Tera-2 Cells Research Articles

Modulation of Fibroblast Growth Factor Receptor Expression and Signaling During Retinoic Acid Induced Differentiation of Tera 2 Teratocarcinoma Cells

We have analyzed the regulation of fibroblast growth factor receptors (FGFRs) during retinoic acid (RA) induced differentiation of Tera-2 human embryonal carcinoma cells. Undifferentiated Tera-2 cells expressed mRNAs for all four known FGFRs. Their differentiation led to loss of FGFR-4 mRNA expression and mRNA levels for FGFR-2 and FGFR-3 were considerably downregulated, whereas the mRNA levels for FGFR- I remained unaltered. A substantial decrease in binding of K-FGF was found to occur upon RA-induced differentiation of the cells. In undifferentiated Tera-2 cells FGF stimulation caused an increase of c-fos mRNA, and c-jun mRNAs, but no increase of junB mRNA, whereas in the differentiated cells, FGFs strongly stimulated the expression of all three genes. Thus differentiation of the Tera-2 cells leads to marked changes in FGFR gene expression as well as to complex alterations in their responses to exogenous FGFs.

Comparison of MRC-5 and continuous cell lines for detection of cytomegalovirus in centrifugation cultures

Continuous cell lines were assessed for use for rapid human cytomegalovirus (HCMV) detection procedures combining tissue culture, centrifugation, and immediate early antigen (IEA) immunostaining. Human cells (MRC-5 embryonic fibroblasts, U-373MG astrocytoma cells, differentiated teratocarcinoma (Tera-2) cells), murine cells (BALB/c-3T3 and Y-1 cells), BHK 21 hamster cells, and mink lung (ML) cells were first inoculated with HCMV laboratory strain. IEA synthezising cells were detected by immunoperoxidase assay using a monoclonal antibody. ML cells and differentiated Tera-2 cells exhibited more positive cells than MRC-5 cells. BHK 21, and MRC-5 cells were equivalent in sensitivity whereas U-373MG, BALB/c-3T3, and Y-1 cells had only reduced IEA positive cells. When 63 urine specimens were inoculated onto MRC-5, ML and differentiated Tera-2 cells, 20 (31.7%) were positive in MRC-5 cells versus 18 (28.5%) in ML or Tera-2 cells. Moreover, greater numbers of infected cells were detected in MRC-5 cells than in these two cell lines. MRC-5 cells were superior for detection of HCMV in clinical samples by centrifugation cultures.

HLA class I homologous transcripts in the human embryonal carcinoma cell line Tera-2

We have used the human teratocarcinoma-derived embryonal carcinoma cell line Tera-2 cl. 13 to explore the putative expression of novel HLA class I(-like) genes. Serological analyses revealed that Tera-2 cells do not express polymorphic HLA class I (-A, -B, -C) specificities, but do express HLA class I-like antigens. These phenotypic properties parallel those of certain mouse embryonal carcinoma cells. To study the expression of HLA class I(-like) genes in the Tera-2 cells two different approaches were used. Screening of a Tera-2 cDNA library with a full-length HLA class I cDNA probe under conditions that would allow for the identification of relatively distinct HLA class I-like sequences yielded 27 positive clones, all of which were of the regular HLA-A, -B, -C type. Reverse northern hybridizations of the restriction enzyme-digested Tlab region comprising cosmids with Tera-2 cDNA as the probe resulted in the identification of several putative human genes whose equivalents map within the mouse Tla region. However, none of these genes appeared to be structurally related to HLA class I. A putative H3.3 histone gene was identified in the proximal Tla region of the C57BL/10 mouse. It is concluded that no structural homologues of mouse Qa/Tla genes are expressed in the human developmental cell line Tera-2.

Productive infection of both CD4+ and CD4− human cell lines with HIV-1, HIV-2 and SIVagm

Human monolayer cells of various origins were shown to be susceptible to infection by HIV-1, HIV-2 and simian immunodeficiency virus obtained from African green monkeys (SIVagm). Immunoperoxidase staining revealed infection of 2-7% of the monolayer cells, although in order to achieve infection approximately 50-fold more virus was necessary than with CD4(+)-permissive lymphoma cells. No CD4-receptor antigen expression by fibroblastoid cells was detectable by immunofluorescence using several monoclonal antibodies (MAbs), although a low level of CD4-specific messenger RNA expression was revealed by Northern analysis (with the exception of Tera-1 and RD cells). Attempts to block viral infection by anti-CD4 MAbs indicated a CD4 receptor-mediated mechanism for all lines tested except RD cells. We conclude that a low level of CD4-receptor expression is sufficient to allow infection of fibroblastoid cells. The infectability of a CD4-negative cell line indicates a second pathway of cellular infection, possibly mediated by a cellular receptor distinct from the CD4 molecule.

Differential expression of the HLA class I multigene family by human embryonal carcinoma and choriocarcinoma cell lines.

We have studied the expression of both HLA class and the recently described HLA class I-like genes (HLA-E and HLA-6.0) in two human developmental tumor cell lines, that serologically could not be typed for HLA-A, -B, and -C. Evidence is presented that the teratocarcinoma Tera-2 stem cells express trace amounts of non-beta 2 microglobulin-associated classical HLA-A, -B, and -C Ag on their cell surface. The Jeg-3 human choriocarcinoma cells derived from fetal trophoblast express normal levels of surface beta 2 microglobulin associated with 45-kDa and 41-kDa H chains that display unique isoelectric points in IEF gels. The HLA-6.0 or HLA-E genes may encode the lower molecular mass component on Jeg-3 cells, because these genes express molecules of about 38 kDa and 41 kDa, respectively, when transfected to appropriate host cells. Transcripts homologous to the HLA-6.0 gene are found to be constitutively expressed in the Jeg-3 cells but not in Tera-2 cells, whereas HLA-E is not significantly transcribed in either cell line. Transcription of class I (HLA-A, -B, and -C) and class I-like (HLA-E and HLA-6.0) genes is up-regulated after treatment with IFN-gamma in Tera-2 cells, whereas the corresponding genes in Jeg-3 cells remain essentially unresponsive. The biologic role of trophoblast class I(-like) molecules in the context of the maternal acceptance of the fetal semiallograft is discussed.

Novel human MHC class I genes are expressed by tumour cell lines representing embryonic and extraembryonic tissues.

The expression of HLA class I(-like) genes was studied in two human developmental tumour cell lines representing embryonic (Tera-2) and extraembryonic (Jeg-3) origins. Neither cell line expresses polymorphic HLA-A, -B, -C antigens as determined by standard serological typing. Tera-2 cells express the HLA class I-like T cell system A (TCA) determinants; Jeg-3 cells are TCA negative. Northern blot analysis using an HLA class I alpha 3 domain specific probe revealed markedly reduced levels of HLA class I(-like) transcripts in both cell lines, which can be upregulated in Tera-2 cells by incubation with gamma interferon (gamma IFN). Immunoprecipitation studies with a large panel of HLA class I/beta-2 microglobulin (beta 2m) monoclonal antibodies (mAbs), detect low quantities of regular HLA class I heavy chains that are not associated with beta 2m on the surface of Tera-2 cells. In contrast, Jeg-3 cells express significant amounts of cell membrane beta 2m associated molecules of 41 and 45 kilodalton (kD). Screening of a Tera-2 cDNA library, yielded 30 clones that hybridize to a full length HLA class I cDNA probe. Sixteen have been characterized and represent HLA class I sequences, consistent with the haplotype of Tera-2. A similar screening of a Jeg-3 cDNA library isolated clones representing a single novel HLA-C-like sequence; this probably codes for the 45 kD cell surface molecules of Jeg-3. The 41 kD molecule may be encoded by the HLA-6.0 gene since this is constitutively expressed in Jeg-3 cells.

Insulin-like growth factors and the multiplication of Tera-2, a human teratoma-derived cell line.

A human teratoma cell line (Tera-2) was grown in serum-free medium, and the population multiplication was stimulated by the addition of somatomedins/insulin-like growth factors (IGFs). Both IGF-I and IGF-II gave maximal stimulation when added daily at 10 ng ml-1. The IGFs did not substantially change the labelling index of the cells, and the IGFs appeared to exert their effect on population multiplication by increasing cell survival. Membranes isolated from Tera-2 cells displayed both type 1 and type 2 IGF receptors.

Cell cycle analysis during retinoic acid induced differentiation of a human embryonal carcinoma-derived cell line

Several subclones of the human embryonal carcinoma (EC) cell line Tera-2 can be induced to differentiate in monolayer culture by retinoic acid (RA) to a flattened cell type with reduced growth rate. Using a method based on the transition probability model, we have analysed changes in cell cycle kinetics of Tera-2 cells during the differentiation process. Growth inhibition was shown to occur without a lag period and to be partly due to an increase in the duration of the S-phase, but with a relatively greater contribution from an increase in the duration of G1-phase. Since the fraction of the cell population in the G1-phase then doubled, cells accumulated in this part of the cycle. In contrast, the reduced proliferation rate of two murine EC cell lines, PC13 and P19, treated with RA occurs after a lag period of about two cell cycles and is mainly attributable to an increase in the duration of the S-phase. The results illustrate a differential response of human and murine EC cells to growth regulation by RA and again emphasize that although the stem cells of murine teratocarcinomas may provide a useful model, they are not identical to their human counterparts.

Human embryonal carcinoma cells and their differentiation in culture

Based on the study of two clonal cell lines, 2102Ep and TERA-2, isolated from human germ cell tumours, we have identified several properties that are commonly expressed by human embryonal carcinoma (EC) cells, the stem cells of teratocarcinomas. These properties include the expression of surface antigens SSEA-3, SSEA-4, TRA-1-60 and TRA-1-81, and the presence of cytokeratin in the cytoplasm. However, some human EC cells lack expression of SSEA-3 and -4, although glycolipids containing these epitopes can be extracted from such variant cells. Analysis of the glycolipid composition of TERA-2 cells suggests that the switching of oligosaccharide core structure synthesis from globo-series to lacto- and ganglio-series is a key event during the differentiation of these cells. Variant, SSEA-3 and -4-negative EC cells may have already initiated these changes while retaining other features of the EC phenotype. Other studies have indicated that human EC cells variably express class I MHC antigens. We have shown that interferon induces expression of these surface molecules in EC cells without inhibiting their growth or inducing their differentiation or resistance to viral infection.

Induction of Retrovirus Particles in Human Testicular Tumor (Tera-1) Cell Cultures: An Electron Microscopic Study<xref ref-type="fn" rid="FN2">2</xref>

The Tera-1 and Tera-2 cell lines, established from germ-cell tumors of the human testis, were examined by electron microscopy for particles with the morphology of retroviruses. Extracellular and budding particles were observed at low frequencies only in cultures of Tera-1 cells that had been treated with 5-iodo-2'-deoxyuridine and dexamethasone. No particles were detected in untreated cultures of Tera-1 cells or in any preparations of Tera-2 cells.