Herlyn M, Kath R, Williams N, Valyi-Nagy I, Rodeck U
Wistar Institute of Anatomy and Biology, Philadelphia, Pennslyvania 19104.
Adv Cancer Res. 1990;54:213-34. doi: 10.1016/s0065-230x(08)60812-x.
Normal human cells, cells from nonmalignant proliferative lesions, and primary and metastatic tumor cells can be maintained in vitro and analyzed for requirements for growth in chemically defined media. The human melanocytic cell system with normal melanocytes, precursor nevus cells, and primary and metastatic melanoma cells has been extensively studied for the phenotypic properties of the cells, including their requirements for exogenous growth factors and other mitogens. In high calcium-containing W489 medium, normal melanocytes require four supplements: IGF-I (or insulin); bFGF, TPA, and alpha-MSH. Nevus cells are largely independent of bFGF. Depletion of TPA from medium is not as detrimental to nevus cells as it is to melanocytes, but the phorbol ester is still essential for maintenance of the typical nevic phenotype. Primary melanoma cells require at least one growth factor, IGF-I (or insulin), for continuous proliferation. On the other hand, metastatic cells of melanoma as well as of carcinomas of colon and rectum, bladder, ovary, and cervix are able to proliferate after a short adaptation period in medium depleted of any growth factors and other proteins. Doubling times of metastatic tumor cells in protein-free medium are only 30-60% longer than in FCS-containing medium. The growth autonomy of human tumor cells is apparently due to the endogenous production of growth factors. Likely candidates for autocrine growth stimulation of human tumor cells are TGF-alpha, TGF-beta, and PDGF. Melanoma and colorectal carcinoma cells express functional EGF/TGF-alpha receptors, and produce TGF-alpha, indicating that this growth factor is produced for autocrine stimulation. In addition to the use of anti-growth factor antibodies, other strategies for the inhibition of autocrine growth stimulation include mAbs to growth factor receptors, soluble receptors, receptor-mimicking antiidiotype antibodies, and active immunization against growth factors. Whether any of these therapeutic approaches is clinically feasible will need to be determined in extensive preclinical investigations.
正常人类细胞、来自非恶性增殖性病变的细胞以及原发性和转移性肿瘤细胞均可在体外培养，并在化学成分明确的培养基中分析其生长所需条件。具有正常黑素细胞、痣细胞前体以及原发性和转移性黑色素瘤细胞的人类黑素细胞系统已针对细胞的表型特性进行了广泛研究，包括它们对外源生长因子和其他促有丝分裂原的需求。在高钙含量的W489培养基中，正常黑素细胞需要四种补充剂：IGF-I（或胰岛素）、bFGF、TPA和α-MSH。痣细胞在很大程度上不依赖bFGF。从培养基中去除TPA对痣细胞的损害不像对黑素细胞那么大，但佛波酯对于维持典型的痣细胞表型仍然至关重要。原发性黑色素瘤细胞需要至少一种生长因子IGF-I（或胰岛素）才能持续增殖。另一方面，黑色素瘤以及结肠直肠癌、膀胱癌、卵巢癌和宫颈癌的转移细胞在适应不含任何生长因子和其他蛋白质的培养基的短时间后能够增殖。无蛋白培养基中转移肿瘤细胞的倍增时间仅比含胎牛血清的培养基长30%-60%。人类肿瘤细胞的生长自主性显然归因于生长因子的内源性产生。人类肿瘤细胞自分泌生长刺激的可能候选因子是TGF-α、TGF-β和PDGF。黑色素瘤和结肠癌细胞表达功能性EGF/TGF-α受体，并产生TGF-α，表明这种生长因子是为自分泌刺激而产生的。除了使用抗生长因子抗体之外，抑制自分泌生长刺激的其他策略包括针对生长因子受体的单克隆抗体、可溶性受体、模拟受体的抗独特型抗体以及针对生长因子的主动免疫。这些治疗方法中是否有任何一种在临床上可行，需要在广泛的临床前研究中确定。
