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PubMed1996

Mutations and polymorphisms in the familial early-onset breast cancer (BRCA1) gene. Breast Cancer Information Core.

Mutations in the familial early-onset breast cancer gene (BRCA1) account for approximately 2-5% of all breast cancer cases (Easton et al., 1993). Since the isolation of the BRCA1 gene in 1994, many mutations have been identified. We report here a total of 254 BRCA1 mutations, 132 (52%) of which are unique. These represent mutations entered into a database established by the Breast Cancer Information Core (BIC), which have appeared in the literature or have been submitted by BIC members and other contributors prior to publication. A total of 221 (87%) of all mutations or 107 (81%) of the unique mutations are small deletions, insertions, nonsense point mutations, splice variants, and regulatory mutations that result in truncation or absence of the BRCA1 protein. A total of 11 disease-associated missense mutations (5 unique), and 21 variants (19 unique) as yet unclassified as either missense mutations or polymorphisms have been detected. Thirty-five independent benign polymorphisms are also described. The most common mutations are 185delAG and 5382insC, which account for 30 (11.7%) and 26 (10.1%), respectively, of all mutations shown. The biological and clinical relevance of these BRCA1 mutations is discussed.

Age of Onset↗
PubMed2005

Inhibition of NF-kappaB enhances the cytotoxicity of virus-directed enzyme prodrug therapy and oncolytic adenovirus cancer gene therapy.

Virus-directed enzyme prodrug therapy utilizing the bacterial enzyme nitroreductase delivered by a replication-defective adenovirus vector to activate the prodrug CB1954 is a promising strategy currently undergoing clinical trials in patients with a range of cancers. Similarly, selectively replicating oncolytic adenoviruses are entering clinical trials. An understanding of interactions between vector and target cell are critical to the development of these strategies. We demonstrate that adenovirus vectors activate cellular pathways that promote cell survival in an NF-kappaB-dependent manner, and consequently have a negative effect on the efficacy of cell killing induced by cancer gene therapy strategies. This provides a potential therapeutic target to enhance the cytotoxicity of these approaches.

Adenoviridae↗
PubMed1999

The tylosis esophageal cancer (TOC) locus: more than just a familial cancer gene.

Tylosis (focal non-epidermolytic palmoplantar keratoderma; NEPPK) is associated with esophageal cancer in three families, two of which contain six or seven generations. The causative locus, the tylosis esophageal cancer (TOC) gene, has been localized to a small region on chromosome 17q25. Recent loss of heterozygosity (LOH) studies have indicated a role for the TOC gene in sporadic squamous cell esophageal cancer and Barrett's adenocarcinoma. We have now integrated genetic and physical mapping data from the TOC region, based on microsatellite markers and radiation hybrid, yeast (YAC), bacterial (BAC) and P1 artificial chromosomal (PAC) clones, and formed a partial minimal contig of one non-chimeric YAC (330 kb) and one PAC. Twenty-three candidate genes, including envoplakin (EVPL), were mapped against this contig, but only one was shown to be located within the minimal region. This physical map will allow further characterization of the region and identification of a gene implicated in both familial and sporadic squamous cell esophageal carcinoma and Barrett's adenocarcinoma.

Barrett Esophagus↗
PubMed1998

Cancer gene therapy using a replication-competent herpes simplex virus type 1 vector.

OBJECTIVE: The authors investigate the efficacy of hrR3, a viral vector derived from herpes simplex virus type 1 (HSV 1), in destroying colon carcinoma cells in vitro and in vivo. The effect of adding the prodrug ganciclovir in combination with hrR3 infection also is assessed. SUMMARY BACKGROUND DATA: Most cancer gene therapy strategies use viral vectors that are incapable of replication. The HSV 1 vector hrR3 is capable of replication, and its replication is cytotoxic to cells. hrR3 also possesses the HSV-thymidine kinase gene, which converts ganciclovir into a toxic metabolite. Thus, the addition of ganciclovir to hrR3-infected cells may enhance the ability of hrR3 to destroy tumor cells. To increase specificity for tumor cells, hrR3 has a mutated ribonucleotide reductase gene and replicates selectively in cells with high levels of endogenous rbonucleotide reductase. Actively dividing cells such as tumor cells have high levels of endogenous ribonucleotide reductase for synthesis of DNA precursors. The authors are interested in the use of HSV 1 vectors to treat liver metastases from colorectal cancer. METHODS: Ribonucleotide reductase expression in several colon carcinoma cell lines and in primary cultures of human hepatocytes was determined by Western blot analysis. hrR3-mediated cytotoxicity in the colon carcinoma cell lines was determined using an in vitro assay. The human colon carcinoma cell line HT29 was injected into the flanks of nude mice followed by intratumoral injection of hrR3. Tumor growth rate was assessed with and without the addition of intraperitoneal ganciclovir. RESULTS: Ribonucleotide reductase levels in colon carcinoma cell lines are much higher than in primary cultures of human hepatocytes. hrR3 efficiently destroys colon carcinoma cell lines in vitro. A single intratumoral injection of hrR3 into HT29 flank tumors significantly reduces tumor growth rate, and the administration of ganciclovir has no additive effect. CONCLUSIONS: The inherent cytotoxicity of hrR3 replication effectively destroys colon carcinoma cells in vitro and in vivo. This cytotoxicity is not enhanced in vivo by the addition of ganciclovir. In the future, more efficacious and selective HSV 1 vectors may be useful in the treatment of cancer.

Animals↗
PubMedDate not supplied

Recombinant vaccinia expressing interleukin-2 for cancer gene therapy.

Use of a recombinant vaccinia virus expressing human interleukin-2 (IL-2) was evaluated for preparation of tumor vaccines. A/J mice were immunized against neuroblastoma (C1300) cells using a preparation of C1300 cells infected/transfected with the recombinant virus, vCF13, expressing IL-2. A second recombinant vaccinia, vSC8, expressing Escherichia coli beta-galactosidase, was used as a control. After three weekly immunizations with virus-transfected cells, the mice were challenged with 1 x 10(6) unmodified C1300 cells and tumor development was monitored. Tumor development in the mice was inhibited by immunization with vCF13-transfected cells, compared to those vaccinated with vSC8-transfected cells (P < .008). A group of mice (7/15) immunized with vCF13-transfected cells followed by tumor challenge survived more than 60 days, at which time all mice immunized with the control vaccine were dead (p < .006). Five of the mice treated with the vCF13 vaccine were alive for more than 75 days (P < .05), after which they were rechallenged with another dose of 1 x 10(6) unmodified tumor cells. Tumor development was not apparent in these mice for more than 45 days following the second challenge, suggesting that these mice were completely protected by this immunization. These results demonstrate that recombinant vaccinia virus expressing IL-2 may be useful for cancer gene therapy.

Animals↗
PubMed2001

Transcriptional targeting for ovarian cancer gene therapy.

Ovarian carcinoma is a leading cause of cancer death in women. Though advances in conventional therapies have been achieved, long-term survival rates for most patients diagnosed with ovarian cancer are still low. Therefore, novel molecular therapeutic strategies such as gene therapy are being intensively pursued. Such approaches are based on the enormous progress that has been achieved in the elucidation of the molecular foundations of ovarian cancer. In this regard transcriptional control elements (promoters) of genes frequently upregulated or specifically expressed in tumors can be applied in a heterologous context to drive expression of therapeutic genes in targeted gene therapy strategies. This review discusses transcriptional targeting strategies in ovarian cancer gene therapy and gives an overview of tumor-specific promoters (TSPs) that have been applied for this purpose.

Animals↗
PubMed2001

Cancer gene therapy using a survivin mutant adenovirus.

We have constructed a replication-deficient adenovirus encoding a nonphosphorylatable Thr(34)-->Ala mutant of the apoptosis inhibitor survivin (pAd-T34A) to target tumor cell viability in vitro and in vivo. Infection with pAd-T34A caused spontaneous apoptosis in cell lines of breast, cervical, prostate, lung, and colorectal cancer. In contrast, pAd-T34A did not affect cell viability of proliferating normal human cells, including fibroblasts, endothelium, or smooth muscle cells. Infection of tumor cells with pAd-T34A resulted in cytochrome c release from mitochondria, cleavage of approximately 46-kDa upstream caspase-9, processing of caspase-3 to the active subunits of approximately 17 and 19 kDa, and increased caspase-3 catalytic activity. When compared with chemotherapeutic regimens, pAd-T34A was as effective as taxol and considerably more effective than adriamycin in induction of tumor cell apoptosis and enhanced taxol-induced cell death. In three xenograft breast cancer models in immunodeficient mice, pAd-T34A suppressed de novo tumor formation, inhibited by approximately 40% the growth of established tumors, and reduced intraperitoneal tumor dissemination. Tumors injected with pAd-T34A exhibited loss of proliferating cells and massive apoptosis by in situ internucleosomal DNA fragmentation. These data suggest that adenoviral targeting of the survivin pathway may provide a novel approach for selective cancer gene therapy.

Adenoviruses, Human↗
PubMed1999

Progress in cancer gene therapy.

Many technical difficulties have to be overcome before effective gene therapy can be achieved. Strategies for gene therapy include 'suicide' gene therapy, transfer of a tumor suppressor gene, inhibition of activated oncogenes by antisense mechanisms, and cytokine gene transfer and tumor cell vaccination. Gene therapy will have a major impact on the healthcare of our population only when vectors are developed that can safely and efficiently be injected directly into patients as drugs. One of the most promising areas of vector development is that of non-viral vectors, which consist of liposomes, molecular conjugates, and naked DNA delivered by mechanical methods. Future research should be focused on modifying viral vectors to reduce toxicity and immunogenicity, increasing the transduction efficiency of non-viral vectors, enhancing vector targeting and specificity, regulating gene expression, and identifying synergies between gene-based agents and other cancer therapeutics. The evaluation of gene therapy combinations is another important area for future research. The identification of tumor rejection antigens from a variety of cancers and the immune response that is defective in cancer patients are important topics for future studies. A universal gene delivery system has yet to be identified, but the further optimization of each of these vectors should result in each having a unique application. Gene therapy has still a long way to go and requires the efforts of investigators in the basic and clinical sciences. Despite substantial progress, a number of key technical issues need to be resolved before gene therapy can be effectively applied in the clinic.

Clinical Trials as Topic↗
PubMedDate not supplied

In vivo cancer gene therapy with a recombinant interleukin-2 adenovirus vector.

Recombinant adenovirus (AdV) vectors are highly efficient at in vitro and in vivo gene delivery. In vivo therapy of established murine fibrosarcoma and mammary carcinomas was attempted with intratumoral injections of a recombinant AdV vector in which the human interleukin-2 (IL-2) gene was driven by the cytomegalovirus enhancer/promoter. Delayed growth and rejection of some tumors could be achieved with a cumulative virus dose of 2 to 6 x 10(9) plaque-forming units in two or three divided doses. Lower viral doses were ineffective, and higher doses resulted in animal death due to IL-2 toxicity. Using AdV vectors with the marker genes beta-galactosidase and luciferase, it is clear that even small volume (10 to 20 microL) intratumoral injections result in substantial systemic delivery of a portion of the virus dose. These findings define the potential and limitations of in vivo AdV-based cancer gene therapy and provide support for strategies to develop tumor-specific vectors.

Adenoviridae↗
PubMed1994

Cytogenetic approaches to human cancer genes.

Chromosome studies of human tumors have provided important clues to the location of relevant genes and the mechanisms by which their growth regulatory functions have been altered. In the last decade, molecular dissection of chromosome translocations in hematopoietic tumors and chromosomal deletions in solid tumors have been particularly helpful in demonstrating the involvement of a few previously known oncogenes and a wide variety of previously unknown "cancer genes," which often differ from one type of tumor to another, and normally may either stimulate or inhibit cell growth. These studies have also helped to clarify the importance of multiple genetic lesions in the development of most tumors, and the recently acquired information is already being used in clinical diagnosis and management. In addition, new specific treatments will ultimately result from these findings, but the work to date also clearly indicates that no single, simple answer to human cancer will be forthcoming.

Chromosome Aberrations↗
PubMed2001

Cancer gene and oncolytic virus therapy.

By far, cancer accounts for the majority of gene therapy trials that are being carried out worldwide. Seventy percent of the gene therapy protocols that have been reviewed by the National Institutes of Health Recombinant DNA Advisory Committee (NIH RAC) are for the treatment of cancer. Of these, two thirds involve immunotherapy, with transfer of genes for cytokines, immune accessory molecules, or tumor antigens into a variety of cellular targets. Other clinical protocols include chemoprotection, prodrug activation, or tumor-suppressor gene replacement. Either local or distal bystander effects may mediate antitumor effects. These bystander mechanisms may help to overcome poor transduction efficiencies by currently available vectors. Replicating oncolytic viruses entering the clinic include herpes virus, Newcastle disease virus, reovirus, and others. These viruses have been shown to replicate selectively in cancer cells, albeit by different mechanisms. Reovirus, for example, requires the presence of an activated Ras signaling pathway in order to replicate and destroy cells. Tumor selectivity can be achieved by placing an essential viral gene under the control of a tumor-specific promoter. The tumoricidal effects of replicating viruses may be enhanced by genetic modification-for example, by the insertion of a cytokine gene to elicit antitumor immunity. Clearly, much work needs to be done both in the laboratory and in the clinic in order to exploit the full potential of these novel gene and viral therapies.

Animals↗
PubMed2005

Applications of molecular imaging in cancer gene therapy.

Gene-based therapy is a promising and flexible therapeutic approach to manage diverse types of cancer. The lack of convincing therapeutic success of current gene therapy protocols in part, can be attributed to the inability to monitor gene expression at the targeted site in the living subject. Linking molecular imaging to gene therapy will enable real-time assessment of the therapeutic process and the refinement of treatment protocols. This review will cover two common imaging modalities, positron emission tomography (PET) and bioluminescence imaging (BLI), used in pre-clinical and clinical gene therapy applications. Strategies to develop more specific and robust cancer gene therapy and imaging approaches will be discussed. Coupling PET to gene therapy of cancer has already been implemented in several clinical studies. This approach would help to improve the efficacy and safety of future gene therapy clinical trials.

Gene Expression↗
PubMedDate not supplied

Genetic alterations in K-ras and p53 cancer genes in lung neoplasms from Swiss (CD-1) male mice exposed transplacentally to AZT.

A transplacental carcinogenicity study was conducted by exposing pregnant Swiss (CD-1) mice to 0, 50, 100, 200, or 300 mg of 3'-azido-3'-deoxythymidine (AZT)/kg bw/day, through a 18 to 19-day gestation [National Toxicology Program, NIH Pub. No. 04-4458, 2004]. The incidences of alveolar/bronchiolar adenomas and carcinomas, in the 200 and 300 mg/kg male treatment groups, were significantly greater than that of the controls. In the present study, we evaluated the benign and malignant lung neoplasms from this bioassay for point mutations, in the K-ras and p53 cancer genes that are often mutated in human lung tumors. K-ras and p53 mutations were detected by cycle sequencing of polymerase chain reaction-amplified DNA, isolated from formalin-fixed, paraffin-embedded neoplasms. K-ras mutations were detected in 25 of 38 (66%) of the AZT-induced lung tumors, and the predominant mutations were codon 12 G-->T transversions. p53 mutations were detected in 32 of 38 (84%) of the AZT-induced lung tumors, with the predominant mutations being exon 8, codon 285 A-->T transversions, and exon 6, codon 198 T-->A transversions. No K-ras or p53 mutations were detected in five tumors, examined from control mice. The patterns of mutations identified in the lung tumors suggest that incorporation of AZT or its metabolites into DNA, oxidative stress, and genomic instability may be the contributing factors to the mutation profile and development of lung cancer in these mice.

Animals↗
PubMed2005

Enhanced transgene expression in urothelial cancer gene therapy with histone deacetylase inhibitor.

PURPOSE: Efficient adenoviral infection requires the presence of the coxsackievirus and adenovirus receptor (CAR). We determined whether the histone deacetylase inhibitor FR901228 (Fujisawa Pharmaceutical Co., Ltd., Osaka, Japan) increases the efficiency of adenoviral gene therapy in bladder cancer in vivo and in vitro. MATERIALS AND METHODS: Cytotoxicity studies were performed to determine a minimally cytotoxic FR901228 concentration for bladder cancer cells. The level of CAR expression was determined by fluorescence activated cell scanning and/or reverse transcriptase-polymerase chain reaction analysis in FR901228 treated bladder cell lines. The in vivo effect on adenoviral gene expression was investigated in athymic mice. RESULTS: The concentration of FR901228 showing no or minimal cytotoxicity that was selected for these studies was 0.5 ng/ml for bladder cancer cells. Treatment of cancer cells with 0.5 ng/ml histone deacetylase inhibitor increased CAR RNA levels and acetylated histone H3. This increase was associated with a 5 to 10-fold increase in adenoviral infection, as evidenced by increased transgene expression from a beta-galactosidase containing adenoviral vector. Intravenous administration of FR901228 enhanced CAR expression in athymic mice. The combination of p53 adenovirus and histone deacetylase inhibitor resulted in significant tumor inhibition in vitro and in vivo. CONCLUSIONS: Nontoxic doses of the histone deacetylase inhibitor FR901228 increased CAR RNA levels and resulted in the marked enhancement of transgene expression after adenoviral infections. FR901228 pretreatment may increase the sensitivity of tumor cells to adenoviral gene therapy vectors.

Adenoviridae↗
PubMed2005

HIV-1 TAT protein transduction domain mediates enhancement of enzyme prodrug cancer gene therapy in vitro: a study with TAT-TK-GFP triple fusion construct.

Protein transduction domain (PTD) from HIV-1 TAT protein has been reported to translocate across the mammalian cell membrane, also as a part of fusion proteins. However, the true nature of TAT-mediated intercellular spreading is still under debate because it has been claimed to be a fixation artifact. To study the spreading of TAT fusion proteins and their potency to enhance thymidine kinase/ ganciclovir (HSV-TK/GCV) cancer gene therapy, we constructed a novel triple fusion protein containing TAT PTD, HSV-TK and green fluorescent protein (TAT-TK-GFP). This fusion protein has three functional domains in the same polypeptide, allowing reliable determination of the relationship between transduction rate and cell killing efficiency. TAT-TK-GFP was cloned into a lentivirus vector and used for analyses of TAT-mediated protein translocation and enhancement of HSV-TK/GCV cytotoxicity. The triple fusion protein was expressed correctly in vitro, but cell-to-cell translocation was not observed in rat glioma cells (BT4C). However, TAT-TK-GFP made BT4C and SKOV3.ip1 (human ovarian carcinoma) cells significantly more sensitive to ganciclovir than TK-GFP, whereas the effect in PC-3 human prostate carcinoma cells was more subtle. It was also observed that growth in lower serum concentration (2.5-5%) abolished the enhancement in BT4C cells, suggesting that high proliferation rate is one of the factors that contribute to TAT PTD-mediated enhancement of cytotoxicity. In summary, our results indicate that TAT PTD fusion proteins do not translocate intercellularly at detectable levels, but enhancement of the HSV-TK/GCV cytotoxicity can be detected in rat and human tumor cell lines in vitro.

Animals↗