Circulating miR-26b-5p and miR-451a as diagnostic biomarkers in medullary thyroid carcinoma patients.

PURPOSE/METHODS: The determination of tumour biomarkers is paramount to advancing personalized medicine, more so in rare tumours like medullary thyroid carcinoma (MTC), whose diagnosis is still challenging. The aim of this study was to identify non-invasive circulating biomarkers in MTC. To achieve this goal, paired MTC tissue and plasma extracellular vesicle samples were collected from multiple centres and microRNA (miRNA) expression levels were evaluated. RESULTS: The samples from a discovery cohort of 23 MTC patients were analysed using miRNA arrays. Lasso logistic regression analysis resulted in the identification of a set of circulating miRNAs as diagnostic biomarkers. Among them, miR-26b-5p and miR-451a, were highly expressed and their expression decreased during follow-up in disease-free patients in the discovery cohort. Circulating miR-26b-5p and miR-451a were validated using droplet digital PCR in a second independent cohort of 12 MTC patients. CONCLUSION: This study allowed the identification and validation of a signature of two circulating miRNAs, miR-26b-5p and miR-451a, in two independent cohorts reporting a significant diagnostic performance for MTC. The results of this study offer advancements in molecular diagnosis of MTC proposing a novel non-invasive tool to use in precision medicine.

Hyaluronan-estradiol nanogels as potential drug carriers to target ER+ breast cancer cell line.

An innovative hyaluronan-based nano-delivery system is proposed for the active targeting towards ER+ breast cancer. Hyaluronic acid (HA), an endogenous and bioactive anionic polysaccharide, is functionalized with estradiol (ES), a sexual hormone involved in the development of some hormone-dependent tumors, to give an amphiphilic derivative (HA-ES) able to spontaneously self-assemble in water to form soft nanoparticles or nanogels (NHs). The synthetic strategy used to obtain the polymer derivatives and the physico-chemical properties of the obtained nanogels (ES-NHs) are reported. ES-NHs ability to entrap hydrophobic molecules has also been investigated, by loading curcumin (CUR) and docetaxel (DTX), both able to inhibit the growth of ER+ breast cancer. The formulations are studied for their capability to inhibit the growth of the MCF-7 cell line, thus evaluating their efficacy and potential as a selective drug delivery systems. Our results demonstrate that ES-NHs have not toxic effects on the cell line, and that both ES-NHs/CUR and ES-NHs/DTX treatments inhibit MCF-7 cell growth, with ES-NHs/DTX effect higher than that of free DTX. Our findings support the use of ES-NHs to deliver drugs to ER+ breast cancer cells, assuming a receptor-dependent targeting.

Chloroquine supplementation increases the cytotoxic effect of curcumin against Her2/neu overexpressing breast cancer cells in vitro and in vivo in nude mice while counteracts it in immune competent mice.

Autophagy is usually a pro-survival mechanism in cancer cells, especially in the course of chemotherapy, thus autophagy inhibition may enhance the chemotherapy-mediated anti-cancer effect. However, since autophagy is strongly involved in the immunogenicity of cell death by promoting ATP release, its inhibition may reduce the immune response against tumors, negatively influencing the overall outcome of chemotherapy. In this study, we evaluated the in vitro and in vivo anti-cancer effect of curcumin (CUR) against Her2/neu overexpressing breast cancer cells (TUBO) in the presence or in the absence of the autophagy inhibitor chloroquine (CQ). We found that TUBO cell death induced by CUR was increased in vitro by CQ and slightly in vivo in nude mice. Conversely, CQ counteracted the Cur cytotoxic effect in immune competent mice, as demonstrated by the lack of in vivo tumor regression and the reduction of overall mice survival as compared with CUR-treated mice. Immunohistochemistry analysis revealed the presence of a remarkable FoxP3 T cell infiltrate within the tumors in CUR/CQ treated mice and a reduction of T cytotoxic cells, as compared with single CUR treatment. These findings suggest that autophagy is important to elicit anti-tumor immune response and that autophagy inhibition by CQ reduces such response also by recruiting T regulatory (Treg) cells in the tumor microenvironment that may be pro-tumorigenic and might counteract CUR-mediated anti-cancer effects.

Curcumin induces apoptosis in breast cancer cell lines and delays the growth of mammary tumors in neu transgenic mice.

Breast cancer is a leading cancer in women and despite the benefits of the current therapies a significant number of patients with this tumor is at risk of relapse. Some of the alterations taking place in breast cancer cells are currently exploited by molecularly targeted drugs. Different drugs have been developed which target a single molecule but, given that the tumor originates from the dysregulation of many genes, there is the need to find new drugs that have more than one molecular target. Curcumin [1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione] (CUR), a polyphenolic compound found in the spice turmeric, is a pleiotropic molecule able to interact with a variety of molecular targets and has antitumor, anti-inflammatory, antioxidant, immunomodulatory and antimicrobial activities. Here we demonstrate that CUR inhibits the growth of breast cancer cell lines in a dose dependent manner, with IC50 values in the micromolar range, and induces an increase in the percentage of cells in sub-G0 phase, representing the apoptotic cell population. The activation of apoptosis was confirmed by PARP-1 cleavage and by the increased ratio between the pro-apoptotic Bax and the anti-apoptotic Bcl-2 protein. In addition, in CUR-treated cells the activity of ERK1/ERK2 MAP kinases was down-regulated. The cytotoxic effects of CUR were observed in breast cancer cells expressing either high or low levels of ErbB2/neu. The in vivo antitumor activity of CUR was tested in BALB-neuT mice transgenic for the neu oncogene, which develop atypical hyperplasia of the mammary gland at 6 weeks of age and invasive carcinoma at 16 weeks of age. CUR, administered to mice both early and in an advanced stage of mammary carcinogenesis, induced a significant prolongation of tumor-free survival and a reduction of tumor multiplicity. In addition, CUR administration was safe, since no modification of hematological and clinical chemistry parameters could be observed in BALB-neuT and BALB/c mice treated with this compound for several weeks. These findings support further studies on the therapeutic potential of CUR in combination with standard therapies in breast cancer patients.

A common repertoire of autoantibodies is shared by cancer and autoimmune disease patients: Inflammation in their induction and impact on tumor growth.

The repertoire of autoantibodies found in cancer patients partly overlaps with that typical of patients with autoimmune diseases. Beside the biochemical and immunological properties of the target antigens and their altered expression in tumor tissues, the intratumoral inflammatory context can play a key role in the induction of autoimmune disease-associated autoantibodies in cancer patients. Furthermore, the impact of such antibodies on cancer growth and progression can be deeply influenced by the interplay with inflammation. The characterization of the spontaneous humoral responses occurring in cancer patients, of the mechanisms that trigger and sustain the autoantibody response and of the biological effects of such autoantibodies may help the rational design of anti-cancer immunotherapeutic protocols.

Immunity to extracellular matrix antigens is associated with ultrastructural alterations of the stroma and stratified epithelium basement membrane in the skin of Hashimotos thyroiditis patients.

Employing purified extracellular matrix (ECM) proteins, i.e. type I, III, IV and V collagens (CI, CIII, CIV, CV), laminin (LM) and fibronectin (FN), as antigen sources we detected autoantibodies to conformational and/or denatured ECM antigens among 34 of 50 sera obtained from Hashimotos thyroiditis (HT) patients and 6 of 51 control sera obtained from non-autoimmune thyroid disease patients and healthy donors (HT sera vs. control sera p=4 x 10-9). Reactivity to conformational antigens, mostly due to autoantibodies of the IgG isotype, was observed in 30/50 HT sera and in 6/51 control sera (p=3.5 x 10-7) and was not always concomitant with that to linear antigens, found in 23/50 HT and in 6/51 control sera (p=1.6 x 10-4). Ultrastructural analysis of skin biopsies obtained from 18 HT patients without symptomatic cutaneous diseases revealed defects of the stratified squamous epithelium basement membrane in 11/18, alterations of the stroma in 13/18 and both basement membrane and stromal defects in 9/18. Interestingly, 13/13 (p=0.012) and 9/11 (p=0.012) patients with stromal and basement membrane defects respectively, exhibited serum antibodies to at least one ECM antigen involved in the organization of the altered tissue compartment. Lastly, 10/18 skin biopsies presented immunoglobulin (Ig) and/or complement (C3) deposits along the cutaneous basement membrane zone (BMZ) or in the papillary dermis and 9/10 sera from the same patients simultaneously showed antibodies to at least one ECM antigen involved in the organization of these two skin compartments. Besides, 8/11 HT patients with basement membrane defects exhibited Ig or C3 deposits along the BMZ. Our findings suggest that autoantibodies to ECM molecules might contribute to the development of asymptomatic extra-thyroid skin diseases in HT patients.

Type I consensus IFN (IFN-con1) gene transfer into KSHV/HHV-8-infected BCBL-1 cells causes inhibition of viral lytic cycle activation via induction of apoptosis and abrogates tumorigenicity in sCID mice.

In this study, we investigated the effects of human type I consensus interferon (IFN-con1) (Amgen) gene transfer into body cavity-based lymphomas (BCBL)-1 cells, which are latently infected with Kaposi's sarcoma-associated herpesvirus (KSHV) human herpesvirus-8 (HHV-8). Both the basal and 12-O-tetradecanoyl phorbol-13-acetate (TPA)-stimulated production of KSHV/HHV-8 mature virions was strongly inhibited in genetically modified IFN-producing BCBL-1 cells as compared with parental or control transduced counterparts. A similar inhibition was obtained on treatment of parental BCBL-1 cells with exogenous IFN-con1. The reduction in KSHV/HHV-8 production was associated with a decrease in the basal and TPA-stimulated intracellular amount of the linear form of the viral genome. Interestingly, 25%40% of the IFN-producing BCBL-1 cell population underwent spontaneous apoptosis in vitro. TPA treatment, which did not significantly affect the viability of the parental and control BCBL-1 cells, resulted in the apoptotic death of up to 70% of the IFN-producing cell population. Addition of exogenous IFN-con1 to parental BCBL-1 cells produced similar effects, although less intense. Injection of either parental or control-transduced BCBL-1 cells into SCID mice resulted in progressively growing tumors characterized by an unusually high level of tumor angiogenesis. In contrast, complete tumor regression was observed in all the mice injected either subcutaneously (s.c.) or intraperitoneally (i.p.) with the IFN-producing BCBL-1 cells. These results represent the first evidence that type I IFN can counteract the activation of a productive herpesvirus infection in latently infected tumor cells by the induction of apoptosis, providing an interesting link between the antiviral and antitumor activities of this cytokine. These data suggest the possible advantages of strategies of type I IFN gene transfer (with respect to the use of the exogenous cytokine) for the treatment of patients with some HHV-8-induced malignancies.

The ras suppressor, RSU-1, enhances nerve growth factor-induced differentiation of PC12 cells and induces p21CIP expression.

The Rsu-1 Ras suppressor gene was isolated based on its ability to inhibit v-Ras transformation. Using Rsu-1 transfectants of the pheochromocytoma cell line PC12, we demonstrated previously that Rsu-1 expression inhibited Jun kinase activation but enhanced Erk2 activation in response to epidermal growth factor. In the present study, the Rsu-1 PC12 transfectants were used to investigate the role of Rsu-1 in nerve growth factor (NGF)- and v-Ki-ras-mediated neuronal differentiation. NGF-induced neurite extension was enhanced, not inhibited, by the expression of Rsu-1 in PC12 cells. The activation of Erk kinase activity in response to NGF was sustained longer in the Rsu-1 transfectants compared with the vector control cells. During NGF-mediated differentiation, an increase in the expression of specific mRNAs for the early response genes Fos, cJun, and NGF1a was detected in both the vector control and Rsu-1 transfectants. The expression of the differentiation-specific genes VGF8 and SCG10 was similar in Rsu-1 transfectants compared with the vector control cells. The induction of Rsu-1 expression in these cell lines did not inhibit v-Ki-ras-induced differentiation, as measured by neurite extension. These data suggest that although Rsu-1 blocked some Ras-dependent response(s), these responses were not required for differentiation. Moreover, the induction of Rsu-1 expression in the PC12 clones resulted in growth inhibition and p21(WAF/CIP) expression. Hence, Rsu-1 expression enhances NGF-induced differentiation while inhibiting the growth of cells.

Suppression of src-induced transformed phenotype by expression of tropomyosin-1.

Suppression of high M(r) tropomyosins (TMs) is a common feature of transformed cells. Previous work from this laboratory has demonstrated that the isoform 1 of TM, TM1, acts as an anti-oncogene in ras-transformed murine fibroblasts. In this study, we have investigated whether TM1 is a ras-specific suppressor, or a general suppressor protein of the cellular transformation. V-src transformed fibroblasts, which express decreased TM1, were transduced with a full-length cDNA to overexpress TM1. Both the control and the transduced cells expressed v-src kinase at comparable levels. TM1 expressing (src-T1) cells grew at a lower rate in monolayer, exhibited well spread, flat morphology than the control cells. Enhanced expression of TM1 resulted in improved microfilamental architecture. More significantly, src-T1 cells completely failed to grow under anchorage independent conditions. These data demonstrate that TM1 is as an anti-oncogene of functionally diverse oncogenes, and it is a class II tumor suppressor protein.

Immune responses to all ErbB family receptors detectable in serum of cancer patients.

Employing NIH3T3 transfectants with individual human ErbB receptor coding sequences as recombinant antigen sources, we detected by immunoblot analysis specific immunoreactivity against all four ErbB receptors among 13 of 41 sera obtained from patients with different types of epithelial malignancies. Overall, serum positivity was most frequently directed against ErbB2 followed by EGFR, ErbB3 and ErbB4. Specificity patterns comprised tumor patients with unique serum reactivity against ErbB2 or ErbB4. Moreover, approximately half of the positive sera exhibited concomitant reactivity with multiple ErbB receptors including EGFR and ErbB2, EGFR and ErbB4, ErbB2 and ErbB3 or EGFR, ErbB2 and ErbB3. Serum reactivity was confirmed for the respective ErbB receptors expressed by human tumor cells and corroborated on receptor-specific immunoprecipitates. Positive sera contained ErbB-specific antibodies of the IgG isotype. Representative immunohistochemical analysis of tumor tissues suggested overexpression of ErbB receptors for which serum antibodies were detectable in five of six patients. These findings implicate multiple ErbB receptors including ErbB3 and ErbB4 in addition to EGFR and ErbB2 in primary human cancer. Heterogeneity of natural ErbB-specific responses in cancer patients warrants their evaluation in light of immunotherapeutic approaches targeting these receptors.

The use of a cationic liposome formulation (DOTAP) mixed with a recombinant tumor-associated antigen to induce immune responses and protective immunity in mice.

The cationic liposome DOTAP is a well-known transfection reagent. It has been manufactured and approved for clinical use, is readily available, and can be easily used as an adjuvant. These characteristics prompted us to investigate the effectiveness of DOTAP as an adjuvant to induce immune responses and protective immunity in mice using baculovirus-derived carcinoembryonic antigen (bV-CEA) as a model antigen. Two routes of administration and a dose-response study of bV-CEA were used in BALB/c mice to define the magnitude of the immune response as well as the most effective route of immunization. The results demonstrate differences in antibody titers, immunoglobulin (Ig)G isotype, and T-cell responses between the intravenous (i.v.) or subcutaneous (s.c.) route of immunization. The titer of the anti-CEA antibodies induced by the s.c. immunization was greater than the response by i.v. immunization. The s.c. route enhanced the IgG2a/2b isotype, whereas i.v. immunization elicited primarily IgG1. T-cell proliferation responses and cytokine production paralleled the humoral response (i.e., production was higher in the s.c. immunized animals). No differences in immunological responses were seen using either 25 or 10 microg of bV-CEA three times. An amount of 25 microg of bV-CEA/DOTAP given by s.c. immunization was sufficient in protecting mice from the transplant of syngeneic tumor cells transduced with the human CEA gene. We conclude that the cationic liposome DOTAP may be a useful immunoadjuvant for active anti-tumor immunotherapy in future clinical trials. This study will help to define the most effective way to use such an adjuvant.

Increased expression of the Ras suppressor Rsu-1 enhances Erk-2 activation and inhibits Jun kinase activation.

Studies were undertaken to determine the effect of the Ras suppressor Rsu-1 on Ras signal transduction pathways in two different cell backgrounds. An expression vector containing the mouse rsu-1 cDNA under the control of a mouse mammary tumor virus promoter was introduced into NIH 3T3 cells and the pheochromocytoma cell line PC12. Cell lines developed in the NIH 3T3 background expressed p33rsu-1 at approximately twice the normal endogenous level. However, PC12 cell clones which expressed p33rsu-1 at an increased level in a regulatable fashion in response to dexamethasone were isolated. Analysis of proteins involved in regulation of Ras and responsive to Ras signal transduction revealed similar changes in the two cell backgrounds in the presence of elevated p33rsu-1. There was an increase in the level of SOS, the guanine nucleotide exchange factor, and an increase in the percentage of GTP-bound Ras. In addition, there was an increase in the amount of p120 Ras-specific GTPase-activating protein (GAP) and GAP-associated p190. However, a decrease in Ras GTPase-activating activity was detected in lysates of the Rsu-1 transfectants, and immunoprecipitated p120 GAP from the Rsu-1 transfectants showed less Ras GTPase-activating activity than GAP from control cells. Activation of Erk-2 kinase by growth factor and tetradecanyol phorbol acetate was greater in the Rsu-1 transfectants than in control cells. However, c-Jun amino-terminal kinase activity (Jun kinase) was not activatable by epidermal growth factor in Rsu-1 PC12 cell transfectants, in contrast to the PC12 vector control cell line. Transient expression of p33rsu-1 in Cos1 cells following cotransfection with either hemagglutinin-tagged Jun kinase or hemagglutinin-tagged Erk-2 revealed that Rsu-1 expression inhibited constitutive Jun kinase activity while enhancing Erk-2 activity. Detection of in vitro binding of Rsu-1 to Raf-1 suggested that in Rsu-1 transfectants, increased activation of the Raf-1 pathway occurred at the expense of activation of signal transduction leading to Jun kinase. These results indicate that inhibition of Jun kinase activation was sufficient to inhibit Ras transformation even in the presence of activated Erk-2.

Peptide-specific activation of cytolytic CD4+ T lymphocytes against tumor cells bearing mutated epitopes of K-ras p21.

Alterations in the ras p21 protein have been associated with both rodent and human neoplasia. Thus, mutated ras p21 proteins may bear unique antigenic epitopes for immune recognition, such as by T cells, which have been implicated in host antitumor activity. Synthetic peptides that mimic segments of mutated ras p21 have been reported to be immunogenic in mice in vivo, although detailed functional analyses remains undefined. Here, in a murine model, we explored and characterized distinct effector properties of host-derived T lymphocytes reactive to mutated ras peptides, which was consistent with the CD4+ T helper type 1 (Th1) subset. BALB/c mice (H-2d) were immunized with a purified peptide, 13 amino acids in length, containing the substitution of Gly (G12) to Val (V12) at position 12, which is commonly found in human carcinomas. An alpha beta T cell receptor-positive, CD3+, CD4+, CD8- T cell line was established, which expressed peptide-specific proliferation. Cytokine assays revealed the production of interleukin-2, interferon-gamma, tumor necrosis factor and granulocyte-macrophage colony-stimulating factor. Moreover, antigen-specific cytotoxicity was demonstrable against: (1) Iad-bearing A20 tumor cells incubated with exogenously bound V12 peptide; and (2) A20 tumor cells transduced with the K-ras p21 oncogene encoding the corresponding point mutation. CD4(+)-mediated cytotoxicity was major histocompatibility complex (MHC) class II-restricted, as revealed by the absence of lysis against MHC class II- P815 targets, inhibition of A20 lysis with anti-Iad monoclonal antibodies, and induction of lysis against L cell targets transfected with E alpha A beta d. Independent isolation of a second CD4+ V12 line revealed a very similar cytolytic and MHC class II-restricted profile. Overall, these data demonstrated that peptide immunization produced a CD4+ Th1 response that specifically recognized tumor cells expressing endogenous activated K-ras epitopes, which may have implications for the development of peptide-based active immunotherapies.

The Ras suppressor RSU-1 localizes to 10p13 and its expression in the U251 glioblastoma cell line correlates with a decrease in growth rate and tumorigenic potential.

Rsu-1, which was isolated based on its ability to suppress transformation by v-Ras, is a highly conserved gene which shares homology with yeast adenylyl cyclase in the region required for activation by Ras. Genomic DNA clones of human RSU-1 have been isolated and used as a probe for fluorescence in situ hybridization (FISH) to assign RSU-1 to 10p13, confirming the previous results of somatic cell hybrid mapping localizing RSU-1 to chromosome 10. Screening of more than 20 human tumor cell lines for RSU-1 expression revealed that most cell lines contained abundant RSU-1 RNA and protein. However, the p33 RSU-1 protein was undetectable in the U251 glioblastoma cell line and transfection of a rsu-1 expression vector into U251 cells yielded a cell line in which rsu-1 was under the control of a regulatable metallothionein promoter. Addition of Cd2+ to the U251-Rsu-1 transfectant resulted in transcription of rsu-1 RNA and the accumulation of p33 Rsu-1 protein. Appearance of the Rsu-1 protein correlated with a reduction in growth rate of the U251-Rsu-1 transfectant. In addition, reduction in anchorage independent growth and phenotypic alteration in U251-Rsu-1 transfectant agar colonies was observed. Two U251-Rsu-1 transfectant cell lines were non tumorigenic when injected subcutaneously into athymic nude mice. These results, in conjunction with the frequent deletions observed in chromosome 10 in glioblastomas, suggest that RSU-1 loss of function may play a role in the progression of this disease.

Ultrastructural evidence of the mechanisms responsible for interleukin-4-activated rejection of a spontaneous murine adenocarcinoma.

The ultrastructural pattern of the anti-tumor response elicited by interleukin-4 (IL-4) was investigated by using a spontaneous mammary adenocarcinoma (TS/A) unable to elicit protective immunity in syngeneic BALB/c mice as suggested by a variety of preimmunization-challenge experiments. A subcutaneous lethal challenge of TS/A tumor cells was inhibited in a significant number of BALB/c mice receiving recombinant murine IL-4 injected daily for 10 days around the tumor-draining lymph node. Tumor rejection was mainly the result of direct membrane and cytoplasmic damage to tumor cells by eosinophils, neutrophils and macrophages that deeply penetrated the proliferating tumor mass. Lymphocytes and fibroblasts participated in the reaction by interacting with tumor cells, granulocytes and each other. The most frequent cell interactions in the peri- and intra-tumoral areas and in the tumor-draining lymph nodes are illustrated. The efficiency with which the IL-4-activated reaction leads to tumor inhibition and induction of a T-lymphocyte-dependent tumor-specific immune memory appears to depend on interactions between distinct leukocytes.

Selective transformation of host lymphocytes in vivo by retrovirus-producing macrophages.

Macrophage-mediated retroviral transformation of host cells was studied in vivo utilizing the cloned murine macrophage-line GG2EE, generated by in vitro infection of bone marrow cells from C3H/HeJ mice (H-2k) with the acute transforming retrovirus J2 bearing the v-myc and v-raf oncogenes. Because GG2EE macrophages produce the J2 retrovirus, the development of secondary, J2 virus-induced tumors after the injection of the cell line into several strains of mice was evaluated. GG2EE cells proliferated and gave rise to histiocytic tumors in syngeneic mice and in allogeneic athymic Swiss mice. The inoculum of GG2EE cells in allogeneic DBA/2 mice (H-2d) and, to a lesser extent, in BALB/c (H-2d) and BALB/k (H-2k) mice gave rise to a small, solid mass at the injection site. Although the initial tumor was slowly rejected, secondary lymphomas belonging to the B or T cell lineage developed, leading to mouse death. Extensive phenotypic, functional, and chromosomal analyses proved that lymphomas were derived from host T and B cell transformation. Southern and Northern blot studies showed that J2 virus was integrated and expressed in lymphoma cells, demonstrating that the virus was transmitted to the host lymphocytes and suggesting that it was causal in lymphoma development. The existence of close and protracted interactions between GG2EE macrophages and allogeneic host lymphocytes and the presence of viral particles in the area of macrophage-lymphocyte contact were demonstrated by histologic and ultrastructural analysis. Rejection of J2 virus-infected lymphocytes in allogeneic mice suggested that host lymphocyte transformation was dependent upon the macrophage cell type. These results demonstrate that macrophage-derived J2 retrovirus transforms host lymphocytes in vivo in allogeneic mice and that a condition of host alloreactivity is critical for such event.

Modulation of laminin synthesis in human neuroblastoma cells during retinoic acid induced differentiation.

A comparable pattern of morphological neuronal differentiation was induced in the human neuroblastoma cell line SMS-KCNR by treatment with either retinoic acid (RA) or exogenous laminin (LM). LM expression and synthesis by SMS-KCNR was increased upon RA treatment which involved the cell bound, rather than the secreted protein. These data suggest an involvement of LM in the neuroblastoma differentiation process manifested both as an ability of LM to induce a morphological neuronal differentiation and as a selective control on LM metabolism during RA induced neuronal differentiation.

Human immunodeficiency virus (HIV)-infected tumor xenografts as an in vivo model for antiviral therapy: role of alpha/beta interferon in restriction of tumor growth in nude mice injected with HIV-infected U937 tumor cells.

The host factors involved in the restriction of tumor growth were studied in nude mice transplanted with a cloned line of chronically human immunodeficiency virus (HIV)-infected U937 cells. HIV-infected and uninfected U937 cells exhibited the same growth patterns in culture. However, HIV-infected cells were not tumorigenic when injected subcutaneously in nude mice, whereas large solid tumors were observed in mice injected with uninfected U937 cells. Injection of nude mice with antibody to alpha/beta interferon (IFN-alpha/beta) enabled HIV-infected U937 cells to grow progressively in approximately 90 to 100% of mice. HIV-infected U937 cells formed solid tumors in the majority (60 to 90%) of either immunosuppressed (splenectomized, irradiated, and anti-asialo-GM1-treated) or genetically immunodeficient (bg/nu/xid) nude mice. In mice treated with antibodies to IFN-alpha/beta with established HIV-positive tumors, a direct correlation was found between p24 antigenemia and tumor size. Treatment of established HIV-positive U937 cell tumors with human IFN-alpha or mouse IFN-alpha/beta resulted in a clear-cut inhibition of both tumor growth and p24 HIV antigenemia. In contrast, treatment with tumor necrosis factor alpha markedly inhibited tumor growth but did not significantly decrease serum p24 levels. 3'-Azido-3'-deoxythymidine treatment did not affect either tumor growth or the levels of serum p24 antigen. These data indicate that endogenous IFN-alpha/beta is a crucial factor in the restriction of both tumor growth and p24 antigenemia in mice injected with HIV-infected tumor cells. Moreover, the results suggest that the development of HIV-1 p24 antigenemia in athymic immunosuppressed mice may represent an interesting in vivo model for anti-HIV therapy.

Low doses of IL-4 injected perilymphatically in tumor-bearing mice inhibit the growth of poorly and apparently nonimmunogenic tumors and induce a tumor-specific immune memory.

The ability of rIL-4 to trigger host reactivity against both a chemically induced fibrosarcoma (CE-2) and a spontaneous adenocarcinoma (TS/A) of BALB/c mice was studied. Daily local s.c. administration around tumor draining lymph nodes of 10 injections of progressive amounts (0.00001 to 1000 pg/day) of rIL-4 induced appreciable inhibition of the growth of both tumors after a dose-response survival curve peaking at 0.1 pg/day. Inasmuch as rIL-4 has no direct antitumor activity, as shown by in vitro tests, host immune reactivity plays a fundamental role in this lymphokine activated tumor inhibition (LATI). LATI, in fact, is abolished when recipient mice are sublethally irradiated or treated with cyclosporin A, or when the reactivity of CD4+ lymphocytes is suppressed, whereas it is not affected by anti-asialo GM1 antibody. The morphologic data show that rIL-4 LATI rests on the recruitment of several cell reaction mechanisms, among which those that are nonspecific seem to predominate. rIL-4 LATI also leads to a state of long lasting and specific immune memory: the growth of a second contralateral tumor challenge is significantly impaired after LATI. This immune memory takes place after LATI of both the poorly immunogenic CE-2 fibrosarcoma and the TS/A adenocarcinoma, previously classed as nonimmunogenic on the basis of immunization-protection tests. In the latter case, adoptive transfer experiments show that Thy-1+ lymphocytes and, in particular, the CD4 cell-depleted T lymphocyte subpopulation, are responsible for the immune memory. Finally, the ability of rIL-4 to trigger LATI is greater than that of the most effective doses of rIL-2, rIL-1 beta, and IFN-gamma, whereas its association with rIL-1 beta induces a more effective immune memory.