Gavin R. Turbett

Distinction Between Intraductal Carcinoma of the Prostate (IDC-P), High-Grade Dysplasia (PIN), and Invasive Prostatic Adenocarcinoma, Using Molecular Markers of Cancer Progression

Prostate ducts and acini whose lumens are filled with malignant cells represent a well‐recognized histological pattern recently termed intraductal carcinoma of the prostate (IDC‐P). These tumors are often associated with rapid disease progression, and most recur after radical surgery. Controversy exists as to whether IDC‐P should be recognized as a separate entity, an extension of high‐grade dysplasia (PIN) or invasive carcinoma as described by the Gleason grading system. This study investigates the use of molecular markers in defining the position of IDC‐P in the evolutionary hierarchy of prostate cancer progression.

Loss of heterozygosity on chromosome 2q: possibly a poor prognostic factor in head and neck cancer.

Loss of heterozygosity (LOH) correlates with inactivated tumor suppressor genes. The aim of this study was to see if LOH on chromosomes 2q, 3p, 5q, 9p, and 17p correlated with survival in early squamous cell carcinoma of the head and neck (SCCHN).

Microsatellite instability and loss of heterozygosity in mammary carcinoma and its probable precursors.

Microsatellite instability is a form of genetic damage that may be due to defective mismatch repair genes and may be a marker of processes leading to malignancy. We have analysed a series of epithelial hyperplasia of usual type, carcinomas in situ and invasive and metastatic carcinomas from the mammary gland on the assumption that they represent stages in the evolution of mammary carcinoma. Eight markers on chromosomes 3p, 4q, 9p, 11p, 14q, 17p, 17q and Xq were examined for microsatellite instability and loss of heterozygosity. High rates of loss on chromosomes 17p, 17q and Xq indicate that these chromosomal arms contain genes important in mammary carcinogenesis. The rate of microsatellite instability observed in this study was uniformly low, irrespective of the lesion. This implies that microsatellite instability is not a marker of malignancy in most instances of mammary neoplasia.

The use of optimal cutting temperature compound can inhibit amplification by polymerase chain reaction.

Optimal cutting temperature (OCT) is a widely used embedding medium for tissues for histopathologic analysis. This investigation examined the effects that OCT storage can have upon the ability to perform subsequent molecular biological analyses. Tumor material was dissected into small pieces and stored at −20°C both with and without OCT. DNA and RNA were then extracted from the tissue fragments and analyzed by the polymerase chain reaction (PCR), using primer sets designed to amplify a range of product sizes, and also by reverse transcriptase-PCR (RT-PCR). The storage of pathological specimens in OCT compound was found to affect significantly and irreversibly the ability to amplify DNA in the PCR, particularly as the size of the amplified fragment increased. This effect appeared to occur as a result of greater degradation of DNA extracted from tissue embedded in OCT compared to DNA extracted from tissue stored without OCT. RNA quality appeared unaffected, which may be because of the extraction protocol employed. Our results suggest that OCT-embedded frozen-tissue samples may be used for RNA isolation for subsequent RT-PCR and for the in vitro amplification of DNA targets of approximately < 300 base pairs only. We strongly advise against the routine storage of any tissue biopsy material in OCT if molecular analyses may be required.

The incidence of microsatellite instability and loss of heterozygosity in fibroadenoma of the breast

A majority of studies have shown an increase in the risk of breast cancer among women previously diagnosed with fibroadenoma (FA). At present there is conflicting evidence whether some of the chromosome abnormalities frequently found in breast carcinoma, such as loss of heterozygosity (LOH), are already present in FAs and other types of benign breast disease and, if present, whether such abnormalities are associated with the observed increase in risk. Microsatellite instability (MSI) is also recognised as a marker of genetic damage and is thought to occur when there has been damage to the cells mismatch repair (MMR) system. We have analysed 39 cases of FA obtained from paraffin-embedded tissue for the presence of MSI and LOH at 11 loci to determine if these types of genetic alterations occur in FA. The incidence of MSI and LOH found were 4 of 395 (1.0%) and 5 of 271 (1.8%) informative loci tested respectively. Approximately 8% of cases were positive for MSI and 10% were positive for LOH, with one specimen having multiple occurences of both MSI and LOH. We conclude that these forms of genetic alteration do occur in FAs but that the incidence is low.