Diagnostic markers and progression markers are still lacking in many tumor entities. Renal cell carcinoma is no exception. However, many tumors release a wide variety of "soluble" surface proteins that can be isolated and measured in body fluids or from exosomes.
In addition to various protein markers from whole blood or serum, exosomes and RNAs are the main focus of biomarker research, including renal cell carcinoma. Exosomes are essentially spherical structures measuring 30 to 150 nm that serve cell-to-cell communication. In addition to RNA and DNA, they can also contain proteins and peptide fragments. Cells control other cells and their immediate environment via exosomes and their components.
Researchers had their first success in isolating exosomes from kidney cancer cells in cell cultures. There, exosomes are found in the cell culture supernatant. This is centrifuged using special gradient methods and thus releases the exosomes. Ultracentrifugation using sucrose gradients, for example, has proved to be a successful method.
Through the purification and enrichment of exosomes from cell culture supernatants, we already know four possible, soluble tumor markers of renal cell carcinoma, some of which could have the potential to be developed into biomarkers. The following four possible marker proteins have already been described in tumor tissue and in the blood plasma of patients with renal cell carcinoma.
CD70 is predominantly expressed in clear cell renal cell carcinoma (ccRCC) and mainly induces cell proliferation. EpCAM, on the other hand, is an epithelial cell marker that serves cell adhesion and is overexpressed primarily in rapidly dividing cells. CD147, the so-called basigin, is upregulated in some tumors and then supports angiogenesis and lactate transport. Of particular interest is also carbonic anhydrase IX (CA9), which is strongly overexpressed by ccRCC in particular. This is a cellular acid-base regulator which, among other things, plays an important role in cell survival.
Reference:
7th Symposium Renal Cell Carcinoma 2021 (online)