bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 1869: Genetic variants of DNA repair genes and lung cancer among nonsmokers: A pooled analysis in the International Lung Cancer Consortium
Authors: Lee Yuan-Chin Amy , Hung Rayjean , Boffetta Paolo , Brennan Paul , Christiani David , Kiyohara Chikako , Lan Qing , Seow Adeline , Paolo Vineis , Zhang Zuo-Feng
Published: February 2011

Background

Lung cancer among nonsmokers has been considered as a different disease from that among smokers. Involuntary smoking has been suggested to be a risk factor for lung cancer among nonsmokers with a modest effect. Few studies have examined the role of single nucleotide polymorphisms (SNPs) of the DNA repair genes and their potential interactions with involuntary smoking on the development of lung cancer among nonsmokers.

Methods

We evaluated the associations between SNPs of the DNA repair genes and lung cancer based on a pooled data of the International Lung Cancer Consortium. The individual-level epidemiological data and genotyping data on eight SNPs from six participating studies were pooled, including 845 nonsmoker cases and 4,262 nonsmoker controls. Logistic regression models with adjustment by age, sex, ethnicity, study, and ever involuntary smoking status were used to obtain odds ratios (OR) and 95% confidence intervals (CI).

Results

Among nonsmokers, the associations with the polymorphisms in OGG1 S326C and XPD D312N were observed among those with involuntary smoking (for OGG1 S326C: OR=1.61, 95% CI 1.18-2.20 for CG, OR=1.74, 0.99-3.06 for GG, compared to CC; for XPD D312N: OR=1.06, 0.76-1.47 for AG, OR=1.60, 1.06-2.42 for AA, compared to GG), but not for those without involuntary smoking (for OGG1 S326C: OR=0.78, 0.39-1.54 for CG, OR=0.88, 0.25-3.06 for GG, compared to CC; for XPD D312N: OR=1.13, 0.57-2.21 for AG, OR=0.81, 0.27-2.43 for AA, compared to GG). The association with XRCC3 T241M variant was detected for adenocarcinoma and non-small cell lung cancer among those without exposure to involuntary smoking (adenocarcinoma: OR=3.52, 1.21-10.20 for AA, OR=0.94, 0.38-2.38 for GA, compared to GG; and non-small cell lung cancer: OR=2.75, 1.05-7.21 for AA, OR=1.10, 0.51-2.38 for GA, compared to GG, respectively). Due to limited power, no apparent interaction between DNA repair SNPs and involuntary smoking was detected.

Conclusion

This is the first large-scale collaborative study on the relationship between DNA repair genetic variants and lung cancer among nonsmokers, accounting for involuntary smoking. Our results show that SNPs of the DNA repair genes may play an important role for lung cancer among nonsmokers, and the associations may vary by involuntary smoking status and histological subtype.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1869.
Abstract 187: Epigenetic memory during breast cancer progression is sustained by Smad signaling pathway
Authors: Thiagalingam Sam , Lambert Arthur W. , Ozturk Sait , Abdolmaleky Hamid M. , Papageorgis Panagiotis
Published: February 2011

The molecular basis for the “epigenetic memory” that ensures maintenance of unique patterns of regulatory DNA methylation of selected genes responsible for cancer progression has remained elusive. Using a breast cancer progression model system, we found that hyperactive TGFβ-TGFβR-Smad2 signaling axis is involved in the maintenance of DNA hypermethylation mediated silencing of critical target genes to facilitate breast cancer progression. Disruption of TGFβ signaling caused a corresponding decrease in DNMT1 binding activity accompanied with increased expression of the target genes and acquisition of tumorigenic properties. These observations are consistent with passive demethylation of the newly synthesized DNA due to absence of sustained TGFβ-Smad signaling downstream events. In summary, we provide conclusive evidence that the reversal of the DNA hypermethylation status of gene promoters occurs as a result of TGFβ/Smad signaling pathway perturbation. By extension, we predict that inhibition of TGFβ-TGFβR-Smad2 signaling axis is an effective therapeutic strategy for breast cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 187.
Abstract 1873: Delayed progression to hormone-independent prostate cancer through modulation of mTOR by omega-3 fatty acids
Authors: Apte Shruti , Friedrichs William , Hursting Stephen , Cavazos David , Nogueira Leticia , Perkins Susan , deGraffenried Linda A.
Published: February 2011

Prostate cancer is the second leading cause of cancer related deaths in men. The primary obstacle in effective treatment of prostate cancer is the progression of the disease from a hormone-dependent to a hormone-independent state. Previous studies indicate that activation of the mammalian Target of Rapamycin (mTOR) signaling pathway may be involved in progression of prostate cancer. Several studies have demonstrated a significant role for mTOR in promoting androgen independence. Recent data indicate that the combination of androgen deprivation with mTOR inhibition provides an additive anti-tumor effect in vivo. mTOR is directly involved in regulating cell survival, growth, proliferation, and differentiation. Many dietary and lifestyle interventions that reduce cancer risk and progression mediate their effects through regulation of mTOR signaling. Epidemiological studies indicate an inverse relation between dietary intake of omega-3 fatty acids and prostate cancer risk. Omega-3 fatty acids have been shown to inhibit prostate cell growth both in vitro and in vivo. Preliminary data from our laboratory demonstrated that treatment of LNCaP prostate cancer cells with omega-3 fatty acids, specifically docosahexaonoic acid (DHA), delayed development of androgen independence in vitro. This delay correlated with a decrease in protein expression of downstream targets of mTOR regulation, including phosphorylated S6, Bcl-2, and cyclin D. We hypothesize that omega-3 fatty acids may prevent prostate cancer progression to a hormone independent phenotype in part through modulation of mTOR. To test this hypothesis, we transiently transfected LNCaP cells to express a constitutively active mTOR. Our results showed that expression of the constitutively active mTOR correlated with a reduction in response to hormone deprivation, resembling that observed in our previously generated hormone refractory LNCaP cell line. When exposed to hormone-ablation conditions, the proliferation rates observed compared to the that of the vector-only control cells were 64% higher in the constitutively active mTOR cells, and 55% higher in the hormone-refractory cell. Ongoing studies are using a stable transfectant of constitutively active mTOR to determine if modulation of mTOR signaling is one mechanism by which the omega-3 fatty acids delay the progression to hormone-independence. These studies suggest that inhibition of mTOR is critical for cellular response to hormone ablation, and that mTOR may be a viable target for delaying progression to a hormone refractory disease.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1873.
Abstract 1874: Impact of vitamin D and calcium on PGE2 metabolism in colorectal cancer
Authors: Nittke Thomas , Horváth Henrik C. , Bises Giovanna , Thalhammer Theresia , Kállay Enikoe
Published: February 2011

Aberrant expression of cyclooxygenase 2 (COX2), the enzyme responsible for synthesizing prostaglandin E2 (PGE2), is one of the early events in colorectal cancer (CRC) development. Repression of COX2 results in the inhibition of prostaglandin synthesis which can delay colon tumorigenesis. It has been shown previously that in cancer cells 1α,25-dihydroxyvitamin D3 (1,25D3) downregulates the expression of COX2 and increasing that of the PGE2 catabolizing enzyme 15-prostaglandin-dehydrogenase (15-PGDH). Due to the differentiation-promoting, pro-apoptotic and anti-proliferative effects calcium and 1,25D3 have become factors of great interest for the chemoprevention of CRC.

In order to study the effect of calcium on the PGE2 pathway, we treated the colon cancer cell line Caco-2 with low calcium (0.025 mM) for 48 hours. This led to an increase in COX2 expression while decreasing that of 15-PGDH. Similar effect was seen in vivo: in mice low calcium (0.04%) diet elevated COX2 expression in the colon when compared with the control diet (0.5%). Interestingly, expression of the vitamin D catabolizing enzyme, CYP24A1 was also augmented, in parallel with an increase of crypt cell proliferation. However, expression of the 1,25D3 synthesizing CYP27B1 was not affected. These results suggested that low dietary calcium might reduce 1,25D3 levels in the colon, thereby lowering the impact of 1,25D3 on the COX2-PGE2 pathway. To investigate whether this expression profile is prevalent also in the human colon, we screened over 200 tissue specimens from CRC patients by QRT-PCR. In colon tumors, the mRNA ratio of 15-PGDH and COX2 was significantly downregulated (p<0.0001). This unbalance implicates an elevated PGE2 production. In these tumor samples the CYP24A1/CYP27B1 mRNA ratio was also significantly increased (p<0.05) as compared with the adjacent mucosa. Additionally, CYP24A1 staining confirmed elevated levels of the enzyme in adenocarcinomas.

Thus, in these colorectal tumors local 1,25D3 levels were most probably insufficient to inhibit PGE2 accumulation due to high CYP24A1 expression. Low dietary calcium is a promoter of CYP24A1 expression. Our data represent one of the possible molecular mechanisms for the synergistic action of calcium and vitamin D levels in CRC chemoprevention.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1874.
Abstract 1875: Dietary grape seed proanthocyanidins induce rapid repair of DNA damage via nucleotide excision repair genes in preventing UV-induced immunosuppression
Authors: Katiyar Santosh K. , van Steeg Harry , Sharma Som D.
Published: February 2011

Ultraviolet (UV) radiation-induced immunosuppression has been implicated in the development of skin cancers, including melanoma and non-melanoma. UV-induced DNA damage, predominantly the formation of cyclobutane pyrimidine dimers (CPDs), has been recognized as an important molecular trigger for the initiation of UVB-induced immunosuppression and skin carcinogenesis. We have shown earlier that administration of dietary grape (Vitis vinifera) seed proanthocyanidins (GSPs) supplemented with AIN76A control diet inhibit photocarcinogenesis in mice; however, the molecular mechanism of chemopreventive effects of GSPs are not clearly understood. To investigate the possible mechanism of action of GSPs we used genetically modified human cells and animal model. We observed that administration of dietary GSPs (0.2 and 0.5%, w/w) with supplementation of AIN76A control diet inhibited (52-65%, P<0.001) UV-induced suppression of contact hypersensitivity response to a contact sensitizer, 2,4-dinitrofluorobenzene, in a contact hypersensitivity mouse (C3H/HeN) model. Dietary GSPs repaired UV-induced DNA damage (CPD-positive cells) faster in the skin of mice as demonstrated by reduced number of CPD-positive cells (59%, p<0.001), and reduced the migration of CPD-positive cells from the skin to draining lymph nodes compared to non-GSPs-fed control mice, which was associated with the elevated levels of nucleotide excision repair (NER) genes. GSPs did not prevent UV-induced immunosuppression in NER-deficient mice but significantly prevented in NER-proficient mice (p<0.001) concomitantly repaired UV-induced DNA damage in NER-proficient mice (p<0.01) but did not repair in NER-deficient mice as indicated by immunohistochemical analysis of CPD-positive cells. Further, southwestern dot-blot analysis revealed that GSPs repaired UV-induced CPDs in xeroderma pigmentosum complementation group A (XPA)-proficient cells obtained from healthy person but did not repair in XPA-deficient cells obtained from the patients suffering from xeroderma pigmentosum disease, indicating that NER mechanism is involved in DNA repair. Together, these data identify a novel mechanism by which dietary GSPs prevent UV-induced immunosuppression which is mediated through rapid repair of damaged DNA, and that these effects lead to the prevention of UV radiation-induced skin tumors in mice.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1875.
Abstract 1885: Dietary stearate reduces abdominal fat, serum leptin and glucose and increases MCP-1
Authors: Shen Ming-Che T. , Evans Lynda M. , Toline Eric C. , Desmond Renee A. , Gene Siegal P. , Hardy Robert W.
Published: February 2011

Stearate is a dietary, long-chain saturated fatty acid (C18:0) that has been shown to decrease breast cancer cell proliferation, migration, and invasion in vitro and reduce tumor growth and metastasis in vivo. Obesity, or excess adipose tissue, is a risk factor for breast cancer. Our overall hypothesis is that dietary stearate inhibits breast cancer by decreasing body fat. Our goal was to determine whether there was an association between dietary stearate and adipose tissue. Four groups of 10 athymic nude mice each were each fed one of four different diets for 18 weeks (6% corn oil - low fat diet, 17% stearate diet, 17% corn oil diet, or 17% safflower oil diet). Body composition was assessed by nuclear magnetic resonance (NMR) and dual energy X-ray absorptionmetry (DXA). Serum concentrations of glucose, insulin, leptin, adiponectin, interleukin-6, and monocyte chemoattractant protein-1 (MCP-1) were also determined. In a repeated measures model assessing the relationship between groups, for fat and lean mass over time the following differences were found: the stearate group had significantly reduced body fat compared to the low fat and the corn oil groups (p<0.001); mice on the high fat diets (stearate, corn oil, and safflower oil) had a significantly increased lean body mass compared to the low fat group (p=0.009, 0.012, and 0.022 respectively). Postmortem measurement revealed no significant changes in organ weight (brain, heart/lungs, liver, and kidney) among the four diet groups. However dietary stearate had less abdominal fat than the other diets although only the low fat - stearate difference was significant (low fat-stearate *p= 0.0043. corn oil-stearate p= 0.0565, and safflower-stearate p= 0.0636). Serum glucose and leptin concentrations were significantly reduced in the stearate diet mice (glucose, p<0.039, stearate vs all other diets, leptin, p<0.015, stearate vs low fat and corn oil diets). Serum MCP-1 was increased in stearate diet mice compared to either the low fat or safflower oil mice (p<0.019). Significant differences were not observed with the other analytes. Studies have suggested that glucose and leptin have cancer promoting effects, while MCP-1 may promote or inhibit breast cancer. Overall these data support our hypothesis that dietary stearate decreases body fat and that this decrease in body fat may be related to stearate inhibition of breast cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1885.
Abstract 189: 5-azacytidine radiosensitizes androgen-independent prostate cancer cells by impairing DNA double-strand break repair
Authors: Weterings Eric , Dino Pamela M. , Feng Yi , Sharma Sunil , Pizzorno Giuseppe
Published: February 2011

5-azacytidine is a cytidine analogue with cytotoxic and cytostatic activity, currently utilized for the treatment of myelodysplastic syndromes. The cytostatic activities of low-dose 5-azacytidine are attributed to its incorporation into the DNA and RNA of mammalian cells, which influences epigenetic regulation, cell cycle progression, and protein expression. We observed that treatment with 5-azacytidine significantly radio-sensitizes androgen-independent prostate cancer cells, synergistically enhancing the overall efficiency of radiation treatment both in vivo and in vitro. Furthermore, we found that exposure of androgen-independent prostate cancer cells to 5-azacytidine impairs or delays the repair of radiation induced DNA double-strand breaks through the non-homologous end-joining pathway. This observation explains the radio-sensitizing potential of 5-azacytidine and constitutes the first conclusive evidence for a DNA repair defect introduced by this compound. In addition, we found that this DNA repair defect was not introduced by the 2’-deoxy derivative of 5-azacytidine. From this finding we infer that the inhibitory effects of 5-azacytidine on DNA repair are primarily mediated by its incorporation into the RNA. We suggest that a combined treatment with 5-azacytidine and ionizing radiation would be a good candidate for clinical trials, not necessarily limited to prostate cancers.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 189.
Abstract 1895: Phytochemicals inhibit proliferation and promote death through NADPH oxidase and G6PD
Authors: Edderkaoui Mouad , Hui Hongxiang , Li Gang , Xu Jun , Lee Wai-Nang , Go Vay Liang W. , Pandol Stephen J.
Published: February 2011

Background & Aims: Pancreatic cancer is a very aggressive disease that is resistant to therapy. Evidence from population studies indicates a protective effect of fruits and vegetables in the diet on cancer including pancreatic cancer. In vitro and in vivo studies, including our own, suggest that several phytochemicals, such as ellagic acid and lycopene may be involved in this beneficial effect. In this study we investigated the effect of these phytochemicals, alone and in combination, on apoptosis and proliferation of pancreatic cancer cells in vitro, and we analyzed their mechanism of action. Methods: We measured the effect of ellagic acid and lycopene on DNA fragmentation using Cell Death Detection ELISA and on proliferation using 3H-thymidine incorporation into DNA in pancreatic cancer cell line MIA PaCa-2. Molecular signaling mechanisms were evaluated with Western. NF-kB activity was measured using electromobility shift assay. Metabolic phenotype of the cells was analyzed using mass spectrometry and the glucose molecule labeled with stable isotope D-glucose (1,2-13C2). Results: Both lycopene and ellagic acid at doses from 0.1 to 30 μM induced increases in DNA fragmentation and inhibited proliferation in pancreatic cancer cells. Combinations of ellagic acid with lycopene at low doses (1 µM) induced a synergistic effect on DNA fragmentation and proliferation. Ellagic acid induced apoptosis by decreasing NF-kB activity in pancreatic cancer cells. Lycopene decreased NADPH oxidase activity. Combined compounds had a synergistic effect on the inhibition of glucose-6-phosphate dehydrogenase (G6PD) activity as measured by mass spectrometry leading to a synergistic inhibition of DNA synthesis. Conclusions: Combination of ellagic acid and lycopene induced a synergistic effect on apoptosis and proliferation in pancreatic cancer cells. The synergistic effect is due to different mechanisms of action of these phytochemicals leading to the inhibition of G6PD activity, a key step in DNA synthesis. Our study suggests a potentially beneficial role for combinations of ellagic acid and lycopene in prevention and treatment strategies of pancreatic cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1895.
Abstract 1899: Induction of phase 2 antioxidant genes by the aqueous extract of Matricaria chamomilla (Chamomile) through Keap1-Nrf2 signaling pathway
Authors: Bhaskaran Natarajan , Shukla Sanjeev , Gupta Sanjay
Published: February 2011

Induction of phase 2 detoxifying enzymes in response to naturally occurring agents provides an effective means of protection against oxidative stress. Increasing lines of evidence show that the Keap1-Nrf2 complex is a key molecular target of phase 2 enzyme inducers. The transcription factor Nrf2 is a member of basic leucine-zipper NF-E2 family and interacts with the antioxidant response element (ARE) in the promoter region of phase 2 detoxifying enzymes. A cytoplasmic actin-binding protein, Keap1, is an inhibitor of Nrf2 and sequesters it in the cytoplasm. Various extracellular stimuli and inducers dissociate this complex, allowing Nrf2 to translocate into the nucleus, binding with ARE and induce the expression of various antioxidant genes. Recently natural compounds have been established as activators of phase 2 antioxidant enzymes through Nrf2 signaling pathway. We used aqueous chamomile extract obtained from dried flowers to investigate its effect on Nrf2 activation and induction of phase 2 enzymes in human prostate cancer PC-3 and LNCaP cells. Treatment of these cells with chamomile at 1-40μM concentration equivalent to aglycone apigenin caused significant dissociation of Keap1 from the Keap1-Nrf2 complex with significant decrease of Keap1 in the cytoplasm in dose- and time- dependent fashion. Similarly, a marked decrease in Nrf2 was observed in the cytoplasm after chamomile treatment. Chamomile treatment further led to increase in phase 2 enzymes including superoxide dismutase, NAD(P)H dehydrogenase [quinone] 1 and catalase in these cells which correlated with nuclear Nrf2 expression in dose- and time- dependent manner. Taken together, these molecular evidences provide an insight into the mechanism underlying the induction of phase 2 enzymes through Keap1- Nrf2 signaling pathway by chamomile, endorsing its antioxidant function.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1899.
Abstract 1902: A multilevel map of the immunological terrain in an orthotopic mouse model of lung cancer with emphasis on PGD2/DP1-dependent immunomodulation
Authors: Pyfferoen Lotte , Prijck Sofie De , Vanheerswynghels Manon , Deswarte Kim , Vergote Karl , Hammad Hamida , Lambrecht Bart N. , Vermaelen Karim Y.
Published: February 2011

The influence of the organ-specific micro-environment on the host immune response to tumors has been insufficiently adressed. We examined tumor-induced immunomodulation in an orthotopic mouse model of lung cancer. We focused on the PGD2-DP1 signalling axis given its contrasting roles in dendritic cell (DC)-dependent immunomodulation on one hand, and tumor angiogenesis on the other.

We found an enrichment of CD11b+ (inflammatory type) DCs within lung tumors. In sharp contrast to DCs in immediately adjacent peritumoral lung tissue, intratumoral DCs displayed a strong upregulation of the T-cell co-inhibitory molecules PD-L1 and ICOS-L on the cell surface. Remarkably, tumor-infiltrating CD4 and CD8 T-cells showed a robust upregulation of the activation marker CD69, while increased numbers of double-negative T-cells were seen within lung tumors as well. Regulatory T-cells were also clearly elevated within tumors as well as in draining lymph nodes (LN) of tumor-bearing hosts. Interestingly, DCs in lung-draining LNs appeared more immature in end-stage tumor bearing mice. Finally, systemic tumor-induced effects were manifest as a strong expansion of myeloid derived suppressor cells in the spleen.

DP1-deficiency did not significantly affect any of these immunological parameters. Moreover, in contrast to previous observations using heterotopically implanted lung tumor cells, DP1-deficiency had no impact on survival in our orthotopic lung cancer model.

In summary, we provide a multi-level detailed map of tumor-immune system interactions in an orthotopic mouse model of lung cancer. Our findings in DP1-deficient mice stress the importance of the local, organ-specific milieu in driving tumor development and shaping host immune responses.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1902.
Abstract 1904: Reversal of thymic involution and immunosuppression in tumor-bearing mice by IFN-γ
Authors: Carrio-Jardines Roberto , Iragavarapu-Charyulu Vijaya , Libreros Stephania , Garcia-Areas Ramon A. , Lopez Diana M.
Published: February 2011

The thymus is a central lymphoid organ critical for the development and maintenance of an effective peripheral T cell repertoire. Most important, it provides a specialized environment for the selection of rearranged clones that will function appropriately in the adaptive immune response. The tumor-induced immunosuppression observed during murine mammary tumorigenesis has been associated with a profound thymus involution accompanied with a severe depletion of the most abundant subset of thymocytes; CD4+CD8+ double positive (DP) immature cells. Thymic involution has been observed in several model systems; including graft-vs-host disease, aging, and tumor development, however, the mechanisms involved in this phenomenon remain to be elucidated. Previous results from our laboratory have reported that the severe thymic atrophy and impaired T cell development seen in mammary tumor bearers are associated with an arrest in at least two steps of T cell differentiation, changes in the levels of crucial cytokines expressed in the thymus microenvironment, and a progressive increase in apoptosis during the tumor development mainly due to downregulation of important molecules that control programmed cell death. Moreover, we have shown that mice bearing the murine parental D1-DMBA-3 mammary tumor and tumors derived from the parental tumor, the DA-3, develop many changes in their cytokine production. For example, in mice bearing these tumors there is a decrease in the IFN-γ in the peripheral circulation and production of this crucial cytokine is greatly diminished in the T cells. In the present study we have used our DA-3 mammary tumor model to investigate whether the levels of IFN-γ have an important role in anti-tumor activity, in the pathogenesis of thymic atrophy as well as the tumor-induced immunosuppression in these mice. Interestingly, our results show that the overexpression of IFN-γ in DA-3 tumor cells results in a marked delay of tumor growth and a blockage in the tumor-associated thymus atrophy. Importantly, peripheral T cells from IFN-γ-transfected DA-3 tumor-bearing mice, show markedly high levels of this cytokine. Moreover, when thymuses from tumor-bearing mice that received IFN-γ were analyzed, thymic populations were very similar to those observed in the thymuses of normal mice. Collectively, our data suggest that the replacement of the faulty levels of IFN-γ in tumor bearers results in a delayed tumor growth and thymic involution leading to a decrease of tumor-induced immune suppression caused by the mammary tumor development.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1904.
Abstract 1906: IL-6-mediated activation of STAT3 inhibits APC and T cell function in metastatic breast cancer
Authors: Anderson Karen S. , Sasada Tetsuro , Nelson Erik , Khazaie Khash , Feng Gang , Lin Simon , Frank David A.
Published: February 2011

Background: The transcription factor STAT3 is a negative regulator of myeloid inflammatory immune responses, leading to profound suppression of dendritic cell (DC) and T cell function, and anti-tumor immunity. Blockade of STAT3 signaling in tumor models results in activation of innate immune cells, DCs, and tumor infiltration of T cells. We hypothesized that tumor associated macrophages (TAMs) from breast cancer patients were dysfunctional, due to IL-6-mediated activation of STAT3.

Methods: To isolate sufficient numbers of CD14+ TAMs and CD3+ tumor infiltrating lymphocytes (TILs) for functional assays, 10 malignant effusions were obtained from breast cancer patients and peripheral blood was obtained from 8 healthy controls. Levels of up to 22 cytokines in the effusions and the blood were determined by Luminex cytokine assay. CD14+ TAMs and CD3+ TILs were magnetically sorted, and functional mixed lymphocyte reaction (MLR) assays were performed. Quantitation of STAT3 and tyrosine-phosphorylated STAT3 (pSTAT3) were determined by immunoblotting. RNA expression analysis of TILs and healthy donor CD3+ cells was performed using Affymetrix U133 microarrays.

Results: Malignant effusions from breast cancer patients have high levels of IL-6 (mean 3188 pg/ml; range 966-5235), compared with serum from healthy donors (mean 88 pg/ml; p<0.0001). TAMs isolated from malignant effusions, but not peripheral blood, poorly stimulated healthy T cells in MLR, and showed increased expression of pSTAT3 and total STAT3 on immunoblot. A 30 minute exposure to a malignant effusion containing high levels of IL-6 markedly induced STAT3 activation in healthy donor CD14+ monocytes. Compared with CD3 cells from healthy donors (n=3), RNA microarray analysis of CD3+ TILs (n=3) showed downregulation in TCR signalling (Zap70, fyn, PI3K), NK/CTLs (CD160, KLRF1), and chemokines for T cell trafficking (CXCR4). Immunosuppressive factors (IL10, PDIA4, IL13R, STAT1, and VEGF) were upregulated (p<0.05).

Conclusions: High levels of IL-6 in breast cancer malignant effusions are associated with both antigen presenting cell and T cell dysfunction. Inhibition of STAT3 is a potential target to enhance immune activation.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1906.
Abstract 1907: Mechanisms mediated by CXCL12 signaling through CXCR4 and CXCR7 in breast cancer
Authors: Mosley Lasharon D. , Singh Rajesh , Sharma Praveen K. , Triplett Ashley S. , Singh Shailesh , Lillard James W.
Published: February 2011

Interactions between chemokines and their receptors are involved in organ-specific homing and propagation of metastatic breast cancer (BrCa) cells. BrCa cells express higher levels of CXCR4 and CXCR7 mRNA and cell surface protein, than normal human mammary epithelial cells (HMECs). Recent studies show CXCR7 is highly expressed by activated endothelial cells (i.e., neovasculature), fetal liver cells, and many tumors, but not by non-transformed (or normal) human tissues. Unlike other chemokine receptors, activation of CXCR7 does not cause Ca2+ mobilization/flux or cell migration. However, CXCR7 activation by its ligands provides signals for growth, survival, and adhesion. CXCR4, CXCR7, and CXCL12 mRNAs and proteins are differentially expressed by BrCa cell lines (MCF-7 and MDA-MB-231) and breast tumor, than compared to HMEC or benign mammary tissue, respectively. Using selective G protein inhibitors, CXCR4/CXCR7-specific siRNAs as well as Amnis ImageStream, real time PCR, and active matrix metalloproteinase assays, we tested the hypothesis that CXCR7 and its interactions with CXCR4 and CXCL12 promote BrCa cell collagenase expression, alter NF-κB and ERK1/2 localization to the nucleus, and correlates with cell cycle. CXCL12-induced CXCR4 mRNA upregulation required Gβγ protein and/or JAK/STAT signal transduction; CXCL12 expression was negatively regulated by the presence of CXCR4. CXCL12-mediated CXCR7 mRNA expression in a pertussis toxin-sensitive manner. Lastly, CXCL12-dependent MMP-1 and MMP-13 mRNA expression was Gα protein-, Gβ protein-, and Gγ protein-dependent presumably through CXCR4, while elevated expression of CXCR7 suppressed these effects. Together, this study suggests that differential and cell cycle-dependent CXCR7 and CXCR4 expression plays a critical role in enhancing BrCa cell invasion and survival cell signals, which were CXCL12-dependent, but often G protein-independent.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1907.
Abstract 1914: Cross-talk between breast cancer cells and tumor-associated macrophages leads to tumor cell invasion, angiogenesis and metastasis
Authors: Luo Yun Ping , Liao Debbie , Chuang Tsung-Hsien , Xiang Rong , Reisfeld Ralph A.
Published: February 2011

Interactions between neoplastic and stromal cells leads to crosstalk that contributes to tumor growth and progression. Since Fos-related antigen-1 (Fra-1) and Interleukin 6 (IL-6) are involved in tumor cell angiogenesis, invasion and metastasis, and are frequently deregulated in cancer cells, they represent attractive targets to regulate these effects. Here, we demonstrate that up-regulation of Fra-1 by tumor associated macrophages (TAMs) represents a malignant switch in breast carcinoma triggered by the deregulation of the IL-6/JAK/Stat3 signaling pathway which, in turn, increases the release of pro-angiogenesis factors MMP9, VEGF and TGF-β. Co-culture of 4T1 breast cancer cells with TAMs leads to up-regulation of Fra-1, IL-6 and Stat3 in TAMs. Furthermore, knockdown of Fra-1 in TAMs causes downregulation of IL-6, Stat3 and decreases the release of MMP9, VEGF and TGF-β. Together, these effects suppress the malignant characteristics of 4T1 breast tumor cells such as invasiveness, angiogenesis and metastasis. This study delineates novel mechanisms involved in the transcriptional deregulation of Fra-1 that lead to the activation of the IL-6/JAK/Stat3 signaling pathway in TAMs. Such events play a key role in promoting breast cancer cell invasion, growth and metastasis and our findings will determine if AP-1 family transcription factors such as Fra-1 are responsible for the overexpression of IL-6 in TAMs. Importantly, blocking of the IL-6/JAK/Stat3 signaling pathway will interrupt the crosstalk between TAMs and breast tumor cells in the tumor microenvironment (TME) and thereby change the biological function of TAMs, resulting in the suppression of breast cancer invasion and metastasis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1914.
Abstract 1919: Phosphatidylserine on dying tumor cells suppresses dendritic cell activation and inhibits tumor immunity: reversal with PS-targeting antibody
Authors: Huang Xianming , Ye Dan , Thorpe Philip E.
Published: February 2011

We recently showed that PS on the surface of apoptotic cancer cells can suppress recognition of tumor antigens by the immune system. It appears from work in several laboratories that dendritic cells (DC) that ingest PS-expressing tumor cells fail to mature in response to external maturation signals. In the present study, we investigated whether masking PS on apoptotic tumor cells with anti-PS antibody (2aG4) can reverse the inhibitory effect of PS on DC. Mouse bone marrow derived DC were cocultured with irradiated (PS-expressing) 4T1 breast tumor cells in the presence or absence of 2aG4. We found that: (i) masking tumor cell PS with 2aG4 increases their phagocytosis by DCs; (ii) masking tumor cell PS with 2aG4 allows DCs to mature and express immunostimulatory molecules (CD40, CD80, CD86 and MHC II); (iii) masking PS with 2aG4 decreases the production of anti-inflammatory cytokines (TGFβ and IL-10) and increases the production of inflammatory cytokines (TNFα, CCL5, IL-1β and IL-6), indicating that PS-blockade polarizes DC towards the immunostimulatory type I phenotype; (iv) immunizing mice with 2aG4-treated irradiated 4T1 cells enhances the immunogenicity of the tumor cells, rendering them resistant to rechallenge with syngeneic viable 4T1 tumor cells. These results have important implications for our understanding of the immunosuppressive effects of PS in cancer and could lead to the development of a novel whole cell cancer vaccine strategy in which PS-blocking is used to enhance immunogenicity.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1919.
Abstract 1922: Do stress response genes play a role in maintaining MDSC survival and suppression
Authors: Beury Daniel W. , Fitzgerald Phillip , Srivastava Minu K. , Ostrand-Rosenberg Suzanne
Published: February 2011

Myeloid- derived suppressor cells (MDSC) contribute to immune suppression in tumor bearing individuals. Their suppression and survival are increased by inflammation. MDSC production of toxic radicals is the primary mechanism of suppression but the toxic mediators do not affect the MDSC themselves. We are investigating stress response genes that may maintain MDSC survival and facilitate suppression. BALB/c mice were injected with BALB/c derived mammary carcinoma 4T1 or 4T1 constitutively expressing the pro-inflammatory cytokine IL-1β (4T1/IL-1β). Primary tumors were surgically removed after 25 days. At 35 days, spleens were harvested and assayed for the percentage of Gr1+ CD11b+ MDSC. Surgical removal of 4T1 results in a regression of the MDSC population, however MDSC do not regress in mice bearing 4T1/IL-1β tumors, confirming that inflammation increases MDSC survival. Western blots and confocal microscopy of MDSC induced by 4T1 and 4T1/IL-1β tumors localize Nrf2 in the nucleus, demonstrating that Nrf2 is activated in MDSC. In flow cytometry assays, MDSC induced by 4T1/IL-1β have higher expression of one chain of the cystine transporter, xCT, compared to 4T1 induced MDSC. 4T1/IL-1β induced MDSC also expressed more reactive oxygen species (ROS) compared to 4T1 MDSC. The increased expression of ROS and xCT in 4T1/IL-1β induced MDSC represent mechanisms for the increased suppression of CD4+ and CD8+ T cells compared to 4T1 induced MDSC. Catalase, a protein transcriptionally regulated by Nrf2, when added to a T cell activation assay eliminates MDSC suppressive activity. Addition of catalase to T cells co-cultured with MDSC and peptide causes a synergistic effect, activating T cells to a greater level than peptide alone. Collectively these data suggest that stress genes may play a role in maintaining MDSC survival and suppressive activity.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1922.
Abstract 1923: Regulatory T-cell subsets suppress high avidity CD8 T-cell activation and trafficking
Authors: Weiss Vivian L. , Lee Timothy H. , Armstrong Todd D. , Jaffee Elizabeth M.
Published: February 2011

Cancer vaccines are one treatment modality that can prevent the development of some cancers. The advantage of cancer vaccines is their ability to target cancer proteins specifically, thereby resulting in minimal toxicities to normal tissue. Unfortunately, immune tolerance mechanisms provide a formidable barrier to effective treatment of cancer when vaccines are used as a single agent. One way to overcome these barriers is to develop vaccination strategies that combine vaccines with tolerance-reducing agents that allow the recruitment and activation of the most potent tumor-specific T cells. In fact, accumulating data suggest that the availability and activation of a diverse high avidity T cell repertoire is a key factor in the effectiveness of cancer vaccines. To further understand the role of high avidity T cells in the treatment of cancer, we developed TCR transgenic mice that are high avidity and specific for the immunodominant CD8+ T cell epitope, RNEU420–429, that derives from the HER-2/neu breast cancer antigen. By adoptively transferring these high avidity T cells into the tolerant environment of the neu-N mouse, we have studied their proliferation, trafficking, and tumor-clearing capacity. High avidity T cell responses were evaluated following vaccination using a neu-expressing, GM-CSF-secreting, whole cell vaccine. Vaccine was given either alone or in combination with two T regulatory cell (Treg) depleting agents: Cyclophosphamide (Cy) and the anti-CD25 antibody, PC61. Our data demonstrate that the Cy specifically targets a subset of Tregs and the depletion of this subset allows for more effective tumor clearance by high avidity T cells. While most tolerance reduction strategies focus on the depletion of CD4+CD25+ T regulatory cells, our studies reveal the existence of a population of CD25low effector Tregs that can effectively traffic to the tumor microenvironment and mediate tolerance. Through targeted removal of this CD25low effector Treg population, high avidity T cells undergo increased activation, T cell trafficking, and tumor clearance. Thus, we demonstrate that vaccination in combination with targeted, effector Treg depletion can activate higher avidity T cell populations to eradicate pre-existing tumor burdens. Through an in-depth understanding of the tolerance mechanisms that mediate high avidity T cells suppression, it will be possible to design more effective vaccination strategies to activate the small but potent high avidity T cell populations present in cancer patients.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1923.
Abstract 1928: Resistance of human melanoma to MART-1/HLA A2.1 specific CTL (F5 CTL)-killing: poor recognition, low MART-1 expression and reversal of resistance
Authors: Jazirehi Ali R. , Baritaki Stavroula , Bonavida Benjamin , Economou James S.
Published: February 2011

Adoptive cell therapy (ACT) using ex vivo engineered autologous lymphocytes encoding high affinity TCRα/β genes specific for MART-1+/HLA-A2.1+ (F5 CTL) kill human melanoma lines in vitro in an MHC-I restricted and caspase-dependent manner and mediate modest clinical responses. Development of antigen-loss tumor variants is one mechanism of immune escape. The objective of this study is to investigate the mechanism of resistance to CTL-killing due to loss of recognition and reversal of resistance by pharmacological inhibitors. We hypothesized that the development of Ag-loss variants is due to degradation or epigenetic modifications of MART-1. Also, we hypothesized that aberrant apoptotic cell signaling contribute to immune resistance. To test the hypotheses, we generated F5 CTL-resistant clones (R) from sensitive parental (P) lines by growing the cells under F5 CTL selective pressure followed by limiting dilution. Detailed analysis revealed that compared to P cells, M244R clone exhibit significantly higher resistance to F5 CTL killing, proliferate at a higher rate, and are unable to trigger IFNγ release by F5 CTLs suggesting diminished MART-1 expression (loss of MART-1 was confirmed by gene analysis, surface HLA-A2.1 was unaltered). F5 CTLs recognized and interacted with MART-1 pulsed M244R clone (IFNγ secretion and conjugate formation), yet, the cells still remained resistant to F5 CTL killing. We observed deregulation and constitutive hyper-activation of the components of the NF-κB pathway leading to over-expression of anti-apoptotic Bcl-2, Mcl-1 and Bcl-xL in M244R clones. The proteasome inhibitor bortezomib efficiently blocked NF-κB activity, reduced the expression of resistant factors, restored recognition and sensitized the M244R clones to F5 CTL-induced killing. These novel results suggest that bortezomib, not only interferes with the deregulated signaling pathway but also restores recognition of low MART-1 expressing, poorly recognized immune resistant variants by F5 CTLs, thus, reverses the acquired resistance. These results also imply that immune resistance can not be solely explained by the development of MHC-/antigen-loss variants and is partly due to perturbed cell survival signaling pathways of the tumor cells. Targeted therapy with specific pharmacological inhibitors in conjunction with F5 CTL can override F5 CTL-resistance, which can improve clinical response.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1928.