Fusion of splicing factor genes PSF and NonO (p54nrb) to the TFE3 gene in papillary renal cell carcinoma

TFE3 fusion oncoprotein condensates drive transcriptional reprogramming and cancer progression in translocation renal cell carcinoma

Translocation renal cell carcinoma (tRCC) presents a significant clinical challenge due to its aggressiveness and limited treatment options. It is primarily driven by fusion oncoproteins (FOs), yet their role in oncogenesis is not fully understood. Here, we investigate TFE3 fusions in tRCC, focusing on NONO::TFE3 and SFPQ::TFE3. We demonstrate that TFE3 FOs form liquid-like condensates with increased transcriptional activity, localizing to TFE3 target genes and promoting cell proliferation and migration. The coiled-coil domains (CCDs) of NONO and SFPQ are essential for condensate formation, prolonging TFE3 FOs' chromatin binding time and enhancing transcription. Compared with wild-type TFE3, TFE3 FOs bind to new chromatin regions, alter chromatin accessibility, and form new enhancers and super-enhancers at pro-growth gene loci. Disruption of condensate formation via CCD modification abolishes these genome-wide changes. Altogether, our integrated analyses underscore the critical functions of TFE3 FO condensates in driving tumor cell growth, providing key insights for future therapeutic strategies.

TFE3 fusions drive oxidative metabolism and ferroptosis resistance in translocation renal cell carcinoma

The oncogenic mechanisms by which TFE3 fusion proteins drive translocation renal cell carcinoma (tRCC) are poorly characterized. Here, we integrated loss and gain of function experiments with multi-omics analyses in tRCC cell lines and patient tumors. High nuclear accumulation of NONO-TFE3 or PRCC-TFE3 fusion proteins promotes their broad binding across the genome at H3K27ac-marked active chromatin, engaging a core set of M/E-box-containing regulatory elements to activate specific gene expression programs as well as promiscuous binding to active promoters to stimulate mRNA synthesis. Within the core program, TFE3 fusions directly regulate genes involved in ferroptosis resistance and oxidative phosphorylation metabolism (OxPhos). Consequently, human tRCC tumors display high OxPhos scores that persist during their epithelial to mesenchymal transition (EMT). We further show that tRCC tumor aggressiveness is related to their EMT and their associated enrichment in myofibroblast cancer-associated fibroblasts (myCAFs) that are both hallmarks of poor prognostic outcomes. We define tRCC as a novel metabolic subtype of renal cancer and provide unique insights into how broad genomic binding of TFE3 fusion proteins regulates OxPhos and ferroptosis resistance.

Upregulation of GSTP1 mediated by chimeric TFE3 promotes TFE3-tRCC progression by targeting JNK signaling pathway

BACKGROUND

TFE3-translocation renal cell carcinoma (TFE3-tRCC), a distinct subtype of kidney cancer characterized by Xp11.2 translocations, involving TFE3 fusion with various partner genes, lacks effective treatments and prognostic biomarkers for advanced stages. This study aimed to unravel the pathogenic mechanisms and uncover novel therapeutic targets.

METHODS

The transcriptional characterization of TFE3-tRCC was conducted by RNA sequencing on 14 untreated primary TFE3-tRCC patients. The relative mRNA and protein levels were detected using qRT-PCR and Western blot, respectively. The location of ASPL-TFE3 fusion protein was analyzed by immunofluorescence. MTT and colony formation assays were used to detect cell proliferation. Annexin V/PI staining was used to evaluate cell apoptosis. Transwell assays were used to evaluate in vitro cell migration and invasion.

RESULTS

In TFE3-tRCC patients, GSTP1 expression was upregulated. ASPL-TFE3 cell models revealed that the ASPL-TFE3 fusion protein translocates to the nucleus, contributing to tumorigenesis. Notably, GSTP1 was transcriptionally activated by chimeric TFE3. Treatment with GSTP1-targeting siRNA or the GSTP1 inhibitor Ezatiostat effectively inhibited tumor growth and induced apoptosis in TFE3-tRCC cells. Furthermore, GSTP1 was found to drive TFE3-tRCC progression via modulation of the JNK signaling pathway.

CONCLUSION

Upregulation of GSTP1 mediated by chimeric TFE3 promotes TFE3-tRCC progression by targeting JNK signaling pathway, which underscore the potential of GSTP1 as a promising therapeutic target for TFE3-tRCC.

TFE3-Rearranged Tumors of the Kidney: An Emerging Conundrum

Background: Identical translocations involving the TFE3 gene and various partners have been found in both renal and soft tissue tumors, like alveolar soft part sarcoma (ASPSCR1), ossifying fibromyxoid tumor (PHF1), epithelioid hemangioendothelioma, and the clear cell stromal tumor of the lung (YAP1). Methods: Herein, we review in detail the clinicopathologic and molecular data of TFE3-rearranged renal tumors and propose our perspective, which may shed light on this emerging conundrum. Results: Among the kidney tumors carrying TFE3 translocations, most are morphologically heterogeneous carcinomas labeling for the tubular marker PAX8. The others are mesenchymal neoplasms known as PEComas, characterized by epithelioid cells co-expressing smooth muscle actin, cathepsin-K, melanogenesis markers, and sometimes melanin pigment deposition. Over the past 30 years, numerous TFE3 fusion partners have been identified, with ASPL/ASPSCR1, PRCC, SFPQ/PSF, and NONO being the most frequent. Conclusions: It is not well understood why similar gene fusions can give rise to renal tumors with different morpho-immunophenotypes, which may contribute to the recent disagreement regarding their classification. However, as these two entities, respectively, epithelial and mesenchymal in nature, are widely recognized by the pathology community and their clinicopathologic features well established, we overall believe it is still better to retain the names TFE3-rearranged renal cell carcinoma and TFE3-rearranged PEComa.

Exploring G-quadruplex structure in PRCC-TFE3 fusion oncogene: Plausible use as anti cancer therapy for translocation Renal cell carcinoma (tRCC)

The TFE3 fusion gene, byproduct of Xp11.2 translocation, is the diagnostic marker for translocation renal cell carcinoma (tRCC). Absence of any clinically recognized therapy for tRCC, pressing a need to create novel and efficient therapeutic approaches. Previous studies shown that stabilization of the G-quadruplex structure in oncogenes suppresses their expression machinery. To combat the oncogenesis caused by fusion genes, our objective is to locate and stabilize the G-quadruplex structure within the PRCC-TFE3 fusion gene. Using the Quadruplex-forming G Rich Sequences (QGRS) mapper and the Non-B DNA motif search tool (nBMST) online server, we found putative G-quadruplex forming sequences (PQS) in the PRCC-TFE3 fusion gene. Circular dichroism demonstrating a parallel G-quadruplex in the targeted sequence. Fluorescence and UV-vis spectroscopy results suggest that pyridostatin binds to this newly discovered G-quadruplex. The PCR stop assay, as well as transcriptional or translational inhibition using real time PCR and Dual luciferase assay, revealed that stable G-quadruplex formation affects biological processes. Confocal microscopy of HEK293T cells transfected with the fusion transcript confirmed G-quadruplexes formation in cell. This investigation may shed light on G-quadruplex's functions in fusion genes and may help in the development of therapies specifically targeted against fusion oncogenes, which would enhance the capability of current tRCC therapy approach.

The pleiotropic nature of NONO, a master regulator of essential biological pathways in cancers

NONO is a member of the Drosophila behavior/human splicing (DBHS) family of proteins. NONO is a multifunctional protein that acts as a "molecular scaffold" to carry out versatile biological activities in many aspects of gene regulation, cell proliferation, apoptosis, migration, DNA damage repair, and maintaining cellular circadian rhythm coupled to the cell cycle. Besides these physiological activities, emerging evidence strongly indicates that NONO-altered expression levels promote tumorigenesis. In addition, NONO can undergo various post-transcriptional or post-translational modifications, including alternative splicing, phosphorylation, methylation, and acetylation, whose impact on cancer remains largely to be elucidated. Overall, altered NONO expression and/or activities are a common feature in cancer. This review provides an integrated scenario of the current understanding of the molecular mechanisms and the biological processes affected by NONO in different tumor contexts, suggesting that a better elucidation of the pleiotropic functions of NONO in physiology and tumorigenesis will make it a potential therapeutic target in cancer. In this respect, due to the complex landscape of NONO activities and interactions, we highlight caveats that must be considered during experimental planning and data interpretation of NONO studies.

TFE3 -Rearranged PEComa/PEComa-like Neoplasms : Report of 25 New Cases Expanding the Clinicopathologic Spectrum and Highlighting its Association With Prior Exposure to Chemotherapy

Since their original description as a distinctive neoplastic entity, ~50 TFE3 -rearranged perivascular epithelioid cell tumors (PEComas) have been reported. We herein report 25 new TFE3 -rearranged PEComas and review the published literature to further investigate their clinicopathologic spectrum. Notably, 5 of the 25 cases were associated with a prior history of chemotherapy treatment for cancer. This is in keeping with prior reports, based mainly on small case series, with overall 11% of TFE3 -rearranged PEComas being diagnosed postchemotherapy. The median age of our cohort was 38 years. Most neoplasms demonstrated characteristic features such as nested architecture, epithelioid cytology, HMB45 positive, and muscle marker negative immunophenotype. SFPQ was the most common TFE3 fusion partner present in half of the cases, followed by ASPSCR1 and NONO genes. Four of 7 cases in our cohort with meaningful follow-up presented with or developed systemic metastasis, while over half of the reported cases either recurred locally, metastasized, or caused patient death. Follow-up for the remaining cases was limited (median 18.5 months), suggesting that the prognosis may be worse. Size, mitotic activity, and necrosis were correlated with aggressive behavior. There is little evidence that treatment with MTOR inhibitors, which are beneficial against TSC -mutated PEComas, is effective against TFE3 -rearranged PEComas: only one of 6 reported cases demonstrated disease stabilization. As co-expression of melanocytic and muscle markers, a hallmark of conventional TSC -mutated PEComa is uncommon in the spectrum of TFE3 -rearranged PEComa, an alternative terminology may be more appropriate, such as " TFE3 -rearranged PEComa-like neoplasms," highlighting their distinctive morphologic features and therapeutic implications.

A nomogram based on TFE3 IHC results and clinical factors as a preliminary screening scheme for TFE3-rearranged renal cell carcinoma

BACKGROUND

TFE3 immunohistochemistry (TFE3-IHC) is controversial in the diagnosis of TFE3-rearranged renal cell carcinoma (TFE3-rearranged RCC). This study is to investigate the accuracy and sensitivity of IHC and establish a predictive model to diagnose TFE3-rearranged RCC.

METHODS

Retrospective analysis was performed by collecting IHC and fluorescence in situ hybridization (FISH) results from 228 patients. IHC results were evaluated using three scoring systems. Scoring system 1 is graded based on nuclear staining intensity, scoring system 2 is graded based on the percentage of stained tumor cell nuclei, and scoring system 3 is graded based on both the nuclear staining intensity and the percentage. We collected patients' IHC results and clinical information. Important variables were screened based on univariate logistic regression analysis. Then, independent risk factors were established through multivariate logistic regression, and a nomogram model was constructed. The model was validated in internal test set and external validation set. The receiver operating characteristic curve (ROC curve), calibration curve, and decision curve analysis (DCA) were generated to assess discriminative ability of the model.

RESULTS

The accuracy of IHC based on three scoring systems were 0.829, 0.772, and 0.807, respectively. The model included four factors including age, gender, lymph node metastasis and IHC results. Area under the curve (AUC) values were 0.935 for the training set, 0.934 for the internal test set, 0.933 for all 228 patients, and 0.916 for the external validation set.

CONCLUSIONS

TFE3 IHC has high accuracy in the diagnosis of TFE3-rearranged RCC. Clinical information such as age and lymph node metastasis are independent risk factors, which can be used as a supplement to the results of TFE3 IHC. This study confirms the value of IHC in the diagnosis of TFE3-rearranged RCC. The accuracy of the diagnosis can be improved by incorporating IHC with other clinical risk factors.

Comparative genomics incorporating translocation renal cell carcinoma mouse model reveals molecular mechanisms of tumorigenesis

Translocation renal cell carcinoma (tRCC) most commonly involves an ASPSCR1-TFE3 fusion, but molecular mechanisms remain elusive and animal models are lacking. Here, we show that human ASPSCR1-TFE3 driven by Pax8-Cre (a credentialed clear cell RCC driver) disrupted nephrogenesis and glomerular development, causing neonatal death, while the clear cell RCC failed driver, Sglt2-Cre, induced aggressive tRCC (as well as alveolar soft part sarcoma) with complete penetrance and short latency. However, in both contexts, ASPSCR1-TFE3 led to characteristic morphological cellular changes, loss of epithelial markers, and an epithelial-mesenchymal transition. Electron microscopy of tRCC tumors showed lysosome expansion, and functional studies revealed simultaneous activation of autophagy and mTORC1 pathways. Comparative genomic analyses encompassing an institutional human tRCC cohort (including a hitherto unreported SFPQ-TFEB fusion) and a variety of tumorgraft models (ASPSCR1-TFE3, PRCC-TFE3, SFPQ-TFE3, RBM10-TFE3, and MALAT1-TFEB) disclosed significant convergence in canonical pathways (cell cycle, lysosome, and mTORC1) and less established pathways such as Myc, E2F, and inflammation (IL-6/JAK/STAT3, interferon-γ, TLR signaling, systemic lupus, etc.). Therapeutic trials (adjusted for human drug exposures) showed antitumor activity of cabozantinib. Overall, this study provides insight into MiT/TFE-driven tumorigenesis, including the cell of origin, and characterizes diverse mouse models available for research.

Established and Evolving Roles of the Multifunctional Non-POU Domain-Containing Octamer-Binding Protein (NonO) and Splicing Factor Proline- and Glutamine-Rich (SFPQ)

It has been more than three decades since the discovery of multifunctional factors, the Non-POU-Domain-Containing Octamer-Binding Protein, NonO, and the Splicing Factor Proline- and Glutamine-Rich, SFPQ. Some of their functions, including their participation in transcriptional and posttranscriptional regulation as well as their contribution to paraspeckle subnuclear body organization, have been well documented. In this review, we focus on several other established roles of NonO and SFPQ, including their participation in the cell cycle, nonhomologous end-joining (NHEJ), homologous recombination (HR), telomere stability, childhood birth defects and cancer. In each of these contexts, the absence or malfunction of either or both NonO and SFPQ leads to either genome instability, tumor development or mental impairment.

LncRNA like NMRK2 mRNA functions as a key molecular scaffold to enhance mitochondrial respiration of NONO-TFE3 rearranged renal cell carcinoma in an NAD+ kinase-independent manner

BACKGROUND

NONO-TFE3 rearranged renal cell carcinoma (NONO-TFE3 rRCC) is one of a subtype of TFE3 rRCCs with high malignancy and poor prognosis. Compared with clear cell RCC, NONO-TFE3 rRCC shows a preference for mitochondrial respiration. We recently identified that the upregulation of nicotinamide ribokinase 2 (NMRK2) was associated with enhanced mitochondrial respiration and tumor progression in TFE3 rRCC.

METHODS

A tumor-bearing mouse model was established to verify the pro-oncogenic effect of NMRK2 on NONO-TFE3 rRCC. Then the expression of NMRK2 RNA and protein was detected in cell lines and patient specimens. The NMRK2 transcripts were Sanger-sequenced and blasted at NCBI website. We constructed dCas13b-HA system to investigate the factors binding with NMRK2 RNA. We also used molecular experiments like RIP-seq, IP-MS, FISH and fluorescence techniques to explore the mechanisms that long non-coding RNA (lncRNA) like NMRK2 mRNA promoted the mitochondrial respiration of NONO-TFE3 rRCC. The efficacy of the combination of shRNA (NMRK2)-lentivirus and metformin on NONO-TFE3 rRCC was assessed by CCK-8 assay.

RESULTS

In this study, we confirmed that NMRK2 showed transcriptional-translational conflict and functioned as lncRNA like mRNA in the NONO-TFE3 rRCC. Furthermore, we revealed the molecular mechanism that NONO-TFE3 fusion suppressed the translation of NMRK2 mRNA. Most importantly, three major pathways were shown to explain the facilitation effects of lncRNA like NMRK2 mRNA on the mitochondrial respiration of NONO-TFE3 rRCC in an NAD+ kinase-independent manner. Finally, the efficacy of combination of shRNA (NMRK2)-lentivirus and metformin on NONO-TFE3 rRCC was demonstrated to be superior than either agent alone.

CONCLUSIONS

Overall, our data comprehensively demonstrated the mechanisms for the enhanced mitochondrial respiration in NONO-TFE3 rRCC and proposed lncRNA like NMRK2 mRNA as a therapy target for NONO-TFE3 rRCC.

Role of the long non-coding RNAs in regulation of Gemcitabine response in tumor cells

Chemotherapy is widely used as one of the first line therapeutic methods in cancer patients. However, chemotherapeutic resistance is one of the most common problems in cancer patients, which leads to the therapeutic failure and tumor relapse. Considering the side effects of chemotherapy drugs in normal tissues, it is required to investigate the molecular mechanisms involved in drug resistance to improve the therapeutic strategies in cancer patients. Long non-coding RNAs (lncRNAs) have pivotal roles in regulation of cellular processes associated with drug resistance. LncRNAs deregulations have been frequently reported in a wide range of chemo-resistant tumors. Gemcitabine (GEM) as a nucleoside analog has a wide therapeutic application in different cancers. However, GEM resistance is considered as a therapeutic challenge. Considering the role of lncRNAs in the occurrence of GEM resistance, in the present review we discussed the molecular mechanisms of lncRNAs in regulation of GEM response among cancer patients. It has been reported that lncRNAs have mainly an oncogenic role as the inducers of GEM resistance through direct or indirect regulation of transcription factors, autophagy, polycomb complex, and signaling pathways such as PI3K/AKT, MAPK, WNT, JAK/STAT, and TGF-β. This review paves the way to present the lncRNAs as non-invasive markers to predict GEM response in cancer patients. Therefore, lncRNAs can be introduced as the efficient markers to reduce the possible chemotherapeutic side effects in GEM resistant cancer patients and define a suitable therapeutic strategy among these patients.

MED15::TFE3 Renal Cell Carcinomas: Report of Two New Cases and Review of the Literature Confirming Nearly Universal Multilocular Cystic Morphology

We report two novel cases of Xp11 translocation renal cell carcinomas with the MED15::TFE3 gene fusion in adult females aged 40 and 74 years. Both cases were extensively cystic and contained only minimal clear cells lining cysts and within septal walls, raising the differential diagnosis of multilocular cystic renal neoplasm of low malignant potential. By immunohistochemistry, both neoplasms labeled for PAX8, TFE3, cathepsin K and Melan A but not for HMB45. On review of the published literature and the two cases reported herein, over 90% of MED15::TFE3 renal cell carcinomas (RCCs) have been described as cystic. The correlation of the MED15::TFE3 fusion with extensively cystic morphology represents the strongest association of TFE3 fusion partner with clinicopathological features among TFE3-rearranged RCC reported to date.

High-throughput and targeted drug screens identify pharmacological candidates against MiT-translocation renal cell carcinoma

BACKGROUND

MiT-Renal Cell Carcinoma (RCC) is characterized by genomic translocations involving microphthalmia-associated transcription factor (MiT) family members TFE3, TFEB, or MITF. MiT-RCC represents a specific subtype of sporadic RCC that is predominantly seen in young patients and can present with heterogeneous histological features making diagnosis challenging. Moreover, the disease biology of this aggressive cancer is poorly understood and there is no accepted standard of care therapy for patients with advanced disease. Tumor-derived cell lines have been established from human TFE3-RCC providing useful models for preclinical studies.

METHODS

TFE3-RCC tumor derived cell lines and their tissues of origin were characterized by IHC and gene expression analyses. An unbiased high-throughput drug screen was performed to identify novel therapeutic agents for treatment of MiT-RCC. Potential therapeutic candidates were validated in in vitro and in vivo preclinical studies. Mechanistic assays were conducted to confirm the on-target effects of drugs.

RESULTS

The results of a high-throughput small molecule drug screen utilizing three TFE3-RCC tumor-derived cell lines identified five classes of agents with potential pharmacological efficacy, including inhibitors of phosphoinositide-3-kinase (PI3K) and mechanistic target of rapamycin (mTOR), and several additional agents, including the transcription inhibitor Mithramycin A. Upregulation of the cell surface marker GPNMB, a specific MiT transcriptional target, was confirmed in TFE3-RCC and evaluated as a therapeutic target using the GPNMB-targeted antibody-drug conjugate CDX-011. In vitro and in vivo preclinical studies demonstrated efficacy of the PI3K/mTOR inhibitor NVP-BGT226, Mithramycin A, and CDX-011 as potential therapeutic options for treating advanced MiT-RCC as single agents or in combination.

CONCLUSIONS

The results of the high-throughput drug screen and validation studies in TFE3-RCC tumor-derived cell lines have provided in vitro and in vivo preclinical data supporting the efficacy of the PI3K/mTOR inhibitor NVP-BGT226, the transcription inhibitor Mithramycin A, and GPNMB-targeted antibody-drug conjugate CDX-011 as potential therapeutic options for treating advanced MiT-RCC. The findings presented here should provide the basis for designing future clinical trials for patients with MiT-driven RCC.

Estrogen associates with female predominance in Xp11.2 translocation renal cell carcinoma

Based on the epidemiological characteristics of susceptibility and age selectivity for women in Xp11.2 translocation renal cell carcinoma (Xp11.2 tRCC), we inferred that estrogen was to be blamed. Rad54 like 2 (Rad54l2) which might be one of key effector proteins of DNA damage mediated by estrogen was downregulated in numerous cancers, however, its role in epidemiological characteristics of Xp11.2 tRCC was needed to further study. We reviewed 1005 Xp11.2 tRCC cases and collected estrogen data and then compared the onset time of Xp11.2 tRCC cases in female with estrogen changing trend. An RNA-sequencing was performed in estrogen treated HK-2 cells and subsequently bioinformatic analysis was applied based on the Cancer Genome Atlas (TCGA) and GEO database. The male-to-female ratio of Xp11.2 tRCC was 1:1.4 and the median age of onset was 29.7 years old. The onset trend of female was similar to estrogen physiological rhythm (r = 0.67, p < 0.01). In Xp11.2 tRCC and HK-2 cells after estrogen treatment, Rad54l2 was downregulated, and GSEA showed that pathways significantly enriched in DNA damage repair and cancer related clusters after estrogen treated, as well as GO and KEGG analysis. Downregulation of Rad54l2 was in numerous cancers, including renal cell carcinoma (RCC), in which Rad54l2 expression was significantly decreased in male, age over 60 years old, T2&T3&T4 stages, pathologic SII&SIII&SIV stages as well as histologic G3&G4 grades, and cox regression analysis proved that Rad54l2 expression was a risk factor for overall survival, disease-specific survival and progression-free interval in univariate analysis. There existed female predominance in Xp11.2 tRCC and Rad54l2 might play vital role in estrogen mediating female predominance in Xp11.2 tRCC.

Systematic assessment of prognostic molecular features across cancers

Precision oncology promises accurate prediction of disease trajectories by utilizing molecular features of tumors. We present a systematic analysis of the prognostic potential of diverse molecular features across large cancer cohorts. We find that the mRNA expression of biologically coherent sets of genes (modules) is substantially more predictive of patient survival than single-locus genomic and transcriptomic aberrations. Extending our analysis beyond existing curated gene modules, we find a large novel class of highly prognostic DNA/RNA cis-regulatory modules associated with dynamic gene expression within cancers. Remarkably, in more than 82% of cancers, modules substantially improve survival stratification compared with conventional clinical factors and prominent genomic aberrations. The prognostic potential of cancer modules generalizes to external cohorts better than conventionally used single-gene features. Finally, a machine-learning framework demonstrates the combined predictive power of multiple modules, yielding prognostic models that perform substantially better than existing histopathological and clinical factors in common use.

Clinical and pathological heterogeneity of four common fusion subtypes in Xp11.2 translocation renal cell carcinoma

Background

Xp11.2 translocation renal cell carcinoma (Xp11.2 tRCC) is a group of rare and highly heterogeneous renal cell carcinoma (RCC). The translocation involving TFE3 and different fusion partners lead to overexpression of the chimeric protein. The purpose of this study is to explore the clinicopathological features of Xp11.2 tRCC with four common fusion subtypes.

Methods

We screened out 40 Xp11.2 tRCC patients from January 2007 to August 2021 in our institution. The diagnosis was initially confirmed by TFE3 immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) assay and their fusion partners were verified by RNA sequencing. Then the 40 cases were divided into two groups (DBHS family and non-DBHS family group) and a clinical comparison among the four common fusion subtypes was performed.

Results

Among the 40 cases, 11 cases with SFPQ-TFE3 gene fusion and 7 cases with NONO-TFE3 gene fusion were classified in DBHS group, the remaining cases with ASPL-TFE3 (11 cases) or PRCC-TFE3 (11 cases) gene fusion were classified in non-DBHS group. Lymph node (LN) metastasis (P=0.027) and distant metastasis (P=0.009) were more common seen in non-DBHS family group than DBHS family group and cases in DBHS family group have better progressive-free survival (PFS) (P=0.02). In addition, ASPL-TFE3 fusion was associated with worse outcome (P=0.03) while NONO-TFE3 fusion (P=0.04) predicted a better prognosis.

Conclusions

Different fusion partner genes may play a functional role in various morphology, molecular and biological features of Xp11.2 tRCCs. The impact of fusion partners on clinical characteristics of Xp11.2 tRCCs deserves further exploration.

TFE3-immunopositive papillary renal cell carcinoma: A clinicopathological, immunohistochemical, and genetic study

It is possible that PRCCs may still contain a variety of unknown histologic subtypes. Some PRCCs express high expression of TFE3 protein without TFE3 gene rearrangement, but no reports have investigated the significance of this. Here we attempted to examine clinicopathological and molecular significance of the TFE3-immunopositive PRCC. We reviewed the histology and immunohistochemistry in 58 PRCCs. TFE3 immunoexpression was recognized in 7 cases. Because TFE3 immunostaining shows false-positive, to ensure the integrity of TFE3 immunostaining, the immunostaining was performed under strict control of internal controls and western blotting was performed on 2 positive cases and 5 negative cases, and differences in protein expression between two groups were confirmed. Significant immunohistochemical expressions of autophagy/lysosome proteins were observed in TFE3-positive group. No TFE3 gene arrangement was detected in all positive cases by fluorescence in situ hybridization. Whole-exome sequencing was performed on 6 TFE3-positive and 2 TFE3-negative cases. Gain of chromosome 7 was found in five of 6 TFE3-positive cases (83%). TFE3-positive group was correlated significantly with higher pTstage, cNstage, WHO/ISUP nuclear grade, and decreased OS. TFE3-immunopositive PRCC group had a poorer prognosis than TFE3-negative PRCC group and showed correlation with expressions of autophagy/lysosome proteins, suggesting that enhancement of autophagy/lysosome function drives an environment of energy metabolism that is favorable for cancer. It is necessary to recognize that there is TFE3-immunopositive group without TFE3 gene rearrangement within PRCC. Because of its aggressive biological behaviour, TFE3 can act as a biomarker in PRCC; moreover, autophagy-inhibiting drugs may have therapeutic effects on TFE3-immunopositive PRCC.

A central role for regulated protein stability in the control of TFE3 and MITF by nutrients

The TFE3 and MITF master transcription factors maintain metabolic homeostasis by regulating lysosomal, melanocytic, and autophagy genes. Previous studies posited that their cytosolic retention by 14-3-3, mediated by the Rag GTPases-mTORC1, was key for suppressing transcriptional activity in the presence of nutrients. Here, we demonstrate using mammalian cells that regulated protein stability plays a fundamental role in their control. Amino acids promote the recruitment of TFE3 and MITF to the lysosomal surface via the Rag GTPases, activating an evolutionarily conserved phospho-degron and leading to ubiquitination by CUL1β-TrCP and degradation. Elucidation of the minimal functional degron revealed a conserved alpha-helix required for interaction with RagA, illuminating the molecular basis for a severe neurodevelopmental syndrome caused by missense mutations in TFE3 within the RagA-TFE3 interface. Additionally, the phospho-degron is recurrently lost in TFE3 genomic translocations that cause kidney cancer. Therefore, two divergent pathologies converge on the loss of protein stability regulation by nutrients.

Transcription factor EB as a key molecular factor in human health and its implication in diseases

Transcription factor EB, as a component of the microphthalmia family of transcription factors, has been demonstrated to be a key controller of autophagy-lysosomal biogenesis. Transcription factor EB is activated by stressors such as nutrition and deprivation of growth factors, hypoxia, lysosomal stress, and mitochondrial injury. To achieve the ultimate functional state, it is controlled in a variety of modes, such as in its rate of transcription, post-transcriptional control, and post-translational alterations. Due to its versatile role in numerous signaling pathways, including the Wnt, calcium, AKT, and mammalian target of rapamycin complex 1 signaling pathways, transcription factor EB-originally identified to be an oncogene-is now well acknowledged as a regulator of a wide range of physiological systems, including autophagy-lysosomal biogenesis, response to stress, metabolism, and energy homeostasis. The well-known and recently identified roles of transcription factor EB suggest that this protein might play a central role in signaling networks in a number of non-communicable illnesses, such as cancer, cardiovascular disorders, drug resistance mechanisms, immunological disease, and tissue growth. The important developments in transcription factor EB research since its first description are described in this review. This review helps to advance transcription factor EB from fundamental research into therapeutic and regenerative applications by shedding light on how important a role it plays in human health and disease at the molecular level.

TRPML1 and TFEB, an Intimate Affair

Ca²⁺ is a universal second messenger that plays a wide variety of fundamental roles in cellular physiology. Thus, to warrant selective responses and to allow rapid mobilization upon specific stimuli, Ca²⁺ is accumulated in organelles to keep it at very low levels in the cytoplasm during resting conditions. Major Ca²⁺ storage organelles include the endoplasmic reticulum (ER), the mitochondria, and as recently demonstrated, the lysosome (Xu and Ren, Annu Rev Physiol 77:57-80, 2015). The importance of Ca²⁺ signaling deregulation in human physiology is underscored by its involvement in several human diseases, including lysosomal storage disorders, neurodegenerative disease and cancer (Shen et al., Nat Commun 3:731, 2012; Bae et al., J Neurosci 34:11485-11503, 2014). Recent evidence strongly suggests that lysosomal Ca²⁺ plays a major role in the regulation of lysosomal adaptation to nutrient availability through a lysosomal signaling pathway involving the lysosomal Ca²⁺ channel TRPML1 and the transcription factor TFEB, a master regulator for lysosomal function and autophagy (Sardiello et al., Science 325:473-477, 2009; Settembre et al., Science 332:1429-1433, 2011; Medina et al., Nat Cell Biol 17:288-299, 2015; Di Paola et al., Cell Calcium 69:112-121, 2018). Due to the tight relationship of this lysosomal Ca²⁺ channel and TFEB, in this chapter, we will focus on the role of the TRPML1/TFEB pathway in the regulation of lysosomal function and autophagy.

How New Developments Impact Diagnosis in Existing Renal Neoplasms

In recent years, several emerging diagnostic entities have been described in renal cell carcinoma (RCC). However, our understanding of well-known and established entities has also grown. Clear cell papillary RCC is now relabeled as a tumor rather than carcinoma in view of its nonaggressive behavior. Renal tumors with a predominantly infiltrative pattern are very important for recognition, as most of these have aggressive behavior, including fumarate hydratase-deficient RCC, SMARCB1-deficient medullary carcinoma, collecting duct carcinoma, urothelial carcinoma, and metastases from other cancers.

Past, present, and future perspectives of transcription factor EB (TFEB): mechanisms of regulation and association with disease

Transcription factor EB (TFEB), a member of the MiT/TFE family of basic helix-loop-helix leucine zipper transcription factors, is an established central regulator of the autophagy/lysosomal-to-nucleus signaling pathway. Originally described as an oncogene, TFEB is now widely known as a regulator of various processes, such as energy homeostasis, stress response, metabolism, and autophagy-lysosomal biogenesis because of its extensive involvement in various signaling pathways, such as mTORC1, Wnt, calcium, and AKT signaling pathways. TFEB is also implicated in various human diseases, such as lysosomal storage disorders, neurodegenerative diseases, cancers, and metabolic disorders. In this review, we present an overview of the major advances in TFEB research over the past 30 years, since its description in 1990. This review also discusses the recently discovered regulatory mechanisms of TFEB and their implications for human diseases. We also summarize the moonlighting functions of TFEB and discuss future research directions and unanswered questions in the field. Overall, this review provides insight into our understanding of TFEB as a major molecular player in human health, which will take us one step closer to promoting TFEB from basic research into clinical and regenerative applications.

PEComa-like Neoplasms Characterized by ASPSCR1-TFE3 Fusion: Another Face of TFE3-related Mesenchymal Neoplasia

Identical TFE3-related gene fusions may be found in renal cell carcinoma and mesenchymal neoplasms such as alveolar soft part sarcoma and TFE3-rearranged perivascular epithelioid cell tumor (PEComa). Among mesenchymal neoplasms, the ASPSCR1-TFE3 gene fusion has previously been described only in alveolar soft part sarcoma. We report 3 unusual mesenchymal neoplasms harboring the ASPSCR1-TFE3 gene fusion, the morphologic phenotype of which more closely matches PEComa rather than alveolar soft part sarcoma. All 3 neoplasms occurred in females ranging in age from 18 to 34 years and were located in the viscera (kidney, bladder, and uterus). All 3 contained nests of epithelioid cells bounded by fibrovascular septa. However, all were associated with hyalinized stroma, tight nested architecture, mixed spindle cell and epithelioid pattern, clear cytoplasm, and lacked significant discohesion. Overall, morphologic features closely resembled PEComa, being distinct from the typical alveolar soft part sarcoma phenotype. While none of the neoplasms labeled for HMB45, cytokeratin, or PAX8 all showed positivity for TFE3 and cathepsin K, and all except 1 were positive for smooth muscle actin. One patient developed a liver metastasis 7 years after nephrectomy. These cases bridge the gap between 2 TFE3-rearranged neoplasms, specifically alveolar soft part sarcoma and Xp11 translocation PEComa, highlighting the relatedness and overlap among Xp11 translocation neoplasms. While most TFE3-rearranged neoplasms can be confidently placed into a specific diagnostic category such as alveolar soft part sarcoma, PEComa, or Xp11 translocation renal cell carcinoma, occasional cases have overlapping features, highlighting the potential role that the cell of origin and the specific gene fusion play in the phenotype of these neoplasms.

5mC and H3K9me3 of TRAF3IP2 promoter region accelerates the progression of translocation renal cell carcinoma

Background

In our previous study, we found that lncRNA TRAF3IP2 antisense RNA 1 (TRAF3IP2-AS1) could play a critical role in the progression of NONO-TFE3 translocation renal cell carcinoma (NONO-TFE3 tRCC). However, the function of TRAF3IP2 (TRAF3 interacting protein 2), encoded by the complementary strand of TRAF3IP2-AS1, remains poorly understood in NONO-TFE3 tRCC.

Methods

Immunohistochemistry, western blot, and qRT-PCR were undertaken to study the expression and clinical significance of TRAF3IP2 in Xp11.2 tRCC tissues and cells. The functions of TRAF3IP2 in tRCC were investigated by proliferation analysis, EdU staining, colony and sphere formation assay, Transwell assay, and apoptosis analysis. The regulatory mechanisms among TRAF3IP2, NOTCH1, and TRAF3IP2-AS1 were investigated by luciferase assay, RNA immunoprecipitation, western blot, methylated DNA Immunoprecipitation, and CRISPR/dCas9-based system.

Results

The results showed that TRAF3IP2 was highly expressed in NONO-TFE3 tRCC tissues and cells, and the silence of TRAF3IP2 inhibited the proliferation, migration, and invasion of UOK109 cells which were derived from cancer tissue of patient with NONO-TFE3 tRCC. Mechanistic studies revealed that TRAF3IP2 functioned as a co-activator of NOTCH1 to activate the NOTCH1 pathway. Meanwhile, HNRNPK, DNMT1 and SETDB1 could be recruited by TRAF3IP2-AS1 to the promoter region of TRAF3IP2, which mediated 5-hydroxymethylcytosine (5mC) on DNA and trimethylated lysine 9 of histone H3 (H3K9me3) at transcriptional level to repress the expression of TRAF3IP2.

Conclusions

TRAF3IP2 functions as an oncogene in NONO-TFE3 tRCC progression and might serve as a novel target for NONO-TFE3 tRCC therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40364-022-00402-3.

MiTF/TFE Translocation Renal Cell Carcinomas: From Clinical Entities to Molecular Insights

MiTF/TFE translocation renal cell carcinoma (tRCC) is a rare and aggressive subtype of RCC representing the most prevalent RCC in the pediatric population (up to 40%) and making up 4% of all RCCs in adults. It is characterized by translocations involving either TFE3 (TFE3-tRCC), TFEB (TFEB-tRCC) or MITF, all members of the MIT family (microphthalmia-associated transcriptional factor). TFE3-tRCC was first recognized in the World Health Organization (WHO) classification of kidney cancers in 2004. In contrast to TFEB-tRCC, TFE3-tRCC is associated with many partners that can be detected by RNA or exome sequencing. Both diagnoses of TFE3 and TFEB-tRCC are performed on morphological and immunohistochemical features, but, to date, TFE break-apart fluorescent in situ hybridization (FISH) remains the gold standard for diagnosis. The clinical behavior of tRCC is heterogeneous and more aggressive in adults. Management of metastatic tRCC is challenging, especially in the younger population, and data are scarce. Efficacy of the standard of care-targeted therapies and immune checkpoint inhibitors remains low. Recent integrative exome and RNA sequencing analyses have provided a better understanding of the biological heterogeneity, which can contribute to a better therapeutic approach. We describe the clinico-pathological entities, the response to systemic therapy and the molecular features and techniques used to diagnose tRCC.

Targeting chemoresistance in Xp11.2 translocation renal cell carcinoma using a novel polyamide-chlorambucil conjugate

Renal cell carcinoma with Xp11.2 translocation involving the TFE3 gene (TFE3-RCC) is a recently identified subset of RCC with unique morphology and clinical presentation. The chimeric PRCC-TFE3 protein produced by Xp11.2 translocation has been shown to transcriptionally activate its downstream target genes that play important roles in carcinogenesis and tumor development of TFE3-RCC. However, the underlying molecular mechanisms remain poorly understood. Here we show that in TFE3-RCC cells, PRCC-TFE3 controls heme oxygenase 1 (HMOX1) expression to confer chemoresistance. Inhibition of HMOX1 sensitized the PRCC-TFE3 expressing cells to genotoxic reagents. We screened for a novel chlorambucil-polyamide conjugate (Chb) to target PRCC-TFE3-dependent transcription, and identified Chb16 as a PRCC-TFE3-dependent transcriptional inhibitor of HMOX1 expression. Treatment of the patient-derived cancer cells with Chb16 exhibited senescence and growth arrest, and increased sensitivity of the TFE3-RCC cells to the genotoxic reagent etoposide. Thus, our data showed that the TFE3-RCC cells acquired chemoresistance through HMOX1 expression and that inhibition of HMOX1 by Chb16 may be an effective therapeutic strategy for TFE3-RCC.

Chameleon TFE3-translocation RCC and How Gene Partners Can Change Morphology: Accurate Diagnosis Using Contemporary Modalities

Translocation renal cell carcinoma (tRCC) with TFE3 gene rearrangements has been born as a distinct entity 20 years ago. These relatively rare tumors were notable among other RCC subtypes because of their disproportionally high incidence among children and young adults. Initial reports were focused on describing unifying morphologic criteria and typical clinical presentation. Follow-up studies of ancillary immunohistochemical and hybridization techniques provided additional diagnostic tools allowing recognition of tRCC tumors in practice. However, a growing body of literature also expanded the clinicomorphologic spectrum of tRCCs, to include a significant morphologic overlap with other RCC variants thus blurring the diagnostic clarity of this entity. More recent molecular studies utilizing next-generation sequencing technology accelerated recognition of numerous novel gene partners fusing at different breakpoints with the TFE3 gene. Accumulating data indicates that morphologic and clinical heterogeneity of tRCC could be explained by fusion subtypes, and knowledge of TFE3 partnering genes may be important in predicting tumor behavior. Herein we provided a comprehensive analysis of ∼400 tRCC cases with known TFE3 fusion partners, estimated their relative incidence and summarized clinicomorphologic features associated with most common fusion subtypes. Our data was based on an extensive literature review and had a special focus on comparing immunohistochemistry, fluorescent in situ hybridization and contemporary molecular studies for the accurate diagnosis of tRCC.

Both SUMOylation and ubiquitination of TFE3 fusion protein regulated by androgen receptor are the potential target in the therapy of Xp11.2 translocation renal cell carcinoma

Background

The aggressiveness of renal cell carcinoma (RCC) associated with Xp11.2 translocation/TFE3 gene fusion (Xp11.2 translocation RCC [Xp11.2 tRCC]) is age‐dependent, which is similar to the overall trend of reproductive endocrine hormones. Therefore, this study focused on the effect and potential mechanism of androgen and androgen receptor (AR) on the progression of Xp11.2 tRCC.

Methods

The effects of androgen and AR on the proliferation and migration of Xp11.2 tRCC cells were first evaluated utilising Xp11.2 tRCC cell lines and tissues. Because Transcription factor enhancer 3 (TFE3) fusion proteins play a key role in Xp11.2 tRCC, we focused on the regulatory role of AR and TFE3 expression and transcriptional activity.

Results

When Xp11.2 tRCC cells were treated with dihydrotestosterone, increased cell proliferation, invasion and migration were observed. Compared with clear cell RCC, the positive rate of AR in Xp11.2 tRCC tissues was higher, and its expression was negatively associated with the progression‐free survival of Xp11.2 tRCC. Further studies revealed that AR could positively regulate the transcriptional activity of TFE3 fusion proteins by small ubiquitin‐related modifier (SUMO)‐specific protease 1, inducing the deSUMOylation of TFE3 fusion. On the other hand, UCHL1 negatively regulated by AR plays a role in the deubiquitination degradation of the PRCC‐TFE3 fusion protein. Therefore, the combination of the AR inhibitor MDV3100 and the UCHL1 inhibitor 6RK73 was effective in delaying the progression of Xp11.2 tRCC, especially PRCC‐TFE3 tRCC.

Conclusions

Androgen and AR function as facilitators in Xp11.2 tRCC progression and may be a novel therapeutic target for Xp11.2 tRCC.

The combined use of AR antagonist MDV3100 and UCHL1 inhibitor 6RK73 increased both the SUMOylation and ubiquitination of the PRCC‐TFE3 fusion protein

Up-regulation of NMRK2 mediated by TFE3 fusions is the key for energy metabolism adaption of Xp11.2 translocation renal cell carcinoma

Due to the inadequate awareness of Xp11.2 translocation renal cell carcinoma (Xp11.2 tRCC), its metabolic features have not been described. Here, by using nontargeted LC-MS-based metabolomics, we found that the chimeric TFE3 protein, the major oncogenic driver in Xp11.2 tRCC, regulated the metabolic pathways in Xp11.2 tRCC, including glycerophospholipid metabolism, purine metabolism, amino acid metabolism, fatty acid metabolism and energy metabolism. Combined with our present metabolomic data and previous studies, it was found that Xp11.2 tRCC preferred mitochondrial respiration, which was obviously different from renal clear cell carcinoma (ccRCC). Furthermore, by using bioinformatics and data mining, NMRK2, an important target for energy metabolism adaptation of Xp11.2 tRCC, was identified. Additionally, we confirmed that chimeric TFE3 could transcriptionally activate the expression of NMRK2, but the NONO-TFE3 fusion, which lacks the activation domain encoded by exons 4-5 of the TFE3 gene, functioned as a transcription factor by recruiting TFEB. When NMRK2 was knocked down, the mitochondrial respiration of Xp11.2 tRCC, rather than glycolysis, was significantly weakened. Therefore, the present study revealed the mechanism of the energy metabolism adaptation by which the TFE3 fusion promotes mitochondrial respiration by upregulating NMRK2 in Xp11.2 tRCC.

Integrative clinical and molecular characterization of translocation renal cell carcinoma

Translocation renal cell carcinoma (tRCC) is a poorly characterized subtype of kidney cancer driven by MiT/TFE gene fusions. Here, we define the landmarks of tRCC through an integrative analysis of 152 patients with tRCC identified across genomic, clinical trial, and retrospective cohorts. Most tRCCs harbor few somatic alterations apart from MiT/TFE fusions and homozygous deletions at chromosome 9p21.3 (19.2% of cases). Transcriptionally, tRCCs display a heightened NRF2-driven antioxidant response that is associated with resistance to targeted therapies. Consistently, we find that outcomes for patients with tRCC treated with vascular endothelial growth factor receptor inhibitors (VEGFR-TKIs) are worse than those treated with immune checkpoint inhibitors (ICI). Using multiparametric immunofluorescence, we find that the tumors are infiltrated with CD8+ T cells, though the T cells harbor an exhaustion immunophenotype distinct from that of clear cell RCC. Our findings comprehensively define the clinical and molecular features of tRCC and may inspire new therapeutic hypotheses.

TFE3 and TFEB-rearranged renal cell carcinomas: an immunohistochemical panel to differentiate from common renal cell neoplasms

TFE3/TFEB-rearranged renal cell carcinomas are characterized by translocations involving TFE3 and TFEB genes. Despite the initial description of typical morphology, their histological spectrum is wide, mimicking common subtypes of renal cell tumors. Thus, the diagnosis is challenging requiring the demonstration of the gene rearrangement, usually by FISH. However, this technique is limited in most laboratories and immunohistochemical TFE3/TFEB analysis is inconsistent. We sought to identify a useful immunohistochemical panel using the most common available markers to recognize those tumors. We performed an immunohistochemical panel comparing 27 TFE3-rearranged and 10 TFEB-rearranged renal cell carcinomas to the most common renal cell tumors (150 clear cell, 100 papillary, 50 chromophobe renal cell carcinomas, 18 clear cell papillary renal cell tumors, and 50 oncocytomas). When dealing with neoplasms characterized by cells with clear cytoplasm, CA9 is a helpful marker to exclude clear cell renal cell carcinoma. GATA3, AMACR, and CK7 are useful to rule out clear cell papillary renal cell tumor. CK7 is negative in TFE3/TFEB-rearranged renal cell carcinoma and positive in papillary renal cell carcinoma, being therefore useful in this setting. Parvalbumin and CK7/S100A1 respectively are of paramount importance when TFE3/TFEB-rearranged renal cell carcinoma resembles oncocytoma and chromophobe renal cell carcinoma. Moreover, in TFEB-rearranged renal cell carcinoma, cathepsin K and melanogenesis markers are constantly positive, whereas TFE3-rearranged renal cell carcinoma stains for cathepsin K in roughly half of the cases, HMB45 in 8% and Melan-A in 22%. In conclusion, since TFE3/TFEB-rearranged renal cell carcinoma may mimic several histotypes, an immunohistochemical panel to differentiate them from common renal cell tumors should include cathepsin K, CA9, CK7, and parvalbumin.

Translocation carcinomas of the kidney

The MiT subfamily of transcription factors includes TFE3, TFEB, TFEC, and MITF. Gene fusions involving two of these transcription factors have been well-characterized in renal cell carcinoma (RCC). The TFE3-rearranged RCC (also known as Xp11 translocation RCC) was first officially recognized in the 2004 World Health Organization (WHO) renal tumor classification. The TFEB-rearranged RCC, which typically harbor a t(6;11)(p21;q12) translocation which results in a MALAT1-TFEB gene fusion, were first officially recognized in the 2016 WHO renal tumor classification. These two subtypes of translocation RCC have many similarities. Both disproportionately involve young patients, although adult translocation RCC overall outnumber pediatric cases. Both often have unusual and distinctive morphologies; the TFE3-rearranged RCCs frequently have clear cells with papillary architecture and abundant psammoma bodies, while the TFEB-rearranged RCCs frequently have a biphasic appearance with both small and large epithelioid cells and nodules of basement membrane material. However, the morphology of these two neoplasms can overlap, with one mimicking the other or other more common renal neoplasms. Both of these RCC underexpress epithelial immunohistochemical markers, such as cytokeratin and epithelial membrane antigen, relative to most other RCC. Unlike other RCC, both frequently express the cysteine protease cathepsin k and often express melanocytic markers like HMB45 and Melan A. Finally, TFE3 and TFEB have overlapping functional activity as these two transcription factors frequently heterodimerize and bind to the same targets. Therefore, these two neoplasms are now grouped together under the heading of "MiT family translocation RCC." Approximately 50 renal cell carcinomas with gene fusions involving the anaplastic lymphoma kinase (ALK) gene have now been reported. While those with a Vinculin-ALK fusion have distinctive features (predilection to affect children with sickle cell trait and to show solid architecture with striking cytoplasmic vacuolization), other ALK-fusion RCCs have more varied clinical presentations and pathologic features. This review summarizes our current knowledge of these recently described RCC.

TSC2 regulates lysosome biogenesis via a non-canonical RAGC and TFEB-dependent mechanism

Tuberous Sclerosis Complex (TSC) is caused by TSC1 or TSC2 mutations, resulting in hyperactivation of the mechanistic target of rapamycin complex 1 (mTORC1). Transcription factor EB (TFEB), a master regulator of lysosome biogenesis, is negatively regulated by mTORC1 through a RAG GTPase-dependent phosphorylation. Here we show that lysosomal biogenesis is increased in TSC-associated renal tumors, pulmonary lymphangioleiomyomatosis, kidneys from Tsc2^+/- mice, and TSC1/2-deficient cells via a TFEB-dependent mechanism. Interestingly, in TSC1/2-deficient cells, TFEB is hypo-phosphorylated at mTORC1-dependent sites, indicating that mTORC1 is unable to phosphorylate TFEB in the absence of the TSC1/2 complex. Importantly, overexpression of folliculin (FLCN), a GTPase activating protein for RAGC, increases TFEB phosphorylation at the mTORC1 sites in TSC2-deficient cells. Overexpression of constitutively active RAGC is sufficient to relocalize TFEB to the cytoplasm. These findings establish the TSC proteins as critical regulators of lysosomal biogenesis via TFEB and RAGC and identify TFEB as a driver of the proliferation of TSC2-deficient cells.

New developments in existing WHO entities and evolving molecular concepts: The Genitourinary Pathology Society (GUPS) update on renal neoplasia

The Genitourinary Pathology Society (GUPS) reviewed recent advances in renal neoplasia, particularly post-2016 World Health Organization (WHO) classification, to provide an update on existing entities, including diagnostic criteria, molecular correlates, and updated nomenclature. Key prognostic features for clear cell renal cell carcinoma (RCC) remain WHO/ISUP grade, AJCC/pTNM stage, coagulative necrosis, and rhabdoid and sarcomatoid differentiation. Accrual of subclonal genetic alterations in clear cell RCC including SETD2, PBRM1, BAP1, loss of chromosome 14q and 9p are associated with variable prognosis, patterns of metastasis, and vulnerability to therapies. Recent National Comprehensive Cancer Network (NCCN) guidelines increasingly adopt immunotherapeutic agents in advanced RCC, including RCC with rhabdoid and sarcomatoid changes. Papillary RCC subtyping is no longer recommended, as WHO/ISUP grade and tumor architecture better predict outcome. New papillary RCC variants/patterns include biphasic, solid, Warthin-like, and papillary renal neoplasm with reverse polarity. For tumors with 'borderline' features between oncocytoma and chromophobe RCC, a term "oncocytic renal neoplasm of low malignant potential, not further classified" is proposed. Clear cell papillary RCC may warrant reclassification as a tumor of low malignant potential. Tubulocystic RCC should only be diagnosed when morphologically pure. MiTF family translocation RCCs exhibit varied morphologic patterns and fusion partners. TFEB-amplified RCC occurs in older patients and is associated with more aggressive behavior. Acquired cystic disease (ACD) RCC-like cysts are likely precursors of ACD-RCC. The diagnosis of renal medullary carcinoma requires a negative SMARCB1 (INI-1) expression and sickle cell trait/disease. Mucinous tubular and spindle cell carcinoma (MTSCC) can be distinguished from papillary RCC with overlapping morphology by losses of chromosomes 1, 4, 6, 8, 9, 13, 14, 15, and 22. MTSCC with adverse histologic features shows frequent CDKN2A/2B (9p) deletions. BRAF mutations unify the metanephric family of tumors. The term "fumarate hydratase deficient RCC" ("FH-deficient RCC") is preferred over "hereditary leiomyomatosis and RCC syndrome-associated RCC". A low threshold for FH, 2SC, and SDHB immunohistochemistry is recommended in difficult to classify RCCs, particularly those with eosinophilic morphology, occurring in younger patients. Current evidence does not support existence of a unique tumor subtype occurring after chemotherapy/radiation in early childhood.

Renal cell carcinoma associated with Xp11.2 translocation/transcription factor E3 gene fusion: an adult case report and literature review

Renal cell carcinoma (RCC) associated with Xp11.2 translocation/transcription factor E3 (TFE3) gene fusion is a rare and independent subtype of RCC included in the classification of MiT (microphthalmia-associated transcriptional factor) family translocation RCC. Herein, we report an adult case of Xp11.2 translocation RCC, and review the relevant literature to improve our understanding of the pathogenesis, epidemiology, clinical manifestations, diagnosis, differential diagnosis, treatment, and other aspects of the disease.

Nuclear translocation of ASPL-TFE3 fusion protein creates favorable metabolism by mediating autophagy in translocation renal cell carcinoma

The ASPL-TFE3 fusion gene, resulting from t(X;17)(p11.2;q25.3), is one of the most commonly identified fusion genes in Xp11 translocation renal cell carcinoma (tRCC). However, its roles and underlying mechanism in RCC development are not yet clear. Here, we identified ASPL-TFE3 fusion as the most common tRCC subtype in a Chinese population (29/126, 23.03%). This fusion protein translocated into the nucleus and promoted RCC cell proliferation both in vitro and in vivo. Mechanistically, the fusion protein transcriptionally activated the lysosome-autophagy pathway by binding to the promoters of lysosome-related genes. Autophagy, activated by ASPL-TFE3, enabled RCC cells to escape energy stress by promoting the utilization of proteins and lipids. Moreover, we found that the ASPL-TFE3 fusion escaped regulation by the classic mTOR-TFE3 signal and instead activated phospho-mTOR and its downstream targets. Finally, targeting both autophagy and the mTOR axis resulted in a greater antiproliferative effect than single pathway inhibition. In summary, these results confirmed the ASPL-TFE3 fusion as a master regulator of metabolic adaptation mediated by autophagy in tRCC. The simultaneous manipulation of autophagy and the mTOR axis may represent a novel treatment strategy for ASPL-TFE3 fusion RCC.

NONO-TFE3 fusion promotes aerobic glycolysis and angiogenesis by targeting HIF1A in NONO-TFE3 translocation renal cell carcinoma

BACKGROUND

NONO-TFE3 translocation renal cell carcinoma (tRCC), one of RCCs associated with Xp11.2 translocation/TFE3 gene fusion (Xp11.2 tRCCs), involves an X chromosome inversion between NONO and TFE3 with the characteristics of endonuclear aggregation of NONO-TFE3 fusion protein. Nowadays, the oncogenic mechanisms of NONO-TFE3 fusion have not been fully elucidated.

OBJECTIVE

This study aimed at investigating the mechanism of NONO-TFE3 fusion regulating HIF1A as well as the role of HIF-1α in the progression of NONO-TFE3 tRCC under hypoxia.

METHODS

Immunohistochemistry and Western Blotting assays were performed to profile HIF-1α expression in renal clear cell carcinoma (ccRCC) or in Xp11.2 tRCC. Chromatin immunoprecipitation (ChIP), luciferase reporter assay and real-time quantitative PCR (RT-qPCR) were used to evaluate the regulation of HIF1A expression by NONO-TFE3 fusion. Then, flow cytometry analysis, tube formation assays and cell migration assays were used as well as glucose or lactic acid levels were measured to establish the impact of HIF-1α on the progression of NONO-TFE3 tRCC. Besides, the effect of HIF-1α inhibitor (PX-478) on UOK109 cells was analyzed.

RESULTS

We found that HIF1A was targeting gene of NONO-TFE3 fusion. In UOK109 cells, which were isolated from NONO-TFE3 tRCC samples, NONO-TFE3 fusion promoted aerobic glycolysis and angiogenesis by up-regulating the expression of HIF-1α under hypoxia. Furthermore, inhibition of HIF-1α mediated by PX-478 suppressed the development of NONO-TFE3 tRCC under hypoxia.

CONCLUSION

HIF-1α is a potential target for therapy of NONO-TFE3 tRCC under hypoxia.

Low expression of TRAF3IP2-AS1 promotes progression of NONO-TFE3 translocation renal cell carcinoma by stimulating N6-methyladenosine of PARP1 mRNA and downregulating PTEN

Background

NONO-TFE3 translocation renal cell carcinoma (NONO-TFE3 tRCC) is one subtype of RCCs associated with Xp11.2 translocation/TFE3 gene fusions RCC (Xp11.2 tRCCs). Long non-coding RNA (lncRNA) has attracted great attention in cancer research. The function and mechanisms of TRAF3IP2 antisense RNA 1 (TRAF3IP2-AS1), a natural antisense lncRNA, in NONO-TFE3 tRCC remain poorly understood.

Methods

FISH and qRT-PCR were undertaken to study the expression, localization and clinical significance of TRAF3IP2-AS1 in Xp11.2 tRCC tissues and cells. The functions of TRAF3IP2-AS1 in tRCC were investigated by proliferation analysis, EdU staining, colony and sphere formation assay, Transwell assay and apoptosis analysis. The regulatory mechanisms among TRAF3IP2-AS1, PARP1, PTEN and miR-200a-3p/153-3p/141-3p were investigated by luciferase assay, RNA immunoprecipitation, Western blot and immunohistochemistry.

Results

The expression of TRAF3IP2-AS1 was suppressed by NONO-TFE3 fusion in NONO-TFE3 tRCC tissues and cells. Overexpression of TRAF3IP2-AS1 inhibited the proliferation, migration and invasion of UOK109 cells which were derived from cancer tissue of patient with NONO-TFE3 tRCC. Mechanistic studies revealed that TRAF3IP2-AS1 accelerated the decay of PARP1 mRNA by direct binding and recruitment of N⁶-methyladenosie methyltransferase complex. Meanwhile, TRAF3IP2-AS1 competitively bound to miR-200a-3p/153-3p/141-3p and prevented those from decreasing the level of PTEN.

Conclusions

TRAF3IP2-AS1 functions as a tumor suppressor in NONO-TFE3 tRCC progression and may serve as a novel target for NONO-TFE3 tRCC therapy. TRAF3IP2-AS1 expression has the potential to serve as a novel diagnostic and prognostic biomarker for NONO-TFE3 tRCC detection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13045-021-01059-5.

Molecular Heterogeneity of Xp11.2 Translocation Renal Cell Carcinoma: The Correlation Between Split Signal Pattern in FISH and Prognosis

PURPOSE

Xp11.2 translocation renal cell carcinoma (Xp11.2 tRCC) is a distinct subtype of renal cell carcinoma (RCC) characterized by chromosomal translocations involving TFE3 gene. TFE3 break-apart fluorescence in situ hybridization (FISH) assay is an effective tool to diagnose Xp11.2 tRCC. The aim of this study is to evaluate the correlation between split signal pattern in FISH and the clinicopathological characteristics of Xp11.2 tRCC.

PATIENTS AND METHODS

We reviewed 2037 RCC patients who underwent partial nephrectomy or radical nephrectomy from January 2007 to March 2020 in our institution. Forty-nine cases were diagnosed as Xp11.2 tRCC and their split signal patterns were evaluated. X-tile software was used to determine the optimal cut-off value of the percentage of split signal in FISH. Kaplan-Meier analysis and Cox regression analysis were performed to assess the relationship between signal pattern of FISH and the prognosis.

RESULTS

Among the 49 patients, 13 patients and 36 patients were classified into high and low split signal group, respectively. Nine cases showed extra amplification signal pattern and 40 cases showed typical translocation signal pattern. Multivariate analysis demonstrated that high percentage of split signal and amplification signal pattern were the independent predictors for progression-free survival (PFS) whereas only pT stage was associated independently with overall survival (OS).

CONCLUSION

Xp11.2 tRCC cases with high percentage of split signals or amplification signal pattern may have a worse outcome, and the two indicators need to be highlighted in clinical practice.

The positive regulation loop between NRF1 and NONO-TFE3 fusion promotes phase separation and aggregation of NONO-TFE3 in NONO-TFE3 tRCC

TFE3 gene fusions often place TFE3 under the control of a more active promoter and cause overexpression of the TFE3 proteins in renal cell carcinoma associated with Xp11.2 translocations (Xp11.2 tRCC). The purpose of this study was to investigate the transcriptional regulation and aggregation mechanism of NONO-TFE3 in NONO-TFE3 tRCC. In this study, we found that the nuclear aggregation of NONO-TFE3 fusion was significantly more than that of intact TFE3 or PRCC-TFE3 fusion. We observed that NONO fragment mediated-phase separation promoted stabilization and aggregation of NONO-TFE3 fusion. Meantime, we revealed that the positive regulation loop between NONO-TFE3 and NRF1 increased mitochondrial biosynthesis and metabolism in NONO-TFE3 tRCC. Therefore, the present study raises the possibility that mitochondrial metabolism is potentially a fruitful arena for NONO-TFE3 tRCC therapy.

Morphologic and Immunohistochemical Characteristics of Fluorescent In Situ Hybridization Confirmed TFE3-Gene Fusion Associated Renal Cell Carcinoma: A Single Institutional Cohort

TFE3-fusion associated renal cell carcinoma (TFE3-RCC) accounts for up to 5% adults and 40% of childhood RCC. Their comprehensive immunohistochemical (IHC) profile in correlation to fluorescence in situ hybridization (FISH) testing and their role in the diagnostic approach are not well documented because of lacking published data. FISH confirmed TFE3-RCC between years 2010 and 2020 were identified from institutional electronic database and retrospectively reviewed. Eighty-five TFE3-RCC were identified. Seventy-six of 85 (89.4%) TFE3-RCC cases had positive TFE3 expression, with diffuse and strong/moderate TFE3 expression in 45 (54.2%). Three (3.5%) TFE3-RCC had negative TFE3 expression whereas 6 (7%) cases had equivocal TFE3 expression. On the other hand, positive TFE3-IHC expression was observed in 17/29 (58.6%) TFE3-FISH negative RCC cases, although only 8 (27.5%) had diffuse and moderate/strong TFE3 expression. Diffuse and strong TFE3-IHC expression was statistically significant in predicting TFE3-FISH positivity (P<0.0001) regardless of morphologic features. After univariate and multivariate analyses, TFE3-IHC was the only parameter with significant predictive value for detecting positive TFE3-FISH (P<0.0001). On univariate analysis, sex, classic morphology, age, negative AE1/AE3 or cytokeratin 7 were not predictive of TFE3-FISH positivity. Diffuse and strong nuclear TFE3-IHC expression is significantly associated with TFE3-FISH positivity and can be used as a surrogate marker to confirm translocation associated cases. TFE3-rearranged RCCs show variable histomorphologic features and TFE3-FISH should be performed in cases presenting at a younger age or, regardless of the age, tumors with unusual morphology. Despite previous reports, negative pancytokeratin and positive cathepsin K expression may not be reliable markers for TFE3-RCC.

Contributions of genetics to the evolution of the diagnostic classification of renal cell neoplasia: a personal perspective

The classification system for neoplasms of the cells lining the renal tubules (renal cell neoplasms) has expanded greatly over the last five decades. The criteria for recognising an entity and including it in the classification have changed from being purely morphological and clinical to include genetics; presently, some are defined purely on genetics. Expansion of the number of entities included in the classification has many of the newly included entities and those under consideration for inclusion being very rare. The clinical utility of including entities which are extremely rare, based mainly upon genetic information, is unclear.

The suitability of NONO-TFE3 dual-fusion FISH assay as a diagnostic tool for NONO-TFE3 renal cell carcinoma

NONO-TFE3 RCC is a subtype of Xp11.2 translocation renal cell carcinoma (RCC). So far, only a small amount of NONO-TFE3 RCC have been reported owing to lack of effective diagnosis methods. Utilizing the novel dual-fusion fluorescence in situ hybridization (FISH) probe reported here, 5 cases of NONO-TFE3 RCC were identified and were ultimately confirmed by RT-PCR. Histopathology, all 5 cases were consisted by sheets of epithelial cells and papillary architecture. The cytoplasm was abundantly clear, and nucleoli was not prominent. Besides, the nuclear palisading, subnuclear vacuoles and psammoma bodies were identified. The most distinctive features were strong positive TFE3 staining but equivocal split signals of the TFE3 probe, which might lead to the misdiagnosis of Xp11.2 translocation RCC. The median age and median tumor size of the five patients were 41.2 years and 3.6 cm, respectively. A median following follow-up of 27 months showed moderate disease progression and prognosis in NONO-TFE3 RCC patients. In conclusion, the present study demonstrates the effectiveness and reliability of the NONO-TFE3 dual-fusion FISH probe for diagnosing NONO-TFE3 RCC. Suspected cases of Xp11.2 translocation RCC showing biphasic pattern, strong positive TFE3 staining, and equivocal split signals in the TFE3 FISH assay indicated a possibility of NONO-TFE3 RCC.

Autophagy and liver cancer

Autophagy is a highly conserved catabolic process that degrades cytosolic proteins and organelles via formation of autophagosomes that fuse with lysosomes to form autolysosomes, whereby autophagic cargos are degraded. Numerous studies have demonstrated that autophagy plays a critical role in the regulation of liver physiology and homeostasis, and impaired autophagy leads to the pathogenesis of various liver diseases such as viral hepatitis, alcohol associated liver diseases (AALD), non-alcoholic fatty liver diseases (NAFLD), and liver cancer. Recent evidence indicates that autophagy may play a dual role in liver cancer: inhibiting early tumor initiation while promoting progression and malignancy of already formed liver tumors. In this review, we summarized the progress of current understanding of how hepatic viral infection, alcohol consumption and diet-induced fatty liver diseases impair hepatic autophagy. We also discussed how impaired autophagy promotes liver tumorigenesis, and paradoxically how autophagy is required to promote the malignancy and progression of liver cancer. Understanding the molecular mechanisms underlying how autophagy differentially affects liver cancer development and progression may help to design better therapeutic strategies for prevention and treatment of liver cancer.

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.

User guide to MiT-TFE isoforms and post-translational modifications

The microphthalmia-associated transcription factor (MITF) is at the core of melanocyte and melanoma fate specification. The related factors TFEB and TFE3 have been shown to be instrumental for transcriptional regulation of genes involved in lysosome biogenesis and autophagy, cellular processes important for mediating nutrition signals and recycling of cellular materials, in many cell types. The MITF, TFEB, TFE3, and TFEC proteins are highly related. They share many structural and functional features and are targeted by the same signaling pathways. However, the existence of several isoforms of each factor and the increasing number of residues shown to be post-translationally modified by various signaling pathways poses a difficulty in indexing amino acid residues in different isoforms across the different proteins. Here, we provide a resource manual to cross-reference amino acids and post-translational modifications in all isoforms of the MiT-TFE family in humans, mice, and zebrafish and summarize the protein accession numbers for each isoform of these factors in the different genomic databases. This will facilitate future studies on the signaling pathways that regulate different isoforms of the MiT-TFE transcription factor family.

Dual role of G-quadruplex in translocation renal cell carcinoma: Exploring plausible Cancer therapeutic innovation

BACKGROUND

Renal Cell Carcinoma (RCC) is the ninth leading cause of death among kidney cancer. Xp11.2 translocation harboring TFE3 fusion proteins, act as an oncogene in translocation cancers that constitute the hallmark of translocation renal cell carcinoma (tRCC). G-quadruplex (G4), an alternative nucleic acid structure is an emerging and promising factor in cancer. The presence of G4 within the genome plays a pioneering role in cancer as it contributes to genomic aberration as well as inhibition in cell proliferation.

SCOPE OF REVIEW

Here we discuss the link between G4 and tRCC. We compile the available information of G-quadruplex & propose their dual role in tRCC, suggesting both stabilization and destabilization of G-quadruplex could be considered targets for tRCC.

MAJOR CONCLUSIONS

Our in Silico analysis of TFE3 and their three fusions partner's PRCC, SFPQ, and ASPSCR1 discloses a few putative G4 forming sequences (PQS) in their corresponding fusion gene or fusion transcript. Stabilization of G4 structure within fusion gene/transcript can be of great use towards potential therapeutics targeting fusion protein derived oncogenesis, as G4 is a serious menace for DNA polymerization, transcription & translation. G-quadruplex at intron-2 of the TFE3 has been reported to mediate its translocation also. Both stabilization and destabilization of the G4 structure would be a promising approach in the suppression of cancerous cell proliferation.

GENERAL SIGNIFICANCE

Pioneering studies discovered the relevance of G4 in cancer therapy and explore our approaches towards therapeutic innovation against oncogenic fusion protein and tRCC. Selectively targeting G4 in oncogenic fusion transcript will emerge as potential druggable structures.

Clinicopathologic and Molecular Analysis of the TFEB Fusion Variant Reveals New Members of TFEB Translocation Renal Cell Carcinomas (RCCs): Expanding the Genomic Spectrum

Xp11 renal cell carcinoma (RCC) with different gene fusions may have different clinicopathologic features. We sought to identify variant fusions in TFEB translocation RCC. A total of 31 cases of TFEB RCCs were selected for the current study; MALAT1-TFEB fusion was identified in 25 cases (81%, 25/31) using fusion probes. The remaining 6 cases (19%, 6/31) were further analyzed by RNA sequencing and 5 of them were detected with TFEB-associated gene fusions, including 2 ACTB-TFEB, 1 EWSR1-TFEB, 1 CLTC-TFEB, and 1 potential PPP1R10-TFEB (a paracentric inversion of the TFEB gene, consistent with "negative" TFEB split FISH result, and advising a potential diagnostic pitfall in detecting TFEB gene rearrangement). Four of the 5 fusion transcripts were successfully validated by reverse transcription-polymerase chain reaction and Sanger sequencing. Morphologically, approximately one third (29%, 9/31) of TFEB RCCs showed typical biphasic morphology. The remaining two thirds of the cases (71%, 22/31) exhibited nonspecific morphology, with nested, sheet-like, or papillary architecture, resembling other types of renal neoplasms, such as clear cell RCC, Xp11 RCC, perivascular epithelioid cell tumor (PEComa), or papillary RCC. Although cases bearing a MALAT1-TFEB fusion demonstrated variable morphologies, all 9 cases featuring typical biphasic morphology were associated with MALAT1-TFEB genotype. Accordingly, typical biphasic morphology suggests MALAT1-TFEB fusion, whereas atypical morphology did not suggest the specific type of fusion. Isolated or clustered eosinophilic cells were a common feature in TFEB RCCs, which may be a useful morphology diagnostic clue for TFEB RCCs. Clinicopathologic variables assessment showed that necrosis was the only morphologic feature that correlated with the aggressive behavior of TFEB RCC (P=0.004). In summary, our study expands the genomic spectrum and the clinicopathologic features of TFEB RCCs, and highlights the challenges of diagnosis and the importance of subtyping of this tumor by combining morphology and multiple molecular techniques.