Cystic renal-epithelial derived induced pluripotent stem cells from polycystic kidney disease patients.

Autosomal-dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disease, leading to kidney failure in most patients. In approximately 85% of cases, the disease is caused by mutations in PKD1. How dysregulation of PKD1 leads to cyst formation on a molecular level is unknown. Induced pluripotent stem cells (iPSCs) are a powerful tool for in vitro modeling of genetic disorders. Here, we established ADPKD patient-specific iPSCs to study the function of PKD1 in kidney development and cyst formation in vitro. Somatic mutations are proposed to be the initiating event of cyst formation, and therefore, iPSCs were derived from cystic renal epithelial cells rather than fibroblasts. Mutation analysis of the ADPKD iPSCs revealed germline mutations in PKD1 but no additional somatic mutations in PKD1/PKD2. Although several somatic mutations in other genes implicated in ADPKD were identified in cystic renal epithelial cells, only few of these mutations were present in iPSCs, indicating a heterogeneous mutational landscape, and possibly in vitro cell selection before and during the reprogramming process. Whole-genome DNA methylation analysis indicated that iPSCs derived from renal epithelial cells maintain a kidney-specific DNA methylation memory. In addition, comparison of PKD1+/- and control iPSCs revealed differences in DNA methylation associated with the disease history. In conclusion, we generated and characterized iPSCs derived from cystic and healthy control renal epithelial cells, which can be used for in vitro modeling of kidney development in general and cystogenesis in particular.

Clinical and cytogenetic analyses in uveal melanoma.

PURPOSE: Uveal melanoma is one of the most frequently occurring primary intraocular malignancies in the Western world. Cytogenetically these tumors are characterized by typical chromosomal losses and gains, such as loss of 1p, 3, and 6q and gain of 6p and 8q. Whereas most studies focus on known aberrations, in this one, cytogenetic changes were characterized and correlated with clinical and histopathologic parameters. METHODS: Karyotypes of 74 primary uveal melanomas were analyzed with respect to the presence or absence of chromosomal gains and losses. In the analysis, classic clinical and histopathologic parameters were analyzed together with the chromosomal aberrations. RESULTS: At a median follow-up of 43 months, 34 patients had died or had metastatic disease. Clonal chromosomal abnormalities were present in 59 tumors. The most frequent chromosomal abnormalities involved chromosome 8 (53%); loss of chromosome 3, p-arm (41%) and q-arm (42%); partial loss of chromosome 1, p-arm (24%); and abnormalities in chromosome 6 that resulted in gain of 6p (18%) and/or loss of 6q (28%). Less-frequent aberrations were abnormalities in chromosome 16, in particular loss of chromosome 16 q-arm (16%). In the univariate analysis, loss of chromosome 3, largest tumor diameter, gain in 8q, and mixed/epithelioid cell type in the tumor compared with tumors without these chromosomal changes or with a spindle cell type was associated with decreased disease-free survival. When corrected for confounding variables, significance of gain of 8q and cell type was decreased, whereas the significance of loss of chromosome 3p or 3q and largest tumor diameter remained the same. CONCLUSIONS: Monosomy 3 and largest tumor diameter are the most significant in determining survival of patients with uveal melanoma. Abnormalities in the q-arm of chromosome 16 are relatively common in uveal melanoma, but are not associated with survival or other cytogenetic or histopathologic parameters.

Concurrent loss of chromosome arm 1p and chromosome 3 predicts a decreased disease-free survival in uveal melanoma patients.

PURPOSE: Uveal melanoma is a highly malignant disease with a mortality rate of 50% at 10 to 15 years. Previous studies have shown that chromosomal changes are associated with decreased survival of the patient. However, in these studies the small number of tumors analyzed did not allow robust statistical analysis. In the present study, the independent numerical changes in chromosomes 1, 3, 6, and 8 on disease-free survival (DFS) was assessed in a large series of patients with uveal melanoma. METHODS: One hundred twenty tumors from patients with uveal melanoma were analyzed for numerical changes in chromosomes 1, 3, 6, and 8, with cytogenetic analysis, fluorescent in situ hybridization, and/or comparative genomic hybridization. Data were correlated with disease outcome in univariate and multivariate analyses, by Kaplan-Meier and Cox regression analyses. RESULTS: At a mean follow-up time of 45 months, 42 patients had died or had metastatic disease. In the univariate analysis, loss of chromosome 3, gain of 8q, largest tumor diameter, or the presence of epithelioid cells was associated with a decreased DFS. In the multivariate analysis, the effect of monosomy 3 on survival was largely modified by changes in 1p36. Regarding all chromosomal changes, only the concurrent loss of the short arm of chromosome 1 and all of chromosome 3 was an independent prognostic parameter for disease-free survival (P < 0.001). CONCLUSIONS: In uveal melanoma, concurrent loss of the short arm of chromosome 1 and all of chromosome 3 is an independent predictor of decreased DFS.