Asymmetric silicon phthalocyanine based nanoparticle with spatiotemporally targeting of mitochondria for synergistic apoptosis-ferroptosis antitumor treatment.

A promising therapeutic strategy in cancer treatment merges photodynamic therapy (PDT) induced apoptosis with ferroptosis, a form of programmed cell death governed by iron-dependent lipid peroxidation. Given the pivotal role of mitochondria in ferroptosis, the development of photosensitizers that specifically provoke mitochondrial dysfunction and consequentially trigger ferroptosis via PDT is of significant interest. To this end, we have designed and synthesized a novel nanoparticle, termed FECTPN, tailored to address this requisite. FECTPN harnesses a trifecta of critical attributes: precision mitochondria targeting, photoactivation capability, pH-responsive drug release, and synergistic apoptosis-ferroptosis antitumor treatment. This nanoparticle was formulated by conjugating an asymmetric silicon phthalocyanine, Chol-SiPc-TPP, with the ferroptosis inducer Erastin onto a ferritin. The Chol-SiPc-TPP is a chemically crafted entity featuring cholesteryl (Chol) and triphenylphosphine (TPP) functionalities bonded axially to the silicon phthalocyanine, enhancing mitochondrial affinity and leading to effective PDT and subsequent apoptosis of cells. Upon cellular uptake, FECTPN preferentially localizes to mitochondria, facilitated by Chol-SiPc-TPP's targeting mechanics. Photoactivation induces the synchronized release of Chol-SiPc-TPP and Erastin in the mitochondria's alkaline domain, driving the escalation of both ROSs and lipid peroxidation. These processes culminate in elevated antitumor activity compared to the singular application of Chol-SiPc-TPP-mediated PDT. A notable observation is the pronounced enhancement in glutathione peroxidase-4 (GPX4) expression within MCF-7 cells treated with FECTPN and subjected to light exposure, reflecting intensified oxidative stress. This study offers compelling evidence that FECTPN can effectively induce ferroptosis and reinforces the paradigm of a synergistic apoptosis-ferroptosis pathway in cancer therapy, proposing a novel route for augmented antitumor treatments.