Objectives: The primary cilium (PC) associates with Bardet-Biedl family of proteins that form the BBSome complex and the PC may facilitate cell surface receptor engagement and trafficking. Environmental cues such as osmotic stress may be transmitted to the cell interior via the PC. The cellular lining of mesothelial cells of the pleura are subject to osmotic homoestasis. During malignant pleural effusions the pleural fluids have a hyperosmolar nature and in this stimulus the BBSome expression is  un-described. We describe the BBSome genes in 2D and 3D hanging drop  in-vitro models of hyperosmolality of 350mOsm (having an extra 50mOsm of BSA) as an osmotic stressor.

Methods: Synchronized benign mesothelial cells, MeT-5A, were cultured on 2D planar surfaces or in a hanging drop conformation using standard culture medium or media with 7.2% BSA for 24 hours. Cells were lysed for RNA processing and cDNA was prepared followed by qPCR quantitation with gene specific primers for BBS1, BBS2, BBS4, BBS5, BBS7, BBS9 and BBS18 and b-actin. Log 2 transformed 2^-??Ct values were compared to evaluate changes in gene expression.

Results:  In 2D with BSA stimulus BBS1 (Con mean±SEM;0.0±0.2, BSA 1.21±0.16, p<0.005) and BBS7 (Con;0.0±0.2, BSA 1.59±0.11, p<0.005) expression was significantly increased. There were no significant changes to any BBS genes in 3D with BSA stimulus. BBS 2, 4, 7, 9, 18 expression was observed but without significant change in both 2D and 3D.

Conclusions: BBS1 and BBS7 gene is significantly higher during BSA stimulus in cells attached to solid substratum. Expression patterns of some BBSome component genes were reversed between 2D and 3D cultured mesothelial cells.