Dual-color Fluorescence In Situ Hybridization Research Articles

Fluorescence in situ hybridization analysis of allelic losses involving the long arm of chromosome 17 in NF1-associated neurofibromas

Neurofibromatosis type 1 (NF1) is a common autosomal dominant condition associated with germline mutations of the NF1 gene located at chromosome band 17q11.2. Molecular analysis of a number of NF1-specific tumors has shown the inactivation of both NF1 alleles during tumorigenesis, supporting the tumor suppressor hypothesis for the NF1 gene. Using interphase dual-color fluorescence in situ hybridization (FISH) technique on paraffin-embedded tissues, we studied 11 plexiform, 4 cutaneous, and 6 subcutaneous neurofibromas. Cytogenetic analysis was conducted using two probes, one specific for the NF1 region (RP11-229K15) and one for the centromeric region of chromosome 17 as control. No large somatic deletions were found. Only in one of the plexiform neurofibromas loss of a whole chromosome 17 was observed. If we assume that dual-color FISH analysis is sensitive enough to detect the majority of large somatic deletions present, then other mutational mechanisms affecting the NF1 gene are probably involved in neurofibroma formation, and other tumor suppressor genes may play an important role in NF1 tumorigenesis.

Use of interphase fluorescence in situ hybridization in prostate needle biopsy specimens with isolated high-grade prostatic intraepithelial neoplasia as a predictor of prostate adenocarcinoma on follow-up biopsy

Isolated high-grade prostatic intraepithelial neoplasia (HGPIN) on needle biopsy confers an increased risk of prostate carcinoma (CaP) on follow-up biopsy. The aim of this study is to determine whether paraffin-section fluorescence in situ hybridization (FISH) of specific chromosome/oncogene copy number abnormalities (CNAs) in biopsy specimens with isolated HGPIN increases the predictive value for CaP on repeat biopsy. Cases were divided into 3 groups: controls (n = 8) and sextant biopsy specimens with isolated HGPIN without CaP (group A; n = 11) and with CaP (group B; n = 14) on follow-up biopsy. Dual-color FISH assessing c-myc, HER-2/neu, chromosome region 7q31 (D7S486), and corresponding chromosome centromeres was performed. An amplification ratio (AR) for each marker centromere was derived for each biopsy specimen, with AR ranges designated as no/low, low-intermediate, and high. Also calculated for each marker were the percentage of cells with marker amplification, hyperdiploidy, and monosomy. A composite score for each biopsy specimen was calculated based on these parameters, with a possible range of 0 to 15. The specific chromosomal oncogene CNAs were as follows: for chromosome 7/7q31, 2 of 11 (18%) in group A and 6 of 14 (43%) in group B; for chromosome 8/ c-myc, 4 of 11 (36%) in group A and 9 of 13 (69%) in group B; and for chromosome 17/ HER-2/neu, 10 of 10 (100%) in group A and 13 of 14 (93%) in group B. The mean composite score was 0 for controls, 2.5 for group A, and 4.7 for group B. Composite scores ≥4 for the 3 groups were 0 of 9 (0%) for controls, 1 of 11 (12%) for group A, and 8 of 14 (57%) for group B. These differences were statistically significant ( P = 0.015). One group A patient with a high composite score (6) had atypical small glands on follow-up biopsy at <1 year. Chromosome/oncogene CNAs are uncommon in control patients, occurring with increasing frequency and magnitude in patients with isolated HGPIN without and with follow-up CaP. Chromosome/oncogene CNAs in HGPIN are mostly of the low to intermediate level and display intercellular heterogeneity. HER-2/neu amplification is common in HGPIN with and without follow-up CaP. Chromosome 7 and 8 aneusomy and 7q31 and c-myc amplification are greater in HGPIN with follow-up CaP. Patients with isolated HGPIN and high composite score without follow-up CaP are uncommon; these patients may have a small, unsampled CaP. Although patients with HGPIN without CaP are more likely to have a low composite score, a subset of patients with follow-up CaP have low composite score, suggesting (1) mutational pathways independent of chromosomes 7, 8, and 17 and HER-2/neu, c-myc, and chromosome region 7q31 CNAs; (2) CaP derived from an independent, unsampled focus of HGPIN; or (3) CaP not derived from HGPIN.

Increased amplification proximal to the MLL gene in acute myeloid leukemia

Amplification of the chromosomal region 11q23 encompassing the MLL gene has been observed in patients with acute myeloid leukemia (AML). Patients with this abnormality often have a poor response to chemotherapy and short survival. We have studied the regions flanking the MLL gene using 8 bacterial artificial chromosome (BAC) probes and dual color fluorescence in situ hybridization (FISH) analysis. Two contigs of BAC probes flanking the MLL gene, were constructed by standard primer walking and BAC end sequencing. For comparison, metaphase chromosome preparations were also hybridized with a commercial MLL specific probe. Metaphase chromosomes were prepared from the bone marrow sample of an 80-year old female patient with AML-M1 and the cytogenetic aberration der(11)hsr(11) (q23). FISH analysis on metaphase chromosomes showed amplification on the homogeneously staining region (hsr) and marker chromosomes for both the MLL gene and the BAC probes. Using dual color FISH, probes proximal to MLL showed greater amplification than those distal to MLL, as represented by additional red signals on both metaphase and interphase chromosomes. Ratios of the copy numbers of the BAC probes relative to the chromosome 11 centromere copy number confirmed a higher copy number for probes proximal to MLL. These results suggest that other gene(s) proximal to MLL could be the target gene(s) of amplification in this case and not the MLL gene as previously assumed.

Regeneration of heart muscle tissue: quantification of chimeric cardiomyocytes and endothelial cells following transplantation.

Persuasive evidence has been recently provided that adult bone marrow (BM) cells exert greater plasticity than previously assumed. This review is focused on the quantification of mixed chimerism (mCh) in the hearts (cardiomyocytes and endothelial cells) of patients after orthotopic heart to heart transplantation (HHT) in comparison to full (unmanipulated) allogeneic BM and peripheral blood stem cell (PBSC) transplants. Following a sex-mismatched transplantation constellation heart muscle tissue obtained at autopsy was examined. Evaluation of mCh was most often performed by immunophenotyping combined with fluorescence in-situ hybridization (FISH) applying x- and y-chromosome-specific DNA probes. When comparing our data with the results of former studies that were regularly based on the detection of the y-chromosome alone, the quantity of chimeric cardiomyocytes after HHT ranged from 0% to 9%. On the other hand, after full BM transplantats (chimeric) cardiomyocytes of donor-type origin appeared at an incidence between 0.23% to 6.4%. These disturbing inconsistencies were assumed to be related to methodology: the restriction to the y-chromosome, disregard of the plane of section (detection sensitivity ranging between 35% and 67%) and state of tissue preservation (cadaver hearts). Therefore, when strictly applying dual color FISH and limiting the recognition of chimeric cardiomyocytes and endothelial cells to the presence of two distinctive signals detection sensitivity was significantly enhanced. Contrasting a total congruence with the genotyping in control specimens of normal cadaver hearts, a striking disparity in the extent of mCh was found depending on the different modes of transplantation. After allografting with PBSC a considerably low incidence (1.6%) of chimeric cardiomyocytes was determined contrasting with 5.3% of donor-derived cells after full BM transplants. Following HHT host-type endothelial cells (16.2%) of the intramural and subepicardial vessel walls were more often encountered than following BM and PBSC allografting. These findings are in keeping with the assumption of a sprouting and migration of vascular structures into the donor heart from the site of surgical aligment and injury between retained host and donor atrial walls. When considering the other methods of transplantation (BM, PBSC) the data on chimeric endothelial cells support the hypothesis of a common hemangioblast. Concerning the cardiomyocytes it seems most reasonable to assume that primitive mesenchymal stem cells of the BM play a pivotal role in the development of mCh. This phenomenon is more extensively expressed than previously expected and may be related to an enforced repair of the damaged myocardium during the post-transplant period as the sequel of myeloablative (cardiotoxic) conditioning.

Comparative physical mapping of rice BAC clones linked to resistance genes Glh, Bph-3 and xa-5 in Oryza sativa L. and O. granulata Nees et Arn. ex Watt.

Oryza granulata Nees et Arn. ex Watt, is one of the three wild relatives of rice, which are the most valuable for study and utilization in China. In this study, the homology and physical locations of three rice resistance genes, Glh, Bph- 3 and xa- 5 are comparatively analyzed between O. sativa and O. granulata by Southern blotting and fluorescence in situ hybridization (FISH). The results of Southern blotting indicate that there exist homologous sequences of the tested RFLP markers in O. granulata. By using three bacterial artificial chromosome (BAC) clones scanned by the tested RFLP as probes, FISH signals are detected on both mitotic and pachytene chromosomes in O. sativa and O. granulata. Dual-color FISH demonstrates that two of the three BAC clones (14E16 and 38J9) are located on the short arm of the same chromosome pair in O. granulata. Additionally, colinearity is shown for the two clones between O. sativa and O. granulata. Another BAC clone 44B4 is located on the end of the short arm of other chromosome pair in these two species. Although the phylogenetic relationship between O. sativa and O. granulata is the most distinct in Oryza and these two species have evidently different biological features and ecological habits, the relative lengths and arm ratios of the detected chromosomes and the relative positions of the tested clone signals on chromosomes in O. granulata are quite similar to those in O. sativa.

Detection by dual color fluorescence in situ hybridization of in vivo chromosome damage in rat hepatocyte nuclei.

Our previous study using a multicolor fluorescence in situ hybridization (FISH) technique revealed that region-specific DNA probes for rat chromosome 1 enabled the detection of structural chromosome damage in rat interphase nuclei from peripheral blood and bone marrow cells. In the present study, this FISH technique was modified for application to a non-hematopoietic organ (liver) and the usefulness of the system was tested using diethylnitrosamine (DEN) as a model hepatocarcinogen. Male Sprague-Dawley rats were orally treated once with DEN at 200 mg/kg. Their livers were removed at 4, 7 or 14 days after treatment and homogenized with a tissue grinder to isolate hepatocyte nuclei. The nucleus suspension was fixed in methanol:acetic acid and air dried. Dual color FISH with two probes, one labeled with tetramethylrhodamine and one with digoxigenin, demonstrated that the maximum increase in the frequency of nuclei with spatially abnormal signals was observed 7 days after treatment. A dose-response relationship for induction of abnormal nuclei was observed. This improved dual color FISH system is potentially valuable for assessing in vivo clastogenicity in all rat organs.

Spindle assembly checkpoint defects and chromosomal instability in head and neck squamous cell carcinoma.

Alterations in chromosomal number and structure are found in most solid malignancies including head and neck squamous cell carcinoma (HNSC), however, the presence of ongoing, chromosomal instability in HNSC and its relation to spindle assembly checkpoint defects has not been formally demonstrated. We investigated the status of chromosomal instability (CIN) in HNSC primary tumors and cell lines as well as spindle assembly checkpoint integrity in HNSC cell lines. Centromeric fluorescence in situ hybridization (FISH) was carried out on expanded single cell-derived colonies from HNSC cell lines and primary HNSC touch preparations. The deviation of chromosomes from the modal number in single cell derived colonies was 18.4-27% in 6 HNSC cell lines, and 2-3% in a control cell line, HCT116. Twelve primary tumors and 4 normal controls were also studied; all primary tumors demonstrated significant deviation from the modal chromosomal number (average 33.7%, range = 29.9-43.9%), compared to normal controls (average 4.6%, range = 3.6-5.6%). Additional characterization of the rate of chromosomal breakage was carried out by dual color FISH simultaneously using centromeric and telomeric probes for individual chromosomes on expanded singe cell-derived colonies and primary HNSC. Control HCT 116 colonies demonstrated a mean discordance between number of centromeric and telomeric hybridization signals in 21% (range = 19-23%) of cells, whereas HNSC cell line colonies demonstrated a mean discordance of 50% (range = 38-55%), with the majority of instances of discordant signal indicating telomeric loss. Similarly, touch preparations from primary HNSC demonstrated discordance in hybridization signal of centromeric vs. telomeric signal of 26.3% (range = 18.5-42%), with normal controls showing a rate of discordance of 6.4% (range = 4-8%). Finally, all 6 HNSC cell lines demonstrated partial impairment of mitotic arrest in response to nocodazole, indicating that impairment of the spindle assembly checkpoint may contribute to chromosomal instability in HNSC. Ongoing instability in chromosomal number and structure are consistent features of primary HNSC and cell lines. Spindle assembly checkpoint impairment occurs in HNSC cell lines and may contribute to chromosomal instability in HNSC.

HER-2/neu assessment in primary chemotherapy treated breast carcinoma: no evidence of gene profile changing.

HER-2/neu protein expression and gene amplification were analyzed in a series of 85 consecutive breast carcinoma patients entered into an adriamicin/taxol primary chemotherapy trial followed by surgery, 45 of whom underwent pre-treatment fine needle aspirate (FNA). Dual color FISH (fluorescent in situ hybridization) assay revealed high-level HER-2/neu gene amplification in the immunocytochemistry (ICC) indicated 3+ cases and no, low or moderate amplification in the ICC 2+ group, consistent with previous findings in untreated patients series. Results obtained with the ICC assay CB 11 showed higher overall concordance with FISH than did the Herceptest ICC assay, but CB 11 was less accurate than Herceptest in terms of selecting patients suitable for Herceptin treatment, which is currently restricted to ICC 3+/FISH amplified patients. The only ICC 3+ low-level amplified case (non-amplified according the two more stringent criteria applied) was found with the CB 11 assay. Comparison between pre-treatment smears and post-treatment sections by FISH revealed no significant changes in the HER-2/neu gene profile. In the clinical setting these findings point to the usefulness of HER-2/neu assessment in chemotherapy-treated patients, when pre-treatment material is unavailable.

Detection of embryo sex chromosome by dual color fluorescent in-situ hybridization.

In order to evaluate the effects of sex chromosomal mosaicism on the accuracy of single-cell gender diagnosis, sex chromosomes of 21 normal fertilized embryos were detected by dual color fluorescent in-situ hybridization (FISH). The results showed that 4 embryos had sex chromosomal mosaicism (19%) and the remaining 17 showed uniformly XX or XY signals in all blastomeres. In conclusion, identification of sex by dual color FISH analysis of a single cell was accurate and efficient, and sex chromosomal mosaicism would not affect preimplantation gender diagnosis.

Rapid prenatal diagnosis in translocation carriers by interphase FISH with chromosome-specific subtelomere probes.

Interphase fluorescence in situ hybridization (FISH) analysis can provide rapid preliminary analysis of chromosome aneuploidy from direct amniocyte and chorionic villus sample (CVS) preparations. Typically, interphase FISH is used in screening for numerical abnormalities of chromosomes X, Y, 13, 18, and 21. More recently, FISH probe sets became available for the subtelomeric region of each chromosome, allowing screening for terminal chromosome rearrangements. The purpose of the current study was to evaluate the use of dual-color interphase FISH analysis with chromosome-specific subtelomere probes for rapid prenatal diagnosis in 14 pregnancies from 12 different translocation carriers. Interphase FISH analysis was performed on direct CVS or amniocyte preparations from 12 reciprocal translocation and two Robertsonian translocation pregnancies with the appropriate chromosome-specific subtelomere probes for each chromosome involved in the translocation. Analysis of the interphase FISH probe signals predicted balanced or normal segregants in each case, thus rapidly excluding a chromosomally unbalanced segregant. Subsequent metaphase analysis showed normal karyotypes in seven fetuses and balanced translocations in the remaining seven. This series illustrates the utility of interphase FISH analysis with chromosome-specific subtelomere probes for rapid prenatal diagnosis in cases of parental reciprocal translocations and Robertsonian translocations.

The abnormalities of chromosome 8 in two hepatocellular carcinoma cell clones with the same genetic background and different metastatic potential.

Two hepatocellular carcinoma (HCC) cell clones named MHCC97-H and MHCC97-L with different metastatic potential have recently been established from the same parent cell line MHCC97 in our institute. The cytogenetic alterations of these two clones were investigated in this study to explore the possible clues to the mechanism involved in HCC metastasis. Their chromosomal aberrations were analyzed with comparative genomic hybridization (CGH), chromosome-specific painting, and two-color fluorescence in situ hybridization (FISH). The aberrations were found in a total of 17 chromosomes, and six kinds of the aberrations including gains of 1q, 7q, 8q, 20, and the losses of 8p23, 21q were found both in the two cell clones and their parent cell line MHCC97. Using modified CGH, with the DNA of MHCC97-L as control to test the MHCC97-H clone, the loss of 8p23 and the gain of 1q31-32, 8q21.3-22, 13q22, 17q22 were highlighted, and the most significant finding was on chromosome 8. Dual color FISH combining a pericentromeric probe and a BAC probe mapping at 8q23.1 was then performed to verify this result, and the signal ratios of the BAC to centromere were 1.43 in MHCC97-H and 1.45 in MHCC97-L, confirming the over-representations at 8q in both cells. Another interesting finding in the dual-color metaphase FISH was the intrachromosomal translocation of 8q to 8p (looked like an isochromosome 8) and non-reciprocal translocation of part of 8q to 4q, which was further clarified and proved by the FISH with whole chromosome 8 painting probe. The high copies amplification on 8q, the formation of isochromosome 8, non-reciprocal translocation of partial 8q to 4q, and loss of 8p occurred at the same time and are the characteristic chromosomal aberrations of the two cell clones. The chromosome 8p, especially 8p23, might harbor some novel genes related to the HCC metastasis.

The allelic loss of chromosome 3p25 with c-myc gain is related to the development of clear-cell renal cell carcinoma.

To explore the role of allelic losses at 3p25 and genetic alterations of chromosome 8, we investigated the relationships between genetic alterations in these chromosomal regions and clinicopathologic findings (such as tumor size and grade), by employing fluorescence in situ hybridization (FISH). Fifty Japanese clear-cell renal cell carcinomas (RCCs) were examined by dual-color FISH using cosmid DNA probes for 3p25.1-25.3 combined with probes for chromosome 3 centromere, 8p12, 8p21.1, 8p21.3, 8p22 and 8q24.12-24.13 (c-myc), and chromosome 8 centromere. Deletion at 3p25.1-25.3 was detected in 38 patients (76%), while 8p12 deletion, 8p21.1 deletion, 8p21.3 deletion, 8p22 deletion and c-myc gain were detected in 23 (46%), 25 (50%), 25 (50%), 25 (50%), and 20 patients (40%), respectively. There was a significant correlation between 8p21.1 deletion, 8p21.3 deletion and 8p21.1 deletion with c-myc gain and tumor grade (p = 0.04, 0.04 and 0.02, respectively). Deletions at 8p21.1 and 8p21.3 with 3p deletion were significantly related to tumor grade; the statistical significance was identical to that of sole 8p deletion with tumor grade. The deletion at 3p25.1-25.3 with c-myc gain showed a significant correlation with tumor size, indicating an association with tumor progression. Our results suggest that the allelic loss of chromosome 3p25 with c-myc gain is related to the development of clear-cell RCC.

Multi-locus (ML)-FISH is a reliable tool for nondisjunction studies in human oocytes

In the present study, we developed a fluorescence in situ hybridization (FISH) strategy, which allows a reliable determination of the chromatid number of specific chromosomes in mature human oocytes. 168 unfertilized oocytes were analyzed by dual-color FISH with two direct-labeled locus-specific DNA probes for chromosome 13 and 21. To exclude FISH failures, metaphases with abnormal signal patterns were reanalyzed by multi-locus-FISH (ML-FISH) for chromosome 13 and 21. Following dual-color FISH, abnormal signal patterns were detected in 21 out of 108 metaphases (19.4%). 17 of these metaphases were reanalyzed by ML-FISH. In contrast to the first FISH, seven metaphases showed normal signal patterns after rehybridization, whereas ten metaphases remained abnormal. Out of these real aneuploid metaphases, five showed gain or loss of a single signal (= chromatid), two showed missing double signals (= chromosome) and three showed both. In conclusion, locus-specific FISH probes facilitate differentiation between first meiotic nondisjunction of whole chromosomes and prematurely divided chromatids. Moreover, simultaneous hybridization with a second locus-specific probe on the same chromatid (ML-FISH) helps to differentiate between FISH failures and real meiotic division errors and therefore, allows a more reliable analysis of aneuploidies in human oocytes.

Detection of t(11;18)(q21;q21) in marginal zone lymphoma of mucosa-associated lymphocytic tissue type on paraffin-embedded tissue sections by using fluorescence in situ hybridization

A chromosomal t(11;18)(q21;q21) recurrently found in marginal zone lymphomas of mucosa-associated lymphocytic tissue (MALT) type is one of the key determinants of their treatment and outcome because t(11;18)-positive cases are resistant to Helicobacter pylori eradication therapy. To detect t(11;18) on paraffin-embedded tissue sections, we established a method of dual-color fluorescence in situ hybridization (D-FISH) using DNA probes directly labeled with SpectrumGreen and SpectrumOrange (tissue-FISH [T-FISH]). T-FISH detected the t(11;18) as colocalized signals between the band-specific yeast artificial chromosome (YAC) clones y966e4 (11q21) and y943b8 (18q21) on the der(11)t(11;18). The t(11;18) was detected in four of 22 patients with marginal zone lymphoma of MALT type in 72%–78% of the cells. In both patients studied, the percentage of t(11;18)-positive cells was much higher in tissue-FISH analysis than in interphase-FISH: 74% versus 30% in patient 1 and 75% versus 31% in patient 4. None of the 12 patients with diffuse large B-cell lymphoma of the stomach showed the t(11;18). Tissue-FISH is a powerful tool for the diagnosis of marginal zone lymphoma of MALT type because it can be applied not only to small specimens obtained from endoscopic biopsy samples but also to archival materials, hence facilitating the delineation of subtypes in marginal zone lymphoma of MALT type.

Detection of illegitimate rearrangements within the immunoglobulin light chain loci in B cell malignancies using end sequenced probes.

Translocations involving the immunoglobulin loci are recurring events of B cell oncogenesis. The majority of translocations involve the immunoglobulin heavy chain (IGH) locus, while a minor part involves the immunoglobulin light chain loci consisting of the kappa light chain (IGK) located at 2p11.2 and the lambda light chain (IGL) located at 22q11.2. We characterised BAC clones, spanning the IGK and IGL loci, for detection of illegitimate rearrangements by fluorescence in situ hybridisation (FISH). Within the IGL region we have identified six end sequenced probes (22M5, 1152K19, 2036J16, 3188M21, 3115E23 and 274M7) covering the variable (IGLV) cluster and two probes (165G5 and 31L9) covering the constant (IGLC) cluster. Within the IGK region four probes (969D7, 316G9, 122B6 and 2575M21) have been identified covering the variable (IGKV) cluster, and one probe (1021F11) covering the IGK constant (IGKC) cluster. A series of 24 cell lines of different origin have been analysed for the presence of translocations involving the immunoglobulin light chain loci by dual-colour FISH where the split of the variable cluster and the constant cluster indicated a translocation. Probes established in this study can be used for universal screening of illegitimate rearrangements within the immunoglobulin light chain loci in B cell malignancies.

Detection of illegitimate rearrangements within the immunoglobulin light chain loci in B cell malignancies using end-sequenced probes.

Translocations involving the immunoglobulin loci are recurring events of B cell oncogenesis. The majority of translocations involve the immunoglobulin heavy chain (IGH) locus, while a minor part involves the immunoglobulin light chain loci consisting of the kappa light chain (IGK) located at 2p11.2 and the lambda light chain (IGL) located at 22q11.2. We characterised BAC clones, spanning the IGK and IGL loci, for detection of illegitimate rearrangements by fluorescence in situ hybridisation (FISH). Within the IGL region we have identified six end sequenced probes (22M5, 1152K19, 2036J16, 3188M21, 3115E23 and 274M7) covering the variable (IGLV) cluster and two probes (165G5 and 31L9) covering the constant (IGLC) cluster. Within the IGK region four probes (969D7, 316G9, 122B6 and 2575M21) have been identified covering the variable (IGKV) cluster, and one probe (1021F11) covering the IGK constant (IGKC) cluster. A series of 24 cell lines of different origin have been analysed for the presence of translocations involving the immunoglobulin light chain loci by dual-colour FISH where the split of the variable cluster and the constant cluster indicated a translocation. Probes established in this study can be used for universal screening of illegitimate rearrangements within the immunoglobulin light chain loci in B cell malignancies.

Correlation of three methods of measuring cytogenetic response in chronic myelocytic leukemia

Change in proportion of metaphases with a Ph chromosome is often used to measure effect of treatment in chronic myelocytic leukemia, but this method requires analysis of dividing cells. Dual-color fluorescence in situ hybridization (D-FISH) analysis of bone marrow (BM) or blood (PB), can be used to establish the proportion of interphase nuclei with BCR/ABL fusion. We studied the correlation of these three measures with each other and with response classification categories. In a clinical trial to test rIFN − versus rIFN − +Ara-C ( N = 65 patients), we defined for each cytogenetic and FISH parameter, the patient's “best response” over time and at any given time. The strength and nature of agreement among the three measurements were determined by regression, correlation, and kappa statistic. Correlations between cyBM versus D-FISH-BM, cyBM versus D-FISH-PB and D-FISH-BM vs. D-FISH-PB were fairly strong. Regression showed cyBM values were significantly higher than those of D-FISH-PB or D-FISH-BM. No difference between D-FISH-PB and D-FISH-BM was apparent. When numerical responses (BR%) were classified into response categories (CR, PR, MR, NR), levels of agreement were weak to moderate. We observed a trend toward disagreement between cyBM and each D-FISH method, with cyBM tending to “downgrade” response category. Whether analyzed using actual numerical values or classified into response categories, cyBM differed from D-FISH-BM or D-FISH-PB. The results indicate that mixing data of different methods to measure treatment response within or between patients may be misleading clinical index.

Non-Invasive Fetal Sex Determination on Fetal Erythroblasts from the Maternal Circulation Using Fluorescence in situ Hybridisation

Objective: The main purpose of this study was to evaluate the potential of a non-invasive method for fetal sex determination in clinical practice using dual-colour fluorescence in situ hybridisation (FISH) analysis. We evaluated the differences in nucleated red blood cell (NRBC) recovery from the maternal circulation using various slide preparation procedures following high-gradient magnetic cell separation (double MACS). Methods: NRBCs were enriched from peripheral blood mononuclear cells of 63 pregnant women between 12 and 37 weeks of gestation by double MACS involving simultaneous CD14+ and CD45+ maternal cell depletion and CD71+ fetal cell enrichment. Isolated cells were analysed by dual-colour FISH with X- and Y-specific probes. Before applying the FISH technique, cells were treated using three different protocols. Cells were either fixed in methanol:acetic acid (3:1) and dropped immediately onto glass slides (protocol 1) or treated with 75 mM KCl before resuspension in fixative (protocol 2). Alternatively, isolated cells were transferred onto glass slides and then treated using a method described in the literature (protocol 3). Results: Using various slide preparation procedures, fixed cell numbers as well as the quality of slides differed significantly. Using protocol 1, fetal sex was well determined in 30 cases, in 15 out of 17 male fetuses (1–13, mean 3 fetal cells were found among 5–164, mean 50 maternal cells) and in 15 female fetuses (7–178, mean 56 fixed cells). On the other hand, interpretation difficulties occurred in 7 out of 8 studied cases using protocol 2 due to a lack of cells or damage to the isolated cells. The highest recovery of fixed cells was achieved using protocol 3 (27–411, mean 186); fetal cells positive for the Y signal (2–12, mean 6) were detectable in all studied cases (n = 16). In 7 of the samples from women carrying female fetuses, we could only detect cells with two X signals (51–182, mean 103). All of the experiments were interpretable due to the presence of compact cells with well-visible red and green signals. Conclusion: Our study revealed that using protocol 3 as the post-MACS treatment results in improved NRBC recovery and enables a reliable prospective non-invasive fetal sex determination.

C-MYC Activation in Primary and Metastatic Ductal Adenocarcinoma of the Pancreas: Incidence, Mechanisms, and Clinical Significance

Amplification and overexpression of c-MYC is a common event in various neoplasias. Recently, comparative genomic hybridization (CGH) of primary pancreatic adenocarcinomas revealed a distinct high-level amplification of 8q23-qter, suggesting that c-MYC located on 8q24 may be a candidate oncogene. To evaluate the biological significance and prognostic value of c-MYC activation in pancreatic carcinoma, we performed interphase fluorescence in situ hybridization (FISH) and immunohistochemistry on a series of 69 primary pancreatic adenocarcinomas, 19 corresponding lymph node metastases, and 5 pancreatic intraductal lesions. Dual color FISH using a probe for c-MYC (8q24) and a centromeric probe for chromosome 8 revealed amplification of c-MYC in 32.3% and 29.4% of primary and metastatic tumors, respectively. Immunostaining identified c-MYC protein overexpression in 43.5% of primaries and 31.6% of metastases. Low concordance between positive FISH and immunostaining (13.4%) suggests multiple independent regulatory pathways of c-MYC activation. Statistical evaluation revealed significant correlation (α = 0.033) between c-MYC protein overexpression and histopathological tumor grade but absence of correlation with tumor stage or lymph node status. Analysis of pancreatic intraductal lesions showed c-MYC amplification and protein overexpression in two of five cases in which invasive carcinoma exhibited identical aberrations. We conclude that deregulation of c-MYC protein is common in pancreatic cancer and that it may be involved in early neoplastic development and progression rather than in locoregional spread of invasive cancer.

Cyclin D1 amplification and p16(MTS1/CDK4I) deletion correlate with poor prognosis in head and neck tumors.

Cyclin D1, a cell cycle regulator localized to chromosome 11q13, is amplified in several human tumors including head and neck squamous cell carcinoma (HNSCC). Amplification and/or overexpression of cyclin D1 have been correlated to a poor prognosis. Deletion of the p16 gene, localized to 9p21, has also been observed in a significant proportion of HNSCC. The p16 gene regulates cyclin D1-CDK4 activity and prevents retinoblastoma tumor suppressor gene phosphorylation, thereby downregulating cellular proliferation. Detection of cyclin D1 amplification and p16 deletion using a simple and sensitive method will be valuable for the development of effective treatment modalities for head and neck cancer. We have used fluorescence in situ hybridization (FISH) to study cyclin D1 amplification and p16 gene deletion in head and neck tumors. Both single- and dual-color FISH were performed. Paraffin-embedded tissues from 103 patients with HNSCC were analyzed using genomic DNA probes for cyclin D1 and p16. Dual-color FISH was performed with chromosome 11 or 9 centromeric probes as a control. Twenty-eight of these samples were analyzed for p16 expression by immunohistochemistry. Cyclin D1 amplification was observed in 30% (31/103) of patients, and p16 deletion in 52% (54/103). Lack of p16 expression was observed in 64% (18/28) of patients. There was a good correlation between the deletion of p16 sequences and the loss of p16 expression (P = .008). Amplification of cyclin D1 had a statistically significant association with recurrence, distant metastasis, and survival at 36 months. There was a significant association between p16 deletion and the development of distant metastases. Cyclin D1 amplification and p16 deletion together correlated with recurrence, distant metastasis, and survival. We demonstrate that FISH is a simple and sensitive method for detecting cyclin D1 amplification and p16 deletion in head and neck cancer. Our results suggest that these two genetic aberrations together portend a poorer outcome than either of the abnormalities alone in head and neck cancer.