Some human papillomaviruses (HPVs) such as HPV type 16 (HPV16) and HPV18 are involved in cervical carcinoma, and they can immortalize and transform keratinocytes. Endothelin-1 (ET-1) is produced in keratinocytes and has been shown to act through ETA receptors as an autocrine growth factor for keratinocytes. This study examines whether HPV16 alters the ET-1-mediated autocrine loop in human keratinocytes, providing a selective growth advantage for transformed cells. ET-1 is released in similar amounts from normal and HPV-transfected keratinocytes. All HPV-transfected cell lines express high- affinity ET(A) receptors. A two-fold increase in ET-1 binding sites is present in HPV16-immortalized keratinocytes, and this effect seems to be linked to the overexpression of mRNA for this receptor rather than to differences in the surface/internalized ratio of the receptors. ET-1 induces significant increases in [3H] thymidine incorporation and cell proliferation. Furthermore, HPV-transfected keratinocytes can proliferate in the absence of any growth factor added to the growth medium, and the ET(A) receptor antagonist BQ123 prevents this proliferation. These data suggest a new mechanism in the growth control of HPV-transformed cells mediated by the upregulation of ET-1 autocrine loop.
|Number of pages||7|
|Journal||Journal of Virology|
|Publication status||Published - 1997|
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