Synergistic Inhibition Of Tumor Growth Research Articles

766: Synergistic Inhibition of Tumor Growth and Metastasis by Combined Treatment with an Antiangiogenic Agent TNP-470 and Gemcitabine in a Human Bladder Cancer KoTCC-1 Model

766: Synergistic Inhibition of Tumor Growth and Metastasis by Combined Treatment with an Antiangiogenic Agent TNP-470 and Gemcitabine in a Human Bladder Cancer KoTCC-1 Model

Synergistic inhibition of tumor growth and metastasis by combined treatment with TNP-470 and docetaxel in a human prostate cancer PC-3 model

TNP-470, a potent inhibitor of angiogenesis, was reported to synergistically enhance the antitumor effects of cytotoxic agents. The objective of this study was to evaluate the effectiveness of combined treatment with TNP-470 and docetaxel both in vitro and in vivo using androgen-independent human prostate cancer PC-3 cells. The in vitro growth-inhibitory and apoptotic effects of docetaxel and/or TNP-470 on PC-3 cells were assessed using MTT and TUNEL assays. The combined effect of docetaxel and TNP-470 therapy after subcutaneous and orthotopic injection of PC-3 cells into athymic nude mice was evaluated. In vivo effects of this combined regimen on PC-3 tumors were analyzed by the TUNEL assay and immunohistochemical staining of CD31 to quantify microvessel density (MVD). Combined treatment with TNP-470 and docetaxel synergistically inhibited PC-3 cell growth in vitro through the enhanced induction of apoptotic cell death compared with treatment with either agent alone, a result explained, at least in part, by the down-regulation as well as phosphorylation of potential anti-apoptotic genes, Bcl-2 and Bcl-XL. Combined treatment with TNP-470 and docetaxel synergistically suppressed subcutaneous PC-3 tumor growth compared with treatment with either agent alone. Furthermore, this combined regimen significantly inhibited orthotopic PC-3 tumor growth and reduced the incidence of lymph node metastasis. Immunohistochemical analysis of the subcutaneous tumor after each treatment demonstrated that administration of docetaxel as well as TNP-470 significantly induced apoptotic cell death; in contrast, a significant reduction in MVD was observed only after TNP-470. These findings suggest that docetaxel and TNP-470 act synergistically to inhibit PC-3 tumor growth and metastasis, by enhancing apoptosis and suppressing angiogenesis.

Pharmacology and Pharmacodynamics of Bevacizumab as Monotherapy or in Combination with Cytotoxic Therapy in Preclinical Studies

Preclinical models have examined the pharmacologic and pharmacodynamic activities of an anti-vascular endothelial growth factor (VEGF) humanized, monoclonal antibody, bevacizumab, and/or its murine equivalent A4.6.1. These studies found that single-agent therapy with bevacizumab/A4.6.1 resulted in tumor growth inhibition of 20 different human tumor cell lines (13 tumor types) implanted into nude mice irrespective of the route of administration or tumor location. Several of these studies also observed significant inhibition of tumor metastases. Various studies have examined the feasibility of combining anti-VEGF therapy with cytotoxic or biological agents. Combining bevacizumab/A4.6.1 with doxorubicin, topotecan, paclitaxel, docetaxel, or radiotherapy resulted in additive or synergistic tumor growth inhibition. Changes in vascular functions were frequently reported, including decreased vessel diameter, density, and permeability in response to treatment. A reduction in interstitial fluid pressure was also observed. In some studies, these improvements resulted in an increase in intratumoral uptake of chemotherapy, implying that the most effective use of anti-VEGF therapy is in combination with chemotherapy. Alternatively, combination treatment with radiation increased tumor oxygenation and tumor growth inhibition. Interestingly, anti-VEGF therapy has also been reported to reduce the development of ascites in ovarian mouse models. Finally, safety pharmacology studies with bevacizumab in cynomolgus monkeys showed that this agent is generally well tolerated with no unexpected adverse events.

The proteasome inhibitor bortezomib synergizes with gemcitabine to block the growth of human 253JB-V bladder tumors in vivo

Abstract Bortezomib (PS-341, Velcade) is a dipeptidyl boronic acid inhibitor of the 20S proteasome that was developed as a therapeutic agent for cancer. Here, we investigated the effects of bortezomib on the growth of human 253JB-V bladder cancer cells. Although the drug did not stimulate significant increases in levels of apoptosis, it inhibited cell growth in a concentration-dependent fashion and augmented the growth inhibitory effects of gemcitabine in vitro. These effects were associated with accumulation of p53 and p21 and suppression of cyclin-dependent kinase 2 activity. Bortezomib also inhibited secretion of the proangiogenic factors matrix metalloproteinase-9, interleukin-8 (IL-8), and vascular endothelial growth factor (VEGF). In vivo studies with 253JB-V tumors growing in nude mice demonstrated that bortezomib (1 mg/kg) did not inhibit tumor growth when it was delivered as a single agent, although it reduced tumor microvessel density and inhibited expression of VEGF and IL-8. However, combination therapy with bortezomib plus gemcitabine produced synergistic tumor growth inhibition associated with strong suppression of tumor cell proliferation. Together, our results demonstrate that bortezomib has significant antiproliferative activity in aggressive bladder cancer cells, which is best exploited within the context of combination chemotherapy.

Protein kinase A as target for novel integrated strategies of cancer therapy.

We have studied the role of protein kinase A (PKA) in neoplastic transformation, apoptosis, and angiogenesis and its relationship with other signaling molecules, as a basis for developing novel therapeutic strategies. We demonstrated the involvement of PKA type I (PKA-I) in the transduction of mitogenic signals from different sources and demonstrated functional and structural interactions between PKA-I and the activated epidermal growth factor receptor (EGFR). We contributed to the identification and development of several selective inhibitors of PKA-I, such as 8-Cl-cAMP and a hybrid DNA/RNA antisense oligonucleotide of a novel class (AS-PKA-I) and of EGFR, including mAbC225 and ZD1839 (Iressa). All these agents have been investigated in cancer patients. We demonstrated the therapeutic potential of the combined blockade of PKA-I and EGFR, reporting a synergistic antitumor effect when their inhibitors are used in combination. We have also shown that PKA-I and EGFR inhibitors are able to cooperate with selected class of cytotoxic drugs and with ionizing radiation, causing a synergistic inhibition of tumor growth in vitro and in vivo, accompanied by inhibition of expression of growth and angiogenic factors and by suppression of vessel production. Moreover, PKA-I is implicated in a bcl-2-dependent apoptotic pathway, and we have recently reported a cooperative antitumor and proapoptotic effect of AS-PKA-I in combination with an AS-bcl-2. Finally, we have shown that AS-PKA-I also has antitumor and antiangiogenic effects following oral administration and that they can be greatly enhanced in combination with oral ZD1839 and oral taxanes.

Synergistic chemosensitization and inhibition of tumor growth and metastasis by adenovirus-mediated p53 gene transfer in human bladder cancer model

Objectives. To determine whether an adenovirus-mediated p53 gene (Ad5CMV-p53) transfer enhances cisplatin cytotoxicity in vitro and whether Ad5CMV-p53 and cisplatin synergistically inhibit growth and metastasis in vivo using human bladder cancer KoTCC-1 cells. Methods. MTT assays and DNA fragmentation assays were used to examine the effects of treatment with Ad5CMV-p53 and/or cisplatin on growth inhibition and induction of apoptosis, respectively, in KoTCC-1 cells. The efficacies of combined Ad5CMV-p53 and/or cisplatin therapy against growth and metastasis of KoTCC-1 tumors were assessed using subcutaneous and orthotopic tumor cell injection models. Results. Ad5CMV-p53 substantially enhanced cisplatin chemosensitivity in a dose-dependent manner, reducing the median IC 50 by more than 50%. Characteristic apoptotic DNA laddering was induced by the combination of sublethal doses of Ad5CMV-p53 and cisplatin, but not by either agent alone. Furthermore, combined Ad5CMV-p53 and cisplatin therapy synergistically inhibited growth of subcutaneous KoTCC-1 tumors and the incidence of metastasis after orthotopic injection. Conclusions. These findings illustrate that combined treatment with Ad5CMV-p53 and cisplatin could be an attractive strategy for inhibiting progression of bladder cancer through effective induction of apoptosis.

Synergistic inhibition of tumor growth in a murine mammary adenocarcinoma model by combinational gene therapy using IL-12, pro-IL-18, and IL-1beta converting enzyme cDNA.

We report here that a cancer gene therapy protocol using a combination of IL-12, pro-IL-18, and IL-1beta converting enzyme (ICE) cDNA expression vectors simultaneously delivered via gene gun can significantly augment antitumor effects, evidently by generating increased levels of bioactive IL-18 and consequently IFN-gamma. First, we compared the levels of IFN-gamma secreted by mouse splenocytes stimulated with tumor cells transfected with various test genes, including IL-12 alone; pro-IL-18 alone; pro-IL-18 and ICE; IL-12 and pro-IL-18; and IL-12, pro-IL-18, and ICE. Among these treatments, the combination of IL-12, pro-IL-18, and ICE cDNA resulted in the highest level of IFN-gamma production from splenocytes in vitro, and similar results were obtained when these same treatments were delivered to the skin of a mouse by gene gun and IFN-gamma levels were measured at the skin transfection site in vivo. Furthermore, the triple gene combinatorial gene therapy protocol was the most effective among all tested groups at suppressing the growth of TS/A (murine mammary adenocarcinoma) tumors previously implanted intradermally at the skin site receiving DNA transfer by gene gun on days 6, 8, 10, and 12 after tumor implantation. Fifty percent of mice treated with the combined three-gene protocol underwent complete tumor regression. In vivo depletion experiments showed that this antitumor effect was CD8(+) T cell-mediated and partially IFN-gamma-dependent. These results suggest that a combinatorial gene therapy protocol using a mixture of IL-12, pro-IL-18, and ICE cDNAs can confer potent antitumor activities against established TS/A tumors via cytotoxic CD8(+) T cells and IFN-gamma-dependent pathways.

Synergistic inhibition of lymphoid tumor growth in vitro by combined treatment with the iron chelator deferoxamine and an immunoglobulin G monoclonal antibody against the transferrin receptor

Data are presented indicating that the growth of 5 out of 5 murine lymphoid tumors can be inhibited in a synergistic fashion in vitro by combined treatment with the iron chelator deferoxamine (DFO) and an immunoglobulin G (IgG) monoclonal anti-transferrin receptor antibody (ATRA). A two-way dose/response analysis shows that the ATRA becomes more efficient as an inhibitor with increasing doses of DFO. Flow cytometric studies further support the view that IgG ATRAS impair transferrin receptor (TR) function by causing TR down-modulation and degradation, even when the presence of DFO acts to promote increased cell surface TR expression. It is also shown that an IgG ATRA is nearly as effective as an IgM ATRA in inhibiting tumor cell growth when used in combination with DFO. Finally, studies with the iron chelator picolinic acid show that it produces only additive, or very slightly supra-additive, effects when used in combination with the ATRA. Therefore, these studies not only continue to suggest that combination chelator/ATRA therapy warrants further investigation as a tool in the therapy of hematopoietic malignancies, but also make the following new points: (1) the clinically familiar iron chelator deferoxamine, but not all iron chelators, produces synergistic inhibition of tumor growth in vitro with ATRAS; and (2) IgG ATRAS, which may be clinically more attractive reagents than IgA or IgM ATRAS because of better access to extra vascular tissue spaces, have unexpectedly been found to function as powerful growth inhibitors when used in combination with DFO.

Synergistic Inhibition of Lymphoid Tumor Growth In Vitro by Combined Treatment With the Iron Chelator Deferoxamine and an Immunoglobulin G Monoclonal Antibody Against the Transferrin Receptor

Data are presented indicating that the growth of 5 out of 5 murine lymphoid tumors can be inhibited in a synergistic fashion in vitro by combined treatment with the iron chelator deferoxamine (DFO) and an immunoglobulin G (IgG) monoclonal anti-transferrin receptor antibody (ATRA). A two-way dose/response analysis shows that the ATRA becomes more efficient as an inhibitor with increasing doses of DFO. Flow cytometric studies further support the view that IgG ATRAS impair transferrin receptor (TR) function by causing TR down-modulation and degradation, even when the presence of DFO acts to promote increased cell surface TR expression. It is also shown that an IgG ATRA is nearly as effective as an IgM ATRA in inhibiting tumor cell growth when used in combination with DFO. Finally, studies with the iron chelator picolinic acid show that it produces only additive, or very slightly supra-additive, effects when used in combination with the ATRA. Therefore, these studies not only continue to suggest that combination chelator/ATRA therapy warrants further investigation as a tool in the therapy of hematopoietic malignancies, but also make the following new points: (1) the clinically familiar iron chelator deferoxamine, but not all iron chelators, produces synergistic inhibition of tumor growth in vitro with ATRAS; and (2) IgG ATRAS, which may be clinically more attractive reagents than IgA or IgM ATRAS because of better access to extra vascular tissue spaces, have unexpectedly been found to function as powerful growth inhibitors when used in combination with DFO.

Synergistic activity of tumor necrosis factor and interferon in a nude mouse model of human ovarian cancer

In vitro and in vivo studies suggest a synergistic inhibition of tumor growth by the combination of certain interferons and tumor necrosis factors. We have examined the activity of two of these agents in an animal model of human ovarian cancer. The human ovarian cancer cell line SK-OV3 was grown subcutaneously in immunodeficient mice. Mean relative tumor volume was determined weekly by external tumor measurements and a standard formula. Animals were treated by intraperitoneal injection with (1) recombinant human tumor necrosis factor α (rHTNF) 5 or 10 μg/day; (2) recombinant murine Interferon γ (rMIFN) 5 × 10 4 units per day; or (3) a combination of rHTNF 5 μg/day and rMIFN 5 × 10 4 units/day. Simultaneous control groups were run for all experiments. Administration of rHTNF alone in either dose had no effect on rate of tumor growth. Administration of rMIFN at a dose of 5 × 10 4 units/day produced a marginal decrease in rate of tumor growth. Animals receiving both rHTNF 5 μg/day and rMIFN 5 × 10 4 units daily showed marked inhibition of tumor growth, with the mean relative tumor volume after 4 weeks of treatment measuring 0.75 ± 0.91 in the treatment group and 11.06 ± 2.6 in the control group. rHTNF and rMIFN demonstrate a synergistic inhibition of tumor growth in this animal model of human ovarian cancer.

Tumor Necrosis Factor (TNF) とHyperthermia の抗腫瘍性相乗効果とその機序

A synergistic increase in the cytotoxic effects of recombinant human tumor necrosis factor (TNF) and hyperthermia was demonstrated both in vitro and in vivo. The cytotoxicity of TNF against L-M cells in incubation for 12 h at 38.5 and 40°C based on the concentration necessary for 50% cytotoxicity was, respectively, 125 and more than 500 times as high as in similar incubation at 37°C. And, it was also shown to be ralated to an accelerated turnover rate of TNF receptor complex under elevated temperatures rather than to changes in number of cell receptors or binding strength.As observed 18 days after implantation of Meth-A fibrosarcoma cells in mice, single i. v. administration of TNF at 1, 000 units/mouse resulted in complete cures in five mice when performed in combination with hyperthermia (40°C), whereas TNF alone in the same dose resulted in 27.1% inhibition of tumor growth and hyperthermia alone had no appreciable effect on tumor growth. The i. v. administration of TNF three times at 100 or 300 units/mouse together with hyperthermia (40°C) resulted in 41.2 and 89.0% tumor growth inhibition, respectively ; similar administration without hyperthermia appeared to have little or no appreciable effect on tumor growth.A clearly synergistic inhibition of metastatic tumor growth by combined administration of TNF (300 units) and hyperthermia (40°C, 30 min) was also observed in BALB/c mice previously given injections of 1 × 106 Meth-A (F15) cells/mouse via tail vein, neither of which alone resulted in significant inhibition.The results suggest that combination therapy including TNF and hyperthermia may be of value in the treatment of malignancy in human patients.