Gender Difference in DNA Damage Induced by the Environmental Carcinogen Dibenzo[def,p]chrysene Individually and in Combination with Mouse Papillomavirus Infection in the Mouse Oral Cavity

Tobacco smoking and human papillomavirus infection are established etiological agents in the development of head and neck squamous cell carcinoma (HNSCC). The incidence and mortality of HNSCC are higher in men than women. To provide biochemical basis for sex differences, we tested the hypothesis that carcinogen treatment using dibenzo[def,p]chrysene, which is an environmental pollutant and tobacco smoke constituent, in the absence or presence of the mouse papillomavirus infection results in significantly higher levels of DNA damage in the oral cavity in male than in female mice. However, the results of the present investigation do not support our hypothesis since we found that females were more susceptible to carcinogen-induced covalent DNA damage than males independent of the viral infection. Since DNA damage represents only a single-step in the carcinogenesis process, additional factors may contribute to sex differences in humans.

Complementarity between Microbiome and Immunity May Account for the Potentiating Effect of Quercetin on the Antitumor Action of Cyclophosphamide in a Triple-Negative Breast Cancer Model

Immunotherapy targeting program cell death protein 1 (PD-1) in addition to chemotherapy has improved the survival of triple-negative breast cancer (TNBC) patients. However, the development of resistance and toxicity remain significant problems. Using the translationally relevant 4T1 mouse model of TNBC, we report here that dietary administration of the phytochemical quercetin enhanced the antitumor action of Cyclophosphamide, a cytotoxic drug with significant immunogenic effects that is part of the combination chemotherapy used in TNBC. We observed that quercetin favorably modified the host fecal microbiome by enriching species such as Akkermansia muciniphilia, which has been shown to improve response to anti-PD-1 therapy. We also show that quercetin and, to a greater extent, Cyclophosphamide increased the systemic frequency of T cells and NK cells. In addition, Cyclophosphamide alone and in combination with quercetin reduced the frequency of Treg, which is consistent with an antitumor immune response. On the other hand, Cyclophosphamide did not significantly alter the host microbiome, suggesting complementarity between microbiome- and immune-mediated mechanisms in potentiating the antitumor action of Cyclophosphamide by quercetin. Overall, these results support the potential for microbiota-centered dietary intervention to overcome resistance to chemoimmunotherapy in TNBC.

First Generation of Antioxidant Precursors for Bioisosteric Se-NSAIDs: Design, Synthesis, and In Vitro and In Vivo Anticancer Evaluation

The introduction of selenium (Se) into organic scaffolds has been demonstrated to be a promising framework in the field of medicinal chemistry. A novel design of nonsteroidal anti-inflammatory drug (NSAID) derivatives based on a bioisosteric replacement via the incorporation of Se as diacyl diselenide is reported. The antioxidant activity was assessed using the DPPH radical scavenging assay. The new Se-NSAID derivatives bearing this unique combination showed antioxidant activity in a time- and dose-dependent manner, and also displayed different antiproliferative profiles in a panel of eight cancer cell lines as determined by the MTT assay. Ibuprofen derivative 5 was not only the most antioxidant agent, but also selectively induced toxicity in all the cancer cell lines tested (IC50 < 10 µM) while sparing nonmalignant cells, and induced apoptosis partially without enhancing the caspase 3/7 activity. Furthermore, NSAID derivative 5 significantly suppressed tumor growth in a subcutaneous colon cancer xenograft mouse model (10 mg/kg, TGI = 72%, and T/C = 38%) without exhibiting any apparent toxicity. To our knowledge, this work constitutes the first report on in vitro and in vivo anticancer activity of an unprecedented Se-NSAID hybrid derivative and its rational use for developing precursors for bioisosteric selenocompounds with appealing therapeutic applications.

Abstract 5451: New organoselenium compounds with cytotoxic activity in vitro and in vivo towards colon cancer

Colon cancer is currently the third most common diagnosed cancer and the second leading cause of cancer death worldwide. The inclusion of a selenium atom (Se) in organic molecules has been shown to be a valid approximation in the design of novel chemotherapeutic agents with antitumoral activity. On the other hand, non-steroidal anti-inflammatory drugs (NSAIDs) have gained interest in recent years in terms of their chemopreventive and chemotherapeutic use for cancer treatment whether they are evaluated alone, as a combination therapy, or in the form of structurally modified analogs. Considering these findings, we have designed five novel NSAID derivatives containing Se in their structure. The cytotoxicity and selectivity of the new compounds were evaluated in a panel of 10 cancer cell lines including breast, prostate, lung, and colon cancer, and in two non-malignant cell lines. Compound 5 was the most cytotoxic derivative with IC50 values below 10 µM in all the cancer cell lines tested, and it was also the most selectively toxic towards cancer cells while sparing the non-malignant cell lines. The efficacy of compound 5 in vivo was assessed in a subcutaneous colon cancer xenograft mouse model and it showed a significant inhibition of the tumor growth. Taken together, this work supports that the novel Se-NSAID combination provides a feasible frame to develop new agents with potent antitumoral properties

Citation Format: Sandra Ramos-Inza, Cesar Aliaga, Asif Raza, Ignacio Encío, Arun Sharma, Carmen Sanmartín, Daniel Plano. New organoselenium compounds with cytotoxic activity in vitro and in vivo towards colon cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5451.

Black raspberry restores the expression of the tumor suppressor p120ctn in the oral cavity of mice treated with the carcinogen dibenzo[a,l]pyrene diol epoxide

One of the major risk factors for head and neck squamous cell carcinoma (HNSCC) is tobacco smoke exposure, but the mechanisms that can account for disease development remain to be fully defined. Utilizing our HNSCC mouse model, we analyzed oral squamous cell carcinomas (OSCC) induced by the active metabolite of a common smoke constituent, dibenzo[a,l]pyrene diol-epoxide (DBPDE). Analyzing protein expression by either immunofluorescence or immunohistochemistry, we identified biologic processes that are dysregulated in premalignant and invasive cancer lesions induced by DBPDE. Interestingly, p120ctn expression is downregulated in both stages of the disease. In addition to decreased p120ctn expression, there was also increased proliferation (as measured by Ki67), inflammation (as measured by NFkB (p65) expression), neovascularization (as measured by CD31) and recruitment of Ly6G-positive immune cells as well as strong EGFR expression. We also examined the effect of the chemopreventive agent black raspberry (BRB) on p120ctn and EGFR protein expression in DBPDE treated mice. p120ctn, but not EGFR, protein expression increased in mice treated with BRB. Our results suggest that modulation of p120ctn may, in part, account for the mechanism by which BRB inhibits DBPDE induced OSCC in mice.

Abstract 2596: Stage-specific inhibition of NNK-induced lung carcinogenesis by 1,4-phenylenebis(methylene)seleno-aspirin (p-XS-Asp)

Chemopreventive efficacy of p-XSC is well documented but it failed due to systemic toxicity issues. This toxicity could partially be due to the release of poisonous hydrogen cyanide generated after p-XSC metabolizes to form active bis-selenol (p-XSeH). To address the said concern, we recently designed and developed p-XS-Asp, with the rationale that it would cleave in vivo to release the active p-XSeH and aspirin instead of undesired HCN, thus making the compound less toxic and possibly more potent than p-XSC. Indeed, we have shown previously that p-XS-Asp inhibits NNK-induced lung tumorigenesis in A/J mice more effectively than p-XSC in a complete A/J mouse model, and is better tolerable. The complete model, however, does not reveal at what stage of carcinogenesis does p-XS-Asp acts. In the current study, we evaluated the stage-specificity of chemopreventive efficacy of p-XS-Asp in NNK-induced lung carcinogenesis in A/J mice models. A/J mice were divided into 7 distinct groups (n=30 per group, half male, half female; except group 1 and 2 where n=10). The mice were fed AIN-93M diet (control) or p-XS-Asp diet until they reached termination end point of 26 weeks (adenomas) and 40 weeks (adenocarcinomas). Two weeks after the experiment started, all the groups, except for group 1 and 2, were given a single IP injection of 10 µmol (100 mg/kg) of NNK. Group 3 and 4 were on complete control AIN93M and p-XS-Asp diets, respectively. Group 5 (peri-initiation) was on p-XS-Asp for the first 3 weeks and then on the control diet till the end of the experiment. On the other hand, group 6 (post-initiation) was on control diet for 3 weeks and then was changed to the p-XS-Asp diet. In the progression group 7, mice were on control diet for 14 weeks and subsequently changed to p-XS-Asp diet. The Groups 4 and 5 mice showed a remarkable decrease in the tumor multiplicity (TM) and incidence (TI) as compared to the mice on control diet at both 26 and 40 week time-points. The TM in male mice for groups 1, 2, 3, 4, 5, 6 and 7 at 26 weeks was 0.6, 0, 5.7, 1, 1.54, 4.27, and 6.27, respectively, while at 40 weeks, it was 0.2, 0, 7.7, 1, 1.8, 4.1, and 4.9, respectively. A similar trend was also observed in female mice. These data clearly demonstrated that robust inhibition at peri-initiation stage is mainly responsible for the activity observed in the complete model. The inhibition of both O6-methylguanine and pyridoxobutyl mutagenic DNA adducts by p-XS-Asp further compliments that the compound acts at initial stages of carcinogenesis. Body weights comparison and the blood and tissue analyses showed no systemic toxicity for the p-XS-Asp fed groups. RNA-seq data of the tumor tissues showed numerous signaling pathways to be affected in p-XS-Asp treated mice. The exact mechanism of action is still under investigation. In summary, our results show that p-XS-Asp may be promising candidate for future clinical evaluation as a lung cancer preventive agent.

Citation Format: Asif Raza, Amandeep Singh, Cesar Aliaga, Daniel Plano, Shantu Amin, Arun K. Sharma. Stage-specific inhibition of NNK-induced lung carcinogenesis by 1,4-phenylenebis(methylene)seleno-aspirin (p-XS-Asp) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2596.

Effects of E-Cigarette Aerosols with Varying Levels of Nicotine on Biomarkers of Oxidative Stress and Inflammation in Mice

To provide insights into the cause of e-cigarette (e-cig) associated lung injury, we examined the effects of propylene glycol (PG) and glycerol (G), two common solvent carriers used to deliver nicotine/flavor, on markers of oxidative stress and inflammation in female B6C3F1 mice which had been used successfully in tobacco smoke (TS)-induced lung carcinogenesis. Mice exposed to air and TS were used as negative and positive controls, respectively. Using LC-MS/MS, we showed that PG/G alone, in the absence of nicotine, significantly increased the levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG or its tautomer 8-oxodG), a biomarker of DNA oxidative damage, in lung and plasma of mice; moreover, addition of nicotine (12 and 24 mg/mL) in e-cig liquid appears to suppress the levels of 8-oxodG. Exposure to e-cig aerosols or TS induced nonsignificant increases of plasma C-reactive protein (CRP), a biomarker of inflammation; nonetheless, the levels of fibronectin (FN), a biomarker of tissue injury, were significantly increased by e-cig aerosols or TS. Although preliminary, our data showed that exposure to e-cig aerosols induced a higher score of lung injury than did control air or TS exposure. Our results indicate that the B6C3F1 mouse model may be suitable for an in-depth examination of the impact of e-cig on lung injury associated with oxidative stress and inflammation and this study adds to the growing evidence that the use of e-cig can lead to lung damage.

Mechanistic Basis for In Vivo Therapeutic Efficacy of CK2 Inhibitor CX-4945 in Acute Myeloid Leukemia

Simple Summary

Acute Myeloid Leukemia is an aggressive disease with poor outcomes. New targeted therapies that can boost the effects of currently used chemotherapy medications without added toxicity are needed. Targeting an overactive kinase, called the protein Kinase CK2 in AML, helps leukemia cells undergo cell death and helps certain chemotherapy drugs work better. Here, we present evidence that CX-4945, a CK2 inhibitor drug, effectively kills leukemia cells in mouse models and shows the mechanism of action responsible for these effects. Leukemia cells are more sensitive to a decrease in CK2 kinase levels than normal cells. Our results show that inhibiting CK2 kinase makes AML cells more susceptible to anthracycline-induced cell death. Anthracyclines like daunorubicin and doxorubicin are widely used to treat leukemia in children and adults. A rational combination of protein kinase CK2 inhibitors with the standard of care chemotherapy may help treat AML more effectively.

Abstract

Protein Kinase CK2 (Casein Kinase 2 or CK2) is a constitutively active serine-threonine kinase overactive in human malignancies. Increased expression and activity of CK2 in Acute Myeloid Leukemia (AML) is associated with a poor outcome. CK2 promotes AML cell survival by impinging on multiple oncogenic signaling pathways. The selective small-molecule CK2 inhibitor CX-4945 has shown in vitro cytotoxicity in AML. Here, we report that CX-4945 has a strong in vivo therapeutic effect in preclinical models of AML. The analysis of genome-wide DNA-binding and gene expression in CX-4945 treated AML cells shows that one mechanism, by which CK2 inhibition exerts a therapeutic effect in AML, involves the revival of IKAROS tumor suppressor function. CK2 phosphorylates IKAROS and disrupts IKAROS’ transcriptional activity by impairing DNA-binding and association with chromatin modifiers. Here, we demonstrate that CK2 inhibition decreases IKAROS phosphorylation and restores IKAROS binding to DNA. Further functional experiments show that IKAROS negatively regulates the transcription of anti-apoptotic genes, including BCL-XL (B cell Lymphoma like–2 like 1, BCL2L1). CX-4945 restitutes the IKAROS-mediated repression of BCL-XL in vivo and sensitizes AML cells to apoptosis. Using CX-4945, alongside the cytotoxic chemotherapeutic drug daunorubicin, augments BCL-XL suppression and AML cell apoptosis. Overall, these results establish the in vivo therapeutic efficacy of CX-4945 in AML preclinical models and determine the role of CK2 and IKAROS in regulating apoptosis in AML. Furthermore, our study provides functional and mechanistic bases for the addition of CK2 inhibitors to AML therapy.

The environmental pollutant and tobacco smoke constituent dibenzo[def,p]chrysene is a co-factor for malignant progression of mouse oral papillomavirus infections

HPV infections in the oral cavity that progress to cancer are on the increase in the USA. Model systems to study co-factors for progression of these infections are lacking as HPVs are species-restricted and cannot grow in preclinical animal models. We have recently developed a mouse papillomavirus (MmuPV1) oral mucosal infection model that provides opportunities to test, for the first time, the hypothesis that tobacco carcinogens are co-factors that can impact the progression of oral papillomas to squamous cell carcinoma (SCC). Four cohorts of mice per sex were included: (1) infected with MmuPV1 and treated orally with DMSO-saline; (2) infected with MmuPV1 and treated orally with the tobacco carcinogen, dibenzo[def,p]chrysene (DBP); (3) uninfected and treated orally with DMSO-saline, and (4) uninfected and treated orally with DBP. Oral swabs were collected monthly for subsequent assessment of viral load. Oral tissues were collected for in situ viral DNA/RNA detection, viral protein staining, and pathological assessment for hyperplasia, papillomas and SCC at study termination. We observed increased rates of SCC in oral tissue infected with MmuPV1 and treated with DBP when compared to mice treated with DBP or virus individually, each of which showed minimal disease. Virally-infected epithelium showed strong levels of viral DNA/RNA and viral protein E4/L1 staining. In contrast, areas of SCC showed reduced viral DNA staining indicative of lower viral copy per nucleus but strong RNA signals. Several host markers (p120 ctn, p53, S100A9) were also examined in the mouse oral tissues; of particular significance, p120 ctn discriminated normal un-infected epithelium from SCC or papilloma epithelium. In summary, we have confirmed that our infection model is an excellent platform to assess the impact of co-factors including tobacco carcinogens for oral PV cancerous progression. Our findings can assist in the design of novel prevention/treatment strategies for HPV positive vs. HPV negative disease.

Black Raspberry Inhibits Oral Tumors in Mice Treated with the Tobacco Smoke Constituent Dibenzo(def,p)chrysene Via Genetic and Epigenetic Alterations

We previously reported that the environmental pollutant and tobacco smoke constituent dibenzo[def,p]chrysene (DBP) induced DNA damage, altered DNA methylation and induced oral squamous cell carcinoma (OSCC) in mice. In the present study, we showed that 5% dietary black raspberry (BRB) significantly reduced (P < 0.05) the levels of DBP-DNA adducts in the mouse oral cavity with comparable effect to those of its constitutes. Thus, only BRB was selected to examine if aberrant DNA methylation induced by DBP can be altered by BRB. Using comparative genome-wide DNA methylation analysis, we identified 479 hypermethylated and 481 hypomethylated sites (q < 0.01, methylation difference >25%) between the oral tissues of mice treated with DBP and fed control diet or diet containing BRB. Among the 30 differential methylated sites (DMS) induced by DBP, we found DMS mapped to Fgf3, Qrich2, Rmdn2, and Cbarp were hypermethylated by BRB whereas hypomethylated by DBP at either the exact position or proximal sites; DMS mapped to Vamp3, Ppp1rB1, Pkm, and Zfp316 were hypomethylated by BRB but hypermethylated by DBP at proximal sites. In addition to Fgf3, 2 DMS mapped to Fgf4 and Fgf13 were hypermethylated by BRB; these fibroblast growth factors are involved in regulation of the epithelial-mesenchymal transition (EMT) pathway as identified by IPA. Moreover, BRB significantly reduced (P < 0.05) the tumor incidence from 70% to 46.7%. Taken together, the inhibitory effects of BRB on DNA damage combined with its effects on epigenetic alterations may account for BRB inhibition of oral tumorigenesis induced by DBP. SIGNIFICANCE: We provided mechanistic insights that can account for the inhibition of oral tumors by BRB, which could serve as the framework for future chemopreventive trials for addicted smokers as well as non- or former smokers who are exposed to environmental carcinogens.

Synthesis and evaluation of new heteroaryl nitrones with spin trap properties

A new series of heteroaryl nitrones were synthesized and evaluated as free radical traps due to the results showed in our previous report. The physicochemical characterization of these new nitrones by electron spin resonance (ESR) demonstrated their high capability to trap and stabilize different atom centered free radicals generated by the Fenton reaction. Additionally, we intensely studied them in terms of their physicochemical properties. Kinetic studies, including the use of a method based on competition and the hydroxyl adduct decay, gave the corresponding rate constants and half-lives at the physiological pH of these newly synthesized nitrones. New nitrones derived from quinoxaline 1,4-dioxide heterocycles were more suitable than DMPO to trap hydroxyl free radicals with a half-life longer than two hours. We explain some of the results using computational chemistry through density functional theory (DFT).

A new series of heteroaryl nitrones were synthesized and evaluated as free radical traps due to the results showed in our previous report.

Comparative Tumorigenicity and DNA Damage Induced by Dibenzo[ def,p]chrysene and Its Metabolites in the Mouse Ovary

Ovarian cancer ranked second in incidence among gynecologic cancers, but it causes more deaths than any other gynecologic cancer; at present there is no curative treatment beyond surgery. Animal models that employ carcinogens found in the human environment can provide a realistic platform to understand the mechanistic basis for disease development and to design rational chemopreventive/therapeutic strategies. We and others have shown that the administration of the environmental pollutant and tobacco smoke constituent dibenzo[ def,p]chrysene (DBP) to mice by several routes of exposure can induce tumors in multiple sites including the ovary. In the present study we compared, for the first time, the tumorigenicity and DNA damage induced by DBP and its metabolites DBP-dihydrodiol (DBPDHD) and DBP-dihydrodiol epoxide (DBPDE) in the mouse ovary. Compounds were dissolved in dimethyl sulfoxide (DMSO) as the vehicle and administered by topical application into the mouse oral cavity three times per week for 38 weeks. No tumors were observed in mice treated with DMSO. At equal dose (24 nmol/30 μL DMSO), the incidence of ovarian tumors induced by DBPDHD was higher (60.7%), although not significantly, than that induced by DBP (44.8%). Similarly the levels of DNA damage induced by DBPDHD in the ovary were higher than those observed with DBP. We did not observe any histological abnormality in the ovary of mice treated with DBPDE, which is consistent with lack of DNA damage. Our results suggested that both DBP and DBPDHD can be metabolized in the mouse ovary leading to the formation of DBPDE that can damage DNA, which is a prerequisite step in the initiation stage of carcinogenesis.

Abstract 274: Selective chemopreventive efficacy of 1,4-phenylenebis(methylene)seleno-aspirin (p-XS-Asp) towards lung cancer

1,4-Phenylenebis(methylene)selenocyanate (p-XSC) has been shown to inhibit tobacco carcinogen NNK induced lung tumor development in several animal models. This had placed p-XSC on the National Cancer Institute´s (NCI) list of chemopreventive agents for clinical development, but there were systemic toxicity issues. p-XSC metabolizes through the formation of active bis-selenol (p-XSeH) along with the release of poisonous hydrogen cyanide (HCN). We recently developed p-XS-Asp, with a rationale that it would cleave in vivo to release the active p-XSeH and aspirin, thus making the compound less toxic and possibly more potent than p-XSC. Indeed, we previously presented (AACR Annual Meeting 2014) that p-XS-Asp inhibited NNK-induced lung tumorigenesis in A/J mice more effectively than p-XSC, and was also more tolerable. At doses of 15 ppm and 7.5 ppm Se, p-XS-Asp showed a significantly marked decrease in the percentage of lung cancer incidence in vivo with only 50% and 87% of tumor incidence, as compared to p-XSC (79% and 100%), respectively. NNK-control showed an 100% tumor incidence. Likewise, the tumor multiplicity for p-XS-Asp group was 0.87 and 1.93 tumors/mouse as compared to the NNK-control (11.53) and p-XSC (1.66 and 4.10 tumors/mouse, respectively) at the two doses tested. Notably, blood chemistry and tissue analyses did not show systemic toxicity for the p-XS-Asp fed group.

We have now evaluated the underlying mechanisms of lung cancer preventive action of p-XS-Asp and its efficacy for inhibiting azoxymethane (AOM)- and dimethyl hydrazine (DMH)-induced Aberrant Crypt Foci (ACF) in Fischer F344 rats. At a dose of 7.5 ppm Se, p-XS-Asp was able to restore the expression of several genes (MMP9, COX-2, Myc, SphK1 and RELA), that were over-expressed in the NNK group, to control or even lower levels. The AKT1 gene expression was much lower in the lung tissue of p-XS-Asp treated mice at this dose compared to both negative and NNK control groups. Therefore, p-XS-Asp might be exerting its chemopreventive effect on NNK-induce lung tumorigenesis via inhibiting COX-2 mediated PI3K/Akt signaling pathway.

Interestingly, contrary to the striking inhibition of lung tumorigenesis, p-XS-Asp failed to significantly inhibit AOM- or DMH-induced formation of ACF in Fischer F344 rats. In both AOM and DMH models, aspirin (positive control) significantly reduced the number of ACF and large ACF per area (cm2) by 37.4% and 33.8%, respectively. On the other hand, both p-XSC and p-XS-Asp showed no significant inhibitory effect on the formation of ACF and large ACF. Taken together, our results have shown p-XS-Asp to selectively prevent the lung, but not colon, tumorigenesis, and thus is a promising candidate for further development as a lung cancer preventive agent.

Citation Format: Daniel Plano, Srinivasa Ramisetti, Sang-Yub Kim, Manoj Pandey, Cesar Aliaga, Deepkamal N. Karelia, Arthur Berg, Carmen Sanmartin, Junxuan Lu, Shantu Amin, Arun K. Sharma. Selective chemopreventive efficacy of 1,4-phenylenebis(methylene)seleno-aspirin (p-XS-Asp) towards lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 274.

On the interactions of TEMPO radicals with gold nanostructures

Nitroxide radicals do not bind with Au nanostructures through the –NO˙ moiety.

Effects of Black Raspberry on Dibenzo[a,l]Pyrene Diol Epoxide Induced DNA Adducts, Mutagenesis, and Tumorigenesis in the Mouse Oral Cavity

We previously showed that metabolic activation of the environmental and tobacco smoke constituent dibenzo[a,l]pyrene (DB[a,l]P) to its active fjord region diol epoxide (DB[a,l]PDE) is required to induce DNA damage, mutagenesis, and squamous cell carcinoma (SCC) in the mouse oral cavity. In contrast to procarcinogens, which were employed previously to induce SCC, DB[a,l]PDE does not require metabolic activation to exert its biological effects, and thus, this study was initiated to examine, for the first time, whether black raspberry powder (BRB) inhibits postmetabolic processes, such as DNA damage, mutagenesis, and tumorigenesis. Prior to long-term chemoprevention studies, we initially examined the effect of BRB (5% added to AIN-93M diet) on DNA damage in B6C3F1 mice using LC/MS-MS and on mutagenesis in the lacI gene in the mouse oral cavity. We showed that BRB inhibited DB[a,l]PDE-induced DNA damage (P < 0.05) and mutagenesis (P = 0.053) in the oral cavity. Tumor incidence in the oral cavity (oral mucosa and tongue) of mice fed diet containing 5% BRB was significantly (P < 0.05) reduced from 93% to 66%. Specifically, the incidence of benign tumor was significantly (P < 0.001) reduced from 90% to 31% (62% to 28% in the oral cavity and 28% to 2% in the tongue), a nonsignificant reduction of malignant tumors from 52% to 45%. Our preclinical findings demonstrate for the first time that the chemopreventive efficacy of BRB can be extended to direct-acting carcinogens that do not require phase I enzymes and is not just limited to procarcinogens. Cancer Prev Res; 11(3); 157-64. ©2017 AACR.

Hypomethylated Fgf3 is a potential biomarker for early detection of oral cancer in mice treated with the tobacco carcinogen dibenzo[def,p]chrysene

Genetic and epigenetic alterations observed at end stage OSCC formation could be considered as a consequence of cancer development and thus changes in normal or premalignant tissues which had been exposed to oral carcinogens such as Dibenzo[def,p]chrysene (DBP) may better serve as predictive biomarkers of disease development. Many types of DNA damage can induce epigenetic changes which can occur early and in the absence of evident morphological abnormalities. Therefore we used ERRBS to generate genome-scale, single-base resolution DNA methylomes from histologically normal oral tissues of mice treated with DBP under experimental conditions known to induce maximum DNA damage which is essential for the development of OSCC induced by DBP in mice. After genome-wide correction, 30 and 48 differentially methylated sites (DMS) were identified between vehicle control and DBP treated mice using 25% and 10% differences in methylation, respectively. RT-PCR was further performed to examine the expressions of nine selected genes. Among them, Fgf3, a gene frequently amplified in head and neck cancer, showed most prominent and significant gene expression change (2.4× increases), despite the hypomethylation of Fgf3 was identified at >10kb upstream of transcription start site. No difference was observed in protein expression between normal oral tissues treated with DBP or vehicle as examined by immunohistochemistry. Collectively, our results indicate that Fgf3 hypomethylation and gene overexpression, but not protein expression, occurred in the early stage of oral carcinogenesis induced by DBP. Thus, Fgf3 hypomethylation may serve as a potential biomarker for early detection of OSCC.

Abstract 236: Stearoyl-CoA desaturase-1, a novel target of omega-3 fatty acids for reducing breast cancer risk in obese postmenopausal women

Preclinical and epidemiologic data suggest that a unique feature of lipogenesis in cancer cells which has received limited attention is the accumulation of monounsaturated fatty acids (MUFA) which are largely derived from saturated fatty acids (SFA) by the action of stearoyl-Co-A desaturase (SCD-1). Activation of SCD-1, a delta-9 fatty acid desaturase, is considered to be an important factor in the development of obesity and several types of cancer including breast cancer. However, no data are available on how changes in SCD-1 activity induced by potential chemopreventive agents relate to established biomarkers of breast cancer risk. To address this issue, we measured the activity of SCD-1, expressed as the ratios of palmitoleic acid (C16:ln7) to palmitic acid (C16:0) (SCD-16) and oleic acid (C18:ln9) to steric acid (C18:0) (SCD-18) in plasma samples of postmenopausal women enrolled in our recently published clinical trial (Sandhu N, et al Cancer Prev Res 9:275, 2016) designed to test the individual and combined effect of the antiestrogen Raloxifene and the omega-3 preparation Lovaza on breast density, a validated biomarker of breast cancer risk. We observed that daily administration of Lovaza (1,860 mg eicosapentaenoic [EPA] + 1,500 mg docosahexaenoic [DHA]) significantly reduced SCD-1 activity, an effect which was sustained for the two-year duration of the trial. Raloxifene, on the other hand, did not significantly alter SCD-1 activity in our subjects. SCD-1 activity was positively correlated with BMI (for SCD-16, r=0.45, p&lt;01; for SCD-18, r=0.23, p&lt;0.01) and paralleled changes in BMI in the same direction over the two years of the study. These findings support the role of this enzyme in the development of obesity. Importantly, decreasing levels of SCD-1 were found to be associated with a progressive reduction in breast density in obese women (BMI≥30) (for SCD-16; r=0.47, p&lt;0.01; for SCD-18; r=0.36, p&lt;0.05). No correlation between breast density and SCD-1 was observed in non-obese subjects (r=0.02 for SCD-16 and 0.04 for SCD-18). Our results suggest that BMI-related factors play an important role in the reduction of breast density by omega-3 fatty acids. They also indicate that SCD-1 may be a useful biomarker in future clinical trials testing the benefit of nutritional interventions in reducing obesity associated breast cancer risk.

Citation Format: Andrea Manni, John P. Richie, Susann E. Schetter, Ana Calcagnotto, Neil Trushin, Cesar Aliaga, Karam El-Bayoumy. Stearoyl-CoA desaturase-1, a novel target of omega-3 fatty acids for reducing breast cancer risk in obese postmenopausal women [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 236. doi:10.1158/1538-7445.AM2017-236

Influence of the lanthanide(iii) ion in {[Cu3Ln2(oda)6(H2O)6]·nH2O}n (LnIII: La, Gd, Yb) catalysts on the heterogeneous oxidation of olefins

{[Cu₃Ln₂(oda)₆(H₂O)₆]·nH₂O}_n (Ln^III: La, Gd, Yb; odaH₂: oxydiacetic acid) are reported as reusable heterogeneous catalysts in the oxidation of olefins.

Abstract 4454: Genome-wide analysis of DNA methylation induced by environmental carcinogen dibenzo[def,p]chrysene in ovarian tissues of mice

We and others have demonstrated that the administration of dibenzo[def,p]chrysene [also known as dibenzo[a,l]pyrene (DBP)], a representative example of the class of polycyclic aromatic hydrocarbon (PAH), by ip, oral gavage, or topical application onto the oral cavity induced tumors in multiple organ sites in mice; the ovary was the most susceptible tissue. We further demonstrated that the capacity of the target organs to metabolize DBP to active intermediates that can form DNA adducts may account for its tissue selective tumorigenicity. In addition, formation of DNA adducts by certain chemical carcinogens has been linked to aberrant DNA methylation, including the most extensively studied prototype PAH benzo[a]pyrene (B[a]P). The goal of this study is to examine whether alteration of DNA methylation occurs in the ovarian tissues of mice treated with DBP during the early stage of tumor development. In this study, we employed a previously established animal protocol in which the levels of DBP-DNA adducts as a function of time had been determined in the ovary following the oral administration of DBP (24 nmol, 3×/week for 5 weeks) or vehicle (DMSO) to female B6C3F1 mice (six weeks old, n = 3/group). DNA was isolated from ovary and subjected to enhanced reduced representation bisulfite sequencing (ERRBS) which is a single nucleotide resolution technique used to study DNA methylation in CpG sites and the surrounding regions. Briefly, DNA was digested by MspI followed by end repair, adenylation and adapter ligation with a modification of bead size selection to capture MspI fragments of 70-320 bp size. The resulting libraries were bisulfite-converted followed by PCR amplification and read by 1×50 bp on HiSeq 2500. Base calls of bisulfite treated sequencing reads were mapped to the mm9 mouse assembly and methylation calls were performed using Bismark v0.10.1 (Babraham Bioinformatcis, UK). The methylKit v0.9.2 R package was then used to calculate the differential methylation. Differentially methylated bases with q-value &lt; 0.01 and percent methylation difference &gt; 25% were extracted. Among 179 differentiated methylation sites (DMS) identified between DBP and vehicle-treated mice, 68 are hypermethylated and 111 are hypomethylated. About 25% of DMS are located in promoter or exon, 32% in intron and 44% in intergenic regions. DMS are located in genes including oocyte specific homeobox 2, transforming growth factor alpha, and tumor necrosis factor. Ingenuity Pathways analysis of the genes with altered methylation patterns identified top canonical pathways as growth hormone signaling, spermine biosynthesis, threonine degradation, trehalose degradation and L-serine degradation. Collectively, our previous results together with those presented here demonstrate that both genetic and epigenetic alterations may account for the carcinogenicity of DBP in the mouse ovary. Support: NIEHS R21ES020411 and NCI R01-CA173465.

Citation Format: Yuan-Wan Sun, Karam El-Bayoumy, Yuka Imamura Kawasawa, Anna Salzberg, Cesar Aliaga, Krishnegowda Gowdahalli, Shantu Amin, Kun-Ming Chen. Genome-wide analysis of DNA methylation induced by environmental carcinogen dibenzo[def,p]chrysene in ovarian tissues of mice. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4454.

Compostability assessment of nano-reinforced poly(lactic acid) films

Nanomaterials can provide plastics with great advantages on mechanical and active properties (i.e. release and capture of specific substances). Therefore, packaging is expected to become one of the leading applications for these substances by 2020. There are some applications already in the market. Nevertheless, there is still some areas under development. A key issue to be analyzed is the end-of-life of these materials once they become waste, and specifically when nanomaterials are used in biodegradable products. The present study evaluated the disintegration, biodegradability, and ecotoxicity of poly(lactic acid) films reinforced with the three following nanomaterials: (1) montmorillonite modified with an ammonium quaternary salt, (2) calcium carbonate and (3) silicon dioxide. Results on disintegration showed that films completely disintegrated into visually indistinguishable residues after 6-7weeks of incubation in composting environment. Moreover, no differences were observed in the evolution of the bioresidue with respect to color, aspect, and odor in comparison with the control. It was also observed that nanomaterials did not significantly reduce the level of biodegradability of PLA (p>0.05). In fact, biodegradation was higher, without finding significant differences (p>0.05), in all the nano-reinforced samples with respect to PLA after 130days in composting (9.4% in PLA+Nano-SiO2; 34.0% in PLA+Clay1; 48.0% in PLA+Nano-CaCO3). Finally, no significant differences (p>0.05) in ecotoxicity in plants were observed as a result of the incorporation of nanoparticles in the PLA matrix.

Influence of Obesity on Breast Density Reduction by Omega-3 Fatty Acids: Evidence from a Randomized Clinical Trial

Preclinical data indicate that omega-3 fatty acids (n-3FA) potentiate the chemopreventive effect of the antiestrogen (AE) tamoxifen against mammary carcinogenesis. The role of n-3FA in breast cancer prevention in humans is controversial. Preclinical and epidemiologic data suggest that n-3FA may be preferentially protective in obese subjects. To directly test the protective effect of n-3FA against breast cancer, we conducted a 2-year, open-label randomized clinical trial in 266 healthy postmenopausal women (50% normal weight, 30% overweight, 20% obese) with high breast density (BD; ≥25%) detected on their routine screening mammograms. Eligible women were randomized to one of the following five groups (i) no treatment, control; (ii) raloxifene 60 mg; (iii) raloxifene 30 mg; (iv) n-3FA lovaza 4 g; and (v) lovaza 4 g plus raloxifene 30 mg. The 2-year change in BD, a validated biomarker of breast cancer risk, was the primary endpoint of the study. In subset analysis, we tested the prespecified hypothesis that body mass index (BMI) influences the relationship between plasma n-3FA on BD. While none of the interventions affected BD in the intention-to-treat analysis, increase in plasma DHA was associated with a decrease in absolute breast density but only in participants with BMI >29. Our results suggest that obese women may preferentially experience breast cancer risk reduction from n-3FA administration.

Abstract 2955: The effects of the environmental carcinogen dibenzo[a,l]pyrene on genome-wide methylation and the impact of dietary black raspberry in mouse oral tissues

We had previously reported the carcinogenicity of dibenzo[a,l]pyrene (DB[a,l]P) in mouse oral cavity; we also found that that diets containing black raspberry (BRB) significantly reduced the levels of DNA adducts derived from DB[a,l]P in mouse oral tissues. Epigenetic alternations including DNA methylation have been shown to contribute to carcinogenesis induced by certain carcinogens. Literature data showed that dietary BRB can modulate DNA methylation at certain gene-specific promoters; however, the genome-wide methylation alterations by DB[a,l]P and the impact of BRB are not known. Therefore, to mimic the bioassay employed in our previous carcinogenicity study, B6C3F1 female mice (n = 3/group) were fed either control diet or diet containing BRB (5%) for 2 weeks prior to topical application of DMSO containing DB[a,l]P (24 nmol, 3 times a week for 5 weeks); animals treated with DMSO and control diet were used as a control group. DNA was isolated from oral tissues and subjected to enhanced reduced representation bisulfite sequencing analysis which is a single nucleotide resolution technique used to study DNA methylation in CpG sites and the surrounding regions. Briefly, DNA was digested by MspI followed by end repair, adenylation and adapter ligation with a modification of bead size selection to capture MspI fragments of 70-320 bp size. The resulting libraries were bisulfite-converted followed by PCR amplification and read by 1×50 bp on HiSeq 2500. Base calls of bisulfite treated sequencing reads were mapped to the mm9 mouse assembly and methylation calls were performed using Bismark v0.10.1. The methylKit R package was then used to calculate the differential methylation. Differentially methylated bases with q-value &lt; 0.01 and percent methylation difference &gt; 25% were extracted. Differential methylation of 30 genes was observed in DB[a,l]P compared with control; 12 genes were hypermethylated including β-catenin; hypomethylation of 18 genes was observed. Differential methylation of 960 genes was observed in mice treated with DB[a,l]P and fed BRB compared to DB[a,l]P. Ingenuity Pathways analysis was performed on each of the resulting gene sets in the three groups. Pathway analysis of the genes with altered methylation patterns identified canonical pathways for the involvement of cancer related network for genes involved in Wnt/β-catenin signaling, epithelial-mesenchymal transition (EMT), glycolysis and p53 signaling pathways in mice treated with DB[a,l]P. On the other hand, the canonical pathways identified in mice treated with DB[a,l]P and fed BRB are genes involved in glutamate receptor signaling, IGF-1 signaling, EMT, glycolysis, and protein citrullination. Using this quantitative sequencing-based approach, our work uncovers significant global DNA methylation alterations in mouse oral tissues by DB[a,l]P alone and together with BRB. Support: NCI R01-CA173465

Citation Format: Yuan-Wan Sun, Kun-Ming Chen, Yuka Imamura Kawasawa, Anna Salzberg, Cesar Aliaga, Krishnegowda Gowdahalli, Shantu Amin, Gary Stoner, Karam El-Bayoumy. The effects of the environmental carcinogen dibenzo[a,l]pyrene on genome-wide methylation and the impact of dietary black raspberry in mouse oral tissues. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2955. doi:10.1158/1538-7445.AM2015-2955

Abstract 2803: Oral administration of an acid stable liposomal formulation of docosahexaenoic acid (DHA) delivers DHA and its LOX-metabolites to the circulation and the breast tissue of sprague dawley rats

We have shown that dietary ratios of omega-3 to omega-6 fatty acids that significantly inhibited chemically-induced mammary carcinogenesis in the rat were in excess of 10:1 suggesting that a particular omega-3 fatty acid or its metabolite may account for the chemopreventive effects of such high ratios. Docosahexaenoic acid (DHA; 22:6 n-3), a component in fish oil, has been shown to inhibit mammary cancer-induced by chemical carcinogens (7,12-dimethylbenz-[a]-anthracene and N-methyl-N-nitrosourea) in the rat. The Western Diet in humans, with a ratio of 1:15 omega-3:omega-6 fatty acids, is not sufficient to provide the levels of DHA required for cancer prevention. Furthermore, mammals can't synthesize this fatty acid. Previously, a liposomal formulation for DHA for intravenous administration has been developed, but this route of administration is not appropriate for chemoprevention. Oral delivery for long term is the preferred approach. Therefore, we hypothesize that the oral delivery of a liposomal formulation of DHA which is resistant to oxidation and low gastric pH will enhance its bioavailability in the circulation and the breast tissues, and thus enhance the chemopreventive efficacy. We have developed for the first time an acid stable liposomal delivery system of DHA; average size determined by Dynamic Light Scattering is approximately 135nm, while that of the ghost formulation is approximately 150nm. This size is ideal for oral administration and can cross the enterocytes of the intestine. In a pilot study a single dose of liposomal DHA(1.54mg DHA/rat) was orally administered to female Sprague Dawley rats 21 days of age; rats were sacrificed after 24 hours by CO2 asphyxiation and their plasma and various organs including the breast tissue were harvested. The amount of DHA in the plasma and breast tissue was determined by gas chromatography flame ionization detection. Approximately 3.4% of the dose was determined to be in the plasma, while levels of DHA that reached the breast tissue were at least 5-fold higher than those measured in plasma. Using LC-MS/MS we detected DHA and its metabolites, 14-hydroxy DHA and 17-hydroxy DHA, catalyzed by LOX enzymes in rat plasma. In the breast tissue 4-hydroxy DHA, 14-hydroxy DHA, 17-hydroxy DHA, and 20-hydroxy DHA were detected. In summary, we report for the first time the detection of DHA and its LOX-metabolites in the circulation and breast tissue following the oral administration of liposomal DHA, suggesting that our nanotechnology-based approach is a promising strategy for breast cancer prevention. (Support: Institutional Funding)

Citation Format: Christine G. Skibinski, Arunangshu Das, Kun-Ming Chen, Neil Trushin, Bogdan Prokopczyk, Cesar Aliaga, Mark Kester, Andrea Manni, Karam El-Bayoumy. Oral administration of an acid stable liposomal formulation of docosahexaenoic acid (DHA) delivers DHA and its LOX-metabolites to the circulation and the breast tissue of sprague dawley rats. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2803. doi:10.1158/1538-7445.AM2015-2803

Fish Oil Enhances T Cell Function and Tumor Infiltration and Is Correlated With a Cancer Prevention Effect in HER-2/neu But Not PyMT Transgenic Mice

Few studies have explored the effects of omega-3 polyunsaturated fatty acid (n-3 PUFA) supplementation on immune modulation in murine models of mammary carcinogenesis. HER-2/neu and PyMT mice were randomized to 2 dietary interventions: AIN-93G-based diet with 1) 11% of diet (per gram weight) as corn oil (CO) or 2) 10% of diet as menhaden fish oil plus 1% of diet as corn oil (FO). FO significantly reduced the incidence and multiplicity of tumors (P < 0.001) in HER-2/neu, but not PyMT mice. FO-fed mice had significantly larger splenocyte counts than CO-fed mice in both the HER-2/neu and PyMT models; and in both models this was comprised of an increase in most cell types, including Gr-1(+)/CD11b(+) cells. T cells from FO-fed HER-2/neu mice produced significantly more interleukin-2 (P = 0.004) and interferon-γ (P = 0.012) in response to in vitro stimulation with anti-CD3 (0.5 µg/ml). Lastly, FO-fed HER-2/neu mice had significantly more tumor immune infiltrates than CO-fed mice, including NK1.1(+), F4/80(+), and Gr-1(+)/CD11b(+) cells (P ≤ 0.05). Greater Th1 cytokine production and significantly more tumor immune infiltrates in FO-fed Her2/neu mice may account for the cancer prevention effect of fish oil in this model.

Tissue Distribution, Excretion and Pharmacokinetics of the Environmental Pollutant Dibenzo[def,p]chrysene in Mice

Dibenzo[def,p]chrysene (DBP), a representative example of the class of polycyclic aromatic hydrocarbon (PAH), is known to induce tumors in multiple organ sites including the ovary, lung, mammary glands, and oral cavity in rodents. The goal of this study was to test the hypothesis that the levels of DBP and its metabolites that reach and retain the levels for an extended time in the target organs as well as the capacity of these organs to metabolize this carcinogen to active metabolites that can damage DNA may account for its tissue selective tumorigenicity. Therefore, we used the radiolabeled [(3)H] DBP to accurately assess the tissue distribution, excretion, and pharmacokinetics of this carcinogen. We also compared the levels of DBPDE-DNA adducts in a select target organ (ovary) and nontarget organs (kidney and liver) in mice treated orally with DBP. Our results showed that after 1 week, 91.40 ± 7.23% of the radioactivity was recovered in the feces; the corresponding value excreted in the urine was less than 2% after 1 week. After 24 h, the stomach had the highest radioactivity followed by the intestine and the liver; however, after 1 week, levels of the radioactivity in these organs were the lowest among tissues examined including the ovary and liver; the pharmacokinetic analysis of DBP was conducted using a one compartment open model. The level of (-)-anti-trans-DBPDE-dA in the ovaries (8.91 ± 0.08 adducts/10(7) dA) was significantly higher (p < 0.01) than the levels of adducts in kidneys (0.69 ± 0.09 adducts/10(7) dA) and livers (0.63 ± 0.11 adducts/10(7) dA). Collectively, the results of the tissue distribution and pharmacokinetic analysis may not fully support our hypothesis, but the capacity of the target organs vs nontarget organs to metabolize DBP to active intermediates that can damage DNA may account for its tissue selective tumorigenicity.

The influence of printed electronics on the recyclability of paper: a case study for smart envelopes in courier and postal services

The aim of this paper is to analyse the effects of the presence of printed electronics on the paper waste streams and specifically on paper recyclability. The analysis is based on a case study focussed on envelopes for postal and courier services provided with these intelligent systems. The smart printed envelope of the study includes a combination of both conventional (thin flexible batteries and resistors) and printed electronic components (conductive track layout based on nanosilver ink). For this purpose, a comparison between envelopes with and without these components (batteries, resistors and conductive track layouts) was carried out through pilot scale paper recycling tests. The generation of rejects during the recycling process as well as the final quality of the recycled paper (mechanical and optical properties) were tested and quantitatively evaluated. The results show that resistors are retained during the screening process in the sieves and consequently they cannot end up in the final screened pulp. Therefore, mechanical and optical properties of the recycled paper are not affected. Nevertheless, inks from the conductive track layouts and batteries were partially dissolved in the process water. These substances were not totally retained in the sieving systems resulting in slight changes in the optical properties of the final recycled paper (variations are 7.2-7.5% in brightness, 8.5-10.7% in whiteness, 1.2-2.2% in L(∗) values, 3.3-3.5% in opacity and 16.1-27% in yellowness). These variations are not in ranges able to cause problems in current paper recycling processes and restrict the use of recycled paper in current applications. Moreover, real impacts on industrial recycling are expected to be even significantly lower since the proportion of paper product with printed circuits in the current paper waste streams are much lower than the ones tested in this work. However, it should be underlined the fact that this situation may change over the next years due to the future developments in printed electronics and the gradual penetration of these types of devices in the market.

Recyclability assessment of nano-reinforced plastic packaging

Packaging is expected to become the leading application for nano-composites by 2020 due to the great advantages on mechanical and active properties achieved with these substances. As novel materials, and although there are some current applications in the market, there is still unknown areas under development. One key issue to be addressed is to know more about the implications of the nano-composite packaging materials once they become waste. The present study evaluates the extrusion process of four nanomaterials (Layered silicate modified nanoclay (Nanoclay1), Calcium Carbonate (CaCO3), Silver (Ag) and Zinc Oxide (ZnO) as part of different virgin polymer matrices of polyethylene (PE), Polypropylene (PP) and Polyethyleneterephtalate (PET). Thus, the following film plastic materials: (PE-Nanoclay1, PE-CaCO3, PP-Ag, PET-ZnO, PET-Ag, PET-Nanoclay1) have been processed considering different recycling scenarios. Results on recyclability show that for PE and PP, in general terms and except for some minor variations in yellowness index, tensile modulus, tensile strength and tear strength (PE with Nanoclay1, PP with Ag), the introduction of nanomaterial in the recycling streams for plastic films does not affect the final recycled plastic material in terms of mechanical properties and material quality compared to conventional recycled plastic. Regarding PET, results show that the increasing addition of nanomaterial into the recycled PET matrix (especially PET-Ag) could influence important properties of the recycled material, due to a slight degradation of the polymer, such as increasing pinholes, degradation fumes and elongation at break. Moreover, it should be noted that colour deviations were visible in most of the samples (PE, PP and PET) in levels higher than 0.3 units (limit perceivable by the human eye). The acceptance of these changes in the properties of recycled PE, PP and PET will depend on the specific applications considered (e.g. packaging applications are more strict in material quality that urban furniture or construction products).

Abstract 230: The inhibitory effects of an anthocyanin enriched fraction of black raspberry (BRB), protocatechuic acid and ferulic acid on DB[a,l]P-induced DNA adduct formation in mouse oral tissues

Oral squamous cell carcinoma (OSCC) is the most common cancer of the head and neck region; in the USA, over 45,000 cases and about 11,000 deaths from the disease occur annually. Progress in the prevention and control of OSCC has been hampered by the lack of appropriate animal models that would reflect human exposure. Tobacco smoking is considered a major etiological factor in the development of oral cancer. Previous studies have demonstrated the ability of diets containing 5-10% freeze-dried black raspberry (BRB) powder to inhibit the development of chemically-induced cancers in multiple organ sites in rodents including 7,12-dimethylbenz(a)anthracene (DMBA) induced squamous cell carcinomas (SCC) in the hamster cheek pouch. However, DMBA is not present in the environment and the hamster cheek pouch model may not be applicable to humans. We had previously reported the carcinogenicity of dibenzo[a,l]pyrene (DB[a,l]P), an environmental pollutant and a tobacco smoke component, in mouse oral cavity. Recently, we demonstrated that administration of BRB at 5% in the diet can significantly reduce DNA adducts resulted from the administration of DB[a,l]P. It has also been shown that anthocyanins are the most abundant compounds in BRBs that can account for much of their antioxidant activity. In the current study, under identical conditions we compare the inhibitory effects of an anthocyanin enriched fraction extracted from black raspberry (BRBE), protocatechuic acid (PA, a major metabolite of anthocyanins) or ferulic acid (FA, a major phenolic acid in raspberries shown to reduce oral carcinogenesis) with BRB on DNA adducts induced by DB[a,l]P in mouse oral cavity. Levels of DB[a,l]PDE-DNA adducts were quantified by a LC-MS/MS method. We demonstrated that the administration of BRBE (1.6 %), protocatechuic acid (0.2%) or ferulic acid (0.05%) in the diet, starting 2 weeks before DB[a,l]P (24 nmol, 3 times a week for 5 weeks) significantly resulted in 29.6%, 23.0% or 25.3% reduction of the level of (-)-anti-trans-DB[a,l]PDE-dA in murine oral tissues, respectively, compared to a 19.2% reduction of BRB. Our results clearly showed that the anthocyanin components of BRB and its metabolite, PA, are responsible for the inhibitory effects of BRB on the DB[a,l]P- induced DNA adducts formation; in addition, BRB and its related components can inhibit the metabolic activation of DB[a,l]P, and may prevent the subsequent mutagenesis and carcinogenesis resulting from exposure to DB[a,l]P. Supported by NIH grant #CA173465.

Citation Format: Kun-Ming Chen, Shangmin Zhang, Yuan-Wan Sun, Cesar Aliaga, Krishnegowda Gowdahalli, Shantu Amin, Gary Stoner, Karam El-Bayoumy. The inhibitory effects of an anthocyanin enriched fraction of black raspberry (BRB), protocatechuic acid and ferulic acid on DB[a,l]P-induced DNA adduct formation in mouse oral tissues. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 230. doi:10.1158/1538-7445.AM2014-230

Abstract 2139: Pre-clinical chemopreventive efficacy of a novel hybrid p-XSC-aspirin compound in a NNK-induced A/J mouse lung cancer model

Despite the identification of several preventive agents and strategies, prevention of lung cancer, especially in smokers who are at high risk, is still largely unattained. 1,4-Phenylenebis(methylene)selenocyanate (p-XSC) has been shown to inhibit tobacco carcinogen NNK induced lung cancer development in several animal models. It metabolizes through the formation of active bis-selenol (p-XSeH) along with the release of poisonous hydrogen cyanide (HCN). Nevertheless, the HCN released upon metabolism of p-XSC to form active metabolite p-XSeH, pose a serious challenge its clinical use in a chemopreventive set up where a continuous intake is required for healthy individuals over a longer period of time. Recently, we developed a hybrid agent, p-XS-Asp, linking p-XSe- to commonly used non-steroidal anti-inflammatory drug, aspirin (Asp), which has been shown to be preventive of lung, and colorectal cancer. We hypothesized that p-XS-Asp would cleave in vivo to release the active p-XSeH, not releasing undesired HCN but the aspirin, thus making the compound less toxic and more potent than p-XSC or aspirin alone. Our studies have shown p-XS-Asp to be orally bioavailable and a highly effective lung cancer chemopreventive agent both in vitro and in animal studies. Elemental selenium (Se) analysis of plasma, lung, and liver tissue in orally fed mice showed that the level of Se significantly higher for p-XS-Asp than p-XSC, denoting a better bioavailability profile for p-XS-Asp. Dietary p-XS-Asp inhibited both O-6 methyl guanine and pyridoxobutyl (pob) DNA adducts, in lung and liver of A/J mice, more effectively than p-XSC. Particularly, in the lung, the inhibition of O-6 methyl guanine adducts, which are critical for A/J mouse lung tumor development, were more than 2 times higher than p-XSC. In a NNK-induced lung cancer A/J mouse model, p-XS-Asp at doses of 15 ppm and 7.5 ppm Se, showed a significantly marked decrease in percentage of lung tumor incidence of 50% and 87%, as compared to p-XSC (79% and 100%), respectively; NNK-control showed an 100% tumor incidence. In addition, the multiplicity for p-XS-Asp was 0.87 and 1.93 tumors/mouse as compared with NNK-control (11.53 tumors/mouse) and p-XSC (1.66 and 4.10 tumors/mouse, respectively) at the two doses tested. Notably, blood and tissue analyses showed no signs of systemic toxicity for the p-XS-Asp fed group. In conclusion, p-XS-Asp, is less toxic and more effective chemopreventive agent than p-XSC and is a promising candidate to future clinical evaluation.

Citation Format: Daniel Plano, Cesar Aliaga, Manoj K. Pandey, Arunangshu Das, Timothy K. Cooper, Shantu Amin, Arun K. Sharma. Pre-clinical chemopreventive efficacy of a novel hybrid p-XSC-aspirin compound in a NNK-induced A/J mouse lung cancer model. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2139. doi:10.1158/1538-7445.AM2014-2139

Simultaneous detection of deoxyadenosine and deoxyguanosine adducts in the tongue and other oral tissues of mice treated with Dibenzo[a,l]pyrene

We were the first to demonstrate that direct application of the environmental pollutant and tobacco smoke constituent dibenzo[a,l]pyrene (DB[a,l]P) into the oral cavity of mice induced squamous cell carcinoma (SCC) in oral tissues but not in the tongue; however, the mechanisms that can account for the varied carcinogenicity remain to be determined. Furthermore, we also showed that not only dA adducts, but also dG adducts can account for the mutagenic activity of DB[a,l]P in the oral tissues in vivo. In this study, we initially focused on DB[a,l]P-induced genotoxic effects in both oral and tongue tissues. Therefore, to fully assess the contribution of these DNA adducts in the initiation stage of carcinogenesis induced by DB[a,l]P, an LC-MS/MS method to simultaneously detect and quantify DB[a,l]PDE-dG and -dA adducts was developed. Mice were orally administered with DB[a,l]P (24 nmole, 3 times per week for 5 weeks) or its fjord region diol epoxide, (±)-anti-11,12-dihydroxy-13,14-epoxy-11,12,13,14-tetrahydrodibenzo[a,l]pyrene (DB[a,l]PDE, 12 nmole, single application); animals were sacrificed at 2, 7, 14, and 28 days after the last dose of carcinogen administration. Oral and tongue tissues were obtained and DNA were isolated followed by enzymatic hydrolysis. Following the development of an isotope dilution LC-MS/MS method, we successfully detected (−)-anti-cis- and (−)-anti-trans-DB[a,l]PDE-N²-dG, as well as (−)-anti-cis- and (−)-anti-trans-DB[a,l]PDE-N⁶-dA in oral and tongue tissues of mice treated with DB[a,l]P. Levels of (−)-anti-trans-DB[a,l]PDE-N⁶-dA were ≥2 folds higher than (−)-anti-cis-DB[a,l]PDE-N⁶-dA adduct and those of dG adducts in the oral tissues and tongue at all time points selected after the cessation of DB[a,l]P treatment. Levels of dG adducts were comparable in both tissues. Collectively, our results support that DB[a,l]P is predominantly metabolized to (−)-anti-DB[a,l]PDE, and the levels and persistence of (−)-anti-trans-DB[a,l]PDE-N⁶-dA may, in part, explain the carcinogenicity of DB[a,l]P in the oral tissues but not in the tongue.

Influence of omega-3 fatty acids on Tamoxifen-induced suppression of rat mammary carcinogenesis

We report here a detailed time course study of the individual and combined chemopreventive effects of Tamoxifen (Tam) and a high fish oil (FO) diet on multiple histologic parameters of mammary carcinogenesis. Groups of female Sprague-Dawley rats were injected ip with 1-methyl-1-nitrosourea at 50 days of age and assigned to either a control diet (20% corn oil [CO]) or a FO-rich diet (10% FO + 10% CO) in the presence and absence of Tam in the diet (0.6 ppm). Rats were sacrificed at weeks 4 (before palpable tumors), 8 and 12 (when ∼90% of control rats had palpable tumors). Our results demonstrate a major effect of Tam in inhibiting the development of early preneoplastic lesions. FO, while having a marginal protective effect of it own, enhanced the antitumor action of Tam on all histologic parameters of carcinogenesis, although the effects of the combination were not statistically different from those of Tam alone. The combination of FO and Tam was the only intervention that induced regression of established preneoplastic lesions. We also found that in contrast to plasma, only target tissue n-3 fatty acids (FAs) levels correlated with select tissue biomarkers of carcinogenesis whose expression was altered in a manner predictive of a protective effect. Our results demonstrating the potentially superior chemopreventive efficacy of Tam and n-3FA have important translational implications. Our data also emphasize the importance of local factors in affecting target tissue levels and biologic effects of n-3FA.

Mechanisms of oral carcinogenesis induced by dibenzo[a,l]pyrene: an environmental pollutant and a tobacco smoke constituent

We previously reported that dibenzo[a,l]pyrene (DB[a,l]P), the most potent known environmental carcinogen among polycyclic aromatic hydrocarbons (PAH) congeners, is carcinogenic in the oral tissues of mice. We have now developed a new mouse model which employs the oral application of the fjord region diol epoxide, (±)-anti-11,12-dihydroxy-13,14-epoxy-11,12,13,14-tetrahydrodibenzo[a,l]pyrene (DB[a,l]PDE), a metabolite of the tobacco smoke constituent DB[a,l]P, and we show its specific induction of oral squamous cell carcinoma (OSCC) in both tongue and other oral tissues. Groups of B6C3F1 mice (20/group) received 6 or 3 nmol of (±)-anti-DB[a,l]PDE administered into the oral cavity; 3 times per week for 38 weeks. Additional groups received the vehicle alone or were left untreated. Mice were sacrificed 42 weeks after the first carcinogen administration. The high dose induced 74 and 100% OSCC in the tongue and other oral tissues, respectively; the corresponding values at the lower dose were 45 and 89%. Using immunohistochemistry, we showed that DB[a,l]PDE resulted in overexpression of p53 and COX-2 proteins in malignant tissues when compared to normal oral tissues and tongues. Consistent with the carcinogenicity, we demonstrated powerful mutagenicity in cII gene in B6C3F1 (Big Blue) mouse tongue. The mutational profile in lacI reporter gene is similar to those detected in human head and neck cancer, and p53 mutations were observed in mouse oral tumor tissues. Taken together, we conclude that the formation of diol epoxides plays a major role among the mechanisms by which DB[a,l]P exerts its oral mutagenicity and tumorigenicity.

Abstract 3691: Fish oil increases immune cell infiltration of tumors and reduces the incidence of mammary carcinogenesis in Her2neu mice

The role of omega-3 fatty acids (n-3 FA) in breast cancer prevention is widely studied, however much controversy exists in the field. In numerous preclinical models including the Her2neu transgenic model, consumption of n-3 FA provides a protective effect in mammary carcinogenesis. However, to date few studies have explored the effect of n-3 FA supplementation on immune modulation and if such changes contribute to the cancer prevention effects of n-3 FA. The goal of the current study was to explore the role of fish oil, as the source of n-3 FA, on immune markers and tumor yield in a Her2/neu transgenic model. Her2neu mice were randomized to two dietary interventions: AIN-93G-based diet with 1) 11% of diet (per gram weight) as corn oil (CO) or 2) 10% of diet as menhaden fish oil plus 1% of diet as corn oil (FO) (n=30/gr). FO significantly reduced the incidence and multiplicity of tumors in Her2neu mice (P&lt;0.05). A cohort of mice (n=10/gr) were sacrificed at 4 months just prior to developing focal malignant mammary lesions. No differences in the size or cellularity of the spleen were observed; however flow cytometric analysis revealed that FO mice had a significantly greater number of several cell types (CD3+ T cells, NK1.1+ NK cells, CD11c+ DCs) and a greater number of splenic Gr1+/CD11b+ cells than CO mice (14.3 ± 2.6 X 106 vs. 3.6 ± 1.8 X106, respectively; P&lt;0.05). Gr1+/CD11b+ cells are markers that define myeloid derived suppressor cells (MDSCs) which increase with tumor growth and have immunosuppressive function. However, recent reports have documented a role for MDSCs in immune modulation and the emergence of MDSCs subtypes that have different functional roles. A second cohort of mice (n=10/gr) were sacrificed at 12-15 months when ∼80% of control mice have been shown to develop mammary tumors. FO mice had significantly larger spleens with greater splenocyte counts than CO mice (270.3 ± 69.3 X106 and 198.9 ± 38.7 X 106, respectively; P&lt;0.05), which was comprised of a greater number of most cells types (CD3+, F480+, CD11c+, and NK1.1+ cells) including splenic Gr-1+/CD11b+ MDSCs (13.1 ± 4.6 X 106 and 3.4 ± 1.8 X106, respectively P&lt;0.05). Despite the presence of more Gr1+/CD11b+ cells in the spleens of FO mice, T cells from these mice had significantly greater IL-2 and IFN- γ release in response to in vitro stimulation with anti-CD3 (0.5 μg/ml), suggesting that Gr1+/CD11b+ cells may not be inhibiting T cell function in FO mice. Lastly, FO mice had a greater number of tumor infiltrating immune cells than CO mice, including CD3+, NK1.1+, F480+ and Gr1+/CD11b+ cells (P&lt;0.05). The presence of a greater number of tumor infiltrating immune cells correlates with reduced tumor burden in the FO mice. These data suggest unique immune modulatory effects of FO in tumor-bearing animals. This work is supported by the Susan G. Komen Foundation, Komen Grant KG0681632.

Citation Format: William J. Turbitt, Shawntawnee D. Collins, Haifang Xu, Sharlene Washington, Cesar Aliaga, Karam El-Bayoumy, Andrea Manni, Connie J. Rogers. Fish oil increases immune cell infiltration of tumors and reduces the incidence of mammary carcinogenesis in Her2neu mice. [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 3691. doi:10.1158/1538-7445.AM2013-3691

Abstract 3657: Identification of active metabolites of docosohexaenoic acid (DHA): A first step towards unraveling the fish oil/breast cancer conundrum

The role of fish oil (FO) rich in omega-3 fatty acid (n-3FA) in breast cancer prevention remains controversial. Based on our data showing that a high n-3:n-6 ratio (≥10) is necessary to inhibit N-methyl-N-nitrosourea (MNU)-induced rat mammary carcinogenesis (Zhu Z, et al., Cancer Prev Res 4(10):1675, 2011), we hypothesize that this chemopreventive effect of FO may be due to one of its components (e.g., Docosohexaenoic acid, DHA, 22:6) and/or to the production of Active DHA Metabolites (ADM) which may be present in small and variable amounts in FO preparations used in different preclinical studies. To test this hypothesis, we used LC-TOF/MS followed by tandem mass spectroscopy to quantify ADM in the plasma and mammary tumors of rats fed a 20% CO diet and administered either saline or one of two doses of DHA (1.5 ml/kg and 3.0 ml/kg) by gavage twice a week for 8 weeks following ip MNU injection (50 mg/kg) at 21 days of age. The lower dose of DHA was also given in combination with Tamoxifen (Tam) (0.6 ppm) to test the hypothesis that n-3FA may inhibit the development of antiestrogen resistant tumors. We observed that both doses of DHA similarly inhibited mammary carcinogenesis and that the combination of Tam and DHA was more effective than each of the individual agents. DHA administration caused a significant dose-dependent increase in the plasma levels of several ADM including 4-OH-DHA, 7-OH-DHA, 14-OH-DHA, and 17-OH-DHA. The levels of these ADM were ∼10-fold higher in the tumors of the rats given DHA compared to control, irrespective of the dose of DHA administered. The most abundant ADM in the tumors was 14-OH-DHA followed in order by 17-OH-DHA, 4-OH-DHA, and 7-OH-DHA. In order to compare the biological activity of these ADM to that of the parent compound, we tested in vitro their ability to induce PPARγ activation using a PPARγ reporter assay since PPARγ activation is considered to be a potential mechanism by which n-3FA exert their antitumor action. We observed that every ADM was more effective than DHA by at least 2-fold in inducing PPARγ activity with the following order of magnitude of the effect, 7-OH-DHA &gt; 14-OH-DHA &gt; 4-OH-DHA &gt; 17-OH-DHA. In summary, our studies identify for the first time ADM which may be responsible for the chemopreventive effect of FO. This finding may have major translational significance since compounds with well-defined chemical structure given at optimal concentrations are likely to be more effective chemopreventive agents than FO which contains an inconsistent mixture of FA with varying biological activity. In addition, since DHA inhibits carcinogenesis in Tam-treated rats, these ADM may complement the effect of Tam by inhibiting the development of hormone independent tumors.

This work is supported by grant KG081632 from Susan G. Komen for the Cure.

Citation Format: Andrea Manni, John P. Richie, Neil Trushin, Bogdan Prokopczyk, A Patterson, John P. Vanden Heuvel, Sharlene Washington, Haifang Xu, Cesar Aliaga, Arunangshu Das, Krishne Gowda, Shantu Amin, Jason Liao, Henry Thompson, Karam El-Bayoumy. Identification of active metabolites of docosohexaenoic acid (DHA): A first step towards unraveling the fish oil/breast cancer conundrum. [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 3657. doi:10.1158/1538-7445.AM2013-3657

Fish oil alters tamoxifen-modulated expression of mRNAs that encode genes related to differentiation, proliferation, metastasis, and immune response in rat mammary tumors

We have previously shown that a fish oil (FO)-rich diet increased the chemopreventive efficacy of tamoxifen (Tam) against N-methyl-N-nitrosourea (MNU)-induced rat mammary carcinogenesis. Herein, we provide evidence that Tam treatment modifies gene expression of mammary tumors depending upon the type of dietary fat fed to the animals. Rats initiated with MNU and treated with Tam were fed a diet rich in corn oil or FO. After 8 wk, cribriform tumors were collected and gene expression analysis was performed. Increased RNA expression of genes such as SerpinB10, Wisp2, and Apod in tumors from FO-treated rats is indicative of highly differentiated tumors. Decreased expression of H19 and Igf2 mRNA in Tam-treated groups, and Gamma Synuclein mRNA in the FO + Tam group may be related to tumor growth impairment and lower metastatic capacity. Change in the expression of genes associated with immunity in animals in the FO + Tam group may suggest a shift in the immune response. These data show that, although Tam modulates the expression of genes leading to tumor growth impairment, further modulations of genes are influenced by FO. FO modulation of Tam changes in gene expression accounts for its enhancing chemopreventive effect against MNU-induced mammary carcinogenesis. Supplemental materials are available for this article. Go to the publisher's online edition of Nutrition and Cancer to view the supplemental file.

Mutagenesis and carcinogenesis induced by dibenzo[a,l]pyrene in the mouse oral cavity: a potential new model for oral cancer

Cancer of the oral cavity is a serious disease, affecting about 30,000 individuals in US annually. There are several animal models of oral cancer, but each has certain disadvantages. As a new model, we investigated whether topical application of the tobacco smoke carcinogen, dibenzo[a,l]pyrene (DB[a,l]P) is mutagenic and carcinogenic in the oral cavity of the B6C3F1 lacI and B6C3F1 mouse, respectively. B6C3F1 lacI mice received DB[a,l]P (0, 3, 6, 12 nmol) 3× per week. B6C3F1 mice received the same doses and also 24 nmol. At 38 weeks mutagenesis was measured in oral tissues in lacI mice. For the high dose group, the mutant fraction (MF) in upper mucosa and tongue increased about twofold relative to that in vehicle-alone. The increases were statistically significant. The mutational profile in the DB[a,l]P-induced mutants was compared with that induced by benzo[a]pyrene (BaP) in oral tissue. BaP is mutagenic in many tissues when administered by gavage. The mutational profile for DB[a,l]P was more similar to that reported for p53 mutations in head and neck cancers than was that of BaP. At 47 weeks, oral squamous cell carcinomas (OSCC) were found in 31% of the high-dose B6C3F1 group. Elevations of p53 and COX-2 protein were observed in tumor and dysplastic tissue. As DB[a,l]P induces mutations and tumors in the oral cavity, and has a mutational profile in oral tissue similar to that found in p53 in human OSCC, the treatment protocol described here may represent a new and relevant model for cancer of the oral cavity.

Elevated hepatic iron activates NF-E2-related factor 2-regulated pathway in a dietary iron overload mouse model

Hepatic iron overload has been associated classically with the genetic disorder hereditary hemochromatosis. More recently, it has become apparent that mild-to-moderate degrees of elevated hepatic iron stores observed in other liver diseases also have clinical relevance. The goal was to use a mouse model of dietary hepatic iron overload and isobaric tag for relative and absolute quantitation proteomics to identify, at a global level, differentially expressed proteins in livers from mice fed a control or 3,5,5-trimethyl-hexanoyl-ferrocene (TMHF) supplemented diet for 4 weeks. The expression of 74 proteins was altered by ≥ ±1.5-fold, showing that the effects of iron on the liver proteome were extensive. The top canonical pathway altered by TMHF treatment was the NF-E2-related factor 2 (NRF2-)-mediated oxidative stress response. Because of the long-standing association of elevated hepatic iron with oxidative stress, the remainder of the study was focused on NRF2. TMHF treatment upregulated 25 phase I/II and antioxidant proteins previously categorized as NRF2 target gene products. Immunoblot analyses showed that TMHF treatment increased the levels of glutathione S-transferase (GST) M1, GSTM4, glutamate-cysteine ligase (GCL) catalytic subunit, GCL modifier subunit, glutathione synthetase, glutathione reductase, heme oxygenase 1, epoxide hydrolase 1, and NAD(P)H dehydrogenase quinone 1. Immunofluorescence, carried out to determine the cellular localization of NRF2, showed that NRF2 was detected in the nucleus of hepatocytes from TMHF-treated mice and not from control mice. We conclude that elevated hepatic iron in a mouse model activates NRF2, a key regulator of the cellular response to oxidative stress.

Induction of lung glutathione and glutamylcysteine ligase by 1,4-phenylenebis(methylene)selenocyanate and its glutathione conjugate: role of nuclear factor-erythroid 2-related factor 2

The synthetic organoselenium agent 1,4-phenylenebis(methylene)selenocyanate (p-XSC) and its glutathione (GSH) conjugate (p-XSeSG) are potent chemopreventive agents in several preclinical models. p-XSC is also an effective inducer of GSH in mouse lung. Our objectives were to test the hypothesis that GSH induction by p-XSC occurs through upregulation of the rate-limiting GSH biosynthetic enzyme glutamylcysteine ligase (GCL), through activation of antioxidant response elements (AREs) in GCL genes via activation of nuclear factor-erythroid 2-related factor 2 (Nrf2). p-XSC feeding (10 ppm Se) increased GSH (230%) and upregulated the catalytic subunit of GCL (GCLc) (55%), extracellular-related kinase (220%), and nuclear Nrf2 (610%) in lung but not liver after 14 days in the rat (P<0.05). Similarly, p-XSeSG feeding (10 ppm) induced lung GCLc (88%) and GSH (200%) (P<0.05), whereas the naturally occurring selenomethionine had no effect. Both p-XSC and p-XSeSG activated a luciferase reporter in HepG2 ARE-reporter cells up to threefold for p-XSC and greater than or equal to fivefold for p-XSeSG. Luciferase activation by p-XSeSG was associated with enhanced levels of GSH, GCLc, and nuclear Nrf2, which were significantly reduced by co-incubation with short interfering RNA targeting Nrf2. The dependence of GCL induction on Nrf2 was confirmed in Nrf2-deficient mouse embryonic fibroblasts, in which p-XSeSG induced GCL subunits in wild-type but not in Nrf2-deficient cells (P<0.05). These results indicate that p-XSC may act through the Nrf2 pathway in vivo and that p-XSeSG is the putative metabolite responsible for such activation, thus offering p-XSeSG as a less toxic, yet highly efficacious, inducer of GSH.

Abstract 5469: Detection of deoxyguanosine adducts in the oral tissues of mice treated with the environmental carcinogen dibenzo[a, l]pyrene by LC-MS/MS

Oral cancer is the major form of head and neck squamous cell carcinoma, which is the fifth most common cancer worldwide. Tobacco smoking is one of the leading causes of oral cancer. Dibenzo[a, l]pyrene (DB[a, l]P) is the most potent carcinogenic polycyclic aromatic hydrocarbon found in tobacco smoke. Our laboratory had developed a mouse model of oral cancer induced by DB[a, l]P. Our working hypothesis is that the stereochemical course of DB[a, l]P metabolism, the conformations of the DNA adducts formed and their removal by mammalian DNA repair enzymes, and their mutagenic properties if not removed in an error-free manner, all play critical roles during the induction of oral carcinogenesis. As an initial study to test our hypothesis, we have previously developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to detect and quantify DB[a, l]PDE-N6-dA adducts in oral tissues of mice treated with DB[a, l]P. We have shown that (-)-anti-cis- and (-)-anti-trans-DB[a, l]PDE-N6-dA adducts were detected from oral tissues of mice treated with DB[a, l]P. In the present study, to further test our hypothesis, we report on the development of a LC-MS/MS method to detect DB[a, l]PDE-N2-dG adducts in vivo. (±)-anti-[15N5]-DB[a, l]PDE-N2-dG adducts were synthesized as internal standards. The stereochemistry of adducts were characterized. Following the addition of internal standards, DNA isolated from oral tissues of mice treated with DB[a, l]P or DB[a, l]PDE was enzymatically hydrolyzed to 2′-deoxyribonucleosides and partially purified by solid-phase extraction. The LC-MS/MS analysis was carried out by monitoring transitions m/z 620 [M+H]+→ m/z 504 [(M+H)+−2′-deoxyribose] for DB[a, l]PDE-N2-dG adducts and m/z 625α m/z 509 for the internal standards. We have detected two N2-dG adducts from oral tissues of mice treated with DB[a, l]P, and four N2-dG adducts from oral tissues of mice treated with (±)-anti-DB[a, l]PDE. Collectively, the in vivo detection of dA and dG adducts indicated that DB[a, l]P is predominantly metabolized to (-)-anti-DB[a, l]PDE in oral tissues of mice. This sensitive LC-MS/MS method, is capable of simultaneously detecting both dA and dG adducts derived from anti-DB[a, l]PDE. Our results indicated that levels of dA adducts are significantly higher than dG adducts in vivo, which are consistent with those reported in literature in organs other than oral tissues, demonstrating that fjord region diol epoxide of DB[a, l]P predominantly form dA adducts than dG adducts.

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 5469. doi:1538-7445.AM2012-5469

Abstract 5470: Genotoxic effect and epigenetic alterations induced by the environmental carcinogen dibenzo[a, l]pyrene in oral tissues of mice

Oral cancer is the major form of head and neck squamous cell carcinoma, which is the fifth most common cancer worldwide. Tobacco smoking is one of the leading causes of oral cancer. Dibenzo[a, l]pyrene (DB[a, l]P) is the most potent carcinogenic polycyclic aromatic hydrocarbon found in tobacco smoke. Recently we developed a novel mouse model of oral cancer induced by DB[a, l]P; we also showed the remarkable carcinogenicity and specificity of the fjord region diol epoxide metabolite, (±)-anti-11,12-dihydroxy-13,14-epoxy-11,12,13,14-tetrahydrodibenzo[a, l]pyrene (DB[a, l]PDE). Using immunohistochemistry (IHC), we have shown over-expression of p53 protein in mice oral squamous cell carcinoma and dysplastic tissues induced by DB[a, l]P and DB[a, l]PDE. Current understanding of molecular pathogenesis of oral cancer in humans suggests that both genetic and epigenetic alterations are crucial and complement each other. Our hypothesis is that both genetic and epigenetic alterations induced by DB[a, l]P can contribute to the development of oral cancer. P53 protein overexpression detected by IHC may result from p53 gene mutation or exposure to genotoxic stress. To determine whether p53 over-expression is in part due to p53 mutations, Exons 5 to 8 of p53 from 5 tumor tissues were analyzed by polymerase chain reaction single-strand conformation polymorphisms (PCR-SSCP) and direct sequencing. G to T transversion was detected in Exon 5, leading to mutation of codon 155 Arg to Leu; A to T transversion was detected in Exon 7, resulting in mutation of codon 232 Lys to stop codon. To test the epigenetic effect of DB[a, l]P, methylation specific PCR and bisulfate sequencing were used to detect methylation alteration of p16 and RAR-β promoters. Promoter hypermethylation of both p16 and RAR-β were detected in tumors induced by DB[a, l]PDE; also in oral tissues of mice treated with DB[a, l]P (24nmol, 3 times per week, for 5 weeks, sacrificed at 48 h, 1, 2 and 4 weeks after last dose). These results suggested that genotoxic DNA adducts derived from DB[a, l]P can induce mutations in critical genes, such as tumor suppressor gene p53; this environmental carcinogen also can induce p16 and RAR-β promoter hypermethylation at early stage, which can contribute to the promotion and progression of oral carcinogenesis.

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 5470. doi:1538-7445.AM2012-5470

Induction of ovarian cancer and DNA adducts by Dibenzo[a,l]pyrene in the mouse

Tobacco smoking is an etiological factor of ovarian cacner; however, the mechanisms remain largely undefined. Therefore, as an initial investigation, we examined the carcinogenicity and DNA adducts formation in the ovary of mice treated with DB[a,l]P, a tobacco smoke constituent and environmental pollutant. Ovarian tumors in B6C3F1 mice were induced by direct application of DB[a,l]P (24, 12, 6, and 3 nmol/mouse, three times a week for 38 weeks) into the oral cavity of mice. At 6 nmol, DB[a,l]P induced the highest total ovarian tumor incidence (79%), but the incidence of malignancy was only 15%. However, at the dose of 12 nmol, the total ovarian tumor incidence was 75%, and the incidence of malignancy was 65%. In addition to ovarian tumors, at the dose of 24 nmol, DB[a,l]P induced lesions in sites distal from the ovaries including the skin, mammary, lung, and oral tissues, which were rare at doses lower than 24 nmol. Another bioassay was conducted to detect and quantify DNA adducts induced by DB[a,l]P (24 nmol, three times a week for 5 weeks) in the ovary at 48 h and 1, 2, and 4 weeks after the last administration of DB[a,l]P. DNA was isolated, and the dibenzo[a,l]pyrene-11,12-dihydrodiol-13,14-epoxide (DB[a,l]PDE)-DNA adducts were analyzed by a LC-MS/MS method. DB[a,l]P resulted in the formation of (-)-anti-cis-DB[a,l]PDE-dA and (-)-anti-trans-DB[a,l]PDE-dA adducts, which were 0.8 and 1.6 fmol/10(6) dA, respectively, in ovaries of mice within 48 h, and the level of adducts decreased over a week. Our results indicated that DB[a,l]P can be metabolized to form (-)-anti-DB[a,l]PDE; the latter may, in part, account for DB[a,l]P-induced ovarian cancer. This animal model should assist to better understand the mechanisms, account for the induction of ovarian cancer by tobacco carcinogens, and facilitate the development of chemopreventive agents against ovarian cancer.

3,5,5-trimethyl-hexanoyl-ferrocene diet protects mice from moderate transient acetaminophen-induced hepatotoxicity

Acetaminophen (APAP) overdose is the most frequent cause of adult acute liver failure. Susceptibility or resistance to APAP toxicity is most likely accounted for by the interplay of several factors. One factor important in multiple different chronic liver diseases that may play a role in APAP toxicity is elevated hepatic iron. Hereditary hemochromatosis is traditionally associated with hepatic iron overload. However, varying degrees of elevated hepatic iron stores observed in chronic hepatitis C and B, alcoholic liver disease and nonalcoholic fatty liver disease also have clinical relevance. We employed an animal model in which mice are fed a 3,5,5-trimethyl-hexanoyl-ferrocene (TMHF)-supplemented diet to evaluate the effect of elevated hepatic iron on APAP hepatotoxicity. Three hundred milligrams per kilogram APAP was chosen because this dosage induces hepatotoxicity but is not lethal. Since both excess iron and APAP induce oxidative stress and mitochondrial dysfunction, we hypothesized that the TMHF diet would enhance APAP hepatotoxicity. The results were the opposite. Centrilobular vacuolation/necrosis, APAP adducts, nitrotyrosine adducts, and a spike in serum alanine aminotransferase, which were observed in control mice treated with APAP, were not observed in TMHF-fed mice treated with APAP. Further analysis showed that the levels of CYP2E1 and CYP1A2 were not significantly different in TMHF-treated compared with control mice. However, the magnitude of depletion of glutathione following APAP treatment was considerably less in TMHF-treated mice than in mice fed a control diet. We conclude that a TMHF diet protects mice from moderate transient APAP-induced hepatotoxicity prior to the formation of APAP adducts, and one contributing mechanism is reduction in glutathione depletion.

Therapeutic efficacy of FTY720 in a rat model of NK-cell leukemia

NK-cell leukemia is a clonal expansion of NK cells. The illness can occur in an aggressive or chronic form. We studied cell lines from human and rat NK-cell leukemias (aggressive NK-cell leukemia) as well as samples from patients with chronic NK-cell leukemia to investigate pathogenic mechanisms. Here we report that Mcl-1 was overexpressed in leukemic NK cells and that knockdown of Mcl-1 induced apoptosis in these leukemic cells. In vitro treatment of human and rat NK leukemia cells with FTY720 led to caspase-dependent apoptosis and decreased Mcl-1 expression in a time- and-dose-dependent manner. These biologic effects could be inhibited by blockade of reactive oxygen species generation and the lysosomal degradation pathway. Lipidomic analyses after FTY720 treatment demonstrated elevated levels of sphingosine, which mediated apoptosis of leukemic NK cells in vitro. Importantly, systemic administration of FTY720 induced complete remission in the syngeneic Fischer rat model of NK-cell leukemia. Therapeutic efficacy was associated with decreased expression of Mcl-1 in vivo. These data demonstrate that therapeutic benefit of FTY720 may result from both altered sphingolipid metabolism as well as enhanced degradation of a key component of survival signaling.

Phenylbutyl isoselenocyanate modulates phase I and II enzymes and inhibits 4-(methylnitrosamino)-1-(3-pyridyl)- 1-butanone-induced DNA adducts in mice

Lung cancer remains one of the most preventable forms of cancer with about 90% of cases attributed to cigarette smoking. Over the years, the development of chemopreventive agents that could inhibit, delay, or reverse the lung carcinogenesis process has been an active field of research, however, without much attainment. Through extensive structure-activity relationship studies, we recently identified a novel agent phenylbutyl isoselenocyanate (ISC-4), designed on the basis of naturally occurring isothiocyanates well known for their lung cancer prevention properties, as a potential chemopreventive agent. In this study, we used A/J mice to evaluate the lung cancer chemopreventive potential of ISC-4. A single intragastric dose of 1.25 μmol ISC-4 resulted in a time-dependent increase of selenium levels in serum, liver, and lung, suggesting that ISC-4 is orally bioavailable, a key requirement for a chemopreventive agent. This dose also resulted in a time-dependent inhibition of microsomal cytochrome P450 (Cyp450) activity and delayed increases in phase II UDP-glucuronyl transferase (Ugt) and glutathione-S-transferase (Gst) activity. ISC-4 was able to induce mRNA expression of Cyp, Ugt, and Gst enzyme isoforms in liver, but in lung, it inhibited Cyp isoforms while inducing Ugt and Gst isoforms. In addition, ISC-4 effectively inhibited methyl-DNA adduct formation in mice fed diet supplemented with ISC-4 for two weeks and then treated with the tobacco procarcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone. These results suggest that ISC-4 is a strong candidate for development as a chemopreventive agent.