ABSTRACT: Circadian disruption enhances cancer risk, and many tumors exhibit disordered circadian gene expression. We show rhythmic gene expression is unexpectedly robust in clear cell renal cell carcinoma (ccRCC). Furthermore, the clock gene BMAL1 is higher in ccRCC than in healthy kidneys, unlike in other tumor types. BMAL1 is closely related to ARNT and we show that BMAL1-HIF2α regulates a subset of HIF2α target genes in ccRCC cells. Depletion of BMAL1 reprograms HIF2α chromatin association and target gene expression and reduces ccRCC growth in culture and in xenografts. Analysis of pre-existing data reveals higher BMAL1 in patient-derived xenografts that are sensitive to growth suppression by HIF2α antagonists. We show that increasing BMAL1 sensitizes ccRCC-derived A498 cells to growth inhibition by PT2399. Together, these findings indicate that an alternate HIF2α heterodimer containing the circadian partner BMAL1 contributes to HIF2α activity, growth, and sensitivity to HIF2α antagonist drugs in ccRCC cells.
Project description:Circadian disruption enhances cancer risk, and many tumors exhibit disordered circadian gene expression. We show rhythmic gene expression is unexpectedly robust in clear cell renal cell carcinoma (ccRCC). Furthermore, the clock gene BMAL1 is higher in ccRCC than in healthy kidneys, unlike in other tumor types. BMAL1 is closely related to ARNT and we show that BMAL1-HIF2α regulates a subset of HIF2α target genes in ccRCC cells. Depletion of BMAL1 reprograms HIF2α chromatin association and target gene expression and reduces ccRCC growth in culture and in xenografts. Analysis of pre-existing data reveals higher BMAL1 in patient-derived xenografts that are sensitive to growth suppression by HIF2α antagonists. We show that increasing BMAL1 sensitizes ccRCC-derived 786O cells to growth inhibition by PT2399. Together, these findings indicate that an alternate HIF2α heterodimer containing the circadian partner BMAL1 contributes to HIF2α activity, growth, and sensitivity to HIF2α antagonist drugs in ccRCC cells.
Project description:Background: in clear cell renal cell carcinoma (ccRCC), 80% of cases have biallelic inactivation of VHL gene, leading to constitutive activation of both HIF1α and HIF2α. As HIF2α is the driver of the disease promoting tumour growth and metastasis, drugs targeting HIF2α have been developed. However, resistance is common, therefore new therapies are needed. Methods: we generated the 786-0 HIF2α knockout (KO) cell line and assessed the HIF2α antagonist PT2385 in several steps of tumour development. RNA sequencing was performed to identify genes differentially expressed between them and a drug screening was used to identify drugs with differential effects on HIF2α-expressing and KO cells. Results: HIF2α KO promoted cell migration, reduced proliferation and clonogenicity, as well as metastasis, whereas PT2385 treatment only inhibited tumour cell invasion. There was a large set of co-ordinately regulated genes, but HIF2α KO cells also had up-regulation of genes related to EMT and downregulation of genes involving cell migration and extracellular matrix. The HIF2α KO increased sensitivity to statins, while PT2385 had no effect. Conclusions: this study shows new pathways that could be targeted combined with PT2385 to enhance its therapeutic effects and delay resistance.
Project description:We identified ADIRF-AS1 as a BMAL1-CLOCK regulated circadian lncRNA. Loss of ADIRF-AS1 in U2OS cells altered rhythmicity of clock-controlled genes and expression of genes associated with cell adhesion and the extracellular matrix (ECM) but did not affect neighboring genes in cis. Affinity based enrichment of U2OS ADIRF-AS1-interacting proteins identified all components of the tumor suppressive PBAF (PBRM1/BRG1) complex. Because PBRM1 is a tumor suppressor mutated in 40% of clear cell renal carcinoma (ccRCC) cases, we studied ccRCC 786O cells and also found PBRM1 bound to ADIRF-AS1. Reducing ADIRF-AS1 expression in 786O and A498 ccRCC cells decreased expression of PBAF-suppressed genes, consistent with ADIRF-AS1 acting to antagonize the function of PBAF. Loss of PBRM1, however, rescued PBAF responsive cell cycle genes in ADIRF-AS1 KO 786O ccRCC cells. Importantly, ADIRF-AS1 expression correlates with survival in human ccRCC, particularly in PBRM1 wild-type, but not mutant PBRM1 tumors. In this regard, loss of ADIRF-AS1 did not affect in vitro 786O cell growth, but strikingly eliminated in vivo tumorigenesis, which was partially rescued by concurrent loss of PBRM1. This rescue, however, requires Matrigel, suggesting a PBRM1-independent function of ADIRF-AS1 in regulating the ECM. Collectively, our findings suggest that ADIRF-AS1 functions partly to antagonize the tumor suppressive effect of the PBAF complex and behaves as an unforeseen BMAL1-regulated, oncogenic lncRNA.
Project description:HIF2a function is both necessary and sufficient for the growth of VHL-null clear cell Renal Cell Carcinoma (ccRCC). Targeting HIF2a function can therefore be a promising therapeutic strategy. We used microarray analysis to characterize a novel pharmacological inhibitor of HIF2a named PT2399. By comparing genes that are responsive to PT2399 in parental cells vs cells lacking HIF2a, by virtue of CRISPR-mediated genetic editing, we characterized gene signatures that are regulated by PT2399 in a HIF2a dependent manner. Cells were treated with either DMSO (control) or 2uM PT2399 for indicated time periods, total RNA was extracted and analyzed. Please note that the experiments with 786O Parental and HIF2a null cells were conducted independently.
Project description:We identified ADIRF-AS1 as a BMAL1-CLOCK regulated circadian lncRNA. Loss of ADIRF-AS1 in U2OS cells altered rhythmicity of clock-controlled genes and expression of genes associated with cell adhesion and the extracellular matrix (ECM) but did not affect neighboring genes in cis. Affinity based enrichment of U2OS ADIRF-AS1-interacting proteins identified all components of the tumor suppressive PBAF (PBRM1/BRG1) complex. Because PBRM1 is a tumor suppressor mutated in 40% of clear cell renal carcinoma (ccRCC) cases, we studied ccRCC 786O cells and also found PBRM1 bound to ADIRF-AS1. Reducing ADIRF-AS1 expression in 786O and A498 ccRCC cells decreased expression of PBAF-suppressed genes, consistent with ADIRF-AS1 acting to antagonize the function of PBAF. Loss of PBRM1, however, rescued PBAF responsive cell cycle genes in ADIRF-AS1 KO 786O ccRCC cells. Importantly, ADIRF-AS1 expression correlates with survival in human ccRCC, particularly in PBRM1 wild-type, but not mutant PBRM1 tumors. In this regard, loss of ADIRF-AS1 did not affect in vitro 786O cell growth, but strikingly eliminated in vivo tumorigenesis, which was partially rescued by concurrent loss of PBRM1. This rescue, however, requires Matrigel, suggesting a PBRM1-independent function of ADIRF-AS1 in regulating the ECM. Collectively, our findings suggest that ADIRF-AS1 functions partly to antagonize the tumor suppressive effect of the PBAF complex and behaves as an unforeseen BMAL1-regulated, oncogenic lncRNA.
Project description:HIF2a function is both necessary and sufficient for the growth of VHL-null clear cell Renal Cell Carcinoma (ccRCC). Targeting HIF2a function can therefore be a promising therapeutic strategy. We used microarray analysis to characterize a novel pharmacological inhibitor of HIF2a named PT2399. By comparing genes that are responsive to PT2399 in parental cells vs cells lacking HIF2a, by virtue of CRISPR-mediated genetic editing, we characterized gene signatures that are regulated by PT2399 in a HIF2a dependent manner.
Project description:Circadian disruption enhances cancer risk, and many tumors exhibit disordered circadian gene expression. We show rhythmic gene expression is unexpectedly robust in clear cell renal cell carcinoma (ccRCC). Furthermore, the clock gene BMAL1 is higher in ccRCC than in healthy kidneys, unlike in other tumor types. BMAL1 is closely related to ARNT, and we show that BMAL1-HIF2α regulates a subset of HIF2α target genes in ccRCC cells. Depletion of BMAL1 reprograms HIF2α chromatin association and target gene expression and reduces ccRCC growth in culture and in xenografts. Analysis of pre-existing data reveals higher BMAL1 in patient-derived xenografts that are sensitive to growth suppression by a HIF2α antagonist (PT2399). We show that BMAL1-HIF2α is more sensitive than ARNT-HIF2α to suppression by PT2399, and increasing BMAL1 sensitizes 786O cells to growth inhibition by PT2399. Together, these findings indicate that an alternate HIF2α heterodimer containing the circadian partner BMAL1 contributes to HIF2α activity, growth, and sensitivity to HIF2α antagonist drugs in ccRCC cells.
Project description:Using a combination of single-cell RNAseq methods and murine pulmonary hypertension models, we show HIF2α overexpressing pericytes’ transformation into SMC-like cells, confirming HIF2α as a major molecular regulator in hypoxia-induced pulmonary hypertension (PH) and vascular remodeling. We demonstrate that HIF2α overexpression in pericyte-dominant transgenic mice exacerbates PH and right ventricular hypertrophy (RVH), whereas disruption of HIF2α expression attenuates the development of PH.