The presence of retinoblastoma (RB) protein was evaluated by immunohistochemical staining and correlated with loss of heterozygosity (LOH) at the RB locus in 52 primary epithelial ovarian carcinomas. Forty-eight tumors were informative at the RB locus by molecular genetic analysis. Twenty-five tumors (52%) showed loss of heterozygosity at the RB locus. RB protein expression was found in 23 of t...

Genetic alterations of the long arm of chromosome 11 have been implicated in melanoma pathogenesis, and we recently identified two distinct regions of common allelic loss in chromosomal band 11q23. To establish the point in time of melanoma tumorigenesis at which these two putative tumor suppressor loci become relevant, we investigated allelic loss [loss of heterozygosity (LOH)] in both chromos...

Mechanisms for multifocal bladder carcinogenesis remain unclear. To see whether normal mucosa had already acquired genetic or epigenetic changes, we examined loss of heterozygosity (LOH) at 10 microsatellite loci and methylation of the p16(INK4) CpG island in multiple tumors and pathologically normal mucosa in six patients with bladder cancer. Either LOH or methylation was detected in 77% of sa...

BACKGROUND Microsatellite instability (MSI) and loss of heterozygosity (LOH) are frequent events in ovarian carcinogenesis; however, little is known as to their clinical significance and association with other molecular lesions. MATERIALS AND METHODS Twelve microsatellite markers for MSI and LOH analysis were used in 64 ovarian carcinomas with known TP53 mutational status. The clinical import...

Ovarian cancer is currently the most lethal gynecological malignancy in women. It is a heterogeneous and cytogenetically complex disease previously associated with genomic instability. Our purpose was to analyze microsatellite markers to determine patterns and levels of instability as well as possible correlations with histopathological parameters. Polymerase chain reaction was used to characte...

Human chromosomes 1,4,6, and 9 harbor genes which induce cellular senescence in vitro but a role for their inactivation in human tumors is not established. To investigate this we searched for loss of heterozygosity (LOH) on these chromosomes in keratinocyte cultures obtained from different stages of human squamous cell carcinoma progression. There was consistent LOH between markers D9S171 and D...

Consistent deletions and loss of heterozygosity (LOH) in polymorphic markers in a determinate chromosomal fragment are known to be indicative of a closely mapping tumor suppressor gene. Deletion of the long arm of chromosome 7 is a frequent trait in many kinds of human primary tumors. We studied LOH of 14 markers on chromosome 7q in order to determine the location of a putative tumor suppressor...

In addition to RB1 gene mutations, retinoblastomas frequently show gains of 1q and 6p and losses of 16q. To identify suppressor genes on 16q, we analyzed 22 short tandem repeat loci in 58 patients with known RB1 mutations. A subset of tumors was also investigated by conventional and matrix comparative genomic hybridization. In 40 of 58 (69%) tumors, we found no loss of heterozygosity (LOH) at a...

Immune evasion is a hallmark of cancer. Losing the ability to present neoantigens through human leukocyte antigen (HLA) loss may facilitate immune evasion. However, the polymorphic nature of the locus has precluded accurate HLA copy-number analysis. Here, we present loss of heterozygosity in human leukocyte antigen (LOHHLA), a computational tool to determine HLA allele-specific copy number from...

Alterations of the PTEN gene occur in glioblastoma multiforme. To determine the frequency of PTEN alteration, 34 consecutive glioblastomas were studied in detail. Sequencing each of the nine exons amplified from tumor DNA revealed 11 mutations. Analysis of polymorphic markers within and surrounding the PTEN gene identified an additional four homozygous deletion mutations. Loss of heterozygosity...