Substantial changes in gene expression of Wnt, MAPK and TNFα pathways induced by TGF-β1 in cervical cancer cell lines

Transforming growth factor-beta 1 (TGF-beta 1) is a potent inhibitor of epithelial cell proliferation. During the development of cervical carcinoma however, an increase in production of TGF-beta 1 is accompanied by decreased sensitivity for the growth-limiting effect of TGF-beta 1. TGF-beta 1 has an anti-proliferative effect on cells of the immune system and thus can be advantageous for tumor progression. The aim of the present study was to determine the effect of TGF-beta 1 on mRNA expression profile of genes in pathways involved in cell growth and cell death, in cervical carcinoma cell lines with different sensitivity to TGF-beta 1. For this purpose, we have investigated changes in gene expression in TGF-beta 1 stimulated cervical cancer cell lines with high (CC10B), intermediate (SiHa) and low (HeLa) sensitivity to the anti-proliferative effect of TGF-beta 1, at timepoints 0, 6, 12 and 24 h. Microarray analysis, using Affymetrics focus arrays, representing 8973 genes, was used to measure gene expression. In our study novel target genes involved in tumor necrosis factor alpha (TNF alpha), mitogen-activated protein kinase (MAPK) and wingless type (Wnt) pathways in response to TGF-beta 1 were found. Substantial differences in gene expression between TGF-beta 1 sensitive and insensitive cell lines were observed involving genes in TNF alpha, MAPK, Wnt and Smad pathways. Since these pathways are implicated in cell proliferation and cell death, these pathways may play a role in determining the overall sensitivity of a cell to TGF-beta 1 induced cell growth inhibition. The results were subsequently validated by quantitative real-time PCR. Increased resistance to TGF-beta 1 induced cell growth inhibition was correlated with an elevated production of TGF-beta 1 by the cell lines, as measured by enzyme linked immunosorbent assay. TGF-beta 1 production did not inhibit cell growth, since blocking TGF-beta 1 protein by anti-TGF-beta had no effect on cell proliferation. TGF-beta 1 excretion by tumor cells more likely contributes to paracrine stimulation of tumor development.