Improved Diagnosis and Treatment of Cushing's Disease

我们发现，虽然促肾上腺皮质激素瘤是良性肿瘤，但它们经历的代谢重新编程很像恶性肿瘤。我们发现，代谢重编程是通过己糖激酶-1(HK-1)到HK-2、乳酸脱氢酶A(LDH-A)到乳酸脱氢酶-B(LDH-A)的同工酶转换和核靶向6-phosphofructo-2-kinase/fructose-2，6-bisphosphatase-3(PFKFB3)来介导的。我们还假设，核靶向PFKFB3为细胞周期抑制物p27在人促肾上腺皮质激素瘤中的下调提供了一种原因机制。我们发现，人促肾上腺皮质激素瘤过表达葡萄糖转运蛋白1(GLUT1)，从而增加葡萄糖的摄取。然后，我们证明了GLUT1的表达可以通过促分泌剂如促肾上腺皮质激素释放激素(CRH)的刺激而转录调节。我们将这些发现转化为改进促肾上腺皮质激素瘤的FDG-PET检测(葡萄糖摄取的标志)(NIH协议12-N-0007)。5我们发现CRH刺激导致腺瘤平均FDG摄取增加。通常，这些肿瘤在核磁共振成像上是看不见的。在CRH刺激下，盲人神经放射科医生能够在PET成像上发现40%的MRI隐形垂体腺瘤。 我们发现促肾上腺皮质激素瘤的生存依赖于葡萄糖和糖酵解途径。2用3-溴丙酮酸选择性抑制HK-2可显著降低糖酵解活性和细胞存活率，特别是在人促肾上腺皮质激素瘤中，而保留正常腺体。然后我们发现，通过使用针对肿瘤中GLUT1表达的药物(例如组蛋白去乙酰酶抑制剂SAHA)，我们能够减少体外培养的人促肾上腺皮质激素瘤的存活率和激素分泌。正常情况下，ACTH的分泌是通过维甲酸受体(RXR)和肝X受体(LXR)的异源二聚体激活POMC基因的启动子来调节的。我们发现，在体外培养的小鼠肿瘤细胞中，SAHA选择性地转录下调LXR，而在正常的促肾上腺皮质激素细胞中则没有。基于这些发现，我们现在正在启动CD患者口服SAHA的临床试验，以测试其在术前正常化激素水平方面的有效性。 利用美国国立卫生研究院独有的CD患者的大型临床数据集，我的团队得出了一个关键的见解，即术后状态代表着一种内源性压力测试。这一洞察力现在允许临床医生仅从术后一个激素数据点预测CD手术后激素缓解。8我的团队还能够使用该数据集得出预测规则，可以帮助临床医生预测这种激素缓解的持久性。 对毫米大小的垂体腺瘤进行成功的术前成像可以改善CD的手术结果。我的团队正在推进成像技术，以帮助检测这些腺瘤。我们开发了一种用于CD6手术的新型MRI线圈，现在我们正在开始这种线圈的首次人体试验。我们还发现，延迟增强后MRI成像是发现小的、否则MRI看不见的腺瘤的最有用的策略。

We discovered that although corticotropinomas are benign tumors, they undergo metabolic reprogramming much like malignant cancers. We found that metabolic reprogramming is mediated via isozyme switching of Hexokinase-1 (HK-1) to HK-2, lactate dehydrogenase A (LDH-A) to LDH-B and by nuclear targeting of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-3 (PFKFB3). We also posit that nuclear targeting of PFKFB3 provides a causal mechanism for downregulation of cell cycle inhibitor p27 in human corticotropinomas. We found that human corticotropinomas overexpress glucose transporter 1 (GLUT1) that allows increased uptake of glucose. We then demonstrated that GLUT1 expression can be transcriptionally modulated by stimulation with secretagogues such as corticotropin releasing hormone (CRH). We have translated these findings to improve FDG-PET detection (a marker of glucose uptake) of corticotropinomas (NIH Protocol 12-N-0007).5 We found that CRH stimulation led to increased mean FDG uptake in adenomas. Frequently, these tumors are invisible on MRI imaging. With CRH stimulation, blinded neuroradiologists were able to detect 40% of MRI invisible pituitary adenomas on PET imaging. We showed that corticotropinomas rely on glucose and the glycolytic pathway for survival.2 Selective inhibition of HK-2 with 3-bromo-pyruvate led to significantly decreased glycolytic activity and cell survival specifically in human corticotropinomas while sparing the normal gland. We then found that by using drugs that specifically target GLUT1 expression in tumors (such as a histone deacetylase inhibitor SAHA), we were able to decrease survival and hormone secretion in human corticotropinomas ex-vivo. Normally, ACTH secretion is modulated by promoter activation of the POMC gene by a heterodimer of retinoic receptor (RXR) and liver X receptor (LXR). We found SAHA transcriptionally downregulated LXR selectively in murine tumor cells in-vitro but not in normal corticotrophs. Based on these findings, we are now initiating a clinical trial of oral SAHA in patients with CD to test its efficacy in normalizing hormone levels pre-operatively. Using the large clinical dataset of CD patients that is uniquely available at NIH, my group developed a critical insight that the post-operative state represents an endogenous stress test. This insight now allows clinicians to predict hormonal remission after surgery for CD from just one post-operative serum hormone data point.8 My group was also able to use this dataset to derive predictive rules that could help clinicians predict the durability of such hormonal remission. Successful pre-operative imaging of millimeter sized pituitary adenomas can lead to improved surgical outcomes in CD. My group is advancing imaging to help detect these adenomas. We developed a novel MRI coil that is designed to be used during surgery for CD6 and we are now starting a first-in-human trial of this coil. We also found that delayed post contrast MRI imaging was the most useful strategy to detect small, otherwise MRI invisible adenomas.