Background/Objectives: Signal Transducer and Activator of Transcription 3 (STAT3) is a transcription factor that is strongly implicated in various cancers. In its canonical signaling pathway, Janus kinases (JAKs) phosphorylate STAT3 at the Y705 residue in response to cytokines or growth factors, with pY705 serving as a key marker of STAT3 oncogenic activity. Elevated pY705 levels correlate with poor prognosis, and numerous small-molecule inhibitors have been developed to block this phosphorylation site. More recently, phosphorylation at the S727 residue (pS727) has emerged as a critical contributor to STAT3-mediated oncogenesis, particularly due to its role in mitochondrial translocation. Evidence suggests that pS727 may even surpass pY705 in driving oncogenic activity. These findings prompt an important question: Which residue should be prioritized for effective STAT3 inhibition in cancer therapy? Methods: This review compiles and critically analyzes the current literature on STAT3 inhibitors targeting pY705 and/or pS727, evaluating their therapeutic efficacy in vitro, in vivo, and in clinical trials. We assess the unique effects of targeting each residue on downstream signaling, toxicity, and clinical outcomes. Results: Our analysis indicates that inhibitors targeting both pY705 and pS727 achieve the greatest therapeutic effectiveness. However, pS727 targeting is associated with higher toxicity risks. Conclusions: Comprehensive evaluation of STAT3 inhibitors underscores the importance of targeting pY705 for maximum therapeutic benefit. The analysis also shows that co-targeting pS727 may increase overall efficacy. However, pS727 inhibition should be approached with lower affinity to minimize toxicity and enhance the clinical feasibility of dual-targeting strategies.
**背景/目的：** 信号转导与转录激活因子3（STAT3）是一种与多种癌症密切相关的转录因子。在其经典信号通路中，Janus激酶（JAKs）响应细胞因子或生长因子，在Y705位点磷酸化STAT3，pY705是STAT3致癌活性的关键标志物。pY705水平升高与不良预后相关，因此已开发出众多小分子抑制剂来阻断该磷酸化位点。最近，S727位点的磷酸化（pS727）已成为STAT3介导的致癌作用的关键因素，特别是因其在线粒体易位中的作用。有证据表明，在驱动致癌活性方面，pS727甚至可能超过pY705。这些发现引出了一个重要问题：在癌症治疗中，为了有效抑制STAT3，应优先靶向哪个残基？ **方法：** 本综述汇总并批判性分析了当前关于靶向pY705和/或pS727的STAT3抑制剂的文献，评估了它们在体外、体内及临床试验中的治疗效果。我们评估了靶向每个残基对下游信号传导、毒性和临床结果的独特影响。 **结果：** 我们的分析表明，同时靶向pY705和pS727的抑制剂能达到最大的治疗效果。然而，靶向pS727与较高的毒性风险相关。 **结论：** 对STAT3抑制剂的全面评估强调了靶向pY705以获得最大治疗益处的重要性。分析还表明，同时靶向pS727可能提高总体疗效。然而，应以较低的亲和力进行pS727抑制，以最大限度地降低毒性，并提高双靶向策略的临床可行性。
Targeting STAT3 for Cancer Therapy: Focusing on Y705, S727, or Dual Inhibition?
肿瘤(癌症)患者之家