Pseudolaric acid B induces mitotic arrest and apoptosis in both imatinib-sensitive and -resistant chronic myeloid leukaemia cells

Pseudolaric Acid B Targets CD147 to Selectively Kill Acute Myeloid Leukemia Cells

Acute myeloid leukemia (AML) is an aggressive blood cancer. With low survival rates, new drug targets are needed to improve treatment regimens and patient outcomes. Pseudolaric acid B (PAB) is a plant-derived bioactive compound predicted to interact with cluster of differentiation 147 (CD147/BSG). CD147 is a transmembrane glycoprotein overexpressed in various malignancies with suggested roles in regulating cancer cell survival, proliferation, invasion, and apoptosis. However, the detailed function of PAB in AML remains unknown. In this study, AML cell lines and patient-derived cells were used to show that PAB selectively targeted AML (IC50: 1.59 ± 0.47 µM). Moreover, proliferation assays, flow cytometry, and immunoblotting confirmed that PAB targeting of CD147 resulted in AML cell apoptosis. Indeed, the genetic silencing of CD147 significantly suppressed AML cell growth and attenuated PAB activity. Overall, PAB imparts anti-AML activity through transmembrane glycoprotein CD147.

In vitro antimetastatic potential of pseudolaric acid B in HSC-3 human tongue squamous carcinoma cell line

OBJECTIVE

Pseudolaric acid B (PAB) is a novel diterpenoid derived from the traditional Chinese medicinal herb Cortex pseudolaricis that exerts anticancer, anti-inflammatory, and immunomodulatory properties. While the anticancer potential of PAB has been studied, its effects on metastasis have not been well-studied. This study aims to determine the inhibitory effects of PAB on HSC-3 human tongue squamous cell carcinoma (TSCC) cell line.

DESIGN

Cell viability and soft agar colony formation assays were conducted to assess cellular proliferation and in vitro tumorigenic capacity of TSCC cells, respectively. Additionally, wound healing, transwell migration, and invasion assays were conducted to monitor the aggressive behavior of TSCC cells. Furthermore, Western blotting analysis was conducted to reveal the signaling pathways involved in the modulation of epithelial-mesenchymal transition (EMT).

RESULTS

The migratory and invasive capacities of HSC-3 cells were suppressed by PAB irrespective of their proliferation states. PAB's effects on EMT involved upregulation of E-cadherin expression and downregulation of Twist; these were concomitantly accompanied by downregulated phosphorylation of epidermal growth factor receptor (EGFR).

CONCLUSIONS

PAB suppresses human TSCC in vitro by regulating Twist/E-cadherin through the EGFR signaling pathway. PAB may have potential as a candidate antimetastatic drug for TSCC treatment.

Inhibition of NF-κB and ERK signaling pathways in osteoclasts and M1 macrophage polarization: Mechanistic insights into the anti-osteoporotic effects of Pseudolaric acid B

Osteoporosis, characterized by bone metabolism disruption leading to gradual bone loss and increased fracture susceptibility, is linked to the excessive activation of osteoclasts. Pseudolaric acid B (PAB), identified as an NF-κB signaling inhibitor crucial for osteoclastogenesis, is explored here for its protective effects in osteoporosis. Noncytotoxic PAB's impact on osteoclast differentiation was assessed through cell viability and osteoclast formation assays, with subsequent testing of osteoclast function via bone resorption assays. Quantitative real-time polymerase chain reaction evaluated PAB's genetic-level impact on osteoclastogenesis. Network pharmacology, western blot, and luciferase reporter gene assays were employed to elucidate PAB's regulatory mechanism. In an in vivo model of osteoporosis induced by ovariectomy (OVX) in mice, micro-CT, H&E staining, and TRAP staining facilitated histomorphometry analysis, while flow cytometry verified macrophage polarization. PAB demonstrated inhibitory effects on osteoclast formation and bone resorption in BMM and RAW264.7 cells, suppressing osteoclast-specific genes. Bioinformatic analysis, western blot, and luciferase assay results indicated PAB's inhibition of IκBα phosphorylation in the NF-κB signaling pathway and ERK in MAPKs, elucidating its mechanism. In vivo experiments confirmed PAB's attenuation of osteoporosis by reducing osteoclast formation in OVX mice. PAB further facilitated macrophage conversion from M1 to M2 and suppressed IL-1β, TNF-α, and IL-6 synthesis. In conclusion, PAB prevents osteoporosis by inhibiting RANKL-induced osteoclastogenesis through NF-κB and ERK signaling pathway suppression, coupled with macrophage polarization. These findings indicate the potential therapeutic role of PAB in osteoporosis.

Suppressive effect of pseudolaric acid B on Echinococcus multilocularis involving regulation of TGF-β1 signaling in vitro and in vivo

Echinococcus multilocularis, the causative agent of alveolar echinococcosis (AE), severely threats human health and livestock farming. The first line of chemotherapeutic drug for AE is albendazole, which limits rapid extension of E. multilocularis metacestodes, but is rarely curative for AE, with severe side effects in long-term use, thus development of new anti-echinococcal drugs is mandated. Pseudolaric acid B (PAB) has long been used to treat fungal-infected dermatosis, and exerted anti-tumor, -fertility, -angiogenesis, -tubulin and antiparasitic activity. However, the effect of PAB against Echinococcus spp. remains unclear. The present study is to understand the effect of PAB against E. multilocularis in vitro and in vivo, and identify potential anti-echinococcal mechanism, as well as its toxicity. After exposure to PAB at 20 μg/ml, significant reduction of the survival rate and substantial ultrastructural destructions in E. multilocularis protoscoleces were observed in vitro. Furthermore, the wet weight of E. multilocularis cysts in the infected mice was significantly decreased after treatment with PAB (40, 20 or 10 mg/kg) for 12 weeks. Meanwhile, significant increase of both protein and mRNA expression of transforming growth factor beta 1 (TGF-β1) was detected in the serum and liver of the infected mice, whereas PAB administration lowered its expression significantly. The toxicity tests demonstrated that PAB displayed lower cytotoxicity to human liver and kidney cells (HL-7702 and HK-2 cell) with IC₅₀ = 25.29 and 42.94 μg/ml than albendazole with IC₅₀ = 3.71 and 21.22 μg/ml in vitro, and caused lower hepatoxicity and nephrotoxicity in mice than ABZ. Our findings indicated that PAB possesses potent anti-echinococcal effect, with lower toxicity than albendazole, implying a potential chemotherapeutic agent for AE. Additionally, the present study demonstrated that the suppressive effect of PAB on the parasite may involve down-regulation of TGF-β1 signaling.

Co-loaded lapatinib/PAB by ferritin nanoparticles eliminated ECM-detached cluster cells via modulating EGFR in triple-negative breast cancer

Cancer stem cell (CSC) cluster of triple-negative breast cancer (TNBC) is suggested to be responsible for therapy resistance, metastatic process and cancer recurrence, yet the sensitivity of CSC clusters of TNBC to ferroptosis remains elusive in a great measure. Current research revealed that epidermal growth factor receptor (EGFR) reinforced CD44-mediated TNBC cell clustering, whether blockade of EGFR has synergistic effects on erastin-induced tumor inhibition of CSC clusters is still poorly understood. Here, we found that fraction of CD24^lowCD44^high cells and size of tumor spheres clearly decreased following EGFR inhibition in TNBC cells. Inhibition of EGFR promoted expression of LC3B-II via YAP/mTOR signaling pathway, indicating that EGFR-mediated autophagy which contributed to ferroptosis. In order to further verify the protective effects of EGFR on ferroptosis induced by small molecules in TNBC cells, pseudolaric acid B (PAB) which led to ferroptosis of malignant cells was selected. In our experiment, lapatinib and PAB cotreatment inhibited TNBC cells viability and restrained formation of tumor spheres, accompanied with a high level of intracellular ROS. To target delivery lapatinib and PAB to TNBC cells, lapatinib/PAB@Ferritin (L/P@Ferritin) nanoparticles were prepared; results of in vitro and in vivo showed a higher tumor suppression efficiency of L/P@Ferritin, highlighting that it might provide a new perspective for treatment of CSC clusters of TNBC.