The immunotherapy of cancer and tumor escape from immune surveillance.
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Publications and source records attributed to S Chouaib.
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To investigate the mechanism underlying the absence of arachidonic acid (AA) release by TNF in TNF-resistant cells, we first performed comparative analysis of phospholipid pools in both TNF-sensitive (MCF7) and their equivalent resistant cells (C1001). Quantification and incorporation studies of [(3)H]AA indicated that TNF-resistant cells were not depleted in AA. Furthermore, distribution of this fatty acid in different phospholipid pools was similar in both sensitive cells and their resistant counterparts, ruling out a defect in phospholipid pools. Since phospholipase A(2) (PLA(2)) are the main enzymes releasing free AA, we investigated their relative contribution in the acquisition of cell resistance to TNF-induced cell death and AA release. For this purpose, we used two PLA(2) inhibitors, methylarachidonyl fluorophosphate (MAFP) and bromoenol lactone (BEL), which selectively and irreversibly inhibit the cytosolic PLA(2) (cPLA(2)) and the Ca(2+)-independent PLA(2), respectively. Although a significant inhibitory effect of MAFP on both TNF-induced AA release and PLA(2) activity in MCF7 was observed, BEL had no effect. The inhibitory effect of MAFP on cPLA(2) activity correlated with an inhibition of TNF-induced cell death. Western blot analysis revealed that TNF induced a differential cleavage of cPLA(2) in TNF-sensitive vs TNF-resistant cells. Although the p70 (70-kDa) form of cPLA(2) was specifically increased in TNF-sensitive cells, a cleaved form, p50 (50 kDa), was selectively observed in TNF-resistant C1001 cells in the presence or absence of TNF. These findings suggest that the acquisition of cell resistance to this cytokine may involve an abnormal cPLA(2) cleavage.
IL-15 and SCF fail to induce NK differentiation and proliferation of CD34+ hematopoietic progenitors from chronic myeloid leukemia patients in contrast to normal stem cells although, both normal and leukemic CD34+ cells display comparable expression of c-kit or IL-15 receptor subunits. Interestingly, confocal microscopy analysis revealed that leukemic and most normal CD34+ cells produce and secrete IL-15, as shown by its trafficking through the Golgi apparatus and early endosomes. However, only leukemic progenitors express the membrane bound IL-15. Colocalization and internalization of IL-15Rbeta/gammac and IL-15Ralpha/gammac complexes indicated that IL-15 was specifically uptaken by leukemic progenitors. We also demonstrated that in both normal and leukemic progenitors, the signaling kinase Jak3 is constitutively pre-associated with the gammac chain. Anti-IL-15 neutralizing mAb treatment resulted in down-regulation of gammac chain and disruption of gammac/Jak3 interaction in normal but had no effect in leukemic progenitors. Our results suggest the existence in both normal and leukemic CD34+ cells of a constitutive production of a bioactive IL-15 that does not lead to NK differentiation and further indicate that membrane bound IL-15 and constitutive activation of gammac are hallmarks of leukemic progenitors. Oncogene (2000).
In this study, we showed that renal tumors contain substantial subsets of CD8(+) p58(+) T cells. From 1 of these tumors, T cells were amplified in mixed lymphocytes-tumor cell cultures and p58(+) T cells were selected immunologically. After expansion, phenotypic and functional features of p58(+) and p58(-) T cells were examined. The p58(+) T cells expressed p58.2 receptor and corresponded to CD3(+), CD8(+), T-cell receptor (TCR) alpha/beta(+) T cells that were CD56(+) and CD28(-). Functionally, p58(+) T cells showed a low level of lytic activity against autologous tumor cells that was dramatically and specifically increased by anti-p58.2 monoclonal antibody. On the other hand, p58(-) CD8(+) T cells did not lyse autologous tumor cells and had non-major histocompatibility complex-restricted cytotoxicity against K562 and Daudi cells. A p58(+) cytotoxic T lymphocyte (CTL) clone (4C7) with the same characteristics as the p58(+) T-cell line was derived. This CTL clone did not lyse autologous normal B cells but lysed several HLA-A1(+) renal tumor cell lines. Analysis of TCR repertoire diversity showed that the p58(+) T-cell line contained 3 TCR rearrangements, whereas the TCR repertoire of p58(-) T cells was polyclonal. Interestingly, TCR transcripts of p58(+) T cells and of CTL clone 4C7 were detected as prominent ex vivo in tumor cells but not in peripheral blood mononuclear cells, suggesting that these cells are antigen specific and amplified at the tumor site. (Blood. 2000;95:2883-2889)
We have shown that the loss of p53 function contributed to resistance of tumor cells to TNF-induced cytotoxicity. In the present study, we evaluated the effect of wild-type p53 (wt-p53) expression on TNF sensitivity, by introducing wt-p53 into MCF7/Adr cells in which p53 was deleted, via a recombinant adenovirus encoding p53 (Ad-p53). Our results indicate that infection with Ad-p53 (50-100 viral particles per cell) resulted in pronounced cytotoxicity, whereas infection with 10 viral particles per cell, which was weakly toxic for the MCF7/Adr cells, sensitized these cells to TNF-induced cell death. Moreover, expression of wt-p53 in MCF7/Adr cells induced the production of reactive oxygen intermediates (ROIs) and caused glutathione (GSH) depletion, indicating disturbances in the cellular redox state. Additional treatment of cells with the anti-oxidant and glutathione (GSH) precursor N-acetylcysteine (NAC) resulted in inhibition of p53-induced ROIs production and in partial restoration of intracellular GSH levels, which was associated with the ability of NAC to inhibit p53-modulated TNF-induced cytotoxicity. Interestingly, Ad-p53 was able to inhibit TNF-induced MnSOD mRNA expression in MCF7/Adr cells, which might contribute to the sensitization of cells to the cytotoxic action of TNF. Taken together, our data strongly suggest that wt-p53 expression sensitizes TNF-resistant MCF7 cells with p53 deletion to TNF-induced cell death by a pathway that is dependent on ROIs production.
BACKGROUND: Mast cells, which play a unique role in inflammatory and allergic responses, have also been shown to actively participate to the build-up of protective host defense mechanisms. Recently, they have been shown to stimulate resting B cells and to form heterotypic aggregates with activated T cells, resulting in mast cell degranulation. OBJECTIVES: Our aim is to investigate the cytokine requirements and the mechanisms by which murine mast cells activate resting B and T lymphocytes. METHODS: Mouse bone marrow-derived mast cells (BMMCs) or peritoneal mast cells were cocultured with resting splenocytes. Activation of B and T lymphocytes was assessed by measuring cell proliferation, blast formation, and cytokine release. RESULTS: We report that addition of IL-4-treated BMMCs to normal spleen cells resulted within 48 hours in a B- and T-cell activation with substantial amounts of the T(H1) cytokines IFN-gamma and IL-12 and no detectable IL-4. We also demonstrate that mature mast cells in the peritoneal cavity are able to induce spleen cell activation and cytokine release. Addition of antileukocyte function-associated antigen 1 and anti-intercellular adhesion molecule 1 to the cocultures completely abrogates mast cell-induced blast formation and cytokine release. Experiments performed in vivo indicate that spleen cells from mice injected with BMMCs sustain their capacity of proliferation and cytokine production in vitro without any further stimulation. CONCLUSION: These observations suggest that mast cells may exert a helper effect on B and T lymphocytes, initiate T(H1)-type immune responses, and may participate, through this mechanism, in the downregulation of allergic responses.
We have previously described two cytotoxic T lymphocyte clones isolated from lymphocytes infiltrating a human major histocompatibility complex class II-/class I+, CD4+ cutaneous T cell lymphoma. These clones displayed a CD4+CD8dim+ (TC5) and CD4+ CD8- (TC7) phenotype and mediated a specific major histocompatibility complex class I-restricted cytotoxic activity toward Cou-LB autologous tumor cell line. Our studies were performed to elucidate the mechanism involved in T-cell-clone-mediated cytotoxicity and to determine the cytokine profile of both the lymphoma cell line and specific cytotoxic T lymphocyte clones. The results indicate that, despite surface expression of Fas receptor on Cou-LB and Fas ligand induction on TC5 and TC7 cell membranes, the CD4+ cytotoxic T lymphocyte clones do not use this cytotoxic mechanism to lyse their specific target. The TC7 clone uses instead a granzyme-perforin-dependent pathway. Furthermore, quantitative analysis of Th1 and Th2 cytokine mRNA expression in the cutaneous T cell lymphoma cell line as well as in TC5 and TC7 clones indicated that, whereas the tumor cells display a Th2-type profile (interleukin-4, interleukin-6, and interleukin-10), the cytotoxic T lymphocyte clones express Th1-type cytokines (interferon-gamma, granulocyte macrophage colony stimulating factor, and interleukin-2). In addition, preincubation of the tumor-infiltrating lymphocyte clones with autologous tumor cells induced their activation and subsequent amplification of the Th1-type response. These results indicate a direct contribution of the malignant cells in the Th1/Th2 imbalance observed frequently in cutaneous T cell lymphoma patients and suggest their potential role in depressed cell-mediated immunity. Identification of CD4+ Th1-type cytotoxic T lymphocyte clones, the tumor antigen they recognize, and optimization of their cytokine expression profile should be useful for the design of new immunotherapy protocols in cutaneous T cell lymphoma.
We have isolated several cytotoxic T lymphocyte (CTL) clones from lymphocytes infiltrating a human large cell carcinoma (LCC) of the lung. All these clones were found to express a CD3(+), TCRalphabeta(+), CD8(+), CD4(-), CD28(-) phenotype. According to their TCR beta chain variable region expression, they were divided in three major groups. The first group, including the majority of the clones, expressed a unique V(beta)3-J(beta)1.2 TCR. The second group expressed a V(beta)22-J(beta)1.4 rearrangement and the third group, including only two clones, expressed a V(beta)8-J(beta)1.5 TCR. Functional studies showed that all the CTL clones mediated a high cytotoxic activity against the autologous tumor cell line. While the V(beta)3(+) clones showed a weak lysis against few allogeneic non-small cell lung cancer (NSCLC) tumor cell lines, V(beta)8(+) and V(beta)22(+) T cell clones were able to kill a panel of allogeneic NSCLC tumor cell lines. Cytotoxicity-blocking experiments using specific mAb indicated that, while the V(beta)3(+) and V(beta)22(+) CTL clones were HLA-A2 restricted, the V(beta)8(+) clones appeared HLA-B or -C restricted. TCR transcripts expressed in the cloned cells were determined by CDR3 size and sequence analyses, and compared to those present in fresh tumor tissue. Interestingly, our studies demonstrated that the CTL clones identified in vitro were selectively expanded in vivo at the tumor site as compared to autologous peripheral blood lymphocytes. These results further provide evidence that an immune response may take place in NSCLC and that effector T cells may contribute to tumor regression.
Tumor suppressor p53 is a nuclear transcription factor that blocks cell cycle progression and induces apoptosis. We have previously shown that the MCF7 resistance to the cytotoxic action of TNF correlates with p53 mutations. In the present study, we used a recombinant adenovirus carrying a wild-type p53 gene (Adwtp53) in order to investigate the effect of wt p53 transfer on modulation of cell resistance to the cytotoxic action of TNF. Our data indicate that infection of TNF resistant MCF7 cells (1001 and MCF7/Adr) with Adwtp53 resulted in the restoration of wt p53 expression and function as respectively revealed by the yeast assay and the induction of p53 inducible genes MDM2 and p21. Furthermore, the restoration of p53 function significantly sensitized TNF resistant cells to TNF cytotoxic action. This correlated with a significant down-regulation of c-myc in both TNF-resistant cell lines and a decrease of Retinoblastoma protein (Rb) in 1001 clone. In contrast, the effect of p53 seems to be independent from Bcl-2 and Bax protein level regulation. The present study suggests that the combination of TNF and Adwtp53 may be a potential strategy to sensitize mutant p53 TNF-resistant tumors to the cytotoxic action of this cytokine.
Non-small-cell lung cancers (NSCLC) are often infiltrated by T lymphocytes. It is postulated that the presence of tumor-infiltrating lymphocytes (TIL) reflects a local host immune response against autologous tumors. To identify the nature of NSCLC TIL, we have characterized the molecular structure of the TCRbeta chain expressed by infiltrating T cells and paired PBL from 9 untreated patients (4 LLC, 3 ADC and 2 SCC). For this purpose, we have used a high-resolution PCR-based method that determines CDR3 size patterns in TCRVbeta sub-families in fresh tumors and their corresponding autologous PBL samples. Oligoclonality in T-cell populations was observed in 3 (Hor, Bla and Pub) out of 9 tumor biopsies analyzed. In contrast, the TCR repertoire of the 6 following patients as well as of all the autologous PBL was diverse, with virtually all Vbeta specificities expressed. Among the 3 tumors with dominant T-cell clonotypes, relative expansion of some T-cell sub-populations was observed. One patient (Hor) with significant TCRVbeta21 expansion in tumor compared with autologous PBL, showed over-expression of a particular TCRVbeta chain with unique Vbeta21-D-Jbeta2.7 junctional region not detected in autologous PBL. TCRVbeta21/Jbeta2.7 expansion was also observed in IL-2-stimulated TIL cell lines and was confirmed by sequencing analysis of the V-D-J junctional region. These results strengthen the view that local antigen-driven selection may occur, and support the hypothesis that anti-tumor immune response may take place in some NSCLC.
Interleukin-12 (IL-12) is a cytokine that plays a central role in the control of cell-mediated immunity. We have previously shown that transforming growth factor-beta1 (TGF-beta) inhibitory effects on human primary allogeneic cytotoxicity and proliferative responses interfere with IL-12 pathway. The present study was undertaken to further elucidate the biochemical basis of the functional interaction between these two cytokines and to define the site of TGF-beta action on the signaling pathway activated by IL-12. Our data indicate that TGF-beta induced an inhibition of interferon-gamma (IFN-gamma) production without affecting the IL-12Rbeta1 and IL-12Rbeta2 subunits mRNA expression by activated T cells. We further show that TGF-beta has a significant inhibitory effect on the early signal transduction events following interaction of IL-12 with its receptor on activated T cells, resulting in the inhibition of both JAK2 and Tyk2 phosphorylation. In addition, TGF-beta was found to significantly inhibit IL-12-induced phosphorylation of the STAT4 transcription factor. Electrophoretic mobility shift assay indicated that TGF-beta induced a decrease in IL-12-induced STAT4 DNA binding activity in T lymphocytes. This study suggests that TGF-beta influences IL-12 responsiveness at least in part by inhibiting early signaling events essential to gene induction in IL-12-activated T cells.
Several reports indicated that nuclear factor kappaB (NF-kappaB) activation by cytokines, cytotoxic drugs, or ionizing radiation protects cells against apoptosis. Therefore, we investigated the consequence of NF-kappaB inhibition on the efficiency of antineoplastic agents. HPB, HCT116, MCF7, and OVCAR-3 cells stably expressing a dominant negative IkappaBalpha inhibitor showed a decreased NF-kappaB activation following treatment with tumor necrosis factor a and various chemotherapeutic agents. However, there was no difference in survival between parental cells and cells expressing mutated IkappaBalpha. These studies suggest that, at least in these cell lines, stable NF-kappaB inhibition did not modify the response to cytotoxic drugs.
To elucidate further the potential of a Semliki Forest virus (SFV) vector in vivo for gene therapy, we constructed a vector, SFV-IL12, to transfer murine IL-12 genes into tumors. A single intratumoral injection of established B16 murine melanoma with SFV-IL12 resulted in a significant inhibition of tumor growth, while injection with SFV-LacZ had no effect. This antitumoral activity correlated with an increase of IFN gamma production, MIG and IP-10 mRNA expression, both at the tumor site and at the periphery. In contrast, no increase in CTL- or NK cell-mediated cytotoxic response could be detected, ruling out the involvement of T and NK cell cytotoxicity. To determine how the transfer to IL-12 genes induced tumor regression, the antiangiogenic-activity of SFV-IL12 was investigated using Doppler ultrasonography (DUS). SFV-IL12 inhibited in situ neovascularization within the tumor, without affecting the resistance index of pre-existing intratumoral blood flows. In addition, histological analysis of SFV-IL12-treated tumors showed massive tumor necrosis induced by SFV-IL12 treatment. These data indicate that SFV-IL12 inhibits tumor growth through its antiangiogenic activity, demonstrated for the first time in vivo by DUS, and suggest that the SFV vector may be a novel valuable tool in tumor gene transfer.
RATIONALE AND OBJECTIVES: To determine the capacity of color and spectral Doppler ultrasonography (US) to quantify angiogenesis in vivo and to characterize low-resistance intratumor blood flow. METHODS: Thirty-two tumors, xenografted into mice, were studied with Doppler US. The number of intratumor vessels visualized with color Doppler US was compared with the density of microvessels and the number of vessels >100 microm determined by histologic examination. The resistance index and the peak systolic velocities were evaluated. RESULTS: The number of intratumor vessels visualized by color Doppler US was correlated with the number of vessels >100 microm (P<0.001) determined histologically. When vessel density was >30, intratumor vessels were always detected by color Dopper US. The resistance index and peak systolic velocities were significantly lower in intratumor than in peritumor vessels. CONCLUSIONS: Color Doppler US evaluated tumor angiogenesis accurately. Spectral analysis confirmed the low resistance of intratumor blood flow.
In this study we investigated the signalling requirements for TNF-induced cytotoxicity modulated by the methyltransferase inhibitor S-adenosyl-L-homocysteine (AdoHcy) using the TNF-sensitive human breast carcinoma MCF7 cells and its established TNF-resistant clones (R-A1 and clone 1001). Our data indicate that inhibition of methylation reactions by adenosine plus homocysteine, which are known to condense within cells to AdoHcy, markedly potentiated TNF-induced cytotoxicity in MCF7 cells and rendered related TNF-resistant variants, TNF-sensitive by a mechanism independent from the ceramide pathway. We demonstrated that the dominant-negative derivative of FADD (FADD-DN) blocked methylation inhibition/TNF-induced cell death. Moreover, TNF-mediated cytotoxicity modulated by AdoHcy was blocked by the ICE-inhibiting peptide z-VAD-fmk, suggesting that an ICE-like protease is required for the methylation inhibition/TNF-inducible death pathway. In conclusion, these results suggest that the methyltransferase inhibitor AdoHcy potentiates TNF-induced cytotoxicity in MCF7 cells and renders TNF-resistant MCF7 clones, TNF-sensitive via the ceramide independent pathway and that FADD and the ICE-like protease are likely necessary components in transducing methylation inhibition/TNF signals for cell death.
We have examined the influence of the immunosuppressive cytokine TGF-beta on NK receptor expression by T lymphocytes upon allogeneic activation. Using the primary mixed lymphocyte reaction (MLR), our data show that allostimulation induced the expression of CD94/NKG2-A on alloactivated CD8+ T cells. This expression was increased in the presence of TGF-beta whereas IL-15 had no significant effect. The blockage of CD94 and NKG2-A resulted in increased lysis of targets by alloactivated cytotoxic T cells. This increase was dependent on the activation state of T cells. Using PCR, we also demonstrated that TGF-beta had no effect on the transcription of non-inhibitory NKG2 molecules. The present results show that allostimulation can induce CD94 and further point out the role of TGF-beta in the induction of the CD94/NKG2-A receptor on alloactivated T cells.
We have investigated the interleukin-12 (IL-12) and tumor necrosis factor-alpha (TNFalpha)-induced regulation of human natural killer (NK) cell function and their relationship with nitric oxide (NO) generation. We demonstrate that both cytokines were efficient to trigger the transcription of the inducible nitric oxide synthase (iNOS) mRNA, as detected by reverse transcriptase-polymerase chain reaction (RT-PCR). Western blot analysis and intracytoplasmic fluorescence showed that iNOS protein was also induced by both cytokines. However, our data indicate that NO does not play a significant role in the effector phase of the cytotoxic activity mediated by NK-stimulated cells, inasmuch as the lytic activity was not affected in the presence of specific NO synthase inhibitors. When aminoguanidine (AMG), an inhibitor of iNOS, was added during the afferent phase of NK stimulation with IL-12 and TNFalpha, a subsequent increase in the lytic potential of the effector cells towards the NK-sensitive target cells (K562) and lymphokine-activated killer (LAK) target cells (Daudi) was observed. Conversely, the addition of chemical NO donors during the afferent step resulted in a dose-dependent inhibition of the NK and LAK cytotoxicity. Our data suggest that the enhancement of NK-cell cytotoxic activity resulting from iNOS inhibition may be correlated, at least in part, to an increase in interferon-gamma production and granzyme B expression.
For understanding the local immune response in human non-small cell lung cancer (NSCLC), we investigated both Th1 and Th2-type as well as TGF-beta1 cytokine mRNA expression in 10 fresh tumor biopsies, the corresponding tumor and short term TIL cell lines as well as patient PBMC. A methodology based on a highly sensitive quantitative RT-PCR was used. We found that IL-6 mRNA was highly expressed in all tumor biopsy samples analyzed (4 LLC, 3 ADC and 3 SCC). IL-10 mRNA was expressed in 7 of 10 biopsies whereas IL-4 mRNA expression was moderate. Analysis of type I cytokines revealed a low expression level of IL-2 mRNA, while IFNgamma and GM-CSF expression was high in the majority of the tumor lesions studied. Quantitatively, high amounts of Th2-type cytokine mRNA were detected at the tumor site with IL-6 as the predominant lymphokine. A high mRNA expression level of the immunosuppressive cytokine TGF-beta1 was observed in all NSCLC. To identify the cell types responsible for the production of TGF-beta1, IL-6, IL-10 and GM-CSF at the tumor site, tumor and TIL cell lines were derived from the corresponding biopsies. All the 3 tumor cell lines analysed were found to express high amount of TGF-beta1 but not IL-10 mRNA, 2 expressing IL-6 and GM-CSF. Five short term TIL cell lines established in the presence of IL-2 expressed high level of IL-10, IL-4 and IFNgamma but not IL-2 mRNA. Strikingly, high expression of IL-10 mRNA was also observed in all 6 patient PBMC analyzed as compared to controls. Together, our results indicate the existence of a local and peripheral Th-2-type cytokine pattern in patients bearing NSCLC.