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Cisplatin-induced apoptosis and p53 gene status were analyzed in human ovarian carcinoma using a parental IGR-OVI line and a derived cisplatin-resistant IGR-OVI/DDP subline. Compared with parental cells, cisplatin-resistant cells exhibited a 5-fold higher resistance index and a 2-fold longer doubling time. Cisplatin induced apoptosis in both cell lines, as assessed by cell morphology and the presence of a DNA ladder. However, high concentrations were necessary to induce apoptosis in resistant cells. These cells elicited a 5-fold decrease in the number of platinum atoms bound per nucleotide. IGR-OVI/DDP cells also exhibited enhanced drug efflux and a higher glutathione content. Our data suggest that the levels of cisplatin-DNA lesions are critical for drug sensitivity and apoptosis induction in this in vitro ovarian carcinoma model. Comparative analysis of the p53 gene in sensitive and resistant cells revealed the presence of the same heterozygous mutation in exon 5. A 2-fold increase in p53 mRNA and protein amounts was observed in resistant cells as assessed by Northern and Western blots, respectively. Immunocytochemical staining revealed a higher percentage of p53 stained nuclei in resistant cells. RT-PCR analysis of p53 transcripts showed that both wild-type and mutated alleles were transcribed in sensitive as well as in resistant cells. However, mutated transcripts were 1.5-fold more abundant than wild-type transcripts in sensitive cells, whereas they were 2-fold higher in resistant cells. In addition, mdm-2 protein was over-expressed in resistant cells. Our results address the question of the functionality of p53 protein and its possible role in apoptosis induction in this model. In resistant cells, p53 protein might be inactivated by 2 mechanisms: mutation and complexation with mdm-2 protein. Therefore, the presence of non-functional p53 in resistant cells might be involved in the relative failure of cisplatin-induced apoptosis in these cells. © 1996 Wiley-Liss, Inc.

Objective: To detect, quantify, and compare respiratory epithelial cell proliferation in nasal mucosa and polyps from patients with nasal polyposis. Design: Cohort study. Setting: Patients and samples were selected at the Hopital Intercommunal de Creteil (France). Flow cytofluorometry and immunohistochemistry were performed at Hopitaux Tenon and Mondor (Universite Paris [France] VI et XII). Patients: Twenty-one patients undergoing endoscopic ethmoidectomy for treatment of nasal polyposis. Methods: In 10 cases, epithelial cells were removed from frozen inferior turbinate mucosa and polyps by mechanical disaggregation and were then analyzed by flow cytofluorometry, providing the cell DNA content (propidium iodide labeling) and the percentage of S-phase cells. In 11 cases, inferior turbinate mucosa and polyps were fixed in formaldehyde and embedded in paraffin. Proliferating cell nuclear antigen expression in the epithelium was quantified by immunohistochemistry: a proliferating cell nuclear antigen index was calculated for each sample in the basal area, suprabasal area, and full height of the epithelium. Results: All cell populations studied were diploid, and percentages of S-phase cells were significantly higher in nasal polyps than in mucosa. Proliferating cell nuclear antigen indexes were significantly higher in nasal polyps than in the suprabasal area and full height of the mucosal epithelium. Conclusion: Cell proliferation is increased in epithelium from nasal polyps. Epithelial damage caused by inflammatory mediators could induce this increased cell proliferation via epithelial repair processes. Inflammatory cells could up-regulate epithelial cell proliferation by secreting growth factors. (Arch Otolaryngol Head Neck Surg. 1996;122:432-436)