Mechanism of melphalan-induced B7-1 gene expression in P815 tumor cells

The utility of urinary CD80 as a diagnostic marker in patients with renal diseases

CD80, which regulates T cell activation, may provide a differential diagnostic marker between minimal change disease (MCD) and other renal diseases, including focal segmental glomerular sclerosis (FSGS). However, recent reports show contrasting results. Therefore, we evaluated the utility of urinary CD80 as a diagnostic biomarker. We collected 65 urine samples from 55 patients with MCD (n = 31), FSGS (n = 4), inherited nephrotic syndrome (n = 4), Alport syndrome (n = 5) and other glomerular diseases (n = 11), and control samples (n = 30). We measured urinary CD80 levels by ELISA. Urinary CD80 (ng/gCr) (median, interquartile range) levels were significantly higher in patients with MCD in relapse (91.5, 31.1-356.0), FSGS (376.2, 62.7-1916.0), and inherited nephrotic syndrome (220.1, 62.9-865.3), than in patients with MCD in remission (29.5, 21.7-52.8) (p < 0.05). Elevation of urinary CD80 was observed, even in patients with inherited nephrotic syndrome unrelated to T cell activation. Additionally, urinary CD80 was positively correlated with urinary protein levels. Our results suggest that urinary CD80 is unreliable as a differential diagnostic marker between MCD in relapse and FSGS or inherited kidney diseases. Increased urinary CD80 excretion was present in all patients with active kidney disease.

TLR-mediated albuminuria needs TNFα-mediated cooperativity between TLRs present in hematopoietic tissues and CD80 present on non-hematopoietic tissues in mice

Transient albuminuria induced by pathogen-associated molecular patterns (PAMPs) in mice through engagement of Toll-like receptors (TLRs) is widely studied as a partial model for some forms of human nephrotic syndrome (NS). In addition to TLRs, CD80 has been shown to be essential for PAMP-mediated albuminuria. However, the mechanistic relationships between TLRs, CD80 and albuminuria remain unclear. Here, we show that albuminuria and CD80-uria induced in mice by many TLR ligands are dependent on the expression of TLRs and their downstream signalling intermediate MyD88 exclusively in hematopoietic cells and, conversely, on CD80 expression exclusively in non-hematopoietic cells. TNFα is crucial for TLR-mediated albuminuria and CD80-uria, and induces CD80 expression in cultured renal podocytes. IL-10 from hematopoietic cells ameliorates TNFα production, albuminuria and CD80-uria but does not prevent TNFα-mediated induction of podocyte CD80 expression. Chitohexaose, a small molecule originally of parasite origin, mediates TLR4-dependent anti-inflammatory responses, and blocks TLR-mediated albuminuria and CD80-uria through IL-10. Thus, TNFα is a prominent mediator of renal CD80 induction and resultant albuminuria in this model, and small molecules modulating TLR-mediated inflammatory activation might have contributory or adjunct therapeutic potential in some contexts of NS development.

Summary: Systemic TNFα mediates myeloid cell and podocyte cross-talk to cause LPS-induced mouse microalbuminuria, a partial model of human nephrotic syndrome, pointing to potential adjunct therapeutic approaches.

Chemotherapy and Oncolytic Virotherapy: Advanced Tactics in the War against Cancer

Cancer is a traitorous archenemy that threatens our survival. Its ability to evade detection and adapt to various cancer therapies means that it is a moving target that becomes increasingly difficult to attack. Through technological advancements, we have developed sophisticated weapons to fight off tumor growth and invasion. However, if we are to stand a chance in this war against cancer, advanced tactics will be required to maximize the use of our available resources. Oncolytic viruses (OVs) are multi-functional cancer-fighters that can be engineered to suit many different strategies; in particular, their retooling can facilitate increased capacity for direct tumor killing (oncolytic virotherapy) and elicit adaptive antitumor immune responses (oncolytic immunotherapy). However, administration of these modified OVs alone, rarely induces successful regression of established tumors. This may be attributed to host antiviral immunity that acts to eliminate viral particles, as well as the capacity for tumors to adapt to therapeutic selective pressure. It has been shown that various chemotherapeutic drugs with distinct functional properties can potentiate the antitumor efficacy of OVs. In this review, we summarize the chemotherapeutic combinatorial strategies used to optimize virally induced destruction of tumors. With a particular focus on pharmaceutical immunomodulators, we discuss how specific therapeutic contexts may alter the effects of these synergistic combinations and their implications for future clinical use.

Reactive oxygen species- and DNA damage response-dependent NK cell activating ligand upregulation occurs at transcriptional levels and requires the transcriptional factor E2F1

Increasing evidence indicates that cancer cell stress induced by chemotherapeutic agents promote antitumor immune responses and contribute to their full clinical efficacy. In this article, we identify the signaling events underlying chemotherapy-induced NKG2D and DNAM-1 ligand expression on multiple myeloma (MM) cells. Our findings indicate that sublethal doses of doxorubicin and melphalan initiate a DNA damage response (DDR) controlling ligand upregulation on MM cell lines and patient-derived malignant plasma cells in Chk1/2-dependent and p53-independent manner. Drug-induced MICA and PVR gene expression are transcriptionally regulated and involve DDR-dependent E2F1 transcription factor activity. We also describe the involvement of changes in the redox state in the control of DDR-dependent upregulation of ligand surface expression and gene transcriptional activity by using the antioxidant agent N-acetyl-L-cysteine. Finally, in accordance with much evidence indicating that DDR and oxidative stress are major determinants of cellular senescence, we found that redox-dependent DDR activation upon chemotherapeutic treatment is critical for MM cell entry in premature senescence and is required for the preferential ligand upregulation on senescent cells, which are preferentially killed by NK cells and trigger potent IFN-γ production. We propose immunogenic senescence as a mechanism that promotes the clearance of drug-treated tumor cells by innate effector lymphocytes, including NK cells.

Chemoimmunotherapy: reengineering tumor immunity

Cancer chemotherapy drugs have long been considered immune suppressive. However, more recent data indicate that some cytotoxic drugs effectively treat cancer in part by facilitating an immune response to the tumor when given at the standard dose and schedule. These drugs induce a form of tumor cell death that is immunologically active, thereby inducing an adaptive immune response specific for the tumor. In addition, cancer chemotherapy drugs can promote tumor immunity through ancillary and largely unappreciated immunologic effects on both the malignant and normal host cells present within the tumor microenvironment. These more subtle immunomodulatory effects are dependent on the drug itself, its dose, and its schedule in relation to an immune-based intervention. The recent approvals of two new immune-based therapies for prostate cancer and melanoma herald a new era in cancer treatment and have led to heightened interest in immunotherapy as a valid approach to cancer treatment. A detailed understanding of the cellular and molecular basis of interactions between chemotherapy drugs and the immune system is essential for devising the optimal strategy for integrating new immune-based therapies into the standard of care for various cancers, resulting in the greatest long-term clinical benefit for cancer patients.

Chemoimmunotherapy

Cancer chemotherapy drugs are historically regarded as detrimental to immunity because of their myelosuppressive effects. However, accumulating data suggest that the antitumor activity of conventional cancer chemotherapy results in part from its ability to harness the innate and adaptive immune systems by inducing immunologically active tumor cell death. Additional data broaden the immunologic effect of cancer chemotherapy drugs, demonstrating that some drugs have the ability to disrupt pathways of immune suppression and immune tolerance in a manner that depends on the drug dose, and the timing of its administration in relation to immunotherapy. Understanding the cellular and molecular basis of the interactions between chemotherapy drugs and the immune system will facilitate the strategic development of chemoimmunotherapy treatment regimens that both maximize tumor regression and the antitumor immune response for the long-term clinical benefit of cancer patients.

p65 Negatively regulates transcription of the cyclin E gene

NF-kappaB family members play a pivotal role in many cellular and organismal functions, including the cell cycle. As an activator of cyclin D1 and p21(Waf1) genes, NF-kappaB has been regarded as a critical modulator of cell cycle. To study the involvement of NF-kappaB in G(1)/S phase regulation, the levels of selected transcriptional regulators were monitored following overexpression of NF-kappaB or its physiological induction by tumor necrosis factor-alpha. Cyclin E gene was identified as a major transcriptional target of NF-kappaB. Recruitment of NF-kappaB to the cyclin E promoter was correlated with the transrepression of cyclin E gene. Ligation-mediated PCR and micrococcal nuclease-Southern assays suggested the nucleosomal nature of this region while chromatin immunoprecipitation analysis confirmed the exchange of cofactors following tumor necrosis factor-alpha treatment or release from serum starvation. There was a progressive reduction in cyclin E transcription along with the accumulation of catalytically inactive cyclin E-cdk2 complexes and arrest of cells in G(1)/S-phase. Thus, our study clearly establishes NF-kappaB as a negative regulator of cell cycle through transcriptional repression of cyclin E.

Rituximab combined with a small dose of melphalan for a refractory follicular lymphoma patient

A 48-year-old male patient with follicular lymphoma, grade II, stage IV, was treated with CHOP, ESHAP and MACOP-B, resulting in partial remission. After 9 months, the disease progressed and several chemotherapy agents, including three courses of rituximab combined with etoposide, sobuzoxane or methotrexate, only resulted in a stable disease response. However, the fourth course of rituximab combined with a small dose of melphalan produced excellent results and the complete response continued for more than 15 months. It is possible that these two drugs may act synergistically.

Graft rejection occurring in post-liver transplant patients receiving cytotoxic chemotherapy: a case series

Liver transplant recipients are known to be at increased risk for the development of de novo neoplasms or the recurrence of preexisting malignancies, and this is possibly related to the use of immunosuppressive medication. Little is known about the effects of cytotoxic chemotherapy on graft function after transplantation. A retrospective chart and pathology database review was undertaken to identify post-liver transplant patients developing rejection during chemotherapy. All liver biopsies were reviewed by a hepatopathologist. Three patients were identified. All patients were diagnosed with cancer within 7 years of liver transplantation; two-thirds died soon after the diagnosis of malignancy. Rejection occurred soon after chemotherapy was started. All patients were receiving prednisone and tacrolimus (trough levels: 2.1-4.8 ng/mL). One patient developed plasma cell hepatitis (de novo autoimmune hepatitis). There was no histologic evidence of hepatotoxicity due to the chemotherapeutic agents. Cytotoxic chemotherapy should be used in liver transplant recipients with caution, and immunosuppressant doses should be maintained at therapeutic levels, as patients may be at risk for allograft rejection. Treatment of rejection or plasma cell hepatitis in this setting should be undertaken in a timely and aggressive fashion to prevent chronic ductopenic rejection.

Chemotherapy and tumor immunity: an unexpected collaboration

Chemotherapy directly targets the transformed tumor cell, and has long been a key component of therapy for most early and advanced cancers. However, its utility is ultimately limited by unavoidable toxicity to normal tissues, and by drug resistance pathways deeply embedded within the biology of the tumor cell itself. These limitations strongly argue for innovative strategies to treat and manage cancer. Engaging the power of the patient's own immune system is a highly attractive way to complement the activity of standard cancer treatment. Tumor vaccines offer the potential for preventing cancer in those at high risk for disease development, preventing relapse in those diagnosed with early cancer, and treating advanced disease. Notably, the barriers to tumor vaccine efficacy are distinct from the limitations of combination chemotherapy. The ability of vaccines to induce a response robust enough to mediate tumor rejection is limited by the extent of disease burden, the suppressive effect of the local tumor micronenvironment, and multiple layers of systemic immune tolerance established to keep the immune response turned off. Chemotherapy can be used with tumor vaccines in unexpected ways, breaking down these barriers and unleashing the full potential of the antitumor immune response.

Decoding dangerous death: how cytotoxic chemotherapy invokes inflammation, immunity or nothing at all

Chemotherapy and immunotherapy can be either synergistic or antagonistic modalities in the treatment of cancer. Cytotoxic chemotherapy not only affects the tumor but also targets dividing lymphocytes, the very cells that are required to develop an immune response. For this reason, chemo- and immunotherapy have been seen as antagonistic. However, cell death can be immunogenic and the way in which chemotherapeutic drug kills a tumor cell is likely to be an important determinant of how that dying cell interacts with the immune system and whether the interaction will lead to an immune response. When a cell dies as the result of infection, the immune system responds rapidly and the system of Toll-like receptors (TLR) plays a key role in this process. In this review, we will briefly summarize the intracellular signaling pathways that link TLR ligation with immune activation and we will address the questions where and how TLRs recognize their targets.

Regulation of Transcript Elongation through Cooperative and Ordered Recruitment of Cofactors

We studied the regulation of murine CD80, a gene whose basal transcriptional status was characterized by the presence of a stalled RNA polymerase II complex on the promoter-proximal region. Stimulus-induced activation of productive elongation involved a complex interplay of regulated events that included a synergy between ordered cofactor recruitment. This cascade of recruitments was initiated through the engagement of transcription factor NF-kappaB, leading to the temporal association of histone acetyltransferases and the consequent selective acetylation of a transcription start site downstream nucleosome. This in turn culminated into the nucleosomal association of Brd4-associated P-TEFb, a protein complex containing kinase specific for serine 2 of Rbp 1, the largest subunit of the carboxyl-terminal domain of RNA polymerase II. The consequent phosphorylation of serine 2 residues in CTD by CDK9 in the P-TEFb complex then facilitated escape of polymerase II into the productive elongation phase. Thus, the cooperative mechanisms that integrate between independent pathways characterize regulation of the elongation step of transcription, thereby providing another level at which specificity of gene regulation can be achieved.

Alkylating drugs applied in non-cytotoxic doses as a novel compounds targeting inflammatory signal pathway

Alkylating drugs (ADs) belonging to the nitrogen mustard family are commonly used as cytostatic and immunosuppressive agents. Our previous in vitro studies demonstrated that in the case of gradual dose decrease, the number of targets for alkylation in the cell is also reduced and the drug switches from brutal cytostatic to cell growth modifier. At doses of 0.3 microg/ml and lower, the effects of ADs are no longer associated with DNA damage or stress/MAPK pathways activation. Instead, the disruption of signal transduction by the IL-2beta and/or TNFalpha cell surface receptors is observed. As a result, ADs in the doses 100-fold lower than cytostatic ones are capable to modify lymphocyte activity including the activity of regulatory T cells. We hypothesized that ADs may have a beneficial effect in the treatment of inflammatory diseases. Indeed, the application of non-cytotoxic doses of an AD melphalan reduces the severity of murine experimental colitis. Daily administration of melphalan (25 microg/kg body weight) markedly reduced the severity of DSS-colitis as determined by clinical and histological criteria. Moreover, the beneficial effect of melphalan was also shown in asthmatic patients. In 60% of these patients histological and ultrastructural signs of bronchial epithelium regeneration were also revealed. Thus, ADs at non-cytotoxic concentrations exert beneficial effect both in acute and chronic inflammatory diseases. Such anti-inflammatory activity is thought to be due to blocking of signal transduction through various cell surface receptor including IL-2R and TNFR. Consequently different steps of inflammatory cascade turn out to be inhibited.

Importance of signaling via the IFN-alpha/beta receptor on host cells for the realization of the therapeutic benefits of cyclophosphamide for mice bearing a large MOPC-315 tumor

Here we show that low-dose cyclophosphamide (CY), that depends for its therapeutic effectiveness on the immunopotentiating activity of the drug for T cell-mediated tumor-eradicating immunity, is curative for approximately 80% of wild-type (WT) mice bearing a large s.c. MOPC-315 tumor, but only for approximately 10% of IFN-alpha/betaR-/- mice bearing a large s.c. MOPC-315 tumor. Histopathological examination of the s.c. tumors of such mice on day 4 after the chemotherapy revealed that the low dose of CY led to accumulation of T lymphocytes in both the WT and the IFN-alpha/betaR-/- mice. However, in the CY treated tumor bearing WT mice the T lymphocytes were present throughout the tumor mass and in direct contact with tumor cells, but in the CY treated tumor bearing IFN-alpha/betaR-/- mice most of the T lymphocytes remained in blood vessels. In addition to being important for CY-induced transendothelial migration of T lymphocytes into the tumor mass, we show here that signaling via the IFN-alpha/betaR is also important for CY-induced control of metastatic tumor progression in the spleen and liver of the tumor bearing mice. Finally, CY cured tumor bearing WT mice were resistant to a subsequent challenge with MOPC-315 tumor cells, but the few CY cured tumor bearing IFN-alpha/betaR-/- mice were not. Thus, signaling via the IFN-alpha/betaR on host cells in MOPC-315 tumor bearers is important for CY-induced: (a) transendothelial migration of T lymphocytes into the tumor mass and the eradication of the primary tumor, (b) control of metastatic tumor progression, and (c) resistance to a subsequent tumor challenge.

The nitrogen mustard melphalan activates mitogen-activated phosphorylated kinases (MAPK), nuclear factor-kappaB and inflammatory response in lung epithelial cells

To investigate how respiratory epithelial cells react to an alkylating agent, we exposed human bronchial (BEAS-2B) and alveolar (A549) cells to the nitrogen mustard derivative melphalan. The BEAS-2B cells were highly sensitive to melphalan, as shown by a reduced viability after a 10-min incubation with 300 microM melphalan. The A549 cells were less sensitive and required several hours of exposure to reduce significantly in viability. However, exposure to melphalan also induces activation of intracellular signal transduction pathways, as indicated by phosphorylation of extracellular signal-regulated kinase (ERK1/2) and p38 (proteins belonging to the family of stress-induced mitogen-activated phosphorylated kinases, MAPK) within 5 min, as well as translocation of the transcription factor nuclear factor (NF)-kappaB to the nucleus within 45 min. This early activation was followed by elevated levels of tumor necrosis factor (TNF)-alpha mRNA within 2 h. We also observed increased expression of intercellular adhesion molecule-1 (ICAM-1) on the surface of both cell lines 18 h after exposure to 25 microM melphalan and an increased adhesion of monocytes to the epithelial cells in vitro.In conclusion, we have demonstrated that alkylating compounds not only cause cell death of lung epithelial cells but also activate stress-associated MAPK signal transduction pathways and induce expression of mediators known to participate in the recruitment of inflammatory cells.

Apoptotic and necrotic cells induced by different agents vary in their expression of MHC and costimulatory genes

We have recently reported, in a murine tumor model, that apoptotic cells induced by different agents may vary in their ability to elicit host immunity. The basis for this observation is unclear but may involve varying efficiencies of cross-presentation and/or direct activation of immunity by different apoptotic preparations. As a first step in addressing this issue, we compared expression patterns of selected immune genes (MHC class I, class II, CD40, B7-1, B7-2) on viable and apoptotic populations induced by four different agents. The histone deacetylase inhibitor trichostatin A (TSA) induced MHC class II expression on viable and apoptotic cell populations, while LPAM, H2O2 and gamma-irradiation did not activate class II. Each agent employed elicited a different expression pattern of costimulatory molecules (CD40, B7-1, B7-2) on both apoptotic and 7-AAD+ 'necrotic' populations. In striking contrast to the TSA induction of MHC class II, class I cell surface protein was diminished on the apoptotic populations. These effects were not a result of changes in the cell cycle produced by the various treatments. The data demonstrate that distinctive gene expression patterns on viable and apoptotic cells are elicited by different apoptosis inducing agents. We discuss how expression patterns on dead or dying tumor cells could potentially affect the tumor's ability to elicit immunity.

Cytosine arabinoside induces costimulatory molecule expression in acute myeloid leukemia cells

Chemotherapeutic drugs kill cancer cells mainly by direct cytotoxicity, but they might also induce a stronger host immune response by causing the tumor to produce costimulatory cell surface molecules like CD80. We previously reported that in myeloid leukemic cells, gamma-irradiation induced CD80 expression. In this study, we show that cytosine arabinoside (Ara-C), even at low doses, induced CD80 expression in vitro in mouse DA1-3b leukemic cells, by a mechanism that involved reactive oxygen species. In vivo experiments in the mouse DA1-3b/C3H whole-animal acute myeloid leukemia (AML) model showed that injection of Ara-C induced expression of CD80 and CD86, and decreased expression of B7-H1, indicating that chemotherapy can modify costimulatory molecule expression in vivo, in a way not necessarily observed in vitro. Mouse leukemic cells exposed in vivo to Ara-C were more susceptible to specific cytotoxic lymphocyte (CTL)-mediated killing. Ara-C also induced CD80 or CD86 expression in 14 of 21 primary cultured human AML samples. In humans being treated for AML, induction chemotherapy increased CD86 expression in the leukemic cells. These findings indicate possible synergistic strategies between CTL-based immunotherapy and chemotherapy for treatment. They also suggest an additional mechanism by which chemotherapy can eradicate AML blasts.

Irradiation up-regulates CD80 expression through two different mechanisms in spleen B cells, B lymphoma cells, and dendritic cells

We have previously demonstrated irradiation-induced up-regulation of CD80 expression in A20-HL B lymphoma cells by inducing expression of tumour necrosis factor-alpha (TNF-alpha) and CD154. In the present study, we investigated whether irradiation also up-regulates CD80 expression in mouse spleen B cells. Because freshly prepared spleen B cells are highly sensitive to irradiation, we employed spleen B cells stimulated with lipopolysaccharide (LPS-B cells). X-irradiation (8 Gy) followed by incubation (9-12 hr) highly and selectively up-regulated CD80 expression in LPS-B cells, whereas the same treatment slightly increased expression of CD54 and did not affect expression of CD86, major histocompatibility complex class II, CD11a or surface immunoglobulin M. The irradiation-induced up-regulation of CD80 expression resulted in enhanced APC function of LPS-B cells. Up-regulation of CD80 expression on LPS-B cells was accompanied by an increase in CD80 mRNA accumulation and nuclear factor (NF)-kappaB activation. Activation of NF-kappaB was shown to be critical for up-regulation of CD80 expression as pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF-kappaB, severely decreased the observed up-regulation. X-irradiation of LPS-B cells induced expression of TNF-alpha but not CD154. However, anti-TNF-alpha monoclonal antibody (mAb) with anti-CD154 mAb did not inhibit X-irradiation-induced up-regulation of CD80 expression in LPS-B cells, whereas these mAbs almost completely inhibited this up-regulation in A20-HL cells and bone marrow-derived dendritic cells (DCs). In contrast, a thiol antioxidant, N-acetyl-l-cysteine, completely blocked X-irradiation-induced up-regulation of CD80 expression in LPS-B cells, but not in A20-HL cells or in DCs. Based on these findings, we concluded that X-irradiation up-regulates CD80 expression not only in A20-HL cells and DCs but also in LPS-B cells, and that this up-regulation in LPS-B cells via NF-kappaB activation is dependent on the generation of reactive oxygen species, while that in A20-HL cells and DCs is not.

Induction of B7-1 in podocytes is associated with nephrotic syndrome

Kidney podocytes and their slit diaphragms form the final barrier to urinary protein loss. This explains why podocyte injury is typically associated with nephrotic syndrome. The present study uncovered an unanticipated novel role for costimulatory molecule B7-1 in podocytes as an inducible modifier of glomerular permselectivity. B7-1 in podocytes was found in genetic, drug-induced, immune-mediated, and bacterial toxin-induced experimental kidney diseases with nephrotic syndrome. The clinical significance of our results is underscored by the observation that podocyte expression of B7-1 correlated with the severity of human lupus nephritis. In vivo, exposure to low-dose LPS rapidly upregulates B7-1 in podocytes of WT and SCID mice, leading to nephrotic-range proteinuria. Mice lacking B7-1 are protected from LPS-induced nephrotic syndrome, suggesting a link between podocyte B7-1 expression and proteinuria. LPS signaling through toll-like receptor-4 reorganized the podocyte actin cytoskeleton in vitro, and activation of B7-1 in cultured podocytes led to reorganization of vital slit diaphragm proteins. In summary, upregulation of B7-1 in podocytes may contribute to the pathogenesis of proteinuria by disrupting the glomerular filter and provides a novel molecular target to tackle proteinuric kidney diseases. Our findings suggest a novel function for B7-1 in danger signaling by nonimmune cells.

Induction of B7-1 in podocytes is associated with nephrotic syndrome

Kidney podocytes and their slit diaphragms form the final barrier to urinary protein loss. This explains why podocyte injury is typically associated with nephrotic syndrome. The present study uncovered an unanticipated novel role for costimulatory molecule B7-1 in podocytes as an inducible modifier of glomerular permselectivity. B7-1 in podocytes was found in genetic, drug-induced, immune-mediated, and bacterial toxin-induced experimental kidney diseases with nephrotic syndrome. The clinical significance of our results is underscored by the observation that podocyte expression of B7-1 correlated with the severity of human lupus nephritis. In vivo, exposure to low-dose LPS rapidly upregulates B7-1 in podocytes of WT and SCID mice, leading to nephrotic-range proteinuria. Mice lacking B7-1 are protected from LPS-induced nephrotic syndrome, suggesting a link between podocyte B7-1 expression and proteinuria. LPS signaling through toll-like receptor-4 reorganized the podocyte actin cytoskeleton in vitro, and activation of B7-1 in cultured podocytes led to reorganization of vital slit diaphragm proteins. In summary, upregulation of B7-1 in podocytes may contribute to the pathogenesis of proteinuria by disrupting the glomerular filter and provides a novel molecular target to tackle proteinuric kidney diseases. Our findings suggest a novel function for B7-1 in danger signaling by nonimmune cells.

Chemotherapy increases transgene expression in leukemic cells

BACKGROUND

Patients with acute myeloid leukemia (AML) often obtain complete remission with chemotherapy but the majority of patients relapse. Combining chemotherapy and gene therapy appears to be a promising approach; however, the effects of chemotherapy on transgene expression in leukemic cells have not yet been investigated.

METHODS

DA1-3b leukemic cells were transfected with pCDNA3 plasmids carrying GM-CSF or LacZ cDNA. The leukemic K562 cell line and primary cultured AML cells were transduced with an Ad5.CMV-LacZ adenoviral vector. Cells were then incubated with various concentrations of daunorubicin (DNR) and cytosine arabinoside (Ara-C), and expression of the transgene was measured. Murine DA1-3b-pCDNA3/LacZ leukemic cells were also injected into syngeneic C3H/Hej mice.

RESULTS

In the cells carrying pCDNA3, DNR and Ara-C dramatically increased expression of the LacZ and GM-CSF transgenes. Over-expression depended on drug dose and was due to increased transcription. Enhancement was also observed in K562 cells and in some primary cultured AML samples transduced with the Ad5.CMV-LacZ adenovirus. Addition of N-acetyl-L-cysteine inhibited the over-expression, suggesting that reactive oxygen species were involved in activating the CMV promoter. In the A549 lung carcinoma cell line transduced with Ad5.CMV-LacZ, Ara-C had only a minor effect, and DNR had a detrimental effect, suggesting that expression depends on cell type. In vivo experiments in which mice received DA1-3b-pCDNA3/LacZ leukemic cells, and were then treated with Ara-C, also showed increased transgene expression in these leukemic cells.

CONCLUSIONS

In leukemic cells, chemotherapeutic agents can induce over-expression of transgenes. This suggests a promising combined strategy for the treatment of acute leukemia.

Protection of islets by in situ peptide-mediated transduction of the Ikappa B kinase inhibitor Nemo-binding domain peptide

We have previously demonstrated that adenoviral gene transfer of the NF-kappaB inhibitor IkappaB to human islets results in protection from interleukin (IL)-1beta-mediated dysfunction and apoptosis. Here we report that human and mouse islets can be efficiently transduced by a cationic peptide transduction domain (PTD-5) without impairment of islet function. PTD mediated delivery of a peptide inhibitor of the IL-1beta-induced IkappaB kinase (IKK), derived from IKKbeta (NBD; Nemo-binding domain), and completely blocked the detrimental effects of IL-1beta on islet function and NF-kappaB activity, in a similar manner to Ad-IkappaB. We also demonstrate that mouse islets can be transduced in situ by infusion of the transduction peptide through the bile duct prior to isolation, resulting in 40% peptide transduction of the beta-cells. Delivery of the IKK inhibitor transduction fusion peptide (PTD-5-NBD) in situ to mouse islets resulted in improved islet function and viability after isolation. These results demonstrate the feasibility of using PTD-mediated delivery to transiently modify islets in situ to improve their viability and function during isolation, prior to transplantation.

The biologic role for nuclear factor-kappaB in disease and its potential involvement in mucosal injury associated with anti-neoplastic therapy

Oral mucosal barrier injury (mucositis) is a frequent, painful, serious, dose-limiting toxicity associated with many anti-neoplastic drugs and radiation to the head and neck. Results of recent studies suggest that mucositis is the result of a complex series of interactive biological events that take place in the submucosa and epithelium. The nuclear transcription factor NF-kappaB has been implicated in the control of a broad range of biological responses, the activation of a large number of specific cellular genes, and the determination of the fate of cells exposed to ionizing radiation and anti-neoplastic drugs. Of particular importance to mucositis is the fact that NF-kappaB regulates key elements in the apparent sequence that leads to normal tissue toxicity. Not the least of these is the effect that NF-kappaB activation has on apoptosis. In particular, a paradox exists between the potential pro-apoptotic effect NF-kappaB exerts on normal cells, and the anti-apoptotic and cytoprotective effect it causes in tumor cells. This paper provides a review of the structure and function of NF-kappaB and speculates how its apparent enigmatic effect on normal and tumor cells may occur.

Irradiation up-regulates CD80 expression through induction of tumour necrosis factor-alpha and CD40 ligand expression on B lymphoma cells

Previously, we reported that 100 Gy X-ray irradiation followed by 24 hr incubation up-regulates CD80 expression in murine B lymphoma cells, A20-2J. In the present study, we analysed the underlying mechanisms of such up-regulation using A20-HL cells derived from A20-2J cells. Irradiation of A20-HL cells with 100 Gy enhanced CD80 expression. Incubation of untreated A20-HL cells with those 100 Gy irradiated induced up-regulation of CD80 expression. Irradiation of A20-HL cells also up-regulated the expression of tumour necrosis factor-alpha (TNF-alpha) and CD40 ligand (CD40L), and the amount of immunoprecipitable TNF-alpha and CD40L in cell lysates. The addition of anti-TNF-alpha or anti-CD40L monoclonal antibody (mAb) to the incubation of irradiated A20-HL cells partially inhibited up-regulation of CD80 expression, and the addition of both antibodies together almost completely inhibited the up-regulation, suggesting that irradiation up-regulated the CD80 expression through the induction of TNF-alpha and CD40L expression. Irradiation also increased the accumulation of CD80, TNF-alpha and CD40L mRNA. n-tosyl-l-phenylalanine chloromethyl ketone (TPCK), a nuclear factor (NF)-kappaB inhibitor, markedly decreased irradiation-induced accumulation of CD80 mRNA and CD80 expression. FK506, a calcineurin inhibitor, and nifedipine, a calcium channel inhibitor, inhibited not only the expression of TNF-alpha and CD40L, but also the up-regulation of CD80 on irradiated A20-HL cells. These results strongly suggested that irradiation induced TNF-alpha and CD40L expression, which then up-regulated CD80 mRNA and CD80 expression through activation of NF-kappaB transcription factor in A20-HL cells.

Melphalan-induced expression of IFN-beta in MOPC-315 tumor-bearing mice and its importance for the up-regulation of TNF-alpha expression

We have previously shown that administration of a low-dose of melphalan (L-phenylalanine mustard; L-PAM) to mice bearing a large s.c. MOPC-315 tumor leads to up-regulation of TNF-alpha expression, which is first evident at the mRNA level at 24 h after the chemotherapy. In this study, we show accumulation of IFN-beta mRNA in the spleen and tumor nodule of such mice as early as 1 h after the chemotherapy followed by elevated production of IFN-beta protein. IFN-beta protein in turn was found to be important for the L-PAM-induced up-regulation of TNF-alpha expression, as neutralization of IFN-beta inhibited the L-PAM-induced up-regulation of TNF-alpha mRNA expression in MOPC-315 tumor cells. In addition, L-PAM failed to up-regulate TNF-alpha expression in spleen cells from mice in which signaling by IFN-beta is deficient. Studies into the mechanism through which L-PAM leads to rapid accumulation of IFN-beta mRNA revealed that it requires de novo RNA synthesis, indicating that the regulation is at the transcriptional level. However, it did not require de novo protein synthesis, indicating that activation of pre-existing transcription factors is sufficient for IFN-beta gene expression. The L-PAM-induced accumulation of IFN-beta mRNA was mimicked with H(2)O(2) and was prevented with the antioxidant N-acetyl-L-cysteine, indicating that reactive oxygen species are involved in the transcriptional regulation of L-PAM-induced IFN-beta gene expression. Thus, the IFN-beta gene is an early response gene that is activated in response to L-PAM via a pathway that involves reactive oxygen species, and IFN-beta in turn plays an important role in L-PAM-induced TNF-alpha up-regulation.