Synthesis and biological evaluation of novel isoxazoloquinone derivatives as potent STAT3-targeting antipsoriasis agents.

Psoriasis is a troublesome scaling skin disease with no high-effective medication available by far. Signal transducer and activator of transcription 3 (STAT3) has recently been revealed as a crucial player in the pathogenesis and progression of psoriasis and emerged as an intriguing antipsoriatic drug target. Naturally occurring lapachol and its quinone analogs had been discovered as effective STAT3 inhibitors, however, their antipsoriatic effects are not well investigated. Previously, we have reported a series of isothiazoloquinone lapachol derivatives. Here, the antipsoriastic potentials of these isothiazoloquinones were investigated and, in addition, 35 novel isoxazoloquinone derivatives were prepared and studied for their anti-psoriasis properties. Among them, the most potent antipsoriatic compound B20 determined by in vitro test on HaCaT cells could directly bind to STAT3, reduce STAT3 level and inhibit STAT3 nuclear translocation. In vivo studies showed that topical application of B20 could effectively alleviate IMQ-induced psoriasis in mice with no obvious side effects. In addition, B20 inhibited the production of interleukin 17 (IL-17A), a STAT3-downstream cytokine essential for the progression of psoriasis, both in vitro and in vivo. Thus, isoxazoloquinone B20 is a potent STAT3-targeting antipsoriatic agent worth of further investigation.

An Isoxazoloquinone Derivative Inhibits Tumor Growth by Targeting STAT3 and Triggering Its Ubiquitin-Dependent Degradation.

BACKGROUND: Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype, with shorter five-year survival than other breast cancer subtypes, and lacks targeted and hormonal treatment strategies. The signal transducer and activator of transcription 3 (STAT3) signaling is up-regulated in various tumors, including TNBC, and plays a vital role in regulating the expression of multiple proliferation- and apoptosis-related genes. RESULTS: By combining the unique structures of the natural compounds STA-21 and Aulosirazole with antitumor activities, we synthesized a class of novel isoxazoloquinone derivatives and showed that one of these compounds, ZSW, binds to the SH2 domain of STAT3, leading to decreased STAT3 expression and activation in TNBC cells. Furthermore, ZSW promotes STAT3 ubiquitination, inhibits the proliferation of TNBC cells in vitro, and attenuates tumor growth with manageable toxicities in vivo. ZSW also decreases the mammosphere formation of breast cancer stem cells (BCSCs) by inhibiting STAT3. CONCLUSIONS: We conclude that the novel isoxazoloquinone ZSW may be developed as a cancer therapeutic because it targets STAT3, thereby inhibiting the stemness of cancer cells.