Increased cholesterol biosynthesis identified as a key feature and a therapeutic target of cancer stem cells as revealed by proteomic comparison of clinical breast cancer tissue and corresponding patient-derived xenografts and mammospheres
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ABSTRACT: Cancer stem cells (CSCs) comprise a small subpopulation of undifferentiated cancer cells with the ability to self-renew and give rise to the heterogeneous cancer cell lineages that form tumorous masses. Thus, tumor eradication may be greatly improved by specifically targeting CSCs, as they exhibit resistance to conventional therapy. To gain insight into the unique biology of CSCs, we developed patient-derived xenograft (PDX) tumors from ER-negative breast cancer patient tissue from which we isolated mammospheres, a method known to enrich for cells with CSC-properties. An unbiased, comparative global proteomic analysis using label-free mass spectrometry was performed on the patient tumor tissues and corresponding PDX tumors and mammospheres. Good concordance between the proteome profiles of patient tumor tissue and corresponding PDX tumors was observed. However, lower abundance of immune- and extracellular matrix-related proteins and higher abundance of proteins associated with cell-to-cell adhesion including desmosome proteins and β-catenin were observed in PDX versus patient tumors. Interestingly, analysis of proteins elevated in mammospheres vs. PDX tumors identified an enrichment of proteins associated with de novo cholesterol synthesis. The clinical relevance of increased cholesterol biosynthesis protein expression was verified in a large gene expression data set of clinical breast cancers showing correlation with shorter relapse-free survival. RNA interference and chemical inhibition of the cholesterol biosynthesis pathway reduced mammosphere formation and growth of CSCs derived from PDX tumors and cancer cell lines. Our findings identify the cholesterol biosynthesis pathway as central for CSC growth and a potential therapeutic target for CSC as well as providing an additional mechanistic explanation for the observed benefit of statins in breast cancer treatment.
INSTRUMENT(S): Q Exactive
ORGANISM(S): Homo Sapiens (human)
TISSUE(S): Primary Cell
DISEASE(S): Breast Cancer
SUBMITTER: Brian Hood
LAB HEAD: Henrik J. Ditzel
PROVIDER: PXD011222 | Pride | 2019-07-02
REPOSITORIES: Pride
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