Interleukin 1 alpha and tumor necrosis factor alpha stimulate autocrine amphiregulin expression and proliferation of human papillomavirus-immortalized and carcinoma-derived cervical epithelial cells.
Infection with multiple sexually transmitted agents has been associated with inflammation of the cervix and an increased risk of cervical cancer in women infected with human papillomaviruses (HPVs). Two proinflammatory cytokines, interleukin 1 alpha (IL-1 alpha) and tumor necrosis factor alpha (TNF-alpha), inhibited proliferation of normal epithelial cells cultured from human cervix. In contrast, both cytokines significantly stimulated proliferation of cervical cell lines (5 of 7) immortalized by transfection with HPV-16 or -18 DNAs or lines derived from cervical carcinomas (7 of 11). Stimulation was dose dependent from 0.01 to 1.0 nM and was blocked by specific inhibitors, such as the IL-1 receptor antagonist or the TNF type 1 or 2 soluble receptors. Growth stimulation by IL-1 alpha or TNF-alpha was accompanied by a 6- to 10-fold increase in RNA encoding amphiregulin, an epidermal growth factor (EGF) receptor ligand. Recombinant human amphiregulin (0.1 nM) was as effective as IL-1 alpha or TNF-alpha in promoting proliferation. Monoclonal antibodies that blocked signal transduction by the EGF receptor or that neutralized amphiregulin activity prevented mitogenic stimulation by IL-1 alpha or TNF-alpha. These studies indicate that IL-1 alpha and TNF-alpha stimulate proliferation of immortal and malignant cervical epithelial cells by an EGF receptor-dependent pathway requiring autocrine stimulation by amphiregulin. Furthermore, they suggest that chronic inflammation and release of proinflammatory cytokines might provide a selective growth advantage for abnormal cervical cells in vivo.