Single-cell allelic transcriptomic analysis unravels intratumoral gene expression heterogeneity linked to TNBC pathogenesis
Triple-negative breast cancer (TNBC) is the most aggressive subclass of breast cancer, which exhibits high intratumoral heterogeneity. Intratumoral heterogeneity often drives the evolution of drug resistance towards tumour therapy in TNBC. However, the contributing factors and mechanisms behind the intratumoral heterogeneity in TNBC remain poorly understood. It has been implicated that copy number variations (CNVs) often create allelic imbalance and thereby contribute to intratumoral gene expression heterogeneity. However, other processes, such as epigenetic and transcriptional processes, can also contribute to allelic expression heterogeneity in tumour cells. Here, we have investigated how allelic expression heterogeneity contributes to intratumoral heterogeneity in TNBC by performing genome-wide allelic gene expression analysis, excluding most of the CNVs, using single-cell RNA-sequencing datasets. We found widespread monoallelic expression of many genes across different cell types o