Introduction: Recently, our group showed that Vim3 is overexpressed in tissue samples of renal oncocytomas and Mxi-2 in clear cell renal carcinoma (ccRCCs). The mechanism leading to the truncation of both proteins is known and involves with two miRs, both detectable in urine. Since the analysis of miRs is time consuming, our aim was to identify the truncated proteins in urine instead. Furthermore, urine samples from small renal cancers (SRM) (n=45, <4 cm) were analyzed to get a pre-surgical differentiation of the cancer subtypes. Moreover we analyzed the Vim3 and Mxi-2 urine expression in patients before and 5 days after surgery (n=40)
Methods: Urines were accessed from the urological biobank (n=350). Proteins were isolated from urine samples, and Western blots were performed. In addition each sample was analyzed via ELISA for the expression of Vim3 and Mxi-2. A lateral flow assay was established. For the detection of SRMs, the miRs were isolated and qRT-PCR was performed.
Results: A significant increase of Vim3 in urines from patients with oncocytoma (n=20) was detectable via ELISA compared to all other subtypes of RCCs (chromophobe (n=50), papillary (n=40), ccRCC (n=200), and controls (n=40) (***p < 0.0001)). Mxi-2 was predominantly overexpressed in ccRCCs (***p < 0.0001). Lateral flow assay of Vim3 and Mxi-2 shows two bands in the case of oncocytoma and ccRCC respectively indicating the specificity of this test. For SRMs, an overexpression of miR-15a/Mxi2 was detectable in urine samples from ccRCC and chromoRCC patients. In contrast the miR-498/Vim3 were predominantly overexpressed in oncocytoma patients. Furthermore, after surgical removement of the tumors both proteins significantly decreased.
Conclusions: Both proteins (Vim3 and Mxi-2) were detectable in patients’ urines and can be used for the non-invasive differentiation of kidney tumors and moreover both proteins decrease significantly after surgery.
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