Simultaneous imaging of membrane antigen and the corresponding chromosomal locus in pathology archives

Fluorescent in situ hybridization heating pretreatment: the key is temperature control

Fluorescent in situ hybridization (FISH) is a very useful tool for diagnostic and prognostic purposes in pathology. However, many laboratories still experience troubles when applying FISH to paraffin material. To overcome these difficulties, different pretreatments which include enzymatic digestion have been described. Usually, previous to digestion, a heating step is performed. The aim of this study was to compare the efficiency of the heating step with different buffers and different heating methods. We conclude that the main factor in the heating pretreatment is the temperature control, irrespective of the buffer used. Best results are obtained with any buffer by heating the slides to 99°C for 15 min followed by 10 min at room temperature.

PIK3CA mutation and amplification in human lung cancer

To explore the significance of phosphatidylinositol-3-kinase, catalytic, alpha (PIK3CA) in the carcinogenesis in human lung, mutations and copy number changes were investigated in 148 Japanese patients with primary cancer of the lung. For biological validation, the effects of exogenously expressed wild-type and mutated PIK3CA were studied in an immortalized human airway epithelial cell line. Mutations in PIK3CA were found in five (3.6%) of the 139 available patients, and copy number gains were found in 21 (18.3%) of 115 patients, respectively. Overall, mutations or copy number gains were detected in 24 of the 106 patients (22.6%) for whom results in both analyses were available. The prevalence of copy number gains was higher in men, smokers, and in patients with squamous cell carcinoma than in the opposite categories. The copy number changes showed a trend toward higher prevalence in the earlier stages (P = 0.038). Interestingly, the presence of mutations and of copy number alterations were mutually exclusive in the present patients, implying that both entail equivalent oncogenic potential. Over-expressed wild-type PIK3CA and its two common mutants, K545E and H1047R, significantly enhanced the anchorage-independent growth activity and migration activity of immortalized airway epithelium 16HBE14o- cells, but the effects of the K545E and H1047R mutants were more remarkable than those of the wild-type. The present demonstrates an important role of PIK3CA in human lung carcinogenesis.

Genomic instability and increased expression of BUB1B and MAD2L1 genes in ductal breast carcinoma

In a series of invasive ductal breast carcinoma, we investigated the status of chromosomal and intrachromosomal instability by fluorescence in situ hybridisation and determined the level of mRNA expression for two genes involved in the mitotic spindle checkpoint pathway, BUB1B and MAD2L1. All breast cancers demonstrated higher chromosomal instability rates in tumor samples (average: 56.86%, range: 36.24-76.78%) than in controls (average: 11.54%, range: 9.91-14.84%) (P<0.0001). As well as intrachromosomal instability rates were elevated in tumor (average: 18.45% range: 8.34-35.8%) as compared with controls (average: 4.18% range: 3.47-4.81%) (P<0.0001). An increase in BUB1B and MAD2L1 transcripts was demonstrated in the majority of the tumor tested. BUB1B mRNA levels but not MAD2L1 levels correlated with intrachromosomal instability (r=0.722, P=0.018).

Repeated fluorescence in situ hybridization by a microwave-enhanced protocol

A novel re-hybridization protocol for pathology archive sections that uses microwave-assisted fluorescence in situ hybridization (FISH) is described. Stripping the probe from the pathology archive sections with HCl and re-hybridizing with the next probe by intermittent microwave irradiation generated clear signals without background noise. Repeated stripping and hybridization with numerous bacterial artificial chromosome (BAC)-derived probes would identify the profile of genome-wide changes in small lesions on sections.

Chromosomal numerical abnormalities in early stage lung adenocarcinoma

Chromosomal numerical abnormalities (CNA) are ubiquitous in human cancers. However, the question of when a CNA occurs in the course of tumor generation and progression, is controversial. Recent radiological scrutiny has enabled the identification of small peripheral lesions in the lung. A chromosome-wide investigation encompassing almost all the chromosomal centromeres was performed using modified fluorescence in situ hybridization on the archived pathological samples of 16 atypical adenomatous hyperplasia (AAH) and 30 lung adenocarcioma (AdCa) specimens including those smaller than 1 cm in size. The prevalence of the gain was more extensive in male than in female patients, and in non-smokers than in smokers. It tended to be greater in poorly differentiated AdCa, in moderately differentiated AdCa, and in well-differentiated AdCa cases, in that order. Most AAH had non-specific gains affecting all the examined chromosomes. The prevalence of the gain differed significantly between AAH and bronchioloalveolar carcinoma (BAC) </= 1 cm, but not between BAC < 1 cm and well-differentiated AdCa > 1 cm. It is proposed that the CNA is a distinct phenomenon occurring in the early or premalignant stage of lung AdCa, and that the CNA itself may not be a sequel in the carcinogenetic process, but a driving factor in carcinogenesis.