Abstract
Human papilloma virus 16 (HPV16) is considered to be the causative agent for cervical cancer, which ranks second to breast cancer in women’s malignancies. In an attempt to develop drugs that inhibit the malignant transformation of HPV16-immortalized epithelial cells, we examined the effect of tyrphostins on such cells. We examined the effect of tyrphostins from four different families on the growth of HPV16-immortalized human keratinocytes (HF-1) cells. We found that they alter their cell cycle distribution, their morphology, and induce cell death by apoptosis. The effects of tyrphostins on HF-1 cells are different from their effects on normal keratinocytes. Growth suppression by AG555 and AG1478 is accompanied by 30% apoptosis in HF-1 cells, but this is not observed in normal keratinocytes. Tyrphostin treatment produces distinctive morphological changes in HF-1 cells and in normal keratinocytes; however, the culture organization of normal keratinocytes is less disrupted. These differential effects of the tyrphostins on HPV16-immortalized keratinocytes compared with their effects on normal keratinocytes suggests that these compounds are suitable candidates for the treatment of papilloma. Previous and present results indicate that group 1 tyrphostins, which inhibit Cdk2 activation, and group 2 tyrphostins, represented by AG1478, a potent epidermal growth factor receptor kinase inhibitor, induce cell cycle arrest; and, in the case of HF-1 cells, apoptosis and differentiation. Cells accumulate in the G1 phase of the cell cycle at the expense of S and G2 + M. These compounds block the growth of normal keratinocytes without inducing apoptosis or differentiation, causing them to accumulate in G1. AG17, which belongs to group 4, exerts its antiproliferative effect mainly by increasing the fractions of cells in G1 with a concomitant decrease in the fraction of cells in S and G2 + M.
Footnotes
-
Send reprint requests to: Hannah Ben-Bassat, Laboratory of Experimental Surgery, Hadassah University Hospital, Jerusalem 91120, Israel.
-
↵1 This study was partially supported by the German-Israeli Cooperation in Cancer Research (DKF2-MOS).
- Abbreviations:
- HPV
- human papilloma virus
- HF-1
- HPV16-immortalized human keratinocytes
- KGM
- keratinocyte growth medium
- sKGM
- starvation medium (KGM without EGF and without serum)
- DMSO
- dimethyl sulfoxide
- FACS
- fluorescence-activated cell-sorting analysis
- Received August 24, 1998.
- Accepted May 14, 1999.
- The American Society for Pharmacology and Experimental Therapeutics
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|