Zinc-alpha-2-glycoprotein is a protein that in humans is encoded by the AZGP1 gene. AZGP1, also referred to as zinc-alpha-2-glycoprotein (ZAG), is a glycoprotein with a molecular weight of 38-40 kDa. In 1961, AZGP1 was initially isolated from normal human plasma and named as ZAG due to its distinctive electrophoretic mobility within the alpha-2 region and its ability to bind to zinc. Subsequent analysis further identified its specific location on a particular chromosome on chromosome 7q22.1 by fluorescence in situ hybridization. AZGP1 is widely expressed in various tissues and body fluids, including the breast, stomach, liver, prostate, plasma, urine, and saliva.
This gene expresses a soluble protein that stimulates lipolysis, induces a reduction in body fat in mice, is associated with the cachexia related to cancer, and is known to be expressed in secretory cells of lung epithelium. In 2009, it was found that smoking increases expression of this gene, which is why smoking cessation leads to weight gain. Decreased circulating AZGP1 levels are associated with diabetes 2.
AZGP1 has been identified as a biomarker in cancer patients, with its role varying depending on the specific type of cancer. Low expression of AZGP1 is correlated with unfavorable outcomes in gastric cancer, esophageal squamous cell carcinoma, liver cancer, bladder cancer, and prostate cancer. For example, AZGP1 is a potential biomarker for predicting surgical failure and negatively regulates angiogenesis in prostate cancer. Elevated levels of AZGP1 have been significantly associated with poor overall survival and disease-free survival in colon cancer.
