Immunobiology of human mucin 1 in a preclinical ovarian tumor model

Abstract

Epithelial ovarian cancer is an aggressive malignancy, with a low 5-year median survival. Continued improvement on the development of more effective therapies depends in part on the availability of adequate preclinical models for in vivo testing of treatment efficacy. Mucin 1 (MUC1) glycoprotein is a tumor-associated antigen overexpressed in ovarian cancer cells, making it a potential target for immune therapy. To create a preclinical mouse model for MUC1-positive ovarian tumors, we generated triple transgenic (Tg) mice that heterozygously express human MUC1+/− as a transgene, and carry the conditional K-rasG12D oncoallele (loxP-Stop-loxP-K-rasG12D/+) and the floxed Pten gene (Pten/loxP/loxP). Injection of Cre recombinase-encoding adenovirus (AdCre) in the ovarian bursa of triple (MUC1KrasPten) Tg mice triggers ovarian tumors that, in analogy to human ovarian cancer, express strongly elevated MUC1 levels. The tumors metastasize loco-regionally and are accompanied by high serum MUC1, closely mimicking the human disease. Compared with the KrasPten mice with tumors, the MUC1KrasPten mice show increased loco-regional metastasis and augmented accumulation of CD4+Foxp3+ immune-suppressive regulatory T cells. Vaccination of MUC1KrasPten mice with type 1 polarized dendritic cells (DC1) loaded with a MUC1 peptide (DC1–MUC1) can circumvent tumor-mediated immune suppression in the host, activate multiple immune effector genes and effectively prolong survival. Our studies report the first human MUC1-expressing, orthotopic ovarian tumor model, reveal novel MUC1 functions in ovarian cancer biology and demonstrate its suitability as a target for immune-based therapies.

Complement Pathway Is Frequently Altered in Endometriosis and Endometriosis-Associated Ovarian Cancer

“…The mouse tumors show similarly increased epithelial cell expression of complement proteins (Fig. 4A), further demonstrating that the MUC1KrasPten mouse model, which replicates with high fidelity the histopathology of human EAOC (21, 28), may also provide an useful preclinical tool for exploring the complement biology in the ovarian tumor microenvironment.…”

“…To accomplish this, we employed ovarian surface epithelial cells derived from triple transgenic mice that progress to human mucin 1 (MUC1) - expressing endometrioid ovarian cancer that closely mirrors the human disease (21). The mice heterozygously express human MUC1 as a transgene, and simultaneously carry the conditional LoxP-Stop-LoxP K-ras G12D oncoallele and the floxed Pten loxP/loxP gene (28).…”

“…The mice heterozygously express human MUC1 as a transgene, and simultaneously carry the conditional LoxP-Stop-LoxP K-ras G12D oncoallele and the floxed Pten loxP/loxP gene (28). In this Cre-loxP in vivo system, injection of Cre recombinase encoding adenovirus (AdCre) under the ovarian bursa of female MKP mice triggers progression to endometrioid ovarian tumors in about 7–8 weeks (21). The mouse tumors show similarly increased epithelial cell expression of complement proteins (Fig.…”

“…MKPOSE cells were derived in Anda Vlad’s laboratory at Magee Womens Research Institute, from primary ovarian surface epithelial (OSE) cells isolated from healthy MKP mice (21) via gentle trypsinization of six ovaries collected at necropsy from three healthy female mice according to previously published protocols (22) and as further detailed in Supplementary Materials and Methods. Authentication was performed through genomic PCR of MKPOSE cells for the presence of loxP cassettes at the (murine-specific) Kras and Pten loci before and after AdCre infection, as shown in Supplementary Fig.…”

Chronic inflammation in endometriosis and endometriosis-associated ovarian cancer: New roles for the “old” complement pathway

“…To further explore this mechanism, we employed triple transgenic mice that progress to EAOC closely mirroring the human disease. 6,7 Using this preclinical model, we demonstrated that complement upregulation in epithelial cells occurs early in carcinogenesis.…”