Abstract
Previous reports have indicated that reconstituted basement membrane (matrigel), when co-injected with either established or primary human tumour cells, can improve the growth of subcutaneous xenografts in nude mice. The human adenocarcinoma cell lines A549, SW480, and WiDr, and the human fibrosarcoma cell line HT1080scc2 exhibit varying degrees of tumourigenicity in nude mice. All these lines showed increased tumorigenicity and/or growth rate, together with a change towards a more differentiated tissue morphology, when co-injected with matrigel into nude mice. Experiments using A549 cell line have indicated that the effect of matrigel is concentration-dependent and that increased growth rate is not maintained when xenografts grown with matrigel are passaged into further mice. These results strongly suggest that increased tumour growth results from the improved growth conditions afforded by matrigel, rather than from the selection of subpopulations of the most tumourigenic cells. Increased growth of intracaecal tumours arising from the co-injection of SW480 cells with matrigel, indicate a possible use for matrigel in the development of more relevant animal models using the orthotopic site. Purified laminin significantly increased the growth of sc tumours resultant from co-injection with either WiDr or A549 cells, whereas collagen IV or laminin with entactin showed no such effect. A role for free laminin in the stimulation of cell growth in the absence of an intact basement membrane is discussed.
Highlights
In this study, we present evidence of the tumour-enhancing properties of matrigel on a panel of four cell lines selected for their varied growth properties in vivo, together with observations on the concentration dependence and non-sustainability of the observed effects on subsequent passage
It has been shown that metastases of human colorectal carcinomas can be studied in nude mice and that its outcome depends upon the metastatic capacity of the cells and the organ environment of implantation (Giavazzi et al, 1986)
Co-injection of cells with 10 mg ml' matrigel resulted in significantly increased tumour growth rates and final tumour volumes over cells injected with medium only, in three out of the four cell lines under investigation (Figure 1)
Summary
Matrigel and entactin-free laminin were purchased as isolates from the EHS mouse tumour Matrigel from the same batch was used in all experiments, in order to prevent any possible variability in growth-factor or inhibitor levels. Collagen type IV and laminin with entactin, isolated from the same source, together with fibrinogen and thrombin were obtained from Sigma (Gillingham, Dorset, UK). Laminin and matrigel were ready-formulated in phosphate-buffered saline (PBS). A solution of collagen type IV was made by dissolving 1.7 mg in 0.5 ml 0.25% acetic acid in cold PBS, followed by sonication, mixing and re-buffering to pH 7.0. Fibrinogen and thrombin were both dissolved in PBS
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