Endovascular Repair of Juxtarenal and Pararenal Abdominal Aortic Aneurysms Using a Novel Low-Profile Fenestrated Custom-Made Endograft: Technical Details and Short-Term Outcomes

INTRODUCTION

The aim of this study is to share preliminary experiences and outcomes with a novel custom-made fenestrated TREO® Abdominal Stent-Graft System to treat juxtarenal and pararenal abdominal aortic aneurysms (AAAs).

METHODS

Juxtarenal and pararenal AAA patients treated with the custom-made fenestrated TREO® Abdominal Stent-Graft System were included from 4 high-volume European academic medical centers from June 2021 to September 2023. Technical success and 30-day/in-hospital mortality and complications were analyzed. Technical success was defined as successful endovascular implantation of the stent graft with preservation of antegrade flow to the target vessels, and absence of type 1 or 2 endoleak (EL) at the first postoperative computed tomography angiography (CTA).

RESULTS

Forty-two consecutive patients were included. The majority of the devices were constructed with 2 (N=4; 9.5%), 3 (N=9; 21.4%), or 4 (N=27; 64%) fenestrations. In 1 case, the device was constructed with a single fenestration (2.4%) and 1 device contained 5 fenestrations (2.4%); 17% had previous AAA repair. Target vessel cannulation with placement of a bridging stent was successful in all but 1 vessel (99, 3%). One aneurysm-related death occurred in the direct postoperative period and 2 limb occlusions necessitated reintervention during admission. In the median follow-up period of 101 (2-620) days, 3 more patients died due to non-aneurysm-related causes. Technical success was achieved in 90% of the cases. Nineteen ELs were seen on the first postoperative CT scan: 1 type 1b EL (N=1; 2%), 15 type 2 ELs (N=15; 36%), and 3 type 3 ELs (N=3%). Eleven patients received more than 1 CT scan during a median follow-up of 361 days (82-620): 3 type 2 ELs resolved and 1 type 3 EL was treated in this period. In the follow-up, 1 patient had a coagulation disorder that caused occlusions of the branches.

CONCLUSION

The results of the first experiences using the custom-made fenestrated TREO® Abdominal Stent-Graft System in Europe are promising. There was a low short-term mortality and morbidity rate in these patients of which 17% had previous AAA repair. Mid-term and long-term follow-up data are needed to evaluate endograft durability and performance.

CLINICAL IMPACT

This study shows the first experiences and short-term results of a novel low-profile custom-made device: the custom-made fenestrated TREO® Abdominal Stent-Graft System. Showing these results and experiences can help the physicians in clinical decision-making for their patients.

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.

Prolactin levels independently predict major cardiovascular events in patients with erectile dysfunction

The physiological role of prolactin (PRL) in men is not completely clarified. We previously reported that in subjects consulting for sexual dysfunction, lower PRL plasma levels were associated with worse lipid and glycaemic profile, as well as with a higher prevalence of metabolic syndrome and arteriogenic erectile dysfunction (ED). The aim of this study was to assess possible associations between PRL levels and incident major cardiovascular events (MACE) in subjects with ED. When only subjects without pathological hyperprolactinaemia (PRL < 735 mU/L or 35 ng/mL) and pituitary diseases were considered, both unadjusted and adjusted analyses showed a significantly lower incidence of MACE in subjects with PRL levels in the highest PRL quintile (246-735 mU/L or 12-35 ng/mL) when compared with the rest of the sample. In particular, the risk of MACE was reduced by 5% (1-9%; p = 0.03) for each 10 ng/mL increment of PRL. Conversely, comparing patients with hyperprolactinaemia with matched controls, no significant difference was detected between cases and controls in MACE. In subjects at high risk for cardiovascular diseases, such as those with ED, a relatively high PRL plasma level is associated with an overall decreased chance of MACE, independently from other known risk factors.

Differential activation of mitogen-activated protein kinase signalling pathways in the hippocampus of CRND8 transgenic mouse, a model of Alzheimer's disease

Transgenic Centre for Research in Neurodegenerative Diseases 8 (TgCRND8) mice expressing a double mutant form of human amyloid precursor protein represent a good model of Alzheimer's disease, and can be useful to clarify the involvement of mitogen-activated protein kinases (MAPK) dysregulation in the pathophysiology of this neurodegenerative disorder. Activation of extracellular regulated kinase (ERK) 1/2, jun kinase (JNK) and p38MAPK was studied in the hippocampus of 7-month-old TgCRND8 mice by immunohistochemistry and Western blot analysis using antibodies selective for the phosphorylated, and thus active, forms of the enzymes. We demonstrated that the three main MAPK pathways were differentially activated in cells of the hippocampus of TgCRND8 mice in comparison to wild type (Wt) littermates, p38MAPK and JNK being more activated, while ERK less activated. p38MAPK was significantly activated in microglia, astrocytes and neurons, around and distant from the plaques. JNK was highly activated in cells closely surrounding the plaques. No difference was observed in the activation of the two major bands of JNK, at a molecular weight of 46 kDa and 54 kDa. These data indicate the possible involvement of p38MAPK and JNK pathways dysregulation in the pathogenesis of Alzheimer's disease. The ERK2 isoform of the ERK pathway was less activated in the hippocampal dentate gyrus of Tg mice in basal conditions. Furthermore activation of the ERK pathway by ex vivo cholinergic stimulation with carbachol caused significantly higher activation of ERK in the hippocampus of Wt mice than in Tg mice. These findings may pose a molecular basis for the memory disruption of Alzheimer's disease, since proper functioning of the basal forebrain cholinergic neurons and of ERK2 is critical for memory formation.

Gene therapy in melanoma

The identification of genes involved in different biologic functions and in the pathogenesis of diseases has paved the way to the possibility of either interfering with the role of such genes or replacing them in somatic cells in case of loss, which may occur in some genetic diseases or cancer. Such progress has been accomplished thanks to advances in molecular biology and applied technology that allow the transport and insertion of genes into recipient cells by viral or physical vectors as well as the inhibition of gene transcription by antisense oligonucleotides. Methods have also been devised to transfer genes not only in vitro but also in vivo, although this latter approach is still limited owing to poor selectivity and targeting of most vectors when given systemically. Viral and physical vectors have been employed; each of these vectors has distinct advantages and disadvantages, and, therefore, the appropriate vector should be selected according to the therapeutic system involved (1). Retro viral vectors have been used largely for their ability to selectively transfect proliferating cells, a feature that can be advantageous in case one wishes to target only proliferating tumor cells. Owing to the heterogeneous proliferation rate in different parts of a tumor, however, it could be desirable, under some circumstances, to be able to target even the fraction of nonproliferating tumor cells. This can now be obtained by the use of lentivirus (2) or by switching to the use of adenoviruses that can target both dividing and quiescent cells but also induce unwanted inflammmatory reactions from the host.

Immunological gene therapy with ex vivo gene-modified tumor cells: a critique and a reappraisal

Studies using animal models have demonstrated that transduction of genes encoding different cytokines into tumor cells results in a local recruitment of inflammatory cells that in turn can inhibit tumor growth. This is often accompanied by tumor antigen priming of the host immune system, which becomes resistant to subsequent challenge by the parental, untransduced tumor. Gene-transduced tumor cells have therefore been widely used as vaccines, although in the therapeutic setting their antitumor efficacy was limited to a few animal models. On the basis of this rationale, clinical studies were initiated, results of which are evaluated in this review to identify the reasons for their limited efficacy. We point out problems generated by the use of autologous versus allogeneic gene-transduced vaccines, by the choice of the appropriate cytokine(s), and by patient selection. Results of these studies are also compared with those obtained by peptide-based vaccines in similar groups of patients. Altogether, we conclude that improvements can be made in the construction of gene-modified vaccines by (1) using tumor cells known to express molecularly defined antigens, (2) introducing, in addition to genes encoding cytokines, genes encoding T cell costimulatory molecules, (3) increasing the amount of cytokine released locally by irradiated cells, and (4) coadministering adjuvant cytokines (IL-2 and IL-12) systemically in order to expand the T cell pool activated by vaccines.

Nerve growth factor cooperates with p185(HER2) in activating growth of human breast carcinoma cells

Nerve growth factor (NGF) is known to exert a mitogenic effect on human breast cancer cells through proto-TrkA activation. Reverse transcriptase-PCR analysis of proto-TrkA expression in human breast carcinoma specimens and cell lines revealed trkA transcript in 12 of 14 human breast carcinoma specimens and in all of four cell lines tested. While cytofluorimetric and Western blot analysis indicated proto-TrkA expression in three of the four cell lines, NGF stimulated growth in only two of the three positive cell lines. Inhibition of NGF-induced MAPK activation by an antibody directed against the extracellular domain of TrkA but not by an inhibitor of TrkA phosphorylation demonstrated the requirement of NGF binding but not of proto-TrkA kinase activity for MAPK activation, suggesting the recruitment of another kinase for transmission of the mitogenic signaling. Indeed, NGF induced tyrosine phosphorylation and stimulated kinase activity of p185(HER2), a kinase receptor of the HER family. A TrkA phosphorylation inhibitor did not affect this activation. Moreover, the two receptors were coprecipitated by antibodies directed against proto-TrkA and p185(HER2). Down-modulation of p185(HER2) expression in a breast carcinoma line transfected with a construct containing an anti-p185(HER2) antibody sequence and expressing proto-TrkA impaired NGF-induced MAPK activation and proliferation. Together these data show that in cells expressing low levels of TrkA such as breast carcinoma cells, NGF must recruit other overexpressed receptors such as p185(HER2) in order to generate a biological signal that can induce breast cancer cell growth.

Vaccination of melanoma patients with interleukin 4 gene-transduced allogeneic melanoma cells

A human melanoma line genetically modified to release interleukin 4 (IL-4) was utilized to immunize advanced melanoma patients in order to elicit or increase a specific anti-melanoma immune response, which may affect distant lesions. Twelve metastatic melanoma patients were injected subcutaneously at least three times with 5 x 10(7) IL-4 gene-transduced and irradiated allogeneic melanoma cells per dose. Both systemic and local toxicities were mild, consisting of transient fever and erythema, swelling, and induration at the vaccination site. Two mixed but not complete or partial clinical responses were recorded. To assess the immune response of vaccinated patients, both serological and cell-mediated activities were evaluated. Antibodies to alloantigens could be detected in 2 of 11 patients tested. Mixed tumor-lymphocyte cultures were performed, utilizing autologous and allogeneic HLA-A2-matched melanoma lines as simulators and targets. A significant increase in IFN-gamma release was detected in 7 of 11 cases when postvaccination lymphocytes were stimulated by the untransduced allomelanoma cells. However, induction of a specific recognition of autologous melanoma cells by PBLs was obtained after vaccination in only one of six cases studied. This response involved the melanoma peptide Melan-A/MART-1(27-35) that was recognized in an HLA-A2-restricted fashion. These results indicate that vaccination with allogeneic melanoma cells releasing IL-4 locally can expand a T cell response against antigen(s) of autologous, untransduced tumor, although in a minority of patients.

DNA vaccination against the ovarian carcinoma-associated antigen folate receptor alpha (FRalpha) induces cytotoxic T lymphocyte and antibody responses in mice

Human folate receptor alpha (FRalpha) is a folate-binding protein that is selectively overexpressed in ovarian carcinoma and has been regarded as a suitable target antigen for immunotherapy purposes. To study the possible use of this antigen in DNA vaccination, FRalpha cDNA was ligated into the VR1012 (Vical) expression vector under the transcriptional control of the cytomegalovirus promoter. A total of 100 microg of purified plasmid DNA was injected intramuscularly in BALB/c mice three times at 14-day intervals. At 10 days after the second injection, the sera of the animals (100%) displayed significant antibody titers (by indirect immunofluorescence and fluorescence-activated cell sorter analysis) against syngeneic C26 cells transduced with FRalpha, but not against unmodified C26 cells. Immunoglobulin G2a was the predominant isotype. In addition, specific cytotoxic T lymphocyte activity against FRalpha-transduced C26 cells could be detected in splenocytes from all immunized animals. Coinjection of a plasmid containing interleukin-2 cDNA increased both antibody titers and cytotoxic T lymphocyte activity. Challenge by subcutaneous injection with FRalpha-transduced C26 cells (performed 10 days after the third injection) showed a statistically significant delay in tumor growth. Vaccination with the FRalpha and interleukin-2 cDNA mixture, which was performed after an intravenous injection of FRalpha-transduced cells, enhanced the mean survival time and reduced the number of lung metastases, thus suggesting that such vaccination is effective even against preexisting tumor cells.

Cytotoxic T lymphocyte response against non-immunoselected tumor antigens predicts the outcome of gene therapy with IL-12-transduced tumor cell vaccine

The colon adenocarcinoma C26, carrying two endogenous tumor-associated antigens (TAA) recognized by CTL, has been transduced with the gene coding for the human folate receptor alpha (FR alpha) as an additional antigen in order to study the efficacy of vaccination against a tumor expressing multiple antigens. A dicistronic vector was used to transduce the IL-12 genes to create C26/IL-12/FR alpha that has been used as a cellular vaccine to treat mice bearing lung metastases of C26/FR alpha. After vaccination mice were partially splenectomized and splenic lymphocytes frozen and used retrospectively to study in vitro CD8 T cell response related to the treatment outcome. Vaccination cured 50% of mice and the effect was CD8 T cell dependent. Mice either cured (responders) or not cured (nonresponders) by vaccination developed tumor-specific CTL. However, analysis of CTL specificity and pCTL frequencies revealed that responders had a predominant CTL activity against endogenous C26-related tumor antigens, whereas nonresponders had CTL that recognized preferentially the FR alpha antigen. CD8 from responder mice were characterized to release high levels of granulocyte-macrophage (GM)-CSF upon antigen stimulation. Tumors obtained from mice that died despite vaccination lost expression of the FR alpha transgene but maintained expression of endogenous C26 antigens. Immunoselection against FR alpha antigen was not observed in tumors from non-vaccinated controls and from CD8-depleted vaccinated mice. Down-regulation of FR alpha antigen expression was due, at least in part, to methylation of retroviral vector long terminal repeat promoter since FR alpha expression was partially restored, ex vivo, by treatment with 5-aza-2'-deoxy-cytidine (aza). These results indicate that CD8 T cell-mediated immunoselection and production of GM-CSF are determining factors for the efficacy of tumor vaccines.

IgG2a induced by interleukin (IL) 12-producing tumor cell vaccines but not IgG1 induced by IL-4 vaccine is associated with the eradication of experimental metastases

We evaluated whether antibody response correlates with tumor therapy by cytokine gene-modified tumor cell vaccines. To characterize the antibody (Ab) response against a known antigen, colon carcinoma C26 cells and C26 variants engineered to produce interleukin (IL) 12 or IL-4 were further transduced to express the human tumor-associated antigen gp38 folate receptor (FR) alpha. Irradiated IL-12- and IL-4-producing C26/FR alpha cell vaccines cured 50 and 30% of mice bearing C26/FR alpha lung micrometastases. Treatment induced a rapid, CD4-dependent Ab production dominated by IgG2a and IgG1 in response to the IL-12 or IL-4 vaccine, respectively. In contrast, untreated tumor-bearing mice showed a late serological response dominated by IgM. Anti-FR alpha IgG1 and IgG2a were able to suppress tumor metastases upon passive transfer in vivo. Sera from mice cured by the IL-12 vaccine displayed a higher binding activity, a higher anti-FR alpha IgG2a content, and a higher complement-mediated tumor cell lysis in vitro compared to the sera from nonresponder mice. Such a correlation was not found in the sera of mice treated with the IL-4 vaccine. These data indicate that cytokine-producing tumor cell vaccines strongly influence antibody response, and that in the case of the IL-12-based vaccine, the Ab titer correlates with the therapeutic response, thus suggesting its use for monitoring the outcome of vaccination in cancer patients.

Targeting of interleukin 2 to human ovarian carcinoma by fusion with a single-chain Fv of antifolate receptor antibody

To provide a new tool for the immunotherapy of human ovarian carcinoma, we constructed a fusion protein between interleukin-2 (IL-2) and the single-chain Fv (scFv) of MOV19, a monoclonal antibody directed against alpha-folate receptor (alpha-FR), known to be overexpressed on human nonmucinous ovarian carcinoma. This was accomplished by fusing the coding sequences in a single open reading frame and expressing the IL-2/MOV19 scFv chimera under the control of the murine immunoglobulin K promoter in J558L plasmacytoma cells. The design allowed the construction of a small molecule combining the specificity of MOV19 with the immunostimulatory activity of IL-2. This might improve the tissue penetration and distribution of the fusion protein within the tumor, reduce its immunogenicity, and avoid the toxicity related to the systemic administration of IL-2. The IL-2/MOV19 fusion protein was stable on purification from the cell supernatant and was biologically active. Importantly, this construct was able to target IL-2 onto the surface of alpha-FR-overexpressing tumor cells and stimulated the proliferation of the IL-2-dependent CTLL-2 cell line as well as that of human resting peripheral blood lymphocytes. In a syngeneic mouse model, IL-2/MOV19 scFv specifically targeted a-FR gene-transduced metastatic tumor cells without accumulating in normal tissues, due to its fast clearance from the body. Prolonged release of IL-2/MOV19 scFv by in vivo transplanted J558-EF6.1 producer cells protected 60% of mice from the development of lung metastases caused by an i.v. injection of a-FR gene-transduced tumor cells. Moreover, treatment with IL-2/MOV19 scFv, but not with recombinant IL-2, significantly reduced the volume of s.c. tumors. The pharmacokinetics and biological characteristics of IL-2/NMOV19 scFv might allow us to combine the systemic administration of this molecule with the adoptive transfer of in vitro retargeted T lymphocytes for the treatment of ovarian cancer, thereby providing local delivery of IL-2 without toxicity.

Interleukin 12-mediated prevention of spontaneous mammary adenocarcinomas in two lines of Her-2/neu transgenic mice

The ability of interleukin (IL)-12 to prevent tumors when administered to individuals with a genetic risk of cancer was studied in two lines of transgenic mice expressing rat HER-2/neu oncogene in the mammary gland. Female BALB/c (H-2(d)) mice carrying the activated HER-2/ neu oncogene show no morphological abnormalities of the mammary gland until 3 wk of age. They then progress through atypical hyperplasia to in situ lobular carcinoma and at 33 wk of age all 10 mammary glands display invasive carcinomas. Adult FVB mice (H-2(q)) carrying the HER-2/neu protooncogene develop mammary carcinomas with a longer latency (38-49 wk) and a lower multiplicity (mean of 2.6 tumors/mice). Treatment with IL-12 (5 daily intraperitoneal injections, 1 wk on, 3 wk off; the first course with 50 ng IL-12/day, the second with 100 ng IL-12/day) begun at 2 wk of age in BALB/c mice and at 21 wk of age in FVB mice markedly delayed tumor onset and reduced tumor multiplicity. Analogous results were obtained in immunocompetent and permanently CD8(+) T lymphocyte-depleted mice. In both transgenic lines, tumor inhibition was associated with mammary infiltration of reactive cells, production of cytokines and inducible nitric oxide synthase, and reduction in microvessel number, in combination with a high degree of hemorrhagic necrosis.

Anti-tumor immunity induced by murine melanoma cells transduced with the Mycobacterium tuberculosis gene encoding the 38-kDa antigen

The Mycobacterium tuberculosis Ag38 gene, which encodes a highly immunogenic protein, was cloned into a retroviral vector in-frame with the leader and the transmembrane portion of the nerve growth factor receptor, and transduced into murine melanoma cell line B16-B78. Significant protection was observed in mice immunized with the transduced melanoma cells and subcutaneously challenged with parental melanoma cells since only 20% of mice developed tumors. Necroscopy of mice immunized with the transduced melanoma cells revealed dramatic inhibition of experimental metastases induced by intravenous (i.v.) inoculation of parental melanoma cells. Moreover, vaccination with transduced cells significantly prolonged survival of mice challenged i.v. with parental melanoma cells. These data indicate that the presence of the mycobacterial 38-kDa protein greatly enhances immunological recognition of structures expressed by the parental melanoma cells. Comparison of Th1 and Th2 responses in mice immunized with parental melanoma cells versus mice receiving the transduced cells revealed a clear predominance of Th1 responses when the Ag38 protein was endogenously expressed. This transduction approach may represent a promising immunotherapeutic strategy for the treatment of cancer patients.

Active immunization of metastatic melanoma patients with interleukin-2-transduced allogeneic melanoma cells: evaluation of efficacy and tolerability

From January 1994 to July 1996 we immunized metastatic melanoma patients with HLA-A2-compatible, interleukin-2 (IL-2)-secreting, immunogenic melanoma lines in an attempt to induce a systemic reaction that might also affect distant melanoma lesions. Twelve patients (6 male and 6 female) aged from 28 to 72 years, affected with visceral and/or subcutaneous (s.c.) melanoma metastases, were treated. Two different HLA-A2+ melanoma lines were transduced with the human IL-2 gene (14932/IL-2 and 1B6/IL-2) and used as vaccine. Two groups of 4 patients each were injected s.c. with 5 x 10(7) and 15 x 10(7) irradiated 14932/IL-2 melanoma cells respectively, whereas a third group received 5 x 10(7) cells of the second line (1B6/IL-2). All patients received the vaccine on days 1, 13, 26; if no progression was evident, further immunizations were administered at monthly intervals. All patients were assessable for clinical response after at least three injections of the vaccine. In 4 cases a stabilization of disease lasting from 2 to 6 months was observed: in 2 of them a mixed type of response to treatment was noted with simultaneous evidence of regressing and non-responding lesions in the same patients. No signs of clinical response were found in the remaining patients. Nine patients died of disease between 3 and 24 months after the onset of therapy, whereas 3 were alive 3 months after the end of therapy. The local and systemic side-effects of treatment were mild. These results indicate that vaccination with cells bearing the appropriate antigens and releasing IL-2 locally can produce weak clinical responses, but also indicate that better results may be achieved through modifications of the vaccine, the schedule of immunization and/or a more appropriate selection of patients.

Immunotherapy of experimental metastases by vaccination with interleukin gene-transduced adenocarcinoma cells sharing tumor-associated antigens. Comparison between IL-12 and IL-2 gene-transduced tumor cell vaccines

We have compared the therapeutic activity and characterized the antitumor response induced by IL-12 and IL-2 gene-transduced tumor cell vaccines. Mice bearing lung metastases of the BALB/c colon carcinoma C51 were treated with syngenic, histologically related, and antigenically cross-reacting irradiated IL-12 (C26/IL12) or IL-2 (C26/IL2) gene-transduced C26 tumor cells given s.c. Vaccination with C26/IL12 cells cured 40% of mice, while vaccination with C26/IL2 cells reduced the number of metastatic nodules without affecting survival. Despite this difference, similar antitumor CTL activation was shown in mice treated with C26/IL12 or C26/IL2 cells. The lytic pattern of CTL was shown to be directed to tumor-associated Ags (TAA) shared between the colon carcinomas C51, C26, and CC36 as well as with other syngenic tumors. Both treatments induced anti-TAA Abs, but only sera from mice treated with C26/IL12 contained Ab that lysed tumor cells in a C-dependent cytotoxicity assay. Early infiltration of activated T cells was found in the lungs of mice vaccinated with C26/IL12. CD4+ lymphocytes purified from the lymph nodes draining the vaccination site or from the spleen showed a higher production of IFN-gamma in response to anti-CD3 mAb in C26/IL12 vaccinated mice, while a higher production of IL-4 was shown in mice vaccinated with C26/IL2 cells. These results indicate that the better therapeutic efficacy of vaccination with C26/IL12 is associated with the production of C-binding Ab, an early infiltration of the metastatic lungs by activated T lymphocytes and a predominant systemic activation of Th1 more than Th2 cells.

Immunotherapy of experimental metastases by vaccination with interleukin gene-transduced adenocarcinoma cells sharing tumor-associated antigens. Comparison between IL-12 and IL-2 gene-transduced tumor cell vaccines

We have compared the therapeutic activity and characterized the antitumor response induced by IL-12 and IL-2 gene-transduced tumor cell vaccines. Mice bearing lung metastases of the BALB/c colon carcinoma C51 were treated with syngenic, histologically related, and antigenically cross-reacting irradiated IL-12 (C26/IL12) or IL-2 (C26/IL2) gene-transduced C26 tumor cells given s.c. Vaccination with C26/IL12 cells cured 40% of mice, while vaccination with C26/IL2 cells reduced the number of metastatic nodules without affecting survival. Despite this difference, similar antitumor CTL activation was shown in mice treated with C26/IL12 or C26/IL2 cells. The lytic pattern of CTL was shown to be directed to tumor-associated Ags (TAA) shared between the colon carcinomas C51, C26, and CC36 as well as with other syngenic tumors. Both treatments induced anti-TAA Abs, but only sera from mice treated with C26/IL12 contained Ab that lysed tumor cells in a C-dependent cytotoxicity assay. Early infiltration of activated T cells was found in the lungs of mice vaccinated with C26/IL12. CD4+ lymphocytes purified from the lymph nodes draining the vaccination site or from the spleen showed a higher production of IFN-gamma in response to anti-CD3 mAb in C26/IL12 vaccinated mice, while a higher production of IL-4 was shown in mice vaccinated with C26/IL2 cells. These results indicate that the better therapeutic efficacy of vaccination with C26/IL12 is associated with the production of C-binding Ab, an early infiltration of the metastatic lungs by activated T lymphocytes and a predominant systemic activation of Th1 more than Th2 cells.

Limited antitumor T cell response in melanoma patients vaccinated with interleukin-2 gene-transduced allogeneic melanoma cells

We have immunized advanced melanoma patients with a HLA-A2-compatible human melanoma line genetically modified to release interleukin-2 (IL-2), to elicit or increase a T cell-mediated anti-melanoma response that may affect distant lesions. Twelve stage-IV patients were injected subcutaneously at days 1, 13, 26, and 55 with IL-2 gene-transduced and irradiated melanoma cells at doses of 5 or 15 x 10(7) cells. Both local and systemic toxicities were mild, consisting of transient erythema at the vaccination site; fever occurred in a minority of patients. Three mixed responses were recorded. Seven patients were evaluable for immunological studies. Mixed tumor-lymphocyte cultures carried out with different allogeneic HLA-A2-matched melanoma lines as stimulators and targets revealed an increase in the MHC-unrestricted, but no changes in the MHC-restricted, cytotoxicity in peripheral blood lymphocytes (PBL) obtained after vaccination as compared with those obtained before vaccination. Increased recognition of the tyrosinase 368-376 peptide occurred in post-vaccination PBL of one patient, whereas a weak increase in recognition of the gp100 280-288 peptide was detectable in another patient; these 2 patients also recognized the gp100 457-466 peptide. After in vitro, stimulation with the only available autologous melanoma line, CD4+ cells with autologous tumor-specific cytotoxicity and ability to release interferon-gamma (IFN-gamma) were found in post- but not in pre-vaccination PBL. In the same patient, as well as in another patient, limiting dilution analysis showed that vaccination resulted in an increased frequency of melanoma-specific cytotoxic T lymphocyte (CTL) precursors. These results indicate that vaccination with cells releasing IL-2 locally can expand a T cell response against antigen(s) of autologous, untransduced tumor, although this response occurred in a minority of the melanoma patients studied.

Amount of interleukin 12 available at the tumor site is critical for tumor regression

The C26 colon carcinoma is resistant to systemic recombinant interleukin 12 (rIL-12) therapy. Transduction of C26 with genes encoding the two subunits of murine IL-12 to release 30-80 pg/ml resulted in delayed tumor onset after injection of 5 x 10(4) cells into syngeneic BALB/c mice and in 40% tumor regression after injection into CD4-depleted mice. Here, we analyzed the activity of rIL-12 (1 microgram/day) against C26 grown into CD4-depleted mice. Like in mice given injections of interleukin 12 (IL-12) gene-transduced C26 cells, depletion of CD4+ cells led to tumor regression in 6 of 14 mice, and immumocytochemical characterization of tumor-infiltrating leukocytes showed abundant infiltration by CD8+ T cells and asialoGM1+ natural killer cells, which were scanty in tumors from nondepleted mice. On the basis of the percentage of tumor regression and leukocyte infiltration we can conclude that, in the C26 system, systemic rIL-12 (1 pmicrogramg/day) produces the same results as 30-80 pg/ml IL-12 released at the tumor site. A new polycistronic retroviral vector was then used to increase the amount of IL-12 produced by C26-transduced cells. C26 cells releasing 5 ng/ml IL-12, nearly 100 times more than the above-mentioned transduced cells, were tumorigenic in less than 50% of the mice given injections of 5 x 10(4) cells. In mice given injections of 5 x 10(5) cells, an initial tumor take of 100% followed by a complete tumor regression. Tumor regression was associated with infiltration of CD8+ and asialoGM1+ cells, and mice that remained tumor free were immune to a rechallenge of nontransduced C26 cells. The results indicate that the amount of IL-12 made available at the tumor site may determine both the type and number of infiltrating leukocytes and the events leading to tumor regression as well as it may overcame host immunosuppression.

Hypoxic tumor cell death and modulation of endothelial adhesion molecules in the regression of granulocyte colony-stimulating factor-transduced tumors

C-26 colon adenocarcinoma cells transduced with the granulocyte colony-stimulating factor (G-CSF) gene form large tumors when injected into sublethally irradiated mice. These tumors regress when leukocyte function is reconstituted. Electron microscopy and immunocytochemical analysis of regressing C-26/G-CSF nodules indicates that tumor destruction is due mainly to hypoxia resulting from the functional loss of tumor vasculature and is only marginally due to direct cytolysis. Desegregation of basal lamina, cell swelling, and loss of junctions characterized the vessels within regressing tumors. Tumor cells were necrotic or filled with lipid vacuoles regardless of the distance from nearby vessels. Damage of tumor vasculature was dependent on the infiltrating leukocytes and the cytotoxic cytokines they produced. Locally produced interleukin-1 and tumor necrosis factor-alpha (TNF-alpha) induced vascular cellular adhesion molecule-1 (VCAM-1) and E-selectin on tumor vessels. Treatment with monoclonal antibodies to interferon-gamma (IFN-gamma) or TNF-alpha blocked tumor regression by inhibiting VCAM-1 and E-selectin expression on tumor-associated endothelial cells resulting in a reduced number of infiltrating leukocytes. Thus, C-26/G-CSF tumor regression presents features typical of hemorrhagic necrosis that occurs through the cytokines produced by infiltrating leukocytes in response to G-CSF.

Interleukin 12 potentiates the curative effect of a vaccine based on interleukin 2-transduced tumor cells

The purpose of these studies was to determine whether systemic administration of recombinant interleukin 12 (rIL-12) is able to potentiate an initial, but insufficient T-cell antitumor response. Mice challenged with carcinoma cells engineered to release interleukin 2 (IL-2) and displaying such a response received single or multiple i.p. injections of rIL-12. This combination of systemic rIL-12 and local IL-2 increased the percentage of mice that rejected two different IL-2 gene-transduced tumors. In another set of experiments more closely resembling a clinical situation, IL-2 gene-transduced tumors were used as vaccines in an attempt to cure mice bearing wild-type parental tumors. The combination of these vaccines with systemic rIL-12 cured mice more effectively than rIL-12 and IL-2 gene-transduced tumor vaccines alone.

Cytokine-based gene therapy of human tumors. An overview

This review first summarizes the different strategies of gene therapy of cancer and then focuses on the immunological approach. Several studies in animal models with cytokine gene-transduced tumor cells indicate that local cytokine release usually results in tumor growth inhibition. Moreover, in a number of cases vaccination with such cells can reduce growth of established tumors or even cure the tumor-bearing animals. Translation of such a principle in human clinical setting is reported. We have transduced human melanoma cells with genes coding for interleukin (IL)-2, IL-4 or B7-1 and characterized such lines. The phenotype did not change after gene insertion but the functional, immunostimulatory activity of IL-2 or B7-1 gene-transduced melanoma cells was significantly increased compared to that of parental lines. These-lines were then used to vaccinate melanoma patients. Preliminary results of trials with IL-2 gene-transduced cells are presented which indicate a weak clinical response and the activation of a melanoma-specific cytotoxic T lymphocyte response in a low percentage of patients.

A human melanoma cell line transduced with an interleukin-4 gene by a retroviral vector releases biologically active IL-4 and maintains the original tumor antigenic phenotype

Experimental models of vaccination with tumor cells engineered to produce interleukin-4 (IL-4) have shown that the local release of this cytokine is associated with the development of antitumor immunity that may induce regression of established cancer. The aim of this study was to transduce a human melanoma cell line with the gene coding for human IL-4, and to analyze cytokine production, phenotypic characteristics, and antigen expression after transduction. A retroviral vector, constructed by inserting IL-4 cDNA into the LXSN vector, was used to infect the human melanoma cell line Me14932, known to express the MHC class I HLA-A2 and the melanoma-associated antigen Melan-A/MART-1, recognized by HLA-A2-restricted T-cells. The confluence of all G418-resistant cells (Me14932/IL-4) was then analyzed for proviral integration and IL-4 mRNA expression. Substantially stable IL-4 release was detected by ELISA in the supernatant of transduced cells, ranging from 1.6 to 4.6 ng/ml per 10(5) cells per 24 hr; such a cytokine displayed a specific biologic activity, as revealed by the stimulation of blast cell proliferation and the inhibition of lymphokine activated killer cell (LAK) induction by IL-2. After 200 Gy irradiation, IL-4 release remained detectable for 5 weeks, whereas cell proliferation ceased within 7 days. Morphology and immunophenotypic characteristics of the parental cell line (expression of MHC classes I and II, ICAM-1, LFA 3, melanoma-associated antigens, etc.) were retained by the IL-4 gene-transduced melanoma as assayed by microscopy and immunofluorescence; likewise, susceptibility to lysis by LAK cells as well as a T-cell clone recognizing the Melan-A/MART-1 antigen did not change. These results, together with the lack of replication-competent retrovirus, suggest that the Me14932/IL-4 cell line displays suitable characteristics for its use in the treatment of HLA-matched melanoma patients.

Redundancy of autocrine loops in human rhabdomyosarcoma cells: induction of differentiation by suramin

Three human rhabdomyosarcoma cell lines were used to investigate the presence of autocrine loops based on the production of insulin-like growth factor (IGF)-II, basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF)/transforming growth factor (TGF)-alpha and of their corresponding receptors, and whether these loops affect cell proliferation and myogenic differentiation. Two cell lines, RD/18 and CCA, deriving from tumours of the embryonal histotype, showed the presence of both growth factors and receptors which make possible three different autocrine loops, while the alveolar RMZ-RC2 cell line lacked that based on the EGF receptor. Culture of rhabdomyosarcoma cells in the presence of specific blocking antibodies, directed to a component of single autocrine loops, inhibited cell proliferation (up to 50%), without inducing myogenic differentiation. Suramin, a drug which non-selectively interferes with the binding of growth factors to their cellular receptors, was used to block all the autocrine loops simultaneously. In CCA and RMZ-RC2 cells suramin was able to induce a significant increase (up to 3-fold) in the proportion of myosin-positive cells over control cultures. Therefore rhabdomyosarcoma cells of embryonal and alveolar histotype can show a redundancy of growth-sustaining autocrine loops. Suramin could interfere with them by acting on both growth inhibition and induction of myogenic differentiation.

A B7-1-transfected human melanoma line stimulates proliferation and cytotoxicity of autologous and allogeneic lymphocytes

B7 co-stimulation is necessary to activate resting T cells upon antigen recognition by the T cell receptor. To see whether expression of B7 may render human melanoma cells able to stimulate T cells, a cloned melanoma line (Me1B6), which did not express B7-1, was transfected with the human B7-1 gene. In proliferation assays, B7-1 transfected cells (Me1B6/B7) showed greater stimulatory activity of allogeneic and autologous peripheral blood lymphocytes (PBL) compared to parental, non-transfected tumor cells. This effect was also seen when allogeneic CD8+ and CD4+ subpopulations were used as effectors. In these studies, activation of lymphocytes was B7-1-dependent and HLA classes I and II mediated. The higher proliferation correlated with an increased lytic activity by PBL stimulated with B7-1+ tumor cells against the untransfected Me1B6. Furthermore, PBL from a metastatic melanoma patient stimulated by Me1B6/B7 developed an higher lytic activity not only against Me1B6 but also against their autologous, B7-1- tumor. Finally, after Me1B6/B7 stimulation, PBL released interleukin (IL)-2 and interferon-gamma, but not IL-4, suggesting a Th1-mediated response. These data support the use of B7-1 transfected melanoma cells in the therapeutic vaccination of melanoma patients.

An in vivo model to compare human leukocyte infiltration in carcinoma xenografts producing different chemokines

In this study we tested whether the pattern of cytokines expressed by human carcinomas could account for a different in vivo recruitment of leukocyte subpopulations as a part of the anti-tumor immune response. Two carcinoma cell lines, SK-OV-3 ovary carcinoma and CALU-3 lung carcinoma, were analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR), immunofluorescence and ELISA for the expression and in vitro production of cytokines with chemotactic, proinflammatory and growth-stimulating activity. Although both cell lines displayed a constitutive expression of granulocyte colony-stimulating factor (G-CSF), granulocyte macrophage-CSF (GM-CSF), M-CSF, interleukin (IL-) 1 alpha and IL-8, only CALU-3 cell line expressed IL-10, RANTES (Regulated upon Activation, Normal T Expressed and Secreted) and monocyte-activating protein (MCP)-1. MCP-1 and IL-8 were detected by immunohistochemistry on sections from tumors xenografted in nude mice. To analyze whether the tumor-released cytokines modulate leukocytes in tumor infiltration, we studied the distribution of human peripheral blood leukocytes injected in the proximity of SK-OV-3 and of CALU-3 tumor xenografts. While SK-OV-3 was unable to recruit human leukocytes and appeared to be barely infiltrated by murine CD45+ cells, CALU-3 appeared to be rapidly and heavily infiltrated by human leukocytes which induced tumor necrosis within 18-24 hr.

CD4 T cells inhibit in vivo the CD8-mediated immune response against murine colon carcinoma cells transduced with interleukin-12 genes

Retroviral-mediated cytokine gene transfer into tumor cells is a highly effective way of inducing tumor inhibition and immunity. We analyzed the tumorigenicity of C-26 murine colon carcinoma cells transduced with genes encoding the two subunits of murine interleukin-12 (IL-12) in a polycistronic retroviral vector and selected for resistance to G418 and for IL-12 production (30-80 pg/ml). BALB/c mice injected s.c., i.v. and intrasplenically with C-26/IL-12 cells from three different IL-12-producing clones showed delayed tumor onset as compared with mice injected with control NeoR-transduced or parental tumor cells. Although C-26/IL-12 tumor-bearing mice eventually died of lung metastasis, their survival time was twice as long as that of mice injected with control cells. In experiments with mice selectively depleted of natural killer (NK) cells before tumor cell injection, the time of tumor onset and survival of mice injected with C-26/IL-12 s.c. and i.v., respectively, was reduced. CD8+ T cell depletion had no effect on latency or survival, whereas removal of CD4+ T cells led to C-26/IL-12 tumor regression in about 40% of mice. Histological and immunocytochemical characterization of leukocytes infiltrating C-26/IL-12 tumors showed only slight infiltration with few T cells in non-depleted mice but abundant infiltration by CD8+ T cells and asialo-GM1+ NK cells in tumors of mice depleted of CD4+ T cells. The lack of CD8+ T cell infiltration is not due to a CD4-mediated suppression of their activation because irradiated C-26/IL-12 cells primed for the induction of a strong cytotoxic T lymphocyte response against C-26 parental cells and induced CD8+ effector cells that protected against C-26/IL-12 in a Winn assay. Rather, the results suggest that, although C-26/IL-12 cells injected in vivo stimulate both NK and CD8+ T cells, tumor infiltration by the latter is inhibited by CD4+ T cells.

Interleukin-2 gene-transduced human melanoma cells efficiently stimulate MHC-unrestricted and MHC-restricted autologous lymphocytes

Two human melanoma lines were transduced by a retroviral vector with the gene of the human interleukin-2 (IL-2) and characterized for their immunological properties in comparison with the parental lines. Transduction resulted in the production of biologically active IL-2 in the average amounts of 2,282 and 2,336 pg/ml per 10(5) cells per 24 hr over 3 and 2 months by the Me14932/IL-2 and the Me1B6/IL-2 lines, respectively. Melanoma-transduced cells lost their tumorigenicity in nude mice. No major changes in the phenotype were observed in IL-2 gene-transduced lines. In fact, more than 90% of cells expressed class I and II(DR) HLA, adhesion molecules, integrins, and melanoma-associated antigens. Irradiation with 100-400 Gy, while inhibiting tumor cell growth in vitro, allowed the release of IL-2 by the transduced cells for at least 5 weeks. The two melanoma lines also maintained susceptibility to lysis by lymphokine-activated killer (LAK) cells and by a HLA-A2-restricted melanoma-specific cytotoxic T lymphocyte (CTL) clone recognizing the melanoma antigen (Melan-A). In a limiting dilution assay, transduced, but not parental melanoma lines unless added with an amount of IL-2 comparable to that released by the transduced cells, were able to expand both nonspecific and melanoma-specific CTL precursors from autologous peripheral blood lymphocytes (PBL). In mixed lymphocytes-tumor cultures, IL-2 gene-transduced melanoma cells stimulated the expansion of major histocompatibility complex (MHC)-unrestricted effectors from autologous PBL, and of CD3+ CD8+ MHC-restricted CTL from tumor-invaded lymph nodes. These results indicate that IL-2 gene transduction does not alter significantly the expression of the immunologically relevant molecules of human melanoma lines while increasing their ability to stimulate both specific and nonspecific lymphocyte responses. These lines will be of value in the vaccination of melanoma patients.

Expression of cytokine/growth factors and their receptors in human melanoma and melanocytes

Human tumors can constitutively express cytokines and growth factors, but the extent of this expression has not been investigated. Using 44 different probes to cytokines, growth factors, and their receptors, we tested 21 melanoma and 5 melanocyte cultures for RNA transcript expression by reverse transcriptase-polymerase chain reaction. With 30 amplification cycles, expression of the cytokines interleukin (IL)-1 beta, IL-6, leukemia inhibitory factor (LIF), IL-7, gro alpha, IL-8 and the p35 chain of IL-12 was detected in more than 60% of melanomas. Concomitant receptors for IL-6 and IL-7 were also detected. IL-1 alpha, IL-5, Rantes, IL-10, interferon (IFN)-beta, tumor-necrosis factor (TNF)-alpha, G-colony-stimulating factor (CSF) and GM-CSF were expressed at lower levels. Melanocytes showed greatly reduced cytokine RNA transcripts, and only gro alpha was consistently detected. No expression of IL-2, IL-3, IL-4, IL-9, the p40 chain of IL-12, IFN-alpha or IFN-gamma RNA transcripts was detected in melanomas or melanocytes. The growth factors expressed by melanomas and, after further signal amplification, by melanocytes were transforming growth factor (TGF)-alpha, epidermal growth factor (EGF), TGF-beta, endothelial-cell growth factor (ECGF), basic-fibroblast growth factor (bFGF), nerve growth factor (NGF) and steel. The receptors EGFR, FGFR, NGFRp70 and c-kit were also expressed by melanomas and melanocytes. These results point to new possible autocrine and paracrine pathways in melanoma biology.

Cytokine gene transduction in tumor cells: interleukin (IL)-2 or IL-4 gene transfer in human melanoma cells

Cytokine gene transfer into mouse tumor cells has been shown to stimulate a strong immune response resulting in the rejection of the transduced tumor when injected in vivo. Therefore, retroviral vectors containing the human interleukin (IL)-2 or IL-4 gene have been constructed to transduce human melanoma cells to explore whether their immunogenicity can be increased both in vitro and in vivo. Our preliminary results indicate that retroviral vectors can efficiently transduce the IL-2 and or IL-4 gene into melanoma clones, inducing production of either cytokine in the range of 0.5-2 ng/ml/10(5) cells in 48-72 h. No modifications of the growth rate, morphology and antigenicity of the transduced tumor cells were found.

Expression of a growth arrest specific gene (gas-6) during liver regeneration: molecular mechanisms and signalling pathways

A set of growth arrest-specific (gas) genes negatively regulated by serum has been identified. To define the role of gas genes in a model of cell proliferation in vivo we analyzed the expression of one of these genes (gas-6) during liver regeneration after partial hepatectomy (PH). We found that gas-6 mRNA was down-regulated 4 hours after PH, within the G0 to G1 transition. Later on, gas-6 mRNA increased over the level found in normal liver with a peak at 16 hours, before the onset of DNA synthesis. This surge was probably triggered by an inflammatory response caused by the surgical trauma, because an increase of similar extent occurring with the same time course was present in livers of sham-operated and turpentine-treated rats. Comparison of mRNA steady state levels with nuclear transcription rates indicated that gas-6 expression is post-transcriptionally regulated. As we found that down-regulation of gas-6 expression was prevented by treatment with Actinomycin D, a labile protein might be involved in the determination of gas-6 mRNA stability. To investigate the mitogenic signals controlling gas-6 expression during liver regeneration we treated hepatectomized rats with a specific alpha-1-adrenoceptor blocker (prazosin) as well as with drugs which modify intracellular calcium levels. The decrease of gas-6 mRNA 4 hours after PH was prevented by prazosin and by neomycin, an inhibitor of calcium release from endogenous stores. These findings suggest that down-regulation of gas-6 expression during hepatic regeneration is triggered by catecholamines interaction with alpha-1-adrenergic receptors and by subsequent calcium release. In addition we found that the rise of gas-6 gene expression occurring at 16 hours after PH was not affected by prazosin but was inhibited by trifluoperazine. Therefore, we suggest that up-regulation of gas-6 gene expression is mediated by the interaction of calcium with calmodulin, independently of catecholamines.

Lymphotoxin gene expression by melanocytes and melanoma cell lines and persistence of unspliced mRNA

Human melanoma cell lines express many different cytokines [1], including lymphotoxin (LT), the production of which has been considered to be restricted to cells of the lymphocytic lineage in response to cell activation. LT expression by melanomas is constitutive and characterized by the presence of two mRNAs. In the present paper we report an analysis of the origin of the two LT-specific transcripts in four human melanoma cell lines at different stages of progression and in four melanocytic cell lines. Reverse transcription-polymerase chain reaction (RT-PCR) performed with primers lying in the first and fourth exons and hybridization with intron probes showed a spliced and a full-unspliced LT mRNA. This pattern was also displayed by one of four melanocyte cell lines. Western blot analysis indicated that LT RNA is properly translated to a 23-25 kDa protein and immunocytochemistry showed its localization within the cytoplasm and on the cell membrane.

Regression of an established tumor genetically modified to release granulocyte colony-stimulating factor requires granulocyte-T cell cooperation and T cell-produced interferon gamma

Using the murine colon adenocarcinoma C-26 cell line, engineered to release granulocyte colony-stimulating factor (G-CSF) (C-26/G-CSF), were studied the mechanisms responsible for inhibition of tumor take in syngeneic animals and of regression of an established tumor in sublethally irradiated mice injected with these cells. Immunocytochemistry and in situ hybridization, performed to characterize tumor-infiltrating leukocytes and their cytokine expression, respectively, indicated that polymorphonuclear leukocytes (PMN) were the major cells responsible for inhibition of tumor take and that they expressed mRNA for interleukin 1 alpha (IL-1 alpha), IL-1 beta, and tumor necrosis factor alpha (TNF-alpha). Expression of interferon gamma (IFN-gamma) and of IL-4 was undetectable, consistent with the absence of T lymphocytes at the site of tumor injection. In mice injected with C-26/G-CSF cells after 600-rad irradiation, the tumors grew to approximately 1.5 cm in 30 d, regressing completely thereafter in 70-80% of mice. During the growing phase, tumors were infiltrated first by PMN (between days 15 and 20), then by macrophages, and last by T lymphocytes. Both CD4+ and CD8+ T cells were present but only CD8 depletion significantly abrogated tumor regression. Depletion of PMN by the RB6-8C5 antigranulocytes monoclonal antibody reduced the number of T cells infiltrating the tumor and prevented tumor regression. In situ hybridization performed at the beginning of tumor regression revealed the presence of mRNA for IL-1 alpha, IL-1 beta, and TNF-alpha, but also the presence of cells, with lymphoid morphology, expressing IFN-gamma. Tumors from mice treated with recombinant IFN-gamma (between days 20 and 35) were rejected faster, whereas mice treated with antibodies to IFN-gamma (from day 20) died of progressive tumor. Cyclosporin A treatment (started at day 20) also abrogated tumor regression. These results indicate that inhibition of tumor take and regression in this model occurs through different mechanisms that involve PMN and PMN-T cell interactions, respectively, as well as a combination of cytokines that, for tumor regression, require IFN-gamma. Thus, gene transfer of a single cytokine gene such as G-CSF into tumor cells appears to be sufficient to trigger the cascade of cell interactions and cytokine production necessary to destroy a cancer nodule.

Interleukin-6 expression in human neutrophil and eosinophil peripheral blood granulocytes

Human peripheral blood granulocytes were analyzed for expression of interleukin-6 (IL-6) using reverse-transcriptase polymerase chain reaction (RT-PCR) and in situ hybridization. Neutrophil granulocytes from healthy donors were shown to express variable levels of IL-6. This expression was rapidly down-regulated after the removal of the cells from the circulating blood. In vitro culture of neutrophils abolished IL-6 expression, which could be reactivated by addition of GM-CSF to the culture medium. Constitutive expression of IL-6 was instead demonstrated in eosinophil granulocytes purified from normal donors and from a hypereosinophilic patient. In situ hybridization of unstimulated granulocytes confirmed that IL-6 expression occurs both in eosinophils and in neutrophils from peripheral blood. These findings show that granulocytes can actively contribute to cytokine expression in the peripheral blood and suggest their role in the afferent limb of the immune response, since by IL-6 production they might modulate T- and B-lymphocyte functions, granulocyte self-priming, and endothelial interaction.

Expression of cytokine genes, including IL-6, in human malignant melanoma cell lines

As a preliminary to transducing human melanoma cells with lymphokine genes, we sought for constitutive gene expression and production of eight interleukins, tumour necrosis factors and granulocyte-colony stimulating factor in 19 human melanoma cell lines. Conversion of RNA into cDNA by reverse transcriptase and polymerase chain reaction (RT-PCR) were employed to evaluate gene expression while enzyme-linked immunosorbent assays (ELISA) or biological assays were used to assess the presence of proteins. No expression of interleukins (IL) 3, 4, and 5 or interferon-gamma RNA was found, while the other cytokines were variably expressed in melanoma lines, with IL-1 alpha, IL-1 beta, IL-6, IL-8, being detectable in most of the lines. At protein level, 10 melanoma cells were tested with ELISA and all were found to produce IL-8, five produced IL-6, two tumour necrosis factor (TNF)-alpha, one IL-1 alpha and two TNF beta. The levels of TNF beta were at the limit of test sensitivity. The amount of various cytokines released by the different lines varied widely. Biological assay with the D10-G4 clone confirmed the presence of IL-1 alpha in the supernatant of melanoma (ME) 10221 and revealed an IL-1 activity in the supernatant of Me 4024/1. The proliferating activity of melanoma supernatants on D10-G4 was inhibited by treatment with polyclonal antibodies against IL-1 alpha but not with antibodies against IL-1 beta. TNF biological activity was tested against the TNF-susceptible fibrosarcoma WEHI 164 clone 13.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation and mapping to 17p12-13 of the human homologous of the murine growth arrest specific Gas-3 gene

A family of growth arrest specific (Gas) genes was operationally defined on the basis of the strategy utilized to isolate them e.g. differential expression in quiescent and growing cells. Our interest in the Gas-3 gene was prompted by our previously reported localization of the gene on the mouse chromosome 11.44 +/- 1.9 cM proximal to the Trp53 locus and by the finding, by others, that it codes for a myelin protein and that a point mutation in its fourth putative transmembrane region is associated with the trembler mutation. We have isolated the human homologous of the mouse Gas-3 gene and utilized the cloned sequences as a probe to localize the gene on human chromosomes both by analysis of human-rodent somatic cell hybrids and in situ hybridization of human metaphases. We have now localized the human Gas-3 gene on chromosome 17p12-13. Its possible role in both the development of neoplasia in neurofibromatosis patients and in the myelin degenerative disease as the Charcot-Marie-Tooth is discussed.

Granulocyte colony-stimulating factor (G-CSF) gene transduction in murine adenocarcinoma drives neutrophil-mediated tumor inhibition in vivo. Neutrophils discriminate between G-CSF-producing and G-CSF-nonproducing tumor cells

We have previously demonstrated that the murine colon adenocarcinoma C-26 cell line transduced with the human gene for the granulocyte CSF (G-CSF) loses tumorigenic activity through a mechanism that involved massive targeting of neutrophils at the site of tumor injection. The suppression of tumorigenicity by G-CSF was limited to the G-CSF-producing cells and was not transferred to nonproducing C-26 cells in a mixed tumor transplantation assay. We present direct evidence that neutrophils are involved in this phenomenon. We firstly examined, by electron microscopy (EM), the morphology of tumor infiltrates obtained 2, 5, and 10 days after s.c. injection of a mixture of G-CSF-producing and -nonproducing C-26 cells into syngeneic BALB/c mice. The EM analysis showed at 5, but not at 2 or 10 days, the presence of neutrophils in intimate contact with tumor cells. We then investigated whether neutrophils discriminate between G-CSF-producing and -nonproducing C-26 cells. To this aim, C-26 cells were transduced, via retroviral vector, with the Escherichia coli LacZ gene and mixed tumor transplantation assays were performed by injecting a mixture of G-CSF-producing beta-gal- and G-CSF-nonproducing beta-gal+ C-26 cells at different ratios. Histologic and EM analysis of the tumors growing at the site of injection were carried out. Five days after injection, treatment with x-gal revealed, at the histochemical level, the presence of neutrophils around G-CSF producing beta-gal- cells; cell-cell contacts and fusion of cell membranes were detected by EM only between neutrophils and G-CSF-producing cells. In vitro experiments, performed in Boyden chambers, confirmed that the G-CSF produced by C-26 cells was a chemoattractant for neutrophils. In addition, a colorimetric, cytostatic assay revealed that neutrophils were able to inhibit the growth of G-CSF-producing but not of G-CSF-nonproducing C-26 cells. Thus the tumor take after injection of G-CSF-producing C-26 cells seems to be controlled in situ through two major mechanisms namely neutrophil chemotaxis and neutrophil-mediated tumor inhibition. The results indicate that neutrophils can discriminate between G-CSF-producing and -nonproducing tumor cells and that neutrophils infiltrate the tumor mixture as long as G-CSF-producing cells are present.

Granulocyte colony-stimulating factor (G-CSF) gene transduction in murine adenocarcinoma drives neutrophil-mediated tumor inhibition in vivo. Neutrophils discriminate between G-CSF-producing and G-CSF-nonproducing tumor cells

We have previously demonstrated that the murine colon adenocarcinoma C-26 cell line transduced with the human gene for the granulocyte CSF (G-CSF) loses tumorigenic activity through a mechanism that involved massive targeting of neutrophils at the site of tumor injection. The suppression of tumorigenicity by G-CSF was limited to the G-CSF-producing cells and was not transferred to nonproducing C-26 cells in a mixed tumor transplantation assay. We present direct evidence that neutrophils are involved in this phenomenon. We firstly examined, by electron microscopy (EM), the morphology of tumor infiltrates obtained 2, 5, and 10 days after s.c. injection of a mixture of G-CSF-producing and -nonproducing C-26 cells into syngeneic BALB/c mice. The EM analysis showed at 5, but not at 2 or 10 days, the presence of neutrophils in intimate contact with tumor cells. We then investigated whether neutrophils discriminate between G-CSF-producing and -nonproducing C-26 cells. To this aim, C-26 cells were transduced, via retroviral vector, with the Escherichia coli LacZ gene and mixed tumor transplantation assays were performed by injecting a mixture of G-CSF-producing beta-gal- and G-CSF-nonproducing beta-gal+ C-26 cells at different ratios. Histologic and EM analysis of the tumors growing at the site of injection were carried out. Five days after injection, treatment with x-gal revealed, at the histochemical level, the presence of neutrophils around G-CSF producing beta-gal- cells; cell-cell contacts and fusion of cell membranes were detected by EM only between neutrophils and G-CSF-producing cells. In vitro experiments, performed in Boyden chambers, confirmed that the G-CSF produced by C-26 cells was a chemoattractant for neutrophils. In addition, a colorimetric, cytostatic assay revealed that neutrophils were able to inhibit the growth of G-CSF-producing but not of G-CSF-nonproducing C-26 cells. Thus the tumor take after injection of G-CSF-producing C-26 cells seems to be controlled in situ through two major mechanisms namely neutrophil chemotaxis and neutrophil-mediated tumor inhibition. The results indicate that neutrophils can discriminate between G-CSF-producing and -nonproducing tumor cells and that neutrophils infiltrate the tumor mixture as long as G-CSF-producing cells are present.

bcl-2 proto-oncogene expression in normal and neoplastic human myeloid cells

The present study provides immunobiochemical and molecular data on the differentiation-linked expression of the bcl-2 proto-oncogene in normal and neoplastic myeloid cells. Using a recently developed monoclonal antibody (MoAb) to the bcl-2 molecule, staining of normal bone marrow myeloblasts, promyelocytes, and myelocytes, but neither monocytes nor most polymorphonuclear cells, was demonstrated. By two-color flow cytometric analysis, bcl-2 was evidenced in CD33+ and CD33+/CD34+ myeloid cells as well as in the more primitive CD33-/CD34+ population. The leukemic cell lines HL-60, KG1, GM-1, and K562 were bcl-2 positive together with 11 of 14 acute myeloid leukemias (AML) and three of three chronic myeloid leukemias (CML) in blast crises; six of seven CML were negative. Among myelodysplastic cases, augmentation of the bcl-2 positive myeloblastic compartment was found in refractory anemia with excess of blasts (RAEB) and in transformation (RAEB-t). Western blots of myeloid leukemias and control lymphocytes extracts evidenced an anti-bcl-2 immunoreactive band of the expected size (26 Kd). Moreover, the HL-60 and KG1 cell lines, both positive for the bcl-2 protein, exhibited the appropriate size bcl-2 mRNA (7.5 Kb). These findings clearly indicate that the bcl-2 gene is operative in myeloid cells and that the anti-bcl-2 MoAb identifies its product and not a cross-reactive epitope. Induction of HL-60 differentiation toward the monocytic and granulocytic pathways was accompanied by a marked decrease in bcl-2 mRNA and protein levels; bivariate flow cytometric analysis showed that the fraction becoming bcl-2 negative was in the G1 phase of the cell cycle. These data establish that the bcl-2 proto-oncogene is expressed on myeloid cells and their progenitors and is regulated in a differentiation-linked manner.

Inhibition of proliferation by c-myb antisense oligodeoxynucleotides in colon adenocarcinoma cell lines that express c-myb

Steady-state mRNA levels of the protooncogene c-myb were measured by Northern blot analysis in the human colon carcinoma cell lines LoVo, the doxorubicin-resistant derivative LoVo/Dx, Colo 205, and HT 29. Overexpression of c-myb mRNA was detected in the Colo 205 cell line, probably because of gene amplification, while in human HT 29 cells c-myb was not expressed at a detectable level. Comparison between LoVo and LoVo/Dx cell lines showed that c-myb mRNA levels were much higher in the doxorubicin-resistant derivative than in the parental line. c-myb antisense oligodeoxynucleotides inhibited cell proliferation only in the cell lines with detectable mRNA c-myb (LoVo, LoVo/DX, and Colo 205). The dose of antisense exerting inhibitory effect was related to the levels of c-myb mRNA expression. Inhibition of c-myb expression in antisense-treated LoVo/DX cells was demonstrated by the reverse transcriptase polymerase chain reaction technique. LoVo/Dx cells were induced to differentiate by treatment with dimethylformamide to determine whether down-regulation of c-myb expression would accompany the process of differentiation. During the treatment with dimethylformamide the expression of c-myb decreased in parallel with the reduction of cell growth, while terminal differentiation of these cells was associated with changes in the expression of carcinoembryonic antigen and laminin receptor genes. Our findings demonstrate that the expression of c-myb is important for the proliferation of colon carcinoma cell lines and suggest that the role of this protooncogene is not restricted to cells of hematopoietic origin but is more general than previously thought.

The high lysability by LAK cells of colon-carcinoma cells resistant to doxorubicin is associated with a high expression of ICAM-1, LFA-3, NCA and a less-differentiated phenotype

A human colon-carcinoma cell subline resistant to doxorubicin (LoVo/Dx), previously shown to be more lysed than the chemosensitive subline LoVo/H by different immune effectors, is reported here to be similarly susceptible to direct, anti-proliferative effect of soluble cytokines (TNF-alpha and/or IFN-gamma). More adhesion molecules ICAM-1, LFA-3 and NCA were expressed on LoVo/Dx than on LoVo/H, while no significant amounts of CEA were detectable on the cell surface or in culture supernatant of either tumor subline. Anti-ICAM-1, anti-LFA-3 and anti-NCA monoclonal antibodies (MAbs) caused a marked reduction of lysis by interleukin-2 (IL-2) activated lymphocytes (LAK) of LoVo/Dx, whereas a lower effect was evident on LoVo/H. A pool of these antibodies was able to further increase the inhibition of the LAK lysis of both sublines. LoVo/Dx displayed a less differentiated phenotype as assessed by morphology, in vitro growth and altered or increased expression of markers such as desmoplakin and vimentin respectively, and disappearance of mucin. Treatment of LoVo sublines with differentiating agents (dimethylformamide and retinoic acid) led to a decreased expression of all adhesion molecules studied, accompanied by increased resistance to LAK-mediated lysis. These data indicate that sensitivity of chemoresistant tumor cells to cytotoxic effectors depends on the level of expression of adhesion molecules, including NCA, and is related to differentiation stage.