Mucins in cancer: function, prognosis and therapy

The mucin family of transmembrane and secreted glycoproteins form a barrier that protects the epithelium. Mucins affect epithelial polarity, inflammation, and cell growth and survival signalling; all of these functions could have roles in tumour formation and progression. This Review highlights the functions of mucins in cancer and discusses how these proteins are being targeted therapeutically. Epithelia are protected from adverse conditions by a mucous barrier. The secreted and transmembrane mucins that constitute the mucous barrier are largely unrecognized as effectors of carcinogenesis. However, both types of mucins are intimately involved in inflammation and cancer. Moreover, diverse human malignancies overexpress transmembrane mucins to exploit their role in signalling cell growth and survival. Mucins have thus been identified as markers of adverse prognosis and as attractive therapeutic targets. Notably, the findings that certain transmembrane mucins induce transformation and promote tumour progression have provided the experimental basis for demonstrating that inhibitors of their function are effective as anti-tumour agents in preclinical models.