Yuka Kimura

Measurement of proliferating cell nuclear antigen (PCNA) and its clinical application in oral cancers.

The PCNA score was measured in oral squamous cell carcinoma (SCC), and its relationship to other cell proliferation markers, Ki-67 score, S-phase fraction (SPF), and AgNORs counts was investigated. The PCNA score ranged from 0.4% to 43.5% with an average value of 22.8%, the Ki-67 score ranged from 4.9% to 40% with an average of 24.1%, and the SPF ranged from 0.4% to 32.5% with an average of 12.4%, while AgNORs counts ranged from 2.53/nucleus to 7.03/nucleus with an average of 4.74/nucleus. These four parameters were closely interrelated. There was a significant difference in PCNA score between malignant and nonmalignant lesions, suggesting a difference in growth activity. The mean PCNA score decreased significantly from 20.0% to 8.0% after cancer chemotherapy. The response of cancer cells to anticancer agents may be estimated by consecutive measurement of PCNA, since the PCNA score dropped after treatment in cases showing a favorable prognosis.

Saikosaponin A-induced cell death of a human hepatoma cell line (HuH-7): the significance of the 'sub-G1 peak' in a DNA histogram.

Salkosaponin A (SSA) induced cell death in the human hepatoma cell line (HUH‐7) was investigated. Shortly after exposure to SSA, a DNA histogram showed a ‘sub‐G1 peak’, which was recently reported as suggestive of apoptosis by other researchers. However, the electrophoresis of DNA indicated that such was not the case in the present experiment. The decreased intake of rhodamine 123 and the swelling of mitochondria were remarkable shortly after SSA exposure. These data seem to support the idea that the sub‐G, peak represents necrosis rather than apoptosis. Interestingly, the DNA electrophoresis revealed the smear pattern of small DNA fragments shortly after SSAexposure, although it did not show the apoptotic ladder pattern. This finding and the appearance of the ‘sub‐G, peak’ is thought to have been a result of the degradation of the nuclear DNA in the early stages of cell death. Because these findings are different not only from apoptosis, but also from typical necrosis, a distinct mechanism of cell death caused by SSA is suggested.

Detection of Structural Aberrations of Chromosome 17 in Malignant Gliomas by Fluorescence in Situ Hybridization (FISH)

Isolated nuclei prepared from fresh-frozen tissue specimens were used to investigate structural aberrations of chromosome 17 in 18 malignant gliomas (7 anaplastic astrocytomas, 11 glioblastomas). Nuclear DNA was hybridized with four DNA probes specific for centromeric (D17ZI), telomeric (Tel 17p, Tel 17q) and 17p 13.1 sequences (p53) of chromosome 17, using fluorescence in situ hybridization (FISH). The rates of nuclei with one signal (OS) for Tel 17p and p53 were significantly higher than those for D17ZI and Tel 17q. This indicated that the majority of chromosome 17 aberrations was a deletion of the short arm including the p53 gene. When compared with the histological grading, the rates of OS for Tel 17p and p53 in anaplastic astrocytomas were higher than those of glioblastomas, suggesting that the deletion may be associated with the early events in tumorigenesis and that some glioblastomas without chromosome 17 aberrations may be independent from tumour progression via low-grade gliomas.