Pancreatic Cancer In Rats Research Articles

The Effect of Graviola Leaves Extract on the Progression of Pancreatic Cancer in Rats

The Effect of Graviola Leaves Extract on the Progression of Pancreatic Cancer in Rats

Analysis of Kras gene from induced pancreatic cancer rats administered with Momordicacharantia and Ocimumbasilicum leaf extracts

ObjectiveTo analyze K-ras gene from induced pancreatic cancer rats administered with Momordicacharantia and Ocimumbasilicum leaf extracts. MethodsTwenty-five (25) adult rats weighing between 90–120 g were divided into 5 groups namely RA, RB, RC, NC and PC, each group had 5 rats. The PC which served as the control was fed with normal fish meal and water ad libitum; the NC which is the negative control received 20 mg/ml/week of Nitrosamines only while other groups received different concentrations of aqueous extract of both M.charantia and O.basilicum (200 mg, 100 mg, 50 mg) and Nitrosamine. Qualitative phytochemical screening of the aqueous extract of both M.charantia and O.basilicum was carried out. The extraction of DNA was done using Jena Bioscience DNA preparation kit and the protocol was based on the spin column based genomic DNA purification from blood, animal and plant cells. Agarose gel electrophoresis was used to analyze the K-ras gene extracted from the pancreas tissues of experimental rats while hematoxylinand eosin staining was used for histological assay. ResultsPhytochemical screening revealed the presence of alkaloids, tannins, flavonoids, saponins and glycosides in M.charantia while saponins, tannins and glycosides were discovered in O.basilicum. Significant reduction in the weight of rats treated with 200 mg of aqueous extracts of M.charantia and O.basilicum while rats that were dosed with nitrosamines only showed a slight increase in weight in the first three weeks when compared to the positive control. Histological studies revealed that there is both enlargement and reduction in the islet cell size, with one of the sections showing a normal islet cell size. While the agarose gel electrophoresis revealed that there may be possibility of prevention of damage to k-ras gene as a result of the effect of plants extract. ConclusionThis work has shown that the leaf extracts of both M.charantia and O.basilicum will serve as a measure against induced pancreatic cancer in rats.

Feasibility and reliability of pancreatic cancer staging using a new confocal non-fluorescent microscopy probe: a double-blind study in rats

Surgical management of pancreatic cancer depends on tumor resectability and staging. Lymph node (LN) metastases represent an important decision-making factor when it comes to surgical treatment. To evaluate a new in vivo, endoscopic confocal microscopy (CM) system not requiring fluorescence markers, for detection and staging of pancreatic cancer in rats. A confocal system consisting of a confocal scanning laser operating in reflection mode and a dedicated rigid Hopkins rod-lens endoscope were used for in vivo imaging in a rat model of pancreatic ductal adenocarcinoma. A double-blind study compared CM to standard histology in (1) the detection of tumors in rat bearing cancer (n=11) and controls (n=6), and (2) in the detection of local nodal involvement at 3 and 6weeks after tumor induction. CM detected all pancreatic tumors with 100% sensitivity and specificity and identified 15 metastatic LNs with an average adenocarcinoma nodule diameter of 2.3mm (range from 1 to 4.2mm) out of the 66 examined. CM demonstrated a sensitivity of 87.5% and a specificity of 98% in LN detection. The Spearman's rank correlation/rho calculator was of 0.87. CM demonstrated a negative predictive value of 96.1% and a positive predictive value of 93.3% in the detection of metastatic LNs. Interpretation of confocal images has a high concurrence rate with histopathology examination for primary tumor and lymphatic involvement detection making it a promising technique for in vivo real-time detection and staging of pancreatic cancer. Larger studies are warranted to confirm these preliminary results.

Mutations in the p16 gene in DMBA-induced pancreatic intraepithelial neoplasia and pancreatic cancer in rats

7, 12-dimethylbenzanthracene (DMBA)-induced pancreatic intraepithelial neoplasia (PanIN) and pancreatic cancer in rats provide a classic model for uncovering the molecular mechanisms underlying pancreatic cancer. However, this model has not been characterized genetically, and in particular, the major genetic alterations in the p16 gene are unknown. Lesions of PanIN and pancreatic cancer were induced with DMBA implantation in 40 rats, and control pancreatic tissue was obtained from 10 age-matched rats without exposure to DMBA. Pancreatic tissue was harvested three months after DMBA implantation and DNA was extracted. Homozygous deletions and point mutations of the p16 (exons 1 and 2) gene were detected by PCR amplification and direct sequencing. DMBA implantation in the 40 rats induced 26 PanINs and 9 carcinomas. The overall frequency of p16 alterations in the pancreatic tissue of these rats was 42.86% (15/35), and the changes were point mutations, not homozygous deletions. p16 mutations were present in 30.77% (8/26) of the rats with PanIN and 77.78% (7/9) of the rats with carcinoma (P<0.05). The increasing incidence of p16 alterations was detected in 20.00% (1/5) of PanIN-1, 28.57% (2/7) of PanIN-2 and 35.71% (5/14) of PanIN-3 lesions. Our findings indicated that p16 alteration is a common event in the carcinogenesis of this model and that the mutation pattern is analogous to that of human lesions.

Expression of DNA-repair proteins and their significance in pancreatic cancer and non-cancerous pancreatic tissues of Sprague–Dawley rats

BackgroundTo establish a model of pancreatic cancer induced by 7,12-dimethylbenzantracene (DMBA) in Sprague–Dawley (SD) rats, and detect the expression of DNA-repair proteins (MGMT, ERCC1, hMSH2, and hMLH1) and their significance in pancreatic cancer and non-cancerous pancreatic tissues of SD rats.MethodsDMBA was directly implanted into the parenchyma of rat pancreas (group A and group B), and group B rats were then treated with trichostatin A (TSA). The rats in both groups were executed within 3 to 5 months, and their pancreatic tissues were observed by macrography and under microscopy. Meanwhile, the rats in the control group (group C) were executed at 5 months. Immunohistochemistry was used to assay the expression of MGMT, ERCC1, hMSH2, and hMLH1.ResultsThe incidence of pancreatic cancer in group A within 3 to 5 months was 48.7% (18/37), including 1 case of fibrosarcoma. The incidence of pancreatic cancer in group B was 33.3% (12/36), including 1 case of fibrosarcoma. The mean of maximal diameters of tumors in group A was higher than that in group B (P <0.05). No pathological changes were found in pancreas of group C and other main organs (except pancreas) of group A and group B. No statistical differences were found among the positive rates of MGMT, ERCC1, hMSH2, and hMLH1 in ductal adenocarcinoma and non-cancerous pancreatic tissues of group A (P >0.05). The positive rates of MGMT, ERCC1, hMSH2, and hMLH1 were significantly lower in ductal adenocarcinoma than those in non-cancerous tissues of group B (P ≤0.05). All pancreas of group C had positive expression of MGMT, ERCC1, hMSH2, and hMLH1 and two cases of fibrosarcoma showed a negative expression.ConclusionsDMBA, directly implanted into the parenchyma of pancreas, creates an ideal pancreatic cancer model within a short time. TSA might restrain DNA damage related to the genesis and growth of pancreatic cancer in rats. The DNA-repair proteins, including MGMT, ERCC1, hMSH2, and hMLH1, might play an important role in the genesis of pancreatic cancer induced by DMBA in rats.

Oligonucleotide Microarray Identifies Genes Differentially Expressed during Tumorigenesis of DMBA-Induced Pancreatic Cancer in Rats

The extremely dismal prognosis of pancreatic cancer (PC) is attributed, at least in part, to lack of early diagnosis. Therefore, identifying differentially expressed genes in multiple steps of tumorigenesis of PC is of great interest. In the present study, a 7,12-dimethylbenzanthraene (DMBA)-induced PC model was established in male Sprague-Dawley rats. The gene expression profile was screened using an oligonucleotide microarray, followed by real-time quantitative polymerase chain reaction (qRT-PCR) and immunohistochemical staining validation. A total of 661 differentially expressed genes were identified in stages of pancreatic carcinogenesis. According to GO classification, these genes were involved in multiple molecular pathways. Using two-way hierarchical clustering analysis, normal pancreas, acute and chronic pancreatitis, PanIN, early and advanced pancreatic cancer were completely discriminated. Furthermore, 11 upregulated and 142 downregulated genes (probes) were found by Mann-Kendall trend Monotone test, indicating homologous genes of rat and human. The qRT-PCR and immunohistochemistry analysis of CXCR7 and UBe2c, two of the identified genes, confirmed the microarray results. In human PC cell lines, knockdown of CXCR7 resulted in decreased migration and invasion. Collectively, our data identified several promising markers and therapeutic targets of PC based on a comprehensive screening and systemic validation.

Abstract 1687: Carcinogen induced inflammation and pancreatic cancer

Abstract National Toxicology Program (NTP) performs two-year cancer bioassays. We have analyzed the NTP rat data base and searched for gender differences in susceptibility to carcinogens. We identified 10 chemicals that induced exocrine pancreatic cancer in male rats only, but found no chemical that induced pancreatic cancer in female rats only. Furthermore, males were most affected by three chemicals that induced pancreatic cancer in both sexes. In an effort to understand this sex difference in susceptibility, we used a tool which builds on the technology published in BMC Bioinformatics 2009, 10, 303. This tool was built to assist cancer risk assessors in the analysis of literature data on modes of action (MOA). We used this tool in the analysis of 2041 PubMed abstracts on the 10 male-specific carcinogens. The tool automatically selected 634 abstracts as relevant for cancer and sorted them in taxonomies. The sorting suggested that induction of oxidative stress and inflammation was a common feature among the 10 carcinogens. As chronic pancreatitis is a risk factor for human exocrine pancreatic cancer, we investigated the effects of the 10 carcinogens on Ca2+ signaling and on inflammatory markers in pancreatic cancer cell line Panc-1. It was found that many the 10 male specific carcinogens rapidly increased intracellular [Ca2+] and interfered with extracellular ATP-induced Ca2+ release in Panc-1 cells. The effect on [Ca2+] was followed by activation of calcineurin and phosphorylation of Erk. Some of these effects were blocked by inhibitors of the purinergic P2X7 receptor, a receptor which may rapidly increase intracellular [Ca2+]. We further studied the induction of mRNA levels of inflammatory mediators, and found that IL8 was significantly up-regulated by most of the 10 chemicals. Our data suggest that inflammation is important for chemically induced exocrine pancreatic cancer in the rat and that male rats are more susceptible. Our data may have a bearing on human pancreatic cancer as men, and in particular young men, have a higher incidence of pancreatic cancer than women. Increased levels of the P2X7 receptor has also been detected in chronic pancreatitis in humans. 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 1687.

Origin and Development of the Precursor Lesions in Experimental Pancreatic Cancer in Rats

Notwithstanding the importance of understanding how pancreatic ductal adenocarcinoma develops, the process remains controversial. A key question is whether the cells of origin of the tubular complexes that constitute precursor lesions are derived from a single cell type or from multiple types. Suggestions that they arise solely from centroacinar cells or ductal cells have been based on inference due to their morphologic appearance in tissue from patients or investigation of limited numbers of tubular complexes in animal models later in the carcinogenic process. The present study establishes clearly that two steps are involved; rapid transdifferentiation to produce tubular complexes followed later by transformation of the component cells. Animals were killed at intervals beginning 1 day after implantation of the carcinogen dimethylbenzanthracene. Transdifferentiation of acinar cells to ductal cells does not require cell division. Transition of lobules to tubular complexes begins by 2 days after implantation of carcinogen. Within 4 days after implantation well-developed tubular complexes are present. Islets participate in the process. Ductal adenocarcinoma is observed by 1 month after implantation of carcinogen. Chymotrypsin and cytokeratin localized by immunocytochemistry indicate acinar and ductal cell characteristics. Acino-ductal transdifferentiation persists in carcinogen-implanted animals, but not in controls implanted with sodium chloride crystals or subjected to sham implantation. The precursor lesions (tubular complexes) are formed by the transdifferentiation of acinar cells and to a lesser extent islet cells, with the incorporation of the duct cells pre-existing in the lobules. Therefore, cells that at one time were acinar cells, islet cells, and duct cells, provide the precursor cells for the ductal adenocarcinoma that develops from tubular complexes. The results raise the question whether the transdifferentiated cells in the tubular complexes of patients with chronic pancreatitis are more susceptible to carcinogenic influences, resulting in the increased rate of pancreatic cancer.

Pancreatic cancer in rats and hamsters does not induce IAPP-related hyperglycaemia.

Many patients with exocrine pancreatic cancer develop diabetes mellitus due to insulin resistance. This may relate to concurrent over-production of islet amyloid polypeptide (IAPP) by the pancreatic beta cells. We investigated the effects of pancreatic cancer on circulating IAPP and glucose homeostasis in azaserine-treated rats (developing acinar pancreatic tumours) and BOP-treated hamsters (developing ductular pancreatic tumours). Glucose, insulin and IAPP levels in plasma were neither affected in azaserine-only treated rats nor in animals with enhanced carcinogenesis after chronic caerulein treatment. Azaserine-treated rats on a high-fat diet had decreased insulin levels and enhanced IAPP/insulin ratios in plasma, without hyperglycaemia. All BOP-treated hamsters showed pancreatic carcinogenesis at 6 months post-treatment. Supranormal plasma glucose levels in animals on a low-fat diet were the only change observed. After a second 6-month period, subnormal plasma glucose levels, at least 4-fold decreased plasma insulin and up to 2-fold decreased plasma IAPP levels were present in all hamsters. Remarkably, both in azaserine-treated rats on high-fat and in BOP-treated hamsters, decreased insulin levels and elevated IAPP/insulin ratios are not associated with hyperglycaemia. In contrast to humans with pancreatic cancer, IAPP over-production and hyperglycaemia do not develop in rats and hamsters with (pre-)neoplastic pancreatic lesions.

Pancreatic cancer in rats and hamsters does not induce IAPP‐related hyperglycaemia

Many patients with exocrine pancreatic cancer develop diabetes mellitus due to insulin resistance. This may relate to concurrent over-production of islet amyloid polypeptide (IAPP) by the pancreatic beta cells. We investigated the effects of pancreatic cancer on circulating IAPP and glucose homeostasis in azaserine-treated rats (developing acinar pancreatic tumours) and BOP-treated hamsters (developing ductular pancreatic tumours). Glucose, insulin and IAPP levels in plasma were neither affected in azaserine-only treated rats nor in animals with enhanced carcinogenesis after chronic caerulein treatment. Azaserine-treated rats on a high-fat diet had decreased insulin levels and enhanced IAPP/insulin ratios in plasma, without hyperglycaemia. All BOP-treated hamsters showed pancreatic carcinogenesis at 6 months post-treatment. Supranormal plasma glucose levels in animals on a low-fat diet were the only change observed. After a second 6-month period, subnormal plasma glucose levels, at least 4-fold decreased plasma insulin and up to 2-fold decreased plasma IAPP levels were present in all hamsters. Remarkably, both in azaserine-treated rats on high-fat and in BOP-treated hamsters, decreased insulin levels and elevated IAPP/insulin ratios are not associated with hyperglycaemia. In contrast to humans with pancreatic cancer, IAPP over-production and hyperglycaemia do not develop in rats and hamsters with (pre-)neoplastic pancreatic lesions. Int. J. Cancer 72:637–641, 1997. © 1997 Wiley-Liss, Inc.

Retinoids and cancer prevention.

As indicated above, in some cases the effects of retinoids appear to be species-specific. Although retinyl acetate and 4-HPR are ineffective in preventing mammary cancer induced by DMBA or occurring spontaneously in mice, these retinoids prevent carcinogen-induced mammary cancer in rats. In contrast, retinoids have modest chemopreventive activity for bladder cancer in various strains of both mice and rats and may have some therapeutic and preventive effects in human bladder. Retinyl palmitate is reported to reduce the incidence of esophageal lesions in hamsters; however, retinyl acetate may increase the incidence of esophageal tumors in rats. Although 13-cis-RA reduces the incidence of spontaneous thymic lymphomas in AKR mice and C57Bl/10W mice exposed to X rays and has some therapeutic effect on myelodysplastic syndromes in humans, 4-HPR may enhance leukemic progression in patients with this syndrome. For treatment of this syndrome, selection of the proper retinoid appears to be important. Topically applied retinyl palmitate reduces the incidence of cervical cancer in hamsters, and topically applied RA has a therapeutic effect on cervical dysplasia in humans. Retinamides have a modest chemopreventive effect against pancreatic cancer in rats dosed with azaserine; these compounds are reported both to increase and to decrease the incidence of pancreatic cancer in hamsters. Retinoids may, or may not, be carcinogen-specific in different species. Some are effective in preventing mammary cancer in rats, regardless of which carcinogen is used. Applied to mouse skin, retinoids are active with either DMBA or BP as the carcinogen and 12-tetradecanoyl phorbol-13-acetate (TPA) as the promoter. Nevertheless, retinoids are not effective in preventing skin papillomas and carcinomas caused by UV light. There is no comparable system for humans, although retinoids demonstrate activity against basal cell carcinomas, squamous cell carcinomas, and actinic keratoses on the skin of humans. Fewer bladder tumors develop in rats dosed with HO-BBN when they are put on diets containing certain retinoids, but those dosed with FANFT are not affected. Similarly, retinyl acetate is reported to be active against liver tumors induced by 3'-MeDAB but not against those induced by aflatoxin B1. In contrast, forestomach carcinomas induced in hamsters by either DMBA or BP are prevented by retinyl palmitate. The route of administration of retinoids may also be important.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of feeding partial and intermittent raw soya flour diets on the rat pancreas

Continuous administration of a diet consisting of raw soya flour produces pancreatic cancer in rats and sensitises the rat pancreas to the action of genotoxic carcinogens. We have therefore studied the effects of continuous feeding of diets containing lesser amounts of raw soya flour (5%, 25% and 50%) and feeding raw soya flour intermittently (2 days each week). The study has shown that a diet containing as little as 5% raw soya flour stimulates focal proliferation of the pancreatic acinar cells and sensitises to the action of azaserine. Similarly, intermittent feeding of raw soya flour induced focal proliferation of the acinar pancreas and, when 100% raw soya flour diet was fed for 2 days each week, resulted in the development of pancreatic cancer in some of the rats. We conclude that raw soya flour must be excluded from the diets of rats used in toxicological and carcinogenicity studies.

Effects of immunosuppressive acidic protein on DMBA-induced pancreatic cancer in rats.

In order to determine the effect of immunosuppressive acidic protein (IAP) on the formation of pancreatic carcinoma, rats of the Sprague-Dawley strain were embedded with 7,12-dimethyl-benzanthracene (DMBA) in the pancreas with and without administration of IAP. In these animals, the growth of pancreatic cancer was studied both immunologically and histologically. Tumor was induced in 51 animals (85%) of 60 treated with embedding of 1 mg DMBA alone. Tumors began to appear from the 16th week after the embedding. Among animals in which tumor was induced, tubular adenocarcinoma and pleomorphic carcinoma accounted for 55% of the cases. When administration of IAP was combined, the period required for development of tumor was shortened. It became shorter with increases in the dosage and frequency of administration of IAP. In animals which received IAP in a mean dose of 75 mg/kg the area showing cancerous changes appeared as early as at the 8th week after the embedding of DMBA. A significant increase in the volume of tumors was seen in the group treated with IAP as compared to the group not treated with IAP. Animals which received IAP in increasing doses and frequencies showed an accelerated increase in the volume of the tumors which underwent cancerous changes. IAP was eliminated from the serum of rats within 72 hr after the administration, and acid protein was clearly recovered from the serum when tumors proliferated. These findings indicate that the acceleration of carcinogenesis in DMBA-induced pancreatic carcinoma may be attributable to the immunosuppressive effect of IAP administered and tend to be dependent on the dosage and frequency of its administration in the early phase of tumor induction.

Metabolism of the cis and trans isomers of N-nitroso-2,6-dimethylmorpholine and their deuterated analogs by liver microsomes of rat and hamster.

Liver microsomes from male Syrian golden hamsters and Sprague Dawley rats metabolize the cis and trans isomers of N-nitroso-2,6-dimethylmorpholine (NNDM) to N-nitroso-(2-hydroxypropyl)(2-oxopropyl)amine (HPOP) as the major product detectable by h.p.l.c. The rates of total metabolism are similar for both the cis and trans isomers; but the cis isomer of NNDM yields greater than 70% of the total product as HPOP while the trans isomer yields HPOP only as a minor product (20-30%) in both hamster and rat. The inability to identify other products could be attributed to alpha-hydroxylation which leads to fragmentation of NNDM and loss of tritium label to water. In order to investigate the possibility of the participation of an alpha-hydroxylation reaction, the metabolism of NNDM fully deuterated at either the 3 and 5 (alpha-d4) or the 2 and 6 (beta-d2) positions was examined and compared to the metabolism of the undeuterated compound (d0). Although the rates of metabolism of all the cis and trans derivatives of NNDM were similar (VMax = 2.13 nmol/min/mg hamster microsomal protein) as determined from measurements of substrate disappearance, the yields of HPOP were different. Maximum HPOP yields were observed with cis alpha-(d4) NNDM (93.9% of the total), followed by cis d0 NNDM (72.3%), trans alpha-(d4) NNDM (60.1%), trans d0 NNDM (30.2%), cis beta-(d2) NNDM (19.5%) and trans beta-(d2) NNDM (8.5%). These results suggest that alpha-hydroxylation is an alternative to beta-hydroxylation. Since the carcinogenic potency of the various deuterium derivatives of NNDM for the Syrian golden hamster parallels their ability to yield HPOP, beta-hydroxylation is closely related to pancreatic carcinogenesis in the hamster. Rat liver microsomal fractions showed the same patterns of HPOP formation to total metabolite yields as hamster liver microsomes with both the cis and trans isomers. However, rates of NNDM metabolism and HPOP formation were 7 times faster with hamster than with rat liver microsomes. Such a difference may be related to the failure of the cis isomer to induce pancreatic cancer in rats.

Potentiation of pancreatic carcinogenesis in the rat by DL-ethionine-induced pancreatitis.

We have assessed the influence of an attack of acute pancreatitis on the incidence of experimentally induced pancreatic cancer in rats. A low-protein diet plus repeated injections of DL-ethionine produced acute pancreatitis in rats. The animals were then fed either a diet of raw soya flour or a non-soya-containing diet and given repeated injections of azaserine, a weak pancreatic carcinogen. The rats that had recovered from acute pancreatitis developed pancreatic cancer, whereas those without previous pancreatitis did not. We conclude that the interaction of recovery from acute pancreatitis with a pancreatic carcinogen predisposes to pancreatic cancer in rats.