Increase In Number Of Tumors Research Articles

Relationship between whole-body tumor burden and quality of life in patients with neurofibromatosis.

6136 Background: NF1, NF2, and schwannomatosis are a group of related genetic disorders in which affected individuals share the predisposition to develop multiple nerve sheath tumors. While previous studies have investigated the relationship between cutaneous tumor burden and quality of life, the relation between internal tumors and quality of life is unknown. Methods: As part of an IRB-approved research study, we performed whole-body MRI and administered the short form (SF)-36 to 245 adult subjects with NF. The number and location of internal nerve sheath tumors in each patient was identified by a board-certified radiologist and tumor volume was calculated using semi-automated volumetric analysis. One sample t-tests were used to compare subjects’ SF-36 scores to general population means. Independent linear regression analyses controlling for age and gender effects were used to relate whole-body tumor count, volume, and distribution (via Gini coefficient) to each domain of the SF-36. Results: 245 patients (142 with NF1, 53 with NF2, 50 with schwannomatosis) completed the study. On the SF-36, subjects with NF1 showed reduced quality of life in the physical role, emotional role, and mental health domains compared to the normal population (p<0.05). Subjects with NF2 showed reductions in the physical functioning, physical role, general health, and social functioning domains while subjects with schwannomatosis showed reductions in the physical role and bodily pain domains (p<0.05). In linear regression analysis, increased tumor number, increased tumor volume, and decreased Gini coefficient were correlated with decreased physical functioning in patients with NF2 (p<0.01). There was also a trend for increasing tumor volume to be correlated with decreased physical role and increased bodily pain in patients with NF1 and with increased bodily pain in patients with schwannomatosis (p<0.10). Conclusions: In our multi-institutional cohort, patients with all forms of neurofibromatosis show selected deficits in quality of life. Internal tumor burden does not correlate with these deficits, with the exception of physical function in NF2 patients.

Chronic Inflammation in the Pathogenesis of COPD and Lung Cancer

Chronic obstructive pulmonary disease (COPD) and lung cancer are leading causes of morbidity and mortality worldwide. At least 85 to 90% of all COPD and human lung cancers are related to cigarette smoke (CS), but genetic susceptibility and environmental factors also contribute to the pathogenesis. Chronic airway inflammation has been indicated as a major risk factor in COPD and has been suggested to be associated with an increased risk of human cancer, including lung cancer. Therefore, we hypothesize that COPD and lung cancer may share chronic inflammation as one of the common pathogenic mechanisms. We developed two animal exposure paradigms to elucidate roles of chronic inflammation in COPD and lung cancer. In the COPD study, mice were separated into four treatment groups: filtered-air control, lipopolysaccharides (LPS), CS, and LPS1CS. For the lung cancer study, mice were assigned into four different treatment groups: saline control, LPS, NNK (a major cigarette smoke carcinogen), and LPS1NNK. Mice were killed after 4 to 6 months of treatment and lung tissues were collected to assess alveolar space enlargement, lung tumors, and the inflammatory response. The LPS group showed increased inflammation but no alveolar space enlargement or tumor formation. LPS1CS displayed enhanced alveolar space enlargement when compared with CS alone, but neither group developed lung tumor. On the lung cancer study, we observed a more than sixfold increase in tumor numbers in the LPS1NNK group compared with the NNK alone group, but no alveolar space enlargement was observed. There were significant increases of inflammatory cells, particularly macrophages, in all treatment groups except NNK and controls. The increased alveolar macrophage population displayed an alternatively activated M2 phenotype in both COPD and lung cancer models. Our results suggest that chronic inflammation enhances emphysemalike alveolar space enlargement and also synergistically promotes cigarette smoke carcinogen–induced lung tumorigenesis.

Hepatocyte Nuclear Factor 4 alpha (HNF4α) Knockdown Stimulates Pro‐Mitogenic Gene Expression in Hepatocytes

HNF4α, the master regulator of hepatocyte differentiation, has been shown to inhibit hepatocyte proliferation via yet to be identified mechanisms. We investigated the mechanisms of HNF4α‐induced inhibition of hepatocyte proliferation using two novel HNF4α knockdown mouse models. Hepatocyte specific deletion of HNF4α resulted in increased hepatocyte proliferation. Comparative global gene expression analysis revealed a set of genes commonly regulated in both HNF4α deletion models. The majority of the down‐regulated genes are known HNF4α target genes involved in hepatic differentiation. Interestingly, many up‐regulated genes were associated with cell proliferation and cancer. HNF4α knockdown mice treated with the known hepatic carcinogen diethylnitrosamine developed a 7‐fold increase in number of tumors, as compared to controls. Furthermore, in vitro over expression of HNF4α in mouse HCC cells resulted in a decrease in cell proliferation along with a decrease in promitogenic gene expression. Taken together these data indicate that HNF4α inhibits hepatocyte proliferation by repression of specific pro‐mitogenic genes.

Inhibition of Pancreatic Stellate Cell Activation by Halofuginone Prevents Pancreatic Xenograft Tumor Development

Most solid tumors consist of neoplastic and nonneoplastic cells and extracellular matrix components. In the pancreas, activated stellate cells (PSCs) are the source of the extracellular matrix proteins. We evaluated the significance of PSC activation in tumor establishment and development in mouse xenografts. Xenografts were established by implanting human pancreatic cancer cells (MiaPaca-2) subcutaneously or orthotopically by injecting them into the spleen. Fibrosis was induced by cerulein. Collagen level was evaluated by Sirius red staining. Prolyl 4-hydroxylase β and stellate cell activation-associated protein (Cygb/STAP) were determined by immunohistochemistry. Halofuginone inhibited subcutaneous tumor development implanted with Matrigel and reduced collagen and prolyl 4-hydroxylase β levels. Few tumors, which developed slowly, were observed after MiaPaca-2 implantation without Matrigel. Increase in tumor number and rate of development were observed with addition of PSCs from control pancreas, and further increase was observed when the PSCs were from cerulein-treated mice. Preincubation of the PSCs with halofuginone elicited Cygb/STAP level reduction and tumor growth inhibition. More tumors developed orthotopically in cerulein-treated mice than in controls; this was prevented by halofuginone. Extracellular matrix production by activated PSCs is essential for tumor establishment and growth. Thus, inhibition of PSC activation is a viable means of reducing pancreatic tumor development.

Abstract 2318: Induction of Rac1b by MMP-3 causes lung tumors by activating EMT

Abstract During development, epithelial cells acquire mesenchymal characteristics through a process known as epithelial-mesenchymal transition (EMT). Substantial evidence now exists that EMT-related processes play a major role in tumor progression. EMT is a focus of interest in lung cancer as loss of E-cadherin expression confers increased resistance to several types of chemotherapy. In previous studies, we found that matrix metalloproteinase-3 (MMP3) induced EMT in mouse mammary epithelial cells through induction of Rac1b, an alternatively spliced isoform of Rac1. We now show that exposure to MMPs stimulates Rac1b and induction of EMT markers in human lung cancer cell lines, and that knockdown of Rac1b blocks MMP induced EMT. We also show that Rac1b expression levels in human lung tumor biopsies is predictive of patient outcome, and that Rac1b and MMP expression levels are correlated in these samples, suggesting a direct relationship. We also describe the generation of new transgenic mouse models for which MMP3 or Rac1b is inducibly expressed in lung epithelial cells; activation of kRAS in these mice reveals that expression of MMP3 or Rac1b promotes increased tumor number, size, and progression to adenocarcinoma as well as increased expression of EMT markers vimentin, sm-actin, col1a1, and Snail. We also show that expression of Rac1b in lung epithelial cells leads to spontaneous adenocarcinoma formation. These results demonstrate a direct linkage between induction of EMT and tumor progression, implicate Rac1b as a key mediator of these processes, and demonstrate that MMPs can directly stimulate all of these events. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2318.

Krüppel-like factor 5 is a crucial mediator of intestinal tumorigenesis in mice harboring combined Apc Min and KRASV 12mutations

BackgroundBoth mutational inactivation of the adenomatous polyposis coli (APC) tumor suppressor gene and activation of the KRAS oncogene are implicated in the pathogenesis of colorectal cancer. Mice harboring a germline ApcMin mutation or intestine-specific expression of the KRASV12 gene have been developed. Both mouse strains develop spontaneous intestinal tumors, including adenoma and carcinoma, though at a different age. The zinc finger transcription factor Krüppel-like factor 5 (KLF5) has previously been shown to promote proliferation of intestinal epithelial cells and modulate intestinal tumorigenesis. Here we investigated the in vivo effect of Klf5 heterozygosity on the propensity of ApcMin/KRASV12 double transgenic mice to develop intestinal tumors.ResultsAt 12 weeks of age, ApcMin/KRASV12 mice had three times as many intestinal tumors as ApcMin mice. This increase in tumor number was reduced by 92% in triple transgenic ApcMin/KRASV12/Klf5+/- mice. The reduction in tumor number in ApcMin/KRASV12/Klf5+/- mice was also statistically significant compared to ApcMin mice alone, with a 75% decrease. Compared with ApcMin/KRASV12, tumors from both ApcMin/KRASV12/Klf5+/- and ApcMin mice were smaller. In addition, tumors from ApcMin mice were more distally distributed in the intestine as contrasted by the more proximal distribution in ApcMin/KRASV12 and ApcMin/KRASV12/Klf5+/- mice. Klf5 levels in the normal-appearing intestinal mucosa were higher in both ApcMin and ApcMin/KRASV12 mice but were attenuated in ApcMin/KRASV12/Klf5+/- mice. The levels of β-catenin, cyclin D1 and Ki-67 were also reduced in the normal-appearing intestinal mucosa of ApcMin/KRASV12/Klf5+/- mice when compared to ApcMin/KRASV12 mice. Levels of pMek and pErk1/2 were elevated in the normal-appearing mucosa of ApcMin/KRASV12 mice and modestly reduced in ApcMin/KRASV12/Klf5+/- mice. Tumor tissues displayed higher levels of both Klf5 and β-catenin, irrespective of the mouse genotype from which tumors were derived.ConclusionsResults of the current study confirm the cumulative effect of Apc loss and oncogenic KRAS activation on intestinal tumorigenesis. The drastic reduction in tumor number and size due to Klf5 heterozygosity in ApcMin/KRASV12 mice indicate a critical function of KLF5 in modulating intestinal tumor initiation and progression.

Histological analysis of low dose NMU effects in the rat mammary gland

BackgroundOur objective was to assess the histological changes in mammary glands of the female Wistar-Furth rat as a result of low dose exposure to N-nitrosomethylurea (NMU).MethodsGroups of 30–40 virgin female rats of between 49–58 days old received a single injection of 10, 20, 30 or 50 mg NMU/kg body weight (BW). A group of 10 control rats received 0.9% NaCl solution only. The formation of palpable mammary gland tumors was assessed weekly and, upon sacrifice at 12, 22 and 25–30 weeks after treatment, we performed a comprehensive histological analysis of all mammary gland lesions and tumors.ResultsAlongside the predicted increase in tumor number and decrease in tumor latency with increasing NMU dose, we observed a number of microscopic lesions and other epithelial abnormalities in the mammary glands for all NMU doses. Two types of non-neoplastic histological changes were observed in rats exposed to 10 or 20 mg NMU/kg BW: namely, (i) an increase in the number of acinar structures often accompanied by secretion into the lumen which is normally associated with pregnancy and lactation, and (ii) an increase in the number of epithelial cells sloughed into the lumen of the epithelial ducts.ConclusionThis study establishes a baseline for low-dose exposure and defines the histological features in the mammary gland resulting from NMU exposure. Furthermore, this system provides an ideal platform for evaluating the relative susceptibility of animals protected from, or predisposed to, developing cancer through environmental influences.

The Ets dominant repressor En/Erm enhances intestinal epithelial tumorigenesis in ApcMin mice

BackgroundEts transcription factors have been widely implicated in the control of tumorigenesis, with most studies suggesting tumor-promoting roles. However, few studies have examined Ets tumorigenesis-modifying functions in vivo using model genetic systems.MethodsUsing mice expressing a previously characterized Ets dominant repressor transgene in the intestinal epithelium (Villin-En/Erm), we examined the consequences of blocking endogenous Ets-mediated transcriptional activation on tumorigenesis in the ApcMin model of intestinal carcinoma.ResultsEn/Erm expression in the intestine, at levels not associated with overt crypt-villus dysmorphogenesis, results in a marked increase in tumor number in ApcMin animals. Moreover, when examined histologically, tumors from En/Erm-expressing animals show a trend toward greater stromal invasiveness. Detailed analysis of crypt-villus homeostasis in these En/Erm transgenic animals suggests increased epithelial turnover as one possible mechanism for the enhanced tumorigenesis.ConclusionOur findings provide in vivo evidence for a tumor-restricting function of endogenous Ets factors in the intestinal epithelium.

High Sucrose Diets Promote Intestinal Epithelial Cell Proliferation and Tumorigenesis in APC Min Mice by Increasing Insulin and IGF-I Levels

Epidemiological studies report that high sucrose consumption is associated with increased risk of colon cancer. One hypothesis is that this association is mediated by elevated circulatory insulin and IGF levels promoting intestinal proliferation. To test this hypothesis, APC Min mice and their wild type littermates were fed, starting at 4 wk of age, sucrose or cornstarch as the sole carbohydrate source in the absence or presence of low levels of dietary sulindac for 10 or 16 wk, respectively. APC Min mice fed sucrose had an increased tumor number in the proximal third of the small intestine in both studies and a higher incidence of papillary colon tumors in the 16-wk feeding study ( P ≤ 0.05). Mice fed sucrose (relative to cornstarch) had higher body weights and greater Ki67-labeling indexes in colonic epithelium than mice fed cornstarch in both feeding studies ( P ≤ 0.05). Furthermore, mice fed sucrose had higher serum glucose and liver IGF-I mRNA concentrations ( P ≤ 0.05) and tended to have higher serum insulin levels ( P = 0.08). These results support the hypothesis that high dietary sucrose intake promotes intestinal proliferation and tumorigenesis by increasing circulating levels of insulin and IGF-I.

Estrogen promotes tumor progression in a genetically defined mouse model of lung adenocarcinoma

Numerous epidemiological observations point to sex differences in lung cancer etiology and progression. The present study was aimed at understanding the bases of these sex differences. To test the effect of estradiol on tumor progression, we used a mouse model based on conditional Kras expression and concurrent deletion of Tp53 following inhalation of an adenoviral vector expressing Cre recombinase (AdeCre). Ovariectomized females and males were treated with estradiol via a continuous-release capsule. Tumor multiplicity, tumor volume, and histological grade were determined at 10 weeks after AdeCre administration. Cell proliferation was monitored by Ki67 immunohistochemistry at 4 and 10 weeks after AdeCre administration. At 10 weeks, female mice had more than twice the number of tumors evident on the surface of the lungs than male mice; ovariectomy eliminated this sex difference. The estrogen treatment significantly increased tumor number and volume in ovariectomized females and in males. Histological character of the tumors ranged from adenoma to adenocarcinoma. Ovary-intact females exhibited higher grade tumors than ovariectomized females or males. Progression to higher histological grade was stimulated by estrogen in male mice but not in ovariectomized females. At 10 weeks after AdeCre administration, tumor cell Ki67-labeling varied widely, precluding assessment of an estrogen effect; however, at 4 weeks, Ki67 labeling of lung parenchymal cells was increased 3.5-fold by estrogen. In conclusion, estrogen acts as a promoter for lung adenocarcinoma in a genetically defined lung cancer model; estrogen-induced cell proliferation in the oncogene-initiated cells is likely to play a role in this tumor promoter activity.

JP-8 jet fuel exposure potentiates tumor development in two experimental model systems

The US Air Force has implemented the widespread use of JP-8 jet fuel in its operations, although a thorough understanding of its potential effects upon exposed personnel is unclear. Previous work has reported that JP-8 exposure is immunosuppressive. Exposure of mice to JP-8 for 1 h/day resulted in immediate secretion of two immunosuppressive agents; namely, interleukin-10 (IL-10) and prostaglandin E2 (PGE2). Thus, it was of interest to determine if jet fuel exposure might promote tumor growth and metastasis. The syngeneic B16 tumor model was used for these studies. Animals were injected intravenously with tumor cells, and lung colonies were enumerated. Animals were also examined for metastatic spread of the tumor. Mice were either exposed to 1000 mg/m3 JP-8 (1 h/ day) for 7 days before tumor injection or were exposed to JP-8 at the time of tumor injection. All animals were killed 17 days after tumor injection. In the present study, JP8 exposure potentiated the growth and metastases of B16 tumors in an animal model. Exposure of mice to JP-8 for 1 h/day before tumor induction resulted in an approximately 8.7-fold increase in tumors, whereas those mice exposed to JP8 at the time of tumor induction had a 5.6-fold increase in tumor numbers. Thus, low concentration JP-8 jet fuel exposures have significant immune suppressive effects on the immune system that can result in increased tumor formation and metastases. We have now extended the observations to an experimental subcutaneous tumor model. JP8 exposure at the time of tumor induction in this model did not affect the growth of the tumor. However, JP8-exposed, tumor-bearing animals died at an accelerated rate as compared with air-exposed, tumor-bearing mice.

Adiposity-Related Protection of Intestinal Tumorigenesis: Interaction With Dietary Calcium

Although high-calcium diets have been reported to reduce the risk of colorectal cancer, our preliminary data with the adenomatous polyposis coli (Apc) Min mutation (Min/+;ApcMin/+) mouse shows a paradoxical increase in intestinal tumor loads (> 65%) with high calcium diets. Since we previously demonstrated that increasing dietary calcium reduces adiposity, and ApcMin/+ mice on high calcium diets exhibited profound loss of adipose tissue, we hypothesized that loss of an adipose tissue-derived tumor suppressor factor(s) resulted in increased tumor susceptibility in animals on the high calcium diet. Accordingly, tumor prone ApcMin/+ mice were crossed with obesity prone lethal yellow agouti (A y /a) mice to generate obese Ay/ApcMin/+ mice. Low (0.2%), normal (0.5%), and high (1.2%) calcium diets were fed to both Ay/Apc Min/+ mice and ApcMin/+ mice from 35–40 days until 90 days of age (n = 21/strain, n = 7/diet group). The high calcium diet reduced weight gain in both strains (P < 0.01) and reduced fat pad mass by 46–57% in A y /ApcMin/+(P < 0.004) and by 65–82% in ApcMin/+(P < 0.03).ApcMin/+ mice on the high calcium diet exhibited an increase in tumor number (76 vs. 29, P = 0.009), but this effect was not seen in the Ay/ApcMin/+ mice.β-Catenin and cyclin D1 gene expression were significantly induced with high calcium diet in intestinal tumor tissue of ApcMin/+ mice but not in Ay/ApcMin/+ mice. We conclude that the differential effect of dietary calcium on intestinal tumorigenesis in lean vs. obese ApcMin/+ may result from the loss of adipose-derived protective factor(s) due to the substantial loss of body fat in ApcMin/+ mice fed a high calcium dairy diet, increasingβ-catenin and cyclin D1 in tumors.

Depletion of CD4+ Cells Exacerbates the Cutaneous Response to Acute and Chronic UVB Exposure

Solid organ transplant recipients have a 60-250-fold increased likelihood of developing sunlight-induced squamous cell carcinoma (SCC) compared with the general population. This increased risk is linked to the immunosuppressive drugs taken by these patients to modulate T cell function, thus preventing organ rejection. To determine the importance of T cells in the development of cutaneous SCC, we examined the effects of selectively depleting Skh-1 mice of systemic CD4+ or CD8+ T cells, using monoclonal antibodies, on ultraviolet B (UVB) radiation-induced inflammation and tumor development. Decreases in systemic CD4+ but not CD8+ T cells significantly increased and prolonged the acute UVB-induced cutaneous inflammatory response, as measured by neutrophil influx, myeloperoxidase activity, and prostaglandin E2 levels. Significantly more p53+ keratinocytes were observed in UVB-exposed CD4-depleted than in CD4-replete mice, and this difference was abrogated in mice depleted of neutrophils before UVB exposure. Increased acute inflammation was associated with significantly increased tumor numbers in CD4-depleted mice chronically exposed to UVB. Furthermore, topical treatment with the anti-inflammatory drug celecoxib significantly decreased tumor numbers in both CD4-replete and CD4-depleted mice. Our findings suggest that CD4+ T cells play an important role in modulating both the acute inflammatory and the chronic carcinogenic response of the skin to UVB.

Matrix Metalloproteinase-9 from Bone Marrow–Derived Cells Contributes to Survival but not Growth of Tumor Cells in the Lung Microenvironment

The role of specific stromal-derived matrix metalloproteinases (MMPs) was analyzed in experimental metastasis assays in wild-type and either MMP-9, MMP-7, or MMP-2 null mice. MMP-9 null mice showed an 81% reduction in Lewis lung carcinoma tumor number, whereas MMP-7 null mice showed a 42% increase in tumor number, and there was no difference in tumor number in MMP-2 null mice compared with wild-type controls. Similarly, in an orthotopic model of lung cancer, 50% fewer MMP-9 null mice were able to establish tumors in the lung compared with control mice, although the size of the tumors was not different. The effect of MMP-9 on lung tumor colonization was dependent on the expression of MMP-9 from bone marrow-derived cells and is most likely contributed by neutrophils. To examine temporal effects of stromal MMP-9, bioluminescence imaging from luciferase-expressing human lung cancer-derived A549 cells revealed that there were fewer tumor cells in the lungs of MMP-9 null mice as early as 19 hours after injection compared with control mice, with no difference in subsequent growth rates. Six hours after injection of tumor cells, MMP-9 null mice showed a 4-fold increase in the percent of tumor cells undergoing apoptosis compared with control mice. We conclude that MMP-9 from the bone marrow contributes to the early survival and establishment of tumors in the lung and has no effect on subsequent growth. These results provide insights into the failure of MMP inhibitors in clinical trials in patients with late-stage lung cancer.

The role of NO synthases in arginine-dependent small intestinal and colonic carcinogenesis

Arginine is catabolized by NOS2 and other nitric oxide synthases to form nitric oxide. We evaluated the roles of dietary arginine and Nos2 in Apc-dependent intestinal tumorigenesis in Min mice with and without a functional Nos2 gene. NOS2 protein was expressed only in intestinal tissues of Apc(Min/+) Nos2+/+ mice. NOS3 expression was higher in intestinal tissues of mice lacking Nos2, mainly in the small intestine. When diet was supplemented with arginine (0.2% and 2% in drinking water), lack of Nos2 results in decreased tumorigenesis in both small intestine and colon. In Nos2 knockout mice, supplemental arginine (up to 2%) caused a decrease in small intestinal tumor number and size. The arginine-dependent decrease was associated with an increase in nitrotyrosine formation and apoptosis in the region of intestinal stem cells. Mice expressing Nos2 did not show these changes. These mice did, however, show an arginine-dependent increase in colon tumor number and incidence, while no effect on apoptosis was seen. These changes were associated with increased nitrotyrosine formation in epithelial cells. Mice lacking Nos2 did not show changes in tumorigenesis or nitrotyrosine formation, while demonstrating an arginine-dependent increase in apoptosis. These data suggest that Nos2 and dietary arginine have significant effects on intestinal and colonic tumorigenesis in Min mice. In both tissues, loss of Nos2 is associated with decreased tumorigenesis when mice are supplemented with dietary arginine. In the small intestine, Nos2 prevents the arginine-induced decrease in tumor number and size, which is associated with NOS3 expression and increased apoptosis. In the colon, Nos2 is required for the arginine-induced increase in tumor number and incidence.

Raltitrexed increases tumorigenesis as a single agent yet exhibits anti-tumor synergy with 5-fluorouracil in ApcMin/+ Mice1

The thymidylate synthase (TS) inhibitors raltitrexed (RTX) and 5-fluorouracil (FUra) have shown promising anti-tumor activity in preclinical and clinical settings for the treatment of colorectal cancer. Though the effects of these two agents have been reasonably wellcharacterized in cell lines, knowledge of their modes of action in vivo is limited. Here, we utilize the ApcMin/+ mouse, an animal model of intestinal tumorigenesis, to study the effects of RTX treatment alone and in combination with FUra. Rather surprisingly, RTX monotherapy resulted in a dose dependent 4-10-fold increase in tumor number. The majority of these adenomas (74- 95%) were rather small (i.e., less than 1 mm in diameter) and exhibited loss of heterozygosity at the Apc locus, suggesting an increase in mutational events leading to tumor development. RTX augmented BrdU-labeling of crypt epithelial cells, and retarded the movement of these cells along the crypt-villus axis. Co-administration of FUra and RTX resulted in a significant reduction in tumor number compared to mice treated with either RTX or FUra alone (P < 0.0001). In addition, FUra abrogated the RTX-mediated increase in BrdU labeling. In all, the results show that RTX increases tumor burden in the ApcMin/+ mouse, yet enhances the anti-tumor effect of FUra. This is the first illustration of in vivo synergy of RTX and FUra in a genetically predisposed animal model. Possible mechanisms underlying the current observations are discussed.

Matrix metalloproteinase activity modulates tumor size, cell motility, and cell invasiveness in murine aggressive fibromatosis.

Matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) regulate the degradation of extracellular matrix components and play important roles in the progression of select neoplastic processes. The locally invasive soft tissue tumor, aggressive fibromatosis (also called desmoid tumor), is caused by mutations resulting in beta-catenin-mediated T-cell factor (tcf)-dependent transcriptional activity. Because beta-catenin can regulate MMP expression, we investigated the expression of several MMPs and TIMPs in aggressive fibromatosis tumors that develop in Apc+/Apc1638N mice. Mmp-3 and Timp-1 were differentially regulated (5-fold and 0.5-fold, respectively) in tumors compared with normal fibrous tissue. Conditioned media from tumor cells showed an increased ability to degrade collagen, and inhibition of MMPs using GM6001 decreased the ability of the tumor cells to invade through Matrigel. Both the treatment of Apc/Apc1638N mice with GM6001 or crossing with a transgenic mouse that overexpresses Timp-1 resulted in a significant reduction in tumor volume. Surprisingly, overexpression of Timp-1 also resulted in a 50% increase in tumor number. Although TIMP-1 can induce growth stimulatory effects in some cell types, we found no difference in proliferation or apoptosis rate in cells from tumors that developed in the Timp-1-transgenic mice compared with mice that did not express the Timp-1 transgene, suggesting that TIMP-1 promotes aggressive fibromatosis tumor formation through an alternate mechanism. These data suggest that MMPs play a crucial role in regulating the invasiveness of mesenchymal cells and in modulating aggressive fibromatosis tumor progression. Because this is a locally invasive tumor, MMP inhibition could slow tumor growth and may prove to be an effective adjuvant therapy.

The anti-ischemia agent ranolazine promotes the development of intestinal tumors in APC(Min/+) mice

Ranolazine was shown to improve exercise parameters in patients with chronic angina. It works by switching myocardial energy metabolism from fatty acids to glucose, thus increasing the efficiency of ATP production under hypoxic conditions. Tumors are hypoxic and may also respond to ranolazine. We found that ranolazine caused a dose-dependent increase in tumor number in APC(Min/+) mice, a model of spontaneous intestinal tumorigenesis. Tumors from drug-treated mice were also more dysplastic and invasive than those from untreated mice. These findings have implications for the use of ranolazine in patients with a history of malignant neoplasms or adenomatous polyps.

The anti-ischemia agent ranolazine promotes the development of intestinal tumors in APC (Min/+) mice

Ranolazine was shown to improve exercise parameters in patients with chronic angina. It works by switching myocardial energy metabolism from fatty acids to glucose, thus increasing the efficiency of ATP production under hypoxic conditions. Tumors are hypoxic and may also respond to ranolazine. We found that ranolazine caused a dose-dependent increase in tumor number in APC (Min/+) mice, a model of spontaneous intestinal tumorigenesis. Tumors from drug-treated mice were also more dysplastic and invasive than those from untreated mice. These findings have implications for the use of ranolazine in patients with a history of malignant neoplasms or adenomatous polyps.

Progressive alterations in global and GC-rich DNA methylation during tumorigenesis.

DNA methylation plays a key role in the regulation of gene expression, and failure to maintain normal patterns of methylation often contributes to carcinogenesis. We have characterized progressive methylation changes during the promotion stage of carcinogenesis using a SENCAR mouse skin initiation/promotion tumorigenesis model. Mice were initiated with a dermal application of 75 microg dimethylbenz[a]anthracene (DMBA) and promoted with 9, 18, 27, and 36 mg cigarette smoke condensate (CSC) thrice weekly for time periods up to 29 weeks, when a large increase in tumor number was produced by the highest three doses. Global and GC-specific methylation were assessed using SssI methylase and arbitrarily primed PCR, respectively. Changes in GC-specific methylation were dose- and time-dependent. CSC doses required to detect these changes were 27 mg at 6 weeks and 18 mg at 9 weeks. This effect appears to be reversible; changes in GC-specific methylation were less marked after 9 weeks promotion with 27 mg CSC followed by 6 weeks of recovery in comparison to 9 and 15 weeks promotion with 27 mg CSC and no recovery period. Both tumor and non-tumor tissue promoted with 27 mg CSC for 29 weeks exhibited changes in GC-specific methylation that were more pronounced in tumors. Tumor tissue was globally hypomethylated, whereas non-tumor tissue did not exhibit changes in global methylation. In conclusion, as expected for a mechanism underlying tumor promotion, CSC alters methylation in a threshold-exhibiting, reversible, progressive fashion during promotion. Progressive alterations in global and GC-rich methylation appear to be mechanistically important during tumor promotion.