A clearer view of the molecular complexity of clear cell renal cell carcinoma

Expression and Mutation Patterns of PBRM1, BAP1 and SETD2 Mirror Specific Evolutionary Subtypes in Clear Cell Renal Cell Carcinoma

Bi-allelic inactivation of the VHL gene on chromosome 3p is the characteristic feature in most clear cell renal cell carcinomas (ccRCC). Frequent gene alterations were also identified in SETD2, BAP1 and PBRM1, all of which are situated on chromosome 3p and encode histone/chromatin regulators. The relationship between gene mutation, loss of protein expression and the correlations with clinicopathological parameters is important for the understanding of renal cancer progression. We analyzed PBRM1 and BAP1 protein expression as well as the tri-methylation state of H3K36 as a surrogate marker for SETD2 activity in more than 700 RCC samples. In ccRCC loss of nuclear PBRM1 (68%), BAP1 (40%) and H3K36me3 (47%) expression was significantly correlated with each other, advanced tumor stage, poor tumor differentiation (P < .0001 each), and necrosis (P < .005) Targeted next generation sequencing of 83 ccRCC samples demonstrated a significant association of genetic mutations in PBRM1, BAP1, and SETD2 with absence of PBRM1, BAP1, and HEK36me3 protein expression (P < .05, each). By assigning the protein expression patterns to evolutionary subtypes, we revealed similar clinical phenotypes as suggested by TRACERx Renal. Given their important contribution to tumor suppression, we conclude that combined functional inactivation of PBRM1, BAP1, SETD2 and pVHL is critical for ccRCC progression.

Cullin 5 is a novel candidate tumor suppressor in renal cell carcinoma involved in the maintenance of genome stability

Clear cell renal cell carcinoma (ccRCC) is intimately associated with defects in ubiquitin-mediated protein degradation. Herein, we report that deficiency in the E3 ligase subunit cullin 5 (CUL5) promotes chromosomal instability and is an independent negative prognostic factor in ccRCC. CUL5 was initially identified in an RNA interference screen as a novel regulator of centrosome duplication control. We found that depletion of CUL5 rapidly promotes centriole overduplication and mitotic errors. Downregulation of CUL5 also caused an increase of DNA damage that was found to involve impaired DNA double-strand break repair. Using immunohistochemistry, CUL5 protein expression was found to be below detection level in the majority of RCCs. A re-analysis of the TCGA ccRCC cohort showed that a reduced CUL5 gene expression or CUL5 deletion were associated with a significantly worse overall patient survival. In conclusion, our results indicate that CUL5 functions as a novel tumor suppressor with prognostic relevance in ccRCC and is critically involved in the maintenance of genome stability.

Biocompatible carbon-doped MoSe2 nanoparticles as a highly efficient targeted agent for human renal cell carcinoma

MoSe₂ is a typical transition-metal dichalcogenide material, and many researches have been focused on using its property of near infrared strong absorption for laser mediated photothermal cancer treatment. However, the anti-canter effect of MoSe₂ and its possible mechanism in renal cell carcinoma (RCC) is still unclear. RCC has high incidence of metastasis, which is known as one of the most lethal malignancies in the urological system. This study revealed that the carbon-doped MoSe₂ particles can obviously inhibit proliferation for 786-O and ACHN cells. Meanwhile, the carbon-doped MoSe₂ nanoparticles have little impact on the viability of KH-2 cells in vitro. The mechanism analysis revealed that the carbon-doped MoSe₂ particles have hydrogen bond effect in aqueous solution, and the particle aggregation effect caused the KH-2 cells to have high viability. The carbon-doped MoSe₂ nanoparticles with minimal toxicity may be a potential therapeutic candidate against RCC.

HK-2 cells have weak cellular uptake efficiency leading to high viability with carbon-doped MoSe₂ nanoparticles.

Lipophagy in nonliver tissues and some related diseases: Pathogenic and therapeutic implications

Lipid autophagy (lipophagy) is defined as a selective autophagy process in which some intracellular lipid droplets are selectively degraded by autophagic lysosomes pathway. The occurrence of lipophagy was first discovered in liver tissues. Additionally, abundant evidence indicated that the occurrence of hepatic lipophagy has been implicated in many liver diseases including fatty liver diseases, nonalcoholic fatty liver diseases, liver fibrosis, and liver cirrhosis. However, recent studies suggested that hepatic lipophagy occurs not only in liver tissue but also in other nonliver tissues and cells. Furthermore, the occurrence of lipophagy plays a crucial role in nonliver tissues and some related diseases. For instance, lipophagy relieves insulin resistance in adipose tissue from obesity patient with type 2 diabetes. Additionally, lipophagy has the ability to remit neurodegenerative diseases by reducing activity-dependent neurodegeneration in nervous tissue. Lipophagy decreases muscle lipid accumulation and accordingly improves lipid storage myopathy in muscle tissue. Moreover, lipophagy alleviates the malignancy and metastasis of cancer in clear renal cell carcinoma tissue. Lipophagy is also involved in other processes, such as spermatogenesis, osteoblastogenesis, and mucosal ulceration. In conclusion, targeting lipophagy may be a critical regulator and a new therapeutic strategy for nonliver tissues and some related diseases.

The Association Between Ascorbate and the Hypoxia-Inducible Factors in Human Renal Cell Carcinoma Requires a Functional Von Hippel-Lindau Protein

Hypoxia-inducible transcription factors (HIFs) drive angiogenesis and cancer cell growth, contributing to an aggressive tumor phenotype. HIF-α protein levels and activity are controlled at the post-translational level by HIF hydroxylases. Hydroxylated HIF-α is recognized by the von Hippel Lindau (VHL) tumor suppressor and targeted for degradation. The HIF hydroxylases are members of the iron and 2-oxoglutarate-dependent dioxygenases, which require ascorbate as cofactor for activity. Clear cell renal cell carcinomas (ccRCC) harbor mutations in the VHL gene, whereas papillary RCC (pRCC) have a functional VHL. These natural occurring VHL variants in RCC enable the testing, in clinical samples, of the hypothesis that ascorbate modulates HIF-α levels through its role as a cofactor for the HIF hydroxylases. We measured ascorbate, HIF-1α, and HIF-2α protein and HIF downstream targets BNIP3, CA9, cyclin D1, GLUT1, and VEGF (combined to generate the HIF pathway score) in VHL-defective ccRCC (n = 73) and VHL-proficient pRCC human tumor tissue (n = 41). HIF and ascorbate levels were increased in ccRCC and pRCC tumors compared to matched renal cortex. HIF-1 and total HIF pathway activation scores were decreased with higher ascorbate in pRCC tumors (Spearman r = −0.38, p < 0.05 and r = −0.35, p < 0.05). This was not evident for ccRCC tumors. In mechanistic studies in vitro, ascorbate influenced HIF-1 activity in VHL-proficient, but not VHL-defective ccRCC cells. Our results indicate that ccRCC, which lacks a functional VHL, does not respond to ascorbate-mediated modulation of the HIF response. This contrasts with the demonstrated association between ascorbate content and the HIF pathway observed in pRCC and other tumors with a functional VHL. The results support a role for ascorbate as a modulator of HIF activity and tumor aggression in cancer types with a functional hypoxic response.

Update on the biology and management of renal cell carcinoma

Renal cell cancer (RCC) (epithelial carcinoma of the kidney) represents 2%-4% of newly diagnosed adult tumors. Over the past 2 decades, RCC has been better characterized clinically and molecularly. It is a heterogeneous disease, with multiple subtypes, each with characteristic histology, genetics, molecular profiles, and biologic behavior. Tremendous heterogeneity has been identified with many distinct subtypes characterized. There are clinical questions to be addressed at every stage of this disease, and new targets being identified for therapeutic development. The unique characteristics of the clinical presentations of RCC have led to both questions and opportunities for improvement in management. Advances in targeted drug development and understanding of immunologic control of RCC are leading to a number of new clinical trials and regimens for advanced disease, with the goal of achieving long-term disease-free survival, as has been achieved in a proportion of such patients historically. RCC management is a promising area of ongoing clinical investigation.

Mixed signals from the cell's antennae: primary cilia in cancer

Primary cilia (PC) are antenna-like organelles that protrude from most mammalian cells. They are essential for the regulation of several signaling pathways such as Hedgehog and WNT It is therefore not surprising that a dysfunction of PC is frequently associated with pathologies. Originally, PC were found to be involved in a variety of diseases commonly referred to as ciliopathies including cystic kidney diseases. Evidence is accumulating that PC play also an important role in cancer formation and regulation, which is the focus of this review.

Prognostic significance of the programmed death ligand 1 expression in clear cell renal cell carcinoma and correlation with the tumor microenvironment and hypoxia-inducible factor expression

Background

Clear cell renal cell carcinoma (ccRCC) is the most common renal malignancy. Hypoxia-inducible factors, HIF-1α and HIF-2α, are expressed in the majority of ccRCC. Targeting immune checkpoints with the blockade of PD-1 and its ligand PD-L1 reorganizes T-cell activity in tumor microenvironment and provides important antitumor responses. PD-L1 upregulation has been found to be hypoxia-inducible factor (HIF) dependent. Our aim is to demonstrate the association between PD-L1 and HIF expression and to reveal the role of PD-L1 in prognosis and its association with tumor microenvironment.

Methods

Surgical specimens from 145 patients diagnosed with ccRCC, who had undergone radical or partial nephrectomy, were retrospectively analyzed. Immunohistochemistry on tissue microarrays (TMA) was performed to demonstrate expressions of PD-L1, HIF-1α, and HIF-2α in tumor cells and PD-1, CD4, and CD8 in lymphocytes to assess lymphocyte density in tumor microenvironment.

Results

PD-L1 tumor cell expression was detected in 20/125 (13.8%) cases, which correlated with higher levels of PD-1, CD4, CD8 and HIF-2α expression. Low or high expression of HIF-1α was similar in PD-L1-positive cases. When PD-L1-positive cases were compared with negative ones, there was no significant difference in terms of prognostic factors. However, the number of WHO/ISUP grade 3–4 tumors was significantly higher in PD-L1-positive cases than in negative ones.

Conclusion

PD-L1 tumor cell expression is strongly associated with increased HIF-2α expression and presence of dense lymphocytic infiltration in ccRCCs. Our findings confirm that PD-L1 positivity is associated with high ISUP nucleolar grade. The association between PD-L1, HIF, and lymphocyte density in tumor microenvironment must be clarified and especially taken into account in combination treatment.

Proteomic distinction of renal oncocytomas and chromophobe renal cell carcinomas

BACKGROUND

Renal oncocytomas (ROs) are benign epithelial tumors of the kidney whereas chromophobe renal cell carcinoma (chRCCs) are malignant renal tumors. The latter constitute 5-7% of renal neoplasias. ROs and chRCCs show pronounced molecular and histological similarities, which renders their differentiation demanding. We aimed for the differential proteome profiling of ROs and early-stage chRCCs in order to better understand distinguishing protein patterns.

METHODS

We employed formalin-fixed, paraffin-embedded samples (six RO cases, six chRCC cases) together with isotopic triplex dimethylation and a pooled reference standard to enable cohort-wide quantitative comparison. For lysosomal-associated membrane protein 1 (LAMP1) and integrin alpha-V (ITGAV) we performed corroborative immunohistochemistry (IHC) in an extended cohort of 42 RO cases and 31 chRCC cases.

RESULTS

At 1% false discovery rate, we identified > 3900 proteins, of which > 2400 proteins were consistently quantified in at least four RO and four chRCC cases. The proteomic expression profiling discriminated ROs and chRCCs and highlighted established features such as accumulation of mitochondrial proteins in ROs together with emphasizing the accumulation of endo-lysosomal proteins in chRCCs. In line with the proteomic data, IHC showed enrichment of LAMP1 in chRCC and of ITGAV in RO.

CONCLUSION

We present one of the first differential proteome profiling studies on ROs and chRCCs and highlight differential abundance of LAMP1 and ITGAV in these renal tumors.

Integrated analysis of differentially expressed profiles and construction of a competing endogenous long non-coding RNA network in renal cell carcinoma

Background

Long non-coding RNAs (lncRNAs) play crucial roles in the initiation and progression of renal cell carcinoma (RCC) by competing in binding to miRNAs, and related competitive endogenous RNA (ceRNA) networks have been constructed in several cancers. However, the coexpression network has been poorly explored in RCC.

Methods

We collected RCC RNA expression profile data and relevant clinical features from The Cancer Genome Atlas (TCGA). A cluster analysis was explored to show different lncRNA expression patterns. Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses and gene set enrichment analysis (GSEA) were performed to analyze the functions of the intersecting mRNAs. Targetscan and miRanda bioinformatics algorithms were used to predict potential relationships among RNAs. Univariate Cox proportional hazards regression was conducted to determine the RNA expression levels and survival times.

Results

Bioinformatics analysis revealed that the expression profiles of hundreds of aberrantly expressed lncRNAs, miRNAs, and mRNAs were significantly changed between different stages of tumors and non-tumor groups. By combining the data predicted by databases with intersection RNAs, a ceRNA network consisting of 106 lncRNAs, 26 miRNAs and 69 mRNAs was established. Additionally, a protein interaction network revealed the main hub nodes (VEGFA, NTRK2, DLG2, E2F2, MYB and RUNX1). Furthermore, 63 lncRNAs, four miRNAs and 31 mRNAs were significantly associated with overall survival.

Conclusion

Our results identified cancer-specific lncRNAs and constructed a ceRNA network for RCC. A survival analysis related to the RNAs revealed candidate biomarkers for further study in RCC.

Expanding the miRNA Transcriptome of Human Kidney and Renal Cell Carcinoma

Despite advancements in therapeutic strategies, diagnostic and prognostic molecular markers of kidney cancer remain scarce, particularly in patients who do not harbour well-defined driver mutations. Recent evidence suggests that a large proportion of the human noncoding transcriptome has escaped detection in early genomic explorations. Here, we undertake a large-scale analysis of small RNA-sequencing data from both clear cell renal cell carcinoma (ccRCC) and nonmalignant samples to generate a robust set of miRNAs that remain unannotated in kidney tissues. We find that these novel kidney miRNAs are also expressed in renal cancer cell lines. Moreover, these sequences are differentially expressed between ccRCC and matched nonmalignant tissues, implicating their involvement in ccRCC biology and potential utility as tumour-specific markers of disease. Indeed, we find some of these miRNAs to be significantly associated with patient survival. Finally, target prediction and subsequent pathway analysis reveals that miRNAs previously unannotated in kidney tissues may target genes involved in ccRCC tumourigenesis and disease biology. Taken together, our results represent a new resource for the study of kidney cancer and underscore the need to characterize the unexplored areas of the transcriptome.

Hypoxia-Inducible Factor 2-Dependent Pathways Driving Von Hippel-Lindau-Deficient Renal Cancer

The most common type of the renal cancers detected in humans is clear cell renal cell carcinomas (ccRCCs). These tumors are usually initiated by biallelic gene inactivation of the Von Hippel-Lindau (VHL) factor in the renal epithelium, which deregulates the hypoxia-inducible factors (HIFs) HIF1α and HIF2α, and provokes their constitutive activation irrespective of the cellular oxygen availability. While HIF1α can act as a ccRCC tumor suppressor, HIF2α has emerged as the key HIF isoform that is essential for ccRCC tumor progression. Indeed, preclinical and clinical data have shown that pharmacological inhibitors of HIF2α can efficiently combat ccRCC growth. In this review, we discuss the molecular basis underlying the oncogenic potential of HIF2α in ccRCC by focusing on those pathways primarily controlled by HIF2α that are thought to influence the progression of these tumors.

Methods for the evaluation of biomarkers in patients with kidney and liver diseases: multicentre research programme including ELUCIDATE RCT

Background

Protein biomarkers with associations with the activity and outcomes of diseases are being identified by modern proteomic technologies. They may be simple, accessible, cheap and safe tests that can inform diagnosis, prognosis, treatment selection, monitoring of disease activity and therapy and may substitute for complex, invasive and expensive tests. However, their potential is not yet being realised.

Design and methods

The study consisted of three workstreams to create a framework for research: workstream 1, methodology – to define current practice and explore methodology innovations for biomarkers for monitoring disease; workstream 2, clinical translation – to create a framework of research practice, high-quality samples and related clinical data to evaluate the validity and clinical utility of protein biomarkers; and workstream 3, the ELF to Uncover Cirrhosis as an Indication for Diagnosis and Action for Treatable Event (ELUCIDATE) randomised controlled trial (RCT) – an exemplar RCT of an established test, the ADVIA Centaur® Enhanced Liver Fibrosis (ELF) test (Siemens Healthcare Diagnostics Ltd, Camberley, UK) [consisting of a panel of three markers – (1) serum hyaluronic acid, (2) amino-terminal propeptide of type III procollagen and (3) tissue inhibitor of metalloproteinase 1], for liver cirrhosis to determine its impact on diagnostic timing and the management of cirrhosis and the process of care and improving outcomes.

Results

The methodology workstream evaluated the quality of recommendations for using prostate-specific antigen to monitor patients, systematically reviewed RCTs of monitoring strategies and reviewed the monitoring biomarker literature and how monitoring can have an impact on outcomes. Simulation studies were conducted to evaluate monitoring and improve the merits of health care. The monitoring biomarker literature is modest and robust conclusions are infrequent. We recommend improvements in research practice. Patients strongly endorsed the need for robust and conclusive research in this area. The clinical translation workstream focused on analytical and clinical validity. Cohorts were established for renal cell carcinoma (RCC) and renal transplantation (RT), with samples and patient data from multiple centres, as a rapid-access resource to evaluate the validity of biomarkers. Candidate biomarkers for RCC and RT were identified from the literature and their quality was evaluated and selected biomarkers were prioritised. The duration of follow-up was a limitation but biomarkers were identified that may be taken forward for clinical utility. In the third workstream, the ELUCIDATE trial registered 1303 patients and randomised 878 patients out of a target of 1000. The trial started late and recruited slowly initially but ultimately recruited with good statistical power to answer the key questions. ELF monitoring altered the patient process of care and may show benefits from the early introduction of interventions with further follow-up. The ELUCIDATE trial was an ‘exemplar’ trial that has demonstrated the challenges of evaluating biomarker strategies in ‘end-to-end’ RCTs and will inform future study designs.

Conclusions

The limitations in the programme were principally that, during the collection and curation of the cohorts of patients with RCC and RT, the pace of discovery of new biomarkers in commercial and non-commercial research was slower than anticipated and so conclusive evaluations using the cohorts are few; however, access to the cohorts will be sustained for future new biomarkers. The ELUCIDATE trial was slow to start and recruit to, with a late surge of recruitment, and so final conclusions about the impact of the ELF test on long-term outcomes await further follow-up. The findings from the three workstreams were used to synthesise a strategy and framework for future biomarker evaluations incorporating innovations in study design, health economics and health informatics.

Trial registration

Current Controlled Trials ISRCTN74815110, UKCRN ID 9954 and UKCRN ID 11930.

Funding

This project was funded by the NIHR Programme Grants for Applied Research programme and will be published in full inProgramme Grants for Applied Research; Vol. 6, No. 3. See the NIHR Journals Library website for further project information.

MiR-199a-3p acts as a tumor suppressor in clear cell renal cell carcinoma

OBJECTIVES

To explore the biological function and mechanism of miR-199a-3p in clear cell renal cell carcinoma (CCRCC).

METHODS

We investigated the expression of miR-199a-3p in CCRCC through quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Over expression of miR-199a-3p was performed in CCRCC cell lines, and cell growth curve, colony formation capacity, cell invasion, wound healing and cell apoptosis assay were used for investigating the roles of miR-199a-3p in CCRCC.

RESULTS

The expression of miR-199a-3p in CCRCC tissues was significantly lower than that in para-carcinoma tissues. Functional assay showed that over expression of miR-199a-3p influenced cell growth, colony formation, cell invasion, cell migration and cell apoptosis in CCRCC cell lines.

CONCLUSIONS

Our work suggested that miR-199a-3p was related to cell growth, colony formation, cell invasion, cell migration and cell apoptosis, which might act as a tumor suppressor in CCRCC.

Timing the Landmark Events in the Evolution of Clear Cell Renal Cell Cancer: TRACERx Renal

Clear cell renal cell carcinoma (ccRCC) is characterized by near-universal loss of the short arm of chromosome 3, deleting several tumor suppressor genes. We analyzed whole genomes from 95 biopsies across 33 patients with clear cell renal cell carcinoma. We find hotspots of point mutations in the 5' UTR of TERT, targeting a MYC-MAX-MAD1 repressor associated with telomere lengthening. The most common structural abnormality generates simultaneous 3p loss and 5q gain (36% patients), typically through chromothripsis. This event occurs in childhood or adolescence, generally as the initiating event that precedes emergence of the tumor's most recent common ancestor by years to decades. Similar genomic changes drive inherited ccRCC. Modeling differences in age incidence between inherited and sporadic cancers suggests that the number of cells with 3p loss capable of initiating sporadic tumors is no more than a few hundred. Early development of ccRCC follows well-defined evolutionary trajectories, offering opportunity for early intervention.

Generation of autochthonous mouse models of clear cell renal cell carcinoma: mouse models of renal cell carcinoma

Renal cell carcinoma (RCC) is one of the 10 most common cancers worldwide, and to date, a strong systemic therapy has not been developed to treat RCC, even with the remarkable modern advances in molecular medicine mostly due to our incomplete understanding of its tumorigenesis. There is a dire unmet need to understand the etiology and progression of RCC, especially the most common subtype, clear cell RCC (ccRCC), and to develop new treatments for RCC. Genetically engineered mouse (GEM) models are able to mimic the initiation, progression, and metastasis of cancer, thus providing valuable insights into tumorigenesis and serving as perfect preclinical platforms for drug testing and biomarker discovery. Despite substantial advances in the molecular investigation of ccRCC and monumental efforts that have been performed to try to establish autochthonous animal models of ccRCC, this goal has not been achieved until recently. Here we present a review of the most exciting progress relevant to GEM models of ccRCC.

Single-cell genetic analysis validates cytopathological identification of circulating cancer cells in patients with clear cell renal cell carcinoma

CONTEXT

Circulating Rare Cells (CRC) are non-haematological cells circulating in blood. They include Circulating Cancer Cells (CCC) and cells with uncertain malignant features (CRC-UMF) according to cytomorphology. Clear cell renal cell carcinomas frequently bear a mutated Von Hippel-Lindau (VHL) gene.

AIM

To match blind genetic analysis of CRC and tumor samples with CRC cytopathological diagnosis.

RESULTS

29/30 patients harboured CRC (20 harboured CCC, 29 CRC-UMF) and 25/29 patients carried VHL mutations in their tumour. 205 single CRC (64 CCC, 141 CRC-UMF) provided genetic data. 57/57 CCC and 104/125 CRC-UMF from the 25 patients with VHL-mutated tumor carried the same VHL mutation detected in the tumor. Seven CCC and 16 CRC-UMF did not carry VHL mutations but were found in patients with wild-type VHL tumor tissue.

CONCLUSIONS

All the CCC and 83,2% (104/125) of the CRC-UMF were found to carry the same VHL mutation identified in the corresponding tumorous tissue, validating cytopathological identification of CCC in patients with clear cell renal cell carcinoma.

METHODS

The blood of 30 patients with clear cell renal cell carcinoma was treated by ISET® for CRC isolation, cytopathology and single-cell VHL mutations analysis, performed blindly and compared to VHL mutations of corresponding tumor tissues and leukocytes.

Bioinformatics and functional analyses of key genes and pathways in human clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most common type of kidney cancer. The present study was conducted to explore the mechanisms and identify the potential target genes for ccRCC using bioinformatics analysis. The microarray data of GSE15641 were screened on Gene-Cloud of Biotechnology Information (GCBI). A total of 32 ccRCC samples and 23 normal kidney samples were used to identify differentially expressed genes (DEGs) between them. Subsequently, the clustering analysis and functional enrichment analysis of these DEGs were performed, followed by protein-protein interaction (PPI) network, and pathway relation network. Additionally, the most significant module based on PPI network was selected, and the genes in the module were identified as hub genes. Furthermore, transcriptional level, translational level and survival analyses of hub genes were performed to verify the results. A total of 805 genes, 403 upregulated and 402 downregulated, were differentially expressed in ccRCC samples compared with normal controls. The subsequent bioinformatics analysis indicated that the small molecule metabolic process and the metabolic pathway were significantly enriched. A total of 7 genes, including membrane metallo-endopeptidase (MME), albumin (ALB), cadherin 1 (CDH1), prominin 1 (ROM1), chemokine (C-X-C motif) ligand 12 (CXCL12), protein tyrosine phosphatase receptor type C (PTPRC) and intercellular adhesion molecule 1 (ICAM1) were identified as hub genes. In brief, the present study indicated that these candidate genes and pathways may aid in deciphering the molecular mechanisms underlying the development of ccRCC, and may be used as therapeutic targets and diagnostic biomarkers of ccRCC.

Vhl deletion in renal epithelia causes HIF-1α-dependent, HIF-2α-independent angiogenesis and constitutive diuresis

One of the earliest requirements for the formation of a solid tumor is the establishment of an adequate blood supply. Clear cell renal cell carcinomas (ccRCC) are highly vascularized tumors in which the earliest genetic event is most commonly the biallelic inactivation of the VHL tumor suppressor gene, leading to constitutive activation of the HIF-1α and HIF-2α transcription factors, which are known angiogenic factors. However it remains unclear whether either or both HIF-1α or HIF-2α stabilization in normal renal epithelial cells are necessary or sufficient for alterations in blood vessel formation. We show that renal epithelium-specific deletion of Vhl in mice causes increased medullary vascularization and that this phenotype is completely rescued by Hif1a co-deletion, but not by co-deletion of Hif2a. A physiological consequence of changes in the blood vessels of the vasa recta in Vhl-deficient mice is a diabetes insipidus phenotype of excretion of large amounts of highly diluted urine. This constitutive diuresis is fully compensated by increased water consumption and mice do not show any signs of dehydration, renal failure or salt wasting and blood electrolyte levels remain unchanged. Co-deletion of Hif1a, but not Hif2a, with Vhl, fully restored kidney morphology and function, correlating with the rescue of the vasculature. We hypothesize that the increased medullary vasculature alters salt uptake from the renal interstitium, resulting in a disruption of the osmotic gradient and impaired urinary concentration. Taken together, our study characterizes a new mouse model for a form of diabetes insipidus and non-obstructive hydronephrosis and provides new insights into the physiological and pathophysiological effects of HIF-1α stabilization on the vasculature in the kidney.

VHL missense mutations in the p53 binding domain show different effects on p53 signaling and HIFα degradation in clear cell renal cell carcinoma

Clear cell Renal Cell Carcinoma (ccRCC) formation is connected to functional loss of the von Hippel-Lindau (VHL) gene. Recent data identified its gene product, pVHL, as a multifunctional adaptor protein which interacts with HIFα subunits but also with the tumor suppressor p53. p53 is hardly expressed and rarely mutated in most ccRCC. We showed that low and absent p53 expression correlated with the severity of VHL mutations in 262 analyzed ccRCC tissues. In contrast to nonsense and frameshift mutations which abrogate virtually all pVHL functions, missense mutations may rather influence one or few functions. Therefore, we focused on four VHL missense mutations, which affect the overlapping pVHL binding sites of p53 and Elongin C, by investigating their impact on HIFα degradation, p53 expression and signaling, as well as on cellular behavior using ccRCC cell lines and tissues. TP53 mRNA and its effector targets p21, Bax and Noxa, were altered both in engineered cell lines and in tumor tissues which carried the same missense mutations. Two of these mutations were not able to degrade HIFα whereas the remaining two mutations led to HIFα downregulation, suggesting the latter are p53 binding site-specific. The selected VHL missense mutations further enhanced tumor cell survival, but had no effects on cell proliferation. Whereas Sunitinib was able to efficiently reduce cell proliferation, Camptothecin was additionally able to increase apoptotic activity of the tumor cells. It is concluded that systematic characterization of the VHL mutation status may help optimizing targeted therapy for patients with metastatic ccRCC.

Morphological clues to the appropriate recognition of hereditary renal neoplasms

An important emerging role of the surgical pathologist besides the traditional tasks of establishment of the diagnosis and documentation of prognostic and predictive factors, is to recognize the possibility of a hereditary condition in cases where the histology is suggestive for a familial cancer syndrome. In recent years, the knowledge regarding all of the above roles, including the role of recognition of familial cancer, has particularly expanded in renal neoplasms with the close scrutiny to morphology, molecular correlates and clinical features of the different sub-types of renal cell carcinoma. Awareness of these clinically distinctive sub-types and their associated histologic clues will prompt the pathologist for further immunohistochemical or molecular work up, to look for clinical information to support the suspected diagnosis of familial cancer, to alert managing physician/s to look for stigmata of history of familial cancer, which will permit triaging patients and their families for appropriate genetic counseling. This review provides a comprehensive review of the known sub-types of renal cell carcinoma that have a predilection to occur in the setting of hereditary disease; examples include renal cancers occurring in the background of von Hippel Lindau disease, hereditary leiomyomatosis and renal cell carcinoma syndrome, tuberous sclerosis, Birt Hogg Dube syndrome and succinate dehydrogenase deficiency. Herein we focus on diagnostic clues for renal tumors occurring in a non-pediatric setting that should prompt their correct recognition and reiterate the importance of the correct diagnosis.

Biomarker discovery for renal cancer stem cells

Characterised by high intra- and inter-tumor heterogeneity, metastatic renal cell carcinoma (RCC) is resistant to chemo- and radiotherapy. Therefore, the development of new prognostic and diagnostic markers for RCC patients is needed. Cancer stem cells (CSCs) are a small population of neoplastic cells within a tumor which present characteristics reminiscent of normal stem cells. CSCs are characterised by unlimited cell division, maintenance of the stem cell pool (self-renewal), and capability to give rise to all cell types within a tumor; and contribute to metastasis in vivo (tumourigenicity), treatment resistance and recurrence. So far, many studies have tried to establish unique biomarkers to identify CSC populations in RCC. At the same time, different approaches have been developed with the aim to isolate CSCs. Consequently, several markers were found to be specifically expressed in CSCs and cancer stem-like cells derived from RCC such as CD105, ALDH1, OCT4, CD133, and CXCR4. However, the contribution of genetic and epigenetic mechanisms, and tumor microenvironment, to cellular plasticity have made the discovery of unique biomarkers a very difficult task. In fact, contrasting results regarding the applicability of such markers to the isolation of renal CSCs have been reported in the literature. Therefore, a better understanding of the mechanism underlying CSC may help dissecting tumor heterogeneity and drug treatment efficiency.

TMIGD1 acts as a tumor suppressor through regulation of p21Cip1/p27Kip1 in renal cancer

Renal cell carcinoma (RCC) is a high-risk metastasizing tumor with a poor prognosis and poorly understood mechanism. In this study, we demonstrate that transmembrane and immunoglobulin domain-containing 1 (TMIGD1) is a novel tumor suppressor that is highly expressed in normal renal tubular epithelial cells, but it is downregulated in human renal cancer. We have identified CCAAT/enhancer-binding proteinβ (C/EBPβ, also called LAP) as a key transcriptional regulator of TMIGD1, whose loss of expression is responsible for downregulation of TMIGD1 in RCC. Transcriptionally active C/EBPβ/LAP physically interacted with and increased TMIGD1 promoter activity and expression of TMIGD1. Re-introduction of TMIGD1 into renal tumor cells significantly inhibited tumor growth and metastatic behaviors such as morphogenic branching and cell migration. Restoring TMIGD1 expression in renal tumor cells stimulated phosphorylation of p38MAK, induced expression of p21CIP1 (cyclin-dependent kinase inhibitor 1), and p27KIP1 (cyclin-dependent kinase inhibitor 1B) expression, key cell cycle inhibitor proteins involved in regulation of the cell cycle. The present study identifies TMIGD1 as a novel candidate tumor suppressor gene and provides important insight into pathobiology of RCC that could lead to a better diagnosis and possible novel therapy for RCC.

Proteome profiling of clear cell renal cell carcinoma in von Hippel-Lindau patients highlights upregulation of Xaa-Pro aminopeptidase-1, an anti-proliferative and anti-migratory exoprotease

Patients of the von Hippel-Lindau (VHL) disease frequently develop clear cell renal cell carcinoma (ccRCC). Using archived, formalin-fixed, paraffin-embedded (FFPE) samples, we sought to determine global proteome alterations that distinguish ccRCC tissue from adjacent, non-malignant kidney tissue in VHL-patients. Our quantitative proteomic analysis clearly discriminated tumor and non-malignant tissue. Significantly dysregulated proteins were distinguished using the linear models for microarray data algorithm. In the ccRCC tissue, we noticed a predominant under-representation of proteins involved in the tricarboxylic acid cycle and an increase in proteins involved in glycolysis. This profile possibly represents a proteomic fingerprint of the "Warburg effect", which is a molecular hallmark of ccRCC. Furthermore, we observed an increase in proteins involved in extracellular matrix organization. We also noticed differential expression of many exoproteases in the ccRCC tissue. Of particular note were opposing alterations of Xaa-Pro Aminopeptidases-1 and -2 (XPNPEP-1 and -2): a strong decrease of XPNPEP-2 in ccRCC was accompanied by abundant presence of the related protease XPNPEP-1. In both cases, we corroborated the proteomic results by immunohistochemical analysis of ccRCC and adjacent, non-malignant kidney tissue of VHL patients. To functionally investigate the role of XPNPEP-1 in ccRCC, we performed small-hairpin RNA mediated XPNPEP-1 expression silencing in 786-O ccRCC cells harboring a mutated VHL gene. We found that XPNPEP-1 expression dampens cellular proliferation and migration. These results suggest that XPNPEP-1 is likely an anti-target in ccRCC. Methodologically, our work further validates the robustness of using FFPE material for quantitative proteomics.

Clinical pharmacology of anti-angiogenic drugs in oncology

Abnormal vasculature proliferation is one of the so-called hallmarks of cancer. Angiogenesis inhibitor therapies are one of the major breakthroughs in cancer treatment in the last two decades. Two types of anti-angiogenics have been approved: monoclonal antibodies and derivatives, which are injected and target the extracellular part of a receptor, and protein kinase inhibitors, which are orally taken small molecules targeting the intra-cellular Adenosine Triphosphate -pocket of different kinases. They have become an important part of some tumors' treatment, both in monotherapy or in combination. In this review, we discuss the key pharmacological concepts and the major pitfalls of anti-angiogenic prescriptions. We also review the pharmacokinetic and pharmacodynamics profile of all approved anti-angiogenic protein kinase inhibitors and the potential role of surrogate markers and of therapeutic drug monitoring.

Epigenome Aberrations: Emerging Driving Factors of the Clear Cell Renal Cell Carcinoma

Clear cell renal cell carcinoma (ccRCC), the most common form of Kidney cancer, is characterized by frequent mutations of the von Hippel-Lindau (VHL) tumor suppressor gene in ~85% of sporadic cases. Loss of pVHL function affects multiple cellular processes, among which the activation of hypoxia inducible factor (HIF) pathway is the best-known function. Constitutive activation of HIF signaling in turn activates hundreds of genes involved in numerous oncogenic pathways, which contribute to the development or progression of ccRCC. Although VHL mutations are considered as drivers of ccRCC, they are not sufficient to cause the disease. Recent genome-wide sequencing studies of ccRCC have revealed that mutations of genes coding for epigenome modifiers and chromatin remodelers, including PBRM1, SETD2 and BAP1, are the most common somatic genetic abnormalities after VHL mutations in these tumors. Moreover, recent research has shed light on the extent of abnormal epigenome alterations in ccRCC tumors, including aberrant DNA methylation patterns, abnormal histone modifications and deregulated expression of non-coding RNAs. In this review, we discuss the epigenetic modifiers that are commonly mutated in ccRCC, and our growing knowledge of the cellular processes that are impacted by them. Furthermore, we explore new avenues for developing therapeutic approaches based on our knowledge of epigenome aberrations of ccRCC.

Combined mutation in Vhl, Trp53 and Rb1 causes clear cell renal cell carcinoma in mice

Clear cell renal cell carcinomas (ccRCC) frequently exhibit inactivation of the VHL tumour suppressor gene and often harbour multiple copy number alterations in genes that regulate cell cycle progression. We show here that modelling these genetic alterations by combined renal epithelium-specific deletion of Vhl, Trp53 and Rb1 in mice caused ccRCC. These tumours arose from proximal tubule epithelial cells and shared molecular markers and mRNA expression profiles with human ccRCC. Exome sequencing revealed that mouse and human ccRCCs exhibit recurrent mutations in genes associated with the primary cilium, uncovering a mutational convergence on this organelle and implicating a subset of ccRCCs as genetic ciliopathies. Different mouse tumours responded differently to standard therapies for advanced human ccRCC, mimicking the range of clinical behaviours in the human disease. Inhibition of HIF-α transcription factors with Acriflavine as third line therapy had therapeutic effects in some tumours, providing pre-clinical evidence for further investigation of HIF-α inhibition as a ccRCC treatment. This autochthonous mouse ccRCC model represents a tool to investigate the biology of ccRCC and to identify new treatment strategies.

Loss of chromosome Y leads to down regulation of KDM5D and KDM6C epigenetic modifiers in clear cell renal cell carcinoma

Recent genomic studies of sporadic clear cell renal cell carcinoma (ccRCC) have uncovered novel driver genes and pathways. Given the unequal incidence rates among men and women (male:female incidence ratio approaches 2:1), we compared the genome-wide distribution of the chromosomal abnormalities in both sexes. We observed a higher frequency for the somatic recurrent chromosomal copy number variations (CNVs) of autosomes in male subjects, whereas somatic loss of chromosome X was detected exclusively in female patients (17.1%). Furthermore, somatic loss of chromosome Y (LOY) was detected in about 40% of male subjects, while mosaic LOY was detected in DNA isolated from peripheral blood in 9.6% of them, and was the only recurrent CNV in constitutional DNA samples. LOY in constitutional DNA, but not in tumor DNA was associated with older age. Amongst Y-linked genes that were downregulated due to LOY, KDM5D and KDM6C epigenetic modifiers have functionally-similar X-linked homologs whose deficiency is involved in ccRCC progression. Our findings establish somatic LOY as a highly recurrent genetic defect in ccRCC that leads to downregulation of hitherto unsuspected epigenetic factors, and suggest that different mechanisms may underlie the somatic and mosaic LOY observed in tumors and peripheral blood, respectively.

Pseudohypoxia induced by miR-126 deactivation promotes migration and therapeutic resistance in renal cell carcinoma

Pseudohypoxia plays a central role in the progression and therapeutic resistance of clear cell renal cell carcinoma (ccRCC); however, the underlying mechanisms are poorly understood. MicroRNA miR-126 has decreased expression in metastatic or relapsed ccRCC as compared to primary tumors, but the mechanisms by which miR-126 is implicated in RCC remain unknown. Through RNA-seq profiling to evaluate the impact of overexpression or CRISPR knockout of miR-126, we have identified SERPINE1 as a miR-126-5p target regulating cell motility, and SLC7A5 as a miR-126-3p target regulating the mTOR/HIF pathway. Specifically, miR-126 inhibits HIFα protein expression independent of von Hippel-Lindau tumor suppressor (VHL). On the other hand, deactivation of miR-126 induces a pseudohypoxia state due to increased HIFα expression, which further enhances therapeutic resistance and cell motility mediated by SLC7A5 and SERPINE1, respectively. Finally, the clinical relevance of miR-126 modulated gene regulation in ccRCC has been confirmed with profiling data from The Cancer Genome Atlas.

Fast clearance of lipid droplets through MAP1S-activated autophagy suppresses clear cell renal cell carcinomas and promotes patient survival

Clear cell renal cell carcinoma (ccRCC) is composed of cells whose cytoplasm filled with lipid droplets, subcellular organelles coated with adipocyte differentiation-related protein (ADFP) for the storage of triacylglycerol converted from excess free fatty acids. Mammalian cells primarily use the autophagy-lysosome system to degrade misfolded/aggregated proteins and dysfunctional organelles such as lipid droplets. MAP1S (originally named C19ORF5) is an autophagy activator and promotes the biogenesis and degradation of autophagosomes. Previously, we reported that MAP1S suppresses hepatocellular carcinogenesis in a mouse model and promoted the survival of patients with prostate adenocarcinomas by increasing the degradation of aggregated proteins and dysfunctional mitochondria. Here we show that a suppression of MAP1S in renal cells causes an impairment of autophagic clearance of lipid droplets. In contrast, an overexpression of MAP1S causes an activation of autophagy flux and a reduction of lipid droplets so less DNA double strand breakage is induced. The levels of MAP1S in normal renal cells are dramatically higher than those in the ccRCC tissues and cell lines derived from renal cell carcinomas. High levels of MAP1S are associated with a reduced malignancy and metastasis of ccRCC and predict a better survival of ccRCC patients. Therefore, autophagy defects in the degradation of lipid droplets triggered by the MAP1S deficiency may enhance the initiation and development of ccRCC and reduce the survival of ccRCC patients.

Prognostic Value of Plasma and Urine Glycosaminoglycan Scores in Clear Cell Renal Cell Carcinoma

BACKGROUND

The prognosis of metastatic clear cell renal cell carcinoma (ccRCC) vastly improved since the introduction of antiangiogenic-targeted therapy. However, it is still unclear which biological processes underlie ccRCC aggressiveness and affect prognosis. Here, we checked whether a recently discovered systems biomarker based on plasmatic or urinary measurements of glycosaminoglycans (GAGs) aggregated into diagnostic scores correlated with ccRCC prognosis.

METHODS

Thirty-one patients with a diagnosis of ccRCC (23 metastatic) were prospectively enrolled, and their urine and plasma biomarker scores were correlated to progression-free survival (PFS) and overall survival (OS) as either a dichotomous ("Low" vs. "High") or a continuous variable in a multivariate survival analysis.

RESULTS

The survival difference between "High"- vs. "Low"-scored patients was significant in the case of urine scores (2-year PFS rate = 53.3 vs. 100%, p = 3 × 10-4 and 2-year OS rate = 73.3 vs. 100%, p = 0.0078) and in the case of OS for plasma scores (2-year PFS rate = 60 vs. 84%, p = 0.0591 and 2-year OS rate = 66.7 vs. 90%, p = 0.0206). In multivariate analysis, the urine biomarker score as a continuous variable was an independent predictor of PFS [hazard ratio (HR): 4.62, 95% CI: 1.66-12.83, p = 0.003] and OS (HR: 10.13, 95% CI: 1.80-57.04, p = 0.009).

CONCLUSION

This is the first report on an association between plasma or urine GAG scores and the prognosis of ccRCC patients. Prospective trials validating the prognostic and predictive role of this novel systems biomarker are warranted.

Curcumin enhances temsirolimus-induced apoptosis in human renal carcinoma cells through upregulation of YAP/p53

Curcumin has frequently been used as a therapeutic agent in the treatment of various types of disease and is known to enhance the drug sensitivity of cells. In the present study, the combined effect of curcumin and temsirolimus treatment on apoptosis in human renal cell carcinoma (RCC) cells was investigated. Temsirolimus is an inhibitor of the mechanistic target of rapamycin signaling pathway and used in the first-line treatment of metastatic RCC. It was demonstrated that curcumin combined with temsirolimus markedly induced apoptosis in RCC cells, however this effect was not observed following curcumin or temsirolimus treatment alone. Co-treatment with temsirolimus and curcumin led to the activation of cleaved poly ADP-ribose polymerase and caspase 3, upregulation of p53 expression and nuclear translocation, and downregulation of B-cell lymphoma 2 protein expression. Furthermore, curcumin treatment was demonstrated to increase Yes-associated protein (YAP) expression in a time-dependent manner, which was concurrent with the curcumin-induced expression pattern of p53 after 2 h. In addition, knockdown of YAP by small interfering RNA caused the attenuation of curcumin-induced increased p53 expression in RCC cells. In conclusion, the present results indicate that combined curcumin and temsirolimus treatment has a synergistic effect on apoptosis in human RCC cells, through the activation of p53. Mechanistically, YAP is essential in the induction of p53 expression by curcumin. Furthermore, the results suggest that pre-treatment or co-treatment of cells with low concentration curcumin enhances the response to targeted drugs, and this presents a potentially novel and efficient strategy to overcome drug resistance in human RCC.

High fidelity of driver chromosomal alterations among primary and metastatic renal cell carcinomas: implications for tumor clonal evolution and treatment

Recent studies have demonstrated considerable genomic heterogeneity in both primary and metastatic renal cell carcinoma (RCC). This mutational diversity has serious implications for the development and implementation of targeted molecular therapies. We evaluated 39 cases of primary RCC tumors with their matched metastatic tumors to determine if the hallmark chromosomal anomalies of these tumors are preserved over the course of disease progression. Thirty-nine matched pairs of primary and metastatic RCCs (20 clear cell RCC, 16 papillary RCC, and 3 chromophobe RCC) were analyzed. All clear cell RCC and papillary RCC tumors were evaluated for chromosome 3p deletion, trisomy 7 and 17 using fluorescence in situ hybridization. Chromophobe RCC tumors were evaluated for genetic alterations in chromosomes 1, 2, 6, 10, and 17. Of the 20 clear cell RCC tumors, 18 primary tumors (90%) showed a deletion of chromosome 3p and were disomic for chromosomes 7 and 17. All molecular aberrations were conserved within the matched metastatic tumor. Of the 16 papillary RCC tumors, 10 primary tumors (62%) showed trisomy for both chromosomes 7 and 17 without 3p deletion. These molecular aberrations and others were conserved in the paired metastatic tumors. Of the three chromophobe RCC tumors, multiple genetic anomalies were identified in chromosomes 1, 2, 6, 10, and 17. These chromosomal aberrations were conserved in the matched metastatic tumors. Our results demonstrated genomic fidelity among the primary and metastatic lesions in RCCs. These findings may have important clinical and diagnostic implications.

The proteomic landscape of renal tumors

INTRODUCTION

Renal cell carcinoma (RCC) is the most fatal of the common urologic cancers, with approximately 35% of patients dying within 5 years following diagnosis. Therefore, there is a need for non-invasive markers that are capable of detecting and determining the severity of small renal masses at an early stage in order to tailor treatment and follow-up. Proteomic studies have proved to be very useful in the study of tumors. Areas covered: In this review, we will detail the current knowledge obtained by the different proteomic approaches, focusing on MS-based strategies, used to investigate RCC biology in order to identify diagnostic, prognostic and predictive biomarkers on tissue, cultured cells and biological fluids. Expert commentary: Currently, no reliable biomarkers or targets for RCC have been translated into the clinical setting. Moreover, despite the efforts of proteomics and other -omics disciplines, only a small number of them have been observed as shared targets between the different analytical platforms and biological specimens. The difficulty to define a specific molecular pattern for RCC and its subtypes highlights a peculiar profile and a heterogeneity that must be taken into account in future studies.

Everolimus in the management of metastatic renal cell carcinoma: an evidence-based review of its place in therapy

Introduction

Renal cell carcinoma (RCC) is the most common type of kidney cancer in adults, and its pathogenesis is strictly related to altered cellular response to hypoxia, in which mTOR signaling pathway is implicated. Everolimus, an mTOR serine/threonine kinase inhibitor, represents a therapeutic option for the treatment of advanced RCC.

Aim

The objective of this article is to review the evidence for the treatment of metastatic RCC with everolimus.

Evidence review

Everolimus was approved for second- and third-line therapy in patients with advanced RCC according to the results of a Phase III pivotal trial that demonstrated a benefit in median progression-free survival of ~2 months compared to placebo after failure of previous lines of therapy, of which at least one was an anti-VEGFR tyrosine kinase inhibitor (TKI). The role of this drug in first-line setting has been investigated in Phase II trials, with no significant clinical benefit, even in combination with bevacizumab. Everolimus activity in non-clear cell RCC is supported by two randomized Phase II trials that confirmed the benefit in second-line setting but not in first line. Recently, two randomized Phase III trials (METEOR and CheckMate 025) demonstrated the inferiority of everolimus in second-line setting compared to the TKI cabozantinib and to the immune checkpoint inhibitor nivolumab, respectively. Moreover, a recent Phase II study demonstrated a significant benefit for the second-line combination treatment with everolimus plus lenvatinib (a novel TKI) in terms of progression-free survival and overall survival compared to the single-agent everolimus. Basing on preclinical data, the main downstream effectors of mTOR cascade, S6RP and its phosphorylated form, could be good predictive biomarkers of response to everolimus. The safety profile of the drug is favorable, with a good cost-effectiveness compared to second-line sorafenib or axitinib, and no significant impact on the quality of life of treated patients has been found.

Conclusion

Everolimus still represents a current standard of treatment for RCC progressive to previous treatment lines with VEGFR-TKI. The evidence about two new molecules, cabozantinib and nivolumab, successfully tested head-to-head with everolimus in recently published Phase III trials, will determine the shift of everolimus to the third-line setting and subsequent lines of treatment.

Characterization of VHL missense mutations in sporadic clear cell renal cell carcinoma: hotspots, affected binding domains, functional impact on pVHL and therapeutic relevance

BACKGROUND

The VHL protein (pVHL) is a multiadaptor protein that interacts with more than 30 different binding partners involved in many oncogenic processes. About 70 % of clear cell renal cell carcinoma (ccRCC) have VHL mutations with varying impact on pVHL function. Loss of pVHL function leads to the accumulation of Hypoxia Inducible Factor (HIF), which is targeted by current targeted treatments. In contrast to nonsense and frameshift mutations that highly likely nullify pVHL multipurpose functions, missense mutations may rather specifically influence the binding capability of pVHL to its partners. The affected pathways may offer predictive clues to therapy and response to treatment. In this study we focused on the VHL missense mutation pattern in ccRCC, and studied their potential effects on pVHL protein stability and binding partners and discussed treatment options.

METHODS

We sequenced VHL in 360 sporadic ccRCC FFPE samples and compared observed and expected frequency of missense mutations in 32 different binding domains. The prediction of the impact of those mutations on protein stability and function was assessed in silico. The response to HIF-related, anti-angiogenic treatment of 30 patients with known VHL mutation status was also investigated.

RESULTS

We identified 254 VHL mutations (68.3 % of the cases) including 89 missense mutations (35 %). Codons Ser65, Asn78, Ser80, Trp117 and Leu184 represented hotspots and missense mutations in Trp117 and Leu 184 were predicted to highly destabilize pVHL. About 40 % of VHL missense mutations were predicted to cause severe protein malfunction. The pVHL binding domains for HIF1AN, BCL2L11, HIF1/2α, RPB1, PRKCZ, aPKC-λ/ι, EEF1A1, CCT-ζ-2, and Cullin2 were preferentially affected. These binding partners are mainly acting in transcriptional regulation, apoptosis and ubiquitin ligation. There was no correlation between VHL mutation status and response to treatment.

CONCLUSIONS

VHL missense mutations may exert mild, moderate or strong impact on pVHL stability. Besides the HIF binding domain, other pVHL binding sites seem to be non-randomly altered by missense mutations. In contrast to LOF mutations that affect all the different pathways normally controlled by pVHL, missense mutations may be rather appropriate for designing tailor-made treatment strategies for ccRCC.

Sleep Apnea and Cancer: Analysis of a Nationwide Population Sample

STUDY OBJECTIVES

Epidemiological evidence from relatively small cohorts suggests that obstructive sleep apnea (OSA) is associated with higher cancer incidence and mortality. Here we aimed to determine whether cancer incidence for major cancer types and risk of metastases or mortality from cancer are increased in the presence of OSA.

METHODS

All OSA diagnoses included in an employee-sponsored health insurance database spanning the years 2003-2012 were identified and 1:1 matched demographically based on age, gender, and state of residence, or alternatively matched by comorbidities. The incidence of 12 types of cancer was assessed. In addition, another cohort of patients with a primary diagnosis of cancer was retrieved, and the risk of metastatic disease or cancer mortality was determined as a function of the presence or absence of OSA. Multivariate Cox proportional hazards regression models were fitted to assess the independent associations between OSA and outcomes of interest.

RESULTS

Based on a cohort of ∼5.6 million individuals, the incidence of all cancer diagnoses combined was similar in OSA and retrospectively matched cases. However, the adjusted risk of pancreatic and kidney cancer and melanoma were significantly higher in patients with OSA, while the risk of colorectal, breast, and prostate cancers appeared to be lower. Among individuals with a diagnosis of cancer, the presence of OSA was not associated with an increased risk for metastasis or death.

CONCLUSIONS

In a large nationally representative health insurance database, OSA appears to increase the risk for only a very selective number of cancer types, and does not appear to be associated with an increased risk of metastatic cancer or cancer-related deaths.

Combined deletion of Vhl, Trp53 and Kif3a causes cystic and neoplastic renal lesions

The von Hippel-Lindau (VHL) tumour suppressor gene is bi-allelically inactivated in the majority of cases of clear cell renal cell carcinoma (ccRCC); however, Vhl knockout mouse models do not recapitulate human ccRCC, implying that additional mutations are required for tumour formation. Mutational inactivation of VHL sensitises renal epithelial cells to lose the primary cilium in response to other mutations or extracellular stimuli. Loss of cilia is believed to represent a second hit in VHL mutant cells that causes the development of cystic lesions that, in some cases, can progress to ccRCC. Supporting this idea, genetic ablation of the primary cilium by deletion of the kinesin family member 3A (Kif3a) gene cooperates with loss of Vhl to accelerate cyst formation in mouse kidneys. Additionally, aged Vhl/Trp53 double-mutant mice develop renal cysts and tumours at a relatively low incidence, suggesting that there is a genetic cooperation between VHL and TP53 mutation in the development of ccRCC. Here we generated renal epithelium-specific Kif3a/Trp53 and Vhl/Kif3a/Trp53 mutant mice to investigate whether primary cilium deletion would accelerate the development of cystic precursor lesions or cause their progression to ccRCC. Longitudinal microcomputed tomography (μCT) imaging and histopathological analyses revealed an increased rate of cyst formation, increased proportion of cysts with proliferating cells, higher frequency of atypical cysts as well as the development of neoplasms in Vhl/Kif3a/Trp53 mutant kidneys compared to Kif3a/Trp53 or Vhl/Kif3a mutant kidneys. These findings demonstrate that primary cilium loss, in addition to Vhl and Trp53 losses, promotes the transition towards malignancy and provide further evidence that the primary cilium functions as a tumour suppressor organelle in the kidney. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Proteotranscriptomic Analysis Reveals Stage Specific Changes in the Molecular Landscape of Clear-Cell Renal Cell Carcinoma

Renal cell carcinoma comprises 2 to 3% of malignancies in adults with the most prevalent subtype being clear-cell RCC (ccRCC). This type of cancer is well characterized at the genomic and transcriptomic level and is associated with a loss of VHL that results in stabilization of HIF1. The current study focused on evaluating ccRCC stage dependent changes at the proteome level to provide insight into the molecular pathogenesis of ccRCC progression. To accomplish this, label-free proteomics was used to characterize matched tumor and normal-adjacent tissues from 84 patients with stage I to IV ccRCC. Using pooled samples 1551 proteins were identified, of which 290 were differentially abundant, while 783 proteins were identified using individual samples, with 344 being differentially abundant. These 344 differentially abundant proteins were enriched in metabolic pathways and further examination revealed metabolic dysfunction consistent with the Warburg effect. Additionally, the protein data indicated activation of ESRRA and ESRRG, and HIF1A, as well as inhibition of FOXA1, MAPK1 and WISP2. A subset analysis of complementary gene expression array data on 47 pairs of these same tissues indicated similar upstream changes, such as increased HIF1A activation with stage, though ESRRA and ESRRG activation and FOXA1 inhibition were not predicted from the transcriptomic data. The activation of ESRRA and ESRRG implied that HIF2A may also be activated during later stages of ccRCC, which was confirmed in the transcriptional analysis. This combined analysis highlights the importance of HIF1A and HIF2A in developing the ccRCC molecular phenotype as well as the potential involvement of ESRRA and ESRRG in driving these changes. In addition, cofilin-1, profilin-1, nicotinamide N-methyltransferase, and fructose-bisphosphate aldolase A were identified as candidate markers of late stage ccRCC. Utilization of data collected from heterogeneous biological domains strengthened the findings from each domain, demonstrating the complementary nature of such an analysis. Together these results highlight the importance of the VHL/HIF1A/HIF2A axis and provide a foundation and therapeutic targets for future studies. (Data are available via ProteomeXchange with identifier PXD003271 and MassIVE with identifier MSV000079511.)

Deletion of Amino Acid Transporter ASCT2 (SLC1A5) Reveals an Essential Role for Transporters SNAT1 (SLC38A1) and SNAT2 (SLC38A2) to Sustain Glutaminolysis in Cancer Cells

Many cancer cells depend on glutamine as they use the glutaminolysis pathway to generate building blocks and energy for anabolic purposes. As a result, glutamine transporters are essential for cancer growth and are potential targets for cancer chemotherapy with ASCT2 (SLC1A5) being investigated most intensively. Here we show that HeLa epithelial cervical cancer cells and 143B osteosarcoma cells express a set of glutamine transporters including SNAT1 (SLC38A1), SNAT2 (SLC38A2), SNAT4 (SLC38A4), LAT1 (SLC7A5), and ASCT2 (SLC1A5). Net glutamine uptake did not depend on ASCT2 but required expression of SNAT1 and SNAT2. Deletion of ASCT2 did not reduce cell growth but caused an amino acid starvation response and up-regulation of SNAT1 to replace ASCT2 functionally. Silencing of GCN2 in the ASCT2(-/-) background reduced cell growth, showing that a combined targeted approach would inhibit growth of glutamine-dependent cancer cells.

PD-L1 expression is regulated by hypoxia inducible factor in clear cell renal cell carcinoma

In our study, we demonstrate that ccRCC cell lines with impaired function of pVHL to degrade HIFα express elevated levels of PD-L1. In vitro analysis provided evidence that both reconstitution of pVHL and silencing of HIF2α, but not of HIF1α, lead to reduced PD-L1 expression. The strong correlation of expression between the HIF2α-specific HIF target Glut1 and PD-L1 confirmed this finding in ccRCC cell lines and tissue. Soluble PD-L1 levels remained constant in the sera of ccRCC patients regardless of the PD-L1 expression status in their tumors. In conclusion, our data suggest PD-L1 as HIF2α target, which is upregulated in pVHL deficient ccRCC. The combination of PD-L1 targeting drugs with HIF inhibiting agents may be an additional option for the treatment of ccRCC.

The 2016 WHO Classification of Tumours of the Urinary System and Male Genital Organs-Part A: Renal, Penile, and Testicular Tumours

The fourth edition of the World Health Organization (WHO) classification of urogenital tumours (WHO "blue book"), published in 2016, contains significant revisions. These revisions were performed after consideration by a large international group of pathologists with special expertise in this area. A subgroup of these persons met at the WHO Consensus Conference in Zurich, Switzerland, in 2015 to finalize the revisions. This review summarizes the most significant differences between the newly published classification and the prior version for renal, penile, and testicular tumours. Newly recognized epithelial renal tumours are hereditary leiomyomatosis and renal cell carcinoma (RCC) syndrome-associated RCC, succinate dehydrogenase-deficient RCC, tubulocystic RCC, acquired cystic disease-associated RCC, and clear cell papillary RCC. The WHO/International Society of Urological Pathology renal tumour grading system was recommended, and the definition of renal papillary adenoma was modified. The new WHO classification of penile squamous cell carcinomas is based on the presence of human papillomavirus and defines histologic subtypes accordingly. Germ cell neoplasia in situ (GCNIS) of the testis is the WHO-recommended term for precursor lesions of invasive germ cell tumours, and testicular germ cell tumours are now separated into two fundamentally different groups: those derived from GCNIS and those unrelated to GCNIS. Spermatocytic seminoma has been designated as a spermatocytic tumour and placed within the group of non-GCNIS-related tumours in the 2016 WHO classification.

PATIENT SUMMARY

The 2016 World Health Organization (WHO) classification contains new renal tumour entities. The classification of penile squamous cell carcinomas is based on the presence of human papillomavirus. Germ cell neoplasia in situ of the testis is the WHO-recommended term for precursor lesions of invasive germ cell tumours.

Regulation of glucose metabolism by p62/SQSTM1 through HIF1α

The signaling adaptor sequestosome 1 (SQSTM1)/p62 is frequently overexpressed in tumors and plays an important role in the regulation of tumorigenesis. Although great progress has been made, biological roles of p62 and relevant molecular mechanisms responsible for its pro-tumor activity remain largely unknown. Here, we show that p62 knockdown reduces cell growth and the expression of glycolytic genes in a manner that depends on HIF1α activity in renal cancer cells. Knockdown of p62 decreases HIF1α levels and transcriptional activity by regulating mTORC1 activity and NF-κB nuclear translocation. Furthermore, p62 interacts directly with the von Hippel-Lindau (VHL) E3 ligase complex to modulate the stability of HIF1α. Mechanistically, p62 binds to the VHL complex and competes with HIF1α. Expression of p62 inhibits the interaction of DCNL1 (also known as DCUN1D1) with CUL2 and attenuates the neddylation of CUL2, and thus downregulates the VHL E3 ligase complex activity. Functionally, HIF1α expression is required for p62-induced glucose uptake, lactate production and soft agar colony growth. Taken together, our findings demonstrate that p62 is a crucial positive regulator of HIF1α, which is a facilitating factor in p62-enhanced tumorigenesis.

Lysophosphatidic acid activates Arf6 to promote the mesenchymal malignancy of renal cancer

Acquisition of mesenchymal properties by cancer cells is critical for their malignant behaviour, but regulators of the mesenchymal molecular machinery and how it is activated remain elusive. Here we show that clear cell renal cell carcinomas (ccRCCs) frequently utilize the Arf6-based mesenchymal pathway to promote invasion and metastasis, similar to breast cancers. In breast cancer cells, ligand-activated receptor tyrosine kinases employ GEP100 to activate Arf6, which then recruits AMAP1; and AMAP1 then binds to the mesenchymal-specific protein EPB41L5, which promotes epithelial–mesenchymal transition and focal adhesion dynamics. In renal cancer cells, lysophosphatidic acid (LPA) activates Arf6 via its G-protein-coupled receptors, in which GTP-Gα12 binds to EFA6. The Arf6-based pathway may also contribute to drug resistance. Our results identify a specific mesenchymal molecular machinery of primary ccRCCs, which is triggered by a product of autotaxin and it is associated with poor outcome of patients.

Acquisition of mesenchymal properties by cancer cells is a critical event for the development of malignancy. Here, the authors show that in renal cancer cells, lysosphosphatidic acid does not utilize the RhoA pathway but specifically activates the Arf6 mesenchymal pathway via its GPCRs and EFA6 to promote invasion, metastasis and drug resistance.

Formation of Renal Cysts and Tumors in Vhl/Trp53-Deficient Mice Requires HIF1α and HIF2α

The von Hippel-Lindau (VHL) tumor suppressor gene is inactivated in the majority of clear cell renal cell carcinomas (ccRCC), but genetic ablation of Vhl alone in mouse models is insufficient to recapitulate human tumorigenesis. One function of pVHL is to regulate the stability of the hypoxia-inducible factors (HIF), which become constitutively activated in the absence of pVHL. In established ccRCC, HIF1α has been implicated as a renal tumor suppressor, whereas HIF2α is considered an oncoprotein. In this study, we investigated the contributions of HIF1α and HIF2α to ccRCC initiation in the context of Vhl deficiency. We found that deleting Vhl plus Hif1a or Hif2a specifically in the renal epithelium did not induce tumor formation. However, HIF1α and HIF2α differentially regulated cell proliferation, mitochondrial abundance and oxidative capacity, glycogen accumulation, and acquisition of a clear cell phenotype in Vhl-deficient renal epithelial cells. HIF1α, but not HIF2α, induced Warburg-like metabolism characterized by increased glycolysis, decreased oxygen consumption, and decreased ATP production in mouse embryonic fibroblasts, providing insights into the cellular changes potentially occurring in Vhl mutant renal cells before ccRCC formation. Importantly, deletion of either Hif1a or Hif2a completely prevented the formation of renal cysts and tumors in Vhl/Trp53 mutant mice. These findings argue that both HIF1α and HIF2α exert protumorigenic functions during the earliest stages of cyst and tumor formation in the kidney. Cancer Res; 76(7); 2025-36. ©2016 AACR.