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Sökning: WFRF:(Tumkur Sitaram Raviprakash 1974 )

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1.
  • Laskar, Ruhina S, et al. (författare)
  • Sex specific associations in genome wide association analysis of renal cell carcinoma.
  • 2019
  • Ingår i: European Journal of Human Genetics. - : Nature Publishing Group. - 1018-4813 .- 1476-5438. ; 27:10, s. 1589-1598
  • Tidskriftsartikel (refereegranskat)abstract
    • Renal cell carcinoma (RCC) has an undisputed genetic component and a stable 2:1 male to female sex ratio in its incidence across populations, suggesting possible sexual dimorphism in its genetic susceptibility. We conducted the first sex-specific genome-wide association analysis of RCC for men (3227 cases, 4916 controls) and women (1992 cases, 3095 controls) of European ancestry from two RCC genome-wide scans and replicated the top findings using an additional series of men (2261 cases, 5852 controls) and women (1399 cases, 1575 controls) from two independent cohorts of European origin. Our study confirmed sex-specific associations for two known RCC risk loci at 14q24.2 (DPF3) and 2p21(EPAS1). We also identified two additional suggestive male-specific loci at 6q24.3 (SAMD5, male odds ratio (ORmale) = 0.83 [95% CI = 0.78-0.89], Pmale = 1.71 × 10-8 compared with female odds ratio (ORfemale) = 0.98 [95% CI = 0.90-1.07], Pfemale = 0.68) and 12q23.3 (intergenic, ORmale = 0.75 [95% CI = 0.68-0.83], Pmale = 1.59 × 10-8 compared with ORfemale = 0.93 [95% CI = 0.82-1.06], Pfemale = 0.21) that attained genome-wide significance in the joint meta-analysis. Herein, we provide evidence of sex-specific associations in RCC genetic susceptibility and advocate the necessity of larger genetic and genomic studies to unravel the endogenous causes of sex bias in sexually dimorphic traits and diseases like RCC.
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  • Johansson, Mattias, et al. (författare)
  • The influence of obesity-related factors in the etiology of renal cell carcinoma : A mendelian randomization study
  • 2019
  • Ingår i: PLoS Medicine. - : Public Library of Science. - 1549-1277 .- 1549-1676. ; 16:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Several obesity-related factors have been associated with renal cell carcinoma (RCC), but it is unclear which individual factors directly influence risk. We addressed this question using genetic markers as proxies for putative risk factors and evaluated their relation to RCC risk in a mendelian randomization (MR) framework. This methodology limits bias due to confounding and is not affected by reverse causation.Methods and findings: Genetic markers associated with obesity measures, blood pressure, lipids, type 2 diabetes, insulin, and glucose were initially identified as instrumental variables, and their association with RCC risk was subsequently evaluated in a genome-wide association study (GWAS) of 10,784 RCC patients and 20,406 control participants in a 2-sample MR framework. The effect on RCC risk was estimated by calculating odds ratios (ORSD) for a standard deviation (SD) increment in each risk factor. The MR analysis indicated that higher body mass index increases the risk of RCC (ORSD: 1.56, 95% confidence interval [CI] 1.44–1.70), with comparable results for waist-to-hip ratio (ORSD: 1.63, 95% CI 1.40–1.90) and body fat percentage (ORSD: 1.66, 95% CI 1.44–1.90). This analysis further indicated that higher fasting insulin (ORSD: 1.82, 95% CI 1.30–2.55) and diastolic blood pressure (DBP; ORSD: 1.28, 95% CI 1.11–1.47), but not systolic blood pressure (ORSD: 0.98, 95% CI 0.84–1.14), increase the risk for RCC. No association with RCC risk was seen for lipids, overall type 2 diabetes, or fasting glucose.Conclusions: This study provides novel evidence for an etiological role of insulin in RCC, as well as confirmatory evidence that obesity and DBP influence RCC risk.
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  • Mallikarjuna, Pramod, et al. (författare)
  • Interactions between TGF-β type I receptor and hypoxia-inducible factor-alpha mediates a synergistic crosstalk leading to poor prognosis for patients with clear cell renal cell carcinoma
  • 2019
  • Ingår i: Cell Cycle. - : Taylor & Francis. - 1538-4101 .- 1551-4005. ; 18:17, s. 2141-2156
  • Tidskriftsartikel (refereegranskat)abstract
    • To investigate the significance of expression of HIF-1 alpha, HIF-2 alpha, and SNAIL1 proteins; and TGF-beta signaling pathway proteins in ccRCC, their relation with clinicopathological parameters and patient's survival were examined. We also investigated potential crosstalk between HIF-alpha and TGF-beta signaling pathway, including the TGF-beta type 1 receptor (ALK5-FL) and the intracellular domain of ALK5 (ALK5-ICD). Tissue samples from 154 ccRCC patients and comparable adjacent kidney cortex samples from 38 patients were analyzed for HIF-1 alpha/2 alpha, TGF-beta signaling components, and SNAIL1 proteins by immunoblot. Protein expression of HIF-1 alpha and HIF-2 alpha were significantly higher, while SNAIL1 had similar expression levels in ccRCC compared with the kidney cortex. HIF-2 alpha associated with poor cancer-specific survival, while HIF-1 alpha and SNAIL1 did not associate with survival. Moreover, HIF-2 alpha positively correlated with ALK5-ICD, pSMAD2/3, and PAI-1; HIF-1 alpha positively correlated with pSMAD2/3; SNAIL1 positively correlated with ALK5-FL, ALK5-ICD, pSMAD2/3, PAI-1, and HIF-2 alpha. Intriguingly, in vitro experiments performed under normoxic conditions revealed that ALK5 interacts with HIF-1 alpha and HIF-2 alpha, and promotes their expression and the expression of their target genes GLUT1 and CA9, in a VHL dependent manner. We found that ALK5 induces expression of HIF-1 alpha and HIF-2 alpha, through its kinase activity. Under hypoxic conditions, HIF-alpha proteins correlated with the activated TGF-beta signaling pathway. In conclusion, we reveal that ALK5 plays a pivotal role in synergistic crosstalk between TGF-beta signaling and hypoxia pathway, and that the interaction between ALK5 and HIF-alpha contributes to tumor progression.
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6.
  • Mallikarjuna, Pramod, 1987- (författare)
  • The role of transforming growth factor‐β signaling and hypoxia‐inducible factors in renal cell carcinoma
  • 2019
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Renal cell carcinoma (RCC) is the cancer of the kidneys; about 1100 patients with RCC are diagnosed in Sweden each year. RCC can be classified into several subtypes, clear cell renal cell carcinoma (ccRCC) is most common accounting to about 70% of all RCCs, and also the most lethal; papillary renal cell carcinoma (pRCC) accounts to about 10%‐15%, while chromophobe renal cell carcinoma (chRCC) accounts to about 5% of all RCCs. There is a need to study the distinguishing features of RCC subtypes to design treatment. Von Hippel‐Lindau tumor suppressor gene (VHL) is often inactivated in ccRCC, unlike in pRCC or chRCC. Transforming growth factor‐β (TGF‐β) is a cytokine involved in various biological processes such as differentiation, proliferation, apoptosis, migration, andepithelial‐mesenchymal transition. TGF‐β exerts its functions through canonical (Smad‐dependent) and non‐canonical (Smadindependent) signaling pathways. In the first study, we have shown that both canonical and non‐canonical TGF‐β signaling pathways are associated with ccRCC tumor progression. VHL is known to have a dampening effect on TGF‐β signaling in RCC. However, the effects of pVHL status on the TGF‐β signaling pathway in ccRCC and non-ccRCC has not yet been studied in detail. In the second study, we have investigated the effects of the TGF‐β signaling pathway in the presence or absence of pVHL in ccRCC and non‐ccRCC. We show that, in ccRCC, VHL has an inhibiting effect exclusively on canonical TGF‐β signaling, and has no effect on non‐canonical TGF‐β signaling via ALK5‐ICD. In non‐ccRCC, TGF‐β signaling did not have an effect on tumor progression. Further, we demonstrate that VHL, through its ubiquitin ligases activity ubiquitinates ALK5 in a K48 dependent manner and subjects it to proteasomal degradation. During the normoxic conditions, VHL is implicated in ubiquitination and proteasomal degradation of Hypoxia‐inducible factors (HIFs). In hypoxic conditions or when the loss of VHL occurs, HIFs accumulates in the cytoplasm and enters the nucleus to initiate angiogenesis, cell proliferation, and tumor progression. In the third study, we have explored a potential synergistic cross‐talk between TGF‐β signaling and hypoxia in ccRCC. We demonstrate a correlation between TGF‐β signaling components and HIF‐1α/2α in ccRCC. We have also shown that TGF‐β signaling enhances the expression of HIF‐1α/2α and their target genes even under normoxic conditions, dependent on the kinase activity of ALK5 and dictated by the status of VHL. We present novel data that the synergistic crosstalk between hypoxia and TGF‐β is orchestrated through interactions between ALK5 and HIF‐1α/2α. HIF‐3α is only limited studied, compared with HIF‐1α and HIF‐2α. In the fourth study, we have analyzed the roles of HIF‐3α in ccRCC and pRCC and show that HIF‐3α is associated with advanced stage and metastasized tumors. We also found that HIF‐3α is associated with TRAF6, a crucial component of non‐canonical TGF‐β signaling.
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7.
  • Mallikarjuna, Pramod, et al. (författare)
  • VHL status regulates transforming growth factor-β signaling pathways in renal cell carcinoma
  • 2018
  • Ingår i: OncoTarget. - : Impact Journals, LLC. - 1949-2553 .- 1949-2553. ; 9:23, s. 16297-16310
  • Tidskriftsartikel (refereegranskat)abstract
    • To evaluate the role of pVHL in the regulation of TGF-β signaling pathways in clear cell renal cell carcinoma (ccRCC) as well as in non-ccRCC; the expression of pVHL, and the TGF-β pathway components and their association with clinicopathological parameters and patient’s survival were explored. Tissue samples from 143 ccRCC and 58 non-ccRCC patients were examined by immunoblot. ccRCC cell lines were utilized for mechanistic in-vitro studies. Expression levels of pVHL were significantly lower in ccRCC compared with non-ccRCC. Non-ccRCC and ccRCC pVHL-High expressed similar levels of pVHL. Expression of the TGF-β type I receptor (ALK5) and intra-cellular domain were significantly higher in ccRCC compared with non-ccRCC. In non-ccRCC, expressions of ALK5-FL, ALK5-ICD, pSMAD2/3, and PAI-1 had no association with clinicopathological parameters and survival. In ccRCC pVHL-Low, ALK5-FL, ALK5-ICD, pSMAD2/3, and PAI-1 were significantly related with tumor stage, size, and survival. In ccRCC pVHL-High, the expression of PAI-1 was associated with stage and survival. In-vitro studies revealed that pVHL interacted with ALK5 to downregulate its expression through K48-linked poly-ubiquitination and proteasomal degradation, thus negatively controlling TGF-β induced cancer cell invasiveness. The pVHL status controls the ALK5 and can thereby regulate the TGF-β pathway, aggressiveness of tumors, and survival of the ccRCC and non-ccRCC patients.
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8.
  • Tumkur Sitaram, Raviprakash, 1974-, et al. (författare)
  • Role of Wnt Signaling Pathways in Clear Cell Renal Cell Carcinoma Pathogenesis in Relation to VHL and HIF Status
  • 2020
  • Ingår i: Clinical Oncology and Research. - 2613-4942. ; 3:3
  • Forskningsöversikt (refereegranskat)abstract
    • Renal cell carcinoma (RCC) encompasses various tumor types characterized by a variety of genetic abnormalities. The genetic changes, like mutations, deletions, and epigenetic alterations, can affect the signaling components and signaling networks, causing the modification of tumor pathogenesis and prognosis of RCC. The most prevalent RCC, clear cell RCC (ccRCC), is asymptomatic in the early stages, refractory to chemotherapy and radiation therapy, and has a poorer prognosis compared with the papillary and chromophobe ccRCC types. Loss of the VHL gene and upregulation of oxygen sensors, hypoxia-inducible factor alphas (HIF-α), which promote different growth factors, is a signature of sporadic ccRCC. The VHL-HIF-α and Wnt/β-catenin pathways are closely connected and contribute to the ontogeny of ccRCC. This review confines to ccRCC and the role of the Wnt/β-catenin signaling pathways and its crosstalk with VHL/HIF.
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9.
  • Tumkur Sitaram, Raviprakash, 1974- (författare)
  • Signalling pathways in renal cell carcinoma with a focus on telomerase regulation
  • 2010
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Telomerase is a ribonucleoprotein complex that catalyses telomeric repeat addition at the ends of chromosomes. The catalytic subunit, hTERT, acts as a key determinant for telomerase activity control; the induction of hTERT expression is required for telomerase activity. hTERT participates in cellular immortalization and is elevated in certain malignant tissues. Several tumours exhibit telomerase activity, which contributes to the infinite proliferation capacity that promotes tumour progression. Renal cell carcinoma (RCC) represents 2% of all adult malignancies and has a high mortality rate. The WHO classifies RCC into several sub-types based on cytogenetic aberrations and morphological features; the most prevalent sub-types are clear cell (ccRCC), papillary (pRCC), and chromophobe RCC (chRCC). The aims of this thesis were to study the expression patterns of various signalling molecules, to elucidate the functional links among them, and to define the roles of these signalling molecules in the regulation of hTERT gene expression and telomerase activity in RCC. The first paper included in this thesis revealed mRNA overexpression of DJ-1 (a PTEN inhibitor), cMyc, and hTERT in clinical ccRCC samples compared to tumour-free kidney cortex tissues. Significant, positive correlations were detected for DJ-1, cMyc, and hTERT mRNA levels in ccRCC, but not in pRCC. In vitro knockdown of DJ-1 by siRNA in ccRCC cells induced downregulation of p-Akt, cMyc, hTERT, and telomerase activity. Forced overexpression of DJ-1 in an ovarian carcinoma cell line was followed by increased hTERT promoter activity, which appeared to be dependent on cMYC binding to the promoter. Collectively, the in vitro studies verified a functional link among DJ-1, cMyc, and hTERT as implied in the clinical ccRCC samples. The second paper included in this thesis demonstrated overexpression of NBS1 mRNA levels in ccRCC compared to the kidney cortex. NBS1 mRNA levels exhibited significant, positive correlations with DJ-1, cMyc, and S phase, but not with hTERT. In vitro experiments suggested that DJ-1 could regulate NBS1 gene expression. The role of the hTERT transcriptional repressor WT1 in RCC was evaluated in the third paper included in this thesis. ccRCC samples displayed low WT1 mRNA levels compared to kidney cortex samples. Interestingly, WT1 expression was negatively associated with hTERT and cMyc both of which were elevated in ccRCC. Forced overexpression of WT1 isoforms in a ccRCC cell line increased the expression of several negative transcriptional regulators of hTERT and diminished the expression of hTERT positive regulators. In consequence, hTERT mRNA levels and telomerase activity were reduced. Chromatin immunoprecipitation verified direct binding of WT1 to the cMyc, Smad3, and hTERT promoters. Taken together, these data suggested that in ccRCC, WT1 affects hTERT at the transcriptional level via a combined effect on both positive and negative regulators. In conclusion, DJ-1 can regulate hTERT and telomerase activity through the PI3K pathway encompassing PTEN, NBS1, p-Akt, and cMyc in ccRCC, but not in pRCC. WT1 negatively regulates hTERT and telomerase activity directly and indirectly through multiple pathways in ccRCC.
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10.
  • Tumkur Sitaram, Raviprakash, 1974-, et al. (författare)
  • Significance of PI3K Signalling pathway in clear cell renal cell carcinoma in relation to VHL and HIF status
  • 2021
  • Ingår i: Journal of Clinical Pathology. - : BMJ Publishing Group Ltd. - 0021-9746 .- 1472-4146. ; 74:4, s. 216-222
  • Forskningsöversikt (refereegranskat)abstract
    • Renal cell carcinoma (RCC) includes diverse tumor types characterized by various genetic abnormalities. The genetic changes, like mutations, deletions, and epigenetic alterations, play a crucial role in the modification of signaling networks, tumor 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 typesRCCs. Generally, ccRCC is refractory to chemotherapy and radiation therapy. Loss of 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 PTEN/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 signaling pathways directly or indirectly involved in ccRCC tumor progression, metastasis, angiogenesis, and survival. However, most of these drugs have limitations; either metastatic ccRCC develops resistance to these agents, or despite blocking receptors, tumor cells utilize alternate signaling pathways. This review compiles the state of knowledge about the PI3K/AKT signaling pathway confined to ccRCC and their cross-talks with VHL/HIF pathways.
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