Changes in expression of mesothelial BBS genes in 2D and 3D after lithium chloride and ammonium sulphate induction of primary cilium disturbance: a pilot study

Abstract

Background Malignant pleural mesothelioma (MPM), a rare and aggressive pleural tumor, has significant histological and molecular heterogeneity. Primary Cilium (PC), an organelle of emerging importance in malignancies, has been scarcely investigated in MPM. A critical molecular complex for the PC function is the BBSome and here we aimed at assessing its expression patterns in ordinary 2D and spheroid 3D cell cultures. Methods A human benign mesothelial cell line (MeT-5A), MPM cell lines (M14K, epithelioid MPM; MSTO, biphasic MPM), and primary MPM cells (pMPM) were used. Primers specific for the human BBS1, 2, 4, 5, 7, 9, 18 transcripts were designed, and quantitative real-time PCR (qRT-PCR) was done with β-actin as the gene of reference. The relative gene expression across 2D and 3D cultures was analyzed by the expression factor (mean of 1/ΔCt values). With the 2–∆∆Ct method the gene expression fold changes were assessed from qRT-PCR data. Molecular changes using the PC-modulating drugs ammonium sulfate (AS) and lithium chloride (LC) were also determined. Results PC was present in all cells used in the study at approximately 15% of the observed area. BBSome transcripts were differentially expressed in different dimensions of cell culture (2D vs. 3D) in all cell lines and pMPM. Treatment with AS and LC affected the expression of the ciliary BBS2 and BBS18 genes in the benign as well as in the MPM cells. Conclusions These data indicate distinct BBSome molecular profiles in human benign and MPM cells cultured in 2D and 3D dimensions and support the notion that PC genes should be investigated as potential MPM therapeutic targets.