Targeting gene therapy vectors to CNS malignancies

Multidrug resistance to anti-cancer drugs is a major medical problem. Resistance is manifested largely by the product of the human MDR1 gene, P-glycoprotein, an ABC transporter that is an integral membrane protein of 1280 amino acids arranged into two homologous halves, each comprising 6 putative transmembrane alpha-helices and an ATP binding domain. Despite the plethora of data from site-directed, scanning and domain replacement mutagenesis, epitope mapping and photoaffinity labeling, a clear structural model for P-glycoprotein remains largely elusive. In this report, we propose a new model for P-glycoprotein that is supported by the vast body of previous data. The model comprises 2 membrane-embedded 16-strand beta-barrels, attached by short loops to two 6-helix bundles beneath each barrel. Each ATP binding domain contributes 2 beta-strands and 1 alpha-helix to the structure. This model, together with an analysis of the amino acid sequence alignment of P-glycoprotein isoforms, is used to delineate drug binding and translocation sites. We show that the locations of these sites are consistent with mutational, kinetic and labeling data.     

Prophylactic gene therapy for cancer

BACKGROUND: Epithelial ovarian tumors of borderline malignancy are different from benign tumors and malignant neoplasms. They exist with relatively benign clinical course, younger age and better prognosis as compared with invasive malignant carcinomas. Most of them are discovered at early stage, for example, stage Ia. This retrospective review evaluates the clinical features, treatments and prognosis of 48 patients with borderline malignancy of ovarian tumors. METHODS: Forty-eight patients with ovarian tumors of borderline malignancy, aged from 14 to 69 years (mean: 39.2 years; median: 36 years), were retrospectively studied. The histopathologic diagnosis was based on the morphologic criteria published by Tazelaar et al. in 1985. All cases, including 16 cases diagnosed before 1985, were pathologically reviewed. All information of clinical stage, surgical intervention and prognosis was achieved by reviewing hospital record or contacting patients by telephone. Two patients were lost to follow up. One patient died of sepsis resulting from another operation for another gynecological cancer. Totally forty-five patients were included for evaluation. RESULTS: Thirty-nine of the 48 patients (81.3%) were at stage Ia, 6 cases (12.5%) were at stage Ib, 2 cases (4.1%) were at stage Ic, and the remaining one patient (2.1%) was at state IIIc. Thirty-four patients (71%) were with mucinous cystadenoma of borderline malignancy, 11 cases (23%) were of serous type, and 3 patients (6%) were of mixed serous and mucinous type. Twenty-two patients underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy (TAH and BSO), but one of them remained partial ovary due to young age (27 y/o). Twelve patients were treated with unilateral oophorectomy or unilateral salpingo-oophorectomy (USO). Twelve patients underwent USO and wedge resection of contralateral ovary. One case underwent debulking surgery. One patient underwent enucleation of ovarian tumor and biopsy of contralateral ovary. Eighteen patients were treated with chemotherapy after operation. One patient developed recurrence 4 months after the primary operation. Excluding two cases lost to follow up and one case with surgical mortality for another gynecological cancer, forty-five patients were alive and were followed from 9 months to 165 months. (median: 48 months; mean: 46 months) CONCLUSIONS: Most of the patients were at the early stage of disease when first diagnosed, 81.3% were at stage Ia and only one case was at stage IIIc. Sixty-three percent of our patients underwent surgical treatment alone while the rest of them (37%) had post-operative chemotherapy with either alkeran or PAC. The use of adjuvant chemotherapy seemed unwarranted as there was no difference in survival between those with and without it. (P > 0.05) The low recurrent rate of 2% in our patients again confirmed the 9 P relative benign clinical course of this disease.     

Targeting strategy for gene delivery to carcinoembryonic antigen-producing cancer cells by retrovirus displaying a single-chain variable fragment antibody

Cancer-specific antigens are promising targets for the specific delivery of certain drugs or genes to cancer cells in cancer therapy. Carcinoembryonic antigen (CEA) is one of the cancer-associated antigens predominantly detected in the gastrointestinal cancer of the colon and stomach. Targeting strategies for CEA-producing cancer cells have been thoroughly developed mainly by the production of monoclonal antibodies to CEA and further single-chain variable fragment (scFv) antibodies. Here, we have generated Moloney murine leukemia virus-derived retroviral vectors co-displaying an anti-CEA scFv-envelope chimeric protein and an unmodified envelope protein to deliver a gene for herpes simplex virus thymidine kinase (HSV-tk) or Escherichia coli beta-galactosidase. The harvested viruses successfully incorporated the chimeric envelope protein as well as the unmodified envelope into the viral particles, and specifically bound to and infected human CEA-producing cancer cells via recognition of CEA, depending on the CEA-producing phenotype of the target cells. These results may have significant implications for the use of scFv directed against tumor-specific antigens for targeting specific antigen-producing cancer cells, a potential step toward in vivo cancer therapy.     

组蛋白甲基化:肿瘤治疗的新靶标

暴露在核小体表面的N-末端尾部可发生共价修饰,这些共价修饰可以影响组蛋白和DNA结合的紧密程度,从而影响DNA的表达,被称之为组蛋白密码.近来大量的研究表明,组蛋白末端的赖氨酸和精氨酸残基的异常甲基化与肿瘤的发生、发展、预后有着密切的关系.应用组蛋白甲基转移酶/去甲基转移酶抑制剂调控组蛋白的甲基化水平,能够抑制肿瘤细胞的生长并诱导凋亡.     

Thyroid cancer: a review

Thyroid cancer is a rare and complex disease. The thyroid contains various cell types from which distinct diseases arise. These malignancies range from indolent to extremely aggressive. Diagnosis includes attention to risk factors, family history, and subjective reports. The most valuable tool for diagnosis is the fine-needle aspiration. Primary treatment is surgery with postoperative hormone therapy. Radiation and chemotherapy serve palliative and adjuvant roles in advanced, recurrent, or metastatic disease. Nurses make a significant contribution to patient understanding and successful treatment outcome.     

Validation therapy: a review of its contribution to dementia care

There has been a great deal of interest in validation therapy (VT), an interactive technique and group therapy for people who are disoriented. This article reviews the strengths and development of VT and acknowledges Naomi Feil's contribution to the care of those with dementia. Techniques for communicating with people who are dysphasic are described, as are therapeutic interventions which address the devastating effects of memory loss on the sufferers' sense of self and identity.     

Internal radiation therapy for patients with primary or metastatic hepatic cancer: a review

BACKGROUND: The limited efficacy of current approaches to the treatment of patients with hepatic cancer, including external beam radiation therapy and cytotoxic chemotherapy, has reawakened interest in the use of internal radiation therapy. METHODS: The authors reviewed series of patients with liver metastases or hepatocellular carcinoma (HCC) treated with 1) interstitial irradiation and direct intratumoral injection of 90Y microspheres, 2) intraarterial infusion of (131)I-Lipiodol, 3) intraarterial infusion of 90Y microspheres, or 4) parenteral administration of radiolabeled monoclonal antibodies. RESULTS: High dose rate interstitial irradiation with afterloading of (192)Ir resulted in local control of hepatic metastases for a median of 8 months and complete tumor eradication in 2 patients. Direct intratumoral injection of 90Y microspheres reduced the size of 90.6% of tumors and completely destroyed them in 8 patients. Treatment with arterial (131)I-Lipiodol resulted in a 17-92% response rate as well as a case of complete remission of unresectable HCC. It was found to be most effective against small tumors. No response was observed with liver metastases from colorectal carcinoma. Partial response was commonly achieved when patients with unresectable liver metastases or HCC were treated with intraarterial 9OY microspheres. Among four patients whose HCC became resectable following treatment with 90Y microspheres, two cases of complete remission were documented. In a prospective randomized trial, (131)I-antiferritin combined with chemotherapy was no more effective than chemotherapy alone. CONCLUSIONS: The different approaches to internal radiation therapy that are reviewed in this article represent several ways in which radiation can be selectively targeted to hepatic tumors without undue radiation to the nontumorous liver. However, the efficacy of each of these therapies still needs to be evaluated in randomized controlled trials.     

Nonstandard fractionation schedules in radiation therapy of head and neck cancer: a review

The authors present an updated review of the clinical trials on hyperfractionated and accelerated fractionation schedules in radiotherapy of head and neck cancer. The available results in terms of survival and local control, and acute and late toxicity data are summarized in order to show the current status of this research field. The new breed of fractionation schedules that are on study, designed on the ground of new rationales, are presented as well. Finally, an introductory overview of combination therapy including non standard fractionation radiotherapy associated with chemotherapy is reported.     

Targeting endothelium for gene therapy via receptors up-regulated during angiogenesis and inflammation

Endothelial cells are an attractive target for gene therapy because they are intimately involved in disease processes associated with inflammation and angiogenesis and because endothelial cells are readily accessible to gene therapy vectors via the circulation. Furthermore, specific receptors are up-regulated during angiogenesis or during inflammation. Therefore it should be possible to target the specific populations of endothelial cells involved in each of these disease processes. We have utilized two bispecific antibodies to target entry of an adenovirus vector into endothelial cells expressing a receptor up-regulated during angiogenesis (alpha v integrins) and a receptor up-regulated during inflammation (E-selectin). Both bispecific antibodies contain the anti-FLAG M2 mAb, which binds to a FLAG epitope genetically incorporated into the penton base protein of the vector, AdFLAG. The anti-alpha v-integrin x anti-FLAG bsAb was able to direct binding and entry of AdFLAG into endothelial cells via alpha v integrins. Likewise, the anti-E-selectin x anti-FLAG bsAb was able to direct binding and entry of AdFLAG into tumor-necrosis-factor(TNF)-activated endothelial cells via E-selectin. Endothelial cells not activated with TNF were not efficiently transduced by the AdFLAG/E-selectin bsAb complex. These results demonstrate that bispecific antibodies can be successfully used to target adenovirus to endothelially expressed receptors that are up-regulated during angiogenesis or inflammation.     

Noninfectious gene transfer and expression systems for cancer gene therapy

Gene therapy provides a significant opportunity to devise novel strategies for the control or cure of cancer. Success of this modality will ultimately depend on the ability to express a therapeutic gene of interest at high levels, and specific gene delivery to targeted tumor cells will minimize toxicities. Although current gene therapy trials typically use viral-based, infectious vectors to express suitable target genes in human cancer cells, these vectors have significant limitations in their expression characteristics, lack of specificity in targeting tumor cells for gene transfer, and safety concerns regarding induction of secondary malignancies and recombination to form replication-competent virus. These limitations have refocused efforts to develop noninfectious gene transfer technologies for in vivo gene delivery of plasmid-based expression vectors. This article reviews recent developments in non-infectious gene transfer techniques, including liposome and receptor-mediated methods, which can efficiently deliver plasmid vectors into tumor cells in vivo. Additionally, strategies are reviewed for efficiently expressing target genes in tumor cells, including use of tissue-specific promoters, inducible promoters, and replication-control sequences to regulate extrachromosomal amplification of vector DNA in human tumor cells. Optimal coupling of these noninfectious gene transfer and expression technologies have the potential to yield safe and effective gene therapies for patients with cancer.     

Breast cancer associated mucin: a review

Rabbit polyclonal antibody against mouse EHS laminin was used to investigate the distribution and composition of laminin in the rat first molar tooth germ. Immunohistochemical analysis showed that laminin is expressed in the inner and outer epithelia of the enamel organ and in small blood vessels in the dental papilla and strellate reticulum. Immunoblots revealed that tooth germ laminin differs from EHS laminin. Tooth germ laminin contains beta chains, while the alpha 1 chain is substituted by a 300-kDa chain. Two-dimensional electrophoresis analysis of tooth germ extract showed that beta chains appeared as four spots with approximate pI values of 6.6, 7.5, 7.8 and 8.5. These results indicate that more than-one type of laminin isoform is present in the first molar tooth germ. Additionally, we have shown that despite the early degradation of tooth germ basement membrane, the laminin molecule is still intact at the time of birth.