DNA Synthesis In Cell Lines Research Articles

Induction of FGF receptor 2-IIIb expression and response to its ligands in epithelial ovarian cancer.

Epithelial ovarian cancers (EOCs) arise in the Ovarian Surface Epithelium (OSE). This tissue is a simple, poorly committed mesothelium which exhibits characteristics of epithelial and mesenchymal cells when grown in culture. In contrast, EOCs frequently exhibit properties of complex epithelial tissues of the female reproductive tract, such as oviductal, endometrial and cervical epithelia, and show induction of expression of epithelial markers such as E-cadherin. Fibroblast Growth Factor Receptor 2 isoform IIIb (FGF receptor 2-IIIb) is a spliced variant of FGF receptor 2 that binds the ligands FGF-1 and FGF-7 with high affinity, and is expressed exclusively by epithelial cells. We have studied the expression of FGF receptor 2-IIIb and its ligands in primary cultures of normal human OSE, EOC cell lines and snap frozen tissue from EOCs. Expression of FGF receptor 2-IIIb mRNA is undetectable in normal OSE, but is expressed in 16/20 (80%) of EOCs. FGFs 1 and 7 mRNAs are expressed in normal OSE, whilst only 4/20 (20%) and 12/20 (60%) of EOCs demonstrated expression for these ligands respectively. However, FGF-7 protein was detected in 70% (mean level=0.7 ng/ml) of ascitic fluids obtained from patients with EOC. FGFs 1 and 7 stimulate DNA synthesis in EOC cell lines that express FGF receptor 2-IIIb. Moreover, DNA synthesis in these cell lines can be partially blocked by blocking antisera to FGFs 1 and 7. It is suggested that induction of expression of FGF receptor 2-IIIb may play a role in the development of EOCs by rendering the OSE susceptible to paracrine and/or autocrine stimulation by its requisite FGF ligands.

Resistance to UV-irradiation of DNA synthesis in fibroblast cell lines derived from LEC strain rats.

After UV-irradiation, no difference in the survival curves was observed among cell lines derived from LEC strain (LEC) rats and WKAH strain (WKAH) rats. The dose-response curves for inhibition of DNA synthesis in WKAH-derived cells showed a sharp decline at lower doses and a mild decline at higher doses of UV-rays. In contrast, the dose-response curves in LEC-derived cell lines had no sharp component, and were almost identical to the mild component of the curves in WKAH-derived cells. These results show that DNA synthesis in the cell lines of LEC rats was more resistant to UV-irradiation than that of WKAH rats.

Functional role of CD26 on human B lymphocytes

CD26 is a well-known activation marker on T cells and natural killer (NK) cells [1]. It is identical with the ectopeptidase dipeptidyl peptidase IV (DP IV). The expression of CD26 on B cells has been discussed controversially [2,3]. We have studied the expression of this enzyme on B cells from the peripheral blood of healthy donors and of CVID patients, on cells of the Daudi Burkitt line and the EBV-transformed B-cell lines Jojo and Laz509. DP IV was detected by using anti-CD26 monoclonal antibodies and with help of specific enzyme substrates. Further the influence of specific synthetic DP IV inhibitors on mitogenic activation of purified B cells and DNA synthesis of cell lines was studied. We could show that in both groups 0–5% of freshly isolated CD20-positive B cells do express the CD26 antigen. After stimulation with pokeweed mitogen or St. aureus protein, the fraction of CD26-positive cells was enhanced up to 51% and 36%, respectively. Interestingly, induction of CD26 expression on B cells from CVID patients occurs in a manner similar to the B cells from healthy donors. Treatment of peripheral blood B cells and B-cell lines with highly specific competitive DP IV inhibitors leads to a significant inhibition of DNA synthesis in a dose-dependent manner. These data show that CD26 can be considered to be an activation marker not only of T- and NK cells but also of a main population of B cells, suggesting an involvement of CD26 in B-cell activation.

A Comparison of Unscheduled DNA Synthesis, D 0 , Cell Recovery, and Chromosome Number in x-Irradiated Mammalian Cell Lines

SHAEFl'EH, JAMES, AND MERZ, TIMOTHY. A Comparison of Unscheduled DNA Synthesis, Do, Cell Recovery and Chromosome Number in x-irradiated Mammalian Cell Lines, Radiat. Res. 47, 426-436. The relative extent of x-ray-induced unscheduled DNA synthesis was measured in seven mammalian cell lines: HeLa, mouse L-929, rat kangaroo kidney, human embryonic kidney, human laryngeal tumor, rat kangaroo liver, and human peripheral lymphocyte. Radiosensitivities (Do) and recovery ratios were measured in the HeLa, mouse L-929, and rat kangaroo kidney lines. There was no apparent correlation between unscheduled DNA synthesis and radiosensitivity or recovery ratio in these cell lines. These observations are consistent with the conclusion that cell survival after x-irradiation is not solely, if at all, dependent on unscheduled DNA synthesis. A correlation was observed between the relative amount of unscheduled DNA synthesis in the cell lines studied and their modal chromosome number. Cell lines containing more chromosomes showed greater amounts of unscheduled DNA synthesis. No correlation was apparent, however, when unscheduled DNA synthesis was compared with DNA content. One cell line, the rat kangaroo kidney line, showed no apparent unscheduled DNA synthesis. Whether this absence of unscheduled synthesis is the result of an enzymatic deficiency or is the natural consequence of a low chromosome number (11) is not clear and warrants further investigation. INTRODUCTON