Benign and tumor parenchyma metabolomic profiles affect compensatory renal growth in renal cell carcinoma surgical patients

Possible Effects of Uremic Toxins p-Cresol, Indoxyl Sulfate, p-Cresyl Sulfate on the Development and Progression of Colon Cancer in Patients with Chronic Renal Failure

Chronic kidney disease (CKD) induces several systemic effects, including the accumulation and production of uremic toxins responsible for the activation of various harmful processes. Gut dysbiosis has been widely described in CKD patients, even in the early stages of the disease. The abundant discharge of urea and other waste substances into the gut favors the selection of an altered intestinal microbiota in CKD patients. The prevalence of bacteria with fermentative activity leads to the release and accumulation in the gut and in the blood of several substances, such as p-Cresol (p-C), Indoxyl Sulfate (IS) and p-Cresyl Sulfate (p-CS). Since these metabolites are normally eliminated in the urine, they tend to accumulate in the blood of CKD patients proportionally to renal impairment. P-CS, IS and p-C play a fundamental role in the activation of various pro-tumorigenic processes, such as chronic systemic inflammation, the increase in the production of free radicals and immune dysfunction. An up to two-fold increase in the incidence of colon cancer development in CKD has been reported in several studies, although the pathogenic mechanisms explaining this compelling association have not yet been described. Based on our literature review, it appears likely the hypothesis of a role of p-C, IS and p-CS in colon cancer development and progression in CKD patients.

Can kidney parenchyma metabolites serve as prognostic biomarkers for long-term kidney function after nephrectomy for renal cell carcinoma? A preliminary study

Objective

Nephrectomy, the standard of care for localized renal cell carcinoma (RCC), may lead to kidney function loss. Our goal was to identify prognostic biomarkers of postoperative renal function using metabolomics.

Methods

Metabolomics data from benign kidney parenchyma were collected prospectively from 138 patients with RCC who underwent nephrectomy at a single institution. The primary endpoint was the difference between the postoperative and preoperative estimated glomerular filtration (eGFR) rate divided by the elapsed time (eGFR slope). eGFR slope was calculated ∼2 years post-nephrectomy (GFR1), and at last follow-up (GFR2). A multivariate regularized regression model identified clinical characteristics and abundance of metabolites in baseline benign kidney parenchyma that were significantly associated with eGFR slope. Findings were validated by associating gene expression data with eGFR slope in an independent cohort (n = 58).

Results

Data were compiled on 78 patients (median age 62.6 years, 65.4% males). The mean follow-up was 25 ± 3.4 months for GFR1 and 69.5 ± 23.5 months for GFR2 and 17 (22%) and 32 (41%) patients showed eGFR recovery, respectively. Nephrectomy type, blood lipids, gender and 23 metabolites from benign parenchyma were significantly associated with eGFR slope. Some metabolites associated with eGFR slope overlapped with previously reported chronic kidney disease-related processes. Subgroup analysis identified unique ‘metabolite signatures’ by older age, nephrectomy type and preoperative eGFR.

Conclusions

Nephrectomy type, gender, blood lipids and benign parenchyma metabolites at nephrectomy were associated with long-term kidney function. On further study, these metabolites may be useful as potential biomarkers and to identify novel therapeutic targets for malignancy-associated renal disease.