Influence of novel KGFR tyrosine kinase inhibitors on KGF-mediated proliferation of breast cancer.

BACKGROUND: Keratinocyte growth factor (KGF) acts at the KGF receptor (KGFR) to produce a rapid stimulation of breast cancer cell proliferation and motility which is mediated via the Erk signaling pathway. Enhancement of KGF/KGFR signal transduction may be an early step in the metastatic progression of breast cancer. Receptor modeling of KGFR was used to identify selective KGFR tyrosine kinase (TK) inhibitor molecules that have the potential to bind selectively to the KGFR. The present study evaluated the biological activity of 57 of these KGFR TK inhibitor compounds on breast cancer cells. MATERIALS AND METHODS: These compounds were tested for their ability to inhibit KGF-mediated breast cancer cell proliferation in MCF-7 breast cancer cells. Furthermore, the effects of the most effective proliferation inhibitors were examined on Erk signaling and on the relative density of cell membrane KGFR. RESULTS: It was observed that 27 of the 57 compounds tested produced a 20% or greater reduction in KGF-mediated proliferation; while five compounds produced greater than 50% inhibition. In addition, the most potent inhibitors also reduced Erk signaling and cell membrane density of the KGFR. CONCLUSION: The compounds examined appear to be selective KGFR inhibitors which inhibit KGF-mediated activity and reduce the expression of KGFR on cancer cells. These results may lead to the development of a novel class of anticancer agents for the prevention of metastatic cancer progression.

Development of keratinocyte growth factor receptor tyrosine kinase inhibitors for the treatment of cancer.

BACKGROUND: The mammary glands of adult female animals are remarkably sensitive to keratinocyte growth factor (KGF). KGF acts at the KGF receptor (KGFR) to produce a rapid and profound stimulation of breast cancer cell proliferation and motility. Further, KGF-induced motility in breast cancer cells is mediated via the Erk1/2 signaling pathway. Thus, enhancement of KGF/KGFR signal transduction may be an early step in the metastatic progression of breast cancer. Receptor modeling of KGFR was used to identify selective KGFR tyrosine kinase inhibitor (TKI) molecules with high receptor affinity. The present study describes the synthesis and biological activity of three of the KGFR TKI compounds. MATERIALS AND METHODS: Computer modeling of the KGFR was used to create a virtual library of compounds that have the potential to bind with high affinity to the KGFR. Three of these compounds were synthesized and tested in this study. The compounds were tested for their ability to inhibit KGF-mediated breast cancer cell proliferation and motility using a culture wounding assay. In addition, the effect of the most potent KGFR TKI compound on the relative density of cell membrane KGFR was measured using immunocytochemistry. RESULTS: It was observed that the KGFR TKIs decreased KGF-mediated activity as predicted by computer modeling. In addition, the most potent inhibitor also reduced the density of the KGFR on the membrane of the cancer cells. CONCLUSION: The novel inhibitors identified in this project are selective KGFR inhibitors which appear to reduce the expression of KGFR on cancer cells. These results may lead to the development of a novel class of anticancer agents for the chemoprevention of metastatic cancer development and provide a new approach in the treatment of breast cancer.

Keratinocyte Growth Factor-Mediated Pattern of Gene Expression in Breast Cancer Cells.

BACKGROUND: Breast cancer metastasis is associated with the motility and invasiveness of breast cancer cells. In a previous study we reported the motility enhancement effect of keratinocyte growth factor (KGF) on breast cancer cells. This study established and characterized the influence of KGF on breast cancer cell motility and determined that KGF-induced motility was observed only in estrogen receptor-positive breast cancer cells. The objective of the present study was to identify genes involved in the KGF motility response in human breast cancer cells. MATERIALS AND METHODS: Using cDNA expression assays, we compared the expression of mRNA in control and KGF-treated MCF-7 breast cancer cells. Scatter plots and cluster analysis of gene expression were used to determine KGF-mediated gene expression patterns. RESULTS: It was determined that over 100 genes were up- or down-regulated from 3-100 fold at 1h following KGF treatment. We identified up-regulated and down-regulated target genes that are associated with some aspect of tumor progression, proliferation or metastasis. CONCLUSION: Knowledge of specific genes and patterns of gene regulation associated with KGF-enhanced cell motility may provide important new information concerning the mechanisms involved in tumor metastasis. In addition, these genes and/or protein products may serve as novel therapeutic targets or biomarkers of metastatic progression. The pattern gene of expression observed in this study provides new information on the molecular signature associated with the motility and metastatic progression of breast cancer.