Faculty Bibliography

A highly sensitive microfluidic system to capture circulating tumor cells from whole blood of cancer patients is presented. The device incorporates graphene oxide into a thermoresponsive polymer film to serve as the first step of an antibody functionalization chemistry. By decreasing the temperature, captured cells may be released for subsequent analysis.

Pancreatic cancer is an aggressive cancer that continues to have single-digit 5-year mortality rates despite advancements in the field. Surgery remains the only curative treatment; however, most patients present with late-stage disease deemed unresectable, either due to extensive local vascular involvement or the presence of distant metastasis. Resection guidelines that include a borderline resectable group, as well as advancements in neoadjuvant chemotherapy and radiation that improve resectability of locally advanced disease, may improve outcomes for patients with more invasive disease. Multi-agent chemotherapy regimens fluorouracil, leucovorin, irinotecan, and oxaliplatin (FOLFIRINOX) and nab-paclitaxel with gemcitabine improved response rates and survival in metastatic pancreatic cancer and are now being used in earlier stages for patients with localized potentially resectable and unresectable disease, with goals of downstaging tumors to allow margin-negative resection and reducing systemic recurrence. Chemoradiotherapy, although still controversial for both resectable and unresectable pancreatic cancer, is being used in the context of contemporary chemotherapy backbone regimens, and novel radiation techniques such as stereotactic body frame radiation therapy (SBRT) are studied on the premise of maintaining or improving efficacy and reducing treatment duration. Patient selection for optimal treatment designation is currently provided by multidisciplinary tumor boards, but biomarker discovery, in blood, tumors, or through novel imaging, is an area of intense research. Results to date suggest that some patients with unresectable disease at the outset have survival rates as good as those with initially resectable disease if able to undergo surgical resection. Long-term follow-up and improved clinical trials options are needed to determine optimal treatment modalities for patients with localized pancreatic cancer.

Molecular indicators to specify the risk posed by a pancreatic cyst would benefit patients. Previously we showed that most cancer-precursor cysts, termed mucinous cysts, produce abnormal glycoforms of the proteins MUC5AC and endorepellin. Here we sought to validate the glycoforms as a biomarker of mucinous cysts and to specify the oligosaccharide linkages that characterize MUC5AC. We hypothesized that mucinous cysts secrete MUC5AC displaying terminal N-acetylglucosamine (GlcNAc) in either alpha or beta linkage. We used antibody-lectin sandwich assays to detect glycoforms of MUC5AC and endorepellin in cyst fluid samples from three independent cohorts of 49, 32, and 66 patients, and we used monoclonal antibodies to test for terminal, alpha-linked GlcNAc and the enzyme that produces it. A biomarker panel comprising the previously-identified glycoforms of MUC5AC and endorepellin gave 96%, 96%, and 87% accuracy for identifying mucinous cysts in the three cohorts with an average sensitivity of 92% and an average specificity of 94%. Glycan analysis showed that MUC5AC produced by a subset of mucinous cysts displays terminal alpha-GlcNAc, a motif expressed in stomach glands. The alpha-linked glycoform of MUC5AC was unique to intraductal papillary mucinous neoplasms (IPMN), whereas terminal beta-linked GlcNAc was increased in both IPMNs and mucinous cystic neoplasms (MCN). The enzyme that synthesizes alpha-GlcNAc, A4GNT, was expressed in the epithelia of mucinous cysts that expressed alpha-GlcNAc, especially in regions with high-grade dysplasia. Thus IPMNs secrete a gastric glycoform of MUC5AC that displays terminal alpha-GlcNAc, and the combined alpha-GlcNAc and beta-GlcNAc glycoforms form an accurate biomarker of mucinous cysts.

Bladder cancer is a common and deadly malignancy but its treatment has advanced little over the last twenty years because the biologic drivers are incompletely understood. Ataxia-Telangiectasia Group D Complementing (ATDC; also named TRIM29) is highly expressed in many lethal tumor types including bladder, pancreatic and lung, but whether it is sufficient to drive tumor formation was unknown. Here we show that overexpression of ATDC in vivo is sufficient to drive both non-invasive and invasive bladder carcinoma development in transgenic animals. ATDC-driven bladder tumors were indistinguishable from and had a similar gene expression signature to human bladder cancers. ATDC was highly expressed in human bladder cancers, marked invasive tumors, mediated proliferation, invasion and tumor growth in vivo. ATDC expression drove suppression of miR-29, which resulted in upregulation of DNMT3A and subsequent DNA methylation and silencing of the tumor suppressor PTEN. ATDC-mediated suppression of PTEN promoted both invasion and proliferation. These results identify ATDC as a driver of both noninvasive and invasive bladder cancer formation and establish the importance of ATDC in human disease. Given its ubiquity and importance in human bladder cancer, these results implicate ATDC as a potential biomarker and therapeutic target for a disease with limited therapeutic options.

Induction of DNA damage by ionizing radiation (IR) and/or cytotoxic chemotherapy is an essential component of cancer therapy. The ataxia telangiectasia group D complementing gene (ATDC, also called TRIM29) is highly expressed in many malignancies. It participates in the DNA damage response downstream of ataxia telangiectasia-mutated (ATM) and p38/MK2 and promotes cell survival after IR. To elucidate the downstream mechanisms of ATDC-induced IR protection, we performed a mass spectrometry screen to identify ATDC binding partners. We identified a direct physical interaction between ATDC and the E3 ubiquitin ligase and DNA damage response protein, RNF8, which is required for ATDC-induced radioresistance. This interaction was refined to the C-terminal portion (amino acids 348-588) of ATDC and the RING domain of RNF8 and was disrupted by mutation of ATDC Ser-550 to alanine. Mutations disrupting this interaction abrogated ATDC-induced radioresistance. The interaction between RNF8 and ATDC, which was increased by IR, also promoted downstream DNA damage responses such as IR-induced gamma-H2AX ubiquitination, 53BP1 phosphorylation, and subsequent resolution of the DNA damage foci. These studies define a novel function for ATDC in the RNF8-mediated DNA damage response and implicate RNF8 binding as a key determinant of the radioprotective function of ATDC.

Pancreatic cancer (PC) is estimated to become the second leading cause of cancer death in the United States by 2020. Early detection is the key to improving survival in PC. Addressing this urgent need, the Kenner Family Research Fund conducted the inaugural Early Detection of Sporadic Pancreatic Cancer Summit Conference in 2014 in conjunction with the 45th Anniversary Meeting of the American Pancreatic Association and Japan Pancreas Society. This seminal convening of international representatives from science, practice, and clinical research was designed to facilitate challenging interdisciplinary conversations to generate innovative ideas leading to the creation of a defined collaborative strategic pathway for the future of the field. An in-depth summary of current efforts in the field, analysis of gaps in specific areas of expertise, and challenges that exist in early detection is presented within distinct areas of inquiry: Case for Early Detection: Definitions, Detection, Survival, and Challenges; Biomarkers for Early Detection; Imaging; and Collaborative Studies. In addition, an overview of efforts in familial PC is presented in an addendum to this article. It is clear from the summit deliberations that only strategically designed collaboration among investigators, institutions, and funders will lead to significant progress in early detection of sporadic PC.

Epigenetic dysregulation is involved in the initiation and progression of many epithelial cancers. BMI1, a component of the polycomb protein family, plays a key role in these processes by controlling the histone ubiquitination and long-term repression of multiple genomic loci. BMI1 has previously been implicated in pancreatic homeostasis and the function of pancreatic cancer stem cells. However, no work has yet addressed its role in the early stages of pancreatic cancer development. Here, we show that BMI1 is required for the initiation of murine pancreatic neoplasia using a novel conditional knockout of Bmi1 in combination with a Kras(G12D)-driven pancreatic cancer mouse model. We also demonstrate that the requirement for Bmi1 in pancreatic carcinogenesis is independent of the Ink4a/Arf locus and at least partially mediated by dysregulation of reactive oxygen species. Our data provide new evidence of the importance of this epigenetic regulator in the genesis of pancreatic cancer.

Glycosylation has significant effects on protein function and cell metastasis, which are important in cancer progression. It is of great interest to identify site-specific glycosylation in search of potential cancer biomarkers. However, the abundance of glycopeptides is low compared to that of nonglycopeptides after trypsin digestion of serum samples, and the mass spectrometric signals of glycopeptides are often masked by coeluting nonglycopeptides due to low ionization efficiency. Selective enrichment of glycopeptides from complex serum samples is essential for mass spectrometry (MS)-based analysis. Herein, a strategy has been optimized using LCA enrichment to improve the identification of core-fucosylation (CF) sites in serum of pancreatic cancer patients. The optimized strategy was then applied to analyze CF glycopeptide sites in 13 sets of serum samples from pancreatic cancer, chronic pancreatitis, healthy controls, and a standard reference. In total, 630 core-fucosylation sites were identified from 322 CF proteins in pancreatic cancer patient serum using an Orbitrap Elite mass spectrometer. Further data analysis revealed that 8 CF peptides exhibited a significant difference between pancreatic cancer and other controls, which may be potential diagnostic biomarkers for pancreatic cancer.

The initiation of pancreatic ductal adenocarcinoma (PDA) is linked to activating mutations in KRAS. However, in PDA mouse models, expression of oncogenic mutant KRAS during development gives rise to tumors only after a prolonged latency or following induction of pancreatitis. Here we describe a novel mouse model expressing ataxia telangiectasia group D complementing gene (ATDC, also known as TRIM29 [tripartite motif 29]) that, in the presence of oncogenic KRAS, accelerates pancreatic intraepithelial neoplasia (PanIN) formation and the development of invasive and metastatic cancers. We found that ATDC up-regulates CD44 in mouse and human PanIN lesions via activation of beta-catenin signaling, leading to the induction of an epithelial-to-mesenchymal transition (EMT) phenotype characterized by expression of Zeb1 and Snail1. We show that ATDC is up-regulated by oncogenic Kras in a subset of PanIN cells that are capable of invading the surrounding stroma. These results delineate a novel molecular pathway for EMT in pancreatic tumorigenesis, showing that ATDC is a proximal regulator of EMT.

Pancreatic cancer is one of the deadliest human malignancies due to its early metastatic spread and resistance to therapy. The mechanisms regulating pancreatic cancer metastasis are so far poorly understood. Here, using both in vitro and in vivo approaches, it is demonstrated that CD44, a transmembrane glycoprotein expressed on a subset of pancreatic cancer cells, is required for the induction of epithelial-mesenchymal transition (EMT) and the activation of an invasive program in pancreatic cancer. Mechanistically, the transcription factor Snail1 (SNAI1), a regulator of the EMT program, is a downstream target of CD44 in primary pancreatic cancer cells and regulates membrane bound metalloproteinase (MMP14/MT1-MMP) expression. In turn, MT1-MMP expression is required for pancreatic cancer invasion. Thus, these data establish the CD44-Snail-MMP axis as a key regulator of the EMT program and of invasion in pancreatic cancer. IMPLICATIONS: This study sets the stage for CD44 and MT1-MMP as therapeutic targets in pancreatic cancer, for which small molecule or biologic inhibitors are available. Visual Overview: http://mcr.aacrjournals.org/content/early/2014/09/10/1541-7786.MCR-14-0076/F1.lar ge.jpg.