[The promotive effects of N-nitrosopiperidine on the malignant transformation of the immortalized esophageal epithelium induced by human papillomavirus].
BACKGROUND
Study on the promotive effects of N-nitrosopiperidine on carcinogenesis process was performed, based on the immortalization of human fetal esophageal epithelium induced by human papillomavirus (HPV) 18E6E7 genes.


METHODS
The immortalized esophageal epithelium SHEE was induced by HPV18E6E7. The cells at 17th passages were cultured in 50 ml flasks. The N-nitrosopiperidine (NPIP) 0, 2, 4, 8 mmol/L added to the cultured medium of SHEE cells for 3 weeks. The morphology, proliferation and apoptosis of the cells were studied by phase contrast microscopy and flow cytometry. Modal number of chromosomes was analyzed by standard method. Tumorigenicity of the cells was assessed by soft agar colony formation and by transplantation of cells into nude mice. Expression of HPV was detected by Western blot.


RESULTS
When cells were exposed to high concentration (8 mmol/L) of NPIP, cell death was increased, leaving a few live cells. In normal cultural medium instead of NPIP proliferative status of the cells restored after 4 weeks and the cells progressed to the proliferation stage with continuous replication and atypical hyperplasia. At the end of the 8th week, the cells appeared with large colonies in soft-agar and tumor formation in transplanted nude mice. When the cells were cultured in 2, 4 mmol/L NPIP the doubling passage was delayed and without tumor formation in transplanted nude mice. Modal number of chromosomes was 61-65, in 8 mmol/L NPIP group and control group, 56-61. Expression of HPV18 appeared in experimental and control groups.


CONCLUSIONS
NPIP promotes malignant change of the immortalized esophageal epithelial cells induced by HPV18E6E7. HPV18E6E7 synergy with NPIP will accelerate malignant transformation in esophageal epithelium.
Shen
Zhong-Ying
ZY
Shantou University Medical College, Shantou 515031, China.
Teng
Zhi-Ping
ZP
Shen
Jian
J
Cai
Wei-Jia
WJ
Chen
Ming-Hua
MH
Qin
Shan
S
Chen
Jiong-Yu
JY
Zeng
Yi
Y
D000818:Animals; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002471:Cell Transformation, Neoplastic / Q000187:drug effects*; D002472:Cell Transformation, Viral / Q000187:drug effects*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000821:virology; D004947:Esophagus / Q000166:cytology; D005434:Flow Cytometry; D052161:Human papillomavirus 18 / Q000502:physiology*; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009374:Neoplasms, Experimental / Q000378:metabolism / Q000473:pathology; D009602:Nitrosamines / Q000633:toxicity*; D009856:Oncogene Proteins, Viral / Q000378:metabolism
D004268:DNA-Binding Proteins; C052603:E6 protein, Human papillomavirus type 18; D009602:Nitrosamines; D009856:Oncogene Proteins, Viral; C002743:N-nitrosopiperidine