Abstract 3686: Microarray analysis of dynamic regulation of genes in early and late stages of chemically induced esophageal carcinogenesis in rats

Esophageal carcinogenesis is a multistage process characterized by morphological changes from normal esophagus to basal cell hyperplasia, dysplasia, carcinoma in situ and squamous cell carcinoma (SCC). Our laboratory has used the model of N-nitrosomethylbenzylamine (NMBA)-induced esophageal SCC in rats to investigate carcinogenesis and identify putative chemopreventive agents for this disease. The current study is part of large scale investigations on carcinogenesis of esophageal SCC. F344 rats were treated with NMBA (0.30 mg/kg b.w.) or a solution of 20% dimethyl sulfoxide (DMSO) in water (the solvent for NMBA) three times per week for five weeks. The esophageal tissues were collected at 6 and 29 weeks. The RNA pools from 3 individual RNA samples each were prepared for microarray analysis using Affymetrix Rat Genome 230 2.0 Array. Triplicate microarrays were completed for total 27 rats/9 microarrays. A P-value cutoff of 0.001 with a minimum 2.0-fold change was used to define the differently expressed genes. Ingenuity Pathway Analysis (IPA) software was used to identify cancer-related pathways and cellular functions. At 6 weeks (tumor incidence = 20%), 173 genes were modulated by NMBA when compared to control animals. Among which, 20 genes were associated with cancer, cellular development, cellular assembly and organization network; 34 genes were associated with inflammatory disease. The top five cellular functions altered by NMBA were cellular development, carbohydrate metabolism, cell death and survival, cellular growth and proliferation, and cellular function and maintenance. At 29 weeks (tumor incidence = 100%), we identified 1628 genes which were significantly up- or down-regulated by NMBA treatment when compared to normal animals and among which, 466 genes were involved in tumor development. In addition, we identified four cancer-related pathways (nuclear factor erythroid 2-related factor 2 mediated oxidative stress response, protein kinase A signaling, mitochondrial dysfunction, and AMP-activated kinase signaling) and five cellular functions (cellular development, cell morphology, cell death and survival, carbohydrate metabolism and molecular transport). Among genes altered during NMBA-induced esophageal carcinogenesis, 16 genes differently expressed only at 6 weeks including Gbp2, Psmb, Psmb9, Lgals3bp, Id1, Igfbp3, Agpat4, rCG_35099, Tes, RGD1563091, Cyp26b1, Itga1, Scarb1, LOC682861, Serpinb2 and Slfn3. The fold changes of Plcd4, Hbb, Bmper, Hba-a2, Defb4, LOC100134871 and LOC364653 increased from 6 weeks to 29 weeks. In conclusion, we identified differently expressed genes in early and late stages of NMBA-induced esophageal SCC by microarray analysis. Further investigations on biomarkers and cellular/molecular events during multistage of carcinogenesis in NMBA-rat preclinical model of esophageal SCC are underway.

Citation Format: Ni Shi, Ronald G. Nines, Lianbo Yu, Michael J. Nicholl, Tong Chen. Microarray analysis of dynamic regulation of genes in early and late stages of chemically induced esophageal carcinogenesis in rats. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3686. doi:10.1158/1538-7445.AM2013-3686

Abstract 1624: Black raspberries suppress phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling pathway in carcinogen-induced esophageal cancer in rats

Esophageal squamous cell carcinoma (SCC) is one of the most common malignant neoplasms worldwide. The overall 5-year survival rate of esophageal SCC in the United States is only 13%, which is close to the observed rates in high-risk countries including China and other global regions. To decrease the incidence of esophageal cancer, cancer chemoprevention through dietary and/or chemical intervention would be a logical and practical approach. Our laboratory and others have used the N-nitrosomethylbenzylamine (NMBA)-induced rat preclinical model of esophageal cancer to investigate the mechanisms of esophageal carcinogenesis and to evaluate the efficacy of potential chemopreventive agents. Studies found that dietary freeze-dried black raspberries (BRBs) significantly inhibited NMBA-induced tumor development in rat esophagus, at least in part by inhibition of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2)), c-Jun, vascular endothelial growth factor (VEGF), and activation of mitogen-activated protein kinase (MAPK) and nuclear factorβB (NFκB) pathways. The phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway plays important roles in certain aspects of carcinogenesis. The principal objective of this study is to assess the roles of this signaling cascade in preclinical esophageal cancer model and examine the mechanistic actions of BRBs against this disease. In the present study, F344 rats were treated with NMBA (0.30 mg/kg b.w.) three times per week for 5 weeks. After 72 hours, animals were fed AIN-76A diet or AIN-76A diet containing 5% BRBs. At week 29, rats were sacrificed and esophageal tumors were counted. Western blot assays were conducted to detect the expression levels of some proteins involved in PI3K/AKT/mTOR pathway. Our data show that in esophageal preneoplastic lesions, BRBs significantly decreased expression levels of p-AKTSer478, p-PI3K-p83, p-S6 and p-mTORSer2448 from 3.2-fold, 5.9-fold, 5.4-fold and 4.4-fold in rats fed control diet to 0.9-fold (P < 0.005), 1.1-fold (P < 0.001), 1.2-fold (P < 0.001) and 1.3-fold (P < 0.001), in rats fed 5% BRBs, respectively. In papillomatous lesions, the expression levels of the above proteins were also reduced by BRBs from 5.3-fold to 1.5-fold (p-AKTSer478; P < 0.001), 6.7-fold to 1.7-fold (p-PI3K-p83, P < 0.001), 8.4-fold to 1.5-fold (p-S6, P < 0.001) and 7.9-fold to 1.7-fold (p-mTORSer2448, P < 0.001). Our results indicated that the PI3K/AKT/mTOR signaling pathway was activated in NMBA-induced tumor development in rats and the activation was significantly suppressed by BRBs. Further investigation of this signaling cascade in esophageal carcinogenesis is underway in our laboratory. (Supported by NCI RO1 CA131073-01A1).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1624. doi:1538-7445.AM2012-1624

Abstract 811: Co-inhibition of cyclooxygenase-2 and inducible nitric oxide synthase prevents N-nitrosomethylbenzylamine-induced esophageal squamous cell carcinoma in rats

Hyperactivation of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) has been observed separately in esophageal squamous cell carcinoma (ESCC) in rats that is induced by N-nitrosomethylbenzylamine (NMBA), a powerful carcinogen found in some human diets. In approach to discover new prevention strategies for ESCC, celecoxib and S,S′-1,4-phenylene-bis(1,2-ethanediyl)bis-isothiourea (PBIT), selective inhibitors respectively to COX-2 and iNOS, were evaluated in the NMBA-rat preclinical esophageal cancer model. F344 rats were treated with NMBA (0.30mg/kg b.w.) three times per week for five weeks. Seventy-two hours after the last NMBA treatment, rats were fed with control diet with or without different doses of celecoxib and PBIT. At week 35, rats were sacrificed and esophageal tumors were counted. Celecoxib (1000 ppm) or PBIT (100 ppm) alone, and a combination treatment with celecoxib (500 ppm) and PBIT (50 ppm), significantly decreased the NMBA-induced tumor multiplicity (from 4.73 ± 0.45 to 2.00 ± 0.25, 1.89 ± 0.23, and 1.61 ± 0.27, respectively), which were accompanied by the inhibition of transcription, translation and kinase activity of both COX-2 and iNOS in all these treatments. By using this COX-2/iNOS co-inhibition strategy, celecoxib/PBIT combination inhibited cancerous esophagus cell proliferation by immunohistochemistry staining of PCNA, and decreased c-Myc expression in NMBA-induced papillomas by Western blot analysis. In addition, the histopathological examination of rat esophagus showed that celecoxib/PBIT combination significantly prevented NMBA-induced tumor transformation (from 8.373% to 1.765%). In conclusion, our results indicated that co-inhibition of COX-2 and iNOS by Celecoxib/PBIT combination prevented NMBA-induced ESCC in rats, which represents a new means of esophageal cancer prevention. (Supported by NIH/NCI RO1 CA131073-01A1).

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 811. doi:10.1158/1538-7445.AM2011-811

Abstract LB-462: Chemopreventive effects of freeze-dried strawberries in inflammation-associated mouse colon tumorigenesis

Colorectal cancer (CRC) is one of the most common malignant neoplasms in the United States. The risk for CRC is associated with extent and duration of inflammatory bowel disease (IBD). Patients with IBD are at increased risk of developing CRC when compared to the general population. Therefore, primary cancer chemoprevention is an important strategy to reduce the risk of CRC in IBD patients and thus, this approach has recently received more attention. Our laboratory has conducted extensive research on cancer chemoprevention in GI tract. In our previous study, we found that dietary freeze-dried black raspberries significantly inhibited adenoma and adenocarcinoma formation and decreased the level of oxidative stress in an azoxymethane (AOM)-induced rat CRC model. In a carcinogen-induced rat esophageal cancer model, we found that dietary freeze-dried strawberries significantly inhibited tumor development. However, the effects of strawberries in inflammation-associated CRC have not been investigated as yet. The principal objective of this study is to investigate the inhibitory effects of dietary freeze-dried strawberries in AOM/Dextran Sodium Sulfate (DSS)-induced mouse colon carcinogenesis. At 4–5 weeks of age, male Crj: CD-1 mice were given a single intraperitoneal injection of AOM (10mg/kg body weight), followed by 2% DSS in their drinking water for seven days, starting one week after the AOM injection. After 3 weeks, animals were fed AIN-76A diet or AIN-76A diet containing 10% freeze-dried strawberries. At week 20, mice were sacrificed for histopathological examination. We found that strawberries significantly decreased tumor incidence from 100% in mice treated with AOM/DSS only to 44.4% in mice treated with AOM/DSS plus strawberries (55.6% reduction, P = 0.02). We also found that the average animal body weight was significantly higher (P = 0.036) in animals fed strawberries (41.9 ± 5.3 g) when compared to animals fed control diet (38.7 ± 3.7 g). A large-scale investigation of the inhibitory effects of strawberries on biomarkers associated with colon carcinogenesis is under way. (Supported by California Strawberry Commissions)

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 LB-462. doi:10.1158/1538-7445.AM2011-LB-462

Abstract 819: Black raspberries inhibit N-nitrosomethylbenzylamine (NMBA)-induced rat esophageal tumorigenesis through down-regulation of MAPK and NFκB pathways

Esophageal cancer is the 6th most common cancer worldwide. Our laboratory has used a rodent preclinical model of esophageal squamous cell carcinoma to identify putative chemopreventive agents for this disease and to determine their mechanisms of action. In our previous studies, we found that freeze-dried black raspberry (BRB) significantly suppressed N-nitrosomethylbenzylamine (NMBA)-induced tumor development in rat esophagus, at least in part by inhibition of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), c-Jun and vascular endothelial growth factor (VEGF). The mitogen-activated protein kinase (MAPK) and nuclear factor κB (NFκB) pathways play important roles in certain aspects of carcinogenesis. However, their roles and effects of BRB on these two pathways in the NMBA model of rat esophageal tumorigenesis have not been investigated yet. In the present study, F344 rats were treated with NMBA (0.30 mg/kg b.w.) three times per week for 5 weeks. After 72 hours, animals were fed AIN-76A diet or AIN-76A diet containing 5% BRB. At week 35, rats were sacrificed and esophageal tumors were counted. The incidence of esophageal tumors was decreased from 100% in NMBA-treated rats to 81.48% (P < 0.05) in rats treated with NMBA+5% BRB. The tumor multiplicity was reduced in rats fed 5% BRB to an average of 1.44 ± 0.25 (P < 0.001) tumors per rat compared with 4.73 ± 2.70 in rats fed the control diet. In preneoplastic lesions, BRB decreased protein expression of phospho-NFκB-p65, phospho-IkBα, phospho-MAPK-p38, phospho-MAPK-p44/42 and phosphor-SAPK/JNK from 4.2-fold, 3.9-fold, 3.1-fold, 4.7-fold and 5.5-fold in rats fed the control diet to 1.2-fold (P < 0.005), 1.3-fold (P < 0.005), 1.3-fold (P < 0.005), 1.4-fold (P < 0.005) and 1.4-fold (P < 0.005), respectively, in rats fed 5% BRB. In papillomatous lesions, BRB reduced protein expression of phospho-NFκB-p65, phospho-IkBα, phospho-MAPK-p38, phospho-MAPK-p44/42 and phosphor-SAPK/JNK from 5.9-fold, 4.7-fold, 5.7-fold, 5.9-fold and 6.1-fold in rats fed the control diet to 1.3-fold (P < 0.005), 1.5-fold (P < 0.005), 1.6-fold (P < 0.005), 1.5-fold (P < 0.005) and 1.6-fold (P < 0.005), respectively, in rats fed 5% BRB. Our results indicated that both MAPK and NFκB pathways were activated in NMBA-induced tumor development in rats and these activations were significantly inhibited by BRB. Collectively, our data suggest that BRB may offer a relatively nontoxic alternative to the prevention of esophageal cancer in humans. (Supported by NCI RO1 CA131073-01A1).

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 819. doi:10.1158/1538-7445.AM2011-819

Abstract LB-423: Combined chemopreventive effects of selective inducible nitric oxide synthase and cyclooxygenase-2 inhibitors on N-Nitrosomethylbenzylamine-induced rat esophageal tumorigenesis

Esophageal cancer is the 6th most common cancer worldwide. Our laboratory has used a rodent preclinical model of esophageal squamous cell carcinoma to identify putative chemopreventive agents for this disease and to determine their mechanisms of action. In our previous studies, we found an association between increased expressions of the inducible nitric oxide synthase (iNOS) and of cyclooxygenase-2 (COX-2) in the development of N-Nitrosomethylbenzylamine (NMBA)-induced tumors in the rat esophagus. We also demonstrated that S, S’-1,4-phenylene-bis(1,2-ethanediyl) bis-isothiourea (PBIT), a selective iNOS inhibitor and celecoxib, a selective COX-2 inhibitor, significantly inhibited NMBA-induced rat esophageal tumorigenesis. In view of these observations, we initiated a study to determine the combination effects of low doses of celecoxib and PBIT on progression of preneoplastic lesions to papillomas in NMBA-treated rats. F344 rats were treated with NMBA (0.30 mg/kg b.w.) three times per week for 5 weeks. After 72 hours, animals were fed AIN-76A diet or AIN-76A diet containing different doses of celecoxib, PBIT, or celecoxib plus PBIT. At week 35, rats were sacrificed and esophageal tumors were counted. The incidence of esophageal tumors was decreased from 100% in NMBA-treated rats to 96.55%, 82.76% (P < 0.05) and 83.33% (P < 0.05) in rats treated with 300, 500 and 1000 ppm celecoxib, respectively. PBIT reduced the tumor incidence to 73.33% (P < 0.001) and 85.19% (P < 0.001) in rats treated with 50 and 100 ppm PBIT, respectively. The combination of celecoxib and PBIT reduced tumor incidence to 66.67% (celecoxib 300 ppm + PBIT 50 ppm; P < 0.001) and 71.43% (celecoxib 500 ppm + PBIT 50 ppm; P < 0.001), respectively. The tumor multiplicity was reduced in rats fed 300, 500 or 1000 ppm celecoxib to an average of 3.07 ± 2.20, 1.90 ± 1.40 (P < 0.05) and 2.00 ± 1.39 (P < 0.05) tumors per rat, respectively, compared with 4.73 ± 2.70 in rats fed the control diet. PBIT reduced the tumor multiplicity to 2.13 ± 1.80 (P < 0.05) and 1.89 ± 1.19 (P < 0.05) in rats fed 50 and 100 ppm PBIT, respectively. The combination of celecoxib and PBIT reduced the tumor multiplicity to 1.59 ± 1.37 (celecoxib 300 ppm + PBIT 50 ppm; P < 0.05) and 1.61 ± 1.42 (celecoxib 500 ppm + PBIT 50 ppm;P < 0.05), respectively. This study demonstrates, for the first time, that combination of low doses of selective iNOS and COX-2 inhibitors improves the efficacy of esophageal cancer prevention in preclinical animal model. The investigation of the cellular and molecular mechanisms of their actions is underway. Our study provided important information and rationale to develop a combination with agents that may have synergistic activity in human clinical trials of chemoprevention of esophageal cancer. (Supported by NIH/NCI RO1 CA131073-01A1).

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 LB-423.

Photochemoprevention of UVB-induced skin carcinogenesis in SKH-1 mice by brown algae polyphenols

Chronic exposure of the skin to ultraviolet B (UVB) radiation induces oxidative stress, which plays a crucial role in the induction of skin cancer. In this study, the effect of dietary feeding and topical application of brown algae polyphenols on UVB radiation-induced skin carcinogenesis in SKH-1 mice was investigated. SKH-1 hairless mice were randomly divided into 9 groups, including control, UVB control and treatment groups. They were treated orally (0.1% and 0.5% with AIN-76 diet, w/w) and topically (3 and 6 mg/0.2 ml of vehicle) with brown algae polyphenols and irradiated with UVB for 26 weeks. Dietary feeding (0.1% and 0.5%) of brown algae polyphenols significantly reduced tumor multiplicity (45% and 56%) and tumor volume (54% and 65%), and topical administration (3 and 6 mg) significantly decreased tumor multiplicity (60% and 46%) and tumor volume (66% and 57%), respectively, per tumor-bearing mouse. Dietary feeding and topical administration of the polyphenols also inhibited tumor incidence by 6% and 21%, respectively, but the results were not significant. Dietary and topical administration of the polyphenols markedly inhibited cyclooxygenase-2 activity and cell proliferation. These observations show that brown algae polyphenols have an antiphotocarcinogenic effect which may be associated with the prevention of UVB-induced oxidative stress, inflammation, and cell proliferation in the skin.

Black raspberries inhibit N-nitrosomethylbenzylamine (NMBA)-induced angiogenesis in rat esophagus parallel to the suppression of COX-2 and iNOS

Angiogenesis, the formation of new blood vessels, is critical to tumor growth and metastasis. Vascular endothelial growth factor (VEGF), an important angiogenic activator, is essential for angiogenesis. Our laboratory has used a rodent model of human esophageal squamous cell carcinoma (ESCC) to identify putative chemopreventive agents for this disease and determine their mechanisms of action. We reported that dietary black raspberry powder (BRB) inhibits N-nitrosomethylbenzylamine (NMBA)-induced tumor development in the rat esophagus by inhibiting the formation of DNA adducts and reducing the proliferation rate of preneoplastic cells. On a molecular level, BRB downregulates the expression of c-Jun, cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS). In this study we analyzed the effect of BRB on angiogenesis. VEGF expression was determined by real-time RT-PCR and immunohistochemical analysis of microvessel density (MVD). BRB significantly suppressed VEGF-C expression from a 2.38 (+/- 0.34)-fold increase in animals treated with NMBA alone to a 1.08 (+/- 0.22)-fold increase in animals treated with NMBA plus BRB (P < 0.005). The MVD of esophagus was decreased from 53.7 +/- 5.6 vessels/cm in animals treated with NMBA alone to 22.6 +/- 2.6 vessels/cm in animals treated with NMBA plus BRB (P < 0.0001). Our data also suggest that downregulation of VEGF is correlated with suppression of COX-2 (r2 = 0.86, P < 0.001) and iNOS (r2 = 0.81, P < 0.005). As high vascularity is a risk factor for metastasis and tumor recurrence, BRB may have cancer therapeutic effects in human esophageal cancer.

Chemopreventive properties of black raspberries in N-nitrosomethylbenzylamine-induced rat esophageal tumorigenesis: down-regulation of cyclooxygenase-2, inducible nitric oxide synthase, and c-Jun

Our laboratory has used a rodent model of human esophageal squamous cell carcinoma to identify putative chemopreventive agents for this disease and to determine their mechanisms of action. In the present study, we treated F344 rats with the esophageal carcinogen, N-nitrosomethylbenzylamine (NMBA), thrice per week for 5 weeks. Beginning 1 week later, they were fed a synthetic diet containing 5% black raspberries (BRB) for the duration of the bioassay (25 weeks). Rats were sacrificed at weeks 9, 15, and 25. Esophageal tissues were collected, and tumor data were recorded. The expression and enzymatic activities of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) as well as the expression of c-Jun in the esophagi, were evaluated to investigate the mechanism(s) by which black raspberries modulate tumorigenesis. At week 25, BRB inhibited tumor multiplicity, the standard end point in this tumor model, from 3.78 +/- 0.41 tumors per rat in NMBA-treated animals to 2.23 +/- 0.21 tumors per rat in animals treated with NMBA plus BRB (P < 0.005). BRB reduced mRNA and protein expression levels of COX-2, iNOS, and c-Jun as well as the level of prostaglandin E(2) in preneoplastic lesions of the esophagus at week 25. The berries inhibited mRNA expression of iNOS and c-Jun, but not COX-2, in papillomatous lesions of the esophagus. Prostaglandin E(2) and total nitrite levels were also decreased by BRB in papillomas. These results suggest a novel tumor suppressive role of BRB through inhibition of COX-2, iNOS, and c-Jun.

Chemopreventive effects of a selective nitric oxide synthase inhibitor on carcinogen-induced rat esophageal tumorigenesis

The inducible nitric oxide synthase (iNOS) generates a high concentration of nitric oxide (NO) in tissues. Increased NO production is associated with many disorders including esophageal cancer. Previous studies in our laboratory demonstrated an association between increased iNOS expression and the development of N-nitrosomethylbenzylamine (NMBA)-induced tumors in the rat esophagus. On the basis of these observations, we initiated a bioassay to evaluate the ability of S,S'-1,4-phenylene-bis(1,2-ethanediyl)bis-isothiourea (PBIT), a selective iNOS inhibitor, to prevent the progression of esophageal tumors in rats preinitiated with NMBA. Rats were given s.c. injections of NMBA (0.25 mg/kg body weight) three times per week for 5 weeks. One week later, they were fed a synthetic diet containing either 50 or 100 ppm PBIT until the end of the bioassay (25 weeks). PBIT reduced the incidence of esophageal cancer from 96% in NMBA-treated rats to 83% and 77% (P < 0.05) in rats treated with 50 and 100 ppm PBIT, respectively. Tumor multiplicity was reduced from 3.64 +/- 0.42 tumors per esophagus in NMBA-treated rats to 1.79 +/- 0.25 (P < 0.001) and 1.50 +/- 0.24 (P < 0.0001) in rats treated with 50 and 100 ppm PBIT, respectively. PBIT reduced the production of NO in NMBA-induced preneoplastic and papillomatous esophageal lesions when compared with comparable lesions in rats treated with NMBA only. iNOS mRNA expression was not modulated by PBIT. These observations suggest that iNOS plays a role in tumor development and that its selective inhibitor, PBIT, significantly inhibits esophageal tumor progression presumably through reducing the production of NO.

Effects of lyophilized black raspberries on azoxymethane-induced colon cancer and 8-hydroxy-2'-deoxyguanosine levels in the Fischer 344 rat

This study examined the effects of lyophilized black raspberries (BRB) on azoxymethane (AOM)-induced aberrant crypt foci (ACF), colon tumors, and urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in male Fischer 344 rats. AOM was injected (15 mg/kg body wt i.p.) once per week for 2 wk. At 24 h after the final injection, AOM-treated rats began consuming diets containing 0%, 2.5%, 5%, or 10% (wt/wt) BRB. Vehicle controls received 5% BRB or diet only. Rats were sacrificed after 9 and 33 wk of BRB feeding for ACF enumeration and tumor analysis. ACF multiplicity decreased 36%, 24%, and 21% (P < 0.01 for all groups) in the 2.5%, 5%, and 10% BRB groups, respectively, relative to the AOM-only group. Total tumor multiplicity declined 42%, 45%, and 71% (P < 0.05 for all groups). Although not significant, a decrease in tumor burden (28%, 42%, and 75%) was observed in all BRB groups. Adenocarcinoma multiplicity decreased 28%, 35%, and 80% (P < 0.01) in the same treatment groups. Urinary 8-OHdG levels were reduced by 73%, 81%, and 83% (P < 0.01 for all groups). These results indicate that BRB inhibit several measures of AOM-induced colon carcinogenesis and modulate an important marker of oxidative stress in the Fischer 344 rat.

Intraoperative detection of occult colon cancer micrometastases using 125 I-radiolabled monoclonal antibody CC49

BACKGROUND

The detection of locally-disseminated disease is one of the principal goals of oncologic surgery. For this study, a hand-held, gamma-detecting probe was used intraoperatively to assess the extent of colorectal carcinoma in patients previously injected with radiolabeled antibody to the TAG-72 antigen (CC49); this technique is known as Radioimmunoguided Surgery (RIGS) (Neoprobe Corporation, Dublin, OH). RIGS-positive areas (i.e. those with increased signal over background) have previously been shown to contain carcinoma in a high proportion of cases. However, some RIGS-positive areas had no tumor detectable by clinical examination or routine histopathologic analysis. This study was undertaken to determine if the presence of occult metastases might account for this disparity.

METHODS

A total of 57 regional lymph nodes (LN), resected from 16 patients with primary (9) or recurrent (7) colorectal carcinoma, were studied. The patients were injected with 125I labeled CC49 murine monoclonal antibody approximately 3 weeks prior to surgery. After routine histologic evaluation, the LN were analyzed for occult metastases; paraffin sections were cut at 5 levels (50 micron apart) and were examined by histology (hematoxylin and eosin stain [H & E]) and by immunohistochemistry (IHC) with a cocktail of monoclonal antibodies to cytokeratins.

RESULTS

Fifty-seven LN were included in this study; 17 were H & E-positive (i.e., contained tumor by routine histologic examination [overt tumor]), while 40 LN were H & E-negative (i.e., no evidence of tumor after routine histologic examination). Thirty-nine LN were RIGS-positive, but only 14 of these were H & E-positive. Of the 25 RIGS-positive/H & E-negative LN, 10 (40%) demonstrated the presence of occult metastases after serial section/IHC analysis. Thus, a total of 27 LN contained metastatic carcinoma (17 overt, 10 occult); routine histologic analysis was able to identify tumor in only 17 of these 27 LN (63%), while the probe signaled the presence of tumor in 24 of these LN (89%). None of the RIGS-negative/H & E-negative LN were found to have occult metastases (0/15). Specific immunoreactivity with CC49 antibody was observed in 5 of 15 RIGS-positive/H & E-negative LN in which no tumor could be identified by any method (histopathology or IHC. CC49 immunoreactivity was not observed in 15 RIGS-negative/H & E-negative LN.

CONCLUSIONS

The finding of a RIGS-positive LN had a significant association with the presence of tumor cells (P < 0.05). In this study, the RIGS procedure was more sensitive than clinical or histopathologic examination in detecting the regional spread of a tumor. Furthermore, in LN that showed no evidence of tumor by routine histopathologic examination, a positive RIGS reading was significantly associated with the presence of occult LN metastases (P < 0.01). This study is the first to demonstrate the detection of histologically occult tumor by a remote imaging device. RIGS assessment is a highly sensitive method for detecting occult tumor deposits, and may guide therapeutic intervention in patients with colorectal carcinoma.