Characterization of renal cell carcinoma-associated constitutional chromosome abnormalities by genome sequencing

Mosaic Form of von Hippel-Lindau Syndrome: Case Report and Literature Review

von Hippel-Lindau syndrome (VHLS) is a hereditary cancer syndrome with CNS hemangioblastomas, clear cell renal carcinoma, pheochromocytoma, retinal angiomas, and a number of other manifestations. VHLS is caused by a mutation in the VHL gene and is inherited in an autosomal dominant manner. However, some cases of VHLS develop de novo, and among them, there are rare patients with a mosaic form of the disease. Genetic testing in mosaic patients is prone to false-negative results due to the low copy number of a mutant allele in DNA isolated from the blood. We describe a case of molecular genetic diagnostics of VHLS in a 39-year-old patient using various methods, including mutation analysis in asynchronous primary tumors and repeated DNA analysis from blood using NGS with high coverage for the mutant position. As a result, the patient was diagnosed with a mosaic form of VHLS caused by the variant c.481C>T (p.Arg161Ter), the proportion of which in the blood DNA was 2%. We also summarized the literature data on the mosaic form of VHLS: the severity of clinical manifestations, the features of differential diagnostics of VHLS with a negative result of routine molecular genetic VHL testing, and specific options of active surveillance and treatment for mutation carriers.

ERN GENTURIS clinical practice guidelines for the diagnosis, surveillance and management of people with Birt-Hogg-Dubé syndrome

Birt-Hogg-Dubé syndrome (BHD syndrome) is an autosomal dominant multisystem disorder with variable expression due to pathogenic constitutional variants in the FLCN gene. Patients with BHD syndrome are predisposed to benign cutaneous fibrofolliculomas/trichodischomas, pulmonary cysts with an associated risk of spontaneous pneumothorax, and renal cell carcinoma. A requirement for updated International consensus recommendations for the diagnosis and management of BHD syndrome was identified. Based on a comprehensive literature review and expert consensus within the fields of respiratory medicine, urology, radiology, dermatology, clinical oncology and clinical genetics, updated recommendations for diagnosis, surveillance and management in BHD syndrome were developed. With the widespread availability of FLCN genetic testing, clinical scenarios in which a diagnosis should be considered and criteria for genetic testing were defined. Following a clinical and/or molecular diagnosis of BHD syndrome, a multidisciplinary approach to disease management is required. Regular renal cancer surveillance is recommended in adulthood and life-long, but the evidence base for additional tumour surveillance is limited and further research warranted. Recommendations for the treatment of cutaneous, pulmonary and renal manifestations are provided. Awareness of BHD syndrome needs to be raised and better knowledge of the clinical settings in which the diagnosis should be considered should enable earlier diagnosis. Further details, including areas for future research topics are available at: https://www.genturis.eu/l=eng/Guidelines-and-pathways/Clinical-practice-guidelines.html .

Downregulation of praja2 restrains endocytosis and boosts tyrosine kinase receptors in kidney cancer

Clear cell renal cell carcinoma (ccRCC) is the most common kidney cancer in the adult population. Late diagnosis, resistance to therapeutics and recurrence of metastatic lesions account for the highest mortality rate among kidney cancer patients. Identifying novel biomarkers for early cancer detection and elucidating the mechanisms underlying ccRCC will provide clues to treat this aggressive malignant tumor. Here, we report that the ubiquitin ligase praja2 forms a complex with-and ubiquitylates the AP2 adapter complex, contributing to receptor endocytosis and clearance. In human RCC tissues and cells, downregulation of praja2 by oncogenic miRNAs (oncomiRs) and the proteasome markedly impairs endocytosis and clearance of the epidermal growth factor receptor (EGFR), and amplifies downstream mitogenic and proliferative signaling. Restoring praja2 levels in RCC cells downregulates EGFR, rewires cancer cell metabolism and ultimately inhibits tumor cell growth and metastasis. Accordingly, genetic ablation of praja2 in mice upregulates RTKs (i.e. EGFR and VEGFR) and induces epithelial and vascular alterations in the kidney tissue.In summary, our findings identify a regulatory loop between oncomiRs and the ubiquitin proteasome system that finely controls RTKs endocytosis and clearance, positively impacting mitogenic signaling and kidney cancer growth.

The prognostic value of RASGEF1A RNA expression and DNA methylation in cytogenetically normal acute myeloid leukemia

BACKGROUND

Acute myeloid leukemia (AML) is a significantly heterogeneous malignancy of the blood. Cytogenetic abnormalities are crucial for the prognosis of AML. However, since more than half of patients with AML are cytogenetically normal AML (CN-AML), predictive prognostic indicators need to be further refined. In recent years, gene abnormalities are considered to be strong prognostic factors of CN-AML, already having clinical significance for treatment. In addition, the relationship of methylation in some genes and AML prognosis predicting has been discovered. RASGEF1A is a guanine nucleotide exchange factors of Ras and widely expressed in brain tissue, bone marrow and 17 other tissues. RASGEF1A has been reported to be associated with a variety of malignant tumors, examples include Hirschsprung disease, renal cell carcinoma, breast cancer, diffuse large B cell lymphoma, intrahepatic cholangiocarcinoma and so on [1, 2]. However, the relationship between the RASGEF1A gene and CN-AML has not been reported.

METHODS

By integrating the Cancer Genome Atlas (TCGA) database 75 patients with CN-AML and 240 Gene Expression Omnibus (GEO) database CN-AML samples, we examined the association between RASGEF1A's RNA expression level and DNA methylation of and AML patients' prognosis. Then, we investigated the RASGEF1A RNA expression and DNA methylation's prognostic value in 77 patients with AML after allogeneic hematopoietic stem cell transplantation (Allo-HSCT) as well as 101 AML patients after chemotherapy respectively. We investigated the association between sensitivity to Crenolanib and expression level of RASGED1A in patients by integrating 191 CN-AML patients from BeatAML dadataset. We integrated the expression and methylation of RASGEF1A to predict the CN-AML patients' prognosis and investigated the relationship between prognostic of AML patients with different risk classification and expression levels or methylation levels of RASGEF1A.

RESULTS

We found that RASGEF1A gene high expression group predicted poorer event-free survival (EFS) (P< 0.0001) as well as overall survival (OS) (P< 0.0001) in CN-AML samples, and the identical results were found in AML patients receiving chemotherapy (P< 0.0001) and Allo-HSCT (P< 0.0001). RASGEF1A RNA expression level is an CN-AML patients' independent prognostic factor (EFS: HR = 5.5534, 95% CI: 1.2982-23.756, P= 0.0208; OS: HR = 5.3615, 95% CI: 1.1014-26.099, P= 0.0376). The IC50 (half maximal inhibitory concentration) of Crenolanib of CN-AML samples with RASGEF1A high expression level is lower. In addition, patients with high RASGEF1A methylation level had significant favorable prognosis (EPS: P< 0.0001, OS: P< 0.0001). Furthermore, the integrative analysis of expression and methylation of RASGEF1A could classify CN-AML patients into subgroups with different prognosis (EFS: P= 0.034, OS: P= 0.0024). Expression levels or methylation levels of RASGEF1A help to improve risk classification of 2010 European Leukemia Net.

CONCLUSION

Higher RASGEF1A RNA expression and lower DNA methylation predicts CN-AML patients' poorer prognosis. The RASGEF1A high expression level from patients with CN-AML have better sensitivity to Crenolanib. The integrative analysis of RASGEF1A RNA expression and DNA methylation can provide a more accurate classification for prognosis. Lower RASGEF1A expression is a favorable prognostic factor for AML patients receiving chemotherapy or Allo-HSCT. 2010 European Leukemia Net's risk classification can be improved by RASGEF1A expression levels or methylation levels.

Major heritable renal cell carcinoma syndromes: novel treatment options and future perspectives

PURPOSE OF REVIEW

To provide an overview of diagnosis, genetic abnormalities, clinical signs and treatment options for the major heritable renal cell carcinoma (RCC) syndromes.

RECENT FINDINGS

RCC in major hereditary syndromes are disorders which are typically autosomal dominant. They predispose patients to early onset of RCC and may exhibit other extrarenal manifestations. Early recognition of these diseases allows correct screening at appropriate ages as well as early detection of RCC. Moreover, expedient identification may optimize the management of extra renal manifestations as well as allow for genetic testing and screening of at-risk relatives.

SUMMARY

The risk of RCC in these major heritable syndromes is higher than sporadic disease. They occur at earlier age groups and can be multifocal or bilateral. Tumours are observed until at least 3 cm before any intervention, while nephron sparing surgery is widely considered as the treatment of choice except for hereditary leiomyomatosis with renal cell cancer, of which radical nephrectomy is treatment of choice. Intervention should be timeous as there is a highly reported incidence of early metastasis. Molecular therapies have been used in the setting of patients with metastasis, some of which show favourable outcomes.

The Pathologic and Molecular Genetic Landscape of the Hereditary Renal Cancer Predisposition Syndromes

It is estimated that 5-8% of renal tumors are hereditary in nature with many inherited as autosomal dominant. These tumors carry a unique spectrum of pathologic and molecular alterations, the knowledge of which is expanding in the recent years. Indebted to this knowledge, many advances in treatment of these tumors have been achieved. In this review, we summarize the current understanding of the genetic renal neoplasia syndromes, the clinical and pathologic presentations, their molecular pathogenesis, the advances in therapeutic implications and targeted therapy.

[Hereditary kidney cancer - easily clarified and diagnosed with ToSCaNA]

BACKGROUND

In recent years great improvements in the diagnosis and differentiation of hereditary syndroms with predisposition for kidney cancer have been achieved. It has been assumed that 5-8% of all kidney cancer have a hereditary origin. In reality, this number will probably be much higher as many genetic aspects of kidney cancer are still not entirely known. Hereditary kidney cancer usually shows two characteristic properties: While the median age of diagnosis of sporadic renal cell carcinoma is 64 years, patients with a hereditary tumor predisposition are about 20 years younger at the time of diagnosis. Additionally, their tumors often occur multifocal/bilateral. Therefore, a special management with extended diagnostics is necessary for these young kidney cancer patients. In literature many reports on hereditary syndromes with kidney cancer predisposition exist. Though, these papers usually put their focus on single syndromes rather than on the aspects of kidney cancer. The goal of this article is to present the practicing urologist with a compact overview of the most important hereditary syndromes with kidney cancer predisposition and by this improve the primary diagnostic and treatment of renal cancer patients and their relatives.

MATERIAL/METHODS

We conducted a literature search on the five most important hereditary syndromes with kidney cancer association and summarized the results in a chart. Additionally, we formed the acronym ToSCaNA combining the most important extrarenal manifestations of the syndromes. Based on this data, a diagnostic workflow and treatment path was established.

RESULTS

All in all, hereditary kidney cancer is a rare entity, which nonetheless could present as a significant number in high-volume centers. For doctors who scarcely get in contact with these types of tumors, the acronym and workflow could pose a valuable asset for their clinical diagnostic portfolio. An early identification and diagnostic work-up of affected patients and their relatives is crucial for appropriate treatment and surveillance and allows the identification/treatment of additionally affected relatives.

CONCLUSION

In patients with young age of onset and multifocal/bilateral occurrence of kidney cancer, hereditary syndromes should always be considered. The initial suspicion of a hereditary genesis of the cancer can be further evaluated by the acronym ToSCaNA and the presented workflow.

Characterization of renal cell carcinoma-associated constitutional chromosome abnormalities by genome sequencing

Constitutional translocations, typically involving chromosome 3, have been recognized as a rare cause of inherited predisposition to renal cell carcinoma (RCC) for four decades. However, knowledge of the molecular basis of this association is limited. We have characterized the breakpoints by genome sequencing (GS) of constitutional chromosome abnormalities in five individuals who presented with RCC. In one individual with constitutional t(10;17)(q11.21;p11.2), the translocation breakpoint disrupted two genes: the known renal tumor suppressor gene (TSG) FLCN (and clinical features of Birt‐Hogg‐Dubé syndrome were detected) and RASGEF1A. In four cases, the rearrangement breakpoints did not disrupt known inherited RCC genes. In the second case without chromosome 3 involvement, the translocation breakpoint in an individual with a constitutional t(2;17)(q21.1;q11.2) mapped 12 Kb upstream of NLK. Interestingly, NLK has been reported to interact indirectly with FBXW7 and a previously reported RCC‐associated translocation breakpoint disrupted FBXW7. In two cases of constitutional chromosome 3 translocations, no candidate TSGs were identified in the vicinity of the breakpoints. However, in an individual with a constitutional chromosome 3 inversion, the 3p breakpoint disrupted the FHIT TSG (which has been reported previously to be disrupted in two apparently unrelated families with an RCC‐associated t(3;8)(p14.2;q24.1). These findings (a) expand the range of constitutional chromosome rearrangements that may be associated with predisposition to RCC, (b) confirm that chromosome rearrangements not involving chromosome 3 can predispose to RCC, (c) suggest that a variety of molecular mechanisms are involved the pathogenesis of translocation‐associated RCC, and (d) demonstrate the utility of GS for investigating such cases.