BackgroundCancer cell aggregation is a key process involved in the formation of clusters of circulating tumor cells. We previously reported that cell-cell adhesion proteins, such as E-cadherin, and desmosomal proteins are involved in cell aggregation to form clusters independently of cell migration or matrix adhesion. Here, we investigated the involvement of gap junction intercellular communication (GJIC) during anchorage-independent clustering of MCF7 breast adenocarcinoma cells.MethodsWe used live cell image acquisition and analysis to monitor the kinetics of MCF7 cell clustering in the presence/absence of GJIC pharmacological inhibitors and to screen a LOPAC® bioactive compound library. We also used a calcein transfer assay and flow cytometry to evaluate GJIC involvement in cancer cell clustering.ResultsWe first demonstrated that functional GJIC are established in the early phase of cancer cell aggregation. We then showed that pharmacological inhibition of GJIC using tonabersat and meclofenamate delayed MCF7 cell clustering and reduced calcein transfer. We also found that brefeldin A, an inhibitor of vesicular trafficking, which we identified by screening a small compound library, and latrunculin A, an actin cytoskeleton-disrupting agent, both impaired MCF7 cell clustering and calcein transfer.ConclusionsOur results demonstrate that GJIC are involved from the earliest stages of anchorage-independent cancer cell aggregation. They also give insights into the regulatory mechanisms that could modulate the formation of clusters of circulating tumor cells.Electronic supplementary materialThe online version of this article (10.1186/s12885-018-4148-5) contains supplementary material, which is available to authorized users.

Follicular lymphoma (FL) is an indolent B cell lymphoproliferative disorder of transformed follicular center B cells, which accounts for 20–30 percent of all non-Hodgkin lymphoma (NHL) cases. Great advances have been made to identify the most relevant targets for precision therapy. However, no relevant models for in vitro studies have been developed or characterized in depth. To this purpose, we generated a 3D cell model from t(14;18)-positive B-NHL cell lines cultured in ultra-low attachment 96-well plates. Morphological features and cell growth behavior were evaluated by classical microscopy (2D imaging) and response to treatment with different drugs was evaluated by a high-content analysis system to determine the robustness of the model. We show that the ultra-low attachment (ULA) method allows the development of regular, spherical and viable ULA-multicellular aggregates of lymphoma cells (MALC). However, discrepancies in the results obtained after 2D imaging analyses on drug-treated ULA-MALC prompted us to develop 3D imaging and specific analyses. We show by using light sheet microscopy and specifically developed 3D imaging algorithms that 3D imaging and dedicated analyses are necessary to characterize morphological properties of 3D models and drug effects. This study proposes a new method, but also imaging tools and informatic solutions, developed for FL necessary for future preclinical studies.