Expansion of p75NTR/Oct4-Expressing Putative Stem Cells in HPV16- Transformed Precancerous Immortal Cell Lines under the Presence of TGF and TNF

We show here a possible in vitro model system for the analysis of relationship between our proposed p75NTRexpressing tissue-type-stem cell (TSC) candidate and HPV16-immortalized p75NTR-positive putative stem cell lines. We demonstrate that HPV16-transformed human cervical epithelial cell lines express Oct3/4 and contain p75NTR-positive cell subpopulation at various ratios in the immortalized cell population. We have isolated clonal variants (NCE16N+ and NCE16N-) that express p75NTR at high or low levels, respectively, and examined responses against inflammatory cytokines, TGF and TNF . We demonstrate that expression levels of p75NTR in the two distinct lines, NCE16N+ and NCE16N-, are correlated with differences in survival rates in the presence of TGF . TGF also induced epithelialmesenchymal transition in these cell lines as demonstrated by the morphologic changes with expression of vimentin, enhanced migration, and induction of snail. TNF alone had no effect on these processes, but was essential for apoptosis by co-stimulation with TGF in NCE16N-. NCE16N+ was fairly resistant against apoptosis but sensitive to the inhibitory effect on the growth by these cytokines. Among receptors for these cytokines, the expression level of TGF RII in NCE16Nwas higher than that in NCE16+. Hyper-phosphorylation of ERK1/2, p38MAPK and JNK occurred in NCE16N+ but not in NCE16N-. A specific inhibitor to p38MAPK influenced the survival rate in NCE16N-. These results implicate that the p75NTR-positive precancerous cell lineage will have an advantageous phenotype to survive longer under inflammatory situation.