Laminin is a major component of the extracellular matrix. The laminin gamma1 chain is the least variant component of the laminin heterotrimeric assembly. The laminin gamma1 chain gene (LAMC1) expression is induced by several factors, including transforming growth factor-beta (TGF-beta). LAMC1 promoter contains a highly conserved transcriptional element, bcn-1. We screened cDNA libraries with the yeast one-hybrid system to identify transcriptional factors that are recognized by the bcn-1 motif. Using this strategy we isolated the basic helix-loop-helix/leucine zipper (bHLHzip) E-box-binding transcription factor, TFE3. Until now, the E-box was the only element known to recruit the bHLHzip transcription factors. Although the bcn-1 element only remotely resembles the E-box sequence, we show that TFE3 binds and activates the bcn-1 element. TFE3 cooperates with Smad proteins in the activation of the LAMC1 promoter in cells, an effect that is critically dependent not only on the bcn-1 element but also on one of the Smad-binding elements (SBE). The cooperative induction of the LAMC1 promoter and the endogenous LAMC1 gene by TFE3 and Smad3 is augmented by the TGF-beta signaling pathway. Thus, the bcn-1 is a novel TFE3-dependent TGF-beta target element that regulates LAMC1 gene expression.

The diagnosis of Xp11.2 translocation renal cell carcinoma (tRCC), which relies on morphology and immunohistochemistry (IHC), is often either missed in the diagnosis or misdiagnosed. To improve the accuracy of diagnosis of Xp11.2 tRCC and ASPL-TFE3 renal cell carcinoma (RCC), we investigated newly designed fluorescence in situ hybridization (FISH) probes (diagnostic accuracy study).Based on the genetic characteristics of Xp11.2 tRCC and the ASPL-TFE3 RCC, a new break-apart TFE3 FISH probe and an ASPL-TFE3 dual-fusion FISH probe were designed and applied to 65 patients with RCC who were <45 years old or showed suspicious microscopic features of Xp11.2 tRCC in our hospital. To test the accuracy of the probes, we further performed reverse transcriptase-polymerase chain reaction (PCR) on 8 cases for which frozen tissues were available.Among the 65 cases diagnosed with RCC, TFE3 IHC was positive in 24 cases. Twenty-two cases were confirmed as Xp11.2 tRCC by break-apart TFE3 FISH, and 6 of these cases were further diagnosed as ASPL-TFE3 RCC by ASPL-TFE3 dual-fusion FISH detection. Importantly, reverse transcriptase-PCR showed concordant results with the results of FISH assay in the 8 available frozen cases.The break-apart and ASPL-TFE3 dual-fusion FISH assay can accurately detect the translocation of the TFE3 gene and ASPL-TFE3 fusion gene and can thus serve as a valid complementary method for diagnosing Xp11.2 tRCC and ASPL-TFE3 RCC.

A 57-yr-old woman presented to the National Cancer Institute (NCI) with a history of nephrectomy for a clear cell renal cell carcinoma (RCC), Fuhrman grade 3 of 4 diagnosed 1 yr prior to admission to the NCI. A CT scan done upon admission revealed multiple bilateral lung masses. A CT-guided fine-needle aspiration (FNA) of one of the lung masses revealed a cellular specimen composed primarily of follicular structures surrounding dense hyalinized central cores. The cells in the follicular structures displayed bland nuclei and had granular to vacuolated cytoplasm. Papillary structures were also appreciated. Immunocytochemical studies showed tumor cells that were strongly vimentin and TFE3 positive. Focal staining for AE1/AE3 and CD10 was observed, as was negative staining for EMA. A surgical biopsy specimen reflected the FNA findings and demonstrated a similar immunoprofile. These findings correspond to the recently described Xp11.2 translocation/TFE3 fusion renal cell carcinoma. To our knowledge, this is the first report describing the cytologic features of an Xp11.2 translocation/TFE3 fusion RCC.

The dry (nonneovascular) form of age-related macular degeneration (AMD), a leading cause of blindness in the elderly, has few, if any, treatment options at present. It is characterized by early accumulation of cellular waste products in the retinal pigmented epithelium (RPE); rejuvenating impaired lysosome function in RPE is a well-justified target for treatment. It is now clear that amino acids and vacuolar-type H+ -ATPase (V-ATPase) regulate the mechanistic target of rapamycin, complex 1 (mTORC1) signaling in lysosomes. Here, we provide evidence for the first time that the amino acid transporter SLC36A4/proton-dependent amino acid transporter (PAT4) regulates the amino acid pool in the lysosomes of RPE. In Cryba1 (gene encoding βA3/A1-crystallin) KO (knockout) mice, where PAT4 and amino acid levels are increased in the RPE, the transcription factors EB (TFEB) and E3 (TFE3) are retained in the cytoplasm, even after 24 h of fasting. Consequently, genes in the coordinated lysosomal expression and regulation (CLEAR) network are not activated, and lysosomal function remains low. As these mice age, expression of RPE65 and lecithin retinol acyltransferase (LRAT), two vital visual cycle proteins, decreases in the RPE. A defective visual cycle would possibly slow down the regeneration of new photoreceptor outer segments (POS). Further, photoreceptor degeneration also becomes obvious during aging, reminiscent of human dry AMD disease. Electron microscopy shows basal laminar deposits in Bruch's membrane, a hallmark of development of AMD. For dry AMD patients, targeting PAT4/V-ATPase in the lysosomes of RPE cells may be an effective means of preventing or delaying disease progression.

OBJECTIVE

To evaluate the feasibility and efficacy of tumor enucleation (TE) for patients with small renal cell carcinoma (RCC) associated with Xp11.2 translocation/TFE3 gene fusion (Xp11.2 RCC) by analyzing the pseudocapsule characteristics of Xp11.2 RCCs comparing with that of clear cell renal cell carcinoma (ccRCC).

METHODS

From June 2007 to February 2014, 22 patients with Xp11.2 RCC who were diagnosed by fluorescence in-situ hybridization polyclonal (FISH) assay and 32 patients with ccRCC treated in our institution were comparatively studied. 12 patients with ccRCC underwent radical nephrectomy (RN) and 20 received TE. Among 22 patients with Xp11.2 RCC, 19 were treated by RN and 3 by TE (1 by radiofrequency ablation assisted TE). Pseudocapsule and other clinicopathological characteristics of the two subtypes of RCC were compared. Survival of patients treated with different surgical methods was evaluated and compared.

RESULTS

Pseudocapsule incidence of Xp11.2 RCC (14/22, 63.6%) was lower than that of ccRCC (32/32, 100%, P<0.001). However, pseudocapsule integrity rate of Xp11.2 RCC (10/14, 71.4%) was comparable with that of ccRCC (23/32, 71.9%, P=1.000). The 5-year overall survival of patients with ccRCC treated with RN and TE was 86% and 81%, respectively (P=0.845). Three patients with small Xp11.2 RCC performed well after TE.

CONCLUSIONS

Over half Xp11.2 RCC had pseudocapsules, whose integrity rate was comparable to that of ccRCC. Treatment effectives of TE and RN were comparable in ccRCC. A preliminary attempt to treat small Xp11.2 RCC with intact pseudocapsule by using TE produced a favorable treatment outcome.

Renal cell carcinoma (RCC) is a rare tumor in the pediatric population. Recently, a phenotypically and genetically distinct kidney carcinoma, mainly prevalent in children and associated with an Xp11.2 translocation or TFE3 gene fusion, has been described. It has been advanced that in this subtype of RCC, there is an accumulation of cyclin D1, cyclin D3, and p21 ((wafl/cip1)). The aim of the present study was to figure out in two pediatric RCC recently diagnosed in our department (one clear cell-type RCC and one TFE3-positive RCC) whether those features are indeed specific of the latter tumor or occur in pediatric RCC irrespective of the tumor type. The following immunostains were performed in both cases: Ki67, p16(ink4a), p21 ((wafl/cip1)), p27(kip1), p53, p63, mdm2, cyclin D1, cyclin D3, TFE3, CD10, vimentin, E-cadherin, and RCC-antigen. We observed in the TFE3-positive carcinoma an intense immunoreaction for p21 ((wafl/cip1)), cyclin D1, and cyclin D3, without expression for p53, p16, p27(kip1), and mdm2, whereas the immunoexpression profile observed in the classic RCC was similar to that of clear cell, adult-type RCC. Our study confirms that TFE3-positive RCC exhibits a deregulation of the cell cycle apparently unrelated to the young age of the patients.

Xp11.2 translocation renal cell carcinoma (RCC) is rare and predominantly found in children and young adults. Because of the property of overexpressed transcription factor E3 (TFE3) fusion protein, immunohistochemical (IHC) staining with TFE3 antibody makes an excellent diagnostic tool. This study analyzed preliminary experiences of eight Xp11.2 translocation RCCs in our institution between 2007 and 2012. In four males and four females with a mean age of 28.4 years. Xp11.2 translocation RCCs were diagnosed. TFE3 IHC stain was positive in all tumor specimens. As the initial presentation, four patients suffered from abdominal pain, three cases had gross hematuria, and one case had hemoptysis caused by existing lung metastasis. The tumor was located in the right kidney (75%) with mean diameter of 5.85 ± 2.64 cm. Three cases (38%, 3/8) presented with lymph node metastasis at the time of diagnosis. In five cases (63%, 5/8), the initial diagnosis was Stage III and IV. Treatment included open surgery (one partial nephrectomy and five radical nephrectomies), cryoablation, immunotherapy, and target therapy. The mean follow-up time was 32 months. One patient died after 23.4 months of follow-up. The application of TFE3 IHC stain will improve the diagnostic accuracy for detecting XP11.2 translocation renal cell carcinoma. Surgery or cryoablation both had excellent prognosis in early stages. Although the disease is believed to be indolent, an increasingly aggressive clinical course should be kept in mind, especially for children and young adults.

A 36-year-old male was found to have a 7.0 cm left upper pole renal mass on renal ultrasound. Following nephrectomy, the mass was grossly ill-demarcated, friable and red-brown, invading renal parenchyma, hilar fat and the renal vein. Microscopically, the tumor had a nested and papillary architecture. The cells demonstrated abundant clear and eosinophilic cytoplasm and focal intracytoplasmic melanin pigment. Nucleoli were prominent. By immunohistochemistry, the tumor was positive for TFE3; HMB-45 stained approximately 5% of tumor cells corresponding to the histologic melanin pigment, which was confirmed with Fontana-Masson stain with bleach. Immunostains for PAX8, CD10, MiTF, and CAIX were negative; keratins Cam 5.2 and AE1/AE3 were focally positive. Targeted next-generation sequencing revealed an ARID1B-TFE3 gene fusion. Melanotic Xp11 renal cell carcinoma is a rare, pigment containing translocation variant demonstrating overlapping features with melanoma and is usually associated with an SFPQ-TFE3 gene fusion. The patient is alive and without evidence of disease 7 years after his diagnosis. The combination of high grade histopathology, the presence of melanin, absent PAX8, keratin positivity, and relatively indolent clinical behavior with a unique translocation may warrant recognition as a distinct renal cell carcinoma translocation subtype.

A series of thirteen different DNA markers was mapped relative to papillary renal cell carcinoma- and synovial sarcoma-associated translocation breakpoints in Xp11.2 using a panel of tumor-derived somatic cell hybrids in conjunction with Southern blot analysis. Our results indicate that the two translocation breakpoints differ from each other and that the chromosomal break in t(X;1)-positive papillary renal cell carcinoma is located between the markers PFC-TIMP-OATL1-SYP-TFE3 and DXS226-DXS146-DXS255-OATL2-DXS14. In addition, our current breakpoint analysis has resulted in a revision of the regional localization of the proximal Xp marker DXS226.

MITF (microphthalmia-associated transcription factor) encodes a transcription factor with a basic-helix-loop-helix-leucine zipper (bHLH-Zip) motif. Ectopic expression of MITF is found to convert NIH/3T3 fibroblasts into cells with characteristics of melanocytes. MITF transfectants formed foci, which superficially resembled those induced by oncogenes, but did not exhibit malignant phenotypes. Instead, they contained dendritic cells that express melanogenic marker proteins such as tyrosinase and tyrosinase-related protein 1. Such properties were not observed in cells transfected with the closely related gene, TFE3. These findings indicated that MITF is involved in melanocyte differentiation. Two mutations (C760->>T and C895->>T) in MITF are found to be associated with individuals with Waardenburg syndrome type 2 (WS2). These mutations create stop codons in exon 7 and 8, respectively, and probably result in truncated proteins lacking HLH-Zip or Zip structure. To understand how these MITF mutations cause WS2 in heterozygotes, mutant MITF proteins were generated and used for DNA-binding and luciferase reporter assays. The mutated MITF proteins lose their DNA-binding activity and fail to transactivate the promoter of the tyrosinase gene. However, these mutated proteins do not appear to interfere with the activity of wild-type MITF protein in these assays, indicating that they do not show a dominant-negative effect. These findings suggest that the phenotypes of the two WS2 families are caused by loss-of-function mutations in one of the two MITF alleles, resulting in haploinsufficiency of the MITF protein, the transcription factor necessary for normal melanocyte differentiation.

We have established a cultured cell line named FU-UR-1 from a large retroperitoneal tumor of a 24-year-old Japanese male patient who simultaneously had a small renal cell carcinoma (RCC). Cytogenetic analysis and fluorescence in situ hybridization of the retroperitoneal tumor, and the cell line established from this tumor demonstrated similar karyotypes including add(13)(p11).ish der(13)t(13;17) (p11;q11)t(X;17)(p11;q25)(wcpX+,wcp17+). FU-UR-1 had been propagated continuously for more than 70 passages, and the doubling time was 32 h. Successful heterotransplantation was performed by inoculation of the cultured FU-UR-1 cells into the subcutis of BALB/c nude mice. Reverse transcriptase-polymerase chain reaction (RT-PCR) and sequence analysis demonstrated reciprocal ASPL-TFE3 and TFE3-ASPL fusion transcripts in the retroperitoneal tumor, cultured FU-UR-1 cells and xenografted tumors. In addition, the pathological findings of these samples and the renal tumor resembled each other. These observations suggest that the FU-UR-1 cell line established from the retroperitoneal tumor is an RCC cell line. This well-examined cell line may become a useful system for studying the genetic and biologic characteristics of rare neoplasms with the reciprocal ASPL-TFE3 fusion transcript.

PEComas are mesenchymal tumors composed of histologically and immunohistochemically distinctive perivascular epithelioid cells that are characterized by the coexpression of muscle and melanogenetic markers. This group of lesions includes angiomyolipoma, clear cell "sugar" tumor of the lung and extrapulmonary sites, lymphangioleiomyomatosis, clear cell myomelanocytic tumor of the falciform ligament/ligamentum teres, and rare clear cell tumors of other anatomical sites. In the genitourinary tract, PEComas have been described in the kidney, bladder, prostate, testis, and urethra. Although most PEComas behave as benign tumors, some are potentially malignant, and criteria for malignancy have been suggested for both and renal and extrarenal lesions. Recently, the expression of cathepsin K has been demonstrated in a large number of PEComas and has been proposed as a relatively specific marker to distinguish these proliferations from the majority of human cancers. In addition, a distinctive subset of PEComas harboring TFE3 gene fusions has been reported, giving rise to a possible relationship between them and MiTF/TFE family translocation renal cell carcinomas. The genetic alterations of tuberous sclerosis complex that promote activation of the mTOR pathway have been identified in PEComas. Therapy with mTORC1 inhibitors has been shown to be effective in some cases.

OBJECTIVE. The purpose of this study was to compare the MDCT features of renal cell carcinoma (RCC) associated with Xp11.2 translocation and TFE3 gene fusion (Xp11 RCC) and papillary RCC. MATERIALS AND METHODS. The study included 19 and 39 patients with histologically proven Xp11 RCC and papillary RCC, respectively, who underwent multiphase renal MDCT before nephrectomy. CT findings were compared between Xp11 RCC and papillary RCC using the Student t test and chi-square test. Subgroup analyses of small (< 4 cm) renal masses for these features were performed. RESULTS. Patients with Xp11 RCC were younger (p < 0.001), and it was more prevalent in women (p = 0.007). Tumor size was greater in Xp11 RCC (p = 0.004) and more common in cystic change (p < 0.001). Calcification and unenhanced high-attenuating areas were more frequent in Xp11 RCC (p = 0.001 and 0.026, respectively). Xp11 RCCs were more prevalent in lymph node and distant metastasis (p < 0.001 and p = 0.031, respectively). Xp11 RCC and papillary RCC showed no significant difference in epicenter, margin, and venous and collecting duct invasion (p = 0.403-1.000). Although Xp11 RCC and papillary RCC had lower attenuation than the renal cortex on corticomedullary and early excretory phases (p < 0.001), only Xp11 RCCs were hyperattenuating to the cortex on the unenhanced phase (p < 0.001). Xp11 RCCs had significantly higher attenuation compared with papillary RCCs on all phases (p ≤ 0.02). Regarding small masses, cystic change, calcification, and lymph node metastasis were still more frequent in Xp11 RCCs (p ≤ 0.016). CONCLUSION. Greater size, more cystic change, calcification, high-attenuating areas on unenhanced imaging, and lymph node and distant metastasis were helpful for differentiating Xp11 RCC from papillary RCC.

OBJECTIVE

To investigate the dynamic contrast-enhanced computed tomography (CT) characteristics of renal cell carcinoma associated with Xp11.2 translocation and TFE gene fusion (Xp11.2 RCC) by comparison with clear cell renal cell carcinoma (CCRCC).

METHODS

Dynamic contrast-enhanced CT images and clinical and pathological records of 20 adult patients with Xp11.2 RCC confirmed by TFE3 immunohistochemical and fluorescence in situ hybridization assay were retrospectively analyzed and compared with the findings of 21 contemporary CCRCCs.

RESULTS

Renal cell carcinoma associated with Xp11.2 translocation and TFE gene fusions often occurred in young (30.6 ± 8.6 years) patients with hematuria (9/20). They presented as well-defined (17/20) cystic-solid (17/20) mass with hemorrhage (8/20) and circular/rim calcifications (6/20). Dynamic contrast-enhanced CT showed heterogeneous moderate prolonged enhancement. A tumor-to-cortex attenuation ratio in corticomedullary phase less than 0.62 gave a sensitivity of 90.0% and a specificity of 92.9% in differentiating Xp11.2 RCC from CCRCC (area under the receiver operating characteristic curve = 0.957, P < 0.001).

CONCLUSIONS

Computed tomographic characteristics and dynamic contrast-enhanced patterns and index can differentiate Xp11.2 RCC from CCRCC.

We describe a primary ovarian neoplasm, occurring in a 15-year-old female patient, with morphologic, immunohistochemical, and molecular genetic features identical to those of the very rare tumors of the kidney previously described as "melanotic Xp11 translocation renal cancer." This represents, to the best of our knowledge, the first report of a melanotic Xp11 translocation-associated neoplasm arising outside of the kidney. We discuss the relationship of these rare tumors to neoplasms showing perivascular epithelioid cell differentiation, in particular those showing TFE3 rearrangements.

We report the case of a patient with metastatic renal cell carcinoma with Xp11.2 translocation/transcription factor E3 (TFE3) gene fusion who had presented with sunitinib-induced nephrotic syndrome in association with favorable and durable treatment response. The nephrotic syndrome was managed successfully by discontinuing sunitinib and symptomatic treatment. The 27-year-old female patient presenting with right upper abdominal pain was diagnosed with Xp11.2 translocation renal cell carcinoma on the right side with multiple pulmonary and hepatic metastases. She underwent radical nephrectomy and took a daily dose of 37.5 mg sunitinib. Partial response to sunitinib was achieved and maintained for 5 months, but when nephrotic syndrome occurred, drug intake was discontinued. The nephrotic syndrome gradually resolved around 2 months after discontinuation of sunitinib and medical management. Our case highlighted the favorable response of a particular non-clear cell type renal cell carcinoma to sunitinib and the specific toxicity associated with the antiangiogenic effect of sunitinib.

We present a case report of a renal cell carcinoma with TFE3 overexpression (related to TFE3 gene fusion) in a 63-year-old woman. Such tumors have been reported predominantly in children and young adults, and to our knowledge there are only 2 such cases mentioned in the literature in patients older than ours. However, we believe that this tumor may be underdiagnosed in adults owing to its similarity to clear cell (conventional) carcinoma and in some cases to papillary renal carcinoma.

Lysosomes are acidic and hydrolytic organelles responsible for receiving and digesting cargo acquired during endocytosis, phagocytosis, and autophagy. For macrophages and dendritic cells, the lysosome is kingpin, playing a direct role in microbe killing and antigen processing for presentation. Strikingly, the historic view that lysosomes are homogeneous and static organelles is being replaced with a more elegant paradigm, in which lysosomes are heterogeneous, dynamic, and respond to cellular needs. For example, lysosomes are signalling platforms that integrate stress detection and molecular decision hubs such as the mTOR complex 1 and AMPK to modulate cellular activity. These signals can even adjust lysosome activity by modulating transcription factors such as transcription factor EB (TFEB) and TFE3 that govern lysosome gene expression. Here, we review lysosome remodelling and adaptation during macrophage and dendritic cell stimulation. First, we assess the functional outcomes and regulatory mechanisms driving the dramatic restructuring of lysosomes from globular organelles into a tubular network during phagocyte activation. Second, we discuss lysosome adaptation and scaling in macrophages driven by TFEB and TFE3 stimulation in response to phagocytosis and microbe challenges. Collectively, we are beginning to appreciate that lysosomes are dynamic and adapt to serve phagocyte differentiation in response to microbes and immune stress.

Papillary renal cell carcinoma may display some unusual morphologic variations, including diffuse oncocytic change not otherwise specified, oncocytic change associated with an inverted nuclear pattern or nonoverlapping low-grade nuclei, low-grade spindle cells, and diffuse clear cells. Tumors comprised predominantly of thyroid-like follicles and inspissated eosoinophilic, colloid-like secretions (thyroid-like follicular carcinoma of the kidney) have been recently recognized. We report herein an unusual renal carcinoma that displayed diffuse clear cells, papillary architecture, foamy histiocytes, psammomatous calcifications, and large areas (approximately 20% of tumor volume) with thyroid macrofollicular-like structures and eosinophilic, colloid-like secretions. The tumor was diffusely positive for alpha-methylacyl-CoA racemase, cytokeratin 7 and CD10, and was entirely negative for CD15, thyroglobulin, thyroid-transcription factor-1, TFE3, and renal cell carcinoma antigen. Fluorescence in situ hybridization using centromeric DNA probes for chromosomes 7, 17, 3, and 3p25 showed gains only in chromosome 7 and no other aberrations. The tumor was accordingly classified as an unusual morphologic variation of papillary renal cell carcinoma. This case affirms the potential for papillary renal cell carcinoma to display a diffuse complement of clear cells, and documents the heretofore unreported finding of large areas of thyroid macrofollicular structures and eosinophilic, colloid-like secretions in this histotype.

Alveolar soft part sarcoma is a rare soft tissue tumor typically affecting young adults. These tumors are most often seen in the deep soft tissues of the extremities and patients generally present with advanced disease. Primary bone involvement is extremely rare and has only been reported in seven cases. This is the first case of alveolar soft part sarcoma in bone documenting the ASPL-TFE3 gene product. Herein, we report a rare presentation of alveolar soft part sarcoma presenting as a primary bone neoplasm involving the proximal fibula in a 41-year-old woman.

The DNA-binding factor TFE3 is closely related to microphthalmia-associated transcription factor (MiTF) and is over-expressed in alveolar soft part sarcoma (ASPS) and select renal cell carcinomas. Reports of TFE3 expression in PEComa prompted investigation into TFE3 expression among other members of the putative MiTF group of neoplasms. The authors examined cases of PEComa (n = 6), conventional angiomyolipoma (AML; n = 22), metastatic melanoma (n = 16), and clear cell sarcoma (CCS; n = 9) for TFE3 expression. Nuclear immunostaining was observed in 74% (39/53) of cases, as follows: 5/6 PEComas, 18/22 AMLs, 10/16 metastatic melanomas, and 6/9 CCSs. However, with the exception of PEComas, compared with ASPS controls, TFE3 staining was significantly less intense in the tumors examined. These results illustrate that TFE3 immunoreactivity is detectable in other members of the MiTF family of neoplasms. For this reason, such neoplasms warrant consideration in the differential diagnosis with nuclear TFE3 immunoreactivity, particularly when staining is focal and less intense.

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.

Human pluripotent stem cells (hPSC) have promise for regenerative medicine due to their auto-renovation and differentiation capacities. Nevertheless, there are several ethical and methodological issues about these cells that have not been resolved. Human amniotic epithelial cells (hAEC) have been proposed as source of pluripotent stem cells. Several groups have studied hAEC but have reported inconsistencies about their pluripotency properties. The aim of the present study was the in vitro characterization of hAEC collected from a Mexican population in order to identify transcription factors involved in the pluripotency circuitry and to determine their epigenetic state. Finally, we evaluated if these cells differentiate to cortical progenitors. We analyzed qualitatively and quantitatively the expression of the transcription factors of pluripotency (OCT4, SOX2, NANOG, KLF4 and REX1) by RT-PCR and RT-qPCR in hAEC. Also, we determined the presence of OCT4, SOX2, NANOG, SSEA3, SSEA4, TRA-1-60, E-cadherin, KLF4, TFE3 as well as the proliferation and epigenetic state by immunocytochemistry of the cells. Finally, hAEC were differentiated towards cortical progenitors using a protocol of two stages. Here we show that hAEC, obtained from a Mexican population and cultured in vitro (P0-P3), maintained the expression of several markers strongly involved in pluripotency maintenance (OCT4, SOX2, NANOG, TFE3, KLF4, SSEA3, SSEA4, TRA-1-60 and E-cadherin). Finally, when hAEC were treated with growth factors and small molecules, they expressed markers characteristic of cortical progenitors (TBR2, OTX2, NeuN and β-III-tubulin). Our results demonstrated that hAEC express naïve pluripotent markers (KLF4, REX1 and TFE3) as well as the cortical neuron phenotype after differentiation. This highlights the need for further investigation of hAEC as a possible source of hPSC.

Renal cell carcinoma (RCC) associated with neuroblastoma (NB) was included as a distinct entity in the 2004 World Health Organization classification of kidney tumors. A spectrum of RCC subtypes has been reported in NB survivors. We herein describe a series of 8 RCCs diagnosed in 7 patients with a history of NB. Microscopic evaluation, immunohistochemical staining for PAX8, cathepsin K, and succinate dehydrogenase subunit B (SDHB), and fluorescence in situ hybridization (FISH) for TFE3 and TFEB were performed. Four distinct morphologic subtypes were identified: 3 tumors were characterized by cells with abundant oncocytoid cytoplasm and irregular nuclei; 3 showed features of microphthalmia transcription factor family translocation RCC (MiTF-RCC); 1 had features of hybrid oncocytic-chromophobe tumor; 1 had papillary RCC histology. All RCCs expressed PAX8 and retained SDHB expression. Cathepsin K was positive in 2 MiTF-RCCs, 1 was TFEB FISH positive, and the other was indeterminate. Cathepsin K was negative in a third MiTF-RCC with TFE3 rearrangement. TFE3 FISH was negative in 4 and insufficient in 1 of the other 5 RCCs. While a subset of RCCs associated with NB is characterized by cells with prominent oncocytoid cytoplasm, other RCC subtypes also occur in post-NB patients. Renal neoplasms occurring in patients with a history of NB do not represent a single entity but a heterogenous group of RCCs. SDHB mutations do not explain the subset of nontranslocation RCCs with oncocytoid features; therefore, further studies are needed to clarify whether they may represent a distinct entity with unique molecular abnormalities or may belong to other emerging RCC subtypes.