Project description:Altered metabolism is an important part of malignant transformation of tumor cells. Oncogenic transformation may reprogram tumor metabolism and render tumor cells addicted to extracellular nutrients. Such nutrient addictions associated with oncogenic mutations may offer therapeutic opportunities; however, it remains difficult to predict these nutrient addictions. Here, we performed a nutrigenetic screen to determine the phenotypes of isogenic pairs of clear-cell renal cancer cells (ccRCC) with or without VHL upon the deprivation of individual amino acids. We identified that cystine deprivation triggered rapid programmed necrosis in VHL-deficient RCC, but not in their VHL-restored counterparts. Similar cystine addiction was also observed in VHL-deficient primary RCC tumors cells. Blockage of cystine uptake significantly delayed xenograft growth of ccRCC. Importantly, cystine deprivation triggered similar metabolic changes regardless of VHL status. Therefore, metabolic differences due to cystine deprivation are not different enough to readily explain the distinct fate of life vs. death in VHL-deficient and restored cell.. Instead, we found that increased levels of TNFα associated with VHL loss in the VHL-deficient RCC force them to rely on intact RIPK1 to inhibit apoptosis. However, this pre-existing elevated TNFα in the VHL-deficient ccRCC renders these cells susceptible to the necrosis signaling triggered by cystine deprivation. In addition, we identified that cystine-deprived necrosis in VHL-deficient RCC depends on reciprocal amplification of the Src-p38-Noxa signaling and TNFα-RIP1/3-MLKL necrosis pathways that culminate in MLKL oligomerization and programmed necrosis. Together, our data reveal that the contextual cystine-addictions in VHL-deficient ccRCC is dependent on activating pre-existing oncogenic pathways to trigger programmed necrosis. RNA was extracted by RNAeasy kits (Qiagen) from the RCC4 Vec and VHL-reconstituted cells which were exposed to the control full DMEM or cystine deprived DMEM media for 6 hours (three replicates in each condition).
Project description:Altered metabolism is an important part of malignant transformation of tumor cells. Oncogenic transformation may reprogram tumor metabolism and render tumor cells addicted to extracellular nutrients. Such nutrient addictions associated with oncogenic mutations may offer therapeutic opportunities; however, it remains difficult to predict these nutrient addictions. Here, we performed a nutrigenetic screen to determine the phenotypes of isogenic pairs of clear-cell renal cancer cells (ccRCC) with or without VHL upon the deprivation of individual amino acids. We identified that cystine deprivation triggered rapid programmed necrosis in VHL-deficient RCC, but not in their VHL-restored counterparts. Similar cystine addiction was also observed in VHL-deficient primary RCC tumors cells. Blockage of cystine uptake significantly delayed xenograft growth of ccRCC. Importantly, cystine deprivation triggered similar metabolic changes regardless of VHL status. Therefore, metabolic differences due to cystine deprivation are not different enough to readily explain the distinct fate of life vs. death in VHL-deficient and restored cell.. Instead, we found that increased levels of TNFα associated with VHL loss in the VHL-deficient RCC force them to rely on intact RIPK1 to inhibit apoptosis. However, this pre-existing elevated TNFα in the VHL-deficient ccRCC renders these cells susceptible to the necrosis signaling triggered by cystine deprivation. In addition, we identified that cystine-deprived necrosis in VHL-deficient RCC depends on reciprocal amplification of the Src-p38-Noxa signaling and TNFα-RIP1/3-MLKL necrosis pathways that culminate in MLKL oligomerization and programmed necrosis. Together, our data reveal that the contextual cystine-addictions in VHL-deficient ccRCC is dependent on activating pre-existing oncogenic pathways to trigger programmed necrosis.
Project description:Triple-negative breast cancer (TNBC) has a highly aggressive nature and distinct molecular characteristics from other subtypes of breast cancer and lacks effective targeted therapy. The molecular and genetic basis of cysteine/cystine dependency in TNBC is complex. We found that cysteine addiction associates with the expression of a set of Claudin genes in TNBC. The Claudin-high TNBCs are independent on cystine, while the Claudin-low TNBCs undergo rapid ferroptosis upon cystine deprivation or inhibition of cystine transport by erastin. To overcome the resistance of Claudin-high TNBC and luminal breast cancer to the potential targeted cystine-addiction therapy, we explored the synthetic lethality of cysteine by an epigenetic compound library screen. Several potent HDAC6 inhibitors were identified and rendered the Claudin-high TNBCs and luminal cancer cells dependent on extracellular cystine and undergoing ferroptosis upon cystine deprivation. The transcriptomic profiling showed that the HDAC6 inhibitor tubacin in combination with erastin activates a synthetic-lethal transcriptional program. Together, we have identified the HDAC6 inhibitors as potent therapy-sensitizers to revive the targeted cysteine-addiction therapy for various subtypes of breast cancer, not limit in the Claudin-low TNBC.
Project description:Clear-cell renal cell carcinoma (ccRCC) is the most prevalent subtype of renal cell carcinoma (up-to 70% of all RCC types). There is a very close causal correlation between ccRCC and inactivation of the tumor suppressor gene von Hippel-Lindau (VHL) located on chromosome 3p25‐26. Up to 80% of sporadic ccRCC carry genomic mutations or epigenetic inactivation of VHL and nearly 100% familial ccRCC (in VHL disease) contain VHL deficiency. Accumulating evidence has indicated that ccRCC arises at the site of chronic inflammation and this solid tumor contains a substantial number of infiltrated immune cells. This indicates that ccRCC may be induced by the interaction between kidney tubule cells carrying inactivated VHL gene and the inflammatory microenvironment. In this study we characterized the interaction between VHL-deficient kidney tubule cells and macrophages with relevance to ccRCC formation, and found that human macrophages induced by VHL-deficient kidney tubule cells exhibit distinct gene expression program containing the signatures of tumor-associated macrophages that can promote ccRCC progression.
Project description:786-0 is a cell line derived from a clear cell renal carcinoma. Previous studies have shown that the 786-O cell line harbors an inactivating mutation in the von-Hippel Lindau (VHL) gene. Mutations in the VHL gene occur in the majority of sporadic clear cell renal cell. To determine how inactivation of the VHL affects cellular functions, we created a derivative of 786-0, which we call 786-VHL in which a functional allele of VHL has been introduced back into the 786-O cell line. The renal cell carcinoma cell line 786-0, which harbors a mutated allele of VHL, was compared to a cell line derived from 786-0, termed 786-VHL, that contains a functional allele of VHL. Genes whose expression characteristics were dependent on functional VHL were identified.
Project description:The human renal cancer cell line 786-0 was transfected with 3 vectors allowing the doxycycline-inducible expression of 1) the full length wild type sequence of VHL: 786-0 VHL WT, VHL+/+, 2) the R167Q mutant : 786-0 R167Q, VHL mutated, 3) the empty vector : 786-0 EV, VHL-/-. The aim of the study was to examine whether the VHL-R167Q mutation, which is associated with a high risk of developping clear cell renal carcinomas, could impact the plasticity of renal carcinoma cells.
Project description:Clear cell renal cell carcinoma (ccRCC), the most common type of renal cancer is often associated with inactivation of the tumor suppressor gene von-Hippel Lindau (VHL), leading to stable expression of hypoxia inducible factors, HIF1α and HIF2α. Although HIF1α functions as a tumor suppressor gene, majority of ccRCCs constitutively express HIF1α, stratifying VHL-deficient ccRCCs into groups which express either both HIF1α and HIF2α (H1H2) or HIF2α exclusively (H2). MicroRNA (miRNA) profiling performed in these two ccRCC subtypes to identify novel molecular mechanisms.
Project description:Clear cell renal cell carcinoma (ccRCC), the most common type of renal cancer is often associated with inactivation of the tumor suppressor gene von-Hippel Lindau (VHL), leading to stable expression of hypoxia inducible factors, HIF1α and HIF2α. Although HIF1α functions as a tumor suppressor gene, majority of ccRCCs constitutively express HIF1α, stratifying VHL-deficient ccRCCs into groups which express either both HIF1α and HIF2α (H1H2) or HIF2α exclusively (H2). MicroRNA (miRNA) profiling performed in these two ccRCC subtypes to identify novel molecular mechanisms. ccRCCs were classified into H1H2 and H2 subtypes by immunohostochemical staining of H1F1α and H1F2α expression. Five H1H2 tumor samples and eight H2 tumor samples were used for the study. Matched adjacent normal renal tissues were used as respective controls.
Project description:Inactivation of the von Hippel-Lindau tumor suppressor gene, VHL, is an archetypical tumor-initiating event in clear cell renal carcinoma (ccRCC) that leads to the activation of hypoxia-inducible transcription factors (HIFs). However, VHL mutation status in ccRCC is not correlated with clinical outcome. Here we show that during ccRCC progression, cancer cells exploit diverse epigenetic alterations to empower a branch of the VHL-HIF pathway for metastasis, and the strength of this activation is associated with poor clinical outcome. By analyzing metastatic subpopulations of VHL-deficient ccRCC cells, we discovered an epigenetically altered VHL-HIF response that is specific to metastatic ccRCC. Focusing on the two most prominent pro-metastatic VHL-HIF target genes, we show that loss of polycomb repressive complex 2 (PRC2)-dependent histone H3 Lys27 trimethylation (H3K27me3) activates HIF-driven chemokine (C-X-C motif) receptor 4 (CXCR4) expression in support of chemotactic cell invasion, whereas loss of DNA methylation enables HIF-driven cytohesin 1 interacting protein (CYTIP) expression to protect cancer cells from death cytokine signals. Thus, metastasis in ccRCC is based on an epigenetically expanded output of the tumor-initiating pathway. Gene expression profiles of 786-O renal cell carcinoma cells and metastatic subpopulations isoloated by in vivo selection in immunocomrpmized mice. The derivatives are significantly enriched in the metastatic propensity as measure by experimental metastasis assays.
Project description:Renal hypoxia is widespread in acute kidney injury (AKI) of various aetiologies. Hypoxia adaptation, conferred through the hypoxia-inducible factor (HIF), appears to be insufficient. Here we show that HIF activation in renal tubules through Pax8-rtTA-based inducible knockout of von Hippel-Lindau protein (VHL-KO) protects from rhabdomyolysis-induced AKI. In this model, histological observations indicate that injury mainly affects proximal convoluted tubules, with 5% necrosis at d1 and 40% necrosis at d2. HIF-1alpha up-regulation in distal tubules reflects renal hypoxia. However, lack of HIF in proximal tubules suggests insufficient adaptation by HIF. AKI in VHL-KO mice leads to prominent HIF activation in all nephron segments, as well as to reduced serum creatinine, serum urea, tubular necrosis, and apoptosis marker caspase-3 protein. At d1 after rhabdomyolysis, when tubular injury is potentially reversible, HIF mediated protection in AKI is associated with activated glycolysis, cellular glucose uptake and utilization, autophagy, vasodilation, and proton removal as demonstrated by qPCR, pathway enrichment analysis and immunohistochemistry. Together, our data provide evidence for a HIF-orchestrated multi-level shift towards glycolysis as a major mechanism for protection against acute tubular injury. All experiments were carried out in transgenic mice in which selective renal tubular VHL knockout (VHL-KO) was inducible by doxycycline (Reference: Mathia S, Paliege A, Koesters R, Peters H, Neumayer HH, Bachmann S, Rosenberger C. Action of hypoxia-inducible factor in liver and kidney from mice with Pax8-rtTA-based deletion of von Hippel-Lindau protein. Acta Physiol (Oxf). 2013; 207(3):565-76.). Four groups of animals were used: 1) controls: untreated mice; 2) VHL-KO: injected with doxycycline (0.1 mg per 10 g body weight SC), 4 days prior to sacrifice; 3) AKI: rhabdomyolysis; 4) VHL-KO/AKI: doxycycline plus rhabdomyolysis. To induce AKI, 50% glycerol (0.05 ml per 10 g body weight) was injected IM into the left hind limb under isoflurane narcosis. Drinking water was withdrawn between 20 h prior and 24 h after glycerol injection.