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Inhibitory effects of (S)-1-3-(3-hydroxy-2-phosphonylmethoxypropyl1)Cytosine and 0-(1,3-dihydroxy-2-propoxymethyl)guanine on human cytomegalovirus replication and DNA synthesis
89 I n h i b i t o r y E f f e c t s of ( $ ) - l - ( 3 - H y d r o x y - 2 - P h o s p h o n y l m e t h o x y p r o p y l ) C y t o s l n e and 9 - ( l , $ - D i h y d r o x y - 2 - P r o p o x ~ n e t h y l ) C u a n l n e on Human C y t o m e g a l o v l r u s R e p l l c a t i o n and DNA S y n t h e s i s J . N e y t s , R, Snoeck, J . B a l a a r i n i and E. De C l e r c q Rage I n s t i t u t e f o r Medical R e s e a r c h , K a t h o l i e k e U n i v e r s i t e i t Leuven, Leuven, Belgium Human c y t o m e g a l o v £ r u s (CMV) i s an i m p o r t a n t p a t h o g e n , e s p e c i a l l y i n tmmunosuppressed p a t i e n t s . The o n l y d r u g which has been approved f o r t h e t r e a t m e n t o f CMV i n f e c t i o n s is 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG, g a n c i c l o v i r ) R e c e n t l y , ( $ ) - l - ( 3 - h y d r o x y - 2 - p h o s p h o n y l m e t h o x y p r o p y l ) c y t o s i n e (HPMPC) was shown t o be a p o t e n t and s e l e c t i v e i n h i b i t o r of CMV r e p l i c a t i o n i n v i t r o . We have now e v a l u a t e d t h e i n h i b i t o r y e f f e c t s of HPMPC and DHPG on v i r a l DNA s y n t h e s i s i n CMV-infected human embryonic l u n g (HEL) c e l l s . Both compounds a c h i e v e d a d o s e - d e p e n d e n t i n h i b i t i o n of CMV DNA s y n t h e s i s w i t h i n t h e c o n c e n t r a t i o n range of 0.04 t o 4 ~g/ml. At a c o n c e n t r a t i o n o f 4 ~glml, HPMPC and DXPG reduced v i r a l DNA s y n t h e s i s by 100Z nnd 96Z, r e s p e c t i v e l y . At a c o n c e n t r a t i o n o f 0.04 ~glml t h e y i n h i b i t e d v i u a l DNA s y n t h e s i s by 30Z and l e a , r e s p e c t i v e l y . A s h o r t e x p o s u r e time (from 0 t o e i t h e r 6 o r 24 h r p o s t i n f e c t i o n ) o f CMV-infected c e l l s t o HPMPC s u f f i c e d t o a f f o r d a pronounced and p r o l o n g e d i n h i b i t i o n o f v i r a l DNA s y n t h e s i s and v i r a l r e p l i c a t i o n . I n c o n t r a s t , DHPG did n o t e f f e c t more t h a n a weak and t r a n s i e n t i n h i b i t i o n o f CMV DNA s y n t h e s i s and CMV r e p l i c a t i o n a f t e r i t had been exposed t o t h e c e l l s from 0 t o e i t h e r 6 or 24 h r p o s t i n f e c t i o n . N e i t h e r DHPG n o r HPMPC i n h i b i t e d c e l l p r o l i f e r a t i o n and c e l l u l a r DNA s y n t h e s i s u n l e s s t h e y were added a t a c o n c e n t r a t i o n (100 ~ g l m l ) , t h a t i s 1 0 0 0 - f o l d h i g h e r t h a n t h e c o n c e n t r a t i o n r e q u i r e d t o i n h i b i t v i r a l DNA s y n t h e s i s .
9O H e c h a n i u l o f C e l l u l a r Uotake of Phosphonylmethoxyalkyl P u r i n a D e r i v a t i v e s
C. Pal~ 1, S. S t e f a n e l l i I , M. Rassu 1, C. P a r o l i n 1, J . B a l z a r i n i 2 and E. De C l e r c q 2 I n s t i t u t e o f M i c r o b i o l o g y , Padova U n i v e r s i t y , Padova, I t a l y 1 and Rega I n s t i t u t e f o r Medical R e s e a r c h , K a t h o l i e k e U n i v e r s i t e t t Leuven, Leuven, Belgium Cellular uptake of t r i t i u m - l a b e l l e d ($)-9- (3-hydroxy-2-phosphonyl. m e t h o x y p r o p y l ) a d e n i a e (HPMPA) and 9 - ( 2 - p h o s p h o n y l m e t h o x y e t h y l ) a d e n i n e (PMEA) was s t u d i e d i n a number o f c e l l l i n e s o f d i f f e r e n t o r i g i n , i . e . macrophage. lymphocyte, f i b r o b l a s t and e p i t h e l i a l c e l l s . The compounds showed ~ v i r t u a l l y i d e n t i c a l p a t t e r n o f p e r m e a t i o n i n a l l c e l l s , as i n d i c a t e d by k i n e t i c e x p e r i m e n t s ~rith i n h t b i t o r s o f t h e n u c l e o s i d e t r a n s p o r t s y s t e m . C e l l u l a r u p t a k e d i d n o t o c c u r v i a f a c i l i t a t e d d i f f u s i o n , as f o r n a t u r a l n u c l e o s i d e s , b u t t h r o u g h a p r o c e s s i n v o l v i n g e n d o c y t o e t s , which was t e m p e r a t u r e - d e p e n d e n t and s e n s i t i v e t o e n d o c y t o s i s i n h i b i t o r s such as sodlum a z i d e and c y t o c h a l a s i n B. Uptake was s i g n i f i c a n t l y h i g h e r i n c e l l s o f t h e macrophage t y p e t h a n i n t h e o t h e r c e l l l i n e s . The amount o f c e l l - a s s o c i a t e d d r u 8 i n c r e a s e d w i t h t i m e , u n t i l a t a b o u t 2 h r an e q u i l i b r i u m was e s t a b l i s h e d between endoand e x o c y t o s l e . At t h i s t i m e , i n t r a c e l l u l a r d r u g m o l a r i t y exceeded extracellular d r u g m o l a r i t y by two- o r t h r e e - f o l d . C e l l u l a r u p t a k e o f t h e d r u g s was i n h X b i t e d by an e x c e s s o f cold HPMPA o r PMEA, and by ssDNA, which sufj|eats th a t the endocytosia process i s of the a b so r p t i v e type. I t is prob a b l y I m d t a t e d by t h e r e c e p t o r s i t e s t h a t r e c o g n i z e n u c l e i c a c i d s based on t h e i r n e g a t i v e c h a r g e s . T h i s c o n c l u s i o n i s s u b s t a n t i a t e d by t h e o b s e r v a t i o n t h a t a s S K n i f £ c a n t p r o p o r t i o n (~ 10Z) o f t h e c e l l - a s s o c i a t e d d r u g was TCAprecipitable.
9O H e c h a n i u l o f C e l l u l a r Uotake of Phosphonylmethoxyalkyl P u r i n a D e r i v a t i v e s
C. Pal~ 1, S. S t e f a n e l l i I , M. Rassu 1, C. P a r o l i n 1, J . B a l z a r i n i 2 and E. De C l e r c q 2 I n s t i t u t e o f M i c r o b i o l o g y , Padova U n i v e r s i t y , Padova, I t a l y 1 and Rega I n s t i t u t e f o r Medical R e s e a r c h , K a t h o l i e k e U n i v e r s i t e t t Leuven, Leuven, Belgium Cellular uptake of t r i t i u m - l a b e l l e d ($)-9- (3-hydroxy-2-phosphonyl. m e t h o x y p r o p y l ) a d e n i a e (HPMPA) and 9 - ( 2 - p h o s p h o n y l m e t h o x y e t h y l ) a d e n i n e (PMEA) was s t u d i e d i n a number o f c e l l l i n e s o f d i f f e r e n t o r i g i n , i . e . macrophage. lymphocyte, f i b r o b l a s t and e p i t h e l i a l c e l l s . The compounds showed ~ v i r t u a l l y i d e n t i c a l p a t t e r n o f p e r m e a t i o n i n a l l c e l l s , as i n d i c a t e d by k i n e t i c e x p e r i m e n t s ~rith i n h t b i t o r s o f t h e n u c l e o s i d e t r a n s p o r t s y s t e m . C e l l u l a r u p t a k e d i d n o t o c c u r v i a f a c i l i t a t e d d i f f u s i o n , as f o r n a t u r a l n u c l e o s i d e s , b u t t h r o u g h a p r o c e s s i n v o l v i n g e n d o c y t o e t s , which was t e m p e r a t u r e - d e p e n d e n t and s e n s i t i v e t o e n d o c y t o s i s i n h i b i t o r s such as sodlum a z i d e and c y t o c h a l a s i n B. Uptake was s i g n i f i c a n t l y h i g h e r i n c e l l s o f t h e macrophage t y p e t h a n i n t h e o t h e r c e l l l i n e s . The amount o f c e l l - a s s o c i a t e d d r u 8 i n c r e a s e d w i t h t i m e , u n t i l a t a b o u t 2 h r an e q u i l i b r i u m was e s t a b l i s h e d between endoand e x o c y t o s l e . At t h i s t i m e , i n t r a c e l l u l a r d r u g m o l a r i t y exceeded extracellular d r u g m o l a r i t y by two- o r t h r e e - f o l d . C e l l u l a r u p t a k e o f t h e d r u g s was i n h X b i t e d by an e x c e s s o f cold HPMPA o r PMEA, and by ssDNA, which sufj|eats th a t the endocytosia process i s of the a b so r p t i v e type. I t is prob a b l y I m d t a t e d by t h e r e c e p t o r s i t e s t h a t r e c o g n i z e n u c l e i c a c i d s based on t h e i r n e g a t i v e c h a r g e s . T h i s c o n c l u s i o n i s s u b s t a n t i a t e d by t h e o b s e r v a t i o n t h a t a s S K n i f £ c a n t p r o p o r t i o n (~ 10Z) o f t h e c e l l - a s s o c i a t e d d r u g was TCAprecipitable.