PubMed Health⌕ Search

Biomedical subjects

X W Tong

Publications and source records attributed to X W Tong.

At least 19 recordsLinked to original sources
PubMed2001

Adenovirus-mediated thymidine kinase gene therapy in combination with topotecan for patients with recurrent ovarian cancer: 2.5-year follow-up.

OBJECTIVE: Patients with recurrent ovarian cancer were treated intraperitoneally (ip) with a replication-deficient recombinant adenovirus (ADV) containing the herpes simplex virus thymidine kinase gene. Vector delivery was followed by intravenous administration of an antiherpetic prodrug and a topoisomerase I inhibitor. METHODS: Ten patients with stage IIIc epithelial ovarian cancer underwent secondary debulking to < or =0.5 cm residual tumor. Patients with normal ip flow received delivery of ip ADV. Two patients each were treated on dose level 1 (2 x 10(10) vector particles), dose level 2 (2 x 10(11)), and dose level 3 (2 x 10(12)); four patients were on dose level 4 (2 x 10(13)). Acyclovir and topotecan were started 24 h after vector delivery. Five patients underwent second-look surgery about 4 weeks after application of gene therapy (GT). RESULTS: At the time of the second-look surgery, two out of five patients were free of tumor. Four weeks after GT none of the peritoneal biopsies showed residual vector DNA. Patients pretreated with an average of three different chemotherapeutic drugs and two different chemotherapy regimens had a median overall survival (OS) of 18.5 months. Three patients are still alive 30, 30, and 31 months after GT. CONCLUSION: With the combination of secondary optimal debulking, GT, and topotecan, median OS was about one-third longer than in previously reported second-and third-line trials. Survival was comparable to that of patients of other studies with secondary cytoreductive surgery in combination with chemotherapy.

Acyclovir↗
PubMed2000

Thymidine kinase gene therapy with concomitant topotecan chemotherapy for recurrent ovarian cancer.

INTRODUCTION: Patients with recurrent ovarian cancer were treated with a replication-deficient recombinant adenovirus containing the herpes simplex virus thymidine kinase gene administered intraperitoneally (i.p.) followed by administration of an anti-herpetic prodrug and topotecan. MATERIALS AND METHODS: A total of 10 patients with stage IIIc epithelial ovarian cancer underwent secondary debulking to < or =0.5 cm residual tumor. Patients with normal i.p. flow received i.p. delivery of adenovirus. Two patients each were treated on dose level 1 (2 x 10(10) vector particles (VP)), dose level 2 (2 x 10(11) VP), and dose level 3 (2 x 10(12) VP); four patients were treated on dose level 4 (2 x 10(13) VP). Acyclovir and topotecan were started 24 hours after vector delivery. RESULTS: No patient treated at any dose level incurred unanticipated toxic effects, and all side effects resolved. The most common adverse event was myelosuppression: grade 3 or 4 thrombocytopenia with grade 2-4 anemia in three patients and grade 3 or 4 neutropenia in eight patients. Three patients developed thrombocytosis and three patients had a mild elevation of serum glutamic pyruvic transaminase/alanine aminotransferase. Temperature elevations that were not associated with detectable infection occurred in two patients. DISCUSSION: I.p. delivery of adenoviral vector with concomitant topotecan chemotherapy was well tolerated without significant lasting toxicities. Side effects were independent of the dose of adenoviral vector.

Acyclovir↗
PubMed1999

Molecular aspects of ovarian cancer. Is gene therapy the solution?

Genetic abnormalities of cancer cells are complex and usually nonspecific. Genetic anomalies specific to ovarian cancer have not been reported. This article focuses on what molecular anomalies are known in ovarian cancer and describes the first trials that have used transfer of genes to reestablish a normal cellular function in this disease. Suicide gene therapy has been the prototype of this new therapeutic approach.

Female↗
PubMed1996

In vivo gene therapy of ovarian cancer by adenovirus-mediated thymidine kinase gene transduction and ganciclovir administration.

Efficacy and toxicity of adenovirus-mediated transfer of the herpes simplex virus thymidine kinase gene followed by administration of ganciclovir were studied in vivo. A human epithelial ovarian cancer animal model was established in nude mice using the serous ovarian adenocarcinoma cell line Ov-ca-2774. Intraperitoneal (ip) injection of 1 x 10(8) Ov-ca-2774 cells resulted in tumor growth and formation of malignant ascites in all 15 animals. In a prospective randomized experimental design mice were treated 1, 3, or 7 days after ip injection of 1 x 10(8) cells with ip injection of 2 x 10(8), 6.7 x 10(8), or 2 x 10(9) pfu ADV.RSV-TK followed by administration of ganciclovir (10 microgram /ml, ip, bid) for 6 consecutive days. End points were survival and toxicity. Mice treated with GCV or HSV-TK alone died from 14.4 +/- 1.7 to 19.5 +/- 3.5 days after treatment as did untreated controls. No toxicity of ADV.RSV-TK was found up to 2 x 10(9) pfu (2 x 10(11) particles). The mice with the highest tumor burden treated with the lowest viral dose lived significantly longer than controls (P < 0.05). Median survival in all other groups of mice treated with ADV.RSV-TK plus GCV was even longer (P < 0.01). Treatment benefit was dependent on ADV/RSV-TK dose and tumor burden. Adenovirus-mediated thymidine kinase gene therapy is a realistic approach to ovarian cancer treatment that warrants investigation in the clinical setting.

Adenoviridae↗
PubMed1996

Subcellular localization of accumulated p53 in ovarian cancer cells.

Inactivation of the tumor suppressor gene p53 is frequently associated with ovarian cancer. Accumulation of stabilized p53 protein is a common feature in this tumor type. Underlying mutations in the p53 core region can lead to loss of the normal conformational state or loss of residues necessary for DNA binding and transcriptional regulation. Five HPV-free ovarian cancer cell lines established in our laboratory with and without immunocytochemically detectable p53 expression were selected for the correlation of subcellular localization of aberrant p53 and the type of gene mutation. The expression level regarding staining intensity and proportion of cells accumulating p53 was characterized employing an immunoreactive score. Two cell lines with point missense mutations in the core region showed strong nuclear or nuclear plus cytoplasmic staining. One cell line with exclusive staining of the cytoplasm contained a deletion of the major nuclear localization signal. Among two cell lines without p53 accumulation, one contained a microdeletion resulting in a frame shift, the other carried the wild-type sequence. The MDM2 oncogene was not amplified and its gene product was not overexpressed. In ovarian cancer, inactivated p53 can accumulate in both major cell compartments depending on the type of the underlying mutation.

Base Sequence↗
PubMed1995

Glycolipid patterns during Xenopus embryo development.

Glycolipid patterns have been studied during the first six days of Xenopus embryo development. Glycolipid contents showed a sharp increase more evident after the third day of development. Glucosylceramide and sulphatide are not only the most represented species, but also those which exhibit a statistically significant percentage change during early development. Among gangliosides, GD3 is the most represented specie. Two polysialylated gangliosides with not yet established structures are also present.

Ammonia↗
PubMed1994

p53 mutant His175 identified in a newly established fallopian tube carcinoma cell line secreting interleukin 6.

Fallopian tube carcinoma is a lethal gynecologic malignancy. Etiologic factors are unknown. No experimental data on molecular alterations exist so far. For an in vitro model, we established the permanent human tubal carcinoma cell line FT-MZ-1. The median doubling time was 14 days with 24.2% in S phase. A point missense mutation of the p53 tumor suppressor gene resulting in the His175 mutant was identified. Aberrant p53 protein accumulated in nucleus and cytoplasm. FT-MZ-1 substantially secreted interleukin 6 (Il-6) coinciding with the inactivation of p53 as a transrepressor on the Il-6 gene promoter.

Base Sequence↗
PubMed1994

Multiplex PCR screening detects small p53 deletions and insertions in human ovarian cancer cell lines.

Mutations at the p53 tumor suppressor gene locus are a frequent genetic alteration associated with human ovarian carcinoma. Little information exists regarding whether mutational events occur other than point mutations and large deletions, causing loss of heterozygosity. Small intragenic deletions and insertions in the p53 gene have been observed in various human neoplasias. We developed a multiplex polymerase chain reaction (MPCR) screening assay to amplify the complete p53 coding region from genomic DNA in a single step. Deletions and/or insertions were found in six out of 11 newly established ovarian carcinoma cell lines. MPCR detected deletions as small as 2 bp, as confirmed by nucleotide sequence analysis. Most of the observed alterations (6/7) were homozygous or hemizygous. Structural aberrations of the p53 gene possibly leading to loss of p53 cell cycle control may be a consequence of a slipped-mispairing mechanism in rapid DNA replication during repetitious ovulation and wound repair of ovarian epithelial cells. MPCR may be a valuable tool for screening for possible p53 deletion and insertion mutations not only in ovarian cancer but also in other malignancies.

Base Sequence↗
PubMed1993

Alterations of serum phospholipids in patients with multiple sclerosis.

The total phospholipids in serum and the percentages of major phospholipid classes of phosphatidylserine (PS), phosphatidylcholine (PC), phosphatidylethanol-amine (PE) and sphingomyelin (SM) were studied based on 21 patients with multiple sclerosis (MS) and 18 healthy subjects. Serum samples were extracted with isopropanol, then major phospholipid classes were separated by thin-layer chromatography, finally, the samples were quantitated by CS-910 densitometer. Though the results were insignificantly different in the concentration of total phospholipid between the MS patients and the controls, there was partial reduction of the concentrations of PS and PE (P < 0.01), moreover, the percentages of PS and PE were relatively lower, correspondingly, the percentage of PC was higher as compared with control group. The results suggest that there should exist an abnormality in the metabolism of phospholipids in patients with MS in the sense of the alterations of phospholipid compositions in serum samples.

Adult↗
PubMedDate not supplied

Thymidine kinase (TK) gene therapy of solid tumors: valacyclovir facilitates outpatient treatment.

BACKGROUND: In a Phase I study replication-deficient adenovirus containing the herpes simplex virus (HSV) thymidine kinase (TK) gene (AdV-HSV-TK) was instilled intraperitoneally in patients with recurrent ovarian cancer. Patients were treated with Acyclovir (ACV) or Valacyclovir (VCV) as enzymatic substrates. The purpose of this study was to compare serum levels of ACV and VCV. PATIENTS AND METHODS: The antiherpetic prodrug and Topotecan (1.0 mg/m2 over 30 minutes each day for 5 days) were started 24 hours after vector application. Eight patients received ACV (15 mg/kg i.v. over one hour every 8 hours for 42 doses), two patients were started on ACV for 5 days and then switched to oral VCV (2 g every 8 hours for a total of 42 doses). Blood samples were obtained 20 minutes prior to each drug. RESULTS: Serum levels of ACV and VCV (converted to ACV) were comparable. CONCLUSIONS: Suicide gene therapy with TK is under investigation in a variety of solid tumors. Replacing ACV by VCV will offer a cost-effective alternative and will significantly reduce duration of hospital stay improving quality of life and facilitating an outpatient gene therapy concept.

Acyclovir↗
PubMedDate not supplied

Androgen receptor gene mutations do not occur in ovarian cancer.

Genetic alterations have been frequently found in ovarian cancer. There is some indirect evidence indicating that mutation of the steroid receptor genes may play a role in the carcinogenesis of ovarian cancer. Human androgen receptor (hAR) gene mutations have been found in up to 50% of hormone-relapsed prostate cancer. The role of hAR mutation and its association with decreased expression in ovarian cancer has never been elucidated. In this study mutations of hAR gene in 38 human ovarian cancer cell lines with different AR expression pattern were studied using SSCP. No mutation of the hAR gene was found. Mutation of hAR gene is an infrequent event and therefore unlikely to be involved in the development of ovarian cancer. The decreased expression of hAR in advanced ovarian tumor is not due to genetic aberration of hAR. Mutation screening of hAR may not provide any information for risk assessment of developing ovarian cancer.

Cystadenocarcinoma, Serous↗
PubMedDate not supplied

Adenovirus-mediated suicide gene therapy for bladder cancer: comparison of the cytomegalovirus- and Rous sarcoma virus-promoter.

BACKGROUND: To compare efficacy and toxicity of the human cytomegalovirus-immediate-early (CMV) promoter and the Rous-sarcoma-virus (RSV) promoter to express thymidine kinase (tk) for adenovirus-mediated suicide gene therapy of experimental bladder cancer in vivo and in vitro. MATERIALS AND METHODS: In vitro: 3 human (5637, RT-4 and TCC-SUP) and one murine (MBT-2) bladder cancer cell line were exposed to ADV/RSV-tk or ADV/CMV-tk vectors and cell survival was determined. In vivo: Subcutaneous tumors were established and adenovirus vectors were injected 10 days later. RESULTS: In vitro: ADV/CMV-tk was up to 4 times more potent in terms of cell killing than ADV/RSV-tk. In vivo: ADV/CMV-tk had a three-fold higher antitumor potency per viral particle as compared to ADV/RSV-tk. Higher doses of ADV/CMV-tk caused treatment-associated hepatotoxicity. CONCLUSIONS: Our results confirm the efficacy of adenovirus-mediated tk suicide gene therapy in the treatment of experimental bladder cancer. Dose-related toxicity was greater with the use of ADV/CMV-tk, but lower doses achieved the same efficacy as ADV/RSV-tk.

Adenoviruses, Human↗
PubMedDate not supplied

Adenovirus-mediated thymidine kinase gene transduction in human epithelial ovarian cancer cell lines followed by exposure to ganciclovir.

In an effort to develop gene therapy for ovarian cancer efficacy and toxicity of adenovirus-mediated transfer of the HSV-TK gene followed by administration of ganciclovir were studied in two human epithelial ovarian cancer cell lines Ov-ca-2774 and Ov-ca-1225. 100% transduction was achieved in both cell lines at MOIs of 7 and 15 as demonstrated by X-Gal staining. No toxicity of virus alone was observed at MOIs up to 30. GCV was not toxic up to 200 micrograms/ml. Cell killing efficacy was shown to be dependent on MOI as well as GCV dose. The "bystander effect" of ADV/RSV-TK was quantified by mixing experiments and found to be dependent on the proportion of ADV/RSV-TK positive cells as well as the GCV dosage. Similar results were observed in both cell lines. ADV/RSV-TK mediated gene therapy may be a promising approach in ovarian cancer.

Adenoviridae↗
PubMedDate not supplied

Chicken ovalbumin upstream promoter--transcription factor (COUP-TF) expression in human endometrial cancer cell lines.

COUP-TF is an orphan member of the steroid receptor superfamily. COUP-TF down-regulates hormonal induction by other steroid receptors involved in cell proliferation and differentiation. Previous study has suggested a role in gynecological adenocarcinoma. In the present study we evaluated COUP-TF expression in endometrial cancer. Fourteen permanent endometrial cancer cell lines were established front the primary site of 14 endometrial cancer patients. Immunocytochemistry for COUP-TF-like activity was performed using an affinity selected polyclonal rabbit-derived antibody in an immunoperoxidase staining technique. The staining intensity and cell surface area were quantified by image analysis. By immunostain 2 cell lines were COUP-TF (+), 6 (+ +) and 6 (+ + +). Quantitative differences in staining intensity and cell surface area were not significant in these groups. All cell lines tested were immunocytochemically negative for estrogen and progesterone receptors. COUP-TF is a new factor involved in endometrial cancer cell differentiation and growth, especially in estrogen receptor negative tumors.

Animals↗
PubMedDate not supplied

Human epithelial ovarian cancer xenotransplants into nude mice can be cured by adenovirus-mediated thymidine kinase gene therapy.

BACKGROUND: Adenovirus-mediated suicide gene therapy of ovarian cancer has effective anti-tumor effects in vitro and in vivo. By transduction of ovarian adenocarcinoma with the Herpes Simplex Thymidine Kinase gene and subsequent treatment with the antiviral agent ganciclovir, prolongation of survival has been described in nude mice. So far, however, in animal models of solid tumors no cures have been reported after gene therapy. METHODS: In a prospective randomized experimental design 76 mice with xenotransplanted serous ovarian carcinoma were treated with three different doses of ADV/RSV-TK at three different time points followed by intraperitoneal ganciclovir administration. The experiment was designed to show significance of survival differences upon doubling of the number of survived days at a p-value of 0.05 with a power of 80%. The endpoint of the trial was survival. RESULTS: Treatment response was seen in all treated animals evident by significant prolongation of survival. Treatment response was dependent on the therapeutic viral dose and the tumor burden of the animal at the time of treatment. Two out of eight mice with early disease have now survived ten months without evidence of disease with untreated animals dying after nineteen days. Subcutaneous tumor development at the injection site was the reason of death in the remaining six mice of this group. CONCLUSIONS: Intraperitoneal ADV/RSV-TK suicide gene therapy of epithelial ovarian cancer in combination with ganciclovir administration can cure nude mice with early disease. This treatment modality may lend itself to incorporation into the current treatment concept of human ovarian malignancy. Clinical trials are warranted.

Adenoviridae↗