Pancreatic Ductal Adenocarcinoma Mice Lacking Mucin 1 Have a Profound Defect in Tumor Growth and Metastasis

Abstract

MUC1 is over expressed and aberrantly glycosolated in >60% of pancreatic ductal adenocarcinomas. The functional role of MUC1 in pancreatic cancer has yet to be fully elucidated due to a dearth of appropriate models. In the present study, we have generated mouse models that spontaneously develop pancreatic ductal adenocarcinoma (KC), which are either Muc1-null (KCKO) or express human MUC1 (KCM). We show that KCKO mice have significantly slower tumor progression and rates of secondary metastasis, compared to both KC and KCM. Cell lines derived from KCKO tumors have significantly lower tumorigenic capacity compared to cells from KCM tumors. Therefore, mice with KCKO tumors had a significant survival benefit compared to mice with KCM tumors. In vitro, KCKO cells have reduced proliferation and invasion and failed to respond to epidermal growth factor (EGF), platelet-derived growth factor (PDGF), or matrix metalloproteinase-9 (MMP9). Further, significantly fewer KCKO cells entered the G2M phase of the cell cycle compared to the KCM cells. Proteomics and western blotting analysis revealed a complete loss of cdc-25c expression, phosphorylation of MAPK, as well as a significant decrease in Nestin and Tubulin α-2 chain expression in KCKO cells. Treatment with a MEK1/2 inhibitor, U0126, abrogated the enhanced proliferation of the KCM cells but had minimal effect on KCKO cells, suggesting that MUC1 is necessary for MAPK activity and oncogenic signaling. This is the first study to utilize a Muc1-null PDA mouse in order to fully elucidate the oncogenic role of MUC1, both in vivo and in vitro.

Oncolytic Vesicular Stomatitis Virus in an Immunocompetent Model of MUC1-Positive or MUC1-Null Pancreatic Ductal Adenocarcinoma

“…Regardless of treatment, most KCKO tumors never grew as large as the KCM tumors. This observation is in agreement with previous studies in which mice bearing KCKO tumors present a less-challenging, more-stable form of PDA disease as the cells grow at a lower rate than the more aggressive KCM cells (7).…”

“…MUC1 is overexpressed and aberrantly glycosylated in more than 80% of human PDAs and in 100% of metastatic lesions (5). It not only plays an important role in development and progression of PDA and other cancers but also is a major marker of poor prognosis, and its expression often confers resistance of cancer cells to chemotherapeutics (7,8,11). In general, our data suggest that VSV is tolerant to the expression of MUC1, at least in the tested PDA cell lines.…”

“…We focused our initial experiment on mice bearing KCM tumors, given that MUC1-expressing tumors are more clinically relevant and more challenging. Previous comparative studies of KCM and KCKO cell lines in vitro and in vivo demonstrated that KCM cells display a much more aggressive phenotype, evidenced by an increase in invasiveness of KCM cells, an increase in proliferation, and deregulation of the mitogen-activated protein kinase (MAPK) pathway (7). The efficacy of VSV-⌬M51-GFP was compared to that of gemcitabine, the most common chemotherapeutic used against pancreatic cancer (46).…”

“…In a tumor setting, the membranetethered glycoprotein mucin 1 (MUC1) becomes overexpressed and aberrantly glycosylated in more than 80% of human PDAs and in 100% of metastatic lesions (5). MUC1 plays an important role in the development and progression of PDA and other cancers and is a major marker for poor prognosis (7)(8)(9)(10)(11). Importantly, while the role of MUC1 in vesicular stomatitis virus (VSV) infection or oncolytic virus (OV) therapy has never been studied before, the O-linked carbohydrates of MUC1 purified from human breast milk can inhibit poxvirus (12), HIV (13,14), and rotavirus (15), and MUC1 expression can block adeno-associated virus attachment (16).…”

Small-Molecule Inhibition of GCNT3 Disrupts Mucin Biosynthesis and Malignant Cellular Behaviors in Pancreatic Cancer

“…The mucins may prevent drugs from accessing their sites of action. The expression of several mucins, including MUC1, MUC4, MUC5AC, and MUC16, is highly upregulated in pancreatic ductal adenocarcinoma (PDAC), pancreatic intraepithelial neoplasia (PanIN), intrapapillary mucinous neoplasms, and mucinous cystic neoplasms from patients with pancreatic cancer (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18). The extent to which the dense mucin mesh influences the antiproliferative activity of 5-fluorouracil (5-FU) was investigated using human pancreatic cancer cells (2,3).…”