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PubMed1995

WEHI-13VAR: a stable and sensitive variant of WEHI 164 clone 13 fibrosarcoma for tumor necrosis factor bioassay.

Bioassaying tumor necrosis factor (TNF) relies not only on a sensitive but also on a stable cell line towards TNF action. A variant of WEHI 164 clone 13, WEHI-13VAR, was characterized by us. This variant demonstrated both stability and high sensitivity towards rTNF-alpha or rTNF-beta when assayed in the presence of actinomycin-D (AcD). Fifteen subclones were generated from WEHI-13VAR (rTNF-alpha; ED50 range: 0.005-0.065 ng/ml). No clones were found more sensitive than the AcD-treated WEHI-13VAR cell line. An important feature of this line is its stable sensitivity. The stability of the cell line sensitivity towards rTNF-beta was demonstrated in the presence of AcD over a period of 16 months with an average ED50 of 0.046 +/- 0.004 ng/ml. In conclusion, unlike other TNF-sensitive cell lines in which the sensitivity is lost or the stability is unknown, WEHI-13VAR provides a sensitive, reliable and stable bioassay system to detect cytotoxin, TNF-alpha, and TNF-beta.

Animals↗
PubMed1992

Changes of host cell infiltration into Meth A fibrosarcoma tumor during the course of regression induced by injections of a BCG nucleic acid fraction.

MY-1, which consists of DNA and RNA extracted and purified from Mycobacterium bovis strain BCG, causes the regression of various experimental syngeneic tumors when injected intratumorally. In order to identify the host cells involved in the antitumor mechanism(s) of MY-1, we examined Meth A tumors inoculated intradermally to BALB/c mice, which were given multiple injections of MY-1 following tumor inoculation. Histological and immunohistochemical examinations were performed at several time points. On day 4 after inoculation, the MY-1-treated tumors were heavily infiltrated with a heterogeneous population of mononuclear cells with low density nuclei. The MY-1-injected tumors contained asialo-GM1-positive cells and Mac-1-positive cells, which indicated that the infiltrating mononuclear cells were natural killer cells and macrophages. On day 14 after inoculation, the tumors were infiltrated with a large number of L3T4-positive cells and fewer Lyt-2-positive cells, both of which were more abundant in the MY-1-treated tumors than in the control tumors. The observed sequence of host cell infiltration corresponded well with our previous studies which have indicated that the antitumor mechanism of MY-1 is divided into two phases, i.e. the early phase when natural killer cells and macrophages inhibit tumor growth, and the late phase when L3T4-positive cells act to induce tumor regression via a delayed-type hypersensitivity against tumor cells.

Animals↗
PubMed1991

Down-regulation of SPARC/osteonectin/BM-40 expression in methylcholanthrene-induced fibrosarcomas and in Kirsten-MSV transformed fibroblasts.

SPARC (secreted protein acid and rich in cysteine), also known as osteonectin or BM-40, is a glycoprotein associated with the extracellular matrix of bone as well as with many soft tissues that produce extracellular matrix, including matrix-producing tumours. Northern and slot-blot analyses were used to study SPARC expression in tumours induced in vivo by methylcholanthrene (MCA) and in transformed cells induced in vitro by Kirsten-MSV and SV-40 infection. MCA-induced tumours expressed SPARC mRNA at quantitatively different levels. Fibroblasts transformed in vitro by Kirsten-MSV, and, to a lesser extent, by SV-40, showed reduced levels of SPARC mRNA expression compared with normal fibroblasts. Run-on assay indicated that transcription of SPARC was lower in the Kirsten-MSV transformed cells than in the normal parental fibroblast culture. However, SPARC mRNA in the transformed culture was as stable as that in normal culture. The difference, therefore, between levels of SPARC mRNA in transformed and normal culture was mainly due to different rates of transcription. Cloned cell lines derived from the Kirsten-MSV transformed culture also showed heterogeneous expression of SPARC: two lines had high and two had low expression of the gene. The level of mRNA correlated with that of the protein secreted. The SPARC expression might contribute to the malignant phenotype.

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