CELULA MADRE EN CANCER DE PROSTATA IMPLICACIONES CLINICAS Y TERAPEUTICAS

2. CELULA MADRE EN CANCER DE PROSTATA IMPLICACIONES CLINICAS Y TERAPEUTICAS Prof. Dr. L. M. Antón Aparicio Jefe Servicio Oncología Médica Complejo Hospitalario Universitario Coruña

3. SUMMARY (I) • Normal prostate gland development requires many coordinated cellular process through prostate stem cells, including epithelial proliferation, mesenchymal-epithelial interaction, ductal branching morphogenesis, and ductal canalisation. • Stem cells are defined functionally as cells that have the capacity to self-renew as well as the ability to generate differentiated cells. Stem cells can generate daughter cells identical to their mother (self-renewal) as well as produce progeny with more restricted potential (differentiation). Self-renewal is achieved by symmetrical cell division while maintaining pluripotency; and this can be modulated by extrinsic factors, transcriptional regulator, and effectors. • The regenerative capacity of prostate gland has been attributed to stem/progenitor cells within adult prostatic epithelium. It was hypothesized that the adult prostate contains stem, transit/amplifying, and postmitotic cells and that the stem cells were androgen-independent for survival.

4. SUMMARY (II) • In the normal prostateglandepitheliumexist at manystages a spectrum of cellsexpressing a continuum of differentiationmarkers, biologicalproperties, allthembeginningfromstem/progenitor cellsthroughmultipleintermediatecelltypesalongdifferentlineagestoterminallydifferentiatedcells. • Thereisnowstrongevidencethatthestemcells of manytissues reside in physicallydelineated as well as physiologicallyspecializedstructurestermedniches. Insidetheniche, stemcells are oftenquiescent; outsidetheniche, stemcellsmusteitherpossesssufficientintrinsicfactorstoovercomedifferentiationorsuccumbtoomuch of fate. Thesignalthatcontrolswhichdaughtercelloranadultstemcellremains as stemcell and whichbeginstheprocess of determinationmay be mediatedthrough a number of signallingpathwaysincludingWnt, Hedgehog (Hh), Notch, BoneMorphogenicProtein (BMP), Oct-4. • Thesignalthatcontrolswhichdaughtercell of anadultstemcellremains a stemcell and whichbegindtheprocess of determinationmaybemediatedthrough a number of signallingpathwaysincluding, Wnt, Hh, Notch, Oct-4, BMP, JAK/Stat, orothersignallingpathways.

5. PROSTATE GLAND Theprostateislocated at the base of thebladder in males, surroundingtheurethra (Cunha et al. 1987). Theglandiscomposed of tubulesthathaveanepithelialcompartmentsurroundedbystromalcellsthatincludefibroblasts, smoothmuscle, and myofibroblasts. 1. Theepitheliumconsists of twocellularcompartmentsmade up of threemophologically, functionally, and molecularlydistinctcelltypes. 1.a. Androgen-independent flat basal cells are attachedtothebasementmembrane, wheretheymaintainthe homeostasis of theorgan and expressthehigh-molecular-weightcytokeratins (CK) 5 and CK14.A subpopulation of basal cellsalsoexpressesthe p53-family-related gene p63. 1.b. Luminalcells are CK8/18-positive androgen-dependentcolumnarcellsthat lay abovethe basal layerfacingthe lumen of eachtubulewherethey secrete prostaticproteins. 1.c. Neuroendocrinecells reside largely in the basal compartment, wherethey secrete neuroendocrinepeptidessuch as synaptophysin and chromogranin A thatsupportepithelialviability (Bonkhoff 1998; Abrahmsson 1999). 1.d. A fourthpopulation of epithelialcells, namedtransit-amplifyingcells, thatcoexpress basal (CK5) and luminal (CK8) markers (Isaacs and Coffey 1989), as well as prostatestemcellantigen (PSCA) in laterstages (Tran et al. 2002).

6. ADULT PROSTATE STEM CELLS Theexistence of PrSCswasdeterminedbytheobservationthattherodentprostate can undergo up to 30 cycles of involution and regeneration in response toandrogencycling (English et al. 1987). Twoprevalentmodelshave emerged toexplainhowthesePrSCsgiverisetothedifferentcelltypes of theprostate. • The linear modelprosposesthatthePrSCs reside amongthe CK5-positive basal cells, wherethey can differentiateintothedouble-positive intermediate/transit-amplifyingpopulation and thefinallyintothe CK8-positive luminalphenotype (Isaacs and Coffey 1989; Hudson et al. 2001) • Thebranchedmodel of differentiationwheretheluminal and basal cells are in separatelineages, maintainedbyseparate progenitor cells.

7. Location of stem cells: niche.

8. Multiple growth factor and cytokins are involved in stem-niche interactions. These include SCF/Kit, SDF-1/CXCR4, Jagged/Notch, Androgen/Receptor, etc. BMP4 is expressed in stromal cells, but the type of receptor expressed in prostate stem cells is unknown. The Wnt signal is important for stem cell self-renewal, but the Wnts present in the niche are unknown. The source is true for FGF and Hh.

9. Progenitor/stem cells in embryonic urogenital sinus epithelium and adult prostate epithelium with their respective cell lineage markers.

10. Cell lineage relationships in adult prostate: basal cells (CK5/14/p63/CK19/GSTpi+/CK8/CK18-); definitive luminal cells (CK8/18+/CK5/14/p63-); embryonic-like cells co-expressing both luminal and basal cell markers (CK8/18/14/5/p63/CK19/GSTpi+).

11. Cells presents in prostate with characteristics and cell markers associated

12. Developmental proposed model that implicates the different prostate gland epithelial cells genesis from stem/progenitor cells.

13. Prostate stem cell hierarchy.

14. Prostateepithelialcellhierarchy.Thestemcells divide, giveriseto a new stemcell –selfrenewal- and more committed progenitor cells (early&late) forthefunctionalexocrine and neuroendocrinecelllineages; theexocrinelineageiscriticallydependenton DHT, and in factthispopulationrepresents >90% of allepithelialcells in theadultprostategland

15. ORIGIN OF PROSTATE CANCER CELLS If prostate cancers indeed originate from different cell types (e.g., the basal or luminal compartment), the resulting tumors might have different genetic profiles, biologic behavior, and therapeutic responses.

16. Proposed model of the cellular events associated with the initiation and progression of prostatic cancer.

17. Ontogeny of prostatecanerstemcells. In primaryhumanprostatetumoursthreeclasses can bediscriminated; thosewith a minority of cells (candidatestemcells) similar totheearly- or late progentors, and the pre-terminallydifferentiatedphenotype.

18. Hh

19. WNT

20. WNT • Wnt signaling pathways regulate a variety of processes, including cell growth, development and oncogenesis (Polakis 2000) • Wnt regulate the stability of -catenin, a Key component of Wnt signaling • A protein-protein interaction between th AR and -catenin has been identified (Yang 2002). • -catenin act as an AR coactivator, increasing AR-mediated transcription (Truica 2000). • Wnt 3 a plays an important role in androgen-mediated transcription and cell growth (Verras 2004). • Wnt 3 a induces AR activity in the absence of androgens or ehances AR activity in the presence of low concentrataions of androgens (Verras 2004) CONCLUSION AR: Wnt crosstalk adds an additional layer of complexity to the Wnt pathway´s role in prostate biology

21. Notch

22. NOTCH • Notchispart of anevolutionarilyconservedsignalingpathwaythatregulatescelldifferentiation, proliferation, angrowht (MummSkopan 2000) • Notchsignaling has beenreportedtobe a requirementfor normal murineprostate re-growth and branching (Wang et al 2004, 2006). • Notch-1 signalwasseenselectively in theepitheliumsurroundingthe lumen of thebudded ductal epithelialunits. (Shon et al 2001). • Notch-1 expressionisassociatedwith basal epithelialcells in prostate (Gluene et al, 2001). • The Notch-1 cellsappearedtocorrelatewiththepopulation of thebsalcellsduringprostaticdevelpment. (Shon et al 2001). • Notch-1 signalingmayacttorepress AR signaling (Belandia et al 2005) • Endrogenous Nothc-1 regulates PTEM tumor suppressor gene (Whelan et al 2009). • Notch-1 signaling has beenlinkedwithregulation of prostate tumor cellmotility (Scorey et al 2006). • Notch-1 signalingislost in prostateadenocarcinoma (Whelan et al 2009) CONCLUSION Notch-1 signalingmaycontributetotheaccumulation of geneticalterationsthatesult in prostatecancerthronghreduced PTEN gene expressions.

23. CROSS TALK / CROSS-REGULATION NOTCH activity inhibits prostate progenitor function ( Shahi et al 2011) • The inhibitory role of Notch signaling toward proliferation of prostate epithelial cells is via PTEN induction (Barth et al 1999) Wnt signaling results in proliferation of immature prostate progenitors (Shahi et al 2011) • The reported mechanism describe the induction of AR-mediated transcription and enhances prostate cancer cells growth (Verras et al 2004) CONCLUSIONS • The ability of Wnt pathway to promote adult stem cell proliferation and self-renewal is associated with is ability to influence the Notch signaling pathway which is upregulated as a result of Wnt pathway induction. (Reya 2003, Duncan 2005) • Wnt and Notch pathways have interrelated opposing roles on prostate progenitor cells proliferation and differentiation(Shahi et al 2011).

24. ANDROGEN RECEPTOR • Theandrogensignalingpathway, whichismainlymediatedthroughthe AR isimportantsforthe normal and neoplasticdevelopment of prostatecells (Gelmann 2002). • Multiplemechanismsbywhichprostatecancercellsprogresstoandrogen-insensitivestageshavebeenreported: AR mutations, anplification (Balk 2002). • In particular, it has beenshownthat PI3PK/AKt and PTEN regulate AR. Mediatedtranscription (Sharma 2002, Wen 2000). • Wnt and Notch are abletostimulate AR. Mediatedtranscription, havinginterrelatedopposing roles onprostate progenitor cellproliferation and differentiation (Shahi 2011).

29. Scheme showing the possible mitogenic and antiapoptotic cascades induced through the EGF–EGFR, hedgehog, Wnt and other growth factor signaling pathway elements co-localized in caveolea.

30. Scheme showing the possible oncogenic cascades involved in the stimulation of sustained growth, survival,migration and drug resistance of cancer progenitor cells.

31. STRATEGIES FOR ELIMINATIONOF CSCs IN THE PROSTATE (I) • Therapeuticstrategiestorepairoreliminatemutatedstemcells are in at theirstages, and thedangersassociatedwithtargetingstemnessremaintobeassessed. • In determiningthephenotypicdifferencesbetween normal and malignantstemcells in prostate, therewas a signaturethatcouldnotonlydifferentiatecancerfrombenign, butalsostemfrom TA cells. • Thecancerelementis more tractable, and overlapsthestem and TA compartiments: destruction of stem and TA cellswouldprovide a more lastingtherapythanjustelimination of the more differentiatedprogenycells as at present.

32. STRATEGIES FOR ELIMINATIONOF CSCs IN THE PROSTATE (II) • Thus, to target thestemcellcompartmentforelimination of theCSCswillrequire new strategies and arraysystemsthat are quite distinctformthoseusedto derive antiproliferativesthat are thecurrentlyfavored targets of thepharmaceuticalindustry. First, arrayssystemicsforcancerdrugdevelopmentrequiretheavailability of largenumbers of cells, and are currentlybasedon a selectednumber of celllinesformost tumor types. Second, becauserapidproliferationisnotnecessary in thestem-cellcompartment, theassaysrequiredforelimination of theCSCscannotbemeasuredby a slowing of growthratormetabolism. Third, thereisalsothelikelihoodthattheCSCshaveinherentresistancemechanisms.