Increased tumorigenicity of human keratinocytes harboring human papillomavirus type 16 is associated with resistance to endogenous tumor necrosis factor‐α‐mediated growth limitation

Abstract

The aim of this study was to evaluate the relationship between tumorigenicity of cell sublines derived from weakly tumorigenic SKv-e and SKv-l keratinocytes harboring human papillomavirus type 16 (HPV16) and their susceptibility to autocrine growth limitation mediated by tumor necrosis factor-alpha (TNF-alpha). These sublines displayed different in vitro proliferative potential which correlated with tumorigenicity in nu/nu mice. Recombinant TNF-alpha inhibited in vitro growth of weakly tumorigenic parental SKv cell lines while it did not affect proliferation of their respective highly tumorigenic sublines. Resistance to TNF-alpha correlated with both increased in vitro proliferation and tumorigenicity. Anti-TNF-alpha antibodies (Ab) significantly increased in vitro proliferation of weakly tumorigenic parental SKv cells up to the levels of their highly tumorigenic sublines. Growth of highly tumorigenic SKv cells was not affected. On the other hand, proliferation of SKv cells was affected neither by transforming growth factor-beta (TGF-beta) nor by anti-TGF-beta Ab. All SKv cell sublines tested spontaneously released TNF-alpha, as evaluated by a specific radioimmunoassay; however, the levels of the endogenous cytokine were not related to their proliferative potential and tumorigenicity. An increased resistance to the anti-proliferative effect of TNF-alpha may be associated with decreased expression of TNF-alpha receptors (TNF-alpha R) inasmuch as evaluation of 125I-TNF-alpha binding and Northern-blot analysis of TNF-alpha R-specific mRNA showed that highly tumorigenic SKv cell sublines expressed significantly lower numbers of TNF-alpha R than their respective parental cells. These results show that an increased tumorigenicity of HPV16-harboring SKv keratinocytes may be, at least partially, due to escape from autocrine TNF-alpha-mediated growth limitation.

Progressive growth of human papillomavirus type 16-transformed keratinocytes is associated with an increased release of soluble tumour necrosis factor (TNF) receptor

“…In line with our previous observation (Malejczyk et al, 1994), the levels of specific steady-state mRNA were higher in SKv-Il than in SKv-12 cells. This difference was not caused by an unequal amount of RNA loaded onto each lane in as much as rehybridisation with ,B-actin cDNA probe showed similar amounts of specific ,B-actin mRNA.…”

“…However, it is tempting to speculate that sTNF-R may exert a tumour protecting effect: (1) shedding of surface-bound TNF-R from tumour cells may lead to their desensitisation to circulating TNF, and (2) sTNF-R may neutralise biological anti-tumour activity of the locally released TNF. Accordingly, release of higher amounts of sTNF-RI by highly tumorigenic SKv-12 cells was accompanied by their higher in vitro proliferation and correlated with their relative TNF-resistance and higher tumorigenic potential (Malejczyk et al, 1994). Furthermore, treatment of weakly tumorigenic, TNF-sensitive SKv-l 1 parental cells with rhsTNF-RI or SKv cell-derived TNF inhibitor resulted in a significant dosedependent stimulation of their growth.…”

“…Compared with weakly tumorigenic SKv-11 parental cells, SKv-12 cells displayed a significantly higher in vitro proliferative potential which correlated with their increased tumorigenic potential (Malejczyk et al, 1994). To evaluate whether the higher proliferation of SKv-I cells may be related to some stimulatory activity of sTNF-RI, both SKv-11 and SKv-12 cells were cultured in the presence of different (1) and (2) concentrations of rhsTNF-RI.…”

“…Indeed, highly tumorigenic HPV-harbouring epithelial cells have been found to be resistant to anti-proliferative activity of TGF-,B (Woodworth et al, 1990;Braun et al, 1990). Similarly, spontaneous tumorigenic progression of SKv cells was found to be associated with loss of susceptibility to autocrine TNFa-mediated growth limitation (Malejczyk et al, 1994). This phenomenon was, at least partially, related to a lowered type I TNF receptor (TNF-RI) expression, however, it could also depend on release of some TNF-cx inhibitory activity.…”

Immune Response Profiling of Patients with Anogenital Warts

“…As the epithelial cells have shown to be the producers of these cytokines except for IFN-γ, some authors have suggested the autocrine role of cytokines in growth regulation of keratinocytes infected with HPV. [36][37][38] This points to the fact that a large number of cell types possibly are contributing to the growth-inhibitory function; these cytokines are secreted by many cells like T cells, macrophages, NK cells, and others. Cell-mediated immunity to HPV had been studied by in vitro tests, 39,40 but there is much controversy regarding the significance of these tests, 41 and, in general, patients with anogenital warts were excluded from these studies.…”