Seefried Felix, Haller Lucia, Fukuda Shinji, Thongmao Aranya, Schneider Nadja, Utikal Jochen, Higashiyama Shigeki, Bosserhoff Anja Katrin, Kuphal Silke
Institute of Biochemistry, Friedrich Alexander University Erlangen-Nürnberg, Erlangen, Germany.
Department of Biochemistry, School of Dentistry, Aichi Gakuin University, Nagoya, Japan.
Int J Cancer. 2022 Dec 15;151(12):2244-2264. doi: 10.1002/ijc.34254. Epub 2022 Sep 5.
AMPHIREGULIN (AREG) is a multifaceted molecule, which acts not only as an extracellular ligand for EGF receptor (EGFR), but also as an intracellular signaling molecule. It remains elusive, however, whether AREG has a tumor suppressive or oncogenic role in melanoma. Here, we found that several melanoma cell lines express AREG, but the expression does not correlate with that of EGFR. Recombinant AREG and the neutralizing antibody experiments showed that intracellular AREG plays an important role in melanoma, implying a divergent function of AREG in addition to the role as a ligand for EGFR. Further investigation of this mechanism revealed that particularly nuclear-localized AREG regulates IGF-1R, P21 (Cip1/Waf1), TP53 and JARID1B protein accumulation in the nucleus. Furthermore, manipulation of nuclear AREG levels has influence on heterochromatin condensation (HP1beta, SETDB1) and trimethylation of histones H3K9 and H3K4. As these molecules correspond to previously identified markers for slow-cycling drug resistant cells, we speculate that nuclear AREG predisposes cells to resistance to therapy. According to the hypothesis, we detected the accumulation of AREG in the nucleus of SK-Mel-28-VR, which was cultured under Vemurafenib (VR) selection pressure, and this correlates with JARID1B expression. Here, knockdown of AREG makes the previously resistant cells more sensitive to VR treatment, resulting in inhibited proliferation. Taken together, we suggest that nuclear AREG affects a slow-cycling phenotype and increases resistance to VR, raising a possibility that AREG might be a potential therapeutic target for resistance in melanoma.
双调蛋白（AREG）是一种多面分子，它不仅作为表皮生长因子受体（EGFR）的细胞外配体起作用，还作为细胞内信号分子。然而，AREG在黑色素瘤中是具有肿瘤抑制作用还是致癌作用仍不清楚。在这里，我们发现几种黑色素瘤细胞系表达AREG，但这种表达与EGFR的表达不相关。重组AREG和中和抗体实验表明，细胞内AREG在黑色素瘤中起重要作用，这意味着除了作为EGFR配体的作用外，AREG还具有不同的功能。对这一机制的进一步研究表明，特别是核定位的AREG调节细胞核中胰岛素样生长因子1受体（IGF-1R）、P21（Cip1/Waf1）、TP53和JARID1B蛋白的积累。此外，对核AREG水平的调控会影响异染色质凝聚（HP1β、SETDB1）以及组蛋白H3K9和H3K4的三甲基化。由于这些分子与先前确定的慢周期耐药细胞标志物相对应，我们推测核AREG使细胞易于产生治疗抗性。根据这一假设，我们检测到在维莫非尼（VR）选择压力下培养的SK-Mel-28-VR细胞核中AREG的积累，且这与JARID1B的表达相关。在这里，敲低AREG使先前耐药的细胞对VR治疗更敏感，从而导致增殖受到抑制。综上所述，我们认为核AREG影响慢周期表型并增加对VR的抗性，这增加了AREG可能成为黑色素瘤抗性潜在治疗靶点的可能性。
