Smoothened as a Novel Signal Stabilization Scaffold in Doxorubicin Resistance

Smoothened作为一种新的“信号稳定支架”在阿霉素耐药中的应用 多柔比星（DXR）是癌症治疗中最广泛使用的疗法之一。但结合 其心脏毒性，由于耐药性而需要更高的剂量是治疗中的主要挑战。弥漫性B- 细胞淋巴瘤（DLBCL）是成人中最常见的淋巴瘤，并且DXR抗性是主要的 成功使用当前基于蒽环类药物的标准治疗（CHOP）的限制因素。增强AKT 已知信号传导与DXR敏感性的丧失相关，并且传统上，直接作用于DXR敏感性的机制 对它的磷酸化/去磷酸化一直是研究的主要焦点。最近，竞争 AKT泛素化模式已成为平衡降解（UB-K48连接）与 膜募集、Ser/Thr磷酸化和活化（UB-K63连接）。膜定位的pAKT是 是最强的致癌信号我们发现TRAF 6，一种（K63）E3-连接酶，负责 调节DLBCL中pAKT的稳定性和功能。此外，我们首次观察到， 依赖于七跨膜受体“Smoothened”（SMO）。SMO局限于筏内 微结构域，募集TRAF 6，启动TRAF 6自动稳定和激活，从而增强TRAF 6的表达。 这是抵抗DXR所需的信号。测绘局的这一新颖角色超出了其典型角色， Hedgehog信号传导，并反映在DXR耐药患者样品中SMO表达升高 DLBCL。异位SMO表达或SMO敲低分别降低或增加DXR敏感性， 淋巴瘤细胞系。在这个建议中，我们将解剖SMO的区域，这是需要这种新的功能 并识别为该筏定位信号稳定功能而组装的相互作用伙伴。在 此外，我们将使用患者来源的异种移植小鼠模型来评估SMO对 化疗耐药性，并评估在当前化疗中添加现有SMO抑制剂的效用 逆转耐药性的方案。

Smoothened as a Novel “Signal Stabilization Scaffold” in Doxorubicin Resistance Doxorubicin (DXR) is among the most widely used therapeutics in cancer treatment. However, combined with its cardiotoxicity, the need for higher dosing due to drug resistance is a major challenge in treatment. Diffuse B- Cell Lymphoma (DLBCL) is the most common lymphoma in adults, and DXR resistance is the predominant limiting factor for the successful use of current anthracycline based standard therapy (CHOP). Enhanced AKT signaling is known to be associated with loss of DXR sensitivity, and traditionally, mechanisms that directly act on its phosphorylation/dephosphorylation have been the main focus of research. More recently, competing AKT ubiquitination modes have emerged as a critical factor that balances degradation (UB-K48 linkage) versus membrane recruitment, Ser/Thr phosphorylation and activation (UB-K63 linkage). Membrane localized pAKT is represents the most potent oncogenic signal. We found that TRAF6, a (K63)E3-ligase, is responsible for regulating pAKT stability and function in DLBCL. Moreover, we observed for the first time that this mechanism is dependent on the seven transmembrane spanning receptor “Smoothened” (SMO). SMO is localized in raft microdomains, recruits TRAF6, initiates TRAF6 auto stabilization and activation, and thereby enhances signaling that is needed for DXR resistance. This novel role of SMO goes beyond its canonical role in Hedgehog signaling and is reflected in elevated SMO expression in samples from patients with DXR resistant DLBCL. Ectopic SMO expression or SMO knockdown decrease or increase DXR sensitivity respectively in lymphoma cell lines. In this proposal, we will dissect the regions of SMO that are needed for this novel function and identify the interaction partners that are assembled for this raft-localized signal stabilization function. In addition, we will use a patient derived xenograft mouse model to evaluate the contribution of SMO to chemoresistance and evaluate the utility of adding existing SMO inhibitors to the current chemotherapy regimens to reverse resistance.