The Mucin Family of Proteins: Candidates as Potential Biomarkers for Colon Cancer

SIMPLE SUMMARY: Colorectal cancer is the second leading cause of cancer-related deaths in the United States with an overall 5-year survival of 65%. While there have been many advances in the treatment of this disease over the past few decades, there has been minimal change in the overall five-year survival in the past twenty years. Thus, there is still a need for the improved detection and treatment of this malignancy that affects many patients. Mucins are a family of glycoproteins (MUC1–MUC24) expressed by many epithelial tissues and some have been implicated in the progression of various malignancies. Mucins have diverse expression profiles amongst pre-malignant, malignant, and normal colonic tissues. This review article focuses on mucin expression profiles in normal and malignant colonic tissue as well as mucins’ role in diagnostics, therapeutics, and prognostication. ABSTRACT: Mucins (MUC1–MUC24) are a family of glycoproteins involved in cell signaling and barrier protection. They have been implicated in the progression of numerous malignancies including gastric, pancreatic, ovarian, breast, and lung cancer. Mucins have also been extensively studied with respect to colorectal cancer. They have been found to have diverse expression profiles amongst the normal colon, benign hyperplastic polyps, pre-malignant polyps, and colon cancers. Those expressed in the normal colon include MUC2, MUC3, MUC4, MUC11, MUC12, MUC13, MUC15 (at low levels), and MUC21. Whereas MUC5, MUC6, MUC16, and MUC20 are absent from the normal colon and are expressed in colorectal cancers. MUC1, MUC2, MUC4, MUC5AC, and MUC6 are currently the most widely covered in the literature regarding their role in the progression from normal colonic tissue to cancer.