PO.MCB02.01 · 分子与细胞生物学
叶酸受体alpha激活STAT3/LATS1信号轴使乳腺癌细胞抵抗铁死亡
Activation of a STAT3/LATS1 signaling axis by folate receptor alpha enables breast cancer cells to resist ferroptosis
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
癌细胞在进展过程中所遭遇的肿瘤微环境的动态变化可触发铁死亡——一种以铁依赖性细胞膜脂质过氧化为特征的细胞死亡形式。这一现象在转移过程中加剧，因为循环中的肿瘤细胞暴露于基质脱离、氧化应激和高铁浓度的条件下。许多肿瘤细胞能够承受这些条件而存活，提示它们已获得抵抗铁死亡刺激的机制。本研究的目标是鉴定乳腺癌细胞上表达的、促进铁死亡抵抗的特定细胞表面蛋白，因为此类蛋白可作为治疗靶点。为实现这一目标，我们采用无偏方法，分析了从一名乳腺癌患者来源、经铁死亡诱导药物咪唑酮erastin（IKE）处理的类器官中获得的单细胞RNA测序数据（scRNA-seq）。该scRNA-seq的差异基因表达分析揭示，叶酸受体alpha（FRalpha）在铁死亡非应答者群体中显著表达。随后，我们在乳腺癌细胞系（CAL51和T47D）中证明了FRalpha在促进对IKE和基质脱离所诱导铁死亡抵抗中的因果作用。我们验证了FRalpha激活STAT3的能力，并观察到STAT3在我们的模型中驱动铁死亡抵抗。为理解STAT3如何促进铁死亡抵抗，我们鉴定了LATS1——一个磷酸化并使YAP和TAZ失活的Hippo信号关键调控因子。通过染色质免疫沉淀，我们观察到STAT3结合LATS1启动子区域，且抑制STAT3可降低LATS1基因和蛋白表达。我们还发现，STAT3介导的LATS1调控抑制YAP，而YAP已知可促进铁死亡敏感性。为探究STAT3/LATS1抑制YAP如何促成铁死亡抵抗的机制，我们聚焦于YAP调控酰基辅酶A合成酶长链家族成员4（ACSL4）的能力，该酶通过重塑细胞脂质膜触发铁死亡。我们的数据揭示，STAT3和LATS1在抑制YAP介导的ACSL4表达诱导中具有因果作用。总之，这些数据凸显了FRalpha通过一种依赖LATS1的机制促进铁死亡抵抗的新作用。正在进行的研究旨在探究FRalpha和LATS1通过促进铁死亡抵抗增强转移的能力。本研究还提示，FRalpha可能是缓解转移性乳腺癌的有效治疗靶点。
查看英文原文 English abstract
Dynamic changes occurring in the tumor microenvironment that carcinoma cells encounter during their progression can trigger ferroptosis, a form of cell death characterized by the iron-dependent lipid peroxidation of cell membranes. This phenomenon is exacerbated during metastasis as tumor cells in circulation are exposed to conditions of matrix-detachment, oxidative stress and high iron concentration. Many tumor cells withstand these conditions to survive, which suggests they have acquired mechanisms to resist ferroptotic stimuli. Our goal in this study was to identify specific cell surface proteins expressed on breast cancer cells that promote ferroptosis resistance since such proteins can serve as therapeutic targets. To achieve this goal, we used an unbiased approach that involved analysis of single-cell RNA sequencing data (scRNA-seq) that we obtained from an organoid derived from a breast cancer patient that was exposed to a ferroptosis-inducing drug, imidazole ketone erastin (IKE). Differential gene expression analysis of this scRNA seq revealed that folate receptor alpha (FRalpha) is significantly expressed in ferroptosis non-responder populations. Subsequently, we demonstrated a causal role for FRalpha in promoting resistance to ferroptosis induced by both IKE and matrix detachment in breast cancer cell lines (CAL51 and T47D). We verified the ability of FRalpha to activate STAT3 and observed that STAT3 drives ferroptosis resistance in our model. To understand how STAT3 promotes ferroptosis resistance, we identified LATS1, a key regulator of Hippo signaling that phosphorylates and inactivates YAP and TAZ. Using chromatin immunoprecipitation, we observed that STAT3 binds to the LATS1 promoter region and that inhibition of STAT3 reduces LATS1 gene and protein expression. We also found that STAT3-mediated regulation of LATS1 inhibits YAP, which is known to promote ferroptosis sensitivity. To investigate a mechanism for how inhibition of YAP by STAT3/LATS1 contributes to ferroptosis resistance, we focused on the ability of YAP to regulate Acyl-CoA synthetase long-chain family member 4 (ACSL4), an enzyme that triggers ferroptosis by remodeling lipid membranes in cells. Our data revealed that STAT3 and LATS1 have a causal role in inhibiting YAP-mediated induction of ASCL4 expression. Together, these data highlight a novel role for FRalpha in promoting ferroptosis resistance by a mechanism that is dependent on LATS1. Ongoing studies are aimed at investigating the ability of FRalpha and LATS1 to enhance metastasis by promoting ferroptosis resistance. This work also suggests that FRalpha could be an effective therapeutic target for mitigating metastatic breast cancer.
利益披露 Disclosure
P. Ambegaokar, None.