M2 macrophages drive leukemic transformation by imposing resistance to phagocytosis and improving mitochondrial metabolism.

It is increasingly becoming clear that cancers are a symbiosis of diverse cell types and tumor clones. Combined single-cell RNA sequencing, flow cytometry, and immunohistochemistry studies of the innate immune compartment in the bone marrow of patients with acute myeloid leukemia (AML) reveal a shift toward a tumor-supportive M2-polarized macrophage landscape with an altered transcriptional program, with enhanced fatty acid oxidation and NAD+ generation. Functionally, these AML-associated macrophages display decreased phagocytic activity and intra-bone marrow coinjection of M2 macrophages together with leukemic blasts strongly enhances in vivo transformation potential. A 2-day in vitro exposure to M2 macrophages results in the accumulation of CALRlow leukemic blast cells, which are now protected against phagocytosis. Moreover, M2-exposed "trained" leukemic blasts display increased mitochondrial metabolism, in part mediated via mitochondrial transfer. Our study provides insight into the mechanisms by which the immune landscape contributes to aggressive leukemia development and provides alternatives for targeting strategies aimed at the tumor microenvironment.

MLL5 improves ATRA driven differentiation and promotes xenotransplant engraftment in acute promyelocytic leukemia model.

Although the mixed lineage leukemia 5 (MLL5) gene has prognostic implications in acute promyelocyte leukemia (APL), the underlying mechanism remains to be elucidated. Here, we demonstrate the critical role exerted by MLL5 in APL regarding cell proliferation and resistance to drug-induced apoptosis, through mtROS regulation. Additionally, MLL5 overexpression increased the responsiveness of APL leukemic cells to all-trans retinoic acid (ATRA)-induced differentiation, via regulation of the epigenetic modifiers SETD7 and LSD1. In silico analysis indicated that APL blasts with MLL5high transcript levels were associated with retinoic acid binding and downstream signaling, while MLL5low blasts displayed decreased expression of epigenetic modifiers (such as KMT2C, PHF8 and ARID4A). Finally, APL xenograft transplants demonstrated improved engraftment of MLL5-expressing cells and increased myeloid differentiation over time. Concordantly, evaluation of engrafted blasts revealed increased responsiveness of MLL5-expressing cells to ATRA-induced granulocytic differentiation. Together, we describe the epigenetic changes triggered by the interaction of MLL5 and ATRA resulting in enhanced granulocytic differentiation.

Exuberant hypercementosis mimicking cementoblastoma / Hipercementose exuberante simulando cementoblastoma

RESUMEN La hipercementosis se clasifica como una proliferación no neoplásica que implica un depósito excesivo de cemento a lo largo del cemento radicular normal. Presentamos el caso de un paciente masculino de 77 años que acude al dentista por una lesión supurativa en la encía que evoluciona desde hace varios meses. El examen radiográfico mostró una gran área radiopaca involucrando la raíz del diente 46, que estaba completamente rodeada por un área radiolúcida, sugiriendo un cementoblastoma asociado con el proceso infeccioso. El examen histopatológico del diente afectado reveló hipercementosis extensa asociada con inflamación supurativa crónica, además de osteomielitis crónica localizada. Esta presentación es infrecuente y, debido a los hallazgos clínico-patológicos, se propone el término "hipercementitis crónica". Los dentistas, especialmente los patólogos orales y endodoncistas, deben estar tener conocimiento de esta inusual presentación para establecer el diagnóstico correcto.

The antimetastatic activity of orlistat is accompanied by an antitumoral immune response in mouse melanoma.

PURPOSE: Fatty acid synthase (FASN), the multifunctional enzyme responsible for endogenous fatty acid synthesis, is highly expressed and associated with poor prognosis in several human cancers, including melanoma. Our group has previously shown that pharmacological inhibition of FASN with orlistat decreases proliferation, promotes apoptosis, and reduces the metastatic spread of B16-F10 cells in experimental models of melanoma. While most of the orlistat antitumor properties seem to be closely related to direct effects on malignant cells, its impact on the host immune system is still unknown. METHODS: The effects of orlistat on the phenotype and activation status of infiltrating leukocytes in primary tumors and metastatic lymph nodes were assessed using a model of spontaneous melanoma metastasis (B16-F10 cells/C57BL/6 mice). Cells from the primary tumors and lymph nodes were mechanically dissociated and immune cells phenotyped by flow cytometry. The expression of IL-12p35, IL-12p40, and inducible nitric oxide synthase (iNOS) was analyzed by qRT-PCR and production of nitrite (NO2-) evaluated in serum samples with the Griess method. RESULTS: Orlistat-treated mice exhibited a 25% reduction in the number of mediastinal lymph node metastases (mean 3.96 ± 0.78, 95% CI 3.63-4.28) compared to the controls (mean 5.7 ± 1.72; 95% CI 5.01-6.43). The drug elicited an antitumor immune response against experimental melanomas by increasing maturation of intratumoral dendritic cells (DC), stimulating the expression of cytotoxicity markers in CD8 T lymphocytes and natural killer (NK) cells, as well as reducing regulatory T cells (Tregs). Moreover, the orlistat-treatment increased serum levels of nitric oxide (NO) concentrations. CONCLUSION: Taken together, these findings suggest that orlistat supports an antitumor response against experimental melanomas by increasing CD80/CD81-positive and IL-12-positive DC populations, granzyme b/NKG2D-positive NK populations, and perforin/granzyme b-positive CD8 T lymphocytes as well as reducing Tregs counts within experimental melanomas.

SMARCB1 (INI-1) and NUT immunoexpression in a large series of head and neck carcinomas in a Brazilian reference center.

BACKGROUND: SMARCB1 (INI-1)-deficient carcinomas and NUT carcinomas are aggressive neoplasms, often affecting the sinonasal region. Not uncommonly, their diagnoses are made retrospectively. METHODS: Through SMARCB1 (INI-1) and NUT immunomarkers, 643 head and neck carcinomas were assessed retrospectively. Moreover, SMARCB1 (INI-1)-deficient and NUT carcinomas were additionally evaluated by immunohistochemistry, as well as in situ hybridization analysis for HPV and EBV. RESULTS: Four SMARCB1 (INI-1)-deficient carcinomas (located in lower lip, soft palate, hypopharynx and vocal cord, this latter high-risk HPV positive) and three NUT carcinomas (all located in oropharynx) were detected, previously diagnosed as nonkeratinizing or moderately differentiated squamous cell carcinoma. All cases showed squamous differentiation. NUT carcinomas than SMARCB1 (INI-1)-deficient carcinomas showed low overall survival rate. CONCLUSION: The current cases expand the clinicopathological spectrum of SMARCB1 (INI-1)-deficient carcinomas and NUT carcinomas. Notably, the diagnosis of these cases is easily reached through immunohistochemistry, with impact on their accurate classification, treatment, and prognosis.

Gingival carcinoma cuniculatum mimicking a reactive/inflammatory process / Carcinoma cuniculado gengival mimetizando um processo inflamatório/reativo

ABSTRACT Carcinoma cuniculatum (CC), a rare variant of oral squamous cell carcinoma, presents well-differentiated neoplastic epithelial cells infiltrating the underlying submucosal or bone tissues, forming the so-called "rabbit burrows" filled with keratin. A 67-year-old female patient was referred complaining of a painless tumoral mass in the left mandibular body, with several months of evolution. Previous history indicated extraction of the teeth #37 and #38 and diagnosis of chronic suppurative osteomyelitis. A deep incisional biopsy revealed CC. Due to its microscopic features, suggesting an inflammatory or reactive process, strict clinicopathological correlation is necessary for the correct diagnosis of CC.

RESUMEN El carcinoma cuniculatum (CC), una variante del carcinoma de células escamosas oral, presenta células epiteliales neoplásicas bien diferenciadas que se infiltran en la submucosa o en el tejido óseo subyacente, formando la llamada "madriguera de conejo", rellenada con queratina. Reportamos el caso de una paciente de 67 años con quejas de una masa tumoral asintomática en el cuerpo mandibular izquierdo con varios meses de evolución. La historia previa apuntó exodoncia de los dientes 37 y 38 y diagnóstico de osteomielitis supurativa crónica. Una biopsia incisional profunda reveló CC. Debido a las características microscópicas, que sugirieron un proceso inflamatorio o reactivo, es necesaria una estrecha correlación clinicopatológica para el diagnóstico correcto del CC.

RESUMO O carcinoma cuniculado (CC), uma rara variante do carcinoma espinocelular oral, apresenta células epiteliais neoplásicas bem diferenciadas que se infiltram na submucosa ou no tecido ósseo subjacente, formando a chamada "toca de coelho", preenchida por queratina. Relatamos o caso de uma paciente de 67 anos que foi encaminhada apresentando uma massa tumoral assintomática no corpo mandibular esquerdo com vários meses de evolução. A história prévia indicou exodontia dos dentes 37 e 38 e diagnóstico de osteomielite supurativa crônica. Uma biópsia incisional profunda revelou CC. Devido às características microscópicas, as quais sugeriram um processo inflamatório ou reativo, é necessário estrita correlação clinicopatológica para o correto diagnóstico do CC.

Young and elderly oral squamous cell carcinoma patients present similar angiogenic profile and predominance of M2 macrophages: Comparative immunohistochemical study.

BACKGROUND: M2 macrophages are often detected in oral squamous cell carcinoma (OSCC), which, influenced by hypoxic conditions, appear to have high angiogenesis-inducing capacity. However, the effects of immunosenescence on tumor-associated macrophages (TAMs) and angiogenesis in OSCC are unknown. METHODS: Fifty-seven OSCCs were divided into 3 groups (I: <40 years [n = 17]; II: 40-65 years [n = 20]; III: >65 years [n = 20]). Immunohistochemistry for CD68 and CD163 (TAMs), and CD34 and D2-40 for microvessel density (MVD), microvessel area (MVA), and total vascular area (TVA) were performed. RESULTS: All groups showed similar clinicopathological and immunohistochemical findings. Similar CD68 and CD163 expression, confirmed a M2 phenotype. MVD, MVA, and TVA were similar, however, with significant predominance of blood vessels. No significant correlation between macrophage and angiogenic markers was observed. CONCLUSIONS: A similar TAM and angiogenesis profile suggests the participation of other mechanisms, instead immunosenescence, in young and elderly OSCC patients.

Low-fat and fat-free spindle cell lipomas in the oral cavity: Immunohistochemical analysis and review of the literature.

The low-fat and fat-free spindle cell lipomas (SCLs) are rare and often mistaken for other benign and malignant morphological mimics, because of the fact that the diagnosis relies on its non-lipogenic component analysis. Here, we report the clinicopathological features of two oral SCLs (low-fat and fat-free variants). Both lesions presented clinically as an asymptomatic nodule, which initially yielded diagnostic difficulties on the morphological analysis alone. One case was diagnosed as low-fat SCL on the lower lip in a 29-year-old man, and the other as fat-free SCL on the buccal mucosa in a 46-year-old man. In both cases, immunohistochemistry showed strong positivity for CD34 and, remarkably, retinoblastoma (Rb) protein was deficient. Mast cell (MC) tryptase and toluidine blue stain highlighted numerous MCs distributed throughout all tumor stroma. Alpha-SMA and desmin were negative. S100 evidenced scarce adipocytes only in the low-fat SCL case. Conservative surgical treatment was performed and no recurrence was noticed in about 2-year of follow-up in both cases. Because of the potential pitfalls, careful morphological analysis of the tumor stroma in the low-fat/fat-free SCL diagnosis, supported by immunohistochemistry (especially CD34, Rb and MC tryptase), is strongly recommended. To the best of our knowledge, these are the first and second cases reported of fat-free and low-fat SCL in the oral cavity.

Immature, but Not Mature, Dendritic Cells Are More Often Present in Aggressive Periodontitis Than Chronic Periodontitis: An Immunohistochemical Study.

BACKGROUND: Dendritic cells (DCs) form a key link between innate and adaptive immune responses. The aim of this study is to analyze presence and distribution of immature (im) and mature (m) DCs in gingival tissue samples obtained from patients diagnosed with aggressive periodontitis (AgP), chronic periodontitis (CP), and clinically healthy periodontium (control group). METHODS: Gingival tissue samples obtained from patients with: 1) AgP (aged <35 years); 2) CP (aged ≥35 years); and 3) control group (aged >18 years) (n = 10 per group) were collected. Two-way analysis of variance and posterior Fisher least significant difference test were used to observe differences between the means of cells positively marked for imDC (S100, CD1a, and CD207) and mDC (CD208) immunomarkers. RESULTS: imDCs were more numerous in AgP than CP and control groups, being statistically significant only for S100+ cells. Conversely, mDCs were visualized in higher numbers in CP than AgP and control groups (both P <0.05). Considering frequency of immunostained cells, the number of S100+ cells was greater than CD207+ and CD1a+ cells, followed by a lesser number of CD208+ cells, in all groups. CONCLUSIONS: Considering that the ability of DCs to regulate immunity is dependent on DC maturation, results suggest that predominance of imDCs appears to be involved in AgP pathogenesis, probably due to lack of ability to induce immune cell activation. Further studies are necessary to elucidate the role of DC maturation in regulating immune responses in periodontal disease.

The fatty acid synthase inhibitor orlistat reduces the growth and metastasis of orthotopic tongue oral squamous cell carcinomas.

Fatty acid synthase (FASN) is the biosynthetic enzyme responsible for the endogenous synthesis of fatty acids. It is downregulated in most normal cells, except in lipogenic tissues such as liver, lactating breast, fetal lung, and adipose tissue. Conversely, several human cancers, including head and neck squamous cell carcinomas (HNSCC), overexpress FASN, which has been associated with poor prognosis and recently suggested as a metabolic oncoprotein. Orlistat is an irreversible inhibitor of FASN activity with cytotoxic properties on several cancer cell lines that inhibits tumor progression and metastasis in prostate cancer xenografts and experimental melanomas, respectively. To explore whether the inhibition of FASN could impact oral tongue squamous cell carcinoma (OTSCC) metastatic spread, an orthotopic model was developed by the implantation of SCC-9 ZsGreen LN-1 cells into the tongue of BALB/c nude mice. These cells were isolated through in vivo selection, show a more invasive behavior in vitro than the parental cells, and generate orthotopic tumors that spontaneously metastasize to cervical lymph nodes in 10 to 15 days only. SCC-9 ZsGreen LN-1 cells also exhibit enhanced production of MMP-2, ERBB2, and CDH2. The treatment with orlistat reduced proliferation and migration, promoted apoptosis, and stimulated the secretion of VEGFA165b by SCC-9 ZsGreen LN-1 cells. In vivo, the drug was able to decrease both the volume and proliferation indexes of the tongue orthotopic tumors and, importantly, reduced the number of metastatic cervical lymph nodes by 43%. These results suggest that FASN is a potential molecular target for the chemotherapy of patients with OTSCC.