Cell aggregation assays.

Invasion of carcinoma cells is the result of a disequilibrium between invasion promoter and invasion suppressor gene products (Mareel and Van Roy, Anticancer Res 6:419-435, 1986). The E-cadherin/catenin complex is the most potent invasion suppressor at the cell membrane of epithelioid cells (Duffy et al., J Pathol 214:283-293, 2008).

Opioids affect focal contact-mediated cell-substrate adhesion.

Earlier observations suggested that opioids modify cell-substrate adhesion on agar. In this study, we wanted to investigate whether opioids also interfere with cell adhesion to biologically relevant substrates, including interstitial matrix and basement membrane components. Human embryonic kidney 293 cells stably transfected with FLAG-tagged micro-opioid receptor were used as an experimental model.

Direct effects of delta opioid receptor agonists on invasion-associated activities of HCT-8/E11 colon cancer cells.

Background: Opioids and opioid receptors are an integral part of the tumour microenvironment and hence may influence tumour progression. Studies on direct effects of opioids on invasion-associated cellular activities are equivocal. We wanted to clarify these differences.

Cell aggregation on agar as an indicator for cell-matrix adhesion: effects of opioids.

The slow aggregation assay is generally used to study the functionality of cell-cell adhesion complexes. Single cells are seeded on a semisolid agar substrate in a 96-well plate and the cells spontaneously aggregate. We used HEK FLAG-MOP cells that stably overexpress the mu opioid receptor and the mu-opioid-receptor-selective agonists DAMGO and morphine to study whether other factors than functionality of cell-cell adhesions complexes can contribute to changes in the pattern of slow aggregation on agar.

Colon cancer cells: pro-invasive signalling.

Colon cancer results from erroneous renewal of the enteric epithelium. Mutations in stem cells, or their proliferative progenitors, cause accumulation of cells that invade into the stroma and continue to divide rather than migrating on top of the basement membrane prior to entering into apoptosis. Many of these changes in invasive activity appear to be related to the invasion-suppressor role of E-cadherin.