Makiko Mizumoto

T140 analogs as CXCR4 antagonists identified as anti‐metastatic agents in the treatment of breast cancer

A chemokine receptor, CXCR4, and its endogenous ligand, stromal cell‐derived factor‐1 (SDF‐1), have been recognized to be involved in the metastasis of several types of cancers. T140 analogs are peptidic CXCR4 antagonists composed of 14 amino acid residues that were previously developed as anti‐HIV agents having inhibitory activity against HIV‐entry through its co‐receptor, CXCR4. Herein, we report that these compounds effectively inhibited SDF‐1‐induced migration of human breast cancer cells (MDA‐MB‐231), human leukemia T cells (Sup‐T1) and human umbilical vein endothelial cells at concentrations of 10–100 nM in vitro. Furthermore, slow release administration by subcutaneous injection using an Alzet osmotic pump of a potent and bio‐stable T140 analog, 4F‐benzoyl‐TN14003, gave a partial, but statistically significant (P≤0.05 (t‐test)) reduction in pulmonary metastasis of MDA‐MB‐231 in SCID mice, even though no attempt was made to inhibit other important targets such as CCR7. These results suggest that T140 analogs have potential use for cancer therapy, and that small molecular CXCR4 antagonists could potentially replace neutralizing antibodies as anti‐metastatic agents for breast cancer.

Identification of a CXCR4 antagonist, a T140 analog, as an anti‐rheumatoid arthritis agent

Several recent papers support the involvement of an interaction between stromal cell‐derived factor‐1 (SDF‐1/CXCL12) and its receptor, chemokine receptor CXCR4, in memory T cell migration in the inflamed rheumatoid arthritis (RA) synovium. Analogs of the 14‐mer peptide T140 were previously found to be specific CXCR4 antagonists that were characterized as not only HIV‐entry inhibitors but also anti‐cancer‐metastatic agents. In this study, a T140 analog, 4F‐benzoyl‐TN14003, was proven to inhibit CXCL12‐mediated migration of human Jurkat cells and mouse splenocyte in a dose‐dependent manner in vitro (IC50=0.65 and 0.54 nM, respectively). Furthermore, slow release administration by subcutaneous injection (s.c.) of 4F‐benzoyl‐TN14003 using an Alzet osmotic pump significantly suppressed the delayed‐type hypersensitivity response induced by sheep red blood cells in mice, and significantly ameliorated clinical severity in collagen‐induced arthritis in mice. As such, T140 analogs might be attractive lead compounds for chemotherapy of RA.

Enhancement of the T140-based pharmacophores leads to the development of more potent and bio-stable CXCR4 antagonists

A CXCR4 antagonistic peptide, T140, and its bio-stable analogs, such as Ac-TE14011, were previously developed. These peptides inhibit the entry of T cell line-tropic strains of HIV-1 (X4-HIV-1) into T cells. Herein, a series of TE14011 analogs having modifications in the N-terminal region were synthesized to develop effective compounds with increased biostability. Among these analogs, 4F-benzoyl-TE14011 (TF14013) showed the strongest anti-HIV activity derived from CXCR4-antagonism, suggesting that a 4-fluorobenzoyl moiety at the N-terminus of T140 analogs constitutes a novel T140-based pharmacophore for CXCR4 antagonists. Structure-activity relationship (SAR) studies on TE14011 analogs with N(alpha)-acylation by several benzoic acid derivatives have disclosed a significant relationship between the anti-HIV activity and the Hammett constant (sigma) of substituted benzoic acids. TF14013 was found to be stable in mouse serum, but not completely stable in rat liver homogenate due to deletion of the C-terminal Arg14-NH2 from the parent peptide. This biodegradation was completely suppressed by N-alkyl-amidation at the C-terminus. Taken together, the enhancement of the T140-based pharmacophores led to development of a novel CXCR4 antagonist, 4F-benzoyl-TE14011-Me (TF14013-Me), which has very high anti-HIV activity and increased biostability.

Topochemical exploration of potent compounds using retro-enantiomer libraries of cyclic pentapeptides

Cyclic pentapeptides have been adopted as conformationally restricted peptide templates to dispose pharmacophores of bioactive peptides. In our recent study, use of two orthogonal cyclic pentapeptide libraries involving conformation-based and sequence-based libraries containing critical residues of a bioactive peptide led to the discovery of potent downsized peptides that possess activity comparable to that of the parent peptide. The present study demonstrates that a third library consisting of retro-enantiomers (retro-inverso peptides) that possess not only all residues with the opposite configuration to those in the corresponding original peptide but also amino acid sequences with reversed arrangement, is important as an alternative library for rationally finding active compounds.