The Cartilage Oligomeric Matrix Protein (COMP) Gene Is Associated with High-Grade Bladder Cancer and Promotes Bladder Cancer Cell Proliferation

Bladder cancer (BLCA) is a globally prevalent malignancy that poses a severe threat to patient health. Accurate high/low-grade classification of BLCA is critical for tailoring effective treatment strategies. This study integrated eight single-cell RNA sequencing (scRNA-seq) datasets and bulk RNA sequencing test from bladder tissues in our hospital, performing cell subpopulation annotation, differential gene expression analysis, and pathway enrichment analysis. Focusing on Cartilage Oligomeric Matrix Protein (COMP), we evaluated drug sensitivities and validated its functional role in BLCA using 5637 cell lines. Single-cell clustering identified distinct gene expression profiles between high/low-grade bladder epithelial cells, with the unfolded protein response pathway being most significantly enriched. Integrative analysis revealed COMP as a prognostic marker, positively correlated with 16 potential therapeutic drugs. In vitro experiments confirmed that COMP promotes BLCA cell proliferation. Our findings highlight COMP as an oncogenic driver in BLCA and provide drug targets for clinical translation. Overall design: This experimental design focuses on investigating bladder cancer, encompassing multiple interconnected research components. Firstly, tissue samples were collected from 8 bladder cancer patients (6 low-grade and 2 high-grade cases) for RNA sequencing (RNA-seq) to profile genome-wide gene expression, while 8 public single-cell RNA sequencing (scRNA-seq) datasets (2 low-grade and 6 high-grade) were re-analyzed to dissect cellular heterogeneity and cell-type-specific expression signatures. Secondly, hematoxylin and eosin (H&E) staining was used to assess histological features and pathological grading of the tissues, and immunohistochemical (IHC) staining with antibodies against GFAP, CK, SOX-10, P53, P16, Ki-67, and CD34 was conducted to evaluate phenotypic characteristics, proliferation status, tumor suppressor gene expression, vascularization, and lineage-specific markers of the tumors. Thirdly, public RNA-seq datasets were re-analyzed to perform survival analysis (including overall survival [OS] and progression-free survival [PFS]) and explore the association between COMP (Cartilage Oligomeric Matrix Protein) expression and clinical outcomes, so as to determine COMP's prognostic value. Additionally, gain-of-function (via COMP-overexpressing plasmid transfection) and loss-of-function (via RNA interference [RNAi] with COMP-targeting siRNAs) experiments were carried out to investigate COMP's biological role, with empty vectors and non-targeting siRNAs as negative controls respectively. Quantitative real-time polymerase chain reaction (qRT-PCR) was applied to quantify COMP expression in bladder cancer tissues, cell lines, and transfected cells, using glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as an internal reference gene for normalization. Finally, functional assays including colony formation assay (to evaluate clonogenic potential), Cell Counting Kit-8 (CCK-8) assay (to assess proliferative capacity by generating growth curves), and drug sensitivity analysis (to calculate half-maximal inhibitory concentration [IC50] values and evaluate changes in drug sensitivity) were performed to further explore the effects of COMP modulation on bladder cancer cells.