Inhibition of IGF-1R: A Therapeutic Strategy for Colon Cancer Stem-like Cells

 描述(由申请人提供)： 抑制IGF-1R：一种抑制结肠癌干细胞样细胞PD/PI的治疗策略：Patel，Bhaumik B.项目描述摘要：尽管最近在治疗方面取得了进展，但结直肠癌仍然是美国第三大致死性癌症。这主要归因于被称为干细胞(CSCs)的一小部分癌症细胞的存活，这些细胞表现出自我更新的失调，细胞水平的异常分化，以及对大多数阻止癌症完全治愈的癌症化疗的耐药性。我们已经证明，抑制IGF-1R-AKT-mTOR(Inat)轴是一种很有前途的方法，可以在肿瘤内靶向这些耐药群体。然而，这一承诺并没有辜负人们的高期望。我们已经发现了IGF-1R抑制CSCs的一个新的、关键的和临床相关的机制，包括下调广泛使用的降胆固醇药物他汀类药物靶向的类固醇合成前体途径甲戊酸-异戊二烯生物合成(MIB)的水平。抑制MIB途径导致几种生物活性萜类物质的耗竭，这些活性萜类物质参与了蛋白质预烯基化和N-糖基化等关键生物学过程，而N-糖基化又反过来调节了控制结肠CSCs生长的关键途径？？连环蛋白信号转导。我们假设，同时抑制inat轴和MIB途径的联合策略，与FDA批准的药物或那些处于临床晚期开发中的药物，将导致MIB途径、？-catenin信号和CSCs生长的协同下调。这一假设将在三个具体目标上得到检验。在体外和体内的CSCs模型以及利用原代人类结肠癌标本，我们将建立inat轴和MIB途径上调对CSCs生长的意义(目标1)。随后，我们将通过在10个具有不同基因变化代表散发性结肠癌的结肠癌细胞系中进行体外筛选的序贯策略，确定靶向inat轴的选定药物与抑制MIB途径的药物的最佳治疗组合(S)，以确定将在CSCs生长的动物模型中应用的高度协同的组合(目标2)。此外，我们将通过先进的生物物理和生化研究来研究inat轴(单独或与MIB途径抑制剂联合使用，也是最佳的抗CSCs组合(S))抑制MIB途径下调和CSCs生长的详细分子机制，以a)确定甲羟戊酸途径代谢物的水平，b)确定inat-SREBP轴在调节MIB途径酶基因特异性转录中的作用，以及c)研究下游萜类分子(调节预烯基化和N-糖基化)在调节？-catenin/Tcf-4信号通路中的作用(目标3)。拟议实验的结果将极大地扩展我们对结肠CSCs生长机制的理解，并确定将立即在临床试验(S)中测试的“最佳抗CSCs组合(S)”疗法，并将对结直肠癌的治疗具有范式转换的意义。1

 DESCRIPTION (provided by applicant): Inhibition of IGF-1R: A therapeutic strategy to inhibit colon cancer stem-like cells PD/PI: Patel, Bhaumik B. PROJECT DESCRIPTION Abstract: Despite recent advances in therapeutics, colorectal cancer remains the third deadliest cancer in the USA. This is mainly attributable to survival of a small population of cancer cells called stem cells (CSCs), which display dysregulated self-renewal, aberrant differentiation at the cellular level, and resistance to most cancer chemotherapies preventing complete cure of cancer. Others and we have shown that inhibition of IGF-1R- AKT-mTOR (InAT) axis is a promising approach to target this resistant population within the tumors. However, this promise has not lived up to the high expectations. We have uncovered a novel, critical and clinically relevant mechanism of IGF-1R inhibition's effect on CSCs that involves downregulation of mevalonate- isoprenoid biosynthesis (MIB) pathway, a precursor pathway of steroid synthesis, at levels distal to that targeted by statins, th widely used anti-cholesterol drugs. Inhibition of MIB pathway results in depletion of several bioactive terpenes that are involved in critical biological processes such as protein prenylation and N- Glycosylation, which in turn regulates ß-catenin signaling, a critical pathway governing colonic CSCs growth. We hypothesize that that a combination strategy employing simultaneous inhibition of InAT axis and MIB pathway, with FDA-approved agents or those that are in advanced clinical development, will results in synergistic downregulation of MIB pathway, ß-catenin signaling, and CSCs growth. This hypothesis will be tested in three specific aims. In vitro and in vivo models of CSCs as well as utilizing primary human colon cancer samples, we will establish significance of InAT axis and MIB pathway upregulation on CSCs growth (Aim 1). Subsequently, we will determine optimal therapeutic combination(s) of select agents from targeting InAT axis combined with those that suppress MIB pathway by employing sequential strategy of in vitro screening of the proposed drug combination in 10 selected colon cancer cell lines, with diverse genetic changes representing sporadic CRC, to identify highly synergistic combinations that will be advanced in animal models of CSCs growth (Aim 2). Moreover, we will examine detailed molecular mechanisms of inhibition of InAT axis (alone or in combination with a MIB pathway inhibitor, also 'optimum anti-CSCs combination(s)') on MIB pathway downregulation as well as CSCs growth by employing advanced biophysical and biochemical studies to a) determine levels of mevalonate pathway metabolites, b) determine the role of InAT-SREBP axis in regulating gene specific transcription of MIB pathway enzymes, and c) examining the role of downstream terpene molecules (which regulate prenylation and N-glycosylation) in regulating ß-catenin/TCF-4 signaling (Aim 3). The results from the proposed experiments would greatly expand our understanding of mechanisms of colon CSCs growth and identify 'optimum anti-CSCs combination(s)' therapy that will be immediately testable in the clinical trial(s), and will have paradigm-shifting implications in the treatment of colorectal cancr. 1