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Effects of Bleomycin on Human Tongue Carcinoma Cells as Revealed by Electron Microscopy¹

Electron Microscope Research Laboratory, Nara Medical University, Kashihara City, Nara [G. Y., Y. H., T. H.],

Five patients with tongue carcinoma were treated for 20 days with bleomycin, 15 mg/day, given by one-shot infusion through the superficial temporal artery. Specimens were taken 7, 14, and 20 days after the initial administration for light and electron microscope observations.

The first alterations observed were the decrease of electron-dense chromatin clumps in nuclei and, simultaneously, the segregation of nucleolar components, i.e., amorphous protein component segregated from fibrillar and granular components. Subsequently, numerous nuclear bodies appeared in the nucleoplasm, which were observed for the first time in human tongue carcinoma cell nuclei in cases of bleomycin treatment. On the other hand, the cytoplasmic alterations were recognized by the decrease in number of mitochondria and by the appearance of numerous free ribosomes followed by the formation of tonofilaments. The cells enlarged because tonofilaments flocked together to make cancer cell nests, which were gradually transformed into a keratinic structure showing the so-called cancer pearl pattern. Finally, cancer cells were degenerated nearly to necrosis; there was no evidence of recurrence of cancer.

Although the precise mechanism of the effect of bleomycin on nuclear activities of human tongue cancer cells remains unsettled because of the lack of cytochemical analysis, it is believed that bleomycin inhibits DNA synthesis and might also activate ribosomal RNA synthesis.

¹ Supported by Grant 801056 for scientific research from the Ministry of Education of Japan.

² To whom requests for reprints should be addressed, at 5–10, Tanabe-Higasino-Cho, Higasi-Sumiyosi-Ku, Osaka City 546, Japan.

Received 5/22/75. Accepted 6/11/76.