Erythrophagocytosis by epithelial cells of a breast carcinoma

Ez-Metastasizing: The Crucial Roles of Ezrin in Metastasis

Ezrin is the cytoskeletal organizer and functions in the modulation of membrane-cytoskeleton interaction, maintenance of cell shape and structure, and regulation of cell-cell adhesion and movement, as well as cell survival. Ezrin plays a critical role in regulating tumor metastasis through interaction with other binding proteins. Notably, Ezrin has been reported to interact with immune cells, allowing tumor cells to escape immune attack in metastasis. Here, we review the main functions of Ezrin, the mechanisms through which it acts, its role in tumor metastasis, and its potential as a therapeutic target.

Glioma cells remotely promote erythropoiesis as a self-expanding strategy of cancer stem cells

Cancer stem cells are a promising target for cancer eradication due to their responsibility for therapy-resistance and cancer recurrence. Previously, we have demonstrated that glioma stem cells (GSCs) recruit and induce the differentiation of bone marrow (BM) monocytes into tumor-infiltrating macrophages, which phagocytose hemorrhaged erythrocytes and store GSC-beneficial iron in mouse xenografts, suggesting a self-expanding strategy of GSCs that exploits host hematopoiesis of myeloid cells. However, it remains unclear whether a self-advantageous effect of GSCs also occurs on erythroid cells during glioma development. Here, we found that, in the primary cultures of mouse fetal liver proerythroblasts (proEs), conditioned media prepared from glioma cells including patient-derived glioblastoma (GBM) cells significantly facilitated the differentiation of proEs into erythroblasts. Importantly, in-vivo erythroid analysis in intracranially GSC-transplanted mice showed an enhanced erythropoiesis in the BM. In addition, the sphere forming ability of patient-derived GBM cells was significantly suppressed by hypoxia treatment and iron chelation, suggesting higher demands of GSCs for oxygen and iron, which may be supplied by GSCs- and their progeny-induced erythrocyte production. Our findings provide a new insight into survival and expanding strategies of GSCs that systemically exploit host erythropoiesis.

Construction of bifunctional living red blood cells for combined photothermal-chemotherapy

Modifying living cells using in-situ synthesized nanomaterials to endow them with new functions is highly desirable. Herein we report intra- and extra-cellular dual-modified red blood cells (RBCs) with intracellular CaCO₃ nanoparticles (NPs) and extracellular polypyrrole-folic acid (PPy-FA) coating, which are exploited as a bifunctional drug carrier. The functionalized living cells (CaCO₃@RBC@PPy-FA) are fabricated through first the intracellular in situ reaction of exogenous Ca²⁺ and CO₃^2- ions to generate CaCO₃ NPs, then polymerization of pyrrole and finally modification of folic acid (FA) on the membrane of individual cells, forming a CaCO₃@RBC@PPy-FA structure. As a result, such dual-modified RBCs not only preserve the original performances of the cells but also possess the desirable properties as a drug carrier, such as high loading capacity due to the action of CaCO₃ NPs, targeting and light-controlled drug release due to the action of PPy-FA. Under NIR laser stimulation, these bifunctional RBCs (DOX-CaCO₃@RBC@PPy-FA) present an instant release profile of doxorubicin (DOX) and have high targeting-ability toward cancer cells, achieving a marked synergistic combined photothermal-chemotherapy effect.

Consideration of Ketogenic Metabolic Therapy as a Complementary or Alternative Approach for Managing Breast Cancer

Breast cancer remains as a significant cause of morbidity and mortality in women. Ultrastructural and biochemical evidence from breast biopsy tissue and cancer cells shows mitochondrial abnormalities that are incompatible with energy production through oxidative phosphorylation (OxPhos). Consequently, breast cancer, like most cancers, will become more reliant on substrate level phosphorylation (fermentation) than on oxidative phosphorylation (OxPhos) for growth consistent with the mitochondrial metabolic theory of cancer. Glucose and glutamine are the prime fermentable fuels that underlie therapy resistance and drive breast cancer growth through substrate level phosphorylation (SLP) in both the cytoplasm (Warburg effect) and the mitochondria (Q-effect), respectively. Emerging evidence indicates that ketogenic metabolic therapy (KMT) can reduce glucose availability to tumor cells while simultaneously elevating ketone bodies, a non-fermentable metabolic fuel. It is suggested that KMT would be most effective when used together with glutamine targeting. Information is reviewed for suggesting how KMT could reduce systemic inflammation and target tumor cells without causing damage to normal cells. Implementation of KMT in the clinic could improve progression free and overall survival for patients with breast cancer.

Nano-hole induction by nanodiamond and nanoplatinum liquid, DPV576, reverses multidrug resistance in human myeloid leukemia (HL60/AR)

Recently nanoparticles have been extensively studied and have proven to be a promising candidate for cancer treatment and diagnosis. In the current study, we examined the chemo-sensitizing activity of a mixture of nanodiamond (ND) and nanoplatinum (NP) solution known as DPV576, against multidrug-resistant (MDR) human myeloid leukemia (HL60/AR) and MDR-sensitive cells (HL60). Cancer cells were cultured with different concentrations of daunorubicin (DNR) (1 × 10 ⁻⁹−1 × 10 ⁻⁶ M) in the presence of selected concentrations of DPV576 (2.5%–10% v/v). Cancer cell survival was determined by MTT assay, drug accumulation by flow cytometry and confocal laser scanning microscopy (CLSM), and holes and structural changes by atomic force microscopy (AFM). Co-treatment of HL60/AR cells with DNR plus DPV576 resulted in the reduction of the IC₅₀ to 1/4th. This was associated with increased incidences of holes inside the cells as compared with control untreated cells. On the other hand, HL60 cells did not show changes in their drug accumulation post-treatment with DPV576 and DNR. We conclude that DPV576 is an effective chemo-sensitizer as indicated by the reversal of HL60/AR cells to DNR and may represent a potential novel adjuvant for the treatment of chemo-resistant human myeloid leukemia.

On the origin of cancer metastasis

Metastasis involves the spread of cancer cells from the primary tumor to surrounding tissues and to distant organs and is the primary cause of cancer morbidity and mortality. In order to complete the metastatic cascade, cancer cells must detach from the primary tumor, intravasate into the circulatory and lymphatic systems, evade immune attack, extravasate at distant capillary beds, and invade and proliferate in distant organs. Currently, several hypotheses have been advanced to explain the origin of cancer metastasis. These involve an epithelial mesenchymal transition, an accumulation of mutations in stem cells, a macrophage facilitation process, and a macrophage origin involving either transformation or fusion hybridization with neoplastic cells. Many of the properties of metastatic cancer cells are also seen in normal macrophages. A macrophage origin of metastasis can also explain the long-standing "seed and soil" hypothesis and the absence of metastasis in plant cancers. The view of metastasis as a macrophage metabolic disease can provide novel insight for therapeutic management.

Perspectives on the mesenchymal origin of metastatic cancer

Emerging evidence suggests that many metastatic cancers arise from cells of the myeloid/macrophage lineage regardless of the primary tissue of origin. A myeloid origin of metastatic cancer stands apart from origins involving clonal evolution or epithelial-mesenchymal transitions. Evidence is reviewed demonstrating that numerous human cancers express multiple properties of macrophages including phagocytosis, fusogenicity, and gene/protein expression. It is unlikely that the macrophage properties expressed in metastatic cancers arise from sporadic random mutations in epithelial cells, but rather from damage to an already existing mesenchymal cell, e.g., a myeloid/macrophage-type cell. Such cells would naturally embody the capacity to express the multiple behaviors of metastatic cells. The view of metastasis as a myeloid/macrophage disease will impact future cancer research and anti-metastatic therapies.

Cancer as a metabolic disease

Emerging evidence indicates that impaired cellular energy metabolism is the defining characteristic of nearly all cancers regardless of cellular or tissue origin. In contrast to normal cells, which derive most of their usable energy from oxidative phosphorylation, most cancer cells become heavily dependent on substrate level phosphorylation to meet energy demands. Evidence is reviewed supporting a general hypothesis that genomic instability and essentially all hallmarks of cancer, including aerobic glycolysis (Warburg effect), can be linked to impaired mitochondrial function and energy metabolism. A view of cancer as primarily a metabolic disease will impact approaches to cancer management and prevention.

Influence of methotrexate and cisplatin on tumor progression and survival in the VM mouse model of systemic metastatic cancer

We recently identified a new tumor (VM-M3), which arose spontaneously in the brain of an inbred VM mouse. When grown outside the brain, the VM-M3 tumor expresses all major biological processes of metastasis to include local invasion, intravasation, immune system survival, extravasation, and secondary tumor formation involving lung, liver, kidney, spleen and brain. The VM-M3 tumor also expresses multiple properties of macrophage-like cells similar to those described previously in numerous human metastatic cancers suggesting that the VM-M3 model will be useful for studying most types of metastatic cancer, regardless of tissue origin. VM-M3 tumor cells, expressing firefly luciferase (VM-M3/Fluc), were grown subcutaneously in the immunocompetent and syngeneic VM mouse host. The antimetastatic effects of methotrexate (MTX; 25 mg/kg) and cisplatin (10-15 mg/kg) were evaluated following i.p. injections administered once/wk for 3 weeks. Bioluminescent imaging was used to measure VM-M3/Fluc growth and metastasis. All (12/12) control mice developed systemic cancer within 21 days of subcutaneous VM-M3/Fluc implantation. Although methotrexate did not inhibit VM-M3/Fluc primary tumor growth, it reduced lung and liver metastasis by 50% and completely inhibited metastasis to kidneys, spleen and brain. Cisplatin significantly reduced primary tumor growth, blocked metastasis to lung, liver, kidneys, spleen and brain, and significantly increased survival in all treated animals. Our findings show that the response of the VM-M3/Fluc tumor to MTX and cisplatin is similar to that reported in humans with metastatic disease. These findings indicate that the VM-M3/Fluc tumor is a reliable preclinical model for evaluating antimetastatic cancer therapies and underlying control pathways.

The human homologue of Dictyostelium discoideum phg1A is expressed by human metastatic melanoma cells

Tumour cannibalism is a characteristic of malignancy and metastatic behaviour. This atypical phagocytic activity is a crucial survival option for tumours in conditions of low nutrient supply, and has some similarities to the phagocytic activity of unicellular microorganisms. In fact, Dictyostelium discoideum has been used widely as a model to study phagocytosis. Recently, phg1A has been described as a protein that is primarily involved in the phagocytic process of this microorganism. The closest human homologue to phg1A is transmembrane 9 superfamily protein member 4 (TM9SF4). Here, we report that TM9SF4 is highly expressed in human malignant melanoma cells deriving from metastatic lesions, whereas it is undetectable in healthy human tissues and cells. TM9SF4 is predominantly expressed in acidic vesicles of melanoma cells, in which it co-localizes with the early endosome antigens Rab5 and early endosome antigen 1. TM9SF4 silencing induced marked inhibition of cannibal activity, which is consistent with a derangement of intracellular pH gradients, with alkalinization of acidic vesicles and acidification of the cell cytosol. We propose TM9SF4 as a new marker of malignancy, representing a potential new target for anti-tumour strategies with a specific role in tumour cannibalism and in the establishment of a metastatic phenotype.

New technologies used in the study of human melanoma

The amount of information on tumor biology has expanded enormously, essentially due to the completion of the human genome sequencing and to the application of new technologies that represent an exciting breakthrough in molecular analysis. Often these data spring from experimental procedures, such as a serial analysis of gene expression (SAGE) and DNA microarrays, which cannot be defined as hypothesis-driven: it may appear to be a "brute force" approach through which no information can be directly generated concerning the specific functions of selected genes in a definite context. However, interesting results are fruitfully generated, and thus it is important to consider the enormous potential these new technologies possess and to learn how to apply this novel form of knowledge in the emerging field of molecular medicine. This review, after a limited outline regarding several classic aspects of human cutaneous melanoma biology, genetics, and clinical approaches, will focus on the proficient use of up-to-date technologies in the study of the neoplastic disease and on their capability to provide effective support to conventional approaches in melanoma diagnosis, prognosis, and treatment.

Phagocytosis of Candida albicans by metastatic and non metastatic human breast cancer cell lines in vitro

Experiments were carried out to investigate the kinetic characteristics of phagocytosis of candida by metastatic (MCF-7 and ZR-75-1) and nonmetastatic (HCC70) breast cancer cell (BCC) lines. Cancer cells were mixed with candida at a ratio of 1:10 and attachment/phagocytosis were examined using cytospin preparations stained with either Giemsa or tannic acid and May-Grünwald Giemsa and by using flow cytometry. A high attachment of candida to cancer cells (29-39%) was detected as early as 10 min. Following attachment, cancer cells phagocytized yeast. The phagocytic activity of MCF-7 and ZR-75 cells was significantly higher (58-61%) than that of HCC70 cells (26%). A similar trend was observed with respect to the phagocytic index. Phagocytosis of candida by tumor cells was inhibited significantly by both cytochalasin B (50%) and by lowering temperature to 4 degrees C (66%). Phagocytosis was not associated with oxidative burst in any cell lines used. In conclusion, metastatic breast cancer cells possess phagocytic activity which may explain their invasive property.

Phagocytosis of candida albicans by lymphatic tumour cells in vitro

Experiments were carried out to investigate whether different lymphatic tumour cell lines have similar kinetic characteristics of phagocytosis of microorganisms. Six tumour cell lines were used. These were a human T-cell line (CEM), a mouse T-cell line (YAC-1), a human B-cell line (LAZ), and a human erythroleukemic tumour cells (K562), whereas 2 cell lines of professional phagocytosis were used as controls, a human macrophage cell line (THP1) and a mouse macrophage cell line (P388D1). Tumour cells were mixed with candida albicans at a ratio of 10:1 of candida to tumour cells and the percentage of tumour cells that had attached/phagocytosed candida was determined. After 4 h coculture with candida, tumour cells not of T-cell origin (LAZ and K562) showed moderate level of phagocytosis (28%), whereas tumour cells of T-cell origin (CEM and YAC-1) demonstrated low levels of phagocytosis (15%) as compared to macrophage cell lines (THP1 and P388D1) that showed maximum phagocytosis (64-78%). Acid phosphatase (AcPase) activity was increased by 33% during coculture of YAC-1 cells and yeast cells. In conclusion, the results suggest that lymphatic tumour cells of nonphagocytic origin acquire phagocytic properties during the course of malignancy, and digestion of phagocytosed yeast cells maybe related with AcPase activity, as well as that of other lysosomal enzymes. This phenomenon may represent one mechanism by which tumour cells downregulate immune surveillance.

Potent phagocytic activity discriminates metastatic and primary human malignant melanomas: a key role of ezrin

Features of phagocytosis have been observed in human tumors, but the phagocytic apparatus of tumor cells and the mechanism(s) underlying this phenomenon have yet to be defined. To address the phenomenon of phagocytosis, its underlying mechanism(s), and its possible role in tumor biology, we used human melanoma cells as a prototypic model. Our results showed that a process of phagocytosis of apoptotic cells occurs in vivo in human melanoma. This finding was consistent with evidence that human melanoma cells in vitro express all of the known lysosomal and phagocytic markers on their cytoplasmic vesicles and that a process of phagocytosis occurs in these vesicles. However, exclusively human melanoma cells deriving from metastatic lesions possess an efficient phagocytic machinery responsible for a macrophage-like activity against latex beads, yeast, and apoptotic cells of different origins, which was comparable to that of human primary macrophages. Moreover, the actin-binding protein ezrin was expressed on phagocytic vacuoles of melanoma cells and of cells deriving from a human adenocarcinoma; both treatment with cytochalasin B and specific inhibition of ezrin synthesis strongly affected the phagocytic activity of melanoma cells. This suggests that the association with the actin cytoskeleton is a crucial requirement for the development of this phenomenon. Hence our data provide evidence for a potent phagocytic activity exerted by metastatic melanoma cells possibly involved in determining the level of aggressiveness of human melanoma. This suggests that the assessment of phagocytic activity may be exploited as a new tool to evaluate the malignancy of human melanoma. Moreover, our data suggest that gene therapy or drug treatments aimed at inhibiting actin assembly to the phagosomal membranes may be proposed as a new strategy for the control of tumor aggressiveness.

Malignant fibrous histiocytoma of the skin with marked inflammatory infiltrate: a sarcoma mimicking malignant lymphoma

Three cases of malignant fibrous histiocytoma of the skin with a marked inflammatory infiltrate in the stroma are reported. The inflammatory infiltrate, composed mainly of T-lymphocytes, obscured the nature of the neoplasms, and immunohistochemical studies were required to establish the diagnosis. Two tumors arose in the sun-damaged skin of the face, and one tumor arose in the chest wall. One patient developed a local recurrence with histopathologic findings similar to those observed in the original lesion, including the inflammatory infiltrate. Possible differential diagnoses include large cell lymphoma, inflammatory pseudotumor, inflammatory leiomyosarcoma, and spindle cell squamous cell carcinoma. The presumed rarity of inflammatory changes in malignant fibrous histiocytoma of the skin is supported by the absence of reported cases.

Ileal carcinoid tumor complicating carcinoid heart disease and secondary retroperitoneal fibrosis

A 70-year-old man with metastatic liver tumors showed carcinoid syndrome with clinical symptoms of facial flushing, palpitation, dyspnea, and an itching sensation. Regurgitation of the tricuspid and aortic valves was observed by echocardiography. An elevated serum level of serotonin and a high urine excretion of serotonin metabolites were confirmed. Autopsy confirmed a serotonin-immunoreactive 1 cm ileal carcinoid tumor with metastasis to the liver, bone and peritoneum. The tumor cells were argyrophilic but not argentaffin, and showed erythrophagocytosis in the primary lesion. All the four heart valves and bilateral atrial endocardium showed fibromyxoid thickening, indicating the association of carcinoid heart disease. Desmoplastic reaction with deposition of sulfated acid mucopolysaccharides was also observed in the retroperitoneal space (secondary retroperitoneal fibrosis). Stenosis of the bilateral ureters and inferior mesenteric artery provoked hydronephrosis and lethal ischemic necrosis of the left-sided colon, respectively. Rarity of functioning ileal carcinoid tumor and pathogenesis of systemic fibroplasia are discussed.

Pigmented atypical fibroxanthoma

AIM

The purpose of this report is to call attention to a pigmented variant of atypical fibroxanthoma that resembles malignant melanoma, both clinically and histopathologically.

METHODS AND RESULTS

Thirty-eight cases of atypical fibroxanthoma were examined for the presence of pigmented areas. Four such cases were found. Neoplastic cells showed erythrophagocytosis and accumulation of haemosiderin pigment in the cytoplasm. In three cases, immunohistochemical studies using a battery of antibodies were performed. Neoplastic cells were strongly positive for vimentin and weakly positive for CD68, whereas they were negative for melanocytic markers, including S100 protein, HMB45, and the monoclonal antibody NK1-C3 to melanoma-associated antigen.

CONCLUSIONS

Pigmented atypical fibroxanthoma represents a poorly recognized variant of the neoplasm that may be easily misinterpreted as malignant melanoma. To the best of our knowledge, this is the first report of erythrophagocytosis in atypical fibroxanthoma.

Hemophagocytic syndrome associated with hematological neoplasias

Hemophagocytic syndrome (HPS) is a reactive process that complicates several diseases including hematological neoplasias (HN). It has been suggested that HPS may be a negative prognosis factor for neoplastic diseases. In this retrospective analysis, 13 cases with HPS associated to HN were compared with two age, sex, diagnosis, disease stage and treatment matched controls in order to determine the impact of this syndrome on the survival. Cases with HPS were adult patients with a male:female ratio of 1:1 and their clinical picture was characterized by fever, lymphadenopathy, hepatosplenomegaly, and pancytopenia. Median survival since HN diagnosis was 7 and 48 months for the HPS and control groups, respectively (P = 0.0001). In ten patients who died, median survival after HPS presentation was 1 month. These results suggest that the presence of HPS is a negative prognosis factor in patients with HN. Due to its high mortality rate, an individualized, early, and intensive chemotherapeutic regimen may be required for HN complicated with this syndrome.

A case of histiocytic medullary reticulosis complicated with x-ray-irradiated oral cancer

We report the case of a patient in whom oral squamous cell carcinoma and a fatal reactive form of histiocytosis were simultaneously manifested. Our conclusions indicate that such a hematophagocytic syndrome may occur in the setting of oral squamous cell carcinoma as previously described in other malignancies.

Photosensitized destruction of human bladder carcinoma cells treated with chlorin e6-conjugated microspheres

A photosensitizer conjugate, chlorin e6 (Ce6) covalently bound to 1-micron-diameter polystyrene microspheres, has been investigated in the photodynamic destruction of MGH-U1 human bladder carcinoma cells in vitro. The microspheres were taken up avidly by the carcinoma cells; confocal laser scanning fluorescence microscopy showed them to be localized in the cytoplasm, apparently within lysosomes, visualized by labeling with acridine orange. In contrast, fluorescence of unconjugated Ce6 was present within most cellular membranes. Use of Ce6-microsphere conjugates led to a 20-fold-higher mean intracellular concentration, compared with unconjugated Ce6. Cells incubated in the presence of Ce6-microsphere conjugates (0.43 microM equivalent) and subsequently irradiated at 659 nm with a dye laser pumped by an argon-ion laser showed dose-dependent phototoxicity, leading to total inhibition of colony formation at a radiant exposure of 5J/cm2; in contrast, cells incubated with either unconjugated Ce6 (0.43 microM) or unconjugated microspheres before laser irradiation were unaffected. Cells pretreated with Ce6-microsphere conjugates and irradiated in the presence of 90% 2H2O showed significantly increased phototoxicity, an effect consistent with an important role for excited-state singlet oxygen in the mechanism of injury. In solution, however, photosensitized generation of singlet oxygen with Ce6-microsphere conjugates was 9 times less efficient than with unconjugated Ce6. The markedly greater phototoxicity of Ce6-microsphere conjugates compared to unconjugated Ce6 was therefore a consequence of the high intracellular Ce6 concentration attained by phagocytosis of the conjugates and their particular sites of intracellular localization. Thus, these conjugates are an efficient system for the delivery of photosensitizing drugs to carcinoma cells.

Hemophagocytosis by small cell lung carcinoma

A 60-year-old woman with disseminated small cell carcinoma of the lung and hemophagocytosis by the metastatic cells in the bone marrow is presented. It is the first clinicopathologic report on phagocytosis of erythrocytes by lung tumor cells in concordance with a recently described evidence of a macrophage origin of small cell carcinoma of the lung.

Histiocytic cytophagic panniculitis

Nineteen cases of histiocytic cytophagic panniculitis from our institution and from the literature were reviewed for their clinical and histopathologic features. All patients had cutaneous involvement consisting of cutaneous nodules and plaques that occasionally were ecchymotic and ulcerated and were characterized by infiltration of the subcutaneous tissue by large, benign histiocytes with cytophagic features. Thirteen of the patients had died (nine with hemorrhagic complications), four patients had a benign course with remission of the disease, and two patients responded to aggressive polychemotherapy. Immunohistochemical studies of paraffin-embedded tissue, performed in five cases, revealed a large number of infiltrating T cells in the subcutaneous inflammatory lesions.

Erythrophagocytosis in the skin: case report

A 68-year-old male with a myelodysplastic syndrome developed a bulla on his right thigh. A skin biopsy revealed a subepidermal cleavage containing fibrin and a mononuclear cell infiltrate exhibiting prominent erythrophagocytosis. Erythrophagocytosis by mononuclear cells was present, to a lesser extent, throughout the dermis and in the subcutis. Immunoperoxidase studies with anti-lysozyme and anti-alpha-l-chymotrypsin confirmed the histiocytic nature of the phagocytic cells. Only a few prior reports of cutaneous erythrophagocytosis exist in the literature. In contrast to the generally grave clinical manifestations of the patients described in previous publications documenting erythrophagocytosis, this patient lacked a concomitant hematologic deterioration or serious systemic illness.

The nature of host tissue destruction in tumor invasion. An experimental investigation on carcinoma and sarcoma xenotransplants

The nature of host tissue destruction in tumor invasion was investigated in experimentally induced carcinomas and sarcomas, xenografted into skeletal muscle. By means of light and electron microscopy it was shown that in both carcinomas and sarcomas the confrontation of host tissue with the invading tumor cells does not result in immediate destruction of host tissue but in a transitory state of coexistence which gradually proceeds to progressive host tissue atrophy. This process of progressive atrophy, which finally results in the total disappearance of the invaded host tissue, is considered to be caused mainly by the increasing pressure and competitive withdrawal of oxygen and nutrients by the invading and proliferating tumor cells. Morphological changes suggesting an active enzymatic breakdown of host tissue cells by tumor cells were not observed during any stage of tumor invasion.

Hypogammaglobulinemia and hemophagocytic syndrome associated with lymphoproliferative disorders

Four patients with lymphohistiocytic disorders had or subsequently experienced severe hypogammaglobulinemia and pancytopenia due to hemophagocytosis. The percentages of B- and T-lymphocytes and the ratios of helper (OKT4) cells to suppressor (OKT8) cells in the peripheral blood were variably altered. Mitogenic response to pokeweed mitogen and phytohemagglutinin was depressed but could be restored to near normal by the in vitro addition of indomethacin or interleukin-2. The half-life of intravenously administered immunoglobulin was markedly shortened. The data indicate that hyperactive monocytes/histiocytes are capable of simultaneously ingesting apparently normal blood cells and immunoglobulin, leading to pancytopenia and hypogammaglobulinemia. The monocytes with suppressor activity (which could be abrogated with indomethacin or interleukin-2) appeared to additionally contribute to the hypogammaglobulinemia, possibly by interfering with the terminal differentiation of the B-lymphocytes. Hemophagocytosis occurs frequently in histiocytic and occasionally in lymphoproliferative disorders or viral diseases. More frequent and serial determination of serum immunoglobulin levels in such situations may lead to the discovery of additional cases.

Mechanisms of tumor invasion: evidence from in vivo observations

The major mechanisms of tumor invasion in vivo are discussed in the present review. A special emphasis is placed on tumor dedifferentiation which has proved to be of paramount importance for the invasion process. Based on in vivo observations obtained from various human and animal tumors a concept for the mechanism of tumor invasion is proposed which mainly comprises the following basic events: the first and essential step in tumor invasion is the tumor dedifferentiation and dissociation at the invasion front. This apparently temporary and reversible process mobilizes the tumor cells out of the main tumor bulk and enables them to invade the host tissue by active locomotion. This mechanism is essentially supported by an interstitial edema in the host tissue adjacent to the tumor periphery, which causes an 'opening and widening' of the host intercellular spaces. Enzymatic changes in the micromilieu of the extracellular matrix may contribute to this process. The tumor cell proliferation completes the invasion process in so far, as the invading tumor cells are still able to proliferate, leading this way to expanding tumor cell nests in the host tissue which have the potency to redifferentiate. The expansive growth of these tumor cell nests results in a progressive atrophy of the host tissue, mainly caused by an increasing compression and a competitive withdrawal of oxygen and other nutrients by the tumor cells. The overall picture of tumor invasion can therefore be considered as a repetitive cycle of active tumor cell locomotion followed by focal tumor cell proliferation in the host tissue.

Reactive hemophagocytic syndrome

Two cases of reactive hemophagocytic syndrome (RHS) are reported, and the clinical and pathological features are compared with other histiocytic proliferative disorders, including familial hemophagocytic lymphohistiocytosis (FHL) and malignant histiocytosis. RHS can be associated with a variety of infections, including viral, bacterial, fungal, and parasitic. RHS may also be familial as exemplified by our 2 cases in siblings. The isolation of an effective agent appears to be the only criterion by which a diagnosis of RHS can be made.

Erythrophagocytic acute lymphocytic leukemia with B-cell markers and with a 20q- chromosome abnormality

An erythrophagocytic neoplastic infiltration of the bone marrow which resembled malignant histiocytosis was found in an elderly man who, when initially examined, had fever and cytopenias. Results of cytochemical and immunologic studies were consistent with an acute lymphocytic leukemia in which the lymphoblasts showed the simultaneous expression of lymphoid stem cell and B-cell markers. Chromosome analysis revealed an abnormal clone with a deletion of part of the long arm of chromosome 20. This case illustrates (1) the occurrence of striking erythrophagocytosis by lymphoblasts at the time of initial presentation of a patient with acute lymphocytic leukemia, (2) the fact that abnormalities of chromosome 20 can occur in patients with acute lymphocytic leukemia, and (3) the capability of lymphoid malignant lesions to show the simultaneous expression of antigens that are characteristic of different stages of lymphoid differentiation.

True histiocytic lymphoma. A report of four cases

Clinical, morphologic, cytochemical, immunologic, and ultrastructural features of four cases of true histiocytic lymphoma are described. The neoplastic cells were large, ranging from 20 to 45 mu in diameter with round, folded, or convoluted nuclei, and abundant eosinophilic cytoplasm. They exhibited diffuse nonspecific esterase activity. Diffuse acid phosphatase activity was present in two cases so tested. Muramidase activity was present in half of the cases. Finely granular PAS-positive material was seen in the cytoplasm. Methyl green-pyronin positivity was variable. An occasional neoplastic cell showed erythropagocytosis in one case. Malignant cells either contained no cytoplasmic immunoglobulins (three cases) or had immunoglobulins of multiple classes (one case). Surface markers were studied in two cases; they were absent in one case, and were of multiple classes in another case. Ultrastructurally the neoplastic cells had lysosomal granules in three cases so examined, and phagolysosomes, phagocytized material and residual bodies in one of three cases so studied. Patients ranged in age from 28 to 60 years. Two patients had extralymphatic tumors. Survival of more than 5 years was seen in one patient.

Malignant lymphoma and erythrophagocytosis simulating malignant histiocytosis

Six patients with malignant lymphoma are described, in whom a syndrome that mimicked malignant histiocytosis clinically and pathologically developed as a terminal event. The clinical course was characterized by hepatosplenomegaly, fever, and a rapid fall in all hematologic counts. Survival from onset of this syndrome was less than six weeks. Pathologically, activation of benign histiocytes with marked erythrophagocytosis was seen throughout the reticuloendothelial system. Disseminated lymphoma was also evident but was grossly and microscopically segregated from the erythrophagocytic process. Immunologic and cytochemical studies in two cases indicated the lymphomas to be of peripheral T cell origin, whereas the phagocytic cells had markers characteristic of histiocytes. A likely mechanism for this syndrome is the production of lymphokines (macrophage-activating factors) by neoplastic T lymphocytes.

Cell necrosis and endocytosis (apoptosis) in an embryonal rhabdomyosarcoma of the orbit

An orbital embryonal rhabdomyosarcoma, which was excised from the orbit of an 8-year-old girl, was studied by light microscopy and transmission electron microscopy. Cells within the tumour demonstrated by light microscopy diffuse areas of necrosis and isolated single-cell necrosis. There were many viable tumour cells with intracytoplasmic vacuolar structures which contained basophilic granules. Ultrastructural studies showed close apposition between well-preserved tumour rhabdomyoblasts and degenerate or necrotic tumour cells: degenerate cells and condensed cell fragments were observed within the cytoplasm of the well-preserved tumour cells. Some cells which showed degenerative changes had features which suggested that they had ingested more than one degenerate cell on separate occasions. This phenomenon may be regarded as a variant of selective individual cell death, currently referred to as apoptosis, which has not been previously reported in a case of embryonal rhabdomyosarcoma. The patient remains free of tumour recurrence four years following treatment with combined radiotherapy and chemotherapy.

Renal sarcomas of childhood. A clinicopathologic and ultrastructural study

Of 230 consecutive primary renal tumors of childhood collected over a 26-year period, 19 (8.2%) were sarcomas. The histologic criteria devised by the National Wilms' Tumor Study for diagnosis of "sarcomatous variants" of Wilms' tumor could be applied to all but three cases, namely, a rhabdomyosarcoma, a spindle-celled tumor, possibly leiomyosarcoma, and an unclassified primitive tumor. The most prevalent subtype was the bone-metastasizing, "clear cell" sarcoma. Correlative histologic and ultrastructural study supports the concept of subsets of tumors within the category now called "sarcomatous Wilms' tumor." Although this designation has the practical value of alerting the oncologist to the need for aggressive therapy, an origin in nephrogenic mesoderm cannot be cogently proposed for all of these tumors. This study also shows that the histologic features of the different subtypes of renal sarcomas may overlap. Hence, electron microscopy is indispensable for appropriate subclassification of these tumors.

A proposed model of cancer as the inappropriate expression of non-body introns

An a posteriori proposal is made that cancer represents an alien non-body phenotype erupting from "silent" gene groups within actively coding regions of a normal cell's genome. Relevant empirical data is garnered from the literature and twelve premises are derived from the data. On the basis of these premises it is hypothesized that the malignant neoplastic phenotype results from interference with non-histone chromosomal proteins causing retention and expression in a body cell of non-body introns. These are asserted to be the same introns which, as exons in a trophoblast cell, direct the normal development of the fetal placenta. Development of a malignant tumor is presented as a pathological recapitulation of the development of a normal placenta. Unrestrained tumor growth is attributed to the inability of endogenous body chalones to suppress the non-body gene groups coding for neoplastic mitosis, while invasion and metastasis result from failure of the non-body genes which code for implantation and mitosis to switch off at the proper time. The hypothesis asserts that all carcinogenic agents alter phosphorylation of non-histone chromosomal proteins, that cancer and normal trophoblast cells are genetically programmed to travel through the body's vascular system to effect immunosuppression in lymphoid tissues, that malignant neoplastic tissue will regress when exposed to trophoblast-based chalones, and that mammals immunized against trophoblast-based antigen will be resistant to the development of malignant tumors.

Infantile sarcoma with intracytoplasmic filamentous inclusions: distinctive tumor of possible histiocytic origin

This report describes four malignant tumors originating in infants, (one present at birth), for which a common origin is proposed. The common nature of these tumors was suggested by a remarkable similarity of histologic and ultrastructural features, including the presence of intracellular filamentous aggregates, as well as a shared aggressive clinical course consistent with sarcomatous origin. Two of these neoplasms arose within the kidney and were classified as "rhabdoid" sarcomas, according to the NWTS nomenclature. However, cells from these neoplasms could not be identified as muscular in origin. In culture, these cells demonstrated adherence to substratum, ability to phagocytose particles, and cell surface complement receptors. In addition, the renal tumors contained definite tumor cells positive for muramidase; the liver primary tumor contained only a limited number of such cells, which could not be interpreted as neoplastic. These findings suggest that among the "round-cell sarcomas" of infants and young children, a distinct, highly malignant form may be identified on clinical and morphologic grounds. The possibility that the tumor cells may be linked to the mononuclear phagocyte system was suggested, but not proved, and deserves further study.

Phagocytic capacity of invasive malignant cells in three-dimensional culture

To study the phagocytic capacity of invasive malignant cells, fragments of the hypoblast from chick blastoderms were confronted in three-dimensional culture with spheroidal aggregates of 1) malignant virally transformed C3H mouse cells (MO4), 2) HeLa cells and 3) embryonic chick heart cells. The hypoblast was used because it contains yolk, a marker that is absent in the confronting cells and that can be identified histologically and ultrastructurally. The confronting tissues were incubated on semi-solid agar-agar medium or in fluid medium on a gyrotory shaker. Cultures were followed for 1 to 7 days by stereomicroscopy, cinemicrophotography, light and transmission electron microscopy. Confrontation with MO4 cells of HeLa cells, known to be invasive in vitro, led to complete disappearance of the hypoblast. The fragments of hypoblast were well conserved when cultured alone or confronted with aggregates of chick heart cells. Degeneration of the hypoblast is shown at the area of contact with MO4-cell or HeLa-cell aggregates, in contrast to heart cells. Filopodia-like extensions from the MO4 or HeLa cells penetrate intercellularly, transcellularly and intracellularly into the hypoblast. Phagosomes, containing yolk and unidentified debris are observed in MO4 cells and in HeLa cells, but not in heart cells. These observations demonstrate the phagocytic capacity of invasive malignant cells.

Erythrophagocytosis by undifferentiated lung carcinoma cells

A case is reported of undifferentiated metastatic lung carcinoma in which both a supraclavicular lymph node and bone marrow were infiltrated by anaplastic tumor cells which had engulfed erythrocytes and nucleated elements. The possibility of a histiocytic origin for the phagocytizing neoplastic cells was excluded by ultrastructural, cytochemical, and immunoperoxidase studies. This investigation shows that epithelial tumor cells may, at times develop phagocytizing activity, a phenomenon observed in certain experimentally induced tumors. The mechanism responsible for this phenomenon is not clear.

Osteoclastoma-like giant cell tumor of the liver

A rare, osteoclastoma-like giant cell tumor developed in the macronodular cirrhotic liver of an 87-year-old man. Histogenetically, the tumor was considered to be of reticuloendothelial cell (Kupffer cell) origin. A brief review of the literature concerning the extraosseous giant cell tumors is included in this report.

Polymorph phagocytosis by cancer cells in an endometrial adenoacanthoma

A case of endometrial adenoacanthoma is reported in which two histologically distinct populations of cells were identified in the primary tumor. The two cell types differed in that one had phagocytosed large numbers of polymorphonuclear leucocytes. A subsequent skin metastasis was composed entirely of cells capable of phagocytosing polymorphs. The ability of cancer cells to phagocytose other cellular elements may provide a histologic marker for the presence of surface membrane abnormalities in these cells. The possibility that this may be associated with metastasis is considered.

Spheroidal filamentous inclusion body cells in von Recklinghausen's disease

Cells with spheroidal filamentous cytoplasmic bodies, distinctive by both light and electron microscopy, were found in a neoplasm arising from the sciatic nerve of a patient with von Recklinghausen's disease. Tissue fixed with formalin and embedded in paraffin for three years was deparaffinized, reprocessed, and examined with the electron microscope. The morphology of the spheroidal body cells, the close resemblance to erythrophagocytosis, and the possible significance of the changes are discussed.