Regulation Of Renal Cell Carcinoma Research Articles

CircRARS synergises with IGF2BP3 to regulate RNA methylation recognition to promote tumour progression in renal cell carcinoma.

As the most prominent RNA modification, N6-methyladenosine (m6 A) participates in the regulation of tumour initiation and progression. Circular RNAs (circRNAs) also play crucial roles in ubiquitous life processes. Whether circRNAs are required for m6 A regulation in renal cell carcinoma (RCC) remains unclear. Meta-analysis and bioinformatics identified that IGF2BP3 was upregulated in RCC and indicated a worse prognosis. IGF2BP3 significantly promoted RCC progression in vitro and in vivo. Mechanistically, circRARS bound to KH1-KH2 domains of IGF2BP3 to enhance m6 A modification recognition. A 12-nt sequence (GUCUUCCAGCAA) was proven to be the IGF2BP3-binding site of circRARS. Additionally, CAPN15, CD44, HMGA2, TNRC6A and ZMIZ2 were screened to be the target genes regulated by the IGF2BP3/circRARS complex in an m6 A-dependent manner. Stabiliser proteins, including HuR, Matrin3 and pAbPC1, were recruited by circRARS, thereby increasing the mRNA stability of the forementioned five target genes. Consequently, the IGF2BP3/circRARS complex facilitated the lipid accumulation of RCC cells and promoted sunitinib resistance via target genes. circRARS synergised with IGF2BP3 to facilitate m6 A recognition, thereby promoting RCC progression. Thus, IGF2BP3 could be a potential biomarker for RCC diagnosis and prognosis and a therapeutic target.

TRIM21 attenuates renal carcinoma lipogenesis and malignancy by regulating SREBF1 protein stability

BackgroundMetabolic reprogramming is a hallmark of various cancers. Targeting metabolic processes is a very attractive treatment for cancer. Renal cell carcinoma (RCC) is a type of metabolic disease, and the lipidomic profile of RCC is significantly altered compared with that of healthy tissue. However, the molecular mechanism underlying lipid metabolism regulation in RCC is not clear.MethodsThe XF long-chain fatty acid oxidative stress test kits were used to assess the dependence on long-chain fatty acids and mitochondrial function after knockdown TRIM21 in RCC cells. The effect of TRIM21 on the lipid content in RCC cells was determined by metabolomics analysis, Oil Red O staining, and cellular Nile red staining. qRT-PCR and western blot were used to explore the relationship between TRIM21 and lipogenesis, and then the key molecule sterol regulatory element binding transcription factor 1 (SREBF1) was identified to interact with TRIM21 by immunoprecipitation, which was also identified in an orthotopic model. Subsequently, the relevance and clinical significance of TRIM21 and SREBF1 were analyzed by The Cancer Genome Atlas (TCGA) database, and 239 tissues were collected from RCC patients.ResultsTRIM21 silencing attenuated the dependence of RCC cells on fatty acids, and enhanced lipid accumulation in RCC cells. TRIM21 overexpression significantly decreased lipid contents by decreasing the expression of lipogenic enzymes via ubiquitination-mediated degradation of SREBF1. SREBF1 is critical for TRIM21-mediated lipogenesis inhibition in vitro and in vivo. Moreover, TRIM21 expression is negatively correlated with SREBF1 expression, and TRIM21-SREBF1 is a reliable combinational biomarker for RCC prognosis.ConclusionThe findings from this study reveal a novel pathway through which TRIM21 inhibits the lipid metabolism process of RCC and shed light on the development of targeted metabolic treatment and prognosis diagnosis of RCC.

The potential of Lycium barbarum miR166a in kidney cancer treatment

Predator species of animal can absorb plant microRNA that can regulate target gene expression and physiological function across species. The herb Lycium barbarum, a traditional Chinese medicine, has a wide range of antitumor effects. However, there are no reports on the effects of microRNA derived from it on the cross-border regulation of renal cell carcinoma (RCC). We performed in vitro and in vivo experiments to explore the role and mechanism of the L. barbarum-derived microRNA miR166a (Lb-miR166a) in cross-border regulation of RCC. Our mRNA sequencing analysis showed that Lb-miR166a regulates the expression of various genes in tumor cells, including 1232 upregulated genes and 581 downregulated genes, which were enriched to 1094 Gene Ontology entries and 43 Kyoto Encyclopedia of Genes and Genomes pathways. In vitro cell experiments confirmed that Lb-miR166a can inhibit the proliferation of RCC cells, promote the apoptosis of tumor cells, and inhibit the invasion and metastasis of tumor cells by regulating the expression of related genes. Furthermore, our in vivo tumor-bearing experiment showed that subcutaneous tumor formation volume decreased in Lb-miR166a mice, along with the number of liver metastases. This study elucidates the role and mechanism of Lb-miR166a in RCC treatment (Fig. 1). Our results further mechanistically confirm the antitumor properties of L. barbarum. Our study may contribute to the clinical development of a targeted drug for RCC treatment.

Pinin acts as a poor prognostic indicator for renal cell carcinoma by reducing apoptosis and promoting cell migration and invasion.

Pinin (PNN) was originally characterized as a desmosome‐associated molecule. Its function and the mechanism of its regulation in renal cell carcinoma (RCC) are still undefined. Data on PNN expression, clinicopathological features, and prognosis of patients with RCC were obtained from The Cancer Genome Atlas (TCGA) database. Immunohistochemistry revealed high PNN expression in tumour cells. PNN expression showed negative correlation with survival in patients with RCC, acting as an independent prognostic factor in RCC. PNN up‐regulation might be attributed to epigenetic alterations in RCC. Immunofluorescence revealed PNN expression mainly in the nucleus of RCC cells. The transfection of siRNA targeting the PNN gene resulted in enhanced apoptosis, which was detected by flow cytometry, and reduced cell migration and invasion, which were assessed using wound healing and transwell migration assay. Gene set enrichment analysis revealed associations between PNN expression and several signalling pathways involved in cancer progression, as a potential mechanism underlying the carcinogenicity of PNN. The analyses of the Tumor Immune Estimation Resource platform showed significant positive associations between high PNN expression and tumour immune infiltrating cells. PNN may function as an oncogenic factor by reducing apoptosis and promoting cell migration and invasion in RCC.

BRDT is a novel regulator of eIF4EBP1 in renal cell carcinoma.

Among all types of kidney diseases, renal cell carcinoma (RCC) has the highest mortality, recurrence and metastasis rates, which results in high numbers of tumor-associated mortalities in China. Identifying a novel therapeutic target has attracted increasing attention. Bromodomain and extraterminal domain (BET) proteins have the ability to read the epigenome, leading to regulation of gene transcription. As an important member of the BET family, bromodomain testis-specific protein (BRDT) has been well studied; however, the mechanism underlying BRDT in the regulation of RCC has not been fully investigated. Eukaryotic translation initiation factor 4E-binding protein 1 (eIF4EBP1) is a binding partner of eIF4E that is involved in affecting the progression of various cancer types via regulating gene transcription. To identify novel regulators of eIF4EBP1, an immunoprecipitation assay and mass spectrometry analysis was performed in RCC cells. It was revealed that eIF4EBP1 interacted with BRDT, a novel interacting protein. In addition, the present study further demonstrated that BRDT inhibitors PLX51107 and INCB054329 blocked the progression of RCC cells, along with suppressing eIF4EBP1 and c-myc expression. Small interfering (si) RNAs were used to knock down BRDT expression, which suppressed RCC cell proliferation and eIF4EBP1 protein expression. In addition, overexpression of eIF4EBP1 partially abolished the inhibited growth function of PLX51107 but knocking down eIF4EBP1 improved the inhibitory effects of PLX51107. Furthermore, treatment with PLX51107 or knockdown of BRDT expression decreased c-myc expression at both the mRNA and protein levels, and attenuated its promoter activity, as determined by luciferase reporter assays. PLX51107 also significantly altered the interaction between the c-myc promoter with eIF4EBP1 and significantly attenuated the increase of RCC tumors, accompanied by decreased c-myc mRNA and protein levels in vivo. Taken together, these data suggested that blocking of BRDT by PLX51107, INCB054329 or BRDT knockdown suppressed the growth of RCC via decreasing eIF4EBP1, thereby leading to decreased c-myc transcription levels. Considering the regulatory function of BET proteins in gene transcription, the present study suggested that there is a novel mechanism underlying eIF4EBP1 regulation by BRDT, and subsequently decreased c-myc in RCC, and further identified a new approach by regulating eIF4EBP1 or c-myc for enhancing BRDT-targeting RCC therapy.

Phosphofructokinase-M inhibits cell growth via modulating the FOXO3 pathway in renal cell carcinoma cells

Phosphofructokinase-M (PFKM) is a key enzyme in glycolysis. The expression and activity of PFKM is closely related to the occurrence and development of malignant tumors, but its role in the regulation of renal cell carcinoma (RCC) is still unknown. We found that the expression of PFKM was lower in RCC tumor tissue than in adjacent normal tissues, and that low expression of PFKM was related to the poor overall survival of RCC patients. In addition, our results showed that FOXO3 mediated PFKM inhibited the growth, migration and invasion of RCC cells, suggesting that PFKM is a protective factor for RCC.

Knockdown of ALPK2 blocks development and progression of renal cell carcinoma

Renal cell carcinoma (RCC) is one of the most common malignant tumors in the urinary system, whose molecular mechanism is still not clear. ALPK2 is a member of alpha protein kinase family, and its relationship with RCC is never reported. In this study, expression of ALPK2 in tumor tissues or cells of RCC was detected by qPCR, western blotting and immunohistochemical analysis. The effects of ALPK2 knockdown on cell proliferation, colony formation, cell migration and apoptosis were assessed by MTT, colony formation assay, wound-healing assay, Transwell assay and flow cytometry, respectively. The influence of ALPK2 knockdown on tumor growth in vivo was evaluated by mice xenograft models. The results demonstrated that ALPK2 was upregulated in tumor tissues of RCC and its high expression was significantly associated with advanced stage and poor prognosis. Knockdown of ALPK2 could inhibited cell proliferation, colony formation and cell migration of RCC cells, while promoting cell apoptosis. The suppression of tumor growth in vivo by ALPK2 knockdown was also showed by using mice xenograft models. Moreover, the regulation of RCC by ALPK2 may involve Akt, CDK6, Cyclin D1 and PIK3CA signaling. Therefore, our studies suggested that ALPK2 may act as a tumor promotor in the development and progression of RCC, and could be considered as a novel therapeutic target for RCC treatment.

SPTLC1 inhibits cell growth via modulating Akt/FOXO1 pathway in renal cell carcinoma cells

Serine palmitoyltransferase long chain-1 (SPTLC1), which is the rate-limiting enzyme for sphingolipid biosynthesis, has been indicated to be essential for carcinoma cell survival and proliferation in recent, but its role in the regulation of renal cell carcinoma (RCC) remains unknown. In the present study, we found that SPTLC1 expression was significantly decreased in RCC tissues compared to non-tumor tissues, and low SPTLC1 expression was associated with poor overall survival of RCC patients. In addition, our results revealed that forced expression of SPTLC1 could significantly inhibit cell growth in vitro and in vivo via, at least in part, modulating Akt/FOXO1 signaling pathway, thus representing a novel role of SPTLC1 in the regulation of tumor growth in RCC for the first time.

Ubiquitin-specific peptidase 46 (USP46) suppresses renal cell carcinoma tumorigenesis through AKT pathway inactivation

USP46, a member of the ubiquitin-specific protease family, plays essential roles in cancer cell proliferation and metastasis and is used as a candidate target for cancer therapeutics. However, the effects of USP46 on renal cell carcinoma (RCC) and its underlying molecular mechanism remain unknown. In this study, the predictive and prognostic relevance of USP46 in RCC, patient-derived primary tissues, and normal liver tissues obtained from the TCGA dataset were analyzed for the USP46 mRNA levels or prognostic relevance. Gain-of-function or loss-of-function assays were used to evaluate the vital roles of USP46 in tumor cell proliferation and cell migration. As a result, the USP46 expression level in RCC is highly decreased compared to normal tissues, and the Kaplan-Meier curve showed that USP46 high expression patients had good prognoses. Functionally, the forced expression of USP46 significantly restrained tumor cell proliferation, colony formation, and cell migration. The shRNA mediated USP46 knockdown cells exhibited the opposite results. We further showed that ectopically expressed USP46 obviously inhibited the AKT signaling pathway in cancer cells, while USP46 depletion caused a dramatic increase in AKT activity reflected by phosphorylation in the serine and threonine residues of AKT or downstream p70S6K1. Importantly, MK2206, a specific AKT inhibitor, completely counteracted the effects on cell proliferation, cell migration, and AKT activity in the USP46 depletion cells. We thus revealed a novel mechanism of USP46 regulation in RCC, and our data indicate that USP46 is a tumor suppressor in RCC via AKT signaling pathway inactivation.

MiR-193a-3p and miR-224 mediate renal cell carcinoma progression by targeting alpha-2,3-sialyltransferase IV and the phosphatidylinositol 3 kinase/Akt pathway.

Tumor metastasis is a major cause of cancer-related death in renal cell carcinoma (RCC). MicroRNAs (miRNAs) have been widely known to modulate proliferation invasion, metastasis, and apoptosis of cancer cells. In this study, we aimed to investigate the function and novel target of miR-193a-3p and miR-224 in RCC. The levels of miR-193a-3p and miR-224 were significantly increased in RCC tissues and RCC cell lines. Alpha-2,3-Sialyltransferase IV (ST3GalIV) was highly expressed in adjacent nontumor tissues and human normal proximal tubular cell line HK-2 compared to RCC tissues and cell lines. ST3GalIV expression was negatively correlated with miR-193a-3p and miR-224. Further analysis indicated that miR-193a-3p and miR-224 directly targeted ST3GalIV. MiR-193a-3p and miR-224 increased cell proliferation and migration by directly inhibiting ST3GalIV, and this effect was reversed by co-transfection with ST3GalIV in vitro. Overexpression of miR-193a-3p and miR-224 increased RCC cell proliferation in vivo. Furthermore, the phosphatidylinositol 3 kinase (PI3K)/Akt pathway was mediated by miR-193a-3p and miR-224 in RCC cell lines. Collectively, these results suggested that miR-193a-3p and miR-224 played an important role in regulation of RCC by targeting ST3GalIV via PI3K/Akt pathway.

HIF-2α/ITPR1 axis: A new saboteur of NK-mediated lysis

We recently investigated the role of von Hippel-Lindau (VHL) mutation and the subsequent induction of hypoxia-inducible factor 2α (HIF-2α) in the regulation of renal cell carcinoma (RCC) susceptibility to natural killer (NK) cell-mediated killing. We demonstrated that the resistance of VHL-mutated RCC cell line 786-0 to NK-mediated lysis requires HIF-2α and ITPR1, a direct novel target of HIF-2α, through the activation of autophagy in target cells by NK-derived signals.

Identification of Key Genes and Pathways in Renal Cell Carcinoma Through Expression Profiling Data

Background/Aims: To isolate key genes and pathways in renal cell carcinoma (RCC), which might reveal more evidences on the regulation network and contribute to pathogenic mechanisms of RCC. Methods: Microarray data of GSE34676, GSE23926 and GSE48008 were downloaded from Gene Expression Omnibus. Differentially expressed genes (DEGs) and differentially expressed miRNAs were respectively screened using Limma package, followed by the selection of CNV associated genes and miRNAs. A multi-molecular regulation interaction network was constructed, and significant modules were subsequently isolated from the network by Molecular Complex Detection (Mcode) of Cytoscape. Finally, GO terms and KEGG pathways of these genes and miRNAs in significant modules were enriched using DAVID. Results: Total 403 DEGs and 231 differentially expressed miRNAs were screened in RCC samples and normal group. Moreover, 1369 genes and 68 miRNAs were isolated by CNV analysis. Besides, a total of 59 miRNAs and 209 genes that related to 340 interaction pairs were analyzed and used to construct the network and 2 significant modules were identified. In the modules, CAV1 and CAV2 were shown to correlate with RCC. GNAI1, GPSM2 and GNAO1 were likely involved in the regulation of RCC through G protein signal transduction. Besides, G-protein coupled receptor protein signaling pathway, focal adhesion, MAPK signaling pathway and neuroactive ligand receptor interaction were enriched. Conclusion: Our study suggests that several crucial genes including CAV1,CAV2, GNAI1, GPSM2, and GNAO1 and pathways may play key roles in RCC progression.

Renal cell neoplasias: reversion-inducing cysteine-rich protein with Kazal motifs discriminates tumor subtypes, while extracellular matrix metalloproteinase inducer indicates prognosis

BackgroundMatrix metalloproteinases can promote invasion and metastasis, which are very frequent in renal cell carcinoma even at the time of diagnosis. Knowing the reversion-inducing cysteine-rich protein with Kazal motifs (RECK) as an inhibitor of matrix metalloproteinases and the extracellular matrix metalloproteinase inducer (EMMPRIN) protein as inducer, we aimed to determine their expression, localization and possible antagonistic action in the pathogenesis and progression of renal cell tumors in a retrospective study.MethodsTumor and adjacent normal tissues of 395 nephrectomized patients were immunostained for RECK and EMMPRIN on a tissue microarray.ResultsRECK strongly decreased in renal cell carcinoma compared to normal counterparts (Wilcoxon signed rank test, P < 0.001), and it discriminated tumor entities showing the highest expression in oncocytomas. EMMPRIN, however, could be significantly correlated to pT stage and Fuhrman grading (Spearman’s correlation coefficient rs = 0.289 and rs = 0.382, respectively). Higher expression of EMMPRIN was associated with decreased overall survival in Kaplan-Meier analysis (P < 0.001), and the EMMPRIN level could independently predict survival for cases without metastasis and involvement of lymph nodes. Decreased RECK expression was confirmed by Western blotting in tissue of eight normal/tumor matches of patients after radical nephrectomy, whereas the EMMPRIN pattern appeared to be heterogeneous.ConclusionsWe propose RECK down regulation in renal cell carcinoma to be an early event that facilitates tumor formation and progression. EMMPRIN, however, as a prognostic tumor marker, increases only when aggressiveness is proceeding and could add an additional step to invasive properties of renal cell carcinoma.

Epigenetic regulation in RCC: opportunities for therapeutic intervention?

Renal cell carcinoma (RCC) is a constellation of malignancies of different histological subtypes arising from the renal parenchyma. The clear cell histological subtype (ccRCC) accounts for around 75% of RCCs and is characterized by distinct genetic abnormalities, of which the loss of function of the von Hippel-Lindau (VHL) tumor suppressor gene is the most common. Inactivation of other tumor suppressor genes such as SETD2, KDM6A, KDM5C and PBRM1 has been reported in ccRCC--notably, the proteins encoded by these genes are involved in histone and chromatin regulation. Furthermore, the PBRM1 and SETD2 genes are located on the short arm of chromosome 3 near the VHL locus. Chromatin and histones modify gene expression and, as a consequence, their function is tightly regulated. Data from RNA interference (RNAi) assays suggest that loss of function of PBRM1 drives proliferation and growth of ccRCC, but the clinical relevance of this is unclear and restoring the function of these genes for therapeutic purposes is likely to be challenging. An improved understanding of histone and chromatin regulation in RCC biology and the consequences of intratumor heterogeneity might identify novel targets in RCC and present alternative therapeutic opportunities.

Abstract 4079: Loss of microtubule-dependent HIF regulation in renal cell carcinoma

Abstract Cancer is a class of deadly diseases that is expected to afflict 1 in 2 American men and 1 in 3 American women. Human cancer frequently exhibits hypoxic conditions, which confers resistance to chemotherapy and radiation therapy, and thus prevents patient survival. The master regulator of cellular response to hypoxia is the hypoxia inducible factor 1α (HIF-1α), a transcription factor that drives the expression of genes that promote cell survival, angiogenesis and metabolic adaptation in low oxygen tension conditions. Interestingly, HIF-1α protein stabilization and activation can occur in well-oxygenated tumors that have lost the VHL gene such as clear cell renal cell carcinomas (RCC). As a result RCCs overexpress HIF-1α and several HIF-1 target genes such as the vascular endothelial growth factor VEGF, the glucose transporter GLUT-1 and others resulting in hypervascularity and aggressive tumor phenotypes. HIF-1α upregulation seems to occur even in the earliest detected neoplastic lesions; hence HIF-1α is considered causal to RCC. Therefore, RCCs that are associated with VHL mutations have been proposed as good candidates for HIF-1 targeted therapy. Our laboratory has previously discovered a new mechanism of HIF-1α and HIF-2α regulation that is microtubule dependent. Specifically, we showed that the taxanes and other microtubule targeting drugs (MTDs) inhibit HIF protein and HIF-transcriptional activity downstream of disrupting cellular microtubules. In addition, we have demonstrated that taxane treatment induces the re-localization of HIF-1α mRNA from actively translating to inactively translating ribosomes, as determined by linear sucrose gradients. Interestingly, current data has demonstrated that this mechanism does not occur in RCCs, as taxane treatment fails to inhibit HIF-1α and HIF-2α in VHL-null RCCs at concentrations that affect microtubules. Interestingly, when we used the isogenic RCC2/VHL and RCC4/VHLcells, in which wild-type VHL was stably re-introduced and able to target HIF for degradation, the ability of taxol or other MTDs to inhibit HIF was not restored. RCC with loss of VHL function is the only tumor type, in our experience, in which HIF is unaffected by taxane treatment. These results suggest that the regulation of HIF protein and function has become independent of the microtubule cytoskeleton in and that this mechanism contributes to the excessive HIF stabilization and the chemoresistant nature of RCCs. We are currently investigating whether the lack of drug-induced HIF inhibition in RCC involves changes in HIF regulation at the level of translation or at the level of protein-dependent susceptibility to microtubule dynamics. Further understanding of the failure of this microtubule dependent regulation of HIF-1α in RCC will help us better elucidate the biology of HIF translation and potentially identify new targets for RCC treatment. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4079.

Ror2, a developmentally regulated kinase, promotes tumor growth potential in renal cell carcinoma

Inappropriate kinase expression and subsequent promiscuous activity defines the transformation of many solid tumors including renal cell carcinoma (RCC). Thus, the expression of novel tumor-associated kinases has the potential to dramatically shape tumor cell behavior. Further, identifying tumor-associated kinases can lend insight into patterns of tumor growth and characteristics. Here, we report the identification of Ror2, a new tumor-associated kinase in RCC cell lines and primary tumors. Ror2 is an orphan receptor tyrosine kinase with physiological expression normally seen in the embryonic kidney. However, in RCC, Ror2 expression correlated with expression of genes involved at the extracellular matrix, including Twist and matrix metalloprotease-2 (MMP2). Expression of MMP2 in RCC cells was suppressed by Ror2 knockdown, placing Ror2 as a mediator of MMP2 regulation in RCC and a potential regulator of extracellular matrix remodeling. The suppression of Ror2 not only inhibited cell migration, but also inhibited anchorage independent growth in soft agar and growth in an orthotopic xenograft model. These findings suggest a novel pathway of tumor-promoting activity by Ror2 within a subset of renal carcinomas, with significant implications for unraveling the tumorigenesis of RCC.