Showing papers by "Janet E. Price published in 1993"

Enhanced c-erbB-2/neu Expression in Human Ovarian Cancer Cells Correlates With More Severe Malignancy That Can Be Suppressed by E1A

Abstract: Amplification or overexpression of c-erbB-2/neu protooncogene, or both, occur frequently in many different types of human cancers and have been shown to correlate with decreased survival in ovarian cancer patients. We have previously found that the ovarian carcinoma cell line SK-OV-3 overexpresses c-erbB-2/neu mRNA. To further study the biological effect of c-erbB-2/neu overexpression in SK-OV-3 cells, we injected such cells i.p. into female nu/nu mice and found that this cell line forms extensive abdominal tumors and ascites. From the ascites in an injected mouse, we established the SKOV3.ip1 cell line and found that it expressed 2-fold more c-erbB-2/neu-encoded p185 proteins than the parental SK-OV-3 cells. When transformation phenotypes of SK-OV-3 and SKOV3.ip1 cells were compared, SKOV3.ip1 cells showed higher cell growth and DNA synthesis rates, formed more colonies in soft agar, produced larger s.c. tumors, and resulted in shorter survival of nu/nu mice after i.p. injection. These data indicate that the level of c-erbB-2/neu overexpression may correlate with the degree of malignancy in these ovarian carcinoma cells. Since we had previously shown that the adenovirus 5 E1A gene product can suppress transformation and metastatic properties induced by mutation-activated rat neu oncogene in mouse embryo fibroblast cells, we further examined whether E1A can abrogate malignancy in c-erbB-2/neu-overexpressing human ovarian cancer cells. We introduced the E1A gene into c-erbB-2/neu-overexpressing SKOV3.ip1 cells and found that the E1A-expressing ovarian cancer cell lines had decreased c-erbB-2/neu-encoded p185 expression and reduced malignancy, including a decreased ability to induce tumors in nu/nu mice. Therefore, we concluded that E1A is a tumor suppressor gene for c-erbB-2/neu-overexpressing human ovarian cancer cells and may be useful in developing therapeutic reagents for these human cancers.

Simultaneous radiolabel, genetic tagging and proliferation assays to study the organ distribution and fate of metastatic cells

Abstract: We compared the suitability of 3 techniques to study tumor cell survival in the lungs of mice and proliferation into metastases. Genetic tagging of tumor cells with the bacterial beta-galactosidase marker gene lacZ, radiolabeling of tumor cells with [I-125]IdUrd, and S-phase labeling of cells with bromodeoxyuridine (BrdUrd) were used simultaneously to track the fate of highly metastatic K-1735 X-21 melanoma cells injected into syngeneic C3H/HeN mice. The melanoma cells were transfected with a plasmid containing lacZ and neomycin resistance genes. After growth in selective medium, the cells were incubated in medium containing [I-125]IdUrd and then injected i.v. into mice. Lungs isolated at various times after i.v. injection were processed for staining with X-gal, radioactive monitoring, and immunohistochemical staining with a monoclonal antibody against BrdUrd. At early time points, the presence of lacZ-positive cells directly correlated with radioactivity associated with viable cells. However, the expression of the beta-galactosidase was only stable for 1 week, and by 3 weeks after injection, large metastases contained only a few lacZ-positive cells. The combination of lacZ tagging with BrdUrd proliferation assay accurately identified dividing tumor cells in micrometastases. The simultaneous use of these 3 techniques allowed us to conclude that quantitative analysis of tumor cell survival is best accomplished by radioactive labeling of cells, whereas the use of lacZ-tagged cells allowed for studies of localization. Analysis of tumor cell proliferation requires the use of both lacZ tagging and immunohistochemistry using anti-BrdUrd antibodies. Since the process of metastasis consists of a series of distinct steps, each technique presents its own advantages and limitations.