Battling Drug Resistance of Tumors using novel SHP2 Inhibitors

非受体酪氨酸磷酸酶SHP2（由PTPN 11编码）已涉及酪氨酸激酶受体的信号传导，并诱导细胞中的生理和病理生理过程。最近对小鼠的遗传分析表明，SHP 2在各种器官的发育和维持中发挥作用。在人类中，PTPN11的生殖系和体细胞突变与努南综合征和豹综合征以及许多恶性肿瘤相关。SHP 2在70%的浸润性乳腺癌中上调，shRNA干扰抑制异种移植模型中的肿瘤生长和癌症干细胞。因此，SHP 2是肿瘤治疗中一个有吸引力的靶点，因此，鉴定小分子SHP 2抑制剂对于治疗目的具有巨大的需求。然而，没有SHP 2抑制剂已经达到临床试验的后期阶段。我们的实验室已经鉴定并表征了活性位点SHP 2抑制剂GS 493。我们已经证明，GS493与MEK抑制剂组合可以阻断小鼠内源性KRAS突变型肿瘤的生长，并防止BRAF突变型结肠癌和黑色素瘤细胞中RTK介导的对BRAF抑制剂维罗非尼的耐药性。最近，其他人已经开发了新的SHP 2抑制剂，其通过变构机制起作用，并保持SHP 2处于封闭的自抑制构象。然而，越来越多的证据表明，与活性位点抑制剂相比，根据突变和活化状态，变构抑制剂的有效性较低。近一半的SHP 2突变型癌症患者携带强激活突变，在这些突变型肿瘤中成功抑制SHP 2活性可能难以在临床环境中使用变构抑制剂实现。 在随后的化学优化研究中，我们计划改善我们支架的结构特征，并将其转化为药物样先导分子。我们将（i）通过药物化学方法和生物化学研究开发和表征新型高活性、选择性、细胞渗透性和代谢稳定的SHP 2抑制剂，（ii）设计有效的不可逆SHP 2抑制剂，其发挥延长的停留时间并耐受SHP 2的强烈激活突变，（iii）分析SHP 2在癌细胞系中的急性扰动的影响，患者来源的类器官和小鼠模型，并机械地剖析可逆和不可逆活性位点抑制与MEK抑制组合对KRAS突变型肿瘤的耐药性的作用，（iv）分析SHP 2的组合活性位点和变构抑制在预防肿瘤耐药性中的协同作用，最后，（V）建立SHP 2的组合催化和变构位点抑制作为治疗KRAS驱动的肿瘤的新治疗方法。这些研究将对SHP 2在介导癌症耐药性中的细胞作用产生新的见解，并具有很高的潜力被转化为肿瘤学新疗法的开发。

The non-receptor tyrosine phosphatase SHP2 (encoded by PTPN11) has been implicated in signaling of tyrosine kinase receptors, and to induce physiological and pathophysiological processes in cells. Recent genetic analyses in mice showed that SHP2 functions in the development and maintenance of various organs. In humans, germline and somatic mutations of PTPN11 are associated with Noonan and Leopard syndromes, as well as with a number of malignancies. SHP2 is upregulated in 70% of invasive breast cancers, and shRNA interference inhibited tumor growth and cancer stem cells in xenograft models. Therefore, SHP2 is an attractive target in cancer therapy.And so, the identification of small molecule SHP2 inhibitors is in great demand for therapeutic purposes. However, no SHP2 inhibitor has yet reached advanced stages of clinical trials. Our laboratories have identified and characterized the active site SHP2 inhibitor GS493. We have shown that GS493 in combination with MEK inhibitors can block the growth of endogenous KRAS-mutant tumors in mice and prevent RTK-mediated resistance to BRAF inhibitor vemurafenib in BRAF-mutant colon cancer and melanoma cells. Recently, others have developed new inhibitors of SHP2 that act by an allosteric mechanism, and keep SHP2 in a closed, auto-inhibitory conformation. However, accumulating evidence suggests that compared to active site inhibitors, depending on the mutational and activation state, the allosteric inhibitors are less efficacious. Nearly half of patients with SHP2-mutated cancers bear strongly activating mutations and successful suppression of SHP2 activity in these mutated tumors may be difficult to achieve with allosteric inhibitors in clinical settings. In subsequent chemical optimization studies, we plan to improve the structural features of our scaffold and convert it into a drug-like lead molecule. We will (i) develop and characterize novel highly active, selective, cell-permeable and metabolically stable inhibitors of SHP2 by medicinal chemistry approaches and biochemical studies, (ii) design potent irreversible SHP2 inhibitors that exert a prolonged residence time and withstand strongly activating mutations of SHP2, (iii) analyze the effect of acute perturbation of SHP2 in cancer cell lines, patient-derived organoids and mouse models, and to mechanistically dissect the role of reversible and irreversible active site inhibition in combination with MEK inhibition on the drug resistance of KRAS-mutant tumors, (iv) analyze the synergistic effect of combined active site and allosteric inhibition of SHP2 in preventing drug resistance of tumors, and finally, (v) establish the combined catalytic and allosteric site inhibition of SHP2 as a new therapeutic approach to treat KRAS-driven tumors. These studies will yield novel insights into the cellular role of SHP2 in mediating drug resistance in cancer and have a high potential of being translated into the development of novel therapies in oncology.