Heteromorphism 18ph+ : with or without reproductive consequences?

Heteromorphism or chromosomal variants are usually attributed to structural variations in constitutive heterochromatin. In the case of chromosome 18, 25 cases of 18ph+ have been reported to date. Using the Primed In Situ Labelling technique (PRINS) to study 2 new cases of 18ph+, we have been able to confirm their molecular nature and assuming a mechanism of formation. Although such chromosomal variants are usually thought to have no adverse clinical consequence, a review of the literature shows that many cases were diagnosed because of recurrent abortion, malformed or mentally retarded children suggesting the possible relationship between 18ph+ and such clinical outcomes.

Cytogenetic analysis of trophoblasts by comparative genomic hybridization in embryo-fetal development anomalies.

Cytogenetic studies of spontaneous abortions or intrauterine fetal death depend on conventional tissue culturing and karyotyping. This technique has limitations such as culture failure and selective growth of maternal cells. Fluorescent in situ hybridization (FISH) using specific probes permits diagnosis of aneuploidies but is limited to one or a few chromosomal regions. Comparative genomic hybridization (CGH) provides an overview of chromosomal gains and losses in a single hybridization directly from DNA samples. In a prospective study, we analyzed by CGH trophoblast cells from 21 fetuses in cases of spontaneous abortions, intrauterine fetal death or polymalformed syndrome. Six numerical chromosomal abnormalities including one trisomy 7, one trisomy 10, three trisomies 18, one trisomy 21 and one monosomy X have been correctly identified by CGH. One structural abnormality of the long arm of chromosome 1 has been characterized by CGH. One triploidy and two balanced pericentromeric inversions of chromosome 9 have not been identified by CGH. Sexual chromosomal constitutions were concordant by both classical cytogenetic technique and CGH. Contribution of trophoblast analysis by CGH in embryo-fetal development anomalies is discussed.

Distal deletion of 1p in colorectal tumors: an initial event and/or a step in carcinogenesis? Study by fluorescence in situ hybridization interphase cytogenetics.

Cytogenetics studies have suggested that short arm deletion in chromosome 1 is involved in triggering colorectal tumor development. To elucidate the role of 1p under-representation in the tumoral process, we investigated by fluorescence in situ hybridization interphase cytogenetics, using simultaneously centromeric and p36 telomeric probes for chromosome 1, 27 primary adenocarcinomas, 5 metastases, 5 adenomas and as control 4 normal mucous membranes. The 1p under-representation in paradiploid tumoral cells, interpreted as a 1p deletion, was observed in 8/27 adenocarcinomas, 2/5 metastases and 3/5 adenomas. Thus, in diploid cells 1p deletion was observed in some tumors independently of the stage of the process. The 1p under-representation in total number of examined cells, i.e., diploid and aneuploid, was observed in 14/16 grade B1-B2 tumors, in 5/8 grade C1-C2 tumors, and all grade D tumors (3/3) and all metastases (5/5). There were no correlations with location or histological characteristics of cancers, gender or age of patients. These results show high frequency of 1p under-representation in intestinal tumors, and lead to separate the under-representation of 1p in diploid cells, which correspond to a 1p deletion probably implicated in the initiation of the process, from the under-representation in aneuploid cells, which mainly may be the consequence of complex rearrangements in relation to extension of the malignant process.

Relation between cytogenetic characteristics of two human colonic adenocarcinoma cell lines and their ability to grow locally or metastasize or both: an experimental study in the nude mouse.

This study was aimed at elucidating the relation between the cytogenetic characteristics and the invasive ability of two human colonic adenocarcinoma cells lines, HT29 and CaCO2. These two cell lines have very different tumorigenic and metastatic capacities after intrasplenic injection into nude mice: high for HT29 and relatively weak for CaCO2. At the time of injection, cytogenetic studies of the two cell lines revealed shared abnormalities: paratriploidy with seven common extra chromosomes or chromosome regions and specific particularities. In HT29 cells, we observed a large marker of unknown origin, an isochromosome i(11)(q10) and 5, 12, 13, 15, 19, and (19q+) supernumerary chromosomes, and, finally, the absence of one chromosome 16. In CaCO2 cells, we observed a chromosome 1-derived marker with q24-31 duplication, 12q and 16 supernumerary chromosomes, and a der(16) marker. The most striking difference between the karyotypes of these two cell lines concerned chromosome 16 (under- and overexpressed in HT29 and CaCO2 cells, respectively), overexpression of chromosomes 13, 15, and 19 in HT29 cells, and the relative loss of 12p in CaCO2 cells. Although some differences may be due to the intrinsic characteristics of the stem line, the establishment of specific cytogenetic abnormalities points out the role of many regions of the genome in tumorigenic and metastatic capacities of malignant cells.

[Colorectal carcinogenesis, frequency and significance of genetic alterations: deletion of the short arm of chromosome 1, and initiating event]. / Cancérogenèse recto-colique, fréquence et signification des altérations génétiques: la délétion du bras court du chromosome 1, un événement initiateur.

Cytogenetic anomalies described in colo-rectal tumors are numerous. Despite the complexity and the number of the anomalies observed, a combined study of their frequency and of the stage of prognosis of the tumors suggests that the evolution from colonic adenoma to carcinoma often follows a sequence of events comprising a 5q15-22 deletion (DCC), and a 17p deletion (P53). It even seems likely that in many cases, these events are not constant and that others might lead to the same phenotypic transformation. Chromosome 1 involvement in structural rearrangements has been demonstrated in numerous forms of cancers, malignant blood disorders and in solid tumors. In colorectal adenocarcinoma anomalies have been described on short and/or long arms. In a case of adenoma with mild dysplasia a deletion of the distal part of the short arm of chromosome 1 was observed as an isolated cytogenetic anomaly, suggesting it would be an early, perhaps triggering, event for the tumour development. A cytogenetic study in a series of colo-rectal tumours, researches on loss of heterozygosity and microsatellite instability lead to consider deletions at chromosome 1p as an early event in human colorectal tumourigenesis.

Interphase cytogenetic studies of human hepatocellular carcinomas by fluorescent in situ hybridization.

Although numerous allelic chromosome losses have been reported in hepatocellular carcinomas (HCC), chromosome analysis by cytogenetic methods has rarely been performed in these tumors, unlike other solid malignant tumors. The purpose of the current study was to analyze primary liver tumors by conventional cytogenetic methods and by a new molecular cytogenetic technique, called fluorescent in situ hybridization (FISH), a technique that has been recently proposed to count the number of chromosome copies in interphase nuclei with chromosome centromeric probes. Primary cultures of tumoral cells were prepared to obtain metaphases. Specific chromosomes probes 7, 17, and 20 were used to perform in situ hybridization on isolated intact tumoral cells. Seven cases of primary liver tumors (six cases of HCC and one case of benign focal hepatic nodular hyperplasia) were investigated. A few metaphases were obtained in five of the seven tumors, and in most cases numerical abnormalities were difficult to interpret. In contrast with in situ hybridization, all cases of HCC showed losses and/or gains of chromosomes. Loss of one to three chromosomes occurred in five tumors. A gain of two chromosomes was observed in two of these five tumors. In only one case, a gain of only three chromosomes occurred. In addition, a loss of chromosome 17 was recorded for the benign tumor. These results demonstrate that FISH with specific probes can provide information on chromosome number in the tumoral cells of primary liver tumors even in the absence of analyzable metaphases. This technique opens new possibilities for the investigation of chromosome abnormalities in HCC.

Cytogenetic analysis of BC2, a new human hepatoma cell line, by fluorescent in situ hybridization.

Cytogenetic analysis of a new human hepatoma cell line BC2 was performed with conventional cytogenetic techniques and fluorescent in situ hybridization. Numerical and structural abnormalities were observed by conventional cytogenetics for chromosomes 1, 2, 4, 7, 8, 9, 10, 11, 15, 17 and 20. Chromosome painting allowed to specify the translocation of chromosome 1, and to characterize 3 markers from chromosome 8 and one marker from 9, which were unrecognizable by conventional techniques. Comparison of chromosome 1 abnormalities with those reported in the literature for other human hepatoma cell lines showed that structural abnormalities of chromosome 1 were present in different regions of this chromosome. A review of the literature was done, and the results discussed, suggesting that alterations of chromosome 1 may be important in hepatocarcinogenesis.

Report of a family case of satellited Y chromosome associated with a severe oligoasthenoteratospermia. A review of the literature.

A new case of familial Yqs is reported. The discovery has been made at the time of karyotyping of a patient with an oligoasthenoteratospermia. A possible correlation between supernumerary NORs of the Yqs chromosome and meiotic disturbances is discussed, and a review of the literature is performed.

Chromosome 1 in human colorectal tumors. Cytogenetic research on structural changes and their significance.

The significance of short and long arm anomalies of chromosome 1 was investigated in 55 colorectal tumors comprising 41 carcinomas and 14 adenomas. The tumors were at various stages of transformation from adenoma to carcinoma. Our investigation was prompted by the observation of a p32-pter deletion on the short arm of chromosome 1 in a case of benign tubulovillous adenoma with mild dysplasia, as well as by frequent reports that chromosome 1 is involved in many neoplastic processes. Long arm anomalies were found in seven of the 41 carcinomas, six of which were in stage B2, and short arm anomalies in ten carcinomas at various stages. Three of the adenomas exhibited chromosome 1 anomalies, which in one case comprised a 1p32-pter deletion only. Overall, short arm anomalies especially concerned the p32-36 region. These results suggest that the cytogenetic anomalies respectively located on the short and long arms of chromosome 1 should be considered separately. Damage to the long arm might constitute a late non-specific event, whereas damage to the p32-pter region of the short arm might be involved in triggering colorectal tumor development.

Tubulovillous adenoma of the colon with hyperdiploidy, double-minute chromosomes, and inversion of chromosome 1.

A sessile adenoma of the left flexure of the colon was studied after surgical colectomy. Specimens were obtained for complete histologic evaluation. The tumor consisted of glandular tubes with decreased mucin production and a papillary structure on the luminal aspect. The muscularis mucosa was not involved; there was no carcinomatous focus. Cytogenetic study was carried out on 56 cells; none was normal, 77% were hyperdiploid (52-87 chromosomes), 16% were hypodiploid (18-39 chromosomes), and 7% were paradiploid. The supernumerary chromosomes were chromosomes #3, #6, #13, #19, and #20; chromosome #18 was missing in 80% of the cells. A marker for chromosome #1 resulting from a q21.1-q21.2 break with inversion of the centromere-bearing segment (pter-q21) was observed in 58% of the cells. Twenty-five percent of the cells had double minute chromosomes. Despite the histologically benign nature of the tumor, all the cells showed significant cytogenetic aberrations, some of which are considered to be markers of neoplastic transformation (polyploidy, double minutes, chromosome #1 marker).

Human chromosome analysis in 24 cases of primary carcinoma of the large intestine: contribution of the G-banding technique.

As in the haemopathies, the application of cytogenetics to epithelial cancers could aid in the study of their pathogenesis evaluation. In this context we performed chromosome analyses on a series of human colo-rectal cancers. The technique was consistently reliable since the modal number of chromosomes could be determined in all 24 cases. In 22, karyotypes could also be established. Each tumour was characterized by a single cell clone in 21 cases and by a mosaic of 2 populations in 3 cases. Numerical anomalies were not due to chance: they enabled near-diploid (11 cases), near-triploid (9 cases), mosaic (3 cases) and highly polyploid (1 case) cancers to be distinguished. Supernumerary chromosomes were primarily in groups C and F. The most frequent markers before denaturation techniques were No 2q +, No F and minutes. Each time double-minutes were observed (5 cases), they were in invasive cancers (B and C Dukes classification). Cells were generally diploid in non-invasive cancers with fewer quantitative and structural anomalies. Tumour cytogenetics were related to the histological type and localization in the colon, as well as to the local and metastatic spread.

Characterization of a newly established human gastric cancer cell line HGT-1 bearing histamine H2-receptors.

A human gastric adenocarcinoma cell line, HGT-1, was established in vitro from the primary tumor of a 60-year-old patient. Histological examination of the tumor revealed a poorly differentiated adenocarcinoma. Primary tumor cells were cloned in soft agarose and gave rise to tumor colonies. The procedures enabling us to form a continuous cell line from the agarose colonies are described. The cultured cells grew as monolayers of closely apposed polygonal cells with a population-doubling time of 19.48 +/- 1.20 (S.E.) hr during exponential growth at passage 59. They had an epithelial morphology. Ultrastructural studies revealed the presence of microvilli and tight junctions. The HGT-1 cell line is tumorigenic in nude mice and has a hyperdiploid karyotype with a modal number of 57 chromosomes. It exhibits numerous marker chromosomes. These human gastric epithelial cells do not secrete mucus or carcinoembryonic antigen. They exhibit functional histamine H2-receptors mediating cellular cyclic adenosine 3':5'-monophosphate production and adenylate cyclase activation. In conclusion, the use of a soft-agarose clonogenic assay permitted us to develop a cancer cell line without the problems of fibroblastic cell contamination. The existence of histamine H2-receptors on gastric HGT-1 cells stresses the importance of this line as a model for studies of regulatory mechanisms involved in gastric secretion.

[Immunofluorescent study of crystallin-specific proteins of rat embryo]. / Etude en immunofluorescence des protéines spécifiques du cristallin de l'embryon de rat

Using indirect fluorescent antibody techniques, the beginning of crystallin synthesis is detected in the embryonic Rat lens. The appearance of the crystallins is observed from the twelfth day of gestation at the basal cytoplasm of the cells, in proximity to the presumptive neural retina. At the fourteenth day fluorescence appears throughout the lens.