A venetoclax and azacitidine bridge-to-transplant strategy for NPM1-mutated acute myeloid leukaemia in molecular failure.

NPM1-mutated acute myeloid leukaemia (NPM1mut AML) represents a mostly favourable/intermediate risk disease that benefits from allogeneic haematopoietic stem cell transplantation (HSCT) in case of measurable residual disease (MRD) relapse or persistence after induction chemotherapy. Although the negative prognostic role of pre-HSCT MRD is established, no recommendations are available for the management of peri-transplant molecular failure (MF). Based on the efficacy data of venetoclax (VEN)-based treatment in NPM1mut AML older patients, we retrospectively analysed the off-label combination of VEN plus azacitidine (AZA) as bridge-to-transplant strategy in 11 NPM1mut MRD-positive fit AML patients. Patients were in MRD-positive complete remission (CRMRDpos ) at the time of treatment: nine in molecular relapse and two in molecular persistence. After a median number of two cycles (range 1-4) of VEN-AZA, 9/11 (81.8%) achieved CRMRD -negative (CRMRDneg ). All 11 patients proceeded to HSCT. With a median follow-up from treatment start of 26 months, and a median post-HSCT follow-up of 19 months, 10/11 patients are alive (1 died from non-relapse mortality), and 9/10 patients are in MRDneg status. This patient series highlights the efficacy and safety of VEN-AZA to prevent overt relapse, achieve deep responses and preserve patient fitness before HSCT, in patients with NPM1mut AML in MF.

Lymphocyte transformation and autoimmune disorders.

The many features that link autoimmune disorders (AD) and lymphoma are reviewed herein. Firstly, the epidemiology indicates the increased risk of non-Hodgkin's lymphoma (NHL) development in many AD, and especially in Sjögren's syndrome, rheumatoid arthritis and systemic lupus erythematosus. In these AD, the relative risk of NHL occurrence varies between 2 and 4 up to 40 fold higher than in the general population, according to various surveys. Factors favouring or predicting NHL have been reported in detail. B-cell activation and proliferation are part of AD and are essential factors for the onset of malignant cell clones in a deregulated immunological environment. Targeting deregulated or malignant B-cells is the goal of some newly developed treatments. The prototype is anti-CD20 rituximab that has substantially modified the prognosis of B-cell NHL and is also an effective new treatment opportunity for some AD. Similarly, intensified treatments with autologous haematopoietic stem cell transplant (ASCT) that were developed for high-risk lymphoma are now under advanced investigation for use in some refractory AD. Thus, the successful use of rituximab and ASCT in both AD and NHL further emphasizes the close link between these two entities. This review provides details on the main epidemiological features regarding NHL incidence in AD, the pathogenetic factors that favour lymphoma onset and some recent advances in therapeutic approaches that are effective in both autoimmune and malignant lymphoproliferative disorders.

Cytokine induced killer cells as adoptive immunotherapy strategy to augment graft versus tumor after hematopoietic cell transplantation.

Donor lymphocyte infusion (DLI) is used to increase the graft versus tumor (GVT) effect after allogeneic hematopoietic cell transplant (HCT). The limited spectrum of activity and high risk of graft versus host disease (GVHD) remain major limitations of this approach. The finding of new cell populations for adoptive immunotherapy, with the ability to separate GVT from GVHD, would be useful. Here we review the main basic, preclinical and clinical research on cytokine-induced killer (CIK) cells, highlighting the aspects of their antitumor and alloreactive potentials that might favourably affect the balance between GVT and GVHD. CIK cells are ex vivo-expanded T lymphocytes sharing NK markers and endowed with a potent MHC-unrestricted antitumor activity against haematological and solid malignancies. Studies in preclinical animal models have demonstrated their low GVHD potential when infused across MHC-barriers, and recent clinical studies seem to confirm these findings in patients with hematological malignancies relapsing after HCT. If consolidated with larger clinical trials, adoptive immunotherapy with CIK cells might represent an effective alternative to classic DLI, helping HCT to succesfully meet current challenges like the extension across major HLA-barriers and application to solid tumors.

Degradation of pyrimethanil in soil: influence of light, oxygen, and microbial activity.

The research was carried out in order to verify the influence that light, oxygen, and microbial activity have on the degradability of pyrimethanil (PYR) in soil. The products of degradation were also identified and their evolution in time evaluated. The results indicate that the molecule is more persistent in the absence of light, oxygen, and microbial activity. The order of importance of these three factors is as follows: light < microbial activity < oxygen. The following products of degradation were identified: (1) benzoic acid, (2) cis,cis-muconic acid, (3) hydroxyl-4,6-dimethyl-2-pirimidinamine, (4) N'-ethyl-N-hydroxyformamidine, and (5) 4,6-dimethyl-2-piridinamine, which appeared different from those reported in literature for the degradation of PYR in abiotic conditions. This result suggests that the degradation in soil is mainly biotic.

Influence of soil organic matter on the leaching of polycyclic aromatic hydrocarbons in soil.

Polycyclic aromatic hydrocarbons (PAHs) are one of the main classes of contaminants in the terrestrial environment. Aside from total organic carbon, the ratio among the different organic matter fractions [dissolved organic matter, fulvic acid (FA), humic acid (HA) and humin] can also affect the mobility of these hydrocarbons in soils. In this study the effect of the whole organic carbon pool has been compared with that of HA and FA on the translocation of four PAHs (biphenyl, fluorene, phenanthrene and pyrene) in soil columns. Oxidized and untreated soil columns with and without HA or FA, were prepared, spilled with hydrocarbons and leached with a 0.01 M CaCl2 solution. The influence of HA and FA on PAH translocation was investigated through determinations of the PAH contents and total organic carbon (TOC) in the layers of the columns. All molecules were moved vertically by the percolating solutions, their concentrations decreasing with depths. The nonoxidized soil tended to retain more PAHs (96%) than the oxidized one (60%), confirming that organic matter plays an important role in controlling PAH leaching. The whole organic matter pool reduced the translocation of pollutants downward the profile. The addition of HA enhanced this behaviour by increasing the PAH retention in the top layers (7.55 mg and 4.00 mg in the top two layers, respectively) while FA increased their mobility (only 2.30 and 2.90 mg of PAHs were found in the top layers) and favoured leaching. In fact, in the presence of HA alone, the higher amounts of PAHs retained at the surface and the good correlation (r2=0.936) between TOC and hydrocarbon distribution can be attributed to a parallel distribution of PAHs and HA, while in the presence of FA, the higher mobility of PAHs can be attributed to the high mobility of the humic material, as expected by its extensive hydrophilic characteristics.

Liquid chromatographic determination of triasulfuron in soil.

Two extraction methods were developed for the determination of triasulfuron in soil. Method I included extraction with methanol-phosphate buffer at pH 7 (2 + 1, v/v), liquid-liquid partition with dichloromethane, and cleanup on a liquid chromatographic Si adsorption solid-phase extraction tube. In Method II, Extrelut was added and the sample was then extracted with acetonitrile. In both cases, the extracts were analyzed by liquid chromatography (LC) with UV detection and the LC peak was confirmed by LC/mass spectrometry (MS). The 2 methods were tested on 3 soils having different physicochemical characteristics. Method I gave 83% average recovery and a determination limit of 0.4 microg/kg soil. Method II gave 67% average recovery and a determination limit of 2 microg/kg soil. Examples of application of Method I to field samples are reported.

Interleukin-2 gene-transduced human leukemic cells induce major histocompatibility complex-restricted and -unrestricted anti-leukemic effectors in mixed lymphocyte-tumor cultures.

To explore the feasibility of designing vaccination protocols in acute leukemia patients with cytokine gene-transduced leukemic cells, we studied in vitro the growth potential of human leukemic cells transduced with the interleukin-2 (IL-2), IL-7, or IL-7 plus IL-2 genes, as well as the capacity of generating both autologous and allogeneic cytotoxic lymphocytes directed against the parental cells. A lymphoblastic T-cell line, ST4, obtained from a patient in long-lasting complete remission, was retrovirally engineered with the IL-2, IL-7, and IL-7 plus IL-2 genes; in addition, clones releasing different amounts of the cytokines were obtained by limiting dilution. Mixed lymphocyte-tumor cultures (MLTCs) were set up with parental or transduced leukemic cells as stimulators and with autologous or allogeneic lymphocytes as responders. When nonirradiated ST4 parental cells or clones producing <50 international units (IU)/mL/10(6) cells/72 hours of IL-2 were used as stimulators, leukemic overgrowth was observed in MLTCs within 16 days of culture. When clones producing >80 IU/mL/10(6) cells/72 hours of IL-2 were used as stimulators, the proliferation of leukemic cells was blocked and the transduced leukemic cells were completely cleared from the cultures by day 16; repeated restimulations with IL-2-producing leukemic cells were required to sustain long-term lymphocyte survival. On the contrary, when IL-7- or IL-7-IL-2-producing cells were used as stimulators, only a delay in leukemic cell overgrowth was observed, and lymphocytes were completely cleared from the cultures after day 60. IL-7 production by the different clones ranged between 11 and 36 ng/mL/10(6) cells/72 hours, whereas the highest IL-2-producing IL-7-IL-2 clone released 50 IU/mL/10(6) cells/72 hours of IL-2. When the stimulator efficacy of the highest IL-2-producing clone (ST4/IL-2#A7) was compared with that of exogenous IL-2 plus parental cells, a 7-fold higher amount of exogenous IL-2 was required to achieve the same results obtained with IL-2-producing leukemic cells. Autologous and allogeneic long-term MLTCs (up to 35 days) with ST4/IL-2#A7 as the stimulator were capable of generating cytotoxic effectors equally endowed with both major histocompatibility complex (MHC) class I-unrestricted and -restricted activity against parental ST4 cells. By day 18 of both autologous and allogeneic cultures, a substantial proportion of CD56+ cells was consistently recorded; this was coupled to a predominantly MHC-unrestricted cytotoxic activity directed against parental ST4 cells. CD56+ cells decreased considerably at the end of the different MLTCs, together with the unrestricted cytotoxic activity. At this time, >50% of the cells were CD8+, and 55% of the activity could be blocked by an anti-MHC class I monoclonal antibody. The results of this study demonstrate that IL-2 gene-transduced human acute leukemia cells cocultured with both autologous and allogeneic lymphocytes are capable of inducing a strong MHC-unrestricted anti-leukemic activity and subsequently "educating" MHC class I-restricted anti-leukemic effectors. The evidence that the immunogenic potential of human leukemic blasts can be boosted after transfer of the IL-2 gene suggests that the possibility of using leukemic cells engineered to release IL-2 as a therapeutic vaccine needs to be explored further.

Chronic myeloid leukemia cells resistant to interferon-alpha lack STAT1 expression.

INTRODUCTION: Interferon-alpha (IFN) plays a role in the management of different neoplasias, particularly those of hematological origin. The mechanisms of action of IFN are still poorly understood and the individual response is unpredictable. In the present study, the pattern of intracellular gene expression following in vitro and in vivo exposure of chronic myeloid leukemia (CML) cells to IFN was evaluated and correlated with the response to in vivo treatment with IFN. MATERIALS AND METHODS: CML patients in different phases of the disease were studied. The pattern of expression of two IFN-inducible proteins involved in IFN-mediated biological activities, the p91 and p84 proteins (STAT1alpha and STAT1beta), components of the IFN-stimulated gene factor 3 (ISGF3) complex and the enzyme 2'-5' oligoadenylate synthetase (2'-5' OASE) were investigated by Western blot in peripheral blood mononuclear cells stimulated or not in vitro by IFN. RESULTS AND CONCLUSIONS: In 6/9 patients evaluated before starting treatment, STAT1 was expressed either constitutively or after in vitro stimulation by IFN. In three cases, STAT1 remained negative even after in vitro activation. The pattern of protein expression correlated with the subsequent hematological response to prolonged in vivo IFN administration: the presence of STAT1 being associated with the clinical response to IFN and the absence and non-inducibility of STAT1 with resistance to IFN. This was further substantiated by studies carried out in ten patients analyzed at the time of a documented clinico-hematological response or resistance to the in vivo administration of IFN. Finally, in order to establish whether the pattern of response to IFN treatment could be predicted at diagnosis, cells cyropreserved at diagnosis from patients with a documented complete response, confirmed also by cytogenetic negativity, or resistance, were studied. While complete responders proved STAT1 positive, none of the four resistant cases ever expressed STAT1. The expression of 2'-5' OASE did not correlate with the clinical response to IFN. This study documents the pivotal role of STAT1 in the in vitro and in vivo responses of CML cells to IFN. The constitutive or induced presence or absence of STAT1 shows a predictive correlation with the response or resistance to treatment with IFN and could be utilized to identify, at diagnosis, resistant patients who may be spared an expensive and unnecessary prolonged IFN administration.

CD34(+) acute myeloid and lymphoid leukemic blasts can be induced to differentiate into dendritic cells.

CD34(+) hematopoietic stem cells from normal individuals and from patients with chronic myelogenous leukemia can be induced to differentiate into dendritic cells (DC). The aim of the current study was to determine whether acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) cells could be induced to differentiate into DC. CD34(+) AML-M2 cells with chromosome 7 monosomy were cultured in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor alpha (TNFalpha), and interleukin-4 (IL-4). After 3 weeks of culture, 35% of the AML-M2 cells showed DC morphology and phenotype. The DC phenotype was defined as upmodulation of the costimulatory molecules CD80 and CD86 and the expression of CD1a or CD83. The leukemic nature of the DC was validated by detection of chromosome 7 monosomy in sorted DC populations by fluorescence in situ hybridization (FISH). CD34(+) leukemic cells from 2 B-ALL patients with the Philadelphia chromosome were similarly cultured, but in the presence of CD40-ligand and IL-4. After 4 days of culture, more than 58% of the ALL cells showed DC morphology and phenotype. The leukemic nature of the DC was validated by detection of the bcr-abl fusion gene in sorted DC populations by FISH. In functional studies, the leukemic DC were highly superior to the parental leukemic blasts for inducing allogeneic T-cell responses. Thus, CD34(+) AML and ALL cells can be induced to differentiate into leukemic DC with morphologic, phenotypic, and functional similarities to normal DC.

IL4 production and increased CD30 expression by a unique CD8+ T-cell subset in B-cell chronic lymphocytic leukaemia.

Phenotypic and functional abnormalities within the residual non-B-cell compartment of B-cell chronic lymphocytic leukaemia (CLL) suggest an interaction between tumour cells and host immune effectors. To explore the possibility of a polarized Th1/Th2 response we have studied CD30 antigen expression and the pattern of cytokine production by purified CLL T cells. Activated T cells from CLL patients showed a significant increase in the expression of CD30 compared to normal controls. Accordingly, high levels of soluble CD30 were detected in supernatants from activated T-cell cultures, as well as in CLL serum samples. Messenger RNA for IL4 was found in both resting and, to a greater extent, in activated CLL T lymphocytes. The latter cells were also capable of releasing IL4. Three-colour immunofluorescence analyses revealed a strong CD30 expression in the CD3+/CD8+/CD28- large granular lymphocyte subset, which is considerably expanded in CLL. Production of IL4, as well as expression and release of CD30 by these T cells, was conclusively demonstrated at the clonal level. These findings document an expansion of a peculiar subset of 'Th2-like' cells in CLL, with an increased IL4 production and CD30 expression and release, that are likely to contribute to both the B-cell accumulation and immune-defects characteristic of this disease.

Platelet-activating factor synthesized by IL-12-stimulated polymorphonuclear neutrophils and NK cells mediates chemotaxis.

IL-12 is chemotactic for NK cells and polymorphonuclear neutrophils (PMN), but not for monocytes. In the present study, we evaluated whether the chemotactic effect of IL-12 is a direct phenomenon or is dependent on the generation of secondary mediators. The results obtained indicate that IL-12 induces a dose- and time-dependent synthesis of platelet-activating factor (PAF) from PMN and NK cells and of reactive oxygen radicals (ROS) from PMN. Monocytes and CD56-negative PBMC cells did not synthesize PAF or ROS after challenge with IL-12. The production of ROS by PMN was significantly inhibited by two chemically different PAF receptor antagonists (WEB 2170 and CV 3988), suggesting an autocrine stimulation of PMN by PAF newly synthesized after the challenge with IL-12. Moreover, the IL-12-induced chemotaxis of PMN and NK cells was significantly reduced by both WEB 2170 and CV 3988, suggesting that synthesized PAF mediates the chemotactic effect of IL-12. Preincubation with superoxide dismutase, which blocks the formation of superoxide anions, also reduced the chemotactic effect of IL-12 on PMN, but not on NK cells, suggesting that superoxide anion generation is relevant only for the IL-12-induced chemotaxis of PMN. In conclusion, the results of the present study indicate that IL-12-induced PAF synthesis plays a critical role in triggering the events involved in the motogenic response of PMN and NK to IL-12.

Microsatellite analysis in childhood acute lymphoblastic leukemia.

BACKGROUND AND OBJECTIVE: Genetic alterations, including genomic instability, represent possible steps towards a malignant transformation. One approach to delineate replication errors in cancer cells is to determine alterations of microsatellites that are short tandem repeat sequences dispersed throughout the human genome. We have investigated whether genomic instability may be a possible event in the leukemogenic process by evaluating the pattern of instability in 41 cases of childhood acute lymphoblastic leukemia (ALL). MATERIALS AND METHODS: Eighty-two samples of genomic DNA (41 at diagnosis and 41 at remission) were analyzed by PCR with microsatellite markers chosen on five different chromosomes (2, 10, 11, 13, 18) known to be frequently involved in tumors of various origins. Since deletions of the short arm of chromosome 12 are relatively common in children with ALL, we also analyzed one region flanked by the microsatellite marker D12S308 on 12p. This area encompasses a genetic locus which contains the putative suppressor gene KIP1. RESULTS: A pattern of MI at one or two loci on different chromosomes could be documented in 4 of the 41 cases analyzed (9.7%). Three were common ALL and 1 was a T-ALL. One case showed two concomitant sites of instability, while 1 revealed two additional bands by using simultaneously microsatellite markers D2S123 and D18S58. INTERPRETATION AND CONCLUSIONS: These results indicate that genetic instability of microsatellite repeat sequences occurs in a proportion of childhood ALL. Mismatched repair errors documented in hereditary and sporadic solid tumors may thus be involved in hematological malignancies. While in such cases the pattern of genomic instability appears indicative of a mutator phenotype and of a potential predisposition towards a leukemic transformation, other genomic loci close to cytogenetic and molecular alterations known to occur in ALL need to be investigated in depth in cases with an apparently non mutated phenotype.

Control of the membrane sex hormone-binding globulin-receptor (SHBG-R) in MCF-7 cells: effect of locally produced SHBG.

The interaction between plasma sex hormone-binding globulin (SHBG) and its receptor (SHBG-R) inhibits estradiol-induced proliferation of MCF-7 cells (human estrogen-dependent breast cancer) through cAMP and PKA. Thus, SHBG can modulate estradiol action in breast cancer, but the implications of this require a more detailed knowledge of the SHBG-R. To this end, we have transfected MCF-7 cells with an expression vector carrying the human SHBG cDNA (S-MCF-7) and studied the effects of this on both SHBG-R binding and cell proliferation. Control cells were parental MCF-7 (P-MCF-7) and MCF-7 cells transfected with the beta-galactosidase gene (B-MCF-7). Transfections were mediated by lipofectin followed by selection of transfected cells with G418. The amounts of SHBG in culture medium were evaluated by IRMA assay, with only S-MCF-7 cells shown to secrete SHBG; SHBG-R levels were evaluated by tracer binding technique. In P-MCF-7 and B-MCF-7 cells, SHBG-R was detectable as a two-binding site receptor, but no binding of SHBG was observed in S-MCF-7 cells. Proliferation of cells treated with estradiol was evaluated by [3H]thymidine incorporation in the three cell lines and in cells pretreated with SHBG (1 nM) purified from human serum or with conditioned medium from S-MCF-7 cells (medium S). In all three lines, cell proliferation increased after estradiol treatment. Preincubation with purified SHBG was effective in reducing estrogen-induced cell proliferation to basal levels in P-MCF-7 and B-MCF-7 but not in S-MCF-7 cells. The estradiol effect was also inhibited in P-MCF-7 cells treated with medium S. In conclusion, 1) SHBG inhibits estradiol-induced proliferation in cells containing a functional SHBG-R, whereas it has no detectable effect in cells in which the SHBG-R is either absent or not available to bind SHBG; and 2) S-MCF-7 cells are insensitive to SHBG (locally produced or exogenous) because their SHBG-R is occupied by SHBG.

Cytotoxic effectors activated by low-dose IL-2 plus IL-12 lyse IL-2-resistant autologous acute myeloid leukaemia blasts.

We have investigated the susceptibility of primary acute myeloid leukaemia (AML) samples to the lytic action of normal peripheral blood mononuclear cells (PBMC), as well as of the patients' autologous and allogeneic PBMC collected at the time of remission following stimulation with different concentrations of interleukin (IL)-2 and IL-12, both alone and in variable combinations. Primary AML blasts were resistant to IL-2-activated PBMC effectors generated from normal individuals, allogeneic and autologous patients in five, six and eight of the 10 AML samples tested, respectively, IL-12 alone proved ineffective in generating anti-leukaemic activity, whereas, in combination, the two cytokines induced anti-leukaemic killing in all five cases resistant to normal PBMC, in 4/6 samples resistant to allogeneic AML effectors and in 5/8 cases resistant to autologous effectors. In each case the lytic effect was maintained at the lowest cytokine combination (10 + 10 IU/ml) utilized. The suggestion of a synergistic effect was further strengthened by the evidence that at the lowest doses of IL-2 and IL-12 the degree of killing was greater than that promoted by each cytokine independently. The results of this study suggest that two major limitations associated with the administration of IL-2 to AML patients, the resistance of the blasts to IL-2-generated killing and the toxicity associated with high-dose IL-2, may be overcome by the combined use of very low doses of IL-2 and IL-12. As IL-2-resistant blasts may be lysed by a low-dose combination of IL-2/IL-12, feasibility studies with this cytokine combination are worthy of exploration in vivo.

Transfer of the interleukin-2 gene into human cancer cells induces specific antitumor recognition and restores the expression of CD3/T-cell receptor associated signal transduction molecules.

Normal peripheral blood mononuclear cells (PBMC) were co-cultured with a human lung cancer cell line (LC89) transduced with the interleukin-2 (IL-2), IL-7, granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor-alpha (TNF-alpha) genes to evaluate the capacity of the engineered cells to: allow survival of CD3+ and CD56+ cells, generate cytotoxic effectors with HLA class I restricted and unrestricted antitumor activity, and interfere in the molecular organization of the CD3/T-cell receptor associated signal transduction machinery. When PBMC were cultured up to 3 weeks with IL-2 releasing LC89 cells (LC89/IL-2), the number of viable CD3+ and CD56+ lymphocytes was much greater than in cultures with parental cells or with LC89 cells transduced with the other cytokine genes. After 1 week of coculture, a variable degree of restricted and unrestricted killing directed against different targets was observed. When the cultures were prolonged up to 3 weeks, LC89/IL-2 cells induced a marked increase in specific cytotoxic activity, which was coupled to a further enhancement of unrestricted lytic function. In the presence of LC89/IL-7 cells the degree of specific lysis remained unchanged, whereas unrestricted effectors were markedly decreased. No cytotoxic activity could be induced by LC89/GM-CSF and LC89/TNF-alpha cells in the few lymphocytes surviving after 3 weeks of culture. Coculture of parental LC89 cells with PBMC was consistently associated with a downmodulation in the expression of the CD3 zeta chain, as well as of the tyrosine kinases p56ick and ZAP-70. On the contrary, LC89/IL-2 cells, and not LC89 cells transduced with the IL-7, GM-CSF, or TNF-alpha gene, were capable of reverting the immunosuppressive effect exerted by the tumor cells. This protective effect could be maintained in cultures prolonged up to 4 weeks. When the same cultures were set up in Transwell, ie, with a membrane separation between cancer cells and PBMC, the expression of the CD3 zeta chain and of the p56ick and ZAP-70 tyrosine kinases remained unchanged under all culture conditions, indicating that the downmodulation of T-cell signal transduction molecules requires a direct cell to cell contact. These results show that transfer of the IL-2 gene into the DNA of human cancer cells promotes both restricted and unrestricted antitumor activity, and is capable of restoring and maintaining the expression of molecules involved in the process of T-cell mediated tumor cell recognition, thus underlining the potential role of the IL-2 gene in the design of vaccination protocols with cytokine gene transduced cancer cells.

Retroviral vector-mediated transfer of the tumor necrosis factor alpha gene into human cancer cells restores an apoptotic cell death program and induces a bystander-killing effect.

Tumor necrosis factor alpha (TNFalpha) may induce tumor cell death by apoptosis, the physiologic program of cell death usually lost during neoplastic progression. However, many tumor cells are resistant to its effect unless high doses are administered. By retroviral vector-mediated gene transfer, we have transduced the TNFalpha gene into the DNA of human tumor cells to investigate whether the indefinite neoplastic cell proliferation could be blocked and the lost physiologic program of cell death restored. Evidence is provided that high-TNFalpha-producing clones generated from a human lymphoma T-cell line (ST4) can undergo apoptosis following transduction of the TNFalpha gene. Internucleosomal DNA cleavage was documented by May-Grünwald-Giemsa and by propidium iodide staining, as well as by gel electrophoresis. The induced apoptotic phenomenon is TNFalpha-mediated, since it can be reverted following incubation with anti-TNFalpha monoclonal antibodies (MoAbs), and it occurs with cytokine levels released in the supernatant by the engineered cells much lower(>100 times) than those required to promote the same effect on parental ST4 cells following administration of exogenous recombinant TNFalpha. The process is associated with a downregulation of the apoptosis-preventing gene, bcl-2, while the expression of bax and p53, genes usually involved in promoting apoptosis, persists. Mixed-culture experiments performed coincubating TNFalpha-transduced and untransduced ST4 cells allowed documentation of a bystander-killing effect on the parental cells. This phenomenon still occurred at transduced to parental cell ratios as low as 1:20 and was blocked in the presence of an anti-TNFalpha MoAb. These findings indicated that TNFalpha may play a regulatory role in the proliferation of human tumor cells, and suggest potential new antitumor therapeutic strategies based on the direct delivery of the TNFalpha gene into cancer cells.

Human lung carcinoma cells engineered to release IL2, IL7, GM-CSF and TNF alpha.

A human lung adenocarcinoma cell line (LC89) was transduced with the IL2, IL7, GM-CSF and TNF alpha genes by retroviral vector mediated infection. This induced the constitutive and stable release of all cytokines. No difference or modulation was found in the parental and gene transduced LC89 cells with regard to cytokine receptor expression, in vitro cell growth and proliferation, nor in cell surface expression of different adhesion molecules. Following injection into immunosuppressed nu/nu mice, IL2 gene transduced LC89 cells lost their tumorigenic potential. LC89 cells engineered to release IL7 and TNF alpha grew in nu/nu mice, but in 40% of the animals tumor regression was observed. GM-CSF gene transduced LC89 cells showed a tumorigenic capacity identical to that of the parental clone. The levels of TGF beta(1) released by IL2, IL7 and GM-CSF gene transduced LC89 cells were markedly reduced compared to those of the parental and TNF alpha gene transduced cells. The results of this study support the concept that human lung cancer cells engineered with different cytokine genes maintain their intrinsic morphologic and proliferative features, while their tumorigenic and immunosuppressive capacities can be profoundly down-modulated. Both these effects are optimally achieved following insertion of the IL2 gene, suggesting that vaccination protocols with IL2 gene transduced tumor cells may be considered for the management of human lung cancer.