Fan K, Barendsen N, Sensenbrenner L, Chen B D
Department of Internal Medicine, Wayne State University School of Medicine, Detroit, Michigan 48201.
J Cell Physiol. 1993 Mar;154(3):535-42. doi: 10.1002/jcp.1041540312.
J774A.1 immortalized macrophage tumor cells display several phenotypes and functional capacities similar to that of murine peritoneal exudate macrophages (PEM). Both populations display comparable number of M-CSF receptors. Yet the number of GM-CSF receptors on J774A.1 cells is only one-fourth that of PEM (1,500 vs. 6,000 per cell). Unlike J774A.1 cells, which constitutively express c-myc transcripts, normal PEM required rMuGM-CSF for the induction of c-myc expression. Nevertheless, the growth of J774A.1 cells can be further enhanced in the presence of exogenous rMuGM-CSF, rHuM-CSF, and rMuIL-3. Treatment with either rMuIL-3 (20 ng/ml) and rHuTGF-beta 1 (1.0 ng/ml) for 24 hr at 37 degrees C, markedly enhanced the expression of GM-CSF receptors on normal PEM but not leukemic J774A.1 cells. J774A.1 cells also did not respond by autologous upregulation of GM-CSF receptors as seen in PEM following treatment with rMuGM-CSF. Treatment with either pertussis toxin (20-100 ng/ml) or H-8 (50 microM) for 24 hr led to an enhanced expression of GM-CSF receptors on J774A.1 cells in a time- and dose-dependent manner but did not result in enhanced receptor expression on normal PEM. These findings suggest that the expression of GM-CSF receptors may be regulated by mechanisms involving Gi-proteins and their downstream elements, which in turn are linked to regulatory pathways of other cytokine receptors. In J774A.1 cells, such regulatory interaction may not exist.
J774A.1永生化巨噬细胞肿瘤细胞表现出几种与小鼠腹腔渗出巨噬细胞（PEM）相似的表型和功能能力。这两种细胞群体显示出相当数量的M-CSF受体。然而，J774A.1细胞上GM-CSF受体的数量仅为PEM的四分之一（每细胞1500个与6000个）。与组成性表达c-myc转录本的J774A.1细胞不同，正常PEM需要rMuGM-CSF来诱导c-myc表达。尽管如此，在外源rMuGM-CSF、rHuM-CSF和rMuIL-3存在的情况下，J774A.1细胞的生长可以进一步增强。用rMuIL-3（20 ng/ml）和rHuTGF-β1（1.0 ng/ml）在37℃处理24小时，可显著增强正常PEM上GM-CSF受体的表达，但对白血病变异的J774A.1细胞没有作用。J774A.1细胞也不会像用rMuGM-CSF处理后的PEM那样通过自身上调GM-CSF受体来做出反应。用百日咳毒素（20 - 100 ng/ml）或H-8（50 μM）处理24小时，可使J774A.1细胞上GM-CSF受体的表达呈时间和剂量依赖性增强，但对正常PEM的受体表达没有增强作用。这些发现表明，GM-CSF受体的表达可能受涉及Gi蛋白及其下游元件的机制调控，而这些机制又与其他细胞因子受体的调控途径相关。在J774A.1细胞中，可能不存在这种调控相互作用。
