CYTOGENETIC ANALYSIS OF INVERTED NASAL PAPILLOMAS AND DEMONSTRATION OF GENETIC CONVERGENCE DURING IN-VITRO PASSAGING

Three inverted nasal papillomas were cytogenetically investigated afte r short-term culture. Two of the cases were characterized by a single abnormal clone with t(1;8)(p36;q11) and trisomy 7, respectively, where as the third papilloma showed extreme cytogenetic heterogeneity: of 85 2 analyzed cells, 329 belonged to 36 unrelated clones, 344 had non-clo nal changes, and 179 had a normal chromosome constitution. The polyclo nal papilloma was further analyzed during in vitro passage of 3 lines (L1-L3) cultured independently since initiation of the primary culture s and found to have 6, 16 and 6 unrelated clones at analysis of primar y cultures. At passage I, each line was further subdivided into 2 sub lines (LIA and B, L2A and B, and L3A and B), which were cultured separ ately until the cells spontaneously stopped dividing. After 4 to 7 pas sages, each sub-line was dominated (83-98% of the cells) by a single c lone. The cell populations that took over the cultures were the same w ithin each set of sub-lines (A and B lines), demonstrating that clonal overgrowth in vitro is not random. The difference in clonal selection among the L1-L3 lines further shows that genetic convergence during i n vitro growth in stable conditions is dependent not only on the clone s' ability to adapt to the culture conditions, but also on the nature of the neighboring cells with which they collaborate and compete. (C) 1997 Wiley-Liss, Inc.