Autocrine growth limitation of human papillomavirus type 16-harboring keratinocytes by constitutively released tumor necrosis factor-alpha.
TNF-alpha is known to exert antitumor and antiviral effects and to participate in the regulation of the immune response. In our study we demonstrate that human rTNF-alpha specifically blocks growth of SK-v keratinocyte cell line harboring and expressing human papillomavirus type 16 (HPV16) sequences. This inhibitory effect was shown by [3H]TdR incorporation and cell counting. Binding experiments with 125I-TNF-alpha showed that SK-v cells express about 10,000 single class TNF-alpha R per cell with affinity constant of about 0.7 nM. Binding of 125I-TNF-alpha could be inhibited by htr-9 mAb recognizing a 55/60-kDa type I TNF-alpha R but not by utr-1 mAb recognizing 75/80-kDa type II TNF-alpha R or irrelevant mAb specific for HPV16E7 protein. Addition of anti-TNF-alpha antibodies to SK-v cell culture resulted in significant (p < 0.05), dose-dependent stimulation of their proliferation. SK-v cells constitutively expressed TNF-alpha mRNA, and SK-v CM contained TNF-alpha, as demonstrated by Northern blot analysis, a specific ELISA, Western blot analysis, and a bioassay with TNF-alpha-sensitive L-M cells. HPLC gel filtration of SK-v cell CM showed that the factor cytotoxic for L-M cells coeluted with immunoreactive TNF-alpha. These results demonstrate that HPV16-harboring SK-v cells constitutively express and release immunoreactive and biologically active TNF-alpha that in turn may exert an autocrine growth inhibitory effect. This phenomenon could represent one of the self-limiting mechanisms controling growth of HPV-induced neoplasia.
Malejczyk
J
J
Department of Histology and Embryology, Warsaw Medical School, Poland.
Malejczyk
M
M
Köck
A
A
Urbanski
A
A
Majewski
S
S
Hunzelmann
N
N
Jablonska
S
S
Orth
G
G
Luger
T A
TA
D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D006801:Humans; D015603:Keratinocytes / Q000382:microbiology* / Q000502:physiology; D027383:Papillomaviridae / Q000187:drug effects*; D011994:Recombinant Proteins / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology / Q000502:physiology*
D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha