Malignant Transformation of Immortalized Human Embryonic Esophageal Epithelial Cells lnduced by Human Papillomavirus
This paper intented to identify the inducement of malignant transformation in parts of immortalized human embryonic esophageal epithelial cells (SHEE) by HPV18 E 6E 7 at the 61th passage and to search a method to monitor the early malignant transformation of the cells. The cultured SHEE cells at its 10th(SHEE10) and 61st passages (SHEE 61) were observed under light and electron microscope for cell morphology and cell growth pattern, analyzed by flow cytometry for cell cycle, tested by chromosome G-band idiogram and assayed for centromeres of the interphase nucleus with the probes of chromosomes 1,7,8, by FISH. The rapidly growing cell clone (SHEE61A) was selected with optimum seeking method from SHEE61 cell line and it was used to inoculate into nude mice and SCID mice. The results showed that SHEE61 cells were different in size and shape and grew overlapped under light microscope. They showed a proliferative phenotype with polymorphic nuclei and enlarged nucleoli under electron microscope. SHEE10 and SHEE61 cells when tested by flow cytometry, both had the similar proliferative cycle as indicated by DNA histograms, but the proliferative index and the cells with DNA4n in SHEE61 cells were more than that in SHEE10 cells. Chromosome modal number of SHEE61 cells revealed two subpopulation, 57-60 and 63-65, and in chromosomes 1,7,9,13,17, the trisomy, tetrasomy and pentasomy were frequently seen. FISH revealed the centromere increment in interphase nuclei of chromosomes 1,7. When both SHEE 10 and SHEE61A cells were separately inoculated into SCID mice, the latter developed tumors and infiltrated into the muscular layer. So, it can be judged that SHEE61A cells has been malignantly transformed. The experimental data showed that the early malignantly transformed cells may be monitored by examining cell genetic characteristics and the clone optimum seeking method.