Basal cell adhesion molecule promotes metastasis‐associated processes in ovarian cancer

Abstract

Background Basal cell adhesion molecule (BCAM) is a laminin α5 (LAMA5) binding membrane‐bound protein with a putative role in cancer. Besides full‐length BCAM1, an isoform lacking most of the cytoplasmic domain (BCAM2), and a soluble form (sBCAM) of unknown function are known. In ovarian carcinoma (OC), all BCAM forms are abundant and associated with poor survival, yet BCAM's contribution to peritoneal metastatic spread remains enigmatic. Methods Biochemical, omics‐based and real‐time cell assays were employed to identify the source of sBCAM and metastasis‐related functions of different BCAM forms. OC cells, explanted omentum and a mouse model of peritoneal colonisation were used in loss‐ and gain‐of‐function experiments. Results We identified ADAM10 as a major BCAM sheddase produced by OC cells and identified proteolytic cleavage sites proximal to the transmembrane domain. Recombinant soluble BCAM inhibited single‐cell adhesion and migration identically to membrane‐bound isoforms, confirming its biological activity in OC. Intriguingly, this seemingly anti‐tumorigenic potential of BCAM contrasts with a novel pro‐metastatic function discovered in the present study. Thus, all queried BCAM forms decreased the compactness of tumour cell spheroids by inhibiting LAMA5 – integrin β1 interactions, promoted spheroid dispersion in a three‐dimensional collagen matrix, induced clearance of mesothelial cells at spheroid attachment sites in vitro and enhanced invasion of spheroids into omental tissue both ex vivo and in vivo. Conclusions Membrane‐bound BCAM as well as sBCAM shed by ADAM10 act as decoys rather than signalling receptors to modulate metastasis‐related functions. While BCAM appears to have tumour‐suppressive effects on single cells, it promotes the dispersion of OC cell spheroids by regulating LAMA5‐integrin‐β1‐dependent compaction and thereby facilitating invasion of metastatic target sites. As peritoneal dissemination is majorly mediated by spheroids, these findings offer an explanation for the association of BCAM with a poor clinical outcome of OC, suggesting novel therapeutic options.

Machine Learning-Enhanced Extraction of Biomarkers for High-Grade Serous Ovarian Cancer from Proteomics Data

“…A recent study reports that the dysregulation of MSLN in serum and tissue acts as a promising diagnostic biomarker for gastric cancer 42 . Basal cell adhesion molecule (BCAM) is another important protein reported in ovarian cancer playing a key role in the metastasis process 43 , 44 and immune suppression 45 . The recurrent BCAM-AKT2 fusion gene leads to activated AKT2 function kinase in HGSOC compared to the healthy 46 .…”

Reciprocal crosstalk between Th17 and mesothelial cells promotes metastasis‐associated adhesion of ovarian cancer cells

“…Omenta were stimulated with 30 ng/mL rmIL‐17A (210‐17, Peprotech, Cranbury, USA) and 10 ng/mL rmTNF (12343014, ImmunoTools, Friesoythe, Germany). The culture was carried out under hypoxic conditions 42 for 24 h at 37°C and 2% O2, 93% N 2 and 5% CO 2 as described 41 . Whole mount staining of the omentum was performed based as published 41,43 .…”

“…The culture was carried out under hypoxic conditions 42 for 24 h at 37°C and 2% O2, 93% N 2 and 5% CO 2 as described. 41 Whole mount staining of the omentum was performed based as published. 41 , 43 The following antibodies were used: anti‐CD45‐APC (559864, BD Biosciences, Franklin Lakes, USA); anti‐CD31‐PE (553373, BD Biosciences, Franklin Lakes, USA); anti‐ZO‐1‐AlexaFluor 488 (339188, Invitrogen, Waltham, USA); anti‐VCAM‐1‐V450 (105772, Biolegend, San Diego, USA).…”

“… 41 Whole mount staining of the omentum was performed based as published. 41 , 43 The following antibodies were used: anti‐CD45‐APC (559864, BD Biosciences, Franklin Lakes, USA); anti‐CD31‐PE (553373, BD Biosciences, Franklin Lakes, USA); anti‐ZO‐1‐AlexaFluor 488 (339188, Invitrogen, Waltham, USA); anti‐VCAM‐1‐V450 (105772, Biolegend, San Diego, USA). Fluorescence microscopy was performed on an Olympus FVMPE‐RS Multiphoton Microscope.…”

“…The protocol of Khan et al 40 was applied with some modifications. 41 C57BL/6 mice were sacrificed by cervical dislocation and the omentum together with the pancreas and spleen were separated en bloc from the gastrointestinal tract, removed and placed in a beaker filled with ice-cold PBS, where the pancreas and spleen remained at the bottom of the beaker, while the fat-rich omentum floated at the top. The omentum was separated from the surrounding organs by trimming its base, and was fixed on a Millicell culture insert using Cell-Tak Cell and Tissue Adhesive (Corning, #10317081).…”