Tumorigenicity and H-2 expression of papillomavirus-transformed mouse cell lines

Abstract

Tumorigenicity in immunocompetent syngeneic mice and H-2 class I antigen expression of BPV1-transformed mouse cell lines had no correlation. H-2 expression was examined using monoclonal anti-(H-2Kb) and anti-(H-2Db) antibodies in immunofluorescence staining for flow cytometry analysis and by determining the sensitivity of the cells to cytolysis by allostimulated spleen cells. Nontumorigenic cell lines were as resistant as tumorigenic cell lines to natural killer activity. The results indicate that in our model defence by natural killer cells is not a decisive factor. The results also show that instead of or in addition to H-2 class I antigens other factors (e.g. the presence or absence of virus-specific antigens) are important in determining the tumorigenicity of BPV1-transformed cell lines.

Effect of interferon γ on the sensitivity of bovine-papilloma-virus(BPV1)-transformed cell lines to cell-mediated cytotoxicity

“…The treatment of our BPVl-transformed cell lines with IFNy increases their expression of H-2K and H-2D antigens. However, it is not known whether class I antigens, the expression of which has no relationship to the tumorigenic properties of BPVl-transformed cell lines [5], are the critical molecules in determining the sensitivity to lysis by syngeneic LAK cells. With our cell lines, the effect ofIFN 7 on the expression of cell-surface molecules other than class I antigens has not been determined.…”

“…Cell lines were also established from tumours grown in nude mice ("NUT" lines) or in B6 mice ("B6T" lines). Of the cell lines used in the present study, B6B22 is weakly tumorigenic in nude mice, B6B31.A is highly tumorigenic in B6 mice, and B6B31.CNuT.A is tumorigenic in nude mice but nontumorigenic in B6 mice [5]. The cell line B6MCA is a fibroblast line of B6 origin induced in vitro by 3-methylcholanthrene.…”

Bovine papillomavirus type 1-transformed primary mouse fibroblasts show no correlation between tumorigenicity and viral gene expression, but c-myc gene expression is elevated in tumorigenic cell lines

“…Tumorigenicity of a cell line in an immunocompetent host is also affected by immunological mechanisms, and we have addressed that question in a parallel series of studies (Laatikainen et al, 1990). In our analyses, clones containing integrated viral DNA sequences showed low levels of E6/E7 gene expression suggesting selective down-regulation of these genes on integration.…”

“…The two episomal cell lines B6B22 and B6B71 exhibit a very low and a high tumorigenicity in nude mice, respectively (Laatikainen et al, 1990). Lines derived from B6B71-induced nude mouse tumours produce tumours in B6 mice.…”

“…Transcription of BPV-1 early genes was lower in B6B71 than in B6B22 cells, and no specific features of expression could be associated with the tumorigenic phenotype. The tumour-inducing capacity of clones containing integrated BPV-1 DNA is variable (Mfintyj/~rvi et al, 1988;Laatikainen et al, 1990 B6B31-A, B6B31-C and B6B31-J can all form tumours in nude mice although the parental line B6B31 is nontumorigenic. The parental line B6B31 expressed low levels of BPV-l-specific transcripts from both the E6/E7 and E2/E50RF regions as compared to the tumorigenic clones (Table 1).…”