ROLE OF EGF-RELATED PEPTIDES IN THE PATHOGENESIS OF BREAST AND COLON CANCER

转化生长因子α（TGF α）、双调蛋白（AR）和cripto-1 （CR-1）是在结构上并且在某些情况下在功能上与CR 1结合的蛋白质。 与表皮生长因子（EGF）相关，因为TGF α和AR可以结合 EGF受体（c-er B B）。TGF-α已经被间接地 与许多不同的人类自分泌生长有关 癌细胞如乳腺癌和结肠癌。然而，该条例 这种生长因子的表达和干扰其生物学特性 活动尚未得到彻底审查。此外，相对水平 AR和CR-1在这些恶性肿瘤中的表达和生物学功能 是未知的。目前的研究表明，MCF-10A人 乳腺上皮细胞对外源EGF有丝分裂反应， TGF α或AR和这些细胞的转化与点突变 c-Ha-ras原癌基因但不含c-er B B-2原癌基因导致 内源性TGF α表达增加。此外，委员会认为， 人TGF α cDNA在这些细胞中的过表达导致它们的表达， 离体转化添加抗EGF受体阻断抗体 或者抗TGF α中和抗体可以部分或完全 抑制Ha-ras或TGF α转化的乳腺细胞的生长 这表明在这些细胞中有一个外部自分泌环起作用。在 相反，在Ha-ras和c-er B B-2中AR表达增加 转化的MCF-10A细胞，并且这些转化体的生长可以是 被AR反义硫代磷酸寡核苷酸抑制，表明 AR是一种自分泌媒介， Ha-ras和erB B-2都利用的途径。雌激素可以 增加雌激素受体TGF α mRNA和蛋白的表达， 响应性人乳腺癌细胞系，如MCF-7或ZR-75-1细胞。 使用质粒在MCF-7或ZR-75-1细胞中的瞬时转染测定 含有TGF α启动子，其连接到氯霉素 乙酰转移酶（CAT）或荧光素酶基因已经证明， 生理浓度的雌激素可以诱导5- 50倍的 这些报告基因的活性增加，表明 TGF α启动子含有顺式作用雌激素应答元件 （ERE）。MCF-7或ZR-75-1细胞用重组嗜中性粒细胞转染， TGF α反义mRNA表达载体。反义核酸的表达 mRNA导致雌激素诱导的TGF α蛋白产生减少 并对雌激素诱导的 在这些细胞中增殖。AR的特异性mRNA和免疫反应性 和CR-1已在约50%至80%的原发性和 转移性人类结直肠肿瘤，而只有5%的正常相邻 结肠或肝脏组织表达这些基因。同样，免疫反应性AR和 在约70%的原发性人类乳腺肿瘤中检测到CR-1， 超过邻近正常乳腺组织水平的水平 上皮

Transforming growth factor a (TGFalpha), amphiregulin (AR) and cripto-1 (CR-1) are proteins that are structurally and in some cases functionally related to epidermal growth factor (EGF) in that TGFalpha and AR can bind to the EGF receptor (c-erb B). TGFalpha has been circumstantially implicated in the autocrine growth of a number of different human carcinoma cells such as breast and colon tumors. However, the regulation of expression of this growth factor and interference with its biological activity have not been thoroughly examined. Moreover, the relative levels of expression and biological function of AR and CR-1 in these malignancies are unknown. The present studies have demonstrated that MCF-10A human mammary epithelial cells are mitogenically responsive to exogenous EGF, TGFalpha or AR and that transformation of these cells with a point-mutated c-Ha-ras protooncogene but not with a c-erb B-2 protooncogene results in an increase in the expression of endogenous TGFalpha. Furthermore, overexpression of a human TGFalpha cDNA in these cells leads to their in vitro transformation. Addition of an anti-EGF receptor blocking antibody or an anti-TGFalpha neutralizing antibody can partially or completely inhibit the growth of the Ha-ras or TGFalpha transformed mammary cells suggesting that an external autocrine loop is operative in these cells. In contrast, AR expression is increased in both Ha-ras and c-erb B-2 transformed MCF-10A cells and the growth of these transformants can be inhibited by AR antisense phosphorothioate oligonucleotides demonstrating that AR is functioning as an autocrine intermediary in the transformation pathway that is utilized by both Ha-ras and erb B-2. Estrogens can increase the expression of TGFalpha mRNA and protein in estrogen- responsive human breast cancer cell lines such as MCF-7 or ZR-75-1 cells. Transient transfection assays in MCF-7 or ZR-75-1 cells using a plasmid containing the TGFalpha promoter ligated to either the chloramphenicol acetyltransferase (CAT) or luciferase genes have demonstrated that physiological concentrations of estrogens can induce a 5-to 50-fold increase in the activity of these reporter genes, suggesting that the TGFalpha promoter contains a cis-acting estrogen-responsive element(s) (ERE). MCF-7 or ZR-75-1 cells were infected with a recombinant amphotropic TGFalpha antisense mRNA expression vector. Expression of this antisense mRNA lead to a reduction in estrogen-induced TGFalpha protein production and to an equivalent degree of inhibition of estrogen-induced proliferation in these cells. Specific mRNA and immunoreactivity for AR and CR-1 have been detected in approximately 50% to 80% of primary and metastatic human colorectal tumors, whereas only 5% of normal adjacent colon or liver tissue express these genes. Likewise, immunoreactive AR and CR-1 was detected in approximately 70% of primary human breast tumors at a level that exceeded the level found in adjacent normal mammary epithelium.