Tuberous sclerosis complex protein 1 expression is affected by VHL Gene alterations and HIF-1α production in sporadic clear-cell renal cell carcinoma.

Alterations in von Hippel-Lindau gene (VHL) do not determine deregulation of hypoxia-inducible factors (HIFs) in clear-cell renal carcinoma (ccRCC). Their effects on tuberous sclerosis proteins (TSC1/2) and heat shock protein 90 (Hsp90) expressions in sporadic ccRCC are unknown. Therefore, we analyze the impact of VHL alterations and HIF-α production on the expression of TSC proteins and Hsp90 in these tumors. Alterations in VHL gene region exhibited 37/47 (78.7%) tumors. Monoallelic inactivation (intragenic mutation or LOH) was found in 10 (21.3%) and biallelic inactivation (intragenic mutation plus LOH) in 27 (57.4%) ccRCCs. Tumorous expression of HIF-α mRNAs, HIF-α, Hsp90 and TSC2 were VHL independent; TSC2 was underexpressed in all tumors by immunostaining (P<0.001). Immunoblotting revealed that TSC1 production was lower in tumors with monoallelic VHL inactivation than in control (P=0.01) and tissues with biallelic VHL inactivation (P=0.019), while tumors lacking HIF-1α (16/47) concurrently overexpressed HIF-2α and underexpressed TSC1 in comparison to controls (P=0.01 for both) and HIF-1α positive tumors (P=0.015 and P=0.050). Significant portion of variability (56.4%) in tumor diameter was explained by oscillations in nuclear grade, and TSC1 and HIF-2α expression in VHL altered tumors. In conclusion, while TSC2 is broadly downregulated in sporadic ccRCC, TSC1 expression is reduced in two subsets of these tumors, those with monoallelic VHL gene inactivation and those with concurrent low HIF-1α and high HIF-2α expression. Hence, the involvement of nuclear grade, TSC1 and HIF-2α in the progression of VHL altered tumors, implies the interplay between pVHL and TSC1.

VHL Dependent Expression of REDD1 and PDK3 Proteins in Clear-cell Renal Cell Carcinoma.

BACKGROUND: Sporadic clear-cell renal cell carcinoma (ccRCC) is associated with mutations in the VHL gene, upregulated mammalian target of rapamycin (mTOR) activity and glycolytic metabolism. Here, we analyze the effect of VHL mutational status on the expression level of mTOR, eIF4E-BP1, AMPK, REDD1, and PDK3 proteins. METHODS: Total proteins were isolated from 21 tumorous samples with biallelic inactivation, 10 with monoallelic inactivation and 6 tumors with a wild-type VHL (wtVHL) gene obtained from patients who underwent total nephrectomy. The expressions of target proteins were assessed using Western blot. RESULTS: Expressions of mTOR, eIF4EBP1 and AMPK were VHL independent. Tumors with monoallelic inactivation of VHL underexpressed REDD1 in comparison to wtVHL tumors (P = 0.042), tumors with biallelic VHL inactivation (P < 0.005) and control tissue (P = 0.004). Additionally, REDD1 expression was higher in tumors with VHL biallelic inactivation than in control tissue (P = 0.008). Only in wt tumor samples PDK3 was overexpressed in comparison to tumors with biallelic inactivation of VHL gene (P = 0.012) and controls (P = 0.016). In wtVHL ccRCC, multivariate linear regression analysis revealed that 97.4% of variability in PDK3 expression can be explained by variations in AMPK amount. CONCLUSION: Expressions of mTOR, eIF4EBP1 and AMPK were VHL independent. We have shown for the first time VHL dependent expression of PDK3 and we provide additional evidence that VHL mutational status affects REDD1 expression in sporadic ccRCC.

Expression of neural cell adhesion molecule in renal cell carcinoma.

Neural cell adhesion molecule (NCAM) is important for cell migration and it could be expressed in some renal cell carcinoma (RCC). In recent decades, the incidence of RCC has been steadily rising by 2-4% each year. In this study NCAM expression and correlation with nuclear grade in different RCC were analyzed. We analyzed NCAM expression on 7 different RCC cell lines and 32 different RCC by immunohistochemistry, immunofluorescence, Western blot and FACS analysis. NCAM expression is detected in 6 cell lines and 16 RCC cases. NCAM-140 kDa isoform is expressed in different RCC and RCC cell lines. NCAM expression in non-invasive clear cell RCC is lower than in clear cell RCC with high nuclear grade. Expression of NCAM is not exclusive for specific RCC type, so NCAM can not be used as a specific diagnostic marker for RCC. NCAM expression is in correlation with nuclear grade in clear cell RCC, suggesting that NCAM expression is involved in aggressive behavior and metastatic potential in RCC.

[Pax-2 antigen expression in kidney tumours].

UNLABELLED: Pax-2 transcriptional factor is expressed during kidney development and could re-express in renal tumors. The aim of this study was to examine Pax-2 expression in different types of renal cell carcinoma (RCC) in order to see whether it is good immunohistochemical marker. METHOD: We analyzed 48 different renal tumours stained with Pax-2 antibody. Pax-2 positive reaction was noticed in nucleus or cytoplasm. Expression of this antigen in tumours tissue was correlated with tumour stage and nuc-lear grade. Pax-2 expression between different histological RCC types was analyzed by chi2 test and Fishers test for two in-depended samples. RESULTS: Pax-2 is expressed by a high percentage of re-nal tumors regardless of histologic type. Significant diffe-rence of Pax-2 expression between oncocytomas and chromofobe RCC was found. CONCLUSION: Nuclear expression of Pax-2 is useful diagnostic kidney tumour marker. Pax-2 showed stronger expression in lower malignancy kidney tumours and in oncocytomas, than in high grade RCC like in those with sarcomatoid differentiation