Department of Cancer Biology and Genetics and Comprehensive Cancer Center, The Ohio State University, Columbus, 43210, OH, USA.
Department of Clinical and Molecular Medicine, Faculty of Medicine and Psychology, Sant'Andrea Hospital, University of Rome "Sapienza", Rome, 00189, Italy.
Signal Transduct Target Ther. 2024 Feb 12;9(1):31. doi: 10.1038/s41392-024-01740-4.
Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease, characterized by an intense desmoplastic reaction that compresses blood vessels and limits nutrient supplies. PDAC aggressiveness largely relies on its extraordinary capability to thrive and progress in a challenging tumor microenvironment. Dysregulation of the onco-suppressor miR-15a has been extensively documented in PDAC. Here, we identified the transcription factor Fos-related antigen-2 (Fra-2) as a miR-15a target mediating the adaptive mechanism of PDAC to nutrient deprivation. We report that the IGF1 signaling pathway was enhanced in nutrient deprived PDAC cells and that Fra-2 and IGF1R were significantly overexpressed in miR-15a downmodulated PDAC patients. Mechanistically, we discovered that miR-15a repressed IGF1R expression via Fra-2 targeting. In miR-15a-low context, IGF1R hyperactivated mTOR, modulated the autophagic flux and sustained PDAC growth in nutrient deprivation. In a genetic mouse model, Mir15a PDAC showed Fra-2 and Igf1r upregulation and mTOR activation in response to diet restriction. Consistently, nutrient restriction improved the efficacy of IGF1R inhibition in a Fra-2 dependent manner. Overall, our results point to a crucial role of Fra-2 in the cellular stress response due to nutrient restriction typical of pancreatic cancer and support IGF1R as a promising and vulnerable target in miR-15a downmodulated PDAC.
胰腺导管腺癌 (PDAC) 是一种致命性疾病,其特征为强烈的促结缔组织反应,这种反应会压迫血管并限制营养供应。PDAC 的侵袭性在很大程度上依赖于其在极具挑战性的肿瘤微环境中茁壮成长和发展的非凡能力。miR-15a 的致癌抑制因子失调在 PDAC 中已得到广泛证实。在这里,我们鉴定出转录因子 Fos 相关抗原-2 (Fra-2) 是 miR-15a 的靶标,介导 PDAC 对营养缺乏的适应性机制。我们报告说,在营养剥夺的 PDAC 细胞中 IGF1 信号通路增强,并且 Fra-2 和 IGF1R 在 miR-15a 下调的 PDAC 患者中显著过表达。从机制上讲,我们发现 miR-15a 通过靶向 Fra-2 抑制 IGF1R 的表达。在 miR-15a 低表达的情况下,IGF1R 过度激活 mTOR,调节自噬通量,并在营养缺乏时维持 PDAC 的生长。在遗传小鼠模型中,Mir15a PDAC 表现出 Fra-2 和 Igf1r 的上调以及 mTOR 的激活,以响应饮食限制。一致地,营养限制以 Fra-2 依赖的方式提高了 IGF1R 抑制的疗效。总的来说,我们的结果表明 Fra-2 在由于营养限制而导致的细胞应激反应中起着关键作用,这是典型的胰腺癌特征,并支持 IGF1R 作为 miR-15a 下调的 PDAC 中一个有前途且脆弱的靶点。
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