Co-targeting PDAC tumor cells and the microenvironment to succeed in EGFR/ErbB2-targeted therapy

项目概要/摘要 胰腺导管腺癌（PDAC）是最致命的癌症类型之一，有毁灭性的7%的五- 年生存率。目前，对于PDAC患者没有有效的治疗方法。吉西他滨，一线 晚期PDAC的辅助化疗仅在6-11%的PDAC中产生轻度治疗反应 患者靶向治疗和免疫治疗在PDAC中也显示出非常有限的疗效。EGFR经常 在PDAC中激活尽管EGFR酪氨酸激酶抑制剂（TKI）厄洛替尼与 吉西他滨，已被FDA批准用于PDAC治疗，联合用药仅轻微改善PDAC 与吉西他滨单药治疗相比，患者的生存率（1年生存率：23% vs. 17%）。令人困惑的是， EGFR/ErbB 2靶向治疗仅具有非常有限的益处，尽管EGFR/ErbB 2活化频繁。 PDAC。最近，我们发现14-3-3？过表达（14-3-3？+）PDAC细胞增加EGFR/ErbB 2 EGFR/ErbB 2双重TKI（拉帕替尼）在培养时有效抑制其活化和生长 一个人但是，同样的14-3-3？拉帕替尼对EGFR/ErbB 2激活的PDAC细胞无抑制作用 当与成纤维细胞共培养时。数据在表型上复制了EGFR/ErbB 2 TKI的低应答， PDAC患者，并提出纤维化肿瘤微环境（TME）可能使PDAC肿瘤细胞 EGFR/ErbB 2 TKI耐药。PDAC肿瘤细胞及其纤维化TME细胞相互沟通以共同进化 形成恶性循环。事实上，我们发现，14-3-3？+ PDAC细胞分泌更多的CXCL 5， 激活成纤维细胞中的PI 3 K-Akt-GSK 3 β信号传导轴。PI 3 K-Akt-GSK 3 β轴功能促进 成纤维细胞活化并参与多种纤维化疾病。我们的数据表明，14-3-3？+在PDAC中 肿瘤细胞激活成纤维细胞中的PI 3 K-Akt-GSK-3β轴，这使得PDAC肿瘤细胞 EGFR/ErbB 2 TKI耐药。然后，我们测试了靶向PI 3 K/Akt是否可以防止成纤维细胞活化， 从而使PDAC肿瘤细胞对EGFR/ErbB 2 TKI敏感。虽然通过抑制剂靶向PI 3 K/Akt， （BKM 120）本身对PDAC细胞生长无显著影响，共靶向PI 3 K/Akt功能， 拉帕替尼对PDAC细胞中EGFR/ErbB 2的激活有效地抑制了PDAC细胞中EGFR/ErbB 2的表达。 与成纤维细胞共培养生长。因此，我们假设PDAC所造成的恶性循环 肿瘤细胞及其纤维化TME促进PDAC对EGFR/ErbB 2 TKI的耐药性; PDAC肿瘤细胞中的EGFR/ErbB 2活化和纤维化TME中的PI 3 K-Akt赋予PDAC对以下的敏感性： EGFR/ErbB 2靶向治疗。该提案的主要目标是：1）系统地测试治疗药物， 共靶向PDAC细胞中的EGFR/ErbB 2活化和纤维化TME中的PI 3 K-Akt信号传导在各种肿瘤中的功效 体外和体内PDAC模型;和2）鉴定促进PDAC肿瘤细胞增殖的成纤维细胞衍生的分子。 EGFR/ErbB 2靶向治疗的耐药性。这些研究的成功完成将指导设计 有效的靶向治疗，然后可以转化为临床治疗PDAC患者。

Project Summary/Abstract Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancer types with a devastating 7% five- year survival rate. At present, no effective treatment exists for PDAC patients. Gemcitabine, the first-line adjuvant chemo-therapy for advanced PDAC, only yields a mild therapeutic response in 6-11% of PDAC patients. Targeted- and immuno-therapies have also showed very limited efficacy in PDAC. EGFR is frequently activated in PDAC. Although an EGFR tyrosine kinase inhibitor (TKI), erlotinib, in combination with gemcitabine, has been approved by FDA for PDAC treatment, the combination only slightly improved PDAC patients’ survival compared to gemcitabine alone (one year survival: 23% vs. 17%). It has been puzzling why EGFR/ErbB2 targeted therapies only had very limited benefits despite of frequent EGFR/ErbB2 activations in PDAC. Recently, we found that 14-3-3? overexpressing (14-3-3?+++) PDAC cells increase EGFR/ErbB2 activation and their growth were effectively inhibited by an EGFR/ErbB2 dual TKI (lapatinib) when cultured alone. However, the same 14-3-3?+++ and EGFR/ErbB2 activated PDAC cells were not inhibited by lapatinib when co-cultured with fibroblasts. The data phenotypically copy the low response to EGFR/ErbB2 TKIs in PDAC patients and suggested that the fibrotic tumor microenvironment (TME) may render PDAC tumor cells resistant to EGFR/ErbB2 TKIs. PDAC tumor cells and its fibrotic TME reciprocally communicate to co-evolve creating a vicious cycle. Indeed, we found that the 14-3-3?+++ PDAC cells secrete more CXCL5 which activates the PI3K-Akt-GSK3β signaling axis in fibroblasts. PI3K-Akt-GSK3β axis functions to promote fibroblast activation and is involved in multiple fibrotic diseases. Our data suggest that 14-3-3?+++ in PDAC tumor cells activates the PI3K-Akt-GSK-3β axis in fibroblasts which reciprocally confers PDAC tumor cell resistance to EGFR/ErbB2 TKIs. We then tested if targeting PI3K/Akt could prevent fibroblast activation and, thereby, sensitize PDAC tumor cells to EGFR/ErbB2 TKIs. Although targeting PI3K/Akt by an inhibitor (BKM120) had no significant effect on PDAC cell growth on its own, co-targeting PI3K/Akt function in fibroblasts by BKM120 and EGFR/ErbB2 activation in PDAC cells by lapatinib effectively inhibited PDAC cell growth in co-culture with fibroblasts. Therefore, we hypothesize that the vicious cycle created by the PDAC tumor cells and their fibrotic TME promotes PDAC resistance to EGFR/ErbB2 TKIs; whereas co-targeting EGFR/ErbB2 activation in the PDAC tumor cells and PI3K-Akt in fibrotic TME confers PDAC sensitivity to EGFR/ErbB2 targeted therapies. The major goals of this proposal are 1) to systematically test the therapeutic efficacy of co-targeting EGFR/ErbB2 activation in PDAC cells and PI3K-Akt signaling in fibrotic TME in various PDAC models in vitro and in vivo; and 2) to identify fibroblast-derived molecules that promote PDAC tumor cell resistance to EGFR/ErbB2 targeted therapies. The successful completion of these studies will guide the design of effective targeted therapies that can then be translated into the clinic to treat PDAC patients.