Division of Translational Cancer Research, Department of Laboratory Medicine, Lund University, Lund, Sweden.
Clin Epigenetics. 2018 Jun 19;10:83. doi: 10.1186/s13148-018-0516-x. eCollection 2018.
The PI3K/mTOR pathway is the second most frequently deregulated pathway in a majority of cancers such as breast cancer, lung cancer, and melanomas as well as leukemia. Mutations in the genes coding for receptor tyrosine kinases (RTKs) and G-protein-coupled receptors (GPCRs) are quite common in all forms of acute leukemia. This can be a major cause of deregulation of the PI3K-mTOR pathway. To understand how cells display resistance to the dual PI3K/mTOR inhibitor, we used a panel of 25 acute leukemia cell lines. We observed that while a number of cell lines displayed sensitivity to the dual PI3K/mTOR pathway inhibitor PKI-587, many cells displayed substantial resistance. Cells sensitive to PKI-587 also showed aberrant activation of PI3K/mTOR pathway components such as AKT and S6K and also displayed sensitivity to a panel of various other PI3K/mTOR inhibitors. Using RNA sequencing data, we observed that expression of a G protein-coupled receptor, P2RY14, was upregulated nine-fold in cells showing resistance to the PI3K/mTOR inhibitor. P2RY14 has not been much studied in hematologic malignancies. However, this receptor seems to have a role in the localization of hematopoietic stem cells (HSCs) and in promoting regenerative capabilities following injury. We observed that acute lymphoblastic leukemia (ALL) and FLT3-ITD-positive acute myeloid leukemia (AML) patients with higher expression of P2RY14 mRNA displayed relatively poor survival compared to patients carrying lower expression of P2RY14 suggesting a role of P2RY14 in patient survival. To understand the role of this receptor in cell signaling, we used phospho-protein arrays and observed activation of distinct signaling cascades. Furthermore, array data were verified using murine pro-B cell line Ba/F3 stably transfected with P2RY14. We observed that activation of P2RY14 by its ligand, UDP-glucose, resulted in selective induction of ERK1/2 phosphorylation. Taken together, our data suggest that acute leukemia cells resistant to PI3K/mTOR inhibition display upregulation of a GPCR, P2RY14, which has a role in patient survival and also couples to the activation of ERK signaling.
PI3K/mTOR 通路是大多数癌症（如乳腺癌、肺癌和黑色素瘤以及白血病）中第二大常见失调通路。受体酪氨酸激酶 (RTKs) 和 G 蛋白偶联受体 (GPCR) 编码基因的突变在所有形式的急性白血病中都很常见。这可能是 PI3K-mTOR 通路失调的主要原因。为了了解细胞如何对双 PI3K/mTOR 抑制剂产生耐药性，我们使用了 25 种急性白血病细胞系的面板。我们观察到，虽然许多细胞系对双 PI3K/mTOR 通路抑制剂 PKI-587 表现出敏感性，但许多细胞表现出明显的耐药性。对 PKI-587 敏感的细胞也表现出 PI3K/mTOR 通路成分如 AKT 和 S6K 的异常激活，并且对各种其他 PI3K/mTOR 抑制剂也表现出敏感性。使用 RNA 测序数据，我们观察到在对 PI3K/mTOR 抑制剂耐药的细胞中，G 蛋白偶联受体 P2RY14 的表达上调了九倍。P2RY14 在血液恶性肿瘤中研究甚少。然而，该受体似乎在造血干细胞 (HSCs) 的定位和损伤后再生能力的促进中发挥作用。我们观察到，急性淋巴细胞白血病 (ALL) 和 FLT3-ITD 阳性急性髓系白血病 (AML) 患者中 P2RY14 mRNA 表达较高的患者与 P2RY14 表达较低的患者相比，生存相对较差，表明 P2RY14 在患者生存中的作用。为了了解该受体在细胞信号转导中的作用，我们使用磷酸化蛋白阵列观察到不同信号通路的激活。此外，还使用 P2RY14 稳定转染的小鼠原 B 细胞系 Ba/F3 进行了阵列数据验证。我们观察到，其配体 UDP-葡萄糖激活 P2RY14 导致 ERK1/2 磷酸化的选择性诱导。总之，我们的数据表明，对 PI3K/mTOR 抑制有耐药性的急性白血病细胞显示出 GPCR P2RY14 的上调，该受体在患者生存中起作用，并与 ERK 信号的激活偶联。
