Dual targeting of PI3K and NOS pathways in Metaplastic BreastCancer (MBC)

摘要 化生性乳腺癌(MpBC)是一种罕见的亚型，占所有乳腺癌的5%。MpBC是一个重要的 健康挑战，因为它表现出所有乳腺癌亚型中预后最差的，比非MpBC更差 三阴性乳腺癌(TNBC)，转移性患者的中位生存期不超过8个月 疾病。由于缺乏可用药靶点，转移性多发性骨髓细胞癌的主要治疗选择仍然是全身的。 化疗，尽管已知对大多数细胞毒药物具有耐药性。MpBC中一种常见的分子改变是 肌醇磷脂3-激酶和蛋白激酶B(PI3K/AKT)途径的过度激活。此外，我们 发表的MpBC也显示了核糖体蛋白L39(RPL39)的功能获得致癌突变， 它负责治疗耐药、干细胞自我更新和肺转移。机械论 RPL39的功能是通过诱导型一氧化氮合酶(INOS)介导的一氧化氮产生来实现的。 在最近发表的一项针对一氧化氮合酶(NOS)途径的临床试验中，使用了PAN-NOS抑制剂 L-精氨酸乙酯(L-精氨酸甲酯)对化疗耐药的TNBC患者有较高的疗效。 此外，进行的体内研究显示，肿瘤生长显著减少，与 Alpelisib/L-NMMA联合用药后细胞凋亡率显著增加。因此，我们假设 一氧化氮合酶和PI3K信号通路可能协同发挥其致癌效应 促进侵袭性肿瘤生长。为了检验这一假设，《特定目标1》试图证明 同时抑制一氧化氮合酶和PI3K通路联合化疗对多发性骨髓细胞癌前病变的疗效 原发肿瘤生长和转移的临床模型。特定目标2将调查全球和RPL39- MpBC中一氧化氮合酶/PI3K抑制反应的特定核糖体翻译景观。在特定的目标3中，细胞- 肿瘤内肿瘤细胞、髓系细胞、淋巴样细胞和间质细胞之间的细胞相互作用 微环境及其在支持癌症生态位群体中的作用将在单细胞水平上进行评估 使用空间转录学、免疫荧光、细胞飞行时间成像系统和多模式数据分析 模特。因此，这项研究提出了一种组合靶向方法来对抗 MpBC中的两条关键路径，确定细胞之间的相互作用，并开发独特的串扰模型，将 有效地预测结果和治疗反应，并补充我们最近资助的U01临床试验 MpBC患者。

ABSTRACT Metaplastic breast cancer (MpBC) is a rare subset accounting for <5% of all breast cancers. MpBC is a significant health challenge as it exhibits the most dismal prognosis of all breast cancer subtypes, worse than non-MpBC triple-negative breast cancer (TNBC), with median survival rate of 8 months or less in patients with metastatic disease. Due to a lack of druggable targets, the main therapeutic option for metastatic MpBC remains systemic chemotherapy, despite known resistance to most cytotoxic drugs. One common molecular alteration in MpBC is hyperactivation of the phosphoinositide 3-kinase and protein kinase B (PI3K/AKT) pathway. Additionally, we published that MpBC also displays a gain-of-function oncogenic mutation in ribosomal protein L39 (RPL39), which is responsible for treatment resistance, stem cell self-renewal, and lung metastasis. The mechanistic function of RPL39 is mediated through inducible nitric oxide synthase (iNOS)-mediated nitric oxide production. In a recently published clinical trial targeting this nitric oxide synthase (NOS) pathway with a pan-NOS inhibitor NG-methyl-L-arginine acetate (L-NMMA), high efficacy in chemorefractory TNBC patients was demonstrated. Furthermore, in vivo studies performed showed a significant reduction in tumor growth, associated with a significant increase in apoptosis after the alpelisib/L-NMMA combinatorial regimen. Therefore, we hypothesize that the NOS and PI3K signaling pathways may exert their oncogenic responses synergistically to promote aggressive tumor growth. To test this hypothesis, Specific Aim 1 seeks to demonstrate the therapeutic efficacy of simultaneous inhibition of NOS and PI3K pathways with chemotherapy in MpBC pre- clinical models on primary tumor growth and metastasis. Specific Aim 2 will investigate the global and RPL39- specific ribosome translation landscape in response to NOS/PI3K inhibition in MpBC. In Specific Aim 3, the cell- cell interactions among tumor cells, myeloid cells, lymphoid cells, and stromal cells within the tumor microenvironment and their role in supporting cancer niche populations will be evaluated at the single-cell level using spatial transcriptomics, immunofluorescence, CyTOF imaging systems, and a multi-modal data analysis model. This study thus proposes a mechanistic investigation of a combinatorial targeted approach against the two key pathways in MpBC, identifies cell–cell interactions, and develops unique crosstalk models that will effectively predict outcome and treatment response and complement our recently funded U01 clinical trial on MpBC patients.