Differential expression pattern of annexin A2 during nephrogenesis and kidney carcinoma.

The creation of a cancer cell could be due to reactivation of repressed gene in the process of normal embryonic development. The differences in embryonic origins and functions of various components of nephron may contribute to the diversity of morphological patterns, molecular and immunohistochemical phenotypes of common renal neoplasms. Renal cell carcinomas (RCCs) are the most common amongst the genitourinary cancers. Annexin A2 (AnxA2) is a multifunctional calcium-regulated phospholipids-binding protein found in a subset of renal neoplasms. Since the tumor cells usually recapitulate embryonic cells, we studied the ontogeny of AnxA2 in developing renal tissues and compared it with those of normal adult RCCs, to better understand their role in renal development and tumorigenesis. AnxA2 immunoexpression was evaluated by immunohistochemistry from various autopsied fetuses, mature kidney and renal cancer tissue specimens. The study showed moderate membranous AnxA2 immunoexpression in the ureteric buds and collecting tubules of fetal kidneys (in all gestational ages) and in the collecting ducts of adult normal renal tissues. It is not often expressed in the proximal convoluted tubules of normal adult kidney; however, younger fetal kidneys show moderate AnxA2 immunoexpression in the proximal convoluted tubules (thought to be the origin of RCC) and the reappearance of strong membranous AnxA2 immunoexpression in the clear cell carcinoma is suggesting a deregulation of the gene during tumorigenesis. The understanding of the AnxA2 molecular immunoexpression pattern during development, its specific function and deregulated immunoexpression in different renal carcinoma types indicates the decisive role of AnxA2 in the cancer progression.