Clear cell sarcomas of the kidney are characterised by BCOR gene abnormalities, including exon 15 internal tandem duplications and BCOR-CCNB3 gene fusion.

AIMS: Clear cell sarcoma of the kidney (CCSK) is a rare paediatric renal malignant tumour. The majority of CCSKs have internal tandem duplications (ITDs) of the BCOR gene, whereas a minority have the YWHAE-NUTM2 gene fusion. A third 'double-negative' (DN) category comprises CCSKs with neither BCOR ITDs nor YWHAE-NUTM2 fusion. The aim of this study was to characterise 11 histologically diagnosed CCSKs immunohistochemically (with CCND1, BCOR and CCNB3 stains) and genetically. METHODS AND RESULTS: By next-generation sequencing, 10 cases (90.9%) had BCOR exon 15 ITDs, with positive BCOR immunoreactivity being found in four (36%) or eight (72%) cases, depending on the antibody clone. By reverse transcription polymerase chain reaction, none had the YWHAE-NUTM2 fusion. The DN case had a BCOR-CCNB3 fusion and strong nuclear CCNB3 and BCOR immunoreactivity. Quantitative polymerase chain reaction showed markedly elevated BCOR expression in this case, whereas BCOR ITD cases had lower levels of elevated BCOR expression. CONCLUSIONS: The majority of the CCSKs in our cohort had BCOR ITDs, and none had the YWHAE-NUTM2 fusion. We verified the strong, diffuse cyclin D1 (CCND1) immunoreactivity in CCSKs described in recent reports. BCOR immunoreactivity was not consistently positive in all CCSKs with BCOR ITDs, and therefore cannot be used as a diagnostic immunohistochemical stain to identify BCOR ITD cases. The DN case was a BCOR-CCNB3 fusion sarcoma. BCOR-CCNB3 sarcoma is typically a primary bone sarcoma affecting male adolescents, and this is the first report of it presenting in a kidney of a young child as a CCSK. The full spectrum of DN CCSKs awaits more comprehensive characterisation.

Signatures of mutation and selection in the cancer genome.

The cancer genome is moulded by the dual processes of somatic mutation and selection. Homozygous deletions in cancer genomes occur over recessive cancer genes, where they can confer selective growth advantage, and over fragile sites, where they are thought to reflect an increased local rate of DNA breakage. However, most homozygous deletions in cancer genomes are unexplained. Here we identified 2,428 somatic homozygous deletions in 746 cancer cell lines. These overlie 11% of protein-coding genes that, therefore, are not mandatory for survival of human cells. We derived structural signatures that distinguish between homozygous deletions over recessive cancer genes and fragile sites. Application to clusters of unexplained homozygous deletions suggests that many are in regions of inherent fragility, whereas a small subset overlies recessive cancer genes. The results illustrate how structural signatures can be used to distinguish between the influences of mutation and selection in cancer genomes. The extensive copy number, genotyping, sequence and expression data available for this large series of publicly available cancer cell lines renders them informative reagents for future studies of cancer biology and drug discovery.

A germline mutation in PBRM1 predisposes to renal cell carcinoma.

BACKGROUND: Many cases of familial renal cell carcinoma (RCC) remain unexplained by mutations in the known predisposing genes or shared environmental factors. There are therefore additional, still unidentified genes involved in familial RCC. PBRM1 is a tumour suppressor gene and somatic mutations are found in 30-45% of sporadic clear cell (cc) RCC. METHODS: We selected 35 unrelated patients with unexplained personal history of ccRCC and at least one affected first-degree relative, and sequenced the PBRM1 gene. RESULTS: A germline frameshift mutation (c.3998_4005del [p.Asp1333Glyfs]) was found in one patient. The patient's mother, his sister and one niece also had ccRCC. The mutation co-segregated with the disease as the three affected relatives were carriers, while an unaffected sister was not, according with autosomal-dominant transmission. Somatic studies supported these findings, as we observed both loss of heterozygosity for the mutation and loss of protein expression in renal tumours. CONCLUSIONS: We show for the first time that an inherited mutation in PBRM1 predisposes to RCC. International studies are necessary to estimate the contribution of PBRM1 to RCC susceptibility, estimate penetrance and then integrate the gene into routine clinical practice.

Folliculin interacts with p0071 (plakophilin-4) and deficiency is associated with disordered RhoA signalling, epithelial polarization and cytokinesis.

Inherited mutations in the folliculin (FLCN) gene cause the Birt-Hogg-Dubé syndrome of familial hair follicle tumours (fibrofolliculomas), lung cysts and kidney tumours. Though folliculin has features of a tumour suppressor, the precise function of the FLCN gene product is not well characterized. We identified plakophilin-4 (p0071) as a potential novel folliculin interacting protein by yeast two-hybrid analysis. We confirmed the interaction of folliculin with p0071 by co-immunoprecipitation studies and, in view of previous studies linking p0071 to the regulation of rho-signalling, cytokinesis and intercellular junction formation, we investigated the effect of cell folliculin status on p0071-related functions. Folliculin and p0071 partially co-localized at cell junctions and in mitotic cells, at the midbody during cytokinesis. Previously, p0071 has been reported to regulate RhoA signalling during cytokinesis and we found that folliculin deficiency was associated with increased expression and activity of RhoA and evidence of disordered cytokinesis. Treatment of folliculin-deficient cells with a downstream inhibitor of RhoA signalling (the ROCK inhibitor Y-27632) reversed the increased cell migration phenotype observed in folliculin-deficient cells. Deficiency of folliculin and of p0071 resulted in tight junction defects and mislocalization of E-cadherin in mouse inner medullary collecting duct-3 renal tubular cells. These findings suggest that aspects of folliculin tumour suppressor function are linked to interaction with p0071 and the regulation of RhoA signalling.

Chromosomal amplification of leucine-rich repeat kinase-2 (LRRK2) is required for oncogenic MET signaling in papillary renal and thyroid carcinomas.

The receptor tyrosine kinase MET is frequently amplified in human tumors, resulting in high cell surface densities and constitutive activation even in the absence of growth factor stimulation by its endogenous ligand, hepatocyte growth factor (HGF). We sought to identify mechanisms of signaling crosstalk that promote MET activation by searching for kinases that are coordinately dysregulated with wild-type MET in human tumors. Our bioinformatic analysis identified leucine-rich repeat kinase-2 (LRRK2), which is amplified and overexpressed in papillary renal and thyroid carcinomas. Down-regulation of LRRK2 in cultured tumor cells compromises MET activation and selectively reduces downstream MET signaling to mTOR and STAT3. Loss of these critical mitogenic pathways induces cell cycle arrest and cell death due to loss of ATP production, indicating that MET and LRRK2 cooperate to promote efficient tumor cell growth and survival in these cancers.

Functional importance of Dicer protein in the adaptive cellular response to hypoxia.

The processes by which cells sense and respond to ambient oxygen concentration are fundamental to cell survival and function, and they commonly target gene regulatory events. To date, however, little is known about the link between the microRNA pathway and hypoxia signaling. Here, we show in vitro and in vivo that chronic hypoxia impairs Dicer (DICER1) expression and activity, resulting in global consequences on microRNA biogenesis. We show that von Hippel-Lindau-dependent down-regulation of Dicer is key to the expression and function of hypoxia-inducible factor α (HIF-α) subunits. Specifically, we show that EPAS1/HIF-2α is regulated by the Dicer-dependent microRNA miR-185, which is down-regulated by hypoxia. Full expression of hypoxia-responsive/HIF target genes in chronic hypoxia (e.g. VEGFA, FLT1/VEGFR1, KDR/VEGFR2, BNIP3L, and SLC2A1/GLUT1), the function of which is to regulate various adaptive responses to compromised oxygen availability, is also dependent on hypoxia-mediated down-regulation of Dicer function and changes in post-transcriptional gene regulation. Therefore, functional deficiency of Dicer in chronic hypoxia is relevant to both HIF-α isoforms and hypoxia-responsive/HIF target genes, especially in the vascular endothelium. These findings have relevance to emerging therapies given that we show that the efficacy of RNA interference under chronic hypoxia, but not normal oxygen availability, is Dicer-dependent. Collectively, these findings show that the down-regulation of Dicer under chronic hypoxia is an adaptive mechanism that serves to maintain the cellular hypoxic response through HIF-α- and microRNA-dependent mechanisms, thereby providing an essential mechanistic insight into the oxygen-dependent microRNA regulatory pathway.

Deregulation of E2-EPF ubiquitin carrier protein in papillary renal cell carcinoma.

Molecular pathways associated with pathogenesis of sporadic papillary renal cell carcinoma (PRCC), the second most common form of kidney cancer, are poorly understood. We analyzed primary tumor specimens from 35 PRCC patients treated by nephrectomy via gene expression analysis and tissue microarrays constructed from an additional 57 paraffin-embedded PRCC samples via immunohistochemistry. Gene products were validated and further studied by Western blot analyses using primary PRCC tumor samples and established renal cell carcinoma cell lines, and potential associations with pathologic variables and survival in 27 patients with follow-up information were determined. We show that the expression of E2-EPF ubiquitin carrier protein, which targets the principal negative regulator of hypoxia-inducible factor (HIF), von Hippel-Lindau protein, for proteasome-dependent degradation, is markedly elevated in the majority of PRCC tumors exhibiting increased HIF1α expression, and is associated with poor prognosis. In addition, we identified multiple hypoxia-responsive elements within the E2-EPF promoter, and for the first time we demonstrated that E2-EPF is a hypoxia-inducible gene directly regulated via HIF1. These findings reveal deregulation of the oxygen-sensing pathway impinging on the positive feedback mechanism of HIF1-mediated regulation of E2-EPF in PRCC.

Downregulation of CASR expression and global loss of parafibromin staining are strong negative determinants of prognosis in parathyroid carcinoma.

Parathyroid carcinoma is associated with mutations in the HRPT2/CDC73 gene and with decreased parafibromin and calcium-sensing receptor (CASR) expression, but in some cases establishing an unequivocal diagnosis remains a challenge. The aim of our study was to evaluate the prognostic value of CASR and parafibromin expression and of HRPT2/CDC73 mutations in patients with an established diagnosis of parathyroid carcinoma. Data on survival and disease-free survival were obtained from hospital records of 23 patients with an established diagnosis of parathyroid carcinoma in whom CASR and parafibromin expression and HRPT2/CDC73 mutation analyses were available from paraffin-embedded pathological specimens. Kaplan-Meier curves were used for survival analysis. Downregulation of CASR expression, global loss of parafibromin staining and a HRPT2/CDC73 mutation were, respectively, found in 7 (30%), 13 (59%) and 4 (17%) patients, and were associated with, respectively, 16-fold, 4-fold and 7-fold increased risk of developing local or distant metastasis. These findings suggest that although downregulation of CASR expression, global loss of parafibromin staining and mutations in the HRPT2/CDC73 gene are tools of proven value to assist in establishing a diagnosis of parathyroid carcinoma, their absence does not exclude it. Notwithstanding, we demonstrate a significant added value of these markers as strong determinants of increased malignant potential and thus as negative prognostic markers in this malignancy.

Kinase targets in renal-cell carcinomas: reassessing the old and discovering the new.

Renal-cell carcinoma is a heterogeneous group of tumours that arise in the adult kidneys. Irrespective of the type of renal tumour, traditional chemotherapeutic and radiation-based therapies have been largely ineffective at treating advanced tumours, with long-term survival being very low. Molecularly-targeted inhibitors of protein kinases are effective in delaying progression of advanced renal tumours. These therapies revolve around inhibition of the vascular endothelial growth factor receptor tyrosine kinase and the mammalian target of rapamycin serine or threonine kinase signalling pathways. The genetic complexity of renal tumours revealed by gene-expression profiling and other molecular-genetic technologies indicate that inhibition of additional kinase-associated pathways could also prevent renal tumour growth. In this review, we discuss the use of molecularly-targeted kinase inhibitors in the treatment of renal-cell carcinoma and identify the next generation of kinase inhibitors that show promise for treatment.

The tumor suppressor parafibromin is required for posttranscriptional processing of histone mRNA.

Parafibromin, encoded by the gene HRPT2, is a tumor suppressor protein associated with the RNA polymerase II-associated complex, Paf1 complex. HRPT2 mutations were first identified in patients with the multiple endocrine neoplasia syndrome, hyperparathyroidism-jaw tumor (HPT-JT) syndrome, and have also been found in sporadic parathyroid and renal tumors. However, the mechanisms by which parafibromin suppresses tumor formation remain unknown. In this study, we identify a novel role of parafibromin in the regulation of replication-dependent histones. Both in vitro and in vivo analyses reveal a posttranscriptional role of parafibromin in histone mRNA processing. Downregulation of parafibromin through RNA interference or in vivo mutations lead to uncleaved histone mRNA with polyadenylated tails. These results indicate that parafibromin regulates the 3' processing of histone RNA, an essential component of the cell cycle.

Prospective clinical trial of preoperative sunitinib in patients with renal cell carcinoma.

PURPOSE: Sunitinib is an approved treatment for metastatic renal cell carcinoma. We performed a prospective clinical trial to evaluate the safety and clinical response to sunitinib administered before nephrectomy in patients with localized or metastatic clear cell renal cell carcinoma. MATERIALS AND METHODS: Patients with biopsy proven clear cell renal cell carcinoma were enrolled in the study and treated with 37.5 mg sunitinib malate daily for 3 months before nephrectomy. The primary end point was safety. RESULTS: In an 18-month period 20 patients were enrolled. The most common toxicities were gastrointestinal symptoms and hematological effects. Grade 3 toxicity developed in 6 patients (30%). No surgical complications were attributable to sunitinib treatment. Of the 20 patients 17 (85%) experienced reduced tumor diameter (mean change -11.8%, range -27% to 11%) and cross-sectional area (mean change -27.9%, range -43% to 23%). Enhancement on contrast enhanced computerized tomography decreased in 15 patients (mean HU change -22%, range -74% to 29%). After tumor reduction 8 patients with cT1b disease underwent laparoscopic partial nephrectomy. Surgical parameters, such as blood loss, transfusion rate, operative time and complications, were similar to those in patients who underwent surgery during the study period and were not enrolled in the trial. CONCLUSIONS: Preoperative treatment with sunitinib is safe. Sunitinib decreased the size of primary renal cell carcinoma in 17 of 20 patients. Future trials can be considered to evaluate neoadjuvant sunitinib to maximize nephron sparing and decrease the recurrence of high risk, localized renal cell carcinoma.

VHL promotes E2 box-dependent E-cadherin transcription by HIF-mediated regulation of SIP1 and snail.

The product of the von Hippel-Lindau gene (VHL) acts as the substrate-recognition component of an E3 ubiquitin ligase complex that ubiquitylates the catalytic alpha subunit of hypoxia-inducible factor (HIF) for oxygen-dependent destruction. Although emerging evidence supports the notion that deregulated accumulation of HIF upon the loss of VHL is crucial for the development of clear-cell renal cell carcinoma (CC-RCC), the molecular events downstream of HIF governing renal oncogenesis remain unclear. Here, we show that the expression of a homophilic adhesion molecule, E-cadherin, a major constituent of epithelial cell junctions whose loss is associated with the progression of epithelial cancers, is significantly down-regulated in primary CC-RCC and CC-RCC cell lines devoid of VHL. Reintroduction of wild-type VHL in CC-RCC (VHL(-/-)) cells markedly reduced the expression of E2 box-dependent E-cadherin-specific transcriptional repressors Snail and SIP1 and concomitantly restored E-cadherin expression. RNA interference-mediated knockdown of HIFalpha in CC-RCC (VHL(-/-)) cells likewise increased E-cadherin expression, while functional hypoxia or expression of VHL mutants incapable of promoting HIFalpha degradation attenuated E-cadherin expression, correlating with the disengagement of RNA polymerase II from the endogenous E-cadherin promoter/gene. These findings reveal a critical HIF-dependent molecular pathway connecting VHL, an established "gatekeeper" of the renal epithelium, with a major epithelial tumor suppressor, E-cadherin.

Prognostic value of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and TRAIL receptors in renal cell cancer.

PURPOSE: The death ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and its receptors (TRAIL-R) are involved in immune surveillance and tumor development. Here, we studied a possible association between the expression of TRAIL/TRAIL-Rs and the prognosis in patients with renal cell carcinomas (RCC). EXPERIMENTAL DESIGN: A tissue microarray containing RCC tumor tissue samples and corresponding normal tissue samples from 838 patients was generated. Expression of TRAIL and TRAIL-Rs was examined by immunohistochemistry and the effect of TRAIL and TRAIL-R expression on disease-specific survival was assessed. RESULTS: High TRAIL-R2 expression levels were associated with high-grade RCCs (P < 0.001) and correlated negatively with disease-specific survival (P = 0.01). Similarly, high TRAIL expression was associated with a shorter disease-specific survival (P = 0.01). In contrast, low TRAIL-R4 expression was associated with high-stage RCCs (P < 0.001) as well as with the incidence of distant metastasis (P = 0.03) and correlated negatively with disease-specific survival (P = 0.02). In patients without distant metastasis, multivariate Cox regression analyses revealed that TRAIL-R2 and TRAIL are independent prognostic factors for cancer-specific survival (in addition to tumor extent, regional lymph node metastasis, grade of malignancy, and type of surgery). CONCLUSION: High TRAIL-R2, high TRAIL, and low TRAIL-R4 expression levels are associated with a worse disease-specific survival in patients with RCCs. Therefore, the assessment of TRAIL/TRAIL-R expression offers valuable prognostic information that could be used to select patients for adjuvant therapy studies. Moreover, our findings are of relevance for a potential experimental therapeutic administration of TRAIL-R agonists in patients with RCCs.

Functional and genetic characterization of three cell lines derived from a single tumor of an Opisthorchis viverrini-associated cholangiocarcinoma patient.

Three cholangiocarcinoma (CCA) cell line-formerly named, M156, M213 and M214 have been intensively used with discrepancy of their tumor origins. They were assumed to be originated from three different donors without authentication. To verify the origins of these cell lines, the short tandem repeat (STR) analysis of the currently used cell lines, the cell stocks from the establisher and the primary tumor of a CCA patient were performed. Their phenotypic and genotypic originality were compared. The currently used 3 CCA cell lines exhibited similar STR as CCA patient ID-M213 indicating the same origin of these cells. The cell stocks from the establisher, however, revealed the same STR of M213 and M214 cells, but not M156. The misidentification of M214 and M156 is probably due to the mislabeling and cross-contamination of M213 cells during culture. These currently used cell lines were renamed as KKU-213A, -213B and -213C, for the formerly M213, M214 and M156 cells, respectively. These cell lines were established from a male with an intrahepatic mass-forming CCA stage-4B. The tumor was an adenosquamous carcinoma with the liver fluke ova granuloma in evidence. All cell lines had positive CK19 with differential CA19-9 expression. They exhibited aneuploidy karyotypes, distinct cell morphology, cell growth, cytogenetic characteristic and progressive phenotypes. KKU-213C formed a adenosquamous carcinoma, whereas KKU-213A and KKU-213B formed poorly- and well-differentiated squamous cell carcinomas in xenografted mice. mRNA microarray revealed different expression profiles among these three cell lines. The three cell lines have unique characteristics and may resemble the heterogeneity of tumor origin.

Accuracy of combined protein gene product 9.5 and parafibromin markers for immunohistochemical diagnosis of parathyroid carcinoma.

CONTEXT: Parafibromin, encoded by HRPT2, is the first marker with significant benefit in the diagnosis of parathyroid carcinoma. However, because parafibromin is only involved in up to 70% of parathyroid carcinomas and loss of parafibromin immunoreactivity may not be observed in all cases of HRPT2 mutation, a complementary marker is needed. OBJECTIVE: We sought to determine the efficacy of increased expression of protein gene product 9.5 (PGP9.5), encoded by ubiquitin carboxyl-terminal esterase L1 (UCHL1) as an additional marker to loss of parafibromin immunoreactivity for the diagnosis of parathyroid carcinoma. DESIGN: In total, 146 parathyroid tumors and nine normal tissues were analyzed for the expression of parafibromin and PGP9.5 by immunohistochemistry and for UCHL1 by quantitative RT-PCR. These samples included six hyperparathyroidism-jaw tumor syndrome-related tumors and 24 sporadic carcinomas. RESULTS: In tumors with evidence of malignancy, strong staining for PGP9.5 had a sensitivity of 78% for the detection of parathyroid carcinoma and/or HRPT2 mutation and a specificity of 100%. Complete lack of nuclear parafibromin staining had a sensitivity of 67% and a specificity of 100%. PGP9.5 was positive in a tumor with the HRPT2 mutation L64P that expressed parafibromin. Furthermore, UCHL1 was highly expressed in the carcinoma/hyperparathyroidism-jaw tumor syndrome group compared to normal (P < 0.05) and benign specimens (P < 0.001). CONCLUSION: These results suggest that positive staining for PGP9.5 has utility as a marker for parathyroid malignancy, with a slightly superior sensitivity (P = 0.03) and similar high specificity to that of parafibromin.

A comparison study reveals important features of agreement and disagreement between summarized DNA and RNA data obtained from renal cell carcinoma.

Cytogenetic abnormalities, such as DNA amplifications and deletions, often lead to significant changes in gene expression levels within a chromosomal region. Instead of generating additional DNA copy number data, one method to identify DNA copy number abnormalities has been to search existing gene expression data for regional perturbations in gene expression. However, it is not clear how well this surrogate method performs in the examination of individual tumors and how we can use both DNA and RNA data to identify candidate genes that may be mutated. Here we report a comparison study using summarized DNA and RNA data to identify chromosomal abnormalities in human samples. Forty-four tissue samples from patients diagnosed as having renal cell carcinoma (RCC) were collected, together with 15 normal kidney samples as controls, and for each sample the genome-wide DNA and RNA data were obtained for comparison using Affymetrix 100K SNP and HGU133plus2 gene expression chips, respectively. The DNA and RNA data was summarized by both chromosome arm and cytogenetic banding patterns and compared. The result of this analysis revealed that the two summarized data sets used to identify cytogenetic changes agreed well. However, some differences between the two were also identified. These differences of large-scale gene expression deregulation without evidence of the comparable DNA copy number alterations may be the result of known mechanisms, such as large-scale methylation or chromosome inactivation, or may be the result of some new mechanism of DNA-RNA translation. The usefulness of the combined data set for identifying regions of mutated genes is also discussed.

Human kidney injury molecule-1 (hKIM-1): a useful immunohistochemical marker for diagnosing renal cell carcinoma and ovarian clear cell carcinoma.

Human kidney injury molecule-1 (hKIM-1), a type I transmembrane glycoprotein expressed in injured renal proximal tubules, was also found in renal cell carcinoma (RCC). The current study attempts to evaluate the diagnostic utility of hKIM-1 in a large series of 480 neoplasms including defined subtypes of renal cell tumors, metastatic RCCs, and nonrenal tumors. Tissue microarray (TMA) sections containing 179 renal cell tumors (73 clear cell RCC, 30 papillary RCC, 16 chromophobe RCC, 15 oncocytoma, and 45 metastatic RCC) were included in this study. In addition, 80 cases of renal cell neoplasm and 221 nonrenal tumors in routine tissue sections were also included. Both TMA and routine sections were incubated with anti-hKIM-1 monoclonal antibody using an EnVision-HRP kit. The results demonstrated that a membranous/cytoplasmic staining pattern for hKIM-1 was observed in 54 of 73 (74%) clear cell RCCs and 28 of 30 (93%) papillary RCCs on TMA sections. Zero of 54 chromophobe RCCs and 4 of 41 (9.75%) oncocytomas were positive for hKIM-1 when combining TMA and routine sections. Similar staining results were observed in 35 of 45 (78%) metastatic RCCs. Data from cDNA microarray expression and Western blot demonstrated similar findings. Fifteen of 16 cases (93.8%) of clear cell carcinoma of the ovary demonstrated positive reactivity for hKIM-1. These data indicate that hKIM-1: (1) is a relatively sensitive and specific marker for papillary, clear cell, and metastatic RCCs, (2) can be used to distinguish clear cell from chromophobe RCC, and (3) may serve as a diagnostic marker for clear cell carcinoma of the ovary.

Renal papillary adenoma--a putative precursor of papillary renal cell carcinoma.

The precursor lesions of renal cell carcinoma (RCC) are unknown. The purpose of this study is to determine the incidence, histomorphological features, and immunohistochemical features of papillary adenoma and elucidate its potential relationship to RCC. We reviewed 542 consecutive nephrectomy specimens over an 8-year period. Immunohistochemistry was carried out with antibodies specific for alpha-methyl-coenzyme A racemase (AMACR) and glutathione S-transferase alpha (clear-cell RCC marker). Thirty-eight (7%) nephrectomy specimens showed histologic evidence of papillary adenoma. Of these 38 cases, 18 (47%) arose in the setting of papillary RCC (PRCC). Seven papillary adenomas (18%) occurred in the setting of acquired polycystic kidney disease (APKD), 6 in clear-cell RCCs, 3 in chromophobe RCCs, 2 in end-stage kidney disease, 1 in oncocytoma, 1 in angiomyolipoma, and 1 in renal schwannoma. Furthermore, papillary adenomas were more commonly found in kidneys removed for PRCC (25%, 18/71) than in kidneys harboring clear-cell RCC (1.9%, 6/318). Histomorphologically, papillary adenomas were characterized by varying proportions of papillae and tubules formed by cuboidal cells with scant basophilic cytoplasm similar to those in type 1 PRCC. Adenomas associated with PRCC tend to be multiple in number (61% [11/18] of cases had >2 adenomas; mean, 5). In contrast, 100% of papillary adenomas arising in other conditions had less than 2 adenomas. Most of the adenomas (82%, 31/38) stained strongly for AMACR in a fashion similar to that of PRCC. The 7 AMACR-negative cases all arose in the setting of APKD. In this study of surgical specimens, the high coincidence, multifocality, and histologic and immunohistochemical similarities between papillary adenoma and PRCC suggest that the 2 are strongly associated and may represent a continuum of 1 biologic process. In contrast, adenomas associated with APKD exhibit distinct morphological and immunohistochemical features and, therefore, may have an entirely different pathogenesis.

Osteoblast-specific deletion of Hrpt2/Cdc73 results in high bone mass and increased bone turnover.

Inactivating mutations that lead to loss of heterozygosity within the HRPT2/Cdc73 gene are directly linked to the development of primary hyperparathyroidism, parathyroid adenomas, and ossifying fibromas of the jaw (HPT-JT). The protein product of the Cdc73 gene, parafibromin, is a core member of the polymerase-associated factors (PAF) complex, which coordinates epigenetic modifiers and transcriptional machinery to control gene expression. We conditionally deleted Cdc73 within mesenchymal progenitors or within mature osteoblasts and osteocytes to determine the consequences of parafibromin loss within the mesenchymal lineage. Homozygous deletion of Cdc73 via the Dermo1-Cre driver resulted in embryos which lacked mesenchymal organ development of internal organs, including the heart and fetal liver. Immunohistochemical detection of cleaved caspase-3 revealed extensive apoptosis within the progenitor pools of developing organs. Unexpectedly, when Cdc73 was homozygously deleted within mature osteoblasts and osteocytes (via the Ocn-Cre driver), the mice had a normal life span but increased cortical and trabecular bone. OCN-Cre;Cdc73flox/flox bones displayed large cortical pores actively undergoing bone remodeling. Additionally the cortical bone of OCN-Cre;Cdc73flox/flox femurs contained osteocytes with marked amounts of cytoplasmic RNA and a high rate of apoptosis. Transcriptional analysis via RNA-seq within OCN-Cre;Cdc73flox/flox osteoblasts showed that loss of Cdc73 led to a derepression of osteoblast-specific genes, specifically those for collagen and other bone matrix proteins. These results aid in our understanding of the role parafibromin plays within transcriptional regulation, terminal differentiation, and bone homeostasis.

Aristolochic acids and their derivatives are widely implicated in liver cancers in Taiwan and throughout Asia.

Many traditional pharmacopeias include Aristolochia and related plants, which contain nephrotoxins and mutagens in the form of aristolochic acids and similar compounds (collectively, AA). AA is implicated in multiple cancer types, sometimes with very high mutational burdens, especially in upper tract urothelial cancers (UTUCs). AA-associated kidney failure and UTUCs are prevalent in Taiwan, but AA's role in hepatocellular carcinomas (HCCs) there remains unexplored. Therefore, we sequenced the whole exomes of 98 HCCs from two hospitals in Taiwan and found that 78% showed the distinctive mutational signature of AA exposure, accounting for most of the nonsilent mutations in known cancer driver genes. We then searched for the AA signature in 1400 HCCs from diverse geographic regions. Consistent with exposure through known herbal medicines, 47% of Chinese HCCs showed the signature, albeit with lower mutation loads than in Taiwan. In addition, 29% of HCCs from Southeast Asia showed the signature. The AA signature was also detected in 13 and 2.7% of HCCs from Korea and Japan as well as in 4.8 and 1.7% of HCCs from North America and Europe, respectively, excluding one U.S. hospital where 22% of 87 "Asian" HCCs had the signature. Thus, AA exposure is geographically widespread. Asia, especially Taiwan, appears to be much more extensively affected, which is consistent with other evidence of patterns of AA exposure. We propose that additional measures aimed at primary prevention through avoidance of AA exposure and investigation of possible approaches to secondary prevention are warranted.