title: Thymopentin (TP5), an immunomodulatory peptide, suppresses proliferation and induces differentiation in HL-60 cells.
abstract: Thymopentin (Arg-Lys-Asp-Val-Tyr, TP5) has shown immuno-regulatory activities in humans. In the present study, we investigated the effects of TP5 on the proliferation and differentiation of a human promyelocyte leukemia cell line, HL-60. It is noteworthy that TP5 displayed concentration-dependent inhibitory effects on the proliferation and colony formation of HL-60 cells. Furthermore, the decrease or even disappearance of AgNORs from nucleoli was observed in HL-60 cells after the treatment with TP5. The suppression induced by TP5 was accompanied by an accumulation of cell cycle in the G0/G1 phase. Moreover, TP5 significantly increased the NBT-reduction activity of HL-60 cells. Cytofluorometric and morphologic analysis indicated that TP5 had induced differentiation along the granulocytes lineage in HL-60 cells. d-tubocurarine (TUB) significantly antagonized the inhibitory effects induced by TP5, whereas atropine did not exhibit such effect. All the results indicated that TP5 was able to significantly inhibit proliferation and induce differentiation in HL-60 cells. Our observations also implied that TP5 not only acted as an immunomodulatory factor in cancer chemotherapy, but is also a potential chemotherapeutic agent in the human leukemia therapy.
authors.affiliation: Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Department of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, 222 Tian Shui South Road, Lanzhou, 730000, PR China.
authors.forename: Ying-zhe
authors.initials: YZ
authors.lastname: Fan
authors.forename: Hui
authors.initials: H
authors.lastname: Chang
authors.forename: Ye
authors.initials: Y
authors.lastname: Yu
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.forename: Li
authors.initials: L
authors.lastname: Zhao
authors.forename: Ding-jian
authors.initials: DJ
authors.lastname: Yang
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology; D002453:Cell Cycle; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D018922:HL-60 Cells; D006801:Humans; D018950:Lipopolysaccharide Receptors / Q000032:analysis; D009580:Nitroblue Tetrazolium / Q000032:analysis; D010455:Peptides / Q000494:pharmacology*; D016622:Silver Staining; D016305:Thymopentin / Q000494:pharmacology*
chemical_list: D000276:Adjuvants, Immunologic; D018950:Lipopolysaccharide Receptors; D010455:Peptides; D009580:Nitroblue Tetrazolium; D016305:Thymopentin