Figure 4

Gene expression of COL5A2, ITGAV, SPARC and ACTA2 correlated with mesenchymal phenotype in Epithelioid vs non-Epithelioid (biphasic and sarcomatoid) subtype in TCGA MESO database, and confirmation in our patients and cell lines. (A) The numbers of epithelioid subtype MPM patients (n = 62), biphasic and sarcomatoid subtypes (n = 23 and n = 2, respectively) were included. Gene expression of COL5A2, ITGAV, SPARC and ACTA2 (RNA expression in Transcripts Per Million-TPM) was observed to be significantly different between epithelioid and non-epithelioid subtypes in TCGA Cohort MESO (p < 0.05 for all comparisons). All genes had significantly higher mRNA expression in non-epithelioid than epithelioid subtypes as shown in violin graphs. (B) Malignant mesothelioma with dual phenotypes is likely an optimal model to study the EMT process and characterize epithelial cells changing their phenotypes into mesenchymal ones. Top graph shows the merged data of 4 genes’ expression in epithelioid, biphasic and sarcomatoid subtypes. Bottom diagram indicates the EMT plasticity is likely to mimic MESO subtypes. (C) In TCGA MESO cohort, gene expression of COL5A2, ITGAV, SPARC and ACTA2 correlated with the hallmark EMT gene set as shown in scatter plots. The expression of each gene was positively correlated with hallmark EMT regardless of tumor stage, all p values for each comparison are less than 0.05. The correlation curves became more significant along with tumor progression from stage 1–4. (D) The scRNA-Seq data from the biopsy specimens of naïve MESO patients, the patient (SMTR02T0) with biphasic subtype had highest expression of COL5A2, ITGAV, SPARC and ACTA2 genes compared with other cases who were confirmed to be epithelioid subtypes. Gene expression of COL5A2, ITGAV, SPARC and ACTA2 in epithelioid vs non-epithelioid subtype in MESO patients was shown in “Supplementary data” (“Supplementary data”, Fig. 4S). (E) Fluorescent immunostaining of human mesothelioma cell lines for COL5A2 and SPARC, showing that sarcomatoid CRL-5946 cells expressed COL5A2 and SPARC dramatically higher compared to epithelioid CRL-5915 cells, while CRL-5915 cells expressed little for either protein but expressed epithelial marker EpCAM specifically.