A model for evaluation of in situ hybridization spot-count distributions in tissue sections

Gain of Chromosomal Region 3q26 as a Prognostic Biomarker for High-Grade Cervical Intraepithelial Neoplasia: Literature Overview and Pilot Study

Approximately 20–40% of high-grade Cervical Intraepithelial Neoplasia (CIN) regresses spontaneously, but the natural prognosis of an individual lesion is unpredictable. Gain of the chromosomal 3q region, which contains the human telomerase RNA gene on 3q26, is found in CIN lesions and cervical carcinoma and shows correlation with disease grade. The aim of this study is to assess whether 3q26 gain as a single genetic marker can predict the natural prognosis of high-grade CIN, by performing a review of the literature and pilot study. A literature review was conducted. Additionally, we performed a pilot study in 19 patients with histologically confirmed high-grade CIN lesions who were followed for a mean of 115 days, after which loop excision was performed. Fluorescent in situ hybridization analysis was performed on the initial diagnostic biopsies to determine gain of 3q26. Eight studies were included in the literature overview, with a total of 407 patients. Of these, only 22 patients had high-grade lesions. All studies found an association between 3q26 gain and disease prognosis. Positive predictive values (PPV) ranged from 50 to 93%, negative predictive values (NPV) ranged from 75 to 100%. Only five out of 155 patients (3.2%) without 3q26 gain showed disease persistence or progression. In our pilot study on 3q26 gain in high-grade CIN, the PPV of 3q26 gain for disease persistence was 67%, the NPV 100%. All four patients without 3q26 gain showed disease regression. In conclusion, the absence of 3q26 gain in diagnostic biopsies may be applied to identify high-grade CIN lesions with a high probability of disease regression.

Use of multicolor fluorescence in situ hybridization to detect deletions in clinical tissue sections

A variety of laboratory methods are available for the detection of deletions of tumor suppressor genes and losses of their proteins. The clinical utility of fluorescence in situ hybridization (FISH) for the identification of deletions of tumor suppressor genes has previously been limited by difficulties in the interpretation of FISH signal patterns. The first deletion FISH assays using formalin-fixed paraffin-embedded tissue sections had to deal with a significant background level of signal losses affecting nuclei that are truncated by the cutting process of slide preparation. Recently, more efficient probe designs, incorporating probes adjacent to the tumor suppressor gene of interest, have increased the accuracy of FISH deletion assays so that true chromosomal deletions can be readily distinguished from the false signal losses caused by sectioning artifacts. This mini-review discusses the importance of recurrent tumor suppressor gene deletions in human cancer and reviews the common FISH methods being used to detect the genomic losses encountered in clinical specimens. The use of new probe designs to recognize truncation artifacts is illustrated with a four-color PTEN FISH set optimized for prostate cancer tissue sections. Data are presented to show that when section thickness is reduced, the frequency of signal truncation losses is increased. We also provide some general guidelines that will help pathologists and cytogeneticists run routine deletion FISH assays and recognize sectioning artifacts. Finally, we summarize how recently developed sequence-based approaches are being used to identify recurrent deletions using small DNA samples from tumors.

Processing and staining of cell and tissue material for interphase cytogenetics

This unit describes in detail the protocols for preparation of biological specimens (fresh or fixed) for the purposes of establishing in situ hybridization procedures using probes for specific regions of the genome, allowing targeted detection of numerical and structural chromosome aberrations in the interphase nucleus. The authors present a series of comprehensive protocols from the simplest to the most complex.

Biological behavior of CIN lesions is predictable by multiple parameter logistic regression models

OBJECTIVES

Progression and regression of premalignant cervical lesions cannot be predicted using conventional cytomorphological or histomorphological parameters. However, markers such as human papillomavirus (HPV) or makers indicating proliferation, genetic instability and chromosomal aberration may be of predictive value assessing short-term biological behavior of cervical intraepithelial neoplasia. In this paper, we have studied the usage of logistic regression models with Ki-67 labeling index (LI), chromosome index for chromosome 1 (CI#1) and aneusomy for chromosome 1 in cervical smears to predict progressive and regressive behavior of premalignant cervical lesions.

METHODS

Retrospectively, the intake smears of 42 women showing regression in follow-up and of 31 women showing progression in follow-up were assessed.

RESULTS

A multiparameter logistic regression model containing the parameters Ki-67 LI, CI#1 and the fraction of cells with four copies of chromosome 1 per nucleus appeared to be the best predicting model, overall correct classification of 93.2% (area under the receiver operating characteristic curve 0.96 +/- 0.02). After cross-validation, the model correctly classified 66 of 73 samples (90.4%). Moreover, the model predicted biological behavior perfectly assessing the smear taken subsequently to the intake smear of 46 women.

CONCLUSION

Although measuring parameters indicating proliferation and chromosome 1 aberration is laborious, this study demonstrates that short-term progressive and regressive behavior is highly predictable using a model combing these parameters. We also showed that in the triage management of high-risk human papillomavirus-positive women with minimally abnormal smears applying a model as such can be useful.

Amplification patterns of three genomic regions predict distant recurrence in breast carcinoma

Currently used clinical and histopathological parameters imprecisely define the risk of distant recurrence in breast cancer, underscoring the need for more informative prognostic markers. In the present fluorescence in situ hybridization study of archived surgical specimens, we derived an algorithm for computing a prognostic index (PI) from DNA copy numbers of three genomic regions (CYP24, PDCD6IP, and BIRC5) for estrogen/progesterone receptor-positive (ER/PR+) cancers and a distinct PI (based on NR1D1, SMARCE1, and BIRC5) for estrogen/progesterone receptor-negative (ER/PR-) cancers. Among independent test cases stratified by PI, recurrence rates were significantly higher among high-risk patients than low-risk patients for both ER/PR+ (odds ratio = 9.52, 95% confidence interval >2.12, P = 0.0024) and ER/PR- (odds ratio = 12.3, 95% confidence interval >1.45, P = 0.0188) cancers. Among the entire population, recurrences were significantly more prevalent for cases with PI above the medians for both ER/PR+ (Fisher's exact, P = 1.19 x 10(-5)) and ER/PR- (P = 0.0025) patients and for the node-negative subsets (ER/PR+ node-negative, P = 0.042 and ER/PR- node-negative, P = 0.039). In conclusion, these markers perform well in comparison with other criteria for recurrence risk assessment and can be used with routinely formalin-fixed, paraffin-embedded surgical specimens.

Determination of DNA ploidy by fluorescence in situ hybridization (FISH) in hydatidiform moles: Evaluation of FISH on isolated nuclei

In the past 20 years, the diagnosis of hydatidiform moles has become more difficult because of the widespread use of early uterine evacuation. Differentiating hydropic degeneration, partial, and complete moles is important because of their different prognosis. However, clinical diagnosis is less obvious, and the pathologist has to separate the different entities on the basis of very subtle morphologic criteria. In difficult cases, ploidy may be determined by various methods, including fluorescence in situ hybridization (FISH) on routine histological sections from paraffin-embedded specimens. However, FISH analysis is often difficult because of the presence of numerous truncated nuclei. In this context, we have tested the advantages of FISH on isolated nuclei, a well-known variant of the technique that might be more sensitive. We reviewed 24 cases of products of abortion: hydropic degenerations, complete hydatidiform moles, partial moles, and nonmolar triploidies. After histological review, FISH on isolated nuclei proved conclusive in all cases. The results could be easily interpreted thanks to the reduced number of truncated nuclei. The percentage of cells with 2 signals was always >70% in the diploid cases and >60% in the triploid cases. In conclusion, this sensitive technique seems to be a valuable tool for the diagnosis of moles.

Tumour embolization of the Vx2 rabbit head and neck cancer model with Dextran hydrogel and Holmium-poly(L-lactic acid) microspheres: a radionuclide and histological pilot study

INTRODUCTION

Intra-arterial embolization of unresectable malignant tumours with biodegradable microspheres is an effective way of selective anti-tumour therapy. Promising candidates are Dextran hydrogel (Dex) microspheres for chemo-embolization and Holmium-166 poly(L-lactic acid) (166HoPLA) microspheres for radio-embolization. This study was performed to investigate the distribution of intra-arterially injected microspheres both in vivo and histologically in order to establish an optimal size of particles for embolization of head and neck tumours.

MATERIAL

Twenty rabbits with Vx2 auricular tumours were embolized via the caudal auricular artery with 4 different batches of microspheres: Radioactive (166)HoPLA microspheres sieved between 20 and 50 microm and Dextran hydrogel microspheres sieved between 20 and 100 microm (Dex20), 30 and 100 microm (Dex30) or 50 and 100 microm (Dex50). Dex20 and Dex50 microspheres were labelled with 99mTechnetium in six cases.

METHODS

The average particle size of the microspheres was determined. The proportion of microspheres entrapped in the tumour was measured with a gamma camera. The distribution of microspheres around the primary tumour and spill of particles over into lungs or other organs was analysed from histological sections.

RESULTS

The mean particle diameter varied from 19 to 66 microm: (166)HoPLA 19+/-11 microm, Dex20 40+/-19 microm, Dex30 50+/-19 microm, Dex50 66+/-21 microm. The 19 microm(166)HoPLA particles proved inadequate for embolization as 51% spilled over into the lungs, whereas over 95% of the 40-66 microm Dex microspheres were retained within the primary tumour area. Particle density in lung tissues proved significantly lower for the Dex50 group. Stray emboli to the brain occurred in two rabbits.

CONCLUSION

The results of this investigation show that both Dextran hydrogel and holmium-166 poly(L-lactic acid) microspheres are potential candidates for embolization of head and neck cancer. In future studies, arterio-arteriolar anastomoses which might confound treatment should be identified and occluded. Particles with a number weighted mean diameter of at least 40 microm and a volume weighted mean size up to 70 microm should be used.

Chromosomal abnormalities in Hodgkin's disease are not restricted to Hodgkin/Reed-Sternberg cells

Hodgkin and Reed-Sternberg cells are considered to represent the malignant fraction in Hodgkin's disease. Several studies have shown that the Hodgkin and Reed-Sternberg cells are chromosomally abnormal, but genetic data about the morphologically normal cell population in Hodgkin's disease are very limited. This latter cell population has therefore been examined for chromosomal aberrations, using the in situ hybridization (ISH) procedure, making use of DNA probes for chromosomes 1, 7, 8, 9, 11, 12, 15, 17, and 18. Nuclei were isolated from freshly frozen (10 cases) and paraffin-embedded (16 cases) biopsy samples and 1000 nuclei per case were evaluated. The cases of Hodgkin's disease were compared with reactive lymph nodes, which show aberrant chromosome copy numbers in less than 1 per cent of the cells. Using strict scoring criteria, nuclei in the tumour were found to show an abnormal genotype, in the range of 1-12 per cent, with trisomies occurring most frequently. No characteristic numerical chromosome abnormality was observed. ISH on 4 microns thick paraffin sections of six cases of Hodgkin's disease revealed numerical aberrations for chromosome 1 in cells which appeared to be morphologically normal. The genomically abnormal nuclei did not differ in morphology or size from the nuclei of morphologically normal cells, but differed considerably in size when compared with the nuclei of Hodgkin/Reed-Sternberg cells after the ISH procedure. Three of these six cases revealed a population of apparently normal cells with an aberrant copy number which differed notably from the fraction observed in reactive lymph nodes. It is concluded, therefore, that a subset of morphologically normal cells, next to the Hodgkin/Reed-Sternberg cells, are chromosomally aberrant and may participate in the malignant cell fraction of Hodgkin's disease.

Is chromosome 9 loss a marker of disease recurrence in transitional cell carcinoma of the urinary bladder?

Investigation of transitional cell carcinoma of the urinary bladder (TCC) patients classified by recurrence and/or progression has demonstrated that loss of chromosome 9, as detected by FISH analysis of the pericentromeric classical satellite marker at 9q12, occurs early. A total of 105 TCCs from 53 patients were analysed in situ by two independent observers for loss of chromosome 9 using quantitative fluorescence in situ hybridization (FISH). All 53 primary tumours were evaluated for chromosomes 9, 7 and 17. Normal ranges for chromosomal copy number were defined for normal skin epidermis and bladder epithelium. Values for chromosome 9 copy number outwith the range 1.51-2.10 (mean +/- 3 x s.d. of normal values) were significantly abnormal. Twenty-five TCCs were detected with consistent monosomic scores. Of 89 TCCs, in which multiple tumour areas were analysed, 85 tumours (96%) demonstrated the same chromosome 9 copy number in all areas (2-6) analysed; only three tumours demonstrated heterogeneity for this locus. A total of 36% (12 out of 33) of patients with subsequent disease recurrence demonstrated loss of chromosome 9 in their primary and all subsequent TCCs analysed. Only a single patient (n = 20) with non-recurrent TCC showed loss of chromosome 9 (P = 0.0085). Of 53 primary tumours, eight showed significant elevation of chromosome 17. Of these patients, six demonstrated elevation in chromosome 7 copy number. No abnormalities were observed in non-recurrent patients. This study describes rapid quantitation of chromosomal copy number by FISH using a pericentromeric probe for chromosome 9 in TCC of the urinary bladder. Routinely fixed and processed material was evaluated without disaggregation. Strict quality control of FISH demonstrated that this technique was reproducible in a clinical environment and could be used to detect genetic changes relevant to patient outcome. It is proposed that loss of chromosome 9 from primary TCC of the urinary bladder identified patients at high risk of recurrence and possible progression.

The role of deoxyribonucleic acid image cytometric and interphase cytogenetic analyses in the differential diagnosis, prognosis, and clinical follow-up of hydatidiform moles. A report from the Central Molar Registration in The Netherlands

OBJECTIVES

To assess the value of deoxyribonucleic acid ploidy in the differential diagnosis and clinical follow-up of hydatidiform moles, the histopathologic features, deoxyribonucleic acid ploidy, and clinical follow-up were compared in 347 cases: 143 complete moles, 52 partial moles, and 152 abortions, of which 56 cases were hydropic abortions with histologic features of triploidy but lacked trophoblastic hyperplasia.

STUDY DESIGN

In all cases deoxyribonucleic acid image cytometry was performed, and in 85 of these cases interphase cytogenetics was also performed.

RESULTS

With use of deoxyribonucleic acid image cytometry and interphase cytogenetics, a bimodal polyploid deoxyribonucleic acid pattern was present in 97% of complete moles, 27% of partial moles, and 4% of abortions. All these cases of partial mole were reclassified to complete mole on the basis of this deoxyribonucleic acid pattern and the histopathologic features in spite of the presence of fetal blood cells, amnion, or yolk sac. Deoxyribonucleic acid triploidy was found in 95% of the remaining partial moles, in 77% of hydropic abortions with histologic features of triploidy, and in 14% of the remaining abortions. Reliable differentiation between deoxyribonucleic acid triploid partial moles and hydropic abortions with histologic features of triploidy was not possible on basis of the histopathologic features (trophoblastic hyperplasia) or 3.5c exceeding rates. Deoxyribonucleic acid diploidy was found in 1% of complete moles, 23% of hydropic abortions with features of triploidy, and 78% of the remaining abortions. Deoxyribonucleic acid tetraploidy was rarely found (1% of complete moles, 2% of partial moles, 1% of abortions). Persistent gestational trophoblastic disease developed in 33% of the bimodal deoxyribonucleic acid polyploid cases (all complete moles), in 1% of the diploid cases (concerning one of the two diploid complete moles), and in 1% of the triploid cases (partial moles).

CONCLUSION

Deoxyribonucleic acid analysis is essential in the diagnosis of hydatidiform moles to decide on clinical follow-up.

Interphase cytogenetic analysis reveals numerical chromosome aberrations in large liver cell dysplasia

BACKGROUND/AIMS

Little is known about genetic alterations in large or small liver cell dysplasia. The aim of this study was to determine whether these lesions present numerical chromosome aberrations.

METHODS

Eight patients with hepatocellular carcinoma on cirrhosis, five with large liver cell dysplasia and three with small liver cell dysplasia, were analysed by in situ hybridization with different centromeric nucleic acid probes specific respectively for chromosomes 1, 7, 17 and 18. In each case results were compared between dysplastic, tumoral and non-dysplastic cirrhotic cells. Four normal livers were also studied with the same method and served as cytogenetic controls.

RESULTS

All cases of large liver cell dysplasia dysplayed a polysomic population for each investigated chromosome. A high variability of numerical chromosome aberrations was observed with a copy number of chromosomes which ranged from two to more than six. By contrast, only one case of small liver cell dysplasia showed chromosomal anomalies. Numerical aberrations of at least one chromosome were observed in six of the eight hepatocellular carcinoma while the non-dysplastic cirrhosis and normal liver always showed a diploid pattern.

CONCLUSIONS

These results demonstrate that cellular modifications in large liver cell dysplasia coexist with an early acquisition of genomic alterations, supporting the view that these phenotypic changes are preneoplastic.

Quantitative analysis of numerical chromosome aberrations in various morphological types of colorectal carcinomas

Quantitative analysis by fluorescence in situ hybridization (FISH) on thin paraffin-embedded tissue sections, using specific probes for chromosomes 11, 17, and 18 was employed in various morphological types of early and advanced colorectal cancer to clarify tumor cytogenetics. The chromosome index (CI) was calculated as a quantitative measure of the chromosome copy number. Compared with the CI of normal epithelium, the CI of chromosome 11 in villous components of adenomas or polypoid early cancers was decreased, while the CI in flat type or advanced colorectal cancers, conversely, was increased (P < 0.05). The CI of chromosome 17 in villous components of adenomas and all cancers was higher than that of normal epithelium (P < 0.05), but the differences were not significant. In protruding advanced cancers, the CI of chromosome 18 was significantly decreased (P < 0.01) compared to the CI of normal epithelium. There was no significant chromosomal heterogeneity between the superficial and the deepest layer in each cancer. In mucosa adjacent to sessile and flat type cancers, the CI of chromosome 17 was significantly higher than the CI in normal epithelium or adenomas (P < 0.05). These results suggest that numerical chromosome aberrations are associated with the histological type of adenoma and the morphological diversity of cancer in the colorectum, and that chromosome 17 abnormality occurs in mucosa adjacent to sessile and flat cancers.

Clonal origin of trisomy for chromosome 7 in the epithelial compartment of colon neoplasia

In this study, we demonstrated the clonal origin of trisomy for chromosome 7 in epithelial cells of colon neoplasia. By using the double-target fluorescence in situ hybridization (FISH) technique in frozen tissue sections that were also immunostained for keratin and vimentin, ratio analysis of FISH signals for chromosomes 7 and 17 could be performed in epithelial (cytokeratin-positive) or stromal (vimentin-positive) areas. The data demonstrated that trisomy for chromosome 7 is found exclusively in the epithelial compartments and not in the stroma of colon adenocarcinoma. We then demonstrated the occurrence of trisomy for chromosome 7 in the different types of epithelial neoplastic cells, i.e., columnar and goblet cells, which were isolated from frozen tissue sections by mechanical disaggregation of colon tissue and mild lysis of the cells while protease activity was inhibited. In these cell suspensions, the columnar cells were detected with an antibody to villin, and the goblet cells were stained for mucin, whereas all cells were subsequently subjected to FISH for chromosome 7. For analysis of neuroendocrine cells, which are present in a very low frequency in colon neoplasia, frozen tissue sections that were immunostained for Chromogranin A could be used. Individual neuroendocrine cells could be distinguished in these thin frozen tissue sections. The presence of trisomy for chromosome 7 in all three different epithelial cell types strengthens our suggestion that this chromosomal aberration is found in the epithelial stem cell compartment of colon neoplasia.