Female Apc Research Articles

Trends analysis of cancer incidence, mortality, and survival for the elderly in the United States, 1975-2020.

Cancer burden from the elderly has been rising largely due to the aging population. However, research on the long-term epidemiological trends in cancer of the elderly is lacking. Registry data of this population-based cross-sectional study were from the Surveillance, Epidemiology, and End Results (SEER) database. The study population aged 65 years or more, from geographically distinct regions. Joinpoint regression and JP Surv method were used to analyze cancer trends and survival. Mortality rate during 1975-2020 decreased from 995.20 to 824.99 per 100,000 elderly persons, with an average annual decrease of 0.421% (95% CI, 0.378-0.464). While overall incidence increased with no significance. Prostate (29%) and breast (26%) cancer were the most common malignancies, respectively, in elderly males and females, and the mortality for both of the two (prostate 15%, breast 14%) ranked just behind lung and bronchus cancer, which had the highest mortality rates in males (29%) and females (23%). Many cancers showed adverse trends in the latest follow-up periods (the last period calculated by the Joinpoint method). For intrahepatic cholangiocarcinoma, incidence (male Annual Percentage Change [APC] = 7.4*; female APC = 6.7*) and mortality (male APC = 3.0*; female APC = 3.3*) increased relatively fast, and its survival was also terrible (3-year survival only 10%). Other cancers with recent increasing mortality included cancer of anus, anal canal and anorectum, retroperitoneum, pleura, peritoneum, etc. Most cancers had favorable trends of survival during the nearest follow-up period. Against the background of overall improvement, many cancers showed adverse trends. Further research for the underlying mechanisms and targeted implements towards adverse trends is also urgent.

Sex-dependent lifespan extension of Apc Min/+ FAP mice by chronic mTOR inhibition.

Apc Min/+ mice model familial adenomatous polyposis (FAP), a disease that causes numerous colon polyps leading to colorectal cancer. We previously showed that chronic treatment of Apc Min/+ females with the anti-aging drug, rapamycin, restored a normal lifespan through reduced polyposis and anemia prevention. Lifespan extension by chronic rapamycin in wildtype UM-HET3 mice is sex-dependent with females gaining the most benefit. Whether Apc Min/+ mice have a similar sex-dependent response to chronic mTOR inhibition is not known. To address this knowledge gap and gain deeper insight into how chronic mTOR inhibition prevents intestinal polyposis, we compared male and female Apc Min/+ mice responses to chronic treatment with a rapamycin-containing diet. Animals were fed a diet containing either 42 ppm microencapsulate rapamycin or empty capsules, one group was used to determine lifespan and a second group with similar treatment was harvested at 16 weeks of age for cross-sectional studies. We found that the survival of males is greater than females in this setting (P < 0.0197). To explore the potential basis for this difference we analyzed factors affected by chronic rapamycin. Immunoblot assays showed that males and females exhibited approximately the same level of mTORC1 inhibition using phosphorylation of ribosomal protein S6 (rpS6) as an indirect measure. Immunohistochemistry assays of rpS6 phosphorylation showed that rapamycin reduction of mTORC1 activity was on the same level, with the most prominent difference being in intestinal crypt Paneth cells in both sexes. Chronic rapamycin also reduced crypt depths in both male and female Apc Min/+ mice (P < 0.0001), consistent with reduced crypt epithelial cell proliferation. Finally, chronic rapamycin prevented anemia equally in males and females. In males and females, these findings link rapamycin-mediated intestinal polyposis prevention with mTORC1 inhibition in Paneth cells and concomitant reduced epithelial cell proliferation.

Preventive Effects of Heat-Killed Enterococcus faecalis Strain EC-12 on Mouse Intestinal Tumor Development.

Establishing effective methods for preventing colorectal cancer by so-called “functional foods” is important because the global burden of colorectal cancer is increasing. Enterococcus faecalis strain EC-12 (EC-12), which belongs to the family of lactic acid bacteria, has been shown to exert pleiotropic effects, such as anti-allergy and anti-infectious effects, on mammalian cells. In the present study, we aimed to evaluate the preventive effects of heat-killed EC-12 on intestinal carcinogenesis. We fed 5-week-old male and female Apc mutant Min mice diets containing 50 or 100 ppm heat-killed EC-12 for 8 weeks. In the 50 ppm treated group, there was 4.3% decrease in the number of polyps in males vs. 30.9% in females, and significant reduction was only achieved in the proximal small intestine of female mice. A similar reduction was observed in the 100 ppm treated group. Moreover, heat-killed EC-12 tended to reduce the levels of c-Myc and cyclin D1 mRNA expression in intestinal polyps. Next, we confirmed that heat-killed EC-12 suppressed the transcriptional activity of the T-cell factor/lymphoid enhancer factor, a transcriptional factor involved in cyclin D1 mRNA expression in intestinal polyps. Our results suggest that heat-killed EC-12 very weakly suppresses intestinal polyp development in Min mice, in part by attenuating β-catenin signaling, and this implies that heat-killed EC-12 could be used as a “functional food”.

Cysteinyl leukotriene 1 receptor influences intestinal polyp incidence in a gender-specific manner in the ApcMin/+ mouse model.

There is emerging literature emphasizing the role of inflammatory eicosanoids, including prostaglandins and leukotrienes, in cancer development. Increased expression of both the cysteinyl leukotriene receptor 1 (CysLTR1) and the enzyme responsible for the production of leukotrienes, 5-lipoxygenase, is associated with poor prognosis in patients with colorectal adenocarcinomas. Apc mutation is an early event in the development of sporadic and hereditary (familial adenomatous polyposis) colorectal cancer. We utilized the Apc(Min/+) mouse model of familial adenomatous polyposis/sporadic colorectal cancer to investigate the role of CysLTR1 in intestinal tumorigenesis by crossing Apc(Min/+) mice with mice lacking the Cysltr1 gene. We could observe a reduced tumor burden in the small intestine of double-mutant female (Cysltr1 (-/-) Apc (Min/+) ) but not double-mutant male mice, compared with gender-matched single-mutant (Cysltr1 (+/+) Apc (Min/+) ) mice. This reduction was in a Cysltr1-dependent manner, female double-mutant mice having significantly reduced tumor formation compared with control littermates. The female double-mutant phenotype was accompanied with decreased systemic inflammation, as evidenced by significantly reduced serum levels of prostaglandin E2 and CysLTs, as well as increased CD3(+)CD8(+) T-cell tumor infiltration. Furthermore, the reduced formation of polyps in double-mutant (Cysltr1 (-/-) Apc (Min/+) ) female mice could in part be explained by the cytotoxic action of CD3(+)CD8(+) T cells in the polyp and reduced nuclear accumulation of β-catenin in the epithelium of small intestinal polyps. Our results stress the important role that CysLTR1 plays in colorectal cancer and its potential as a therapeutic target in cancer therapy.

Relative Biological Effectiveness of Energetic Heavy Ions for Intestinal Tumorigenesis Shows Male Preponderance and Radiation Type and Energy Dependence in APC1638N/+ Mice

There are uncertainties associated with the prediction of colorectal cancer (CRC) risk from highly energetic heavy ion (HZE) radiation. We undertook a comprehensive assessment of intestinal and colonic tumorigenesis induced after exposure to high linear energy transfer (high-LET) HZE radiation spanning a range of doses and LET in a CRC mouse model and compared the results with the effects of low-LET γ radiation. Male and female APC(1638N/+) mice (n=20 mice per group) were whole-body exposed to sham-radiation, γ rays, (12)C, (28)Si, or (56)Fe radiation. For the >1 Gy HZE dose, we used γ-ray equitoxic doses calculated using relative biological effectiveness (RBE) determined previously. The mice were euthanized 150 days after irradiation, and intestinal and colon tumor frequency was scored. The highest number of tumors was observed after (28)Si, followed by (56)Fe and (12)C radiation, and tumorigenesis showed a male preponderance, especially after (28)Si. Analysis showed greater tumorigenesis per unit of radiation (per cGy) at lower doses, suggesting either radiation-induced elimination of target cells or tumorigenesis reaching a saturation point at higher doses. Calculation of RBE for intestinal and colon tumorigenesis showed the highest value with (28)Si, and lower doses showed greater RBE relative to higher doses. We have demonstrated that the RBE of heavy ion radiation-induced intestinal and colon tumorigenesis is related to ion energy, LET, gender, and peak RBE is observed at an LET of 69 keV/μm. Our study has implications for understanding risk to astronauts undertaking long duration space missions.

Krüppel-like factor 9 (KLF9) prevents colorectal cancer through inhibition of interferon-related signaling.

Expression of the transcription factor Krüppel-like factor 9 (KLF9) is frequently reduced in colorectal cancers, although a tumor suppressive role has not been established. To determine if KLF9 suppresses intestinal adenoma formation, we generated mice of distinct Klf9 genotypes in the background of the Apc (Min/+) mouse and compared their adenoma burdens at 16 weeks of age. While small intestine adenoma burden remained unchanged among Klf9 genotypes, male and female Apc(Min/+)/Klf9(-/-) and Apc(Min/+)/Klf9(+/-) mice exhibited significantly more colon adenomas than their Apc(Min/+)/Klf9(+/+) counterparts. Microarray analysis showed significant increases in the expression of interferon-induced genes in the colon mucosa of female Apc (Min/+)/Klf9(+/-) and Apc(Min/+)/Klf9(-/-) compared to Apc(Min/+)/Klf9(+/+) mice, prior to overt adenoma occurrence. Gene upregulation was confirmed by qPCR of colon mucosa and by siRNA knockdown of KLF9 in human HT29 colorectal cancer cells. Increases in expression of these genes were further augmented by supplementation with Interferon β1. Circulating levels of the cytokine, interferon-stimulated gene 15 (ISG15) were increased in Apc(Min/+)/Klf9(+/-) and Apc(Min/+)/Klf9(-/-) mice relative to Apc(Min/+)/Klf9(+/+). Additionally, colon mucosal levels of ISG15 were increased in Apc(Min/+)/Klf9(+/-) mice. Chromatin immunoprecipitation demonstrated KLF9 recruitment to the ISG15 promoter. Lastly, treatment with ISG15 suppressed apoptosis in HT29 cells, in the presence and absence of 5-fluorouracil (5FU). Results show KLF9 to be a haploinsufficient suppressor of colon tumorigenesis in Apc(Min/+) mice in part, by repression of ISG15 and the latter's antiapoptotic function. Krüppel-like factor 9 (KLF9) is a haploinsufficient tumor suppressor in the ApcMin/+ mouse colon by suppressing expression of ISG15, an apoptosis-inhibiting cytokine.

Improved innate immune responses by Frondanol A5, a sea cucumber extract, prevent intestinal tumorigenesis.

Sea cucumbers are a source of antibacterial, anti-inflammatory, and anticancer compounds. We show that sea cucumber extract Frondanol A5 is capable of enhancing innate immune responses and inhibiting intestinal tumors in APC(Min/+) mice. APC(Min/+) mice were fed semi-purified diets containing 0, 250, or 500 ppm FrondanolA5 for 14 weeks before we assessed intestinal tumor inhibition. Dietary Frondanol A5 suppressed small intestinal polyp sizes and formation up to 30% (P < 0.02) in males and up to 50% (P < 0.01) in females. Importantly, 250 and 500 ppm Frondanol A5 diet suppressed colon tumor multiplicities by 65% (P < 0.007) and 75% (P < 0.0001), compared with untreated male APC(Min/+) mice. In female APC(Min/+) mice, both dose levels of Frondanol A5 suppressed colon tumor multiplicities up to 80% (P < 0.0001). Isolated peritoneal macrophages from treated mice showed increased phagocytosis efficiency (control 24% vs. treated 50%; P < 0.01) and an increase in GILT mRNA expression, indicating increased innate immune responses by these cells in treated animals. Similarly, we observed an increase in GILT expression in treated tumors, compared with untreated tumors. Furthermore, an increase in G-CSF cytokine, a decrease in inflammatory cytokines and marker 5-LOX, its regulator FLAP, proliferation (PCNA), and angiogenesis (VEGF) markers were observed in treatment groups. These data suggest that Frondanol A5 decreased inflammatory angiogenic molecules and increased GILT expression and macrophage phagocytosis. These decreases may have improved the innate immune systems of the treated mice, thus aiding in inhibition of intestinal tumor formation. These results suggest that Frondanol A5 exhibits significant chemopreventive potential against intestinal tumorigenesis.

The effect of sex on IL‐6 regulation of cancer cachexia progression in the Apc min/+ mouse (704.2)

Cachexia is a condition that arises secondary to many chronic diseases and accounts for more than 20% of cancer‐related deaths. Cachexia occurs in both sexes, but research into its etiology and progression has been almost exclusively in the male. Our lab has previously shown that body weight loss in the male Apc min/+ mouse is closely associated with plasma IL‐6 and triglyceride levels as well as tumor burden. The purpose of the present study was to determine if sex alters IL‐6 regulation of cachexia progression in Apc min/+ mice. 24 female Apc min/+ mice were monitored during the development of cachexia until sacrifice at 20 weeks of age. Plasma IL‐6 and triglycerides as well as intestinal polyps were quantified. Body weight loss from peak ranged from 0% to 21%, with 30% of mice becoming severely cachectic. Plasma IL‐6 levels varied from 4.4‐39.7 pg/ml, which is comparable to the male. Similar to the male, body weight loss was correlated with tumor number (p=0.01). Unlike the male, there was neither a relationship between body weight loss and plasma IL‐6 or triglyceride levels; nor between tumor number and plasma IL‐6 level. Interestingly, muscle mass loss was inversely correlated with plasma IL‐6 level (p=0.03), which is contrary to the male. We present evidence that sex can affect the relationship between muscle mass loss, cachexia development, and plasma IL‐6 in the Apc min/+ mouse, which may impact therapeutics for cachexia.

Plant Sterol Feeding Induces Tumor Formation and Alters Sterol Metabolism in the Intestine of Apc MinMice

Dietary plant sterols reduce the absorption of cholesterol and therefore increase intraluminal cholesterol concentration. We examined how plant sterol esters from functional foods affect intestinal tumorigenesis in tumor-prone adenomatous polyposis coli (Apc) Minmice. Feeding plant sterols at 0.8% increased the number of intestinal adenomas, and the effect was significant in female mice. The concentration of mucosal free sitosterol increased by eightfold in plant sterol males and by threefold in plant sterol females when compared with respective controls. The concentration of mucosal free cholesterol was significantly lower in plant sterol males than in control males, and the decrease in free cholesterol was accompanied with a significant increase in nuclear sterol regulatory element binding protein-2. No difference was found in the levels of β-catenin, cyclin D1, epidermal growth factor receptor, extracellular signal-regulated kinase 1/2, or caveolin-1 in either gender after plant sterol feeding. Among all measured parameters, higher levels of estrogen receptor β and free cholesterol in the mucosa were among the strongest predictors of increased intestinal tumorigenesis. In addition, gene expression data showed significant enrichment of up-regulated genes of cell cycle control and cholesterol biosynthesis in plant sterol females. The results indicate that high intake of plant sterols accelerates intestinal tumorigenesis in female Apc Minmice; however, the mechanism behind the adverse effect remains to be discovered.

Estrogen receptor α or β loss in the colon of Min/+ mice promotes crypt expansion and impairs TGFβ and HNF3β signaling

Adenomatous polyposis coli (APC)-regulated Wnt and transforming growth factor-β (TGFβ) signaling cooperate in the intestine to maintain normal enterocyte functions. Human clinical trials showed that estrogen [17β-estradiol (E2)], the ligand of nuclear receptors estrogen receptor α (ERα) and ERβ, inhibited colorectal cancer (CRC) in women. Consistent with this finding, we reported that E2, ERα and ERβ suppressed intestinal tumorigenesis in the C57BL/6J-Min/+ (Min/+) mouse, a CRC model. Here, we extended our results with further comparisons of colon and small intestine from intact female Apc (+/+) (WT), Min/+ and ER-deficient Min/+ mice. In the colon of ER-deficient Min/+ mice, ER loss reduced TGFβ signaling in crypt base cells as evidenced by minimal expression of the effectors Smad 2, 3 and 4 in these strains. We also found reduced expression of Indian hedgehog (Ihh), bone morphogenetic protein 4 and hepatocyte nuclear factor 3β or FoxA2, factors needed for paracrine signaling between enterocytes and mesenchyme. In proximal colon, ER loss produced a >10-fold increased incidence of crypt fission, a marker for wound healing and tumor promotion. These data, combined with our previous work detailing the specific roles of E2, ERα and ERβ in the colon, suggest that ER activity helps to maintain the intestinal stem cell (ISC) microenvironment by modulating epithelial-stromal crosstalk in ways that regulate cytokine, Wnt and Ihh availability in the extracellular matrix (ECM).

Abstract 1429: Apc heterozygosity in the C57BL/6J-Min/+ mouse produces an abnormal exuberant proliferative response in excisional wound healing

Abstract The Min mouse is a model for intestinal tumor formation. Previously, we showed that the ApcMin allele produces a dominant-negative effect on enterocyte migration and stromal interaction in vivo. Tumorigenesis is driven by features of epithelial-mesenchymal interaction that are observed in wound healing, therefore we hypothesized that the Min phenotype also involved abnormalities in the wounding response program. We performed excisional wound assays on female Min mice (10 or 20-week old), comparing response to that of female age-matched Apc+/+ (WT) mice. The healing kinetics of full thickness dorsum wounds were quantified by digital planimetry. Histological cross sections on post-operative day 7 were used to measure granulation tissue thickness, nascent blood vessel density, and cell proliferation. Western blotting was performed using granulation tissue lysates to compare the expression of adhesion and extracellular matrix proteins, as well as α-smooth muscle actin, a marker for the presence of contractile cells. Immunofluorescent histochemistry was performed to detect the co-expression and quantitation of αSMA+, vimentin+, SM22+, desmin− myofibroblasts at wound edges. Wound closure was faster in Min mice relative to WT mice, 88.85% versus 68.86% (P&amp;lt;0.01). Min mice also showed the strongest induction of granulation tissue formation; the relative granulation tissue thickness in the centre of wounds was 171.15±47.53 and 147.96±16 mm (P&amp;lt;0.01) in Min and WT, respectively. Blood vessel density, measured by counting the number of CD31+ cells/high power field, was increased (40.72 + 22.6) in Min mice when compared to WT (19.03 ± 17.6, P&amp;lt;0.01). The number of proliferating cells in granulation tissue (Ki67+ nuclei/all) in Min mice (63.72±16.83) was greater than in WT (41.58±23.46) (P&amp;lt;0.01). Masson's stain demonstrated that more collagen deposition was present in wounds of Min/+ relative to WT. In conclusion, this study showed that wound healing was accelerated in Min/+ mice relative to WT. Therefore, even before the loss of the WT allele, Apc heterozygosity likely promotes tumor formation because it affects wound-induced invasive, homing, and engraftment responses of the epithelial stroma. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1429. doi:10.1158/1538-7445.AM2011-1429

Fem1b antigen in the stool of ApcMin mice as a biomarker of early Wnt signaling activation in intestinal neoplasia

Background: Colorectal cancer is preventable by early detection and removal of precursor lesions. Central to early stages of colorectal neoplasia is activation of Wnt signaling, usually due to inactivation of the Apc tumor suppressor gene for which there is an established animal model, the Apc Min mouse. Immunodetection in stool of proteins up-regulated by aberrant Wnt signaling, within intestinal epithelial cells shed into the lumen, could be a rational approach to identify biomarkers of early intestinal neoplasia. Fem1b gene expression is up-regulated, following inactivation of Apc, in mouse intestinal epithelium. Methods: We initially screened pooled random stool samples by immunoblotting and found that we could detect, in Apc Min mice but not wild-type mice, a fragment of Fem1b protein with an antibody (Li-50) directed against an epitope near the middle of the protein, but not with antibodies directed against N-terminus or C-terminus epitopes. We then evaluated freshly voided individual stool samples collected on four consecutive days from four each of male and female Apc Min mice and their wild-type littermates. Results: The Fem1b antigen was detected with the Li-50 antibody in 15/16 samples from male Apc Min mice compared to 0/16 samples from male wild-type mice, and in 5/16 samples from female Apc Min mice compared to 0/16 samples from female wild-type mice. Conclusions: This study provides proof-of-principle that fragments of proteins, whose expression is increased by aberrant Wnt signaling early in intestinal neoplasia, can be immunodetected in stool. Excreted Fem1b protein fragments may be a useful biomarker for epithelial Wnt signaling and early intestinal neoplasia.

Dietary Feeding of Grape Seed Extract Prevents Intestinal Tumorigenesis in APCmin/+ Mice

Chemopreventive effects and associated mechanisms of grape seed extract (GSE) against intestinal/colon cancer development are largely unknown. Herein, we investigated GSE efficacy against intestinal tumorigenesis in APC(min/+) mice. Female APC(min/+) mice were fed control or 0.5% GSE (wt/wt) mixed AIN-76A diet for 6 weeks. At the end of the experiment, GSE feeding decreased the total number of intestinal polyps by 40%. The decrease in polyp formation in the small intestine was 42%, which was mostly in its middle (51%) and distal (49%) portions compared with the proximal one. GSE also decreased polyp growth where the number of polyps of 1 to 2 mm in size decreased by 42% and greater than 2 mm in size by 71%, without any significant change in polyps less than 1 mm in size. Immunohistochemical analyses of small intestinal tissue samples revealed a decrease (80%-86%) in cell proliferation and an increase (four- to eight-fold) in apoptosis. GSE feeding also showed decreased protein levels of cyclooxygenase-2 (COX-2) (56%-64%), inducible nitric oxide synthase (iNOS) (58%-60%), and beta-catenin (43%-59%) but an increased Cip1/p21-positive cells (1.9- to 2.6-fold). GSE also decreased cyclin D1 and c-Myc protein levels in small intestine. Together, these findings show the chemopreventive potential of GSE against intestinal polyp formation and growth in APC(min/+) mice, which was accompanied with reduced cell proliferation and increased apoptosis together with down-regulation in COX-2, iNOS, beta-catenin, cyclin D1, and c-Myc expression, but increased Cip1/p21. In conclusion, the present study suggests potential usefulness of GSE for the chemoprevention of human intestinal/colorectal cancer.

Gender-specific modulation of tumorigenesis by folic acid supply in theApc+/Minmouse during early neonatal life

Epidemiological studies suggest an inverse association between folic acid intake and colorectal cancer risk. Conversely, conventional treatment of existing tumours includes the use of folate antagonists. This suggests that the level of exposure to folate and its timing in relation to stage of tumorigenesis may be critical in determining outcomes. We hypothesised that folic acid depletion in utero and during early neonatal life may affect tumorigenesis in offspring. To investigate this hypothesis, female C57Bl6/J mice were randomised to a folic acid adequate (2 mg folic acid/kg diet) or folic acid depleted diet (0.4 mg folic acid/kg) from mating with Apc+/Min sires and throughout pregnancy and lactation. At weaning the Apc+/Min offspring were randomised to a folic acid adequate (2 mg folic acid/kg diet) or depleted (0.26 mg folic acid/kg diet) diet, creating four in utero/post-weaning dietary regimens. At 10 weeks post-weaning, mice were killed and the intestinal tumour number and size were recorded. Folic acid depletion during pregnancy and post-weaning reduced erythrocyte folate concentrations in offspring significantly. Folic acid depletion during pregnancy and lactation did not affect tumour multiplicity or size. However, female mice fed normal folic acid diets post-weaning had more, and larger, tumours when compared with depleted females and both depleted and adequate folic acid fed males. These data suggest that folate depletion post-weaning was protective against neoplasia in female Apc+/Min mice and highlights the need for further investigation of the optimal timing and dose of folic acid supplementation with regard to colorectal cancer risk.

Surprising Kinetics of the T cell Response to HY (102.25)

Abstract Cooperation of CD4+ and CD8+ T cells is required for the development of primary effector and memory CD8+ T cells following immunization with non-inflammatory immunogens. In this study, we characterized endogenous CD4+ and CD8+ T cell responses to male-specific minor histocompatibility (HY) antigens. We find that male cells are rejected 10–12 days after transfer into female mice of the same strain, and this rejection coincides with the expansion and effector function of CD8+ CTLs to two H-2Db-restricted epitopes. While anti-male CD4+ T cell responses are readily detectable day 5 post-transfer, CD8+ T cell response are not detectable until day 10. The early CD4+ T cell response is not dependent on direct presentation of antigen by donor male cells, but depends on processing and presentation of the male cells by female APC. The primary and recall CD8+ T cell responses and rejection of HY incompatible cells are dependent on a sustained CD4+ T cell response and the absence of this response is not replaced by inflammation or treatment with anti-CD40 agonist Ab. Unexpectedly, HY-specific CD4+ T cells are also capable of efficiently lysing target cells in vivo. The delay in the CD8 effector response can be largely abrogated by depleting T cells from the male inoculum, and we further demonstrate that donor CD8+ T cells in particular suppress or veto the host anti-HY CD8+ T cell responses.

Intestinal‐specific PPARγ deficiency enhances tumorigenesis in ApcMin/+ mice

Multiple investigations of the effects of peroxisome proliferator-activated receptor gamma (PPARgamma) ligands on colon cancer have produced contradictory results. While some studies demonstrated increased numbers of colonic polyps in Apc(Min/+) mice treated with various thiazolidinedione (TZD) PPARgamma ligands, others reported amelioration of tumor multiplicity and progression in both Apc(Min/+) mice and in mice with chemically-induced colon cancer. Here, we addressed the role of PPARgamma in murine intestinal tumorigenesis using gene knockout methodology. We found that either heterozygous or homozygous intestinal-specific PPARgamma deficiency enhanced the number of Apc(Min/+) tumors in both the small intestine and colon, especially in the colon, where PPARgamma deficiency also modulated tumor incidence. Gender significantly affected tumor multiplicity independent of PPARgamma genotype. Female Apc(Min/+) mice developed more tumors in the small intestine and more tumors overall, whereas male Apc(Min/+) mice developed more tumors in the colon. Nevertheless, intestinal PPARgamma deficiency enhanced tumorigenesis irrespective of gender. Our results suggest that PPARgamma functions as a tumor resistance factor in the mouse intestine and warrant further investigation of the PPARgamma-dependent and independent actions of TZDs in cancer.

Myofiber degeneration/regeneration is induced in the cachecticApcMin/+mouse

Cachexia is characterized as an inflammatory state induced by the cancer environment, which is accompanied by the loss of muscle and fat mass. Well-investigated mechanisms of cachexia include the suppression of myofiber protein synthesis and the induction of the protein degradation. However, it is not well characterized whether chronic inflammation during cachexia induces myofiber degeneration, which contributes to muscle mass loss and decreased functional capacity. The purpose of this study was to determine whether Apc(Min/+) mice, which demonstrate a chronic systemic inflammatory state due to an intestinal tumor burden, undergo cachexia and whether the myofibers exhibit signs of degeneration and/or regeneration. Six-month-old female Apc(Min/+) body weight decreased 21% compared with C57BL/6 mice and was not the result of blunted growth. Apc(Min/+) gastrocnemius muscle was reduced 45%, and soleus mean fiber cross-sectional area decreased 24% vs. C57BL/6 mice. Soleus muscle morphology demonstrated pathology of myofibers undergoing degeneration and/or regeneration. These data demonstrate that the Apc(Min/+) mouse becomes cachectic by 6 mo of age and that skeletal muscle degeneration and regeneration may be related to the muscle loss.

Dextran sodium sulfate strongly promotes colorectal carcinogenesis in ApcMin/+ mice: Inflammatory stimuli by dextran sodium sulfate results in development of multiple colonic neoplasms

The mouse model for familial adenomatous polyposis, Apc(Min/+) mouse, contains a truncating mutation in the Apc gene and spontaneously develops numerous adenomas in the small intestine but few in the large bowel. Our study investigated whether dextran sodium sulfate (DSS) treatment promotes the development of colonic neoplasms in Apc(Min/+) mice. Apc(Min/+) and Apc+/+ mice of both sexes were exposed to 2% dextran sodium sulfate in drinking water for 7 days, followed by no further treatment for 4 weeks. Immunohistochemistry for cyclooxygenase-2, inducible nitric oxide synthase, beta-catenin, p53, and nitrotyrosine, and mutations of beta-catenin and K-ras and loss of wild-type allele of the Apc gene in the colonic lesions were examined. Sequential observation of female Apc(Min/+) mice that received DSS was also performed up to week 5. At week 5, numerous colonic neoplasms developed in male and female Apc(Min/+) mice but did not develop in Apc+/+ mice. Adenocarcinomas developed in Apc(Min/+) mice that received DSS showed loss of heterozygosity of Apc and no mutations in the beta-catenin and K-ras genes. The treatment also significantly increased the number of small intestinal polyps. Sequential observation revealed increase in the incidences of colonic neoplasms and dysplastic crypts in female Apc(Min/+) mice given DSS. DSS treatment increased inflammation scores, associated with high intensity staining of beta-catenin, cyclooxygenase-2, inducible nitric oxide synthase and nitrotyrosine. Interestingly, strong nuclear staining of p53 was specifically observed in colonic lesions of Apc(Min/+) mice treated with DSS. Our results suggest a strong promotion effect of DSS in the intestinal carcinogenesis of Apc(Min/+) mice. The findings also suggest that strong oxidative/nitrosative stress caused by DSS-induced inflammation may contribute to the colonic neoplasms development.

Generation of a unique strain of multiple intestinal neoplasia (Apc+/Min‐FCCC) mice with significantly increased numbers of colorectal adenomas

The relevance of the Apc(+/Min) mouse model in the study of human colorectal cancer remains uncertain due to the predominance of small intestinal adenomas and few, if any, colorectal adenomas. A new strain of Apc(+/Min) mice (Apc(+/Min-FCCC)) with significantly greater numbers of colorectal adenomas has been generated and characterized. Male C57BL/6J-Apc(+/Min) mice (the Jackson Laboratory, Bar Harbor, ME) were crossed with wild-type (Apc(+/+)) C57BL/6J females from an independent colony at this institution (offspring=Apc(+/Min-FCCC)) and 233 animals were evaluated over 20 generations. In order to determine the contribution of genetics to the enhanced colorectal adenoma phenotype, breeding pairs (Apc(+/Min) male x wild type female C57BL/6J) were purchased from the Jackson Laboratory and offspring (Apc(+/Min-JAX)) were maintained in our facility under identical conditions (n=98). Animals were fed Purina Rodent chow (#5013) diet containing 5% fat. The entire intestinal tract was examined histopathologically in both strains. Both the Apc and Pla2g2a (candidate for Mom1) genes were sequenced and found to be identical for both the Apc(+/Min-FCCC) and Apc(+/Min-JAX) mouse strains. The multiplicity of colorectal adenomas in the Apc(+/Min-FCCC) mice was much higher than reported in the literature and significantly greater than the multiplicity of colorectal adenomas in Apc(+/Min-JAX) mice maintained in our facility (P=0.01). Apc(+/Min-FCCC) had a significantly greater incidence of rectal prolapse (P = 0.02) and small intestinal adenocarcinomes (P=0.001), and multiplicity of small intestinal adenocarcinomas (P=0.001) compared to Apc(+/Min-JAX) mice. Male Apc(+/Min-FCCC) mice had significantly greater numbers of colorectal adenomas compared to female Apc(+/Min-FCCC) mice (P=0.0002), as did male Apc(+/Min-JAX) mice vs. female Apc(+/Min-JAX) mice (P< 0.0001). These results allow us to conclude: (1) Apc(+/Min-FCCC) mice are unique in that they develop significantly greater numbers of colorectal adenomas and small intestinal cancers, and a significantly greater incidence of small intestinal cancers and rectal prolapse than Apc(+/Min-JAX) mice. (2) This study represents the first report of a significant gender difference in multiplicity of colorectal adenomas. (3) Differences between Apc(+/Min-FCCC) and Apc(+/Min-JAX) mice in currently undefined genetic modifiers may contribute to the enhanced colorectal phenotype. (4) The Apc(+/Min-FCCC) strain is highly suited for the investigation of colorectal neoplastic disease and chemoprevention studies.

Decreased intestinal polyp multiplicity is related to exercise mode and gender in ApcMin/+ mice

Moderate-intensity treadmill running can alter male Apc(Min/+) mouse polyp formation. This purpose of this study was to examine whether exercise mode differentially affects Apc(Min/+) mouse intestinal polyp development in male and female mice. Male and female Apc(Min/+) mice were randomly assigned to control, treadmill (18 m/min; 60 min/day; 6 days/wk), or voluntary wheel running (24-h access) groups. Nine weeks of training decreased total intestinal polyps by 29% in male treadmill runners (66 +/- 9; P = 0.038) compared with male controls (93 +/- 7). The number of large polyps (>/=1-mm diameter) were also reduced by 38% in male treadmill runners (49 +/- 6; P = 0.005) compared with male controls (79 +/- 6). Treadmill running in female Apc(Min/+) mice and wheel running in both genders did not affect polyp number or size. Spleen weight decreased in male treadmill runners (91 +/- 9 mg; P = 0.011) and wheel runners (75 +/- 6 mg; P = 0.004) compared with controls (141 +/- 13 mg). Plasma IL-6 was reduced by 96% in male treadmill runners (1.2 +/- 0.6 pg/ml) and 78% in male wheel runners (6.6 +/- 3.3 pg/ml) compared with control mice (27.9 +/- 2.8 pg/ml; P < 0.05). Female mice responded similarly with an 86% decrease in plasma IL-6 with treadmill running (3.2 +/- 1.2 pg/ml) and 90% decrease with wheel running (2.9 +/- 2.0 pg/ml) compared with control mice (21.1 +/- 5.3 pg/ml; P < 0.05). The crypt depth-to-villus height ratio in the intestine, an indirect marker of intestinal inflammation, decreased by 21 (P = 0.024) and 24% (P = 0.029), respectively, in male and female treadmill runners but not wheel runners. Physical activity-induced attenuation of intestinal polyp number and size is dependent on exercise mode and differs between genders. The modulation of systemic and intestinal inflammation may also depend on exercise mode.