Two new cases of papillary renal cell carcinoma with t(X;1)(p11;q21) in females

Clinicopathological Findings on 28 Cases with XP11.2 Renal Cell Carcinoma

Xp11.2 translocation carcinoma is a distinct subtype of renal cell carcinoma characterized by translocations involving the TFE3 gene. Our study included the morphological, immunohistochemical and clinicopathological examination of 28 Xp11.2 RCCs. The immunophenotype has been assessed by using CA9, CK7, CD10, AMACR, MelanA, HMB45, Cathepsin K and TFE3 immunostainings. The diagnosis was confirmed by TFE3 break-apart FISH in 25 cases. The ages of 13 male and 15 female patients, without underlying renal disease or having undergone chemotherapy ranged from 8 to 72. The mean size of the tumors was 78.5 mm. Forty-three percent of patients were diagnosed in the pT3/pT4 stage with distant metastasis in 6 cases. Histological appearance was branching-papillary composed of clear cells with voluminous cytoplasm in 13 and variable in 15 cases, including one tumor with anaplastic carcinoma and another with rhabdoid morphology. Three tumors were labeled with CA9, while CK7 was negative in all cases. Diffuse CD10 reaction was observed in 17 tumors and diffuse AMACR positivity was described in 14 tumors. The expression of melanocytic markers and Cathepsin K were seen only in 7 and 6 cases, respectively. TFE3 immunohistochemistry displayed a positive reaction in 26/28 samples. TFE3 rearrangement was detected in all the analyzed cases (25/25), including one with the loss of the entire labeled break-point region. The follow-up time ranged from 2 to 300 months, with 7 cancer-related deaths. In summary, Xp11.2 carcinoma is an uncommon form of renal cell carcinoma with a variable histomorphology and rather aggressive clinical course.

Papillary renal cell carcinoma: A review of the current therapeutic landscape

Renal cell carcinoma (RCC) is the most common cancer of the kidney and accounts for 2-3% of all adult malignancies. Clear cell carcinoma represents the most common histologic subtype, while papillary Renal Cell Carcinoma (pRCC) accounts for 10-20% of all renal cell cancers. While the inactivation of VHL gene can be found in the majority of clear cell carcinomas, different molecular mechanisms are involved into pRCC biology. Mutations in the MET oncogene are an essential step into the pathogenesis of hereditary pRCC forms, but they can be found only in a small rate of sporadic cases. Several agents, including anti-VEGF drugs and mTOR inhibitors, are possible options in the treatment of advanced and metastatic pRCC, following the demonstration of efficacy obtained in clinical trials including all RCC histologic subtypes. However, data specifically obtained in the subgroup of patients affected by pRCC are limited and not conclusive. Several ongoing trials are evaluating the efficacy of targeted therapy in papillary form. However, more rationale approaches based on molecular studies would help improving the outcome of these patients. Among others, MET inhibitors and targeted immunotherapy are promising new strategies for hereditary and sporadic disease. This review summarizes current knowledge on pRCC tumorigenesis and discusses recent and ongoing clinical trials with new therapeutic agents.

Clinical heterogeneity of Xp11 translocation renal cell carcinoma: impact of fusion subtype, age, and stage

Xp11 translocation renal cell carcinomas harbor chromosome translocations involving the Xp11 breakpoint, resulting in gene fusions involving the TFE3 gene. The most common subtypes are the ASPSCR1-TFE3 renal cell carcinomas resulting from t(X;17)(p11;q25) translocation, and the PRCC-TFE3 renal cell carcinomas, resulting from t(X;1)(p11;q21) translocation. A formal clinical comparison of these two subtypes of Xp11 translocation renal cell carcinomas has not been performed. We report one new genetically confirmed Xp11 translocation renal cell carcinoma of each type. We also reviewed the literature for all published cases of ASPSCR1-TFE3 and PRCC-TFE3 renal cell carcinomas and contacted all corresponding authors to obtain or update the published follow-up information. Study of two new, unpublished cases, and review of the literature revealed that 8/8 patients who presented with distant metastasis had ASPSCR1-TFE3 renal cell carcinomas, and all but one of these patients either died of disease or had progressive disease. Regional lymph nodes were involved by metastasis in 24 of the 32 ASPSCR1-TFE3 cases in which nodes were resected, compared with 5 of 14 PRCC-TFE3 cases (P=0.02).; however, 11 of 13 evaluable patients with ASPSCR1-TFE3 renal cell carcinomas who presented with N1M0 disease remained disease free. Two PRCC-TFE3 renal cell carcinomas recurred late (at 20 and 30 years, respectively). In multivariate analysis, only older age or advanced stage at presentation (not fusion subtype) predicted death. In conclusion, ASPSCR1-TFE3 renal cell carcinomas are more likely to present at advanced stage (particularly node-positive disease) than are PRCC-TFE3 renal cell carcinomas. Although systemic metastases portend a grim prognosis, regional lymph node involvement does not, at least in short-term follow-up. The tendency for PRCC-TFE3 renal cell carcinomas to recur late warrants long-term follow-up.

Molecular cytogenetic analysis for TFE3 rearrangement in Xp11.2 renal cell carcinoma and alveolar soft part sarcoma: validation and clinical experience with 75 cases

Renal cell carcinoma with TFE3 rearrangement at Xp11.2 is a distinct subtype manifesting an indolent clinical course in children, with recent reports suggesting a more aggressive entity in adults. This subtype is morphologically heterogeneous and can be misclassified as clear cell or papillary renal cell carcinoma. TFE3 is also rearranged in alveolar soft part sarcoma. To aid in diagnosis, a break-apart strategy fluorescence in situ hybridization (FISH) probe set specific for TFE3 rearrangement and a reflex dual-color, single-fusion strategy probe set involving the most common TFE3 partner gene, ASPSCR1, were validated on formalin-fixed, paraffin-embedded tissues from nine alveolar soft part sarcoma, two suspected Xp11.2 renal cell carcinoma, and nine tumors in the differential diagnosis. The impact of tissue cut artifact was reduced through inclusion of a chromosome X centromere control probe. Analysis of the UOK-109 renal carcinoma cell line confirmed the break-apart TFE3 probe set can distinguish the subtle TFE3/NONO fusion-associated inversion of chromosome X. Subsequent extensive clinical experience was gained through analysis of 75 cases with an indication of Xp11.2 renal cell carcinoma (n=54), alveolar soft part sarcoma (n=13), perivascular epithelioid cell neoplasms (n=2), chordoma (n=1), or unspecified (n=5). We observed balanced and unbalanced chromosome X;17 translocations in both Xp11.2 renal cell carcinoma and alveolar soft part sarcoma, supporting a preference but not a necessity for the translocation to be balanced in the carcinoma and unbalanced in the sarcoma. We further demonstrate the unbalanced separation is atypical, with TFE3/ASPSCR1 fusion and loss of the derivative X chromosome but also an unanticipated normal X chromosome gain in both males and females. Other diverse sex chromosome copy number combinations were observed. Our TFE3 FISH assay is a useful adjunct to morphologic analysis of such challenging cases and will be applicable to assess the growing spectrum of TFE3-rearranged tumors.

Renal translocation carcinomas: clinicopathologic, immunohistochemical, and gene expression profiling analysis of 31 cases with a review of the literature

We report clinicopathologic features of a large series of renal translocation carcinomas from a multicentric study. Diagnosis was performed by cytogenetic examination of fresh material and/or by immunochemistry with antibodies directed against the C-terminal part of transcription factor E3 (TFE3) and native transcription factor EB (TFEB) proteins. Clinical data, follow-up, and histologic features were assessed. Antibodies against CK7, CD10, vimentin, epithelial membrane antigen, AE1-AE3, E-cadherin, alpha-methylacyl-coenzyme A racemase, melan A, and HMB45 were tested on tissue microarrays. Whole-genome microarray expression profiling was performed on 4 tumors. Twenty-nine cases were diagnosed as TFE3 and 2 as TFEB renal translocation carcinomas, including 13 males and 18 females, mean age 24.6 years. Two patients had a previous history of chemotherapy and 1 had a history of renal failure. Mean size of the tumor was 6.9 cm. Thirteen cases were > or = pT3 stage. Twelve cases were N+ or M+. Mean follow-up was 29.5 months. Three patients presented metastases and 5 have died. Mixed papillary and nested patterns with clear and/or eosinophilic cells represented the most consistent histologic appearance, with common foci of calcifications regardless of the type of translocation. Using a 30 mn incubation at room temperature, TFE3 immunostainings were positive in only 82% of our TFE3 translocation carcinomas. Both TFE3 and TFEB renal translocation carcinomas expressed CD10 and alpha-methylacyl-coenzyme A racemase in all cases. An expression of E-cadherin was observed in two-third of cases. Cytokeratins were expressed in less than one-third of cases. Melanocytic markers were expressed at least weakly in all cases except two. Unsupervised clustering on the basis of the gene expression profiling indicated a distinct subgroup of tumors. TRIM 63 glutathione S-transferase A1 and alanyl aminopeptidase are the main differentially expressed genes for this group of tumors. Our results suggest that these differentially expressed genes may serve as novel diagnostic or prognostic markers.

Translocation renal cell carcinoma: lack of negative impact due to lymph node spread

BACKGROUND

Pediatric renal cell carcinoma (RCC) is clinically distinct from adult RCC. Characterization of the unique biological and clinical features of pediatric RCC are required.

METHODS

A retrospective review and biological analysis of all RCC cases presenting to Cincinnati Children's Hospital Medical Center (CCHMC) in the last 30 years was undertaken. Cases were classified according to the recent World Heath Organization morphologic classification and according to TFE3/TFEB status. A literature review of pediatric TFE+ cases was performed.

RESULTS

Eleven cases of RCC with clinical data were identified in our institutional review as follows: 6 clear cell, 2 papillary, 2 translocation, and 1 sarcomatoid. Upon reanalysis, 1 papillary and 1 sarcomatoid were confirmed, 1 case was "unclassified", and 8 of 11 (72.7%) had features consistent with translocation morphology. Of these 8, all demonstrated immunoreactivity for TFE3 (7 patients) or TFEB (1 patient) protein. In 3 cases, cytogenetics was available, each demonstrating confirmatory MiTF/TFE translocations. Seven of 8 TFE+ RCC patients presented with TNM Stage III/IV disease. Literature analysis confirmed a significant increase in advanced stage presentation in pediatric TFE+ RCC compared with TFE- RCC. Fourteen of fifteen (93.3%) patients with TFE+ stage III/IV RCC due to lymph node spread (N+ M(0)) remain disease free with a median and mean follow-up of 4.4 and 6.3 years, respectively (range, 0.3-15.5).

CONCLUSIONS

Translocation morphology RCC is the predominant form of pediatric RCC, associated with an advanced stage at presentation. Patients with TFE+ N+ M(0) RCC maintain a favorable short-term prognosis after surgery alone. Young RCC patients should be screened for translocation morphology, and the screening information should be considered when debating adjuvant therapy.

Molecular mechanisms underlying the MiT translocation subgroup of renal cell carcinomas

Renal cell carcinomas (RCCs) represent a heterogeneous group of neoplasms, which differ in histological, pathologic and clinical characteristics. The tumors originate from different locations within the nephron and are accompanied by different recurrent (cyto)genetic anomalies. Recently, a novel subgroup of RCCs has been defined, i.e., the MiT translocation subgroup of RCCs. These tumors originate from the proximal tubule of the nephron, exhibit pleomorphic histological features including clear cell morphologies and papillary structures, and are found predominantly in children and young adults. In addition, these tumors are characterized by the occurrence of recurrent chromosomal translocations, which result in disruption and fusion of either the TFE3 or TFEB genes, both members of the MiT family of basic helix-loop-helix/leucine-zipper transcription factor genes. Hence the name MiT translocation subgroup of RCCs. In this review several features of this RCC subgroup will be discussed, including the molecular mechanisms that may underlie their development.

Xp11 translocation renal cell carcinoma: delayed but massive and lethal metastases of a chemotherapy-associated secondary malignancy

A recently described subtype of renal cell carcinoma (RCC) bearing chromosome translocations involving a breakpoint at Xp11 and resulting in gene fusions involving the TFE3 transcription factor gene often presents in the pediatric population. Herein we describe an Xp11 translocation RCC associated with prior exposure to cytotoxic chemotherapy, which massively recurred and led to the patient's death 17 years later. This case highlights the association of these RCCs with prior chemotherapy exposure, the tendency of these RCCs to recur late, their unusual pattern of metastases, and the utility of TFE3 immunohistochemistry in confirming their diagnosis in archival pathologic specimens.

Cytogenetic findings in pediatric renal cell carcinoma

Adenocarcinomas of the kidney are rare childhood tumors. Only 30 cases with chromosomal abnormalities have been reported, and neither their karyotypic characteristics nor the molecular mechanisms behind their pathogenesis are clear, except for a special group of papillary tumors characterized by X-chromosome abnormalities. We have cytogenetically analyzed short-term cultured cells from two pediatric renal carcinomas, one papillary, and one chromophobe renal cell carcinoma, revealing the following karyotypes: 58-60,XX,-X,-1,+7,-8,-9,-11,-14,-15,+17,-18,-19,-21,-22 and 36,X,-X,-1,-2,-5,-6,-9,-10,-13,-17,-21/37,idem,+r/36,idem,-14,+1-2r, respectively. The findings indicate that subsets of pediatric renal cell carcinoma show karyotypes that are similar to their adult counterparts.

Adult Papillary Renal Tumor With Oncocytic Cells

We report a series of 10 oncocytic renal papillary tumors, with the aim of determining their clinicopathologic features. All patients were male (median age, 71 years), treated by radical nephrectomy and free of recurrence or metastasis (median follow-up, 62 months). Tumors (median size, 3.3 cm) were intrarenal and well limited, with no extrarenal extension. They consisted of thin, nonfibrotic papillae lined by a single layer of oncocytic cells, with finely granular eosinophilic cytoplasm and round regular nucleus exhibiting central nucleolus (Fuhrman grade II, except for one grade III). Foci of necrosis were present in most cases. All tumors were immunoreactive for alpha-methylacyl-coenzyme A racemase, vimentin, and CD10; 4 expressed renal cell carcinoma antigen and 3 cytokeratin 7. There were a low number of cytogenetic changes in the 5 analyzed cases (median, 4; range, 1-7), with no trisomy 7 or 17. Papillary architecture, necrosis, and immunohistochemical profiles argued against the diagnosis of oncocytoma and suggested our cases to be part of the papillary renal cell carcinoma group. However, the cases were atypical for type 1 papillary carcinoma (due to oncocytic cells and absence of trisomy 17) and for type 2 (due to a good outcome). These results suggest that adult papillary renal tumors with oncocytic cells might be a distinct variant in the papillary renal cell carcinoma group.

[Tumors of the kidneys: new entities]

Since 1998 new entities have surfaced in renal tumor classification and have been included in the WHO 2004 classification. In this article, we will discuss the following entities: multilocular clear cell renal carcinoma, Xp11 translocation carcinoma, low grade mucinous tubular carcinoma, epithelioid angiomyolipoma, benign mixed epithelial and stromal tumor. We will investigate new concepts of hybrid oncocytoma and chromophobe renal cell carcinoma and the syndrome of Birt-Hogg-Dube which is associated to kidney tumors. At least, we will touch on new elements in the Bellini carcinoma definition.

Translocation carcinomas of the kidney

A significant proportion of RCCs of children and young adults bear specific chromosome translocations that result in gene fusions that involve members of the MiTF/TFE transcription factor family. These include the Xp11-translocation carcinomas, which bear TFE3 gene fusions, and the renal carcinomas with the t(6;11)(p21;q12), which bear an Alpha-TFEB gene fusion. Both types of translocation result in overexpression of the fusion gene products, such that nuclear labeling for TFE3 or TFEB by immunohistochemistry is a sensitive and specific marker of these respective tumor types. The clinical behavior of these neoplasms relative to conventional, adult-type renal carcinomas remains to be determined, and will be an important area of future investigation.

Pediatric renal carcinoma associated with Xp11.2 translocations/TFE3 gene fusions and clinicopathologic associations

Renal cell carcinomas (RCCs) are rare in children and studies of their subtypes and clinicopathologic associations are limited to small series. We identified 8 patients with RCC treated at our institution between 1981 and 2003, reviewed their clinicopathologic features, cytogenetics findings, and evaluated the status of TFE3 expression by immunohistochemistry and numerical chromosomal alterations by interphase fluorescent in situ hybridization on paraffin-embedded tissue. These 8 patients (5 female and 3 male) had diploidy, and 5 had morphologic features compatible with the recently described RCC associated with Xp11.2 translocations/TFE3 gene fusions and demonstrated nuclear labeling for TFE3 protein by immunohistochemistry. The translocation was confirmed in 2 of these 5 patients by conventional cytogenetics. One case was a high-grade nonpapillary RCC and the other was compatible with type 2 papillary RCC. Four patients showed at least 1 chromosomal gain including trisomy 7 and/or trisomy 17. None of the tumors from male patients showed evidence of loss of the Y chromosome, but 2 patients showed numerical abnormalities of X chromosome +add(X). Two patients had sickle cell disease, and 1 of these also had stage IV-S neuroblastoma. This study suggests that many cases of RCC in children reported under the terms "papillary" and "clear cell" likely represent Xp11.2 translocation/TFE3 gene fusion-associated RCC. It also emphasizes the unusual associations of RCC with neuroblastoma and sickle cell hemoglobinopathy, which need further study.

Recent advances in pediatric renal neoplasia

Over the past 6 years, molecular genetic studies have significantly advanced our understanding of pediatric renal neoplasms. The cellular variant of congenital mesoblastic nephroma (but not the classic variant) has been shown to bear the same t(12;15)(p13;q25) and ETV6-NTRK3 gene fusion as infantile fibrosarcoma, a tumor with which it shares morphologic and clinical features. Rhabdoid tumor of the kidney is characterized by deletion of the hSNF5/INI1 gene, which links it to other rhabdoid tumors of infancy that arise in the soft tissue and brain. Primary renal synovial sarcomas and renal primitive neuroectodermal tumors have become accepted entities, and likely comprise a subset of what had previously been termed "adult Wilms tumor." Renal carcinomas associated with Xp11.2 translocations that result in fusions involving the TFE3 transcription factor gene have been delineated, including a distinctive neoplasm that shares the identical gene fusion as alveolar soft part sarcoma. Most recently, a distinctive type of renal neoplasm with a t(6;11)(p21;q12) has been described, and the cloning of the resulting gene fusion links it to the Xp11 translocation carcinomas. Together, these last two translocation-associated tumors represent a significant proportion of pediatric renal cell carcinomas. This review highlights each of these recent advances.

Five new cases of juvenile renal cell carcinoma with translocations involving Xp11.2: a cytogenetic and morphologic study

Two cases of renal cell carcinoma (RCC) carrying a t(X;1)(p11.2;q21) in a 12-year-old boy and a 14 year-old girl, two cases with a t(X;1)(p11.2;p34) in a 9-year-old boy and a 31-year-old woman, and one case with a t(X;17)(p11.2;q25) in a 15-year-old boy are reported. Two are likely papillary RCC, with clear or slightly eosinophilic cells, and two to a clear cell RCC; one shows a mixture of papillary and clear cell RCC architecture. Renal cell carcinomas with translocations involving Xp11.2 form a specific entity characterized by subtle pathologic features and younger age of occurrence, especially for those with the t(X;17).

Papillary renal cell carcinoma. Prognostic value of morphological subtypes in a clinicopathologic study of 43 cases

A series of 43 papillary renal cell carcinomas (PRCCs) were analyzed to investigate the prognostic value of the morphological subtyping (type 1/type 2) proposed by Delahunt and Eble. Twenty-six cases were type 1 (small cuboid cells arranged in single or double layers), 13 cases were type 2 (voluminous eosinophilic cells with irregular pseudostratification pattern), and four cases with oncocytic cells (large eosinophilic cells with round regular nuclei) were distinct from type 2 and grouped apart. All type-1 and oncocytoid-type PRCCs were staged pT1 or pT2, whereas 8/13 type-2 PRCCs were staged pT3 or pT4. Follow-up information (range, 3-113 months; median, 43 months) showed 12 deaths from disease: 2 in the type-1 group,10 in the type-2 group, 0 in the oncocytoid-type group. The Kaplan-Meier analysis showed that pejorative outcome was associated (P<0.001) with high stage (pT3/pT4), high nuclear grade (3/4), morphological type 2, absence of foam cells, and abundant fibrous stroma. The multivariate analysis showed that stage and morphological type were independently associated with survival (P<0.05). These results support the clinical interest of morphological subtyping of PRCCs in the prognosis evaluation of the patients. The four oncocytoid-type PRCCs had a favorable outcome, but additional data are required to evaluate this type of neoplasm.

PRCC-TFE3 renal carcinomas: morphologic, immunohistochemical, ultrastructural, and molecular analysis of an entity associated with the t(X;1)(p11.2;q21)

The reappraisal of genetically defined subsets of renal tumors can help to highlight the key pathologic features of specific neoplastic entities. We report the morphologic, immunophenotypic, ultrastructural, and molecular features of 11 renal carcinomas bearing a t(X;1)(p11.2;q21) and/or the resulting PRCC-TFE3 gene fusion. The male/female ratio was 4:7. Ten patients were in the age range of 9-29 years and one was 64 years old (mean 21.3 years, median 15 years). The predominant histologic pattern was nested, with islands of tumor cells compartmentalized by thin-walled capillary vasculature. Minor variations on this pattern yielded solid, acinar, alveolar, and tubular architecture. Papillary architecture was seen in nine cases, usually as a minor component. Neoplastic cells were typically characterized by irregularly shaped nuclei with vesicular chromatin and small nucleoli not visible with a 10x objective, and cytoplasm that ranged from clear to densely granular and eosinophilic. Mitoses were extremely rare; 5 were found in 900 high power fields examined from the 11 neoplasms. The most distinctive immunohistochemical feature of these neoplasms was moderate to intense nuclear labeling for TFE3 protein. These tumors were also consistently immunoreactive for the RCC antigen (10 of 11) and CD10 (9 of 9), whereas cytokeratin and epithelial membrane antigen were negative in four cases and were positive focally in the others. Ultrastructurally, all of the six neoplasms examined showed features consistent with conventional-type (clear cell) renal carcinoma, although two demonstrated distinctive intracisternal microtubules. Both tumors tested contained PRCC-TFE3 fusion transcripts. The differential diagnosis includes conventional-type papillary renal cell carcinoma, conventional-type (clear cell) renal carcinoma, and the ASPL-TFE3 renal carcinomas associated with the t(X;17)(p11.2;q25), with the latter two being morphologically the most similar to the t(X;1) renal carcinomas. Aside from their distinctive clinicopathologic features described here, there is experimental evidence suggesting that these tumors may show differential sensitivity to certain chemotherapeutic agents.

Renal cancer: cytogenetic and molecular genetic aspects

To date, much progress has been made in the fields of cytogenetics and molecular genetics of renal tumors. The previous and recent findings have delineated the characteristics of the various tumors, particularly the cytogenetic and molecular differences that exist between papillary and nonpapillary clear cell renal cell carcinomas (RCCs). At the same time, new cytogenetic subtypes have emerged [e.g., t(X;1)] in subtypes of RCC, while in others (e.g., Wilms tumors) several new cytogenetic abnormalities and consequent molecular involvement have been found. In addition to Wilms tumor, papillary RCC, and clear-cell RCC, cytogenetic and fluorescence in situ hybridization analyses have been performed on several other tumors of the kidney, including chromophobic carcinoma, metanephric adenoma, collecting duct carcinoma, transitional cell carcinoma, congenital mesoblastic nephroma, and malignant rhabdoid tumors of the kidney. This review is therefore intended to present a concise update on the cytogenetic and molecular data on renal tumors, focusing mainly on the clinical usefulness of the findings reported in the literature.

Unique patterns of allelic imbalance distinguish type 1 from type 2 sporadic papillary renal cell carcinoma

The molecular genetic correlates of a recently proposed subclassification of papillary renal cell carcinoma (PRCC) that designates tumors as type 1 and type 2 based on histological features have not yet been established. Alterations of known genes in PRCC include missense mutations in the MET oncogene (7q31) and rare translocations fusing TFE3 at Xp11.2 with a variety of other loci. Previous cytogenetic and allelic loss studies of PRCC cases revealed gain of chromosome 3q, 7, 8, 12q, 16, 17, and 20q, and loss of 1p, 6q, 9p, 11p, 13q, 14q, 18, 21q, X, and Y. We analyzed a series of sporadic type 1 and type 2 PRCC cases for MET mutations, TFE3 rearrangements, and allelic imbalance (AI) on 3p, 6, 7q, 9p, 11, 13q, 14q, 17q, 18, 20q, and 21q and compared selected results with a series of conventional renal cell carcinomas. A somatic mutation M1149T was identified in MET exon 17 in 1 of 35 PRCC cases whereas TFE3 rearrangements were not detected in 22 PRCC cases examined. Significant differences in AI frequency between PRCCs and conventional renal cell carcinoma cases were seen on 3p (37.5% versus 77.8%, P = 0.01), 7q (42.9% versus 5.6%, P = 0.01), and 17q (54.5% versus 20.0%, P = 0.03). Significant differences in AI frequency between type 1 and type 2 PRCCs were noted on 17q (78.6% versus 12.5%, P = 0.006) and 9p (0% versus 37.5%, P = 0.02). Additional analyses suggested that the relationship between 17q AI and PRCC type may be independent of histological grade and stage. Our findings identify genetic differences between the recently proposed type 1 and type 2 PRCCs, and support the premise that these subtypes arise from distinct genetic pathways.

Impairment of MAD2B-PRCC interaction in mitotic checkpoint defective t(X;1)-positive renal cell carcinomas

The papillary renal cell carcinoma (RCC)-associated (X;1)(p11;q21) translocation fuses the genes PRCC and TFE3 and leads to cancer by an unknown molecular mechanism. We here demonstrate that the mitotic checkpoint protein MAD2B interacts with PRCC. The PRCCTFE3 fusion protein retains the MAD2B interaction domain, but this interaction is impaired. In addition, we show that two t(X;1)-positive RCC tumor cell lines are defective in their mitotic checkpoint. Transfection of PRCCTFE3, but not the reciprocal product TFE3PRCC, disrupts the mitotic checkpoint in human embryonic kidney cells. Our results suggest a dominant-negative effect of the PRCCTFE3 fusion gene leading to a mitotic checkpoint defect as an early event in papillary RCCs.

Transformation capacities of the papillary renal cell carcinoma-associated PRCCTFE3 and TFE3PRCC fusion genes

A recurrent chromosomal abnormality associated with a subset of papillary renal cell carcinomas is t(X;1)(p11;q21). This translocation leads to the formation of two fusion genes, TFE3PRCC and the reciprocal product PRCCTFE3. Both fusion genes are expressed in t(X;1)-positive renal cell carcinomas and contain major parts of the coding regions of the parental transcription factor PRCC and TFE3 genes, respectively. To find out whether these fusion genes possess transforming capacity, we transfected NIH3T3 and rat-1 cells with the fusion products, either separately or combined. When using soft agar assays, we observed colony formation in all cases. NIH3T3 cells transfected with PRCCTFE3 or PRCCTFE3 together with TFE3PRCC yielded the highest colony forming capacities. Examination of other characteristics associated with malignant transformation, i.e., growth under low-serum conditions and formation of tumors in athymic nude mice, revealed that cells transfected with PRCCTFE3 exhibited all these transformation-associated characteristics. Upon transfection of the fusion products into conditionally immortalized kidney cells, derived from the proximal tubules of an H-2Kb-tsA58 transgenic mouse, and consecutive incubation under non-permissive conditions, growth arrest was observed, followed by differentiation except for those cells transfected with PRCCTFE3. Therefore, we conclude that PRCCTFE3 may be the t(X;1)-associated fusion product that is most critical for the development of papillary renal cell carcinomas.

Molecular cytogenetics of t(X;1)(p11.2;q21) with complex rearrangements in a renal cell carcinoma

We report a new case of renal cell carcinoma with the translocation (X;1)(p11;q21) and complex structural rearrangements in a female patient of 64 years of age. We analyzed abnormalities using FISH to identify chromosomal rearrangements, and wonder whether the translocation (X;1) could represent a particular subentity in renal cell carcinoma with distinct histologic features.

Translocation (X;1) associated with a nonpapillary carcinoma in a young woman: a new definition for an Xp11.2 RCC subtype

We report a translocation (X;1)(p11.2;q21) associated with a nontubulopapillary renal cell carcinoma in a 23-year-old woman. To our knowledge this the first report of such an association. A review of the previously published cases of renal cell carcinoma with t(X;1) and its cytogenetic variants with Xp11.2 anomalies is included. The role of this karyotype abnormality as a clinical marker is discussed. The Xp11.2 abnormality could be a primary abnormality characterizing a particular type of RCC appearing in children and young adults of both sexes and in which the histological aspect is not specific.