CXCR4 blockade sensitizes osteosarcoma to doxorubicin by inducing autophagic cell death via PI3K‑Akt‑mTOR pathway inhibition

Blocking CXCR4-CARM1-YAP axis overcomes osteosarcoma doxorubicin resistance by suppressing aerobic glycolysis

Osteosarcoma, recognized for its aggressiveness and resistance to chemotherapy, notably doxorubicin, poses significant treatment challenges. This comprehensive study investigated the CXCR4-CARM1-YAP signaling axis and its pivotal function in controlling aerobic glycolysis, which plays a crucial role in doxorubicin resistance. Detailed analysis of Dox-resistant 143b/MG63-DoxR cells has uncovered the overexpression of CXCR4. Utilizing a combination of molecular biology techniques including gene silencing, aerobic glycolysis assays such as Seahorse experiments, RNA sequencing, and immunofluorescence staining. The study provides insight into the mechanistic pathways involved. Results demonstrated that disrupting CXCR4 expression sensitizes cells to doxorubicin-induced apoptosis and alters glycolytic activity. Further RNA sequencing revealed that CARM1 modulated this effect through its influence on glycolysis, with immunofluorescence of clinical samples confirming the overexpression of CXCR4 and CARM1 in drug-resistant tumors. Chromatin immunoprecipitation studies further highlighted the role of CARM1, showing it to be regulated by methylation at the H3R17 site, which in turn affected YAP expression. Crucially, in vivo experiments illustrated that CARM1 overexpression could counteract the tumor growth suppression that resulted from CXCR4 inhibition. These insights revealed the intricate mechanisms at play in osteosarcoma resistance to doxorubicin and pointed toward potential new therapeutic strategies that could target this metabolic and signaling network to overcome drug resistance and improve patient outcomes.

CXCR4 Expression as a Prognostic Biomarker in Soft Tissue Sarcomas

Poor long-term survival in localized high-risk soft tissue sarcomas (STSs) of the extremities and trunk highlights the need to identify new prognostic factors. CXCR4 is a chemokine receptor involved in tumor progression, angiogenesis, and metastasis. The aim of this study was to evaluate the association between CXCR4 expression in tumor tissue and survival in STSs patients treated with neoadjuvant therapy. CXCR4 expression was retrospectively determined by immunohistochemical analysis in serial specimens including initial biopsies, tumors post-neoadjuvant treatment, and tumors after relapse. We found that a positive cytoplasmatic expression of CXCR4 in tumors after neoadjuvant treatment was a predictor of poor recurrence-free survival (RFS) (p = 0.003) and overall survival (p = 0.019) in synovial sarcomas. We also found that positive nuclear CXCR4 expression in the initial biopsies was associated with poor RFS (p = 0.022) in undifferentiated pleomorphic sarcomas. In conclusion, our study adds to the evidence that CXCR4 expression in tumor tissue is a promising prognostic factor for STSs.

Engineering Bimetallic Polyphenol for Mild Photothermal Osteosarcoma Therapy and Immune Microenvironment Remodeling by Activating Pyroptosis and cGAS-STING Pathway

The immunosuppressive tumor microenvironment (ITME) of osteosarcoma (OS) poses a significant obstacle to the efficacy of existing immunotherapies. Despite the attempt of novel immune strategies such as immune checkpoint inhibitors and tumor vaccines, their effectiveness remains suboptimal due to the inherent difficulty in mitigating ITME simultaneously from both the tumor and immune system. The promotion of anti-tumor immunity through the induction of immunogenic cell death and activation of the cGAS-STING pathway has emerged as potential strategies to counter the ITME and stimulate systemic antitumor immune responses. Here, a bimetallic polyphenol-based nanoplatform (Mn/Fe-Gallate nanoparticles coated with tumor cell membranes is presented, MFG@TCM) which combines with mild photothermal therapy (PTT) for reversing ITME via simultaneously inducing pyroptosis in OS cells and activating the cGAS-STING pathway in dendritic cells (DCs). The immunostimulatory pathways, through the syngeneic effect, exerted a substantial positive impact on promoting the secretion of damage-associated molecular patterns (DAMPs) and proinflammatory cytokines, which favors remodeling the immune microenvironment. Consequently, effector T cells led to a notable antitumor immune response, effectively inhibiting the growth of both primary and distant tumors. This study proposes a new method for treating OS using mild PTT and immune mudulation, showing promise in overcoming current treatment limitations.

Blockade of CXCR4 promotes macrophage autophagy through the PI3K/AKT/mTOR pathway to alleviate coronary heart disease

OBJECTIVE

Autophagy is important in regulating inflammation and cholesterol efflux, suggesting that targeting autophagy may slow down atherosclerosis (AS). Since the pathological basis of coronary artery disease (CAD) is atherosclerosis, it is crucial to investigate the role of autophagy in atherosclerosis. This study aimed to investigate the role of the chemokine CXC chemokine receptor 4 (CXCR4) in promoting macrophage autophagy through the phosphoinositide-3 kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway to alleviate coronary artery disease.

METHODS

The human left coronary artery and myocardium were collected to detect CXCR4, MAP1LC3(LC3) and SQSTM1(p62) expression. ApoE-/- mice were used to establish an atherosclerosis mice model, while human monocytes (THP-1) were used to establish a foam cell model and co-cultured with foam cells using siRNACXCR4. Western blotting was conducted to quantify CXCR4, PI3K/AKT/mTOR pathway protein, LC3, Beclin1 and p62 protein levels. The left coronary artery from humans and mouse aorta and myocardium were stained with Hematoxylin and Eosin (H&E), macrophages with Oil Red O staining and foam cells were assessed by Movat's staining. CXCR4 levels, PI3K/AKT/mTOR pathway protein, LC3 and p62 were detected by immunohistochemistry (IHC) and immunofluorescence assays. Detection of autophagosomes in macrophages using transmission electron microscopy. We further assessed whether the effect of CXCR4-mediated macrophage autophagy on the formation of atherosclerosis and structural changes in the myocardium was mediated via the PI3K/AKT/mTOR signaling pathway.

RESULTS

CXCR4 and p62 proteins were upregulated in human coronary lesions, mouse aorta, myocardial tissue, and foam cells, while LC3II/LC3I was downregulated. p85 (P-PI3K), Ser473 (P-AKT), and Ser2448 (P-mTOR) phosphorylated proteins associated with the PI3K/AKT/mTOR pathway were detected in AS and foam cell models. Upregulated CXCR4 inhibited autophagy of macrophages and increased the severity of atherosclerotic lesions. After specific knockdown of CXCR4 by adeno-associated virus (AAV9-CXCR4-RNAi) and siRNACXCR4, the above indicators were reversed, macrophage autophagy was promoted, the severity of atherosclerotic lesions was reduced, and the disorganized arrangement of myocardial architecture was improved.

CONCLUSION

Knockdown of CXCR4 reduces the extent of coronary artery disease by promoting macrophage autophagy through the PI3K/AKT/mTOR pathway to attenuate atherosclerosis.

New emerging targets in osteosarcoma therapy: PTEN and PI3K/Akt crosstalk in carcinogenesis

Osteosarcoma (OS) is a malignant bone carcinoma that affects people in childhood and adulthood. The heterogeneous nature and chromosomal instability represent certain characteristics of OS cells. These cancer cells grow and migrate abnormally, making the prognosis undesirable for patients. Conventional and current treatments fail to completely eradicate tumor cells, so new therapeutics targeting genes may be considered. PI3K/Akt is a regulator of events such as growth, cell death, migration, and differentiation, and its expression changes during cancer progression. PTEN reduces PI3K/Akt expression, and its mutations and depletions have been reported in various tumors. Experimental evidence shows that there is upregulation of PI3K/Akt and downregulation of PTEN in OS. Increasing PTEN expression may suppress PI3K/Akt to minimize tumorigenesis. In addition, PI3K/Akt shows a positive association with growth, metastasis, EMT and metabolism of OS cells and inhibits apoptosis. Importantly, overexpression of PI3K/Akt causes drug resistance and radio-resistance and its level can be modulated by miRNAs, lncRNAs and circRNAs. Silencing PI3K/Akt by compounds and drugs can suppress OS. Here, we review in detail the function of the PTEN/PI3K/Akt in OS, revealing its biological function, function in tumor progression, resistance to therapy, and pharmacological significance.

ANXA2 and Rac1 negatively regulates autophagy and osteogenic differentiation in osteosarcoma cells to confer CDDP resistance

BACKGROUND

Cisplatin (CDDP) is a mainstay chemotherapeutic agent for OS treatment, but drug resistance has become a hurdle to limit its clinical effect. Autophagy plays an important role in CDDP resistance in OS, and in the present study we explored the role of ANXA2 and Rac1 in dictating CDDP sensitivity in OS cells.

METHODS

ANXA2 and Rac1 expression levels were examined by Western blot and autophagy induction was detected by transmission electron miscroscope (TEM) in the clinical samples and OS cell lines. CDDP resistant cells were established by exposing OS cells to increasing doses of CDDP. The effects of ANXA2 and Rac1 knockdown on CDDP sensitivity were evaluated in the cell and animal models.

RESULTS

Reduced autophagy was associated with the increased expression of ANXA2 and Rac1 in CDDP resistant OS tumor samples and cells. Autophagy suppression promoted CDDP resistance and inducing autophagy re-sensitized the resistant cells to CDDP treatment in vitro and in vivo. Further, knocking down ANXA2 or Rac1 re-activated autophagy and attenuated CDDP resistance in OS cells. We further demonstrated that CDDP resistant OS cells displayed a poorer osteogenic differentiation state when compared to the parental cell lines, which was significantly reversed by autophagy re-activation and ANXA2 or Rac1 silencing.

CONCLUSION

Our findings revealed a complicated interplay of ANXA2/Rac1, autophagy induction, and osteogenic differentiation in dictating CDDP resistance in OS cells, suggesting ANXA2 and Rac1 as promising targets to modulate autophagy and overcome CDDP resistance in OS cells.

Functional role of MicroRNA/PI3K/AKT axis in osteosarcoma

Osteosarcoma (OS) is a primary malignant bone tumor that occurs in children and adolescents, and the PI3K/AKT pathway is overactivated in most OS patients. MicroRNAs (miRNAs) are highly conserved endogenous non-protein-coding RNAs that can regulate gene expression by repressing mRNA translation or degrading mRNA. MiRNAs are enriched in the PI3K/AKT pathway, and aberrant PI3K/AKT pathway activation is involved in the development of osteosarcoma. There is increasing evidence that miRNAs can regulate the biological functions of cells by regulating the PI3K/AKT pathway. MiRNA/PI3K/AKT axis can regulate the expression of osteosarcoma-related genes and then regulate cancer progression. MiRNA expression associated with PI3K/AKT pathway is also clearly associated with many clinical features. In addition, PI3K/AKT pathway-associated miRNAs are potential biomarkers for osteosarcoma diagnosis, treatment and prognostic assessment. This article reviews recent research advances on the role and clinical application of PI3K/AKT pathway and miRNA/PI3K/AKT axis in the development of osteosarcoma.

Autophagy and its role in osteosarcoma

Osteosarcoma (OS) is the most common bone malignancy and preferably occurs in children and adolescents. Despite significant advances in surgery and chemotherapy for OS over the past few years, overall survival rates of OS have reached a bottleneck. Thus, extensive researches aimed at developing new therapeutic targets for OS are urgently needed. Autophagy, a conserved process which allows cells to recycle altered or unused organelles and cellular components, has been proven to play a critical role in multiple biological processes in OS. In this article, we summarized the association between autophagy and proliferation, metastasis, chemotherapy, radiotherapy, and immunotherapy of OS, revealing that autophagy-related genes and pathways could serve as potential targets for OS therapy.

HIF-1α mediates CXCR4 transcription to activate the AKT/mTOR signaling pathway and augment the viability and migration of activated B cell-like diffuse large B-cell lymphoma cells

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoid malignancy with a high relapse rate. We previously found that C-X-C motif chemokine receptor 4 (CXCR4) was highly expressed in DLBCL and associated with poor prognosis. This study focused on the effect of hypoxia-inducible factor-1α (HIF-1α) on CXCR4 expression and the DLBCL progression. Two activated B cell-like DLBCL cell lines Ly-3 and SUDHL2 were transfected with overexpression and knockdown plasmids or HIF-1α. The viability and migration of DLBCL cells were significantly increased under hypoxic conditions, or upon HIF-1α overexpression under normoxic conditions, but the HIF-1α downregulation led to inverse trends. However, the promoting effects of HIF-1α overexpression on DLBCL cells were suppressed by Plerixafor (a CXCR4 inhibitor). The luciferase and chromatin immunoprecipitation assays revealed that HIF-1α bound to the functional site HRE1 on CXCR4 promoter to activate its transcription. HIF-1α-mediated CXCR4 activation further led to increased phosphorylation of AKT/mTOR under hypoxic conditions. Taken together, this work reports that HIF-1α promotes viability and migration of activated B cell-like cells under hypoxia, which might involve the transcription of CXCR4 and the activation of the AKT/mTOR pathway. The finding may provide novel lights in the management of DCBCL.