DNA stem line heterogeneity in esophageal cancer accurately identified by flow cytometric analysis

Cytogenetic heterogeneity and progression of esophageal squamous cell carcinoma

It is widely believed that most human tumors, including esophageal squamous cell carcinoma (ESCC), arise through multistep genetic and cytogenetic alterations. The time sequence of these alterations, however, is still unknown. The present study was designed to differentiate common early changes from uncommon later ones with combined comparative genomic hybridization (CGH) and ploidy analyses in multiple or single samples of 12 ESCCs. We first demonstrated that the mean copy numbers of chromosomes 3 and 11, determined directly by fluorescence in situ hybridization, showed linear correlation with the mean copy numbers calculated from the G/R ratio of CGH and DNA ploidy (R(2)=0.714, P<0.0001). On this basis, we estimated the absolute copy numbers of chromosomal parts by applying the ploidy-dependent threshold criteria to the G/R ratio data after the criteria were corrected by the percentage of tumor cells in each sample. One-copy changes in the DNA-diploid stage may give large shifts of the G/R ratio, even after tetraploidization, whereas those after tetraploidization undergo small shift. Using the tumors with multiple samples, it was actually demonstrated that most of the gains common to the samples in individual tumors showed the large shifts. Though early changes varied from tumor to tumor in the nine informative cases, it was found that gains of 3q (5/7: number of cases with large-shift 3q+/total number of cases with 3q+), 8q (3/4), 11q13 (4/5), and 14q (3/4) were early events, while losses of 3p (2/8), 5q (1/5), 13q (1/5), and 21q (1/5), and gains of 1p (1/4) and Xq (1/4) were later events in progression of individual tumors.

In situ localization of S-phase-specific histone (H3) mRNA in Bowen's disease

PCNA and Ki-67 immunohistochemistry has been used to assess cell proliferation in place of tritiated thymidine or BrdU labeling of S-phase cells. Recently, it has been possible to reliably demonstrate histone H3 mRNA by in situ hybridization in formalin-fixed and paraffin-embedded tissue sections. We have compared this new proliferation marker with Ki-67 and PCNA with regard to distribution of positive cells and labeling indices (LI%) for 22 cases of Bowen's disease. In normal skin, Ki-67-IHC positive cells and histone mRNA positive cells were observed in the basal and suprabasal layers of the epidermis. In Bowen's disease, positive cells with each marker were more frequent in upper neoplastic epidermis than in suprabasal layers, and the average LI%s were markedly elevated with all markers, the scores decreasing in the following order: PCNA-IHC, Ki-67-IHC and H3mRNA-ISH. However, the results of double staining demonstrated that S-phase cells do not necessarily show exactly the same distributions as with PCNA and Ki-67-IHC labeling. H3mRNA-ISH showed three different degrees of reaction with significantly different LI%s, whereas PCNA and Ki-67 LI% did not vary essentially in the same areas. These results strongly suggest that Bowen's disease, which is well known as a low-grade neoplastic state with malignant potential, also demonstrates clear intratumoral heterogeneity of S-phase cells using the H3mRNA-ISH method.

Flow-cytometric DNA content analysis of oesophageal carcinoma. Comparison between tumour and sequential non-tumour mucosae

The DNA content in oesophageal carcinoma and in sequential non-tumour mucosa was evaluated in 35 patients with oesophageal carcinoma, to explore the hypotheses that DNA distribution pattern and S-phase fraction can reflect malignant potential and that DNA aneuploidy can provide an early-warning signal of developing cancer. DNA flow cytometry was performed on 129 specimens from the tumours and on 119 specimens from non-tumour mucosa. Control specimens from gastric fundus had normal diploid DNA content and low S-phase fraction. Aneuploidy was found in 94.3% of the carcinoma specimens and intratumoral heterogeneity in 54.3%. Of the non-tumour specimens, 43.7% showed aneuploidy and none multiple aneuploidy. Pattern III distribution was present in 8.6% of the tumour specimens but not in non-tumour mucosa, where the incidence of aneuploidy rose with closeness to the tumour (p < 0.001). S-phase fraction was smaller in non-tumour than in tumour specimens (p < 0.0001). The study indicated that histologically tumour-free oesophageal mucosa may have a high malignant potential in patients with oesophageal carcinoma. The relative instability of such mucosa, with aneuploid cells and low S-phase fraction, may facilitate transition to abnormally proliferating cells in response to environmental signals. Cigarette smoking and alcohol may increase the risk of multicentric cancer development.

Cytofluorometric DNA analysis by stathmokinetic method of experimental thyroid neoplasms in rats

Thyroid neoplasms were induced in rats by the intraperitoneal injection of N-bis(2-hydroxy-propyl)nitrosamine as a carcinogenic substance and by the oral administration of KCIO4 as a promoter. The nuclear DNA content was measured in tissue sections of the tumors by the stathmokinetic method with the use of vincristine, and was correlated with the histopathological findings in the process of tumorigenesis and progression. Histological examination showed various types of lesions were produced in 47 surviving rats. A diploid pattern was seen in 82 (92%) of 89 tumors and an aneuploid pattern in 7 (8%) of 89 tumors. Papillary carcinomas and mixed carcinomas only had a diploid pattern, while two of 17 follicular carcinomas and five of 13 anaplastic carcinomas had an aneuploid pattern. On the other hand, benign proliferative nodules only had a diploid pattern. DNA heterogeneity was noted in seven malignant tumors. In four of them it was associated with the histopathological evidence of change, but in three there was no histological difference between the aneuploid and diploid areas other than a difference in the mitotic index. Mitotic indices were significantly higher in the aneuploid than in the diploid areas. These findings suggest that changes in the DNA ploidy cause histological abnormalities and/or affect the mitotic index. It is hypothesized that a change occurs in some diploid cells in a region of a tumor, and that aneuploid cells develop from the diploid cells which then acquire high proliferative activity.