Retinoic acid-induced AP-1 transcriptional activity regulates B16 mouse melanoma growth inhibition and differentiation.

Huang Y; Boskovic G; Niles RM

摘要

Retinoic acid (RA) inhibits growth and induces differentiation of B16 mouse melanoma cells. These effects are accompanied by a large increase in PKCalpha mRNA and protein levels and surprisingly an increase in activating protein-1 (AP-1) transcriptional activity. To further investigate the RA-induced AP-1 activity we established clones of B16 cells stably expressing an AP-1-luciferase reporter gene. Treatment of these clones with phorbol dibutyrate increased AP-1 activity which peaked at 2-4 h and returned to baseline level by 24 h. In contrast, RA treatment resulted in a slow increase in AP-1 activity that reached a maximum level at 48 h and was maintained for the duration of the treatment. We tested the importance of the RA-induced AP-1 activity by establishing clones which stably express a dominant negative fos gene (A-fos) and have greatly diminished AP-1 activity. Growth rates of untreated A-fos expressing cells were similar to wt B16 and clones not expressing A-fos. However, clones expressing thedominant-negative fos had a markedly decreased sensitivity to RA-induced inhibition of anchorage-dependent and -independent growth. Treatment of wt B16 cells for 48 h with RA increased melanin production by two to fourfold, but this effect was completely lost in the A-fos clones. The ability of RA to induce RARbeta and PKCalpha expression was retained in A-fos clones, suggesting that A-fos was not interfering with RAR transcription activation functions. We tested whether the RA-induced AP-1 activity might be mediated by the ERK1/2 MAPK pathway. Inhibition of ERK1/2 phosphorylation stimulated AP-1 activity, which was not additive to that induced by RA. This finding raises the possibility that this MAPK pathway may be a target of retinoid action. Our observations suggest that AP-1 transcriptional activity induced by RA likely plays an important role in the biological changes mediated by this retinoid in B16 melanoma cells.

机译：维甲酸(RA)抑制生长和诱导B16转椅小鼠黑色素瘤细胞的分化。这些影响是伴随着大量增加在PKCalpha信使rna和蛋白质含量令人惊讶的是激活蛋白1的增加(AP-1)转录活动。我们调查RA-induced AP-1活动建立B16转椅的克隆细胞稳定表达一个AP-1-luciferase记者基因。这些克隆与佛波醇dibutyrate增加AP-1活动达到2 - 4 h和返回通过24小时基线水平。相比之下,RA治疗导致AP-1缓慢增加活动,在48 h和达到最高水平维持治疗的持续时间。我们测试的重要性RA-induced AP-1活动通过建立稳定的克隆表达一个占主导地位的消极基因(A-fos)和安全系数大大减少AP-1活动。未经处理的A-fos表达细胞类似于wt B16转椅,克隆不表达A-fos。thedominant-negative安全系数有明显下降对RA-induced抑制的敏感性anchorage-dependent和独立成长。治疗与RA wt B16转椅细胞48 h黑色素生产增加了2 - 4倍,但这种效应是完全迷失在A-fos克隆。PKCalpha表达式是保留在A-fos克隆,这表明A-fos没有干扰RAR转录激活功能。是否RA-induced AP-1活动的ERK1/2 MAPK通路。ERK1/2磷酸化AP-1刺激活动,诱导的添加剂类风湿性关节炎。这个MAPK通路可能是一个类维生素a的目标行动。风湿性关节炎引起的转录活动的可能性生理变化起着重要的作用由这类维生素a在B16转椅黑色素瘤细胞。

Retinoic acid-induced AP-1 transcriptional activity regulates B16 mouse melanoma growth inhibition and differentiation.

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