Long non-coding RNAs within the tumour microenvironment and their role in tumour-stroma cross-talk

Long non-coding RNAs (lncRNAs) are a diverse class of RNA transcripts which have limited protein coding potential. They perform a variety of cellular functions in health, but have also been implicated during malignant transformation. A further theme in recent years is the critical role of the tumour microenvironment and the dynamic interactions between cancer and stromal cells in promoting invasion and disease progression. Whereas the contribution of deregulated lncRNAs within cancer cells has received considerable attention, their significance within the tumour microenvironment is less well understood. The tumour microenvironment consists of cancer-associated stromal cells and structural extracellular components which interact with one another and with the transformed epithelium via complex extracellular signalling pathways. LncRNAs are directly and indirectly involved in tumour/stroma cross-talk and help stimulate a permissive tumour microenvironment which is more conducive for invasive tumour growth. Furthermore, lncRNAs play key roles in determining the phenotype of cancer associated stromal cells and contribute to angiogenesis and immune evasion pathways, extracellular-matrix (ECM) turnover and the response to hypoxic stress. Here we explore the multifaceted roles of lncRNAs within the tumour microenvironment and their putative pathophysiological effects. •The tumour microenvironment plays an important role during malignant progression.•LncRNAs in the tumour microenvironment may promote tumour growth and metastasis.•LncRNAs regulate the phenotype of cancer associated stromal cells.•LncRNAs play important roles in tumour/stroma cross-talk.•Stromal lncRNAs may have clinical applications as biomarkers/drug targets in cancer.