Renal cell carcinomas
RAGE and its ligands are reported to be abnormally expressed in various cancers, including breast, lung, kidney, thyroid, prostate, and oral cancers. S100 protein, one of the representative ligands of RAGE, which has at least over 20 subtypes, has been well reviewed to play major roles in tumor-related processes, including proliferation, apoptosis, metastasis, and invasion [10]. In renal cancer, S100A1 has been observed to be highly expressed in papillary RCC and oncocytoma, which are relatively common types of renal cancers, whereas it is absent in chromophobe RCC [49]. Likewise, a broad range of S100 proteins has been detected differently, depending on the subtype of renal carcinoma, which means that it should be a useful biomarker for discriminating the subtype of renal cancers if it is correctly examined [50]. In addition, HMGB1, another ligand of RAGE, has appeared to be up-regulated and interacts with its receptor for promoting cell proliferation, migration, and invasion via the ERK pathway in RCC [32]. From this evidence, RAGE and its multiple ligands are increasingly suggested as biomarkers and therapeutic targets for different types of renal carcinomas.