G-band analysis in a serially transplanted Rous rat sarcoma

Chromosome banding analysis of a new stemline of hypodiploid Hirosaki sarcoma established by single cell transplantation

A new hypodiploid stemline of the long-lasting ascites sarcoma, Hirosaki sarcoma (HS), was established by means of single-cell transplantation, and its G-, C- and NOR-banding patterns were compared with those of the predecessor stemline, with special notice taken of the structural alteration of marker chromosomes. Their chromosomal relationship was well explained by the rearrangement, t(M7pM8q): Translocation of the short arm of marker M7 to the NOR of marker M8 produced a new marker M8t, and the translocation-carrying variant cells grew into a subline. A new translocation-carrying stemline was formed from this subline by single-cell transplantation. Judging from the size and number of silver-positive NORs, the NOR activity was significantly higher in this stemline than in its predecessor. The increased NOR activity might have been partly responsible for the growth of a translocation-carrying variant cell into a new subline. Single-cell-mass transplantation may be one of the most effective systems for studying the proliferative ability of subline cells and for understanding the mechanism of stemline formation in transplantable rat ascites sarcomas.

Nonrandom involvement of chromosome 4 in the progression of rat prostatic cancer

Owing to progression of the original spontaneous Dunning R-3327 rat prostatic cancer, a large series of transplantable prostatic tumors have been isolated that differ widely in their histological degree of differentiation, growth rate, androgen sensitivity, and metastatic ability. Using these parameters as criteria, the full spectrum of disease progression is represented within this Dunning system of rat prostatic cancers, ranging from slow-growing, well-differentiated, androgen-sensitive, nonmetastatic forms to fast-growing, anaplastic, androgen-independent, highly metastatic forms. Cytogenetic analysis of the two least progressionally advanced Dunning cancers (i.e., histologically well-differentiated, slow-growing, nonmetastatic variants) demonstrated no structural or numerical chromosomal aberration, suggesting that the initial development of prostatic cancer may not require detectable cytogenetic changes. In contrast, all 16 of the progressionally more advanced Dunning variants analyzed had a series of characteristic structural and/or numerical chromosomal aberrations that minimally involved chromosome 4. This nonrandom involvement of chromosome 4 was consistently observed regardless of whether the karyotype of the cancer was near-diploid or hyperaneuploid, suggesting that chromosome 4 aberrations are specifically involved in the progression of rat prostatic cancer. In addition, all four variants that were highly metastatic had, besides aberration of chromosome 4, structural aberrations involving chromosomes 1, 2, and 11. Of the 14 variants that did not have a high metastatic ability, only two had a similar aberrations involving chromosomes 1, 2, 4, and 11, suggesting that these specific chromosomal aberrations may be necessary, albeit not sufficient, for a high metastatic ability of rat prostatic cancers.

Multiple common fragile sites are expressed in the genome of the laboratory rat

Splenic lymphocytes from Sprague Dawley and Fischer 344 rats were exposed to two chemicals known to induce common fragile site expression in man: fluorodeoxyuridine (in conjunction with the enhancing effects of caffeine) and aphidicolin. Of 39 sites that were significantly damaged in excess, 12 meet the criteria for fragility proposed in this investigation. Rat fragile sites appear to differ from those in man in that no common hierarchical frequency of expression is evident from the two methods of induction. In addition, a comparison of published cancer-specific chromosome breakpoints from a variety of rat tumors reveals little or no apparent concordance with the identified fragile sites. The rat is an animal model in which multiple common fragile sites can be induced and, as such, will be valuable for testing hypotheses concerning the biological basis of chromosomal fragility.

Cellular DNA regions involved in the induction of rat thymic lymphomas (Mlvi-1, Mlvi-2, Mlvi-3, and c-myc) represent independent loci as determined by their chromosomal map location in the rat

The induction of thymic lymphomas by Moloney murine leukemia virus in the rat is linked to provirus integration in at least four independent cellular DNA regions (Mlvi-1, Mlvi-2, Mlvi-3, and c-myc). Because sequences homologous to at least three of these regions (Mlvi-1, Mlvi-2, and c-myc) map to chromosome 15 in the mouse, the question was raised whether they are closely linked in the rat genome and whether provirus integration in any one of these regions affects the same functional domain in rat DNA. In this study, we identified the chromosomal map location of Mlvi-1, Mlvi-2, and Mlvi-3 in the rat by using mouse-rat somatic cell hybrids that lose the rat chromosomes. The results showed that Mlvi-1 maps similarly to c-myc to chromosome 7, and Mlvi-2 maps to chromosome 2. Mlvi-3 probably maps to chromosome 15. We conclude that Mlvi-1, Mlvi-2, and Mlvi-3 are separate and independent genetic loci. Although Mlvi-1 and c-myc map to the same chromosome, they are not related, as determined by hybridization and restriction endonuclease mapping. The chromosomal map location of Mlvi-1 to chromosome 7 and Mlvi-2 to chromosome 2 is interesting, since chromosomal aberrations involving these two chromosomes are reproducibly observed in rat neoplasias induced by a variety of agents.

Acid phosphatase-producing androgen-independent subline of rat prostatic adenocarcinoma (Dunning R3327 tumor) in cell culture

Establishment of a cell line derived from the androgen-independent subline of rat prostatic adenocarcinoma (Dunning R3327 tumor) is reported. Cells of this line produced acid phosphatase. When the cultured cells were transplanted to Copenhagen rats, solid tumors were formed. Histologically, the tumor consisted of spindle-shaped, large and bizarre polygonal cells; this feature was almost identical to that of the original tumor. Chromosomes were in the triploid range with seven frequently appearing marker chromosomes.

Cytogenetic changes during tumor progression towards invasion, metastasis and immune escape in the Eb/ESb model system

Related tumor lines which represent different stages in their progression towards metastatic capacity were investigated and compared at the chromosomal level. The parental low-metastatic tumor line (L5178Y/Eb) was derived from a long-term transplanted, chemically induced T-cell lymphoma of the DBA/2 mouse. The cytogenetic analysis included this Eb line, a spontaneous high metastatic variant thereof which expressed a distinct tumor-associated transplantation antigen (ESb TATA+), and an immunoresistant TATA-negative variant of the latter (ESb TATA-). All three cell lines were characterized by a near-diploid chromosome count and by some common chromosomal markers derived from Nos. 6, 13 and 16 Large-scale chromosomal rearrangments resulted in the formation of eight marker chromosomes in Eb cells, 16 in ESb TATA+ cells and 18 in ESb TATA- cells. Tumor progression in this system showed a tendency to monosomies, which could bring the corresponding genes to a hemizygous state and possibly to a release from repression. Chromosome 15 was trisomic in Eb cells, monosomic in ESb TATA+ cells and hardly detectable in ESb TATA- cells. The Ig heavy-chain gene-carrying region of both chromosomes No. 12 was found in translocation with chromosomes Nos. 5, 13 and 14 (Eb cells) and with Nos. 1 and 17 (ESb cells). ESb TATA- cells differed from ESb TATA+ cells at four different chromosomes (Nos. 5, 8, 14 and 15).

Chromosomal investigations of the Usubuchi sarcoma. II. Chromosomal alteration of the stem line cells revealed by differential staining techniques

Stem line cells of the Usubuchi sarcoma (US) were karyologically investigated by means of G-, C-, and N-banding methods in ten samples from the 1,923rd to 2,081st transfer generations, with special attention to the structural alteration of marker-1 chromosome. The US cells showed wide variations in chromosome constitution and number, while the modal number of chromosomes was consistently 64 in all the generations examined. The chromosome constitutions varied widely even in cells with the modal number. In the early stage (1,923rd to 1,936th generations) the US contained two major stem lines characterized by marker combinations such as 1-2-3-4(1)-4(3)-8 and 2-3-4(1)-4(2)-4(3)-8, occurring with nearly similar frequency. From the middle to later transfer stages (from the 2,004th to the 2,081st generations), the 1-2-3-4(1)-4(3)-8 stem line rapidly declined and finally disappeared. In contrast, the 2-3-4(1)-4(2)-4(3)-8 line became a predominant part of the stem line. The G- and C-banding and population analyses of the stem line cells strongly suggested that marker 4(2) might have been derived from marker 1 by a deletion of the distal half of its long arm. The US studied contained a few stem lines and various types of sublines, each karyologically characteristic. G-Banding analysis revealed various types of intra- and interchromosomal rearrangements probably due to occasional chromosomal mutations either in markers or in nonmarkers in both stem lines and sublines. It seems likely that the stem line cells of the US are not always stable, but rather variable, in their chromosome makeup during the course of multiplication and successive transfers.