Search Results (622)

Background: Treatment response to neoadjuvant therapy in rectal cancer exhibits a considerable degree of interpatient heterogeneity. Select components of the tumour immune microenvironment have been identified as predictive biomarkers of therapeutic response, for which more evidence is required for future clinical prediction models. Aim: The research aimed to identify key tumour immune microenvironment biomarkers predictive of the response to neoadjuvant therapy through the systematic appraisal of existing literature. Methods: A structured search was performed across PubMed, Ovid Embase, and Cochrane databases to retrieve primary studies investigating the association between the tumour immune microenvironment and pathological complete response (pCR) or tumour regression grade (TRG) in patients with rectal cancer. Studies were screened against predefined inclusion and exclusion criteria. Results: Fifteen studies satisfied the inclusion criteria, with cohorts ranging between 24 and 298 participants with predominantly stage II–III disease. Considerable heterogeneity was observed in both types and methods of quantification of biomarkers. Biomarkers assessed in pretreatment biopsies included tumour-infiltrating lymphocytes (TILs), investigated by subtype (cluster of differentiation (CD)8+, CD4+, forkhead box protein 3+ (FOXP3)) or as a composite measure, as well as programmed death-ligand 1 (PD-L1), PD-1+, natural killer (NK) cells, CD163+, and CD68+. Findings showed that high densities of TILs—particularly the CD8+ subtype—consistently correlated with improved tumour regression. FOXP3+ and CD163+ were inconsistently associated with reduced treatment response. NK cells and CD68+ cells were less frequently investigated and yielded non-significant findings. Conclusions: CD8+ TILs have the potential to serve as predictive biomarkers of therapeutic response to neoadjuvant treatment in patients with rectal cancer. Inconsistent findings with FOXP3+ Tregs and CD163+ macrophages reinforce the need for their further investigation. Full article

Background: While the prognostic and predictive value of tumor cell–derived features such as grade, estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) status, and Ki67 index is well established in breast cancer, less is known about the prognostic role of tumor stroma. This study aimed to evaluate stromal parameters in HER2-positive breast cancer patients treated with adjuvant trastuzumab. Material and methods: The study included 224 patients (T ≥ 1, N ≥ 0, M0) who underwent radical treatment followed by adjuvant chemotherapy, hormone therapy (if ER/PR-positive), and trastuzumab. The following histological and immunohistochemical parameters were analyzed: stroma type, tumor-infiltrating lymphocytes (TILs), eosinophils, neutrophils, central area of fibrosis, necrosis, and programmed cell death protein ligand 1 (PD-L1) expression in tumor and stromal cells. Results: Low TILs percentage (≤50%) was associated with lower tumor grade (G2) (p = 0.013) and ER/PR positivity (p = 0.001). Tumors lacking PD-L1 expression had a lower percentage of TILs (p < 0.001), less frequently exhibited tumor-associated neutrophilia (p = 0.019), and more often presented with desmoplastic stroma (p < 0.001). The following parameters were associated with prognosis: TILs percentage, stroma type, and PD-L1 expression. High TILs percentage (>50%) was an independent positive prognostic factor. Conclusions: In patients with HER2-positive breast cancer treated with adjuvant trastuzumab, the percentage of TILs, stroma type, and PD-L1 expression are prognostically relevant. Specifically, a TILs percentage >50% independently predicts favorable outcomes. Routine evaluation of stromal features may provide additional prognostic information and support treatment planning. Full article

Oncolytic viruses represent a paradigm-shifting approach to cancer immunotherapy, functioning as in situ vaccines that convert immunologically “cold” tumors into “hot” tumors through induction of immunogenic cell death (ICD). Despite the clinical success of checkpoint inhibitors targeting programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), many patients exhibit primary or acquired resistance due to insufficient tumor immunogenicity and exclusion of tumor-infiltrating lymphocytes. Oncolytic viruses address this limitation by selectively replicating in tumor cells, inducing robust ICD characterized by four cardinal hallmarks: calreticulin exposure, ATP secretion, HMGB1 release, and type I interferon production. This review systematically examines the molecular mechanisms underlying virus-induced ICD, compares DNA virus platforms (Vaccinia, HSV-1, Adenovirus) with RNA virus platforms (Coxsackieviruses A21, A11, and B3), and analyzes clinical trial data demonstrating synergistic efficacy when combined with checkpoint inhibitors. Notably, RNA viruses generate higher type I interferon responses compared to DNA viruses, correlating with superior clinical outcomes. Coxsackievirus A21 combined with pembrolizumab achieved a 47% objective response rate in melanoma in the CAPRA trial, representing notable efficacy exceeding either monotherapy. Coxsackievirus A11 demonstrates exceptional selectivity for thoracic cancers through ICAM-1-dependent receptor tropism and potent immunogenic cell death induction. Japanese researchers have pioneered microRNA-targeted Coxsackievirus B3, achieving cardiac safety attenuation while preserving complete oncolytic potency and ICD-inducing capacity. This comprehensive analysis synthesizes molecular mechanisms, platform comparisons, clinical efficacy data, and translational challenges to guide future development of oncolytic virotherapy as a cornerstone of cancer immunotherapy. Full article

Background and Objectives: Autologous stem cell transplantation (ASCT) remains the standard of care for relapsed or refractory Hodgkin lymphoma (R/R HL), and an increasing proportion of patients receive programmed cell death protein 1 (PD-1) inhibitors prior to transplantation. Engraftment syndrome (ES) is a noninfectious inflammatory complication classically associated with neutrophil recovery; however, early peri-transplant inflammatory manifestations remain poorly characterized and may mimic infectious complications. We aimed to evaluate peri-transplant inflammatory events after ASCT, with particular emphasis on ES-compatible manifestations occurring before neutrophil engraftment and their association with prior PD-1 inhibitor exposure. Materials and Methods: In this single-center retrospective cohort study, 64 consecutive adult patients with HL undergoing ASCT between 2018 and 2025 were analyzed. ES was defined according to Spitzer and Maiolino criteria. Inflammatory manifestations fulfilling these criteria but occurring prior to neutrophil recovery were classified as pre-engraftment syndrome (pre-ES). Clinically significant events were defined by the requirement for systemic corticosteroid therapy. Clinical and laboratory parameters were compared using non-parametric statistical analyses. Results: No cases fulfilled the Spitzer criteria for classical ES, while three patients (4.7%) met the Maiolino criteria, none requiring corticosteroid therapy. Using the broader Maiolino definition, pre-ES was observed in 34 patients (53.1%) when the conventional engraftment time window was disregarded; however, only three patients required systemic corticosteroid therapy. Importantly, all three cases also fulfilled the Spitzer criteria outside the conventional time window, whereas the remaining Maiolino-defined pre-ES cases were self-limiting. All steroid-requiring pre-ES cases occurred exclusively in PD-1-exposed patients, and prior PD-1 therapy was significantly associated with severe pre-ES (p = 0.0007), although this finding is based on a very small number of events. These patients also demonstrated significantly higher early C-reactive protein (CRP) levels. Conclusions: While classical ES after ASCT was uncommon, clinically significant pre-ES occurred exclusively in PD-1-exposed patients. These early inflammatory events may represent a distinct phenotype and require prompt recognition and timely corticosteroid therapy after exclusion of infection. Prospective studies are warranted to validate these findings and refine risk stratification and monitoring strategies. Full article

Background/Objectives: Colorectal cancer (CRC) is a leading cause of cancer-related mortality worldwide, yet the association between folic acid (FA) intake and CRC risk remains controversial. This study investigated the effects of varying dietary FA levels on colorectal carcinogenesis and the underlying mechanisms. Methods: BALB/c mice were fed diets containing FA at <0.1, 2.0, 6.0, 8.0, or 20.0 mg/kg for 14 weeks. After 4 weeks, colorectal tumorigenesis was induced using the azoxymethane/dextran sulfate sodium (AOM/DSS) protocol. Tumor multiplicity, maximum tumor diameter, tumor volume, colorectal length, histopathology, and cell proliferation were assessed. Mechanistic assessments included uracil misincorporation, thymidylate synthase (TS), telomere attrition, genome-wide DNA methylation, RAP1 signaling, immune-related markers, and inflammatory cytokines in colorectal tissues. Results: Both FA deficiency (<0.1 mg/kg) and excess (8.0/20.0 mg/kg) increased colorectal tumor burden, with increased tumor number, larger maximum diameter, greater tumor volume, shortened colorectal length, and enhanced cell proliferation, whereas the 6.0 mg/kg diet group showed the lowest tumor burden. FA deficiency reduced TS expression, elevated deoxyuridine monophosphate (dUMP) levels, decreased deoxythymidine monophosphate (dTMP) levels, increased uracil misincorporation, and exacerbated telomere attrition, as evidenced by shortened telomeres and increased damage. In contrast, excessive FA intake induced Rap1 GTPase-activating protein (RAP1GAP) hypermethylation, reduced Rap1GAP expression, enhanced RAP1 activity, and upregulated programmed death-ligand 1 (PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA4) expression. Conclusions: Dietary FA can exhibit a U-shaped association with colorectal carcinogenesis, with protective effects observed within an optimal range. FA deficiency and excess may drive tumor development through distinct molecular pathways involving uracil misincorporation-induced telomere attrition and DNA methylation-mediated immunosuppression, respectively. Full article

Background: Cutaneous adverse events (cAEs) are among the most frequent immune-related toxicities associated with immune checkpoint inhibitors (ICIs). Previous clinical trials have reported higher rates of dermatologic toxicity with anti-CTLA-4 agents compared to Programmed Cell Death (PD-1)/ Programmed Cell Death-1 Ligand (PD-L1) inhibitors. However, real-world data may differ due to evolving clinical experience and improved AE management strategies. Methods: We conducted a retrospective analysis of patients treated with ICIs to assess the incidence and severity of cAEs —specifically rash and pruritus—across different treatment regimens and PD-L1 expression subgroups, 285 patients treated with ICIs at Soroka Medical center during the years August 2018–November 2025. Results: Regarding dermatologic toxicity, 57 out of 285 patients (20%) experienced a rash. Among them, 46 patients (16% of total; 81% of those with rash) had grade 1, 7 patients (2% of total; 12% of those with rash) had grade 2, and 4 patients (1% of total; 7% of those with rash) had grade 3 reactions. No grade 4 or life-threatening cases were observed. Additionally, 47 patients (16.5%) developed pruritus, all grade 1–2. When stratified by treatment type, PD-L1 expression and the occurrence of immune-related adverse events, specifically rash and pruritus, were significantly associated with survival outcomes (p < 0.001). Patients with expressions of PD-L1 ≥1% had longer median overall survival (34.0 months) compared to those with expressions of PD-L1 < 1% (20.0 months), and longer progression-free survival (22.0 vs. 13.0 months). When considering rash, overall survival ranged from 19.0 months (PD-L1 < 1% with rash) to 36.0 months (PD-L1 ≥1% without rash), and progression-free survival ranged from 12.0 to 27.0 months. The presence of pruritus was associated with the most favorable outcomes, with median overall survival reaching 48.0 months and progression-free survival 31.0 months in patients with PD-L1 ≥1% and pruritus. All comparisons showed statistically significant differences (p < 0.001). Conclusion: These findings highlight that higher PD-L1 expression and the presence of immune-related adverse events—particularly pruritus—may serve as important prognostic indicators and could help inform personalized treatment strategies. The incidence and severity of cAEs in our study were consistent with prior clinical trials. The low frequency of grade ≥ 3 events may reflect increased familiarity with ICIs, leading to earlier recognition of adverse events, better patient education, and more effective management of skin toxicities. Full article

Background: Indoleamine 2,3-dioxygenase (IDO) is an immune checkpoint that has been shown to play a key immunomodulatory role in various solid tumors, including breast cancer (BC). Although increased IDO expression has been previously observed in some BC subtypes, mainly triple-negative BC (TNBC), the clinical relevance of this protein across the entire range of BC and its exact correlations with other immune checkpoints remain to be elucidated. We herein aimed to further investigate the differential expression patterns of IDO and programmed death-ligand 1 (PD-L1) in variable BC subtypes and in distinct compartments of breast cancer tissue, and to explore their potential associations with standard patient- and tumor-related clinicopathological parameters as well as prognosis. Methods: This was a retrospective multi-center cohort study of 150 female patients with BC. The clinicopathological parameters analyzed were retrieved from the medical records of patients while sections from archival formalin-fixed, paraffin-embedded (FFPE) tissue blocks were also obtained for the performance of immunohistochemistry. The expression of IDO and PD-L1 was evaluated separately on tumor cells (IDO/CA, PD-L1/CA), lymphocytes (IDO/L, PD-L1/L) and stromal cells (IDO/S, PD-L1/S) and the results were correlated with the remaining clinical and pathological features of patients, as well as with local recurrence, metastasis and survival. Results: The mean age of patients was 59.5 years (SD = 13.4 years). Positive expression of IDO/CA, IDO/L and IDO/S was found in 6%, 93.3% and 90.7% of tissue samples, respectively, while 4%, 11.2% and 6.7% of tumors were positive for PD-L1/CA, PD-L1/L and PD-L1/S, respectively. A significantly higher rate of positive IDO/CA expression was observed in triple-negative BC (TNBC) patients (p = 0.037). Positive expression of IDO-CA was also significantly associated with positivity for PD-L1/L and PD-L1/S (p = 0.001 and p = 0.015, respectively). Multivariable logistic regression analysis showed independent correlations between IDO/CA and IDO/L and the presence of invasive ductal carcinoma (IDC) (OR = 1.10; p = 0.026) and N1 status (OR = 10.93; p = 0.039), respectively, IDO/S and both N1 (OR = 14.64; p = 0.018) and positive HER2 status (OR = 6.11; p = 0.019), PD-L1/L and high Ki67 (OR = 7.96; p = 0.001) as well as negative ER (OR = 0.08; 0.003) and PR status (OR = 0.09; p = 0.002), PD-L1/S and both NST (no special type) histology (OR = 4.68; p = 0.032) and negative ER status (OR = 0.21; p = 0.044). No statistically significant associations were observed between the expression patterns of the examined biomarkers and recurrence, metastasis or survival. Conclusions: In our study, IDO expression on tumor cells was predominantly observed in TNBC and was found to correlate with PD-L1 expression in the lymphocytic and stromal compartments. Furthermore, expression of PD-L1 among lymphocytes was found to independently correlate with unfavorable clinicopathological parameters, including high proliferation rate and negative hormone receptor status. Full article

The programmed death-ligand 1 (PD-L1) plays a critical role for promoting cancer immune evasion. However, the resistance to PD-L1-targeted immunotherapy greatly limits its application. α-lipoic acid (ALA) is an endogenous antioxidant, while whether ALA affects PD-L1 expression remains unknown. In IFN-γ-stimulated castration-resistant prostate cancer (CRPC)-mimicking PC3 and DU145 cells, the expression of PD-L1 and its regulatory genes was determined by Western blotting, RT-PCR, and immunofluorescence. The T-cell-mediated tumor-killing activity was evaluated in a co-culture system of cancer cells and Jurkat T cells. ALA significantly inhibits IFN-γ-induced PD-L1 protein and mRNA expression without affecting its degradation. The upstream genes accounting for PD-L1 induction, including JAK1/STAT1/IRF-1 cascade, c-Myc, HIF-1α, and GSK3β activity, were markedly suppressed by ALA. The decreased expression of PD-L1 and these regulators by ALA is also modulated by attenuation of mTOR/p70S6K/4EBP1-dependent protein translation and ROS production. In the co-culture system, ALA markedly increased T-cell-mediated tumor-killing activity compared to that of ALA treatment alone, suggesting that ALA may augment the antitumor immunity. Collectively, we demonstrated that ALA-mediated inhibition of PD-L1 expression is regulated by multiple mechanisms, which indicates that ALA may be a potential agent to enhance cancer immunotherapy, particularly in CRPC. Full article

Background: Exercise modulates the immune system and may enhance anti-cancer activity, offering potential synergy with cancer immunotherapy. Tumours with low immune cell infiltration (“cold” tumours) often respond poorly to immunotherapy and are associated with poor prognosis. Here, we demonstrate that exercise can reshape the immune landscape of tumours across the cold spectrum. Methods: C57BL/6 mice underwent orthotopic implantation of PANC02 (murine pancreatic adenocarcinoma) cells and BALB/c mice underwent intraperitoneal injections of AB-1 (murine mesothelioma) cells. Mice were then divided into groups; exercise with anti-Programmed Cell Death Protein 1 (PD-1), exercise with isotype, no exercise with anti-PD-1 and no exercise with isotype. Treadmill-running was performed for 20 min/day, 4 days/week at a speed of 12 metres/minute. Resistance training consisted of hanging upside down on a wire-mesh screen for 1 min 2 days/week. Flow cytometry was used to measure TME immune populations. Tumour and liver samples were harvested, paraffin wax-embedded/sectioned and analysed using SlideViewer 2.9.0™. A total of 22 healthy volunteers underwent a single bout of high-intensity interval cycling. Blood was collected pre- and post-exercise. Flow cytometry was used to measure leucocyte subpopulations. MSTO-211H (mesothelioma) and PANC-1 (pancreatic cancer) cells were cultured with pre- and post-exercise serum, with/without HSV1716, and viability determined using alamarBlue^®. PANC-1 apoptosis and migration were assessed using caspase-3/7 and scratch assays, respectively. Results: In an orthotopic pancreatic cancer mouse model, combining exercise with immunotherapy significantly increased tumour necrosis and reduced metastatic potential. In both pancreatic cancer and mesothelioma models, this combination remodelled the tumour microenvironment, enhancing cytotoxic CD8⁺ T cell infiltration, upregulating Programmed Cell Death Protein 1 (PD-1), and reducing Myeloid-Derived Suppressor Cells and regulatory T cells (Tregs). Complementary human studies revealed an acute systemic release of Natural Killer cells and a reduction in Tregs following high-intensity interval exercise in healthy volunteers. Moreover, exercise-conditioned serum from these participants exerted anti-cancer effects on pancreatic cancer and mesothelioma cell lines. Conclusions: Altogether, these findings highlight exercise as a promising adjunct to immunotherapy for poorly immunogenic cancers such as pancreatic cancer and mesothelioma. Full article

Background: Programmed cell death protein (ligand) 1 (PD-(L)1) inhibitors are well established in the treatment of dermatological tumors. Mostly, they are well tolerated, but in about 9–21% of patients, grade 3/4 immune-related adverse events (irAEs) occur. As treatment options are limited, it is of interest to determine whether readministration of another or the same PD-(L)1 inhibitor is safe. Methods: This is a multicenter, retrospective study on patients with metastasized dermatological tumors who were retreated with either the same or a different PD-(L)1 inhibitor after the development of irAEs. The study was conducted at centers in Heidelberg, Zurich, and Frankfurt. Results: 22 patients were included between April 2020 and December 2022 with a median age of 71 years. A total of 13 (59%) patients were re-exposed with the same antibody and nine (41%) received a different PD-(L)1 inhibitor. Six (46%) of the patients who were re-exposed to the same antibody had an irAE, of which 67% were identical with the first. In patients receiving a different PD-(L)1 inhibitor, four (44%) developed an irAE, of which 75% were identical with the first. Conclusions: Both an intraclass switch of PD-(L)1 inhibitor treatment and re-exposure with the same antibody after an irAE can be considered as options with a fair chance of improving therapy tolerance. Full article

Cancer immunotherapy has recently become an essential approach for treating cancer, showing considerable promise as a substitute for surgery, radiation therapy, and conventional chemotherapy. It primarily aims to boost the host’s natural defense system to combat cancer malignancies by utilizing components of immune checkpoint blockades (ICBs), mainly programmed cell death protein 1 (PD-1) and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), along with elements of adoptive cellular therapies (ACTs) like Chimeric Antigen Receptor (CAR) therapy, T Cell Receptor (TCR) therapy and Tumor-Infiltrating Lymphocyte (TIL) therapy. However, cancer cells tend to undermine the effectiveness of cancer immunotherapeutic strategies by employing one or more immune evasion mechanisms. This review briefly highlights how key mechanisms of cancer immune evasion confer resistance to immunotherapy and how the Clustered Regularly Interspaced Short Palindromic Repeats/Cas9 (CRISPR)/Cas9 systems, as gene-editing tools, are poised to enhance cancer immunotherapy for treating challenging cancers. We emphasize that (CRISPR/Cas9) systems can be used to explore and positively alter the genes of the immune system, boosting the effectiveness of cancer immunotherapy by editing immune checkpoints, TILs, and CAR-T cells, and disrupting genes, facilitating tumors’ evasion of the immune system. Furthermore, we highlight the growing interest in emerging base editor technology to engineer natural killer (NK) cells to overcome NK-cell-based immunotherapy challenges, particularly human leukocyte antigens (HLA)-mediated limitations, and to engineer CAR-T cells for improved immunotherapy outcomes. Full article

Background: While neutrophil extracellular traps (NETs) have been shown to contribute to cancer progression, including that of lung adenocarcinoma, the mechanisms underlying NET formation within the tumor immune microenvironment (TIME) remain incompletely understood. Notably, neutrophil infiltration has been strongly linked to tumor necrosis factor alpha-inducible protein 6 (TNFAIP6) expression. Methods: In vitro and in vivo experiments were performed. DNA pulldown coupled with mass spectrometry, bioinformatics analyses, immunohistochemistry, and dual-luciferase reporter assays were conducted. DNA pulldown Western blotting, chromatin immunoprecipitation–quantitative PCR, and dual-luciferase reporter assays using truncated promoter constructs were also employed. Results: TNFAIP6 expressed by lung adenocarcinoma cells was shown to induce NET formation (a form of programmed cell death called NETosis). Mechanistically, TNFAIP6 interacted with CD44 in lung adenocarcinoma cells, leading to increased extracellular availability of secreted phosphoprotein 1 (SPP1) within the TIME and the subsequent promotion of NETosis. Additionally, nucleophosmin 1 (NPM1) significantly enhances the transcriptional activation of TNFAIP6 and associates with the −2000 to −1700 bp region of its promoter. Conclusions: These findings delineate a regulatory model in which lung adenocarcinoma cells directly stimulate NETosis through the NPM1–TNFAIP6–CD44–SPP1 axis, suggesting that therapeutic targeting of this pathway may attenuate tumor progression. Full article

Background/Objectives: Programmed death ligand 1 (PD-L1) is often overexpressed in triple-negative breast cancer (TNBC), where it helps the tumor evade the immune system and promotes tumor growth. Interleukin-24 (IL-24) is recognized for its anti-tumor activity, although its role in immune regulation remains unclear. In this study, we examined the role of IL-24 in regulating PD-L1 and its anti-cancer activity in TNBC cells. Methods: The study used TNBC cell lines treated with IL-24, delivered via a non-replicating adenovirus vector expressing the IL-24 gene. Assays included MTT for cell viability, Annexin V for apoptosis, Western blot for protein analysis, and qRT-PCR for mRNA analysis. Results: We found that the highly aggressive MDA-MB-231 cells had significantly higher PD-L1 levels. We discovered that treatment with IL-24 reduced cell growth, induced apoptosis, and significantly decreased PD-L1 protein levels in MDA-MB-231 cells. Mechanistically, we identified PKR, also known as eukaryotic translation initiation factor 2 alpha kinase 2, as a key mediator of IL-24–induced PD-L1 suppression. Additionally, doxorubicin, a primary chemotherapy drug used to treat triple-negative breast cancer, decreases PD-L1 expression and increases the sensitivity when combined with IL-24. Conclusions: In this study, we show that IL-24 decreases PD-L1 expression in MDA-MB-231 cells through PKR activation, enhances the anti-tumor effects of Doxorubicin, and may enable lower doses that reduce toxicity and further decrease PD-L1 levels. These findings suggest that IL-24 could serve as a valuable target for therapeutic intervention and suggest that it can improve doxorubicin’s effectiveness against aggressive breast cancer. Full article

Programmed Death-Ligand 1 (PD-L1) promotes tumor progression through several mechanisms, including its intrinsic effect on breast cancer cell proliferation via the S-Phase Kinase-Associated Protein 2 (SKP2)–p21^Cip1/p27^Kip1 (SKP2-p21/p27) axis. However, the specific regulatory signaling through which PD-L1 influences the SKP2–p21/p27 axis to drive cell proliferation remains unclear. To investigate how PD-L1 mediates SKP2-dependent proliferation, proteomic analyses, gene-expression manipulation via knockdown or overexpression, Western blotting, quantitative immunofluorescence, colony-forming assays, real-time cell analysis, and Xenograft-derived cells were used. Proteomic data analysis identified several PD-L1 downstream targets as potential candidate regulators of the SKP2–p21/p27 axis and activators of the PI3K/AKT pathway. Candidate screening by gene knockdown, followed by analyses of SKP2, p21, and p27 protein expression, revealed Livin and Galectin-1 as upstream regulators of the SKP2–p21/p27 axis. Moreover, Western blotting and quantitative immunofluorescence in three breast cancer cell lines confirmed that PD-L1 is an upstream regulator of Livin, Galectin-1, and SKP2 protein expression. Mechanistically, Livin and Galectin-1 enhanced AKT phosphorylation (Ser473) to sustain PI3K/AKT pathway activation in a positive feedback loop to upregulate SKP2 expression. Functional assays, including colony-forming assays and real-time cell analyzer, demonstrated that Livin and Galectin-1 are critical for PD-L1-mediated, SKP2-dependent proliferation. These findings were corroborated in vivo using xenograft-derived cells. Overall, these findings delineate a tumor-intrinsic signaling axis in which PD-L1 upregulates Livin and Galectin-1 to sustain PI3K/AKT activity and drive SKP2-dependent cell proliferation. Targeting Livin and/or Galectin-1 may provide a rational strategy to disrupt PD-L1-associated proliferative signaling and improve combinatorial therapeutic approaches in breast cancer. Full article

Hepatocellular carcinoma (HCC) remains a leading cause of cancer-related death, yet adequate in vitro models mimicking the tumor immune microenvironment (TIME) are rare. Specifically, the role of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) in modulating interactions between tumor cells and tumor-associated macrophages (TAMs) is not fully understood. We established a 3D multicellular tumor spheroid (MCT) model using murine N-HCC25 cells with CRISPR/Cas9-mediated knockouts of Nrf2 and its negative regulator Kelch-like ECH-associated protein 1 (Keap1), the latter mimicking constitutive activation. N-HCC25 cells were co-cultured with bone marrow-derived macrophages (BMDMs) isolated from wild-type and Nrf2-knockout C57BL/6J mice. We compared co-culture setups (conditioned media, transwell systems, direct contact) using RT-qPCR, flow cytometry, and invasion assays. 3D spheroid systems better preserved stemness than 2D cultures and revealed functional Nrf2-dependent effects such as increased Vegf-α secretion in Keap1-deficient spheroids. Among the different co-cultivation models, the most profound effects were observed in the MCT model. Macrophages successfully integrated into the spheroids and triggered invasive outgrowth, whereas MCTs containing Nrf2-deficient macrophages displayed markedly reduced tumor spheroid growth and lower programmed cell death ligand-1 expression. These findings demonstrate that Nrf2 signaling in macrophages fosters an immunosuppressive and pro-invasive microenvironment. The established MCT model provides a suitable platform to further unravel Nrf2-dependent mechanisms in the HCC TIME. Full article