Tumor-Host Cell Hybrids in Radiochimeras

Abstract

F1 hybrid mice syngeneic or semiallogeneic with respect to the relevant tumor were lethally irradiated and then reconstituted with hemopoietic cells from strain CBAT6T6 mice. After chimerism had been established, the animals were inoculated with solid or ascites tumors. Tumor-host cell hybrids were selected from enzyme-deficient solid tumors by explanting the tumor cell suspension into hypoxanthine-amethopterin-thymidine containing medium. The selection of hybrid cells from ascites tumors was achieved by exploiting the difference between the ascites tumor cells and hybrid cells in their ability to adhere to the surface of culture vessels. T6T6 chromosomal and H-2 antigenic markers served to distinguish between the hemopoietic cells derived from the donor graft and the cells of the host. All solid tumors tested fused with cells of the irradiated host, whereas ascites tumors fused with repopulating cells ofhemopoietic origin.In two previous publications (1, 2) we have described the successful selective isolation of tumor-host cell hybrids from The type of host cell involved in the fusion is unknown. In order to assess the biological significance of the phenomenon, it was obviously important to define this, at least in outline. Radiation chimeras in which the host and the repopulating cells carried different markers appeared to present a possible approach to this question. MATERIALS AND METHODSThe experimental design was as follows. F1 hybrid mice syngeneic or semiallogeneic with respect to the test tumor were lethally irradiated and then reconstituted with CBAT6T6 hemopoietic cells. After chimerism had been established, the animals were inoculated with solid or ascites tumors. Tumor-host cell hybrids were selected as previously described (1, 2). T6T6 chromosomal and H-2 antigenic markers served to distinguish between the hemopoietic cells derived from the embryonic liver graft and the cells of the host.Production of Chimeras. C3H X DBA/2, C3H X C57B1, and C3H X C57 leaden F. hybrid mice, 6-8 weeks old, were lethally irradiated with 800 R (3). About 5 X 105 hemopoietic cells obtained from the liver of newborn CBAT6T6 mice were suspended in 0.5 ml of sterile Eagle's minimal essential medium and inoculated into the tail vein of an irradiated recipient. The development of chimerism was confirmed by examining metaphase plates of spleen or lymph node cells. As a rule, lymphopoietic and hemopoietic organs were repopulated with T6T6 marker positive cells within 2-3 weeks.Tumors. (a). Solid tumors. A9HT and B82HT are highly malignant variants selected from the L cell sublines, A9 and B82 (4). Like the original in vitro lines from which they were derived, A9HT and B82HT are enzyme-deficient; A9HT lacks hypoxanthinq -guanine -phosphoribosyltransferase (HGPRT), while B82HT lacks thymidine kinase (TK). Due to these enzyme deficiencies both lines are unable to grow on hypoxanthine-amethopterin-thymidine (HAT) medium. With inoculla of 4 X 104 to 4 X 104 cells, both lines grew progressively in newborn x-irradiated (4 J k...

Spontaneous fusion in vivo between normal host and tumor cells: possible contribution to tumor progression and metastasis studied with a lectin-resistant mutant tumor.

“…Given the fact that a number of laboratories These results, although they confirm those of Wiener and his colleagues (67,68), do differ in some interesting respects. First, it was shown by these authors that tumor-host hybrid cells isolated from solid tumors were the progeny of tumor cells that had fused with cells of the irradiated host, whereas hybrids isolated from ascites tumors fused with a repopulating cell of bone marrow origin in their allogeneic radiation chimeras.…”

“…Nature of the normal host cell(s) involved in the MDW4 tumor cell-host fusion in vivo: evidence for a bone marrow origin. Wiener and his associates reported that when tumor cells were grown as ascites in the peritoneal cavities of bone marrow radiation chimeras, the normal host cell involved in any in vivo spontaneous fusions which occurred was a bone marrowderived cell (67). In contrast, analysis of solid s.c. growing tumors revealed that the host cell involved in any fusion was not bone marrow derived, but was from another cell lineage (67).…”

“…Wiener and his associates reported that when tumor cells were grown as ascites in the peritoneal cavities of bone marrow radiation chimeras, the normal host cell involved in any in vivo spontaneous fusions which occurred was a bone marrowderived cell (67). In contrast, analysis of solid s.c. growing tumors revealed that the host cell involved in any fusion was not bone marrow derived, but was from another cell lineage (67). We therefore sought evidence to implicate a bone marrow cell being involved in our experimental model by injecting MDW4 into CBA/HT6T6 -.…”

“…The rationale is that all of the bone marrow-derived cells (such as macrophages, lymphocytes, hematopoietic cells, etc.) will have the H-2k antigen or T6 marker chromosomes or both of the CBA/HT6T6 strain (67). Hence the presence of these two markers in any WGAS revertants recovered from the radiochimeric recipients would implicate bone marrowderived cells as a source of normal cell fusion partners.…”

Acquired Expression of NFATc1 Downregulates E-Cadherin and Promotes Cancer Cell Invasion

“…Some cells might experience growth arrest and cell death (38)(39)(40), whereas others might exhibit increased malignancy (9,16), depending on their parental cell types and the tumor microenvironment. Identification and analysis of bona fide fused cells positive for NFATc1 expression in vivo will be necessary to validate a role for NFATc1 in tumor progression.…”