Tumor-stromal cell interactions modulate metalloproteinase and kalli Krein expression in direct and indirect co-culture cell models

Abstract

Introduction The crosstalk between tumor cells and surrounding stromal fibroblasts is now considered crucial for cancer progression, particularly in invasive tumors such as lung carcinomas. Tumor- stromal cell interactions might provide signal for regulating protease and protease inhibitor secretion in the tumoral microenvironment and modulate extracellular matrix (ECM) proteolysis and then tumor invasion. The aim of this study was to develop co-culture models with cancer cells, derived from a non-small cell lung carcinoma (NSCLC), and fibroblast cells. Expression of several MMPs, kallicrein 6 (KLK) and Tissue Factor Pathway inhibitor 2 (TFPI-2) was then measured in these models. Material and methods Two in vitro co-culture models were developed to evaluate the effects of direct or indirect contact between NSCLC NCI-H460 cells and CCD19-Lu fibroblast cells. In direct co-culture, both cells (ratio 1 :1) were cultured for 24 h in serum free medium. In indirect co-culture, conditioned media were collected from either confluent tumoral cells or fibroblasts grown in serum free medium during 24 h. Transcript levels of MMP-1, -2, -3, -9, -13 and –14, EMMPRIN (Extracellular Matrix MetalloPRoteinase Inducer), KLK6 and TFPI-2 were measured using specific quantitative real-time RT-PCR. Protein expressions were evaluated by Western Blotting and immunofluorescence staining. Results We found a 3-fold and 8-fold increase of MMP-3 and MMP-9 expression respectively in the direct co-culture compared to cells grown alone. Although the level was lower, KLK6 mRNA was also enhanced in direct co-culture. In indirect co-culture with CCD19Lu cultured with NCI-H460 conditioned medium, we observed an increase in MMP-1, -3, -9 and TFPI-2 transcripts. Except for MMP3 and KLK6, no difference in transcripts level were observed in the other indirect co-culture model, i. e NCI-H460 grown in CCD19Lu conditioned medium. Conclusion Our results indicate that direct or indirect contacts between tumors and surrounding fibroblasts modulate the expression of various proteinases. This effect might be mediated by soluble or/ and cell surface factors. Further investigations will be required to identify them.