Transforming growth factor-β1, β2, and β3, urokinase and parathyroid hormone-related peptide expression in 8701-BC breast cancer cells and clones

Abstract

Abstract 8701-BC is a recently characterized cell line isolated from a primary ductal infiltrating carcinoma of the breast (d.i.c.), showing some pleomorphism in cell microanatomy at an ultrastructural level. We have obtained different sublines of 8701-BC cells by cloning in soft agar at different concentrations (0.3% and 0.6%), and we have characterized the cloned lines by some morphological and growth parameters. 8701-BC cells and clones have been submitted to analysis by reverse trans-criptase-linked polymerase chain reaction to detect mRNAs of various cytokines (transforming growth factor-βs, tumour necrosis factors, interleukin 1s, interleuk-in 6, parathyroid hormone-related peptide, gamma interferon) and of urokinase, which are bioactive molecules commonly involved in cell-cell and cell-stroma interactions at primary and/or secondary sites of invasion. The aims of the present investigation were to determine: (a) if the corresponding genes are active in 8701-BC cell line and (b) if the sublines tested exhibit transcriptional heterogeneity. The results obtained show that 8701-BC cells express transcripts of transforming growth factor-βs, urokinase and parathyroid hormone-related peptide (PTHrP), the latter product being responsible for the cancer-associated humoral hypercalcemic syndrome. Moreover, while the first two mRNAs are detectable in all the sublines tested, PTHrP is expressed almost uniquely by the clones isolated in 0.6% agar which exhibit a peculiar morphological appearance, a higher growth rate and a more active invasive behaviour in vitro. The correlation between PTHrP expression and the potentially more aggressive subpopulation(s) of 8701-BC cell line suggests the possibility to use also PTHrP as a marker of high risk of malignancy in breast carcinoma.