Potent and selective ferroptosis regulators promote an intensive understanding of the regulation and mechanisms underlying ferroptosis, which is highly associated with various diseases. In this study, through a stepwise structure optimization, a potent and selective ferroptosis inducer was developed targeting to inhibit glutathione peroxidase 4 (GPX4), and the structure–activity relationship (SAR) of these compounds was uncovered. Compound 26a exhibited outstanding GPX4 inhibitory activity with a percent inhibition up to 71.7% at 1.0 μM compared to 45.9% of RSL-3. At the cellular level, 26a could significantly induce lipid peroxide (LPO) increase and effectively induce ferroptosis with satisfactory selectivity (the value of 31.5). The morphological analysis confirmed the ferroptosis induced by 26a. Furthermore, 26a significantly restrained tumor growth in a mouse 4T1 xenograft model without obvious toxicity.
Photodynamic therapy (PDT)-mediated oxidation treatment is extremely attractive for skin melanoma ablation, but the strong hydrophobicity and poor tumor selectivity of photosensitizers, as well as the oxygen-consuming properties of PDT, leading to unsatisfactory therapeutic outcomes. Herein, a tumor acidic microenvironment activatable dissolving microneedle ([email protected]) was developed to realize controlled drug release and excellent chemo-photodynamic therapy of melanoma via oxidative stress amplification. The versatile [email protected] was fabricated by crosslinking a self-synthesized protoporphyrin (PpIX)-ADH-hyaluronic acid (HA) conjugate HA-ADH-PpIX with "iron reservoir" PA-Fe3+ complex in the needle tip via acylhydrazone bond formation, and dihydroartemisinin (DHA) was concurrently loaded in the hydrogel network. HA-ADH-PpIX with improved water solubility averted undesired aggregation of PpIX to ensure enhanced PDT effect. [email protected] with sharp needle tip, efficient drug loading and excellent mechanical strength could efficiently inserted into skin and reach the melanoma sites, where the acidic pH triggered the degradation of microneedles, enabling Fe-activated and DHA-mediated oxidation treatment, as evidenced by abundant reactive oxygen species (ROS) generation. Moreover, under light irradiation, a combined chemo-photodynamic therapeutic effect was achieved with amplified ROS generation. Importantly, the Fe-catalyzed ROS production of DHA was oxygen-independent, which work in synergy with the oxygen-dependent PDT to effectively destroy tumor cells. This versatile microneedles with excellent biosafety and biodegradability can be customized as a promising localized drug delivery system for combined chemo-photodynamic therapy of melanoma.
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