SPOP mutations promote tumor immune escape in endometrial cancer via the IRF1-PD-L1 axis

The role of DDIT3 in modulating proliferation and tamoxifen resistance in luminal A subtype breast cancer through the DDIT3-IRF1 axis

BACKGROUND

This study investigates the role of DNA Damage Inducible Transcript 3 (DDIT3) in luminal A subtype breast cancer (LABC). DDIT3, a transcription factor linked to various stress responses, has been implicated in tumorigenesis, yet its specific contributions to LABC biology remain poorly understood.

METHODS

To elucidate these functions, we utilized bioinformatics analyses, including data from TCGA and Kaplan-Meier databases. Furthermore, we performed siRNA-mediated knockdown and overexpression experiments in MCF-7 and T47D cells to assess DDIT3's functional impact on cell proliferation, drug resistance, etc. RNA sequencing analysis identified differentially expressed genes (DEGs) associated with DDIT3 manipulation, and pinpointing the crucial downstream target with rescue experiment.

RESULTS

Compared to normal breast tissue, DDIT3 is lowly expressed in LABC, and LABC patients with low DDIT3 expression have a lower survival rate, indicating relatively poor prognosis. Furthermore, DDIT3 negatively regulates the proliferation of LABC cells, also negatively correlated with the sensitivity of TAM. RNA-seq result and rescue experiment identified the interferon regulatory factor 1 (IRF1) as a crucial downstream target of DDIT3 to regulating LABC cell proliferation and tamoxifen (TAM) resistance.

CONCLUSIONS

DDIT3 is negatively correlated with poor prognosis in LABC patients. And DDIT3 may negatively regulate the proliferation and TAM sensitivity in LABC cells through the DDIT3-IRF1 axis.

Molecular mechanism of tumor-infiltrating immune cells regulating endometrial carcinoma

Endometrial carcinoma (EC) is a prevalent gynecological cancer, and its interaction with the immune system is pivotal in cancer progression. This comprehensive review explores the molecular mechanisms involved in the regulation of EC by tumor-infiltrating immune cells. This review discusses the composition and functions of various immune cell types within the tumor microenvironment, including T cells, B cells, macrophages, and natural killer cells, and elucidates their specific roles in cancer control. It also delves into the immune evasion strategies employed by EC cells, with a specific focus on immune checkpoint pathways and their influence on tumor development. Signaling pathways, cytokines, and chemokines mediating immune responses within the tumor microenvironment are also detailed. Furthermore, clinical implications and therapeutic strategies, such as immunotherapies, are also reviewed, and relevant clinical trials are discussed. Additionally, this review discusses the existing gaps in our knowledge, suggests potential avenues for future research, and emphasizes the significance of understanding these mechanisms for enhanced EC treatment. This review provides an exhaustive overview of the current knowledge, supporting the ongoing quest for more effective therapeutic interventions on EC.

miR-186-5p Down-Regulates PD-L1 Level in Acute Myeloid Leukemia Cells and Inhibits Tumorigenesis and Immune Escape

Acute myeloid leukemia (AML) is a malignant tumor of blood cells, which seriously interferes with the generation of normal cells. Although miR-186-5p is diminished in AML, its exact mechanism is not well understood. miR-186-5p and PD-L1 levels in AML cells (HL-60, KG-1, TF-1a, MOLT-3) and subcutaneous tumor tissue were discovered through qRT-PCR and Western blot. miR-186-5 p and PD-L1 combining sites were foreseen by the database and verified by dual luciferase and immunoprecipitation experiments. AML cells with miR-186-5p overexpression or knockdown and PD-L1 overexpression were cocultured with CD4+ and CD8+ T cells. The proliferation, migration, invasion and apoptosis of AML cells, CD8+ and CD4+ T cell growth and apoptosis, and activated markers (Perforin and Granzyme B) and secreted cytokines (IFN-γ, IL-4 and TNF-α) levels were detected by CCK8, Transwell, flow cytometry, CFSE, Western blot and ELISA, respectively. Subcutaneous xenograft magnitude and mass in nude mice were measured. Ki67 level was identified through immunohistochemistry. CD4+ and CD8+ T cell level and infiltration were detected by immunofluorescence and flow cytometry. miR-186-5p was downregulated, and PD-L1 was boosted in AML cells and subcutaneous tumor tissues (p < 0.05), while miR-186-5p targeted down-regulate PD-L1. miR-186-5p upregulation hindered AML cell multiplication, migration, invasion and facilitate cell death, and enhanced the proliferation activity, activation markers (Perforin and Granzyme B) and secreted cytokines (IFN-γ, IL-4, TNF-α) of CD8+ and CD4+ T cells, inhibited apoptosis, and inhibited immune escape (p < 0.05). Knockdown of miR-186-5p can promote AML progression, but PD-L1 upregulation weakens the antitumor impact of miR-186-5p overexpression (p < 0.05). Transplanted tumor mice experiments also found that miR-186-5p hindered PD-L1 and tumor growth (p < 0.05). In conclusion, miR-186-5p can target inhibit PD-L1, suppress AML cells multiplication, movement, invasion and immune escape, and then reduce AML, aiming to provide support and basis for the pathological mechanism and prevention and treatment strategy of AML.

Immune microenvironment and molecular mechanisms in endometrial cancer: implications for resistance and innovative treatments

This review provides a systematic overview of the molecular mechanisms of endometrial cancer and its drug resistance, particularly involving the aberrant activation of some key signaling pathways. These molecular mechanisms significantly affect the therapeutic outcome of endometrial cancer by promoting tumor cell proliferation, anti-apoptosis, and drug resistance. The article also analyzes the critical role of the immune microenvironment in cancer drug resistance, focusing on the impact of immune cells, immune checkpoints, and hypoxic metabolic reprogramming on anticancer therapies. In recent years, immunotherapy and individualized therapy have shown promising clinical outcomes, especially in advanced endometrial cancer. This article summarizes recent advances in related therapeutic strategies and proposes emerging therapeutic strategies by targeting key pathways and modulating the immune microenvironment to overcome drug resistance and improve patient prognosis.

SPOP/NOLC1/B4GALT1 signaling axis enhances paclitaxel resistance in endometrial cancer by inducing O-dysglycosylation

The effective treatment of paclitaxel-resistant patients remains a major challenge. We found that nucleolar and coiled body phosphoprotein 1 (NOLC1) was highly expressed in the paclitaxel-resistant endometrial cancer (ECa) cells and pathological tissue of ECa patients, which could promote the occurrence and progression of ECa cells. Mechanistically, we confirmed that the E3 ubiquitin ligase substrate-binding adaptor SPOP mediates the ubiquitination and degradation of NOLC1, thereby maintaining normal protein levels. However, ECa-associated SPOP mutants abrogated the binding and ubiquitination of NOLC1, resulting in the accumulation of NOLC1, and ultimately promoting the proliferation, migration, and invasion of ECa cells. In addition, we demonstrated that NOLC1 could act as a transcriptional factor to activate the transcriptional expression of B4GALT1, ultimately leading to abnormal glycosylation metabolism. Moreover, knockdown of B4GALT1 can partly counteract the cancer-promoting effect caused by the overexpression of NOLC1 in vitro and in vivo. Based on these findings, an O-glycosylation inhibitor combined with paclitaxel could effectively improve the sensitivity of paclitaxel-resistant cells. In summary, we found that SPOP can negatively regulate the NOLC1-B4GALT1 signaling axis in ECa, whereas ECa-associated SPOP mutants lead to abnormal activation of this signaling axis, leading to glycosylation metabolism disorders. In addition, paclitaxel combined with B4GALT1-KD or glycosylation inhibitors can significantly inhibit the growth of paclitaxel-resistant endometrial cancer cells.

Cul3 substrate adaptor SPOP targets Nup153 for degradation

SPOP is a Cul3 substrate adaptor responsible for the degradation of many proteins related to cell growth and proliferation. Because mutation or misregulation of SPOP drives cancer progression, understanding the suite of SPOP substrates is important to understanding the regulation of cell proliferation. Here, we identify Nup153, a component of the nuclear basket of the nuclear pore complex, as a novel substrate of SPOP. SPOP and Nup153 bind to each other and colocalize at the nuclear envelope and some nuclear foci in cells. The binding interaction between SPOP and Nup153 is complex and multivalent. Nup153 is ubiquitylated and degraded upon expression of SPOPWT but not its substrate binding-deficient mutant SPOPF102C. Depletion of SPOP via RNAi leads to Nup153 stabilization. Upon loss of SPOP activity, the nuclear envelope localization of spindle assembly checkpoint protein Mad1, which is tethered to the nuclear envelope by Nup153, is stronger. Altogether, our results demonstrate that SPOP regulates Nup153 levels and expands our understanding of the role of SPOP in protein and cellular homeostasis.

Expression levels of STAT3, and protein levels of IL‑6 and sPD‑L1 in different pathological characteristics of endometrial adenocarcinomas

Endometrial cancer is a common type of cancer in women, with endometrial adenocarcinoma (EA) being the most common type. Monitoring the expression levels of signal transducer and activator of transcription 3 (STAT3), the protein levels of interleukin 6 (IL-6) and soluble programmed death ligand 1 (sPD-L1), and their differences in patients with various pathological characteristics is beneficial for accurately evaluating the disease stage and differentiation degree of patients in clinical practice. The aim of the present study was to assess the expression levels of STAT3, and the protein levels of IL-6 and sPD-L1 in EA. In the present retrospective study, data were retrieved from the medical records of 137 patients with EA who received surgical treatment at The First Affiliated Hospital of Hebei North University from January 2017 to December 2022. Of the 137 cases, 90 met the inclusion criteria. The patients with EA were matched with a cohort of 30 patients with atypical endometrial hyperplasia in a ratio of 3:1. Among the 90 patients with EA, 30 patients with well-differentiated EA were matched with 30 patients with moderately differentiated EA and 30 patients with poorly differentiated EA in a 1:1:1 ratio. Expression level of STAT3, and protein levels of IL-6 and sPD-L1 were recorded preoperatively and compared between patients with different pathological characteristics [such as differentiation degree, disease stage, depth of myometrial invasion and lymph node metastasis (LNM)] and prognosis. Levels of IL-6, STAT3 and sPD-L1 in the observation group were significantly higher compared with the control group (P<0.001). Additionally, there were significant differences in IL-6, STAT3 and sPD-L1 levels between patients with different differentiation degrees, disease stages, myometrial invasion and LNM (P<0.001). The increase in IL-6, STAT3 and sPD-L1 levels were significantly associated with the decrease in the differentiation degree and the increase in the disease stage, depth of myometrial invasion and LNM (P<0.001). IL-6, STAT3 and sPD-L1 levels in patients with a poor prognosis were significantly higher compared with patients with good prognoses (P<0.001). Overall, the expression levels of STAT3, and the protein levels of IL-6 and sPD-L1 were increased in patients with EA compared with in those without EA, and their increase is associated with the pathological characteristics of the disease. The levels of these indices may be detected in clinical practices to evaluate the disease and predict the prognosis.

Recent advances in developing targeted protein degraders

Targeted protein degradation (TPD) represents a promising therapeutic approach, encompassing several innovative strategies, including but not limited to proteolysis targeting chimeras (PROTACs), molecular glues, hydrophobic tag tethering degraders (HyTTD), and lysosome-targeted chimeras (LYTACs). Central to TPD are small molecule ligands, which play a critical role in mediating the degradation of target proteins. This review summarizes the current landscape of small molecule ligands for TPD molecules. These small molecule ligands can utilize the proteasome, lysosome, autophagy, or hydrophobic-tagging system to achieve the degradation of target proteins. The article mainly focuses on introducing their design principles, application advantages, and potential limitations. A brief discussion on the development prospects and future directions of TPD technology was also provided.

Baicalin attenuates the immune escape of oral squamous cell carcinoma by reducing lactate accumulation in tumor microenvironment

INTRODUCTION

The acidic microenvironment caused by excessive lactate accumulation could inhibit immune lymphocytes antitumor activity and promote the immune escape of tumor cells. Baicalin is an active flavonoid isolated from Scutellaria baicalensis Georgi, a traditional Chinese medicinal herb with antioxidant and anti-inflammatory properties.

OBJECTIVES

The present study aims to investigate whether and how baicalin inhibits oral squamous cell carcinoma (OSCC) acidic microenvironment and attenuates immune escape.

METHODS

Baicalin was dose-dependently administrated to OSCC cells (0-50 μmol/L). Co-culture system was constructed by OSCC cells and activated PBMCs. The proliferation and migration of OSCC cells were tested by CCK-8, colony formation, EdU, transwell assays. The cytokines were tested by ELISA kits. Mechanistical exploration was verified by RNA immunoprecipitation (RIP), fluorescence in situ hybridization (FISH) and RNA stability assays.

RESULTS

Results indicated that baicalin dose-dependently repressed the proliferation and migration of OSCC cells, and strengthened the antitumor immune activity of activated PBMCs to OSCC cells. Moreover, baicalin repressed the lactate accumulation, acidification and m6A modification level of OSCC cells. Molecular docking and MeRIP-Seq revealed that baicalin targeted LDHA via m6A-IGF2BP3-dependent manner to reduce lactate accumulation and PD-L1 expression in co-culture microenvironment.

CONCLUSION

This study revealed the anti-tumor activity of baicalin for OSCC by reducing lactate accumulation and attenuating the immune escape in tumor microenvironment, which provided a novel insight to improve our understanding in the treatment of traditional Chinese medicine on human cancer.

Ubiquitination Enzymes in Cancer, Cancer Immune Evasion, and Potential Therapeutic Opportunities

Ubiquitination is cells' second most abundant posttranslational protein modification after phosphorylation. The ubiquitin-proteasome system (UPS) is critical in maintaining essential life processes such as cell cycle control, DNA damage repair, and apoptosis. Mutations in ubiquitination pathway genes are strongly linked to the development and spread of multiple cancers since several of the UPS family members possess oncogenic or tumor suppressor activities. This comprehensive review delves into understanding the ubiquitin code, shedding light on its role in cancer cell biology and immune evasion. Furthermore, we highlighted recent advances in the field for targeting the UPS pathway members for effective therapeutic intervention against human cancers. We also discussed the recent update on small-molecule inhibitors and PROTACs and their progress in preclinical and clinical trials.

Pan-cancer analysis of IRF1 focusing on prognostic and immunological roles in non-small cell lung cancer

Interferon regulatory factor 1 (IRF1) significantly affects tumour occurrence and development. This study aimed to analyse its function as a pan-cancer prognostic indicator. We compared IRF1 expression and prognostic significance in normal and tumour samples from different databases. Accordingly, we performed in vitro experiments and immunohistochemistry (IHC) to investigate the role of IRF1 in non-small cell lung cancer (NSCLC). Our findings indicate that IRF1 expression is significantly correlated with prognosis, the tumour microenvironment, and immune cell infiltration. Furthermore, receiver operating characteristic (ROC) analysis revealed that IRF1 had high accuracy in distinguishing cancerous tissues from normal ones. Notably, IRF1 expression was linked to immune-related and immune checkpoint genes. Cell proliferation, invasion, and migration were significantly related to IRF1 expression. IHC indicated that IRF1 was downregulated in NSCLC tissues. Our study provides comprehensive bioinformatic analysis and experimental verification of IRF1, suggesting its potential as a prognostic biomarker in cancer.

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.

Comprehensive assessment of TECENTRIQ® and OPDIVO®: analyzing immunotherapy indications withdrawn in triple-negative breast cancer and hepatocellular carcinoma

Atezolizumab (TECENTRIQ®) and nivolumab (OPDIVO®) are both immunotherapeutic indications targeting programmed cell death 1 ligand 1 (PD-L1) and programmed cell death 1 (PD-1), respectively. These inhibitors hold promise as therapies for triple-negative breast cancer (TNBC) and hepatocellular carcinoma (HCC) and have demonstrated encouraging results in reducing the progression and spread of tumors. However, due to their adverse effects and low response rates, the US Food and Drug Administration (FDA) has withdrawn the approval of atezolizumab in TNBC and nivolumab in HCC treatment. The withdrawals of atezolizumab and nivolumab have raised concerns regarding their effectiveness and the ability to predict treatment responses. Therefore, the current study aims to investigate the immunotherapy withdrawal of PD-1/PD-L1 inhibitors, specifically atezolizumab for TNBC and nivolumab for HCC. This study will examine both the structural and clinical aspects. This review provides detailed insights into the structure of the PD-1 receptor and its ligands, the interactions between PD-1 and PD-L1, and their interactions with the withdrawn antibodies (atezolizumab and nivolumab) as well as PD-1 and PD-L1 modifications. In addition, this review further assesses these antibodies in the context of TNBC and HCC. It seeks to elucidate the factors that contribute to diverse responses to PD-1/PD-L1 therapy in different types of cancer and propose approaches for predicting responses, mitigating the potential risks linked to therapy withdrawals, and optimizing patient outcomes. By better understanding the mechanisms underlying responses to PD-1/PD-L1 therapy and developing strategies to predict these responses, it is possible to create more efficient treatments for TNBC and HCC.

Ubiquitin modification in the regulation of tumor immunotherapy resistance mechanisms and potential therapeutic targets

Although immune checkpoint-based cancer immunotherapy has shown significant efficacy in various cancers, resistance still limits its therapeutic effects. Ubiquitination modification is a mechanism that adds different types of ubiquitin chains to proteins, mediating protein degradation or altering their function, thereby affecting cellular signal transduction. Increasing evidence suggests that ubiquitination modification plays a crucial role in regulating the mechanisms of resistance to cancer immunotherapy. Drugs targeting ubiquitination modification pathways have been shown to inhibit tumor progression or enhance the efficacy of cancer immunotherapy. This review elaborates on the mechanisms by which tumor cells, immune cells, and the tumor microenvironment mediate resistance to cancer immunotherapy and the details of how ubiquitination modification regulates these mechanisms, providing a foundation for enhancing the efficacy of cancer immunotherapy by intervening in ubiquitination modification.

Low Serum Apolipoprotein A1 Levels Impair Antitumor Immunity of CD8+ T Cells via the HIF-1α-Glycolysis Pathway

An immunosuppressive microenvironment promotes the occurrence and development of tumors. Low apolipoprotein A1 (ApoA1) is closely related to tumor development, but the underlying mechanisms are unclear. This study investigated the association between serum ApoA1 levels and the immune microenvironment in endometrial, ovarian, and lung cancers. The serum ApoA1 level was decreased significantly in patients with endometrial and ovarian cancers compared with healthy controls. In endometrial cancer (EC) tissues, the low serum ApoA1 level group showed increased CD163+ macrophage infiltration and decreased CD8+ T-cell infiltration compared with the normal serum ApoA1 group. Compromised tumor-infiltrating CD8+ T-cell functions and decreased CD8+ T-cell infiltration also were found in tumor-bearing Apo1-knockout mice. CD8+ T-cell depletion experiments confirmed that ApoA1 exerted its antitumor activity in a CD8+ T-cell-dependent manner. In vitro experiments showed that the ApoA1 mimetic peptide L-4F directly potentiated the antitumor activity of CD8+ T cells via a HIF-1α-mediated glycolysis pathway. Mechanistically, ApoA1 suppressed ubiquitin-mediated degradation of HIF-1α protein by downregulating HIF-1α subunit α inhibitor. This regulatory process maintained the stability of HIF-1α protein and activated the HIF-1α signaling pathway. Tumor-bearing Apoa1 transgenic mice showed an increased response to anti-PD-1 therapy, leading to reduced tumor growth along with increased infiltration of activated CD8+ T cells and enhanced tumor necrosis. The data reported herein demonstrate critical roles for ApoA1 in enhancing CD8+ T-cell immune functions via HIF-1α-mediated glycolysis and support clinical investigation of combining ApoA1 supplementation with anti-PD-1 therapy for treating cancer.

The therapeutic effect and targets of herba Sarcandrae on breast cancer and the construction of a prognostic signature consisting of inflammation-related genes

Background

The prevalence of breast cancer (BRCA), which is common among women, is on the rise. This study applied network pharmacology to explore the potential mechanism of action of herba sarcandrae in BRCA and construct a prognostic signature composed of inflammation-related genes.

Methods

The active ingredients of herba sarcandrae were screened using the SymMap, TCMID, and TCMSP platforms, and the molecular targets were determined in the UniProt database. The "drug-active compound-potential target" network was established with Cytoscape 3.7.2. The molecular targets were subjected to disease ontology, gene ontology (GO), and Kyoto Encyclopedia of Genes (KEGG) analyses. AutoDock software was used for molecular docking. Differentially expressed genes (DEGs) related to inflammation were obtained from the BRCA Cancer Genome Atlas (TCGA) database. In the training cohort, the univariate Cox regression model was applied to preliminarily screen prognostic genes. A multigene signature was built by the least absolute shrinkage and selection operator (LASSO) regression model, followed by validation through Kaplan‒Meier, Cox, and receiver operating characteristic (ROC) analyses.

Results

Forty-one active compounds were identified, and 265 therapeutic targets for herba sarcandrae were predicted. GO enrichment results revealed significant enrichment of biological processes, such as response to xenobiotic stimuli, response to nutrient levels, and response to lipopolysaccharide. KEGG analysis revealed significant enrichment of pathways such as AGE-RAGE and chemical carcinogenesis receptor activation signaling pathways. In addition, the herbs Marc-Andre and rutin were shown to mediate BRCA cell proliferation and apoptosis via the interferon regulatory factor 1 (IRF1)/signal transducer and activator of transcription 3 (STAT3)/programmed death-ligand 1 (PD-L1) pathway. Sixteen inflammatory signatures, including BST2, GPR132, IL12B, IL18, IL1R1, IL2RB, IRF1, and others, were constructed, and the risk score was found to be a strong independent prognostic factor for overall survival in BRCA patients. The 16-inflammation signature was associated with several clinical features (age, clinical stage, T, and N classifications) and could reflect immune cell infiltration in tumor microenvironments with different immune cells.

Conclusions

Herba sarcandrae and rutin were shown to mediate BRCA cell proliferation and apoptosis via the IRF1/STAT3/PD-L1 pathway, and the 16-member inflammatory signature might be a novel biomarker for predicting BRCA patient prognosis, providing more accurate guidance for clinical treatment prognosis evaluation and having important reference value for individualized treatment selection.

Nur77-IRF1 axis inhibits esophageal squamous cell carcinoma growth and improves anti-PD-1 treatment efficacy

The nuclear receptor Nur77 plays paradoxical roles in numerous cancers. However, whether Nur77 inhibits esophageal squamous cell carcinoma (ESCC) growth and affects immunological responses against ESCC has not been determined. The functional role of Nur77 in ESCC was investigated in this study using human ESCC cell lines, quantitative real-time polymerase chain reaction (PCR), cell proliferation and colony formation assays, flow cytometry analysis, western blotting and animal models. The target gene controlled by Nur77 was verified using dual-luciferase reporter assays, chromatin immunoprecipitation analysis and functional rescue experiments. To examine the clinical importance of Nur77, 72 human primary ESCC tissues were subjected to immunohistochemistry. Taken together, these findings showed that, both in vitro and in vivo, Nur77 dramatically reduced ESCC cell growth and triggered apoptosis. Nur77 directly interacts with the interferon regulatory factor 1 (IRF1) promoter to inhibit its activity in ESCC. Pharmacological induction of Nur77 using cytosporone B (CsnB) inhibited ESCC cell proliferation and promoted apoptosis both in vitro and in vivo. Furthermore, CsnB increased CD8+ T-cell infiltration and cytotoxicity to inhibit the formation of ESCC tumors in an immunocompetent mouse model. In ESCC tissues, Nur77 expression was downregulated, and IRF1 expression was increased; moreover, their expression levels were negatively related. IRF1 and Nur77 were strongly correlated with overall survival. These findings suggested that Nur77 targets and regulates the IRF1/PD-L1 axis to serve as a tumor suppressor in ESCC. Graphical abstract of the regulatory mechanism of Nur77 overexpression downregulates IRF1 in the inhibition of ESCC progression and enhance anti-PD-1 therapy efficacy.

Interleukin-21 as an adjuvant in cancer immunotherapy: Current advances and future directions

Immunotherapy has revolutionized cancer treatment. However, it's well-recognized that a considerable proportion of patients fail to benefit from immunotherapy, and to improve immunotherapy response is clinically urgent. Insufficient immune infiltration and immunosuppressive tumor microenvironments (TME) are main contributors to immunotherapy resistance. Thus sustaining functional self-renewal capacity for immune cells and subverting immune-suppressive signals are potential strategies for boosting the efficacy of immunotherapy. Interleukin-21 (IL-21), a crucial cytokine, which could enhance cytotoxic function of immune cells and reduces immunosuppressive cells enrichment in TME, shows promising orientations as an immunoadjuvant in tumor immunotherapy. This review focuses on IL-21 in cancer treatment, including function and mechanisms of IL-21, preclinical and clinical studies, and future directions for IL-21-assisted therapies.

SPOP point mutations regulate substrate preference and affect its function

The adaptor SPOP recruits substrates to CUL3 E3 ligase for ubiquitination and degradation. Structurally, SPOP harbors a MATH domain for substrate recognition, and a BTB domain responsible for binding CUL3. Reported point mutations always occur in SPOP's MATH domain and are through to disrupt affinities of SPOP to substrates, thereby leading to tumorigenesis. In this study, we identify the tumor suppressor IRF2BP2 as a novel substrate of SPOP. SPOP enables to attenuate IRF2BP2-inhibited cell proliferation and metastasis in HCC cells. However, overexpression of wild-type SPOP alone suppresses HCC cell proliferation and metastasis. In addition, a HCC-derived mutant, SPOP-M35L, shows an increased affinity to IRF2BP2 in comparison with wild-type SPOP. SPOP-M35L promotes HCC cell proliferation and metastasis, suggesting that M35L mutation possibly reprograms SPOP from a tumor suppressor to an oncoprotein. Taken together, this study uncovers mutations in SPOP's MATH lead to distinct functional consequences in context-dependent manners, rather than simply disrupting its interactions with substrates, raising a noteworthy concern that we should be prudent to select SPOP as therapeutic target for cancers.

Roles of Interferon Regulatory Factor 1 in Tumor Progression and Regression: Two Sides of a Coin

IRF1 is a transcription factor well known for its role in IFN signaling. Although IRF1 was initially identified for its involvement in inflammatory processes, there is now evidence that it provides a function in carcinogenesis as well. IRF1 has been shown to affect several important antitumor mechanisms, such as induction of apoptosis, cell cycle arrest, remodeling of tumor immune microenvironment, suppression of telomerase activity, suppression of angiogenesis and others. Nevertheless, the opposite effects of IRF1 on tumor growth have also been demonstrated. In particular, the "immune checkpoint" molecule PD-L1, which is responsible for tumor immune evasion, has IRF1 as a major transcriptional regulator. These and several other properties of IRF1, including its proposed association with response and resistance to immunotherapy and several chemotherapeutic drugs, make it a promising object for further research. Numerous mechanisms of IRF1 regulation in cancer have been identified, including genetic, epigenetic, transcriptional, post-transcriptional, and post-translational mechanisms, although their significance for tumor progression remains to be explored. This review will focus on the established tumor-suppressive and tumor-promoting functions of IRF1, as well as the molecular mechanisms of IRF1 regulation identified in various cancers.

BCLAF1 binds SPOP to stabilize PD-L1 and promotes the development and immune escape of hepatocellular carcinoma

Interaction between programmed death-1 (PD-1) ligand 1 (PD-L1) on tumor cells and PD-1 on T cells allows tumor cells to evade T cell-mediated immune surveillance. Strategies targeting PD-1/PD-L1 have shown clinical benefits in a variety of cancers. However, limited response rates in hepatocellular carcinoma (HCC) have prompted us to investigate the molecular regulation of PD-L1. Here, we identify B cell lymphoma-2-associated transcription factor 1 (BCLAF1) as a key PD-L1 regulator in HCC. Specifically, BCLAF1 interacts with SPOP, an E3 ligase that mediates the ubiquitination and degradation of PD-L1, thereby competitively inhibiting SPOP-PD-L1 interaction and subsequent ubiquitination and degradation of PD-L1. Furthermore, we determined an SPOP-binding consensus (SBC) motif mediating the BCLAF1-SPOP interaction on BCLAF1 protein and mutation of BCLAF1-SBC motif disrupts the regulation of the SPOP-PD-L1 axis. In addition, BCLAF1 expression was positively correlated with PD-L1 expression and negatively correlated with biomarkers of T cell activation, including CD3 and CD8, as well as with the level of immune cell infiltration in HCC tissues. Besides, BCLAF1 depletion leads to a significant reduction of PD-L1 expression in vitro, and this reduction of PD-L1 promoted T cell-mediated cytotoxicity. Notably, overexpression of BCLAF1 sensitized tumor cells to checkpoint therapy in an in vitro HCC cells-Jurkat cells co-culture model, whereas BCLAF1-SBC mutant decreased tumor cell sensitivity to checkpoint therapy, suggesting that BCLAF1 and its SBC motif serve as a novel therapeutic target for enhancing anti-tumor immunity in HCC.

Improving the Efficacy of Common Cancer Treatments via Targeted Therapeutics towards the Tumour and Its Microenvironment

Cancer is defined as the uncontrolled proliferation of heterogeneous cell cultures in the body that develop abnormalities and mutations, leading to their resistance to many forms of treatment. Left untreated, these abnormal cell growths can lead to detrimental and even fatal complications for patients. Radiation therapy is involved in around 50% of cancer treatment workflows; however, it presents significant recurrence rates and normal tissue toxicity, given the inevitable deposition of the dose to the surrounding healthy tissue. Chemotherapy is another treatment modality with excessive normal tissue toxicity that significantly affects patients' quality of life. To improve the therapeutic efficacy of radiotherapy and chemotherapy, multiple conjunctive modalities have been proposed, which include the targeting of components of the tumour microenvironment inhibiting tumour spread and anti-therapeutic pathways, increasing the oxygen content within the tumour to revert the hypoxic nature of the malignancy, improving the local dose deposition with metal nanoparticles, and the restriction of the cell cycle within radiosensitive phases. The tumour microenvironment is largely responsible for inhibiting nanoparticle capture within the tumour itself and improving resistance to various forms of cancer therapy. In this review, we discuss the current literature surrounding the administration of molecular and nanoparticle therapeutics, their pharmacokinetics, and contrasting mechanisms of action. The review aims to demonstrate the advancements in the field of conjugated nanomaterials and radiotherapeutics targeting, inhibiting, or bypassing the tumour microenvironment to promote further research that can improve treatment outcomes and toxicity rates.

LRP5 competes for SPOP binding to enhance tumorigenesis mediated by Daxx and PD-L1 in prostate cancer

Genetic factors coordinate with environmental factors to drive the pathogenesis of prostate adenocarcinoma (PRAD). SPOP is one of the most mutated genes and LRP5 mediates lipid metabolism that is abnormally altered in PRAD. Here, we investigated the potential cross-talk between SPOP and LRP5 in PRAD. We find a negative correlation between SPOP and LRP5 proteins in PRAD. SPOP knockdown increased LRP5 protein while SPOP overexpression resulted in LRP5 reduction that was fully rescued by proteasome inhibitors. LRP5 intracellular tail has SPOP binding site and the direct interaction between LRP5 and SPOP was confirmed by Co-IP and GST-pulldown. Moreover, LRP5 competed with Daxx for SPOP-mediated degradation, establishing a dynamic balance among SPOP, LRP5 and Daxx. Overexpression of LRP5 tail could shift this balance to enhance Daxx-mediated transcriptional inhibition, and inhibit T cell activity in a co-culture system. Further, we generated human and mouse prostate cancer cell lines expressing SPOP variants (F133V, A227V, R368H). SPOP-F133V and SPOP-A227V have specific effects in up-regulating the protein levels of PD-1 and PD-L1. Consistently, SPOP-F133V and SPOP-A227V show robust inhibitory effects on T cells compared to WT SPOP in co-culture. This is further supported by the mouse syngeneic model showing that SPOP-F133V and SPOP-A227V enhance tumorigenesis of prostate cancer in in-vivo condition. Taken together, our study provides evidence that SPOP-LRP5 crosstalk plays an essential role, and the genetic variants of SPOP differentially modulate the expression and activity of immune checkpoints in prostate cancer.

Differential Impact of SPOP Mutation in Prostate and Endometrial Cancers

Editorial on differential impact of mutSPOP on prostate & endometrial Ca

Opposing Roles of SPOP Mutations in Human Prostate and Endometrial Cancers

PURPOSE

Recurrent gene mutations in speckle-type POZ protein (SPOP), the substrate-binding component of E3 ubiquitin ligase, are associated with tumor progression in prostate and endometrial cancers. Here, we characterized SPOP mutations in these cancers and explored their association with molecular and immune signatures and patient outcomes.

METHODS

There were 7,398 prostate cancer and 19,188 endometrial cancer samples analyzed for clinical and molecular profiles at Caris Life Sciences. Overall survival (OS) was analyzed using Kaplan-Meier survival curves. Statistical significance was determined using chi-square and Mann-Whitney U tests, with P values adjusted for multiple comparisons.

RESULTS

SPOP mutations were identified in 9.2% of prostate and 4.3% of endometrial cancers. Mutations clustered in the SPOP meprin and TRAF-C homology domain, with no significant overlap between cancer types. SPOP mutation was associated with differential comutation profiles and opposing tumor immune microenvironment signatures for each cancer, with greater immune infiltration in SPOP-mutated endometrial cancer. SPOP-mutated prostate and endometrial cancers displayed altered epigenetic gene expression, including opposite regulation of BRD2 transcripts. In SPOP-mutant prostate cancer, higher expression of androgen receptor-regulated transcripts and improved OS after treatment with hormonal agents were observed. In endometrial cancer, hormone receptor expression was significantly lower in SPOP-mutated tumors and differences in OS were highly dependent on the particular hotspot mutation and histologic subtype.

CONCLUSION

These data indicate that SPOP mutations drive opposing molecular and immune landscapes in prostate and endometrial cancers-suggesting a loss-of-function mechanism in prostate cancer and gain-of-function mechanism in endometrial cancer-and provide a rationale for tailored therapeutic approaches.

SPOP targets the immune transcription factor IRF1 for proteasomal degradation

Adaptation of the functional proteome is essential to counter pathogens during infection, yet precisely timed degradation of these response proteins after pathogen clearance is likewise key to preventing autoimmunity. Interferon regulatory factor 1 (IRF1) plays an essential role as a transcription factor in driving the expression of immune response genes during infection. The striking difference in functional output with other IRFs is that IRF1 also drives the expression of various cell cycle inhibiting factors, making it an important tumor suppressor. Thus, it is critical to regulate the abundance of IRF1 to achieve a 'Goldilocks' zone in which there is sufficient IRF1 to prevent tumorigenesis, yet not too much which could drive excessive immune activation. Using genetic screening, we identified the E3 ligase receptor speckle type BTB/POZ protein (SPOP) to mediate IRF1 proteasomal turnover in human and mouse cells. We identified S/T-rich degrons in IRF1 required for its SPOP MATH domain-dependent turnover. In the absence of SPOP, elevated IRF1 protein levels functionally increased IRF1-dependent cellular responses, underpinning the biological significance of SPOP in curtailing IRF1 protein abundance.

Cul3 substrate adaptor SPOP targets Nup153 for degradation

SPOP is a Cul3 substrate adaptor responsible for degradation of many proteins related to cell growth and proliferation. Because mutation or misregulation of SPOP drives cancer progression, understanding the suite of SPOP substrates is important to understanding regulation of cell proliferation. Here, we identify Nup153, a component of the nuclear basket of the nuclear pore complex, as a novel substrate of SPOP. SPOP and Nup153 bind to each other and colocalize at the nuclear envelope and some nuclear foci in cells. The binding interaction between SPOP and Nup153 is complex and multivalent. Nup153 is ubiquitylated and degraded upon expression of SPOPWT but not its substrate binding-deficient mutant SPOPF102C. Depletion of SPOP via RNAi leads to Nup153 stabilization. Upon loss of SPOP, the nuclear envelope localization of spindle assembly checkpoint protein Mad1, which is tethered to the nuclear envelope by Nup153, is stronger. Altogether, our results demonstrate SPOP regulates Nup153 levels and expands our understanding of the role of SPOP in protein and cellular homeostasis.

The Cross Talk between Cellular Senescence and Melanoma: From Molecular Pathogenesis to Target Therapies

Melanoma is a malignant skin tumor that originates from melanocytes. The pathogenesis of melanoma involves a complex interaction that occurs between environmental factors, ultraviolet (UV)-light damage, and genetic alterations. UV light is the primary driver of the skin aging process and development of melanoma, which can induce reactive oxygen species (ROS) production and the presence of DNA damage in the cells, and results in cell senescence. As cellular senescence plays an important role in the relationship that exists between the skin aging process and the development of melanoma, the present study provides insight into the literature concerning the topic at present and discusses the relationship between skin aging and melanoma, including the mechanisms of cellular senescence that drive melanoma progression, the microenvironment in relation to skin aging and melanoma factors, and the therapeutics concerning melanoma. This review focuses on defining the role of cellular senescence in the process of melanoma carcinogenesis and discusses the targeting of senescent cells through therapeutic approaches, highlighting the areas that require more extensive research in the field.

The E3 ubiquitin ligases regulate PD-1/PD-L1 protein levels in tumor microenvironment to improve immunotherapy

The tumor microenvironment (TME) is the tumor surrounding environment, which is critical for tumor development and progression. TME is also involved in clinical intervention and treatment outcomes. Modulation of TME is useful for improving therapy strategies. PD-L1 protein on tumor cells interacts with PD-1 protein on T cells, contributing to T cell dysfunction and exhaustion, blockage of the immune response. Evidence has demonstrated that the expression of PD-1/PD-L1 is associated with clinical response to anti-PD-1/PD-L1 therapy in cancer patients. It is important to discuss the regulatory machinery how PD-1/PD-L1 protein is finely regulated in tumor cells. In recent years, studies have demonstrated that PD-1/PD-L1 expression was governed by various E3 ubiquitin ligases in TME, contributing to resistance of anti-PD-1/PD-L1 therapy in human cancers. In this review, we will discuss the role and molecular mechanisms of E3 ligases-mediated regulation of PD-1 and PD-L1 in TME. Moreover, we will describe how E3 ligases-involved PD-1/PD-L1 regulation alters anti-PD-1/PD-L1 efficacy. Altogether, targeting E3 ubiquitin ligases to control the PD-1/PD-L1 protein levels could be a potential strategy to potentiate immunotherapeutic effects in cancer patients.