MiT family translocation renal cell carcinomas: A 15th anniversary update

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.

Contrast-Enhanced Ultrasound Features of Adult Xp11.2 Translocation Renal Cell Carcinoma: Differential Diagnosis With Three Main Renal Cell Carcinoma Subtypes

OBJECTIVES

To investigate the sonographic features in Xp11.2 translocation renal cell carcinoma (Xp11.2 tRCC) using both conventional ultrasound (US) and contrast-enhanced US (CEUS) and evaluate the usefulness of sonographic imaging characteristics to differentiate between Xp11.2 tRCC and the three common RCC subtypes.

METHODS

Thirty-four adult Xp11.2 tRCC patients who preoperatively underwent both conventional US and CEUS and had solitary renal lesions and pathological confirmation after surgery were enrolled. Control matched patients included 131 with clear cell RCC (ccRCC), 48 with papillary RCC (pRCC), and 35 with chromophobe RCC (chRCC). Conventional US and CEUS data of all patients were retrospectively analyzed and compared.

RESULTS

Xp11.2 tRCC was more common in young women. The echogenicity of Xp11.2 tRCC lesions was hypo- and isoechoic relative to the adjacent renal cortex. A higher frequency of calcification within tumors was detected in Xp11.2 tRCC, but the presence of color flow signal (26.5%, 9/34) was much lower. Regarding CEUS features relative to the adjacent renal cortex, synchronous wash-in (61.8%, 21/34), iso-enhancement at peak (55.9%, 19/34), and fast wash-out (50.0%, 17/34) were more common in Xp11.2 tRCC. Moreover, an integrated variables model based on these features could differentiate Xp11.2 tRCC from ccRCC, pRCC, and chRCC (area under the curve, sensitivity, and specificity: 0.934, 92.0%, and 86.0%; 0.907, 88.0%, and 87.0%; and 0.808, 65.0%, and 99.0%, respectively).

CONCLUSIONS

Combining conventional US and CEUS lesion features with clinical information may provide a feasible and effective method to differentiate Xp11.2 tRCC from ccRCC, pRCC, and chRCC.

Xp11.2 Translocation Renal Cell Carcinoma With TFE3 Rearrangement: Distinct Morphological Features and Prognosis With Different Fusion Partners

Background

Renal cell carcinoma (RCC) associated with Xp11.2 translocation/TFE3 gene fusion is a rare and new subtype of RCC and was classified by the WHO in 2004. Since then, multiple 5′ fusion partners for TFE3 have been reported; however, the impact of individual fusion variant on specific clinicopathologic features of Xp11.2 RCCs has not been well defined.

Methods

Four Xp11.2 translocation RCCs were identified by morphological, immunostaining, and fluorescence in situ hybridization (FISH) assays from 200 patients who attended Guangdong General Hospital between January 2017 and January 2020. All these four cases were further analyzed by RNA sequencing to explore their TFE3 gene fusion partners. The clinicopathologic features, including clinical manifestations, pathological findings, treatment strategies, clinical outcomes, and follow-up information on Xp11.2 translocation RCCs, were recorded and evaluated.

Results

These four cases affected one male and three females. The median age was 13 years at the time of diagnosis (range = 4–20 years). All the examined tumors were unilateral and unifocal. The largest diameter of these tumors ranged from 2.0 to 10.0 cm, and the average was 5.55 cm. Regional lymph node or distant metastasis developed in two patients. Three cases demonstrated known fusions: ASPCR1–TFE3 (two cases) and PRCC–TFE3 (one case). However, one case showed an unreported VCP–TFE3 fusion gene in Xp11.2 translocation RCCs. Immunohistochemistry results revealed tumor cells diffusely positive for TFE3, but have no consistency in other markers. Moreover, there were different clinical prognoses among the different variant TFE3 rearrangements; RCC patients with VCP–TFE3 translocation had worse prognosis compared to those with other fusion types. Follow-up were available for all the patients and ranged from 3 to 36 months. Three patients were without evidence of disease progression, while that with VCP–TFE3 fusion died of the disease 3 months after the diagnosis.

Conclusion

In conclusion, our data expand the list of TFE3 gene fusion partners and the clinicopathologic features of Xp11.2 RCCs with specific TFE3 gene fusions. We identified a novel VCP–TFE3 fusion in Xp11.2 translocation RCCs for the first time, which has unique morphology and worse prognosis than those with other variant TFE3 rearrangements. Integration of morphological, immunohistochemical, and molecular methods is often necessary for the precise diagnosis and optimal clinical management of malignant tumors.

Autophagy in Xp11 translocation renal cell carcinoma: from bench to bedside

Xp11 translocation renal cell carcinoma (tRCC) characterized by the rearrangement of the TFE3 is recently identified as a unique subtype of RCC that urgently requires effective prevention and treatment strategies. Therefore, determining suitable therapeutic targets and fully understanding the biological significance of tRCC is essential. The importance of autophagy is increasingly acknowledged because it shows carcinogenic activity or suppressor effect. Autophagy is a physiological cellular process critical to maintaining cell homeostasis, which is involved in the lysosomal degradation of cytoplasmic organelles and macromolecules via the lysosomal pathway, suggesting that targeting autophagy is a potential therapeutic approach for cancer therapies. However, the underlying mechanism of autophagy in tRCC is still ambiguous. In this review, we summarize the autophagy-related signaling pathways associated with tRCC. Moreover, we examine the roles of autophagy and the immune response in tumorigenesis and investigate how these factors interact to facilitate or prevent tumorigenesis. Besides, we review the findings regarding the treatment of tRCC via induction or inhibition of autophagy. Hopefully, this study will shed some light on the functions and implications of autophagy and emphasize its role as a potential molecular target for therapeutic intervention in tRCC.

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.

Comprehensive Characterization of Common and Cancer-Specific Differently Expressed lncRNAs in Urologic Cancers

Urologic cancers, comprising prostate carcinoma (PCa), renal cell carcinoma (RCC), and bladder carcinoma (BCa), were the commonly occurred carcinoma amid males. Long noncoding RNAs (lncRNAs) with the length of more than 200 nt functioned importantly in physiological and pathological advancement. Nevertheless, further investigation regarding lncRNA expression feature and function in urologic cancers should be essential. This study is aimed at uncovering the roles of the differently expressed lncRNAs in urologic cancers. The data of gene expression levels was downloaded from lncRNAtor datasets. The lncRNA expression pattern existing in different urologic cancers was assessed by hierarchical clustering analysis. Gene Ontology (GO) analysis and KEGG pathway analysis were separately applied to evaluate the biological function and process and the biological pathways involving differently expressed lncRNAs. Our results indicated that 18 lncRNA expressions were increased, and 16 lncRNA expressions were reduced in urologic cancers after comparison with that in normal tissues. Moreover, our results demonstrated 61, 422, 137, and 281 lncRNAs were specifically dysregulated in bladder cancer (BLCA), kidney renal clear cell cancer (KIRC), kidney renal papillary cell cancer (KIRP), and prostate adenocarcinoma (PRAD), respectively. Bioinformatics analysis showed that differently expressed lncRNAs displayed crucially in urologic cancers. The prognostic value of common and cancer-specific differently expressed lncRNAs, such as PVT1, in cancer outcomes, was emphasized here. Our research has deeply unearthed the mechanism of differently expressed lncRNAs in urologic cancers development.

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.

Optimal Management of First-Line Advanced Renal Cell Carcinoma: Focus on Pembrolizumab

Renal cell carcinoma (RCC) is among the 10 most common cancers in the USA. One-third of the patients diagnosed with this cancer present with locally advanced or metastatic disease. In the past, advanced disease conferred poor survival outcomes; however, the treatment paradigm for RCC has been revolutionized twice since 2005. The initial wave of revolution came with the emergence of vascular endothelial growth factor (VEGF) inhibitors and a second wave arose more recently with the emergence and unprecedented success of checkpoint inhibitors in RCC. A third wave combining these two strategies is well underway and likely represents the new paradigm to improve survival outcomes for afflicted patients. In this review, we discuss the current treatment landscape for patients with advanced RCC, focusing on approved VEGF and checkpoint inhibitors in the first-line setting as well as highlighting landmark combination clinical trials.

Renal Tumors of Childhood-A Histopathologic Pattern-Based Diagnostic Approach

Renal tumors comprise approximately 7% of all malignant pediatric tumors. This is a highly heterogeneous group of tumors, each with its own therapeutic management, outcome, and association with germline predispositions. Histopathology is the key in establishing the correct diagnosis, and therefore pathologists with expertise in pediatric oncology are needed for dealing with these rare tumors. While each tumor shows different histologic features, they do have considerable overlap in cell type and histologic pattern, making the diagnosis difficult to establish, if based on routine histology alone. To this end, ancillary techniques, such as immunohistochemistry and molecular analysis, can be of great importance for the correct diagnosis, resulting in appropriate treatment. To use ancillary techniques cost-effectively, we propose a pattern-based approach and provide recommendations to aid in deciding which panel of antibodies, supplemented by molecular characterization of a subset of genes, are required.

Molecular Genetics of Renal Cell Tumors: A Practical Diagnostic Approach

Renal epithelial cell tumors are composed of a heterogeneous group of tumors with variable morphologic, immunohistochemical, and molecular features. A "histo-molecular" approach is now an integral part of defining renal tumors, aiming to be clinically and therapeutically pertinent. Most renal epithelial tumors including the new and emerging entities have distinct molecular and genetic features which can be detected using various methods. Most renal epithelial tumors can be diagnosed easily based on pure histologic findings with or without immunohistochemical examination. Furthermore, molecular-genetic testing can be utilized to assist in arriving at an accurate diagnosis. In this review, we presented the most current knowledge concerning molecular-genetic aspects of renal epithelial neoplasms, which potentially can be used in daily diagnostic practice.