Preparation, Characterization, and Antitumor Activities of Miriplatin-Loaded Liposomes

Lipid core-shell nanoparticles co-deliver FOLFOX regimen and siPD-L1 for synergistic targeted cancer treatment

FOLFOX regimen, composed of folinic acid, 5-fluorouracil (5-FU) and oxaliplatin (OXP), has been used as clinical standard therapeutic regimen in treatments of colorectal cancer (CRC) and esophageal squamous cell carcinoma (ESCC). To further improve its therapeutic outcomes, FOLFOX was combined with anti-PD-1 antibody to form an advanced chemo-immune combination strategy, which has been proven more efficient in controlling cancer progression and prolonging patients' survival in various clinical trials. However, bad tumor accumulation, relative high toxicity, numerous treatment cycles with high fees and low compliance as well as drug resistance seriously limit the prognosis of FOLFOX regimen. The "all-in-one" formulations, which could precisely delivery multidrug regimen into tumor sites and cells, showed a promising application prospect for targeted drug delivery as well as reducing side effects. However, the design and preparation of the "all-in-one" formulation with high drug encapsulation efficiencies for all drugs was still challenging. Herein, a lipid core-shell nanoparticle codelivery platform was designed for simultaneous encapsulation of variant FOLFOX composed of miriplatin (MiPt), 5-Fluoro-2'-deoxyuridine 5'-monophosphate (FdUMP), calcium folinate (CF) and PD-L1 siRNA (siPD-L1) with high efficiencies, and their synergistic anti-tumor mechanisms were studied, respectively. MiPt, a precursor of OXP, was validated capable of inducing efficient immunogenic cell death (ICD) in this work. Additionally, ICD-mediated release of damage associated molecular patterns functionalized synergistically with PD-L1 silence by siPD-L1 to overcome chemoresistance, reverse suppressive tumor microenvironment and recruit more CD8+ T cells. FdUMP, as the intracellular active form of 5-FU, could induce large amounts of reactive oxygen species to enhance the ICD. CF worked as the sensitizer of FdUMP. The enhanced long-term anti-tumor effect of the prepared "all-in-one" formulation compared to free drug regimen and other controls, was verified in heterotopic CRC mice models and ESCC mice models, providing new thoughts for researchers and showing a promising prospect of translation into clinical applications.

Miriplatin-loaded liposome, as a novel mitophagy inducer, suppresses pancreatic cancer proliferation through blocking POLG and TFAM-mediated mtDNA replication

Pancreatic cancer is a more aggressive and refractory malignancy. Resistance and toxicity limit drug efficacy. Herein, we report a lower toxic and higher effective miriplatin (MPt)-loaded liposome, LMPt, exhibiting totally different anti-cancer mechanism from previously reported platinum agents. Both in gemcitabine (GEM)-resistant/sensitive (GEM-R/S) pancreatic cancer cells, LMPt exhibits prominent anti-cancer activity, led by faster cellular entry-induced larger accumulation of MPt. The level of caveolin-1 (Cav-1) determines entry rate and switch of entry pathways of LMPt, indicating a novel role of Cav-1 in nanoparticle entry. After endosome-lysosome processing, in unchanged metabolite, MPt is released and targets mitochondria to enhance binding of mitochondria protease LONP1 with POLG and TFAM, to degrade POLG and TFAM. Then, via PINK1-Parkin axis, mitophagy is induced by POLG and TFAM degradation-initiated mitochondrial DNA (mtDNA) replication blocking. Additionally, POLG and TFAM are identified as novel prognostic markers of pancreatic cancer, and mtDNA replication-induced mitophagy blocking mediates their pro-cancer activity. Our findings reveal that the target of this liposomal platinum agent is mitochondria but not DNA (target of most platinum agents), and totally distinct mechanism of MPt and other formulations of MPt. Self-assembly offers LMPt special efficacy and mechanisms. Prominent action and characteristic mechanism make LMPt a promising cancer candidate.

Enhanced binding of β-catenin and β-TrCP mediates LMPt's anti-CSCs activity in colorectal cancer

Cancer stem cells (CSCs), a subpopulation of tumor cells with the features of self-renewal, tumor initiation, and insensitivity to common physical and chemical agents, are the key to cancer relapses, metastasis, and resistance. Accessible CSCs inhibitory strategies are primarily based on small molecule drugs, yet toxicity limits their application. Here, we report a liposome loaded with low toxicity and high effectiveness of miriplatin, lipo-miriplatin (LMPt) with high miriplatin loading, and robust stability, exhibiting a superior inhibitory effect on CSCs and non-CSCs. LMPt predominantly inhibits the survival of oxaliplatin-resistant (OXA-resistant) cells composed of CSCs. Furthermore, LMPt directly blocks stemness features of self-renewal, tumor initiation, unlimited proliferation, metastasis, and insensitivity. In mechanistic exploration, RNA sequencing (RNA-seq) revealed that LMPt downregulates the levels of pro-stemness proteins and that the β-catenin-mediated stemness pathway is enriched. Further research shows that either in adherent cells or 3D-spheres, the β-catenin-OCT4/NANOG axis, the vital pathway to maintain stemness, is depressed by LMPt. The consecutive activation of the β-catenin pathway induced by mutant β-catenin (S33Y) and OCT4/NANOG overexpression restores LMPt's anti-CSCs effect, elucidating the key role of the β-catenin-OCT4/NANOG axis. Further studies revealed that the strengthened binding of β-catenin and β-TrCP initiates ubiquitination and degradation of β-catenin induced by LMPt. In addition,the Apc^Min/+transgenicmouse model, in which colon tumors are spontaneously formed, demonstrates LMPt's potent anti-non-CSCs activity in vivo.

Promoted antitumor therapy on pancreatic cancer by a novel recombinant human albumin-bound miriplatin nanoparticle

Pancreatic cancer is an aggressive and highly lethal disease with a very poor prognosis. Our previous study found miriplatin can inhibit proliferation of various tumor cells, including pancreatic cancer cells. For the chemotherapy of pancreatic cancer, a novel recombinant human serum albumin (rHSA)-bound miriplatin nanoparticles (rHSA-miPt) were constructed by emulsion-diffusion evaporation method. The optimal formulation was composed of 150 mg of rHSA and 30 mg of miriplatin. The key parameters in rHSA-miPt production were 10 min of high-pressure homogenization in a solution with volume ratio of 10:2 of 5% glucose and chloroform. The rHSA-miPt was characterized with a particle size of 61 ± 10 nm, a zeta potential value of -18 ± 5 mV, encapsulation efficiency of 98.4%, drug loading of 16.4%, T_1/2 of 13.3 h and V_d of 0.5 L in Sprague Dawley rats. The concentrations of platinum (Pt) in the tumors were 15 and 22-fold higher than those in the blood at 24 and 72 h in tumor-bearing mice, respectively. The internalization of rHSA-miPt through caveolae-dependent pathway. In vitro, the half-maximal inhibitory concentration (IC₅₀) of rHSA-miPt was 12.7 μM vs more than 100 μM of gemcitabine (Gem). The inhibition rate of tumor growth was 76% of rHSA-miPt and 51% of Gem, respectively. Compared with Gem, rHSA-miPt was identified to be safer and less toxic based on body weight loss in mice (0% vs 20%), the survival rate of mice (100% vs 80%) and hematological and biochemical parameters of the mice including leukocytes, lymphocytes, neutrophils, monocytes, serum alanine aminotransferase and aspartate aminotransferase. The present study revealed that rHSA-miPt might be a promising candidate for pancreatic cancer therapy.

Chelating Phosphine-N-Heterocyclic Carbene Platinum Complexes via Catalytic Asymmetric Hydrophosphination and Their Cytotoxicity Toward MKN74 and MCF7 Cancer Cell Lines

A series of activated vinyl azoles was hydrophosphinated in the presence of a chiral palladacycle catalyst under mild conditions to give enantioenriched phosphine azoles with moderate enantioselectivities and yields. The racemic phosphine azoles were transformed into eleven novel chelating phosphine-N-heterocyclic carbene (NHC) platinum complexes. The drug efficacies of nine selected phosphine-NHC platinum(II) chlorides in two cancer cell lines (MKN74 and MCF7) were evaluated, and two were found to exhibit activities comparable to that of cisplatin.

Nanoparticle Delivery of CD147 Antagonistic Peptide-9 Protects against Acute Ischemic Brain Injury and tPA-Induced Intracerebral Hemorrhage in Mice

CD147 has emerged as a potential therapeutic target in many human diseases. We have demonstrated that inhibition of CD147 using its function-blocking antibody ameliorates acute ischemic brain injury and promotes long-term functional recovery in mice. Recently, peptide-nanoparticle conjugates have emerged as powerful tools for biomedical applications. The present study aimed to investigate the therapeutic potential of CD147 antagonist peptide-9 (AP9) in acute ischemic stroke in mice using nanomaterial as the drug delivery vehicles. AP9-conjugated nanoparticles (APN), with an average size of about 40 nm, were fabricated by maleimide linkage and characterized using dynamic light scattering and transmission electron microscopy. We found that APN specifically bound to CD147 in cultured mouse brain endothelial cells (bEnd.3) and to ischemia-induced CD147 in mouse cerebral microvessels. Using a mouse model of transient middle cerebral artery occlusion (tMCAO), we demonstrated, for the first time, that systemic delivery of APN (2.5 mg/kg, I.V.) initiated at 1 h after tMCAO significantly reduced brain infarct size, improved functional outcome, and attenuated delayed (5 h after tMCAO) tPA-induced intracerebral hemorrhage in acute ischemic stroke. These protective effects were associated with profound inhibition of MMP-9 and MMP-3 in both ischemic brain and plasma. In conclusion, the CD147 antagonist peptide-9 represents a potentially promising therapeutic candidate for the treatment of ischemic stroke.

Cisplatin-Membrane Interactions and Their Influence on Platinum Complexes Activity and Toxicity

Cisplatin and other platinum(II) analogs are widely used in clinical practice as anti-cancer drugs for a wide range of tumors. The primary mechanism by which they exert their action is through the formation of adducts with genomic DNA. However, multiple cellular targets by platinum(II) complexes have been described. In particular, the early events occurring at the plasma membrane (PM), i.e., platinum-membrane interactions seem to be involved in the uptake, cytotoxicity and cell-resistance to cisplatin. In fact, PM influences signaling events, and cisplatin-induced changes on membrane organization and fluidity were shown to activate apoptotic pathways. This review critically discusses the sequence of events caused by lipid membrane-platinum interactions, with emphasis on the mechanisms that lead to changes in the biophysical properties of the membranes (e.g., fluidity and permeability), and how these correlate with sensitivity and resistance phenotypes of cells to platinum(II) complexes.