Kawano Michio M, Ishikawa Hideaki, Tsuyama Naohiro, Abroun Saeid, Liu Shangqin, Li Fu-Jun, Otsuyama Ken-ichiro, Zheng Xu
Department of Bio-Signal Analysis, AMES, Graduate School of Medicine, Yamaguchi Univ, Ube, Japan.
Int J Hematol. 2002 Aug;76 Suppl 1:329-33. doi: 10.1007/BF03165278.
Human myeloma cells are heterogenous morphologically and phenotypically. Myeloma cells can be classified into at least 5 subpopulations; MPC-1-CD45+CD49e-, MPC-1-CD45-CD49e- immature myeloma cells, MPC-1+CD45-CD49e-, MPC-1+CD45+CD49e- intermediate myeloma cells and MPC-1+CD45+CD49e+ mature myeloma cells. Interleukin-6(IL-6) is a major growth factor for human myeloma cells, but only MPC-1-CD45+CD49e- immature myeloma cells can response directly to IL-6 to proliferate. In the U-266 cell lines, IL-6 can lead to the induction of CD45 expression and CD45+ U-266 cells can proliferate in response to IL-6. In primary myeloma cells, MPC-1-CD45-CD49e- immature myeloma cells sorted from bone marrow samples can be changed to CD45+ cells by addition of IL-6 in vitro. In both CD45- and CD45+ U-266 cells, STAT3 and MAPK(ERK1/2) can be activated in response to IL-6 equally between them, but src family kinases such as Lyn, Fyn can be activated only in CD45+ U-266 cells. Thus, the activation of the src family kinases associated with CD45 expression is a prerequisite for the proliferation of myeloma cells. In the bone marrow of myeloma patients, most myeloma cells do not express CD45, and CD45+ immature myeloma cells are only 1 approximately 2%. In order to clarify the difference of cellular context between CD45- and CD45+ myeloma cells, PCR-based cDNA subtraction was performed from CD45+ U-266 cells to CD45-U-266 cells. The series of this subtraction selected several genes. Furthermore, sensitivity to stress stimuli between CD45+ and CD45- U-266 cells was also compared. CD45-U-266 cells were markedly more resistant to stress conditions such as serum-free condition. Therefore, we can speculate that in the bone marrow of human myelomas IL-6 can induce proliferation of CD45+ immature cells, but the amount of IL-6 is too low to support CD45+ myeloma cells and loss of CD45 results in no direct response to IL-6 to proliferate but confers resistance to stress condition leading to the longer survival at the limited amount of IL-6.
人骨髓瘤细胞在形态和表型上具有异质性。骨髓瘤细胞可至少分为5个亚群：MPC-1-CD45+CD49e-、MPC-1-CD45-CD49e-未成熟骨髓瘤细胞、MPC-1+CD45-CD49e-、MPC-1+CD45+CD49e-中间型骨髓瘤细胞和MPC-1+CD45+CD49e+成熟骨髓瘤细胞。白细胞介素-6（IL-6）是人类骨髓瘤细胞的主要生长因子，但只有MPC-1-CD45+CD49e-未成熟骨髓瘤细胞能直接对IL-6作出反应而增殖。在U-266细胞系中，IL-6可导致CD45表达的诱导，且CD45+ U-266细胞能对IL-6作出反应而增殖。在原发性骨髓瘤细胞中，从骨髓样本中分选出来的MPC-1-CD45-CD49e-未成熟骨髓瘤细胞在体外添加IL-6后可转变为CD45+细胞。在CD45-和CD45+ U-266细胞中，STAT3和丝裂原活化蛋白激酶（ERK1/2）均可对IL-6作出同等程度的激活反应，但src家族激酶如Lyn、Fyn仅在CD45+ U-266细胞中被激活。因此，与CD45表达相关的src家族激酶的激活是骨髓瘤细胞增殖的先决条件。在骨髓瘤患者的骨髓中，大多数骨髓瘤细胞不表达CD45，而CD45+未成熟骨髓瘤细胞仅约占1%至2%。为了阐明CD45-和CD45+骨髓瘤细胞之间细胞环境的差异，从CD45+ U-266细胞到CD45-U-266细胞进行了基于PCR的cDNA消减。这一系列消减筛选出了几个基因。此外，还比较了CD45+和CD45- U-266细胞对应激刺激的敏感性。CD45-U-266细胞对诸如无血清条件等应激条件具有明显更强的抗性。因此，我们可以推测，在人类骨髓瘤的骨髓中，IL-6可诱导CD45+未成熟细胞增殖，但IL-6的量过低，无法支持CD45+骨髓瘤细胞，且CD45的缺失导致细胞无法直接对IL-6作出增殖反应，但赋予了对应激条件的抗性，从而在有限量的IL-6条件下实现更长的存活时间。
