Geradts J, Chen J Y, Russell E K, Yankaskas J R, Nieves L, Minna J D
National Cancer Institute-Navy Medical Oncology Branch, National Naval Medical Center, Bethesda, Maryland 20889.
Cell Growth Differ. 1993 Oct;4(10):799-809.
Retinoic acid (RA) and nuclear retinoic acid receptors (RARs) have been implicated in a variety of human malignancies including lung cancer, and RA has been proposed as a chemopreventive agent for bronchogenic carcinoma. Normal human tracheobronchial epithelial cells show dramatic induction of RAR-beta mRNA and significant growth inhibition after RA treatment. In contrast, 17 of 22 small cell lung cancer (SCLC) and 9 of 15 non-SCLC lines treated with 1 microM RA showed no significant growth inhibition. Of interest, 5 SCLC lines with high levels of myc gene family expression related to c-, N-, or L-myc gene amplification exhibited growth inhibition (28-87%), whereas 2 non-SCLC lines actually showed growth stimulation after treatment with 1 microM RA. The lines varied greatly in their constitutive expression of RAR-beta mRNA, and 15 of 20 SCLC and 8 of 15 non-SCLC lines failed to show RAR-beta mRNA induction after RA treatment. Six cell lines showed possible alterations in the coding region of RAR-beta by complementary DNA (cDNA)/polymerase chain reaction (PCR) analysis using primers common to the RAR-beta1,2,3 isoforms, since other regions would undergo cDNA/PCR amplification whereas the DNA binding domain would not. Nonetheless, no abnormal band shift patterns in cDNA amplified by PCR were found by single strand conformation polymorphism analysis covering all 1344 base pairs of the RAR-beta open reading frame. Finally, no abnormalities in RAR-alpha gene structure or expression were identified by Southern and Northern blot analysis, including lines with cytogenetic abnormalities of 17q21. We conclude that abnormalities of the RAR-beta system are common in human lung cancer cell lines.
维甲酸（RA）和核维甲酸受体（RARs）与包括肺癌在内的多种人类恶性肿瘤有关，并且RA已被提议作为支气管癌的化学预防剂。正常人类气管支气管上皮细胞在RA处理后显示出RAR-β mRNA的显著诱导和明显的生长抑制。相比之下，用1微摩尔RA处理的22个小细胞肺癌（SCLC）细胞系中的17个和15个非SCLC细胞系中的9个未显示出明显的生长抑制。有趣的是，5个与c-、N-或L-myc基因扩增相关的myc基因家族高表达的SCLC细胞系表现出生长抑制（28%-87%），而2个非SCLC细胞系在用1微摩尔RA处理后实际上显示出生长刺激。这些细胞系在RAR-β mRNA的组成性表达上差异很大，20个SCLC细胞系中的15个和15个非SCLC细胞系中的8个在RA处理后未显示RAR-β mRNA诱导。通过使用RAR-β1、2、3亚型共有的引物进行互补DNA（cDNA）/聚合酶链反应（PCR）分析，6个细胞系显示RAR-β编码区可能存在改变，因为其他区域会进行cDNA/PCR扩增，而DNA结合结构域不会。尽管如此，通过覆盖RAR-β开放阅读框所有1344个碱基对的单链构象多态性分析，未发现PCR扩增的cDNA中有异常的条带迁移模式。最后，通过Southern和Northern印迹分析未发现RAR-α基因结构或表达异常，包括具有17q21细胞遗传学异常的细胞系。我们得出结论，RAR-β系统异常在人类肺癌细胞系中很常见。
