Paukovits W R, Moser M H, Binder K A, Paukovits J B
Department of Growth Regulation, University of Vienna, Austria.
Cancer Treat Rev. 1990 Sep;17(2-3):347-54. doi: 10.1016/0305-7372(90)90068-q.
We have previously shown that the stem cell inhibitory peptide pGlu-Glu-Asp-Cys-Lys (pEEDCK monomer) leads to a good tolerance of otherwise lethal multiple ara-C doses and an increased survival of ara-C + peptide treated mice. This effect was due to the prevention of drug-induced CFU-S proliferation, thus keeping stem cells in a quiescent state insensitive to ara-C. Here we show that the pEEDCK monomer also inhibits stem cell proliferation after clinically relevant (non-lethal) ara-C doses. This leads to a sustained (100%) stem cell number in the femoral bone marrow, which was greatly reduced without protective peptide treatment (27%). We have measured the kinetics of influx of CFU-S into the empty S-phase (after two consecutive ara-C injections). This influx reached peak levels of 60-70%; pEEDCK treatment reduced it to 25-30%. Due to its cysteine content the pEEDCK monomer is easily oxidized and forms a symmetric disulfide-bonded dimer (pEEDCK)2. This dimer is a potent stimulator of haemopoiesis. Various modes of protective peptide treatment (monomer and dimer) were investigated in conjunction with a standardized protocol of 2 x 300 mg/kg ara-C given 12 h apart. (a) ara-monomer-ara: The administration of pEEDCK-monomer 2 h before the second ara-C injection retarded the onset of neutropenia, shortened its duration and improved recovery after depression. The degree of short-term neutropenia was not changed. (b) ara-ara-HN2-dimer: Post chemotherapy infusion of the stimulatory (pEEDCK)2 dimer led to considerable increases of progenitor levels (6.8 CFU-GM/1000 bone marrow cells vs. 1.2 CFU-GM/1000 in normal mice) 2 days after cytostatic treatment when CFU-GM were not detectable in unprotected mice. This increase was followed by greatly elevated granulocyte counts (8000 PMN/mm3 vs. 750 PMN/mm3 in normal mice). In the dimer-treated mice, up to 75% of the peripheral leukocytes were mature PMN (normal, 10%). (c) ara-monomer-ara-dimer: ara-C and monomer treatment as above (a) followed by dimer infusion led to complete protection of haemopoiesis. Mice treated with the protective pEEDCK monomer plus stimulatory dimer did not develop the leukocyte depression seen in unprotected animals. Our results show that the haemoregulatory peptide monomer and dimer can be used to improve the haematological status of mice treated with clinically relevant doses of cytostatic drugs (anti-metabolite and alkylating, alone and in combination). The pEEDCK monomer and dimer are equally active also on human haemopoietic cells.(ABSTRACT TRUNCATED AT 400 WORDS)
我们之前已经表明，干细胞抑制肽pGlu-Glu-Asp-Cys-Lys（pEEDCK单体）能使小鼠对原本致死剂量的阿糖胞苷产生良好耐受性，并提高阿糖胞苷加肽处理组小鼠的存活率。这种效应是由于阻止了药物诱导的CFU-S增殖，从而使干细胞处于对阿糖胞苷不敏感的静止状态。在此我们表明，pEEDCK单体在临床相关（非致死）剂量的阿糖胞苷处理后也能抑制干细胞增殖。这使得股骨骨髓中的干细胞数量持续保持（100%），而在未进行保护性肽处理时该数量大幅减少（27%）。我们测量了CFU-S流入空S期的动力学（连续两次注射阿糖胞苷后）。这种流入达到峰值水平60 - 70%；pEEDCK处理将其降低至25 - 30%。由于其半胱氨酸含量，pEEDCK单体容易被氧化并形成对称的二硫键结合二聚体（pEEDCK）2。这种二聚体是造血的有效刺激剂。结合间隔12小时给予2×300mg/kg阿糖胞苷的标准化方案，研究了各种保护性肽处理方式（单体和二聚体）。（a）阿糖胞苷 - 单体 - 阿糖胞苷：在第二次注射阿糖胞苷前2小时给予pEEDCK单体可延迟中性粒细胞减少症的发作，缩短其持续时间并改善抑制后的恢复情况。短期中性粒细胞减少的程度没有改变。（b）阿糖胞苷 - 阿糖胞苷 - HN2 - 二聚体：化疗后输注刺激性（pEEDCK）2二聚体导致在细胞毒性治疗2天后祖细胞水平显著增加（6.8 CFU - GM/1000骨髓细胞，而正常小鼠为1.2 CFU - GM/1000），此时未受保护的小鼠中CFU - GM不可检测。随后粒细胞计数大幅升高（8000个PMN/mm3，而正常小鼠为750个PMN/mm3）。在二聚体处理的小鼠中，高达75%的外周白细胞是成熟的PMN（正常为10%）。（c）阿糖胞苷 - 单体 - 阿糖胞苷 - 二聚体：如上述（a）进行阿糖胞苷和单体处理，随后输注二聚体可实现对造血的完全保护。用保护性pEEDCK单体加刺激性二聚体处理的小鼠未出现未受保护动物中所见的白细胞减少。我们的结果表明，血液调节肽单体和二聚体可用于改善用临床相关剂量细胞毒性药物（抗代谢物和烷化剂，单独或联合使用）处理的小鼠的血液学状态。pEEDCK单体和二聚体对人造血细胞同样有活性。（摘要截断于400字）
