Peters D G, Hoover R R, Gerlach M J, Koh E Y, Zhang H, Choe K, Kirschmeier P, Bishop W R, Daley G Q
Whitehead Institute, Cambridge, MA; Division of Hematology/ Oncology, Massachusetts General Hospital, Boston, MA 02142, USA.
Blood. 2001 Mar 1;97(5):1404-12. doi: 10.1182/blood.v97.5.1404.
BCR/ABL, the oncoprotein responsible for chronic myeloid leukemia (CML), transforms hematopoietic cells through both Ras-dependent and -independent mechanisms. Farnesyl protein transferase inhibitors (FTIs) were designed to block mutant Ras signaling, but they also inhibit the growth of transformed cells with wild-type Ras, implying that other farnesylated targets contribute to FTI action. In the current study, the clinical candidate FTI SCH66336 was characterized for its ability to inhibit BCR/ABL transformation. When tested against BCR/ABL-BaF3 cells, a murine cell line that is leukemogenic in mice, SCH66336 potently inhibited soft agar colony formation, slowed proliferation, and sensitized cells to apoptotic stimuli. Quantification of activated guanosine triphosphate (GTP)-bound Ras protein and electrophoretic mobility shift assays for AP-1 DNA binding showed that Ras effector pathways are inhibited by SCH66336. However, SCH66336 was more inhibitory than dominant-negative Ras in assays of soft agar colony formation and cell proliferation, suggesting activity against targets other than Ras. Cell cycle analysis of BCR/ABL-BaF3 cells treated with SCH66336 revealed G2/M blockade, consistent with recent reports that centromeric proteins that regulate the G2/M checkpoint are critical farnesylated targets of FTI action. Mice injected intravenously with BCR/ABL-BaF3 cells developed acute leukemia and died within 4 weeks with massive splenomegaly, elevated white blood cell counts, and anemia. In contrast, nearly all mice treated with SCH66336 survived and have remained disease-free for more than a year. Furthermore, SCH66336 selectively inhibited the hematopoietic colony formation of primary human CML cells. As an oral, nontoxic compound with a mechanism of action distinct from that of ABL tyrosine kinase inhibition, FTI SCH66336 shows promise for the treatment of BCR/ABL-induced leukemia.
BCR/ABL是导致慢性髓性白血病（CML）的癌蛋白，它通过Ras依赖和非依赖机制转化造血细胞。法尼基蛋白转移酶抑制剂（FTIs）旨在阻断突变型Ras信号传导，但它们也抑制具有野生型Ras的转化细胞的生长，这意味着其他法尼基化靶点也参与FTI的作用。在本研究中，对临床候选FTI SCH66336抑制BCR/ABL转化的能力进行了表征。当针对BCR/ABL - BaF3细胞（一种在小鼠中具有致白血病性的鼠细胞系）进行测试时，SCH66336有效抑制软琼脂集落形成，减缓增殖，并使细胞对凋亡刺激敏感。对活化的鸟苷三磷酸（GTP）结合的Ras蛋白进行定量以及针对AP - 1 DNA结合的电泳迁移率变动分析表明，Ras效应通路受到SCH66336的抑制。然而，在软琼脂集落形成和细胞增殖分析中，SCH66336比显性负性Ras更具抑制作用，这表明其对Ras以外的靶点也有活性。对用SCH66336处理的BCR/ABL - BaF3细胞进行细胞周期分析显示出现G2/M期阻滞，这与最近的报道一致，即调节G2/M期检查点的着丝粒蛋白是FTI作用的关键法尼基化靶点。静脉注射BCR/ABL - BaF3细胞的小鼠发生急性白血病，并在4周内死亡，伴有脾脏肿大、白细胞计数升高和贫血。相比之下，几乎所有用SCH66336治疗的小鼠都存活下来，并且在一年多的时间里没有疾病。此外，SCH66336选择性抑制原发性人类CML细胞的造血集落形成。作为一种口服无毒化合物，其作用机制不同于ABL酪氨酸激酶抑制，FTI SCH66336在治疗BCR/ABL诱导的白血病方面显示出前景。
