Establishment and characterization of a human cell line from a serous papillary endometrial carcinoma

Adenovirus-mediated gene therapy of ovarian cancer in a mouse model

OBJECTIVE

Our purpose was to test the feasibility of adenovirus-mediated gene therapy of ovarian cancer.

STUDY DESIGN

Ovarian cancer cell lines were exposed to an adenovirus vector expressing a reporter gene (lacZ) and to the same vector bearing the herpes simplex virus thymidine kinase gene (Ad.RSVtk) followed by ganciclovir. lacZ expression and growth inhibition were quantitated. Immunodeficient mice were injected intraperitoneally and subcutaneously with human ovarian cancer cells and treated with Ad.RSVtk and ganciclovir. Statistical analyses included one-way analysis of variance and t tests.

RESULTS

Staining for lacZ demonstrated viral transduction in vitro. After exposure to Ad.RSVtk all cell lines showed significant (p < 0.0001, analysis of variance) cytotoxicity to ganciclovir. Human ovarian tumor cells established subcutaneously or intraperitoneally in immunodeficient mice responded to therapy with Ad.RSVtk followed by ganciclovir. Treated mice had a 10- to 20-fold lower subcutaneous tumor burden than did control mice. Additionally, no intraperitoneal tumors were observed in treated mice.

CONCLUSIONS

Ovarian cancer cells are readily transduced with recombinant adenovirus and become sensitive to ganciclovir after transduction with Ad.RSVtk. These data support the development of this method for human clinical trials.

Mutational analysis of the p21/WAF1/CIP1/SDI1 coding region in human tumor cell lines

p21/WAF1/CIP1/SDI1 is an important cell-cycle mediator with tumor suppressor gene capabilities, and its inactivation could potentially lead to tumor progression. Because tumor suppressor genes are commonly inactivated by somatic and germline mutations, we analyzed a variety of human tumor cell lines for p21 mutations. We used single-strand conformational analysis and direct sequencing to identify possible mutations in the p21 coding region. Two base-alterations were observed in 41 immortalized human tumor cell lines. A previously reported polymorphism that results in a serine-to-arginine amino-acid substitution at codon 31 was found in 24% (10 of 41) of the tumor cell lines but was also found in 10% (six of 62) of normal parental DNAs tested and 7% (three of 43) of normal DNAs from patients with primary endometrial tumors. Another nucleotide substitution found at codon 80 resulted in the replacement of threonine with methionine. Codon 80 changes were found in 7% (three of 41) of the tumor cell lines (all endometrial) and in 2% (one of 62) of the normal parental DNAs. This change was not found in any of the primary endometrial tumors examined. The biological activity of these base changes was analyzed by using in vitro cyclin-dependent kinase 2-cyclin A kinase assays and calcium phosphate transfections. We observed that wild-type p21 and the p21 variants had similar growth-inhibitory abilities. Thus, our results suggest that mutation of the p21 gene is not prevalent in human tumor cell lines and is not a probable mechanism of inactivation of this gene.

Characterization of murine cell lines from diethylstilbestrol-induced uterine endometrial adenocarcinomas

Neonatal treatment with estrogens is associated with development of uterine adenocarcinomas in CD-1 mice. Treatment with the synthetic estrogen diethylstilbestrol (DES) on Days 1 to 5 after birth results in 90% incidence of these hormone-dependent lesions in 18-mo.-old mice. Three cell lines were established from these DES-associated tumors. Each of these cell lines exhibited morphologic and ultrastructural characteristics of transformed epithelial cells, including an increased nuclear:cytoplasmic ratio, enlarged and irregular nuclei with multiple nucleoli and areas of chromatin condensation, positive staining for cytokeratin, desmosomes, and microvilli. After subcutaneous injection into nude mice, all three cell lines formed solid tumors within 4 wk. Although the primary uterine tumors and tumor transplants in nude mice had been shown to be estrogen-dependent and estrogen-receptor positive, neither the monolayer growth nor the tumorigenicity of any of the three cell lines in this study was enhanced by or dependent on estrogen. Estrogen receptor levels were low in early and intermediate passage cells. Allele-specific oligonucleotide hybridization analysis of PCR-amplified cell line DNA revealed no point mutations in the 12th, 13th, or 61st codons of the K-ras or H-ras protooncogenes. Southern analysis revealed no changes in genomic organization of the putative tumor suppressor gene DCC, but demonstrated a three- to four-fold amplification of the c-myc gene in one cell line. Expression of c-myc RNA was concomitantly increased in the same cell line. These three transformed cell lines represent the end point in the process of hormone-associated tumorigenesis and as such should prove useful in investigating the molecular changes and the mechanisms involved in hormonal carcinogenesis.

Analysis of oncogene alterations in human endometrial carcinoma: prevalence of ras mutations

The molecular genetics of human endometrial carcinoma have yet to be defined to any significant extent. Cell lines from 11 endometrial carcinomas were examined for alterations in proto-oncogenes that might predictably be present, based on existing data from the better-characterized human carcinomas of the uterine cervix, ovary, and breast. Codons 12, 13, and 61 of the Ha-ras, Ki-ras, and N-ras genes were examined for possible point mutations, and the c-erbB2/neu, c-myc, and epidermal growth factor receptor (EGFR) genes were examined for amplification or overexpression. Ras mutations were found in seven of 11 (64%) tumors, including three in codon 61 of Ha-ras (CAG----CAT) and four in codon 12 of Ki-ras (GGT----GAT in two and GGT----GTT in two). No evidence was found for amplification or overexpression of the c-erbB2 or EGFR genes in any tumor. One tumor contained amplified c-myc sequences and exhibited relative overexpression of c-myc. These data suggest that the amplification or overexpression of several proto-oncogenes frequently observed in other human gynecologic and breast tumors are not prevalent in endometrial carcinoma and that ras gene mutations are relatively common in this tumor type.