Rosmarinic acid attenuates glioblastoma cells and spheroids' growth and EMT/stem-like state by PTEN/PI3K/AKT downregulation and ERK-induced apoptosis

Circular RNAs in glioma progression: Fundamental mechanisms and therapeutic potential: A review

Gliomas are the most common primary malignant brain tumors, characterized by aggressive invasion, limited therapeutic options, and poor prognosis. Despite advances in surgery, radiotherapy, and chemotherapy, the median survival of glioma patients remains disappointingly low. Therefore, identifying glioma-associated therapeutic targets and biomarkers is of significant clinical importance. Circular RNAs (circRNAs) are a class of naturally occurring long non-coding RNAs (lncRNAs), notable for their stability and evolutionary conservation. Increasing evidence indicates that circRNA expression is dysregulated in gliomas compared to adjacent non-tumor tissues and contributes to the regulation of glioma-related biological processes. Furthermore, numerous circRNAs function as oncogenes or tumor suppressors, mediating glioma initiation, progression, and resistance to temozolomide (TMZ). Mechanistically, circRNAs regulate glioma biology through diverse pathways, including acting as miRNA sponges, binding RNA-binding proteins (RBPs), modulating transcription, and even encoding functional peptides. These features highlight the potential of circRNAs as diagnostic and prognostic biomarkers, as well as therapeutic targets for glioma. This review summarizes the dysregulation and functions of circRNAs in glioma and explores key mechanisms through which they mediate tumor progression, including DNA damage repair, programmed cell death (PCD), angiogenesis, and metabolic reprogramming. Our aim is to provide a comprehensive perspective on the multifaceted roles of circRNAs in glioma and to highlight their potential for translational application in targeted therapy.

Natural compound rosmarinic acid displays anti-tumor activity in colorectal cancer cells by suppressing nuclear factor-kappa B signaling

BACKGROUND

Rosmarinic acid (RA) is a natural polyphenol carboxylic acid known for its role in chemoprevention. Given its widespread use as a food additive, we are interested in whether RA affects the development of colorectal cancer (CRC).

AIM

To examine the anti-tumor effects of RA on various CRC cell lines, and to further investigate the possible mechanisms.

METHODS

Cell Counting Kit-8 assay and optical microscopy imaging were used to evaluate the viability of CRC cell lines. Western blot, quantitative real-time polymerase chain reaction, and flow cytometry analyses were performed to assess cell viability and activation of nuclear factor-kappa B (NF-κB) signaling. Molecular modeling was used to assess the interaction between RA and inhibitory kappa B kinase beta. Luciferase assay was used to examine the activity of NF-κB-driven transcription. The combinations of RA with 5-fluorouracil or oxaliplatin were utilized to evaluate the potential synergistic action of RA with the chemotherapeutics.

RESULTS

RA exerted potent cytotoxic actions on all six CRC cell lines examined. RA was docked nicely into the binding pocket of inhibitory kappa B kinase beta by molecular modeling. The activity of NF-κB-driven luciferase and the phosphorylation of NF-κB p65 were decreased after exposure to the compound. Lipopolysaccharide-induced NF-κB activation was effectively inhibited by RA, too. Further, RA downregulated the expression of cell proliferation-related cyclin D1 and MYC, which are target genes of NF-κB. Of note, the cytotoxic actions of 5-fluorouracil and oxaliplatin were markedly enhanced by RA in those CRC cells.

CONCLUSION

Our results indicate that RA inhibits NF-κB signaling and induces apoptosis in CRC cells. It enhances the cytotoxic actions of chemotherapeutics and might help to improve the chemotherapy of CRC.

β,β-Dimethylacryloyl Alkannin from Arnebia euchroma Roots Suppresses Triple-Negative Breast Cancer Growth via AKT/Gli1 Signaling

After confirmation of Arnebia euchroma by genetic analysis, we identified the key compounds from the root: alkannin (1), acetylalkannin (2), β-acetoxyisovaleryl alkannin (3), isobutyryl alkannin (4), and β,β-dimethylacryloyl alkannin (DMA) (5). Among these, DMA most effectively inhibited the proliferation of triple-negative breast cancer (TNBC) cells, with IC50 values of 5.1 μM (MDA-MB-231) and 8.7 μM (MCF10DCIS.com). DMA and the Hedgehog (Hh) inhibitor Gant61 targeting Gli1 significantly induced apoptosis, as indicated by increased Bax and cleaved PARP, and decreased Bcl-2 levels (p < 0.01) in both cell lines. We also identified AKT as a potential target of DMA, as treatment reduced phosphorylated AKT (Ser473) protein levels by 66.3% ± 0.7% and 30.1% ± 5.7% in MDA-MB-231 and MCF10DCIS.com cells, respectively (p < 0.01). In vivo, DMA (25 mg/kg) suppressed MDA-MB-231 xenograft tumor growth by approximately 78% (p < 0.01) and induced apoptosis through regulating AKT/Hh/Gli1 axis. Interestingly, the reduced form of DMA (5') lost its efficacy in inhibiting proliferation, p-AKT expression, and Gli1 transcriptional activity and nuclear localization, indicating that the Michael acceptor in DMA is critical for inhibiting TNBC growth. Overall, DMA suppressed TNBC in vitro and in vivo through AKT/Gli1 pathway and shows potential as a potent agent against TNBC.

A Positive Feedback DNA-PK/MYT1L-CXCR1-ERK1/2 Proliferative Signaling Loop in Glioblastoma

Glioblastoma is the most common primary brain tumor in adults. Our previous studies revealed a functional interplay of myelin transcription factor 1-like (MYT1L) with the DNA-dependent protein kinase (DNA-PK) in the regulation of p21 transcription. However, the contributing role of this functional interplay in glioblastoma remains largely unknown. Here, we used cell lines with normal DNA-PK (HEK293 and M059K) or deficient DNA-PK (M059J) as a model system to demonstrate the importance of the DNA-PK-dependent activation of MYT1L in controlling the transcription of CXC chemokine receptor 1 (CXCR1) in a positive-feedback proliferative signaling loop in glioblastoma with numerous conventional techniques. In normal DNA-PK cells, MYT1L acted as an oncogene by promoting cell proliferation, inhibiting apoptosis, and shortening a cell cycle S phase. However, in DNA-PK-deficient cells, MYT1L functioned as a tumor suppressor by inhibiting cell proliferation and inducing a G1 arrest. The enforced expression of MYT1L promoted CXCR1 transcription in DNA-PK-normal cells but attenuated transcription in DNA-PK-deficient cells. Bioinformatics analysis predicted a MYT1L-binding sequence at the CXCR1 promoter. The functional dependence of MYT1L on DNA-PK in CXCR1 transcription was validated by luciferase assay. Although the expression of CXCR1 was lower in M059J cells as compared to M059K cells, it was higher than in normal brain tissue. The CXCR1 ligands interleukin 8 (IL-8) and GRO protein alpha (GROα) expressed in M059J and M059K cells may signal through the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway that can be blocked by CXCR1 siRNA. Our findings demonstrate the existence of a positive feedback DNA-PK/MYT1L-CXCR1-ERK1/2 proliferation loop in glioblastoma cells that may represent a pharmacological target loop for therapeutic intervention.

Transitioning from molecular methods to therapeutic methods: An in‑depth analysis of glioblastoma (Review)

Glioblastoma (GBM) is the most aggressive primary brain tumour, characterised by high heterogeneity, aggressiveness and resistance to conventional therapies, leading to poor prognosis for patients. In recent years, with the rapid development of molecular biology and genomics technologies, significant progress has been made in understanding the molecular mechanisms of GBM. This has revealed a complex molecular network involving aberrant key signalling pathways, epigenetic alterations, interactions in the tumour microenvironment and regulation of non‑coding RNAs. Based on these molecular features, novel therapeutic strategies such as targeted therapies, immunotherapy and gene therapy are rapidly evolving and hold promise for improving the outcome of GBM. This review systematically summarises the advances in molecular mechanisms and therapeutic approaches for GBM. It aims to provide new perspectives for the precise diagnosis and personalised treatment of GBM, and to ultimately improve the prognosis of patients.

Fatty acid synthase inhibitor cerulenin attenuates glioblastoma progression by reducing EMT and stemness phenotypes, inducing oxidative and ER stress response, and targeting PI3K/AKT/NF-κB axis

Targeting cellular metabolism is becoming a critical approach for stopping cancer progression. Limited information is available regarding the effects of inhibiting the lipogenic enzyme fatty acid synthase (FASN) in glioblastoma (GB) cells (grade-IV-astrocytoma), which have high invasion and low response to standard treatments. Herein, we used cerulenin (CER) to inhibit FASN. CER treatments (3.6 μg/mL/48 h and 5.55 μg/mL/48 h indicate IC20 and IC50 values, respectively) led to a dose- and time-dependent decrease in the viability of the U-87MG human GB cells. A significant decrease was detected in the levels of fatty acids, including palmitic acid, determined by GS-MS analysis. FASN inhibition attenuated cell motility, 2D and 3D-clonogenic survival, and cell differentiation characteristics (related markers of epithelial-mesenchymal transition/EMT and stemness). Moreover, treatments caused mitochondrial membrane potential (MMP) collapse and increased intracellular reactive oxygen species (ROS) levels. Protein aggregates and ER stress in the cells also increased. Remarkably, despite increased Hsp70 and p-HSF1 levels against induced cellular stress, CER promoted markedly autophagy and apoptosis. The network pharmacology approach revealed that protein and lipid kinases are crucial targets in cell signaling, and PI3K, AKT, and NF-κB levels were confirmed by immunoblotting. The results demonstrated for the first time that inhibiting FA production and FASN function induces cell death through ROS generation and ER stress while simultaneously reducing the motility and aggressiveness of U-87MG human glioblastoma cells by attenuating EMT and stemness phenotypes. Therefore, blocking lipid metabolism using CER may be considered as a good candidate for GB therapeutic option.