Decoding the Tumor Microenvironment: Insights and New Targets from Single-Cell Sequencing and Spatial Transcriptomics

The field of oncology has been extensively studied to design more effective and efficient treatments. This review explores the advanced techniques that are transforming our comprehension of cancer and its constituents. Specifically, it highlights the signaling pathways that drive tumor progression, angiogenesis, and resistance to therapy, as well as the modern approaches used to identify and characterize these pathways within the tumor microenvironment (TME). Key pathways discussed in this review include vascular endothelial growth factor (VEGF), programmed cell death protein 1/programmed cell death ligand 1 (PD-1/PD-L1), cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), and various extracellular matrix (ECM) pathways. Conventional methods of diagnosis have yielded sufficient knowledge but have failed to reveal the heterogeneity that exists within the TME, resulting in gaps in our understanding of the cellular interaction and spatial dynamics. Single-cell sequencing (SCS) and spatial transcriptomics (ST) are effective tools that can enable the dissection of the TME with the resolution capacity of a single cell. SCS allows the capture of the unique genetic and transcriptomic profiles of individual cells along with rare cell types and new therapeutic targets. ST complements this by providing a spatial map of gene expression, showing the gene expression profiles within the tumor tissue at specific sites with good accuracy. By mapping gene expression patterns at a single cell level and correlating them with the spatial locations, researchers can uncover the intricate networks and microenvironmental influences that contribute to tumor heterogeneity.