Measurement of nuclear DNA content in histological and cytological specimens: principles and applications

Aneuploidy and loss of heterozygosity as risk markers for malignant transformation in oral mucosa

The ability to predict malignant transformation in oral potentially malignant disorders would inform targeted treatment, provide prognostic information and allow secondary prevention. DNA ploidy and loss of heterozygosity assays are already in clinical use, and loss of heterozygosity has been used in prospective clinical trials. This review appraises published evidence of predictive ability and explores interpretation of heterogeneous studies, with different diagnostic methods, criteria and intention. Both methods have a sound biological foundation and have predictive value independent of dysplasia grading and clinical parameters. The application of these two techniques cannot be directly compared because of differences in expression of results and application to populations of different risk. Predicting malignant transformation accurately on an individual patient basis is not yet possible with either technique. However, they are valuable applications to stratify patients for inclusion in trials, identify the lowest risk patients and exclude risk when biopsy results are indeterminate for dysplasia.

Trigonelline attenuates hepatic complications and molecular alterations in high-fat high-fructose diet-induced insulin resistance in rats

The present study aimed to evaluate the effect of trigonelline (TRG) on the hepatic complications associated with high-fat high-fructose (HFHF) diet-induced insulin resistance (IR) in rats. IR was induced by giving a saturated fat diet and 10% fructose in drinking water to rats for 8 weeks. Insulin-resistant rats were orally treated with TRG (50 and 100 mg/kg), sitagliptin (SIT; 5 mg/kg), or a combination of TRG (50 mg/kg) and SIT (5 mg/kg) for 14 days. Liver homogenates were used for assessment of hepatic lipids, oxidative stress biomarkers, and inflammatory cytokines. Histopathological and DNA cytometry examinations were carried out for hepatic and pancreatic tissues. Hepatic tissues were examined using Fourier-transform infrared spectroscopy for assessment of any molecular changes. Results of the present study revealed that oral treatment of insulin-resistant rats with TRG or TRG in combination with SIT significantly decreased homeostatic model assessment of IR, hepatic lipids, oxidative stress biomarkers, and the inflammatory cytokines. TRG or TRG in combination with SIT ameliorated the histopathological, DNA cytometry, and molecular alterations induced by a HFHF diet. Finally, it can be concluded that TRG has beneficial effects on the hepatic complications associated with IR due to its hypoglycemic effect and antioxidant potential.

Thioacetamide-induced liver injury: protective role of genistein

This study aimed to investigate the possible protective effects of genistein (GEN), a phytoestrogen, on the liver injury induced in rats by thioacetamide (TTA; 200.0 mg·(kg body mass)(-1); administered 3 times a week by intraperitoneal injection). GEN (0.5, 1.0, or 2.0 mg·(kg body mass)(-1); by subcutaneous injection) was concurrently administered on a daily basis for 8 weeks, and its effects were evaluated 24 h after the administration of the last dose. The results from this study revealed that TTA-induced liver injury was associated with massive changes in the serum levels of liver biomarkers, oxidative stress markers, and liver inflammatory cytokines. Treatment of TAA-induced liver injury in rats with GEN decreased the elevated serum levels of aspartate aminotransferase, alanine aminotransferase, and total and direct bilirubin, and increased the serum level of albumin. GEN also restored the liver levels of malondialdehyde and reduced glutathione, as well as tumor necrosis factor-alpha, interleukin-6, and their modulator nuclear factor kappa-light-chain-enhancer of activated B cells. From our results, it can be concluded that GEN attenuates the liver injury-induced in rats with TAA, and this hepatoprotective role is attributed to its anti-inflammatory and antioxidant properties.

Principles of ploidy analysis by static cytometry

Aims-To examine the basic assumptions made during DNA ploidy analysis of histological sections with an aim to eliminate methodological errors that have lead to conflicting results with this technique.Methods-A rat liver imprint and histological sections together with sections and whole nuclei cytospins of human breast tumour biopsy specimens were stained with azure A Schiff's reagent and used to investigate the effects of computer imaging, histological section thickness, nuclear volume, and shape corrections.Results-The rat liver imprint demonstrated a linear relation between mean nuclear transmittance and nuclear area for each of the three (2C, 4C, 8C) hepatocyte clusters. This finding was used to produce similar, proportional integrated optical density (IOD) measurements from rat liver sections by selecting only nuclei that were sectioned through their centres, as assumed by the mathematics for volume correction. The limitations of computer imaging necessitated an edge (glare) correction for each nucleus so that nuclei of different sizes could be analysed. Shape correction was required to analyse nuclei of different morphologies. Normal human lymphocytes, squamous epithelium and fibroblasts were all measured with similar IODs. DNA ploidy values obtained from 7 mum human breast tumour sections (using lymphocytes as controls) correlated well with those obtained from the whole nuclei cytospins from the same tissue blocks.Conclusions-With an improved understanding of the theoretical and technical aspects of ploidy analysis of tissue sections, reproducible and consistent results are possible. These results can be integrated into routine histopathology investigations alongside immunohistochemistry and molecular diagnostic techniques.

Combination of immunohistochemistry and ploidy analysis to assist histopathological diagnosis of molar diseases

Background:

Differential diagnosis between hydropic abortion, partial mole and complete mole is still a challenge for pathologists but really important for patient management.

Material and Method:

In this study, we have evaluated 111 products of conception from the first trimester. Histological analysis was made according to the main diagnostic histopathological features described in the literature and the cases were categorized in hydropic abortus (HA), partial mole (PM) and complete mole (CM). Immunohistochemistry was performed using monoclonal antibody against p57^kip protein a putative paternally imprinted inhibitor gene and DNA ploidy was analysed in all cases by image cytometry.

Results:

All 23 HAs presented a diploid DNA content and were p57^kip2 positive. From the 28 CMs, 12 cases (43%) were diploid and 16 cases (57%) were tetraploid but no expression of p57^kip2 was found with positive internal controls. From the 60 PMs, 58 cases were positive for p57^kip2 expression and 53 cases (88%) were triploid, 6 cases (10%) tetraploid and 1 case (2%) diploid.

Conclusion:

This study on 111 cases of early pregnancies confirms the usefulness of immunohistochemistry and cytometry but demonstrates the importance of the combination of both techniques to assist histology for the best reliable diagnosis.

Numerical aberrations of chromosomes 1 and 7 by fluorescent in situ hybridization and DNA ploidy analysis in breast cancer

The goals of this study were to detect the numerical alterations of chromosomes 1 and 7 in breast cancer and to correlate the findings with DNA ploidy status as well as with parameters of prognostic significance. Fluorescence in situ hybridization (FISH) with centromeric probes for chromosomes 1 and 7 and cellular DNA content measurement by image analysis-based cytophotometry were applied on interface nuclei from fresh tissue imprints of 59 breast ductal carcinomas. Immunohistochemical stainings for estrogen receptor (ER), progesterone receptor (PR), HER-2, p53, and Ki67 were performed on paraffin tumor sections. The correlation between DNA ploidy and chromosomal aberrations revealed a significant association between aneuploidy and aneusomy for both chromosomes 1 (p=0.002) and 7 (p=0.00001), however, a number of diploid tumors were found to be aneusomic, especially for chromosome 1. Chromosome 7 polysomy was significantly associated with a higher incidence of axillary lymph node metastasis (p=0.05), poorly differentiated (grade III) tumors (p=0.03), negative ER and PR status (p=0.02 and 0.001, respectively), as well as p53 protein expression (p=0.05) and a higher Ki67 labeling index (p=0.004). Chromosome 1 aneusomy was only related with HER-2 protein overexpression (p=0.05). No association between chromosome alterations and tumor size was detected. In conclusion, the results of our study indicate that the detection of numerical aberrations of chromosomes 1 and 7 by FISH seems to be more sensitive than DNA ploidy status for the evaluation of abnormal cellular DNA and chromosome 7 aneusomy characterizes tumors with aggressive features and therefore might be a useful predictor of unfavorable biological behavior in breast cancer.

Étude du contenu en ADN nucléaire dans les nodules thyroïdiens

Thyroid nodules are frequent and sometimes they pose a diagnostic and prognostic problem. DNA ploidy study and cell cycle analysis could be of value in the distinction between benign tumors and malignant tumors. Formalin-fixed and paraffin-embedded tissues from 69 patients with different benign and neoplastic lesions were investigated. Nuclear DNA content in thyroid cells was measured after Feulgen staining using SAMBA 200 image analysis system. A diploid DNA stemline was revealed in 75% of histologically proven benign thyroid tumors (15/20) and aneuploidy was found in 57.2% of malignant tumors (28/49). There is a significant correlation between aneuploidy and extra-thyroid extension (p=0.007) and bilateral and/or mediastinal lymph node metastasis (p=0.02). In the majority of benign tumors (19/20), the proliferation index was lower than 3% (< or =3%) however, this index value was higher than 3% (>3%) in more than 83% of malignant tumors (41/49) (p<0.001). The S phase fraction analysis revealed that the threshold of 14% divide the near whole of benign and malignant tumors (p<0.001). Our findings show that in follicular lesions, proliferation index and S phase fraction study appears interesting and helpful in the distinction between benign and malignant tumors, and aneuploidy seems more interesting in prognosis evaluation of these tumors.

Micronuclei induction, cell cycle delay and apoptosis as markers of cellular stress caused by ursodeoxycholic acid in human lymphocytes

Ursodeoxycholic acid (UDCA) is a bile acid (BA) used for cholesterol gallstone dissolution. Since epidemiological evidence indicates that BAs can be involved in the etiology of colorectal cancer, we investigated the effects of UDCA and its physiologically produced taurine conjugate tauroursodeoxycholic acid (TUDCA) on human lymphocyte cultures in terms of genetic damage in the form of micronuclei (MN) production, cell cycle modifications and induction of apoptosis. With respect to controls, treatment with UDCA (from 10 microg/ml) caused a dose-related increase in MN, whereas TUDCA caused no significant increase (up to 1000 microg/ml). Fluorescence in situ hybridization (FISH) analysis using pancentromeric probes suggested that UDCA exerts aneugenic activity. Bromodeoxyuridine/Hoechst flow cytometry showed that both BA significantly inhibit cell cycle progression (UDCA at 100 microg/ml, and TUDCA, more markedly at 300-1000 microg/ml). Neither UDCA nor TUDCA affected induction of apoptosis, as evaluated by the Annexin-V-Fluos assay. We conclude that UDCA is potentially genotoxic. However, taking into account the characteristics of other physiological BA, our findings are in line with the concept that long-term UDCA treatment may be safely administered. The multi-assay approach reported here could be useful in the toxicological evaluation of newly developed BA analogs as candidates for pharmacological use.

DNA image cytometry in the differential diagnosis of endocervical adenocarcinoma

BACKGROUND

The value of DNA image cytometry in the differential diagnosis of endocervical adenocarcinoma was tested on a series of 65 cases of normal endocervical cells (n = 25), inflammatory changes (n = 18), and endocervical adenocarcinoma (n = 22).

METHODS

The investigation was performed on gynecologic routine smears by using a television image analysis system MIAMED-DNA (Leica, Wetzlar, Germany), combined with an automated Leica Medilux microscope. First, the Papanicolaou stained specimens were rescreened, and the x/y coordinates of at least 150 endocervical nuclei were stored per case by using a scanning program. After restaining according to Feulgen, the epithelial cells were relocalized and the DNA content, and the nuclear area were determined. The DNA content of 25-30 squamous epithelial cells of intermediate type served as an internal standard for the normal diploid value in each case. Various DNA cytometric parameters and the mean nuclear area were calculated. For statistical analysis, the cases of adenocarcinoma (n = 22) were defined as positive, and the cases with normal endocervical epithelium or inflammatory changes (n = 43) were defined as negative.

RESULTS

The presence of nuclei with a DNA content greater than 9c was observed exclusively in adenocarcinoma (sensitivity, 95.9%; specificity, 100%), indicating that this parameter is suited best for the differentiation between malignant and nonmalignant endocervical epithelium. High sensitivity rates at a specificity level of 100% also were calculated for the 2.5cER (95.5%), the mean ploidy (90.9%), 5cER (90.9%), and the diploid deviation quotient (90.9%). For the 2cDI (86.4%), the entropy (81.8%) and the ploidy imbalance (77.3%) lower values were obtained.

CONCLUSIONS

DNA single cell cytometry represents a highly relevant tool in the identification of malignant transformation in endocervical lesions that could be used as a complementary diagnostic method in cytologically difficult cases. Investigations on endocervical adenocarcinoma in situ should be performed in the near future.

DNA Ploidy Pattern in Pure Seminomas

Nuclear extract and image cytometry was used to determine the DNA ploidy pattern of 31 pure seminomas. At least 5-year but usually 10-year follow-up was available to compare the clinical outcome to the DNA ploidy pattern. In 24 cases (77.4%) the DNA indexes (DI) showed tetraploid (1,8 < DI < 2,2) pattern confirming the recent cytogenetic and flow cytometric DNA studies of others. However, in 7 cases (22,6%) the tumors were aneuploid. Out of these aneuploid cases 2 had two subpopulations and 2 had less than 1,8 DI. These latter cases (providing the loss of chromosomal DNA) had elevated AFP levels in serum that raises the question of nonseminomatous transformation without any morphological evidence. Usually, the aneuploid cases had worse prognoses but there was no significant difference. Because of the small number of aneuploid cases wider clinicopathologic studies are required to confirm our results.

Influence of melatonin on proliferation and antioxidant system in Ehrlich ascites carcinoma cells

The effects of oral supplementation of melatonin on growth of Ehrlich ascites carcinoma (EAC) cells implanted intraperitoneally in female mice were studied. Melatonin at 50 mg/kg body wt. reduced the viability and volume of Ehrlich ascites carcinoma cells and increased the survival of the treated mice. No significant change in intracellular reduced glutathione (GSH) content in EAC cells was observed indicating that GSH was not involved in the inhibitory effect of melatonin. The activity of glutathione-S-transferase in EAC cells was significantly increased. Flow cytometirc studies showed that melatonin not only delayed the progression of cells from G(0)/G(1) phase to S-phase of the cell cycle but also reduced DNA synthesis during cell cycle. In addition, the aneuploidy status was depressed in melatonin treated mice. Based on these data and the reduced viability in both in vitro and in vivo, it is suggested that melatonin might induce apoptosis in EAC cells.

In vitro reactions of human osteoblasts in culture with zirconia and alumina ceramics

The biocompatibility of two implantable materials, zirconia and alumina ceramics, was investigated in vitro using human osteoblast cell cultures. The viability of osteoblast cells with the materials was evaluated by the methylthiazole sulfate test that revealed an absence of any cytostatic or cytotoxic effect. Cell proliferation kinetic and total protein synthesis in osteoblasts with zirconia or alumina were similar to that observed in control cells cultured on glass coverslips. Light and scanning electron microscopic examinations showed an intimate contact between osteoblasts and the substrates; well-spread cells were observed on the surfaces of both materials. Adhesion ability and morphological characteristics were preserved in osteoblast cultures with these substrates. Moreover, immunohistochemical staining in osteoblasts with zirconia and alumina showed the capacity of these cells to elaborate the extracellular matrix composed of types I and V collagen, osteocalcin, osteonectin, bone sialoprotein, and cellular fibronectin. Finally, DNA image cytometry and interphase silver-nucleolar organizer regions quantification were applied as complementary biocompatibility tests to detect any changes in DNA synthesis and cell proliferation, respectively. The results showed that neither material altered cell ploidy or cell growth rate in accordance with the absence of any inducing effect on DNA synthesis or proliferation.

In vitro reactions of human osteoblasts in culture with zirconia and alumina ceramics

The biocompatibility of two implantable materials, zirconia and alumina ceramics, was investigated in vitro using human osteoblast cell cultures. The viability of osteoblast cells with the materials was evaluated by the methylthiazole sulfate test that revealed an absence of any cytostatic or cytotoxic effect. Cell proliferation kinetic and total protein synthesis in osteoblasts with zirconia or alumina were similar to that observed in control cells cultured on glass coverslips. Light and scanning electron microscopic examinations showed an intimate contact between osteoblasts and the substrates; well-spread cells were observed on the surfaces of both materials. Adhesion ability and morphological characteristics were preserved in osteoblast cultures with these substrates. Moreover, immunohistochemical staining in osteoblasts with zirconia and alumina showed the capacity of these cells to elaborate the extracellular matrix composed of types I and V collagen, osteocalcin, osteonectin, bone sialoprotein, and cellular fibronectin. Finally, DNA image cytometry and interphase silver-nucleolar organizer regions quantification were applied as complementary biocompatibility tests to detect any changes in DNA synthesis and cell proliferation, respectively. The results showed that neither material altered cell ploidy or cell growth rate in accordance with the absence of any inducing effect on DNA synthesis or proliferation.

Interphase cytogenetic and AgNOR analyses of hydatidiform moles

AIM

To determine the potential value of interphase cytogenetic and argyrophilic nucleolar organiser region (AgNOR) analyses in the diagnosis and classification of hydatidiform moles.

METHODS

Serial tissue sections from 37 hydatidiform moles, histologically classified as 11 complete and 15 partial, and from 11 hydropic abortuses were examined by in situ hybridisation using digoxigenin labelled probes specific for chromosomes 1, X, and Y, and a one step silver staining method. The percentages of diploid and triploid nuclei, and the mean number of AgNORs for each tissue were determined.

RESULTS

Interphase cytogenetics showed that eight of the 11 cases (73%) each of complete mole and hydropic abortus had diploid pattern and the three remaining cases (27%) of each group were triploid. Two of the triploid complete moles and one of the triploid hydropic abortuses were revised to partial moles and one remaining triploid complete mole was revised to hydropic abortus. Of the 15 partial moles, nine (60%) were triploid, and six (40%) were diploid. These diploid cases were revised to three complete moles and three hydropic abortuses. There was a significant difference (p < 0.0001) between the mean (SD) AgNOR count in partial mole (5.11 (0.91)) versus hydropic abortus (3.79 (0.90)) and complete mole (3.39 (0.97)). The total of 15 triploid cases showed a high mean AgNOR count of 5.24 (0.73). Also, after reclassification, eight of the nine partial moles (89%) had a mean AgNOR count of > or = 5. The results of analyses by the two methods were closely correlated.

CONCLUSIONS

Interphasecytogeneticanalysis using chromosome specific probes and AgNOR count provides a valuable approach for ploidy analysis in histological sections of hydatidiform moles and helps to resolve difficult cases.

Cell cycle-dependent expression of a glioma-specific chloride current: proposed link to cytoskeletal changes

We recently demonstrated expression of a novel, glioma-specific Cl- current in glial-derived tumor cells (gliomas), including stable cell lines such as STTG1, derived from a human anaplastic astrocytoma. We used STTG1 cells to study whether glioma Cl- channel (GCC) activity is regulated during cell cycle progression. Cells were arrested in defined stages of cell cycle (G0, G1, G1/S, S, and M phases) using serum starvation, mevastatin, hydroxyurea, demecolcine, and cytosine beta-D-arabinofuranoside. Cell cycle arrest was confirmed by measuring [3H]thymidine incorporation and by DNA flow cytometry. Using whole cell patch-clamp recordings, we demonstrate differential changes in GCC activity after cell proliferation and cell cycle progression was selectively altered; specifically, channel expression was low in serum-starved, G0-arrested cells, increased significantly in early G1, decreased during S phase, and increased after arrest in M phase. Although the link between the cell cycle and GCC activity is not yet clear, we speculate that GCCs are linked to the cytoskeleton and that cytoskeletal rearrangements associated with cell division lead to the observed changes in channel activity. Consistent with this hypothesis, we demonstrate the activation of GCC by disruption of F-actin using cytochalasin D or osmotic cell swelling.

Use of flow cytometry in the analysis of stage III squamous cell carcinoma of the oesophagus and its association with MIB-1

AIMS

To examine the prognostic and pathobiological importance of DNA content in oesophageal squamous cell carcinomas in Hong Kong Chinese subjects; to evaluate its association with the immunohistochemical proliferative marker MIB-1.

METHODS

Paraffin wax embedded tumour tissue and adjacent normal tissue (control tissue) samples from 45 resected stage III oesophageal squamous cell carcinomas were studied using flow cytometric analysis. The DNA content and the clinicopathological data of these patients were analysed together with the MIB-1 labelling index.

RESULTS

DNA aneuploidy was present in 14 (31%) of the 45 cases. However, the DNA content did not correlate significantly with the age, sex, or survival of the patients, nor the length, location, differentiation and MIB-1 labelling index of the oesophageal carcinomas. The synthetic (S) phase fraction of diploid tumours bore no relation to the patients' survival or MIB-1 score.

CONCLUSIONS

Flow cytometry was not as useful as the MIB-1 labelling index in predicting the biological characteristics of the tumours and the prognosis of patients with oesophageal squamous cell carcinomas. This study does not support the routine use of DNA flow cytometric analysis in oesophageal cancers.

p53 mutation, allele loss on chromosome 17p, and DNA content in ovarian carcinoma

The aim of this investigation was to explore the relationships between p53 mutation, DNA aneuploidy, 17p deletions, and clinical stage in ovarian cancer. Nuclear suspensions were obtained by tissue disaggregation, stained with propidium iodide, and analysed on a Coulter EPICS Elite flow cytometer. DNA cell cycle analysis was performed using Multicycle software (Phoenix Flow Systems). DNA extracted from paraffin-embedded archival carcinomas/non-tumour tissue was used as template for PCR amplification of the microsatellite dinucleotide repeat polymorphism D17S513, a locus telomeric to p53 on 17p13.1. Allele loss at D17S513 was detected in 64.5 per cent of carcinomas (20 of 31 informative cases). DNA aneuploidy was detected in 20 of 54 (37 per cent) carcinomas. Eight of ten cases previously shown to harbour p53 mutations showed aneuploid DNA content. Although ten other DNA aneuploid cases had shown no p53 mutations, the results show a statistically significant association between p53 mutation and DNA aneuploidy (P < 0.01). Furthermore, the mean DNA index of the DNA aneuploid cases was significantly higher in p53 mutant cases compared with those showing no p53 mutation (P = 0.02). There was also a significant association between p53 mutations and stage, between ploidy and stage, and between allelic deletions at D17S513 or p53 and stage, but not between these allelic deletions and ploidy. p53 mutations appear to be associated with DNA aneuploidy in ovarian cancer independently of 17p deletions. p53 mutations, DNA aneuploidy, and 17p deletions are associated with late stage.

Comparison of ploidy analysis by flow cytometry and image analysis in hydatidiform mole and non-molar abortion

Determination of DNA ploidy is useful in the diagnosis and classification of hydatidiform mole. Most reports of ploidy analysis in molar tissue have used DNA flow cytometry. Although image analysis cytometry offers theoretical advantages over flow cytometry, there have been few reports of ploidy analysis by image analysis in hydatidiform mole. We selected 47 cases and measured DNA ploidy by flow cytometry and image analysis cytometry in complete hydatidiform mole, partial hydatidiform mole and non-molar abortion. The two cytometry modalities were compared using kappa statistics. There was reasonable overall agreement between the two modalities (kappa = 0.69) and when ploidy was stratified into diploid/polyploid and triploid categories there was near perfect agreement (kappa = 0.93). Aneuploid cell populations, which were not evident on flow cytometry, were identified by image analysis in a significant proportion of complete and partial hydatidiform moles and in a small number of non-molar abortions. Flow cytometry and image analysis cytometry yield comparable ploidy information, useful in the diagnosis and classification of hydatidiform mole. Image analysis cytometry offers greater sensitivity in the detection of small non-diploid cell populations but the significance of this latter finding is uncertain.

Interobserver variation in cell selection for DNA image cytometry

AIMS

To describe a systematic investigation of interobserver differences in interpretation of nuclear morphology in preparations of small cell lung cancer (SCLC).

METHODS

The screening/reviewing facility on the highly optimised microscope environment was used to individually tag 127 nuclei, chosen to reflect the spectrum of morphological appearances in nuclear preparations from three biopsy specimens of SCLC. Each nucleus was reviewed and labelled as control (lymphocyte), malignant or unsatisfactory by each of four observers. DNA histograms were plotted for each specimen using the nuclei identified as malignant by each participant. The histograms were compared in terms of identification of DNA stemlines and by calculation of a 5c exceeding rate (5cER).

RESULTS

Interobserver variation in assessment of morphology was seen in 55.1% of nuclei. Disagreement occurred most frequently in the malignant/unsatisfactory category. Differences in morphological classification had little influence on histogram assessment by means of visual inspection but did show an effect on 5cER.

CONCLUSIONS

There are significant interobserver differences in subjective assessment of nuclear morphology in cytometric preparations. This effect may seriously influence cytometric measurements.