Anti-Human CD9 Fab Fragment Antibody Blocks the Extracellular Vesicle-Mediated Increase in Malignancy of Colon Cancer Cells

Abstract

Intercellular communication between cancer cells themselves or with healthy cells in the tumor microenvironment and/or pre-metastatic sites plays an important role in cancer progression and metastasis. In addition to ligand–receptor signaling complexes, extracellular vesicles (EVs) are emerging as novel mediators of intercellular communication both in tissue homeostasis and in diseases such as cancer. EV-mediated transfer of molecular activities impacting morphological features and cell motility from highly metastatic SW620 cells to non-metastatic SW480 cells is a good in vitro example to illustrate the increased malignancy of colorectal cancer leading to its transformation and aggressive behavior. In an attempt to intercept the intercellular communication promoted by EVs, we recently developed a monovalent Fab fragment antibody directed against human CD9 tetraspanin and showed its effectiveness in blocking the internalization of melanoma cell-derived EVs and the nuclear transfer of their cargo proteins into recipient cells. Here, we employed the SW480/SW620 model to investigate the anti-cancer potential of the anti-CD9 Fab antibody. We first demonstrated that most EVs derived from SW620 cells contain CD9, making them potential targets. We then found that the anti-CD9 Fab antibody, but not the corresponding divalent antibody, prevented internalization of EVs from SW620 cells into SW480 cells, thereby inhibiting their phenotypic transformation, i.e., the change from a mesenchymal-like morphology to a rounded amoeboid-like shape with membrane blebbing, and thus preventing increased cell migration. Intercepting EV-mediated intercellular communication in the tumor niche with an anti-CD9 Fab antibody, combined with direct targeting of cancer cells, could lead to the development of new anti-cancer therapeutic strategies.

Novel Isolation Method Reveals Sex-Specific Composition and Neurotoxicity of Small Extracellular Vesicles in a Mouse Model of Alzheimer’s Disease

“…Unlike the protein cargo composition, the tetraspanin composition could provide a deeper insight into the fundamental differences between male and female EV heterogeneity. According to previous studies, CD63 and CD81 are commonly known markers for sEVs (especially exosomes), while CD9 tends to be a marker for both microvesicles/ectosomes and sEVs [ 31 , 32 ]. This could imply that either female EVs express higher levels of CD9 or a portion of the isolated sEVs are small microvesicles/ectosomes that are CD9(+).…”

Targeting of Tetraspanin CD81 with Monoclonal Antibodies and Small Molecules to Combat Cancers and Viral Diseases

“…Anti-CD81 mAbs are not yet in the clinic but there are anti-tetraspanin mAbs in early clinical development, such as the anti-CD37 BI 836826 currently developed in leukemia and lymphoma [ 168 , 169 ]. Interesting data have also been reported with anti-CD9 mAbs or Fab in leukemia [ 170 ] and in colon cancer [ 171 ]. These data augur well for the potential development of anti-CD81, probably as a second-line therapy in combination with targeted therapy as is the case for BI 836826.…”

Horizontal Transfer of Malignant Traits and the Involvement of Extracellular Vesicles in Metastasis

“…Regardless of the molecular mechanism, we have shown that the cancer cell transformation can be inhibited by the application of a Fab fragment derived from the anti-CD9 antibody, which prevents the uptake of EVs [ 123 , 124 ] ( Figure 1 A). Similarly, EVs containing annexin A6 released from pancreatic CAFs induced aggressiveness in pancreatic cancer [ 125 ], and CAFs were found to stimulate the migration ability of scirrhous-type gastric cancer cells [ 126 ].…”