acetyl-prolyl-histidyl-seryl-cysteinyl-asparaginamide and Neoplasm-Metastasis

Integrins are expressed by numerous tumor types including breast cancer, in which they play a crucial role in tumor growth and metastasis. In this study, we evaluated the ability of ATN-161 (Ac-PHSCN-NH2), a 5-mer capped peptide derived from the synergy region of fibronectin that binds to alpha5beta1 and alphavbeta3 in vitro, to block breast cancer growth and metastasis.. MDA-MB-231 human breast cancer cells were inoculated s.c. in the right flank, or cells transfected with green fluorescent protein (MDA-MB-231-GFP) were inoculated into the left ventricle of female BALB/c nu/nu mice, resulting in the development of skeletal metastasis. Animals were treated with vehicle alone or by i.v. infusion with ATN-161 (0.05-1 mg/kg thrice a week) for 10 weeks. Tumor volume was determined at weekly intervals and tumor metastasis was evaluated by X-ray, microcomputed tomography, and histology. Tumors were harvested for histologic evaluation.. Treatment with ATN-161 caused a significant dose-dependent decrease in tumor volume and either completely blocked or caused a marked decrease in the incidence and number of skeletal as well as soft tissue metastases. This was confirmed histologically as well as radiographically using X-ray and microcomputed tomography. Treatment with ATN-161 resulted in a significant decrease in the expression of phosphorylated mitogen-activated protein kinase, microvessel density, and cell proliferation in tumors grown in vivo.. These studies show that ATN-161 can block breast cancer growth and metastasis, and provides a rationale for the clinical development of ATN-161 for the treatment of breast cancer.

Topics: Adenocarcinoma; Animals; Bone Neoplasms; Breast Neoplasms; Cell Growth Processes; Cell Line, Tumor; Female; Green Fluorescent Proteins; Humans; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasm Metastasis; Neovascularization, Pathologic; Oligopeptides; Radiography; Soft Tissue Neoplasms; Transfection; Xenograft Model Antitumor Assays

Using naturally serum-free SU-ECM basement membranes as invasion substrates showed that plasma fibronectin was necessary to stimulate invasion by DU 145 human and metastatic MATLyLu (MLL) rat prostate carcinoma cells. This activity mapped to the PHSRN sequence, which induced invasion through alpha5beta1 integrin. PHSCN, a competitive inhibitor, blocked both PHSRN- and serum-induced invasion. Acetylated, amidated PHSCN (Ac-PHSCN-NH2) was 30-fold more potent; however, Ac-HSPNC-NH2 was inactive. Rats receiving injections s.c. with 100,000 MLL cells were treated systemically by i.v. injection three times weekly with 1 mg of either Ac-PHSCN-NH2 or Ac-HSPNC-NH2 beginning 24 h later, three times weekly with 1 mg of Ac-PHSCN-NH2 beginning only after surgery to remove large (2 cm) MLL tumors, or were left untreated. MLL tumors grew rapidly in Ac-HSPNC-NH2-treated and in untreated rats. MLL tumor growth in rats treated with Ac-PHSCN-NH2 beginning 1 day after MLL cell injection was reduced by 99.9% during the first 16 days of treatment, although subsequent tumor growth occurred. MLL tumor cryosections immunostained with anti-PECAM-1 showed that Ac-PHSCN-NH2 inhibited neovascularization by 12-fold during this time. Whether initiated after MLL cell injection or only after MLL tumor removal, Ac-PHSCN-NH2 treatment reduced the numbers of MLL lung colonies and micrometastases by 40- to >100-fold, whereas Ac-HSPNC-NH2 was inactive. Thus, Ac-PHSCN-NH2 may be a potent antitumorigenic and antimetastatic agent for postsurgical use prior to extensive metastasis.

Topics: Amino Acid Sequence; Animals; Antineoplastic Agents; Basement Membrane; Cell Survival; Chemotaxis; Fibronectins; Humans; Lung Neoplasms; Male; Neoplasm Invasiveness; Neoplasm Metastasis; Oligopeptides; Prostatic Neoplasms; Rats; Receptors, Fibronectin; Structure-Activity Relationship; Tumor Cells, Cultured