Mutations of the VHL tumour suppressor gene in renal carcinoma

Adjuvant Therapy in Renal Cell Carcinoma: Current Status and Future Directions

In recent years, incredible progress has been made in the treatment of metastatic renal cell carcinoma, with a paradigm shift from the use of cytokines to tyrosine kinase inhibitors, and more recently, immune checkpoint inhibitors (ICIs). Despite advances in the metastatic setting, effective therapies in the adjuvant setting are a largely unmet need. Currently, sunitinib (Sutent, Pfizer) is the only therapy for the adjuvant treatment of RCC included in the National Comprehensive Cancer Network guidelines, which was approved by the FDA based on the improvement in disease-free survival (DFS) seen in the S-TRAC trial. However, improvement in DFS has not translated into an overall survival (OS) benefit for patients at high-risk of relapse post-nephrectomy, illustrating the need for more effective therapies. This manuscript will highlight attributes of both historical and current drug trials and their implications on the landscape of adjuvant therapy. Additionally, we will outline strategies for selecting patients in whom treatment would be most beneficial, as optimal patient selection is a crucial step towards improving outcomes in the adjuvant setting. This is especially critical, given the financial cost and pharmacological toxicity of therapeutic agents. Furthermore, we will review the design of clinical trials including the value of utilizing OS as an endpoint over DFS. Finally, we will discuss how the incorporation of genomic data into predictive models, the use of more sensitive imaging modalities for more accurate staging, and more extensive surgical intervention involving lymph node dissection, may impact outcomes.

Tumor microenvironment immune subtypes for classification of novel clear cell renal cell carcinoma profiles with prognostic and therapeutic implications

Currently, no effective prognostic model of clear cell renal cell carcinoma (ccRCC) based on immune cell infiltration has been developed. Recent studies have identified 6 immune groups (IS) in 33 solid tumors. We aimed to characterize the expression pattern of IS in ccRCC and evaluate the potential in predicting patient prognosis. The clinical information, immune subgroup, somatic mutation, copy number variation, and methylation score of patients with TCGA ccRCC cohort were downloaded from UCSC Xena for further analysis. The most dominant IS in ccRCC was the inflammatory subgroup (immune C3) (86.5%), regardless of different pathological stages, pathological grades, and genders. In the C3 subgroup, stage IV (69.1%) and grade 4 (69.9%) were the least presented. Survival analysis showed that the IS could effectively predict the overall survival (OS) (P < .0001) and disease-specific survival (DSS) (P < .0001) of ccRCC alone, of which group C3 (OS, HR = 2.3, P < .001; DSS, HR = 2.84, P < .001) exhibited the best prognosis. Among the most frequently mutated ccRCC genes, only VHL and PBRM1 were found to be common in the C3 group. The homologous recombination deficiency score was also lower. High heterogeneity was observed in immune cells and immunoregulatory genes of IS. Notably, CD4+ memory resting T cells were highly infiltrating, regulatory T cells (Treg) showed low infiltration, and most immunoregulatory genes (such as CX3CL1, IFNA2, TLR4, SELP, HMGB1, and TNFRSF14) were highly expressed in the C3 subgroup than in other subgroups. Enrichment analysis showed that adipogenesis, apical junction, hypoxia, IL2 STAT5 signaling, TGF-beta signaling, and UV response DN were activated, whereas E2F targets, G2M checkpoint, and MYC targets V2 were downregulated in the C3 group. Immune classification can more accurately classify ccRCC patients and predict OS and DSS. Thus, IS-based classification may be a valuable tool that enables individualized treatment of patients with ccRCC.

Prolyl Hydroxylase 3 Knockdown Accelerates VHL-Mutant Kidney Cancer Growth In Vivo

Von Hippel Lindau (VHL) inactivation, which is common in clear cell renal cell carcinoma (ccRCC), leads directly to the disruption of oxygen homoeostasis. VHL works through hypoxia-inducible factors (HIFs). Within this VHL-HIF system, prolyl hydroxylases (PHDs) are the intermediary proteins that initiate the degradation of HIFs. PHD isoform 3's (PHD3) role in ccRCC growth in vivo is poorly understood. Using viral transduction, we knocked down the expression of PHD3 in the human ccRCC cell line UMRC3. Compared with control cells transduced with scrambled vector (UMRC3-SC cells), PHD3-knockdown cells (UMRC3-PHD3KD cells) showed increased cell invasion, tumor growth, and response to sunitinib. PHD3 knockdown reduced HIF2α expression and increased phosphorylated epidermal growth factor (EGFR) expression in untreated tumor models. However, following sunitinib treatment, expression of HIF2α and phosphorylated EGFR were equivalent in both PHD3 knockdown and control tumors. PHD3 knockdown changed the overall redox state of the cell as seen by the increased concentration of glutathione in PHD3 knockdown tumors relative to control tumors. UMRC3-PHD3KD cells had increased proliferation in cell culture when grown in the presence of hydrogen peroxide compared to UMRC3-SC control cells. Our findings illustrate (1) the variable effect of PHD3 on HIF2α expression, (2) an inverse relationship between PHD3 expression and tumor growth in ccRCC animal models, and (3) the role of PHD3 in maintaining the redox state of UMRC3 cells and their proliferative rate under oxidative stress.

Towards a new WHO classification of renal cell tumor: what the clinician needs to know-a narrative review

In 1952, renal cell carcinomas had been divided into 2 categories—clear cell or granular cell—depending upon their cytoplasmic staining characteristics. In the following years, the inventory of renal epithelial tumors has expanded by the addition of tumors named by their architectural pattern (i.e., papillary RCC, tubulocystic RCC), anatomic location (i.e., collecting duct carcinoma, renal medullary carcinoma), associated diseases (i.e., acquired cystic disease-associated RCCs). With the extensive application of molecular diagnostic techniques, it becomes possible to detect genetic distinctions between various types of renal neoplasm and discover new entities, otherwise misdiagnosed or diagnosed as unclassified RCC. Some tumors such as ALK rearrangement-associated RCC, MiT family translocation renal carcinomas, SDH-deficient renal cancer or FH-deficient RCC, are defined by their molecular characteristics. The most recent World Health Organization (WHO) classification of renal neoplasms account for more than 50 entities and provisional entities. New entities might be included in the upcoming WHO classification. The aim of this review is to summarise and discuss the newly acquired data and evidence on the clinical, pathological, molecular features and on the prognosis of new RCC entities, which will hopefully increase the awareness and the acceptance of these entities among clinicians and improve prognostication for individual patients.

NK cells sense tumors, course of disease and treatments: Consequences for NK-based therapies

The recent findings on NK activation indicate that these cells are important antitumor effectors. NK cells participate in the graft-vs.-leukemia effect to control the relapse in leukemic patients transplanted with allogeneic hematopoietic stem cells. In various tumors, correlation between NK cell infiltrates and prognosis were reported. However, tumor-infiltrating NK cells are yet poorly characterized. We here summarize our results and the recent studies of the literature on tumor-infiltrating NK cells, and discuss the impact of these novel insights into NK cell responses against tumors for the design of NK cell-based therapies.

NNT-induced tumor cell "slimming" reverses the pro-carcinogenesis effect of HIF2a in tumors

BACKGROUND

HIF2a and lipid accumulation play key roles in the progression of clear cell renal cell carcinoma (ccRCC). Tumor cell "slimming" is a new concept in which tumor cells with abnormal lipids efficiently consume lipids to inhibit tumor progression without producing additional ATP. However, their respective regulatory mechanisms are still unclear. The purpose of this study is uncovering the links between these three key elements of ccRCC to elucidate new mechanisms of ccRCC metabolic abnormalities and providing a basis for new drug development for ccRCC.

METHODS

Bioinformatics screening and analyses were performed in ccRCC according to TCGA-KIRC database. qRT-PCR, luciferase reporter assay, western blot, chromatin immunoprecipitation (ChIP) assays, and other biological methods were used to explore and verify related pathways. Various cell line models and animal models were used to perform related functional experiments.

RESULTS

Screening based on sequencing data after HIF2a knockdown and three independent mitochondrial metabolism-related gene sets showed that nicotinamide nucleotide transhydrogenase (NNT) was a mediator between HIF2a and tumor cells "slimming." Further research showed that NNT had significant prognostic predictive value and was downregulated in ccRCC. It is regulated by HIF2a and can significantly activate lipid browning-mediated tumor cell "slimming." Mechanistic investigations indicated that HIF2a enhanced the expression of miR-455-5p via binding to HIF2a-related response elements in the miR-455-5p promoter, which suppresses NNT expression by binding to its 3' untranslated region.

CONCLUSIONS

Our study revealed a novel mechanism by which HIF2a decreased NNT level through a microRNA that suppressed tumor cell "slimming," resulting in the progression of ccRCC. This mechanism provides a fresh perspective of lipid accumulation in ccRCC and may help target novel strategies for the treatment of tumors with abnormal lipid metabolism.

Molecular Subsets in Renal Cancer Determine Outcome to Checkpoint and Angiogenesis Blockade

Integrated multi-omics evaluation of 823 tumors from advanced renal cell carcinoma (RCC) patients identifies molecular subsets associated with differential clinical outcomes to angiogenesis blockade alone or with a checkpoint inhibitor. Unsupervised transcriptomic analysis reveals seven molecular subsets with distinct angiogenesis, immune, cell-cycle, metabolism, and stromal programs. While sunitinib and atezolizumab + bevacizumab are effective in subsets with high angiogenesis, atezolizumab + bevacizumab improves clinical benefit in tumors with high T-effector and/or cell-cycle transcription. Somatic mutations in PBRM1 and KDM5C associate with high angiogenesis and AMPK/fatty acid oxidation gene expression, while CDKN2A/B and TP53 alterations associate with increased cell-cycle and anabolic metabolism. Sarcomatoid tumors exhibit lower prevalence of PBRM1 mutations and angiogenesis markers, frequent CDKN2A/B alterations, and increased PD-L1 expression. These findings can be applied to molecularly stratify patients, explain improved outcomes of sarcomatoid tumors to checkpoint blockade versus antiangiogenics alone, and develop personalized therapies in RCC and other indications.

Recommendations by the Asian Pacific society of nephrology (APSN) on the appropriate use of HIF-PH inhibitors

Renal anaemia is a common and important complication in patients with chronic kidney disease (CKD). The current standard‐of‐care treatment for renal anaemia in CKD patients involves ensuring adequate iron stores and administration of erythropoietin stimulating agents (ESA). Hypoxia inducible factor (HIF) is a key transcription factor primarily involved in the cellular regulation and efficiency of oxygen delivery. Manipulation of the HIF pathway by the use of HIF‐prolyl hydroxylase inhibitors (HIF‐PHI) has emerged as a novel approach for renal anaemia management. Despite it being approved for clinical use in various Asia‐Pacific countries, its novelty mandates the need for nephrologists and clinicians generally in the region to well understand potential benefits and harms when prescribing this class of drug. The Asian Pacific society of nephrology HIF‐PHI Recommendation Committee, formed by a panel of 11 nephrologists from the Asia‐Pacific region who have clinical experience or have been investigators in HIF‐PHI studies, reviewed and deliberated on the clinical and preclinical data concerning HIF‐PHI. This recommendation summarizes the consensus views of the committee regarding the use of HIF‐PHI, taking into account both available data and expert opinion in areas where evidence remains scarce.

The Asian Pacific society of nephrology HIF‐PHI Recommendation Committee summarizes the consensus views of the committee regarding the use of HIF‐PHI, taking into account both available data and expert opinion in areas where evidence remains scarce.

Construction of a Novel Multigene Panel Potently Predicting Poor Prognosis in Patients with Clear Cell Renal Cell Carcinoma

Simple Summary

Clear cell renal cell carcinoma (ccRCC) is the predominant cause of kidney cancer death attributed to its prevalence (70%) and its nature being the most aggressive form of kidney cancer. Most ccRCC deaths are resulted from metastasis. It is essential to know which ccRCCs are at risk of metastasis and the development to lethal disease; however, our capacity for such analysis remains poor. To improve this diagnostic capacity, we have examined a comprehensive ccRCC dataset containing 512 patients and have produced a 9-gene signature. This signature is novel; all its 9 components genes are unknown to be related to ccRCC. Importantly, all 9 individual genes possess significant ability in diagnosis of ccRCC metastasis and fatality; the combination of these genes or this signature predicts deadly ccRCCs at an impressive efficiency. This research will open new avenues in ccRCC research and will have a major impact in reducing ccRCC-associated deaths.

Abstract

We observed associations of IQGAP1 downregulation with poor overall survival (OS) in clear cell renal cell carcinoma (ccRCC). Differentially expressed genes (DEGs, n = 611) were derived from ccRCCs with (n = 111) and without IQGAP1 (n = 397) reduction using the TCGA PanCancer Atlas ccRCC dataset. These DEGs exhibit downregulations of immune response and upregulations of DNA damage repair pathways. Through randomization of the TCGA dataset into a training and testing subpopulation, a 9-gene panel (SigIQGAP1NW) was derived; it predicts poor OS in training, testing, and the full population at a hazard ratio (HR) 2.718, p < 2 × 10⁻¹⁶, p = 1.08 × 10⁻⁵, and p < 2 × 10⁻¹⁶, respectively. SigIQGAP1NW independently associates with poor OS (HR 1.80, p = 2.85 × 10⁻⁶) after adjusting for a set of clinical features, and it discriminates ccRCC mortality at time-dependent AUC values of 70% at 13.8 months, 69%/31M, 69%/49M, and 75.3%/71M. All nine component genes of SigIQGAP1NW are novel to ccRCC. The inclusion of RECQL4 (a DNA helicase) in SigIQGAP1NW agrees with IQGAP1 DEGs enhancing DNA repair. THSD7A affects kidney function; its presence in SigIQGAP1NW is consistent with our observed THSD7A downregulation in ccRCC (n = 523) compared to non-tumor kidney tissues (n = 100). Collectively, we report a novel multigene panel that robustly predicts poor OS in ccRCC.

On the Shoulders of Giants: The Evolution of Renal Cell Carcinoma Treatment-Cytokines, Targeted Therapy, and Immunotherapy

The treatment of advanced renal cell carcinoma (RCC) has evolved dramatically over the past 30 years, as has a better understanding of the biology of the disease, knowledge of multiple subtypes with distinct molecular abnormalities, and improved comprehension of the perturbed pathways that lead to the development and growth of RCC. This is no longer a monolithic disease, although the majority of tumors are of the clear cell subtype. However, progress is being made in other subtypes as well, as molecular profiles are better understood and as new agents show activity. Immunotherapies remain a major category of treatment, from cytokines to checkpoint inhibitors to ex vivo activated cellular therapy. Antiangiogenesis tyrosine kinase inhibitors are also an important part of the armamentarium. Because these approaches have evolved, we are now in the era of combination therapy using agents of differing mechanisms to try to achieve synergy to increase response rates and create durable responses leading to prolonged survival. Renal cell carcinoma as a tumor is unique in that there has always been a subset of patients who achieve complete responses that last for many years without subsequent treatment. Thus, the goal of further development is to enlarge this subset using new therapeutic approaches and to achieve further durable responses and treatment-free survival.

The prefoldin complex stabilizes the von Hippel-Lindau protein against aggregation and degradation

Loss of von Hippel-Lindau protein pVHL function promotes VHL diseases, including sporadic and inherited clear cell Renal Cell Carcinoma (ccRCC). Mechanisms controlling pVHL function and regulation, including folding and stability, remain elusive. Here, we have identified the conserved cochaperone prefoldin complex in a screen for pVHL interactors. The prefoldin complex delivers non-native proteins to the chaperonin T-complex-protein-1-ring (TRiC) or Cytosolic Chaperonin containing TCP-1 (CCT) to assist folding of newly synthesized polypeptides. The pVHL-prefoldin interaction was confirmed in human cells and prefoldin knock-down reduced pVHL expression levels. Furthermore, when pVHL was expressed in Schizosaccharomyces pombe, all prefoldin mutants promoted its aggregation. We mapped the interaction of prefoldin with pVHL at the exon2-exon3 junction encoded region. Low levels of the PFDN3 prefoldin subunit were associated with poor survival in ccRCC patients harboring VHL mutations. Our results link the prefoldin complex with pVHL folding and this may impact VHL diseases progression.

Mass Spectrometry-Based Metabolic Fingerprinting Contributes to Unveil the Role of RSUME in Renal Cell Carcinoma Cell Metabolism

Clear cell renal cell carcinoma (ccRCC) is a heterogeneous disease with 50-80% patients exhibiting mutations in the von Hippel-Lindau (VHL) gene. RSUME (RWD domain (termed after three major RWD-containing proteins: RING finger-containing proteins, WD-repeat-containing proteins, and yeast DEAD (DEXD)-like helicases)-containing protein small ubiquitin-related modifier (SUMO) enhancer) acts as a negative regulator of VHL function in normoxia. A discovery-based metabolomics approach was developed by means of ultraperformance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (MS) for fingerprinting the endometabolome of a human ccRCC cell line 786-O and three other transformed cell systems (n = 102) with different expressions of RSUME and VHL. Cross-validated orthogonal projection to latent structures discriminant analysis models were built on positive, negative, and a combination of positive- and negative-ion mode MS data sets. Discriminant feature panels selected by an iterative multivariate classification allowed differentiating cells with different expressions of RSUME and VHL. Fifteen identified discriminant metabolites with level 1, including glutathione, butyrylcarnitine, and acetylcarnitine, contributed to understand the role of RSUME in ccRCC. Altered pathways associated with the RSUME expression were validated by biological and bioinformatics analyses. Combined results showed that in the absence of VHL, RSUME is involved in the downregulation of the antioxidant defense system, whereas in the presence of VHL, it acts in rerouting energy-related pathways, negatively modulating the lipid utilization, and positively modulating the fatty acid synthesis, which may promote deposition in droplets.

Potential Links between YB-1 and Fatty Acid Synthesis in Clear Cell Renal Carcinoma

According to the National Institutes of Health, clear cell renal cell carcinoma (ccRCC) is the most common type of Renal Cell Carcinoma (RCC), making up approximately 75% of total renal carcinoma cases. Clear cell Renal Cell Carcinoma is characterized by a significant accumulation of lipids in the cytoplasm, which allows light from microscopes to pass through giving them a "clear" phenotype. Many of these lipids are in the form of fatty acids, both free and incorporated into lipid droplets. RCC is typically associated with a poor prognosis due to the lack of specific symptoms. Some symptoms include blood in urine, fever, lump on the side, weight loss, fatigue, to name a few; all of which can be associated with non-specific, non-cancerous, health conditions that contribute to difficult diagnosis. Treatment of RCC has typically been centered around radical nephrectomy as the standard of care, but due to the potentially small size of lesions and the possibility of causing surgically induced chronic kidney disease, treatments have shifted to more cautious, less invasive approaches. These approaches include active surveillance, nephron-sparing surgery, and other minimally invasive techniques like cryotherapy and renal ablation. Although these techniques have had the desired effect of reducing the number of surgeries, there is still considerable potential for renal impairment and the chance that tumors can grow out of control without surgery. With the difficulty that surrounds the treatment of ccRCC and its considerably high mortality rate amongst urological cancers, it is important to look for novel approaches to improve patient outcomes. This review looks at available literature and our data that suggests the lipogenic enzyme stearoyl-CoA desaturase may be more beneficial to patient survival than once thought. As our understanding of the importance of lipids in cell metabolism and longevity matures, it is important to present new perspectives that present a new understanding of ccRCC and the role of lipids in survival mechanisms engaged by transformed cells during cancer progression. In this review, we provide evidence that pharmacological inhibition of lipid desaturation in renal cancer patients is not without risk, and that the presence of unsaturated fatty acids may be a beneficial factor in patient outcomes. Although more direct experimental evidence is needed to make definitive conclusions, it is clear that the work reviewed herein should challenge our current understanding of cancer biology and may inform novel approaches to the diagnosis and treatment of ccRCC.

Combination therapy in metastatic renal cell carcinoma: Back to the future?

The treatment landscape of metastatic renal cell carcinoma (mRCC), a chemotherapy-resistant disease, has dramatically changed in the last decade after the introduction of small molecule inhibitors targeting the vascular endothelial growth factor receptor and mammalian target of rapamycin kinases. The CheckMate 025 phase III trial in second line mRCC also introduced immunotherapy with immune-checkpoint inhibitors as an option in the management of mRCC. Both small molecules and immunotherapy are used as single agents and they are associated with different toxicities. Recent data demonstrated that the combination of 2 immunotherapies, nivolumab and ipilimumab, is more effective than tyrosine kinase inhibitors (TKI) monotherapy as first line treatment in intermediate and poor risk mRCC. Furthermore, combination of immunotherapies and TKI has been tested in several trials to evaluate if the combo with agents presenting a different mechanism of action is more effective than monotherapy with TKI. During the past several years, combined therapy of cytokines doublets or cytokines and bevacizumab doublets demonstrated little improvement in clinical outcomes and a relevant toxicity profile. Conversely, the combination of new agents has been recently shown to improve survival in patients with metastatic disease, thus changing the treatment landscape of mRCC. This comprehensive review aims at summarizing the recent advances in the treatment of mRCC.

Macrophage HIF-1α Is an Independent Prognostic Indicator in Kidney Cancer

PURPOSE

Clear cell renal cell carcinoma (ccRCC) is frequently associated with inactivation of the von Hippel-Lindau tumor suppressor, resulting in activation of HIF-1α and HIF-2α. The current paradigm, established using mechanistic cell-based studies, supports a tumor promoting role for HIF-2α, and a tumor suppressor role for HIF-1α. However, few studies have comprehensively examined the clinical relevance of this paradigm. Furthermore, the hypoxia-associated factor (HAF), which regulates the HIFs, has not been comprehensively evaluated in ccRCC.

EXPERIMENTAL DESIGN

To assess the involvement of HAF/HIFs in ccRCC, we analyzed their relationship to tumor grade/stage/outcome using tissue from 380 patients, and validated these associations using tissue from 72 additional patients and a further 57 patients treated with antiangiogenic therapy for associations with response. Further characterization was performed using single-cell mRNA sequencing (scRNA-seq), RNA-in situ hybridization (RNA-ISH), and IHC.

RESULTS

HIF-1α was primarily expressed in tumor-associated macrophages (TAMs), whereas HIF-2α and HAF were expressed primarily in tumor cells. TAM-associated HIF-1α was significantly associated with high tumor grade and increased metastasis and was independently associated with decreased overall survival. Furthermore, elevated TAM HIF-1α was significantly associated with resistance to antiangiogenic therapy. In contrast, high HAF or HIF-2α were associated with low grade, decreased metastasis, and increased overall survival. scRNA-seq, RNA-ISH, and Western blotting confirmed the expression of HIF-1α in M2-polarized CD163-expressing TAMs.

CONCLUSIONS

These findings highlight a potential role of TAM HIF-1α in ccRCC progression and support the reevaluation of HIF-1α as a therapeutic target and marker of disease progression.

LC3C-Mediated Autophagy Selectively Regulates the Met RTK and HGF-Stimulated Migration and Invasion

The Met/hepatocyte growth factor (HGF) receptor tyrosine kinase (RTK) is deregulated in many cancers and is a recognized target for cancer therapies. Following HGF stimulation, the signaling output of Met is tightly controlled by receptor internalization and sorting for degradation or recycling. Here, we uncover a role for autophagy in selective degradation of Met and regulation of Met-dependent cell migration and invasion. Met engagement with the autophagic pathway is dependent on complex formation with the mammalian ATG8 family member MAP1LC3C. LC3C deletion abrogates Met entry into the autophagy-dependent degradative pathway, allowing identification of LC3C domains required for rescue. Cancer cells with low LC3C levels show enhanced Met stability, signaling, and cell invasion. These findings provide mechanistic insight into RTK recruitment to autophagosomes and establish distinct roles for ATG8 proteins in this process, supporting that differential expression of ATG8 proteins can shape the functional consequences of autophagy in cancer development and progression.

VON HIPPEL-LINDAU DISEASE: Update on Pathogenesis and Systemic Aspects

PURPOSE

To provide an update summarizing the biologic pathways governing von Hippel-Lindau (VHL) disease pathogenesis and to provide an overview of systemic manifestations as well as screening recommendations.

METHODS

A PubMed search of the English language literature was reviewed using the following search terms: von Hippel-Lindau, von Hippel-Lindau disease, and VHL. Of 6,696 publications, the most current and pertinent information related to the pathogenesis and systemic aspects of VHL disease were included in this review.

RESULTS

von Hippel-Lindau disease is one of the most frequently occurring multisystem familial cancer syndromes. The disease results from germline mutation in the VHL tumor suppressor gene on the short arm of chromosome 3. Mutation in the VHL gene affects multiple cellular processes including transcriptional regulation, extracellular matrix formation, apoptosis, and, in particular, the cellular adaptive response to hypoxia. As a result, there is widespread development of vascular tumors affecting the retina, brain, and spine, as well as a spectrum of benign and malignant tumors and/or cysts in visceral organs.

CONCLUSION

The ophthalmologist plays a key role in VHL disease diagnosis, as retinal hemangioblastoma is frequently the first disease manifestation. Screening guidelines for individuals with known VHL disease, and those at risk of VHL disease, help to ensure early detection of potentially vision-threatening and life-threatening disease.

Identification of anti-tumoral feedback loop between VHLα and hnRNPA2B1 in renal cancer

Our previous study identified a novel VHLα isoform which negatively modulated hnRNPA2B1 expression and therefore influenced pyruvate kinase transcript splicing in renal cancer, while the regulation and initiation of alternative translation are largely unknown. Here we unraveled the CUG-mediated translation start of VHLα, which was subjected to the regulation by both eukaryotic initiator factor eIF2A and RNA helicase eIF4A. Unexpectedly, we found hnRNPA2B1 promoted VHLα alternative translation as well via direct interaction with its octadic pentamer region of VHL transcript. The N-terminal of VHLα was indispensable in mediating ubiquitination of hnRNPA2B1 at lysine residues 274 and 305. We further identified aberrant overexpression of c-myc as upstream oncogenic signaling to positively regulate hnRNPA2B1 transcription in renal cancer. Therefore, our data suggested an anti-tumoral feedback loop between VHLα and hnRNPA2B1.

The oncogenic role of MUC12 in RCC progression depends on c-Jun/TGF-β signalling

Renal cell carcinoma (RCC) is a common kidney cancer worldwide. Even though current treatments show promising therapeutic effectiveness, metastatic RCC still has limited therapeutic options so that novel treatments were urgently needed. Here, we identified that MUC12 was overexpressed in RCC patients and served as poor prognostic factor for RCC progression. Overexpression of MUC12 increased RCC cell growth and cell invasion while deficiency of MUC12 exerted opposite effects on RCC cells. Mechanistic dissection demonstrated that MUC12-mediated RCC cell growth and cell invasion were dependent of TGF-β1 signalling because they could be blocked in the presence of TGF-β1 inhibitor. Moreover, the regulation of TGF-β1 by MUC12 relied on the transactivation of c-Jun. MUC12 promoted the recruitment of c-Jun on the promoter of TGF-β1, leading to its transcription. Importantly, knockdown of c-Jun also attenuated MUC12-mediated TGF-β1 induction and RCC cell invasion. In summary, our study defines the role of MUC12 in RCC progression and provides rational to develop novel targeted therapy to battle against RCC.

Genetic Alterations in Renal Cancers: Identification of The Mechanisms Underlying Cancer Initiation and Progression and of Therapeutic Targets

Renal cell cancer (RCC) involves three most recurrent sporadic types: clear-cell RCC (70-75%, CCRCC), papillary RCCC (10-15%, PRCC), and chromophobe RCC (5%, CHRCC). Hereditary cases account for about 5% of all cases of RCC and are caused by germline pathogenic variants. Herein, we review how a better understanding of the molecular biology of RCCs has driven the inception of new diagnostic and therapeutic approaches. Genomic research has identified relevant genetic alterations associated with each RCC subtype. Molecular studies have clearly shown that CCRCC is universally initiated by Von Hippel Lindau (VHL) gene dysregulation, followed by different types of additional genetic events involving epigenetic regulatory genes, dictating disease progression, aggressiveness, and differential response to treatments. The understanding of the molecular mechanisms that underlie the development and progression of RCC has considerably expanded treatment options; genomic data might guide treatment options by enabling patients to be matched with therapeutics that specifically target the genetic alterations present in their tumors. These new targeted treatments have led to a moderate improvement of the survival of metastatic RCC patients. Ongoing studies based on the combination of immunotherapeutic agents (immune check inhibitors) with VEGF inhibitors are expected to further improve the survival of these patients.

Etiologic heterogeneity of clear-cell and papillary renal cell carcinoma in the Netherlands Cohort Study

At present, mostly case‐control and retrospective studies have investigated the association between etiologic risk factors and the development of histologic subtypes of renal cell carcinoma (RCC). Therefore, we assessed the heterogeneity between body mass index (BMI), cigarette smoking, alcohol consumption and hypertension across clear‐cell RCC (ccRCC) and papillary RCC (pRCC) risk in the prospective Netherlands Cohort Study on diet and cancer. In 1986, 120 852 participants aged 55 to 69 completed a self‐administered questionnaire on diet and other risk factors for cancer. Participants were followed up for cancer through record linkage. Tumor histology was assessed through centralized revision by two experienced uropathologists. After 20.3 years of follow‐up, 384 histologically verified RCC cases, including 315 ccRCC and 46 pRCC cases and 4144 subcohort members were eligible for case‐cohort analysis. Hazard ratios and 95% confidence intervals were estimated by multivariable‐adjusted proportional hazards models. Overall, BMI was associated positively with ccRCC risk, but inversely with pRCC risk. Cigarette smoking was associated with an increased ccRCC, but a decreased pRCC risk. Alcohol consumption was inversely associated with both ccRCC and pRCC risk. Hypertension was associated with an increased risk of both ccRCC and pRCC. Statistically significant etiologic heterogeneity was observed for BMI, BMI change since age 20, and smoking duration in current smokers across ccRCC and pRCC risk. In conclusion, we observed potential heterogeneity for BMI, BMI change and smoking duration across ccRCC and pRCC risk.

What's new?

Etiologic risk factors for clear cell renal cell carcinoma (ccRCC) and papillary renal cell carcinoma (pRCC) include alcohol consumption, body mass index (BMI), cigarette smoking, and hypertension. Little is known, however, about variability in how these factors affect the development of RCC histologic subtypes. In this population‐based prospective cohort study, examination of variability in associations between established etiologic factors and RCC histologic subtypes revealed significant heterogeneity between BMI and ccRCC and pRCC risk and between risk of these subtypes and smoking duration in current smokers. The findings provide novel insight into relationships between etiologic heterogeneity and mechanisms of RCC development.

Adjuvant Therapy for Localized High-Risk Renal Cell Carcinoma

This article reviews the use of adjuvant therapies for prevention of recurrence following resection of clinically localized renal cell carcinoma (RCC). Clinical trials evaluating adjuvant therapy for RCC have focused primarily on the use of tyrosine kinase inhibitors and mammalian target of rapamycin inhibitors, which had improved outcome in patients with metastatic disease. However, all but 1 trial found no difference in disease-free survival in the adjuvant setting and none improved overall survival.

The pVHL neglected functions, a tale of hypoxia-dependent and -independent regulations in cancer

The von Hippel–Lindau protein (pVHL) is a tumour suppressor mainly known for its role as master regulator of hypoxia-inducible factor (HIF) activity. Functional inactivation of pVHL is causative of the von Hippel–Lindau disease, an inherited predisposition to develop different cancers. Due to its impact on human health, pVHL has been widely studied in the last few decades. However, investigations mostly focus on its role in degrading HIFs, whereas alternative pVHL protein–protein interactions and functions are insistently surfacing in the literature. In this review, we analyse these almost neglected functions by dissecting specific conditions in which pVHL is proposed to have differential roles in promoting cancer. We reviewed its role in regulating phosphorylation as a number of works suggest pVHL to act as an inhibitor by either degrading or promoting downregulation of specific kinases. Further, we summarize hypoxia-dependent and -independent pVHL interactions with multiple protein partners and discuss their implications in tumorigenesis.

Anterior gradient 2 promotes tumorigenesis through upregulation of CCAAT-enhancer binding protein beta and hypoxia-inducible factor-2α and subsequent secretion of interleukin-6, interleukin-8, and vascular endothelial growth factor in the Caki-1 clear cell renal cell carcinoma cell line

It has been previously established that hypoxia leads to tumor development, treatment resistance, and a poor prognosis. Under oxygen deprivation, hypoxia-inducible factors (HIFs) are stimulated to activate the genes necessary for tumor development in a low-oxygen environment. These genes encode regulators of angiogenesis, epithelial-mesenchymal transition, and cellular metabolism. A disulfide isomerase, anterior gradient 2 (AGR2), has been shown to increase hypoxia-inducible factor 1, alpha subunit (HIF-1α) stability in breast cancer. Our goal was to determine if AGR2 affects the level of transcription factor hypoxia-inducible factor 2, alpha subunit (HIF-2α). As a model, we used the clear cell renal cell carcinoma (ccRCC) cell line Caki-1. The cells were transduced with lentiviral vector (Tet-On) encoding AGR2. After induction of AGR2 expression, cells were grown under either hypoxic (0.5% O₂ ) or normoxic (21% O₂ ) conditions. Our data showed that AGR2 upregulated both HIF-1α and HIF-2α expression in Caki-1 cells increasing the expression of HIF-activated genes (glucose transporter 1, phosphoglycerate kinase 1, vascular endothelial growth factor A, and transforming growth factor-alpha) under the hypoxic conditions. Under the normoxic conditions, AGR2 strongly activated CCAAT-enhancer binding protein beta (C/EBPβ). Upregulation of C/EBPβ correlated with increased expression and secretion of the interleukin-6 and interleukin-8, inducing angiogenesis and inflammation in Caki-1 cells. In summary, our studies revealed that AGR2 has essential functions in ccRCC progression through upregulation of C/EBPβ and HIF-2α expressions, which affects cell signaling and metabolism.

Genomic profiling in renal cell carcinoma

The treatment landscape of metastatic renal cell carcinoma (RCC) has been revolutionized over the past two decades, bringing forth an era in which more than a dozen therapeutic agents are now available to treat patients. As a consequence, personalized care has become a critical part of developing effective treatment guidelines and improving patient outcomes. One of the most important emerging aspects of precision medicine in cancer is matching patients and treatments based on the genomic characteristics of an individual and their tumour. Despite the lack of a single genomic predictor of treatment response or prognostication feature in RCC, emerging research suggests that the identification of such markers remains promising. Mutations in VHL and alterations in its downstream pathways are the mainstay of RCC development and progression. However, the predictive value of VHL mutations has been questioned. Further research has examined mutations in genes involved in chromosome remodelling (for example, PBRM1, BAP1 and SETD2), DNA methylation and DNA damage repair, all of which have been associated with clinical outcomes. Here, we provide a comprehensive overview of genomic evidence in the context of RCC and its potential predictive and prognostic value.

Third-line sunitinib treatment in a VHL-mutated metastatic intrahepatic cholangiocarcinoma: a case report and literature review

Intrahepatic cholangiocarcinoma (iCCA) is a highly aggressive malignancy with a poor prognosis. There is no standard treatment beyond first-line chemotherapy and no molecular-targeted drug approved for advanced iCCA. We herein present a case of a 46-y-old Asian iCCA patient with multiple metastases in lung, bone, and liver. The patient progressed rapidly after first- and second-line chemotherapy. According to next-generation sequencing result of somatic Von Hippel-Lindau (VHL) gene mutation, the patient was administered third-line sunitinib and obtained a relatively longer survival of 9 months after taking sunitinib. Additionally, we briefly summarized the current targeted treatment of iCCA. To our knowledge, this is the first report of VHL mutation and sunitinib usage in metastatic iCCA patient. As a highly heterogeneous and aggressive malignancy, we strongly recommend making clinical decisions based on precision medicine concept in advanced iCCA.

PRDM16 suppresses HIF-targeted gene expression in kidney cancer

Analysis of transcriptomic data demonstrates extensive epigenetic gene silencing of the transcription factor PRDM16 in renal cancer. We show that restoration of PRDM16 in RCC cells suppresses in vivo tumor growth. RNaseq analysis reveals that PRDM16 imparts a predominantly repressive effect on the RCC transcriptome including suppression of the gene encoding semaphorin 5B (SEMA5B). SEMA5B is a HIF target gene highly expressed in RCC that promotes in vivo tumor growth. Functional studies demonstrate that PRDM16's repressive properties, mediated by physical interaction with the transcriptional corepressors C-terminal binding proteins (CtBP1/2), are required for suppression of both SEMA5B expression and in vivo tumor growth. Finally, we show that reconstitution of RCC cells with a PRDM16 mutant unable to bind CtBPs nullifies PRDM16's effects on both SEMA5B repression and tumor growth suppression. Collectively, our data uncover a novel epigenetic basis by which HIF target gene expression is amplified in kidney cancer and a new mechanism by which PRDM16 exerts its tumor suppressive effects.

Significance of PI3K signalling pathway in clear cell renal cell carcinoma in relation to VHL and HIF status

Renal cell carcinoma (RCC) includes diverse tumour types characterised by various genetic abnormalities. The genetic changes, like mutations, deletions and epigenetic alterations, play a crucial role in the modification of signalling networks, tumour pathogenesis and prognosis. The most prevalent RCC type, clear cell RCC (ccRCC), is asymptomatic in the early stages and has a poorer prognosis compared with the papillary and the chromophobe types RCCs. Generally, ccRCC is refractory to chemotherapy and radiation therapy. Loss of von Hippel-Lindau (VHL) gene and upregulation of hypoxia-inducible factors (HIF), the signature of most sporadic ccRCC, promote multiple growth factors. Hence, VHL/HIF and a variety of pathways, including phosphatase and TEnsin homolog on chromosome 10/phosphatidylinositol-3-kinase (PI3K)/AKT, are closely connected and contribute to the ontogeny of ccRCC. In the recent decade, multiple targeting agents have been developed based on blocking major signalling pathways directly or indirectly involved in ccRCC tumour progression, metastasis, angiogenesis and survival. However, most of these drugs have limitations; either metastatic ccRCC develops resistance to these agents, or despite blocking receptors, tumour cells use alternate signalling pathways. This review compiles the state of knowledge about the PI3K/AKT signalling pathway confined to ccRCC and its cross-talks with VHL/HIF pathway.

Prolyl-hydroxylase inhibitors for the treatment of anemia in chronic kidney disease

PURPOSE OF REVIEW

Prolyl-hydroxylase inhibitors are a novel class of orally administered drugs that are under development for the treatment of anemia in patients with chronic kidney disease. This review discusses the biology of these drugs and their target - hypoxia-inducible factor and potential advantages and disadvantages of these therapies. Finally, we will discuss current trials in patients with both chronic kidney disease and end-stage renal disease.

RECENT FINDINGS

Recent smaller studies have found that prolyl-hydroxylase are as effective as erythropoietin in treating anemia of chronic kidney disease. We do not yet know if they have the same cardiovascular and cancer-related risk profile and these questions will be answered by large phase III trials that are ongoing.

SUMMARY

Although prolyl hydroxylase inhibitors have much potential, questions remain regarding their efficacy and safety. Should these concerns prove to be unfounded, the treatment of anemia in chronic kidney disease will likely be transformed over the next decade.

LRRC19-A Bridge between Selenium Adjuvant Therapy and Renal Clear Cell Carcinoma: A Study Based on Datamining

Kidney renal clear cell carcinoma (KIRC) is the most common and fatal subtype of renal cancer. Antagonistic associations between selenium and cancer have been reported in previous studies. Selenium compounds, as anti-cancer agents, have been reported and approved for clinical trials. The main active form of selenium in selenoproteins is selenocysteine (Sec). The process of Sec biosynthesis and incorporation into selenoproteins plays a significant role in biological processes, including anti-carcinogenesis. However, a comprehensive selenoprotein mRNA analysis in KIRC remains absent. In the present study, we examined all 25 selenoproteins and identified key selenoproteins, glutathione peroxidase 3 (GPX3) and type 1 iodothyronine deiodinase (DIO1), with the associated prognostic biomarker leucine-rich repeat containing 19 (LRRC19) in clear cell renal cell carcinoma cases from The Cancer Genome Atlas (TCGA) database. We performed validations for the key gene expression levels by two individual clear cell renal cell carcinoma cohorts, GSE781 and GSE6344, datasets from the Gene Expression Omnibus (GEO) database. Multivariate survival analysis demonstrated that low expression of LRRC19 was an independent risk factor for OS. Gene set enrichment analysis (GSEA) identified tyrosine metabolism, metabolic pathways, peroxisome, and fatty acid degradation as differentially enriched with the high LRRC19 expression in KIRC cases, which are involved in selenium therapy of clear cell renal cell carcinoma. In conclusion, low expression of LRRC19 was identified as an independent risk factor, which will advance our understanding concerning the selenium adjuvant therapy of clear cell renal cell carcinoma.

Tumor sequencing is useful to refine the analysis of germline variants in unexplained high-risk breast cancer families

Background

Multigene panels are routinely used to assess for predisposing germline mutations in families at high breast cancer risk. The number of variants of unknown significance thereby identified increases with the number of sequenced genes. We aimed to determine whether tumor sequencing can help refine the analysis of germline variants based on second somatic genetic events in the same gene.

Methods

Whole-exome sequencing (WES) was performed on whole blood DNA from 70 unrelated breast cancer patients referred for genetic testing and without a BRCA1, BRCA2, TP53, or CHEK2 mutation. Rare variants were retained in a list of 735 genes. WES was performed on matched tumor DNA to identify somatic second hits (copy number alterations (CNAs) or mutations) in the same genes. Distinct methods (among which immunohistochemistry, mutational signatures, homologous recombination deficiency, and tumor mutation burden analyses) were used to further study the role of the variants in tumor development, as appropriate.

Results

Sixty-eight patients (97%) carried at least one germline variant (4.7 ± 2.0 variants per patient). Of the 329 variants, 55 (17%) presented a second hit in paired tumor tissue. Of these, 53 were CNAs, resulting in tumor enrichment (28 variants) or depletion (25 variants) of the germline variant. Eleven patients received variant disclosure, with clinical measures for five of them. Seven variants in breast cancer-predisposing genes were considered not implicated in oncogenesis. One patient presented significant tumor enrichment of a germline variant in the oncogene ERBB2, in vitro expression of which caused downstream signaling pathway activation.

Conclusion

Tumor sequencing is a powerful approach to refine variant interpretation in cancer-predisposing genes in high-risk breast cancer patients. In this series, the strategy provided clinically relevant information for 11 out of 70 patients (16%), adapted to the considered gene and the familial clinical phenotype.

Growth Rates of Genetically Defined Renal Tumors: Implications for Active Surveillance and Intervention

PURPOSE

Published series of growth rates of renal tumors on active surveillance largely consist of tumors without pathologic or genetic data. Growth kinetics of genetically defined renal tumors are not well known. Here, we evaluate the growth of genetically defined renal tumors and their association with patient clinical and genetic characteristics.

PATIENTS AND METHODS

We evaluated patients with an inherited kidney cancer susceptibility syndrome as a result of a pathologic germline alteration of VHL, MET, FLCN, or BAP1 with at least 1 solid renal mass managed with active surveillance at our institution. Tumor growth rates (GR) were calculated and patients were stratified by genetic alteration and other clinical and genetic factors to analyze differences in growth rates using linear regression and comparative statistics.

RESULTS

A total of 292 patients with 435 genetically defined tumors were identified, including 286 VHL-deficient, 91 FLCN-deficient, 52 MET-activated, and 6 BAP1-deficient tumors. There were significant differences in GRs when stratified by genetic alteration. BAP1-deficient tumors had the fastest median GR (0.6 cm/y; interquartile range [IQR], 0.57-0.68 cm/y), followed by VHL-deficient tumors (GR, 0.37 cm/y; IQR, 0.25-0.57 cm/y), FLCN-deficient tumors (GR, 0.10 cm/y; IQR, 0.04-0.24 cm/y), and tumors with MET activation (GR, 0.15 cm/y; IQR, 0.053-0.32 cm/y; P < .001). Tumors from the same patient had similar GRs. Younger age was independently associated with higher GR (P = .005).

CONCLUSION

In a cohort of genetically defined tumors, tumor growth rates varied in a clinically and statistically different manner according to genetic subtype. Rapid growth of BAP1-deficient tumors indicates that these patients should be managed with caution. The faster growth of tumors in younger patients may support more frequent imaging, whereas the slower growth of other tumors may support extended surveillance beyond annual imaging in some instances.

A Precision Strategy to Cure Renal Cell Carcinoma by Targeting Transglutaminase 2

In a recent report, no significance of transglutaminase 2 (TGase 2) was noted in the analyses of expression differences between normal and clear cell renal cell carcinoma (ccRCC), although we found that knock down of TGase 2 induced significant p53-mediated cell death in ccRCC. Generally, to find effective therapeutic targets, we need to identify targets that belong specifically to a cancer phenotype that can be differentiated from a normal phenotype. Here, we offer precise reasons why TGase 2 may be the first therapeutic target for ccRCC, according to several lines of evidence. TGase 2 is negatively regulated by von Hippel-Lindau tumor suppressor protein (pVHL) and positively regulated by hypoxia-inducible factor 1-α (HIF-1α) in renal cell carcinoma (RCC). Therefore, most of ccRCC presents high level expression of TGase 2 because over 90% of ccRCC showed VHL inactivity through mutation and methylation. Cell death, angiogenesis and drug resistance were specifically regulated by TGase 2 through p53 depletion in ccRCC because over 90% of ccRCC express wild type p53, which is a cell death inducer as well as a HIF-1α suppressor. Although there have been no detailed studies of the physiological role of TGase 2 in multi-omics analyses of ccRCC, a life-long study of the physiological roles of TGase 2 led to the discovery of the first target as well as the first therapeutic treatment for ccRCC in the clinical field.

Identification of Four Pathological Stage-Relevant Genes in Association with Progression and Prognosis in Clear Cell Renal Cell Carcinoma by Integrated Bioinformatics Analysis

Clear cell renal cell carcinoma (ccRCC) is a major histological subtype of renal cell carcinoma and can be clinically divided into four stages according to the TNM criteria. Identifying clinical stage-related genes is beneficial for improving the early diagnosis and prognosis of ccRCC. By using bioinformatics analysis, we aim to identify clinical stage-relevant genes that are significantly associated with the development of ccRCC. First, we analyzed the gene expression microarray data sets: GSE53757 and GSE73731. We divided these data into five groups by staging information-normal tissue and ccRCC stages I, II, III, and IV-and eventually identified 500 differentially expressed genes (DEGs). To obtain precise stage-relevant genes, we subsequently applied weighted gene coexpression network analysis (WGCNA) to the GSE73731 dataset and KIRC data from The Cancer Genome Atlas (TCGA). Two modules from each dataset were identified to be related to the tumor TNM stage. Several genes with high inner connection inside the modules were considered hub genes. The intersection results between hub genes of key modules and 500 DEGs revealed UBE2C, BUB1B, RRM2, and TPX2 as highly associated with the stage of ccRCC. In addition, the candidate genes were validated at both the RNA expression level and the protein level. Survival analysis also showed that 4 genes were significantly correlated with overall survival. In conclusion, our study affords a deeper understanding of the molecular mechanisms associated with the development of ccRCC and provides potential biomarkers for early diagnosis and individualized treatment for patients at different stages of ccRCC.

Hypoxia drives glucose transporter 3 expression through hypoxia-inducible transcription factor (HIF)-mediated induction of the long noncoding RNA NICI

Hypoxia-inducible transcription factors (HIFs) directly dictate the expression of multiple RNA species including novel and as yet uncharacterized long noncoding transcripts with unknown function. We used pan-genomic HIF-binding and transcriptomic data to identify a novel long noncoding RNA Noncoding Intergenic Co-Induced transcript (NICI) on chromosome 12p13.31 which is regulated by hypoxia via HIF-1 promoter-binding in multiple cell types. CRISPR/Cas9-mediated deletion of the hypoxia-response element revealed co-regulation of NICI and the neighboring protein-coding gene, solute carrier family 2 member 3 (SLC2A3) which encodes the high-affinity glucose transporter 3 (GLUT3). Knockdown or knockout of NICI attenuated hypoxic induction of SLC2A3, indicating a direct regulatory role of NICI in SLC2A3 expression, which was further evidenced by CRISPR/Cas9-VPR-mediated activation of NICI expression. We also demonstrate that regulation of SLC2A3 is mediated through transcriptional activation rather than posttranscriptional mechanisms because knockout of NICI leads to reduced recruitment of RNA polymerase 2 to the SLC2A3 promoter. Consistent with this we observe NICI-dependent regulation of glucose consumption and cell proliferation. Furthermore, NICI expression is regulated by the von Hippel-Lindau (VHL) tumor suppressor and is highly expressed in clear cell renal cell carcinoma (ccRCC), where SLC2A3 expression is associated with patient prognosis, implying an important role for the HIF/NICI/SLC2A3 axis in this malignancy.

A transgenic mouse expressing miR-210 in proximal tubule cells shows mitochondrial alteration: possible association of miR-210 with a shift in energy metabolism

Previously we reported that the microRNA miR-210 is aberrantly upregulated in clear cell renal cell carcinoma (ccRCC) via deregulation of the VHL-HIF pathway. In the present study, to investigate the biological impact of miR-210 in ccRCC tumorigenesis, we developed a transgenic mouse line expressing miR-210 in proximal tubule cells under control of the mouse SGLT2/Slc5a2 promoter. Light microscopy revealed desquamation of the tubule cells and regeneration of the proximal tubule, suggesting that miR-210 expression led to damage of the proximal tubule cells. Electron microscopy revealed alterations to the mitochondria in proximal tubule cells, with marked reduction of the mitochondrial inner membrane, which is the main site of ATP production via oxidative phosphorylation (OxPhos). An additional in vitro study revealed that this loss of the inner membrane was associated with downregulation of Iscu and Ndufa4, the target genes of miR-210, suggesting that the miR-210-ISCU/NDUFA4 axis may affect mitochondrial energy metabolism. Furthermore, metabolome analysis revealed activation of anaerobic glycolysis in miR-210-transfected cells, and consistent with this the secretion of lactate, the final metabolite of anaerobic glycolysis, was significantly increased. Lactate concentration was higher in the kidney cortex of transgenic mice relative to wild-type mice, although the difference was not significant (p = 0.070). On the basis of these findings, we propose that miR-210 may induce a shift of energy metabolism from OxPhos to glycolysis by acting on the mitochondrial inner membrane. In addition to activation of glycolysis, we observed activation of the pentose phosphate pathway (PPP) and an increase in the total amount of amino acids in miR-210-transfected cells. This may help cells synthesize nucleotides and proteins for building new cells. These results suggest that miR-210 may be involved in the metabolic changes in the early stage of ccRCC development, helping the cancer cells to acquire growth and survival advantages. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Recent advances in the biology of tumour hypoxia with relevance to diagnostic practice and tissue-based research

In this review article, we examine the importance of low levels of oxygen (hypoxia) in cancer biology. We provide a brief description of how mammalian cells sense oxygen. The hypoxia-inducible factor (HIF) pathway is currently the best characterised oxygen-sensing system, but recent work has revealed that mammals also use an oxygen-sensing system found in plants to regulate the abundance of some proteins and peptides with an amino-terminal cysteine residue. We discuss how the HIF pathway is affected during the growth of solid tumours, which develop in microenvironments with gradients of oxygen availability. We then introduce the concept of 'pseudohypoxia', a state of constitutive, oxygen-independent HIF system activation that occurs due to oncogenic stimulation in a number of specific tumour types that are of immediate relevance to diagnostic histopathologists. We provide an overview of the different methods of quantifying tumour hypoxia, emphasising the importance of pre-analytic factors in interpreting the results of tissue-based studies. Finally, we review recent approaches to targeting hypoxia/HIF system activation for therapeutic benefit, the application of which may require knowledge of which hypoxia signalling components are being utilised by a given tumour. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

An overview of the clinical use of cabozantinib in the treatment of advanced non-clear-cell renal cell carcinoma (NCCRCC)

Patients diagnosed with non-clear renal cell carcinoma have often been excluded from clinical trials due to the shortage of treatments available, the low incidence of tumours with non-clear histology, and the corresponding diversity of intrinsic molecular features. This approach led to a knowledge gap in finding the optimal treatment for patients diagnosed with non-clear cell renal carcinoma. Cabozantinib, a potent multiple tyrosine kinase receptor inhibitor, has been recently investigated in patients with non-clear cell histologies of renal cell cancer. In this review, we have summarized available data on the use of cabozantinib in non-clear renal cell carcinoma.

Deletion of Von Hippel-Lindau Interferes with Hyper Osmolality Induced Gene Expression and Induces an Unfavorable Gene Expression Pattern

Loss of von Hippel–Lindau (VHL) protein function can be found in more than 90% of patients with clear cell renal carcinoma (ccRCC). Mice lacking Vhl function in the kidneys have urine concentration defects due to postulated reduction of the hyperosmotic gradient. Hyperosmolality is a kidney-specific microenvironment and induces a unique gene expression pattern. This gene expression pattern is inversely regulated in patients with ccRCC with consequences for cancer-specific survival. Within this study, we tested the hypothesis if Vhl function influences the hyperosmolality induced changes in gene expression. We made use of the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 technology to inhibit functional Vhl expression in murine collecting duct cell line. Loss of Vhl function induced morphological changes within the cells similar to epithelial to mesenchymal transition like phenotype. Vhl-deficient cells migrated faster and proliferated slower compared to control cells. Gene expression profiling showed significant changes in gene expression patterns in Vhl-deficient cells compared to control cells. Several genes with unfavorable outcomes showed induced and genes with favorable outcomes for patients with renal cancer reduced gene expression level. Under hyperosmotic condition, the expression of several hyperosmolality induced genes, with favorable prognostic value, was downregulated in cells that do not express functional Vhl. Taken together, this study shows that Vhl interferes with hyperosmotic signaling pathway and hyperosmolality affected pathways might represent new promising targets.

Inactivation of BRM/SMARCA2 sensitizes clear cell renal cell carcinoma to histone deacetylase complex inhibitors

BRM, a key subunit of the SWI/SNF chromatin remodeling complex, is an important tumor suppressor gene in multiple tumors. BRM is not mutated, but rather epigenetically silenced in a variety of tumor types, which is different from many anti-cancer genes. In addition, histone deacetylase complex (HDAC) inhibitors are known to reverse BRM silencing, but they also inactivate it via acetylation of its c-terminus. HDAC inhibitors have been reported to be effective at pharmacologically restoring BRM and thereby inhibiting cancer cell growth. But we do not know which HDAC inhibitor, if any, regulate BRM in clear cell renal cell carcinoma (RCC). By using seven types of HDAC inhibitors, we found that Pan-HDAC inhibitors restored BRM protein expression. Despite their ability to restore BRM expression, these HDAC inhibitors also blocked BRM function when present. However, after their removal, we observed that BRM expression remained elevated for several days, and during this period, BRM activity was detected. In addition, HDAC3 and HDAC9 regulate BRM expression and function, especially for HDAC3 inhibitor, RGFP966. Our study demonstrated that knockdown of BRM promoted RCC cells proliferation, migration and invasion. RGFP966 inhibited the tumor progression of clear cell RCC by restoring BRM expression both in vivo and in vitro. In conclusion, HDAC3 is potential targets for clinical treatment, and our study provides a new approach for targeted therapy of BRM-negative clear cell RCC.

The adjuvant treatment of kidney cancer: a multidisciplinary outlook

Approximately 70% of cases of kidney cancer are localized or locally advanced at diagnosis. Among patients who undergo surgery for these cancers, 30-35% will eventually develop potentially fatal metachronous distant metastases. Effective adjuvant treatments are urgently needed to reduce the risk of recurrence of kidney cancer and of dying of metastatic disease. To date, almost all of the tested adjuvant agents have failed to demonstrate any benefit. Only two trials of an autologous renal tumour cell vaccine and of the vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitor sunitinib have shown positive results, but these have been criticized for methodological reasons and conflicting data, respectively. The results of two additional trials of targeted agents as adjuvant therapies have not yet been published. Novel immune checkpoint inhibitors are promising approaches to adjuvant therapy in kidney cancer, and a number of trials are now underway. An important component of the management of patients with kidney cancer, particularly those who undergo radical resection for localized renal cell carcinoma, is the preservation of kidney function to reduce morbidity and mortality. The optimal management of these patients therefore requires a multidisciplinary approach involving nephrologists, oncologists, urologists and pathologists.

Characterization of renal cell carcinoma-associated constitutional chromosome abnormalities by genome sequencing

Constitutional translocations, typically involving chromosome 3, have been recognized as a rare cause of inherited predisposition to renal cell carcinoma (RCC) for four decades. However, knowledge of the molecular basis of this association is limited. We have characterized the breakpoints by genome sequencing (GS) of constitutional chromosome abnormalities in five individuals who presented with RCC. In one individual with constitutional t(10;17)(q11.21;p11.2), the translocation breakpoint disrupted two genes: the known renal tumor suppressor gene (TSG) FLCN (and clinical features of Birt‐Hogg‐Dubé syndrome were detected) and RASGEF1A. In four cases, the rearrangement breakpoints did not disrupt known inherited RCC genes. In the second case without chromosome 3 involvement, the translocation breakpoint in an individual with a constitutional t(2;17)(q21.1;q11.2) mapped 12 Kb upstream of NLK. Interestingly, NLK has been reported to interact indirectly with FBXW7 and a previously reported RCC‐associated translocation breakpoint disrupted FBXW7. In two cases of constitutional chromosome 3 translocations, no candidate TSGs were identified in the vicinity of the breakpoints. However, in an individual with a constitutional chromosome 3 inversion, the 3p breakpoint disrupted the FHIT TSG (which has been reported previously to be disrupted in two apparently unrelated families with an RCC‐associated t(3;8)(p14.2;q24.1). These findings (a) expand the range of constitutional chromosome rearrangements that may be associated with predisposition to RCC, (b) confirm that chromosome rearrangements not involving chromosome 3 can predispose to RCC, (c) suggest that a variety of molecular mechanisms are involved the pathogenesis of translocation‐associated RCC, and (d) demonstrate the utility of GS for investigating such cases.

Circular RNA hsa_circ_001895 serves as a sponge of microRNA-296-5p to promote clear cell renal cell carcinoma progression by regulating SOX12

There is an urgent need to find novel potential therapeutic targets for the diagnosis and treatment of clear cell renal cell carcinoma (ccRCC) due to its highly invasive ability as a common urological malignant tumor. Circular RNAs (circRNAs) have been indicated as potentially critical mediators in various types of tumor progression. We first used qRT-PCR analysis to find dysregulated circRNAs in ccRCC. A novel circRNA, hsa_circ_001895, was upregulated in ccRCC specimens and associated with metastatic properties of ccRCC. However, the tumorigenic mechanism of hsa_circ_001895 on ccRCC is yet to be found. We first indicated that hsa_circ_001895 predicted a poor prognosis in ccRCC patients. Additionally, overexpression of hsa_circ_001895 not only promoted cell proliferation, invasion and migration of ccRCC, but also inhibited cell apoptosis, whereas hsa_circ_001895 knockdown reversed the effect on ccRCC progression. In vivo s.c. xenotransplanted tumor model also showed that silencing hsa_circ_001895 could suppress in vivo ccRCC growth. Mechanistically, hsa_circ_001895 directly binds with microRNA (miR)-296-5p and inhibits its expression. Moreover, sex determining region Y (SRY)-box 12 (SOX12) was identified as a target of miR-296-5p, the expression of which was suppressed by miR-296-5p. Notably, the inhibitory effect of hsa_circ_001895 on ccRCC progression was reversed by miR-296-5p inhibitor. In general, our findings indicated that hsa_circ_001895 may sponge miR-296-5p and promote SOX12 expression, which is the underlying mechanism of hsa_circ_001895-induced ccRCC progression.

Perivascular Neuropilin-1 expression is an independent marker of improved survival in renal cell carcinoma

Renal cell carcinoma (RCC) treatment has improved in the last decade with the introduction of drugs targeting tumor angiogenesis. However, the 5‐year survival of metastatic disease is still only 10–15%. Here, we explored the prognostic significance of compartment‐specific expression of Neuropilin 1 (NRP1), a co‐receptor for vascular endothelial growth factor (VEGF). NRP1 expression was analyzed in RCC tumor vessels, in perivascular tumor cells, and generally in the tumor cell compartment. Moreover, complex formation between NRP1 and the main VEGF receptor, VEGFR2, was determined. Two RCC tissue microarrays were used; a discovery cohort consisting of 64 patients and a validation cohort of 314 patients. VEGFR2/NRP1 complex formation in cis (on the same cell) and trans (between cells) configurations was determined by in situ proximity ligation assay (PLA), and NRP1 protein expression in three compartments (endothelial cells, perivascular tumor cells, and general tumor cell expression) was determined by immunofluorescent staining. Expression of NRP1 in perivascular tumor cells was explored as a marker for RCC survival in the two RCC cohorts. Results were further validated using a publicly available gene expression dataset of clear cell RCC (ccRCC). We found that VEGFR2/NRP1 trans complexes were detected in 75% of the patient samples. The presence of trans VEGFR2/NRP1 complexes or perivascular NRP1 expression was associated with a reduced tumor vessel density and size. When exploring NRP1 as a biomarker for RCC prognosis, perivascular NRP1 and general tumor cell NRP1 protein expression correlated with improved survival in the two independent cohorts, and significant results were obtained also at the mRNA level using the publicly available ccRCC gene expression dataset. Only perivascular NRP1 expression remained significant in multivariable analysis. Our work shows that perivascular NRP1 expression is an independent marker of improved survival in RCC patients, and reduces tumor vascularization by forming complexes in trans with VEGFR2 in the tumor endothelium. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

SETD2 mutation in renal clear cell carcinoma suppress autophagy via regulation of ATG12

Inactivating mutations in the SETD2 gene, encoding for a nonredundant histone H3 methyltransferase and regulator of transcription, is a frequent molecular feature in clear cell renal cell carcinomas (ccRCC). SETD2 deficiency is associated with recurrence of ccRCC and bears low prognostic values. Targeting autophagy, a conserved catabolic process with critical functions in maintenance of cellular homeostasis and cell conservation under stress condition, is emerging as a potential therapeutic strategy to combat ccRCC. Epigenetics-based pathways are now appreciated as key components in the regulation of autophagy. However, whether loss of function in the SETD2 histone modifying enzyme occurring in ccRCC cells may impact on their ability to undergo autophagy remained to be explored. Here, we report that SETD2 deficiency in RCC cells is associated with the aberrant accumulation of both free ATG12 and of an additional ATG12-containing complex, distinct from the ATG5–ATG12 complex. Rescue of SETD2 functions in the SETD2 deficiency in RCC cells, or reduction of SETD2 expression level in RCC cells wild type for this enzyme, demonstrates that SETD2 deficiency in RCC is directly involved in the acquisition of these alterations in the autophagic process. Furthermore, we revealed that deficiency in SETD2, known regulator of alternative splicing, is associated with increased expression of a short ATG12 spliced isoform at the depend of the canonical long ATG12 isoform in RCC cells. The defect in the ATG12-dependent conjugation system was found to be associated with a decrease autophagic flux, in accord with the role for this ubiquitin-like protein conjugation system in autophagosome formation and expansion. Finally, we report that SETD2 and ATG12 gene expression levels are associated with favorable respective unfavorable prognosis in ccRCC patients. Collectively, our findings bring further argument for considering the SETD2 gene status of ccRCC tumors, when therapeutic interventions, such as targeting the autophagic process, are considered to combat these kidney cancers.

PGC1α suppresses kidney cancer progression by inhibiting collagen-induced SNAIL expression

The transcriptional events that promote invasive and metastatic phenotypes in renal cell carcinoma (RCC) remain poorly understood. Here we report that the decreased expression of peroxisome proliferator-activated receptor gamma, coactivator 1 alpha (PGC1α) and the increased expression of several genes encoding collagen family members are associated with RCC tumor progression. PGC1α restoration attenuates invasive phenotypes and suppresses tumor progression in vivo. In contrast, collagens produced by RCC cells promote invasive and migratory phenotypes. PGC1α restoration suppresses the expression of collagens and tumor phenotypes via the induction of miR-29a. Furthermore, decreased collagens via the PGC1α/miR-29a axis suppresses collagen-mediated activation of discoidin domain receptor 1 (DDR1)/ERK signaling. In turn, the suppression of collagen/DDR1 signaling by PGC1α leads to decreased levels of the known EMT regulators SNAIL1 and 2. Collectively, our results demonstrate a novel role for PGC1α in the regulation of proinvasive SNAIL proteins.

Comprehensive Analysis of Copy Number Variations in Kidney Cancer by Single-Cell Exome Sequencing

Clear-cell renal cell carcinoma (ccRCC) is the most common and lethal subtype of kidney cancer. VHL and PBRM1 are the top two significantly mutated genes in ccRCC specimens, while the genetic mechanism of the VHL/PBRM1-negative ccRCC remains to be elucidated. Here we carried out a comprehensive analysis of single-cell genomic copy number variations (CNVs) in VHL/PBRM1-negative ccRCC. Genomic CNVs were identified at the single-cell level, and the tumor cells showed widespread amplification and deletion across the whole genome. Functional enrichment analysis indicated that the amplified genes are significantly enriched in cancer-related signaling transduction pathways. Besides, receptor protein tyrosine kinase (RTK) genes also showed widespread copy number variations in cancer cells. Our studies indicated that the genomic CNVs in RTK genes and downstream signaling transduction pathways may be involved in VHL/PBRM1-negative ccRCC pathogenesis and progression, and highlighted the role of the comprehensive investigation of genomic CNVs at the single-cell level in both clarifying pathogenic mechanism and identifying potential therapeutic targets in cancers.

Prevalence and clinical significance of VHL mutations and 3p25 deletions in renal tumor subtypes

Purpose: To evaluate prevalence and clinical impact of VHL mutations and deletions (3p), a cohort of consecutive kidney tumors was analyzed by DNA sequencing and fluorescence in-situ hybridization (FISH).

Patients and Methods: The study includes 1,805 patients with renal tumors who were surgically treated at the Department of Urology at the University Medical Center Hamburg-Eppendorf between 1994 and 2015. The cohort included 1,176 clear cell, 270 papillary, 101 chromophobe, and 28 clear cell (tubulo) papillary cancers, as well as 149 oncocytomas and 81 less common subtypes.

Results: Among 431 successfully analyzed tumors, VHL mutations were found in 59.3% of clear cell, 5.2% of papillary, 3.1% of chromophobe carcinomas and in 7.3% of oncocytomas as well as in the rare kidney tumor types (25%–60%). FISH analysis was successful in 1,403 cases. 3p25 deletion was found in 57.2% of clear cell, 17.6% of papillary, 17.7% of chromophobe carcinomas and in 11.9% of oncocytomas as well as in the rare kidney tumor types (16.7%–50%). No statistically significant associations between VHL mutation/deletion and tumor grade, stage, and clinical outcome was found. Only in the subgroup of papillary cancers, 3p deletion was significantly associated with lymph node and distant metastasis as well as with poor patient outcome (p < 0.05 each).

Conclusions: The presence of a VHL mutation in virtually all renal tumor subtypes suggests that VHL analysis cannot be used to distinguish between renal tumor subtypes. Consequently, anti-VHL treatment strategies should not be limited to patients with clear cell cancer.

Germline polymorphisms in the Von Hippel-Lindau and Hypoxia-inducible factor 1-alpha genes, gene-environment and gene-gene interactions and renal cell cancer

We investigated the relationship between germline single nucleotide polymorphisms (SNPs) in Von Hippel-Lindau (VHL) and Hypoxia-inducible factor 1-alpha (HIF1A), and their gene-environment and gene-gene interactions, and clear-cell RCC (ccRCC) risk. Furthermore, we assessed the relationship between VHL SNPs and VHL promoter methylation. Three VHL polymorphisms and one HIF1A polymorphism were genotyped in the Netherlands Cohort Study. In 1986, 120,852 participants aged 55–69 completed a self-administered questionnaire on diet and lifestyle and toenail clippings were collected. Toenail DNA was genotyped using the Sequenom MassARRAY platform. After 20.3 years, 3004 subcohort members and 406 RCC cases, of which 263 ccRCC cases, were eligible for multivariate case-cohort analyses. VHL_rs779805 was associated with RCC (Hazard Ratio (HR) 1.53; 95% Confidence Interval (CI) 1.07–2.17) and ccRCC risk (HR 1.88; 95% CI 1.25–2.81). No associations were found for other SNPs. Potential gene-environment interactions were found between alcohol consumption and selected SNPs. However, none remained statistically significant after multiple comparison correction. No gene-gene interactions were observed between VHL and HIF1A. VHL promoter methylation was not associated with VHL SNPs. VHL SNPs may increase (cc)RCC susceptibility. No associations were found between gene-environment and gene-gene interactions and (cc)RCC risk and between VHL promoter methylation and VHL SNPs.