King I C, Sartorelli A C
Biochem Biophys Res Commun. 1986 Nov 14;140(3):837-43. doi: 10.1016/0006-291x(86)90710-2.
The replication of human epidermoid carcinoma A431 cells is inhibited by epidermal growth factor (EGF), with 5 ng/ml of EGF causing 50% inhibition of cellular proliferation. EGF resistant clones isolated from A431 cells were able to replicate in the presence of 100 ng/ml of EGF. That this insensitivity to EGF was probably due to a decrease in the expression of EGF receptors (EGFR) on the cell surface was shown using an EGFR cDNA probe to detect a 68% to 85% decrease relative to parental cells in the amount of EGFR mRNA in the EGF resistant clones. A corresponding decrease in surface EGFR levels was also detected in EGF resistant clones as measured by 125I-EGF binding. Eighteen percent of A431 cells cultured in serum-free medium for 6 days entered a pathway of terminal differentiation, as expressed by the formation of envelope-competent cells, whereas EGF resistant clones exhibited a considerably greater capacity to mature, even when cultured in serum-containing medium. The findings suggest that the concentration of EGFRs is important for the capacity of epidermal cells to undergo terminal differentiation in vitro.
表皮生长因子（EGF）可抑制人表皮样癌A431细胞的增殖，5 ng/ml的EGF可导致50%的细胞增殖抑制。从A431细胞中分离出的EGF抗性克隆能够在100 ng/ml的EGF存在下进行复制。使用EGFR cDNA探针检测发现，EGF抗性克隆中EGFR mRNA的量相对于亲代细胞减少了68%至85%，这表明对EGF的不敏感性可能是由于细胞表面EGF受体（EGFR）表达的降低所致。通过125I-EGF结合测定，在EGF抗性克隆中也检测到表面EGFR水平相应降低。在无血清培养基中培养6天的A431细胞中有18%进入终末分化途径，表现为形成有包膜能力的细胞，而EGF抗性克隆即使在含血清培养基中培养也表现出明显更强的成熟能力。这些发现表明，EGFR的浓度对于表皮细胞在体外进行终末分化的能力很重要。
