2018_02_Single cell RNA-seq highlights a role for a partial EMT in head and neck cancer (PubMed Link)
2019_12_Immunohistochemical quantification of partial-EMT in oral cavity squamous cell carcinoma primary tumors is associated with nodal metastasis (PubMed Link)
2020_11_Molecular margins in head and neck cancer- Current techniques and future directions (PubMed Link)
______________YHL Research Day Abstract Final______________
(Background) Partial epithelial-to-mesenchymal transition (p-EMT) is a molecularly pathologic feature revealed by single-cell RNA-seq and immunohistochemistry (IHC) studies of oral squamous cell carcinoma (OSCC) tissues comprising both primary and metastatic tumors. Compared with conventional EMT, tumor cells with the p-EMT program retain genes of epithelial origin (e.g. TP63, SPRR1B); express only partial mesenchymal (e.g. SNAI2) and extracellular matrix genes confined to the invasion front (e.g. PDPN, LAMB3, LAMC2). Quantitative IHC studies further demonstrated that p-EMT is an independent prognostic signature for nodal metastasis, which may aid in decision-making for an N0 neck dissection and/or adjuvant modalities.
(Aims) OC3 and TW2.6 are Taiwanese OSCC cell lines expressing distinct sets of EMT marker genes in cell culture, reminiscent of the EMT and p-EMT programs, respectively. In addition, we showed that TW2.6-derived xenograft tissues displayed prominent angiolymphatic- and perineural invasions that involve DDR1 kinase activity and CDH1 protein stability at the cell-cell junctions [Chen YL et al., Cancers, PMID: 32244515]. Here, by combining bulk RNA-seq analysis and IHC assay of OC3 and TW2.6-derived xenograft tissues, we aim to (1) validate genes and pathways attributable to the TW2.6 p-EMT program; (2) identify stromal cell subsets enriched in the TW2.6-CDX tissues; (3) associate p-EMT OSCC tissues with clinical outcomes.
(Results) As a whole, computational analyses using R limma, GSEA and DAVID consistently revealed that genes and cellular pathways related to the angiogenesis and immune processes are statistically enriched in the stroma of TW2.6-CDXs, compared to that of the OC3-group. In addition, CIBERSORTx and GSEA using custom gene matrix transposed files predicted that the two subsets of cancer-associated fibroblasts (CAFs), i.e. myofibroblastic (myCAF) and inflammatory (iCAF), are enriched in the OC3- and TW-2.6 stroma, respectively. To validate the bioinformatic data, IHC assays using Pecam1 (Cd31) and Adgre1 (F4/80) antibodies were conducted in each xenograft tissue. IHC results confirmed that (1) the microvascular densities of the TW2.6-CDX tissues are statistically higher than that of the OC3 group; (2) the major immune subsets in both OC3- and TW2.6 CDXs are macrophages. Interestingly, integrated correlational analyses of RNA-seq data suggested that certain immune related genes denoted in the CIBERSORTx might indeed originate from the iCAFs, including the expression of Cxcl1, Cxcl5, Cxcl9, Cxcl10, and Cxcl12. The clinical outcomes associated with p-EMT program of oral cancer specimens are under progress.
