PD-L1 dimerisation induced by biphenyl derivatives mediates anti-breast cancer activity via the non-immune PD-L1-AKT-mTOR/Bcl2 pathway.

Recent studies on biphenyl-containing compounds, a type of PD-1/PD-L1 blocker which binds to PD-L1 and induces dimerisation, have focussed on its immune function. Herein, 10 novel biphenyl derivatives were designed and synthesised. The results of the CCK-8 showed that compounds have different anti-tumour activities for tumour cells in the absence of T cells. Particularly, 12j-4 can significantly induce the apoptosis of MDA-MB-231 cells (IC50 = 2.68 ± 0.27 µM). In further studies, 12j-4 has been shown to prevent the phosphorylation of AKT by binding to cytoplasmic PD-L1, which induces apoptosis in MDA-MB-231 cells through non-immune pathways. The inhibition of AKT phosphorylation restores the activity of GSK-3ß, ultimately resulting in the degradation of PD-L1. Besides, in vivo study indicated that 12j-4 repressed tumour growth in nude mice. As these biphenyls exert their anti-tumour effects mainly through non-immune pathways, they are worthy of further study as PD-L1 inhibitors.

Design, synthesis and anti-tumor activity of novel benzothiophenonaphthalimide derivatives targeting mitochondrial DNA (mtDNA) G-quadruplex.

A series of new naphthalimide derivatives, benzothiophenonaphthalimides (7a-7g, 8a-8g), were designed and synthesized, of which compounds 8a-8g are hydrochloride salts of corresponding compounds 7a-7g. All compounds presented different anti-tumor activities for tumor cells tested by the CCK-8 assay. In particular, compound 7c displayed the strongest anti-tumor activity with an IC50 value of 0.59 ± 0.08 µM and the best selectivity for HepG2 cells. At the same time, it was observed that 7c could induce HepG2 cell apoptosis, hinder cancer cell migration and arrest the cell cycle at the G2/M phase. Further mechanism studies revealed that 7c selectively induced a G-rich HRCC DNA sequence in the mitochondria to form a G-quadruplex structure (G4) and stabilized it, which mediated the decrease in mitochondrial membrane potential and the production of reactive oxygen species, causing mitochondrial dysfunction. Finally, this led to proliferative inhibition and apoptosis of cancer cells and protective autophagy by promoting the expression of p-Erk1/2. The in vivo experimental results indicated that the compound 8c as a salt of 7c showed significant in vivo anti-tumor efficacy in the HepG2-xenograft mouse model with a tumor growth inhibition rate of 51.4% at a dose of 15 mg/kg. These results suggest that 7c possesses a different anti-tumor mechanism from the previous main reported mechanism of naphthalimide derivatives, which targets the nucleus. In brief, 7c has good anti-tumor activity in vitro and in vivo and may act as a leading compound in development of drugs against liver cancer.

A 1,10-phenanthroline derivative selectively targeting telomeric G-quadruplex induces cytoprotective autophagy, causing apoptosis of gastric cancer cells.

AIMS: This study aimed to evaluate the ability of compound 13d to induce autophagy and to promote apoptosis of tumor cells and its interaction mechanism. MATERIALS AND METHODS: Using CCK-8 assay, transwell assay, fluorescence resonance energy transfer melting analysis (FRET), transmission electron microscopy, flow cytometry assay, immunofluorescence assay, Western blot analysis, and wound healing assay. KEY FINDINGS: The results indicated that compound 13d could induce autophagy and apoptosis of gastric cancer cells. Moreover, the findings of CCK-8 assay, colony formation, migration and invasion assay, and wound healing assay revealed that compound 13d would effectively inhibit cell proliferation, migration, and invasion. Its IC50 value is about 2.4 µM against gastric cancer cells, which is similar to positive drug­platinum. 13d specific induction of telomere G-quadruplex formation was proved in extracellular FRET melting assay, and indirectly affected telomerase activity. G-quadruplex formation promoted cell apoptosis and autophagy. Upon incorporating the autophagy inhibitors 3-MA and HCQ, the expression of the autophagy marker protein LC3 was then checked, suggesting that the compound 13d influences the autophagy flux. Furthermore, knocking down the autophagy-related gene Atg5 to reduce the level of autophagy enhances the anti-tumor activity and increases apoptotic cells' proportion. Mechanistic experiments have shown that blocking the Akt/m-TOR signal pathway plays a crucial role in autophagy and G-quadruplex induced telomere dysfunction. DNA damage is the leading cause of autophagy. Compound 13d combined with autophagy inhibitor can inhibit tumor cells more effectively. SIGNIFICANCE: Our findings demonstrate that compound 13d as a telomeric G-quadruplex ligand induces Telomere dysfunction, DNA damage response, autophagy, and apoptosis in gastric cancer cells by blocking the Akt/m-TOR signaling pathway.

Sequencing of complete mitochondrial genomes confirms synonymization of Hyalomma asiaticum asiaticum and kozlovi, and advances phylogenetic hypotheses for the Ixodidae.

Phylogeny of hard ticks (Ixodidae) remains unresolved. Mitochondrial genomes (mitogenomes) are increasingly used to resolve phylogenetic controversies, but remain unavailable for the entire large Hyalomma genus. Hyalomma asiaticum is a parasitic tick distributed throughout the Asia. As a result of great morphological variability, two subspecies have been recognised historically; until a morphological data-based synonymization was proposed. However, this hypothesis was never tested using molecular data. Therefore, objectives of this study were to: 1. sequence the first Hyalomma mitogenome; 2. scrutinise the proposed synonymization using molecular data, i.e. complete mitogenomes of both subspecies: H. a. asiaticum and kozlovi; 3. conduct phylogenomic and comparative analyses of all available Ixodidae mitogenomes. Results corroborate the proposed synonymization: the two mitogenomes are almost identical (99.6%). Genomic features of both mitogenomes are standard for Metastriata; which includes the presence of two control regions and all three "Tick-Box" motifs. Gene order and strand distribution are perfectly conserved for the entire Metastriata group. Suspecting compositional biases, we conducted phylogenetic analyses (29 almost complete mitogenomes) using homogeneous and heterogeneous (CAT) models of substitution. The results were congruent, apart from the deep-level topology of prostriate ticks (Ixodes): the homogeneous model produced a monophyletic Ixodes, but the CAT model produced a paraphyletic Ixodes (and thereby Prostriata), divided into Australasian and non-Australasian clades. This topology implies that all metastriate ticks have evolved from the ancestor of the non-Australian branch of prostriate ticks. Metastriata was divided into three clades: 1. Amblyomminae and Rhipicephalinae (Rhipicephalus, Hyalomma, Dermacentor); 2. Haemaphysalinae and Bothriocrotoninae, plus Amblyomma sphenodonti; 3. Amblyomma elaphense, basal to all Metastriata. We conclude that mitogenomes have the potential to resolve the long-standing debate about the evolutionary history of ticks, but heterogeneous evolutionary models should be used to alleviate the effects of compositional heterogeneity on deep-level relationships.