Dual inhibition of KIF11 and BCL2L1 induces apoptosis in lung adenocarcinoma cells.

EGFR-mutant lung adenocarcinoma (LUAD) mostly depends on EGFR for survival and consequently responds well to EGFR inhibitors. However, resistance to the drugs develops almost universally during treatment. We previously demonstrated that EGFR-mutant LUAD cell lines, HCC827 and H1975, have subpopulations of cells, which we termed HCC827 GR2 and H1975 WR7 cells, that can thrive independently of EGFR signaling. These EGFR-independent EGFR-mutant cancer cells are difficult to treat because they lack sensitivity to EGFR inhibitors. Therefore, the development of novel strategies to target EGFR-independent EGFR-mutant LUAD is particularly important. We found that high expression of kinesin family member 11 (KIF11) correlated with poor survival in patients with LUAD. We also observed that KIF11 silencing caused cell cycle arrest at G2/M in HCC827 GR2 and H1975 WR7 cells. Furthermore, dual silencing of KIF11 plus BCL2L1, an anti-apoptotic BCL2 family member, in these two EGFR-independent sublines resulted in marked apoptosis levels. Dual inhibition of KIF11 plus BCL2L1 also induced apoptosis in HCC827 and H1975 parental cells and a KRAS-mutant LUAD cell line, H441. These findings collectively suggest that dual inhibition of KIF11 plus BCL2L1 may be a new approach for the treatment of LUAD.

Junctional adhesion molecule 3 is a potential therapeutic target for small cell lung carcinoma.

There are few effective therapies for small cell lung carcinoma (SCLC); thus, we need to develop novel and efficacious treatments. We hypothesized that an antibody-drug conjugate (ADC) could be a promising option for SCLC. Several publicly available databases were used to demonstrate the extent to which junctional adhesion molecule 3 (JAM3) mRNA was expressed in SCLC and lung adenocarcinoma cell lines and tissues. Three SCLC cell lines, Lu-135, SBC-5, and Lu-134 A, were selected and examined for JAM3 protein expression by flow cytometry. Finally, we examined the response of the three SCLC cell lines to a conjugate between an anti-JAM3 monoclonal antibody HSL156 (developed in-house) and the recombinant protein DT3C, which consists of diphtheria toxin lacking the receptor-binding domain but containing the C1, C2, and C3 domains of streptococcal protein G. In silico analyses revealed that JAM3 mRNA was expressed higher in SCLC cell lines and tissues than in those of lung adenocarcinoma. As expected, all the three SCLC cell lines examined were positive for JAM3 at the mRNA and protein levels. Consequently, control SCLC cells, but not JAM3-silenced ones, were highly sensitive to HSL156-DT3C conjugates, resulting in dose- and time-dependent decreased viability. Finally, silencing JAM3 alone suppressed the growth of all SCLC cell lines examined. Taken together, these findings suggest that an ADC targeting JAM3 could represent a new approach to treating SCLC patients.

Dual inhibition of BCL2L1 and MCL1 is highly effective against RET fusion-positive or MET exon 14 skipping mutation-positive lung adenocarcinoma cells.

Non-small cell lung carcinomas (NSCLCs), especially lung adenocarcinomas (LUADs), harbor several driver mutations against which highly effective tyrosine kinase inhibitors (TKIs) are available. Although TKIs are generally effective against certain NSCLCs, primary or acquired resistance almost always develops. Driver mutations include RET fusion (∼1-2% of NSCLC cases) and MET exon 14 skipping mutation (METΔex14; ∼3-4%). Surprisingly, the LUAD cell line LC-2/ad with CCDC6-RET fusion thrived independently of RET signaling, and Hs-746T cells harboring METΔex14 plus amplification survived MET silencing. However, these two cell lines were highly sensitive to dual silencing of the representative anti-apoptotic BCL2 family members BCL2L1 and MCL1, undergoing extensive apoptosis in monolayer or 3D on-top culture systems. Moreover, we found that most LUAD cell lines and tissues expressed high levels of BCL2L1 and MCL1 mRNA but extremely low levels of BCL2. Together, these findings suggest that inhibiting BCL2L1 plus MCL1 may represent a new approach to treating LUAD cells irrespective of their driver mutations.

Anthrax toxin receptor 2 is a potential therapeutic target for non-small cell lung carcinoma with MET exon 14 skipping mutations.

Although MET tyrosine kinase inhibitors (TKIs) are generally effective against non-small cell lung carcinoma (NSCLC) with MET exon 14 skipping mutations (METΔex14), resistance to MET TKIs can occur, indicating the need to develop other therapeutic options. We found that Hs-746 T cells, which harbor METΔex14 plus amplification, were able to survive and grow in the absence of MET signaling, exhibiting primary resistance to MET TKIs. We also found a moderately positive correlation between MET and anthrax toxin receptor 2 (ANTXR2) mRNA expression in NSCLC cell lines using data from the Cancer Dependency Map database. As expected, Hs-746 T cells were positive for ANTXR2 expression. We used an antibody-drug conjugate (ADC) analog in the form of an anti-ANTXR2 monoclonal antibody, H8R23, conjugated to DT3C recombinant protein which consists of diphtheria toxin (DT) lacking the receptor-binding domain but containing the C1, C2, and C3 domains of streptococcal protein G (3C). H8R23-DT3C conjugates, which function in vitro like an ADC, induced Hs-746 T cells to undergo apoptosis, resulting in decreased viability. These findings collectively suggest that an ADC targeting ANTXR2 could be effective for the treatment of METΔex14-positive NSCLC.

MCL1 inhibition enhances the efficacy of docetaxel against airway-derived squamous cell carcinoma cells.

MCL1 is an anti-apoptotic BCL2 family member that is often overexpressed in various malignant tumors. However, few reports have described the role of MCL1 in squamous cell carcinoma (SqCC) derived from airways including the lung. In this study, we examined whether MCL1 could be a novel druggable target for airway-derived SqCC, for which effective molecular targeted drugs are unavailable. We searched the Kaplan-Meier Plotter database and found that high MCL1 mRNA expression was significantly associated with shorter survival in patients with lower airway (lung) or upper airway (head and neck) derived SqCC. We also explored the Expression Atlas database and learned that authentic lung SqCC cell lines expressing both TP63 and KRT5 mRNA were extremely sparse among the publicly available "lung SqCC cell lines", with an exception being HARA cells. HARA cells were highly dependent on MCL1 for survival, and MCL1-depleted cells were not able to grow, and even declined in number, upon docetaxel (DTX) exposure in vitro and in vivo. Similar in vitro experimental findings, including those in a 3D culture model, were also obtained using Detroit 562 pharyngeal SqCC cells. These findings suggested that combined treatment with MCL1 silencing plus DTX appears highly effective against airway-derived SqCC.

Pericyte-myofibroblast transition in the human lung.

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease that includes fibroblastic foci (FF). It has been increasingly appreciated that the origin of collagen-overproducing cells such as pathological myofibroblasts in FF is pericytes. However, neither pericytes derived from the lung nor FF in the IPF lung have not been fully characterized. Human lung pericytes (HuL-P) examined in this study expressed two representative pericyte markers; platelet-derived growth factor receptor ß (PDGFRB) and chondroitin sulfate proteoglycan 4 (CSPG4), and were able to migrate and cover endothelial tubes in 3D conditions, indicating that they retain characteristics of pericytes. Moreover HuL-P cells transitioned to myofibroblast-like cells in the presence of transforming growth factor (TGF)-ß signaling or to pericyte-like cells in the absence of TGF-ß signaling (pericyte-myofibroblast transition). On the other hand, the FF detected in this study were invariably localized between peripheral lung epithelia and capillary endothelia, the basement membranes of which are physiologically fused. The localization is highly specific in that the only cells that exist between the gap are pericytes. As expected, FF were immunohistochemically positive for PDGFRB and CSPG4, suggesting that pericytes are activated to form FF. We also found that HuL-P cells were difficult to eradicate by dual silencing of Bcl-xL plus MCL1. It would be more sensible to suppress pericyte-myofibroblast transition than to kill activated myofibroblasts for the treatment of IPF.

EGFR-independent EGFR-mutant lung adenocarcinoma cells depend on Bcl-xL and MCL1 for survival.

Although most EGFR-mutant lung adenocarcinomas initially respond to EGFR inhibitors, disease progression almost inevitably occurs. We previously reported that two EGFR-mutant lung adenocarcinoma cell lines, HCC827 and H1975, contain subpopulations of cells that display an epithelial-to-mesenchymal phenotype and can thrive independently of EGFR signaling. In this study, we explored to what extent these two sublines, HCC827 GR2 and H1975 WR7, depended on the anti-apoptotic BCL2 family members, Bcl-xL and/or MCL1, for survival. Although HCC827 GR2 cells were hardly affected by Bcl-xL or MCL1 knockdown alone, dual inhibition of Bcl-xL and MCL1 caused the cells to undergo apoptosis, resulting in decreased viability. In H1975 WR7 cells, not only dual inhibition, but also MCL1 silencing alone, induced the cells to undergo apoptosis. Interestingly, the two sublines markedly declined in number when autophagy flux was suppressed, because they depend, in part, on active autophagy for survival. However, autophagy inhibition was inferior to dual inhibition of Bcl-xL plus MCL1 for GR2 cells, or MCL1 inhibition alone, for decreasing the viability of WR7 cells. Collectively, these findings suggest that inhibiting Bcl-xL plus MCL1, or MCL1 alone, may represent a new approach to treat EGFR-independent EGFR-mutant cancer cells.

MCL1 inhibition enhances the therapeutic effect of MEK inhibitors in KRAS-mutant lung adenocarcinoma cells.

OBJECTIVES: MCL1 is an anti-apoptotic BCL2 family member that is highly expressed in various malignant tumors. However, little is known about the role of MCL1 in KRAS-mutant lung adenocarcinomas. In this study, we aimed to clarify whether MCL1 could be a therapeutic target in KRAS-mutant lung adenocarcinomas for which no effective molecular targeted drugs are available. MATERIALS AND METHODS: We examined to what extent MCL1 knockdown either alone or in combination with MEK inhibitor trametinib suppressed growth or induced apoptosis in the KRAS-mutant lung adenocarcinoma cell line H441 and EGFR-mutant lung adenocarcinoma cell line H1975. Furthermore, we investigated the therapeutic effects of dual inhibition of MCL1 and Bcl-xL, another anti-apoptotic BCL2 family member, in these two cell lines. RESULTS: MCL1 knockdown alone did not induce apoptosis in H441 or H1975 cells. However, MCL1-depleted H441 and H1975 cells underwent apoptosis and decreased in number in the presence of trametinib. We also confirmed that combined therapy by MCL1 knockdown and trametinib almost completely suppressed the growth of H441 cells in vivo. Moreover, dual knockdown of MCL1 and Bcl-xL induced extensive apoptosis in H441 and H1975 cells. CONCLUSION: These findings suggest that combined treatments of MCL1 knockdown and trametinib or dual inhibition of MCL1 and Bcl-xL would be effective therapies for lung adenocarcinomas including the KRAS-mutant subtype.

Characterization of distal airway stem-like cells expressing N-terminally truncated p63 and thyroid transcription factor-1 in the human lung.

Distal airway stem cells (DASCs) in the mouse lung can differentiate into bronchioles and alveoli. However, it remains unclear whether the same stem cells exist in the human lung. Here, we found that human lung epithelial (HuL) cells, derived from normal, peripheral lung tissue, in monolayer, mostly express both the N-terminally truncated isoform of p63 (∆Np63), a marker for airway basal cells, and thyroid transcription factor-1 (TTF-1), a marker for alveolar epithelial cells, even though these two molecules are usually expressed in a mutually exclusive way. Three-dimensionally cultured HuL cells differentiated to form bronchiole-like and alveolus-like organoids. We also uncovered a few bronchiolar epithelial cells expressing both ∆Np63 and TTF-1 in the human lung, suggesting that these cells are the cells of origin for HuL cells. Taken together, ΔNp63+ TTF-1+ peripheral airway epithelial cells are possibly the human counterpart of mouse DASCs and may offer potential for future regenerative medicine.

Trametinib downregulates survivin expression in RB1-positive KRAS-mutant lung adenocarcinoma cells.

High expression levels of survivin in KRAS-mutant lung adenocarcinomas are linked with unfavorable patient outcomes, suggesting that survivin is a promising target for tumor treatment. We found that trametinib, a MEK inhibitor, downregulates survivin expression in the RB1-positive KRAS-mutant lung adenocarcinoma cell lines H358 and H441. In these cell lines, trametinib treatment induced p21 expression and dephosphorylated RB1, leading to sustained suppression of survivin. Knockdown of p21 or RB1 restored survivin expression in trametinib-treated cells, at least partially, which supports the contribution of these molecules to trametinib-mediated survivin suppression. In RB1-negative KRAS-mutant lung adenocarcinoma H2009 cells, survivin downregulation by trametinib was only slight and transient, and trametinib-resistant (TR) cells developed within 1 month of treatment. H2009 TR cells depended much more on survivin for survival than its parental cells, as evidenced by apoptosis induction when survivin was depleted. These findings collectively suggest that trametinib is effective for the treatment of RB1-positive KRAS-mutant lung adenocarcinomas through sustained survivin suppression, but not for RB1-negative lung adenocarcinomas. Thus, the RB1 status could be a biomarker for trametinib application in KRAS-mutant lung adenocarcinomas.

Survivin knockdown induces senescence in TTF­1-expressing, KRAS-mutant lung adenocarcinomas.

Survivin plays a key role in regulating the cell cycle and apoptosis, and is highly expressed in the majority of malignant tumors. However, little is known about the roles of survivin in KRAS-mutant lung adenocarcinomas. In the present study, we examined 28 KRAS-mutant lung adenocarcinoma tissues and two KRAS-mutant lung adenocarcinoma cell lines, H358 and H441, in order to elucidate the potential of survivin as a therapeutic target. We found that 19 (68%) of the 28 KRAS-mutant lung adenocarcinomas were differentiated tumors expressing thyroid transcription factor­1 (TTF­1) and E-cadherin. Patients with tumors immunohistochemically positive for survivin (n=18) had poorer outcomes than those with survivin-negative tumors (n=10). In the H358 and H441 cells, which expressed TTF­1 and E-cadherin, survivin knockdown alone induced senescence, not apoptosis. However, in monolayer culture, the H358 cells and H441 cells in which survivin was silenced, underwent significant apoptosis following combined treatment with ABT-263, a Bcl­2 inhibitor, and trametinib, a MEK inhibitor. Importantly, the triple combination of survivin knockdown with ABT-263 and trametinib treatment, clearly induced cell death in a three-dimensional cell culture model and in an in vivo tumor xenograft model. We also observed that the growth of the H358 and H441 cells was slightly, yet significantly suppressed in vitro when TTF­1 was silenced. These findings collectively suggest that the triple combination of survivin knockdown with ABT-263 and trametinib treatment, may be a potential strategy for the treatment of KRAS-mutant lung adenocarcinoma. Furthermore, our findings indicate that the well­differentiated type of KRAS-mutant lung tumors depends, at least in part, on TTF­1 for growth.

Angiotensin-converting enzyme 2 is a potential therapeutic target for EGFR-mutant lung adenocarcinoma.

EGFR-mutant lung adenocarcinomas contain a subpopulation of cells that have undergone epithelial-to-mesenchymal transition and can grow independently of EGFR. To kill these cancer cells, we need a novel therapeutic approach other than EGFR inhibitors. If a molecule is specifically expressed on the cell surface of such EGFR-independent EGFR-mutant cancer cells, it can be a therapeutic target. We found that a mesenchymal EGFR-independent subline derived from HCC827 cells, an EGFR-mutant lung adenocarcinoma cell line, expressed angiotensin-converting enzyme 2 (ACE2) to a greater extent than its parental cells. ACE2 was also expressed at least partially in most of the primary EGFR-mutant lung adenocarcinomas examined, and the ACE2 expression level in the cancer cells was much higher than that in normal lung epithelial cells. In addition, we developed an anti-ACE2 mouse monoclonal antibody (mAb), termed H8R64, that was internalized by ACE2-expressing cells. If an antibody-drug conjugate consisting of a humanized mAb based on H8R64 and a potent anticancer drug were produced, it could be effective for the treatment of EGFR-mutant lung adenocarcinomas.

Fibroblastic foci, covered with alveolar epithelia exhibiting epithelial-mesenchymal transition, destroy alveolar septa by disrupting blood flow in idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease of unknown cause. IPF has a distinct histopathological pattern of usual interstitial pneumonia in which fibroblastic foci (FF) represent the leading edge of fibrotic destruction of the lung. Currently there are three major hypotheses for how FF are generated: (1) from resident fibroblasts, (2) from bone marrow-derived progenitors of fibroblasts, and (3) from alveolar epithelial cells that have undergone epithelial-mesenchymal transition (EMT). We found that FF dissociated capillary vessels from the alveolar epithelia, the basement membranes of which are fused in normal physiological conditions, and pushed the capillaries and elastic fibers down ~100 µm below the alveolar epithelia. Furthermore, the alveolar epithelial cells covering the FF exhibited a partial EMT phenotype. In addition, normal human alveolar epithelial cells in vitro underwent dynamic EMT in response to transforming growth factor-ß signaling within 72 h. Because it seems that resident fibroblasts or bone marrow-derived cells cannot easily infiltrate and form FF between the alveolar epithelia and capillaries in tight contact with each other, FF are more likely to be derived from the epithelial-to-mesenchymal transitioned alveolar epithelia located over them. Moreover, histology and immunohistochemistry suggested that the FF formed in the lung parenchyma disrupt blood flow to the alveolar septa, thus destroying them. Consequently, collapse of the alveolar septa is likely to be the first step toward honeycombing in the lung during late stage IPF. On the basis of these findings, inhibition of transforming growth factor-ß signaling, which can suppress EMT of the alveolar epithelial cells in vitro, is a potential strategy for treating IPF.

Prolyl isomerase Pin1 promotes survival in EGFR-mutant lung adenocarcinoma cells with an epithelial-mesenchymal transition phenotype.

The secondary epidermal growth factor receptor (EGFR) T790M mutation is the most prominent mechanism that confers resistance to first- or second-generation EGFR tyrosine kinase inhibitors (TKIs) in lung cancer treatment. Although third-generation EGFR TKIs can suppress the kinase activity of T790M-positive EGFR, they still cannot eradicate EGFR-mutated cancer cells. We previously reported that a subpopulation of EGFR-mutant lung adenocarcinomas depends on enhanced autophagy, instead of EGFR, for survival, and in this study we explore another mechanism that contributes to TKI resistance. We demonstrate here that an EGFR-mutant lung adenocarcinoma cell line, H1975 (L858R+T790M), has a subset of cells that exhibits an epithelial-mesenchymal transition (EMT) phenotype and can thrive in the presence of third-generation EGFR TKIs. These cells depend on not only autophagy but also on the isomerase Pin1 for survival in vitro, unlike their parental cells. The Pin1 protein was expressed in an EGFR-mutant lung cancer tissue that has undergone partial EMT and acquired resistance to EGFR TKIs, but not its primary tumor. These findings suggest that inhibition of Pin1 activity can be a novel strategy in lung cancer treatment.

Development of a sensitive screening method for selecting monoclonal antibodies to be internalized by cells.

Antibody-drug conjugates (ADCs), drugs developed by conjugation of an anticancer agent to a monoclonal antibody (mAb), have lately attracted attention in cancer therapy because ADCs can directly bind cancer cells and kill them. Although mAbs for ADCs must be internalized by the target cells, few methods are available for screening mAbs for their ability to be internalized by cells. We have developed a recombinant protein, termed DT3C, which consists of diphtheria toxin (DT) lacking the receptor-binding domain but containing the C1, C2, and C3 domains of Streptococcus protein G (3C). When a mAb-DT3C conjugate, which functions in vitro like an ADC, reduces the viability of cancer cells, the mAb being tested must have been internalized by the target cells. DT3C can thus be a tool to identify efficiently and easily mAbs that can be internalized by cells, thereby enhancing the development of promising ADCs.

Epigenetic modulation enhances the therapeutic effect of anti-IL-13R(alpha)2 antibody in human mesothelioma xenografts.

PURPOSE: The interleukin-13 receptor α2 (IL-13Rα2) is expressed by a variety of human malignant cells. Here, we have examined the constitutive surface expression and the epigenetic regulation of IL-13Rα2 by human mesothelioma. We have also investigated the therapeutic effect of the DNA methylation inhibitor 5-aza-2'-deoxycytidine (5-aza-dC) and anti-IL-13Rα2 monoclonal antibody on mesothelioma xenografts. EXPERIMENTAL DESIGN: Cell surface expression of IL-13Rα2 by various lung carcinomas was analyzed using flow cytometry. Therapeutic effects of anti-IL-13Rα2 and 5-aza-dC were investigated using antibody-dependent cellular cytotoxicity and proliferation assays and by monitoring the survival of mesothelioma-bearing mice. RESULTS: We found that human malignant mesotheliomas expressed surface IL-13Rα2 on their surface and that it was upregulated by treatment with 5-aza-dC. This augmented expression of IL-13Rα2 resulted in growth inhibition of the mesothelioma cells when cocultured with anti-IL-13Rα2 and effector cells, such as splenocytes and peritoneal exudate cells. The growth inhibition of mesothelioma cells was mediated by IFN-γ that was only detected in the supernatant when effector cells were exposed to 5-aza-dC-treated tumors in the presence of anti-IL-13Rα2. Compared with the control or either regimen alone, in vivo administration of anti-IL-13Rα2 in combination with 5-aza-dC significantly prolonged the survival of mice with mesothelioma xenografts. CONCLUSIONS: These observations indicate a promising role for IL-13Rα2 as a target for antibody treatment in malignant mesothelioma, and, in combination with epigenetic regulation by a DNA methylation inhibitor, suggest the potential for a novel strategy to enhance therapeutic potency.

Selective gene transfer into neurons via Na,K-ATPase beta1. Targeting gene transfer with monoclonal antibody and adenovirus vector.

BACKGROUND: Neuron-selective gene transfer is an attractive therapeutic strategy for neurological disorders. However, optimal targets and gene delivery systems remain to be determined. METHODS: Following immunization of mice with PC12 cells, hybridomas were screened by beta-Gal reporter gene assay using FZ33 fiber-modified adenovirus vectors. Subsequently, the efficacy and specificity of monoclonal antibody (mAb)-mediated gene transfer via FZ33 and FdZ adenovirus vectors were evaluated by flow cytometry, chemiluminescent beta-Gal reporter gene assay, and immunocytochemistry. Finally, the antigen recognized by the mAb was identified by mass spectrometry and transfection analysis. RESULTS: A hybridoma clone 6E3 producing monoclonal antibody, mAb6E3, was screened. Flow cytometry, chemiluminescent beta-Gal reporter gene assay, and immunocytochemistry with mAb6E3 and the fiber mutant adenovirus demonstrated efficient gene transfer into the PC12 cells. Treatment of neuron-glia cocultures with mAb6E3 and FdZ adenovirus resulted in neuron-selective gene transfer. Immunohistochemical images of rat spinal cord tissue showed that mAb6E3 reacts specifically with neurons. Finally, Na,K-ATPase beta1 was identified as the antigen of mAb6E3. CONCLUSIONS: Hybridoma screening using FZ33 fiber-modified adenovirus vectors serves as an efficient approach to detect antigens in mAb-targeted gene transfer. Neuronal tropism in the central nervous system through mAb6E3 represents an important initial step towards neuron-selective gene transfer in the treatment of local neurological disorders, such as spinal cord injury.

Carcinoembryonic antigen-targeted selective gene therapy for gastric cancer through FZ33 fiber-modified adenovirus vectors.

PURPOSE: A major problem when using the adenoviral vectors for gene therapy applications is thought to be related to low transduction efficiency in cancer cells or to side effects in normal cells. There is an urgent requirement to improve the specificity of gene delivery in the context of cancer gene therapy. EXPERIMENTAL DESIGN: We constructed a genetically modified adenovirus incorporating an IgG Fc-binding motif from the Staphylococcus protein A, Z33, within the HI loop (Adv-FZ33). A remarkable degree of targeted gene delivery to gastric cancer cells was obtained with Adv-FZ33 with the fully human anti-carcinoembryonic antigen (CEA) monoclonal antibody, C2-45. RESULTS: In vitro LacZ or EGFP gene expression after Adv-FZ33 infection via C2-45 was 20 times higher than control monoclonal antibody in MKN-45 at 1,000 viral particles/cell. We generated Ax3CAUP-FZ33 (UP-FZ33), which is an Adv-FZ33 derivative vector expressing a therapeutic gene (i.e., Escherichia coli uracil phosphoribosyltransferase), which converts 5-fluorouracil (5-FU) directly to 5-fluoro-UMP. UP-FZ33 with C2-45 enhanced the cytotoxicity of 5-FU by 10.5-fold in terms of IC(50) against MKN-45 compared with control IgG4. In a nude mouse peritoneal dissemination model, tumor growth in mice treated with UP-FZ33/C2-45/5-FU was significantly suppressed, and tumor volumes were less than one-fourth of those of the control IgG4 group (P < 0.05). The median survival time of the UP-FZ33/C2-45/5-FU group was significantly longer than those treated with PBS or 5-FU only (P < 0.01). CONCLUSIONS: These data suggest that CEA-targeted FZ33 mutant adenovirus-mediated gene delivery offers a strong and selective therapeutic modality against CEA-producing cancers.

Bcl-xL gene transfer inhibits Bax translocation and prolongs cardiac cold preservation time in rats.

BACKGROUND: Apoptosis is an important cause of early graft loss after heart transplantation. Bcl-xL was reported to protect the heart against normothermic ischemia and reperfusion injury. In this study, we determined whether overexpression of Bcl-xL could inhibit tissue injury resulting from prolonged cold preservation followed by warm reperfusion of heart transplants. METHODS AND RESULTS: Lewis rat hearts were transduced with an adenovirus vector harboring Bcl-xL cDNA (AxCAhBclxL) 4 days before collection of tissue. After preservation in University of Wisconsin solution at 4 degrees C for 24 hours, the heart was either perfused with a Langendorff device ex vivo or used for heterotopic heart transplantation in vivo. Bcl-xL gene transfer significantly reduced the infarct size (23.0+/-2.6% versus 47.7+/-7.0% in saline control and 48.6+/-6.1% in vector control, P<0.01) after 2-hour reperfusion at 37 degrees C with the Langendorff device and significantly decreased creatine kinase release (0.82+/-0.27 IU, versus 1.57+/-0.33 and 1.50+/-0.37 IU in saline and vector controls, respectively; P<0.05). In heart transplantation, overexpression of Bcl-xL inhibited Bax translocation from the cytosol to the mitochondria, resulting in decreased cytochrome c release from the mitochondria; it also significantly decreased cardiac cell apoptosis and improved graft survival rate after long cold preservation, followed by warm reperfusion. CONCLUSIONS: Bcl-xL gene transfer inhibited the translocation of Bax and prolonged the cold preservation time of cardiac transplants. This may be a potential therapeutic method in clinical practice.

Mesenchymal stem cells that produce neurotrophic factors reduce ischemic damage in the rat middle cerebral artery occlusion model.

Mesenchymal stem cells (MSC) were reported to ameliorate functional deficits after stroke in rats, with some of this improvement possibly resulting from the action of cytokines secreted by these cells. To enhance such cytokine effects, we previously transfected the telomerized human MSC with the BDNF gene using a fiber-mutant adenovirus vector and reported that such treatment contributed to improved ischemic recovery in a rat transient middle cerebral artery occlusion (MCAO) model. In the present study, we investigated whether other cytokines in addition to BDNF, i.e., GDNF, CNTF, or NT3, might have a similar or greater effect in this model. Rats that received MSC-BDNF (P < 0.05) or MSC-GDNF (P < 0.05) showed significantly more functional recovery as demonstrated by improved behavioral test results and reduced ischemic damage on MRI than did control rats 7 and 14 days following MCAO. On the other hand, rats that received MSC-CNTF or MSC-NT3 showed neither functional recovery nor ischemic damage reduction compared to control rats. Thus, MSC transfected with the BDNF or GDNF gene resulted in improved function and reduced ischemic damage in a rat model of MCAO. These data suggest that gene-modified cell therapy may be a useful approach for the treatment of stroke.