FoXM1 inhibition: a novel therapeutic avenue to treat breast cancers

DNA损伤反应（DDR）缺陷是正常细胞获得致癌基因的主要因素， 突变然而，在肿瘤形成后，癌细胞通过修复DNA损伤来管理它们的生存 是由未经检查的DNA复制造成的癌细胞可以使用替代或备份DNA修复程序 以克服其DDR缺陷。例如，同源重组（HR）缺陷的癌细胞 蛋白质（如BRCA 1）可以通过依赖于其他高表达的HR相关蛋白质来修复它们的DNA， (such如RAD 51或PARP 1）或通过使用其它DNA修复机制如替代性非同源末端 连接（ALT NHEJ）和基底切除修复（BER）。癌细胞对这些救援DNA修复的依赖 途径有助于治疗耐药性;因此，成功靶向在治疗耐药性中起关键作用的因子， 多个DNA修复途径将具有有希望的临床结果。DNA修复途径的改变 通常发生在乳腺癌（BC）进展期间。例如，三阴性乳腺癌（TNBC）和三阴性乳腺癌（TNBC）。 侵袭性BC亚型，经常作为远处转移复发，具有功能障碍的BRCA 1，但表达 RAD 51的水平。此外，雌激素受体阳性BC（ER+BC）占所有BC的约70%， 使用ALT NHEJ、HR或BER来修复他们的DNA。值得注意的是，ER+ BC获得对内分泌治疗的抗性 以及通过诱导DNA修复基因的表达来破坏DNA的化疗药物。一个关键因素是， 参与调节多种DNA修复途径的是FOXM 1，其在TNBC和治疗中高度表达。 耐药ER+ BC。已知FOXM 1促进对化疗药物和抗雌激素疗法的抗性。 在这项提案中，我们提供了令人信服的证据，证明丙咪嗪蓝（IB），一种新的类似物， 我们最近合成的丙咪嗪抑制FOXM 1相关的信号传导，阻碍DNA修复能力， TNBC和ER+BC。使用来自BC患者的肿瘤外植体和肿瘤异种移植模型，我们已经证明， IB抑制TNBC和ER+BC的生长而不诱导任何毒性。此外，我们的研究表明， IB可使内分泌抵抗ER+BCs对他莫昔芬（TAM）敏感，并提高DNA损伤的疗效 TNBC中的化疗药物。基于这些观察，我们假设FOXM 1是一个关键的组成部分， 拯救DNA修复途径，使BC上瘾生存; IB抑制ER+BC和TNBC生长 以及通过靶向FOXM 1及其相关信号传导增强治疗反应; IB是治疗ER+BC和TNBC安全有效的药物。在目标1中，我们将描述IB目标 本发明的目的是研究IB与蛋白质相互作用的关系，并确定IB调节其在TNBC和ER+BC中的靶基因的机制。 在目标2中，我们将检验IB抑制TNBC和ER+BCs生长、转移并增强治疗的假设。 通过抑制这些癌症用来生存的备份DNA修复途径来响应。在目标3中，我们将测试 通过在人源化小鼠中使用患者来源的异种移植物和通过使用人乳腺癌， 癌症外植体研究。我们还将建立IB未来临床开发所需的PK/PD参数。

Defects in DNA damage response (DDR) is major factor that predispose normal cells to acquire oncogenic mutations. However, after a tumor develops, cancer cells manage their survival by repairing DNA damage resulting from unchecked DNA replication. Cancer cells can use the alternative or backup DNA repair programs to overcome their DDR defects. For example, cancer cells with deficiency in homologous recombination (HR) proteins (such as BRCA1) can repair their DNA by either relying on other highly expressed HR-related proteins (such as RAD51 or PARP1) or by using other DNA repair mechanisms such as alternative non-homologous end joining (ALT NHEJ) and basal excision repair (BER). The addiction of cancer cells to these rescue DNA repair pathways contributes to therapy-resistance; therefore, successful targeting of factor(s) that play critical role in multiple DNA repair pathways will have promising clinical outcomes. Alterations in DNA repair pathways commonly occur during breast cancer (BC) progression. For example, triple negative breast cancer (TNBC) an aggressive BC subtype that frequently relapses as distant metastases, have dysfunctional BRCA1 but expresses high levels of RAD51. Further, estrogen receptor positive BC (ER+BC), which accounts for ~70% of all BCs, employs ALT NHEJ, HR or BER to repair their DNA. Notably, ER+BCs acquire resistance to endocrine therapy and DNA-damaging chemotherapy drugs by inducing expression of DNA repair genes. A key factor that is involved in regulating multiple DNA repair pathways is FOXM1, which is highly expressed in TNBC and therapy resistant ER+BCs. FOXM1 is known to promote resistance to chemotherapy drugs and anti-estrogen therapies. In this proposal, we provide compelling evidence that imipramine blue (IB), a novel analogue of anti-depressant imipramine that we recently synthesized inhibits FOXM1-associated signaling impeding DNA repair ability of TNBCs and ER+BC. Using tumor explants from BC patients and tumor xenograft models, we have demonstrated that IB inhibits the growth of TNBC and ER+BC without inducing any toxicity. Further, our studies have shown that IB may sensitize endocrine resistant ER+BCs to tamoxifen (TAM) and improve the efficacy of DNA damaging chemotherapy drugs in TNBC. Based on these observations, we hypothesize that FOXM1 is a critical component of rescue DNA repair pathways that BCs get addicted to survive; that IB suppresses ER+BC and TNBC growth and progression as well as enhances the therapy response by targeting FOXM1 and its associated signaling; and that IB is a safe and effective drug for treating ER+BC and TNBC. In Aim 1, we will characterize the IB-target protein interaction and determine the mechanism(s) by which IB regulates its target genes in TNBC and ER+BC. In Aim 2, we will test the hypothesis that IB inhibits TNBC and ER+BCs growth, metastasis, and enhances therapy response by inhibiting backup DNA repair pathways that these cancers employ to survive. In Aim 3, we will test the safety and viability of IB by using patient derived xenografts in humanized mice and by using human breast cancer explant studies. We will also establish PK/PD parameters required for future clinical development of IB.