Biomedical subjects

Donald J Buchsbaum

Publications and source records attributed to Donald J Buchsbaum.

At least 19 recordsLinked to original sources

PubMed2006

Treatment with gemcitabine and TRA-8 anti-death receptor-5 mAb reduces pancreatic adenocarcinoma cell viability in vitro and growth in vivo.

Gemcitabine is a first line agent for pancreatic cancer, but yields minimal survival benefit. This study evaluated in vitro and in vivo effects of a monoclonal antibody (TRA-8) to human death receptor 5, combined with gemcitabine, using two human pancreatic cancer cell lines, S2VP10 and MIA PaCa-2. A subcutaneous model of pancreatic cancer was employed to test in vivo efficacy. S2VP10 and MIA PaCa-2 cells were treated with varying doses of gemcitabine and TRA-8. Cell viability and apoptosis were determined with an adenosine triphosphate assay and annexin V staining, respectively. Mitochondrial membrane destabilization was evaluated with fluorescence-activated cell sorting analysis of JC-1 stained cells. Caspase activation was evaluated by Western blot analysis. MIA PaCa-2 subcutaneous xenografts in athymic nude mice were evaluated for response to treatment with 200 mug of TRA-8 (intraperitoneal on days 9, 13, 16, 20, 23, and 27 postimplant) and 120 mg/kg gemcitabine (I.P. on days 10, 17, and 24). Tumor growth was measured with calipers. MIA PaCa-2 and S2VP10 cells receiving combination treatment with TRA-8 and gemcitabine demonstrated enhanced cytotoxicity, annexin V staining, and mitochondrial destabilization compared to either agent alone. Combination treatment produced enhanced caspase-3 and -8 activation in both cell lines compared with either agent alone. In vivo studies demonstrated mean subcutaneous tumor surface area (produce of two largest diameters) doubling times of 38 days untreated, 32 days gemcitabine, 49 days TRA-8, and 64 days combination treatment. TRA-8 is an apoptosis-inducing agonistic monoclonal antibody that produced synergistic cytotoxicity in combination with gemcitabine in vitro through enhanced caspase activation. These findings, with substantial inhibition of tumor growth in a mouse pancreatic cancer xenograft model receiving combination therapy, are encouraging for anti-death receptor therapy in the treatment of pancreatic cancer.

Animals↗

PubMed2006

Pretargeted radioimmunotherapy.

This brief review covers the concept of pretargeted radioimmunotherapy and summarize the results obtained in preclinical animal models and initial phase I clinical trials. Reagents studied have been a bifunctional antibody prepared by crosslinking Fab' fragments from two antibodies with different specificity, one binding the target antigen expressed on tumors and the other binding a radiolabeled peptide. The alternative system is a conjugate of streptavidin linked to the pretargeting agent and radiolabeled biotin. After reaching optimal tumor targeting of the pretargeting agent, a synthetic mono-biotin poly N-acetyl-galactosamine compound was used to clear unbound targeting agent from the circulation before the injection of radiolabeled biotin. Promising therapeutic responses were obtained in various tumor xenograft models in athymic nude mice. A phase I study of an anti-CD20/streptavidin pretargeting agent and 15 mCi/m(2)(90)Y-biotin produced objective responses with minimal toxicity among lymphoma patients, with an average tumor-to-whole-body radiation dose ratio of 49. Pretargeting radioimmunotherapy approaches have shown higher tumor-to-whole-body ratios than that usually obtained with one-step radioimmunotherapy.

Animals↗

PubMed2006

Gene delivery and gene therapy of prostate cancer.

Surgery, radiation or hormonal therapy are not adequate to control prostate cancer. Clearly, other novel treatment approaches, such as gene therapy, for advanced/recurrent disease are desperately needed to achieve long-term local control and particularly to develop effective systemic therapy for metastatic prostate cancer. In the last decade, significant progress in gene therapy for the treatment of localised prostate cancer has been demonstrated. A broad range of different gene therapy approaches, including cytolytic, immunological and corrective gene therapy, have been successfully applied for prostate cancer treatment in animal models, with translation into early clinical trials. In addition, a wide variety of viral and nonbiological gene delivery systems are available for basic and clinical research. Gene therapy approaches that have been developed for the treatment of prostate cancer are summarised.

Animals↗

PubMed2006

TRAIL receptor-targeted therapy.

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF family of cytokines. Based on its ability to induce apoptosis selectively in a wide variety of cancer cell lines and human tumor xenografts, TRAIL has been in drug development as a potential biological agent for cancer therapy. A variety of chemotherapy agents have been shown to enhance the cytotoxic effects of TRAIL. The potential benefits of TRAIL as an anticancer therapy have been further indicated by its ability to enhance the efficacy of radiotherapy. Preclinical studies have shown the potential use of agonistic monoclonal antibodies that selectively bind TRAIL death receptors for cancer therapy. This review provides an overview of TRAIL receptor-mediated apoptosis of tumor cells, with TRAIL or agonistic monoclonal antibodies only or with chemotherapy drugs. Treatment of tumor xenografts with these ligands, alone or in combination with chemotherapy or radiation, are discussed along with preliminary information about early clinical trials. Additional clinical trials with TRAIL receptor ligands in combination treatment regimens are required to determine their potential for targeted therapy of cancer.

Animals↗

PubMed2006

Multiple gene expression analyses in paraffin-embedded tissues by TaqMan low-density array: Application to hedgehog and Wnt pathway analysis in ovarian endometrioid adenocarcinoma.

Recent studies have shown the hedgehog and Wnt families of signaling proteins to be associated with tumor initiation, growth, and survival. However, these pathways remain unexplored in ovarian endometrioid adenocarcinoma (OEA). Here, we describe a novel TaqMan low-density array to examine the expression of 26 and 20 genes in the hedgehog and Wnt pathways, respectively, in six matched snap-frozen and formalin-fixed, paraffin-embedded (FPE) OEA specimens. Expression values were normalized to uninvolved ovarian epithelium. Gene expression in matched frozen and FPE tissues demonstrated significant concordance (r = 0.92, P < 0.0001). However, comparison of amplified and unamplified RNA from frozen OEA tissues revealed an altered molecular profile in amplified RNA. Amplification of RNA from FPE tissues was not successful. The expression of Desert hedgehog (DHH), Indian hedgehog (IHH), Hedge-hog interacting protein (HHIP), Wnt10B, Wnt9B, and Wnt inhibitory factor (WIF1) were tumor-specific with no detectable expression in normal ovarian epithelium. In addition, several genes were significantly (P < 0.025) down-regulated in OEA, including cyclin E2, Porcupine, c-Myc, and Axin 2 (4.8-, 3.6-, 2.9-, and 1.9-fold, respectively). TaqMan low-density array provides an effective multivariate technique for examining gene expression in RNA isolated from either snap-frozen or archival FPE tissues and can identify tumor-specific genes, possibly leading to novel treatments.

Animals↗

PubMed2006

Oncolytic HSV-1 for the treatment of brain tumours.

The prognosis for patients diagnosed with malignant glioma, the most common primary tumour of the central nervous system, remains poor despite decades of research and advances in surgery, radiation and chemotherapy. The development of new approaches for the treatment of these tumours has led to the emergence of oncolytic viral therapy, with the use of conditionally replicating viruses, as a potential new intervention. Herpes simplex virus type 1 has emerged as the leading candidate oncolytic virus, with six different trials either completed or underway for patients with malignant glioma. In this review, the background of this approach will be discussed, followed by a discussion of the clinical trials, as well as potential directions for future trials.

Brain Neoplasms↗

PubMed2005

Antitumor efficacy of capecitabine and celecoxib in irradiated and lead-shielded, contralateral human BxPC-3 pancreatic cancer xenografts: clinical implications of abscopal effects.

PURPOSE: X-ray therapy (XRT) remains one of the major modalities used to treat patients diagnosed with locally advanced pancreatic adenocarcinoma. However, the effect of XRT on metastatic tumors outside the field of irradiation (abscopal effect) remains largely unknown. In the current study, we examined the effect of XRT alone and in combination with capecitabine and/or celecoxib in both irradiated and lead-shielded contralateral BxPC-3 pancreatic cancer xenografts. This chemoradiation regimen was chosen based on our molecular analysis of pancreatic adenocarcinoma. EXPERIMENTAL DESIGN: Athymic mice were injected bilaterally with BxPC-3 cells and treatment was initiated 28 days postimplant. During XRT (2 Gy for 5 consecutive days, administered on days 0 and 24), one flank was irradiated whereas the rest of the body (including the contralateral tumor) was lead shielded. Capecitabine (350 mg/kg) was administered on days 0 to 13 and 24 to 37. Celecoxib was initiated in the diet at 100 ppm (equivalent to 20 mg/kg/d p.o.) and administered throughout the study. RESULTS: In irradiated xenografts, capecitabine and XRT showed synergistic anitiumor efficacy (P=0.008), which was further improved with the addition of celecoxib (P<0.001). In contralateral shielded xenografts, abscopal effects were observed. Whereas monotherapy with XRT showed significant reduction in tumor area in irradiated xenografts, growth was promoted by 23% (P<0.001) in contralateral lead-shielded tumors in the same animals relative to untreated tumors. Interestingly, synergistic antiproliferative efficacy occurred in these contralateral tumors when capecitabine was administered (P<0.001), despite being outside the irradiated field. The addition of celecoxib further inhibited tumor growth (P<0.001). This trimodal combination most effectively stabilized disease in both shielded and irradiated tumors; however, tumor eradication was not observed. There were no significant changes in thymidine phosphorylase, dihydropyrimidine dehydrogenase, or cyclooxygenase-2 mRNA levels in irradiated or lead-shielded tumors, suggesting that efficacy cannot be predicted solely from these previously identified indicators of response. Immunohistochemistry examining the proliferation marker Ki-67 showed concordance with tumor response in both irradiated and contralateral shielded xenografts. CONCLUSIONS: These results have implications in the rational design of treatment paradigms for pancreatic cancer where metastatic disease remains the primary cause of patient morbidity and abscopal effects in tumors outside the field of irradiation may affect tumor response.

5'-Nucleotidase↗

PubMed2005

Intraperitoneal pretarget radioimmunotherapy with CC49 fusion protein.

PURPOSE: This study examined a pretarget radioimmunotherapy strategy for treatment of an i.p. tumor model (LS174T). EXPERIMENTAL DESIGN: The strategy used regional administration (i.p.) of a novel targeting molecule composed of four CC49 anti-tumor-associated glycoprotein 72 (TAG-72) single-chain antibodies linked to streptavidin as a fusion protein (CC49 fusion protein); 24 hours later, a synthetic clearing agent was administered i.v. to produce hepatic clearance of unbound CC49 fusion protein/synthetic clearing agent complexes. Four hours later, a low molecular weight radiolabeled reagent composed of biotin conjugated to the chelating agent 7,10-tetra-azacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA) complexed with (111)In-, (90)Y-, or (177)Lu-DOTA-biotin was injected. RESULTS: Radiolocalization to tumor sites was superior with i.p. administration of radiolabeled DOTA-biotin as compared with i.v. administration. Imaging and biodistribution studies showed excellent tumor localization of radioactivity with (111)In- or (177)Lu-DOTA-biotin. Tumor localization of (111)In-DOTA-biotin was 43% ID/g and 44% ID/g at 4 and 24 hours with the highest normal tissue localization in the kidney with 6% ID/g at 48 and 72 hours. Therapy studies with (90)Y-DOTA-biotin at doses of 400 to 600 microCi or (177)Lu-DOTA-biotin at doses of 600 to 800 microCi produced significant prolongation of survival compared with controls (P = 0.03 and P < 0.01). CONCLUSIONS: Pretarget radioimmunotherapy using regional administration of CC49 fusion protein and i.p. (90)Y- or (177)Lu-DOTA-biotin represents a successful therapeutic strategy in the LS174T i.p. tumor model and this strategy may be applicable to human trials in patients with i.p. ovarian cancer.

Animals↗

PubMed2005

Anti-tumor activity of TRA-8 anti-death receptor 5 (DR5) monoclonal antibody in combination with chemotherapy and radiation therapy in a cervical cancer model.

OBJECTIVES: There is substantial evidence that tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) causes apoptosis via activation of death receptors 4 and 5 (DR4 and DR5). We sought to determine the therapeutic potential of TRA-8 (anti-DR5 monoclonal antibody) in combination with chemotherapy and radiation therapy in a cervical cancer model. METHODS: DR5 expression in 7 human cervical cancer cell lines was analyzed by indirect immunofluorescence using murine TRA-8 in combination with flow cytometry. Cell lines were treated with TRA-8 alone or in combination with cisplatin, topotecan, or radiation, and cytotoxicity assays were performed. Mice were inoculated with ME-180 cancer cells and treated with different combinations of therapy. Animals receiving antibody were injected intraperitoneally with 200 microg of TRA-8. Animals received 9 Gy 60Co radiation divided into 3 fractions and 3 intraperitoneal doses of cisplatin (6 mg/kg) 1 h before radiation. A similar experiment was performed using topotecan (2 mg/kg) as the chemotherapeutic agent. RESULTS: DR5 was expressed to a varying degree on the cervical cancer cell lines. Combination treatment with TRA-8 and chemotherapy or radiation resulted in synergistic cytotoxicity in vitro. In vivo, combination therapy with TRA-8, cisplatin, and radiation produced tumor growth inhibition that was significantly greater than the other groups. Similar results were seen in combination studies with topotecan. CONCLUSIONS: These data suggest that DR5 is a good target for activation of the apoptotic pathway. Monoclonal antibodies such as TRA-8 may play an important role in the development of an effective treatment strategy for patients with advanced cervical cancer.

Animals↗

PubMed2005

The small heat shock protein alpha B-crystallin is a novel inhibitor of TRAIL-induced apoptosis that suppresses the activation of caspase-3.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor alpha family of cytokines that preferentially induces apoptosis in transformed cells, making it a promising cancer therapy. However, many neoplasms are resistant to TRAIL-induced apoptosis by mechanisms that are poorly understood. We demonstrate that the expression of the small heat shock protein alpha B-crystallin (but not other heat shock proteins or apoptosis-regulating proteins) correlates with TRAIL resistance in a panel of human cancer cell lines. Stable expression of wild-type alpha B-crystallin, but not a pseudophosphorylation mutant impaired in its assembly and chaperone function, protects cancer cells from TRAIL-induced caspase-3 activation and apoptosis in vitro. Furthermore, selective inhibition of alpha B-crystallin expression by RNA interference sensitizes cancer cells to TRAIL. In addition, wild-type alpha B-crystallin promotes xenograft tumor growth and inhibits TRAIL-induced apoptosis in vivo in nude mice, whereas a pseudophosphorylation alpha B-crystallin mutant impaired in its anti-apoptotic function inhibits xenograft tumor growth. Collectively, these findings indicate that alpha B-crystallin is a novel regulator of TRAIL-induced apoptosis and tumor growth. Moreover, these results demonstrate that targeted inhibition of alpha B-crystallin promotes TRAIL-induced apoptosis, thereby suggesting a novel strategy to overcome TRAIL resistance in cancer.

Apoptosis↗

PubMed2005

Intraperitoneal radioimmunotherapy with a humanized anti-TAG-72 (CC49) antibody with a deleted CH2 region.

The application of intraperitoneal (i.p.) radioimmunotherapy to treat i.p. tumor loci has been limited by bone marrow toxicity secondary to circulating radiolabeled antibodies. The generation of novel genetically engineered monoclonal antibodies, which can achieve high tumor uptake and rapid blood clearance, should enhance the therapeutic index of i.p. radioimmunotherapy. In this regard, a novel humanized anti-TAG-72 monoclonal antibody with a deleted CH2 region (HuCC49DeltaCH2) has been described, which localized well to subcutaneous xenograft tumors and had a rapid plasma clearance. The aim of this study was to examine the characteristics of this radiolabeled reagent when administered through the i.p. route in mice bearing i.p. tumor (LS174T). The DeltaCH2 molecule and intact humanized CC49 (HuCC49) monoclonal antibody were conjugated to PA-DOTA and radiolabeled with (177)Lu. Both molecules retained high-affinity binding to TAG-72 positive LS174T tumor cells in vitro. The radiolabeled DeltaCH2 molecule had a modest decrease in tumor localization, as compared to the intact molecule when administered i.p. to tumor-bearing mice and a dramatically shorter plasma disappearance T(1/2) at 2.7 hours compared to 61.2 hours for the intact antibody. The radiolabeled DeltaCH2 molecule thus had very high tumor:blood ratios. Using an (131)I-labeled system, the maximum tolerated dose of DeltaCH2 was >3x that of intact HuCC49. Autoradiography of tumors showed low radiation dose rates at tumor centers early (1 and 4 hours), as compared to higher dose rates at tumor periphery but a more uniform distribution by 24 hours. Dose-rate distributions were similar for both reagents. Animals bearing LS174T i.p. tumors were treated with 300 microCi of (177)Lu-labeled DeltaCH2 or intact HuCC49 by i.p. route daily x 3. The (177)Lu-DeltaCH(2) molecule mediated an increase in median survival compared to controls (67.5 +/- 7.5 days versus controls of 32 +/- 3.3) while the same dose of (177)Lu-HuCC49 produced early toxic deaths. These studies suggest that i.p. radioimmunotherapy using radiolabeled HuCC49DeltaCH2 should allow higher radiation doses to be administered with less marrow toxicity and potentially improved efficacy.

Animals↗

PubMed2005

Radiotargeted gene therapy.

The radiotargeted gene therapy approach to localizing radionuclides at tumor sites involves inducing tumor cells to synthesize a membrane-expressed receptor with a high affinity for injected radiolabeled ligands. A second strategy involves transduction of the sodium iodide symporter (NIS) and free radionuclide therapy. Using the first strategy, induction of high levels of human somatostatin receptor subtype 2 expression and selective tumor uptake, imaging, or growth inhibition with radiolabeled somatostatin analogs has been achieved in human tumor xenograft models. Therapy studies have been performed on several tumor xenograft models with various radionuclides using the NIS radiotargeted gene therapy approach. The use of gene transfer technology to induce expression of high-affinity membrane receptors or transporters can enhance the specificity and extent of radioligand or radionuclide localization in tumors, and the use of radionuclides with appropriate emissions can deliver radiation-absorbed cytotoxic doses across several cell diameters to compensate for limited transduction efficiency. Clinical studies are needed to determine the most promising of these new therapeutic approaches.

Animals↗

PubMed2004

Adenoviral vector-mediated augmentation of epidermal growth factor receptor (EGFr) enhances the radiosensitization properties of anti-EGFr treatment in prostate cancer cells.

PURPOSE: To determine whether an adenoviral vector approach to the augmentation of epidermal growth factor receptor (EGFr) expression results in increased antiproliferative and radiosensitization properties of anti-EGFr antibody therapy in prostate cancer cells. METHODS AND MATERIALS: DU145 and LNCaP human prostate cancer cells were used to test the above question in vitro. An adenoviral vector was utilized to transduce cells with an EGFr transgene (AdEGFr). Immunoblots were performed to measure EGFr expression and EGFr tyrosine phosphorylation. Radiolabeled ligand studies were employed to test binding of epidermal growth factor to EGFr. Scatchard analyses allowed for quantification of the number of EGFrs. Standard immunohistochemistry was performed to assess EGFr expression. Cellular proliferation was assessed after various combinations of treatment. RESULTS: Studies of prostate carcinoma cells infected with AdEGFr demonstrated an increase in EGFr expression. This increase in expression correlated with increased function of EGFr. Specifically, increased EGFr expression also resulted in increased ligand binding, ligand-induced internalization of EGFr, and ligand-induced EGFr tyrosine kinase activity that could be blocked with pre-exposure to IMC-C225 (an anti-EGFr monoclonal antibody). Transduction of the LNCaP cells with AdEGFr did not increase the antiproliferative effects of IMC-C225, but did significantly increase IMC-C225-induced radiosensitization as determined by cell proliferation. CONCLUSIONS: Augmentation of EGFr expression, through an adenoviral vector approach in prostate carcinoma cells, resulted in cells that demonstrated greater IMC-C225-induced radiosensitization compared to cells that were not treated with AdEGFr.

Adenoviridae↗

PubMed2004

Gene expression imaging with radiolabeled peptides.

An approach to image radiolabeled peptide localization at tumor sites by inducing tumor cells to synthesize membrane expressed human somatostatin receptor subtype 2 (hSSTr2) with a high affinity for radiolabeled somatostatin analogues is described. The use of gene transfer technology to induce expression of high affinity membrane hSSTr2 can enhance the specificity and degree of radiolabeled peptide localization in tumors. Employing this strategy, induction of high levels of hSSTr2 expression with selective tumor uptake of radiolabeled peptides was achieved in both subcutaneous non-small cell lung cancer and intraperitoneal ovarian cancer mouse human tumor xenograft models. The features of this genetic transduction imaging approach are: (1) constitutive expression of a tumor-associated receptor is not required; (2) tumor cells are altered to express a new target receptor or increased quantities of a constitutive receptor at levels which may significantly increase tumor targeting of radiolabeled peptides compared to uptake in normal tissues; (3) gene transfer can be accomplished by local or regional injection of adenoviral vectors; (4) it is feasible to target adenovirus vectors to tumor cells by modifying adenoviral tropism (binding) or by the use of tumor-specific promoters such that the hSSTr2 will be specifically expressed in the desired tumor; and (5) this technique can be used to image expression of a second therapeutic gene.

Animals↗

PubMed2004

Mechanisms of resistance to Erbitux (anti-epidermal growth factor receptor) combination therapy in pancreatic adenocarcinoma cells.

We previously demonstrated that pancreatic adenocarcinoma BxPC-3 xenografts display resistance to treatment with Erbitux, gemcitabine, and radiation, whereas MIA PaCa-2 xenografts are highly sensitive to the same therapy. Here, we elucidate in vitro mechanisms that may explain the observed differential response of epidermal growth factor receptor (EGFR) expressing pancreatic adenocarcinoma xenografts to Erbitux-based combination therapy in vivo. MIA PaCa-2 and BxPC-3 protein lysates were probed with antibodies to EGFR, ErbB2, ErbB3, and ErbB4. Constitutive ErbB3 activity was visualized by immunoblot analysis using anti-phosphotyrosine antibodies and receptor-specific immunoprecipitates. erbB2 and erbB3 gene expression in both cell lines was quantified with real-time polymerase chain reaction. Erbitux-induced internalization of EGFR was determined by flow cytometry following Erbitux treatment for different incubation times at 0 degrees C and 37 degrees C. MIA PaCa-2 and BxPC-3 protein extracts were also probed with anti-phospho-mitogen-activated protein kinase antibody after stimulation with EGF and in the presence of Erbitux. Although both cell lines expressed EGFR and ErbB2 protein, ErbB3 protein was selectively expressed by BxPC-3 cells, where it also showed evidence of constitutive phosphorylation. There was a 10-fold increase of erbB3 transcript levels in BxPC-3 cells compared with MIA PaCa-2. ErbB4 protein was not detectable in either cell line. Erbitux mediated EGFR internalization in MIA PaCa-2 cells after 2 hours of incubation, whereas it did not promote EGFR internalization in BxPC-3 cells. Likewise, EGF-dependent phosphorylation of MAPK p44/42 was blocked by Erbitux treatment in MIA PaCa-2 but not BxPC-3 cells. Erbitux selectively interfered with EGF-induced MAPK activation in MIA PaCa-2 but not BxPC-3 cells. Persistent MAPK activation and impaired in vitro internalization of EGFR by BxPC-3 pancreatic cancer cells may be due to constitutive ErbB3 signaling, facilitated by heterodimerization with EGFR, which may explain resistance to Erbitux-based combination therapy in vivo.

Adenocarcinoma↗

PubMed2004

Anti-EGFR-mediated radiosensitization as a result of augmented EGFR expression.

PURPOSE: Elevated epidermal growth factor receptor (EGFR) expression has correlated with a poor prognosis after standard treatment of several malignancies. However, it is not clear whether the absolute level of EGFR expression affects the radiosensitizing properties of anti-EGFR treatments. A better understanding of this question would be helpful for the design of protocols that deliver these treatments. To explore this question, cells (LS174T) that did not display inherent anti-EGFR treatment-induced radiosensitization were selected for studies that could potentially enhance EGFR expression. MATERIALS AND METHODS: Human colon carcinoma cells (LS174T), which did not show radiosensitization by anti-EGFR treatments, were employed for these studies. (Also, these cells were not responsive to the antiproliferative effects of anti-EGFR treatment.) Using standard transfection techniques (eukaryotic expression vector) as well as an adenoviral construct to enhance EGFR expression, LS174T cells were transduced in a manner that resulted in enhanced expression of EGFR. Subsequently, standard proliferation studies were performed to test the radiosensitizing properties of anti-EGFR treatment (an anti-EGFR monoclonal antibody: IMC-C225). RESULTS: Studies were undertaken to stably transfect LS174T cells with EGFR. The stable transfectants, LS174T.EGFR cells, were responsive to the antiproliferative effects of anti-EGFR treatment, in contrast to the parent LS174T cells. Similar results were demonstrated when the cells were infected with AdEGFR. Additionally, the LS174T.EGFR cells were responsive to the radiosensitizing properties of anti-EGFR treatment (IMC-C225), whereas the parent cells were not. CONCLUSIONS: Although the level of EGFR expression is of prognostic significance in many tumor models, the response of cells to anti-EGFR treatment alone, or combinations of this treatment with radiation or chemotherapy, depends upon many factors that are not necessarily related to the inherent EGFR expression of the tumor cells. However, the studies reported herein, demonstrate that when LS174T cells were transduced to show increased EGFR expression, they became responsive to the radiosensitizing properties of anti-EGFR treatments.

Adenoviridae↗

PubMed2004

Adenovirus-mediated FLT1-targeted proapoptotic gene therapy of human prostate cancer.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL/Apo2L) is of particular interest in the development of prostate carcinoma therapeutics as it preferentially induces apoptosis of tumor cells. To employ adenoviral vectors for highly efficient and specific TRAIL gene transfer into cancer cells could overcome some potential problems for recombinant TRAIL. The vascular endothelial growth factor receptor FLT-1 is involved in regulation of angiogenesis and tumor growth, invasion, and metastasis of prostate carcinoma. FLT-1 expression is observed in both tumor endothelial cells and prostate cancer cells. We developed an adenoviral vector encoding the TRAIL gene under control of the FLT1 promoter (AdFlt-TRAIL), which produced endothelial and prostate cancer cell death. The combination of ionizing radiation and adenovirus-driven TRAIL expression overcame human prostate cancer cell resistance to TRAIL. Furthermore, in vivo administration of AdFlt-TRAIL at the site of tumor growth in combination with radiation treatment produced significant suppression of the growth of DU145 human prostate tumor xenografts in athymic nude mice. Our results suggest that specific TRAIL delivery employing the FLT1 promoter can effectively inhibit tumor growth and demonstrate the advantage of combination radiotherapy and gene therapy for the treatment of prostate cancer.

Adenoviridae↗

PubMed2004

Imaging and therapy of tumors induced to express somatostatin receptor by gene transfer using radiolabeled peptides and single chain antibody constructs.

The fields of radioimmunodetection and radioimmunotherapy began with an initial paradigm that a targeting molecule (eg, antibody) carrying a radioisotope had the potential of selectively imaging and delivering a therapeutic dose of radiation to tumor sites. A second paradigm was developed in which injection of the targeting molecule was separated from injection of a short-lived radioisotope-labeled ligand (so-called "pretargeting strategy"). This strategy has improved radioisotope delivery to tumors in animal models, enhanced radioimmune imaging in man, and therapeutic trials are in an early phase. We proposed a third paradigm to achieve radioisotopic localization at tumor sites by inducing tumor cells to synthesize a membrane expressed receptor with a high affinity for infused radiolabeled ligands. The use of gene transfer technology to induce expression of high affinity membrane receptors can enhance the specificity of radioligand localization, while the use of radioisotopes with the ability to deliver radiation damage across several cell diameters will compensate for less than perfect transduction efficiency. This approach was termed "Genetic Radioisotope Targeting Strategy." Using this strategy, induction of high levels of gastrin releasing peptide receptor or human somatostatin receptor subtype 2 expression and selective tumor uptake of radiolabeled peptides was achieved. The advantages of the genetic transduction approach are (1) constitutive expression of a tumor-associated antigen/receptor is not required; (2) tumor cells are altered to express a new target receptor or increased quantities of an existing receptor at levels that may significantly improve tumor targeting of radiolabeled ligands compared with normal tissues; (3) gene transfer can be achieved by intratumoral or regional injection of gene vectors; (4) it is feasible to target adenovirus vectors to receptors overexpressed on tumor cells by modifying adenoviral tropism (binding) so that the virus will be targeted specifically to the desired tumor; and (5) it is possible to coexpress the receptor gene and a therapeutic gene, such as cytosine deaminase, for molecular prodrug therapy to produce an enhanced therapeutic effect.

Animals↗