Caveolin-1 in renal cell carcinoma promotes tumour cell invasion, and in co-operation with pERK predicts metastases in patients with clinically confined disease.

BACKGROUND: Up to 40% of patients initially diagnosed with clinically-confined renal cell carcinoma (RCC) and who undergo curative surgery will nevertheless relapse with metastatic disease (mRCC) associated with poor long term survival. The discovery of novel prognostic/predictive biomarkers and drug targets is needed and in this context the aim of the current study was to investigate a putative caveolin-1/ERK signalling axis in clinically confined RCC, and to examine in a panel of RCC cell lines the effects of caveolin-1 (Cav-1) on pathological processes (invasion and growth) and select signalling pathways. METHODS: Using immunohistochemistry we assessed the expression of both Cav-1 and phosphorylated-ERK (pERK) in 176 patients with clinically confined RCC, their correlation with histological parameters and their impact upon disease-free survival. Using a panel of RCC cell lines we explored the functional effects of Cav-1 knockdown upon cell growth, cell invasion and VEGF-A secretion, as well Cav-1 regulation by cognate cell signalling pathways. RESULTS: We found a significant correlation (P = 0.03) between Cav-1 and pERK in a cohort of patients with clinically confined disease which represented a prognostic biomarker combination (HR = 4.2) that effectively stratified patients into low, intermediate and high risk groups with respect to relapse, even if the patients' tumours displayed low grade and/or low stage disease. In RCC cell lines Cav-1 knockdown unequivocally reduced cell invasive capacity while also displaying both pro-and anti-proliferative effects; targeted knockdown of Cav-1 also partially suppressed VEGF-A secretion in VHL-negative RCC cells. The actions of Cav-1 in the RCC cell lines appeared independent of both ERK and AKT/mTOR signalling pathways. CONCLUSION: The combined expression of Cav-1 and pERK serves as an independent biomarker signature with potential merit in RCC surveillance strategies able to predict those patients with clinically confined disease who will eventually relapse. In a panel of in-vitro RCC cells Cav-1 promotes cell invasion with variable effects on cell growth and VEGF-A secretion. Cav-1 has potential as a therapeutic target for the prevention and treatment of mRCC.

Glutathione S-transferases as molecular markers of tumour progression and prognosis in renal cell carcinoma.

AIMS: Renal cell carcinoma (RCC) often recurs as distant metastasis; there is thus a need for new indicators to identify high-risk patients. Glutathione S-transferases (GST)-α and -π are involved in the renal bioactivation of toxic metabolites. The aim was to investigate whether their expression is of diagnostic and prognostic value. METHODS AND RESULTS: Western blotting of microdissected normal kidney and immunostaining of histological RCC microarrays shows expression of GST-α in proximal tubular cells, while GST-π was found in the distal nephron. Of the primary 174 RCC cases examined, GST-α immunoreactivity was restricted to conventional RCC (n=76, 68% positive) and was not seen in any other RCC subtypes. The cross-tabulation of the GST-α scores with other prognostic indices demonstrated that GST-α immunostaining was significantly more frequent in low-grade tumours (χ(2): P<0.004), and that conventional GST-α-positive RCC patients had a mean disease-free survival of 6.0 years (95% confidence interval 5.33-6.63), compared with 4.7 years (3.54-5.90) in GST-α-negative tumours (Kaplan-Meier survival analysis, P=0.011, log-rank test). CONCLUSIONS: GST-α is a highly specific diagnostic marker for primary conventional RCC, where it is a prognostic marker if grade is omitted from the multivariate analysis.

Apc deficiency predisposes to renal carcinoma in the mouse.

Deregulation of Wnt signalling has recently been implicated in human renal cancer. Here, we directly test this association by using a Cre-LoxP strategy to inactivate the Adenomatous Polyposis Coli (Apc) gene in the murine renal epithelium. Mice homozygous for a conditional Apc allele were intercrossed with mice transgenic for Cre recombinase under control of the Cyp1A promoter, which delivers constitutive recombination within a proportion of cells in the renal epithelium. Inactivation of Apc leads to the accumulation of nuclear beta-catenin and the rapid development of multiple dysplastic foci. Renal carcinoma was observed with an earliest onset of 4 months. This predisposition was accelerated by p53 deficiency, reducing the earliest onset to 2 months. Compared to other murine models of kidney neoplasia, this represents particularly rapid onset of disease, and so implicates an important role for Apc in suppressing renal carcinoma.

The presence of glomerular sclerosis at time zero has a significant impact on function after cadaveric renal transplantation.

INTRODUCTION: The aim was to determine the impact of donor glomerulosclerosis on allograft outcome. METHODS: The percentage of glomerular sclerosis (%GS) was calculated in protocol biopsies taken at engraftment. Clinical variables were obtained from the Welsh Transplantation Research Group (WTRG) database. RESULTS: Of 210 allografts, 129 showed %GS=0, but 81 kidneys showed %GS between 1 and 60. Patients with %GS=0 had the highest glomerular filtration rate (GFR) at 1 year (62.0 mL/min) and the slowest deterioration of function (-3.8 mL/min per year). Patients with %GS greater than 20 had the lowest GFR at 1 year (36.0 mL/min) and the steepest rate of deterioration (-9.0 mL/min per year). The %GS of 10 alone can reduce GFR at 4 years by 8 mL/min, a similar reduction to a single rejection episode or an increase in donor age of 30 years. Actuarial 5-year graft survival for %GS=0 was 80%, and for %GS greater than 20 was 35% ( P=0.04). CONCLUSION: The findings indicate that a biopsy taken at procurement will provide information for the most appropriate allocation of a kidney.

Prostate needle biopsy processing: a survey of laboratory practice across Europe.

AIM: To determine the degree of variation in the handling of prostate needle biopsies (PBNx) in laboratories across Europe. METHODS: A web based survey was emailed to members of the European Network of Uropathology and the British Association of Urological Pathologists. RESULTS: Responses were received from 241 laboratories in 15 countries. PNBx were generally taken by urologists (93.8%) or radiologists (23.7%) but in 8.7% were also taken by non-medical personnel such as radiographers, nurses or biomedical assistants. Of the responding laboratories, 40.8% received cores in separate containers, 42.3% processed one core/block, 54.2% examined three levels/block, 49.4% examined one H&E section/level and 56.1% retained spare sections for potential immunohistochemistry. Of the laboratories, 40.9% retained unstained spares for over a year while 36.2% discarded spares within 1 month of reporting. Only two (0.8%) respondents routinely performed immunohistochemistry on all PNBx. There were differences in laboratory practice between the UK and the rest of Europe (RE). Procurement of PNBx by non-medical personnel was more common in the UK. RE laboratories more commonly received each core in a separate container, processed one core/block, examined fewer levels/block and examined more H&E sections/level. RE laboratories also retained spares for potential immunohistochemistry less often and for shorter periods. Use of p63 as the sole basal cell marker was more common in RE. CONCLUSIONS: There are marked differences in procurement, handling and processing of PNBx in laboratories across Europe. This data can help the development of best practice guidelines.

A mouse model of tuberous sclerosis 1 showing background specific early post-natal mortality and metastatic renal cell carcinoma.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by mutations in either the TSC1 or the TSC2 genes and characterized by the development of benign hamartomatous growths in multiple organ systems. We have inactivated Tsc1 in the mouse germ line by gene targeting in ES cells and confirmed that the mutant allele (Tsc1-) has a recessive embryonic lethal phenotype. We found that a significant number (approximately 27%) of heterozygous (Tsc1+/-) mice on the C57BL/6 background died before weaning (P = 0.014) and show that these mice die in the post-natal period (P = 0.033), normally at 1-2 days, from unknown causes. Forty-four percent (7/16) of Tsc1+/- mice on a C3H background developed macroscopically visible renal lesions as early as 3-6 months, increasing to 95% (37/39) by 15-18 months. Renal lesions progressed from cysts through cystadenomas to solid carcinomas. Eighty percent (16/20) of Tsc1+/- mice on a Balb/c background exhibited solid renal cell carcinomas (RCC) by 15-18 months and in 41%, RCCs were > or = 5 mm, resulting in grossly deformed kidneys. Some RCCs had a sarcomatoid morphology of spindle cells in whorled patterns and metastasized to the lungs. We detected loss of the wild-type Tsc1 allele and elevated levels of p-mTOR and p-S6 in lesions from Tsc1+/- mice. This new murine model of hamartin deficiency exhibits a more severe phenotype than existing models.