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Background: We investigated the expression of CXCR4, CCR7, estrogen receptor (ER), progesterone receptor (PR) and HER2-neu in human metastatic breast cancers to determine whether these biological biomarkers were preferentially expressed in any organ-specific metastases., Materials and Methods: CXCR4, CCR7, ER, PR and HER2-neu expression levels were evaluated by immunohistochemical staining using paraffin-embedded tissue sections of metastatic breast cancers (n = 41) obtained by either diagnostic biopsy or surgical resection., Results: The metastatic sites included the following: bone (n = 15), brain (n = 14), lung (n = 6), liver (n = 2), and omental metastases (n = 2). CXCR4 was expressed in 41% of cases, CCR7 expression was demonstrated in 10%, and HER2-neu overexpression was present in 27%. CXCR4 was more likely to be expressed in bone metastases than visceral metastases (67% versus 26%, P = 0.020). Visceral sites demonstrated a lower rate of CXCR4 positivity (33% and 23%, respectively, for lung and brain metastases). Similarly, CCR7 was more likely to be found in bone metastases than visceral sites (27% versus 0%, P = 0.037)., Conclusions: These results indicate that CXCR4 can contribute to the homing of breast cancer cells to the bone. This finding might have important clinical implications since patients with metastatic bone disease may achieve the highest benefit from a CXCR4-targeted therapy.

The purpose of this study was to determine whether systemic administration of interferon-alpha (IFN-alpha) can inhibit liver metastasis produced in nude mice by human colon cancer cells. KM12L4 (IFN-alpha-sensitive) or KM12L4 IFN(R) (IFN-alpha-resistant) cells were injected into the spleen of nude mice. Seven days later, the mice were treated with subcutaneous (s.c.) injections of IFN-alpha (70,000 units/week) at different dosing schedules (1, 2, or 7 times/week). Significant inhibition of tumor growth, vascularization and expression of basic fibroblast growth factor (bFGF) or matrix metalloproteinase-9 (MMP-9) mRNA and protein occurred in mice given daily injections of IFN-alpha. Kinetic analysis of therapy showed that daily s.c. administrations of 10,000 units of IFN-alpha induced apoptosis in liver metastasis-associated endothelial cells, followed by inhibition of tumor cell division and apoptosis of tumor cells. These data suggest that the antiangiogenic activity of IFN-alpha-2a depends on frequent administration of the optimal biologic dose.

We determined the molecular mechanisms that regulate the pathogenesis of malignant pleural effusion (PE) associated with advanced stage of human, non-small-cell lung cancer. Intravenous injection of human PC14 and PC14PE6 (adenocarcinoma) or H226 (squamous cell carcinoma) cells into nude mice yielded numerous lung lesions. PC14 and PC14PE6 lung lesions invaded the pleura and produced PE containing a high level of vascular endothelial growth factor (VEGF)-localized vascular hyperpermeability. Lung lesions produced by H226 cells were confined to the lung parenchyma with no PE. The level of expression of VEGF mRNA and protein by the cell lines directly correlated with extent of PE formation. Transfection of PC14PE6 cells with antisense VEGF165 gene did not inhibit invasion into the pleural space but reduced PE formation. H226 cells transfected with either sense VEGF 165 or sense VEGF 121 genes induced localized vascular hyperpermeability and produced PE only after direct implantation into the thoracic cavity. The production of PE was thus associated with the ability of tumor cells to invade the pleura, a property associated with expression of high levels of urokinase-type plasminogen activator and low levels of TIMP-2. Collectively, the data demonstrate that the production of malignant PE requires tumor cells to invade the pleura and express high levels of VEGF/VPF.

We determined whether hyperplastic mucosa adjacent to colon cancer contributes to neoplastic angiogenesis. Surgical specimens of human colon cancer (40 Dukes' stage B and 34 Dukes' stage C) were analyzed by immunohistochemistry for expression of proliferative and angiogenic molecules. The mucosa adjacent to Dukes' stage C tumors (but not Dukes' stage B tumors) had a higher Ki-67 labeling index and a higher expression of epidermal growth factor receptor and transforming growth factor-alpha than distant mucosa. The expression levels of vascular endothelial growth factor, basic fibroblast growth factor, interleukin-8, and the vascular density in the adjacent mucosa were similar to those in the tumor lesions and significantly higher than those in the distant mucosa. The expression of interferon-beta inversely correlated with the level of pro-angiogenic molecules and the vascular density. The injection of metastatic human colon cancer cells and murine colon cancer cells into the cecal wall of mice induced hyperplastic changes in the adjacent mucosa which expressed higher levels of epidermal growth factor receptor, basic fibroblast growth factor, and vascular endothelial growth factor, and lower levels of interferon-beta than did the control mucosa, which directly correlated with the degree of hyperplasia. These data suggest that metastatic human colon cancer cells can induce hyperplasia in the adjacent mucosa, which in turn produces angiogenic molecules that contribute to neoplastic angiogenesis.

The cytokine interferon-beta is a regulator of cell replication and function, including invasion and induction of angiogenesis. The goal of this study was to determine whether the expression of interferon-beta by cells in the epidermis correlated with terminal differentiation. In situ hybridization analysis and immunohistochemical staining of formalin-fixed, paraffin-embedded specimens of normal human and murine epidermis and human and murine skin tumors of epithelial origin revealed that only differentiated, nondividing cells of the epidermis expressed interferon-beta protein. Keratinocyte cultures established from the epidermis of 3 d old mice were maintained under conditions permitting continuous cell division or induction of differentiation. Continuously dividing cells did not produce interferon-beta whereas nondividing differentiated cells expressing keratin 1 did. Growth-arrested, undifferentiated keratinocytes also expressed interferon-beta protein. Neutralizing interferon-beta in the culture medium inhibited differentiation, but the addition of exogenous interferon-beta did not stimulate differentiation. These data indicate that interferon-beta is produced by growth-arrested, terminally differentiated keratinocytes.

We demonstrated previously that p53 mutations can be detected in ultraviolet B-irradiated mouse skin months before the gross appearance of skin tumors and that applying sun protection factor 15 sunscreens to mouse skin before each Kodacel-filtered FS40 sunlamp irradiation resulted in the reduction of such mutations. To determine whether there is an association between reduction of ultraviolet-induced p53 mutations by sunscreens and protection against skin cancer using an environmentally relevant light source, we applied sunscreens (sun protection factors 15-22) on to the shaved dorsal skin of C3H mice 30 min before each exposure to 4.54 kJ ultraviolet B (290-400 nm) radiation per m2 from a solar simulator. Control mice were treated 5 d per wk with ultraviolet only or vehicle plus ultraviolet. p53 mutation analysis indicated that mice exposed to ultraviolet only or vehicle plus ultraviolet for 16 wk (cumulative exposure to 359 kJ ultraviolet B per m2) developed p53 mutations at a frequency of 56%-69%, respectively, but less than 5% of mice treated with sunscreens plus ultraviolet showed evidence of p53 mutations. More importantly, 100% of mice that received a cumulative dose of 1000 kJ ultraviolet B per m2 only, or vehicle plus ultraviolet B developed skin tumors, whereas, the probability of tumor development in all the mice treated with the sunscreens plus 1000 kJ ultraviolet B per m2 was 2% and mice treated with sunscreens plus 1500 kJ ultraviolet B per m2 was 15%. These results demonstrate that the sunscreens used in this study not only protect mice against ultraviolet-induced p53 mutations, but also against skin cancers induced with solar-simulated ultraviolet. Because of this association, we conclude that inhibition of p53 mutations is a useful early biologic endpoint of photoprotection against an important initiating event in ultraviolet carcinogenesis.

We determined whether cutaneous angiogenesis induced by exposure of mice to ultraviolet-B (UVB) radiation is associated with an imbalance between positive and negative angiogenesis-regulating molecules. Unshaved C3H/HeN mice were exposed to a single dose (15 kJ per m2) of UVB. At various times, the mice were killed, and their external ears were processed for routine histology and immunohistochemistry. Antibodies against proliferating cell nuclear antigen and bromodeoxyuridine identified dividing cells. Antibodies against CD31/ PECAM-1 identified endothelial cells, and antibodies against basic fibroblast growth factor (bFGF), vascular endothelial growth factor/vascular permeability factor, and interferon-beta (IFN-beta) identified angiogenesis-regulating molecules. Epidermal hyperplasia was documented by 48 h and reached a maximum on day 7 after exposure to UVB. The expression of bFGF increased by 24 h, whereas the expression of IFN-beta decreased by 72 h after exposure to UVB. The expression of vascular endothelial growth factor/vascular permeability factor increased slightly after irradiation. The altered balance between bFGF and IFN-beta was associated with increased endothelial cell proliferation (bromodeoxyuridine + CD31 + cells) within existing blood vessels, leading to telangiectasia and new blood vessels. UV-induced epidermal hyperplasia and cutaneous angiogenesis were highest in IFN-alpha/beta receptor knockout mice. These results demonstrate that in response to UVB radiation, dividing keratinocytes produce a positive angiogenic molecule (bFGF) but not a negative angiogenic molecule (IFN-beta), and that this altered balance is associated with enhanced cutaneous angiogenesis.

Cutaneous exposure to ultraviolet radiation suppresses the induction of T cell mediated responses such as contact and delayed type hypersensitivity (DTH) by altering the function of immune cells in the skin and causing the release of immunoregulatory cytokines. Extracts of crude Aloe barbadensis gel prevent this photosuppression. Because the regulation of contact hypersensitivity and DTH responses differ, we investigated whether protection was afforded by a single or multiple agents in Aloe and the mechanism by which this material prevents suppression of DTH immunity. The ability of Aloe gel to prevent suppression of contact hypersensitivity responses to hapten decayed rapidly after manufacture. In contrast, agents that protected against systemic suppression of DTH responses to Candida albicans were stable over time. Oligosaccharides prepared from purified Aloe polysaccharide prevented suppression of DTH responses in vivo and reduced the amount of IL-10 observed in ultraviolet irradiated murine epidermis. To assess the effect of Aloe extracts on keratinocytes, Pam 212 cells were exposed in vitro to ultraviolet radiation and treated for 1 h with Aloe oligosaccharides. Culture supernatants were collected 24 h later and injected into mice. Supernatants from ultraviolet irradiated keratinocytes suppressed the induction of DTH responses, whereas Aloe oligosaccharide treatment reduced IL-10 and blocked the suppressive activity of the supernatants. These results indicate that Aloe contains multiple immunoprotective factors and that Aloe oligosaccharides may prevent ultraviolet induced suppression of DTH by reducing keratinocyte derived immunosuppressive cytokines.

We examined the role of urokinase-type plasminogen activator (u-PA) in the metastasis of the human renal cell carcinoma (HRCC) implanted in athymic nude mice. Cells from a HRCC KG-2 line were implanted in orthotopic (kidney) and ectopic (subcutaneous) organs. The KG-2 cells implanted in the kidney produced local tumors and lung metastases, whereas those implanted subcutaneously produced only local tumors. The production of u-PA was determined by immunohistochemistry and an enzyme-linked immunosorbent assay (ELISA). High levels of u-PA were produced by the metastatic kidney tumors and lung metastases, whereas the subcutaneous tumors produced low levels. KG-2 cells co-cultured with mouse kidney or lung fibroblasts produced higher levels of u-PA than KG-2 cells co-cultured with mouse skin fibroblasts. Furthermore, KG-2 cells cultured with the conditioned medium from mouse kidney or lung fibroblasts produced higher levels of u-PA than KG-2 cells cultured with the conditioned medium from mouse skin fibroblasts. The results indicate that the expression of u-PA by KG-2 cells is one of the important factors that determine their metastatic potential and that the production of u-PA is influenced by the organ microenvironment, including soluble factors produced by surrounding fibroblasts.

The purpose of this study was to determine whether the expression level of several metastasis-regulating genes correlates with the metastatic potential of human prostate cancer cells implanted into the prostate of nude mice. The steady-state mRNA expression levels for epidermal growth factor receptor (EGFR; growth), basic fibroblast growth factor (bFGF) and interleukin (IL)-8 (angiogenesis), 72-kd and 92-kd type IV collagenase (invasion), E-cadherin (adhesion), and multidrug resistance (mdr-1; drug resistance) were measured by Northern blot and colorimetric in situ hybridization techniques in human PC-3M cells and selected cell variants with different metastatic potentials. Highly metastatic cells growing in culture constitutively and uniformly expressed higher levels of bFGF, IL-8, type IV collagenase, and mdr-1 mRNA transcripts than parental PC-3M cells or low metastatic cells, which displayed a heterogeneous pattern of gene expression. Human prostate cancer cells implanted in nude mice at an ectopic site (subcutaneous) expressed lower levels of EGFR, mdr-1, bFGF, IL-8, and collagenase type IV than those implanted in an orthotopic site (prostate), indicating that the expression of these genes was dependent on the organ environment. Highly metastatic cells growing in the prostate expressed higher levels of EGFR, bFGF, type IV collagenase, and mdr-1 mRNA than low metastatic parental cells in the same site. These data demonstrate a direct correlation between the expression of several metastasis-related genes and the metastatic potential of human prostate cancer cells in nude mice and suggest that multiparametric in situ hybridization analyses can be used to identify the metastatic potential of individual patients' prostate cancers.

The purpose of this study was to determine whether the ability of K-1735 murine melanoma cells to repair DNA damage correlates with their metastatic potential. Three nonmetastatic clones, four metastatic clones, and three somatic-cell hybrids between metastatic and nonmetastatic clones were exposed to incident ultraviolet (UV) light (254 nm). Cell survival was determined by the microculture tetrazolium assay, which measures cell metabolic activity. DNA repair capacity was determined with a host-cell reactivation assay, which measures the activities of chloramphenicol acetyltransferase encoded by the reporter gene in both UV-damaged and undamaged plasmid (control) pCMV cat 40 h after transfection. No discernible differences in transfection efficiencies were found between K-1735 clones with low and high metastatic potential or between cells transfected with UV-damaged and control plasmids. DNA repair capacity directly correlated with cell survival (p < 0.05) and with metastatic potential in the K-1735 clones and somatic cell hybrids (p < 0.05). These data suggest that the intrinsic resistance of melanoma metastases to systemic chemotherapy may be due, in part, to the cells' enhanced DNA repair capacity.

We examined the expression level of several genes that regulate different steps of metastasis in formalin-fixed, paraffin-embedded archival specimens of primary human colon carcinomas from patients with at least 5 years of follow-up. The expression of epidermal growth factor receptor, basic fibroblast growth factor, type IV collagenase, E-cadherin, and multidrug resistance (mdr-1) was examined by a colorimetric in situ mRNA hybridization technique concentrating on reactivity at the periphery of the neoplasms. The in situ hybridization technique revealed inter- and intratumor heterogeneity for expression of the metastasis-related genes. The expression of basic fibroblast growth factor, collagenase type IV, epidermal growth factor receptor, and mdr-1 mRNA was higher in Dukes's stage D than in Dukes' stage B tumors. Among the 22 Dukes' stage B neoplasms, 5 specimens exhibited a high expression level of epidermal growth factor receptor, basic fibroblast growth factor, and collagenase type IV. Clinical outcome data (5-year follow-up) revealed that all 5 patients with Dukes' stage B tumors developed distant metastasis (recurrent disease), whereas the other 17 patients with Dukes' stage B tumors expressing low levels of the metastasis-related genes were disease-free. Multivariate analysis identified high levels of expression of collagenase type IV and low levels of expression of E-cadherin as independent factors significantly associated with metastasis or recurrent disease. More specifically, metastatic or recurrent disease was associated with a high ratio (> 1.35) of expression of collagenase type IV to E-cadherin (specificity of 95%). Collectively, the data show that multiparametric in situ hybridization analysis for several metastasis-related genes may predict the metastatic potential, and hence the clinical outcome, of individual lymph-node-negative human colon cancers.

The expression of carcinoembryonic antigen (CEA) is thought to be involved in homotypic adhesion and has been associated with the progression of human colon carcinomas (HCC) to the metastatic state. Three cell lines established from surgical specimens of Dukes' stage D (KM20) or Dukes' stage B (KM12C, KM12SM) with high and low preoperative CEA serum levels, respectively, were studied subsequent to growth in culture, in the subcutis (ectopic) or cecal wall (orthotopic) of nude mice. In all cell lines, CEA expression was higher in cecal tumors than in subcutaneous lesions. The degree of differentiation and CEA expression by HCC growing in the cecal wall of nude mice correlated with the pathological diagnosis and preoperative CEA level of the original patients. To better understand the regulation of CEA expression, the HCC cells were grown in culture as sparse and confluent monolayers or as multicell spheroids. The CEA expression level increased in all three cell lines growing as confluent monolayers and was highest in multicell spheroids. Treatment of sparse monolayer cultures of KM12SM cells with mitomycin-C inhibited cell division and was associated with higher production of CEA protein. Moreover, conditioned media from confluent monolayer cultures or from spheroids up-regulated CEA production in sparse monolayer cells. These data show that CEA expression in HCC cells may be regulated by cell density and by factors from the organ environment.

We examined the expression of E-cadherin and collagenase type IV in formalin-fixed, paraffin-embedded specimens of human gastric carcinoma by an in situ mRNA hybridization (ISH) technique. The ISH technique revealed intertumoral heterogeneity for expression of E-cadherin and collagenase among 12 cases of early gastric cancer and 13 cases of advanced gastric cancer. In the majority of the tumors, we found an inverse relationship between the reactivities of E-cadherin and collagenase type IV. Specifically, E-cadherin was expressed at higher levels in the center of the neoplasms than in their periphery, whereas collagenase type IV was expressed at a higher level in the periphery (invasive edge) than in the center. Advanced gastric cancers with high levels of expression for collagenase type IV in the periphery had a higher incidence of distant lymph node metastasis than those with low expression. The data show an inverse relationship between E-cadherin (involved in cell-to-cell adhesion) and collagenase type IV (involved in invasion) in different zones of human gastric carcinoma and suggest that the relative expression of these independent genes may be involved in local invasion and metastasis.

The purpose of this study was to determine whether the expression level of several genes that regulate different steps of the metastatic process correlates with the metastatic potential of human colon carcinoma cells. The mRNA expression level for epidermal growth factor receptor (growth), basic fibroblast growth factor and interleukin-8 (angiogenesis), type IV collagenase (invasion), E-cadherin and carcinoembryonic antigen (adhesion), and the multidrug resistance gene mdr-1 (drug resistance) in the human KM12 colon carcinoma cell lines and clones with different metastatic potential was measured by Northern blot analysis and by in situ hybridization technique. Highly metastatic KM12SM and KM1214 cells growing in culture uniformly expressed high levels of epidermal growth factor receptor, basic fibroblast growth factor, and carcinoembryonic antigen mRNA, whereas cultures of low metastatic KM12C, clone 1, clone 3, and clone 6 cells displayed heterogeneous patterns of expression. KM12C (low metastatic) and KM12SM (highly metastatic) cells were implanted into the subcutis (ectopic) or the wall of the cecum (orthotopic) of nude mice. The mRNA expression level for epidermal growth factor receptor, basic fibroblast growth factor, interleukin-8, type IV collagenase, carcinoembryonic antigen, and mdr-1 was increased in the cecal wall tumors as compared with subcutaneous tumors or in vitro cultures. These data demonstrate a direct correlation between constitutive and inducible expression of several metastasis-related genes and the metastatic potential of human colon carcinoma cells.

Ultraviolet-B irradiation of murine skin before contact sensitization alters the antigen-presenting activity of cells in the skin and draining lymph nodes (DLN), decreases the contact hypersensitivity (CHS) response, and induces hapten-specific Ts cells. We determined whether hapten-bearing antigen-presenting cells (APC) from the DLN of UV-irradiated mice induce Ts cells. APC from UV-irradiated, FITC-sensitized mice were isolated, and FITC+ cells were FACS-purified and injected into the hind footpads of naive, syngeneic mice. Unseparated and FACS-purified bright FITC+ cells (FITChi) from UV-irradiated mice induced Ts. However, dull (FITClo) FITC+ cells, T-cell-depleted FITChi cells, or DLN cells from C3H SCID mice failed to induce Ts. Injection of FITC-bearing DLN cells from nonirradiated mice into UV-irradiated recipients failed to immunize and induced Ts instead. Treatment of the UV-irradiated recipients with anti-TNF-alpha blocked these effects. Thus, transferable suppression is due to Thy-1+ cells, does not require UV-altered APC for induction, and may depend on TNF-alpha.

Ultraviolet radiation (UVR) modulates cellular immunity in humans and experimental animals and can interfere with immune responses against infectious agents in animal models. We used the lepromin reaction, a cell-mediated immune response to antigens of Mycobacterium leprae, to determine whether UVR affects the cellular immune response to an infectious agent in humans. We selected 29 healthy, lepromin-positive contacts of leprosy patients and determined their minimal erythema dose (MED) of UVR. Immediately afterward, each subject was injected with 0.1 ml of lepromin in two areas of the buttocks: one at the site that had received twice the MED of UVR and the other on the contralateral, unirradiated site. The irradiated site was given twice the MED every 4 d for a total of five treatments. One week after the last irradiation, both lepromin reactions were measured and biopsied. The size of the lepromin-induced granulomas was significantly reduced in the irradiated site, as was the number of lymphocytes. Immunohistochemical analysis showed a depletion in the number of infiltrating cells and a lower percentage of T cells, particularly the CD4+ subpopulation, in granulomas formed in UV-irradiated skin. This study demonstrates that local UV irradiation reduces the granulomatous reaction to lepromin in sensitized individuals. These findings are of clinical relevance because of the fundamental role played by the delayed-type hypersensitivity response in defense against intracellular pathogens and because of potential increases in the amount of UVR in sunlight reaching the earth's surface.

We investigated the influence of organ microenvironment on the angiogenic phenotype in human renal cell carcinoma (HRCC) cells. HRCC line SN12C was established in vitro from a surgical specimen, and metastatic line SN12PM6 was isolated from a lung metastasis produced by parental cells implanted into the kidney of nude mice. SN12C (low metastasis) and SN12PM6 (high metastasis) cells were injected into the kidney or subcutis of nude mice. The kidney tumors were highly vascularized (as revealed by immunohistochemistry using antibodies against factor VIII), and metastatic, whereas the subcutaneous tumors were not. The expression of mRNA for basic fibroblast growth factor (bFGF) in kidney tumors was 10 to 20 times that found in subcutaneous tumors. Similar data were obtained at the protein level by using fluorescence activated cell sorting, immunohistochemistry, and enzyme-linked immunosorbent assay. bFGF was detected in the urine of mice with tumors in the kidney but not subcutaneous tumors. The level of bFGF in the serum of mice with kidney tumors was two to three times that in mice with subcutaneous tumors. The changes in bFGF expression in the tumors was transient. Collectively, these data indicate that the organ microenvironment can influence the expression level of bFGF in HRCC.

Exposure of murine skin to suberythemal doses of ultraviolet-B (UVB) radiation before contact sensitization alters the activity of antigen-presenting cells (APC) in the draining lymph nodes (DLN), decreases the contact hypersensitivity (CHS) response, and induces hapten-specific Ts cells. We determined whether in vivo UVB irradiation alters the ability of hapten-bearing APC from the DLN to form clusters with hapten-specific T lymphocytes. When APC from UV-irradiated, fluorescein isothiocyanate (FITC)-sensitized mice were mixed with a FITC-specific T-cell line, significantly fewer clusters formed compared with FITC+ APC from unirradiated mice. A higher percentage of clusters formed with APC from UV-irradiated mice were Mac-1+ and bound both CD4+ and CD8+ T cells, whereas FITC+ APC from nonirradiated mice bound CD4+ cells. These results suggest that UVB irradiation interferes with the induction of CHS by altering the functional interaction between APC and T cells, perhaps by altering the population of APC in the skin.

We investigated the surface phenotype and localization of hapten in antigen-presenting cells involved in the induction of contact hypersensitivity or tolerance. Dendritic cells collected 18 h earlier from the draining lymph nodes of mice sensitized with fluorescein isothiocyanate (FITC), which induce contact hypersensitivity upon injection into the foot-pads of naive mice, stimulated proliferation of lymphocytes from FITC-specific T-cell lines. By immunoelectron microscopy, these cells expressed high amounts of surface Ia molecules but had a negligible amount of FITC on the cell membrane. The majority of the FITC was localized in discrete structures in the cytoplasm, including mitochondria, endocytic vesicles, lysosomes, and cored tubules. In contrast, lymph node cells conjugated with FITC in vitro did not stimulate proliferation of FITC-specific T cells and showed a heavy, uniform distribution of FITC throughout the cytoplasm. Draining lymph node cells from mice exposed to ultraviolet (UV) radiation and then sensitized by applying FITC to the UV-irradiated skin, which induce tolerance upon injection into naive mice, induced significantly less proliferation of FITC-specific T cells than draining lymph node cells from unirradiated mice. The differences in activity of these cells, relative to draining lymph node cells from unirradiated, FITC-sensitized mice could not be attributed to a decreased number of Ia+ dendritic cells in the DLN, decreased surface expression of Ia molecules on these cells, or an alteration in the intracellular localization of hapten. However, a significantly higher percentage of the FITC+ dendritic cells from UV-irradiated mice expressed mac-1, -2, and -3 and F4/80 macrophage markers than did those from unirradiated animals, and fewer cells contained Birbeck granules, suggesting that a different population of Ia+ antigen-presenting cells may reach the draining lymph nodes of UV-irradiated mice.

We examined the in vitro regulation of the production of two type IV collagenases, MMP-2 and MMP-9, by A431 human epidermoid carcinoma cells. The A431 cells were cultured under sparse or confluent conditions. The addition of transforming growth factor-beta (TGF-beta) or phorbolester-TPA to sparse cultures induced low levels of MMP-9 secretion, whereas in confluent cultures only TGF-beta produced this effect. Neither treatment altered the level of constitutive secretion of MMP-2. Treatment of sparse, actively growing cultures but not confluent stationary cultures with both TGF-beta and TPA produced synergistic induction of MMP-9 but did not affect MMP-2. A431 cells were grown as discrete large monolayer colonies. Radiolabeling with [3H]leucine or [3H]thymidine followed by autoradiography revealed that all the A431 cells in the colonies were metabolically active and only those on the periphery were dividing. Only these dividing A431 cells stained positive by anti-MMP-9 antibodies. Our results demonstrate that the synergistic induction of MMP-9 secretion in A431 cells occurs subsequent to stimulation by external signals in only noncontact-inhibited dividing tumor cells. These regulatory mechanisms may account for the in vivo finding that many proteinases are localized at the invasion front of a neoplasm where tumor cells are dividing and accessible to various environmental signals.

We examined whether fibroblasts from subcutaneous, colon or lung tissues of nude mice influence the invasive potential of highly metastatic human colon carcinoma KM12SM cells. Primary cultures of nude mouse fibroblasts from skin, lung and colon were established. Invasive and metastatic KM12SM cells were cultured alone or with fibroblasts. Growth and invasive properties of the KM12SM cells were evaluated as well as their production of gelatinase activity. KM12SM cells were able to grow on monolayers of all three fibroblast cultures but did not invade through skin fibroblasts. The conditioned media of KM12SM cells cocultured with skin, colon or lung fibroblasts were examined for the presence of type IV collagenase (gelatinase). KM12SM growing on plastic and on colon or lung fibroblasts produced significant levels of latent and active forms of 64 kDa type IV collagenase, whereas KM12SM cells cocultivated with nude mouse skin fibroblasts did not. In contrast, human squamous cell carcinoma A431 cells produced significant levels of collagenase type IV when cocultured with nude mouse skin fibroblasts, a tissue they invaded and completely penetrated. Incubation of KM12SM cells in serum-free medium containing recombinant human interferon-beta (fibroblast interferon) was associated with significant reduction in gelatinase activity. Since the production of type IV collagenase by human colon cancer cells is specifically inhibited by mouse skin fibroblasts but not by colon or lung fibroblasts the data suggest that organ-specific fibroblasts can influence the invasive and metastatic properties of KM12SM cells.

This study clarified whether and when the blood-brain barrier in experimental brain metastases is impaired by using hydrosoluble sodium fluorescein (MW 376) as a blood-brain barrier function indicator. Cells from eight human tumor lines (four melanomas, two breast carcinomas, one colon carcinoma, and one renal carcinoma) were inoculated into the internal carotid artery of nude mice. Brain metastases at different stages of development were sampled and the permeability of the blood-brain barrier around the metastases determined. Histologic examination showed two patterns of tumor growth. In the first, tumor cells formed isolated, well-defined nodules in the parenchyma of the brain. In lesions smaller than 0.2 mm2, the blood-brain barrier was intact. In the second, small diffuse nests of tumor cells were distributed throughout the brain parenchyma. The blood-brain barrier was intact until the small tumor cell colonies coalesced to form large tumor masses. These results suggest that the permeability of the blood-brain barrier varies among different experimental brain metastases and that its function is related to the growth pattern and size of the lesions.

This study determined the distribution pattern of tumor-associated macrophages (TAM) in murine and human neoplasms growing subcutaneously in nude mice. Seven different human neoplasms (cancers of the breast, kidney, colon, prostate, lung, and skin, and a melanoma) and five different murine neoplasms (carcinomas of the lung, colon, and kidney, melanoma, and fibrosarcoma) were injected into nude mice. The murine tumors also were injected into syngeneic mice. Tumor-associated macrophages in small and large tumors were studied immunohistochemically by the use of several antibodies, including the macrophage-specific F4/80. The pattern of TAM distribution differed between mouse and human tumors. Regardless of histologic classification, TAM were uniformly distributed throughout all the murine neoplasms growing in syngeneic or nude mice. In the human neoplasms, TAM were found on the periphery of the lesions and in association with fibrous septae. The distribution of TAM in murine and human tumors was associated with a pattern of vascularization as determined by antibodies to basement membrane collagen type IV. Because the pattern of TAM distribution in neoplasms influences their antitumor activity, the data question the validity of the nude mouse model for the study of macrophage infiltration into human neoplasms.

Dendritic cells isolated from the draining lymph nodes of mice sensitized epicutaneously with hapten are potent antigen-presenting cells and contain Birbeck granules and cored tubules characteristic of antigen-activated epidermal Langerhans cells. We used immunogold labeling and transmission electron microscopy to follow the internalization of Ia molecules in these antigen-presenting cells. We found that Ia molecules were internalized into Birbeck granule-like structures in the antigen-activated dendritic cells. Computer reconstruction of serial sections of the dendritic cells demonstrated that these structures span the cytoplasm from the cell membrane to the nuclear membrane and are associated with lysosomes. The internalization of Ia molecules into these structures supports the hypothesis that the Birbeck granule-like structures are derived from the cell membrane and are involved in the antigen-processing/presenting function of the dendritic cells.

Cells from eight different human melanomas and two murine melanomas were injected into the internal carotid artery of anesthetized nude mice. Although all were injected by the same route, particular melanomas produced lesions in different regions of the brain. Two melanoma cell lines isolated originally from brain metastases in patients produced metastases predominantly in the brain parenchyma. In contrast, melanoma cells from subcutaneous or lymph node metastases produced more lesions in the meninges, choroid plexus, and ventricles than in the brain parenchyma. All of the melanomas grew in the brain after a direct intracerebral injection. The pattern of brain metastasis did not correlate with tumorigenicity per se or with the ability of the melanomas to grow in the lungs of nude mice. Two mouse melanomas showed different patterns of experimental metastasis after internal carotid artery injection, with one growing predominantly in the parenchyma and the other more frequently in the meninges and choroid plexus. The growth pattern of human melanoma metastasis in the brain of T cell-deficient nude mice suggests that it is determined by properties unique to each tumor interacting with the host's organ microenvironment.

A new technique is described for the detection of intracellular antigens by immunofluorescence and flow cytometry. The technique utilizes lysolecithin (lysophosphatidylcholine), a naturally occurring phospholipid, to permeabilize cell membranes and allow antibodies to reach intracellular antigens. The technique is rapid and sensitive, and retains sufficient integrity of the cells being treated to enable differentiation of cell types on the basis of light scatter (e.g., lymphocytes from monocytes). Permeabilization of cells following lysolecithin was assessed using standard techniques including trypan blue exclusion, propidium iodide staining, and hydrolysis of fluorescein diacetate. Lysolecithin treatment was accompanied by only minimal increases in non-specific background fluorescence, and no increase in autofluorescence. Our studies have demonstrated that lysolecithin treatment of human mononuclear cell populations permits flow cytometric analysis of cytoskeletal structures, including intermediate filaments, as well as cytoplasmic immunoglobulin. Studies currently in progress in our laboratory have demonstrated broad intracellular reactivity with some monoclonal antibodies identifying leukocyte differentiation and tumor-associated antigens. These findings contrast with the more restricted expression of these antigens on the cell surface and demonstrate not only the value of the lysolecithin technique but also the importance of the study of intracellular antigens in our overall understanding of the specificity, distribution, synthesis, and function of cellular antigens.

Murine Kupffer cells (RC) were isolated in sufficient number and purity to allow in vitro investigations of their tumoricidal capabilities. The identity of the adherent cells as KCs was established by morphologic, histochemical, and functional criteria. The yield of KCs varied from young (high) to old (low) mice but was not affected by the mouse strain. KCs activated in vitro by either endotoxins (lipopolysaccharide) or lymphokines were rendered highly cytotoxic against syngeneic melanoma or fibrosarcoma target cells. These studies indicate that KCs may indeed play a role in destruction of tumor cells in vivo and thus be important in host defense against developing hepatic cancer metastases.

Human blood monocytes were activated to become tumoricidal by incubation with liposomes containing muramyl tripeptide-phosphatidylethanolamine, a lipophilic derivative of muramyl dipeptide. The interaction of both tumoricidal and control monocytes with target melanoma cells was analyzed by means of light microscopy and scanning and transmission electron microscopy. The authors found increased clustering around the melanoma cells by tumoricidal monocytes as compared with the control monocytes. The initial clustering of the tumoricidal monocytes around the tumor cells was followed by the establishment of numerous focal points of contact (binding), some of which actually exhibited areas of discontinuous membrane, a finding confirmed by stereophotography. By 24-48 hours of cocultivation, many of the target cells exhibited zones of vacuolation in the immediate vicinity of the tumoricidal monocytes, suggesting target cell damage. (This finding was confirmed by time-course cytotoxicity assays.) The authors conclude that tumor cell lysis mediated by activated human blood monocytes occurs as the final step in a process that includes the establishment of a direct cell-cell contact, damage to the target cell membrane, and the development of areas of vacuolation in the target cells.