Adenovirus-mediated transfer of Fas ligand gene augments radiation-induced apoptosis in U-373MG glioma cells

Protein Phosphatases-A Touchy Enemy in the Battle Against Glioblastomas: A Review

Glioblastoma (GBM) is the most common malignant tumor arising from brain parenchyma. Although many efforts have been made to develop therapies for GBM, the prognosis still remains poor, mainly because of the difficulty in total resection of the tumor mass from brain tissue and the resistance of the residual tumor against standard chemoradiotherapy. Therefore, novel adjuvant therapies are urgently needed. Recent genome-wide analyses of GBM cases have clarified molecular signaling mechanisms underlying GBM biology. However, results of clinical trials targeting phosphorylation-mediated signaling have been unsatisfactory to date. Protein phosphatases are enzymes that antagonize phosphorylation signaling by dephosphorylating phosphorylated signaling molecules. Recently, the critical roles of phosphatases in the regulation of oncogenic signaling in malignant tumor cells have been reported, and tumorigenic roles of deregulated phosphatases have been demonstrated in GBM. However, a detailed mechanism underlying phosphatase-mediated signaling transduction in the regulation of GBM has not been elucidated, and such information is necessary to apply phosphatases as a therapeutic target for GBM. This review highlights and summarizes the phosphatases that have crucial roles in the regulation of oncogenic signaling in GBM cells.

Radiogenic Therapy: Novel Approaches for Enhancing Tumor Radiosensitivity

Radiotherapy (RT) is a well established modality for treating many forms of cancer. However, despite many improvements in treatment planning and delivery, the total radiation dose is often too low for tumor cure, because of the risk of normal tissue damage. Gene therapy provides a new adjunctive strategy to enhance the effectiveness of RT, offering the potential for preferential killing of cancer cells and sparing of normal tissues. This specificity can be achieved at several levels including restricted vector delivery, transcriptional targeting and specificity of the transgene product. This review will focus on those gene therapy strategies that are currently being evaluated in combination with RT, including the use of radiation sensitive promoters to control the timing and location of gene expression specifically within tumors. Therapeutic transgenes chosen for their radiosensitizing properties will also be reviewed, these include:

gene correction therapy, in which normal copies of genes responsible for radiation-induced apoptosis are transfected to compensate for the deletions or mutated variants in tumor cells (p53 is the most widely studied example). enzymes that synergize the radiation effect, by generation of a toxic species from endogenous precursors ( e.g., inducible nitric oxide synthase) or by activation of non toxic prodrugs to toxic species ( e.g., herpes simplex virus thymidine kinase/ganciclovir) within the target tissue. conditionally replicating oncolytic adenoviruses that synergize the radiation effect. membrane transport proteins ( e.g., sodium iodide symporter) to facilitate uptake of cytotoxic radionuclides.

The evidence indicates that many of these approaches are successful for augmenting radiation induced tumor cell killing with clinical trials currently underway.

Radiation triggering immune response and inflammation

Radiation therapy (RT) is a well-established but still under optimization branch of Cancer Therapy (CT). RT uses electromagnetic waves or charged particles in order to kill malignant cells, by accumulating the energy onto these cells. The issue at stake for RT, as well as for any other Cancer Therapy technique, is always to kill only cancer cells, without affecting the surrounding healthy ones. This perspective of CT is usually described under the terms "specificity" and "selectivity". Specificity and selectivity are the ideal goal, but the ideal is never entirely achieved. Thus, in addition to killing healthy cells, changes and effects are observed in the immune system after irradiation. In this review, we mainly focus on the effects of ionizing radiation on the immune system and its components like bone marrow. Additionally, we are interested in the effects and benefits of low-dose ionizing radiation on the hematopoiesis and immune response. Low dose radiation has been shown to induce biological responses like inflammatory responses, innate immune system activation and DNA repair (adaptive response). This review reveals the fact that there are many unanswered questions regarding the role of radiation as either an immune-activating (low dose) or immunosuppressive (high dose) agent.

Chapter seven--Cancer treatment with gene therapy and radiation therapy

Radiation therapy methods have evolved remarkably in recent years which have resulted in more effective local tumor control with negligible toxicity of surrounding normal tissues. However, local recurrence and distant metastasis often occur following radiation therapy mostly due to the development of radioresistance through the deregulation of the cell cycle, apoptosis, and inhibition of DNA damage repair mechanisms. Over the last decade, extensive progress in radiotherapy and gene therapy combinatorial approaches has been achieved to overcome resistance of tumor cells to radiation. In this review, we summarize the results from experimental cancer therapy studies on the combination of radiation therapy and gene therapy.

Clinical study of recombinant adenovirus-p53 combined with fractionated stereotactic radiotherapy for hepatocellular carcinoma

OBJECTIVE

The purpose of our study was to evaluate the feasibility and treatment outcomes of recombinant adenovirus-p53 (rAd-p53, trademarked as Gendicine) combined with fractionated stereotactic radiotherapy (fSRT) in treatment of primary hepatocellular carcinoma (HCC).

METHODS

We randomly enrolled 40 patients with HCC treated by fSRT alone (fSRT group) or rAd-p53 combined with fSRT (combined group). Tumor size was 2-5.2 cm (average 3.2 cm). We prescribed 50 Gy in 10 fractions at the 50%-80% isodose line of the planning target volume for 2 weeks in two groups. The combined group was treated with two intratumoral injections of rAd-p53 on day 1 and 8 while fSRT started on day 3. Tumor response was assessed after treatment using modified WHO criteria. The follow-up period was 11-44 months (median 35 months).

RESULTS

The overall response rate of fSRT group was 70%, with 4 patients showing complete response (20%), 10 partial response (50%) and 6 stable disease (30%). Correspondingly the overall response rate of combined group was 85%, with 7 patients showing complete response (35%), 10 partial response (50%) and 3 stable disease (15%). The 1-year survival rates of fSRT group and combined group were 70.0% and 90.0%, respectively. The 1-year disease-free survival rates of fSRT group and combined group were 65% and 85%, respectively. These treatments were well tolerated, because grade 3 or 4 toxicity was not observed.

CONCLUSION

These results suggest that rAd-p53 combined with fSRT is a relatively safe and effective method for treating primary hepatocellular carcinoma compared with only fSRT. Thus, rAd-p53 combined with fractionated SRT may be preferred as a choice of local treatment for primary HCC when the patients are inoperable or when the patients refuse operation.

Genetic control of wayward pluripotent stem cells and their progeny after transplantation

The proliferative capacity of pluripotent stem cells and their progeny brings a unique aspect to therapeutics, in that once a transplant is initiated the therapist no longer has control of the therapy. In the context of the recent FDA approval of a human ESC trial and report of a neuronal-stem-cell-derived tumor in a human trial, strategies need to be developed to control wayward pluripotent stem cells. Here, we focus on one approach: direct genetic modification of the cells prior to transplantation with genes that can prevent the adverse events and/or eliminate the transplanted cells and their progeny.

Gene therapy for carcinoma of the breast

In view of the limited success of available treatment modalities for breast cancer, alternative and complementary strategies need to be developed. The delineation of the molecular basis of breast cancer provides the possibility of specific intervention by gene therapy through the introduction of genetic material for therapeutic purposes. In this regard, several gene therapy approaches for carcinoma of the breast have been developed. These approaches can be divided into six broad categories: (1) mutation compensation, (2) molecular chemotherapy, (3) proapoptotic gene therapy, (4) antiangiogenic gene therapy, (5) genetic immunopotentiation, and (6) genetic modulation of resistance/sensitivity. Clinical trials for breast cancer have been initiated to evaluate safety, toxicity, and efficacy. Combined modality therapy with gene therapy and chemotherapy or radiation therapy has shown promising results. It is expected that as new therapeutic targets and approaches are identified and advances in vector design are realized, gene therapy will play an increasing role in clinical breast cancer treatment.

Retroviral Immunotoxin Gene Therapy of Leukemia in Mice Using Leukemia-Specific T Cells Transduced with an Interleukin-3/Bax Fusion Protein Gene

In past studies, we showed that T cells transduced with retroviral diphtheria immunotoxin (IT) target genes could serve as vehicles for delivering IT to tumors in vivo. We took advantage of the observation that antigen-specific T cells are able to penetrate tumors to design an approach delivering combined cellular and humoral therapy directly to the tumor site. To improve tumor specificity, we selected interleukin (IL)-3 as a ligand because its receptor is selectively overexpressed on myeloid leukemia progenitors. Because Bcl-2 family proteins show structural similarity to diphtheria toxin (DT), we constructed a unique retroviral IT using Bax, a proapoptotic member of the Bcl-2 family, in place of DT. Bax was chosen because several studies showed that its transduction induces lethal apoptosis in different cancers. The retroviral construct for gene therapy included IL-3 positioned downstream of its 80 amino acid leader, and permitted cotranslational protein synthesis of hybrid IL-3/human Bax fusion protein. Other vectors were constructed with IL-3 fused to DT or Pseudomonas exotoxin. Retroviral vectors were used to transiently transduce C8, a CD4(+) T cell clone that specifically recognized FBL-3, a lethal myeloid leukemia. Supernatants collected from transduced cells showed proapoptotic activity and selectively inhibited FBL-3 cells in vitro. Intraperitoneal injection of transduced but not nontransduced C8 into mice with subcutaneous tumors or systemic cancer significantly inhibited tumor growth. These results indicate that retroviral IT made with IL-3 and various toxic proteins may be useful in patients with acute myelogenous leukemia (AML). Furthermore, the Bax construct may be particularly useful as a nonimmunogenic substitute for bacterial toxins in retIT.

Apoptosis in glioma cells: review and analysis of techniques used for study with focus on the laser scanning cytometer

Traditional approaches to the treatment of brain tumors are based on the hypothesis that tumors arise and grow because of the disordered regulation of cell proliferation. More recently, it has become apparent that tumor growth depends not only on the rate of cell proliferation but also on the rate of apoptosis (programmed cell death). Genomic alterations that occur in malignancy may limit the cell's ability to undergo apoptosis. Many new treatment strategies for gliomas stem from the use of techniques aimed at manipulating apoptosis. Being able to assess the efficacy of experimental treatments with refined techniques and being able to use instruments that can provide accurate measurements of the apoptotic markers will open the door for discovering novel strategies with the potential to induce effective and selective cytotoxicity. We discuss here in detail the major traditional techniques of assessing apoptosis. We provide an overview of cytometric techniques, including flow cytometry (FC), and will compare it with the laser scanning cytometer (LSC). This is a powerful new tool with potential for obtaining a fast and objective analysis of apoptosis through multiple mechanisms, as well as for assessing proliferation and DNA ploidy in solid malignant tumors.

Cytokine receptor as a sensitizer for targeted cancer therapy

Introducing a cytokine receptor as a sensitizer into cancer cells offers a unique opportunity for receptor-targeted cancer therapy. It has been shown that transfection of the tumor necrosis factor (TNF) receptor gene in cancer cells or exposing cancer cells to certain reagents which increase expression of TNF receptors results in enhancement of the cytotoxic effect of TNF. In addition, the literature suggests that Fas/CD95-mediated apoptotic tumor cell killing is augmented by gene transfer of Fas into cancer cells or treatment of cells with agents like cisplatin and interferon (IFN)-gamma. In contrast to these approaches, we have discovered a new approach to cancer therapy; wherein introduction of a cytokine receptor chain into cancer cells sensitizes them to receptor-directed cytotoxins. We have demonstrated that when interleukin (IL)-13 receptor (IL-13R) alpha2 chain, one of the two known IL-13 binding proteins, is introduced into cancer cells that do not express this chain the cells acquire extreme sensitivity to a chimeric fusion cytotoxin composed of IL-13 and a mutated form of Pseudomonas exotoxin (IL13-PE). Cells that do not express this chain or express low levels show limited sensitivity to IL13-PE. Acquisition of sensitivity to IL13-PE was observed both in vitro and in vivo when IL-13R alpha2-transfected human tumor cells were implanted in immunodeficient animals followed by systemic or regional IL13-PE therapy. Our third generation experiments suggest that this approach is feasible for clinical situations as intratumor administration of plasmid carrying the IL-13R alpha2 chain gene sensitized these tumors to systemic or regional IL13-PE therapy. This unique approach comprising gene transfer of cytokine receptor chain and receptor-targeted cytotoxin administration represents a novel strategy for cancer therapy.