The Role of the Axon Guidance Molecule Slit2 in Pancreatic Cancer

The Axon Guidance Molecule Sl i t2 impairs pancreatic cancer metastasis in vivo and neural invasion in vi tro Ba ck ground a nd a im : Ea r l y d i ss em in a t i on o f pan c re a t i c duc t a l a de no car c i nom a ( PDAC) v i a vas cu la r r ou te s a nd n eur a l i n va s ion l im i t s c u ra t i ve t h e ra p y in t h i s de va s ta t ing d i s ea se , s ug g es t i ng a ce n t ra l r o l e f o r t h e i n te r ac t io n o f t um or ce l l s w i t h b lo od vess e ls a nd n e r ve s i n t he t um or s t r oma. S l i t 2 a nd i t s r e cep t o rs , Rob o1 an d Ro bo 4 , c on s t i t u t e a s ys tem o f g u id ance c ue s t ha t f un c t ion i n a xo n g u id an ce , ang iog e ne s i s a nd ep i t he l ia l m orp hog e ne s is , r e sp ec t i ve l y . Mo re re cen t l y , a t umor s up pre ssor f u nc t ion o f S l i t 2 wa s p r opo se d . Her e , we s tu d ie d t he e xp r ess ion o f S l i t 2 i n PDAC a nd i t s f unc t i on f o r t umo r g ro wth and d i ss em ina t i on . Met hods and r es u l ts : Qu an t i t a t i ve RT -PCR r e vea le d a re duc ed S l i t 2 m RNA e xpr ess ion i n sp ec ime ns o f hum an PDAC as c omp are d t o no nt ra ns f o rme d p an c re as . C l in i ca l l y , r e du ce d S l i t 2 m RNA e xpre ss ion c o r re l a te d w i t h a h ig h er in c i de nc e an d a h ig her e x t en t o f l ymp ha t i c me t as t as is . I n co n t ra s t , t he S l i t 2 r ec ep t o rs Rob o1 a nd Ro bo 4 were u n i f o rm ly p r es en t i n c l i n i ca l sam p les o f PDAC a nd h ea l t h y p anc r eas a nd d is p la yed d i f f e r en t ia l l oc a l i za t io n o n ep i t he l ia l t umor ce l l s ( Ro bo 1) a nd t umor vas cu la t u re ( Rob o4) i n immu no h i s to ch emic a l a na l yses . Mo r eo ver , pa nc r ea t i c ne r ves e xh ib i t ed s t ro ng Rob o1 immu nor ea c t i v i t y . Co ns is t en t w i t h red uc ed S l i t 2 mRNA l e ve l s in PDAC sp ec im ens , S l i t 2 wa s f ou nd s ub s ta n t ia l l y r ed uce d o r l o s t i n p oor l y d i f f e re n t ia t ed h uman PDAC ce l l l i n es , r es pe c t i ve l y . S ta b le o r i nd uc ib l e re e xp r ess ion o f S l i t 2 i n PDAC ce l l l i n es i n h ib i t e d t h e i r m ig ra t io n a nd in vas io n in t r a ns we l l a ss a ys , an e f f ec t t h a t was p r e ve n ted b y co t r ea tm en t w i t h a so lub le Ro bo 1 d eco y rec ep t o r o r a s o lub le Ro bo 1-Fc f r ag ment . Tum or ce l l d e r i ved S l i t 2 , f u r t h e rmor e , su ppr ess ed VEG Fin duc ed l ame l l i p od ia f o rmat io n , as we l l a s m ig ra t i on o f p r imar y e nd o th e l i a l ce l l s . F in a l l y , i n v i vo s t u d ies i n o r t h o to p ic hum an xe n og ra f t a nd m ou se s yng en e i c p an c re a t i c c an cer mo de l s r e vea led t ha t r e -e xp r ess ion o f S l i t 2 i n PDAC c e l l s i nh i b i t e d t umo r g ro wth , i n vas ion , me t as t as is a nd a ng iog e ne s is . Co ns is t en t l y , f un c t i o na l i nac t i va t io n o f S l i t 2 i n S l i t c omp ete n t PDAC c e l l s v ia le n t i v i r a l -me d ia t ed Rob o1 re ce p to r k nock do wn s t imu la t ed t um or ce l l m ig ra t i on i n v i t r o , an d en ha nc ed in vas ion a nd met as t as is i n v i vo . I n o r de r t o e va lua t e t he e f f ec t s o f S l i t 2 on n eur a l i n vas ion we u se d co -c u l t u r es o f t um or ce l l s w i t h d o rs a l r oo t g ang l i a ( DRGs) t o mo n i t o r PDAC ce l l mo vem ent a l ong t he con du i t p r o v i de d b y ou tg ro wing n eur i t es . I n du c t i on o f S l i t 2 i n PDAC ce l l s imp a i re d t he un id i r ec t io na l m ig ra t io n a lo ng ou tg ro w ing ne ur i t e s .