Cell surface modification with ssDNA–PEG–lipid for analysing intercellular interactions between different cells

Intercellular interactions are important in the development, immune responses, and functions of tissues and organs. Few methods are currently available for experimentally inducing and analysing cell–cell interaction in vitro. Here I propose a method to induce cell–cell attachment by cell surface modification with single-stranded DNA (ssDNA) and poly(ethylene glycol)-conjugated phospholipid (PEG–lipid) derivatives. The incorporation of an ssDNA pair (polyA20 and polyT20) into the cell membranes of two different cells was utilized to attach distinct cells through DNA hybridization. This technique enabled induction of cell–cell attachment between the same cell lines or different cell lines by controlling the contact area of two cells. Using this method, I investigated intercellular interactions, including the cell-in-cell invasion process, without impairing the interaction. I found that the normal cells MCF-10A were internalized into the cancer cells MCF-7, and that the intercellular interactions between them mainly involved the interaction of E-cadherin.