Suppressing c-FOS expression by G-quadruplex ligands inhibits osimertinib-resistant non-small cell lung cancer

Single-cell transcriptomic analysis of canine insulinoma reveals distinct sub-populations of insulin-expressing cancer cells

Canine malignant insulinoma is a rare, highly metastatic and life-threatening neuroendocrine tumour of pancreatic beta cells. To map the single-cell transcriptomic landscape of canine insulinoma for the first time, transcriptomic profiles of 5,532 cells were captured from two spontaneous insulinomas (Patient 1 and 2) and one associated metastasis (Patient 2) in two Boxer dogs. Distinct cancer, endocrine, and immune cell populations were identified. Notably, all three tumour samples contained two transcriptionally distinct insulin-expressing tumour cell populations (INS+ and INS+FOS low ), characterised here for the first time. These two cancer cell populations significantly differed by ~ 8,000 differentially expressed genes (DEGs), particularly tumour suppressor genes (e.g. TP53, EGR1) and cancer-related pathways (e.g., MAPK, p53). In contrast, COX7A2L was one of a few genes ubiquitously expressed and significantly upregulated (> 20-fold) in both insulin-expressing tumour populations compared to other captured populations. Both populations were also characterised by expression of chromogranin/secretogranin neuroendocrine tumour marker genes (e.g. CHGA, SCGN). There were far fewer gene expression differences observed between insulin-expressing tumour cells from the two patients (~ 600 DEGs) than between the two cancer cell populations within each patient. These DEGs included CLTRN, TMSB4X, CSRP2, LGALS2, and C15orf48. Unexpectedly for a tumour of endocrine origin, the metastasis in Patient 2 exhibited > 20-70 fold upregulation of exocrine pancreatic genes including CLPS, PRSS2, PRSS and CTRC. Immune cell analyses identified distinct infiltrating immune populations, including memory T cells and macrophages and revealed likely tumour-immune interactions, including the CD40-CD40L interaction. This study provides the first single-cell RNA sequencing (scRNA-seq) analysis of naturally occurring insulinoma in any species, revealing tumour cell heterogeneity, novel immune microenvironment features, and potential therapeutic targets. Despite its small scale, the findings highlight the utility of scRNA-seq in veterinary oncology and its translational potential for pancreatic neuroendocrine tumours across species.

Supplementary Information

The online version contains supplementary material available at 10.1186/s44356-025-00026-3.

Alkannin triggered apoptosis and ferroptosis in gastric cancer by suppressing lipid metabolism mediated by the c-Fos/SREBF1 axis

BACKGROUND

Gastric cancer (GC), one of the most common malignancies with high mortality worldwide, currently requires beneficial therapeutic strategies. Alkannin is the primary active component of Lithospermum erythrorhizon and has been shown to have potential anticancer effects on a variety of cancers. However, the specific effects and molecular mechanisms of alkannin against GC remain unknown.

PURPOSE

This study aimed to explore the detailed role and downstream effectors of alkannin in the treatment of GC.

METHODS

The functions of alkannin on the proliferation, migration and invasion of GC cells were measured via CCK-8, EdU, colony formation, LDH release, flow cytometry, wound healing, and Transwell assays. BODIPY-C11 staining, determination of cellular ferrous iron, MDA and GSH levels, and western blotting were used to evaluate alkannin-induced ferroptosis. Transcriptome sequencing was analyzed to identify differentially expressed genes. Nile red staining and cholesterol and triglyceride assays were utilized to examine changes in lipid metabolism. Transcriptional regulation was determined by real-time PCR, dual-luciferase reporter and chromatin immunoprecipitation assays. Finally, a xenograft animal model was employed to assess tumor growth in vivo.

RESULTS

Alkannin inhibited growth and motility and simultaneously triggered apoptotic and ferroptotic cell death in GC cells. Transcriptome sequencing analysis revealed that alkannin treatment downregulated c-Fos expression. The overexpression of c-Fos conferred the GC cells to tolerate alkannin in vitro and in vivo. Moreover, we confirmed that c-Fos activated SREBF1 transcription by directly binding to TPA-responsive elements within the SREBF1 promoter, leading to increased expression of lipid biosynthesis-related genes, which counteracted ferroptosis through the maintenance of cellular lipid homeostasis.

CONCLUSION

Our present study provides the first evidence that alkannin induces both apoptosis and ferroptosis in GC cells and reveals a novel mechanism by which alkannin restrains c-Fos-dependent SREBF1 transcriptional activation, leading to lipid metabolism and redox homeostasis disorders. Our findings highlight that alkannin is an available and promising natural product for the avoidance of drug resistance and the clinical treatment of GC.

Identification of BMVC-8C3O as a novel Pks13 inhibitor with anti-tuberculosis activity

Given the increasing prevalence of drug-resistant tuberculosis (TB), there is an urgent demand in developing novel anti-TB medications with highly effective, safe, and utilize innovative mechanisms of action. Blocking the mycolic acid synthesis pathway is well-established to be a significant strategy in developing anti-TB drugs, and Pks13 was identified as a crucial enzyme in this process. Importantly, the modes of action of recognized Pks13 inhibitors differ from traditional anti-TB medications, highlighting Pks13 as a potential and promising target in drug development within TB treatment. In this study, we discovered a compound named BMVC-8C3O that effectively inhibited the activity of Pks13 with a 6.94 μM IC50 value. The binding between BMVC-8C3O and Pks13 was validated through surface plasmon resonance (SPR) assay as well as molecular docking analysis. Moreover, the SPR assay showed that the mutation of Asn1640 and Ser1533 resulted in decreased affinity of BMVC-8C3O to Pks13. Additionally, BMVC-8C3O not only exhibited activity against Mycobacterium tuberculosis (MTB), but also displayed potential intracellular anti-TB activity in macrophages. In summary, our findings indicate that BMVC-8C3O holds great potential as a lead compound against TB.

Impact of C-FOS/C-JUN Transcriptional Factors Co-Expression in Non-small Cell Lung Carcinoma

Background/Aim

Significant transcription factors - including c-Fos (gene locus: 14q24.3) and c-Jun (gene locus: 1p32-p31) - regulate cell homeostasis preventing abnormal signal transduction to nucleus. Their over-activation seems to be associated with an aggressive phenotype in non-small cell lung carcinomas (NSCLCs). In the current study, our aim was to co-analyze c-FOS/c-JUN protein expression in a series of NSCLCs correlating them to the corresponding clinico-pathological features.

Materials and Methods

A set of fifty (n=50) paraffin embedded NSCLC tissue sections were selected comprising of adenocarcinomas (n=25) and squamous cell carcinomas (n=25), respectively. Immunocytochemistry (IHC) for the c-FOS/c-JUN markers was implemented. Digital image analysis (DIA) was also performed for evaluating objectively the corresponding immunostaining intensity levels of the examined proteins.

Results

All the examined tissue samples expressed the markers in different protein levels. High staining intensity levels were detected in 34/50 (68%) and 24/50 (48%), respectively. C-FOS over expression was statistically significant correlated to stage (p=0.033), whereas C-JUN over expression was associated with NSCLC histotype (p=0.05) and with maximum tumor diameter (p=0.046).

Conclusion

C-FOS/C-JUN co- over activation is observed frequently in NSCLC, playing potentially a central role in the aggressiveness of the malignancy's phenotype (advanced stage, increased metastatic potential). Development and implementation of novel agents that target these transcription factors is a promising approach for applying targeted therapeutic strategies in NSCC patients based on specific genetic signatures and protein profiles.

FOS-Mediated PLCB1 Induces Radioresistance and Weakens the Antitumor Effects of CD8+ T Cells in Triple-Negative Breast Cancer

Radioresistance and immune evasion are interactive and crucial events leading to treatment failure and progression of human malignancies. This research studies the role of phospholipase C beta 1 (PLCB1) in these events in triple-negative breast cancer (TNBC) and the regulatory mechanism. PLCB1 was bioinformatically predicted as a dysregulated gene potentially linked to radioresistance in TNBC. Parental TNBC cell lines were exposed to fractionated radiation for 6 weeks. PLCB1 expression was decreased in the first 2 weeks but gradually increased from Week 3. PLCB1 knockdown increased the radiosensitivity of the cells, as manifested by a decreased half-inhibitory dose of irradiation, reduced cell proliferation, apoptosis resistance, mobility, and tumorigenesis in mice. The FOS transcription factor promoted PLCB1 transcription and activated the PI3K/AKT signaling. Knockdown of FOS similarly reduced radioresistance and T cells-mediated immune evasion. However, the radiosensitivity of TNBC cells and the antitumor effects of CD8+ T cells could be affected by a PI3K/AKT activator or by the PLCB1 upregulation. The PLCB1 or FOS knockdown also suppressed radioresistance and tumorigenesis of the TNBC cells in mice. In conclusion, FOS-mediated PLCB1 induces radioresistance and weakens the antitumor effects of CD8+ T cells in TNBC by activating the PI3K/AKT signaling pathway.

Discovery of Voreloxin as a Dual-Selective Stabilizer for c-Myc/Bcl-2 G-Quadruplexes in Leukemia

Overexpression of c-Myc is a key factor in the development of leukemia and other malignancies, highlighting the urgent need for novel drugs to inhibit c-Myc protein levels. DNA G-quadruplexes (G4) have emerged as potential regulatory targets for c-Myc expression. Previous studies identified trovafloxacin, a topoisomerase II inhibitor, as a novel c-Myc G4 stabilizer. In this study, virtual screening based on structural similarity led to the identification of nine derivatives of trovafloxacin, among which voreloxin exhibited potent cytotoxicity in multiple myeloma cells and showed promising therapeutic efficacy in leukemia cells. FRET assays demonstrated that voreloxin specifically stabilized the G4 structures of c-Myc and Bcl-2, with minimal effects on the G4 structures of other oncogenes. Moreover, voreloxin significantly reduced the expression levels of c-Myc and Bcl-2 in THP-1 and MOLM-13 cells. Molecular docking, molecular dynamics (MD) simulations, and MM/GBSA calculations further confirmed the stable binding of voreloxin to both c-Myc and Bcl-2 G4s, primarily driven by π-π stacking and hydrogen bonding interactions. These findings provide valuable insights for the development of G4-targeting drugs for cancer therapy.

EndoQuad: a comprehensive genome-wide experimentally validated endogenous G-quadruplex database

G-quadruplexes (G4s) are non-canonical four-stranded structures and are emerging as novel genetic regulatory elements. However, a comprehensive genomic annotation of endogenous G4s (eG4s) and systematic characterization of their regulatory network are still lacking, posing major challenges for eG4 research. Here, we present EndoQuad (https://EndoQuad.chenzxlab.cn/) to address these pressing issues by integrating high-throughput experimental data. First, based on high-quality genome-wide eG4s mapping datasets (human: 1181; mouse: 24; chicken: 2) generated by G4 ChIP-seq/CUT&Tag, we generate a reference set of genome-wide eG4s. Our multi-omics analyses show that most eG4s are identified in one or a few cell types. The eG4s with higher occurrences across samples are more structurally stable, evolutionarily conserved, enriched in promoter regions, mark highly expressed genes and associate with complex regulatory programs, demonstrating higher confidence level for further experiments. Finally, we integrate millions of functional genomic variants and prioritize eG4s with regulatory functions in disease and cancer contexts. These efforts have culminated in the comprehensive and interactive database of experimentally validated DNA eG4s. As such, EndoQuad enables users to easily access, download and repurpose these data for their own research. EndoQuad will become a one-stop resource for eG4 research and lay the foundation for future functional studies.

EGFR suppression contributes to growth inhibitory activity of G-quadruplex ligands in non-small cell lung cancers

Non-small cell lung carcinomas (NSCLCs) commonly harbor activating mutations in the epidermal growth factor receptor (EGFR). Drugs targeting the tyrosine kinase activity of EGFR have shown effectiveness in inhibiting the growth of cancer cells with EGFR mutations. However, the development of additional mutations in cancer cells often leads to the persistence of the disease, necessitating alternative strategies to overcome this challenge. We explored the efficacy of stabilizing the G-quadruplex structure formed in the promoter region of EGFR as a means to suppress its expression and impede the growth of cancer cells with EGFR mutations. We revealed that the carbazole derivative BMVC-8C3O effectively suppressed EGFR expression and demonstrated significant growth inhibition in EGFR-mutated NSCLC cells, both in cell culture and mouse xenograft models. Importantly, the observed repression of EGFR expression and growth inhibition were not exclusive to carbazole derivatives, as several other G-quadruplex ligands exhibited similar effects. The growth-inhibitory activity of BMVC-8C3O is attributed, at least in part, to the repression of EGFR, although it is possible that additional cellular targets are also affected. Remarkably, the growth-inhibitory effect was observed even in osimertinib-resistant cells, indicating that BMVC-8C3O holds promise for treating drug-resistant NSCLC. Our findings present a promising and innovative approach for inhibiting the growth of NSCLC cells with EGFR mutations by effectively suppressing EGFR expression. The demonstrated efficacy of G-quadruplex ligands in this study highlights their potential as candidates for further development in NSCLC therapy.