Vasudevan Harish N, Arang Nadia, Sacconi Nunez Maria, Kennedy Patrick, Payne Emily, Mohabeer Sarah, Chien Julian, Wright Aaron, Sale Matthew J, Krogan Nevan J, Forget Antoine, McCormick Frank
Department of Radiation Oncology, University of California San Francisco, San Francisco, CA 94143.
Department of Neurological Surgery, University of California San Francisco, San Francisco, CA 94143.
Proc Natl Acad Sci U S A. 2025 Jul 8;122(27):e2506823122. doi: 10.1073/pnas.2506823122. Epub 2025 Jun 30.
The tumor suppressor gene is recurrently mutated in human cancers and is associated with the neurofibromatosis type 1 (NF-1) cancer predisposition syndrome. encodes neurofibromin, a Ras guanosine triphosphate (GTPase) activating protein that negatively regulates Ras signaling. mutation accordingly leads to Ras misactivation and downstream activation of RAF/MEK/ERK signaling, leading to the approval of the MEK inhibitor selumetinib for NF-1 associated peripheral nervous system (PNS) tumors. However, how loss modifies response to selumetinib and the utility of targeting additional upstream inputs or downstream outputs of Ras these tumors remain unclear. Here, we perform RNA-sequencing, phosphoproteomic, pharmacologic, and proximal proteomic analysis across a panel of CRISPR interference immortalized peripheral nerve (iPN) cells to systematically dissect the function of neurofibromin loss. Small guide (sg) repression is sufficient to increase Ras GTP levels and alter gene expression to promote cell proliferation and dedifferentiation, with sg iPNs showing decreased sensitivity to selumetinib due to altered feedback regulation to Ras/RAF/MEK/ERK. Upstream small guide (sg) repression leads to the inverse gene expression signature, decreasing cell proliferation and promoting differentiation, and sg iPNs are more sensitive to selumetinib. However, upstream sonof sevenless 1 inhibition shows limited efficacy in iPNs due to compensation by SOS2. Finally, proximal proteomics reveals Kirsten rat sarcoma virus (KRAS), but not Harvey rat sarcoma virus (HRAS) or neuroblastoma Ras viral oncogene homolog (NRAS), associates with neurofibromin in iPN cells, and pan-KRAS inhibition is sufficient to block ERK activation and CDK1/2 activation in mutant cells, suggesting blocking KRAS may be a therapeutic approach for mutant PNS tumors.
肿瘤抑制基因在人类癌症中经常发生突变，与1型神经纤维瘤病（NF-1）癌症易感综合征相关。它编码神经纤维瘤蛋白，一种Ras鸟苷三磷酸（GTP酶）激活蛋白，对Ras信号传导起负调节作用。因此，该基因的突变会导致Ras的错误激活以及RAF/MEK/ERK信号传导的下游激活，从而促使MEK抑制剂司美替尼被批准用于治疗与NF-1相关的外周神经系统（PNS）肿瘤。然而，该基因缺失如何改变对司美替尼的反应以及针对这些肿瘤中Ras的其他上游输入或下游输出进行靶向治疗的效用仍不清楚。在这里，我们对一组CRISPR干扰永生化外周神经（iPN）细胞进行了RNA测序、磷酸化蛋白质组学、药理学和近端蛋白质组学分析，以系统地剖析神经纤维瘤蛋白缺失的功能。小干扰RNA（sgRNA）抑制足以增加Ras GTP水平并改变基因表达，从而促进细胞增殖和去分化，由于对Ras/RAF/MEK/ERK的反馈调节改变，sgRNA干扰的iPN细胞对司美替尼的敏感性降低。上游小干扰RNA（sgRNA）抑制导致相反的基因表达特征，减少细胞增殖并促进分化，并且sgRNA干扰的iPN细胞对司美替尼更敏感。然而，由于SOS2的补偿作用，上游七号less 1抑制在iPN细胞中的疗效有限。最后，近端蛋白质组学揭示了在iPN细胞中， Kirsten大鼠肉瘤病毒（KRAS）而非哈维大鼠肉瘤病毒（HRAS）或神经母细胞瘤Ras病毒癌基因同源物（NRAS）与神经纤维瘤蛋白相关，并且泛KRAS抑制足以阻断突变细胞中的ERK激活和CDK1/2激活，这表明阻断KRAS可能是治疗突变型PNS肿瘤的一种治疗方法。
