Algorithmic assessment of missense mutation severity in the Von-Hippel Lindau protein

The von Hippel-Lindau protein forms fibrillar amyloid assemblies that are mitigated by the anti-amyloid molecule Purpurin

The von Hippel-Lindau protein (pVHL) is a tumor suppressor involved in oxygen regulation via dynamic nucleocytoplasmic shuttling. It plays a crucial role in cell survival by degrading hypoxia-inducible factors (HIFs). Mutations in the VHL gene cause angiogenic tumors, characterized as VHL syndrome. However, aggressive tumors involving wild-type pVHL have also been described but the underlying mechanism remains to be revealed. We have previously shown that pVHL possesses several short amyloid-forming motifs, making it aggregation-prone. In this study, using a series of biophysical assays, we demonstrated that a pVHL-derived fragment (pVHL104-140) that harbors the nuclear export motif and HIF binding site, forms amyloid-like fibrillar structures in vitro by following secondary-nucleation-based kinetics. The peptide also formed amyloids at acidic pH that mimics the tumor microenvironment. We, subsequently, validated the amyloid formation by pVHL in vitro. Using the Curli-dependent amyloid generator (C-DAG) expression system, we confirmed the amyloidogenesis of pVHL in bacterial cells. The pVHL amyloids are an attractive target for therapeutics of the VHL syndrome. Accordingly, we demonstrated in vitro that Purpurin is a potent inhibitor of pVHL fibrillation. The amyloidogenic behavior of wild-type pVHL and its inhibition provide novel insights into the molecular underpinning of the VHL syndrome and its possible treatment.

The germline mutational landscape of genitourinary cancers and its indication for prognosis and risk

BACKGROUND

Germline mutations represent a high risk of hereditary cancers in population. The landscape and characteristics of germline mutations in genitourinary cancer are largely unknown, and their correlation with patient prognosis has not been defined.

METHODS

Variant data and relevant clinical data of 10,389 cancer patients in The Cancer Genome Atlas (TCGA) database was downloaded. The subset of data of 206 genitourinary cancer patients containing bladder urothelial carcinoma (BLCA), kidney chromophobe carcinoma (KICH), kidney renal clear cell carcinoma (KIRC), kidney renal papillary cell carcinoma (KIRP) and prostate adenocarcinoma (PRAD) cancer with germline mutation information was filtered for further analysis. Variants were classified into pathogenic, likely pathogenic and non-pathogenic categories based on American College of Medical Genetics and Genomics (ACMG) guidelines. Genome Aggregation Database (gnomAD) database was used to assist risk analysis.

RESULTS

There were 48, 7, 44, 45 and 62 patients with germline mutations identified in BLCA, KICH, KIRC, KIRP and PRAD, respectively. Pathogenic germline mutations from 26 genes and likely pathogenic mutations from 33 genes were revealed. GJB2, MET, MUTYH and VHL mutations ranked top in kidney cancers, and ATM and CHEK2 mutations ranked top for bladder cancer, while ATM and BRCA1 mutations ranked top for prostate cancer. Frameshift, stop gained and missense mutations were the predominant mutation types. BLCA exhibited the highest ratio of stop gained mutations (22/48 = 45.8%). No difference in patient age was found among pathogenic, likely pathogenic and non-pathogenic groups for all cancer types. The number of male patients far overweight female patients whether PRAD was included (P = 0) or excluded (P < 0.001). Patients with pathogenic or likely pathogenic germline mutations exhibited significantly worse overall survival rate than the non-pathogenic group for all genitourinary cancers. More important, analyses assisted by gnomAD database revealed that pathogenic or likely pathogenic germline mutations significantly increased the risk for genitourinary cancer in population, with the odds ratio at 14.88 (95%CI 11.80-18.77) and 33.18 (95%CI 24.90-44.20), respectively.

CONCLUSIONS

The germline mutational status for genitourinary cancers has been comprehensively characterized. Pathogenic and likely pathogenic germline mutations increased the risk and indicated poor prognosis of genitourinary cancers.

Germline Pathogenic Variants Identified by Targeted Next-Generation Sequencing of Susceptibility Genes in Pheochromocytoma and Paraganglioma

The aim of this study was to evaluate germline variant frequencies of pheochromocytoma and paraganglioma targeted susceptibility genes with next-generation sequencing method. Germline DNA from 75 cases were evaluated with targeted next-generation sequencing on an Illumina NextSeq550 instrument. KIF1B, RET, SDHB, SDHD, TMEM127, and VHL genes were included in the study, and Sanger sequencing was used for verifying the variants. The pathogenic/likely pathogenic variants were in the VHL, RET, SDHB, and SDHD genes, and the diagnosis rate was 24% in this study. Three different novel pathogenic variants were determined in five cases. This is the first study from Turkey, evaluating germline susceptibility genes of pheochromocytoma and paraganglioma with a detection rate of 24% and three novel variants. All patients with pheochromocytoma and paraganglioma need clinical genetic testing with expanded targeted gene panels for higher diagnosis rates.