Conserved patterns of transcriptional dysregulation, heterogeneity and cell states in clear cell kidney cancer [Bulk RNA-seq]
Ontology highlight
ABSTRACT: Clear cell kidney cancers (ccRCC) stem from proximal tubule cells in which the VHL gene has been disrupted, causing activation of HIF transcription factors. Although this is essential for cancer initiation, it not sufficient for development of aggressive tumors. To better understand transcriptional programs underpinning ccRCC progression, we perform single cell transcriptomics on 75 kidney tumor and patient-matched normal kidney biopsies. We describe tumor dysregulated transcriptional programs that are conserved across patients, deconvoluted by cell type. Leveraging recurrent intratumor heterogeneity in chromosome 14q loss, a metastasis-associated copy number alteration, we describe the ensuing transcriptional programs to reveal potential mechanisms priming cells for metastasis. Lastly, we describe co-existing cancer cell states consistently found in all patients, underpinned by distinct transcriptional regulators and whose transcriptional signatures are prognostic. These cancer cell states reflect heterogeneity found in the normal proximal tubule epithelium, strongly indicating that they arise from lineage plasticity.
Project description:Clear cell kidney cancers (ccRCC) stem from proximal tubule cells in which the VHL gene has been disrupted, causing activation of HIF transcription factors. Although this is essential for cancer initiation, it not sufficient for development of aggressive tumors. To better understand transcriptional programs underpinning ccRCC progression, we perform single cell transcriptomics on 75 kidney tumor and patient-matched normal kidney biopsies. We describe tumor dysregulated transcriptional programs that are conserved across patients, deconvoluted by cell type. Leveraging recurrent intratumor heterogeneity in chromosome 14q loss, a metastasis-associated copy number alteration, we describe the ensuing transcriptional programs to reveal potential mechanisms priming cells for metastasis. Lastly, we describe co-existing cancer cell states consistently found in all patients, underpinned by distinct transcriptional regulators and whose transcriptional signatures are prognostic. These cancer cell states reflect heterogeneity found in the normal proximal tubule epithelium, strongly indicating that they arise from lineage plasticity.
Project description:After acute kidney injury (AKI), patients either recover or alternatively develop fibrosis and chronic kidney disease. Interactions between injured epithelia, stroma and inflammatory cells determine whether kidneys repair or undergo fibrosis, but the molecular events that drive these processes are poorly understood. Here, we use single nucleus RNA sequencing of a mouse model of AKI to characterize cell states during repair from acute injury. We identify a distinct proinflammatory and profibrotic proximal tubule cell state that fails to repair. Deconvolution of bulk RNA-seq datasets indicates that this “failed-repair proximal tubule cell” or FR-PTC, state can be detected in other models of kidney injury, increasing in the aging rat kidney and over time in human kidney allografts. We also describe dynamic intercellular communication networks and discern transcriptional pathways driving successful vs. failed repair. Our study provides a detailed description of cellular responses after injury and suggests that the FR-PTC state may represent a therapeutic target to improve repair.
Project description:We combined lineage tracing of cycling (Ki67+) cells with single nuclear multiomics (single nucleus RNA-seq + single nucleus ATAC-seq) to characterize the long-term (4 weeks and 6 months) outcome of cells that initiate proliferation early after acute kidney injury (AKI). The data document a broad proliferative response to injury in epithelial and non-epithelial kidney cell types, identify novel transcription factors governing the adaptive and maladaptive proximal tubule cell state and highlight the importance of enhancer dynamics in determining cell states. Comparison of lineage traced with control proximal tubule cells reveals long-term effects of AKI on proximal tubule cells, even following adaptive repair.
Project description:Clear cell renal cell carcinomas (ccRCC) are characterized by arm-wide chromosomal alterations. Loss at 14q is associated with disease aggressiveness in ccRCC, which responds poorly to chemotherapeutics. The 14q locus contains one of the largest miRNA clusters in the human genome; however, little is known about the contribution of these miRNAs to ccRCC pathogenesis. In this regard, we investigated the expression pattern of selected miRNAs at the 14q32 locus in TCGA kidney tumors and in ccRCC cell lines. We validated that the miRNA cluster is downregulated in ccRCC (and cell lines) as well as in papillary kidney tumors relative to normal kidney tissues and primary renal proximal tubule epithelial (RPTEC) cells. We demonstrated that agents modulating expression of DNMT1 (e.g., 5-Aza-deoxycytidine) could modulate miRNA expression in ccRCC cell lines. Lysophosphatidic acid (LPA, a Lysophospholipid mediator elevated in ccRCC) not only increased labile iron content but also modulated expression of 14q32 miRNAs. Through an overexpression approach targeting a subset of 14q32 miRNAs (specifically at subcluster A: miR-431, miR-432, miR-127, and miR-433) in 769-P cells, we uncovered changes in cellular viability and claudin-1, a tight junction marker. A global proteomic approach was implemented using these miRNA overexpressing cell lines which uncovered ATXN2 as a highly downregulated target, which has a role in chronic kidney disease pathogenesis. Collectively, these findings support a contribution of miRNAs at 14q32 in ccRCC pathogenesis.
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:Injury to the proximal tubule plays a central role in the initiation and progression of kidney fibrosis, and rates of chronic kidney disease progresses approximately 50% faster in males compared to females. We applied Translating Ribosome Affinity Purification (TRAP) followed by RNA-sequencing to characterize the cell-specific proximal tubule transcriptional landscape during fibrosis in male vs. female mice.
Project description:RASSF1A is frequently biallelically inactivated in clear cell renal cell carcinoma (ccRCC) due to loss of chromosome 3p and promoter hypermethylation. Here we investigated the cellular and molecular consequences of single and combined deletion of the Rassf1a and Vhl tumor suppressor genes to model the common ccRCC genotype of combined loss of function of RASSF1A and VHL. In mouse embryonic fibroblasts and in primary kidney epithelial cells, double deletion of Rassf1a and Vhl caused accumulation of chromosomal segregation defects and increased formation of micronuclei, demonstrating that pVHL and RASSF1A function to maintain genomic integrity. Combined Rassf1a and Vhl deletion in renal epithelial cells in vivo increased proliferation and caused mild tubular disorganization, but did not lead to the development of kidney tumors. Single cell RNA-sequencing unexpectedly revealed that Rassf1a deletion or Vhl deletion both induce the expression of an overlapping set of genes in a sub-population of proximal tubule cells. Many of these genes are also upregulated in the Vhl/Trp53/Rb1 deficient mouse model of ccRCC. In other subsets of proximal tubule cells, combined Vhl/Rassf1a deletion induced the expression of additional genes that were not upregulated in each of the single knockouts. The expression of the human homologues of Rassf1a-regulated genes correlate negatively with RASSF1 expression levels in human ccRCC, suggesting that the loss of RASSF1A function establishes a ccRCC-characteristic gene expression pattern.
Project description:RASSF1A is frequently biallelically inactivated in clear cell renal cell carcinoma (ccRCC) due to loss of chromosome 3p and promoter hypermethylation. Here we investigated the cellular and molecular consequences of single and combined deletion of the Rassf1a and Vhl tumor suppressor genes to model the common ccRCC genotype of combined loss of function of RASSF1A and VHL. In mouse embryonic fibroblasts and in primary kidney epithelial cells, double deletion of Rassf1a and Vhl caused accumulation of chromosomal segregation defects and increased formation of micronuclei, demonstrating that pVHL and RASSF1A function to maintain genomic integrity. Combined Rassf1a and Vhl deletion in renal epithelial cells in vivo increased proliferation and caused mild tubular disorganization, but did not lead to the development of kidney tumors. Single cell RNA-sequencing unexpectedly revealed that Rassf1a deletion or Vhl deletion both induce the expression of an overlapping set of genes in a sub-population of proximal tubule cells. Many of these genes are also upregulated in the Vhl/Trp53/Rb1 deficient mouse model of ccRCC. In other subsets of proximal tubule cells, combined Vhl/Rassf1a deletion induced the expression of additional genes that were not upregulated in each of the single knockouts. The expression of the human homologues of Rassf1a-regulated genes correlate negatively with RASSF1 expression levels in human ccRCC, suggesting that the loss of RASSF1A function establishes a ccRCC-characteristic gene expression pattern.
Project description:Loss of a kidney results in compensatory growth of the remaining kidney, a phenomenon of considerable clinical importance. However, the mechanisms involved are largely unknown. Here, we used a multi-omic approach in a mouse unilateral nephrectomy model to identify signaling processes associated with compensatory hypertrophy of the renal proximal tubule. Morphometry applied to microdissected proximal tubules showed that growth of the proximal tubule involves a marked, rapid increase in cell volume rather than cell number. Measurements of DNA accessibility (ATAC-seq), transcriptome (RNA-seq) and proteome (quantitative protein mass spectrometry) independently identified patterns of change that are indicative of activation of the lipid-regulated transcription factor, PPARα. Activation of PPARα by fenofibrate administration increased proximal tubule cell size, while genetic deletion of PPARα in mice decreased it. The results indicate that PPARα is an important determinant of proximal tubule cell size and is a likely mediator of compensatory proximal tubule hypertrophy.
Project description:Global gene expression in the primary cultured mouse kidney proximal tubule cells treated either DMSO or 1uM GW4064 (a FXR agonist) was compared. Results provide insight into mechanisms underlying effects of FXR activation on gene expression in mouse kidney proximal tubule cells. Male C57/BJ mice aged 6 weeks were sacrificed under anesthesia and kidney proximal tubule cells were cultured until confluent. Cells were treated with either GW4064 (1uM) or equal amount of DMSO and incubated for 24 hours. 4 total RNA samples per group were analyzed and gene expression was compared between the groups.