Transfection of human insulin-like growth factor-binding protein 3 gene inhibits cell growth and tumorigenicity: a cell culture model for lung cancer

Abstract

IGF-I and IGF-II are potent mitogens, postulated to exert autocrine/paracrine effects on growth regulation in human lung cancer. Their proliferative effects are modulated by IGF-binding proteins (IGFBPs), which are found in conditioned medium (CM) of lung cancer cell lines. The biological role of the IGFBPs, which are ontogenetically and hormonally regulated, is not fully understood. Both inhibitory and stimulatory effects on cell growth have been demonstrated. Exogenous IGFBP-3 has been consistently shown to block IGF action, inhibiting cell growth in vitro. In order to evaluate the action of endogenously produced IGFBP-3 on cell growth in lung cancer, we stably transfected the non-small cell lung cancer cell line NCI-H23 with human IGFBP-3 cDNA (resulting in NCI-H23 pOPI3/BP-3) or with the vector pOPI3CAT as control (resulting in NCI-H23 pOPI3CAT). RT-PCR confirmed expression of IGFBP-3-specific mRNA in NCI-H23 pOPI3/BP-3, but not in NCI-H23 or NCI-H23 pOPI3CAT. Western ligand blot and Western immunoblot analysis of CMs yielded strong signals of the characteristic 40-44 kDa human IGFBP-3 protein in NCI-H23 pOPI3/BP-3. An IGFBP-3 ELISA demonstrated a 20-fold increase in IGFBP-3 protein expression in NCI-H23 pOPI3/BP-3 as compared with NCI-H23. The growth of NCI-H23 pOPI3/BP-3 in serum-containing medium was significantly slower (1·7-fold) than that of NCI-H23 or the vector-transfected control NCI-H23 pOPI3CAT. While the proliferation rate of parental and vectortransfected cells could be stimulated by IGF-I, IGF-II, IGF-I analog Long R 3 IGF-I or insulin, that of NCI-H23 pOPI3/BP-3 could not. Xenotransplantation in nude mice resulted in marked tumor growth after the injection of NCI-H23 or NCI-H23 pOPI3CAT, but absent or minimal growth for the IGFBP-3-transfected cell line.These data suggest that IGFBP-3 is a potent inhibitor of cell growth in human lung cancer cell lines and may impair tumorigenicity in vivo.

Insulin-Like Growth Factor Axis and Oncogenic Human Papillomavirus Natural History

“…For example, in vitro data indicate that the inhibitory effects of IGFBP-3 are likely due to both its sequestration of IGF-I and IGF-Iindependent effects; specifically, IGFBP-3 can bind proteins involved in cell cycle in the nucleus (21) and has antiproliferative (22)(23)(24) and direct proapoptotic activities (25)(26)(27)(28). Thus, high IGFBP-3 levels could lead to less replication and/or greater loss of oncogenic HPV infected cells (that is, to levels below the threshold of detection).…”

RRR-α-Vitamin E Succinate Potentiates the Antitumor Effect of Calcitriol in Prostate Cancer without Overt Side Effects

“…Several independent reports showed that IGFBP-3 has potent antitumor activities in vitro and in vivo (43,44). A prospective study also showed that IGFBP-3 was inversely associated with prostate cancer risk (45).…”

Recombinant Human Insulin-like Growth Factor Binding Protein 3 Inhibits Growth of Human Epidermal Growth Factor Receptor-2–Overexpressing Breast Tumors and Potentiates Herceptin Activity In vivo

“…Endogenous overexpression of IGFBP-3 has been shown to significantly reduce tumor formation against human non-small-cell lung cancer and prostate xenografts (34,35). Delivery of IGFBP-3 into H1299 nonsmall-cell lung cancer xenografts via a recombinant adenovirus reduced tumor volume (36).…”