Suppression of growth and cancer‐induced angiogenesis of aggressive human breast cancer cells (MDA‐MB‐231) on the chorioallantoic membrane of developing chicken embryos by E‐peptide of pro‐IGF‐I

Abstract

E-peptide of the pro-Insulin-like growth factor-I (pro-IGF-I) is produced from pre-pro-IGF-I by proteolytic cleavage in the post-translational processing. Previous in vitro studies conducted in our laboratory showed that Ea4-peptide of rainbow trout (rt) pro-IGF-I or Eb-peptide of human (h) pro-IGF-I exhibited activities including induction of morphological differentiation, inhibition of anchorage-independent cell growth and suppression of invasion of several well established human cancer cell lines such as MDA-MB-231, HT-29, SK-N-F1, and HepG-2 (Chen et al. [2002] Gen Comp Endocrinol 126:342-351; Kuo and Chen [2002] Exp Cell Res 280:75-89). Seeding of aggressive human breast cancer cells, MDA-MB-231, on the chorioallantoic membrane (CAM) of 5 days old chicken embryos resulted in rapid growth and invasion of the cells and induction of blood vessel formation around the MDA-MB-231 cell mass in the chicken embryos. The invasion of MDA-MB-231 cells in the chicken embryos was further confirmed by immunocytochemistry. The rapid growth and invasion of MDA-MB-231 cells and the induction of blood vessel formation by MDA-MB-231 cells on chicken CAM are inhibited by treatment with a single or multiple doses of rtEa4- or hEb-peptide. Furthermore, a dose-dependent inhibition of angiogenesis by rtEa4- or hEb-peptide was also demonstrated by the chicken CAM assay. Results of microarray analysis of human gene chips (containing 9,500 unique cDNA clones) and confirmation by comparative real-time RT-PCR analysis showed that a group of genes related to cancer cell activities are up- or down-regulated in MDA-MB-231 cells transfected with a rtEa4-peptide gene. Together these results confirm the anti-tumor activity of rtEa4- and hEb-peptides, and further suggest that these peptides could be developed as therapeutics for treating human cancers.

Induction of Apoptosis in Human Cancer Cells by Human Eb- or Rainbow Trout Ea4-Peptide of Pro-Insulin-Like Growth Factor-I (Pro-IGF-I)

“…These results are consistent with those reported in mammals (Siegfried et al, 1992;Matheny et al, 2010;Yang and Goldspink 2002). Further studies conducted in our laboratory showed that both recombinant rtEa4-or synthetic hEbpeptide exerted unexpected anti-cancer cell activities in established human cancer cell lines such as MDA-MB-231, HT-29, HepG2, SK-N-F1, SKOV-3A, PC-3 and OVCAR-3B (Chen et al, , 2007Kuo and Chen 2002). These activities include: (i) induction of morphological differentiation and inhibition of anchorage-independent growth, (ii) inhibition of invasion and metastasis, and (iii) inhibition of cancer-induced angiogenesis.…”

“…Recombinant rtEa4-peptide, hEb-peptide and control protein were prepared following the method described by our laboratory (Tian et al, 1999;Kuo and Chen, 2002;Chen et al, 2007). Briefly, E. coli cells, transformed with an expressing vector pET-15b (Novagen, EMD Chemicals, Gibbstown, NJ) containing the coding sequence of rtEa4-peptide or hEb-peptide, were cultured in 5 ml of LB broth for 4 h, diluted to 500 ml LB broth and allow the culture to grow at 37 o C. The culture was induced with 1 mM isopropyl β-D-thiolactopyranoside (IPTG) at an OD 600 of 0.6-0.8 for 2 h. Induced cells were harvested by low speed centrifugation and resuspended in 10 ml of a binding buffer (50 mM imidazole, 0.5 M NaCl, 20 mM Tris-HCl, pH 7.9).…”

“…Certain anti-cancer drugs and agents which have been identified as potential effective cancer treatment can restore normal apoptotic pathways (Fulda and Debatin, 2006;Yang et al, 2008). Since rtEa4-and hEb-peptides have been shown to possess anti-cancer activities in vitro in a variety of human cancer cells Chen et al, 2007), it would be of great interest to determine if these peptides can also induce apoptosis in human cancer cells. In this paper, we report that rtEa4-and hEb-peptide of pro-IGF-I induces apoptosis in various human cancer cell lines via both extrinsic and intrinsic pathways.…”

Differential expression of IGF-1 mRNA isoforms in colorectal carcinoma and normal colon tissue

“…The number of IGFs produced reflects the type of epithelial cells and the type of cellular growth (45). Various transcripts and variable IGF-1 precursor peptides act, first of all, as mitogenic factors but they may also inhibit the growth of neoplastic cells (17,18,26,27).…”

“…Peptide Ea which is composed of 35 amino acids is spliced out from the C terminal region of premature IGF-1 (i.e., pre-protein). It may be responsible for both mitogenic (26) and inhibitory effects on cancer cell growth (27). Furthermore, peptide Eb, which is composed of Eb1 and Eb2 peptides may exert mitogenic effects on IGF-1 independently; however, the activity of both peptides differs in various types of tissue (28).…”