin carcinogenesis by diacylglycerol-rich edible oil.

Tumor promotion potential of diacylglycerol (DAG)-rich edible oil was examined using a two-stage mouse skin carcinogenesis model initiated with 7,12-dimethylbenz[a]anthracene (DMBA). Topical treatment with 75 mg DAG oil once a day for 5 days/week for 35 weeks caused papillomas in 4 of 23 (17%) DMBA-treated female ICR mice, while DMBA initiation alone and DAG treatment without DMBA initiation did not induce any skin tumors. Doubling the daily treatment (twice a day x 5 days/week) at doses of 75 and 30 mg caused both papillomas and squamous cell carcinomas after DMBA initiation, the incidences of tumors being 48% (12/25) and 44% (11/25), respectively, significantly higher than the 4% (1/23) in the DMBA+ 85 mg triacylglycerol group and 0% (0/24) in the DMBA+ vehicle-treated group. The results indicate that DAG-rich oil has promoting potential for skin carcinogenesis, and thus, further investigations of its tumor-promoting potential in other organs are warranted.

Anticarcinogenesis pathways activated by bovine lactoferrin in the murine small intestine.

Oral administration of bovine lactoferrin (bLF) inhibits carcinogenesis in the colon and other organs in rats, and lung metastasis in mice. A likely mechanism by which bLF mediates its anticarcinogenesis effects is by enhanced expression of cytokines and subsequent activation of immune cells. Oral administration of bLF enhances expression of interleukin-18 (IL-18) mRNA in the mucosa of the small intestine of mice. Importantly, the pepsin hydrolysate of bLF (bLFH) also induced expression of IL-18 mRNA in the mouse small intestine and a peptide produced by pepsin digestion of bLF, bovine lactoferricin (bLFcin), induced expression of mature IL-18 in organ culture. In addition to IL-18, bLF and bLFcin both induced significant increases in caspase-1 activity in peritoneal macrophages and in organ cultures. The increase of mature IL-18 by macrophages was inhibited by caspase-1 inhibitor: caspase-1 is known to cleave the proform of IL-18 to produce active mature IL-18. Finally, bLF also induced expression of IFNgamma by peritoneal macrophages. Importantly, in IFNgamma knockout (GKO) mice, bLF administration resulted in increased expression of caspase-1 protein, but induction of IL-18 mRNA, caspase-1 activity, and mature IL-18 was not observed. These results indicate that orally administered bLF can induce expression of IFNgamma and caspase-1 in the small intestine. IFNgamma in turn increases expression of target genes, including IL-18. Active caspase-1 then cleaves pro-IL-18 to generate mature IL-18. Thus, bLF activates an effector pathway mediated by IFNgamma, caspase-1, and IL-18. We also show that ingested bLF is able to activate more than a single effector pathway. For example, in GKO mice while bLF administration could not activate the IFNgamma/caspase-1/IL-18 effector pathway, it was able to inhibit tumor growth and metastasis by activation of an IFNalpha/IL-7 effector pathway.

Lack of chronic oral toxicity of chemopreventive bovine lactoferrin in F344/DuCrj rats.

Studies were undertaken to determine whether bovine lactoferrin (bLF) and related compounds, shown to prevent carcinogenesis in the colon and other organs in rats, have any toxic effects in long-term feeding studies. In experiment I, male F344/DuCrj rats received a basal diet containing 0.2% bLF for 40 weeks. No adverse findings were noted, furthermore, serum triglyceride level was significantly decreased to 72% of the control level, suggesting preventive effects against the metabolic syndrome. In experiment II, male and female F344/DuCrj rats were fed a basal diet containing 0.02, 0.2, 2.0 and 5.0% bLF, 2.0% bLF hydrolysate (bLF-H) or 0.1% lactoferricin (LFcin), a peptide derived from bLF, for 60 weeks in males and 65 weeks in females. No toxicological effects, including carcinogenicity, were evident in either sex. The results of the studies provide subjective support for safety of clinical studies of bLF for supplement use.

Possible application of human c-Ha-ras proto-oncogene transgenic rats in a medium-term bioassay model for carcinogens.

With the aim of developing a medium-term assay for screening of environmental carcinogens, we exposed mammary carcinogen sensitive human c-Ha-ras proto-oncogene transgenic (Hras128) rats to various carcinogens, including compounds that do not normally induce mammary tumors. Seven-week-old Hras128 rats and wild-type littermates received administrations of 3-methylcholanthrene (3-MC), benzo[a]pyrene (B[a]P), anthracene, pyrene, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK), dimethylarsinic acid (DMA), diethylnitrosamine (DEN) or azoxymethane (AOM) and were sacrificed at week 12 (females) (at week 10 for the 3-MC group) or week 20 (males). Female Hras128 rats receiving NNK, DEN, or DMA showed a significant increase in mammary tumor incidence and/or multiplicity compared to the respective values with olive oil or deionized distilled water (DDW) vehicles. In male Hras128 rats, a significant increase in mammary tumors was also observed in groups administered 3-MC, B[a]P, anthracene, IQ, and NNK. Mutations of transgenes were observed in codons 12 and/or 61 in the induced tumors by PCR-RFLP except in the DEN group in female and in the MeIQx group in male Hras128 rats. Thus various carcinogens, not necessarily limited to those normally targeting the breast, were found to induce mammary carcinomas in Hras128 rats, especially in females, pointing to potential use for medium-term screening.

Possible enhancing activity of diacylglycerol on 4-nitroquinoline 1-oxide induced carcinogenesis of the tongue in human c-Ha-ras proto-oncogene transgenic rats.

1,2-diacylglycerol (1,2-DAG) is involved in cell proliferation as an activator of protein kinase C (PKC) and has been shown to stimulate growth of cancer cells, raising the possibility of a role in tumor promotion. Ingested DAG oil, containing 70% 1,3-DAG and 30% 1,2-DAG, is digested and considered to be safe as edible oil. However, DAG may directly contact with oral cavity mucosa in undigested form. The present study was conducted to examine the effects of DAG oil on carcinogenesis in c-Ha-ras proto-oncogene transgenic (Tg) rats administered 4-nitroquinoline 1-oxide (4NQO, 10 ppm) in their drinking water for 10 weeks for initiation of mainly upper digestive organs. DAG oil added in basal diet at 5.5%, 2.75%, 1.38% and 0% with total fat made up to 5.5% with triacylglycerol (TAG) was administered during the initiation and post-initiation period. The study was terminated at week 12 (Tg females) and 20 (Tg males, wild females and males). The fatty acid composition of DAG oil was similar to TAG (linoleic acid 46.6% and oleic acid 38.9%). In Tg male rats, DAG oil administration was associated with significant increase (P<0.05) in the incidence of squamous cell carcinomas (SCC) of the tongue (5.5% DAG, 43.8%; 2.75% DAG, 20%; 1.38% DAG, 14.3%; 0%, 12.3%) with the Cochran-Armitage trend test and also number of tumors in coefficients for linear contrast trend tests. Tongue SCC induction of wild males and all females was not significant. The present results suggest that DAG oil may have enhancing and/or promotion potential for tongue carcinogenesis in male Tg featuring elevated ras expression.