Renal cell carcinoma (RCC) diagnosis is mostly achieved incidentally by imaging provided for unrelated clinical reasons. The surgical management of localized tumors has reported excellent results. The therapy of advanced RCC has evolved considerably over recent years with the widespread use of the so-called “targeted therapies.” The identification of molecular markers in body fluids (e.g., sera and urine), which can be used for screening, diagnosis, follow-up, and monitoring of drug-based therapy in RCC patients, is one of the most ambitious challenges in oncologic research. Although there are some promising reports about potential biomarkers in sera, there is limited available data regarding urine markers for RCC. The following review reports some of the most promising biomarkers identified in the biological fluids of RCC patients.

Recent evidence suggests that neutrophil gelatinase-associated lipocalin (NGAL) is required for the development and/or progression of benign and malignant disease, and is overexpressed in several types of tumor. Matrix metalloproteinase-9 (MMP-9), by degrading components of the extracellular matrix and thus promoting the release of growth factors, is important in tumor growth and tumorigenicity. NGAL protects MMP-9 from proteolytic degradation and enhances its enzymatic activities by binding and forming the MMP-9/NGAL complex. Therefore, NGAL, MMP-9 and their complex MMP-9/NGAL have been proposed as soluble biomarkers for numerous malignancies. In the present study, we measured the concentration of these molecules in sera and urine of patients with kidney disease using ELISA. Of these patients, 16 had clear cell renal cell carcinoma (ccRCC) and 4 had oncocytoma. Sera and urine samples of 53 healthy patients were used as controls. In sera, MMP-9 was enhanced in ccRCC patients compared with oncocytoma patients. In urine, the most abundant molecule was NGAL and its mean value was higher in cancer patients. However, there was a broad overlap of the data and we did not identify any correlation with disease type, stage or grade. Therefore, these molecules may not be useful as biomarkers for predicting kidney carcinoma.

The identification of biomarkers in urine or serum samples from patients with bladder cancer is urgently required for the development of non-invasive methods for the diagnosis of bladder carcinoma and to facilitate follow-up surveillance, to combat the high progression and recurrence rates of this type of cancer. The current study measured the content of matrix metalloproteinase (MMP)-2 and -9, as well as tissue inhibitor of metalloproteinase (TIMP)-1 and -2 in the urine and sera of 41 patients with bladder cancer by ELISA. The association between levels of MMP-2 and -9 and TIMP-1 and -2, and tumor grade and stage were investigated to verify whether these molecules are involved in tumor differentiation. Statistical analysis of the data revealed that urinary TIMP-1 levels were significantly higher in the high grade group compared with those of the low grade samples (P=0.022). The results also revealed a significantly differing distribution of TIMP-1 expression between Ta and T1 stage specimens (P=0.040). The corresponding area under the curves (AUCs) were 0.72, with a sensitivity of 0.70 and specificity of 0.75. In addition, neutrophil gelatinase-associated lipocalin (NGAL) and MMP-9/NGAL complex levels in the sera were measured. All molecules evaluated were detected in the sera of the patients studied. In particular, tumors staged as non-muscle invasive (Ta and T1), demonstrated significantly higher NGAL levels compared with those of muscle invasive (>T1) bladder cancer (32.8 ng/ml vs. 16.2 ng/ml; P=0.029). The discriminatory ability of NGAL expression was confirmed by receiver operating characteristic curve analysis that revealed an AUC of 0.75, a sensitivity of 0.88 and a specificity of 0.67. These data indicated that urinary TIMP-1 and serum NGAL may be useful non-invasive biomarkers to provide clinical information for bladder cancer disease management. Multicenter, prospective studies are required to confirm these preliminary results.

A key challenge for the improvement of clear cell renal cell carcinoma (ccRCC) management could derive from a deeper characterization of the biology of these neoplasms that could greatly improve the diagnosis, prognosis and treatment choice. The aim of this study was to identify specific miRNAs that are deregulated in tumor vs. normal kidney tissues and that could impact on the biology of ccRCC. To this end we selected four miRNAs (miR-21-5p, miR-210-3p, miR-185-5p and miR-221-3p) and their expression has been evaluated in a retrospective cohort of formalin-fixed paraffin-embedded (FFPE) tissues from 20 ccRCC patients who underwent surgical nephrectomy resection. miR-21-5p and miR-210-3p resulted the most significantly up-regulated miRNAs in this patient cohort, highlighting these onco-miRNAs as possible relevant players involved in ccRCC tumorigenesis. Thus, this study reports the identification of specific oncogenic miRNAs that are altered in ccRCC tissues and suggests that they might be useful biomarkers in ccRCC management.

Matrix metallo-proteinases (MMPs) are a family of zinc-dependent endopeptidases, capable of degrading all the molecular components of extracellular matrix. A class of MMPs is gelatinases which includes gelatinase A or MMP-2 (72 kDa) and gelatinase B or MMP-9 (92 kDa), which have been shown to play critical roles in pathophysiology of many human disease and, in particular, cancer progression. For these reasons they obtained a great interest as potential non-invasive biomarker in providing useful clinical information in cancer diagnosis and therapy. A sensitive and unexpensive method for analysis of gelatinases is the gelatine zymography, which allows to measure the relative amounts of active and inactive enzymes in body fluids and tissue extracts. The procedure involves the electrophoretic separation of proteins under denaturing but non reducing conditions through a polyacrylamide gel containing a synthetic substrate (gelatin). The aim of this mini-review has been to describe the general principles of gelatine zymography technique, underling the main advantages and disadvantages. Even though an improvement of this method is necessary for a better applicability in laboratory medicine, gelatine zymography represents the most convenient method to detect the activity of the different gelatinases from a wide range of biological samples.

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases, capable of degrading all the molecular components of extracellular matrix. MMPs have been shown to play critical roles in tumor cell invasion and metastasis. We verified the activity of MMPs in the sera and in the urine of patients with kidney carcinoma by gelatin zymography. Of these patients, 16 had clear cell renal carcinoma (ccRCC) and 4 patients had oncocytoma. The sera and the urine of 16 healthy subjects were used as controls. In the sera, zymography analysis showed gelatinolytic bands at 72 kDa (gelatinase A) at 92, 130 and 240 kDa (gelatinase B). MMP-9 activity was slightly enhanced in sera from ccRCC compared with oncocytoma patients. Serum MMP-2 activity was similar in ccRCC and in oncocytoma patients. In the urine, 2 oncocytoma patients and 3 (33%) of the ccRCC patients showed gelatinolytic activity, whereas MMPs could not be detected in the concentrated urine of healthy subjects. The most abundant lytic activity was at 92 kDa, whereas MMP-2 was present in lesser quantities. However, there was broad overlap of the data and we did not find any correlation to type, stage or grade. Therefore, despite previous evidence, MMP-2 and -9 activity in serum and urine may not be useful biomarker for kidney carcinomas.