The unfolded protein response and cancer: a brighter future unfolding?

Mammalian cells are bathed in an interstitial fluid that has a tightly regulated composition in healthy states. Interstitial fluid provides cells with all the necessary metabolic substrates (oxygen, glucose, amino acids, etc.), and waste molecules are removed by diffusion gradients that are controlled by local vascular perfusion. The health and normal function of all cells within a body is dependent on the maintenance of this microenvironment. However, many disease states cause fluctuations in this, and in some instances, these might be of sufficient severity to stress and/or be toxic to the cell. Cells have developed a number of responses to enable their survival in a hostile environment. This article discusses one such pathway--the unfolded protein response and its relationship to cancer. The molecular signalling cascade, the mechanism of its activation in cancer and the consequences of its activation for a tumour are discussed, as are clinical studies and potential translational approaches for utilising this pathway for tumour targeting.