Improved ELISA proliferation assay (EPA) for the detection of in vitro cell proliferation by a new Ki-67-antigen directed monoclonal antibody (Ki-S3)

Effect of covalent photoconjugation of affibodies to epidermal growth factor receptor (EGFR) on cellular quiescence

Cellular quiescence is a reversible state of cell cycle arrest whereby cells are temporarily maintained in the nondividing phase. Inducing quiescence in cancer cells by targeting growth receptors is a treatment strategy to slow cell growth in certain aggressive tumors, which in turn increases the efficacy of treatments such as surgery or systemic chemotherapy. However, ligand interactions with cell receptors induce receptor-mediated endocytosis followed by proteolytic degradation, which limits the duration of cellular quiescence. Here, we report the effects of targeted covalent affibody photoconjugation to epidermal growth factor receptors (EGFR) on EGFR-positive MDA-MB-468 breast cancer cells. First, covalently conjugating affibodies to cells increased doubling time two-fold and reduced ERK activity by 30% as compared to cells treated with an FDA-approved anti-EGFR antibody Cetuximab, which binds to EGFR noncovalently. The distribution of cells in each phase of the cell cycle was determined, and cells conjugated with the affibody demonstrated an accumulation in the G1 phase, indicative of G1 cell cycle arrest. Finally, the proliferative capacity of the cells was determined by the incorporation of 5-ethynyl-2-deoxyuridine and Ki67 Elisa assay, which showed that the percentage of proliferative cells with photoconjugated affibody was half of that found for the untreated control.

Does Candida Albicans Play a Role in the Etiology of Endometriosis?

Purpose

There is increasing evidence that immunologic mechanisms play a role in the pathogenesis of endometriosis. A high incidence of infection with Candida albicans in women with endometriosis has been reported. There is evidence to suggest that C. albicans may contribute to the pathogenesis of endometriosis possibly by modulating cytokine production.

Methods

Endometrial tissue was obtained from eight women attending Aberdeen Royal Infirmary for laparoscopic sterilization or investigation of infertility (n=7 patients without endometriosis, n= 1 patient with endometriosis). Culture of endometrial cells with inactivated Candida/Candida product was performed. The endometrial tissue was processed using a number of different assays including Ki-67 cell proliferation assay, DELFIA Ki-67 assay, MTT cell viability assay, and BrdU incorporation proliferation assay.

Results

The results from seven women without endometriosis showed that Candida product significantly (P<0.01) reduced both cell viability and cell proliferation in the presence and absence of estradiol. The effects of Candida product on endometrial cells from the patient with endometriosis differed from the average effect on seven women without endometriosis: stimulation of cell viability in the presence of estradiol and suppression of cell proliferation only at the highest dose. In terms of the effects of inactivated Candida, there was a reduction in cell viability by up to 60% (unlike in the normal women), but an increase in cell proliferation of cells both in the presence and absence of estradiol.

Conclusions

Our preliminary observations suggest that C. albicans may stimulate cell proliferation of endometrial cells from women with endometriosis whilst it seems to have an opposite effect on cells from women with no endometriosis. Caution must be exercised in the interpretation of the latter data since only one woman with endometriosis was included, but the results suggest there may be differences in the way in which Candida product and inactivated Candida affect endometrial cell viability and proliferation between women with and without endometriosis.

Characterization of a New Double-Injury Restenosis Model in the Rat Aorta

PURPOSE

To characterize a new rat model of restenosis for evaluation of local or systemic drug strategies.

METHODS

Arterial lesions were induced by placement of silicone cuffs around the aorta of Lewis rats. After 21 days, the cuffs were removed, and a subgroup of rat aortas was subjected to secondary balloon injury. Remodeling of wall compartments and cell kinetics were assessed morphometrically at 3, 7, 14, 21, and 28 days after the single and double-injury approaches. Immunohistochemistry was used to assess the distribution of macrophages, smooth muscle cells, and proliferating cells within the layers of the arterial wall in the experimental groups versus sham-operated and untreated controls.

RESULTS

After cuff placement, the adventitia initially undergoes significant enlargement, while the media shows a reduction in relative thickness. Accumulation of cells within the adventitia at 3 and 7 days is followed by a marked decline in cell density at 14 days, with simultaneously increasing cell numbers in the intima. At this time, activated macrophages are detected in the adventitia, indicating chronic inflammation. Following cuff placement, mild intimal hyperplasia develops. In the double-injury model, extensive neointimal hyperplasia forms rapidly, with a peak at 14 days.

CONCLUSIONS

This new double-injury model is technically easy, and multiple experiments can be accrued in short periods of time. It provides an additional platform to identify new targets and strategies for the prophylaxis of postangioplasty restenosis.

Immunoenzymatic detection of the new proliferation associated protein p100 by means of a cellular ELISA: specific detection of cells in cell cycle phases S, G2 and M

In vitro proliferation assays are widely used in biomedical research. We describe the immunoenzymatic (ELISA) detection of a recently described proliferation associated protein (p100) by means of a new monoclonal mouse IgG1 antibody (Ki-S2). P100 is a 100 kDa nuclear protein that is specifically detected during the cell cycle phases S, G2 and M. Comparative studies on lectin-stimulated leukocytes using 3H-thymidine labelling and Ki-67 antibodies revealed a statistically significant positive correlation. Since p100 is absent in GO and G1 cells, its detection permits the precise and specific measurement of actual cell cycle events under culture conditions.