Investigate the role of TPD52-AMPK pathway in tumorigenesis and cancer therapy

 描述(申请人提供)：乳腺癌是女性最常见的癌症，也是导致癌症死亡的第二大原因。更好地了解乳腺癌的病因将有助于我们更好地预防和治疗这种疾病。Lbk1-AMPK通路是能量代谢的中心调节器，该通路的错误调节与包括乳腺癌在内的癌症有关。二甲双胍等间接AMPK激动剂在乳腺癌的预防和治疗中显示出良好的效果。然而，除了LKB1突变之外，这一途径在乳腺癌中如何可能受到错误调控仍不清楚。在这项应用中，基于我们广泛的初步数据，我们建议根据新发现的在AMPK调节以及反过来对乳腺癌和治疗反应的作用来表征几个因子。第一个因子被称为肿瘤抑制蛋白52(TPD52)，我们发现它可以负向调节AMPK。已知TPD52在HER2+乳腺癌中过表达，并与HER2一起促进肿瘤生长。AMPK通路也被认为与抗HER2反应有关。此外，我们还发现AMPK对USP10有调节作用。USP10可以增强两个重要的肿瘤抑制因子P53和SIRT6的稳定性，因此我们的发现建立了一条新的AMPK下游途径。据报道，SIRT6还可以激活AMPK。因此，我们确定了一个新的AMPK调节轴，TPD52与AMPK下游因子一起负向调节AMPK，UPS10/SIRT6形成正反馈环，进一步激活AMPK，所有这些都将在能量代谢和对二甲双胍诱导的代谢应激反应中发挥重要作用。二甲双胍的反应是不同的；因此，我们的发现可能有助于阐明潜在的机制。我们的初步数据表明，TPD52过表达的细胞对二甲双胍以及二甲双胍+HER2联合抑制剂更敏感。这与之前的研究一致，该研究表明二甲双胍可以抑制HER2+乳腺癌患者的细胞增殖和提高患者存活率。基于这些初步发现，我们假设AMPK-USP10轴参与了AMPK的代谢功能；TPD52通过负调控AMPK，可以促进能量代谢的失调，从而促进乳腺癌的发生。像二甲双胍这样的药物对TPD52过度表达的患者会更有效，并可能与HER2+癌症的HER2抑制剂联合使用。因此，在这一应用中，我们建议确定TPD52如何调节AMPK通路，AMPK如何通过调节USP10来调节SIRT6和P53，以及这种调节对使用细胞系、乳腺肿瘤样本和乳腺癌患者来源的异种移植瘤对双胍和抗HER2治疗的反应的影响。总之，这些研究将帮助我们了解这个新的轴TPD52-AMPK-USP10-SIRT6/P53如何在肿瘤发生和治疗反应中发挥作用。

 DESCRIPTION (provided by applicant): Breast cancer is the most common cancer and the second leading cause of cancer death in women. A better understanding of breast cancer etiology would help us to better prevent and treat this disease. The LBK1-AMPK pathway is a central regulator of energy metabolism, and misregulation of this pathway has been implicated in cancers, including breast cancer. Indirect AMPK activators such as metformin have shown beneficial effect in breast cancer prevention and treatment. However, other than LKB1 mutations, how this pathway might be misregulated in breast cancer remains unclear. In this application, based on our extensive Preliminary Data, we propose to characterize several factors based on their newly identified roles in AMPK regulation and in turn, on breast cancer and treatment response. The first factor is called tumor suppressor protein 52 (TPD52) which we found to negatively regulate AMPK. TPD52 is known to overexpress in HER2+ breast cancer and, together with HER2, to promote tumor growth. The AMPK pathway is also known to be involved in anti-HER2 response. Furthermore, we found that AMPK regulates USP10. USP10 can enhance the stability of two important tumor suppressors, p53 and SIRT6, so our finding has established a new downstream pathway to AMPK. It is reported that SIRT6 can also activate AMPK. Therefore, we have identified a new axis of AMPK regulation with TPD52 negatively regulating AMPK with the AMPK downstream factors, UPS10/SIRT6 forming a positive feedback loop, further activating AMPK, all of which would be important in energy metabolism and response to metabolic stress induced by metformin. Metformin response is heterogeneous; therefore our findings could shed light on the underlying mechanisms. Our preliminary data indicated that cells with TPD52 overexpression were more sensitive to metformin as well as combined metformin+HER2 inhibitors. This is consistent with previous studies indicating that metformin can inhibit cell proliferation and increase patient survival in HER2+ breast cancer. Based on these preliminary findings, we hypothesize that the AMPK-USP10 axis contributes to the metabolic function of AMPK; TPD52, by negatively regulating AMPK, can promote misregulation of energy metabolism and contribute to breast cancer development. Drugs like metformin would be more effective in patients with TPD52 overexpression and might be used in combination with HER2 inhibitors in HER2+ cancers. Therefore, in this application, we propose to determine how TPD52 regulates the AMPK pathway and how AMPK might regulate SIRT6 and p53 through the regulation of USP10 as well as the impact of this regulation on response to biguanides and anti-HER2 therapy using cell lines, breast tumor samples, and breast cancer patient derived xenografts. In summary, these studies would help us to understand how this new axis TPD52-AMPK-USP10-SIRT6/p53 contributes to tumorigenesis and treatment response.