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The tumor suppressor TP53 gene, the most frequently mutated gene in human cancers, produces the product tumor protein p53, which plays an essential role in DNA damage. p53 protein mutations may contribute to tumorigenesis by loss of tumor suppressive functions and malignancy of cancer cells via gain‐of‐oncogenic functions. We previously reported that mutant p53 proteins form aggregates and that cytoplasmic p53 aggregates were associated with poor prognosis in human ovarian cancer. However, the prognostic impact of p53 aggregation in other tumors including lung squamous cell carcinoma (SCC) is poorly understood. Here, we demonstrated that lung SCC cases with cytoplasmic p53 aggregates had a significantly poor clinical prognosis. Analysis via patient‐derived tumor organoids (PDOs) established from lung SCC patients and possessing cytoplasmic p53 aggregates showed that eliminating cytoplasmic p53 aggregates suppressed cell proliferation. RNA sequencing and transcriptome analysis of p53 aggregate‐harboring PDOs indicated multiple candidate pathways involved in p53 aggregate oncogenic functions. With lung SCC‐derived cell lines, we found that cytoplasmic p53 aggregates contributed to cisplatin resistance. This study thus shows that p53 aggregates are a predictor of poor prognosis in lung SCC and suggests that detecting p53 aggregates via p53 conventional immunohistochemical analysis may aid patient selection for platinum‐based therapy. [ABSTRACT FROM AUTHOR]

Sinus macrophages in draining lymph nodes (DLNs) are involved in anti‐tumor immune reactions. CD169 (Sialoadhesin, Siglec‐1) is expressed on sinus macrophages and is considered a surrogate marker for the immunostimulatory phenotype of macrophages. In this study, the significance of sinus macrophages in immunotherapy was evaluated using mouse models. Treatment with anti‐programmed death‐ligand 1 (PD‐L1) antibody suppressed the subcutaneous tumor growth of MC38 and E0771 cells but was not effective against MB49 and LLC tumors. Decreased cytotoxic T‐lymphocyte (CTL) infiltration in tumor tissues and CD169 expression in sinus macrophages were observed in MB49 and LLC cells compared to corresponding parameters in MC38 and E0771 cells. The anti‐tumor effects of the anti‐PD‐L1 antibody on MC38 and E0771 cells were abolished when sinus macrophages in DLNs were depleted, suggesting that sinus macrophages are involved in the therapeutic effect of the anti‐PD‐L1 antibody. Naringin activated sinus macrophages. Naringin inhibited tumor growth in MB49‐ and LLC‐bearing mice but did not affect that in MC38‐ and E0771‐bearing mice. The infiltration of CTLs in tumor tissues and their activation were increased by naringin, and this effect was impaired when sinus macrophages were depleted. Combination therapy with naringin and anti‐PD‐L1 antibody suppressed MB49 tumor growth. In conclusion, CD169‐positive sinus macrophages in DLNs are critical for anti‐tumor immune responses, and naringin suppresses tumor growth by activating CD169‐positive sinus macrophages and anti‐tumor CTL responses. The activation status of sinus macrophages has been suggested to differ among tumor models, and this should be investigated in future studies. [ABSTRACT FROM AUTHOR]

The role of sinus macrophages (SMs) in anticancer immune responses has received considerable interest in recent years, but the types of molecules that are expressed in human SMs have not yet been clarified in detail. We therefore sought to identify dendritic cell (DC)– or macrophage‐related molecules in SMs in human lymph nodes (LNs). SMs are strongly positive for Iba‐1, CD163, CD169, and CD209. CD169 (clone SP216) reacted with almost all SMs, mainly in the cell surface membrane, while CD169 (clone HSn 7D2) reacted with a subpopulation of SMs, mainly in the cytoplasm, with a significant increase observed after IFN‐α stimulation. The immunoreactivity of clone HSn 7D2 was markedly reduced after transfection with small interfering RNA against CD169, while that of clone SP216 was slightly reduced. The induction of CCL8 and CXCL10 messenger RNA (mRNA) expression by IFN‐α was confirmed using cultured macrophages and RT‐qPCR, but fluorescence in situ hybridization did not detect CCL8 and CXCL10 mRNA expression in SMs. Single‐cell RNA sequence data of LNs indicated that the highest level of CXCL10 gene expression occurred in monocytes. In conclusion, we found that CD209, also known as DC‐related molecule, was expressed in human SMs. The heterogeneity observed in CD169 reacted with cone HSn 7D2 and SP216 was potentially due to the modification of CD169 protein by IFN stimulation. Further, no expression of CXCL10 mRNA in SMs suggested that SMs might be resident macrophages. [ABSTRACT FROM AUTHOR]

Cholangiocarcinoma (CCA) is an aggressive malignant tumor of bile duct epithelia. Recent evidence suggests the impact of cancer stem cells (CSC) on the therapeutic resistance of CCA; however, the knowledge of CSC in CCA is limited due to the lack of a CSC model. In this study, we successfully established a stable sphere‐forming CCA stem‐like cell, KKU‐055‐CSC, from the original CCA cell line, KKU‐055. The KKU‐055‐CSC exhibits CSC characteristics, including: (1) the ability to grow stably and withstand continuous passage for a long period of culture in the stem cell medium, (2) high expression of stem cell markers, (3) low responsiveness to standard chemotherapy drugs, (4) multilineage differentiation, and (5) faster and constant expansive tumor formation in xenograft mouse models. To identify the CCA‐CSC‐associated pathway, we have undertaken a global proteomics and functional cluster/network analysis. Proteomics identified the 5925 proteins in total, and the significantly upregulated proteins in CSC compared with FCS‐induced differentiated CSC and its parental cells were extracted. Network analysis revealed that high mobility group A1 (HMGA1) and Aurora A signaling through the signal transducer and activator of transcription 3 pathways were enriched in KKU‐055‐CSC. Knockdown of HMGA1 in KKU‐055‐CSC suppressed the expression of stem cell markers, induced the differentiation followed by cell proliferation, and enhanced sensitivity to chemotherapy drugs including Aurora A inhibitors. In silico analysis indicated that the expression of HMGA1 was correlated with Aurora A expressions and poor survival of CCA patients. In conclusion, we have established a unique CCA stem‐like cell model and identified the HMGA1‐Aurora A signaling as an important pathway for CSC‐CCA. [ABSTRACT FROM AUTHOR]

Immune checkpoint inhibitors (ICIs) have recently improved the prognosis of various cancers. By contrast, some immune‐related adverse events (irAEs) caused by ICIs are fatal and have become problematic. The pathogenesis of irAEs remains unknown and must be elucidated to establish biomarkers. This study investigated plasma cytokine, chemokine, and anti‐CD74 autoantibody levels in patients with renal cell carcinoma (RCC) and analyzed their association with irAEs. In a discovery cohort of 13 patients, plasma levels of chemokine (C–X–C motif) ligand (CXCL) 1, IL‐17A, IL‐1β, IL‐6, IL‐8, CXCL10, MCP‐1, and TNFα were measured at baseline and post–dose 1. Only CXCL10, at post–dose 1 but not at baseline, was significantly associated with grade 2 or higher irAEs (P = 0.0413). Plasma CXCL10 levels were then measured at baseline and post–dose 1 in an extended cohort of 43 patients with RCC who received ICI‐based treatment. Higher plasma CXCL10 levels both at baseline and post–dose1 were significantly associated with the occurrence of grade 2 or higher irAEs (P = 0.0246 and 0.0137, respectively). Plasma CXCL13 levels, which we measured in a previous study, were significantly higher in patients with grade 2 or higher irAEs at baseline but not at post–dose 1 (P = 0.0037 and 0.052, respectively). No significant association between plasma anti‐CD74 autoantibody level and both irAE pneumonitis and any grade 2 or higher irAE was observed. In conclusion, plasma CXCL10 is significantly associated with the occurrence of irAEs in patients with RCC treated with ICIs. CXCL10 is a potential predictive and on‐treatment biomarker for irAEs. [ABSTRACT FROM AUTHOR]

Tumor‐associated macrophages (TAMs) are the most prominent immune cells in the breast cancer microenvironment, and the protumor functions of TAMs are thought to affect cancer progression and resistance to anticancer therapy. Numerous studies using human breast cancer samples, cell lines, and murine breast cancer models have revealed details of the mechanisms by which the protumor functions of TAMs are activated. Recent advances have highlighted the significant involvement of TAMs in the resistance of breast cancer cells to immunotherapy. Tumor‐associated macrophages express a number of immunosuppressive genes, and single‐cell sequence analyses of human and murine cancer samples have helped elucidate the mechanism of TAM‐induced immunosuppression. As TAMs are considered suitable targets for anticancer therapies, we summarized the protumor functions of TAMs and the potential of anticancer therapies targeting TAMs, with a focus on breast cancer research. [ABSTRACT FROM AUTHOR]

Although pituitary neuroendocrine tumors (PitNETs) are usually benign, some are highly invasive and recurrent. Recurrent PitNETs are often treatment‐resistant and there is currently no effective evidence‐based treatment. Tumor‐associated macrophages (TAMs) promote tumor growth in many cancers, but the effect of TAMs on PitNETs remains unclear. This study investigated the role of TAMs in the incidence of recurrent PitNETs. Immunohistochemical analysis revealed that the densities of CD163‐ and CD204‐positive TAMs tended to increase in recurrent PitNETs. Compared with TAMs in primary lesions, those in recurrent lesions were enlarged. To clarify the cell–cell interactions between TAMs and PitNETs, in vitro experiments were performed using a mouse PitNET cell line AtT20 and the mouse macrophage cell line J774. Several cytokines related to macrophage chemotaxis and differentiation, such as M‐CSF, were elevated significantly by stimulation with macrophage conditioned medium. When M‐CSF immunohistochemistry analysis was performed using human PitNET samples, M‐CSF expression increased significantly in recurrent lesions compared with primary lesions. Although no M‐CSF receptor (M‐CSFR) expression was observed in tumor cells of primary and recurrent PitNETs, flow cytometric analysis revealed that the mouse PitNET cell line expressed M‐CSFR. Cellular proliferation in mouse PitNETs was inhibited by high concentrations of M‐CSFR inhibitors, suggesting that cell‐to‐cell communication between PitNETs and macrophages induces M‐CSF expression, which in turn enhances TAM chemotaxis and maturation in the tumor microenvironment. Blocking the M‐CSFR signaling pathway might be a novel therapeutic adjuvant in treating recurrent PitNETs. [ABSTRACT FROM AUTHOR]

Cholesterol is an essential plasma membrane lipid for the maintenance of cellular homeostasis and cancer cell proliferation. Free cholesterol is harmful to cells; therefore, excessive free cholesterol must be quickly esterified by acetyl‐coenzyme A:cholesterol acetyltransferase (ACAT) and exported by scavenger receptor class B member I (SR‐BI) or ATP‐binding cassette protein A1 from specific cells such as macrophage foam cells, which contain cholesteryl ester‐derived vacuoles. Many vacuoles are present in the cytoplasm of Burkitt lymphoma cells. In this study, we observed that these vacuoles are often seen in high‐grade lymphomas. Cell culture study using lymphoma cell lines found that esterified cholesterol is the main component of these vacuoles and the expression of cholesterol metabolism‐related molecules was significantly upregulated in lymphoma cell lines, with SR‐BI and ACAT inhibitors (BLT‐1 and CI‐976, respectively) impeding lymphoma cell proliferation. Cytoplasmic free cholesterol was increased by ACAT and SR‐BI inhibitors, and the accumulation of free cholesterol induced lymphoma cell apoptosis by inducing endoplasmic reticulum stress. Furthermore, synergistic effects of SR‐BI and ACAT inhibitors were observed in a preclinical study. Treatment with SR‐BI inhibitor suppressed lymphoma progression in a tumor‐bearing mouse model, whereas ACAT inhibitor did not. Therefore, SR‐BI inhibitors are potential new antilymphoma therapeutics that target cholesterol metabolism. [ABSTRACT FROM AUTHOR]

Recent studies have indicated the clinical significance of tumor-associated macrophages ( TAM) in several malignant tumors including breast cancer. Although recent studies have focused on CD68-positive or CD163-positive TAM in breast cancer, no study has investigated the significance of CD204-positive TAM in breast cancer. We found that CD204 expression on macrophages was evaluated following stimulation with the conditioned medium ( CM) of breast cancer cell lines. Paraffin sections of 149 breast cancer samples which were diagnosed as invasive ductal carcinoma were immunohistochemically analyzed for CD68, CD163 and CD204 expression. The results of analyses indicated that a high number of CD204-positive TAM was associated with worse clinical prognoses, including relapse-free survival, distant relapse-free survival and breast cancer-specific survival; however, neither the numbers of CD68-positive or CD163-positive TAM were associated with clinical courses. Of the clinicopathological factors investigated, estrogen receptor, Ki-67 index, hormone subtype, and histological grade were significantly related to the increased number of CD163-positive and CD204-positive TAM. These data indicate the clinical significance of CD204-positive TAM in breast cancer progression and CD204 is a marker for predicting clinical prognosis in breast cancer. [ABSTRACT FROM AUTHOR]

Immune escape and tolerance in the tumor microenvironment are closely involved in tumor progression, and are caused by T-cell exhaustion and mediated by the inhibitory signaling of immune checkpoint molecules including programmed death-1 ( PD-1), cytotoxic T-lymphocyte associated protein 4, and T-cell immunoglobulin and mucin domaincontaining molecule-3. In the present study, we investigated the expression of the PD-1 ligand 1 ( PD-L1) in a lymphoma microenvironment using paraffin-embedded tissue samples, and subsequently studied the detailed mechanism of upregulation of PD-L1 on macrophages using cultured human macrophages and lymphoma cell lines. We found that macrophages in lymphoma tissues of almost all cases of adult T-cell leukemia/lymphoma ( ATLL), follicular lymphoma and diffuse large B-cell lymphoma expressed PD-L1. Cell culture studies showed that the conditioned medium of ATL-T and SLVL cell lines induced increased expression of PD-L1/2 on macrophages, and that this PD-L1/2 overexpression was dependent on activation of signal transducer and activator of transcription 3 (Stat3). In vitro studies including cytokine array analysis showed that IL-27 (heterodimer of p28 and EBI3) induced overexpression of PD-L1/2 on macrophages via Stat3 activation. Because lymphoma cell lines produced IL-27B ( EBI3) but not IL-27p28, it was proposed that the IL-27p28 derived from macrophages and the IL-27B ( EBI3) derived from lymphoma cells formed an IL-27 (heterodimer) that induced PD-L1/2 overexpression. Although the significance of PD-L1/2 expressions on macrophages in lymphoma progression has never been clarified, an IL-27-Stat3 axis might be a target for immunotherapy for lymphoma patients. [ABSTRACT FROM AUTHOR]