Decoding the Tumour Microenvironment: Molecular Players, Pathways, and Therapeutic Targets in Cancer Treatment

Simple Summary Tumour cells are not independent entities but are always surrounded by different types of non-tumoural cells and other extracellular components, which together constitute a complex association known as the tumour microenvironment. Cancer cells and non-tumoural cells can influence each other in several ways that contribute to sustaining tumour growth and development. This complex crosstalk is mediated by a plethora of different molecules and pathways that, in the context of cancer, are dysregulated and altered. In this work, we reviewed the latest update regarding some of the molecules and pathways involved in the tumour microenvironment and their role in mediating tumour progression.Abstract The tumour microenvironment (TME) is a complex and constantly evolving collection of cells and extracellular components. Cancer cells and the surrounding environment influence each other through different types of processes. Characteristics of the TME include abnormal vasculature, altered extracellular matrix, cancer-associated fibroblast and macrophages, immune cells, and secreted factors. Within these components, several molecules and pathways are altered and take part in the support of the tumour. Epigenetic regulation, kinases, phosphatases, metabolic regulators, and hormones are some of the players that influence and contribute to shaping the tumour and the TME. All these characteristics contribute significantly to cancer progression, metastasis, and immune escape, and may be the target for new approaches for cancer treatment.