Chromosomal proteins in hepatocarcinogenesis

Abstract

The chromosomal proteins of rat liver were studied by SDS-gel electrophoresis during the process of nitrosomorpholine-induced hepatocarcinogenesis, in the primary hepatomas thus obtained, and in their metastases. It was found that an increased proteolytic activity was present in liver homogenates from carcinogen-fed animals which caused differences between the nonhistone chromosomal proteins of control and carcinogen-treated livers. These differences disappeared in the presence of the protease inhibitor PMSF. In the primary hepatomas slight quantative changes were observed: an increased amount of two proteins of 43000 and 63000 daltons molecular weight, respectively, and a decrease in the histone subfraction H 1 degrees. In the metastases both quantative and qualitative differences were detected: a strong decrease in the protein bands corresponding to the contractile proteins alpha-tubulin, beta-tubulin, and actin; an increased content of the 63000 dalton protein; the appearance of new proteins of approximately 60000, 90000, and 120000 daltons molecular weight, and the complete disappearance of histone H 1 degrees.

Immunohistochemical demonstration of histone H10 in human breast carcinoma

“…Histone H1 0 was not found in Ehrlich ascites tumour cells (Panyim and Chalkley 1969b) and in HeLa cells (Marks et al 1975). Tsanev and Hadjiolov (1978) showed reduced level of H1 0 in chemically induced hepatomas. Lea (1983) found inverse correlation between the level of histone H1 0 and the growth rate in Morris hepatomas in rats, but increased levels were described by Medvedev and Medvedeva (1980b) in spontaneous hepatomas in ageing mice.…”

The characterization of non‐histone proteins whose amounts increase in chromatin from mouse hepatocarcinomas

“…The study of cancer-specific chromatin proteins has mainly concentrated on the analysis of non-histone proteins extracted with 0.35 M NaCl or phenol. In similar studies of different transplantable hepatomas, several minor tumour-specific proteins have been identified (Yeoman et al, 1973;Orrick et al, 1973;Gronow and Thakrah, 1974;Tsanev and Hadjiolov, 1978;James et al, 1977).…”

Chemical crosslinking of histone H1° to histone neighbours in nuclei and chromatin

“…In addition, it is probably the only histone fraction that considerably changes during malignant transformation. Usually tumors are characterized by a decreased level of Hl' [6,7], although reports to the contrary are also available [&lo].…”