TGFβ1 regulation and collagen-release-independent connective tissue re-modelling by the ruthenium complex NAMI-A in solid tumours

Abstract Purpose . The objective of this study is to evaluate the fibrotic process induced in vivo by NAMI-A in mice with solid tumours. In addition, the in vitro effects of NAMI-A on collagen fibres and the expression of TGFβ 1 in TS/A adenocarcinoma cells, NIH/3T3 fibroblasts and co-culture of fibroblasts and tumour cells have also been studied. Methods . Collagen fibres release was assayed in supernatant of culture cells treated with 0.1 and 0.01 mM NAMI-A. TGFβ 1 was detected by RT-PCR and immunoblot on cellular lysates. Results . NAMI-A, given to mice bearing MCa mammary carcinoma at advanced stages of growth, increased the thickness of connective tissue and induced recruitment of leukocytes, particularly in the peritumour capsule. In vitro NAMI-A stimulated collagen production by NIH/3T3 fibroblasts and decreased collagen release by TS/A tumour cells after prolonged exposure, either after single cell treatment or in co-cultures. In co-cultures, NAMI-A, in a dose-dependent manner, down-regulated the expression of TGFβ 1 mRNA and protein in tumour cells and up-regulated it in fibroblasts. The isoform of this cytokine is involved in fibrosis, invasion and metastatic processes. Conclusions . These data emphasize the ability of NAMI-A to evoke beneficial effects from healthy cells against tumour growth and metastases. The contribution of fibroblasts to the fibrosis arising in tumour masses is due to TGFβ 1 , and its down-regulation in tumour cells might explain the documented reduction of gelatinase release.