Oberg, Ann L.

DNA repair is a key mechanism in maintaining genomic stability: repair deficiencies increase DNA damage and mutations that lead to several diseases, including cancer. We extracted DNA from peripheral blood mononuclear cells (PBMCs) of 48 pancreatic adenocarcinoma cases and 48 healthy controls to determine relative levels of nuclear DNA (nDNA) and mitochondrial DNA (mtDNA) damage by QPCR. All participants were never smokers and between the ages of 60 and 69. Average levels among cases were compared to controls using a rank sum test, and logistic regression adjusted for potential confounding factors (age, sex, and diabetes mellitus). Cases had less DNA damage, with a significant decrease in mtDNA damage (P‐value = 0.03) and a borderline significant decrease in nDNA damage (P = 0.08). Across samples, we found mtDNA abundance was higher among non‐diabetics compared to diabetics (P = 0.04). Our results suggest that patients with pancreatic adenocarcinoma have less DNA damage in their PBMCs, and that having diabetes, a known pancreatic cancer risk factor, is associated with lower levels of mtDNA abundance. © 2014 Wiley Periodicals, Inc.

Abstract Pancreatic ductal adenocarcinoma (PDA) arises at the convergence of genetic alterations in KRAS with a fostering microenvironment shaped by immune cell influx and fibrotic changes; identification of the earliest tumorigenic molecular mediators evokes the proverbial chicken and egg problem. Matrix metalloproteinases (MMP) are key drivers of tumor progression that originate primarily from stromal cells activated by the developing tumor. Here, MMP3, known to be expressed in PDA, was found to be associated with expression of Rac1b, a tumorigenic splice isoform of Rac1, in all stages of pancreatic cancer. Using a large cohort of human PDA tissue biopsies specimens, both MMP3 and Rac1b are expressed in PDA cells, that the expression levels of the two markers are highly correlated, and that the subcellular distribution of Rac1b in PDA is significantly associated with patient outcome. Using transgenic mouse models, coexpression of MMP3 with activated KRAS in pancreatic acinar cells stimulates metaplasia and immune cell infiltration, priming the stromal microenvironment for early tumor development. Finally, exposure of cultured pancreatic cancer cells to recombinant MMP3 stimulates expression of Rac1b, increases cellular invasiveness, and activation of tumorigenic transcriptional profiles. Implications: MMP3 acts as a coconspirator of oncogenic KRAS in pancreatic cancer tumorigenesis and progression, both through Rac1b-mediated phenotypic control of pancreatic cancer cells themselves, and by giving rise to the tumorigenic microenvironment; these findings also point to inhibition of this pathway as a potential therapeutic strategy for pancreatic cancer. Mol Cancer Res; 12(10); 1430–9. ©2014 AACR.

Abstract The presence of regulatory T cells (Treg) in solid tumors is known to play a role in patient survival in ovarian cancer and other malignancies. We assessed inherited genetic variations via 749 tag single-nucleotide polymorphisms (SNP) in 25 Treg-associated genes (CD28, CTLA4, FOXP3, IDO1, IL10, IL10RA, IL15, 1L17RA, IL23A, IL23R, IL2RA, IL6, IL6R, IL8, LGALS1, LGALS9, MAP3K8, STAT5A, STAT5B, TGFB1, TGFB2, TGFB3, TGFBR1, TGRBR2, and TGFBR3) in relation to ovarian cancer survival. We analyzed genotype and overall survival in 10,084 women with invasive epithelial ovarian cancer, including 5,248 high-grade serous, 1,452 endometrioid, 795 clear cell, and 661 mucinous carcinoma cases of European descent across 28 studies from the Ovarian Cancer Association Consortium (OCAC). The strongest associations were found for endometrioid carcinoma and IL2RA SNPs rs11256497 [HR, 1.42; 95% confidence interval (CI), 1.22–1.64; P = 5.7 × 10−6], rs791587 (HR, 1.36; 95% CI, 1.17–1.57; P = 6.2 × 10−5), rs2476491 (HR, = 1.40; 95% CI, 1.19–1.64; P = 5.6 × 10−5), and rs10795763 (HR, 1.35; 95% CI, 1.17–1.57; P = 7.9 × 10−5), and for clear cell carcinoma and CTLA4 SNP rs231775 (HR, 0.67; 95% CI, 0.54–0.82; P = 9.3 × 10−5) after adjustment for age, study site, population stratification, stage, grade, and oral contraceptive use. The rs231775 allele associated with improved survival in our study also results in an amino acid change in CTLA4 and previously has been reported to be associated with autoimmune conditions. Thus, we found evidence that SNPs in genes related to Tregs seem to play a role in ovarian cancer survival, particularly in patients with clear cell and endometrioid epithelial ovarian cancer. Cancer Immunol Res; 2(4); 332–40. ©2014 AACR.

Abstract Purpose: Ovarian cancer has a high recurrence and mortality rate. A barrier to improved outcomes includes a lack of accurate models for preclinical testing of novel therapeutics. Experimental Design: Clinically relevant, patient-derived tumorgraft models were generated from sequential patients and the first 168 engrafted models are described. Fresh ovarian, primary peritoneal, and fallopian tube carcinomas were collected at the time of debulking surgery and injected intraperitoneally into severe combined immunodeficient mice. Results: Tumorgrafts demonstrated a 74% engraftment rate with microscopic fidelity of primary tumor characteristics. Low-passage tumorgrafts also showed comparable genomic aberrations with the corresponding primary tumor and exhibit gene set enrichment of multiple ovarian cancer molecular subtypes, similar to patient tumors. Importantly, each of these tumorgraft models is annotated with clinical data and for those that have been tested, response to platinum chemotherapy correlates with the source patient. Conclusions: Presented herein is the largest known living tumor bank of patient-derived, ovarian tumorgraft models that can be applied to the development of personalized cancer treatment. Clin Cancer Res; 20(5); 1288–97. ©2014 AACR.

Abstract Ovarian cancer is a clinically and molecularly heterogeneous disease. The driving forces behind this variability are unknown. Here, we report wide variation in the expression of the DNA cytosine deaminase APOBEC3B, with elevated expression in the majority of ovarian cancer cell lines (three SDs above the mean of normal ovarian surface epithelial cells) and high-grade primary ovarian cancers. APOBEC3B is active in the nucleus of several ovarian cancer cell lines and elicits a biochemical preference for deamination of cytosines in 5′-TC dinucleotides. Importantly, examination of whole-genome sequence from 16 ovarian cancers reveals that APOBEC3B expression correlates with total mutation load as well as elevated levels of transversion mutations. In particular, high APOBEC3B expression correlates with C-to-A and C-to-G transversion mutations within 5′-TC dinucleotide motifs in early-stage high-grade serous ovarian cancer genomes, suggesting that APOBEC3B-catalyzed genomic uracil lesions are further processed by downstream DNA "repair" enzymes including error-prone translesion polymerases. These data identify a potential role for APOBEC3B in serous ovarian cancer genomic instability. Cancer Res; 73(24); 7222–31. ©2013 AACR.

Abstract Background: Pancreatic cancer is a devastating disease for which the role of dietary factors remains inconclusive. The study objective was to evaluate risk of pancreatic cancer associated with meat preparation methods and meat-related mutagen consumption using a clinic-based case–control design. Methods: There were 384 cases and 983 controls; subjects provided demographic information and completed a 144-item food frequency questionnaire, which was used to estimate meat mutagen intake using the National Cancer Institute's CHARRED database (Bethesda, MD). Logistic regression was used to calculate ORs and 95% confidence intervals (CI), adjusted for factors including age, sex, cigarette smoking, body mass index, and diabetes mellitus. Results: Overall, the findings were null with respect to meat mutagen intake and pancreatic cancer. Conclusions: The results do not support an association between well-done meat or meat-related mutagen intake and pancreatic cancer and contrast with generally increased risks reported in previous studies. Impact: These data contribute to evidence about pancreatic cancer and potentially carcinogenic compounds in meat. Cancer Epidemiol Biomarkers Prev; 22(7); 1336–9. ©2013 AACR.

Abstract Background: Based upon preclinical synergy and prior phase 1 study results, the clinical efficacy of flavopiridol combined with cisplatin was assessed in patients with recurrent ovarian and primary peritoneal cancers. Methods: A two cohort phase 2 trial of cisplatin (60 mg/m2 IV) followed by flavopiridol (100 mg/m2 IV, 24 h continuous infusion; 21 day cycles) was undertaken in patients with recurrent platin-sensitive or platin-resistant ovarian/primary peritoneal cancers (defined by disease progression > vs. <6 months following platin-based therapy). Measurable disease (RECIST criteria) – or evaluable disease plus CA125 >2X the post-treatment nadir – was required, as was ECOG performance <2 and exposure to only one prior treatment regimen. Results: Forty-five patients were enrolled between April 20, 2004 and March 4, 2010 – 40 platin-resistant patients (Group 1), and 5 platin-sensitive patients (Group 2). In Group 1, the median number of treatment cycles was 3 (range 2-12); 39 of the 40 eligible patients have now discontinued treatment. While only 10% of all patients incurred grade 4 toxicities, grade 3 toxicities were seen in the majority (65%). The most frequent grade 3 and 4 toxicities were neutropenia (all grade 3, 17.5%); nausea (12.5%); vomiting, fatigue, thrombosis, anemia (10% each). Sensory neuropathy, grade 1 or 2, was observed in 75% of all patients – with grade 3 and 4 neuropathy not observed primarily due to pre-specified aggressive dose reductions. Six patients (15%) in Group 1 achieved a confirmed response (1 CR, 5 PR), with a median response duration of 119 days (range 84-212). Ten additional Group 1 patients (32.5%) experienced maintained stable disease. Median Group 1 overall time to progression was 3.7 months; overall survival was 17.2 months. Pilot assessment of attained ascites flavopiridol level and sensitivity of patient ascitic tumor cells to flavopiridol confirmed that patient flavopiridol levels were consistent with observed clinical antitumor efficacy. In Group 2, although 2 of 5 patients also responded (40%; 2 PR), the cohort was closed due to poor accrual. Conclusions: The combination of flavopiridol and cisplatin has promising clinical activity in both platin-sensitive and platin-resistant ovarian and primary peritoneal cancers. Supported in part by NCI CA097129, CA15083 and CM62205; clinicaltrials.gov identifier NCT00083122 Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4712. doi:10.1158/1538-7445.AM2011-4712

Abstract Background: The role of dietary fruit, vegetable, fiber, and whole grain intake is implicated as a potential protective factor against pancreatic cancer, but studies are inconsistent. A possible explanation for the variability is that individuals who carry constitutional metabolism gene variants (minor alleles) may differentially benefit compared to those who are homozygous for the major allele, which over a life-time could lead to altered pancreatic cancer risk. Methods: We genotyped 70 SNPs that tag ten candidate metabolism genes (CAT, GAA, GCK, MT1E, UGT1A6, UGT1A7, UGT1A8, UGT1A9, UGT2B4, and UGT2B7) involved in the metabolism of components of fruits, vegetables, fibers, and whole grains to test if differential associations exist with pancreatic adenocarcinoma. We used a clinic-based case-control design, excluding participants who reported changing their diet within 5 years prior to entering the study. Three hundred eighty-four rapidly ascertained cases and nine hundred eighty-three non-cases from a primary care clinic (frequency matched on age at recruitment (+ 5 years), race, sex, and region of residence) provided blood samples for DNA and completed epidemiologic surveys plus a 144-item food frequency questionnaire developed by the National Cancer Institute. We used a dominant model to code SNPs and split dietary intake categories based on the sex-specific median intake level among non-cases. Logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals, adjusted for age, sex, family-history of pancreatic cancer, smoking (never/ former/ current), body mass index, energy intake, and alcohol consumption. The reference group was defined as carriers of no minor alleles in the lowest intake category. Results: The greatest benefit was observed for carriers of no minor alleles, for rs11032702 (CAT) with higher insoluble dietary fiber intake (OR [95%CI]: 0.515 [0.37, 0.71]); for rs735670 (GCK) with higher soluble dietary intake (0.473 [0.34, 0.67]); for rs2070971 (GCK) and rs2268569 (GCK) with higher fruit intake not from citrus, melon, and berries (0.513 [0.36, 0.73] and 0.554 [0.40, 0.78]); and for rs17832252 (GCK) with higher whole grain intake (0.530 [0.37, 0.76]); all comparisons had a reference group of no minor alleles with low dietary intake and a p-value for interaction <0.001. Conclusions: Inter-individual variation in metabolism of fruits, vegetables, fiber, and whole grain via metabolism gene variants may influence pancreatic cancer risk. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3749. doi:10.1158/1538-7445.AM2011-3749