Macrophage infiltration and tumor progression

Identification of NUTF2 as a Candidate Diagnostic and Prognostic Biomarker Associated with Immune Infiltration in Head and Neck Squamous Cell Carcinoma

Background

Head and neck squamous cell carcinoma (HNSC) is one of the most common tumors worldwide. Nuclear transport factor 2 (NUTF2) plays a key role in cell death and immune processes. However, few reports have studied correlations between NUTF2 gene expression and the occurrence and development of HNSC.

Methods

The expression of NUTF2 was analyzed using publicly available databases, including the Cancer Genome Atlas and Human Protein Atlas and Gene Expression Omnibus (GEO) database, which was validated by RT-PCR. We evaluated the functions of NUTF2 with Kaplan–Meier curve, logistic regression were used to study the relationship between clinicopathological features and the expression of NUTF2. Cox regression analyses were used to identify the effects of NUTF2 expression on survival. Gene Ontology and Gene Set Enrichment Analysis were used to explore relevant biological pathways. The relationship between NUTF2 and tumor-infiltrating immune cells was investigated with on-line bioinformatic tools.

Results

NUTF2 was significantly upregulated in HNSC lesions and is associated with tumor size (P < 0.01). Increased expression of NUTF2 was linked to shorter overall and progress-free survival in HNSC. Cox regression analyses revealed that NUTF2 is an independent prognostic factor in HNSC. GSEA analysis demonstrated that NUTF2 negatively regulates several immune pathways. NUTF2 was correlated with the infiltrating levels of B cells and CD8+ T cells and was negatively correlated with diverse immune marker sets in HNSC.

Conclusion

NUTF2 is highly expressed in HNSC and correlates with poor prognosis. Correlation with immune functions suggests that NUTF2 may serve as a biomarker and therapeutic target for HNSC.

Targeting of MyD88 Homodimerization by Novel Synthetic Inhibitor TJ-M2010-5 in Preventing Colitis-Associated Colorectal Cancer

BACKGROUND

The TLR/MyD88 signaling pathway is an important driver of inflammation and cancer and is a possible target for antitumor therapy.

METHODS

We generated a MyD88 inhibitor (TJ-M2010-5), which was designed to bind to the TIR domain of MyD88 to interfere with its homodimerization, and the TLR/MyD88 signal pathway. We utilized a mouse model of azoxymethane/dextran sodium sulfate (AOM/DSS)-induced colitis-associated cancer (CAC) in combination with TJ-M2010-5 administration to investigate the anti-inflammation-related cancer effect of MyD88 inhibitor in vivo. Data were analyzed with one-way and repeated measures analysis of variance. Differences in survival between groups were compared using the log rank test. All statistical tests were two-sided.

RESULTS

TJ-M2010-5 inhibited MyD88 homodimerization in transfected HEK293 cells in a concentration-dependent manner and suppressed MyD88 signaling in LPS-responsive RAW 264.7 cells in vitro. In a 10-week CAC mouse model (n = 30 per group), TJ-M2010-5 treatment statistically significantly reduced AOM/DSS-induced colitis and completely prevented CAC development with less related body mass loss, resulted in 0% mortality of treated mice (compared with 53% mortality of control mice), decreased cell proliferation, and increased apoptosis in colon tissue. TJ-M2010-5 treatment also inhibited production of inflammatory cytokines and chemokines (TNF-α, IL-6,G-CSF, MIP-1β, TGF-β1, IL-11, IL-17A, IL-22 and IL-23) and infiltration of immune cells (macrophages, dendritic cells, neutropihls and CD(+)4 T cells) in colon tissues of mice.

CONCLUSIONS

Our findings suggest that TLR/MyD88 signaling may be a therapeutic target for CAC intervention and MyD88 inhibitors may be a promising therapeutic modality for treating patients with colitis or CAC.

Proteasomal inhibition sensitizes cervical cancer cells to mitomycin C-induced bystander effect: the role of tumor microenvironment

Inaccessibility of drugs to poorly vascularized strata of tumor is one of the limiting factors in cancer therapy. With the advent of bystander effect (BE), it is possible to perpetuate the cellular damage from drug-exposed cells to the unexposed ones. However, the role of infiltrating tumor-associated macrophages (TAMs), an integral part of the tumor microenvironment, in further intensifying BE remains obscure. In the present study, we evaluated the effect of mitomycin C (MMC), a chemotherapeutic drug, to induce BE in cervical carcinoma. By using cervical cancer cells and differentiated macrophages, we demonstrate that MMC induces the expression of FasL via upregulation of PPARγ in both cell types (effector cells) in vitro, but it failed to induce bystander killing in cervical cancer cells. This effect was primarily owing to the proteasomal degradation of death receptors in the cervical cancer cells. Pre-treatment of cervical cancer cells with MG132, a proteasomal inhibitor, facilitates MMC-mediated bystander killing in co-culture and condition medium transfer experiments. In NOD/SCID mice bearing xenografted HeLa tumors administered with the combination of MMC and MG132, tumor progression was significantly reduced in comparison with those treated with either agent alone. FasL expression was increased in TAMs, and the enhanced level of Fas was observed in these tumor sections, thereby causing increased apoptosis. These findings suggest that restoration of death receptor-mediated apoptotic pathway in tumor cells with concomitant activation of TAMs could effectively restrict tumor growth.

CD68 staining correlates with the size of residual mass but not with survival in classical Hodgkin lymphoma

The prognostic role of CD68 tumor-associated macrophages in classic Hodgkin lymphoma (cHL) remains controversial. We stained diagnostic biopsies and scored for CD68 using the PGM1 antibody among 98 consecutive patients with cHL from our center followed over a median of 45 months for progression-free survival (PFS). Among 79 patients we assessed interim and post-treatment positron emission tomography-computed tomography (PET-CT). Residual mass (RM) size was based on the greatest diameter of the largest mass seen in post-treatment imaging, and percent reduction was calculated by comparing RM size with its greatest pretreatment diameter. We found a significant association between CD68 positivity and absolute size of initial disease mass (p = 0.014) and residual mass at the end of therapy (p = 0.006) but no association was observed with interim PET-CT results or PFS. Our findings suggest that macrophages may influence tumor size by altering the microenvironment. This study does not support a prognostic role of CD68 positivity in predicting survival.

Collagen as a double-edged sword in tumor progression

It has been recognized that cancer is not merely a disease of tumor cells, but a disease of imbalance, in which stromal cells and tumor microenvironment play crucial roles. Extracellular matrix (ECM) as the most abundant component in tumor microenvironment can regulate tumor cell behaviors and tissue tension homeostasis. Collagen constitutes the scaffold of tumor microenvironment and affects tumor microenvironment such that it regulates ECM remodeling by collagen degradation and re-deposition, and promotes tumor infiltration, angiogenesis, invasion and migration. While collagen was traditionally regarded as a passive barrier to resist tumor cells, it is now evident that collagen is also actively involved in promoting tumor progression. Collagen changes in tumor microenvironment release biomechanical signals, which are sensed by both tumor cells and stromal cells, trigger a cascade of biological events. In this work, we discuss how collagen can be a double-edged sword in tumor progression, both inhibiting and promoting tumor progression at different stages of cancer development.

Expression of FOXP3, CD68, and CD20 at diagnosis in the microenvironment of classical Hodgkin lymphoma is predictive of outcome

PURPOSE

The immune microenvironment is key to the pathophysiology of classical Hodgkin lymphoma (CHL). Twenty percent of patients experience failure of their initial treatment, and others receive excessively toxic treatment. Prognostic scores and biomarkers have yet to influence outcomes significantly. Previous biomarker studies have been limited by the extent of tissue analyzed, statistical inconsistencies, and failure to validate findings. We aimed to overcome these limitations by validating recently identified microenvironment biomarkers (CD68, FOXP3, and CD20) in a new patient cohort with a greater extent of tissue and by using rigorous statistical methodology.

PATIENTS AND METHODS

Diagnostic tissue from 122 patients with CHL was microarrayed and stained, and positive cells were counted across 10 to 20 high-powered fields per patient by using an automated system. Two statistical analyses were performed: a categorical analysis with test/validation set-defined cut points and Kaplan-Meier estimated outcome measures of 5-year overall survival (OS), disease-specific survival (DSS), and freedom from first-line treatment failure (FFTF) and an independent multivariate analysis of absolute uncategorized counts.

RESULTS

Increased CD20 expression confers superior OS. Increased FOXP3 expression confers superior OS, and increased CD68 confers inferior FFTF and OS. FOXP3 varies independently of CD68 expression and retains significance when analyzed as a continuous variable in multivariate analysis. A simple score combining FOXP3 and CD68 discriminates three groups: FFTF 93%, 62%, and 47% (P < .001), DSS 93%, 82%, and 63% (P = .03), and OS 93%, 82%, and 59% (P = .002).

CONCLUSION

We have independently validated CD68, FOXP3, and CD20 as prognostic biomarkers in CHL, and we demonstrate, to the best of our knowledge for the first time, that combining FOXP3 and CD68 may further improve prognostic stratification.

Basal-like breast cancer cells induce phenotypic and genomic changes in macrophages

Basal-like breast cancer (BBC) is an aggressive subtype of breast cancer that has no biologically targeted therapy. The interactions of BBCs with stromal cells are important determinants of tumor biology, with inflammatory cells playing well-recognized roles in cancer progression. Despite the fact that macrophage-BBC communication is bidirectional, important questions remain about how BBCs affect adjacent immune cells. This study investigated monocyte-to-macrophage differentiation and polarization and gene expression in response to coculture with basal-like versus luminal breast cancer cells. Changes induced by coculture were compared with changes observed under classical differentiation and polarization conditions. Monocytes (THP-1 cells) exposed to BBC cells in coculture had altered gene expression with upregulation of both M1 and M2 macrophage markers. Two sets of M1 and M2 markers were selected from the PCR profiles and used for dual immunofluorescent staining of BBC versus luminal cocultured THP-1s, and cancer-adjacent, benign tissue sections from patients diagnosed with BBCs or luminal breast cancer, confirming the differential expression patterns. Relative to luminal breast cancers, BBCs also increased differentiation of monocytes to macrophages and stimulated macrophage migration. Consistent with these changes in cellular phenotype, a distinct pattern of cytokine secretion was evident in macrophage-BBC cocultures, including upregulation of NAP-2, osteoprotegerin, MIG, MCP-1, MCP-3, and interleukin (IL)-1β. Application of IL-1 receptor antagonist (IL-1RA) to cocultures attenuated BBC-induced macrophage migration. These data contribute to an understanding of the BBC-mediated activation of the stromal immune response, implicating specific cytokines that are differentially expressed in basal-like microenvironments and suggesting plausible targets for modulating immune responses to BBCs.

Breast cancer-induced bone remodeling, skeletal pain, and sprouting of sensory nerve fibers

Breast cancer metastasis to bone is frequently accompanied by pain. What remains unclear is why this pain tends to become more severe and difficult to control with disease progression. Here we test the hypothesis that with disease progression, sensory nerve fibers that innervate the breast cancer bearing bone undergo a pathological sprouting and reorganization, which in other nonmalignant pathologies has been shown to generate and maintain chronic pain. Injection of human breast cancer cells (MDA-MB-231-BO) into the femoral intramedullary space of female athymic nude mice induces sprouting of calcitonin gene-related peptide (CGRP(+)) sensory nerve fibers. Nearly all CGRP(+) nerve fibers that undergo sprouting also coexpress tropomyosin receptor kinase A (TrkA(+)) and growth-associated protein-43 (GAP43(+)). This ectopic sprouting occurs in periosteal sensory nerve fibers that are in close proximity to breast cancer cells, tumor-associated stromal cells, and remodeled cortical bone. Therapeutic treatment with an antibody that sequesters nerve growth factor (NGF), administered when the pain and bone remodeling were first observed, blocks this ectopic sprouting and attenuates cancer pain. The present data suggest that the breast cancer cells and tumor-associated stromal cells express and release NGF, which drives bone pain and the pathological reorganization of nearby CGRP(+)/TrkA(+)/GAP43(+) sensory nerve fibers.

PERSPECTIVE

Therapies that block breast cancer pain by reducing the tumor-induced pathological sprouting and reorganization of sensory nerve fibers may provide insight into the evolving mechanisms that drive breast cancer pain and lead to more effective therapies for attenuating this chronic pain state.

Pathological sprouting of adult nociceptors in chronic prostate cancer-induced bone pain

Pain frequently accompanies cancer. What remains unclear is why this pain frequently becomes more severe and difficult to control with disease progression. Here we test the hypothesis that with disease progression, sensory nerve fibers that innervate the tumor-bearing tissue undergo a pathological sprouting and reorganization, which in other nonmalignant pathologies has been shown to generate and maintain chronic pain. Injection of canine prostate cancer cells into mouse bone induces a remarkable sprouting of calcitonin gene-related peptide (CGRP(+)) and neurofilament 200 kDa (NF200(+)) sensory nerve fibers. Nearly all sensory nerve fibers that undergo sprouting also coexpress tropomyosin receptor kinase A (TrkA(+)). This ectopic sprouting occurs in sensory nerve fibers that are in close proximity to colonies of prostate cancer cells, tumor-associated stromal cells and newly formed woven bone, which together form sclerotic lesions that closely mirror the osteoblastic bone lesions induced by metastatic prostate tumors in humans. Preventive treatment with an antibody that sequesters nerve growth factor (NGF), administered when the pain and bone remodeling were first observed, blocks this ectopic sprouting and attenuates cancer pain. Interestingly, reverse transcription PCR analysis indicated that the prostate cancer cells themselves do not express detectable levels of mRNA coding for NGF. This suggests that the tumor-associated stromal cells express and release NGF, which drives the pathological reorganization of nearby TrkA(+) sensory nerve fibers. Therapies that prevent this reorganization of sensory nerve fibers may provide insight into the evolving mechanisms that drive cancer pain and lead to more effective control of this chronic pain state.

Blockade of nerve sprouting and neuroma formation markedly attenuates the development of late stage cancer pain

For many patients, pain is the first sign of cancer and, while pain can be present at any time, the frequency and intensity of pain tend to increase with advancing stages of the disease. Thus, between 75 and 90% of patients with metastatic or advanced-stage cancer will experience significant cancer-induced pain. One major unanswered question is why cancer pain increases and frequently becomes more difficult to fully control with disease progression. To gain insight into this question we used a mouse model of bone cancer pain to demonstrate that as tumor growth progresses within bone, tropomyosin receptor kinase A (TrkA)-expressing sensory and sympathetic nerve fibers undergo profuse sprouting and form neuroma-like structures. To address what is driving the pathological nerve reorganization we administered an antibody to nerve growth factor (anti-NGF). Early sustained administration of anti-NGF, whose cognate receptor is TrkA, blocks the pathological sprouting of sensory and sympathetic nerve fibers, the formation of neuroma-like structures, and inhibits the development of cancer pain. These results suggest that cancer cells and their associated stromal cells release nerve growth factor (NGF), which induces a pathological remodeling of sensory and sympathetic nerve fibers. This pathological remodeling of the peripheral nervous system then participates in driving cancer pain. Similar to therapies that target the cancer itself, the data presented here suggest that, the earlier therapies blocking this pathological nerve remodeling are initiated, the more effective the control of cancer pain.

Environmental control of invasiveness and metastatic dissemination of tumor cells: the role of tumor cell-host cell interactions

Recent advances in tumor biology led to the realization that, in order to understand the mechanisms involved in proliferation and invasion of tumor cells, an analysis of the complex interactions that tumor cells establish with host cells of tumor microenvironment is required. The bidirectional interactions between tumor cells and components of tumor microenvironment, in particular endothelial cells, cells of monocyte/macrophage lineage and fibroblasts/myofibroblasts, play a critical role in most of the events that characterize tumor progression and metastasis. Interactions between these "reactive" normal cells and the genetically altered tumor cells, by either cell-to-cell contacts or soluble mediators, control the most aspects of tumor formation and progression. This review addresses some of the experimental evidences documenting that tumor cells may influence host cells of their own microenvironment by triggering changes that facilitate their local as well as distant dissemination. Therefore, it focuses on macrophages and fibroblasts that, upon stimulation by tumor cells, change their state towards a tumor-promoting-like phenotype.

Tuftsin augments antitumor efficacy of liposomized etoposide against fibrosarcoma in Swiss albino mice

Anticancer drugs are generally plagued by toxic manifestations at doses necessary for control of various forms of cancer. Incorporating such drugs into liposomes not only reduces toxicity but also enhances the therapeutic index. Some antioxidants and potent immunomodulators have also been shown to impart significant antitumor activity presumably by nonspecific activation of the host immune system. In the present study, we evaluated augmentation of the antitumor activity of etoposide (ETP) by the immunomodulator tuftsin in Swiss albino mice with fibrosarcoma. The efficacies of the free form of ETP, liposomized ETP (Lip-ETP), and tuftsin-bearing liposomized ETP (Tuft-Lip-ETP) formulations were evaluated on the basis of tumor regression, effect on expression level of p53wt and p53mut, and survival of the treated animals. Tuft-Lip-ETP, when administered at a dosage of 10 mg/kg body weight/day for five days, significantly reduced tumor volume, delayed tumor growth, and also up-regulated the expression of p53wt. In contrast, although Lip-ETP delayed tumor growth, it did not decrease tumor size. The results of the present study suggest that tuftsin incorporation in drug-loaded liposomes is a promising treatment strategy for various forms of cancers, including fibrosarcoma.

Tuftsin augments antitumor efficacy of liposomized etoposide against fibrosarcoma in Swiss albino mice

Anticancer drugs are generally plagued by toxic manifestations at doses necessary for control of various forms of cancer. Incorporating such drugs into liposomes not only reduces toxicity but also enhances the therapeutic index. Some antioxidants and potent immunomodulators have also been shown to impart significant antitumor activity presumably by nonspecific activation of the host immune system. In the present study, we evaluated augmentation of the antitumor activity of etoposide (ETP) by the immunomodulator tuftsin in Swiss albino mice with fibrosarcoma. The efficacies of the free form of ETP, liposomized ETP (Lip-ETP), and tuftsin-bearing liposomized ETP (Tuft-Lip-ETP) formulations were evaluated on the basis of tumor regression, effect on expression level of p53wt and p53mut, and survival of the treated animals. Tuft-Lip-ETP, when administered at a dosage of 10 mg/kg body weight/day for five days, significantly reduced tumor volume, delayed tumor growth, and also up-regulated the expression of p53wt. In contrast, although Lip-ETP delayed tumor growth, it did not decrease tumor size. The results of the present study suggest that tuftsin incorporation in drug-loaded liposomes is a promising treatment strategy for various forms of cancers, including fibrosarcoma.

RANKL-dependent and RANKL-independent mechanisms of macrophage-osteoclast differentiation in breast cancer

The cellular and humoral mechanisms accounting for tumour osteolysis in metastatic breast cancer are uncertain. Osteoclasts, the specialised multinucleated cells responsible for tumour osteolysis, are derived from monocyte/macrophage precursors. Breast cancer-derived tumour-associated macrophages (TAMs) are capable of osteoclast differentiation but the cellular and humoral mechanisms controlling this activity are uncertain. In this study, TAMs were isolated from primary breast cancers and cultured in the presence and absence of cytokines/growth factors influencing osteoclastogenesis. Extensive TAM-osteoclast differentiation occurred only in the presence of RANKL and M-CSF; this process was inhibited by OPG and RANK:Fc, decoy receptors for RANKL. Breast cancer-derived fibroblasts and human bone stromal cells expressed mRNA for RANKL, OPG and TRAIL, and co-culture of these fibroblasts with human monocytes stimulated osteoclast formation by a RANKL-dependent mechanism. Osteoclast formation and lacunar resorption also occurred by a RANKL-independent mechanism when the conditioned medium from breast cancer cells, MDA-MB-231 and MCF-7, was added (with M-CSF) to monocyte cultures. Our findings indicate that TAMs in breast cancer are capable of osteoclast differentiation and that breast cancer-derived fibroblasts and breast cancer cells contribute to this process by producing soluble factors that influence osteoclast formation by RANKL-dependent and RANKL-independent mechanisms respectively.

Inhibition of lipoxygenase pathway in macrophages co-cultivated with tumor cells

Although there is a great deal of interest in the role played by tumor-associated macrophages in tumor progression, the knowledge of the biological mediators involved in the interplay between macrophages and tumor cells is still limited. In the present study, we investigated whether the lipoxygenase pathway in resident murine peritoneal macrophages is affected by contact with tumor cells of a different origin, e.g. murine B16 melanoma and L929 fibrosarcoma cells, and human Hs294T melanoma and HT1080 fibrosarcoma cells. Our experiments have been carried out by using macrophages co-cultivated with tumor cells at different ratios, in order to simulate the relative proportions between macrophages and tumor cells during the in vivo development of a tumor. Reverse phase HPLC analyses of the lipoxygenase products of resident peritoneal macrophages revealed a rather complex profile characterized by a high level of 12(S)-hydroxyeicosatetraenoic acid and 15(S)-hydroxyeicosatetraenoic acid followed by leukotriene B(4), 5(S)-hydroxyeicosatetraenoic acid, and lipoxins. Macrophages co-cultivated with tumor cells, both murine and human, showed a marked reduction of lipoxygenase products, mainly in the co-cultures where tumor cells prevailed over macrophages. The characteristic profile of macrophage lipoxygenase products was re-established after removal of tumor cells from the co-cultures. The inhibitory effect on lipoxygenase pathways exerted by tumor cells, was not seen when macrophages were co-cultivated with normal primary murine and human fibroblasts.

Cellular vehicles for cancer gene therapy: current status and future potential

Cancer is a difficult target for any therapeutic strategy; therefore, there is a continuous search for new therapeutic modalities, for application either alone or in combination. In this regard, gene-based therapy is a new approach that offers hope of improved control of tumors. Intensive research to apply gene therapy for cancer treatment has led to identification of the most important technical and theoretical barriers that need to be overcome for clinical success. One of the central unresolved challenges remains the issue of specific and efficient delivery of genes to target cells or tissues, emphasizing the importance of the gene carrier. Along with different viral and non-viral vector systems, mammalian cells have also been considered as vehicles for delivery of anti-cancer therapeutics. The cell-based delivery approach was introduced as the first attempt to apply gene therapy to cancer treatment, and in general, has followed most of the ups and downs of gene therapy applications, progressing alongside new knowledge gained in this field. As a result, significant progress has been made in some aspects of the cell-based approach, while the development of other essential issues is only just gaining speed. It appears that the initial phase of development of cell-based protocols - the achievement of efficient ex vivo cell loading with therapeutics - has largely been fulfilled. However, the desired efficacy of cell-based strategies in general has not yet been reached, and specificity of tumor homing needs to be improved considerably. There is hope that advances in related scientific fields will promote the utilization of cells as powerful and versatile vehicles for cancer gene therapy.

Cells as vehicles for cancer gene therapy: the missing link between targeted vectors and systemic delivery?

Systemic administration of currently manufactured viral stocks has not so far achieved sufficient circulating titers to allow therapeutic targeting of metastatic disease. This is due to low initial viral titers, immune inactivation, nonspecific adhesion, and loss of particles. One way to exploit the elegant molecular manipulations that have been made to increase vector targeting is to protect these vectors until they reach the local sites of tumor growth. Various cell types home preferentially to tumors and can be loaded with the constructs required to produce targeted vectors. Here we discuss the potential of using such cell carriers to chaperone precious vectors directly to the tumors. The vectors can incorporate mechanisms to achieve tumor site-inducible expression, along with tumor cell-specific expression of the therapeutic gene and/or replicating viral genomes that would be released at the tumor. In this way, the great advances that have so far been made with the engineering of vector tropisms might be genuinely exploited and converted into clinical benefit.

Activation of Kupffer cells inhibits tumor growth in a murine model system

Kupffer cells, a liver organ-specific macrophage, play an important role in preventing the development of malignant tumors. The mechanism responsible for their tumoricidal activities is not completely known. In our study, we established in vivo models involving a rat malignant cell line, rat Kupffer cells and tumor implantation in nude mice. A series of relevant in vitro experiments were also carried out to determine possible pathways. LPS-activated Kupffer cells produced significant amounts of NO, TNFalpha and IFNgamma. Malignant cells treated with either Kupffer cells or culture supernatant of the activated Kupffer cells had an increase in caspase-8 activity. Implanted tumors originated from malignant cells treated with either Kupffer cells or culture supernatant of the activated Kupffer cells grew much smaller than those from malignant cells without treatment or treated with control supernatants. The alteration of anti-apoptotic Bcl-2 was inversely associated with the change of pro-apoptotic caspase-8 and their levels in the tumor tissues matched the size of the tumors and treatments they received. It appeared that the above changes resulted in an increase in cellular DNA damage and apoptosis seen in malignant cells. Therefore, Kupffer cells execute their anti-tumor effect via increasing the production of NO, TNFalpha and IFNgamma and these cytotoxic molecules inhibit the growth of tumor by damaging cellular DNA and inducing apoptosis that was featured by downregulation of Bcl-2 but upregulation of caspase-8.

Human macrophage metalloelastase worsens the prognosis of pancreatic cancer

OBJECTIVE

To evaluate the role of human macrophage metalloelastase (HME) in pancreatic cancer.

SUMMARY BACKGROUND DATA

HME, a member of the human matrix metalloproteinase family, possesses elastolytic activity and is critical for the degradation of extracellular matrix proteins. Inasmuch as tumor invasion and metastasis formation require lysis of extracellular matrix, HME plays a critical role in both processes.

METHODS

HME expression was analyzed by Northern blot analysis, reverse transcriptase-polymerase chain reaction, Western blot analysis, and immunohistochemistry in 39 pancreatic cancer tissues and 13 normal controls. The molecular data were related to clinicopathologic parameters and patient survival.

RESULTS

In human pancreatic cancer, overexpression of HME mRNA was present in 25 of 39 pancreatic cancer tissues (64%) and in five pancreatic cancer cell lines. In contrast, low levels of HME mRNA expression were present in 13 normal pancreatic tissues samples. By Western blot analysis, high levels of HME were found in pancreatic cancer tissues and in the pancreatic cancer cell lines compared with the normal controls. Fifty-six percent of the cancer samples exhibited HME immunoreactivity in the cancer cells, and 63% in the stromal cells. Analysis of the survival data revealed that patients whose tumors exhibited HME mRNA overexpression lived significantly shorter compared with patients whose tumors did not overexpress HME. No relationship between HME expression and tumor stage, tumor grading, or presence of lymph node metastases was found.

CONCLUSIONS

These findings indicate that HME participates in pancreatic cancer progression and that its presence worsens the prognosis. These data suggest a benefit of its inhibition in the treatment of pancreatic cancer.

Human autologous monocytes and monocyte-derived macrophages in co-culture with carcinoma F-spheroids secrete IL-6 by a non-CD14-dependent pathway

The secretion of interleukin (IL)-1 beta, IL-6 and tumour necrosis factor (TNF)-alpha were compared when freshly isolated autologous monocytes or monocytederived macrophages (MDMs) were co-cultured in vitro with autologous fragment (F)-spheroids established from a series of head and neck squamous cell carcinoma (HNSCC) patients. F-spheroids were generated from the malignant tumour (M-spheroids) or from benign mucosa (B-spheroids) from which the tumour originated control. If monocytes maturated towards MDMs before co-culture, the IL-6 secretion declined dependent on the extent of the MDM maturation by both M- and B-spheroid stimulation. When MDMs maturated in continuous co-culture, a steady-state secretion of IL-6 continued for several days but diminished when the culture medium was changed every 24 h. No co-culture-induced IL-1 beta or TNF-alpha was determined. Both the cytokine secretion and the mRNA gene expression revealed a different monocyte/MDM activation when co-culture and lipopolysaccharide (LPS)-stimulation were compared. Addition of anti-CD14 (10 microg/ml) decreased monocyte LPS-stimulated, but increased monocyte co-culture stimulated IL-6 secretion. In conclusion, M- and B-spheroids similarly stimulated monocytes and to a lesser extent MDMs. MDMs that maturated with F-spheroids present, retained responsiveness at the monocyte level. Co-culture-induced monocyte stimulation, as measured by IL-6 secretion, was not dependent on activation via the CD14 molecule.

The macrophage - a novel system to deliver gene therapy to pathological hypoxia

The use of activated macrophages in the treatment of cancer has been largely ineffectual. By 'arming' these cells with the ability to express a therapeutic gene we demonstrate significant advances in the efficacy of this approach. We have used a hypoxia-regulated adenoviral vector to transduce human macrophages with either a reporter or a therapeutic gene encoding human cytochrome P4502B6 (CYP2B6). Infiltration of transduced macrophages into a tumour spheroid results in induction of gene expression. We demonstrate significant tumour cell killing only in the presence of cyclophosphamide via activation by P4502B6 and show that this can be further targeted to tumours through hypoxia regulated gene expression. Gene Therapy (2000) 7, 255-262.

Macrophages, estrogen and the microenvironment of breast cancer

Estrogen is a major mitogenic stimulus to established breast cancer. Estrogen sources include ovarian, extraglandular sites and breast tissue. Which source primarily maintains benign and breast cancer tissue estrogen concentrations remains unclear. While macrophages may comprise up to 50% of the mass of breast carcinomas, previous studies neglected to study them as possible sources of estrogen. We present evidence that breast macrophages constitute an in situ source of estradiol and that the amount produced is sufficient to mediate cellular proliferation. We utilized immunohistochemistry and RT-PCR to study cell-specific aromatase expression in (i) 29 breast biopsies, (ii) human monocytes/macrophages and (iii) a myeloid cell line (THP-1) capable of differentiating into macrophages. Use of a breast cancer cell line (MCF-7) provided biologic confirmation of the role of aromatization in cell proliferation. We demonstrated considerable amounts of immunoreactive-aromatase (irARO) in breast tissue macrophages and a positive correlation between the proportion of irARO present in macrophages and lesion severity. Using in vitro techniques, we demonstrated that monocytes and THP-1 cells require differentiation into macrophages to produce aromatase in amounts approaching placental levels. The amount of estrogen produced by THP-1 cells stimulated MCF-7 cells to proliferate, an effect blocked by aromatase inhibitors. Estrogen production by macrophages in breast tissue appears sufficient to stimulate the proliferation of adjacent epithelial cells and to autoregulate cytokine production. These findings represent a new dimension of cellular regulation in breast tissue with major biologic implications, amenable to pharmacological manipulation.

Macrophage-derived metalloelastase is responsible for the generation of angiostatin in Lewis lung carcinoma

To determine the mechanism responsible for the in vivo production of angiostatin that inhibits growth and metastasis in Lewis lung carcinoma (3LL), we implanted 3LL variant cells into the subcutis of syngeneic C57BL/6 mice. The tumors were infiltrated by macrophages and expressed high levels of steady-state mRNA for metalloelastase (MME). Successive passages (more than three) of cultures established from the tumors resulted in complete depletion of macrophages; steady-state MME mRNA, elastinolytic activity, and production of angiostatin (in the presence of plasminogen) were correspondingly reduced. Coculture of macrophages with either 3LL cells or their conditioned media containing granulocyte-macrophage colony-stimulating factor resulted in secretion of MME and production of angiostatin by the macrophages, suggesting that angiostatin is produced by tumor-infiltrating macrophages whose MME expression is stimulated by tumor cell-derived granulocyte-macrophage colony-stimulating factor.

Clinicopathologic analysis of macrophage infiltrates in breast carcinoma

We compared macrophage density, assessed by enumeration of peritumoral mononuclear cell immunoreactivity for HAM 56, to clinicopathologic features and to immunostaining for two "invasion-associated" proteases (Cathepsin D and Urokinase plasminogen activator) in 80 breast carcinomas. Diffuse (2+) infiltrates of HAM 56- positive mononuclear cells were present in 27 cases (34%) and 43 (54%) exhibited focal (1+) infiltrates. Presence of 2+ macrophage infiltrates correlated significantly with poor differentiation. None of the seven well-differentiated cases exhibited 2+ infiltrates, whereas 9/43 (21%) moderately differentiated and 18/30 (60%) poorly differentiated tumors were diffusely infiltrated (p = .001). Wide-spread macrophage infiltrates were also more frequent in cases with advanced stage (23% of node negative vs 40% of node positive cases, p = NS). Forty-four percent of the cases with diffuse macrophage infiltrates were cathepsin D positive (i.e. in host derived cells) vs only 18% with focal macrophage infiltrates (p = .002). A similar relationship was observed between staining for HAM 56 and urokinase-type plasminogen activator (p = .02). Disease recurrences (50 months median follow-up) were more frequent in patients with 2+ (17/27, 63%) as opposed to 0+ (1/10, 10%) macrophage infiltrates (p = .01). We conclude that the density of stromal macrophage infiltrates is associated with clinical aggressiveness in breast carcinomas. Further, this relationship may reflect contribution of host derived macrophages to invasion and metastasis through elaboration of proteases which putatively mediate degradation and remodeling of extracellular matrix.

The mechanism of the inhibitory effect of polyamines on the induction of nitric oxide synthase: role of aldehyde metabolites

1. We have recently found that in the presence, but not in the absence, of foetal calf serum, spermine inhibits the production of nitric oxide (NO) in cultured J774.2 macrophages stimulated with bacterial endotoxin (lipopolysaccharide; LPS) or with gamma-interferon (IFN), showing that polyamines may act as suppressants of NO-mediated immune functions. Here, we have studied the mechanisms and the specificity of this inhibitory action. 2. Other polyamines, as well as spermine, inhibit the formation of NO in cultured J774.2 macrophages, with the order of potency being spermine > spermidine >> putrescine = cadaverine. This inhibition of NO formation is not due to any cytotoxic effect of these agents for they neither reduced mitochondrial respiration nor increased the release of lactate dehydrogenase into the supernatant. 3. Spermine is not a direct inhibitor of the activity of iNOS in induced J774.2 cells as measured by its lack of effect on the conversion of L-arginine to L-citrulline in homogenates. Neither spermine, nor its metabolites, interfere with the production of nitrite from NO or act as scavengers of NO. Thus, spermine is an inhibitor of the induction of iNOS. 4. Spermine inhibits nitrite formation in the presence of foetal, newborn or adult bovine serum, but not rat or human serum. 5. The effect of sper mine on nitrite production can be prevented by isoniazid, hydrazine or hydroxylamine, inhibitors of spermine oxidase, as well as by phenylhydrazine, an aldehyde inhibitor. We have, therefore, tested the effects of spermine dialdehyde or malon dialdehyde on the induction of iNOS. Spermine dialdehyde (SDA, 10(-5) M) inhibits nitrite formation by IFN-activated J774.2 cells in the absence of serum when given as a pretreatment but not when given 6 h after stimulation. In contrast, malon dialdehyde was ineffective. Thus, aldehyde metabolites of spermine, such as SDA, account for the inhibitory effect of polyamines on the induction of NOS in vitro. 6. The inhibitory effect of polyamines on iNOS induction appears to be fairly specific to iNOS, for spermine does not inhibit LPS-induced production of prostaglandin F2 alpha or tumour necrosis factor.

Cathepsin D immunostaining in paraffin-embedded breast cancer cells and macrophages: correlation with cytosolic assay

High cathepsin D (cath-D) concentration in breast cancer cytosol is associated with increased risk of metastasis. To specify the relative contribution of the different cells types responsible for cath-D level in cytosol, we validated semiquantitative cath-D immunoperoxidase staining on formalin-fixed, paraffin-embedded sections, using the M1G8 monoclonal antibody, one of the two antibodies of the cytosolic assay. Using computer-aided image analysis, cath-D level in cancer cells was estimated by integrating both staining intensity in each cell and proportion of stained cells. We confirmed on 41 primary breast cancers a higher expression of cath-D in cancer cells compared with peritumoral mammary glands. Cancer cell staining was mostly in lysosomes and for some invasive ductal carcinomas in large vesicles corresponding to phagosomes. Lymphocytes and fibroblasts were not or were only weakly stained. Macrophages also were stained for cath-D, generally on the periphery of the tumor area. The cytosolic cath-D level was correlated with cath-D expression in cancer cells (r = .76; P = 1 x 10(-4)) rather than with the number of macrophages in the tumor (r = .29; P = .09), as determined by use of the specific anti-CD68 antibody. There was a significant increase in the tissue cath-D level in tumors containing large vesicles compared with tumors without large vesicles. This approach provides a means to separately estimate the prognostic significance of cath-D expression in cancer cells and macrophages when evaluating risk of metastasis.

Inhibition by spermine of the induction of nitric oxide synthase in J774.2 macrophages: requirement of a serum factor

Polyamines are endogenous regulators of various cell functions. Nitric oxide (NO) is a cytostatic and cytotoxic free radical which is produced by the inducible NO synthase (iNOS) in immuno-stimulated macrophages. We tested whether spermine modulates the induction of iNOS in J774.2 macrophages. Stimulation of macrophages by bacterial lipopolysaccharide (LPS) or gamma-interferon increased the accumulation of nitrite in the culture medium. Spermine (10(-6) - 10(-4) M) inhibited nitrite production without causing cytotoxicity. This inhibition of NO formation by spermine was significantly reduced when it was given 6 h after LPS. Spermine did not inhibit nitrite accumulation when foetal calf serum was omitted from the tissue culture medium. Thus, spermine is an inhibitor of the induction of iNOS, and its inhibitory activity requires the presence of a serum factor.

Synergic in vitro effects of interleukin-2 and tau-interferon on the migration of blood monocytes from control subjects and patients with lung cancer

BACKGROUND

Macrophages can play a major role against cancer by exerting their cytotoxic activity against tumor cells. The presence of macrophages in tumor stroma is related to the recruitment of circulating blood monocytes through the release of chemotactic factors by cancer cells. However, fewer blood monocytes from patients with cancer, such as lung cancer, migrate from in vivo and in vitro, compared with blood monocytes control subjects.

METHODS

Two cytokines, interleukin-2 (IL-2) and tau-interferon (tau-INF), proposed in the treatment of cancer, were tested for their ability to modulate the migratory response in modified Boyden chemotactic chambers of blood monocytes obtained from control subjects and patients with lung cancer in the presence of two chemotactic factors: N-formylmethionyl-leucyl-phenylalanine and complement fraction C5a (C5a).

RESULTS

Incubation with IL-2 and tau-INF resulted in a dose-dependent depression of the migration of blood monocytes from control subjects and patients with lung cancer. IL-2 depression was induced by IL-2 concentrations of 10(5) units/ml, and tau-IFN effects were measured for concentrations of 100 mu/ml. Furthermore, when low concentrations of IL-2 were tested in combination with low concentrations of tau-IFN, dose-dependent depression of blood monocyte migration occurred.

CONCLUSIONS

Dose-dependent depression of blood monocyte migration may modulate the inflammatory component of tumor stroma in patients with lung cancer treated with these cytokines. It may also explain, in part, the high incidence of infections in patients treated with IL-2.

Tumoricidal effect of human macrophage-colony-stimulating factor against human-ovarian-carcinoma-bearing athymic mice and its therapeutic effect when combined with cisplatin

The effect of human macrophage-colony-stimulating factor (hM-CSF) on tumoricidal activity was examined in athymic mice bearing the human ovarian cancer cell line, HRA, injected intraperitoneally (i.p.). The survival period and survival rate in the groups treated daily with hM-CSF were significantly longer (P < 0.01) than in the untreated group. The peritoneal cell smears showed that ascitic tumor cells were markedly decreased in the hM-CSF-treated groups, and macrophages phagocytosed tumor cells, indicating a contact-mediated direct cytolysis. The combined therapeutic effects of cisplatin and hM-CSF on HRA-bearing athymic mice were also studied. The mean survival period was 25.4, 47.2, 42.4 and 67.4 days, respectively, in the untreated group, and in the groups treated with cisplatin alone, with hM-CSF alone, and with combined cisplatin and hM-CSF. The survival period and rate were significantly longer (P < 0.01) in the group treated with combined cisplatin and hM-CSF than in those treated with cisplatin or hM-CSF alone, indicating the therapeutic effectiveness of the combined use. Moreover, hM-CSF is effective against granulocytopenia due to bone marrow suppression caused by cisplatin. Our data demonstrate that hM-CSF administered i.p. has a tumoricidal activity in athymic mice bearing human ovarian cancer i.p., which is mediated by activated macrophages, and that the combined administration of cisplatin and hM-CSF has a significant therapeutic effect.

Suppression of the delayed type hypersensitivity response by tumor facilitating factor of B16 melanoma. A tumor factor suppresses immune responses

BACKGROUND

Tumor facilitating factor is a cell surface glycoprotein produced by B16 melanoma that has been found to reduce the lethal inoculum for B16. Tumor facilitating factor induces macrophage spreading in vitro, reduces macrophage chemotaxis in vivo, and depresses lymphocyte mitogenesis in vitro.

OBJECTIVE

It is assumed that the immune modifying effects are responsible for tumor facilitation. As tumors may be poor immunogens or inducers of inflammation, studies were conducted to determine whether tumor facilitating factor alters the inflammatory cascade of cells found in infiltrates of delayed type hypersensitivity.

RESULTS

Freeze-thawed B16 cells, used as the source of TFF, caused a suppression of delayed type hypersensitivity measured as ear swelling in the mouse. When culture supernatant was substituted for freeze-thawed cells as a source of TFF and injected at different time points of the delayed type hypersensitivity response, the greater suppression was with tumor facilitating factor injections at 24 hours pre-elicitation only (82%), and 24 hours both presensitization and pre-elicitation (89%). Immunohistological staining demonstrated that tumor facilitating factor decreases ear thickness and cellular infiltrates, specifically Mac-1 staining cells, to a site of delayed hypersensitivity. Peritoneal cell analysis confirmed these findings.

CONCLUSION

These data are consistent with the hypothesis that tumor facilitating factor alters immune functions including macrophage and lymphocyte mobility and recruitment to a target site, thereby allowing for facilitation of tumor growth.

Inhibition of candidacidal activity of polymorphonuclear cells by alveolar macrophage-derived factor from lung cancer patients

Culture supernatants of alveolar macrophages (AM) from lung cancer patients are able to inhibit the candidacidal activity of polymorphonuclear cells (PMN) in vitro. This phenomenon is ascribed to a factor secreted in the culture medium by unstimulated AM from tumor-bearing patients, but not from normal subjects. The inhibitor does not apparently affect the phagocytic activity of PMN, but the superoxide release during phagocytosis is significantly impaired when cells are pretreated with supernatants containing the factor. The secretion of the inhibitor seems to be restricted to the pulmonary compartment of lung cancer patients, since culture supernatants of peripheral blood monocytes (PBM) from the same subjects are not capable of depressing the candidacidal activity of PMN. The AM-derived factor is not inactivated after exposure to heat (60 degrees C) and when supernatants are analyzed by HPLC, the inhibitory activity is recovered in the fractions corresponding to a low molecular weight (800 D). In conclusion, AM from lung cancer patients are able to produce a factor capable of inhibiting the antimicrobial activity of PMN. This could account, at least in part, for the enhanced susceptibility to local infections observed in lung cancer patients.

Mechanism for the recruitment of macrophages to cancer site. In vivo concentration gradient of monocyte chemotactic activity

BACKGROUND

Tumor stroma is characterized by the development of new blood vessels, an inflammatory cell infiltration, and a fibrotic reaction. The inflammatory component of tumor stroma plays an important role in the modulation of tumor expansion. In this respect, macrophages constitute a major part of the inflammatory cell infiltration and can exert cytotoxic activity against tumor cells. The accumulation of macrophages in the vicinity of the tumor suggests their recruitment from circulating blood monocytes through the local release of chemotactic factors for monocytes.

METHODS

To detect the existence of a concentration gradient of monocyte chemotactic activity (MCA) between the tumor vicinity and blood vessels, malignant pleural effusions defined by the local presence of cancer cells were evaluated for quantification of MCA.

RESULTS

Unlike nonmalignant pleural effusions, malignant pleural effusions were characterized by the presence of increased levels of MCA, and in lung adenocarcinoma (a cancer with high inflammatory cell infiltration), pleural levels of MCA were significantly greater than in small cell lung carcinoma (a cancer with low inflammatory cell reaction). An MCA concentration gradient between pleural fluid and plasma was present in malignant effusions because pleural MCA levels in all cancer types were significantly greater than MCA levels in the plasma of the same patients.

CONCLUSIONS

Thus, an increased local level of MCA is a feature of cancers with high inflammatory cell infiltration, and the presence of an in vivo concentration gradient of MCA suggests the direct role of this biologic activity in recruiting blood monocytes to the cancer site.

Metastasis induction by incomplete tumor resection. A new metastasis model using inoculation sarcomas in adult nude mice after long-term cultivation of sarcoma cells

In searching an animal model to study metastasis formation we used cultured cells of experimental rhabdomyosarcomas and their inoculation tumors in adult nude mice. Supplementing earlier observations (Katenkamp et al. 1987) we found that long-term cultured sarcoma cells induce tumors in adult nude mice which do not metastasize spontaneously but produce lung metastases after repeated incomplete tumor removal. Possible factors and mechanisms responsible for metastasis emergence are discussed. The metastasis model introduced may be apt to study cellular changes at cytogenetic and molecular biological level that occur during tumor progression and metastatic dissemination.

Therapy of disseminated melanoma by liposome-activated macrophages

The uncontrolled growth of metastases is a major cause of death from melanoma. Metastases arise from the nonrandom spread of specialized malignant cells that preexist within a primary neoplasm. Macrophages are activated to become tumoricidal by interaction with phospholipid vesicles (liposomes) containing immunomodulators recognize and destroy neoplastic cells in vitro and in vivo while leaving nonneoplastic cells unharmed. The mechanism(s) by which macrophages discriminate between tumorigenic and normal cells is independent of tumor cell characteristics such as immunogenicity, metastatic potential, and sensitivity to cytotoxic drugs. Moreover, macrophage destruction of tumor cells apparently is not associated with the development of tumor cell resistance. Intravenously administered liposomes are cleared from the circulation by phagocytic cells. The administration of such liposomes has been shown to activate macrophages in situ and to bring about eradication of cancer metastases in several experimental tumor systems and in dogs with spontaneous osteogenic sarcoma. Macrophage destruction of metastases in vivo is significant, provided that the tumor burden at the start of treatment is minimal. For this reason, we have been investigating various methods to achieve maximal cytoreduction in metastases by modalities such as chemotherapy or radiotherapy prior to systemic activation of macrophages. Macrophage-directed therapy has been studied in several human protocols, yielding important biological information about the safe use of liposome-encapsulated macrophage activators in cancer patients.

Monocyte chemotactic proteins from human tumor cells

The production of the monocyte chemoattractant MCP-1 suggests a common mechanism for the recruitment of monocytes/macrophages and provides an explanation for monocyte/macrophage infiltration frequently observed in solid tumors. The regulated production of MCP-1 by non-transformed cells further substantiates the suggestion that MCP-1 is an important inflammatory mediator and is involved in the recruitment of monocytes in a number of pathologic or physiologic conditions.

Macrophages and cancer

The uncontrolled growth of metastases resistant to conventional therapeutic modalities is a major cause of death from cancer. Data from our laboratory and others indicate that metastases arise from the nonrandom spread of specialized malignant cells that preexist within a primary neoplasm. These metastases can be clonal in their origin, and different metastases can originate from different progenitor cells. In addition, metastatic cells can exhibit an increased rate of spontaneous mutation compared with benign nonmetastatic cells. These data provide an explanation for the clinical observation that multiple metastases can exhibit different sensitivities to the same therapeutic modalities. These findings suggest that the successful therapy of disseminated metastases will have to circumvent the problems of neoplastic heterogeneity and the development of resistance. Appropriately activated macrophages can fulfill these demanding criteria. Macrophages can be activated to become tumoricidal by interaction with phospholipid vesicles (liposomes) containing immunomodulators. Tumoricidal macrophages can recognize and destroy neoplastic cells in vitro and in vivo, leaving nonneoplastic cells uninjured. Although the exact mechanism(s) by which macrophages discriminate between tumorigenic and normal cells is unknown, it is independent of tumor cell characteristics such as immunogenicity, metastatic potential, and sensitivity to cytotoxic drugs. Moreover, macrophage destruction of tumor cells apparently is not associated with the development of tumor cell resistance. Macrophages are found in association with malignant tumors in a definable pattern, suggesting that the most direct way to achieve macrophage-mediated tumor regression is in situ macrophage activation. Intravenously administered liposomes are cleared from the circulation by phagocytic cells, including macrophages, so when liposomes containing immunomodulators are endocytosed, cytotoxic macrophages are generated in situ. The administration of such liposomes in certain protocols has been shown to bring about eradication of cancer metastases. Macrophage destruction of metastases in vivo is significant, provided that the total tumor burden at the start of treatment is minimal. For this reason, we have been investigating various methods to achieve maximal cytoreduction in metastases by modalities such as chemotherapy or radiotherapy prior to macrophage-directed therapy. It is important to note that even the destruction of 99.9% of cells in a metastasis measuring 1 cm2 would leave 10(6) cells to proliferate and kill the host. The ability of tumoricidal macrophages to distinguish neoplastic from bystander nonneoplastic cells presents an attractive possibility for treatment of the few tumor cells which escape destruction by conventional treatments. Macrophage-directed therapy has been studied in several human protocols, yielding important biological information about the use of liposome-encapsulated macrophage activators in cancer patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Macrophages: current views on their differentiation, structure, and function

Macrophages are large mononuclear phagocytes that represent the major differentiated elements of the mononuclear phagocytic system. They arise from distinct progenitors in the bone marrow, and their immediate precursors, the monocytes, emigrate from the vascular compartment into many tissues and organs where they develop into mature macrophages. The latter display diverse morphological and functional characteristics, depending on the environmental stimuli that they receive. This phenotypic heterogeneity is, therefore, the final consequence of a series of down-regulation of some cellular processes and the up-regulation of others. The kinetics of the production of macrophages and their participation in various physiological and pathological phenomena is the subject of this review.

Effect of photodynamic therapy on anti-tumor immune defenses: comparison of the photosensitizers hematoporphyrin derivative and chloro-aluminum sulfonated phthalocyanine

The effects of the two photosensitizers chloroaluminum sulfonated phthalocyanine (ClAlSPc) and hematoporphyrin derivative (HpD) on the functional activities of macrophages and natural killer (NK) cells, two immunocyte populations implicated in the control of tumor development and spread, have been investigated. Murine peritoneal macrophages treated in vivo with ClAlSPc or HpD at 10 mg/kg body weight showed no impairment of Fc-mediated phagocytic capacity and only minor disturbances of in vitro tumoricidal/tumoristatic function. The NK cell activity of splenocytes obtained from photosensitizer-treated mice, assayed 24 or 48 h after i.v. injection of ClAlSPc or HpD at 10 mg/kg was unaffected compared to controls. However significant inhibition of NK activity was observed when splenocytes obtained from mice with or without subcutaneous Colo 26 tumors, treated with ClAlSPc plus laser therapy (675 nm) were used as effector cells. The results show that impairment of some anti-tumor activity can be observed in phthalocyanine treated or phthalocyanine + laser-treated animals but this relatively minor impairment may augur well for the use of systemic phthalocyanine administration in photodynamic therapy.

Effects of CKS-17, a synthetic retroviral envelope peptide, on cell-mediated immunity in vivo: immunosuppression, immunogenicity, and relation to immunosuppressive tumor products

CKS-17 is a heptadecapeptide corresponding to a region highly conserved in retroviral transmembrane proteins such as p15E. Because a relationship had previously been determined between p15E and immunosuppressive tumor cell products, we examined the effect of CKS-17, control peptides and conjugates thereof on the expression of cell-mediated immunity (delayed-type hypersensitivity, DTH) in mice. Conjugates of CKS-17 inhibited DTH reactions to sheep erythrocytes in the feet of mice. The degree of inhibition was dose-dependent. Unconjugated CKS-17 had almost no effect, and control peptide conjugates had no inhibitory effect. Immunization of mice with CKS-17 conjugates, but not with control conjugates, rendered them resistant to the depression of DTH reactions, not only by CKS-17 conjugates, but also by products of cultured tumor cells. CKS-17 conjugates, but not control conjugates, also depressed the cellular inflammatory reactions induced in mouse footpads by concanavalin A (ConA) and immunized mice against the depression of ConA reactions by products of cultured tumor cells. Injections of globulin from sera of mice immunized with CKS-17 conjugates conferred upon normal recipients resistance to the depression of footpad reactions to ConA by products of cultured tumor cells. Globulin from sera of normal mice or control immunized mice did not confer such resistance. Thus conjugates of a synthetic peptide not only mimic the immunosuppressive effects of tumor products in vivo, but can also immunize mice against those effects.

Cellular heterogeneity. Explanation for changing of tumor phenotype and biologic behavior in soft tissue sarcomas

Many human soft tissue sarcomas are known to show variable structures in a given tumor and to be able of changing the histological feature during the course of the disease. These facts prompted an experimental study in order to ascertain if by use of long-term cultures of an established rat fibrosarcoma cell line (RFS) in respective inoculation tumors a histological picture different from the original fibrosarcoma could be produced. It was found that inoculation tumors generated by later subcultures partly corresponded to tumors with features of malignant histiocytomas and malignant fibrous histiocytomas. In a further experiment we attempted to initiate metastatic dissemination of a primarily non-metastasizing xenotransplanted RFS sarcoma in nude mice. By repeated diminution operations comparable to inadequate tumor surgery in human metastasis formation in lung parenchyme was attained. Taking into account cellular heterogeneity as basically responsible for the phenomena observed, different causal aspects concerning the experimental results are discussed. We deduce from our findings that the concept of histogenetic classification of soft tissue sarcomas should be replaced by an interpretation according to the actual differentiation. This also applies to malignant fibrous histiocytomas which are at least in part mesenchymal tumors and not descendants of mononuclear phagocytic cells and may originate by a dedifferentiation process of otherwise defined sarcoma types.

Hormonal changes following tumor transplantation: factors increasing corticosterone and the relationship of corticosterone to tumor-induced anti-inflammation

EL-4 lymphoma cells transplanted to syngeneic C57BL/6J mice induced a biphasic decrease in inflammation and a bi-phasic increase in serum levels of corticosterone. In addition, this tumor altered serum levels of 3 other hormones, resulting in a biphasic decrease in insulin, an early decrease in prolactin, and a terminal severe deficiency in thyroxine. Early changes occurred 16 to 48 hr after tumor transplantation and were of variable duration, while late-phase defects developed during the last few days of life. Soluble factors associated with tumor growth may mediate certain hormonal changes since serum levels of corticosterone increased and insulin decreased following injection of tumorous ascites into normal mice. Further, injection of cell-free tumor culture supernatants increased corticosterone levels. Hormonal changes following injection of soluble factors occurred after a delay of 16 hr indicating that the factors acted indirectly. Surgical adrenalectomy blocked the corticosterone increase induced by tumor transplantation or ascites injection and eliminated the anti-inflammatory effect of tumor transplantation while significantly decreasing the effect associated with injection of tumorous ascites. Thus, the physiologically induced increase in serum levels of corticosterone reached anti-inflammatory levels. Further, elevated levels of corticosterone are a major contributing factor to anti-inflammation induced by tumorous ascites injection and constitute the principal mechanism of anti-inflammation following tumor transplantation.

Inhibition of cell-mediated immunity by tumour cell products: depression of interleukin-2 production and responses to interleukin-2 by mouse spleen cells

Supernatants from cultures of mouse and human tumour cells inhibited the production of interleukin-2 (IL-2) by stimulated mouse spleen cells. The tumour cells tested, all of which were active, included a mouse and a human melanoma, three methylcholanthrene-induced fibrosarcomas of mice, and human HeLa cells. Supernatants from normal mouse and human fibroblasts were inactive. Inhibition was dose-dependent. Spleen cells from aged mice were more susceptible to inhibition than spleen cells from young mice. When tumour cell culture supernatants were fractionated on Sephacryl S-300, two peaks of activity were found, with apparent molecular weights of approximately 50 and 18 kD. Supernatants from tumour cell and fibroblast cultures caused variable, but generally weak, inhibition of responses of lymphoblasts to IL-2. It is suggested that inhibition of IL-2 production may be an important mode of action of tumour cell products that inhibit cell-mediated immunity.

Distribution and survival of passively transferred lymphoblasts in normal and tumor-bearing mice

Although most circulating lymphocytes are long-lived small lymphocytes, it is the recently-divided medium and large-sized lymphoblasts that most clearly migrate to sites of inflammation, and they do so without regard to immunologic commitment. The tumor-bearing state frequently suppresses macrophage accumulation at inflammatory sites but it is not known whether lymphocyte traffic is similarly affected. We addressed this issue using passively transferred radiolabelled lymphoblasts. Lymphoblasts readily entered s.c. fibrosarcomas transplanted to C57BL/6 mice. Large and small tumors acquired the same number of lymphoblasts per gram of tumor, indicating the absence of an anti-inflammatory reaction. However, the intra-tumoral survival of lymphoblasts was shorter in large than in small tumors. Shortened survival was noted also in spleen and whole body of animals bearing tumors. Shortened survival rather than impaired emigration may contribute to the increase in tumor:lymphocyte ratio observed with large tumors. The adverse effect of tumor bearing on lymphoblast survival may be limited to tumors which acquire a high percentage of passively transferred lymphocytes since intraperitoneal P-815 mastocytomas in DBA/2 mice acquired few labelled lymphoblasts and did not alter lymphoblast survival. These results are important for host resistance to tumor growth and therapeutically for the use of lymphocyte cytotoxic cells induced to proliferate in vitro.

In adequate tumor surgery of chemically induced soft tissue sarcomas--an experimental approach for induction of metastasis formation?

In preceding experiments with nude mice bearing xenotransplanted soft tissue sarcomas after inoculation of cultured sarcoma cells we attained a high percentage of metastatic dissemination by repeated inadequate tumor surgery. In the study presented here we used methylcholanthrene induced sarcomas (rhabdomyosarcomas and undifferentiated sarcomas in part showing the picture of storiform/pleomorphic malignant fibrous histiocytomas) which were produced in NMRI mice and examined (1) whether or not metastasis formation could be triggered or enhanced by repeated inadequate tumor surgery in these animals, and (2) the efficacy of the same surgical procedure following xenotransplantation of the tumors into nude mice. We did not reach an increasing frequency with both experimental arrangements. After discussing several factors which could be in general responsible for inducing metastasis formation and after comparing the results of our several experiments it is suggested that the methylcholanthrene induced soft tissue tumors may not contain cell clones able to metastasize.