Sister chromatid exchanges in lymphocytes of patients with oral carcinoma

Spontaneous and gamma-ray-induced sister chromatid exchanges in patients with carcinoma of cervix uteri

The aim was to investigate whether there are differences in the spontaneous and gamma-ray-induced genomic instability in peripheral blood lymphocytes between untreated cervical cancer patients and healthy women using the sister chromatid exchange (SCE) assay as an indicator of chromosomal instability. Lymphocyte cultures from whole venous blood of 10 patients with cervical neoplasia and 10 healthy female volunteers were cultivated in vitro and irradiated using a 60Co-gamma source. Slides were prepared using the standard air-drying procedure and stained by the fluorescence-plus Giemsa (FPG) technique. The number of SCE and the number of chromosomes were assessed in second-division metaphases. A radiation dose-dependent increase of SCE/cell and SCE/chromosome values were found in healthy women as well as in patients, while statistical analysis has shown significantly higher SCE frequencies in healthy women as compared with patients. Cellular kinetics expressed as replication indices (RI) calculated from the frequency of cells in first cell division (M1), second cell division (M2) and third cell division (M3) were also significantly different, while observed RI were higher for patients than for control individuals. The results suggest that patients with carcinoma of the cervix uteri have chromosomal stability changes reflected in statistically different levels of spontaneous and induced SCE in comparison with healthy individuals. Despite the unknown mechanisms of SCE formation, it is felt that the changed SCE frequency, especially after mutagen treatment, may be used as a marker of increased cancer risk.

Genetic aberrations in oral or head and neck squamous cell carcinoma (SCCHN): 1. Carcinogen metabolism, DNA repair and cell cycle control

The ability to metabolise carcinogens or pro-carcinogens, repair DNA damage, and control cell signalling and the cell cycle are fundamental to homeostasis. Oral squamous cell carcinoma (oral cancer) and many squamous cell carcinomas of the head and neck (SCCHN) may, under appropriate exposure to mutagens, arise if these mechanisms are defective. SCCHN arise as a consequence of multiple molecular events induced by the effects of various carcinogens from habits such as tobacco use, influenced by environmental factors, possibly viruses in some instances, against a background of heritable resistance or susceptibility. Consequent genetic damage affects many chromosomes and genes, and it is the accumulation of these changes that appears to lead to carcinoma in some instances, sometimes via a clinically evident pre-malignant, or potentially malignant, lesion. Although lifestyle factors play a prominent role in aetiology, some patients appear susceptible because of an inherited trait in their ability or inability to metabolise carcinogens or pro-carcinogens, possibly along with an impaired ability to repair the DNA damage. This is the first of a series of three papers reviewing the advances in the understanding of this area of research since our last review [Scully C, Field JK. Genetic aberrations in squamous cell carcinoma of the head and neck (SCCHN), with reference to oral carcinoma (Review). Int J Oncol 1977;10:5-21] and discusses mainly oral carcinoma in the context of SCCHN.

Nuclear lesions during rat hepatocarcinogenesis. I. Measuring the sister-chromatid exchanges during initiation, promotion and progression of rat hepatocarcinogenesis induced with diethylnitrosamine

Cytogenetic endpoints such as sister-chromatid exchanges (SCEs), chromosomal aberrations and micronuclei (MNs) have been widely used as indicators of genetic damage. However, no systematic attempts have been made to correlate the levels of these cytogenetic endpoints with the different steps of carcinogenesis. In the present report, the induction, accumulation and persistence of SCEs and high frequency cells (HFCs) were measured in liver cells during the initiation, promotion and progression steps of rat hepatocarcinogenesis induced by diethylnitrosamine (DEN). The results indicate that lesions leading to SCEs accumulate during initiation only. When DEN administration is longer than the duration of this first step, SCE values stabilize. After stopping the carcinogenic treatment, the SCE levels decrease to control values whether or not promotion and progression occur.

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.

Sister chromatid exchange frequencies in carcinoma of the human oral cavity: effect of treatment

Spontaneous and mitomycin-C-induced sister chromatid exchange frequencies were studied in the lymphocytes of 25 oral cancer patients. For these patients, the mean spontaneous SCE value was 8.31 (+/- SD), which was significantly higher than the value of 6.60 (+/- SD) obtained for the controls (p < 0.001). But there was no significant difference between the Mitomycin C induced mean SCE values of oral cancer patients and controls. Seven of these 25 oral cancer patients were selected for second sampling after surgical removal of the tumor. Six of these seven patients showed a decrease in mean SCE/cell value following surgery, which was almost equal to the SCE values obtained for the controls. This indicates that the increased spontaneous SCE rates in oral cancer patients might be due to the metabolic stress imposed by the tumor on the host body or by some clastogenic product of the malignant cells. Surgical removal of the tumour might have resulted in normalization of the lymphocytic SCE rates in postoperatively studied patients.

Role of areca nut consumption in the cause of oral cancers. A cytogenetic assessment

BACKGROUND

Cytogenetic studies, framed to assess the possible genomic damage caused by areca nut consumption (without tobacco and not as a component of betel quid), were performed among areca nut chewers, which included normal people who chew areca nuts, patients with oral submucous fibrosis, and patients with oral cancer, and healthy nonchewing controls.

RESULTS

The analysis showed statistically significant increases in the frequencies of sister chromatid exchanges and chromosome aberrations in peripheral blood lymphocytes and the percentage of micronucleated cells in exfoliated cells of buccal mucosa among all three groups of chewers when compared with those of the controls.

CONCLUSIONS

The current data, the first of this type among only areca nut chewers, highlight that this popular masticatory is erroneously considered "safe" and that it increases the genomic damage even when chewed without tobacco. The data also signify that, henceforth, in cytogenetic biomonitoring, areca nut consumption also should be considered as one of the confounding factors.

Sister chromatid exchange frequency in breast cancer cases

Sister chromatid exchange (SCE) were studied in 22 patients with breast cancer (i.e., four stage II; 12 stage III, six stage IV) and 10 normal healthy females as age-matched controls. The data obtained in these cases followed a Poisson distribution. An apparent increase in the average rate of SCE/cell was observed with the advancing stage of breast cancer.

Sister chromatid exchange in lymphocytes of patients with cancer of the larynx

The frequency of sister chromatid exchange (SCE) was studied in cultured peripheral lymphocytes from 15 untreated patients with carcinoma of the larynx and 10 healthy control subjects. Bromodeoxyuridine-incorporated chromosomes were treated with Hoechst 33258 and stained according to conventional methods. To measure SCE frequency, at least 15 mitoses per donor were evaluated. The SCE values were found to be higher in cancer cases than in control cases.

Elevated sister chromatid exchange frequencies in the lymphocytes of esophageal cancer patients

Thirty patients with esophageal cancer and 35 healthy controls were studied for spontaneous and mutagen-induced sister chromatid exchange (SCE) frequencies and cellular kinetics in peripheral blood lymphocytes. Some of the patients and controls were tobacco consumers (TC). A mean spontaneous SCE per cell value of 8.36 obtained for the patients was higher significantly (P less than 0.001) compared with a SCE per cell value of 6.74 for the controls. It was noticed that the elevation was significant even when persons in both groups were separated and compared on the basis of tobacco consumption. Among the controls, TC had higher SCE compared with non-tobacco consumers (NTC) (P less than 0.01). Mitomycin C (MMC) was used as a mutagen. No significant difference was observed in MMC-induced rates of SCE between the patients and controls. The cellular kinetics, expressed as average generation time (AGT), also were comparable in both groups. It was concluded that either metabolic stress imposed by the tumor or some clastogenic secretion of malignant cells was responsible for elevated SCE rates in the lymphocytes of the esophageal cancer patients. The disease had no effect on mutagen-induced SCE rates or cellular kinetics in lymphocytes.