Loss of a Negative Feedback Loop between IRF8 and AR Promotes Prostate Cancer Growth and Enzalutamide Resistance

The multiple roles of interferon regulatory factor family in health and disease

Interferon Regulatory Factors (IRFs), a family of transcription factors, profoundly influence the immune system, impacting both physiological and pathological processes. This review explores the diverse functions of nine mammalian IRF members, each featuring conserved domains essential for interactions with other transcription factors and cofactors. These interactions allow IRFs to modulate a broad spectrum of physiological processes, encompassing host defense, immune response, and cell development. Conversely, their pivotal role in immune regulation implicates them in the pathophysiology of various diseases, such as infectious diseases, autoimmune disorders, metabolic diseases, and cancers. In this context, IRFs display a dichotomous nature, functioning as both tumor suppressors and promoters, contingent upon the specific disease milieu. Post-translational modifications of IRFs, including phosphorylation and ubiquitination, play a crucial role in modulating their function, stability, and activation. As prospective biomarkers and therapeutic targets, IRFs present promising opportunities for disease intervention. Further research is needed to elucidate the precise mechanisms governing IRF regulation, potentially pioneering innovative therapeutic strategies, particularly in cancer treatment, where the equilibrium of IRF activities is of paramount importance.

PAX6 promotes neuroendocrine phenotypes of prostate cancer via enhancing MET/STAT5A-mediated chromatin accessibility

BACKGROUND

Neuroendocrine prostate cancer (NEPC) is a lethal subset of prostate cancer which is characterized by neuroendocrine differentiation and loss of androgen receptor (AR) signaling. Growing evidence reveals that cell lineage plasticity is crucial in the failure of NEPC therapies. Although studies suggest the involvement of the neural transcription factor PAX6 in drug resistance, its specific role in NEPC remains unclear.

METHODS

The expression of PAX6 in NEPC was identified via bioinformatics and immunohistochemistry. CCK8 assay, colony formation assay, tumorsphere formation assay and apoptosis assay were used to illustrate the key role of PAX6 in the progression of in vitro. ChIP and Dual-luciferase reporter assays were conducted to confirm the binding sequences of AR in the promoter region of PAX6, as well as the binding sequences of PAX6 in the promoter regions of STAT5A and MET. For in vivo validation, the xenograft model representing NEPC subtype underwent pathological analysis to verify the significant role of PAX6 in disease progression. Complementary diagnoses were established through public clinical datasets and transcriptome sequencing of specific cell lines. ATAC-seq was used to detect the chromatin accessibility of specific cell lines.

RESULTS

PAX6 expression was significantly elevated in NEPC and negatively regulated by AR signaling. Activation of PAX6 in non-NEPC cells led to NE trans-differentiation, while knock-down of PAX6 in NEPC cells inhibited the development and progression of NEPC. Importantly, loss of AR resulted in an enhanced expression of PAX6, which reprogramed the lineage plasticity of prostate cancer cells to develop NE phenotypes through the MET/STAT5A signaling pathway. Through ATAC-seq, we found that a high expression level of PAX6 elicited enhanced chromatin accessibility, mainly through attenuation of H4K20me3, which typically causes chromatin silence in cancer cells.

CONCLUSION

This study reveals a novel neural transcription factor PAX6 could drive NEPC progression and suggest that it might serve as a potential therapeutic target for the management of NEPC.

Emerging proteins involved in castration‑resistant prostate cancer via the AR‑dependent and AR‑independent pathways (Review)

Despite achieving optimal initial responses to androgen deprivation therapy, most patients with prostate cancer eventually progress to a poor prognosis state known as castration‑resistant prostate cancer (CRPC). Currently, there is a notable absence of reliable early warning biomarkers and effective treatment strategies for these patients. Although androgen receptor (AR)‑independent pathways have been discovered and acknowledged in recent years, the AR signaling pathway continues to play a pivotal role in the progression of CRPC. The present review focuses on newly identified proteins within human CRPC tissues. These proteins encompass both those involved in AR‑dependent and AR‑independent pathways. Specifically, the present review provides an in‑depth summary and analysis of the emerging proteins within AR bypass pathways. Furthermore, the significance of these proteins as potential biomarkers and therapeutic targets for treating CRPC is discussed. Therefore, the present review offers valuable theoretical insights and clinical perspectives to comprehensively enhance the understanding of CRPC.

The crosstalk between ubiquitination and endocrine therapy

Endocrine therapy (ET), also known as hormone therapy, refers to the treatment of tumors by regulating and changing the endocrine environment and hormone levels. Its related mechanism is mainly through reducing hormone levels and blocking the binding of hormones to corresponding receptors, thus blocking the signal transduction pathway to stimulate tumor growth. However, with the application of ET, some patients show resistance to ET, which is attributed to abnormal accumulation of hormone receptors (HRs) and the production of multiple mutants of HRs. The targeted degradation of abnormal accumulation protein mediated by ubiquitination is an important approach that regulates the protein level and function of intracellular proteins in eukaryotes. Here, we provide a brief description of the traditional and novel drugs available for ET in this review. Then, we introduce the link between ubiquitination and ET. In the end, we elaborate the clinical application of ET combined with ubiquitination-related molecules. KEY MESSAGES: • A brief description of the traditional and novel drugs available for endocrine therapy (ET). • The link between ubiquitination and ET. • The clinical application of ET combined with ubiquitination-related molecules.

Effects of icariin and curcumol on autophagy, ferroptosis, and lipid metabolism based on miR-7/m-TOR/SREBP1 pathway on prostate cancer

This study aimed to investigate the effects and underlying molecular mechanisms of icariin (ICA) and curcumol on autophagy, ferroptosis, and lipid metabolism in prostate cancer (PCa), in vitro and in vivo. Normal prostate epithelial cells RWPE-1 and PCa cell lines DU145 and PC-3 were treated with ICA and curcumol. Ferrostatin-1 (Fer-1) or 3-MA was added to treat DU145 and PC-3 cells. In addition, we knocked down miR-7. The mechanism of ICA and curcumol in PCa cells after the knockdown of miR-7 was verified by in vitro nude mice tumorigenesis experiments. ICA and curcumol had no significant effect on the viability of RWPE-1 cells, but there was a significant difference between DU145 and PC-3 cells. After treatment with ICA and curcumol, the proliferation of PCa cells was inhibited, apoptosis, reactive oxygen species (ROS) levels, and miR-7 expression were increased. The combined treatment of ICA and curcumol had a more significant effect. ICA and curcumol treatment induced autophagy and ferroptosis in PCa cells, and si-miR-7 reversed the effects of ICA and curcumol on autophagy and ferroptosis. MiR-7 targeted mTOR and regulated the expression of the mTOR/SREBP1 pathway in PCa cells. ICA and curcumol may affect the lipid metabolism of PCa cells by affecting SREBP1. In addition, the effects and mechanisms of ICA and curcumol on autophagy, ferroptosis, and lipid metabolism in PCa cells were verified in vivo. ICA and curcumol synergistically regulated the miR-7/mTOR/SREBP1 pathway to induce autophagy and ferroptosis in PCa cells and affected lipid metabolism.

IRF8: Mechanism of Action and Health Implications

Interferon regulatory factor 8 (IRF8) is a transcription factor of the IRF protein family. IRF8 was originally identified as an essentialfactor for myeloid cell lineage commitment and differentiation. Deletion of Irf8 leads to massive accumulation of CD11b+Gr1+ immature myeloid cells (IMCs), particularly the CD11b+Ly6Chi/+Ly6G- polymorphonuclear myeloid-derived suppressor cell-like cells (PMN-MDSCs). Under pathological conditions such as cancer, Irf8 is silenced by its promoter DNA hypermethylation, resulting in accumulation of PMN-MDSCs and CD11b+ Ly6G+Ly6Clo monocytic MDSCs (M-MDSCs) in mice. IRF8 is often silenced in MDSCs in human cancer patients. MDSCs are heterogeneous populations of immune suppressive cells that suppress T and NK cell activity to promote tumor immune evasion and produce growth factors to exert direct tumor-promoting activity. Emerging experimental data reveals that IRF8 is also expressed in non-hematopoietic cells. Epithelial cell-expressed IRF8 regulates apoptosis and represses Osteopontin (OPN). Human tumor cells may use the IRF8 promoter DNA methylation as a mechanism to repress IRF8 expression to advance cancer through acquiring apoptosis resistance and OPN up-regulation. Elevated OPN engages CD44 to suppress T cell activation and promote tumor cell stemness to advance cancer. IRF8 thus is a transcription factor that regulates both the immune and non-immune components in human health and diseases.

rAAV-delivered PTEN therapeutics for prostate cancer

Effective treatments for prostate cancer (PCa) require further development, and previous studies have reported that PTEN and its downstream target CDKN1B are significantly downregulated in PCa cells compared with normal cells. Therefore, modulation of PTEN and CDKN1B expression might be a promising therapeutic approach for PCa treatment. Expression of PTEN and CDKN1B was verified in specimens from PCa patients and transgenic adenocarcinoma mouse prostate (TRAMP) mice. The effect of PTEN on PCa cell migration, apoptosis, and the cell cycle was analyzed in vitro using a wound-healing assay and flow cytometry. We assessed the ability of intraprostatic and intratumoral injections of recombinant adeno-associated virus (rAAV) 9 expressing Pten or Cdkn1b into TRAMP mice and a subcutaneous tumor xenograft mouse model, respectively, to inhibit PCa progression. PTEN and CDKN1B were significantly downregulated in human and mouse PCa samples, and CDKN1B expression correlated positively with PTEN expression. PTEN overexpression significantly inhibited cell migration and cell-cycle progression and promoted apoptosis in PCa cells by decreasing Ccnd1 expression and increasing that of Cdkn1b. Importantly, treatment with the rAAV9.Pten or rAAV9.Cdkn1b extended the lifespan of TRAMP mice and inhibited the growth rate of tumor xenografts by regulating downstream gene expression. Moreover, neoplasia in treated prostates was significantly diminished compared with that in control prostates, and apoptosis was markedly observed in xenografts treated with Pten or Cdkn1b. These data indicate that rAAV-based PTEN/CDKN1B delivery is promising for the development of novel therapeutics for PCa.

Transforming growth factor-beta (TGF-β) in prostate cancer: A dual function mediator?

Transforming growth factor-beta (TGF-β) is a member of a family of secreted cytokines with vital biological functions in cells. The abnormal expression of TGF-β signaling is a common finding in pathological conditions, particularly cancer. Prostate cancer (PCa) is one of the leading causes of death among men. Several genetic and epigenetic alterations can result in PCa development, and govern its progression. The present review attempts to shed some light on the role of TGF-β signaling in PCa. TGF-β signaling can either stimulate or inhibit proliferation and viability of PCa cells, depending on the context. The metastasis of PCa cells is increased by TGF-β signaling via induction of EMT and MMPs. Furthermore, TGF-β signaling can induce drug resistance of PCa cells, and can lead to immune evasion via reducing the anti-tumor activity of cytotoxic T cells and stimulating regulatory T cells. Upstream mediators such as microRNAs and lncRNAs, can regulate TGF-β signaling in PCa. Furthermore, some pharmacological compounds such as thymoquinone and valproic acid can suppress TGF-β signaling for PCa therapy. TGF-β over-expression is associated with poor prognosis in PCa patients. Furthermore, TGF-β up-regulation before prostatectomy is associated with recurrence of PCa. Overall, current review discusses role of TGF-β signaling in proliferation, metastasis and therapy response of PCa cells and in order to improve knowledge towards its regulation, upstream mediators of TGF-β such as non-coding RNAs are described. Finally, TGF-β regulation and its clinical application are discussed.

Toll-Like Receptors Serve as Biomarkers for Early Diagnosis and Prognosis Assessment of Kidney Renal Clear Cell Carcinoma by Influencing the Immune Microenvironment: Comprehensive Bioinformatics Analysis Combined With Experimental Validation

Background: Toll-like receptors (TLRs) are important initiators of innate and acquired immune responses. However, its role in kidney renal clear cell carcinoma (KIRC) remains unclear.

Methods: TLRs and their relationships with KIRC were studied in detail by ONCOMINE, UALCAN, GEPIA, cBioPortal, GeneMANIA, FunRich, LinkedOmics, TIMER and TRRUST. Moreover, we used clinical samples to verify the expressions of TLR3 and TLR4 in early stage of KIRC by real-time fluorescence quantitative polymerase chain reaction (RT-qPCR), flow cytometry (FC) and immunohistochemistry (IHC).

Results: The expression levels of TLRs in KIRC were generally different compared with adjacent normal tissues. Moreover, the expressions of TLR3 and TLR4 elevated significantly in the early stage of KIRC. Overexpressions of TLR1, TLR3, TLR4 and TLR8 in KIRC patients were associated with longer overall survival (OS), while inhibition of TLR9 expression was related to longer OS. Additionally, overexpressions of TLR1, TLR3 and TLR4 in KIRC patients were associated with longer disease free survival (DFS). There were general genetic alterations and obvious co-expression correlation of TLRs in KIRC. The PPI network between TLRs was rather complex, and the key gene connecting the TLRs interaction was MYD88. The GO analysis and KEGG pathway analysis indicated that TLRs were closely related to adaptive immunity, innate immunity and other immune-related processes. RELA, NFKB1, IRF8, IRF3 and HIF1A were key transcription factors regulating the expressions of TLRs. What’s more, the expression levels of all TLRs in KIRC were positively correlated with the infiltration levels of dendritic cells, macrophages, neutrophils, B cells, CD4⁺ T cells and CD8⁺ T cells. Finally, the results of RT-qPCR, FC and IHC confirmed that TLR3 and TLR4 were significantly elevated in the early stage of KIRC.

Conclusion: The occurrence and development of KIRC are closely related to TLRs, and TLRs have the potential to be early diagnostic biomarkers of KIRC and biomarkers for judging the prognosis and immune status of KIRC. This study may provide new insights into the selection of KIRC immunotherapy targets.

IRF7 inhibits the Warburg effect via transcriptional suppression of PKM2 in osteosarcoma

Osteosarcoma (OS) is a malignant bone tumor among adolescents and young adults. IRF7 belongs to the transcription factor family of interferon regulatory factors (IRFs) and has previously been described to function as a tumor suppressor in multiple cancer types. However, the biological functions and cellular mechanism of IRF7 in OS remain elusive. In this study, by quantitative real-time PCR (qRT-PCR) and western blotting, we found that IRF7 was downregulated in OS, and the higher expression of IRF7 was correlated with a better survival prognosis. Moreover, loss-of-function and gain-of-function studies have proved the critical functions of IRF7 in suppressing aerobic glycolysis of osteosarcoma cells as evidenced by glucose uptake, lactate production, extracellular acidification rate, and oxygen consumption rate. Mechanistically, IRF7 inhibited the expression of key glycolytic gene PKM2 via direct transcriptional regulation. Moreover, the in vitro and in vivo tumor-suppressive roles of IRF7 were uncovered in OS and these effects were largely glycolysis-dependent. Therefore, our study unveils a previous unprecedented role of IRF7 in glucose metabolism reprogram and suggests that IRF7 might serve as a potential therapeutic target for patients with OS.

A novel pyroptosis-related gene signature to predict outcomes in laryngeal squamous cell carcinoma

Pyroptosis, a pro-inflammatory form of programmed cell death, is associated with carcinogenesis and progression. However, there is little information concerning pyroptosis-related genes (PRGs) in laryngeal squamous cell carcinoma (LSCC). Herein, we aim to explore the prognostic value of PRGs in LSCC. The expression and clinical data of 47 PRGs in LSCC patients were obtained from The Cancer Genome Atlas. A novel prognostic PRG signature was constructed using least absolute shrinkage and selection operator analysis. Receiver operating characteristic (ROC) curves were drawn, and Kaplan-Meier survival Cox proportional hazard regression analyses were performed to measure the predictive capacity of the PRG signature. Furthermore, we constructed a six-PRG signature to divide LSCC patients into high- and low-risk groups. Patients in the high-risk group had worse overall survival than the low-risk group. The area under the time-dependent ROC curve was 0.696 for 1 year, 0.784 for 3 years, and 0.738 for 5 years. We proved that the PRGs signature was an independent predictor for LSCC. Functional enrichment analysis indicated that several immune-related pathways were significantly enriched in the low-risk group. Consistent with this, patients with low-risk scores had higher immune scores and better immunotherapeutic responses than the high-risk group. In conclusion, we established a novel PRGs signature that can predict outcome and response to immunotherapy of LSCC, pyroptosis may be a potential target for LSCC.

Curcumol inhibits the malignant progression of prostate cancer and regulates the PDK1/AKT/mTOR pathway by targeting miR‑9

Curcumol has been reported to exert anti-tumor activity, but its intrinsic molecular mechanism in prostate cancer remains to be elucidated. The present study aimed to analyze the effect of curcumol on prostate cancer and identify its possible internal regulatory pathway using in vitro cell culture and in vivo tumor model experiments. The cytotoxicity of curcumol was detected using a Cell Counting Kit-8 assay and it was found that curcumol had no obvious toxicity or side effects on RWPE-1 cells. Wound healing, Transwell and flow cytometry assays demonstrated that curcumol could affect the activity of PC3 cells. The luciferase reporter assay also indicated that microRNA (miR)-9 could directly target pyruvate dehydrogenase kinase 1 (PDK1). After PC3 cells were transfected with miR-9 inhibitor or treated with curcumol, the expression levels of the PDK1/AKT/mTOR signaling pathway-related proteins [PDK1, phosphorylated (p)-AKT and p-mTOR] were increased or decreased, respectively. Next, the prostate cancer cell xenograft model was established. Tumor size and the expression levels of PDK1/AKT/mTOR signaling pathway-related factors were altered following treatment with curcumol. The in vitro and in vivo experiments collectively demonstrated that curcumol could inhibit the PDK1/AKT/mTOR signaling pathway by upregulating the expression level of miR-9. The present study found that curcumol regulates the PDK1/AKT/mTOR signaling pathway via miR-9 and affects the development of prostate cancer. These findings could provide a possible scientific insight for research into treatments for prostate cancer.

Hepatic interferon regulatory factor 8 expression mediates liver ischemia/reperfusion injury in mice

Hepatic ischemia/reperfusion (I/R) injury is an inevitable complication of hepatic surgery occasioned by liver transplantation and resection. The progression from liver ischemia to reperfusion injury is accompanied by abnormal metabolism, Kupffer cell activation, neutrophil recruitment and the release of cytokines. Activation of several interferon regulatory factors (IRFs) has been reported to either enhance or restrict I/R progression, but the role of IRF8 in the regulation of I/R injury progression is still unknown. In this study, we explore the IRF8 function in the I/R-mediated liver injury using overexpressed hepatic IRF8 and knockout mice. According to our results, IRF8 knockout mice had significantly lower inflammatory cells infiltration, inflammatory cytokines release and serum aspartate aminotransferase/alanine aminotransferase levels that improved the necrotic injury after I/R, unlike the control mice. Conversely, the overexpression of IRF8 in WT mice markedly aggravated the liver structure damage and its abnormal function. We further showed that IRF8-mediated inflammatory cells infiltration were partly dependent on early autophagy and NF-κΒ signal pathway during I/R. AAV8-IRF8-I/R mice pretreated with autophagy inhibitor hydroxychloroquine and NF-κΒ signal pathway inhibitor secukinumab could drastically reverse the IRF8-mediated increase of neutrophil infiltration and chemokine release at different degrees. This work uncovered a critical role of IRF8 in the modulation of the hepatic microenvironment and as a potential target in the initial treatment of I/R injury.

Mechanisms of enzalutamide resistance in castration-resistant prostate cancer and therapeutic strategies to overcome it

Prostate cancer is the second most common malignancy in men and androgen deprivation therapy is the first-line therapy. However, most cases will eventually develop castration-resistant prostate cancer after androgen deprivation therapy treatment. Enzalutamide is a second-generation androgen receptor antagonist approved by the Food and Drug Administration to treat patients with castration-resistant prostate cancer. Unfortunately, patients receiving enzalutamide treatment will ultimately develop resistance via various complicated mechanisms. This review examines the emerging information on these resistance mechanisms, including androgen receptor-related signalling pathways, glucocorticoid receptor-related pathways and metabolic effects. Notably, lineage plasticity and phenotype switching, gene polymorphisms and the relationship between microRNAs and drug resistance are addressed. Furthermore, potential therapeutic strategies for enzalutamide-resistant castration-resistant prostate cancer treatment are suggested, which can help discover more effective and specific regimens to overcome enzalutamide resistance.