Constitutive heterochromatin studies in patients with solid tumors

Analysis of Structural Genomic Diversity in Aegilops umbellulata, Ae. markgrafii, Ae. comosa, and Ae. uniaristata by Fluorescence In Situ Hybridization Karyotyping

Fluorescence in situ hybridization karyotypes have been widely used for evolutionary analysis on chromosome organization and genetic/genomic diversity in the wheat alliance (tribe Triticeae of Poaceae). The karyotpic diversity of Aegilops umbellulata, Ae. markgrafii, Ae. comosa subsp. comosa and subsp. subventricosa, and Ae. uniaristata was evaluated by the fluorescence in situ hybridization (FISH) probes oligo-pSc119.2 and pTa71 in combination with (AAC)5, (ACT)7, and (CTT)12, respectively. Abundant intra- and interspecific genetic variation was discovered in Ae. umbellulata, Ae. markgrafii, and Ae. comosa, but not Ae. uniaristata. Chromosome 7 of Ae. umbellulata had more variants (six variants) than the other six U chromosomes (2-3 variants) as revealed by probes oligo-pSc119.2 and (AAC)5. Intraspecific variation in Ae. markgrafii and Ae. comosa was revealed by oligo-pSc119.2 in combination with (ACT)7 and (CTT)12, respectively. At least five variants were found in every chromosome of Ae. markgrafii and Ae. comosa, and up to 18, 10, and 15 variants were identified for chromosomes 2 of Ae. markgrafii, 4 of Ae. comosa subsp. comosa, and 6 of Ae. comosa subsp. subventricosa. The six Ae. uniaristata accessions showed identical FISH signal patterns. A large number of intra-specific polymorphic FISH signals were observed between the homologous chromosomes of Ae. markgrafii and Ae. comosa, especially chromosomes 1, 2, 4, and 7 of Ae. markgrafii, chromosome 4 of Ae. comosa subsp. comosa, and chromosome 6 of Ae. comosa subsp. subventricosa. Twelve Ae. comosa and 24 Ae. markgrafii accessions showed heteromorphism between homologous chromosomes. Additionally, a translocation between the short arms of chromosomes 1 and 7 of Ae. comosa PI 551038 was identified. The FISH karyotypes can be used to clearly identify the chromosome variations of each chromosome in these Aegilops species and also provide valuable information for understanding the evolutionary relationships and structural genomic variation among Aegilops species.

Heterochromatin variants in 109 ovarian cancer patients and 192 healthy subjects

Aberrations of the C-band region of chromosome no. 1 (1qh) were studied in 109 patients with ovarian cancer and 192 healthy subjects. The groups were compared for heterochromatin size variations, intrapair size asymmetry, and inversion. No significant correlation was found between the size of 1qh and ovarian cancer. Heterochromatin size asymmetry was estimated visually and determined by objective measurement of 1qh length or area; the methods show strong correlation. The measurements were normalised by comparison with the length or area of 16p or the entire chromosome no. 1. However, since good reliability was found by simply relating the 1qh size difference to the mean 1qh size, this was considered an appropriate and simpler method of normalisation. Asymmetry indices of length and area measurements correlated well, implying that the simpler method of length measurements can be readily used. 1qh asymmetry, measured objectively or estimated visually, was significantly increased in the cancer patient group. The incidence of C-band inversion was significantly increased in the patient group. Moreover, inversion increased significantly with increasing 1qh asymmetry.

Familial occurrence of cancer and heteromorphism of the heterochromatic segment of chromosome 1

During the last decade, evidence has been forthcoming in support of the correlation between heteromorphism of human chromosome 1qh and the incidence of various malignancies in the carriers of such heteromorphism. We present data from a family with hereditary predisposition to cancer. In this family, five members in a sibship of seven developed ovary and/or colon carcinoma at comparatively young ages. A further 4 cases of malignant disease were ascertained, when a pedigree of 36 family members of 3 generations was constructed. Chromosome analysis was carried out in G- and C-banding from peripheral blood cultures of 19 family members. Distinct heteromorphism in the chromosome 1qh region was detected in 15 (79%) of them, including all 3 cancer patients investigated.

Cytogenetic findings in 111 ovarian cancer patients: therapy-related chromosome aberrations and heterochromatic variants

The chromosomes of 111 ovarian cancer patients were studied in G- and C-banded slides from peripheral blood lymphocyte (PBL) cultures for chromosome damage caused by chemotherapy and radiotherapy and for asymmetry of the constitutive heterochromatin of chromosomes 1, 9, and 16. We also monitored the survival of these patients to determine whether any secondary neoplasia induced by the therapy and report the findings of our investigations. Melphalan (MEL) was the only drug used in single-drug chemotherapy. The incidence of chromosome abnormalities in melphalan-treated cells (25%) was higher than in the control group (17%). The incidence of structural changes was also higher (10.5%) in the MEL-treated group than in controls (6%). After treatments with combinations of drugs, the incidence of structural changes remained at the same level (11%). In the patients receiving combined treatment with MEL and radiation, the rate of structural changes increased dramatically (24%). The overall rate of chromosome aberrations in this group was also higher (50%). Combination of two or more drugs and radiation produced only 14% structural chromosome changes. The overall rate of chromosome aberrations was also low (20%) in this group. Of 111 patients studied, only 33 were alive 6 years after initiation of the study. Of the surviving patients, eight had rearranged chromosomes in the first analysis. After 5 years, new blood samples were collected from these patients and chromosome analyses showed abnormal karyotypes in all eight patients. All chromosome abnormalities in the second analysis were completely unrelated to those in the first analysis, however. Whether the chromosome changes in the second analysis were due to therapy or to other unknown factors could not be determined. Data on C-banding and the distribution of inversions indicated that 91% of the patients had C-band heteromorphisms of chromosomes 1, 91% had heteromorphisms of chromosome 9, and 69% had heteromorphisms of chromosome 16. Furthermore, inversions were observed in chromosome 1 (41% of patients), chromosome 9 (28% of patients), and chromosome 16 (5% of patients).

Constitutive heterochromatin polymorphisms in children with acute lymphoblastic leukemia

The C-band heterochromatin polymorphisms of chromosomes 1, 9, and 16 were studied on peripheral lymphocytes of 67 children with acute lymphoblastic leukemia (ALL) and 50 control individuals. A statistically significant difference between patients and controls was found for large heterochromatin regions (level 3) of chromosomes 1 and 9 (P < 0.001) and for small heterochromatin regions (level 1) of chromosome 16 (P < 0.001). The patients also showed a significant increase in chromosomes 1 and 9 heteromorphism with respect to controls (P < 0.001).

Variations in centromeric heterochromatin among patients with pre-malignant and malignant oral diseases

Polymorphism of heterochromatic regions of chromosomes 1, 9 and 16 was studied in 60 oral cancer patients, in 40 patients with oral submucous fibrosis (OSMF) and in 60 normal healthy subjects. The size heteromorphism was significantly greater (p less than 0.001) in chromosome I of the patients. Localization variants were also significantly more frequent among the patients (p less than 0.05 for OSMF and less than 0.001 for oral cancer patients). The C-band heteromorphism patterns remained comparable in OSMF and in oral cancer patients, with chromosome I being the most frequently involved. On correlating the tobacco/areca-nut chewing habit with the presence of C-band heteromorphism, we observed that C-band heteromorphism was present in 89% of the habit-free oral cancer patients and 80% of the OSMF patients with relatively shorter exposure to this habit, i.e. less than 5 years. This signifies that genetic factors are important in the causation of oral precancerous and cancerous conditions and that polymorphism of the heterochromatic regions does appear to play a role in these conditions.

Chromosome changes in 43 carcinomas of the cervix uteri

A summary of the chromosome changes in 43 carcinomas of the cervix studied by a direct technique showed that the most common anomaly was a small metacentric [in 77%, often in two copies: an i(5p) or possibly an i(4p)]. Others commonly involved in structural changes were: chromosome 1 (60%; most commonly an i(1q), 1p-, or translocation of part of 1q onto another chromosome); chromosome 17 (47%; translocations onto the short arm or long-arm isochromosomes), chromosome 11 (37%; translocations onto the short arm); chromosome 3 (26%; including 3p- and 31-); and chromosomes 2, 6, and 9 (each in 19%). Considering the four most frequent categories of markers--small metacentrics and markers derived from chromosomes 1, 17, and 11, none of which is specific for cervical carcinoma--almost any combination of these four might be present in a tumor (and at least one was present in all tumors) so that they were not mutually exclusive. Estimates of the average numbers of normal chromosomes based on representative karyotypes from 35 of the tumors showed that three chromosomes in particular were underrepresented (chromosomes 4, 11, and 14; 72-73% of the expected values), while chromosomes 3, 19, and 20 were those most highly represented (99-103%).

Variability of Euchromatic and Heterochromatic Regions of Y Chromosome in Two Types of Cancer Patients

Heteromorphism of Y chromosome was studied in head and neck cancer patients and leukemia patients. The results were compared with similar data obtained for healthy men. It was observed that, compared to the controls, mean lengths of Y chromosome were nonsignificantly higher for leukemia patients and lower for head and neck cancer patients. The euchromatic region of Y chromosome (Y-eu) remained comparable in the controls and the leukemia patients, whereas it was smaller in patients with head and neck malignancies. The heterochromatic region (Y-het) was more or less analogous in controls and head and neck cancer patients, however, it was significantly larger in patients with leukemia (P < 0.02).

Identification by C-banding of two human prostate tumour cell lines, 1013L and DU 145

Two human prostate carcinoma cell lines are easily distinguished by C-banding. DU 145 has one metacentric chromosome with a large centromeric band, 1 metacentric and 2 acrocentric chromosomes with interstitial C-bands. The Y chromosome was present in 48% and 42% of the cells at passages 83 and 106, respectively, whereas in 1013L only one metacentric chromosome contained distinct extra C bands--one at the centromere and one interstitially. The Y chromosome was present in 72% of the cells at passage 15 and in 20% at passage 22, but by passage 44 it had disappeared. Karyotype analysis using G-banding revealed that DU 145 had retained several of its original markers, and demonstrated multiple marker chromosomes in 1013L.

Solid tumor cytogenetics. Progress since 1979

Some of the advances in the past decade in the field of solid tumor cytogenetics are described, with particular reference to nonrandom structural chromosome changes. Although it had been known for many years that meningiomas and salivary gland tumors were associated with changes involving particular chromosomes, it has only quite recently become clear, following the application of suitable culture techniques, that other benign tumors such as lipomas and leiomyomas may also be characterized by specific changes, particularly reciprocal translocations. Reciprocal translocations may also be found in malignant soft-tissue tumors such as liposarcomas (involving 12q as in lipomas) and Ewing's sarcoma. In contrast, the common forms of carcinoma present a more variable picture, although certain chromosomes may undergo nonrandom changes of various types, including translocations, which, however, are generally nonreciprocal. Some of these chromosomes may be quite specific (e.g., chromosome 10 in prostatic and #18 in colorectal cancer), while others appear to be common to many or all types of carcinoma, such as chromosomes 1, 3, 11, and 17, and a small metacentric that may be an i(5p). In carcinoma of the bladder, different chromosome changes may characterize subsets of the tumors. In carcinoma of the cervix, however, the commonly involved chromosomes, 1, 3, ?5, 11, and 17, appear in markers in any combination and are thus not mutually exclusive. Although further study of the chromosome changes in carcinomas is essential to an understanding of their relationship to the molecular changes that are associated with malignant transformation, it can be hypothesized that, while some of the changes result in the duplication of particular genes, e.g., on chromosome 1q, a more important role may be to bring about the loss of chromosomal segments containing tumor-suppressor genes. Evidence from molecular studies that has recently been accumulating for the loss of alleles on, for instance, 3p, 11p, and 17p, which could in part be due to gross chromosomal rearrangements, also strongly suggests the importance of genic loss in malignant transformation. In carcinomas, at least, the changes probably involve a number of genes, each change representing one of the several steps necessary for tumorigenesis.

Centromeric alpha satellite DNA amplification and translocation in an unusually large chromosome 14p+ variant

We report cytogenetic and molecular studies on a family that carries, in the father, an unusually large chromosome 14p+ variant [WSi-var(14)(p+)] and, in one of his children, a translocation [DSi-der(14)] involving the variant chromosome. Increase in the size of WSi-var(14)(p+) was estimated to be approximately 35% that of a normal chromosome 14. Presence of extra chromosomal material in this variant chromosome was demonstrated by G-banding using trypsin and staining with Leishman, G-banding using bromodeoxyuridine (BrdU) and Giemsa, and R-banding using BrdU and Giemsa. This material was positive using C-banding with BaOH and staining with Giemsa and negative in DAPI/distamycin staining, suggesting that it contained repetitive DNA but probably not of the types found in the heterochromatic regions of chromosomes 1, 9, 15, 16, and Y. Staining of the nucleolus organiser region (NOR) with AgNO3 indicated the retention of the NOR in WSi-var(14)(p+) but not in DSi-der(14). In situ hybridisation of metaphase cells with an alpha satellite DNA probe specific for human acrocentric chromosomes demonstrated a significantly increased amount of centromeric alpha sequences in WSi-var(14)(p+). Most or all of the extra alpha sequences were retained in DSi-der(14), indicating translocation near the very distal end of the enlarged region. The extra alpha satellite DNA material may have originated through amplification of some centromeric segments. The possible role of the amplified DNA in chromosomal translocations is discussed.