New Blocking Antibodies Impede Adhesion, Migration and Survival of Ovarian Cancer Cells, Highlighting MFGE8 as a Potential Therapeutic Target of Human Ovarian Carcinoma

Abstract

Milk Fat Globule – EGF – factor VIII (MFGE8), also called lactadherin, is a secreted protein, which binds extracellularly to phosphatidylserine and to αvβ3 and αvβ5 integrins. On human and mouse cells expressing these integrins, such as endothelial cells, phagocytes and some tumors, MFGE8/lactadherin has been shown to promote survival, epithelial to mesenchymal transition and phagocytosis. A protumoral function of MFGE8 has consequently been documented for a few types of human cancers, including melanoma, a subtype of breast cancers, and bladder carcinoma. Inhibiting the functions of MFGE8 could thus represent a new type of therapy for human cancers. Here, we show by immunohistochemistry on a collection of human ovarian cancers that MFGE8 is overexpressed in 45% of these tumors, and we confirm that it is specifically overexpressed in the triple-negative subtype of human breast cancers. We have established new in vitro assays to measure the effect of MFGE8 on survival, adhesion and migration of human ovarian and triple-negative breast cancer cell lines. Using these assays, we could identify new MFGE8-specific monoclonal antibodies, which efficiently blocked these three tumor-promoting effects of MFGE8. Our results suggest future use of MFGE8-blocking antibodies as new anti-cancer therapeutics in subgroups of ovarian carcinoma, and triple-negative breast carcinoma patients.

Immunoregulatory influence of abundant MFG‐E8 expression by esophageal cancer treated with chemotherapy

“…We examined MFG‐E8 expression in human esophageal squamous cell carcinoma using IHC staining and found that some of the cells abundantly express MFG‐E8, as shown in other types of cancer . As the IHC staining of the samples showed that the expression of MFG‐E8 was more abundant in cancer cells than in macrophages or other stromal cells, MFG‐E8 from cancer cells appears to play an important role in the tumor microenvironment.…”

“…Milk fat globule‐epidermal growth factor factor 8 is reported to be expressed in several types of human cancer cells, as well as immune‐related cells. Such expression has been found to be associated with tumor proliferation, epithelial‐mesenchymal transition, cell migration, M2 macrophage polarization, and the induction of Tregs . However, there are limited reports that clarified its prognostic impact on cancer patients .…”

In Vivo Genetic Screens of Patient-Derived Tumors Revealed Unexpected Frailty of the Transformed Phenotype

“…We showed that KMT2D silencing leads to inactivation of a subset of KMT2D-bound enhancers (reduced H3K4me1 and H3K27Ac) and downregulation of a subset of genes that are critical for cell migration, including MFGE8 and RPL39L . Downregulation of either gene in several cancer types, and in melanoma and breast carcinomas specifically, reduces cell migration, and their expression correlates with a more aggressive phenotype and unfavorable outcome in the patients (37)(38)(39). Notably, KMT2D target genes were the most proximal to the KMT2D-dependent enhancers, suggesting that KMT2D promotes tumorigenesis by deregulating enhancer activity.…”

Proteomic comparison defines novel markers to characterize heterogeneous populations of extracellular vesicle subtypes

“…CD14 + cells were enriched by magnetic sorting (Miltenyi Biotec) and cultured at 1-2 million cells per mL for 5 d in RPMI 1640 (Gibco) supplemented with 10% FCS (Biowest), 50 μM 2-ME, 10 mM Hepes, 100 IU/mL penicillin and 100 μg/mL streptomycin (Gibco) in the presence of IL-4 and GM-CSF (50 ng/mL and 100 ng/mL, respectively; Miltenyi Biotec). Cell lines HEK293T, RPE-1 (37), HeLa-CIITA (32), MDA-MB-231, SHIN, IGROV-1 (38), and OV2008 were cultured in DMEMglutamax (or RPMI-glutamax for IGROV-1) supplemented with 10% FCS (Lonza), 100 IU/mL penicillin, and 100 μg/mL streptomycin (Gibco).…”