Targeting 6-Phosphofructo-2-Kinase to increase efficacy of CDK4/6 Inhibitors

我们最近发现了一种新的致癌机制，通过细胞周期蛋白D1绕过对CDK4/6的抑制 从而刺激6-磷酸果糖-2-激酶(PFKFB3)和葡萄糖代谢。这样做的目的是 建议表征PFKFB3在调节对CDK4/6抑制的适应或抵抗中的作用，并 确定新的方法来提高CDK4/6抑制剂的疗效，以便在 IV期高危乳腺癌患者。雌激素受体(ER)-细胞周期蛋白D1-CDK4/6信号转导通路失控 这是ER乳腺癌的一个标志，促使CDK4/6抑制剂的开发。虽然 对ER晚期乳腺癌患者应用CDK4/6抑制剂可导致 随着无进展生存率的提高，几乎所有患者都会随着时间的推移而不变地产生抵抗和复发。 通过抑制CDK4/6激活葡萄糖代谢正变得越来越明显。一个关键的刺激物 糖酵解是一种合成2，6-二磷酸果糖(F2，6BP)的PFKFB3酶，它是一种有效的变构 限速因子6-磷酸果糖-1-激酶(PFK1)的激活剂。F2，6BP控制整个系统的流量 糖酵解途径，因此是癌细胞增殖所必需的。在初步研究中，我们 提供证据表明，内质网中CDK4抑制后，PFKFB3的表达和活性增加 癌细胞和乳腺癌患者肿瘤。值得注意的是，我们发现PFKFB3抑制剂，PFK-158，增加了 抗CDK4靶向治疗的体内外抗肿瘤活性。我们假设PFKFB3是一个 细胞周期蛋白D1-CDK4/6轴的重要调节效应物，通过以下途径减弱CDK4/6的抑制作用 刺激葡萄糖代谢。此外，我们假设，基因或药物抑制对 PFKFB3将通过使细胞维持足够的能力来增加CDK4/6抑制剂的疗效 葡萄糖代谢是生存和生长所必需的。目标1将确定CDK4/6的机制 抑制可诱导PFKFB3的表达。目标2将确定联合应用CDK4/6和PFKFB3的效果 抑制葡萄糖代谢、细胞周期、体外生长和存活。目标3将检查新陈代谢和 药物抑制CDK4/6和PFKFB3单药及联合应用对小鼠生长的影响 小鼠体内乳腺癌模型的建立。我们预计我们的研究将支持PFKFB3的临床测试 联合应用CDK4/6抑制剂可提高晚期ER乳腺癌患者的生存率。

We have recently discovered a novel oncogenic mechanism whereby cyclin D1 bypasses CDK4/6 inhibition resulting in the stimulation of 6-phosphofructo-2-kinase (PFKFB3) and glucose metabolism. The objective of this proposal is to characterize the role of PFKFB3 in mediating adaptation or resistance to CDK4/6 inhibition and to define new approaches to increase the efficacy of CDK4/6 inhibitors in order to enable durable responses in stage IV HR+ breast cancer patients. Deregulation of the estrogen receptor (ER)-cyclin D1-CDK4/6 pathway is a hallmark of ER+ breast cancer that has prompted the development of CDK4/6 inhibitors. Although administration of CDK4/6 inhibitors to patients with ER+ advanced breast cancers have resulted in an improvement in progression free survival, almost all patients invariable develop resistance and relapse over time. Activation of glucose metabolism upon CDK4/6 inhibition is becoming increasingly evident. A key stimulator of glycolysis is the PFKFB3 enzyme which synthesizes fructose 2,6-bisphosphate (F2,6BP), a potent allosteric activator of the rate-limiting 6-phosphofructo-1-kinase (PFK1). F2,6BP controls flux throughout the entire glycolytic pathway and, as a result is required for the proliferation of cancer cells. In preliminary studies, we provide evidence that PFKFB3 expression and activity is increased in response to CDK4 inhibition in ER+ breast cancer cells and breast cancer patient tumors. Notably, we show that a PFKFB3 inhibitor, PFK-158, increases the anti-tumor activity of anti-CDK4 targeted therapy in vitro and in vivo. We postulate that PFKFB3 is an essential regulatory effector of the cyclin D1-CDK4/6 axis that serves to attenuate CDK4/6 inhibition effects by stimulating glucose metabolism. Furthermore, we hypothesize that genetic or pharmacological inhibition of PFKFB3 will increase the efficacy of CDK4/6 inhibitors by disabling the ability of the cell to sustain sufficient glucose metabolism necessary for survival and growth. Aim 1 will determine the mechanism by which CDK4/6 inhibition induces PFKFB3 expression. Aim 2 will determine the effects of combined CDK4/6 and PFKFB3 inhibition on glucose metabolism, cell cycle, growth and survival in vitro. Aim 3 will examine the metabolic and growth effects of pharmacological CDK4/6 and PFKFB3 inhibition as monotherapies and in combination in mouse models of breast cancer in vivo. We anticipate that our studies will support the clinical testing of PFKFB3 inhibitors in combination with CDK4/6 inhibitors to increase the survival of advanced ER+ breast cancer patients.