Plasmacytoma cells

Aujame, L. Firko, H. (1988). The major inducible heat shock protein hsp68 is not required for acquisition of thermal resistance in mouse plasmacytoma cell lines. Mol. Cell. Biol. 8,5486-5494. 

In addition to these activities, IL-6 has been shown, in vitro at least, to regulate the growth and differentiation of various other cells — both normal and transformed. It inhibits the in vitro growth of human fibroblasts and endothelial cells. As both these cell types also synthesize IL-6, this may suggest the presence in vivo of a negative autocrine feedback loop (Figure 5.8). Plasmacytoma cells (transformed antibody-producing B lymphocytes), on the other hand, also secrete IL-6 and express and IL-6 receptor. In this case, however, the feedback loop is positive. 

Figure 5.8. Several cells secreting IL-6 also display IL-6 receptors on their surface, thus facilitating autocrine regulation by this interleukin. In the case of fibroblasts and endothelial cells, this regulation appears negative (inhibitory to cell growth). In the case of plasmacytoma cells, however, the autocrine loop is positive, with IL-1 stimulating further growth...

The development of hybridoma technology by Milstein and Kohler in 1975 revolutionized the antibody field and radically increased the purity and specificity of antibodies used in the clinic and for diagnostic tests in the laboratory. Hybridomas consist of antibody-forming cells fused to immortal plasmacytoma cells. Hybrid cells that are stable and produce the required antibody can be subcloned for mass culture for antibody production. Large-scale fermentation facilities are now used for this purpose in the pharmaceutical industry. 

J558L Mouse plasmacytoma cell line Obtained from G Koch, MRC Laboratory of Molecular Biology, Cambridge, UK... 

Coleclough, C., Cooper, D., Perry, R.P. (1980). Rearrangement of immunoglobulin heavy chain genes during B-lymphocyte development as revealed by studies of mouse plasmacytoma cells. Proc. Nad. Acad. Sci. USA 77,1422-1426. 

With Potter s development of experimental plasmacytoma in mice, it was established that the turnover of paraprotein (N2), or more simply the serum level (08), was directly related to the weight of solid soft-tissue plasmacytoma. In our laboratory an ascitic form of plasmacytoma has been studied, and using isotope dilution it has been possible to estimate the actual total number of plasmacytoma cells in a mouse. At the same time the serum level of paraprotein was measured and a simple correlation was shown (F2). To the best of my knowledge, this was the first time that the serum level of a tumor product had been directly related to the actually counted number of tumor cells. Incidentally it was noted that the paraprotein could be first detected in the serum, when a 23 g mouse had 3 million tumor cells. 

Several satisfactory plasmacytoma cell lines are available (Table 5.3). All the early lines produced myeloma proteins, so that hybridomas secreted three types of Ig the original myeloma proteins, the specific antibodies, and hybrid molecules. The X63 plasmacytoma, which produces a fully sequenced IgGl, was used in the original technique of Kohler and Milstein (1975). These X63 cells may undergo spontaneous fusion with each other and can be grown at very low cell densities making it relatively easy to clone hybrids. Several variant lines have been selected from this line (NS-1, Sp2, FO) some of which do not synthesize or secrete heavy or light chains. Sp2... 

Furthermore, the recombinations in switch variants, unlike those in normal B cells, are always restricted to the active IgH allele [32], Thus, it is likely that switching in plasmacytoma cells is different from physiological switching, not only by the criteria of frequency and pattern (see above) but also by that of type of recombination. Probably, it reflects the rate of spontaneous deletions within the IgH locus rather than that of switch recombinations. 

Immunoglobulin enhancers differ from previously identified viral enhancers in their spectrum of activity, enhancers from SV40 or polyoma virus being active in a variety of cell types [87,115,161,162]. Transfection experiments have established that both the IgH [81,82], and the k enhancers [84] are preferentially active in plasmacytoma cells. Although weak activity has been described in fibroblasts, this weak activity manifests a strong dependence on distance [88,89], The fact that some deletions of the IgH enhancer increase its activity in non-lymphoid transfectants has been used to infer the existence of repressor molecules in non-lymphoid cells... 

Park, C. H., Bergsagei. 0. E.. and McCulloch, E. A. Ascorbic acid a culture requirement for colony formation by mouse plasmacytoma cells. Science. 174 720-722.1971. 

Recently, we have demonstrated the existence of a poly(ADPR) polymerase activity associated with cytoplasmic free messenger ribonucleoprotein particles (mRNP) isolated from mouse plasmacytoma cells [4]. The enzyme does not require DNA for activity and is able to produce an ADP-ribosylation of some of the mRNP proteins. We have extended our observations to Krebs II ascites-tumor cells and to rat liver. In the present report, we will discuss some properties of this enzyme, particularly the activation by RNase A. 

Egly JM, Schmitt M, Elkaim R, Kempf J (1981) Protein kinases and their protein substrates in free messenger ribonucleoprotein particles and polysomes from mouse plasmacytoma cells. Eur J Biochem 118 379-387... 

Althou most experiments clearly indicate that early after infection ribosomal EEA is the first species of ENA to be inhibited, experiments using isolated nuclei (21, 22) from mengovirus infected L-cells and EMC virus infected mouse plasmacytoma cells indicate that the polymerase II activity (responsible for heterogeneous nuclear ENA and mENA synthesis) is inhibited 1-2 hours before ENA polymerase I and III activities (responsible for rENA and 48 and 58 ENA synthesis, respectively). No difference in activity and relative proportions of the three ENA polymerases, however was found after infection using solubilized enzymes assayed in the presence of exogeneous DNA as template (2l). It is assumed that the inhibition in whole cells results from an initiation defect, since these measurements using nuclei and solubilized enzymes do not measure true initiation. 0 he explanation as to why polymerase II should be inhibited before polymerase I when rENA synthesis is clearly the first to be inhibited in whole cells remains to be worked out. 

Purther evidence that cellular mRNA is not degraded after infection came from experiments using cellular mRNA extracted from infected cells to prime protein synthesis in extracts. From mouse plasmacytoma tumor cells Lawrence and Thach (26) isolated a poly(A)-containing 10S RNA fraction which in extracts was translated into a protein found in plasmacytoma cells, as determined by co-electrophoresis and tryptic mapping. This messenger RNA, when isolated from infected cells, was less active in translation than when isolated from uninfected cells by about However, mRNA... 

Another way in which picomaviruses could inhibit cellular protein synthesis would be to inactivate an initiation factor needed for cellular, but not viral, mENA translation. If this were the case one might expect to find a decreased capacity of extracts from infected cells to initiate translation of cellular mENAs compared to extracts from uninfected cells. Such studies have yielded a variety of results. In some laboratories no differences in activity were detected between extracts from xininfected cells and from EMC infected plasmacytoma cells or mengovirus infected Ehrlich ascites tumor cells (26, 44) In one laboratory the ability of extracts from infected cells to translate exogenously added encephalomyocarditis (EMC) virus ENA and total Krebs II ascites cell mENA was markedly diminished, but no evidence for the selective inhibition of translation of host cell mENA was obtained (52). 

SCHWARTZ, L.B., LAWRENCE, C., THACH, R.E. and ROEDER, R.G. Encephalomyocarditis virus infection of mose plasmacytoma cells. III. Effect on host RNA synthesis and RNA polymerases. 

Fig. 2. Poly(ADP-ribose) glycohydrolase activity in free mRNP. Free mRNP isolated from mouse plasmacytoma cells were p PJADP-ribosylated at 30 C with 200 iM NAD. SAB was added after 30 min of reaction. Aliquots were taken at various times and precipitated in TCA (20% final concentration). The precipitates were collected on GFB Whatman filters and the radioactivity measured. (A), 0 mM SAB ( ), 6 mM SAB ( ), 6 mM SAB, 4 mM ADP-iibose.

When expressed by transfected tumour cells, TNF decreased tumorigenicity of Chinese hamster ovary carcinoma cells (Oliff et al. 1987, Quin et al. 1995), J558L plasmacytoma cells (Blankenstein et al. 1991, Hoch et al. 1993), 1591-RE skin tumour cells (Teng et al. 1991), MCA-205 fibrosarcoma cells (Asher et al. 1991), and TS/A murine mammary adenocarcinoma (Allione et al. 1994), but had no influence on MCA-102 fibrosarcoma cells (Karp et al. 1993), and B16-F10 melanoma cells (Dranoff et al. 1993). TNA-a gene suppressed... 

Surprisingly, it was not a cell line from an ascorbate-dependent species which was first shown to respond to ascorbate in vitro, but a mouse plasmacytoma cell... 

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