1‑Palmitoyl‑2‑linoleoyl‑3‑acetyl‑rac‑glycerol ameliorates EGF‑induced MMP‑9 expression by promoting receptor desensitization in MDA‑MB‑231 cells

Breaking Barriers in Oncology: Harnessing Sonodynamic Therapy for Enhanced Tumor Metabolism Regulation

The recent booming development of sonometabolism regulation in controlling the tumor microenvironment (TME) has opened a new research area to identify innovative approaches against cancer. The aim of this review is to highlight the potentials and advantages of sonodynamic therapy (SDT) in antitumor nanotherapies, specifically, delineating the progress made in SDT concerning the regulation of TME metabolism which encompasses factors such as hypoxia, redox balance, autophagy, immunosuppression, ion homeostasis, and other metabolic processes. By focusing on both tumor cell metabolism and TME dynamics, a wide range of SDT strategies that have demonstrated great therapeutic effectiveness by targeting the metabolic functions inherent to TME are summarized. In conclusion, this review offers valuable insights for researchers involved in SDT-based antitumor therapeutic strategies, with the aim of advancing the development of antitumor SDT methodologies in future research.

Glucocorticoids regulate the expression of Srsf1 through Hdac4/Foxc1 axis to induce apoptosis of osteoblasts

Further study of the mechanism of glucocorticoid (GC)-induced osteoblast (OB) apoptosis is highly important for the prevention and treatment of GC-induced osteoporosis and osteonecrosis. Serine/arginine-rich splicing factor 1 (Srsf1) expression was downregulated in a dose-dependent manner during GC-induced OB apoptosis. Knockdown of Srsf1 significantly promotes GC-induced OB apoptosis, while overexpression of Srsf1 significantly inhibits GC-induced OB apoptosis. Mechanistically, GC induces the up-regulation of histone deacetylase 4 (Hdac4) in OB, and inhibits the expression of transcription activator forkhead box C1 (Foxc1) by reducing the levels of histone H3 lysine 9 acetylation (H3K9ac) and H3K27ac in the promoter region of Foxc1, thereby down-regulating Srsf1. Next, SRSF1 regulates GC-induced OB apoptosis by regulating Bcl-2 modifying factor (Bmf) alternative splicing. From the perspective of alternative splicing, this study demonstrates that Srsf1 and its regulatory mechanism may serve as a new target for the prevention and treatment of GC-induced osteoporosis and osteonecrosis.

Backsplicing of the HIV-1 transcript generates multiple circRNAs to promote viral replication

Circular RNAs (circRNAs) are a family of non-coding RNAs that originate from a non-canonical splicing event (backsplicing) that forms covalently closed continuous loops. An analysis of the human immunodeficiency type 1 virus (HIV-1) complex splicing pattern indicated that the virus had the potential to generate at least 15 distinct circRNAs. The predicted HIV circRNAs were amplified utilizing divergent PCR primers and confirmed by RNase R digestion and sequencing. A predictive circRNA-miRNA interaction modeling approach and a series of validation assays determined that two cellular miRNAs, miR-6727-3p and miR-4722-3p, functionally interact with a sequence present in 8 of the HIV circRNAs. Expression of miR-6727-3p and miR-4722-3p restricted HIV-1 replication while a circRNA containing the sequence recognized by miR-6727-3p and miR-4722-3p increased the production of infective virions. Additionally, miR-6727-3p and miR-4722-3p expression was upregulated following HIV-1 infection of primary CD4+ T cells. Overall, the data presented shows that HIV-1 generates circRNAs which promote viral replication by sequestering and inhibiting the functions of miR-6727-3p and miR-4722-3p.

1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol treatment inhibits abnormal tumor growth by regulating neutrophil infiltration in a non-small cell lung carcinoma mouse model

Excessive neutrophil infiltration into the tumor microenvironment (TME) is an important factor that contributes to tumor overgrowth and limited immunotherapy efficacy. Neutrophils activate various receptors involved in tumor progression, while suppressing the infiltration and activity of cytotoxic T cells and creating optimal conditions for tumor growth. Therefore, the appropriate control of neutrophil infiltration is an effective strategy for tumor treatment. In the present study, 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) inhibited tumor overgrowth by suppressing excessive neutrophil infiltration, resulting in >74.97 % reduction in tumor size in a Lewis lung carcinoma (LLC-1) mouse model. All subjects in the positive control group died during the 90-day survival period, whereas only four subjects in the PLAG treatment group survived. PLAG had a significantly higher tumor growth inhibitory effect and survival rate than other neutrophil infiltration-targeting inhibitors (e.g., Navarixin, lymphocyte antigen 6 complex locus G6D antibody [aLy6G]). The ability of PLAG to regulate neutrophil infiltration and inhibit tumor growth depends on thioredoxin-interacting protein (TXNIP). In tumors lacking TXNIP expression, PLAG failed to control neutrophil infiltration and infiltration-related factor release, and the inhibitory effect of PLAG on tumor growth was reduced. PLAG-mediated inhibition of neutrophil infiltration enhances the efficacy of immune checkpoint inhibitors (ICIs), increasing the antitumor efficacy and survival rate by 30 %. In conclusion, PLAG could be a novel alternative to anti-tumor drugs that effectively targets excessive neutrophil infiltration into cancer tissues.

The role of TXNIP in cancer: a fine balance between redox, metabolic, and immunological tumor control

Thioredoxin-interacting protein (TXNIP) is commonly considered a master regulator of cellular oxidation, regulating the expression and function of Thioredoxin (Trx). Recent work has identified that TXNIP has a far wider range of additional roles: from regulating glucose and lipid metabolism, to cell cycle arrest and inflammation. Its expression is increased by stressors commonly found in neoplastic cells and the wider tumor microenvironment (TME), and, as such, TXNIP has been extensively studied in cancers. In this review, we evaluate the current literature regarding the regulation and the function of TXNIP, highlighting its emerging role in modulating signaling between different cell types within the TME. We then assess current and future translational opportunities and the associated challenges in this area. An improved understanding of the functions and mechanisms of TXNIP in cancers may enhance its suitability as a therapeutic target.

HnRNP K regulates inflammatory gene expression by mediating splicing pattern of transcriptional factors

HnRNP K is a heterogeneous nuclear ribonucleoprotein and has been identified as an oncogene in most solid tumors via regulating gene expression or alternative splicing of genes by binding both DNA and pre-mRNA. However, how hnRNP K affects tumorigenesis and regulates the gene expression in cervical cancer (CESC) remains to be elucidated. In these data, higher expression of hnRNP K was observed in CESC and was negatively correlated with the patient survival time. We then overexpressed hnRNP K (hnRNP K-OE) and found that its overexpression promoted cell proliferation in HeLa cells (P = 0.0052). Next, global transcriptome sequencing (RNA-seq) experiments were conducted to explore gene expression and alternative splicing profiles regulated by hnRNP K. It is shown that upregulated genes by hnRNP K-OE were associated with inflammatory response and an apoptotic process of neuron cells, which involves in cancer. In addition, the alternative splicing of those genes regulated by hnRNP K-OE was associated with transcriptional regulation. Analysis of the binding features of dysregulated transcription factors (TFs) in the promoter region of the inflammatory response genes regulated by hnRNP K revealed that hnRNP K may modulate the expression level of genes related to inflammatory response by influencing the alternative splicing of TFs. Among these hnRNP K-TFs-inflammatory gene regulatory networks, quantitative reverse transcription polymerase chain reaction (RT-qPCR) experiments and gene silencing were conducted to verify the hnRNP K-IRF1-CCL5 axis. In conclusion, the hnRNP K-TFs-inflammatory gene regulatory axis provides a novel molecular mechanism for hnRNP K in promoting CESC and offers a new therapeutic target.

Alternative splicing in multiple myeloma is associated with the non-homologous end joining pathway

Alternative splicing plays a pivotal role in tumorigenesis and proliferation. However, its pattern and pathogenic role has not been systematically analyzed in multiple myeloma or its subtypes. Alternative splicing profiles for 598 newly diagnosed myeloma patients with comprehensive genomic annotation identified primary translocations, 1q amplification, and DIS3 events to have more differentially spliced events than those without. Splicing levels were correlated with expression of splicing factors. Moreover, the non-homologous end joining pathway was an independent factor that was highly associated with splicing frequency as well as an increased number of structural variants. We therefore identify an axis of high-risk disease encompassing expression of the non-homologous end joining pathway, increase structural variants, and increased alternative splicing that are linked together. This indicates a joint pathogenic role for DNA damage response and alternative RNA processing in myeloma.

Improving anticancer effect of aPD-L1 through lowering neutrophil infiltration by PLAG in tumor implanted with MB49 mouse urothelial carcinoma

BACKGROUND

The PD-L1 antibody is an immune checkpoint inhibitor (ICI) attracting attention. The third-generation anticancer drug has been proven to be very effective due to fewer side effects and higher tumor-specific reactions than conventional anticancer drugs. However, as tumors produce additional resistance in the host immune system, the effectiveness of ICI is gradually weakening. Therefore, it is very important to develop a combination therapy that increases the anticancer effect of ICI by removing anticancer resistance factors present around the tumor.

METHODS

The syngeneic model was used (n = 6) to investigate the enhanced anti-tumor effect of PD-L1 antibody with the addition of PLAG. MB49 murine urothelial cancer cells were implanted into the C57BL/6 mice subcutaneously. PLAG at different dosages (50/100 mpk) was daily administered orally for another 4 weeks with or without 5 mpk PD-L1 antibody (10F.9G2). PD-L1 antibody was delivered via IP injection once a week.

RESULTS

The aPD-L1 monotherapy group inhibited tumor growth of 56% compared to the positive group, while the PLAG and aPD-L1 co-treatment inhibited by 89%. PLAG treatment effectively reduced neutrophils infiltrating localized in tumor and converted to a tumor microenvironment with anti-tumor effective T-cells. PLAG increased tumor infiltration of CD8 positive cytotoxic T-cell populations while effectively inhibiting the infiltration of neoplastic T-cells such as CD4/FoxP3. Eventually, neutrophil-induced tumor ICI resistance was resolved by restoring the neutrophil-to-lymphocyte ratio to the normal range. In addition, regulation of cytokine and chemokine factors that inhibit neutrophil infiltration and increase the killing activity of cytotoxic T cells was observed in the tumors of mice treated with PLAG + aPD-L1.

CONCLUSIONS

PLAG effectively turned the tumor-promoting microenvironment into a tumor-suppressing microenvironment. As a molecule that increases the anti-tumor effectiveness of aPD-L1, PLAG has the potential to be an essential and effective ICI co-therapeutic agent.

PLAG co-treatment increases the anticancer effect of Adriamycin and cyclophosphamide in a triple-negative breast cancer xenograft mouse model

Chemotherapy induces tumor cell death and inhibits tumor progression, but the accompanying immune responses in the surrounding dying tissue cause significant inflammation. These responses, such as excessive neutrophil infiltration into tumor tissue, are the main causes of resistance to anticancer treatment. The development of drugs that reduce neutrophil infiltration into tumors is necessary to increase the anticancer effect of chemotherapy. Here, we show that the antitumor effect of the chemotherapy AC regimen (Adriamycin and cyclophosphamide) was increased by 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) cotreatment in the MDA-MB-231 triple-negative breast cancer xenograft mouse model. Tumor growth was inhibited up to 56% in mice treated with AC and inhibited up to 94% in mice cotreated with AC and PLAG. Side effects of chemotherapy, such as a reduction in body weight, were alleviated in mice cotreated with AC and PLAG. Excessive neutrophil infiltration caused by the AC regimen was successfully cleared in mice cotreated with AC and PLAG. We conclude that PLAG inhibits excessive neutrophil infiltration that aids tumor growth. Reduced neutrophils and increased lymphocytes in PLAG-treated mice can maximize the antitumor effect of the AC regimen and inhibit tumor growth.

Suppression of tumor progression by thioredoxin-interacting protein-dependent adenosine 2B receptor degradation in a PLAG-treated Lewis lung carcinoma-1 model of non-small cell lung cancer

•

PLAG effectively inhibited excessive growth of LLC1 cells in an NSCLC model.

•

PLAG inhibited tumor growth by inducing adenosine 2B receptor (A2BR) degradation.

•

Unlike antagonists, PLAG terminates rather than suppresses signaling pathways.

•

A2BR degradation by PLAG occurs through expression and re-localization of TXNIP.

Extracellular adenosine in the tumor microenvironment plays a vital role in cancer development. Specifically, activation of adenosine receptors affects tumor cell growth and adenosine release.

We examined the anti-tumor efficacy of 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) in animal models, revealing the role of PLAG in inhibiting tumor progression by promoting the degradation of adenosine 2B receptors (A2BRs) in tumors. PLAG induced the expression of thioredoxin-interacting protein (TXNIP), a type of α-arrestin that accelerates A2BR internalization by interacting with A2BR complexes containing β-arrestin. Engulfed receptors bound to TXNIP were rapidly degraded after E3 ligase recruitment and ubiquitination, resulting in early termination of intracellular signals that promote tumor overgrowth. However, in control cancer cells, A2BRs bound to protein phosphatase 2A and were returned to the cell membrane instead of being degraded, resulting in continuous receptor-mediated signaling by pathways including the Raf-Erk axis, which promotes tumor proliferation. A TXNIP-silenced cell-implanted mouse model and TXNIP knockout (KO) mice were used to verify that PLAG-mediated suppression of tumor progression is dependent on TXNIP expression. Increased tumor growth was observed in TXNIP-silenced cell-implanted mice, and the anti-tumor effects of PLAG, including delayed tumor overgrowth, were greatly reduced. However, the anti-tumor effects of PLAG were observed in cancer cell-implanted TXNIP-KO mice, which indicates that PLAG produces anti-tumor effects by enhancing TXNIP expression in tumor cells.

These essential functions of PLAG, including delaying tumor growth via A2BR degradation, suggest innovative directions for anticancer drug development.

Self-replicating vehicles based on negative strand RNA viruses

Self-replicating RNA viruses have been engineered as efficient expression vectors for vaccine development for infectious diseases and cancers. Moreover, self-replicating RNA viral vectors, particularly oncolytic viruses, have been applied for cancer therapy and immunotherapy. Among negative strand RNA viruses, measles viruses and rhabdoviruses have been frequently applied for vaccine development against viruses such as Chikungunya virus, Lassa virus, Ebola virus, influenza virus, HIV, Zika virus, and coronaviruses. Immunization of rodents and primates has elicited strong neutralizing antibody responses and provided protection against lethal challenges with pathogenic viruses. Several clinical trials have been conducted. Ervebo, a vaccine based on a vesicular stomatitis virus (VSV) vector has been approved for immunization of humans against Ebola virus. Different types of cancers such as brain, breast, cervical, lung, leukemia/lymphoma, ovarian, prostate, pancreatic, and melanoma, have been the targets for cancer vaccine development, cancer gene therapy, and cancer immunotherapy. Administration of measles virus and VSV vectors have demonstrated immune responses, tumor regression, and tumor eradication in various animal models. A limited number of clinical trials have shown well-tolerated treatment, good safety profiles, and dose-dependent activity in cancer patients.