Current insights in renal cell cancer pathology

Accuracy of CT texture analysis for differentiating low-grade and high-grade renal cell carcinoma: systematic review and meta-analysis

OBJECTIVES

This study aimed to assess the accuracy of CT texture analysis (CTTA) for differentiating low-grade and high-grade renal cell carcinoma (RCC).

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed, Cochrane Library, Embase, Web of Science, OVID Medline, Science Direct and Springer were searched to identify the included studies.

ELIGIBILITY CRITERIA FOR INCLUDING STUDIES

Clinical studies that report about the accuracy of CTTA in differentiating low-grade and high-grade RCC.

METHODS

Multiple databases were searched to identify studies from their inception to 20 October 2021. Two radiologists independently extracted data from the primary studies. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR) and diagnostic OR (DOR) were calculated to assess CTTA performance. The summary receiver operating characteristic (SROC) curve was plotted, and the area under the curve (AUC) was calculated to evaluate the accuracy of CTTA in grading RCC.

RESULTS

This meta-analysis included 11 studies, with 1603 lesions observed in 1601 patients. Values of the pooled sensitivity, specificity, PLR, NLR, DOR were 0.79 (95% CI 0.73 to 0.84), 0.84 (95% CI 0.81 to 0.87), 5.1 (95% CI 4.0 to 6.4), 0.24 (95% CI 0.19 to 0.32) and 21 (95% CI 13 to 33), respectively. The SROC curve showed that the AUC was 0.88 (95% CI 0.84 to 0.90). Deeks' test found no significant publication bias among the studies (p=0.42).

CONCLUSIONS

The findings of this meta-analysis suggest that CTTA has a high accuracy in differentiating low-grade and high-grade RCC. A standardised methodology and large sample-based study are necessary to certain the diagnostic accuracy of CTTA in RCC grading for clinical decision making.

Time to Classify Tumours of the Stomach and the Kidneys According to Cell of Origin

Malignant tumours are traditionally classified according to their organ of origin and whether they are of epithelial (carcinomas) or mesenchymal (sarcomas) origin. By histological appearance the site of origin may often be confirmed. Using same treatment for tumours from the same organ is rational only when there is no principal heterogeneity between the tumours of that organ. Organ tumour heterogeneity is typical for the lungs with small cell and non-small cell tumours, for the kidneys where clear cell renal carcinoma (CCRCC) is the dominating type among other subgroups, and in the stomach with adenocarcinomas of intestinal and diffuse types. In addition, a separate type of neuroendocrine tumours (NETs) is found in most organs. Every cell type able to divide may develop into a tumour, and the different subtypes most often reflect different cell origin. In this article the focus is on the cells of origin in tumours arising in the stomach and kidneys and the close relationship between normal neuroendocrine cells and NETs. Furthermore, that the erythropoietin producing cell may be the cell of origin of CCRCC (a cancer with many similarities to NETs), and that gastric carcinomas of diffuse type may originate from the ECL cell, whereas the endodermal stem cell most probably gives rise to cancers of intestinal type.

The lncRNA Signatures of Genome Instability to Predict Survival in Patients with Renal Cancer

Long noncoding RNAs (lncRNAs) exert an increasingly important effect on genome instability and the prognosis of cancer patients. The present research established a computational framework originating from the mutation assumption combining lncRNA expression profile and somatic mutation profile in the genome of renal cancer to assess the effect of lncRNAs on the gene instability of renal cancer. A total of 45 differentially expressed lncRNAs were evaluated to be genome-instability-associated from the high and low cumulative somatic mutations groups. Then we established a prognosis model based on three genome-instability-associated lncRNAs (AC156455.1, AC016405.3, and LINC01234)-GlncScore. The GlncScore was then verified in testing cohort and the total TCGA renal cancer cohort. The GlncScore was evaluated to have an accurate prediction for the survival of patients. Furthermore, GlncScore was associated with somatic mutation patterns, indicating its capacity of reflecting genome instability in renal cancer. In conclusion, this study evaluated the effect of lncRNAs on genome instability of renal cancer and provided new hidden cancer biomarkers related to genome instability in renal cancer.

A MUCINs expression signature impacts overall survival in patients with clear cell renal cell carcinoma

Background

Kidney cancer, especially clear cell renal cell carcinoma (ccRCC), is one of the most common cancers in the urinary system. Previous studies suggested that certain members of MUCINs could serve as independent predictors for the survival of ccRCC patients. None of them, however, is robust enough to predict prognosis accurately.

Objective

To analyze the correlation of MUCINs alterations and their expression levels with the prognosis of ccRCC patients and develop a prognosis‐related predictor.

Methods

We applied whole‐exome sequencing in samples from 22 Chinese ccRCC patients to identify genetic alterations in MUCIN genes and analyzed their genetic alterations, expression, and correlation with survival using the TCGA, GSE73731, and GSE29069 datasets.

Result

Genetic alternations in MUCINs were identified in 91% and 51% of ccRCC patients in our cohort and the TCGA database, respectively. No correlation with survival was found for the genetic alterations. Using unsupervised clustering analysis of gene expression, we identified two major clusters of MUCIN expression patterns. Cluster 1 was characterized by a global overexpression of MUC1, MUC12, MUC13, MUC16, and OVGP1; and cluster 2 was characterized by a global overexpression of MUC4, MUC5B, MUC6, MUC20, EMCN, and MCAM. Patients with cluster 1 expression pattern had significantly shorter overall survival time and worse clinical features, including higher tumor grades and metastasis. Meanwhile, they had a higher level of mutation counts and more infiltrated immune cells, but lower enrichment in angiogenesis signature genes. A five‐MUCINs expression signature was constructed from cluster 1, and notably, it was demonstrated to be associated with shorter overall survival. A similar worse clinical feature, lower angiogenesis but the more immune signature, was identified in samples presented with signature 1. In the validation data set GSE29069, patients with signature 1 were also associated with a trend of poor survival outcomes.

Conclusion

We established a five‐MUCINs expression signature as a new prognostic marker for ccRCC. The distinct tumor microenvironment feature between the two signatures may further affect ccRCC patients’ clinical management.

Impact of Extracellular Matrix Components to Renal Cell Carcinoma Behavior

Renal cell carcinoma (RCC) represents the main renal tumors and are highly metastatic. They are heterogeneous tumors and are subdivided in 12 different subtypes where clear cell RCC (ccRCC) represents the main subtype. Tumor extracellular matrix (ECM) is composed, in RCC, mainly of different fibrillar collagens, fibronectin, and components of the basement membrane such as laminin, collagen IV, and heparan sulfate proteoglycan. Little is known about the role of these ECM components on RCC cell behavior. Analysis from The Human Protein Atlas dataset shows that high collagen 1 or 4A2, fibronectin, entactin, or syndecan 3 expression is associated with poor prognosis whereas high collagen 4A3, syndecan 4, or glypican 4 expression is associated with increased patient survival. We then analyzed the impact of collagen 1, fibronectin 1 or Matrigel on three different RCC cell lines (Renca, 786-O and Caki-2) in vitro. We found that all the different matrices have little effect on RCC cell proliferation. The three cell lines adhere differently on the three matrices, suggesting the involvement of a different set of integrins. Among the 3 matrices tested, collagen 1 is the only component able to increase migration in the three cell lines as well as MMP-2 and 9 activity. Moreover, collagen 1 induces MMP-2 mRNA expression and is implicated in the epithelial to mesenchymal transition of two RCC cell lines via Zeb2 (Renca) or Snail 2 (Caki-2) mRNA expression. Taken together, our results show that collagen 1 is the main component of the ECM that enhances tumor cell invasion in RCC, which is important for the metastasic process.

Comparison of 3-dimensional laparoscopy and conventional laparoscopy in the treatment of complex renal tumor with partial nephrectomy: A propensity score-matching analysis

To compare the efficacies of 3-dimensional laparoscopic partial nephrectomy and conventional laparoscopic partial nephrectomy for complex renal tumors. The complex renal tumors was defined as Preoperative Aspects and Dimensions Used for an anatomical (PADAU) ≥10, including some cT1b tumors.This was a retrospective analysis of patients with local complex renal tumors who presented to our hospital from January 2014 to January 2018. All patients were managed with laparoscopic partial nephrectomy (LPN) or 3-dimensional partial nephrectomy (3DLPN).There were 48 patients in the LPN group and 60 in the 3DLPN group. In the matched groups, demographic and tumor characteristics including Charlson Comorbidity Index, PADUA, based on the preoperative images, were similar. By contrast, 3DLPN achieved better results in terms of warm ischemia time (19 vs 27 minutes), operation time (105 vs 128 minutes), postoperative complications (14.9% vs 23.4%), and marginal width (0.6 cm vs 0.4 cm). We found statistically significant differences in terms of length of stay, estimated blood loss (EBL), positive surgical margin (PSM), and conversion to open or radical nephrectomy (RN). Median follow-up time was 17 and 18.5 months for the LPN and 3DLPN groups, respectively. The recovery of renal function (% change eGFR, 0 vs -8.7) was significantly different between the 3DLPN and LPN groups, whereas 12-month recurrence-free survival did not differ.Both 3-dimensional laparoscopic nephron-sparing nephrectomy and conventional laparoscopic partial nephrectomy are safe, effective, and acceptable approaches to treating complex renal tumors, while the former may facilitate tumor resection and renorrhaphy for challenging cases, offering a minimally invasive surgical option for patients who may otherwise require open surgery.

Surgical treatment for Xp11.2 translocation renal cell carcinoma with venous thrombus: A STROBE-compliant study

The aim of the study was to report the experience and outcomes of Xp11.2 translocation renal cell carcinoma (tRCC) patients with tumor thrombus undergoing radical nephrectomy and thrombectomy.Between January 2017 and December 2017, 66 consecutive patients with RCC and venous thrombus involvement received surgical treatment at Peking University Third Hospital. Of which, 5 patients were confirmed of Xp11.2 tRCC, 61 patients were diagnosed of non-tRCC subtypes including 45 ccRCCs, 10 pRCCs, and 6 other subtypes. Demographic, clinical, operation, pathological and follow-up data were extracted for analysis. Prognostic factors were identified by Cox regression analysis.All the patients received radical nephrectomy and thrombectomy successfully. During a median follow-up of 18 months, 5 patients in non-tRCC group and 1 patient in tRCC group died of disease progression. Survival analysis revealed that Xp11.2 tRCC patients experienced shorter DFS than non-tRCC patients, however, there is no significant difference in OS between two groups. Xp11.2 tRCC histological subtype and presence of metastasis at diagnosis were identified as independent negative factors of DFS by multivariate analysis.Radical nephrectomy with thrombectomy provides an acceptable efficacy for tRCC patients with tumor thrombus extending into the venous system. In addition, multimodality treatment should be considered for advanced Xp11.2 RCCs as this subtype was a negative prognostic factor of DFS.

Prediction of ISUP grading of clear cell renal cell carcinoma using support vector machine model based on CT images

BACKGROUND

To explore whether radiomics combined with computed tomography (CT) images can be used to establish a model for differentiating high grade (International Society of Urological Pathology [ISUP] grade III-IV) from low-grade (ISUP I-II) clear cell renal cell carcinoma (ccRCC).

METHODS

For this retrospective study, 3-phase contrast-enhanced CT images were collected from 227 patients with pathologically confirmed ISUP-grade ccRCC (155 cases in the low-grade group and 72 cases in the high-grade group). First, we delineated the largest dimension of the tumor in the corticomedullary and nephrographic CT images to obtain the region of interest. Second, variance selection, single variable selection, and the least absolute shrinkage and selection operator were used to select features in the corticomedullary phase, nephrographic phase, and 2-phase union samples, respectively. Finally, a model was constructed using the optimal features, and the receiver operating characteristic curve and area under the curve (AUC) were used to evaluate the predictive performance of the features in the training and validation queues. A Z test was employed to compare the differences in AUC values.

RESULTS

The support vector machine (SVM) model constructed using the screening features for the 2-stage joint samples can effectively distinguish between high- and low-grade ccRCC, and obtained the highest prediction accuracy. Its AUC values in the training queue and the validation queue were 0.88 and 0.91, respectively. The results of the Z test showed that the differences between the 3 groups were not statistically significant.

CONCLUSION

The SVM model constructed by CT-based radiomic features can effectively identify the ISUP grades of ccRCC.

Nomograms for predicting long-term overall survival and disease-specific survival of patients with clear cell renal cell carcinoma

Objectives

The aim of this study was to establish comprehensive and practical nomograms, based on significant clinicopathological parameters, for predicting the overall survival (OS) and the disease-specific survival (DSS) of patients with clear cell renal cell carcinoma (ccRCC).

Patients and methods

The data of 35,151 ccRCC patients, diagnosed between 2004 and 2014, were obtained from the database of the Surveillance, Epidemiology, and End Results (SEER) program. The Kaplan–Meier method and Cox proportional hazards regression model were used to evaluate the prognostic effects of multiple clinicopathological variables on survival. Based on Cox models, a nomogram was constructed to predict the probabilities of OS and DSS for an individual patient. The predictive performance of nomograms was evaluated using the concordance index (C-index) and calibration curves.

Results

According to univariate and multivariate analyses, age at diagnosis, sex, race, marital status, surgical approach, tumor node metastasis (TNM) stage, and Fuhrman grade significantly correlated with the survival outcomes. These characteristics were used to establish nomograms. The nomograms showed good accuracy in predicting 3-, 5-, and 10-year OS and DSS, with a C-index of 0.79 (95% CI, 0.79–0.80) for OS and 0.87 (95% CI, 0.86–0.88) for DSS. All calibration curves revealed excellent consistency between predicted and actual survival.

Conclusion

Nomograms were developed to predict death from ccRCC treated with nephrectomy. These new prognostic tools could aid in improving the predictive accuracy of survival outcomes, thus leading to reasonable individualized treatment.

Metabolomic study of human tissue and urine in clear cell renal carcinoma by LC-HRMS and PLS-DA

Renal cell carcinoma (RCC) is the most prevalent and lethal malignancy of the kidney. Despite all the efforts made, no tissue biomarker is currently used in the clinical management of patients with kidney cancer. A search for possible biomarkers in urine for clear cell renal cell carcinoma (ccRCC) has been conducted. Non-targeted metabolomic analyses were performed on paired samples of surgically removed renal cancer and normal tissue, as well as on urine samples. Extracts were analyzed by liquid chromatography/high-resolution mass spectrometry (LC-HRMS). Hydroxybutyrylcarnitine, decanoylcarnitine, propanoylcarnitine, carnitine, dodecanoylcarnitine, and norepinephrine sulfate were found in much higher concentrations in both cancer tissues (compared with the paired normal tissue) and in urine of cancer patients (compared with control urine). In contrast, riboflavin and acetylaspartylglutamate (NAAG) were present at significantly higher concentrations both in normal kidney tissue as well as in urine samples of healthy persons. This preliminary study resulted in the identification of several compounds that may be considered potential clear cell renal carcinoma biomarkers. Graphical abstract PLS-DA plot based on LC-MS data for normal and cancer human tissue samples. The aim of this work was the identification of up- and downregulated compounds that could potentially serve as renal cancer biomarkers.

Expression of erythropoietin and neuroendocrine markers in clear cell renal cell carcinoma

The aim of the study was to investigate the expression of erythropoietin and neuroendocrine markers in clear cell renal cell carcinoma (CCRCC). We retrospectively reviewed the medical records and re-evaluated histopathological specimens of 33 patients with CCRCC and compared with those of 11 cases of non-CCRCC. All patients were treated with a partial or radical nephrectomy at St. Olavs Hospital, Trondheim University Hospital, between 2010 and 2016. Thirty-three patients who were diagnosed with CCRCC had a total of 35 tumours, where 34 of the tumours were CCRCC and one was papillary adenoma. Thirty-three (97%) of 34 CCRCCs were positive for erythropoietin, and the same 33 (97%) tumours demonstrated strong expression for neuron-specific enolase (NSE). Two (6%) of 34 CCRCCs had a positive reaction for synaptophysin, and three (9%) of 34 were positive for CD56. Erythropoietin and NSE were negative in non-CCRCCs, and chromogranin A was negative in all tumours. The above findings suggest that there is a strong association between CCRCC and the expression of erythropoietin and NSE.

Renal Cell Carcinoma: A Study through NMR-Based Metabolomics Combined with Transcriptomics

Renal cell carcinoma (RCC) is a heterogeneous cancer often showing late symptoms. Until now, some candidate protein markers have been proposed for its diagnosis. Metabolomics approaches have been applied, predominantly using Mass Spectrometry (MS), while Nuclear Magnetic Resonance (NMR)-based studies remain limited. There is no study about RCC integrating NMR-based metabolomics with transcriptomics. In this work, ¹H-NMR spectroscopy combined with multivariate statistics was applied on urine samples, collected from 40 patients with clear cell RCC (ccRCC) before nephrectomy and 29 healthy controls; nine out of 40 patients also provided samples one-month after nephrectomy. We observed increases of creatine, alanine, lactate and pyruvate, and decreases of hippurate, citrate, and betaine in all ccRCC patients. A network analysis connected most of these metabolites with glomerular injury, renal inflammation and renal necrosis/cell death. Interestingly, intersecting metabolites with transcriptomic data from CD133+/CD24+ tumoral renal stem cells isolated from ccRCC patients, we found that both genes and metabolites differentially regulated in ccRCC patients belonged to HIF-α signaling, methionine and choline degradation, and acetyl-CoA biosynthesis. Moreover, when comparing urinary metabolome of ccRCC patients after nephrectomy, some processes, such as the glomerular injury, renal hypertrophy, renal necrosis/cell death and renal proliferation, were no more represented.

Incidence of Clear Cell Papillary Renal Cell Carcinoma in Low-Grade Renal Cell Carcinoma Cases

Clear cell papillary renal cell carcinoma (CCPRCC) is a recently recognized subtype of renal cell carcinoma entity after 2004 World Health Organization classification of renal tumors. CCPRCC has unique histomorphological and immunohistochemical characteristics. The distinction of CCPRCC from renal cell carcinoma (RCC) with clear cell morphology is crucial because the former is considered to have a favorable clinical outcome. CCPRCC may be interpreted in the past as other renal cell carcinomas, particularly low-grade clear cell RCC. In this study, the frequency of CCPRCC in previously diagnosed low-grade RCC and its clinicopathologic features were examined. A total of 126 cases of stage T1a with low nuclear grade RCC were identified from 625 consecutive RCCs removed by radical/partial nephrectomy over 12-year period (2000-2011). Archival tissue sections were retrospectively reviewed along with patient medical charts. Eight cases (1.3% of all RCC, 6.3% of pT1a low grade RCC) with characteristic histologic features of CCPRCC were confirmed by immunohistochemical studies. Seven cases were previously diagnosed as clear cell RCC and one as multilocular cystic RCC. Radiographically, CCPRCC favored a mid-pole location in the kidneys. At a median follow-up period of 52 months (range 20-114.5 months), there were no cases of local or distant recurrence. In conclusion, CCPRCC is not uncommon among small low-grade RCC tumors. CCPRCC can be correctly recognized by its unique histomorphological features and confirmed by immunohistochemistry studies, which is important due to the excellent clinical outcome following resection.

Design, Synthesis, and Biological Activity of Sulfonamide Analogues of Antofine and Cryptopleurine as Potent and Orally Active Antitumor Agents

Due to their profound antiproliferative activity and unique mode of action, phenanthroindolizidine and phenanthroquinolizidine alkaloids, represented by antofine and cryptopleurine, have attracted attention recently as potential therapeutic agents. We have designed, synthesized, and evaluated the methanesulfonamide analogues of these natural alkaloids with the hope of improving their druglikeness. The analogues showed enhanced growth inhibition of human cancer cells compared with the parent natural products. In particular, a methanesulfonamide analogue of cryptopleurine (5b) exhibited improved bioavailability and significant antitumor activity, which suggests that 5b is a promising new anticancer agent. Our studies suggest that the inhibition of cancer cell growth by 5b is associated with the induction of G0/G1 cell cycle arrest via nicotinamide N-methyltransferase-dependent JNK activation in Caki-1 renal cancer cells. In addition, compound 5b significantly inhibited the migration and invasion of Caki-1 cancer cells by modulating the p38 MAPK signaling pathway.

Chronic oxidative stress leads to malignant transformation along with acquisition of stem cell characteristics, and epithelial to mesenchymal transition in human renal epithelial cells

Oxidative injury to cellular macromolecules has been suggested as a common pathway shared by multiple etiological factors for kidney cancer. Whether the chronic oxidative stress alone is sufficient to induce malignant transformation in human kidney cells is not clear. Therefore, the objective of this study was to evaluate the effect of H2O2-induced chronic oxidative stress on growth, and malignant transformation of HK-2 normal kidney epithelial cells. This study revealed that chronic oxidative stress causes increased growth and neoplastic transformation in normal kidney epithelial cells at non-cytotoxic dose and increased adaptation to cytotoxic level. This was confirmed by gene expression changes, cell cycle analysis, anchorage independent growth assay and in vivo tumorigenicity in nude mice. Stem cells characteristics as revealed by up-regulation of stem cell marker genes, and morphological changes indicative of EMT with up regulation of mesenchymal markers were also observed in cells exposed to chronic oxidative stress. Antioxidant NAC did not reverse the chronic oxidative stress-induced growth, and adaptation suggesting that perturbed biological function in these cells are permanent. Partial reversal of oxidative stress-induced growth, and adaptation by silencing of Oct 4 and Snail1, respectively, suggest that these changes are mediated by acquisition of stem cell and EMT characteristics. In summary, this study for the first time suggests that chronic exposure to elevated levels of oxidative stress is sufficient to induce malignant transformation in kidney epithelial cells through acquisition of stem cell characteristics. Additionally, the EMT plays an important role in increased adaptive response of renal cells to oxidative stress.

Fabrication of mAb G250-SPIO molecular magnetic resonance imaging nanoprobe for the specific detection of renal cell carcinoma in vitro

Molecular magnetic resonance imaging (mMRI) has been paid more and more attention for early diagnosis of cancer. A sensitive and specific mMRI probe plays the most important role in this technique. In this study, superparamagnetic iron oxide (SPIO) nanoparticles and mAb G250 were conjugated as mMRI probe for the detection of clear cell renal cell carcinoma (ccRCC) using 3.0-Tesla MRI in vitro. mAb G250 could specifically recognize carbonic anhydrase IX (CAIX) antigen overexpressed in ccRCC and the SPIO nanoparticles as MRI contrast agent presented excellent MRI response and good biocompatibility. The successful assembly of this nanoprobe was confirmed by UV-vis spectrum, FT-IR spectroscopy and DLS analysis. In vitro MRI study on ccRCC cells and control cells indicated that our fabricated mAb G250-SPIO nanoprobe could be used in the specific labeling of clear cell renal carcinoma cells successfully.

Prognostic Significance of Histologic Features in Canine Renal Cell Carcinomas

The prognostic significance of histologic and clinical features was evaluated in a retrospective study of 70 dogs treated with nephrectomy for renal cell carcinoma. Dogs presenting with hematuria and cachexia had significantly decreased overall and tumor-specific survival. Mitotic index (MI), nuclear size, nuclear pleomorphism, tumor differentiation, invasiveness, Fuhrman nuclear grade, and clear cell morphology were significantly associated with survival times (overall and tumor specific) in univariate analyses. A multivariate Cox proportional hazards model was constructed using stepwise selection to evaluate potential histologic predictor variables. This multivariate analysis revealed MI, defined as the number of mitotic figures in ten 400× fields, as the sole independent prognostic variable. Median survival for dogs with an MI >30 was 187 days compared with 1184 days for dogs with an MI of <10. Dogs with an intermediate MI of 10 to 30 had a median survival of 452 days. Canine renal carcinomas were categorized into the following subtypes based on histologic features and histochemical and immunohistochemical staining: (1) clear cell, (2) chromophobe, (3) papillary, and (4) multilocular cystic renal cell carcinomas. Clear cell carcinoma was diagnosed in 6 of 70 (9%) canine tumors and was associated with a significantly decreased median survival time. Papillary carcinomas were identified in 15 of 70 tumors (21%), chromophobe in 6 of 70 (9%), and the multilocular cystic variant of canine renal cell carcinoma in 3 of 70 tumors (4%). These findings facilitate uniform categorization of canine renal cell carcinoma and provide veterinary pathologists with criteria to determine prognostic information.

Epigenetic silencing of Na,K-ATPase β 1 subunit gene ATP1B1 by methylation in clear cell renal cell carcinoma

The Na,K-ATPase or sodium pump carries out the coupled extrusion of Na(+) and uptake of K(+) across the plasma membranes of cells of most higher eukaryotes. We have shown earlier that Na,K-ATPase-β 1 (NaK-β) protein levels are highly reduced in poorly differentiated kidney carcinoma cells in culture and in patients' tumor samples. The mechanism(s) regulating the expression of NaK-β in tumor tissues has yet to be explored. We hypothesized that DNA methylation plays a role in silencing the NaK-β gene (ATP1B1) expression in kidney cancers. In this study, to the best of our knowledge we provide the first evidence that ATP1B1 is epigenetically silenced by promoter methylation in both renal cell carcinoma (RCC) patients' tissues and cell lines. We also show that knockdown of the von Hippel-Lindau (VHL) tumor suppressor gene in RCC cell lines results in enhanced ATP1B1 promoter AT hypermethylation, which is accompanied by reduced expression of NaK-β. Furthermore, treatment with 5-Aza-2'-deoxycytidine rescued the expression of ATP1B1 mRNA as well as NaK-β protein in these cells. These data demonstrate that promoter hypermethylation is associated with reduced NaK-β expression, which might contribute to RCC initiation and/or disease progression.

Identification of potential bladder cancer markers in urine by abundant-protein depletion coupled with quantitative proteomics

In this study, we evaluated the reproducibility of abundant urine protein depletion by hexapeptide-based library beads and an antibody-based affinity column using the iTRAQ technique. The antibody-based affinity-depletion approach, which proved superior, was then applied in conjunction with iTRAQ to discover proteins that were differentially expressed between pooled urine samples from hernia and bladder cancer patients. Several proteins, including seven apolipoproteins, TIM, SAA4, and proEGF were further verified in 111 to 203 individual urine samples from patients with hernia, bladder cancer, or kidney cancer. Six apolipoproteins (APOA1, APOA2, APOB, APOC2, APOC3, and APOE) were able to differentiate bladder cancer from hernia. SAA4 was significantly increased in bladder cancer subgroups, whereas ProEGF was significantly decreased in bladder cancer subgroups. Additionally, the combination of SAA4 and ProEGF exhibited higher diagnostic capacity (AUC=0.80 and p<0.001) in discriminating bladder cancer from hernia than either marker alone. Using MetaCore software to interpret global changes of the urine proteome caused by bladder cancer, we found that the most notable alterations were in immune-response/alternative complement and blood-coagulation pathways. This study confirmed the clinical significance of the urine proteome in the development of non-invasive biomarkers for the detection of bladder cancer.

BIOLOGICAL SIGNIFICANCE

In this study, we evaluated the reproducibility of abundant urine protein depletion by hexapeptide-based library beads and an antibody-based affinity column using the iTRAQ technique. The antibody-based affinity-depletion approach, which proved superior, was then applied in conjunction with iTRAQ to discover proteins that were differentially expressed between pooled urine samples from hernia and bladder cancer patients. Several proteins, including seven apolipoproteins, TIM, SAA4, and proEGF were further verified in 111 to 203 individual urine samples from patients with hernia, bladder cancer, or kidney cancer. SAA4 was significantly increased in bladder cancer subgroups, whereas ProEGF was significantly decreased in bladder cancer subgroups. Additionally, the combination of SAA4 and ProEGF exhibited higher diagnostic capacity in discriminating bladder cancer from hernia than either marker alone. A marker panel composed by two novel biomarker candidates, SAA4 and proEGF, was first discovered and verified successfully using Western blotting. To the best of our knowledge, the associations of urinary SAA4 and proEGF with bladder tumor and kidney cancer have not been mentioned before. In the present study, we discovered and verified SAA4 and proEGF as potential bladder cancer biomarker for the first time.

Collecting Duct Carcinoma Presenting Uncommon Metastatic Features

Collecting duct carcinoma (CDC) is a relatively rare subtype of renal cell carcinoma (RCC) which has an aggressive course with an extremely poor prognosis. Here we report on a case of CDC in a 29-year-old woman who showed rapid disease progression with some uncommon clinical features including extensive vertebral metastases and invasion of the spinal meninges. The patient developed paraplegia and died 9 months after the diagnosis of CDC. The features of the fulminant clinical course with the lesions of the meninges, although rare, are important for the accumulation of experience of this rare disease.

Genome-wide CpG island methylation analysis implicates novel genes in the pathogenesis of renal cell carcinoma

In order to identify novel candidate tumor suppressor genes (TSGs) implicated in renal cell carcinoma (RCC), we performed genome-wide methylation profiling of RCC using the HumanMethylation27 BeadChips to assess methylation at > 14,000 genes. Two hundred and twenty hypermethylated probes representing 205 loci/genes were identified in genomic CpG islands. A subset of TSGs investigated in detail exhibited frequent tumor methylation, promoter methylation associated transcriptional silencing and reactivation after demethylation in RCC cell lines and down-regulation of expression in tumor tissue (e.g., SLC34A2 specifically methylated in 63% of RCC, OVOL1 in 40%, DLEC1 in 20%, TMPRSS2 in 26%, SST in 31% and BMP4 in 35%). As OVOL1, a putative regulator of c-Myc transcription, and SST (somatostatin) had not previously been linked to cancer and RCC, respectively, we (1) investigated their potential relevance to tumor growth by RNAi knockdown and found significantly increased anchorage-independent growth and (2) demonstrated that OVOL1 knockdown increased c-Myc mRNA levels.

Characterization of N-diethylnitrosamine-initiated and ferric nitrilotriacetate-promoted renal cell carcinoma experimental model and effect of a tamarind seed extract against acute nephrotoxicity and carcinogenesis

Renal cell carcinoma (RCC), the commonest malignancy in adult kidney, lacks of early signs, resulting often in metastasis at first diagnosis. N-Diethylnitrosamine (DEN)-initiated and ferric nitrilotriacetate (FeNTA)-promoted RCC may be a useful experimental model, but it is not well characterized. In this study, histological alterations and oxidative stress markers were analyzed at different times throughout RCC development, histological subtype was re-evaluated in the light of current classification, and a tamarind seed extract (TSE) effect was examined. Male Wistar rats experimental groups were control, TSE, DEN, DEN+FeNTA, and TSE+DEN+FeNTA. TSE was given 2 weeks before DEN administration (200 mg/kg) and throughout the experiment. Fourteen days after DEN treatment, two FeNTA doses (9 mg Fe/kg) for acute nephrotoxicity study, and increasing FeNTA doses (3-9 mg Fe/kg) twice a week for 16 weeks for carcinogenesis protocol, were administered. In acute study, necrosis and renal failure were observed and TSE ameliorated them. Throughout carcinogenesis protocol, preneoplastic lesions were observed since 1 month of FeNTA treatment, which were more evident at 2 months, when also renal cysts and RCC were already detected. RCC tumors were obtained without changes in renal function, and clear cell histological subtype was identified in all cases. 4-Hydroxy-2-nonenal and 3-nitro-L: -tyrosine levels increased progressively throughout protocol. TSE decreased both oxidative stress markers and, although there was no statistical difference, it delayed RCC progress and decreased its incidence (21 %). This study brings an insight of the time course events in this carcinogenesis model, identifies clear cell subtype and establishes TSE renoprotective effects.

Three-dimensional tumour volume and cancer-specific survival for patients undergoing nephrectomy to treat pT1 clear-cell renal cell carcinoma

Study Type - Prognosis (case series) Level of Evidence 4. What's known on the subject? and What does the study add? The positive association of tumour size (largest tumour dimension on pathology review) and risk of RCC progression and survival following nephrectomy is well documented. Moreover, several clinicopathological scoring systems (i.e. nomograms and algorithms) have been developed to predict outcomes for surgically treated RCC patients and each of these includes tumour size as an independent predictor of RCC outcome. There is still the question of whether information on three-dimensional tumour volume (cm(3) ) can provide additional prognostic information, particularly among patients with small pT1 tumours where the range of tumour size is more limited. Our study demonstrates that increasing tumour volume is associated with a greater risk of RCC-specific death in patients with pT1 ccRCC, with a more pronounced association in pT1a tumours specifically. In addition, we observed evidence that tumour volume may provide more accurate prognostic information than tumour size alone in pT1a patients. Tumour volume may add prognostic information specifically in pT1a RCC.

OBJECTIVE

To address whether information on three-dimensional tumour volume can provide additional prognostic information for patients with small, localized renal cell carcinoma (RCC) superior to tumour size alone.

PATIENTS AND METHODS

We identified 955 patients treated with radical nephrectomy or nephron-sparing surgery for unilateral, sporadic, pT1, pN0/NX, M0, non-cystic clear-cell RCC (ccRCC) between 1980 and 2004, including 515 pT1a patients and 440 pT1b patients. • We estimated tumour volume using three tumour dimensions recorded on pathological analysis and the equation for the volume of an ellipsoid [π/6 (length × width × height)]. For tumour size alone, we used the maximum tumour diameter recorded on pathological analysis. • Univariate and multivariable associations with RCC-specific death were evaluated using Cox proportional hazards regression models summarized with hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

Among pT1a patients, the risk of RCC death associated with having a tumour volume above the median (HR = 4.55; 95% CI, 1.30-15.83; P= 0.018) was markedly higher than having a tumour size above the median (HR = 2.55; 95% CI 0.83-7.85; P= 0.10). Comparison of concordance (c) index values further supported the idea that additional prognostic information was provided by tumour volume (c= 0.659) compared with tumour size (c= 0.600) for pT1a patients. • Among pT1b patients, we noted that associations of tumour volume and tumour size with RCC-specific death were similar. • Multivariable adjustment did not alter our findings.

CONCLUSIONS

Tumour volume could provide valuable prognostic information for patients with pT1a ccRCC but not pT1b ccRCC. • Future investigations are needed to confirm this finding, explore other RCC subtypes and evaluate accuracy of tumour volume determination on radiographic imaging for potential patient management before surgery.

Prognostic variables and nomograms for renal cell carcinoma

The term renal cell carcinoma (RCC) is used to describe a heterogeneous group of tumors that vary histologically, genetically and molecularly. Extensive research has been conducted to identify characteristics that predict outcomes among patients with RCC. In addition to histological subtype these include tumor size, patient age, mode of presentation and various hematological indices, among others. Several groups have incorporated these clinical and pathological features into nomograms which help the clinician better define individual patient prognosis and direct the optimum therapeutic approach. In the present article we review these prognostic variables and nomograms for RCC.

Nicotinamide N-methyltransferase induces cellular invasion through activating matrix metalloproteinase-2 expression in clear cell renal cell carcinoma cells

Nicotinamide N-methyltransferase (NNMT) was recently identified as one clear cell renal cell carcinoma (ccRCC)-associated gene by analyzing full-length complementary DNA-enriched libraries of ccRCC tissues. The aim of this study is to investigate the potential role of NNMT in cellular invasion. A strong NNMT expression is accompanied with a high invasive activity in ccRCC cell lines, and small interfering RNA-mediated NNMT knockdown effectively suppressed the invasive capacity of ccRCC cells, whereas NNMT overexpression markedly enhanced that of human embryonic kidney 293 (HEK293) cells. A positive correlation between the expression of NNMT and matrix metallopeptidase (MMP)-2 was found in ccRCC cell lines and clinical tissues. The treatment of blocking antibody or inhibitor specific to MMP-2 significantly suppressed NNMT-dependent cellular invasion in HEK293 cells. Furthermore, SP-1-binding region of MMP-2 promoter was found to be essential in NNMT-induced MMP-2 expression. The specific inhibitors of PI3K/Akt signaling markedly decreased the binding of SP1 to MMP-2 promoter as shown by chromatin immunoprecipitation assay. We also demonstrated that PI3K/Akt pathway plays a role in NNMT-dependent cellular invasion and MMP-2 activation. Moreover, short hairpin RNA-mediated knockdown of NNMT expression efficiently inhibited the growth and metastasis of ccRCC cells in non-obese diabetic severe combined immunodeficiency mice. Taken together, the present study suggests that NNMT has a crucial role in cellular invasion via activating PI3K/Akt/SP1/MMP-2 pathway in ccRCC.

Epigenetics of renal cell carcinoma: the path towards new diagnostics and therapeutics

Aberrant DNA methylation, in particular promoter hypermethylation and transcriptional silencing of tumor suppressor genes, has an important role in the development of many human cancers, including renal cell carcinoma (RCC). Indeed, apart from mutations in the well studied von Hippel-Lindau gene (VHL), the mutation frequency rates of known tumor suppressor genes in RCC are generally low, but the number of genes found to show frequent inactivation by promoter methylation in RCC continues to grow. Here, we review the genes identified as epigenetically silenced in RCC and their relationship to pathways of tumor development. Increased understanding of RCC epigenetics provides new insights into the molecular pathogenesis of RCC and opportunities for developing novel strategies for the diagnosis, prognosis and management of RCC.

Accurate molecular classification of renal tumors using microRNA expression

Subtypes of renal tumors have different genetic backgrounds, prognoses, and responses to surgical and medical treatment, and their differential diagnosis is a frequent challenge for pathologists. New biomarkers can help improve the diagnosis and hence the management of renal cancer patients. We extracted RNA from 71 formalin-fixed paraffin-embedded (FFPE) renal tumor samples and measured expression of more than 900 microRNAs using custom microarrays. Clustering revealed similarity in microRNA expression between oncocytoma and chromophobe subtypes as well as between conventional (clear-cell) and papillary tumors. By basing a classification algorithm on this structure, we followed inherent biological correlations and could achieve accurate classification using few microRNAs markers. We defined a two-step decision-tree classifier that uses expression levels of six microRNAs: the first step uses expression levels of hsa-miR-210 and hsa-miR-221 to distinguish between the two pairs of subtypes; the second step uses either hsa-miR-200c with hsa-miR-139-5p to identify oncocytoma from chromophobe, or hsa-miR-31 with hsa-miR-126 to identify conventional from papillary tumors. The classifier was tested on an independent set of FFPE tumor samples from 54 additional patients, and identified correctly 93% of the cases. Validation on qRT-PCR platform demonstrated high correlation with microarray results and accurate classification. MicroRNA expression profiling is a very effective molecular bioassay for classification of renal tumors and can offer a quantitative standardized complement to current methods of tumor classification.

Identification of candidate tumour suppressor genes frequently methylated in renal cell carcinoma

Promoter region hyermethylation and transcriptional silencing is a frequent cause of tumour suppressor gene (TSG) inactivation in many types of human cancers. Functional epigenetic studies, in which gene expression is induced by treatment with demethylating agents, may identify novel genes with tumour-specific methylation. We used high-density gene expression microarrays in a functional epigenetic study of 11 renal cell carcinoma (RCC) cell lines. Twenty-eight genes were then selected for analysis of promoter methylation status in cell lines and primary RCC. Eight genes (BNC1, PDLIM4, RPRM, CST6, SFRP1, GREM1, COL14A1 and COL15A1) showed frequent (>30% of RCC tested) tumour-specific promoter region methylation. Hypermethylation was associated with transcriptional silencing. Re-expression of BNC1, CST6, RPRM and SFRP1 suppressed the growth of RCC cell lines and RNA interference knock-down of BNC1, SFRP1 and COL14A1 increased the growth of RCC cell lines. Methylation of BNC1 or COL14A1 was associated with a poorer prognosis independent of tumour size, stage or grade. The identification of these epigenetically inactivated candidate RCC TSGs can provide insights into renal tumourigenesis and a basis for developing novel therapies and biomarkers for prognosis and detection.

Alteration of gene expression signatures of cortical differentiation and wound response in lethal clear cell renal cell carcinomas

Clear cell renal cell carcinoma (ccRCC) is the most common malignancy of the adult kidney and displays heterogeneity in clinical outcomes. Through comprehensive gene expression profiling, we have identified previously a set of transcripts that predict survival following nephrectomy independent of tumor stage, grade, and performance status. These transcripts, designated as the SPC (supervised principal components) gene set, show no apparent biological or genetic features that provide insight into renal carcinogenesis or tumor progression. We explored the relationship of this gene list to a set of genes expressed in different anatomical segments of the normal kidney including the cortex (cortex gene set) and the glomerulus (glomerulus gene set), and a gene set expressed after serum stimulation of quiescent fibroblasts (the core serum response or CSR gene set). Interestingly, the normal cortex, glomerulus (part of the normal renal cortex), and CSR gene sets captured more than 1/5 of the genes in the highly prognostic SPC gene set. Based on gene expression patterns alone, the SPC gene set could be used to sort samples from normal adult kidneys by the anatomical regions from which they were dissected. Tumors whose gene expression profiles most resembled the normal renal cortex or glomerulus showed better survival than those that did not, and those with expression features more similar to CSR showed poorer survival. While the cortex, glomerulus, and CSR signatures predicted survival independent of traditional clinical parameters, they were not independent of the SPC gene list. Our findings suggest that critical biological features of lethal ccRCC include loss of normal cortical differentiation and activation of programs associated with wound healing.

2009 update on the classification of renal epithelial tumors in adults

The classification of kidney tumors in adults expands rapidly with new categories recently incorporated. This will result in the modification of the current 2004 World Health Organization (WHO) classification of the adult renal epithelial neoplasms. Emphasis should be placed in defining risk groups categorized as malignant or benign tumors, including a category of tumors with low malignant potential to accommodate recently recognized categories with extremely good prognosis after surgery. Unusual tumors such as familial renal cell carcinoma (RCC), translocation RCC, renal cell carcinoma after neuroblastoma, tubular mucinous and spindle cell carcinoma, and mixed epithelial and stromal tumors are also presented. A number of recently described entities and morphologic variants of classical categories deserve recognition since they can be important in differential diagnosis. This review emphasizes clinical, pathological and genetic features defining renal epithelial tumors in adults.