NIR Light-Mediated Mitochondrial RNA Modification for Cancer RNA Interference Therapeutics

Triphenylphosphine-bonded coumaranone dyes realize dual color imaging of mitochondria and nucleoli

Probing intracellular organelles with fluorescent dyes offers opportunities to understand the structures and functions of these cellular compartments, which is attracting increasing interests. Normally, the design principle varies for different organelle targets as they possess distinct structural and functional profiles against each other. Therefore, developing a probe with dual intracellular targets is of great challenge. In this work, a new sort of donor-π-bridge-acceptor (D-π-A) type coumaranone dyes (CMO-1/2/3/4) have been prepared. Four fluorescent probes (TPP@CMO-1/2/3/4) were then synthesized by linking these coumaranone dyes with an amphiphilic cation triphenylphosphonium (TPP). Interestingly, both TPP@CMO-1 and TPP@CMO-2 exhibited dual color emission upon targeting to two different organelles, respectively. The green emission is well localized in mitochondria, while, the red emission realizes nucleoli imaging. RNA is the target of TPP@CMOs, which was confirmed by spectroscopic analysis and computational calculation. More importantly, the number and morphology changes of nucleoli under drug stress have been successfully evaluated using TPP@CMO-1.

Stimulus-Responsive Nanodelivery and Release Systems for Cancer Gene Therapy: Efficacy Improvement Strategies

Introduction of exogenous genes into target cells to overcome various tumor diseases caused by genetic defects or abnormalities and gene therapy, a new treatment method, provides a promising strategy for tumor treatment. Over the past decade, gene therapy has made exciting progress; however, it still faces the challenge of low nucleic acid delivery and release efficiencies. The emergence of nonviral vectors, primarily nanodelivery and release systems (NDRS), has resulted in a historic breakthrough in the application of gene therapy. NDRS, especially stimulus-responsive NDRS that can respond in a timely manner to changes in the internal and external microenvironment (eg, low pH, high concentration of glutathione/reactive oxygen species, overexpressed enzymes, temperature, light, ultrasound, and magnetic field), has shown excellent loading and release advantages in the precision and efficiency of tumor gene therapy and has been widely applied. The only disadvantage is that poor transfection efficiency limits the in-depth application of gene therapy in clinical practice, owing to the presence of biological barriers in the body. Therefore, this review first introduces the development history of gene therapy, the current obstacles faced by gene delivery, strategies to overcome these obstacles, and conventional vectors, and then focuses on the latest research progress in various stimulus-responsive NDRS for improving gene delivery efficiency. Finally, the future challenges and prospects that stimulus-responsive NDRS may face in clinical application and transformation are discussed to provide references for enhancing in-depth research on tumor gene therapy.

Ultrasound-augmented enzyodynamic-Ca2+ overload synergetic tumor nanotherapy

The excessive intracellular Ca2+ can induce oxidative stress, mitochondrial damage and cell apoptosis, which has been extensively explored for tumor therapy. However, the low Ca2+ accumulation originated from Ca2+-based nanosystems substantially weakens the therapeutic effect. Herein, a functional plant polyphenol-appended enzyodynamic nanozyme system CaFe2O4@BSA-curcumin (abbreviation as CFO-CUR) has been rationally designed and engineered to achieve magnified Ca2+ accumulation process, deleterious reactive oxygen species (ROS) production, as well as mitochondrial dysfunction through enzyodynamic-Ca2+ overload synergistic effect. The exogenous Ca2+ released by CaFe2O4 nanozymes under the weakly acidic tumor microenvironment and Ca2+ efflux inhibition by curcumin boost mitochondria-dominant antineoplastic efficiency. The presence of Fe components with multivalent characteristic depletes endogenous glutathione and outputs the incremental ROS due to the oxidase-, peroxidase-, glutathione peroxidase-mimicking activities. The ROS burst-triggered regulation of Ca2+ channels and pumps strengthens the intracellular Ca2+ accumulation. Especially, the exogenous ultrasound stimulation further amplifies mitochondrial damage. Both in vitro and in vivo experimental results affirm the ultrasound-augmented enzyodynamic-Ca2+ overload synergetic tumor inhibition outcomes. This study highlights the role of ultrasound coupled with functional nanozyme in the homeostasis imbalance and function disorder of mitochondria for highly efficient tumor treatment.

Recent Advances in RNA-Targeted Cancer Therapy

Ribonucleic acid (RNA) plays a pivotal role in gene regulation and protein biosynthesis. Interfering the physiological function of key RNAs to induce cell apoptosis holds great promise for cancer treatment. Many RNA-targeted anti-cancer strategies have emerged continuously. Among them, RNA interference (RNAi) has been recognized as a promising therapeutic modality for various disease treatments. Nevertheless, the primary obstacle in siRNA delivery-escaping the endosome and crossing the plasma membrane severely impedes its therapeutic potential. Thus far, a variety of nanosystems as well as carrier-free bioconjugation for siRNA delivery have been developed and employed to enhance the drug delivery and anti-tumor efficiency. Besides, the use of small molecules to target specific RNA structures and disrupt their function, along with the covalent modification of RNA, has also drawn tremendous attention recently owing to high therapeutic efficacy. In this review, we will provide an overview of recent progress in RNA-targeted cancer therapy including various siRNA delivery strategies, RNA-targeting small molecules, and newly emerged covalent RNA modification. Finally, challenges and future perspectives faced in this research field will be discussed.

β-Galactosidase-Activated and Red Light-Induced RNA Modification Strategy for Prolonged NIR Fluorescence/PET Bimodality Imaging

Improving the retention of small-molecule-based therapeutic agents in tumors is crucial to achieve precise diagnosis and effective therapy of cancer. Herein, we propose a β-galactosidase (β-Gal)-activated and red light-induced RNA modification (GALIRM) strategy for prolonged tumor imaging. A β-Gal-activatable near-infrared (NIR) fluorescence (FL) and positron emission tomography (PET) bimodal probe 68Ga-NOTA-FCG consists of a triaaza triacetic acid chelator NOTA for 68Ga-labeling, a β-Gal-activated photosensitizer CyGal, and a singlet oxygen (1O2)-susceptible furan group for RNA modification. Studies have demonstrated that the probe emits an activated NIR FL signal upon cleavage by endogenous β-Gal overexpressed in the lysosomes, which is combined with the PET imaging signal of 68Ga allowing for highly sensitive imaging of ovarian cancer. Moreover, the capability of 68Ga-NOTA-FCG generating 1O2 under 690 nm illumination could be simultaneously unlocked, which can trigger the covalent cross-linking between furan and nucleotides of cytoplasmic RNAs. The formation of the probe-RNA conjugate can effectively prevent exocytosis and prolong retention of the probe in tumors. We thus believe that this GALIRM strategy may provide entirely new insights into long-term tumor imaging and efficient tumor treatment.

ανβ3 integrin-targeted ICG-derived probes for imaging-guided surgery and photothermal therapy of oral cancer

Indocyanine green (ICG), as the only Federal Drug Administration (FDA) approved fluorescence imaging agent, has been widely applied in clinics for near-infrared (NIR) fluorescence imaging-guided surgery and photothermal therapy of cancers. However, its lack of target specificity and poor photo and photothermal stabilities seriously restrict its wide application in clinical practice. Herein, we developed ICG-derived NIR fluorescent probes consisting of a cypate fluorophore and one or two cyclic-(arginine-glycine-aspartic acid) (cRGD) peptides that can specifically target αvβ3 integrin for accurate diagnosis and therapy of oral tumors. Probe Cy-2RGD has been demonstrated to possess bright NIR emission, great tumor targeting capability and a photothermal effect. Moreover, it could be successfully used for effective imaging-guided surgical resection as well as photothermal therapy of oral tumors. This work could provide a valuable tool for sensitive detection and accurate treatment of malignant tumors.