Inhibition of proliferative and invasive capacities of breast cancer cells by arginine-glycine-aspartic acid peptide in vitro

Abstract

Abstract. The Arg-Gly-Asp (RGD) sequence was selected by using phage-display peptides to target tumors, focusing on targeting ·(v) integrins in tumor blood vessels. Recent studies suggest that peptides containing the RGD sequence can bind to tumor cells, as well as tumor endothelial cells. To investigate whether the RGD peptide has other effects on tumor cells expressing ·(v) integrins, besides its tumor targeting capability, we designed and synthesized a 10-amino peptide that contained the RGD sequence in a cyclic conformation with a disulfide bond, which specifically bound to breast cancer cell lines MDA-MB-231 and MCF-7. We found that this RGD peptide, GCGGRGDGGC, inhibited tumor cell proliferation in a dosedependent manner, and also induced apoptosis and G1-phase cell cycle arrest in both of the cell lines that bound and internalized the peptide. Normal ovarian epithelial cells, which did not bind the RGD peptide, were unaffected. RGD peptide treatment also reduced cell invasiveness in both cell lines in vitro. This study suggests that the RGD peptide not only possesses tumor targeting capacity, but also has direct tumor cytotoxic and invasiveness inhibition effects dependent on the blockage of ·(v) integrin activity, which would make it more efficient in tumor targeting therapy. IntroductionTargeting agents specifically to tumors and their metastases is a central challenge in improving existing cancer detection and therapy. Directing therapeutic agents to tumor cells, tumor blood vessels or tumor lymphatic vasculature is likely to enhance the efficacy of anti-cancer drugs and decrease side effects (1). Different strategies have been pursued to achieve this goal, among which 'homing' peptides are promising alternatives because they bind to surface molecules specific to the tumor, and tumor endothelial and tumor lymphatic cells (2-4), but are smaller than other agents such as antibody fragments, which allow them to easily penetrate tumor tissues. A prominent example for homing peptides is an Arg-Gly-Asp (RGD) sequence that was selected by using phage-display peptides to target tumors, focusing on targeting ·(v) integrins in tumor blood vessels (5). The RGD motif is present in many extracellular matrix components, such as fibronectin and vitronectin, and binds to integrins. Peptides containing the RGD sequence are commonly employed in tumor imaging (6,7) and tumor targeting therapy while coupled with therapeutic agents such as radionucleotides (8,9) and chemotherapeutic drugs (10,11).The RGD-peptide receptor-·(v) integrins are also expressed on the surface of many kinds of tumor cells. Studies indicate that the RGD sequence can bind not only to tumor endothelial cells, but also to tumor cells in vivo (3,12). And in vitro, the RGD peptide can be internalized by tumor cells (13). It is known that ·(v) integrins can mediate adhesion and migration in some tumor cell lines (13) and regulate cell proliferation and survival (14). However, whether the RGD peptide has any direct anti-tumor effects on tumor cells expr...

Syntheses and in vitro antitumor activities of ferrocene-conjugated Arg-Gly-Asp peptides

“…4). These results are in accordance with the observations by Ma and coworkers that RGD peptide inhibited cancer cell cycle proliferation by arresting cells at G1 phase [40]. Whereas, our findings differ somewhat from those reported by Dia et al, who found that lunasin, a RGD cancer preventive peptide, induced apoptosis in human colon cancer cells by arresting cell cycle at G2/M phase [41].…”

Exploring new near-infrared fluorescent disulfide-based cyclic RGD peptide analogs for potential integrin-targeted optical imaging

“…Our results demonstrated that disulfide-based cyclization may provide an efficient approach for studying receptor binding affinity and selectivity of RGD peptides as well as enzymatic and metabolic stability of RGD peptides employed for integrin targeting 1, 45, 46. As described above, we have successfully synthesized the near-infrared fluorescent disulfide cyclic RGD peptide and evaluated their integrin α v β 3 binding.…”

Identification and Characterization of a Peptide with Affinity to Head and Neck Cancer

“…For applications in patients, it is important to consider the toxicity of a new compound. Because other RGD peptides were found to be cytotoxic by themselves (37), toxicity has to be investigated for HBP-1, too.…”