NMR detection of tumor differentiation

描述（由申请人提供）：NCI在癌症治疗领域建立的最重要的目标之一是将癌症从急性和致命疾病转化为可以长期管理的慢性疾病。实现这一目标需要两个要求：1）开发新的抗癌药物和利用这些药物的治疗方案，以及2）准确和非侵入性评估这些治疗方案有效性的能力。分化剂在癌症治疗的这一领域中是一种有吸引力的可能性，因为它们是可以引起恶性表型逆转或触发细胞凋亡的试剂。我们在这个项目中的目标是描绘的机制，苯乙酸（PA）和苯丁酸（PB），目前在II期临床试验的两个分化剂，抑制癌细胞的增殖。我们将集中在磷脂酰胆碱（PtdCho）代谢物的变化，可以观察到使用在体内磁共振波谱（MRS）的目标，确定光谱指标，可以可靠地用作PA和PB的增殖抑制和诱导凋亡的指标。这可以提供一个基础，临床监测反应分化治疗的1H MRS。在体内动物肿瘤的研究将结合灌注细胞的机制研究，使用MR光谱与荧光显微镜，流式细胞术和分子生物学技术，以确定关键的检查点PtdCho catastrophic与分化治疗。我们的初步研究表明，PA和PB诱导与诱导相关的MR可见磷脂代谢物水平的变化 细胞凋亡。使用荧光磷脂酶激活的磷脂类似物，我们已经确定了两种不同的磷脂酶活性的前列腺癌细胞：一个是组成性的，主要是核，和一个是细胞质和诱导PA或PB。因此，本申请的目的是i）测量分化剂诱导的体外和体内磷脂酶活化，ii）鉴定在PB诱导的细胞凋亡中有助于光谱变化的磷脂酶同种型; iii）检查磷脂酶抑制对经历细胞凋亡的肿瘤细胞中的MR可见代谢物的影响，以及iv）研究MR-可见代谢物的潜力。可见共振作为对鼠肿瘤模型中的分化疗法的应答的标志物。这些研究为分化治疗诱导磷脂代谢的变化提供了机制基础，因此构成了对胆碱代谢的理解的重要进展，用于解释肿瘤的体内MR谱。

DESCRIPTION (provided by applicant): One of the most important goals that NCI has established in the area of cancer treatment has been for the conversion of cancer from an acute and lethal disease to a chronic condition that can be managed long term. Two requirements are needed to achieve this goal: 1) the development of new anticancer drugs and treatment regimens utilizing these drugs, and 2) the ability to accurately and non-invasively assess the effectiveness of these treatment regimens. Differentiating agents are an attractive possibility in this area of cancer treatment, for they are agents that can either cause reversion of the malignant phenotype or the triggering of apoptosis. Our goal in this project is to delineate the mechanisms by which phenylacetate (PA) and phenylbutyrate (PB), two differentiating agents currently under Phase II clinical trials, inhibit the proliferation of cancer cells. We will concentrate on the changes in phosphatidylcholine (PtdCho) metabolites that can be observed using in vivo magnetic resonance spectroscopy (MRS) with the goal of determining the spectroscopic indicators that can reliably be used as an index for the inhibition of proliferation and induction of apoptosis by PA and PB. This could provide a basis for clinical monitoring of response to differentiation therapy by 1H MRS. In vivo animal tumor studies will be combined with mechanistic studies on perfused cells, using MR spectroscopy with fluorescence microscopy, flow cytometry and molecular biology techniques to identify key checkpoints in PtdCho catabolism associated with differentiation therapy. Our preliminary studies indicate that PA and PB induce changes in MR-visible phospholipid metabolite levels that correlate with the induction of apoptosis. Using fluorescent phospholipase-activated phospholipid analogues, we have identified two different phospholipase activities in prostate cancer cells: one that is constitutive and primarily nuclear, and one that is cytoplasmic and inducible by PA or PB. Thus, the aims of this application are to i) measure in vitro and in vivo phospholipase activation induced by differentiating agents, ii) identify the phospholipase isoform contributing to spectral changes in PBinduced apoptosis; iii) examine the effects of phospholipase inhibition on the MR-visible metabolites in tumor cells undergoing apoptosis and iv) to investigate the potential of MR-visible resonances as a marker for response to differentiation therapy in murine tumor models. These studies provide a mechanistic underpinning for the changes induced in phospholipid metabolism by differentiation therapy and therefore constitute an important advance in the understanding of choline metabolism for the interpretation of in vivo MR spectra of tumors.