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Transcription profiling of human papillary renal cell carcinoma to identify molecular PRCC subclasses with morphologic correlation

ABSTRACT: BACKGROUND: Despite the moderate incidence of papillary renal cell carcinoma; (PRCC), there is a disproportionately limited understanding of its underlying genetic programs. There is no effective therapy for metastatic PRCC, and patients are often excluded from kidney cancer trials. A morphological classification of PRCC into Type 1 and Type 2 tumors has been recently proposed, but its biological relevance remains uncertain. PATIENTS AND METHODS. We studied the gene expression profiles of 34 cases of PRCC using Affymetrix HGU133 Plus 2.0 arrays (54,675 probe sets) using both unsupervised and supervised analysis. Comparative genomic microarray analysis (CGMA) was used to infer cytogenetic aberrations, and pathways were ranked with a curated database. Expression of selected genes was validated by immunohistochemistry in 34 samples, with 15 independent tumors. RESULTS. We identified 2 highly distinct molecular PRCC subclasses with morphologic correlation. The first class, with excellent survival, corresponded to 3 histological subtypes: Type 1, low-grade Type 2 and mixed Type 1/low-grade Type 2 tumors. The second class, with poor survival, corresponded to high-grade Type 2 tumors (n=11). Dysregulation of G1/S and G2/M checkpoint genes were found in Class 1 and Class 2 tumors respectively, alongside characteristic chromosomal aberrations. We identified a 7-transcript predictor that classified samples on cross-validation with 97% accuracy. Immunohistochemistry confirmed high expression of cytokeratin 7 in Class 1 tumors, and of topoisomerase IIa in Class 2 tumors. CONCLUSIONS. We report 2 molecular subclasses of PRCC, which are biologically and clinically distinct, which may be readily distinguished in a clinical setting. Experiment Overall Design: 34 individual samples analyzed, no technical replicates. Based on histologic features and Fuhrman grading system, we designated four categories of tumors: type 1 (n = 14) characterized by small tumor cells of low Fuhrman grade (2); type 2A (n = 4) characterized by large eosinophilic tumor cells of low Fuhrman grade (2); combined type 1 and 2A (n = 5); and type 2B (n = 11) characterized by large eosinophilic tumor cells with Fuhrman grade.

ORGANISM(S): Homo sapiens

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PROVIDER: S-DIXA-D-1082 | biostudies-other |

REPOSITORIES: biostudies-other

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Project description:BACKGROUND: Despite the moderate incidence of papillary renal cell carcinoma; (PRCC), there is a disproportionately limited understanding of its underlying genetic programs. There is no effective therapy for metastatic PRCC, and patients are often excluded from kidney cancer trials. A morphological classification of PRCC into Type 1 and Type 2 tumors has been recently proposed, but its biological relevance remains uncertain. PATIENTS AND METHODS. We studied the gene expression profiles of 34 cases of PRCC using Affymetrix HGU133 Plus 2.0 arrays (54,675 probe sets) using both unsupervised and supervised analysis. Comparative genomic microarray analysis (CGMA) was used to infer cytogenetic aberrations, and pathways were ranked with a curated database. Expression of selected genes was validated by immunohistochemistry in 34 samples, with 15 independent tumors. RESULTS. We identified 2 highly distinct molecular PRCC subclasses with morphologic correlation. The first class, with excellent survival, corresponded to 3 histological subtypes: Type 1, low-grade Type 2 and mixed Type 1/low-grade Type 2 tumors. The second class, with poor survival, corresponded to high-grade Type 2 tumors (n=11). Dysregulation of G1/S and G2/M checkpoint genes were found in Class 1 and Class 2 tumors respectively, alongside characteristic chromosomal aberrations. We identified a 7-transcript predictor that classified samples on cross-validation with 97% accuracy. Immunohistochemistry confirmed high expression of cytokeratin 7 in Class 1 tumors, and of topoisomerase IIa in Class 2 tumors. CONCLUSIONS. We report 2 molecular subclasses of PRCC, which are biologically and clinically distinct, which may be readily distinguished in a clinical setting. Experiment Overall Design: 34 individual samples analyzed, no technical replicates. Based on histologic features and Fuhrman grading system, we designated four categories of tumors: type 1 (n = 14) characterized by small tumor cells of low Fuhrman grade (2); type 2A (n = 4) characterized by large eosinophilic tumor cells of low Fuhrman grade (2); combined type 1 and 2A (n = 5); and type 2B (n = 11) characterized by large eosinophilic tumor cells with Fuhrman grade.

Project description:Rhabdoid histology in clear-cell renal cell carcinoma is associated with a poor prognosis. The prognosis of patients with clear-cell renal cell carcinoma may also be influenced by molecular alterations. The aim of this study was to evaluate the association between histologic features and salient molecular changes in rhabdoid clear-cell renal cell carcinoma. We macrodissected the rhabdoid and clear-cell epithelioid components from 12 cases of rhabdoid clear-cell renal cell carcinoma. We assessed cancer-related mutations from eight cases using a clinical next-generation exome-sequencing platform. The transcriptome of rhabdoid clear-cell renal cell carcinoma (n=8) and non-rhabdoid clear-cell renal cell carcinoma (n=37) was assessed by RNA-seq and gene expression microarray. VHL (63%) showed identical mutations in all regions from the same tumor. BAP1 (38%) and PBRM1 (13%) mutations were identified in the rhabdoid but not in the epithelioid component and were mutually exclusive in 3/3 cases and 1 case, respectively. SETD2 (63%) mutations were discordant between different histologic regions in 2/5 cases, with mutations called only in the epithelioid and rhabdoid components, respectively. The transcriptome of rhabdoid clear-cell renal cell carcinoma was distinct from advanced-stage and high-grade clear-cell renal cell carcinoma. The diverse histologic components of rhabdoid clear-cell renal cell carcinoma, however, showed a similar transcriptomic program, including a similar prognostic gene expression signature. Rhabdoid clear-cell renal cell carcinoma is transcriptomically distinct and shows a high rate of SETD2 and BAP1 mutations and a low rate of PBRM1 mutations. Driver mutations in clear-cell renal cell carcinoma are often discordant across different morphologic regions, whereas the gene expression program is relatively stable. Molecular profiling of clear-cell renal cell carcinoma may improve by assessing for gene expression and sampling tumor foci from different histologic regions.

Project description:Renal medullary carcinomas (RMCs) and collecting duct carcinomas (CDCs) are rare subsets of lethal high-stage, high-grade distal nephron-related adenocarcinomas with a predilection for the renal medullary region. Recent findings have established an emerging group of fumarate hydratase (FH)-deficient tumors related to hereditary leiomyomatosis and renal cell carcinoma (HLRCC-RCCs) syndrome within this morphologic spectrum. Recently developed, reliable ancillary testing has enabled consistent separation between these tumor types. Here, we present the clinicopathologic features and differences in the morphologic patterns between RMC, CDC, and FH-deficient RCC in consequence of these recent developments. This study included a total of 100 cases classified using contemporary criteria and ancillary tests. Thirty-three RMCs (SMARCB1/INI1-deficient, hemoglobinopathy), 38 CDCs (SMARCB1/INI1-retained), and 29 RCCs defined by the FH-deficient phenotype (FH/2SC or FH/2SC with FH mutation, regardless of HLRCC syndromic stigmata/history) were selected. The spectrum of morphologic patterns was critically evaluated, and the differences between the morphologic patterns present in the 3 groups were analyzed statistically. Twenty-five percent of cases initially diagnosed as CDC were reclassified as FH-deficient RCC on the basis of our contemporary diagnostic approach. Among the different overlapping morphologic patterns, sieve-like/cribriform and reticular/yolk sac tumor-like patterns favored RMCs, whereas intracystic papillary and tubulocystic patterns favored FH-deficient RCC. The tubulopapillary pattern favored both CDCs and FH-deficient RCCs, and the multinodular infiltrating papillary pattern favored CDCs. Infiltrating glandular and solid sheets/cords/nested patterns were not statistically different among the 3 groups. Viral inclusion-like macronucleoli, considered as a hallmark of HLRCC-RCCs, were observed significantly more frequently in FH-deficient RCCs. Despite the overlapping morphology found among these clinically aggressive infiltrating high-grade adenocarcinomas of the kidney, reproducible differences in morphology emerged between these categories after rigorous characterization. Finally, we recommend that definitive diagnosis of CDC should only be made if RMC and FH-deficient RCC are excluded.

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Transcription profiling of human papillary renal cell carcinoma to identify molecular PRCC subclasses with morphologic correlation

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