Expression of Annexin A4 in Cancer: A Tissue Microarray Study Involving More than 17,600 Cancers from 148 Tumor Entities

Background/Objectives: Annexin A4 (ANXA4) is one of twelve members of the annexin superfamily that bind membrane phospholipids in a calcium-dependent manner, and which are involved in several processes related to the membrane. Methods: To learn more about the role of ANXA4 in cancer, the ANXA4 expression was analyzed by immunohistochemistry (IHC) on tissue microarrays (TMAs) containing 17,654 tumors and precursor lesions from 148 tumor types. Results: ANXA4 immunostaining was found in 10,858 (83.4%) of 13,017 analyzable tumors, and was considered weak in 10.1%, moderate in 16.6%, and strong in 61.8% of cases. Of 148 tumor categories, 144 showed ANXA4 staining in at least one case and 133 included at least one case with strong staining. Among tumor entities with at least 10 evaluable samples, strong ANXA4 staining in >50.0% of cases was seen in 56 of 120 entities, while absence of staining in >50.0% of cases was seen in 13. Clinically important tumor entities where ANXA4 staining was always positive (>99.5%) included gallbladder adenocarcinoma, cholangiocarcinoma, pancreatic/ampullary, various subtypes of salivary gland tumors, papillary renal cell carcinoma, urothelial carcinoma, squamous and basal cell carcinoma of the skin, and epithelioid mesothelioma. A reduced ANXA4 expression was linked to features of cancer aggressiveness in breast cancer, clear cell renal cell carcinoma, urothelial carcinoma, pancreatic ductal adenocarcinoma, hepatocellular carcinoma, colorectal adenocarcinoma, and follicular thyroid carcinoma. Conclusions: It is concluded that ANXA4 is abundantly expressed in human malignancies and that a reduced expression may be linked to unfavorable disease characteristics in many important tumor entities.