*Article* **A Novel Aldisine Derivative Exhibits Potential Antitumor Effects by Targeting JAK/STAT3 Signaling**

**Dong-Ping Wang 1,2,†, Li-Hong Wu 1,3,†, Rui Li 1,3,†, Na He 1,3, Qian-Yue Zhang 1,3, Chen-Yang Zhao 1,4,\* and Tao Jiang 1,2,\***


**Abstract:** The JAK/STAT3 signaling pathway is aberrantly hyperactivated in many cancers, promoting cell proliferation, survival, invasiveness, and metastasis. Thus, inhibitors targeting JAK/STAT3 have enormous potential for cancer treatment. Herein, we modified **aldisine** derivatives by introducing the isothiouronium group, which can improve the antitumor activity of the compounds. We performed a high-throughput screen of 3157 compounds and identified compounds **11a**, **11b**, and **11c**, which contain a pyrrole [2,3-c] azepine structure linked to an isothiouronium group through different lengths of carbon alkyl chains and significantly inhibited JAK/STAT3 activities. Further results showed that compound **11c** exhibited the optimal antiproliferative activity and was a pan-JAKs inhibitor capable of inhibiting constitutive and IL-6-induced STAT3 activation. In addition, compound **11c** influenced STAT3 downstream gene expression (Bcl-xl, C-Myc, and Cyclin D1) and induced the apoptosis of A549 and DU145 cells in a dose-dependent manner. The antitumor effects of **11c** were further demonstrated in an in vivo subcutaneous tumor xenograft experiment with DU145 cells. Taken together, we designed and synthesized a novel small molecule JAKs inhibitor targeting the JAK/STAT3 signaling pathway, which has predicted therapeutic potential for JAK/STAT3 overactivated cancer treatment.

**Keywords:** JAK/STAT3 signaling pathway; aldisine derivatives; isothiouronium; antitumor activity; JAK inhibitor; high-throughput screening
