- Email: [email protected]
815. miRNA from Tumor-Associated Macrophages as Serum Biomarkers for Ovarian Cancer
CANCER-TARGETED GENE & CELL THERAPY III murine IFNγ. Plasmid DNA expressing the fusion protein, pCpGIFNγ-(HBD)n (n=1 to 3), was delivered to mouse liver through hydrodynamic injection. The serum concentration of IFNγ was determined by ELISA, and its biological activity in the liver was determined by measuring the mRNA levels of IFNγ-inducible molecules. M5076 murine ovarian sarcoma cells were inoculated to mice via the tail vein to establish a mouse model of hepatic metastasis, and the survival of mice was monitored. The toxicity was evaluated by anorexia, body weight loss and liver damage. Results: The mRNA expression of IFNγ derivatives decreased with increasing number of HBD on IFNγ. The serum concentration of IFNγ also decreased with the HBD number, and a large decrease was observed for IFNγ-(HBD)2 and IFNγ-(HBD)3, suggesting that two or more repeats of the HBD are effective in capturing the fusion proteins onto liver cells. An intravenous injection of heparin resulted in a transient increase in the serum concentration of IFNγ-(HBD)2. Despite the huge differences in the serum concentration of IFNγ, the ratio of the mRNA levels of IFNγ-inducible molecules to those of IFNγ in the liver was almost comparable to all groups. A hydrodynamic injection of pCpG-IFNγ(HBD)2 was as effective as that of pCpG-IFNγ in suppressing the liver metastasis, whereas it caused no significant liver toxicity, loss of body weight and anorexia, which were obvious in mice receiving pCpG-IFNγ. Conclusion: We have demonstrated that gene transfer of IFN-γ-(HBD)2 to the liver is effective in inhibiting hepatic metastasis as well as in reducing IFN-γ-inducible systemic side-effects.
813. Cytokine-Based Log-Scale Expansion of Functional Human Dendritic Cells from PBMCs
Yui Harada,1,2 Satoru Saito,1 Yosuke Morodomi,1 Kumi Yoshida,1 Tomohiko Ichikawa,2 Yoshikazu Yonemitsu.1 1 R&D Laboratory for Innovative Biotherapeutics, Kyushu University Graduate School of Pharmaceutical Sciences, Fukuoka, Japan; 2Departments of Urology, Chiba University Graduate School of Medicine, Chiba, Japan. PURPOSE: Dendritic cells (DCs) play a crucial role in maintaining the immune system. Though DC-based cancer immunotherapy has been suggested to hold potential to treat various kinds of malignancies, clinical efficacies are still insufficient in many human trials. We proved that this antitumor effect depends on the number of DCs (unpublished data), and it is necessary to prepare an enough number of DCs for effective treatments of tumors. In this study, therefore, we attempted to expand functional human DCs ex vivo with cytokine cocktail. Materials and Methods: Peripheral blood mononuclear cells (PBMCs) and CD14+ cells were obtained from volunteers. Conventional DCs were obtained from peripheral blood CD14+ cells as described previously with minor modification. Briefly, CD14+ cells were cultured under hGM-CSF and hIL-4 (GM/IL-4). CD3-depleted PBMCs were expanded and differentiated into DCs in the presence of hGM-CSF and hSCF (GM/SCF) or GM/IL-4 for several weeks. Expanded DC properties such as expression of surface markers, inflammatory cytokines production, phagocytotic activity, antigen presentating ability in vitro were analyzed, and compared with those of conventional DC. RESULTS: CD3-negative cells increased approximately 10 - 100 fold after 5 weeks culture and >80% of expanded cells expressed CD11c. Thus, by this method, 10 - 100 times more CD11c+ cells could be obtained than conventional procedures could. As are seen in conventional DCs, expanded DCs showed dendrites after maturation, and endocytotic activities. Expanded DCs also expressed HLA-DR, adhesion molecules, and co-stimulatory molecules and produced inflammatory cytokines as well as conventional DCs did. Functionally, mixed lymphocyte reaction (MLR) assay revealed that expanded DCs could stimulate allogenic T-cell proliferation to the same extent as conventional DCs. CONCLUSIONS: We found that human CD11c+ cells could be effectively expanded from PBMCs by culture with cytokine cocktail Molecular Therapy Volume 19, Supplement 1, May 2011 Copyright © The American Society of Gene & Cell Therapy
(GM/SCF). Expanded DC had properties that were required to obtain therapeutic gain. We expect that this technology will be able to contribute largely to both basic and clinical research of human cancer immunotherapy. DC expansion technology will improve therapeutic gain of cancer and alleviate patients’ burden of apheresis.
814. A New Method To Develop Genetically Modified Lung Cancer Stem Cells
Feridoun Karimi-Busheri,1 Victoria Zadorozhny,1 Ali Haghighi,1 Daniel L. Shawler,1 Habib Fakhrai.1 1 NovaRx Corporation, San Diego, CA. Discovery of cancer stem cells has initiated a new era that holds much promise and hope in the fight against cancer. Tumor stem cells are resistant to chemotherapy and radiation and are reputed to be one of the major causes of cancer recurrence. We have established an intense program to better understand lung cancer tumor stem cells and develop new therapeutic approaches against lung cancer, the most prominent, and most common, cancer killer in the world. The annual death due to this disease exceeds the combined deaths caused by colon, breast, prostate, and pancreatic cancers. Thus, development of an effective therapy is critical to serve this serious unmet medical need. Lung cancer causes sever morbidity and mortality and its cost to the society related to treatment costs, morbidity, and mortality approaches a 100 billion annually in the United States. Here we report the isolation and gene modification of lung cancer stem cells from established non-small cell lung cancer (NSCLC) cell lines and from primary cells of a NSCLC tumor xenograft established in NOD/SCID mice. We also present methodologies towards genetically engineering the isolated cells by antisense gene modification with the TGF-β antisense vector pKNC/SBA2 and the generation of largescale quantities of the gene modified tumor stem cells for utilization in clinical trials. Our data demonstrate that the secretion of TGF-β is significantly reduced by the transformed vector and expression of many genes is significantly altered in gene modified cells compared to the parental unmodified cell lines. Inclusion of a specific cancer stem cells vaccine as components of our whole tumor cell vaccine cocktails belagenpumatucel-L, which has shown effectiveness in 70 percent of the patients in a phase II clinical trial, may result in an even higher survival among the patients and decreasing tumor metastasize.
815. miRNA from Tumor-Associated Macrophages as Serum Biomarkers for Ovarian Cancer
Jonas Persson,1 Ines Beyer,1 Nicole Urban,2 Charles Drescher,2 Andre Lieber.1 1 Division of Medical Genetics, University of Washington, Seattle, WA; 2Fred Hutchinson Cancer Research Center, Seattle, WA. Our findings and published data show that ovarian cancers are heavily infiltrated by tumor-associated macrophages (TAMs). TAMs secrete factors that support tumor growth and prevent anti-tumor immune responses. There is a clear correlation between the number of TAMs and malignancy. Our central hypothesis is that TAM derived miRNA can serve as a serum biomarker for cancer. miRNAs have distinct expression profiles in different tissues. They are actively released from cells and highly stable in a cell-free form in the blood. To test our hypothesis, we isolated TAMs from mouse tumors or biopsies from ovarian cancer patients and compared their miRNA expression profiles with those of peripheral blood monocytes from animals or patients without tumors. Based on this, we selected a set of miRNA that were expressed at a significantly higher level in TAMs. In preliminary studies in mice, we found that several of these miRNAs were present at significantly lower levels in serum from mice with tumors compared to serum from control mice. Furthermore, the concentration of these miRNA inversely correlated with the tumor S311
CANCER-TARGETED GENE & CELL THERAPY III size in animals. By measuring the concentration of these miRNA in tumor cells and circulating TAMs, we came to the conclusion that serum miRNA were derived from circulating TAMs and that in tumor bearing mice less circulating TAMs and more tumor-localized TAMs were present. This explains the lower serum concentration of TAM-specific miRNA in serum of tumor bearing mice. Preliminary data with circulating human TAMs and serum miRNA corroborated the observations made in mice. We are currently conducting studies with a large number of PBMCs and serum from healthy donors and patients with different stages of ovarian cancer to assess the specificity and selectivity of TAM miRNA as biomarkers of ovarian cancer. As the use of tumor derived miRNA as biomarkers is complicated by the genetic and epigenetic instability of cancer cells, TAM-derived miRNAs might be a more reliable marker for early detection and prognosis of ovarian cancer.
816. Increased Invasiveness and Host Vessels Co-Option after 15-LO-1 and HSV-tk Combination Gene Therapy in Rat Glioma Model
Agnieszka Pacholska,1 Haritha Samaranayake,1,2 Jere Pikkarainen,1,2 Farizan Ahmad,1 Thomas Wirth,1 Seppo YläHerttuala.1 1 Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute, Kuopio, Finland; 2Ark Therapeutics Oy, Kuopio, Finland. One of the most fatal and refractory cancer type in humans is malignant glioma, out of which the most common and aggressive subtype is glioblastoma multiforme. Gliomas are among the most vascularised tumors in humans, what makes them a potential target for anti-angiogenic therapies. 15-lipoxygenase-1 (15-LO-1) is widely expressed in various cells and acts on diverse signal transduction pathways. It is known that 15-LO-1 may possess strong antiangiogenic properties. Recently, we have proved that 15-LO can also induce apoptosis by induction of lipid peroxidation in vivo and is able to significantly extent survival in rat malignant glioma. We concluded that 15-LO-1 gene therapy could be used as a promising cancer treatment acting through two independent mechanisms with pro-apoptotic therapeutic effects additionally being complemented by inhibition of tumor angiogenesis. Therefore, we tested the therapeutic potential of 15-LO gene therapy in combination with adenoviral herpes simplex thymidine kinase (AdHSV-tk) to investigate whether it could additionally enhance the effects of suicide gene therapy. BDIX male rats were injected with 104 BT4C glioma cells into the right corpus callosum. 15 days after cell inoculation the animals received 3 injections (2.5 µl per site) of both Adh15-LO-1 (2.7 x 1010 pfu/ml) and AdHSV-tk (1.45x1012 vp/ml), followed by two additional injections applied the next day and 14 days of gancyclovir treatment (50mg/kg). Combination gene therapy did not inhibit the tumor growth and showed no survival benefit. However, a profound effect on the migratory properties of the tumor cells was noted. The treatment induced a shift in glioblastoma tumor phenotype toward enhanced migration and healthy tissue infiltration, represented by formation of multiple satellite tumors. Moreover, co-option of the host vasculature became a compensatory mechanism to combination therapy, as the tumor cells ensheathed preexisting vessels and traveled along them to invade healthy tissue. Our results are in line with other reports, suggesting that some cancer therapeutics, in particular antiangiogenic drugs, may elicit tumor adaptation and its progression to a metastatogenic phenotype.
S312
817. Effective Sensitization of PaclitaxelResistant Colorectal Cancer Cells by New Cationic Micelle-Based Combined Delivery of Paclitaxel and XIAP siRNA
Yeon Lim Jang,1 Ui Jeong Yun,1 Min Sang Lee,1 Myung Goo Kim,1 Su Young Chae,1 Dong-Gyu Jo,1 Jae Hyung Park,2 Ji Hoon Jeong.1 1 School of Pharmacy, Sungkyunkwan University, Suwon, Korea; 2 Department of Chemical Engineering, Kyung Hee University, Suwon, Gyeonggi-do, Korea. Although a number of therapeutic treatments have been developed, cancer is still a leading cause of death. The problem seems to come from the complexity of the disease, which involves a lot of different molecules during its pathogenesis. This may be one of the reasons why cancer cannot be readily eradicated by a single treatment, such as small molecule-based chemotherapy. Chemotherapy is still the most widely used approaches for cancer treatment. One of the most challenging factors of chemotherapy is to overcome intrinsic and acquired drug resistance of cancer cells. Majority of anticancer drugs depend mainly on the induction of apoptosis for cancer cell death. However, since expression of antiapoptotic proteins such as Bcl-2 and inhibitors of apoptosis (IAPs) is significantly elevated in many types of cancers, the efficiency of chemotherapy is often limited by the resistance mechanism developed by cancer cells. In addition, the treatment of anticancer drugs can also induce the expression of the drug-resistant proteins. Simultaneous use of apoptosis-inducing drug and an inhibitor that blocks the action of anti-apoptotic proteins would address the drug resistance problems for cancers. In this case, best results can be expected if an apoptosis-inducing anticancer drug and inhibitors for anti-apoptotic proteins exist in the same space and time, i.e., the same intracellular space. Therefore, in this study, we used a new cationic micelle-based delivery system that can deliver water-insoluble anticancer drug and nucleic acid drug in a single vehicle. Previously, we showed a conjugate of bile acid and low molecular weight polyethylenimine (PEI 1.8 KDa) spontaneously formed cationic micelles in an aqueous milieu and showed highly efficient and consistent cellular delivery of nucleic acid drugs such as plasmid DNA and siRNA in various cells, including hybridomas, primary cells, and adult stem cells. The amphiphilic cationic micelle could also effectively dissolve an water-insoluble anticancer drug, paclitaxel. The paclitaxel-loaded cationic micelle was used for a combined delivery vehicle for siRNA. The siRNA silences the expression of antiapoptotic protein at post-transcriptional level while the anticancer drug induces apoptosis, leading to synergistic anticancer effect. Colorectal cancers are known to over-express XIAP, X-linked inhibitor of apoptosis, which reduces the action of paclitaxel. The delivery of XIAP siRNA efficiently reduced the amount of XIAP in colorectal cancer cell (HCT-116). The combined delivery of an apoptosis inducer, paclitaxel, and siRNA targeting XIAP (X-linked inhibitor of apoptosis) protein significantly increased the sensitivity of colon cancer cells for paclitaxel. The combined delivery system also demonstrated a desired synergic effect in an animal model bearing tumor xenograft.
Molecular Therapy Volume 19, Supplement 1, May 2011 Copyright © The American Society of Gene & Cell Therapy
813. Cytokine-Based Log-Scale Expansion of Functional Human Dendritic Cells from PBMCs
Yui Harada,1,2 Satoru Saito,1 Yosuke Morodomi,1 Kumi Yoshida,1 Tomohiko Ichikawa,2 Yoshikazu Yonemitsu.1 1 R&D Laboratory for Innovative Biotherapeutics, Kyushu University Graduate School of Pharmaceutical Sciences, Fukuoka, Japan; 2Departments of Urology, Chiba University Graduate School of Medicine, Chiba, Japan. PURPOSE: Dendritic cells (DCs) play a crucial role in maintaining the immune system. Though DC-based cancer immunotherapy has been suggested to hold potential to treat various kinds of malignancies, clinical efficacies are still insufficient in many human trials. We proved that this antitumor effect depends on the number of DCs (unpublished data), and it is necessary to prepare an enough number of DCs for effective treatments of tumors. In this study, therefore, we attempted to expand functional human DCs ex vivo with cytokine cocktail. Materials and Methods: Peripheral blood mononuclear cells (PBMCs) and CD14+ cells were obtained from volunteers. Conventional DCs were obtained from peripheral blood CD14+ cells as described previously with minor modification. Briefly, CD14+ cells were cultured under hGM-CSF and hIL-4 (GM/IL-4). CD3-depleted PBMCs were expanded and differentiated into DCs in the presence of hGM-CSF and hSCF (GM/SCF) or GM/IL-4 for several weeks. Expanded DC properties such as expression of surface markers, inflammatory cytokines production, phagocytotic activity, antigen presentating ability in vitro were analyzed, and compared with those of conventional DC. RESULTS: CD3-negative cells increased approximately 10 - 100 fold after 5 weeks culture and >80% of expanded cells expressed CD11c. Thus, by this method, 10 - 100 times more CD11c+ cells could be obtained than conventional procedures could. As are seen in conventional DCs, expanded DCs showed dendrites after maturation, and endocytotic activities. Expanded DCs also expressed HLA-DR, adhesion molecules, and co-stimulatory molecules and produced inflammatory cytokines as well as conventional DCs did. Functionally, mixed lymphocyte reaction (MLR) assay revealed that expanded DCs could stimulate allogenic T-cell proliferation to the same extent as conventional DCs. CONCLUSIONS: We found that human CD11c+ cells could be effectively expanded from PBMCs by culture with cytokine cocktail Molecular Therapy Volume 19, Supplement 1, May 2011 Copyright © The American Society of Gene & Cell Therapy
(GM/SCF). Expanded DC had properties that were required to obtain therapeutic gain. We expect that this technology will be able to contribute largely to both basic and clinical research of human cancer immunotherapy. DC expansion technology will improve therapeutic gain of cancer and alleviate patients’ burden of apheresis.
814. A New Method To Develop Genetically Modified Lung Cancer Stem Cells
Feridoun Karimi-Busheri,1 Victoria Zadorozhny,1 Ali Haghighi,1 Daniel L. Shawler,1 Habib Fakhrai.1 1 NovaRx Corporation, San Diego, CA. Discovery of cancer stem cells has initiated a new era that holds much promise and hope in the fight against cancer. Tumor stem cells are resistant to chemotherapy and radiation and are reputed to be one of the major causes of cancer recurrence. We have established an intense program to better understand lung cancer tumor stem cells and develop new therapeutic approaches against lung cancer, the most prominent, and most common, cancer killer in the world. The annual death due to this disease exceeds the combined deaths caused by colon, breast, prostate, and pancreatic cancers. Thus, development of an effective therapy is critical to serve this serious unmet medical need. Lung cancer causes sever morbidity and mortality and its cost to the society related to treatment costs, morbidity, and mortality approaches a 100 billion annually in the United States. Here we report the isolation and gene modification of lung cancer stem cells from established non-small cell lung cancer (NSCLC) cell lines and from primary cells of a NSCLC tumor xenograft established in NOD/SCID mice. We also present methodologies towards genetically engineering the isolated cells by antisense gene modification with the TGF-β antisense vector pKNC/SBA2 and the generation of largescale quantities of the gene modified tumor stem cells for utilization in clinical trials. Our data demonstrate that the secretion of TGF-β is significantly reduced by the transformed vector and expression of many genes is significantly altered in gene modified cells compared to the parental unmodified cell lines. Inclusion of a specific cancer stem cells vaccine as components of our whole tumor cell vaccine cocktails belagenpumatucel-L, which has shown effectiveness in 70 percent of the patients in a phase II clinical trial, may result in an even higher survival among the patients and decreasing tumor metastasize.
815. miRNA from Tumor-Associated Macrophages as Serum Biomarkers for Ovarian Cancer
Jonas Persson,1 Ines Beyer,1 Nicole Urban,2 Charles Drescher,2 Andre Lieber.1 1 Division of Medical Genetics, University of Washington, Seattle, WA; 2Fred Hutchinson Cancer Research Center, Seattle, WA. Our findings and published data show that ovarian cancers are heavily infiltrated by tumor-associated macrophages (TAMs). TAMs secrete factors that support tumor growth and prevent anti-tumor immune responses. There is a clear correlation between the number of TAMs and malignancy. Our central hypothesis is that TAM derived miRNA can serve as a serum biomarker for cancer. miRNAs have distinct expression profiles in different tissues. They are actively released from cells and highly stable in a cell-free form in the blood. To test our hypothesis, we isolated TAMs from mouse tumors or biopsies from ovarian cancer patients and compared their miRNA expression profiles with those of peripheral blood monocytes from animals or patients without tumors. Based on this, we selected a set of miRNA that were expressed at a significantly higher level in TAMs. In preliminary studies in mice, we found that several of these miRNAs were present at significantly lower levels in serum from mice with tumors compared to serum from control mice. Furthermore, the concentration of these miRNA inversely correlated with the tumor S311
CANCER-TARGETED GENE & CELL THERAPY III size in animals. By measuring the concentration of these miRNA in tumor cells and circulating TAMs, we came to the conclusion that serum miRNA were derived from circulating TAMs and that in tumor bearing mice less circulating TAMs and more tumor-localized TAMs were present. This explains the lower serum concentration of TAM-specific miRNA in serum of tumor bearing mice. Preliminary data with circulating human TAMs and serum miRNA corroborated the observations made in mice. We are currently conducting studies with a large number of PBMCs and serum from healthy donors and patients with different stages of ovarian cancer to assess the specificity and selectivity of TAM miRNA as biomarkers of ovarian cancer. As the use of tumor derived miRNA as biomarkers is complicated by the genetic and epigenetic instability of cancer cells, TAM-derived miRNAs might be a more reliable marker for early detection and prognosis of ovarian cancer.
816. Increased Invasiveness and Host Vessels Co-Option after 15-LO-1 and HSV-tk Combination Gene Therapy in Rat Glioma Model
Agnieszka Pacholska,1 Haritha Samaranayake,1,2 Jere Pikkarainen,1,2 Farizan Ahmad,1 Thomas Wirth,1 Seppo YläHerttuala.1 1 Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute, Kuopio, Finland; 2Ark Therapeutics Oy, Kuopio, Finland. One of the most fatal and refractory cancer type in humans is malignant glioma, out of which the most common and aggressive subtype is glioblastoma multiforme. Gliomas are among the most vascularised tumors in humans, what makes them a potential target for anti-angiogenic therapies. 15-lipoxygenase-1 (15-LO-1) is widely expressed in various cells and acts on diverse signal transduction pathways. It is known that 15-LO-1 may possess strong antiangiogenic properties. Recently, we have proved that 15-LO can also induce apoptosis by induction of lipid peroxidation in vivo and is able to significantly extent survival in rat malignant glioma. We concluded that 15-LO-1 gene therapy could be used as a promising cancer treatment acting through two independent mechanisms with pro-apoptotic therapeutic effects additionally being complemented by inhibition of tumor angiogenesis. Therefore, we tested the therapeutic potential of 15-LO gene therapy in combination with adenoviral herpes simplex thymidine kinase (AdHSV-tk) to investigate whether it could additionally enhance the effects of suicide gene therapy. BDIX male rats were injected with 104 BT4C glioma cells into the right corpus callosum. 15 days after cell inoculation the animals received 3 injections (2.5 µl per site) of both Adh15-LO-1 (2.7 x 1010 pfu/ml) and AdHSV-tk (1.45x1012 vp/ml), followed by two additional injections applied the next day and 14 days of gancyclovir treatment (50mg/kg). Combination gene therapy did not inhibit the tumor growth and showed no survival benefit. However, a profound effect on the migratory properties of the tumor cells was noted. The treatment induced a shift in glioblastoma tumor phenotype toward enhanced migration and healthy tissue infiltration, represented by formation of multiple satellite tumors. Moreover, co-option of the host vasculature became a compensatory mechanism to combination therapy, as the tumor cells ensheathed preexisting vessels and traveled along them to invade healthy tissue. Our results are in line with other reports, suggesting that some cancer therapeutics, in particular antiangiogenic drugs, may elicit tumor adaptation and its progression to a metastatogenic phenotype.
S312
817. Effective Sensitization of PaclitaxelResistant Colorectal Cancer Cells by New Cationic Micelle-Based Combined Delivery of Paclitaxel and XIAP siRNA
Yeon Lim Jang,1 Ui Jeong Yun,1 Min Sang Lee,1 Myung Goo Kim,1 Su Young Chae,1 Dong-Gyu Jo,1 Jae Hyung Park,2 Ji Hoon Jeong.1 1 School of Pharmacy, Sungkyunkwan University, Suwon, Korea; 2 Department of Chemical Engineering, Kyung Hee University, Suwon, Gyeonggi-do, Korea. Although a number of therapeutic treatments have been developed, cancer is still a leading cause of death. The problem seems to come from the complexity of the disease, which involves a lot of different molecules during its pathogenesis. This may be one of the reasons why cancer cannot be readily eradicated by a single treatment, such as small molecule-based chemotherapy. Chemotherapy is still the most widely used approaches for cancer treatment. One of the most challenging factors of chemotherapy is to overcome intrinsic and acquired drug resistance of cancer cells. Majority of anticancer drugs depend mainly on the induction of apoptosis for cancer cell death. However, since expression of antiapoptotic proteins such as Bcl-2 and inhibitors of apoptosis (IAPs) is significantly elevated in many types of cancers, the efficiency of chemotherapy is often limited by the resistance mechanism developed by cancer cells. In addition, the treatment of anticancer drugs can also induce the expression of the drug-resistant proteins. Simultaneous use of apoptosis-inducing drug and an inhibitor that blocks the action of anti-apoptotic proteins would address the drug resistance problems for cancers. In this case, best results can be expected if an apoptosis-inducing anticancer drug and inhibitors for anti-apoptotic proteins exist in the same space and time, i.e., the same intracellular space. Therefore, in this study, we used a new cationic micelle-based delivery system that can deliver water-insoluble anticancer drug and nucleic acid drug in a single vehicle. Previously, we showed a conjugate of bile acid and low molecular weight polyethylenimine (PEI 1.8 KDa) spontaneously formed cationic micelles in an aqueous milieu and showed highly efficient and consistent cellular delivery of nucleic acid drugs such as plasmid DNA and siRNA in various cells, including hybridomas, primary cells, and adult stem cells. The amphiphilic cationic micelle could also effectively dissolve an water-insoluble anticancer drug, paclitaxel. The paclitaxel-loaded cationic micelle was used for a combined delivery vehicle for siRNA. The siRNA silences the expression of antiapoptotic protein at post-transcriptional level while the anticancer drug induces apoptosis, leading to synergistic anticancer effect. Colorectal cancers are known to over-express XIAP, X-linked inhibitor of apoptosis, which reduces the action of paclitaxel. The delivery of XIAP siRNA efficiently reduced the amount of XIAP in colorectal cancer cell (HCT-116). The combined delivery of an apoptosis inducer, paclitaxel, and siRNA targeting XIAP (X-linked inhibitor of apoptosis) protein significantly increased the sensitivity of colon cancer cells for paclitaxel. The combined delivery system also demonstrated a desired synergic effect in an animal model bearing tumor xenograft.
Molecular Therapy Volume 19, Supplement 1, May 2011 Copyright © The American Society of Gene & Cell Therapy