Different types of human cells which normally grow as monolayers or suspension cultures were tested for their capacity to form and grow as spheroids. Sixteen out of the 27 tested tumour cell lines formed spheroids. Nearly all of these spheroids also grew. With only two exceptions the doubling times were longer when the tumour cells grew as spheroids than when they grew in conventional mass culture. Eleven out of 13 tested human non-tumour cells formed small spheroids but of these only the spheroids of lymphoid origin could grow. These lymphoid cells grew faster when aggregated to spheroids than when in single-cell suspension culture. None of the other non-tumour cells, which normally grew as monolayers, could grow as spheroids. The normally monolayer-cultured tumour cells formed symmetrical spheroids with smooth surfaces while the normally suspension-cultured cells formed irregular spheroids with rough surfaces. All large spheroids had a necrotic centre surrounded by a shell of viable cells. The thickness of the viable cell layer varied depending on cell type. The shape and organization of cells within the spheroids also varied largely. The results show that many types of human cells can be cultured as spheroids and that a wide spectrum of morphological appearances and growth rates can be obtained.

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Purpose: Loss of p53 function in urothelial cell carcinoma (UCC) by mutation or inactivation disrupts normal cell cycle checkpoints, generating a favorable milieu for genomic instability, a hallmark of UCC. The aim of this study was to characterize novel DNA copy number changes to identify putative therapeutic targets. Experimental Design:We report our findings using array comparative genomic hybridization on a whole-genome BAC/PAC/cosmid array with a median clone interval of 0.97 Mb to study a series of UCC cases. TP53 status was determined by direct sequencing, and an in-house tissue microarray was constructed to identify protein expression of target genes. Results: Array comparative genomic hybridization allowed identification of novel regions of copy number changes in addition to those already known from previous studies. A novel amplification previously unreported in UCC was identified at 1q32. A chromosome 1tile path array was used to analyze tumors that showed gains and amplification; the mouse double minute 4 (MDM4) homologue was identified as the amplified gene. MDM4 mRNA expression correlated with copy number and tumor grade. Copy number changes of MDM4 and MDM2 occurred exclusively in tumors with wild-type p53. Overexpression of MDM4 corresponded to disruption of p53 transcriptional activity. Immunohistochemistry on an independent series by tissue microarray identified an inverse relationship between Mdm4 and Mdm2, with Mdm4 expression highest in invasive UCC. Conclusion:The data indicate that gain/amplification and overexpression of MDM4 is a novel molecular mechanism by which a subset of UCC escapes p53-dependent growth control, thus providing new avenues for therapeutic intervention.

A series of 20 capillary haemangioblastomas of the central nervous system was screened for mutations of the von Hippel–Lindau (VHL) tumour suppressor gene by single strand conformational polymorphism (SSCP) and heteroduplex analysis. Aberrant polymerase chain reaction (PCR) products were detected in ten tumours. DNA sequencing of these PCR products revealed that seven tumours had frameshift mutations due either to deletions of one or more base pairs (six cases) or to insertion of one base pair (one case). The remaining three tumours had either point mutations of intron splice site sequences (two cases) or a point mutation resulting in an amino acid substitution (one case). Evidence for germline alterations of the VHL gene was found in two patients who showed identical mutations in both tumour and corresponding leukocyte DNA. The results suggest that mutation of the VHL tumour suppressor gene represents a significant event in the development of capillary haemangioblastomas.