Clinical update of Ad-p53 gene therapy for lung cancer

MicroRNA-503 Inhibits Non-Small Cell Lung Cancer Progression By Targeting PDK1/PI3K/AKT Pathway

OBJECTIVES

The aim of the study was to study the role of dysregulated expression of a microRNA (miRNA), miR-503, in non-small-cell lung cancer (NSCLC) and investigate the underlying mechanism.

METHODS

Quantitative real-time PCR (qRT-PCR) and in situ hybridization staining (ISH) were used to evaluate the expression level of miR-503 in NSCLC tissues and paired adjacent tissues. CCK-8, colony formation and flow cytometry were performed to explore the effects of miR-503 overexpression on cell proliferation, colony formation and apoptosis. Cells with miR-503 overexpression were used to initiate xenograft models. Dual luciferase reporter assay, qRT-PCR, immunohistochemistry and Western blotting were conducted to investigate the interaction of miR-503 and its potential target.

RESULTS

Significantly downregulated miR-503 was found in NSCLC tumor tissues and cell lines. miR-503 overexpression significantly inhibited NSCLC cell proliferation, migration and invasion. PDK1 was predicted as the direct targets of miR-503. PDK1 overexpression reversed the inhibitory effects of miR-503 on biological functions, while PDK1 silencing significantly counteracted miR-503 inhibitor-induced pro-tumor effects in A549 cells. Mechanistically, upregulation of miR-503 inhibited PDK1 expression and subsequently caused the inactivation of PI3K/AKT pathway.

CONCLUSION

Our results suggest that miR-503 inhibits NSCLC progression by targeting PDK1/PI3K/AKT pathway, potentiating the use of miR-503 as a biomarker and therapeutic target for NSCLC.

Evaluation of efficacy and safety for recombinant human adenovirus-p53 in the control of the malignant pleural effusions via thoracic perfusion

A certain number of studies have showed that p53 gene transfer has an anti-tumor activity in vitro and in vivo. This study was to evaluate the efficacy and safety of thoracic perfusion of recombinant human adenovirus p53 (rAd-p53, Gendicine) for controlling malignant pleural effusion (MPE). We searched for the relevant studies from the database of MEDLINE, Web of Science, EMBASE, Cochrance Library and CNKI to collect the trials concerning the efficacy and safety of rAd-p53 to treat MPE. Fourteen randomised controlled trials (RCTs) with 879 patients were involved in this analysis. The rAd-p53 combined with chemotherapeutic agents significantly improved the overall response rate (ORR) (P < 0.001; odds ratio = 3.73) and disease control rate (DCR) (P < 0.001; odds ratio = 2.32) of patients with MPE as well as the quality of life (QOL) of patients (P < 0.001; odds ratio = 4.27), compared with that of chemotherapeutic agents alone. In addition, the participation of rAd-p53 did not have an obvious impact on the most of incidence of adverse reactions (AEs) (P < 0.05) except the fever (P < 0.001). However, the fever was self-limited and could be tolerated well. The application of rAd-p53 through thoracic perfusion for treating MPE had a better efficacy and safety, which could be a potential choice for controlling MPE.

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.

Efficacy of recombinant adenoviral human p53 gene in the treatment of lung cancer-mediated pleural effusion

Pleural effusion induced by lung cancer exerts a negative impact on quality of life and prognosis. The aim of the present study was to evaluate the value of the recombinant adenoviral human p53 gene (rAd-p53) in the local treatment of lung cancer and its synergistic effect with chemotherapy. The present study retrospectively recruited 210 patients with lung cancer-mediated pleural effusion who had adopted a treatment strategy of platinum chemotherapy. Pleurodesis was performed via the injection of cisplatin or rAd-p53. Long-term follow-up was conducted to investigate the therapeutic effects of cisplatin and rAd-p53 administration on pleural effusion and other relevant clinical indicators. The short-term effect of pleurodesis was as follows: The efficacy rate of rAd-p53 therapy was significantly higher compared with cisplatin therapy (71.26 vs. 54.47%), and the efficacy of treatment with ≥2×1012 viral particles of rAd-p53 for pleurodesis was significantly greater than treatment with 40 mg cisplatin (P<0.05). Furthermore, efficacy analysis performed 6 and 12 months after pleurodesis indicated that the efficacy rate of rAd-p53 was significantly greater than that of cisplatin (P<0.05). A comparison of median progression-free survival (PFS) time identified a significant difference (P<0.05) between rAd-p53 and cisplatin therapy (3.3 vs. 2.7 months); however, a comparison of median overall survival time identified no significant difference (P>0.05) between rAd-p53 and cisplatin therapy (9.6 vs. 8.7 months). In addition, Cox regression analysis indicated that PFS was not affected by clinical indicators such as age, gender, prognostic staging and smoking status; however, PFS was affected by pathological subtype (adenocarcinoma or squamous carcinoma) in the rAd-p53 group. rAd-p53 administration for pleurodesis exerts long-term therapeutic effects on the local treatment of lung cancer. Thus, a combination of rAd-p53 and chemotherapy may exert a synergistic effect and reverse multidrug resistance.

Adenovirus-mediated IL-24 confers radiosensitization to human lung adenocarcinoma in vitro and in vivo

The current paper aims to study the effect of adenovirus-mediated IL-24 (Ad-IL-24) on human lung adenocarcinoma in vitro and in vivo and determine its possible mechanism of action. The growth-suppressing and apoptosis-inducing effects of Ad-IL-24, radiotherapy, and Ad-IL-24+ radiotherapy (hereinafter referred to as the joint group) on SPC-A1 lung carcinoma cells were assessed by using 3-(4,5-dimethyliazolyl-2)-2,5-diphnyltetrazolium bromide and flow cytometry. A human lung model was established with SPC-A1 cells in nude mice. Groups of mice were subjected to multi-point injections to their tumors. Gross tumor volumes were measured dynamically. The ratios of tumor suppression and radiosensitization effect were evaluated according to the method of probability sum Q values. The expressions of Bax, Bcl-2, Survivin, and Caspase-3 in tumor samples were detected by immunohistochemistry. The ratios of inhibition and apoptosis in the joint group were higher than those in the individual Ad-IL-24 and radiotherapy groups. In vitro, the joint group suppressed tumor growth conspicuously, showing a weight inhibition rate of about 64 %. The expressions of FasL, Bax and Caspase-3 were upregulated in the joint group, while the expressions of Cox,Bcl-2,VEGF,CD34 and Survivin were downregulated. The current study proves that Ad-IL-24 suppresses growth of SPC-A1 cells both in vitro and in vivo. Its functions appear to be related to cell apoptosis and antiangiogenesis.

Immunoexpression and prognostic role of p53 in different subtypes of epithelial ovarian carcinoma

We sought to investigate the significance of p53 expression for epithelial ovarian carcinoma. In this study, we used immunohistochemical method to investigate the expression patterns of p53 in different subtypes of epithelial ovarian carcinoma. We found that the expressions of p53 protein in epithelial ovarian cancer (pituita, serosity and intima) were 88.9%, 75% and 100%, respectively, while the recurrence rates among three cancer subtypes were significantly different (33.3%, 12.5% and 0%, respectively; P < 0.05). Compared with patients without lymph node metastasis, the expression of p53 in patients with lymph node metastasis was significantly strong (68.75% and 100%, respectively; P < 0.05). However, the recurrence rate in the patients with lymph node metastasis (40%) was higher than that without lymph node metastasis (6.25%, P < 0.05). The expressions of p53 protein in ovarian cancer between I-II (25%) stage and II-IV stage (100%) were significantly different (P < 0.05), and the recurrence rates between the two groups were significantly different (0% and 31.25%, respectively, P < 0.05). Therefore, p53 protein has an intimate relationship with the malignant degree and the prognosis of ovarian cancer.

p53 gene therapy modulates signal transduction in the apoptotic and cell cycle pathways downregulating neointimal hyperplasia

PURPOSE

To investigate the molecular mechanisms that lead to inhibition of intimal hyperplasia (IH) following p53 gene therapy.

METHODS

In vivo p53 gene transfer to balloon injured rat carotid arteries was performed by utilizing adenovirus. The relationship between p53, p21, retinoblastoma protein (Rb), B-cell lymphoma 2 (Bcl-2), Bax, and Bcl-x was examined by immunohistochemistry. Expression of cyclin D1, Fas/CD95, and poly(ADP-ribose)polymerase (PARP) was determined.

RESULTS

Our data indicate increased expression of p53 in the nuclei of vascular smooth muscle cells (VSMCs) in the media (P < .01) compared with the controls. In the treated animals, Bax and Bcl-x, p21, and Rb were significantly upregulated (P < .01). Immunoreactivity to Bcl-2 was observed only in the neointima of untreated groups at 14 days. An increased presence of Fas and decreased expression of PARP was observed in the cytoplasm of the VSMCs of p53-treated animals.

CONCLUSIONS

P53 gene transfer activated a battery of downstream effector genes whose products are directly involved in cell cycle arrest, DNA repair, and apoptosis.

Deuterium-depleted water inhibits human lung carcinoma cell growth by apoptosis

To investigate the in vivo and in vitro inhibitory effects of deuterium-depleted water (DDW) on human lung cancer and the possible mechanisms underlying these effects, we cultured and treated human lung carcinoma cell line A549 and human embryonic lung fibroblasts HLF-1 with various concentrations of DDW from 2 to 72 h. Cellular growth inhibition rates were determined using the 3-(4, 5-dimethyldiazol-2-yl)-2, 5-diphenyltetrazolium-bromide) (MTT) proliferation assay. A549 cells were treated with 50±5 ppm DDW, and the morphology and structure of cells were observed by scanning electron microscopy (SEM). We observed alterations in the cellular skeleton by transmission electron microscopy (TEM) and changes in cell cycle by flow cytometry. Our data showed that DDW significantly inhibited the proliferation of A549 cells at a specific time point, and cells demonstrated the characteristic morphological changes of apoptosis under SEM and TEM. The length of the S phase increased significantly in cells treated with 50 ppm DDW, whereas the G0 to G1 phase and G2 to M phase were decreased. We observed DDW-induced cellular apoptosis using terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and DNA fragment analyses. In addition, we established a tumor transplantion model by injecting H460 tumor cells into subcutaneous tissue of BALB/c mice treated with DDW for 60 days. We determined the tumor inhibition rate of treated and control groups and found that the tumor weight was significantly decreased and the tumor inhibition rate was approximately 30% in the DDW group. We conclude that DDW is a promising new anticancer agent with potential for future clinical application.

Adenovirus-mediated wild-type p53 gene transfer in combination with bronchial arterial infusion for treatment of advanced non-small-cell lung cancer, one year follow-up

OBJECTIVE

In the present study, we have examined the safety and efficacy of recombinant adenovirus encoding human p53 tumor suppressor gene (rAd-p53) injection in patients with advanced non-small-cell lung cancer (NSCLC) in the combination with the therapy of bronchial arterial infusion (BAI).

METHODS

A total of 58 patients with advanced NSCLC were enrolled in a non-randomized, two-armed clinical trial. Of which, 19 received a combination treatment of BAI and rAd-p53 (the combo group), while the remaining 39 were treated with only BAI (the control group). Patients were followed up for 12 months, with safety and local response evaluated by the National Cancer Institute's Common Toxicity Criteria and response evaluation criteria in solid tumor (RECIST), respectively. Time to progression (TTP) and survival rates were also analyzed by Kaplan-Meier method.

RESULTS

In the combo group, 19 patients received a total of 49 injections of rAd-p53 and 46 times of BAI, respectively, while 39 patients in the control group received a total of 113 times of BAI. The combination treatment was found to have less adverse events such as anorexia, nausea and emesis, pain, and leucopenia (P<0.05) but more arthralgia, fever, influenza-like symptom, and myalgia (P<0.05), compared with the control group. The overall response rates (complete response (CR)+partial response (PR)) were 47.3% and 38.4% for the combo group and the control group, respectively (P>0.05). Patients in the combo group had a longer TTP than those in the control group (a median 7.75 vs 5.5 months, P=0.018). However, the combination treatment did not lead to better survival, with survival rates at 3, 6, and 12 months in the combo group being 94.74%, 89.47%, and 52.63%, respectively, compared with 92.31%, 69.23%, and 38.83% in the control group (P=0.224).

CONCLUSION

Our results show that the combination of rAd-p53 and BAI was well tolerated in patients with NSCLC and may have improved the quality of life and delayed the disease progression. A further study to better determine the efficacy of this combination therapy is warranted.

Advanced malignant pleural or peritoneal effusion in patients treated with recombinant adenovirus p53 injection plus cisplatin

The aim of this study was to evaluate the efficacy of recombinant adenovirus p53 agent (rAd-p53) injection combined with cisplatin (CDDP) for the treatment of malignant pleural or peritoneal effusion. After puncture drainage, patients in the treatment group (n = 27) received intracavitary administration of rAd-p53 (2 x 10(12) virus particles) once a week for 4 weeks. At 48 h after each rAd-p53 injection, patients were given intracavitary administration of cisplatin 60 mg/m(2). This administration procedure continued once a week for 4 weeks. The control group (n = 21) received the same intracavitary therapy as the treatment group but without rAd-p53 therapy. Efficacy was evaluated by clinical observations, computed tomography, tumour markers, Karnofsky score and short-term follow-up. The total effective rates for the treatment group (63.0%) were significantly higher than for the control group (42.9%), suggesting that the treatment group benefited over the control group. In conclusion, rAd-p53 therapy is a safe and effective treatment for advanced malignant pleural or peritoneal effusion.

Apoptosis of murine melanoma cells induced by heavy-ion radiation combined with Tp53 gene transfer

PURPOSE

To investigate the effect of exogenous wild type p53 (Tp53) on murine melanoma B16 cell apoptosis induced by carbon-ion beam (C-beam) irradiation.

MATERIALS AND METHODS

The murine cell line B16, which has wild-type Tp53 gene status was studied, as well as B16 cells transfected with an adenoviral vector containing the wild-type Tp53 gene (B16/Tp53). Cells were irradiated with C-beam and assayed for cell survival (colony-forming assay), cellular morphology (acridine orange assay), the frequency of apoptotic cells (fluorescence microscopy) and protein expression (Western blot analysis).

RESULTS

The radiosensitivity of B16/Tp53 cells was significantly higher than that of B16 cells. In contrast with Tp53 transfer alone, the combination of C-beam with Tp53 transfer induced a higher proportion of apoptotic cells and micronuclei. After C-beam irradiation, there was no significant increased expression of the cyclin-dependent kinase inhibitor p21 and Tp53 in B16/Tp53 cells compared to B16 cells, but a decreased expression of murine double minute-2 (Mdm2) was observed.

CONCLUSION

The results of this study suggest the potential application of C-beam combined with Tp53 in the treatment of melanoma in human patients.

Gene therapy for lung cancer

Lung cancer patients suffer a 15% overall survival despite advances in chemotherapy, radiation therapy, and surgery due to the usual finding of advanced disease at diagnosis. Attempts to improve survival in advanced disease using various combinations of chemotherapy have demonstrated that no regimen is superior, suggesting a therapeutic plateau and the need for novel, more specific, and less toxic therapeutic strategies. Techniques have been developed that allow transfer of functional genes into mammalian cells, such as those that block activated tumor-promoting oncogenes and/or those that replace inactivated tumor-suppressing or apoptosis-promoting genes. This article will discuss the therapeutic implications of these molecular changes associated with bronchogenic carcinomas, and will then review the status of gene therapies for treatment of lung cancer.

Gene therapy for lung cancer

Lung cancer patients suffer a 15% overall survival despite advances in chemotherapy, radiation therapy, and surgery. This unacceptably low survival rate is due to the usual finding of advanced disease at diagnosis. However, multimodality strategies using conventional therapies only minimally improve survival rates even in early stages of lung cancer. Attempts to improve survival in advanced disease using various combinations of platinum-based chemotherapy have demonstrated that no regimen is superior, suggesting a therapeutic plateau and the need for novel, more specific, and less toxic therapeutic strategies. Over the past three decades, the genetic etiology of cancer has been gradually delineated, albeit not yet completely. Understanding the molecular events that occur during the multistep process of bronchogenic carcinogenesis may make these tasks more surmountable. During these same three decades, techniques have been developed which allow transfer of functional genes into mammalian cells. For example, blockade of activated tumor-promoting oncogenes or replacement of inactivated tumor-suppressing or apoptosis-promoting genes can be achieved by gene therapy. This article will discuss the therapeutic implications of these molecular changes associated with bronchogenic carcinomas and will then review the status of gene therapies for treatment of lung cancer.

Evaluation of the Spatial Diffusion of Methylene Blue Injected in vivo by Bronchoscopy into Non-Small Cell Lung Carcinoma

BACKGROUND

Due to smoking prevalence and the poor efficiency of current therapy, lung cancer is the leading cause of cancer death in developed countries, and its worldwide incidence is steadily increasing. Gene therapy by direct intratumoral injection of different types of gene constructs through a fiberscope has been suggested and evaluated in a few patients.

OBJECTIVE

It was the aim of this study to observe the actual volume of diffusion within a lung tumor using a color marker.

METHODS

Using bronchoscopy, just after anesthesia, methylene blue was injected into patient tumors. These patients subsequently underwent surgery for treatment of a non-small cell lung cancer.

RESULTS

We observed a diffusion of methylene blue in resected lung tumors with a mean infiltrated versus noninfiltrated tumor volume ratio of 29 +/- 15%. Interestingly, some large tumor areas were not stained. At the cellular level, a preferential diffusion of the dye was observed in the tumor stroma compartment versus the tumor cellular compartment, where basal cells were more frequently and strongly labeled than the other tumor cells.

CONCLUSIONS

Since a cancer is cured when most, if not all, cancer cells are killed, the preliminary evaluation of the spatial diffusion of any injected gene construct should be carried out as a first step in any cancer type.

Immunotherapy of lung cancer: an update

In Germany lung cancer is the leading cause of cancer-associated death in men. Surgery, chemotherapy and radiation may enhance survival of patients suffering from lung cancer but the enhancement is typically transient and mostly absent with advanced disease; eventually more than 90% of lung cancer patients will die of disease. New approaches to the treatment of lung cancer are urgently needed. Immunotherapy may represent one new approach with low toxicity and high specificity but implementation has been a challenge because of the poor antigenic characterization of these tumors and their ability to escape immune responses. Several different immunotherapeutic treatment strategies have been developed. This review examines the current state of development and recent advances with respect to non-specific immune stimulation, cellular immunotherapy (specific and non-specific), therapeutic cancer vaccines and gene therapy for lung cancer. The focus is primarily placed on immunotherapeutic cancer treatments that are already in clinical trial or well progressed in preclinical studies. Although there seems to be a promising future for immunotherapy in lung cancer, presently there is not standard immunotherapy available for clinical routine.

Gene therapy for lung cancer

Over the past three decades, the molecular biology of lung cancer has been progressively delineated. Concurrently, gene therapy techniques have been developed that allow targeting or replacement of dysfunctional genes in cancer cells, such as activated tumor-promoting oncogenes, inactivated tumor-suppressing, or apoptosis-promoting genes. This article will review the therapeutic implications of molecular changes associated with non-small cell lung cancer and the status of gene therapy.

Adenoviral-E2F-1 radiosensitizes p53wild-type and p53null human prostate cancer cells

PURPOSE

E2F-1 is a transcription factor that enhances the radiosensitivity of various cell lines by inducing apoptosis. However, there are conflicting data concerning whether this enhancement is mediated via p53 dependent pathways. Additionally, the role of E2F-1 in the response of human prostate cancer to radiation has not been well characterized. In this study, we investigated the effect of Adenoviral-E2F-1 (Ad-E2F-1) on the radiosensitivity of p53wild-type (LNCaP) and p53null (PC3) prostate cancer cell lines.

METHODS AND MATERIALS

LNCaP and PC3 cells were transduced with Ad-E2F-1, Adenoviral-Luciferase (Ad-Luc) control vector, or Adenoviral-p53 (Ad-p53). Expression of E2F-1 and p53 was examined by Western blot analysis. Annexin V and caspase 3 + 7 assays were performed to estimate the levels of apoptosis. Clonogenic survival assays were used to determine overall cell death. Statistical significance was determined by analysis of variance, using the Bonferroni method to correct for multiple comparisons.

RESULTS

Western blot analysis confirmed the efficacy of transductions with Ad-E2F-1 and Ad-p53. Ad-E2F-1 transduction significantly enhanced apoptosis and decreased clonogenic survival in both cell lines. These effects were compounded by the addition of RT. Although E2F-1-mediated radiosensitization was independent of p53 status, this effect was more pronounced in p53wild-type LNCaP cells. When PC3 cells were treated with Ad-p53 in combination with RT and Ad-E2F-1, there was at least an additive reduction in clonogenic survival.

CONCLUSIONS

Our results suggest that Ad-E2F-1 significantly enhances the response of p53wild-type and p53null prostate cancer cells to radiation therapy, although radiosensitization is more pronounced in the presence of p53. Ad-E2F-1 may be a useful adjunct to radiation therapy in the treatment of prostate cancer.

Adenovirus-mediated p53 gene therapy in osteosarcoma cell lines: sensitization to cisplatin and doxorubicin

The poor prognosis for patients with metastatic osteosarcoma (OS) indicates that new therapeutic options should be explored. Studies with adenoviral-mediated p53 gene transfer have been conducted in many cancer types including cervical, ovarian, prostatic and head and neck tumors. However, limited work has been carried out with pediatric cancers, including OS. Using three viral constructs containing cDNA for wild-type p53, mutant p53 (Cys135Ser) and lacZ, we studied the effect of adenoviral-mediated gene therapy in four OS cell lines: Saos-2 (p53-/-), HOS (R156P), KHOS/NP (R156P) and MNNG (R156P, F270L). We demonstrated that the virus efficiently enters the cells using the beta-galactosidase assay. Using the MTT assay, we have shown a dose-dependent decrease in cell viability 72 h post-treatment that occurs with Ad-wtp53 but not with Ad-mutp53. We have also shown that treatment with Ad-wtp53 significantly increases sensitivity of the cell lines to cisplatin and doxorubicin, chemotherapeutic agents commonly used in the treatment of OS. Our results indicate that restoration of wt p53 function in OS cells provides a basis for novel approaches to treatment of this disease.

[Gene therapy: current situation and expectations]

En esta revisión se describe la situación actual de la terapia génica en enfermedades hematológicas, inmunológicas y en cáncer. En todas ellas el objetivo principal de los diversos abordajes de la terapia génica es el transducir los genes terapéuticos en la mayor parte de las células diana. A nivel de enfermedades crónicas o inmunológicas se requiere, asimismo, una expresión estable de los genes terapéuticos y a nivel de las células tumorales la eficiencia o porcentaje de células transducidas condiciona el éxito de los tratamientos. Por consiguiente, los vectores son uno de los elementos básicos para optimizar los abordajes y protocolos de terapia génica dado que sabemos que con el empleo de liposomas menos del 10% de las células van a ser transducidas, que con el empleo de retrovirus sólo se van a infectar células en replicación y que con los adenovirus va a haber una respuesta inflamatoria importante y una transducción transitoria del gen terapéutico. Asimismo se discuten los últimos abordajes en terapia génica del cáncer con virus de replicación selectiva, genes suicidas, etc.

Recent Developments in Critical Genes in the Molecular Biology of Breast Cancer

The biology of breast cancer is complex, and the increasing knowledge of its molecular biology is having a great impact on the clinical management of this serious condition. This review looks at new findings on the role of various critical genes, including BRCA1, BRCA2, HER2 and p53, in the development of breast cancer and their clinical implications.

Adenovirus-mediated p53 gene therapy in pediatric soft-tissue sarcoma cell lines: sensitization to cisplatin and doxorubicin

Sarcomas, or tumors of connective tissue, represent roughly 20% of childhood cancers. Although the cure rate for sarcomas in general has significantly improved in the last 10 years, there continue to be subgroups that are difficult to treat. High-grade or metastatic soft-tissue sarcomas and rhabdomyosarcomas (RMS) of the extremities remain therapeutic challenges and their prognosis is often poor. The future of sarcoma therapy will likely include molecular approaches including gene/protein expression profiling and gene-based therapy. Most sarcomas harbor defects in the p53 or pRb pathways. The tumor suppressor p53 is central to regulation of cell growth and tumor suppression and restoring wild-type p53 function in pediatric sarcomas may be of therapeutic benefit. Studies with adenoviral-mediated p53 gene transfer have been conducted in many cancer types including cervical, ovarian, prostatic and head and neck tumors. Studies of this approach, however, remain limited in pediatric cancers, including sarcomas. Using three viral constructs containing cDNA for wild-type p53, mutant p53 (C135S) and lacZ, we studied the effect of adenoviral-mediated gene therapy in four pediatric sarcoma cell lines, RD and Rh4 (RMS), Rh1 (Ewing's sarcoma) and A204 (undifferentiated sarcoma). Using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay, we have shown a dose-dependent decrease in cell viability 72 h post-treatment that occurs with Ad-wtp53 but not with Ad-mutp53. Cells treated with Ad-wtp53 show upregulation of the p53 downstream targets, p21(CIP1/WAF1) and bax. Growth curves demonstrate suppression of cell growth over a period of 4 days and cells treated with Ad-wtp53 demonstrate a significant increase in sensitivity to the chemotherapeutic agents, cisplatin and doxorubicin. Our results indicate that restoration of wild-type p53 function in pediatric sarcoma cells could provide a basis for novel approaches to treatment of this disease.

Proteasome inhibition with PS-341 (bortezomib) in lung cancer therapy

PS-341 (bortezomib) represents a new class of therapeutics that targets the ubiquitin-proteasome pathway. It has broad-spectrum single-agent anticancer activity and can potentiate chemotherapy and radiation in preclinical models. Early phase clinical studies have shown tolerability and activity in multiple myeloma, lymphoma, prostate cancer, and lung cancers. By its mechanism of inhibiting protein degradation, PS-341 targets a wide range of pathways relevant to tumor progression and therapy resistance and can directly modulate expression of cyclins, p27(Kip1), p53, nuclear factor-kappaB, Bcl-2, and Bax. PS-341 is currently in phase I/II clinical development in both non-small cell lung cancer and small cell lung cancer. This article will review the preclinical and clinical experience with PS-341 as it relates to lung cancer.

A comprehensive assessment of p53-responsive genes following adenoviral-p53 gene transfer in Bcl-2-expressing prostate cancer cells

The p53 protein can induce cell cycle arrest or apoptosis following activation in response to DNA damage. The function of p53 is largely mediated by regulating the expression of downstream target genes. Adenoviral-p53 gene transfer (Ad-p53) is currently being evaluated in clinical trials as a therapeutic intervention. Tumor response is likely to be influenced by context-dependent variables, such as expression of bcl-2. Bcl-2 is upregulated in a variety of neoplasms, and can inhibit p53-dependent apoptosis. It was therefore of interest to use a global genomic strategy to assess gene expression following Ad-p53 gene transfer and to determine if the expression of specific Ad-p53-responsive genes could be modulated in the context of bcl-2 gene deregulation. cDNA arrays were used to identify p53-responsive genes following Ad-p53 gene transfer in control and bcl-2-overexpressing PC3 prostate cancer cells. A total of 40 transcripts were significantly upregulated by Ad-p53 in both control and bcl-2-transfectant PC3 cells. Conversely, 19 transcripts were significantly repressed in both cell lines. These Ad-p53-responsive transcripts included previously identified p53 targets, known genes representing candidate p53 targets, and transcripts identified as expressed sequence tags. A subset of 15 transcripts was differentially modulated by Ad-p53 in the context of bcl-2. Some of these genes were also differentially modulated in LNCaP (wt p53) cells following DNA damage. These results document a number of potential p53 targets and mediators of therapeutically relevant genotoxic stress. The findings further suggest that bcl-2 may inhibit cell death at multiple points downstream of p53 activation.

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Lung cancer vaccines and gene therapy

A number of cancer vaccine and gene therapy approaches are being evaluated in patients with lung cancer. Cancer vaccine strategies include GM-CSF gene-modified cancer cells, liposomal MUC1 peptide, anti-idiotype antibody targeting GD3, Mage-3 peptide, and mutant p53 pulsed dendritic cells among others. Preliminary human trials have demonstrated immune responses as well as tumor regression in late stage disease. The largest human gene therapy experience in lung cancer is with intratumoral gene replacement therapy, predominantly with p53, but such approaches are limited to locoregional disease control. Earlier stage gene therapy programs targeting the immune system or tumor vasculature hold promise as systemic therapies for treatment of advanced, disseminated disease.

Breakthroughs in cancer gene therapy

OBJECTIVES

To give oncology nurses an overview on the vectors and selected approaches used in the current clinical trials involving gene transfer to cancer patients.

DATA SOURCES

Peer-reviewed scientific papers, review articles, and book chapters.

CONCLUSION

Significant progress has been made in the field of cancer gene therapy. Different phases of clinical protocols derived from new generations of vectors and novel approaches are being tested for use in the treatment of patients with cancer.

IMPLICATIONS FOR NURSING PRACTICE

Oncology nurses need to be familiar with current advances in the field of cancer gene therapy to expand their role as health care professional, patient educator, and advocate for the treatment of patients with cancer.