This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Maeda, H. Articles by Yamashita, A. Search for Related Content PubMed PubMed Citation Articles by Maeda, H. Articles by Yamashita, A.

Subcellular Fate of Protein Antibiotic Neocarzinostatin in Culture of a Lymphoid Cell Line from Burkitt's Lymphoma¹

Departments of Microbiology [H. M., S. A.] and Anatomy [A. Y.], Kumamoto University Medical School, Kumamoto, Japan

¹⁴C-Labeled protein antibiotic neocarzinostatin (NCS) was prepared efficiently by chemical modification. With the use of lymphoma-derived cell line P3HR-1, the subcellular behavior of this antitumor antibiotic was studied by the uptake and autoradiography of isolated nuclei of radioactive NCS.

The antibiotic was taken up by the cells, reaching the maximum value at 1.5 hr and decreasing in value at 4.0 hr to the level at 0.5 hr. The silver grains in the autoradiograms were also found in the isolated nuclei. The grain count in the nuclei showed a tendency similar to the uptake of NCS by the whole cells, i.e., a gradual increase at 0.5 hr, reaching the maximum value at 1.5 hr, and then decreasing after 4.0 hr to the level at 0.5 hr. These facts indicated that NCS reached not only to cytosol but also into the nucleus, and/or at least to the nuclear membrane of the lymphoid cell.

The number of NCS molecules incorporated into the cells at 1.5 hr was calculated to be about 1 x 10⁶/cells at a concentration of 3 µg NCS per ml of medium, which can be extrapolated to 1 x 10⁴ molecules per cell at the minimum inhibitory concentration. The number of molecules should be even less within the nucleus.

In cell-free systems, the interaction of DNA and NCS, which is an inhibitor of DNA synthesis, was investigated with the use of a Sephadex G-100 column, with negative results. In the cell culture system, NCS molecules were degraded into smaller polypeptides of certain sizes by proteolysis either by serum component(s) or by cells themselves.

An inactive isomer, pre-NCS, which is an antagonist of NCS and a partially denatured homologous molecule, behaved similarly to NCS in all of these experiments.

Because the chemically modified NCS used in this study retained biological activity essentially similar to that of parental NCS, the results obtained here could be interpreted as similar to those of parental NCS in vitro.

¹ A part of this investigation was supported by Special Cancer Grant II (901542 for 1974) from the Ministry of Education, Japan.

² To whom requests for reprints should be addressed.

Received 6/19/74. Accepted 10/21/74.

This article has been cited by other articles:

				Y. Luo, S. Lin, J. Zhang, H. A. Cooke, S. D. Bruner, and B. Shen Regiospecific O-Methylation of Naphthoic Acids Catalyzed by NcsB1, an O-Methyltransferase Involved in the Biosynthesis of the Enediyne Antitumor Antibiotic Neocarzinostatin J. Biol. Chem., May 23, 2008; 283(21): 14694 - 14702. [Abstract] [Full Text] [PDF]

				G. Christopher, P. Sudhahar, K. Balamurugan, and D.-H. Chin Release of the Neocarzinostatin Chromophore from the Holoprotein Does Not Require Major Conformational Change of the Tertiary and Secondary Structures Induced by Trifluoroethanol J. Biol. Chem., December 15, 2000; 275(51): 39900 - 39906. [Abstract] [Full Text] [PDF]