The practical application of nanoparticles (NPs) as chemotherapeutic drug delivery systems is often hampered by issues such as poor circulation stability and targeting inefficiency. Here, we have utilized a simple approach to prepare biocompatible and biodegradable pH-responsive hybrid NPs that overcome these issues. The NPs consist of a drug-loaded polylactic-co-glycolic acid (PLGA) core covalently ‘wrapped’ with a crosslinked bovine serum albumin (BSA) shell designed to minimize interactions with serum proteins and macrophages that inhibit target recognition. The shell is functionalized with the acidity-triggered rational membrane (ATRAM) peptide to facilitate internalization specifically into cancer cells within the acidic tumor microenvironment. Following uptake, the unique intracellular conditions of cancer cells degrade the NPs, thereby releasing the chemotherapeutic cargo. The drug-loaded NPs showed potent anticancer activity in vitro and in vivo while exhibiting no toxicity to healthy tissue. Our results demonstrate that the ATRAM-BSA-PLGA NPs are a promising targeted cancer drug delivery platform.

Missense mutations in p53 are severely deleterious and occur in over 50% of all human cancers. The majority of these mutations are located in the inherently unstable DNA-binding domain (DBD), many of which destabilize the domain further and expose its aggregation-prone hydrophobic core, prompting self-assembly of mutant p53 into inactive cytosolic amyloid-like aggregates. Screening an oligopyridylamide library, previously shown to inhibit amyloid formation associated with Alzheimer’s disease and type II diabetes, identified a tripyridylamide, ADH-6, that abrogates self-assembly of the aggregation-nucleating subdomain of mutant p53 DBD. Moreover, ADH-6 targets and dissociates mutant p53 aggregates in human cancer cells, which restores p53’s transcriptional activity, leading to cell cycle arrest and apoptosis. Notably, ADH-6 treatment effectively shrinks xenografts harboring mutant p53, while exhibiting no toxicity to healthy tissue, thereby substantially prolonging survival. This study demonstrates the successful application of a bona fide small-molecule amyloid inhibitor as a potent anticancer agent.

Photodynamic therapy (PDT) and photothermal therapy (PTT) have gained considerable attention as potential alternatives to conventional cancer treatments. However, these approaches remain limited by low solubility, poor stability, and inefficient targeting of many common photosensitizers (PSs) and photothermal agents (PTAs). To overcome the aforementioned limitations, we engineered biocompatible and biodegradable tumor-targeted upconversion nanospheres with imaging capabilities. The multifunctional nanospheres consist of a sodium yttrium fluoride core doped with lanthanides (ytterbium, erbium, and gadolinium) and the PTA bismuth selenide (NaYF₄:Yb/Er/Gd,Bi₂Se₃) enveloped in a mesoporous silica shell that encapsulates a PS, chlorin e6 (Ce6), within its pores. NaYF₄:Yb/Er converts deeply penetrating near-infrared (NIR) light to visible light, which excites Ce6 to generate cytotoxic reactive oxygen species (ROS), while Bi₂Se₃ efficiently converts absorbed NIR light to heat. Additionally, Gd enables magnetic resonance imaging of the nanospheres. The mesoporous silica shell is coated with DPPC/cholesterol/DSPE-PEG to retain the encapsulated Ce6 and prevent serum protein adsorption and macrophage recognition that hinder tumor targeting. Finally, the coat is conjugated to the acidity-triggered rational membrane (ATRAM) peptide, which promotes specific and efficient internalization into malignant cells in the mildly acidic microenvironment of tumors. The nanospheres facilitated tumor magnetic resonance and thermal and fluorescence imaging and exhibited potent NIR laser light-induced anticancer effects in vitro and in vivo via combined ROS production and localized hyperthermia, with negligible toxicity to healthy tissue, hence markedly extending survival. Our results demonstrate that the ATRAM-functionalized, lipid/PEG-coated upconversion mesoporous silica nanospheres (ALUMSNs) offer multimodal diagnostic imaging and targeted combinatorial cancer therapy.

Overexpression of mitochondria‐bound hexokinase II (HKII) in cancer cells plays an important role in their metabolic reprogramming and protects them against apoptosis, thereby facilitating their growth and proliferation. Here, we show that covalently coupling a peptide corresponding to the mitochondrial membrane – binding N‐terminal 15 aa of HKII (pHK) to a short, penetration‐accelerating sequence (PAS) enhances the cellular uptake, mitochondrial localization, and cytotoxicity of the peptide in HeLa cells. Further analysis revealed that pHK‐PAS depolarized mitochondrial membrane potential, inhibited mitochondrial respiration and glycolysis, and depleted intracellular ATP levels. The effects of pHK‐PAS were correlated with dissociation of endogenous full‐length HKII from mitochondria and release of cytochrome c . Of significance, pHK‐PAS treatment of noncancerous HEK293 cells resulted in substantially lower cytotoxicity. Thus, pHK‐PAS effectively disrupted the mitochondria‐HKII association in cancer cells, which led to mitochondrial dysfunction and, finally, apoptosis. Our results demonstrate the potential of the pHK‐PAS cell‐penetrating peptide as a novel therapeutic strategy in cancer. —Woldetsadik, A. D., Vogel, M. C., Rabeh, W. M., Magzoub, M. Hexokinase II–derived cell‐penetrating peptide targets mitochondria and triggers apoptosis in cancer cells. FASEB J. 31, 2168–2184 (2017). www.fasebj.org