Increased sister chromatid exchange frequency in young women with breast cancer and in their first-degree relatives

The well-known increased risk of breast cancer (BC) in first-degree relatives of patients with BC has been related to shared genetic factors including defective DNA repair, with loss of genomic integrity. On the other hand, it can be hypothesized that early-onset breast cancer is also associated with overburden of heritable factors leading to increased DNA injury. In this respect, we analyzed sister chromatid exchange frequency (SCE) in 20 women with breast cancer (all < or =40 years old), in their first-degree female relatives, and in 20 age-matched healthy females without a personal or family history of cancer. SCE was significantly increased (P < 0.05) in patients (7.17 +/- 1.81 per metaphase) and in their first-degree relatives (6.44 +/- 0.98), compared with controls (5.85 +/- 0.72). There was no difference in SCE frequency between patients and their first-degree relatives. We suggest that the increased SCE in patients reflects a genomic instability that may be operative in carcinogenesis. Further, genomic instability is shared also by first-degree relatives, although none of them had a history of breast cancer at the time of the study.     

Studies on sister chromatid exchanges in patients with Hodgkin's disease

Sister chromatid exchange frequencies were analyzed in bone marrow cells and in stimulated peripheral blood lymphocytes from 20 patients with Hodgkin's disease. Sister chromatid exchange studies were also carried out in the bone marrow of eight and peripheral blood of 11 normal subjects separately. Among the patients, ten were newly diagnosed and ten patients were survivors who had received therapy 30-64 months prior to studies. The mean sister chromatid exchange frequencies in bone marrow and peripheral blood of untreated patients were 3.93 +/- 0.7/cell and 4.09 +/- 0.91/cell, respectively, which were not significantly different from those of normal subjects (3.22 +/- 0.7/cell and 5.16 +/- 1.3/cell in bone marrow and peripheral blood, respectively). The mean sister chromatid exchange frequencies in bone marrow and peripheral blood in five of the untreated patients 3-4 months after initial therapy and in a treated (30-64 months after therapy) group were close to the sister chromatid exchange values of the untreated group. Analysis of the distribution of exchanges per chromosome or chromosome groups showed a nonrandom distribution of exchanges in chromosomes #1, #2, and #3, and in E-, F-, and G-group chromosomes in the normal controls and in Hodgkin's disease patients.     

Sister chromatid exchanges in peripheral lymphocytes from women with carcinoma of the uterine cervix

Sister chromatid exchanges (SCE) are reciprocal exchanges between sister chromatids. It has been reported that in patients with cervical cancer, the frequency of SCE in peripheral lymphocytes is significantly higher than that in normal individuals; however, other studies have shown no significant difference. The aim of this unmatched case-control study was to compare the mean number of SCE per metaphase in lymphocytes from women with and without carcinoma of the cervix uteri. The SCE specimens were prepared by the fluorescence plus giemsa technique in peripheral lymphocytes from 28 women with carcinoma of cervix uteri and 28 controls. The mean number of SCE per metaphase in women with carcinoma of cervix uteri (7.80 +/- 1.05) was higher than the control group (6.98 +/- 1.13) (P < 0.05; t-test). This study had a statistical power of 0.80 and an alpha value of 0.05. This finding suggests that an increased number of SCE in peripheral lymphocytes is associated with cervical cancer. We consider that the lack of reported association of SCE and cervical cancer might be attributed to the none determination of the statistical power and sample size.     

Effects of a phorbol ester on cell proliferation, cytoskeleton and chromosomes in 3T3 T proadipocytes

Tumour-promoting 12-0-tetradecanoylphorbol-13-acetate (TPA) showed a biphasic effect on cell proliferation of BALB/3T3 T proadipocytes. TPA (100 ng/ml) inhibited cell proliferation after 6-18 h of treatment but stimulated it during the next 3 d. Cultures treated with TPA for 24 d showed a 3.3 times higher saturation density compared with those without TPA treatment. TPA-induced morphological alterations were studied by immunofluorescence and scanning electronmicroscopy. In addition, detergent-extracted whole mount cell observations were carried out with or without immuno-electronmicroscopy. The results showed that TPA induced a rapid and reversible assembly of actin filaments and redistribution of microtubules which commenced as early as 15-20 min, but did not influence the frequency of sister chromatid exchange.     

Sister chromatid exchanges in leukemic patients

Sister chromatid exchange (SCE) was studied in PHA-stimulated peripheral blood lymphocytes from 36 newly diagnosed and untreated leukemic patients: 16 with acute lymphoblastic leukemia (ALL), 10 with acute nonlymphocytic leukemia (ANLL), and 10 with chronic myelocytic leukemia (CML). The metaphases analyzed show no chromosomal abnormalities. The mean SCE frequency (mean +/- SE) for each group of patients was: 6.8 +/- 0.4, 6.6 +/- 0.3, and 7.0 +/- 0.6 per mitosis, respectively, which was significantly lower than the mean SCE score for 30 controls (8.7 +/- 0.2). No differences in SCE score among ALL, ANLL, and CML and a similar SCE frequency by chromosome number and group allowed consolidation of all the cases into a single group of 36 leukemic patients (6.8 +/- 0.3). When the frequency of SCE was compared by chromosome number and group between the leukemic patients with the control group, a significant decrease in SCE frequency was observed due to a low SCE score in almost all the complements, except chromosome #1. It is suggested that the low SCE rate is related to the leukemic process itself.     

12-O-tetradecanoyl-phorbol-13-acetate and its relationship to SCE induction in syrian and chinese hamster cells

12-O-Tetradecanoyl-phorbol-13-acetate (TPA) in conditions that produce enhancement of ultraviolet light (UV) and x-irradiation Syrian hamster embryo cell (HEC) transformation did not cause further increase in the sister chromatid exchange (SCE) frequency induced by UV and x-irradiation, two physical carcinogens that differ in their mode of DNA interaction and efficiency of SCE induction. Several factors which might influence SCE induction by TPA were studied on HEC and Chinese hamster V79-4 cells. Heat-inactivated serum was used because of the possibility that a serum component may interfere with TPA ability to cause SCE. TPA effect on SCE was determined at the first and second division post treatment on cells exposed to different 5-bromodeoxyuridine (BrdUrd) concentrations. Independent of BrdUrd concentration (1-10μg/ml medium) and the number of cell divisions post treatment, TPA (0.01-2μg/ml medium) was ineffective in inducing SCE in exponentially and stationary HEC cultures cultivated in medium supplemented with heat-inactivated serum. Also, TPA did not increase the SCE frequency in V79-4 Chinese hamster cells cultured in heat-inactivated or noninactivated serum. Although SCE induction, a cellular response to carcinogen-induced DNA damage, may be important for the induction of transformation by environmental agents, the enhancement of transformation frequency caused by TPA occurs without further DNA alterations involved in SCE formation.     

Cell-Growth Kinetics and Karyotype Analysis of Human Memory Lymphocytes Responding to Alloantigen and Mitogen

Peripheral-blood lymphocytes were primed in vitro with the mitogen phytohemagglutinin (PHA) or with allogeneic cells and their memory responses studied following sequential restimulation with either mitogen or alloantigen. Chromosome preparations were made every 12 hours following exposure to the stimulating agents. Cultures were labeled with BUdR for sister-chromatid staining of the chromosomes which provided information about the kinetics of cell growth and rates of sister chromatid exchange. Cultures containing no BUdR were used for the investigation of cell karyotypes after chromosome-banding.Following PHA as well as alloantigen restimulation, an earlier reaction of the responding cells was observed. The peak response after the first stimulation was found at 120 h with allogeneic stimulation and at 60 h with mitogen stimulation. In the second round of stimulation, the peak occurred after 48 h (allogeneic) and 36 h (PHA) and following the third stimulation after 36 h (allogeneic) and 24 h (PHA). The speed of cell growth was decreased following restimulation with either alloantigen and mitogen. In contrast to the allogeneic restimulation, the number of cells responding after PHA restimulation was decreased.No systematic numerical or structural aberration of the karyotype was detected following repeated stimulation with either alloantigen or mitogen. In this sense, the lymphocyte subpopulations selected by repeated stimulation did not differ from the starting material. On the other hand, the sister-chromatid exchange (SCE) frequency was increased following allogeneic restimulation, whereas it remained constant with PHA restimulation.     

Chromosome Aberrations and Sister Chromatid Exchange Studies in Patients with Prostate Cancer: Possible Evidence of Chromosome Instability

Cytogenetic studies have been carried out using the G-banding technique in peripheral blood lymphocytes of 24 patients with prostate cancer. Of these, eight belong to stage B, six to stage C/e, three to C/sv, two to Do, and the remaining five to DI stage of carcinoma. Simultaneously, sister chromatid exchanges (SCEs) were also analyzed in the peripheral blood lymphocytes of these patients, along with those of 40 age-matched control subjects. The frequency of aberrant metaphases is significantly higher in patients with prostate cancer (7.32%) than in age-matched controls (2.92%). A large number of chromosome aberrations in lymphocytes of these patients, which are generally constitutional in nature, have also been detected. In stage-B patients, the frequency of cytogenetically abnormal cells is comparatively low with regard to the number of cells scanned, and these abnormalities are generally confined only to single chromosome (except in one metaphase in patient 1, who was diagnosed with bladder carcinoma in addition to cancer of the prostate). Sister chromatid exchanges (SCEs) were also analyzed in the patients and age-matched control subjects. The mean SCE frequencies were 9.24 ± 0.62 (n = 1356) per metaphase and 0.203 per chromosome in patients, whereas in control subjects the frequencies were 5.94 ± 0.25 (n = 4000) per metaphase and 0.129 per chromosome. The SCE frequency in cancer patients was statistically significant (p < 0.001). Our results indicate that the patients with prostate cancer show a degree of chromosomal instability that might be related to a predisposition to neoplasia.     

白血病和MDS患者外周血CA.SCE.CK及超微结构的观察

对11例白血病和10例MDS患者外周血进行CA、SCE、CK及电子显微镜观察。结果表明:白血病及MDS患者染色体畸变率及SCE频率增高,细胞增殖周期延长及白细胞超微结构异常等改变具有一致性。这对白血病及MDS的早期诊断提供实验依据。     

Sister chromatid exchanges in patients with oral submucous fibrosis

The incidence of sister chromatid exchange (SCE) was investigated in the lymphocyte chromosomes of 45 patients with oral submucous fibrosis and 56 age- and sex-matched nonsmoking controls. The frequency of SCE was 9.26 +/- 2.15 in patients with oral submucous fibrosis, which was significantly higher than the mean SCE value of 5.49 +/- 1.24 observed in normal controls. The frequency of SCE in patients with oral submucous fibrosis addicted to the habit of betel with tobacco chewing, "bidi"/cigarette smoking and combined habits of chewing and smoking of tobacco were 8.12 +/- 1.69, 9.43 +/- 1.87, and 10.06 +/- 2.28, respectively. These values were also significantly higher as compared with the SCE values observed in normal controls.     

Sister chromatid exchanges in patients with carcinoma in situ of cervix uteri.

Sister chromatid exchange (SCE) was analyzed in lymphocytes of 21 patients with carcinoma in situ of cervix uteri and 19 control subjects. The mean SCE frequencies were 8.92 +/- 0.31 (n = 417) and 6.94 +/- 0.23, (n = 375) per metaphase in patients and controls, respectively. The increase of SCE levels in cancer patients was highly significant in respect to controls (p less than 0.001). Together with data of other authors in patients with precancerous and cancerous lesions of the cervix, our results suggest that there is no correlation between SCE rate and severity of cancerous lesions.     

The effect of tobacco smoking on the frequency of sister chromatid exchanges in human lymphocyte chromosomes

The incidence of sister chromatid exchange (SCE) was investigated in the lymphocyte chromosomes of 24 bidi smokers, 18 cigarette smokers, and 20 normal nonsmoking controls. Bidi and cigarette smokers had a mean SCE per cell of 10.12 +/- 2.41 and 8.15 +/- 1.62, respectively, which were significantly higher than the mean value of 5.48 +/- 1.29 found in controls. Higher frequencies of SCE were also observed in individuals who smoked more than ten bidis or cigarettes per day, compared with people who smoked less than ten bidis or cigarettes per day, respectively. Individuals who smoked bidis or cigarettes for more than 10 years also showed an increased frequency of SCE as compared with those who smoked bidis or cigarettes for less than 10 years.     

Sister chromatid exchanges in the lymphocytes of patients with oral leukoplakia

The incidence of sister chromatid exchange (SCE) was investigated in lymphocyte chromosomes of 59 patients with oral leukoplakia and 65 age- and sex-matched nonsmoking controls. The frequency of SCE was found to be 8.61 +/- 1.89 in patients with oral leukoplakia, which was significantly higher than the mean SCE value of 5.58 +/- 1.26 observed in normal controls. The frequency of SCE in patients with oral leukoplakia addicted to the single habit of betel with tobacco chewing, bidi/cigarette smoking, and combined habits of chewing and smoking of tobacco were found to be 7.95 +/- 1.63, 8.17 +/- 1.66, and 9.23 +/- 2.14, respectively. These values were also significantly higher as compared to the SCE values observed in normal controls.     

Sister chromatid exchange in normal and Ph1-positive leukemic cells after mitomycin-C treatment in vitro

The sister chromatid exchange (SCE) frequency was investigated in normal bone marrow and Ph1-positive cells of chronic myelocytic leukemia (CML) patients with and without mitomycin-C (MMC) treatment in vitro. Even though the spontaneous SCE frequency was found to be significantly lower in CML cells, the absolute SCE values after MMC treatment did not differ between leukemic and normal cells, and this seems to indicate an equilization of SCE rates. However, the fact that leukemic cells with lower spontaneous SCE rates need a further increase of SCE to reach values equal to those of normal cells might indicate a somewhat higher susceptibility of leukemic cells to DNA damage by MMC. This interpretation appears to be confirmed by the fact that the inhibition of cellular proliferation at higher MMC doses considerably reduced the number of leukemic cells that was able to divide twice during a given culture time.     

Sister chromatid exchange (SCE) studies in breast cancer patients: A follow-up study

Sister chromatid exchanges (SCEs) were studied in 20 patients with breast cancer (stage II) before surgery, one month after surgery, and after three years as a follow-up study. Data from 50 age-matched, normal healthy females, preferably from the affected families, served as controls.

In each patient, 50 well-spread metaphases were scored for SCEs. The mean values of SCEs per metaphase were 5.80, 4.69, and 5.98 in breast cancer patients before surgery, one month after surgery, and after a gap of three years as a follow-up, respectively.

The one-way analysis of variance was applied and it was found that there was a highly significant difference in the frequency of sister chromatid exchanges in these patients before surgery, one month after surgical removal of cancerous tissue, and after three years as a follow-up study. The elevated level of SCEs three years after surgical removal of cancerous tissue predict the chances of development of another type of cancer.     

The effects of four drug regimens on sister chromatid exchange frequency in patients with lymphomas

Patients undergoing first-line chemotherapy after diagnosis of lymphoma have considerable DNA damage in their peripheral blood lymphocytes, using sister chromatid exchange (SCE) frequency as a sensitive indicator. Different drug regimens produce different patterns of changes in SCE frequency. These may be related to their potential to induce second malignancies.     

Sister chromatid exchanges in the lymphocytes of control women, pregnant women, and women taking oral contraceptives: effects of cell culture temperature

The incidence of sister chromatid exchange (SCE) was investigated in the lymphocytes of control women, pregnant women, and women using oral contraceptives after culture at 37 degrees C and 40 degrees C. At 37 degrees C, the mean frequency of SCE (MEAN +/- S.E.) was found to be 7.91 +/- 0.30 in pregnant women and 8.53 +/- 0.29 in oral contraceptive users which were significantly higher than the SCE value of 5.56 +/- 0.21 found in control women. Increase in growth temperature to 40 degrees C elevated the SCE frequency to 11.86 +/- 0.44 in pregnant women, 12.76 +/- 0.46 in oral contraceptive users and 7.24 +/- 0.26 in control women. These data indicate that there is a differential induction of SCEs following increased cell culture temperature in the lymphocytes of pregnant women and oral contraceptive users, compared with control women.     

Reduced expression of aphidicolin-induced common fragile sites in peripheral lymphocyte chromosomes of patients with B-cell chronic lymphocytic leukemia

The occurrence and frequency of aphidicolin-induced common chromosomal fragile sites were examined in 12 B-cell chronic lymphocytic leukemia (B-CLL) patients (ten males and two females) and three normal individuals. The mononuclear cells separated by Ficoll-Hypaque gradient were cultured in vitro for 96 hours stimulated by pokeweed mitogen (PWM) in combination with T-leukemia cell conditioned medium or 10% B-cell growth factor. For the final 24 hours the cells were treated with aphidicolin (0.07 microgram/ml). Results indicate that there was a significant reduction in the overall mean frequency of common fragile sites in CLL patients with a wide individual variation. Fragile sites were found to be localized either on a single chromatid or both chromatids, but rarely involved homologous chromosomes. No definite relationship between the frequency of fragile sites and the staging of CLL disease was observed. A significant reduction and variability in the frequency of fragile sites suggest the heterogenous nature of B-CLL and probably a different mechanism of induction of fragile sites in CLL cells compared to controls.     

Bromodeoxyuridine tablet methodology for in vivo

5-Bromodeoxyuridine (BrdU) tablets with different physical characteristics are useful in a wide variety of studies requiring detection of DNA replication in vivo. These tablets can effect a high substitution of BrdU in DNA, thereby permitting sister chromatid differentiation in chromosomes stained with 33258 Hoechst alone or in conjunction with Giemsa. Baseline and cyclophosphamide-induced in vivo sister chromatid exchange frequencies in mouse spleen, marrow, and thymus were measured and found to be significantly greater than those in spermatogonia. Sister chromatid exchange analysis was also extended to mouse liver and to Chinese hamster and Armenian hamster marrow cells. Sister chromatid differentiation was observed in Armenian hamster meiotic tissue, and evidence for interhomolog chromatid exchange obtained.     

Fluchloralin is cytotoxic and genotoxic and induces apoptosis in mammalian cells

The genotoxic and cytotoxic effects of a widely used herbicide, fluchloralin, were assessed using cultured mammalian cells. Treatment of cells for 8–12 hr with fluchloralin resulted in a significant increase in the frequency of metaphase cells with chromosomal damage. At higher concentrations, the herbicide also induced an increase in the frequency of sister chromatid exchange. A 50% loss in viability was observed when cells were exposed to the herbicide for 72 hr. To understand the mechanism of cell death caused by fluchloralin, its effect on DNA synthesis and its ability to induce apoptosis were investigated. Even short (6 hr) treatment of cells with fluchloralin resulted in a 30–50% inhibition of DNA synthesis. Agarose gel electrophoresis of DNA from herbicide-treated cells and cytochemical staining indicate the induction of apoptosis by fluchloralin. Environ. Mol. Mutagen. 31:257–262, 1998 © 1998 Wiley-Liss, Inc.