Renal cell carcinoma

Elucidating environmental factors and their combined effects on CKDu in Sri Lanka using zebrafish

Chronic kidney disease with uncertain etiology (CKDu) in Sri Lanka has attracted much attention as a global health issue. However, how environmental factors in local drinking water induce kidney damage in organisms is still elusive. We investigated multiple environmental factors including water hardness and fluoride (HF), heavy metals (HM), microcystin-LR (MC-LR), and their combined exposure (HFMM) to elucidate their toxic effects on CKDu risk in zebrafish. Acute exposure affected renal development and inhibited the fluorescence of Na, K-ATPase alpha1A4:GFP zebrafish kidney. Chronic exposure influenced the body weight of both genders of adult fish and induced kidney damage by histopathological analyses. Furthermore, the exposure significantly disturbed differential expression genes (DEGs), diversity and richness of gut microbiota, and critical metabolites related to renal functions. The transcriptomic analysis revealed that kidney-related DEGs were linked with renal cell carcinoma, proximal tubule bicarbonate reclamation, calcium signaling pathway, and HIF-1 signaling pathway. The significantly disrupted intestinal microbiota was closely related to the environmental factors and H&E score, which demonstrated the mechanisms of kidney risks. Notably, the Spearman correlation analysis indicated that the changed bacteria such as Pseudomonas, Paracoccus, and ZOR0006, etc were significantly connected to the DEGs and metabolites. Therefore, the assessment of multiple environmental factors provided new insights on "bio-markers" as potential therapies of the target signaling pathways, metabolites, and gut bacteria to monitor or protect residents from CKDu.

Mitochondrial Sirt3 supports cell proliferation by regulating glutamine-dependent oxidation in renal cell carcinoma

Clear cell renal carcinoma (RCC), the most common malignancy arising in the adult kidney, exhibits increased aerobic glycolysis and low mitochondrial respiration due to von Hippel-Lindau gene defects and constitutive hypoxia-inducible factor-α expression. Sirt3 is a major mitochondrial deacetylase that mediates various types of energy metabolism. However, the role of Sirt3 as a tumor suppressor or oncogene in cancer depends on cell types. We show increased Sirt3 expression in the mitochondrial fraction of human RCC tissues. Sirt3 depletion by lentiviral short-hairpin RNA, as well as the stable expression of the inactive mutant of Sirt3, inhibited cell proliferation and tumor growth in xenograft nude mice, respectively. Furthermore, mitochondrial pyruvate, which was used for oxidation in RCC, might be derived from glutamine, but not from glucose and cytosolic pyruvate, due to depletion of mitochondrial pyruvate carrier and the relatively high expression of malic enzyme 2. Depletion of Sirt3 suppressed glutamate dehydrogenase activity, leading to impaired mitochondrial oxygen consumption. Our findings suggest that Sirt3 plays a tumor-progressive role in human RCC by regulating glutamine-derived mitochondrial respiration, particularly in cells where mitochondrial usage of cytosolic pyruvate is severely compromised.

Proteomic analysis reveals differentially secreted proteins in the urine from patients with clear cell renal cell carcinoma

OBJECTIVE

The aim of this study was to evaluate the differentially secreted protein profile in the urine from patients with clear cell renal cell carcinoma (ccRCC) using mass spectrometry-based methods. Urine composition can reflect kidney physiology and can be used to detect markers for renal diseases. Moreover, characterization of the secretome is likely to assist in the investigation of new drugs for biological targets and diagnose the ccRCC at an early stage.

METHODS AND MATERIALS

Urine samples from patients were divided according to Fuhrman degree (FI-IV), which was associated with the cellular differentiation as good prognosis (GP) and poor prognosis (PP). Healthy individuals were used as the control group (CG). We used both qualitative and quantitative mass spectrometry-based analyses that involved the following approaches: 1-dimensional gel electrophoresis combined with liquid chromatography mass spectrometry in tandem (1DE LC-MS/MS), in-solution digestion combined with label-free 1-dimensional LC-MS(E) (1D LC-MS(E)), and bidimensional gel electrophoresis combined with matrix-assisted laser desorption/ionization time of flight in tandem (2DE MALDI-TOF/TOF) or combined with LC-MS/MS.

RESULTS

All the strategies allowed the identification of 354 proteins from the CG, GP, and PP groups. Qualitative experiments using 1DE LC-MS/MS analysis detected different protein profiles, and 224 proteins were identified in all groups. The label-free MS(E) quantitative analysis identified 113 proteins and generated novel information on secreted protein profiles, including 49 up-secreted proteins in the urine from patients with ccRCC and 40 down-secreted proteins related to the CG. Proteins such as kininogen-1, uromodulin, apolipoprotein D, polyubiquitin, and CD59 glycoprotein were down secreted according to the groups CG>GP>PP. In contrast, apolipoprotein A, fibrinogen, and haptoglobin were up secreted in patient groups. The same expression profile observed for kininogen-1, apolipoprotein D, fibrinogen, and haptoglobin was corroborated by 2DE LC-MS/MS or 2DE MALDI-TOF/TOF analyses. These 2 strategies also showed 13 differentially secreted proteins among the 3 groups.

CONCLUSIONS

The proteins kininogen-1, apolipoprotein D, fibrinogen, and haptoglobin presented similar quantitative protein profiles according to MS(E) and 2DE approaches. The latter proteins were up secreted and the former ones were down-regulated. The strategies used proved to be valuable in identifying proteins that were differentially secreted in urine from patients with RCC.

Targeting GLUT1 and the Warburg effect in renal cell carcinoma by chemical synthetic lethality

Identifying new targeted therapies that kill tumor cells while sparing normal tissue is a major challenge of cancer research. Using a high-throughput chemical synthetic lethal screen, we sought to identify compounds that exploit the loss of the von Hippel-Lindau (VHL) tumor suppressor gene, which occurs in about 80% of renal cell carcinomas (RCCs). RCCs, like many other cancers, are dependent on aerobic glycolysis for ATP production, a phenomenon known as the Warburg effect. The dependence of RCCs on glycolysis is in part a result of induction of glucose transporter 1 (GLUT1). Here, we report the identification of a class of compounds, the 3-series, exemplified by STF-31, which selectively kills RCCs by specifically targeting glucose uptake through GLUT1 and exploiting the unique dependence of these cells on GLUT1 for survival. Treatment with these agents inhibits the growth of RCCs by binding GLUT1 directly and impeding glucose uptake in vivo without toxicity to normal tissue. Activity of STF-31 in these experimental renal tumors can be monitored by [(18)F]fluorodeoxyglucose uptake by micro-positron emission tomography imaging, and therefore, these agents may be readily tested clinically in human tumors. Our results show that the Warburg effect confers distinct characteristics on tumor cells that can be selectively targeted for therapy.

ADAM9 is highly expressed in renal cell cancer and is associated with tumour progression

BACKGROUND

A Disintegrin And Metalloprotease (ADAM) 9 has been implicated in tumour progression of various solid tumours, however, little is known about its role in renal cell carcinoma. We evaluated the expression of ADAM9 on protein and transcript level in a clinico-pathologically characterized renal cell cancer cohort.

METHODS

108 renal cancer cases were immunostained for ADAM9 on a tissue-micro-array. For 30 additional cases, ADAM9 mRNA of microdissected tumour and normal tissue was analyzed via quantitative RT-PCR. SPSS 14.0 was used to apply crosstables (Fisher's exact test and chi2-test), correlations and univariate as well as multivariate survival analyses.

RESULTS

ADAM9 was significantly up-regulated in renal cancer in comparison to the adjacent normal tissue on mRNA level. On protein level, ADAM9 was significantly associated with higher tumour grade, positive nodal status and distant metastasis. Furthermore, ADAM9 protein expression was significantly associated with shortened patient survival in the univariate analysis.

CONCLUSION

ADAM9 is strongly expressed in a large proportion of renal cell cancers, concordant with findings in other tumour entities. Additionally, ADAM9 expression is significantly associated with markers of unfavourable prognosis. Whether the demonstrated prognostic value of ADAM9 is independent from other tumour parameters will have to be verified in larger study cohorts.

[Pediatric renal cell carcinoma. A rare differential diagnosis of Wilms' tumor]

Renal cell carcinoma (RCC) is a very rare pediatric disease and should be treated as an entity of its own because of differences in symptoms, therapy, and prognosis from the adult form of the disease. Our objective is to discuss the difficulties in clinical diagnosis, prognosis, and therapy of this very rare disease in children and to provide a review of the current literature.