Regulation of Death Receptor 5 folding and apoptotic signaling by AGR2

描述 表皮生长因子受体家族酪氨酸激酶EGFR和HER 2在表皮细胞中过表达。 显著比例的侵袭性、难治性乳腺癌。这包括HER 2+肿瘤， 对HER 2特异性单克隆抗体和激酶抑制剂具有获得性耐药性， 乳腺癌（TNBC），其中约50%过度表达EGFR。选择性杀死EGFR+的药物 或HER 2+肿瘤通过一种新的作用机制，可以改善这些患者的生存期。 难治性癌症我们的团队报道了一类新的抗癌化合物，称为DDAs， 对EGFR+和HER 2+癌症的选择性毒性。已发表的和初步的结果表明， DDA杀死患者来源的乳腺异种移植肿瘤，对实验动物没有可检测到的毒性。DAs杀死 通过激活死亡受体4和5（DR 4/5），抗癌细胞因子TRAIL的受体，来治疗癌细胞。 然而，DDA以一种新的不依赖于TRAIL的方式激活DR 4/5。DDA导致的DR 4/5激活 DR 5表达升高、二硫键依赖性DR 4/5簇集和 DR 4/5与细胞表面结合。这些事件特异性地发生在EGFR或HER 2过表达癌细胞中， 导致半胱天冬酶8-半胱天冬酶3促凋亡级联的DR 4/5活化。在体外与此一致 选择性，肿瘤研究表明，DDA诱导的癌细胞凋亡，而没有毒性的相邻 正常组织本项目将检验蛋白质二硫键异构酶AGR 2 催化/陪伴EGFR、HER 2、DR 4和DR 5的天然二硫键。我们进一步假设， DDA抑制AGR 2酶活性，EGFR和HER 2通过竞争性增强DDA作用， DR 4/5用于有限的AGR 2池。具体目标1是阐明二硫化物 DR 4/5的胞外结构域内的结合抑制了它们的基础促凋亡活性，并证明了 癌细胞中的遗传或药理学DR 5激活足以诱导肿瘤消退。具体 目的2是研究DDAs阻断AGR 2 PDI活性的机制，并证明 DR 4/5激活介导癌细胞凋亡以响应AGR 2活性的消融。具体目标3是 确定DDA对患者源性乳腺肿瘤的疗效，并验证DDA的机制 体内作用与体外鉴定的一致。DDA疗效将与标准治疗进行比较， 药剂和组合方案。总之，这个探索性的项目将调查DDAs作为一种新的类别， 抗癌剂，阐明了介导DDA作用的新型AGR 2/死亡受体4/5级联，以及 建立针对转移性和耐药性HER 2+乳腺癌的患者来源模型的DDA功效。

Description The Epidermal Growth Factor Receptor-family tyrosine kinases EGFR and HER2 are overexpressed in a significant proportion of aggressive, treatment-refractory breast cancers. This includes HER2+ tumors that have acquired resistance to HER2-specific monoclonal antibodies and kinase inhibitors and Triple-Negative Breast Cancers (TNBCs), of which approximately 50% overexpress EGFR. Agents that selectively kill EGFR+ or HER2+ tumors through a novel mechanism of action could improve the survival of patients with these treatment-refractory cancers. Our team reported a new class of anticancer compounds, termed DDAs, with selective toxicity against EGFR+ and HER2+ cancers. Published and preliminary results demonstrate that DDAs kill patient-derived breast xenograft tumors without detectable toxicity to experimental animals. DDAs kill cancer cells by activating Death Receptors 4 and 5 (DR4/5), the receptors for the anticancer cytokine TRAIL. However, DDAs activate DR4/5 in a novel TRAIL-independent manner. DR4/5 activation by DDAs results from a combination of elevated DR5 expression, disulfide bond-dependent DR4/5 clustering, and localization of DR4/5 to the cell surface. These events occur specifically in EGFR or HER2 overexpressing cancer cells and result in DR4/5 activation of the Caspase 8-Caspase 3 pro-apoptotic cascade. Consistent with this in vitro selectivity, tumor studies demonstrate DDA-induced apoptosis of cancer cells without toxicity to adjacent normal tissues. This project will test the hypothesis that the protein disulfide isomerase AGR2 catalyzes/chaperones native disulfide bonding of EGFR, HER2, DR4, and DR5. We further hypothesize that DDAs inhibit AGR2 enzyme activity and that EGFR and HER2 strongly potentiate DDA actions by competing with DR4/5 for the limited pool of AGR2. Specific Aim 1 is to elucidate the mechanisms by which disulfide bonding within the extracellular domains of DR4/5 restrains their basal pro-apoptotic activity, and demonstrate that genetic or pharmacologic DR5 activation in cancer cells is sufficient to induce tumor regression. Specific Aim 2 is to investigate the mechanisms by which DDAs block AGR2 PDI activity and to demonstrate that DR4/5 activation mediates cancer cell apoptosis in response to ablating AGR2 activity. Specific Aim 3 is to establish the efficacy of DDAs against patient-derived breast tumors and verify that the mechanisms of DDA action in vivo match those identified in vitro. DDA efficacy will be compared with standard therapies in single agent and combination regimens. In summary, this exploratory project will investigate DDAs as a new class of anticancer agents, elucidate a novel AGR2/Death Receptor 4/5 cascade that mediates DDA actions, and establish DDA efficacy against patient-derived models of metastatic and drug-resistant HER2+ breast cancer.