Targeting both intrinsic and extrinsic apoptosis by FLLL-12 in lung cancer

描述(申请人提供)：肺癌是所有恶性肿瘤中最致命的，2011年美国估计有221,130例新病例和156,940例死亡。尽管常规外科手术、放射治疗和化疗取得了进展，但肺癌的5年生存率几乎没有变化，仍不到15%。可以通过实施化学预防战略来降低肺癌死亡率，这些战略可以逆转或阻止癌前疾病的进展。激活凋亡通路以消除癌前细胞是化学预防的重要途径。此外，在疾病发展过程中处于失活状态的肿瘤抑制通路的重新激活对于制定有效的化学预防策略非常重要。AKT的激活是肺癌中常见的几种致癌基因突变的下游关键成分，如EGFR、KRAS、PTEN、PI3KCA等。我们假设，抑癌基因FOXO通路是通过激活的AKT而不是缺失或突变来磷酸化而失活的。因此，可以通过灭活AKT来重新激活FOXO途径，同时激活其他凋亡途径的药物，如死亡受体介导的细胞凋亡，可能是有效的化学预防药物。过去几十年来广泛的临床前研究表明，姜黄素具有很强的化学预防潜力，这使该药物进入临床试验。然而，低效力和低生物利用度是关键的挑战。为了规避这些问题，正在采取几种方法，例如合成更有效的类似物、修改给药系统或确定与天然姜黄素具有协同作用的药物。我们发现，合成的姜黄素类似物FLLL-12对肺癌细胞株显示出5-10倍的效力，并激活AKT-FOXO信号的下游促凋亡效应因子Bim，同时使AKT失活。同时，Fll-12激活了DR5-caspase8的凋亡通路。由于Fll-12激活了内在和外在途径的生物标记物，我们推测Fll-12是一种新型的无毒药物，其靶向是AKT-FOXO-Bim和DR5-caspase 8途径，其对肺癌的化学预防作用。为了验证我们的假设，我们设计了三个特定的目标：(1)研究Fll-12诱导内源性细胞凋亡的机制；(2)研究DR5通路以了解外源性(caspase 8介导的)细胞凋亡；(3)研究Flll-12在小鼠体内的有效性和生物利用度。我们预计这项提议 研究将确定Fll-12是一种用于预防和控制肺癌生长的机制制剂。这将在临床前的小鼠模型中建立其体内有效性。因此， 这项初步研究的完成将有助于我们进一步开发这种化合物，用于预防肺癌的临床应用。

DESCRIPTION (provided by applicant): Lung cancer is the deadliest of all malignancies with an estimated 221,130 new cases and 156,940 deaths in the year 2011 in the United States. Despite advances in conventional surgical procedures, radiotherapy, and chemotherapy, the 5 year survival rate for lung cancer remains almost unchanged, at less than 15%. Mortality from lung cancer could be reduced through the implementation of chemopreventive strategies that can reverse or impede the progression of pre-malignant disease. Activation of apoptotic pathways to eliminate pre- malignant cells is an important approach for chemoprevention. Moreover, reactivation of the tumor suppressor pathways which are inactivated throughout disease progression is important to develop effective chemopreventive strategies. Activation of AKT is a critical component downstream of several driver oncogenic mutations frequently found in lung cancers such as EGFR, KRAS, PTEN, PI3KCA, etc. We hypothesize that the tumor suppressor FOXO pathway is inactivated through phosphorylation by activated AKT rather than deletion or mutation. Therefore, agents that could reactivate the FOXO pathway by inactivating AKT and simultaneously activate other apoptotic pathways, such as death receptor-mediated apoptosis, might be effective chemopreventive agents. Extensive preclinical research over the last several decades has demonstrated that curcumin has strong potential for chemoprevention, which brought this agent into clinical trials. However, low potency and poor bioavailability are critical challenges. To circumvent these problems, several approaches are being undertaken, such as synthesis of more potent analogs, modification of the delivery system or identification of agents that show synergy with natural curcumin. We found that the synthetic curcumin analog FLLL-12 shows 5-10-fold more potency against lung cancer cell lines and activates Bim, a downstream pro-apoptotic effector of AKT-FOXO signaling along with inactivation of AKT. At the same time, FLLL-12 activates the DR5-caspase 8 apoptotic pathway. Since FLLL-12 activates biomarkers of both intrinsic and extrinsic pathways, we hypothesize that FLLL-12 is a novel non-toxic agent that targets the AKT-FOXO- Bim and DR5-caspase 8 pathways in its chemopreventive efficacy against lung tumorigenesis. To test our hypothesis, we have designed three specific aims: (1) to study the mechanism of intrinsic apoptosis induced by FLLL-12; (2) to investigate the DR5 pathway to understand extrinsic (caspase 8-mediated) apoptosis; and (3) to study the in vivo efficacy and bioavailability of FLLL-12 in mice. We anticipate that this proposed study will identify FLLL-12 as a mechanism-based agent for the prevention and control of lung cancer growth. This will establish its in vivo efficacy in a pre-clinical mouse model. Accordingly, completion of this pilot study would help us to further develop this compound for clinical application for lung cancer prevention.