Wu Y, Barnabas N, Russo I H, Yang X, Russo J
Breast Cancer Research Laboratory, Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
Carcinogenesis. 1997 May;18(5):1069-74. doi: 10.1093/carcin/18.5.1069.
Microsatellite instability (MSI) and loss of heterozygosity (LOH) in chromosomes 9 and 16 have been reported in human breast cancers. In order to determine whether changes in these chromosomes play a role in the initiation and progression of this disease, we performed microsatellite polymorphism analyses in human breast epithelial cells (HBEC) transformed by chemical carcinogens, an in vitro system that recapitulates various stages of neoplastic transformation. In this experimental system we studied the mortal HBEC MCF-10M, immortal MCF-10F cells, derived from MCF-10M cells, and clones derived from MCF-10F cells treated with benzo[a]pyrene (B[a]P) (BP1 and BP1E) and 7,12-dimethylbenz[a]anthracene (DMBA) (D3 and D3-1). The four clones of transformed cells were injected into severe combined immunodeficient (SCID) mice. Only BP1-E cells induced the formation of tumors, designated BP1E-Tp cells. These cells originated six additional tumors, designated BP1E-Tf no. 1 through Tf no. 6. Microsatellite analyses were carried out using five markers for chromosome 9 and 20 for chromosome 16. There was no evidence of MSI or LOH in clones BP1 and BP1E when compared with the MCF-10M and MCF-10F cells, whereas BP1E-Tp cells and Bp1E-Tf no. 1-Tf no. 6 tumors exhibited MSI at loci p23 and p21, and LOH at p21-22 of chromosome 9. They also exhibited MSI and LOH at multiple loci of both the short and long arms of chromosome 16, i.e. p13.13, p13.3, p12, q12.1, q12.2, q23 and q24, to which putative tumor suppressor genes have been localized. Clones D3 and D3-1 exhibited no genomic changes in chromosome 9, but did show MSI at locus q12.1 of chromosome 16 using marker D16S285. Although the cells treated with DMBA expressed early phenotypes of neoplastic transformation, they were not tumorigenic, and also manifested fewer changes than the tumorigenic BP1E-Tp cells and the tumors BP1E-Tf. The changes in chromosomes 9 and 16 observed in these latter ones indicated an association with the expression of tumorigenesis, which represents a late event in the progression of the neoplastic transformation of HBEC. Of interest was the observation that HBEC transformed by chemical carcinogens in vitro express genomic changes similar to those found in spontaneous breast carcinomas.
人类乳腺癌中已报道有微卫星不稳定性（MSI）以及9号和16号染色体杂合性缺失（LOH）。为了确定这些染色体变化是否在该疾病的起始和进展中起作用，我们对经化学致癌物转化的人乳腺上皮细胞（HBEC）进行了微卫星多态性分析，这是一个可概括肿瘤转化各个阶段的体外系统。在这个实验系统中，我们研究了 mortal HBEC MCF - 10M、源自MCF - 10M细胞的永生化MCF - 10F细胞，以及用苯并[a]芘（B[a]P）（BP1和BP1E）和7,12 - 二甲基苯并[a]蒽（DMBA）（D3和D3 - 1）处理过的源自MCF - 10F细胞的克隆。将四个转化细胞克隆注射到严重联合免疫缺陷（SCID）小鼠体内。只有BP1 - E细胞诱导形成肿瘤，命名为BP1E - Tp细胞。这些细胞又产生了另外六个肿瘤，命名为BP1E - Tf编号1至Tf编号6。使用9号染色体的五个标记和16号染色体的二十个标记进行微卫星分析。与MCF - 10M和MCF - 10F细胞相比，克隆BP1和BP1E中没有MSI或LOH的证据，而BP1E - Tp细胞以及BP1E - Tf编号1至Tf编号6的肿瘤在9号染色体的p23和p21位点表现出MSI，在9号染色体的p21 - 22位点表现出LOH。它们在16号染色体短臂和长臂的多个位点即p13.13、p13.3、p12、q12.1、q12.2、q23和q24也表现出MSI和LOH，这些位点已定位有假定的肿瘤抑制基因。克隆D3和D3 - 1在9号染色体上没有基因组变化，但使用标记D16S285在16号染色体的q12.1位点显示出MSI。尽管用DMBA处理的细胞表达了肿瘤转化的早期表型，但它们没有致瘤性，并且与致瘤性BP1E - Tp细胞和BP1E - Tf肿瘤相比变化也较少。在后者中观察到的9号和16号染色体变化表明与肿瘤发生的表达有关，这代表了HBEC肿瘤转化进展中的一个晚期事件。有趣的是观察到经体外化学致癌物转化的HBEC表达的基因组变化与在自发性乳腺癌中发现的相似。
