Streicher Katie L, Willmarth Nicole E, Garcia Jose, Boerner Julie L, Dewey T Gregory, Ethier Stephen P
Barbara Ann Karmanos Cancer Institute, Detroit, MI 48201, USA.
Mol Cancer Res. 2007 Aug;5(8):847-61. doi: 10.1158/1541-7786.MCR-06-0427. Epub 2007 Aug 1.
We have recently shown that an amphiregulin-mediated autocrine loop is responsible for growth factor-independent proliferation, motility, and invasive capacity of some aggressive breast cancer cells, such as the SUM149 breast cancer cell line. In the present study, we investigated the mechanisms by which amphiregulin activation of the epidermal growth factor receptor (EGFR) regulates these altered phenotypes. Bioinformatic analysis of gene expression networks regulated by amphiregulin implicated interleukin-1alpha (IL-1alpha) and IL-1beta as key mediators of amphiregulin's biological effects. The bioinformatic data were validated in experiments which showed that amphiregulin, but not epidermal growth factor, results in transcriptional up-regulation of IL-1alpha and IL-1beta. Both IL-1alpha and IL-1beta are synthesized and secreted by SUM149 breast cancer cells, as well as MCF10A cells engineered to express amphiregulin or MCF10A cells cultured in the presence of amphiregulin. Furthermore, EGFR, activated by amphiregulin but not epidermal growth factor, results in the prompt activation of the transcription factor nuclear factor-kappaB (NF-kappaB), which is required for transcriptional activation of IL-1. Once synthesized and secreted from the cells, IL-1 further activates NF-kappaB, and inhibition of IL-1 with the IL-1 receptor antagonist results in loss of NF-kappaB DNA binding activity and inhibition of cell proliferation. However, SUM149 cells can proliferate in the presence of IL-1 when EGFR activity is inhibited. Thus, in aggressive breast cancer cells, such as the SUM149 cells, or in normal human mammary epithelial cells growing in the presence of amphiregulin, EGFR signaling is integrated with NF-kappaB activation and IL-1 synthesis, which cooperate to regulate the growth and invasive capacity of the cells.
我们最近发现，双调蛋白介导的自分泌环可导致某些侵袭性乳腺癌细胞（如SUM149乳腺癌细胞系）在不依赖生长因子的情况下进行增殖、迁移及具备侵袭能力。在本研究中，我们探究了双调蛋白激活表皮生长因子受体（EGFR）调节这些改变的表型的机制。对受双调蛋白调节的基因表达网络进行生物信息学分析，结果表明白细胞介素-1α（IL-1α）和白细胞介素-1β（IL-1β）是双调蛋白生物学效应的关键介质。该生物信息学数据在实验中得到验证，实验表明双调蛋白而非表皮生长因子可导致IL-1α和IL-1β的转录上调。IL-1α和IL-1β均由SUM149乳腺癌细胞以及经改造表达双调蛋白的MCF10A细胞或在双调蛋白存在下培养的MCF10A细胞合成并分泌。此外，由双调蛋白而非表皮生长因子激活的EGFR可导致转录因子核因子-κB（NF-κB）迅速激活，而NF-κB是IL-1转录激活所必需的。一旦从细胞中合成并分泌出来，IL-1会进一步激活NF-κB，用IL-1受体拮抗剂抑制IL-1会导致NF-κB DNA结合活性丧失及细胞增殖受到抑制。然而，当EGFR活性受到抑制时，SUM149细胞在IL-1存在的情况下仍可增殖。因此，在侵袭性乳腺癌细胞（如SUM149细胞）中，或在存在双调蛋白的情况下生长的正常人类乳腺上皮细胞中，EGFR信号传导与NF-κB激活及IL-1合成相互整合，共同调节细胞的生长和侵袭能力。
